JP5224048B2 - Suspension control device - Google Patents

Description

  The present invention relates to a suspension control device used in a vehicle.

In order to perform vibration control of the vehicle body, a large amount of information is required such as the vertical movement and posture of the vehicle body (pitch, roll, etc.) and the vertical relative speed between each wheel and the vehicle body. If a dedicated sensor is mounted to obtain each information, the cost of the sensor increases. Therefore, it is desirable to reduce the number of sensors as much as possible.
In order to reduce the number of sensors, for example, other values (for example, relative speed between the wheel and the vehicle body) are estimated by calculation based on a value (for example, angular velocity of the wheel) detected by a sensor used for applications other than vibration control. There is a way to do it. In this way, the number of sensors can be reduced as a whole vehicle. As a specific example, there is a suspension control device disclosed in Patent Document 1.
JP-A-8-230433

  Even in the suspension control device described in Patent Document 1, the number of sensors can be reduced, but there is still a need to reduce the number of sensors.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a suspension control device with a reduced number of sensors.

The present invention is a suspension control device that includes a damping force adjusting type shock absorber that is interposed between a vehicle body and wheels of a vehicle and whose damping characteristics change according to an external command, and a control device that controls the damping characteristics. The control device includes: first vertical motion calculation means for calculating the vertical motion of the first point set at an arbitrary position of the vehicle body; roll motion estimation means for estimating the roll motion of the vehicle body; According to the pitch motion estimation means for estimating the pitch motion of the vehicle body, the vertical motion calculation means for calculating the vertical motion of each part of the vehicle body from the vertical motion, the roll motion and the pitch motion, and the vertical motion of the respective parts and calculates a command Te, consists of a controller sending the command to the damping force adjustable shock absorber, said pitch motion estimating means detects the rotation of the wheel, when the wheel speed from the detection result A wheel speed time rate of change calculating means for calculating a change rate, and the longitudinal acceleration acquisition means for detecting or estimating the longitudinal acceleration of the vehicle body without using the rotation of the wheel,
It is characterized by comprising subtracting means for calculating the pitch rate from the difference between the wheel speed time change rate calculated by the wheel speed time change rate calculating means and the longitudinal acceleration acquired by the longitudinal acceleration acquiring means .

  According to the present invention, it is possible to provide a suspension control device with a reduced number of sensors.

Next, an embodiment of the present invention will be described.
<First Embodiment>
First, a suspension control device according to a first embodiment includes a damping force adjustment type shock absorber that is interposed between a vehicle body and a wheel and changes a damping characteristic according to a command from the outside, and a control device that controls the damping characteristic. The suspension control device comprises: a first vertical motion calculation means for calculating a vertical motion of a first point set at an arbitrary position of the vehicle body; and a roll motion of the vehicle body is estimated. Roll motion estimating means, pitch motion estimating means for estimating the pitch motion of the vehicle body, each part vertical motion calculating means for calculating the vertical motion of each part of the vehicle body from the vertical motion, the roll motion and the pitch motion, A controller that calculates a command according to the vertical motion of each part and sends the command to the damping force adjustment type shock absorber; and the pitch motion estimation means is configured to rotate the wheel. A wheel rotation calculating means for output, characterized in that it consists of a longitudinal motion calculating means, and subtraction means for calculating a pitch rate from a difference between the before and after exercise and the wheel rotation to calculate the longitudinal movement of the vehicle body.
Here, “vertical motion”, “roll motion”, and “pitch motion” refer to physical quantities relating to motion in the vertical direction, pitch direction, and roll direction, respectively, vertical displacement, roll angular velocity (roll rate), pitch angular acceleration, etc. including. “Rotation of wheel” refers to a physical quantity related to the rotational motion of the wheel, and includes angular velocity, wheel speed (angular velocity multiplied by effective wheel radius), angular acceleration, and the like. “Wheel rotation calculating means” refers to a mechanism for calculating wheel rotation, and includes a wheel speed sensor, an angle sensor, and the like. The “front-rear motion of the vehicle body” refers to a physical quantity related to the front-rear motion of the vehicle body, and includes vehicle body speed, vehicle body acceleration, and the like. “Longitudinal motion calculation means” refers to a mechanism that calculates the longitudinal motion of the vehicle body, and includes a speed sensor, an acceleration sensor, and the like.
The suspension control device according to the present embodiment may include dimension conversion means for converting the dimensions to the same when the dimension of the wheel rotation and the dimension of the longitudinal motion are different. The estimation accuracy is improved by converting the dimensions to the same before obtaining the difference between the two. Examples of such dimension conversion means include a differentiator and an integrator. Here, “dimension” means an arbitrary physical quantity expressed as a product of time (T), length (L), and mass (M). For example, acceleration is expressed as “L · M ⁻² ”.
The suspension control device according to the present embodiment may include a conversion unit that multiplies at least one of wheel rotation, body movement, and a difference between them by a predetermined coefficient. For example, when the pitch rate is obtained from the difference between the wheel speed and the vehicle body speed, this difference is a value proportional to the pitch rate and not the value of the pitch rate itself. Therefore, if this difference is multiplied by a predetermined coefficient and converted into a pitch rate, the subsequent calculation can be simplified.
Moreover, when the vehicle has a pair of wheels on the left and right sides of the vehicle body, the suspension control device of the present embodiment may use an average value of the wheel rotations of the pair of wheels as the wheel rotation. The estimation accuracy of pitch motion (for example, pitch rate) can be improved as compared with the case of using wheel rotation of only the right or left wheel.
Furthermore, when the vehicle has a pair of wheels on the left and right sides of the vehicle body, the suspension control device of the present embodiment can prevent the pitch motion from being calculated when the wheel rotations of the pair of wheels are in opposite phases. When the phase is opposite, the running road surface is rough and the estimation accuracy of the pitch motion may be reduced, so that it is possible to avoid the estimation with low accuracy.
In addition, the suspension control device of the present embodiment is configured to calculate the wheel rotation from the rotation of the driven wheel when the vehicle includes a driving wheel on which the driving force acts and a driven wheel on which the driving force does not act. Can do. Since the follower wheel is less affected by the driving force due to the fluctuation of the wheel speed, it is possible to improve the estimation accuracy of the pitch motion as compared with the configuration calculated from the rotation of the drive wheel.
The suspension control device according to the present embodiment can determine the longitudinal motion from the output of the longitudinal acceleration sensor. Since the longitudinal motion is calculated from the directly detected longitudinal acceleration, the estimation accuracy can be improved. If this longitudinal acceleration sensor is shared with other applications such as slip control, the cost can be reduced.
When the vehicle has a motor torque detecting means for detecting the torque of the prime mover, the suspension control device of the present embodiment may determine the longitudinal motion from this output. Here, the “motor” refers to a general gasoline engine, a diesel engine, an electric motor, or the like that drives a vehicle.
When various transmissions (MT, AT, CVT, etc.) are interposed between the prime mover and the wheels, the longitudinal motion may be obtained from the product of the output of the prime mover torque detection means and the total reduction ratio from the prime mover to the wheels. .
When the vehicle has a torque converter, the longitudinal motion may be obtained by multiplying a coefficient corresponding to the lock-up and slip of the torque converter. If comprised in this way, the estimation precision of a pitch motion can be improved.
The back-and-forth motion may take into account an external force (for example, air resistance) acting on the vehicle body.
In the suspension control device of the present embodiment, when the vehicle has a braking mechanism, the longitudinal motion may be obtained from the braking force generated by the braking mechanism.
When the braking mechanism is a hydraulic disc brake, the longitudinal motion can be obtained from the hydraulic pressure of the hydraulic disc brake.
An upper limit value for calculation may be set for the back-and-forth motion. This is because when the wheel is locked by braking, the estimated acceleration due to the hydraulic pressure becomes larger than the actual acceleration. Therefore, the upper limit value may be determined based on the acceleration when the braking lock occurs.
When the braking mechanism is a regenerative brake, the back-and-forth motion can be obtained from the electric power generated by the regenerative brake during braking.
Moreover, the suspension control apparatus of this embodiment may obtain | require a back-and-forth motion from the positional information on the said vehicle by GPS. For example, the speed of the vehicle is obtained from the moving distance at a predetermined time interval.
In the suspension control device according to the present embodiment, the control device may include integration means. The vertical motion calculation means calculates vertical acceleration of the point of the vehicle body, the roll motion estimation means estimates roll acceleration of the vehicle body, the pitch motion estimation means estimates pitch acceleration of the vehicle body, Each part vertical motion calculation means calculates the vertical acceleration of each part of the vehicle body from the vertical acceleration, the roll acceleration and the pitch acceleration, and the integration means calculates the vertical speed of each part by integrating the vertical acceleration of each part. The controller may be configured to calculate a command according to the vertical speed of each unit and to send the command to the damping force adjusting shock absorber. In this way, for example, when a vertical acceleration sensor is used as the vertical motion calculation means, an improvement in estimation accuracy can be expected as compared with a configuration in which the vertical speed of each part of the vehicle body is calculated using the vertical speed. This is because the output of the vertical acceleration sensor can be calculated by using it as it is without passing through a differentiator, so that an error caused by passing through the differentiator can be avoided.
In addition, the suspension control device of the present embodiment calculates a second vertical motion that calculates a vertical motion of a second point set at a position away from the first point in a warp direction that is different from the pitch direction of the vehicle body. Calculating means, and warp motion calculating means for calculating a warp motion from the vertical motion of the first point and the vertical motion of the second point, and the roll motion estimating means is based on a difference between the warp motion and the pitch motion. You may comprise so that the roll motion of the said vehicle body may be estimated. With such a configuration, for example, since the output from the vehicle height sensor mounted near the rear wheel mounted for estimating the axis irradiated by the headlight can be diverted, the number of sensors of the vehicle can be reduced. it can.
Similarly, the suspension control apparatus according to the present embodiment calculates the second up-and-down motion of the second point that is set at a position away from the first point in the warp direction that is different from the roll direction of the vehicle body. Motion calculating means, and warp motion calculating means for calculating a warp motion from the vertical motion of the first point and the vertical motion of the second point, and the pitch motion estimating means is a difference between the warp motion and the roll motion. From this, the pitch motion of the vehicle body may be estimated. With such a configuration, for example, since the output from the vehicle height sensor mounted near the rear wheel mounted for estimating the axis irradiated by the headlight can be diverted, the number of sensors of the vehicle can be reduced. it can.
Second Embodiment
Next, the suspension control device according to the second embodiment of the present invention will be described more specifically with reference to FIGS.
FIG. 1 is a perspective view schematically showing a component layout of a vehicle including a suspension control device according to a second embodiment of the present invention. FIG. 2 is a block diagram for explaining a control function of the controller of FIG. FIG. 3 is a block diagram showing the longitudinal acceleration estimation means of FIG. FIG. 4 is a block diagram for explaining a control function of the longitudinal acceleration estimation unit by the engine of FIG. FIG. 5 is a block diagram for explaining a control function of the longitudinal acceleration estimation unit based on the brake fluid pressure in FIG. FIG. 6 is a block diagram for explaining a control function of the longitudinal acceleration estimation unit based on the air resistance of FIG.

1 and 2, the suspension control apparatus 1 according to the first embodiment is applied to a vehicle 2 in which the drive system is rear wheel drive (front engine / rear drive (FR)) and the transmission is AT (automatic transmission). Used. A damping force adjusting buffer (hereinafter also referred to as a shock absorber as appropriate) 4FL, 4FR, 4RL, 4RR is attached to each wheel [front left and right wheels 3FL, 3FR, rear left and right wheels 3RL, 3RR] of the vehicle 2. ing. The vehicle 2 of the present embodiment is driven by rear wheels, and the front left and right wheels 3FL and 3FR are driven wheels. And, the front left and right wheels 3FL, 3FR (driven wheels) are more susceptible to changes in the wheel speed due to the pitch motion than the rear wheels connected to the power train. In the present embodiment, shock absorbers 4FL, 4FR, 4RL, 4RR (hereinafter collectively referred to as shock absorber 4 as appropriate) constitute a suspension mechanism.
A spring 5 is attached to the outer periphery of the shock absorber 4. The wheels (front left and right wheels 3FL and 3FR, rear left and right wheels 3RL and 3RR) are hereinafter collectively referred to as wheels (also referred to as tires as appropriate) 3 as appropriate.
The spring 5 is provided between the vehicle body 6 and each wheel 3 and supports the vehicle body 6.

The vehicle 2 is provided with a CAN (Controller Area Network), and wheel speed sensors 7FL and 7FR for the front two wheels (front left and right wheels 3FL and 3FR) provided as an existing vehicle 2 are provided. Each signal from various detection means (vehicle speed detection means, engine torque detection means, gear position detection means, hydraulic pressure detection means) (not shown) is input to the control device 8 via CAN.
Each of the signals from the various detection means (or information), the various pre-output from the detection means the left and right wheels 3FL, wheel speeds vc _FL of 3FR, vc _FR, the vehicle speed [nu, engine torque T _e, the gear position P _g a signal indicating a brake master cylinder pressure P _m (or information). About this signal (or information), it shows with the code | symbol which shows the content suitably. For example, a vehicle speed signal ν (or vehicle speed information ν) and an engine torque signal _Te (engine torque information _Te ) are displayed. Including the signals (or information) indicating the wheel speeds vc _FL and vc _FR , other signals (or information) described later are displayed in the same manner.

The control device 8 executes arithmetic processing to be described later based on a predetermined control program, outputs a control command value obtained by using the input data in the arithmetic processing, and attenuates the shock absorber 4 Control the force characteristics.
In this embodiment, as will be described later, the longitudinal acceleration of the vehicle body 6 is estimated using a signal that can be acquired from CAN. Therefore, it is not necessary to install a dedicated sensor, and the cost can be reduced.

Next, the configuration of the control device 8 and the contents of the calculation process will be described with reference to FIGS.
As shown in FIG. 2, the control device 8 determines the pitch rate from the longitudinal acceleration estimation means 20 (longitudinal acceleration acquisition means) , the pitch rate estimation means 21, and the pitch rate estimation means 21, which is an example of the longitudinal motion calculation means. The control command calculation means 22 is configured to generate the control command value based on the output and output the control command value to the shock absorber 4.
Instead of the longitudinal acceleration estimation means 20, a longitudinal acceleration sensor that detects longitudinal acceleration may be used. When the longitudinal acceleration sensor is mounted on the vehicle 2, the output value can be used through CAN.

As shown in FIGS. 2 and 3, the longitudinal acceleration estimation means 20 includes an engine longitudinal acceleration estimation unit (hereinafter referred to as an engine-derived longitudinal acceleration estimation unit) 25 and a longitudinal acceleration estimation unit based on the brake master cylinder hydraulic pressure P _m. (Hereinafter referred to as hydraulic pressure-induced longitudinal acceleration estimation unit) 26, longitudinal resistance estimation unit based on air resistance (hereinafter referred to as air resistance-induced longitudinal acceleration estimation unit) 27, and first and second addition units 28, 29 The estimated longitudinal acceleration switching unit 30 is provided, and the longitudinal acceleration of the vehicle body 6 is estimated based on the vehicle speed ν, the engine torque _Te , the gear position P _g , and the brake master cylinder hydraulic pressure P _m as will be described later. To do. The longitudinal acceleration obtained by this estimation is hereinafter referred to as estimated longitudinal acceleration a _es for convenience. The estimated longitudinal acceleration a _es is input to the pitch rate estimating means 21.

The pitch rate estimating means 21 includes a wheel speed time change rate calculating means 31 and a calculating means 32. The wheel speed time change rate calculating means 31 receives wheel speed input from the wheel speed sensors 7FL, 7FR of the front left and right wheels 3FL, 3FR (driven wheels), and the wheel speed sensors 7FL, 7FR of the front left and right wheels 3FL, 3FR. An average value [(vc _FL + vc _FR ) / 2] of the speeds vc _FL and vc _FR is obtained, and a time change rate of the average value (hereinafter referred to as a wheel speed time change rate). ] Is calculated (estimated). The wheel speed time change rate calculating means 31 is a differentiator, and obtains the time change rate by performing a differentiation process on the wheel speeds of the wheel speed sensors 7FL and 7FR. The wheel speed time change rate calculating means 31 constitutes a dimension converting means in the present invention.
In calculating (estimating) the wheel speed time change rate, the time change rates of the wheel speeds vc _FL and vc _FR may be calculated, and the average value may be obtained as the wheel speed time change rate. The wheel speed time change rate may be obtained from only one wheel. In this case, the calculation load is reduced.

The calculation means 32 subtracts the estimated longitudinal acceleration a _es output from the longitudinal acceleration estimation means 20 from the wheel speed time change rate [wheel speed time change rate−estimated longitudinal acceleration a _es ], and integrates the data obtained by this subtraction. The pitch rate is obtained, and this is output to the control command calculation means 22.
Since the effect of acceleration / deceleration of the vehicle body 6 by the engine or brake is canceled by performing the subtraction process of “wheel speed time change rate−estimated longitudinal acceleration a _es ”, Therefore, the pitch motion of the vehicle 2 can always be estimated, and good vibration suppression control can be performed.

In addition, since the pitch motion of the vehicle 2 can be always estimated regardless of the rapid acceleration / deceleration of the vehicle body 6, the pitch of the vehicle 2 is effectively controlled by controlling the damping coefficient of the shock absorber 4 according to the pitch motion. Can be suppressed.
In addition, since the influence of the acceleration / deceleration of the vehicle body 6 is canceled, the pitch rate estimation means 21 can improve the estimation accuracy of the pitch rate.
If longitudinal acceleration cannot be obtained from the CAN (vehicle network), the longitudinal acceleration is estimated using various signals obtained from the ECU of another system through CAN, and the cost is increased by subtracting the longitudinal acceleration from the wheel acceleration. In addition, the pitch motion of the vehicle 2 can be estimated regardless of the acceleration / deceleration effect of the vehicle body 6 caused by the engine or the brake.

  The pitch rate estimating means 21 calculates the pitch rate using the wheel speed sensors 7FL and 7FR of the front left and right wheels 3FL and 3FR, that is, the wheel speeds of the driven wheels. For this reason, unlike the case of using the wheel speed of the rear wheel (drive wheel) connected to the power train, the change in the wheel speed accompanying the pitch motion can be grasped more significantly, and the calculation accuracy is improved. Accordingly, it is possible to improve the control accuracy of vibration suppression.

In the engine due longitudinal acceleration estimating unit 25, the engine torque T _e and the gear position P _g obtained through the CAN, the longitudinal acceleration by the engine (hereinafter, referred to as engine due longitudinal acceleration.) Is calculated a _eg.
The hydraulic pressure-induced longitudinal acceleration estimator 26 calculates the longitudinal acceleration due to the brake (hereinafter referred to as brake-induced longitudinal acceleration) a _{bk based} on the brake master cylinder pressure P _m obtained via CAN.
The air resistance-induced longitudinal acceleration estimation unit 27 calculates a longitudinal acceleration due to air resistance (hereinafter referred to as air resistance-induced longitudinal acceleration) a _ar from the vehicle speed ν obtained via CAN.

The first adder 28 adds the air resistance-induced longitudinal acceleration a _ar and the brake-induced longitudinal acceleration a _bk and outputs the result to the second adder 29. The second adder 29 adds the output data (a _ar + a _bk ) of the first adder 28 and the engine-derived longitudinal acceleration a _eg , and sums the data (a _ar + a _bk + a _eg ) obtained by this addition. The acceleration a _to is output to the estimated longitudinal acceleration switching unit 30.
The estimated longitudinal acceleration switching unit 30 determines whether the vehicle speed ν is 0 km / h or greater than 0 km / h, and if it is determined that the vehicle speed ν is 0 km / h, the estimated longitudinal acceleration a _es Is set to 0 [m / s ² ], and this is output to the pitch rate estimating means 21. If it is determined that the vehicle speed ν is greater than 0 km / h, the total longitudinal acceleration a _to from the second adder 29 is set as the estimated longitudinal acceleration a _es , and this is output to the pitch rate estimating means 21. .

As shown in FIG. 4, the engine-induced longitudinal acceleration estimation unit 25 includes an AT reduction ratio calculation means 34, a final reduction ratio integration unit 35, a tire radius division unit 36, a power transmission efficiency multiplication unit 37, and a vehicle body mass division unit. 38. When the engine rotation is transmitted to the driving wheels, the engine-induced longitudinal acceleration estimation unit 25 generally represents the driving force on the outer periphery of the driving wheels by the following equation (1) and further considers the mass of the vehicle body. Accordingly, the longitudinal acceleration caused by the engine drive, that is, the longitudinal acceleration caused by the engine, is calculated using the expression (2) to calculate the longitudinal acceleration a _eg caused by the engine.
A method of calculating the engine-derived longitudinal acceleration a _eg will be described below.
That is, the driving force P [N] on the outer periphery of the driving wheel is generally expressed by the following equation (1).

P = i * _nt * _Te / _Rt [N] (1)
i: Total reduction ratio _nt : Power transmission efficiency _Te : Engine torque [Nm]
R _t : radius of tire (wheel 3) [m]

Therefore, if the driving force P is calculated from the above equation (1) and the vehicle body mass m [Kg] is taken into consideration, the engine-induced longitudinal acceleration a _eg [m / s ² ] can be obtained from the following equation (2).

a _eg = P / m [m / s ² ] (2)

Using the fact that the engine-derived longitudinal acceleration a _eg is obtained by the above equation (2), the engine-derived longitudinal acceleration estimation unit 25 calculates the engine-induced longitudinal acceleration a _eg as shown in FIG.
That is, the engine due longitudinal acceleration estimating unit 25, first, AT speed reduction ratio calculating unit 34 in response to a gear position signal P _g from CAN, multiplied by the reduction ratio in the engine torque signal T _e, the final reduction of these products The result is output to the ratio integrating unit 35.
The final reduction ratio multiplication unit 35 multiplies the output data of the engine-induced longitudinal acceleration estimation unit 25 by the final reduction ratio _if and outputs the result to the tire radius division unit 36.
The tire radius division unit 36 divides the output data of the final reduction ratio integration unit 35 by the tire radius R _t [m] (in other words, multiplies by 1 / R _t ), and the driving force (driving force [N ] = Torque [Nm] / tire radius [m]) is calculated and output to the power transmission efficiency multiplier 37.
The power transmission efficiency multiplication unit 37 multiplies the driving force by the power transmission efficiency n _t and outputs this to the vehicle body mass division unit 38.
The vehicle body mass division unit 38 divides the output data of the tire radius division unit 36 by the vehicle body mass m [Kg] (in other words, multiplies by 1 / m) to obtain the engine-induced longitudinal acceleration a _eg .

The hydraulic pressure-induced longitudinal acceleration estimation unit 26 includes an acceleration / hydraulic pressure conversion gain multiplication unit 40 and a MAX limiting unit 41, as shown in FIG.
Then, the hydraulic pressure-induced longitudinal acceleration estimation unit 26 indicates that the braking force B of the vehicle 2 equipped with a disc brake is generally expressed by the following equation (3), and that the master cylinder hydraulic pressure P _m can be detected. Then, the brake-induced longitudinal acceleration a _bk is calculated by using the fact that the calculation can be omitted by Expression (4).
A method for calculating the brake-induced longitudinal acceleration a _bk will be described below.
That is, the braking force B of the vehicle 2 having a disc brake is generally expressed by the following equation (3).

B = (2 μ × A _w × F × K × r) / (R _t × A _m ) (3)
B: Brake force [N]
μ: Coefficient of friction between disk rotor and pad A _w : Cross-sectional area of wheel cylinder [m ² ]
F: pedaling force [N]
K: Brake pedal ratio r: Effective radius of disk rotor [m]
R _t : Effective radius of tire [m]
A _m : Master cylinder cross-sectional area [m ² ]

Although the braking force can be calculated by the above equation (3), if the master cylinder hydraulic pressure P _m can be detected here, the calculation can be omitted by the following equation (4).
B = P _m × C (4)
B: Brake force [N]
P _m : Master cylinder hydraulic pressure P _m [Pa]
C: Constant [N / Pa]

Therefore, when the braking force is calculated from the above equation (4) and the vehicle body mass is taken into consideration, the longitudinal acceleration a _bk [m / s ² ] in the influence of the braking force can be obtained by the following equation (5).
a _bk = B / m [m / s ² ] (5)

Using the fact that the longitudinal acceleration a _bk in the influence of the braking force is obtained as shown in the above formula (5), the hydraulic pressure-induced longitudinal acceleration estimation unit 26 performs the longitudinal acceleration in the influence of the braking force as shown in FIG. a _bk is calculated.
That is, as shown in FIG. 5, the hydraulic pressure-induced longitudinal acceleration estimation unit 26, first, the acceleration / hydraulic pressure conversion gain multiplication unit 40 adds the acceleration / hydraulic pressure conversion gain to the master cylinder brake hydraulic pressure signal P _m from CAN. And the data obtained by this multiplication is output to the MAX limiter 41. The MAX limiter 41 sets an upper limit value with 1.2 G as a maximum value that can be realistically generated, considering that the actual acceleration is less than the estimated acceleration in the case of a wheel lock. Then, the MAX restriction unit 41 obtains the brake-induced longitudinal acceleration a _bk so as to restrict the output data of the acceleration / hydraulic pressure conversion gain multiplication unit 40 with the upper limit value.

As shown in FIG. 6, the air resistance-induced longitudinal acceleration estimation unit 27 includes a multiplication circuit 43, a gain multiplication unit 44, an air density multiplication unit 45, a front projection area multiplication unit 46, an air drag coefficient multiplication unit 47, a mass division. A portion 48 is provided.
The air resistance-induced longitudinal acceleration estimator 27 determines that the aerodynamic force and the moment are proportional to the square of the front projection area and the speed of the vehicle body 6 and have different sizes depending on the shape of the vehicle body 6. Is expressed by equation (6), and further, taking into account the mass of the vehicle body, the longitudinal acceleration a _ar in the drag effect due to the air resistance can be obtained by the following equation (7). Calculate _ar .
A method for calculating the air resistance-induced longitudinal acceleration a _ar will be described below.
That is, the drag due to air resistance is expressed by the following equation (6).

F _x = C _x · (1/2) · d _A ν ² S (6)
Fx: Drag due to air resistance [N]
S: Projection area [m ² ]
ν: Vehicle speed ν (atmospheric relative speed) [m / s]
d _A : Air density [Kg / m ³ ]
C _x : drag coefficient (air resistance coefficient)

Therefore, if the drag Fx [N] due to air resistance is calculated from the above and the vehicle body mass m [Kg] is taken into account, the longitudinal acceleration due to the drag effect due to the air resistance (air resistance-induced longitudinal acceleration a _ar [m / s ² ]) It can obtain | require by following Formula (7).
a _ar = Fx / m [m / s ² ] (7)

By utilizing the fact that the air resistance-induced longitudinal acceleration a _ar is obtained as shown in the above equation (7), the air resistance-induced longitudinal acceleration estimation unit 27 first causes the multiplication circuit 43 to perform CAN as shown in FIG. The data v of the vehicle speed signal ν from the square is squared, and the data obtained by the square process is output to the gain multiplier 44. The gain multiplication unit 44 multiplies the output data of the multiplication circuit 43 by a gain (1/2), and outputs the data obtained by this multiplication to the air density multiplication unit 45. The air density multiplier 45 multiplies the output data of the gain multiplier 44 by the air density d _A and outputs the data obtained by this multiplication to the front projection area multiplier 46. The front projection area multiplication unit 46 multiplies the output data of the air density multiplication unit 45 by the front projection area S and outputs the data obtained by this multiplication to the air drag coefficient multiplication unit 47. Air drag coefficient multiplying unit 47 multiplies the drag coefficient C _x to output data of the front projection area multiplying unit 46, and outputs the data obtained by this multiplication to the mass dividing unit 48. The mass dividing unit 48 calculates the air resistance-induced longitudinal acceleration a _ar by dividing the output data of the air drag coefficient multiplying unit 47 by the mass m.

In the above embodiment, the pitch rate estimation means 21 is used to calculate the pitch rate, and the vibration of the vehicle 2 is suppressed using the calculated pitch rate. Since the pitch rate estimation means 21 estimates the pitch rate for generating the control command value in consideration of acceleration / deceleration, the pitch rate can be estimated with high accuracy as described above. The suspension control device 1 can control the vibration suppression of the vehicle 2 with high accuracy.
Furthermore, since the pitch rate estimation by the pitch rate estimation means 21 is performed using the wheel speeds of the driven wheels (front left and right wheels 3FL, 3FR), the wheel speed associated with the pitch motion is compared with the case where the wheel speed of the driving wheel is used. Can be recognized more remarkably, and calculation accuracy is improved. Thereby, the suspension control apparatus 1 can improve the control accuracy of vibration suppression.
Furthermore, the calculating means 32 cancels the influence of the acceleration / deceleration of the vehicle body 6 by the engine or the brake by performing a process of subtracting the estimated longitudinal acceleration a _es from the wheel speed time change rate. As a result, regardless of the acceleration / deceleration effect of the vehicle body 6 caused by the engine or the brake, the pitch motion of the vehicle 2 can always be estimated, and good vibration suppression control can be performed.
Further, although the target of the subtraction processing is acceleration, it is possible to target another dimension of motion, for example, wheel speed and vehicle body longitudinal speed.

In the above embodiment, the suspension control device 1 is used for the vehicle 2 whose transmission is AT, and the AT reduction ratio calculation unit 34 correspondingly calculates the reduction ratio. However, the present invention is not limited to this. It may be used for the vehicle 2 in which the transmission is MT (manual transmission), and instead of the AT reduction ratio calculation means 34, a reduction ratio calculation means corresponding to MT may be provided. Further, the transmission may be used for the vehicle 2 having a CVT (Continuously Variable Transmission), and a reduction ratio calculation unit corresponding to the CVT may be provided instead of the AT reduction ratio calculation unit 34.
Further, the reduction ratio may be calculated in consideration of the efficiency (slip) of the torque converter or the like. In this case, the calculation accuracy of the reduction ratio can be improved.
In the case of a hybrid vehicle or an electric vehicle, the longitudinal acceleration can be similarly estimated by using the sum of the engine and motor torque or the motor torque instead of the engine torque.

  In the above embodiment, when the time change rate of the wheel speed of the left and right wheels 3 is in the opposite phase, it is determined that the traveling road is a bad road and the calculation process of the wheel speed time change rate calculation means 31 is stopped. You may comprise. According to this configuration, unnecessary control can be suppressed.

In the above embodiment, when the longitudinal acceleration estimating means 20 estimates the estimated longitudinal acceleration a _es , information related to slip and lockup of the torque converter may be used. According to this configuration, the estimation accuracy can be further improved.
In the above embodiment, the longitudinal acceleration estimating means 20 (longitudinal acceleration calculating means) is obtained by using the vehicle speed ν, engine torque _Te , gear position P _g , and master cylinder hydraulic pressure P _m information obtained via CAN. However, instead of the above information, the longitudinal motion may be calculated based on a positional change by GPS. For example, the average speed can be calculated by measuring the position of the vehicle at a predetermined time interval during traveling. By subtracting this from the wheel speed, the fluctuation of the wheel speed, that is, the pitch rate can be calculated.

In the above embodiment, the longitudinal acceleration estimating means 20 that estimates the longitudinal acceleration of the vehicle body 6 based on the vehicle speed ν obtained via the CAN, the engine torque _Te , the gear position P _g , and the brake master cylinder hydraulic pressure P _m is provided. Although the case where it is provided is taken as an example, the longitudinal acceleration acting on the vehicle body 6 is directly detected, such as a semiconductor acceleration sensor, a strain gauge acceleration sensor, or a piezoelectric acceleration sensor, instead of the longitudinal acceleration estimating means 20. An acceleration sensor may be used. According to this configuration, since the longitudinal acceleration is directly measured, the pitch rate estimation accuracy can be further improved.

  In the above embodiment, in the longitudinal acceleration calculation process performed by the longitudinal acceleration estimation means 20, the calculation process is performed in consideration of the influence of external force due to the wind pressure acting on the vehicle 2, the inclination of the vehicle body 6, the gradient of the traveling road, and the like. It may be configured to do. By configuring in this way, it is possible to calculate the longitudinal acceleration in a state reflecting the running state, and thus to suppress the vibration of the vehicle 2 in a form closer to the actual use state, thereby improving the accuracy of the vibration suppression control. Can do.

<Third Embodiment>
As shown in FIG. 7, instead of the control device 8 of the above embodiment, the pitch rate estimating means 21 of the above embodiment is provided, and the vertical acceleration estimating means for estimating the vertical acceleration of the vehicle body 6 (first vertical motion calculation). Means) 51, roll rate calculating means (roll motion estimating means) 52 for calculating (estimating) the roll rate of the vehicle body 6, and vertical movement for calculating the vertical movement of each part of the vehicle body 6 from the vertical acceleration, roll rate and pitch rate. The controller 8A may be configured by including the motion calculation means 53 and the controller 54 that sends a predetermined command to the shock absorber 4 from the calculated vertical movement.

  According to the third embodiment, the pitch rate calculating means 21 calculates the pitch rate with high accuracy as described in the second embodiment, and the vertical motion calculating means 53 is obtained by the pitch rate calculating means 21. From the pitch rate, the vertical acceleration from the vertical acceleration estimating means 51, and the roll rate from the roll rate calculating means 52, the vertical movement of each part of the vehicle body 6 is calculated to obtain a vertical movement signal. The controller 54 generates a control command value corresponding to the up-and-down motion signal, and inputs the control command value to the shock absorber 4 to control damping force and thus vibration suppression.

  As described above, since the pitch rate used for command generation used for vibration suppression control is calculated with high accuracy, the control accuracy of vibration suppression of the vehicle 2 can be improved. Further, since the control command value including the vertical acceleration and the roll rate is calculated with respect to the pitch rate used for command generation, the calculation of the control command value affects the vertical acceleration and roll rate acting on the vehicle 2. The calculation accuracy is improved by taking into account the influence of the above, and as a result, the control accuracy of the vibration suppression of the vehicle 2 can be further improved.

<Fourth embodiment>
Instead of the vertical acceleration estimating means 51 and the roll rate calculating means 52 for calculating (estimating) the roll rate of the vehicle body 6 used in the second embodiment, as shown in FIG. The first vertical acceleration calculating means 61 for calculating the vertical acceleration of the vehicle body and the second vertical acceleration calculating means 62 for calculating the vertical acceleration of the second point of the vehicle body 6 are provided. Instead of the vertical motion calculating means 53 for calculating the vertical motion of each part of the vehicle body 6, a vertical motion calculating means 53A for calculating the vertical motion of each part of the vehicle body 6 from the vertical acceleration and pitch rate of the first and second points. It may be provided to constitute the control device 8B.

  According to the fourth embodiment, the pitch rate calculating means 21 calculates the pitch rate with high accuracy as described above, and the vertical motion calculating means 53A is obtained by the vehicle body 6 obtained by the first vertical acceleration calculating means 61. The vertical motion of each part of the vehicle body 6 is calculated from the vertical acceleration of the first point of the vehicle and the vertical acceleration of the second point of the vehicle body 6 obtained by the second vertical acceleration calculation means 62 to obtain a vertical motion signal, The vertical movement signal is output to the controller 54, and the controller 54 generates a control command value corresponding to the vertical movement signal, and inputs the control command value to the shock absorber 4 to control the damping force and hence the vibration suppression.

  As described above, since the pitch rate used for command generation used for vibration suppression control is calculated with high accuracy, the control accuracy of vibration suppression of the vehicle 2 can be improved. Further, since the control command value is calculated including the vertical accelerations of the first and second points with respect to the pitch rate used for command generation, the calculation of the control command value is performed on the vehicle 2 by the first and second. The calculation accuracy is improved by taking into account the influence of the vertical acceleration at two points, and as a result, the control accuracy of vibration suppression of the vehicle 2 can be further improved.

Hereinafter, the fourth embodiment of the present invention will be described in more detail with reference to FIGS.
FIG. 9 is a diagram schematically illustrating an automobile 101 in which the suspension control device according to the fourth embodiment is employed. In FIG. 9, a damping force variable shock absorber (hereinafter referred to as a shock absorber) 103 is provided corresponding to each wheel 102 (only the right front wheel 102FR and the right rear wheel 102RR are shown) of the automobile 101. Yes. The shock absorber 103 is also referred to as a shock absorber 103FR, 103RR, 103FL, 103RL for the right front wheel, the right rear wheel, the left front wheel, and the left rear wheel for convenience, corresponding to each wheel. Signals such as the sprung speed and the sprung relative speed and various members will be described below as appropriate for the shock absorber 103 corresponding to each wheel 102 as appropriate.
A spring 104 is attached to the outer periphery of the shock absorber 103. The shock absorber 103 and the spring 104 are interposed between the vehicle body 105 and each wheel 102 and have a function of damping the vertical movement of each wheel 102. A sprung acceleration sensor 107 (sprung motion detection means) that detects vertical acceleration (sprung vertical motion) acting on the vehicle body 105 corresponding to the right front wheel 102FR is attached to the vehicle body 105. A longitudinal acceleration sensor 108 that detects longitudinal acceleration acting on the vehicle body 105 is attached to the vehicle body 105. Further, a vehicle height sensor 110 that detects the vehicle height level of the automobile 101 is attached to a portion corresponding to the left rear wheel 102RL (not shown) of the vehicle body 105 (hereinafter referred to as a vehicle body left rear wheel portion). Further, the automobile 101 includes a wheel speed sensor 111 that detects the rotational speed of the left and right front wheels 102FL and 102FR (only the right front wheel 102FR is shown) (hereinafter, the wheel speed sensor 111FR corresponding to the left and right front wheels 102FL and 102FR, 111FL) is also provided.
The vehicle height sensor 110 is combined with a sprung speed estimation circuit 115, which will be described later, and constitutes a sprung motion detection means of the present invention.

  A controller (control means) 112 is connected to the sprung acceleration sensor 107, the longitudinal acceleration sensor 108, the vehicle height sensor 110, and the wheel speed sensor 111. The controller 112 receives input of information from each connection member, and based on the arithmetic processing described later, the pitch motion, warp motion, roll motion, bounce motion of the vehicle body 105, and the vertical speed at each wheel position (hereinafter referred to as this speed). Corresponds to the sprung motion of the invention and is called the sprung speed v. The sprung speeds vFR, vRR, vFL, vRL of the right front wheel part, right rear wheel part, left front wheel part, left rear wheel part of the vehicle body And relative speeds vs. each wheel 102 and the vehicle body 105 (hereinafter referred to as relative speeds vsFR, vsRR, vsFL, vsRL of the wheels (right front wheel, right rear wheel, left front wheel, left rear wheel)) Sometimes it is true. ], A control command value (damping force command value) based on the skyhook control theory is calculated based on these calculation results, and the shock absorber 103 is controlled.

As shown in FIG. 10, the controller 112 includes an integration circuit 114, a sprung speed estimation circuit 115 including an observer, a warp calculation unit 116, a pitch estimation unit 117, a roll calculation unit 118, a bounce estimation unit 119, and an observer. A front wheel relative speed estimation unit 120, a differentiation circuit 121, a rear wheel relative speed estimation unit 122 composed of an observer, and a skyhook control unit 123.
The integration circuit 114 integrates the acceleration (sprung acceleration) αFR of the right front wheel portion of the vehicle body detected by the sprung acceleration sensor 107 to calculate the absolute vertical speed (sprung velocity) vFR of the right front wheel portion of the vehicle body. The data is input to the bounce estimation unit 119 and the warp calculation unit 116. Note that the acceleration (sprung acceleration) αFR of the vehicle body right front wheel detected by the sprung acceleration sensor 107 is input to the front wheel relative speed estimation unit 120.

  The sprung speed estimation circuit 115 receives the vehicle height of the left rear wheel portion detected by the vehicle height sensor 110, performs a simulation using a predetermined model, and calculates the absolute vertical speed ( The sprung speed) vRL is estimated, and the estimated data is input to the warp calculating unit 116 and the bounce estimating unit 119. The differentiation circuit 121 is connected to the vehicle height sensor 110, the detection data of the vehicle height sensor 110 is differentiated to calculate the relative speed vsRL of the left rear wheel, and the calculated data is used as the rear wheel relative speed estimation unit. Input to 122.

The warp calculation unit 116 calculates the warp wp by taking the difference between the sprung speed vFR of the right front wheel of the vehicle body from the integration circuit 114 and the sprung speed vRL of the left rear wheel of the vehicle body from the sprung speed estimation circuit 115, Calculation data (warp wp) is input to the roll calculation unit 118.
The pitch estimation unit 117 estimates the pitch rate pt using the wheel speeds of the left and right front wheels 102FL and 102FR detected by the wheel speed sensors 111FR and 111FL and the longitudinal acceleration detected by the longitudinal acceleration sensor 108, and estimates data (pitch rate pt). Is input to the roll calculator 118 and the skyhook controller 123.
The roll calculation unit 118 calculates the roll rate rol by taking these differences from the calculation results of the warp calculation unit 116 and the pitch estimation unit 117, and calculates the calculated data (roll rate rol) as the bounce estimation unit 119 and the front wheel relative speed estimation unit. 120, the rear wheel relative speed estimation unit 122, and the skyhook control unit 123.
The bounce estimation unit 119 includes the sprung speed vFR of the right front wheel of the vehicle body obtained by the integration circuit 114, the sprung speed vRL of the left rear wheel of the vehicle obtained by the sprung speed estimation circuit 115, and the roll obtained by the roll calculation unit 118. From the rate rol, the sprung speed (vFR, vRL, vFL, vRR) at each wheel position is obtained, and the obtained data is sent to the front wheel relative speed estimation unit 120, the rear wheel relative speed estimation unit 122, and the skyhook control unit 123. input.

The front wheel relative speed estimation unit 120 detects the sprung acceleration αFR of the right front wheel of the vehicle body detected by the sprung acceleration sensor 107, and the sprung speeds (vFR, vRL, vFL, vRR) at the respective wheel positions obtained by the bounce estimation unit 119. The input data (the acceleration of the right front wheel of the vehicle body, the roll rate rol calculated by the roll calculation unit 118, and the damping force command value output by the skyhook control unit 123 are input, and a simulation is performed using a predetermined model. To estimate the relative speed between the left and right front wheels 102FL, 102FR and the vehicle body 105 (relative speed of the left and right front wheels 102FL, 102FR) vsFL, vsFR, using the sprung acceleration αFR of the right front wheel of the vehicle body, and the estimated data Is input to the skyhook control unit 123.
The rear wheel relative speed estimation unit 122 calculates the relative speed vsRL of the left rear wheel calculated by the differentiation circuit 121, the roll rate rol calculated by the roll calculation unit 118, and the sprung speed at each wheel position obtained by the bounce estimation unit 119 ( vFR, vRL, vFL, vRR) and a damping force command value output from the skyhook control unit 123, and by performing a simulation using a predetermined model, the relative of the left rear wheel from the differentiation circuit 121 is obtained. Using the speed vsRL, the relative speed between the left and right rear wheels 102RL and 102RR and the vehicle body 105 (the relative speed of the left and right rear wheels 102RL and 102RR) vsRL and vsRR is estimated, and the estimated data is input to the skyhook control unit 123. .

  The skyhook control unit 123 uses the sprung speed at each wheel position and the relative speed between each wheel 102 and the vehicle body 105 based on a predetermined skyhook control theory to attenuate the shock absorber 103 corresponding to each wheel 102. A force command value is generated to control the shock absorber 103. The damping force command value is fed back to the front wheel relative speed estimation unit 120 and the rear wheel relative speed estimation unit 122 and used for simulation.

Next, the above components of the controller 112 will be further described.
As shown in FIG. 11, the sprung speed estimation circuit 115 includes a variable damping force calculation unit 130 and a Kalman filter 131 (observer) to which modern control theory is applied, and is detected by the vehicle height sensor 110 as described above. The vehicle height is input to the left rear wheel portion of the vehicle body, and a simulation is performed using a predetermined model to estimate the absolute vertical speed (absolute speed on the spring) of the left rear wheel portion of the vehicle body. The damping force variable amount calculation unit 130 receives the control command value to the right rear wheel shock absorber 103RR and the calculation data of the Kalman filter 131 (relative speed vsRL of the left rear wheel portion), calculates the damping force variable amount, Input to the Kalman filter 131. Here, the calculated value of the Kalman filter is used as the relative speed, but the vehicle height sensor detection value may be differentiated.
The Kalman filter 131 is designed as follows.
That is, first, as shown in FIG. 12, the vertical movement of the vehicle body 105 is modeled. FIG. 12 shows, as an example, a ¼ vehicle body model in which the vertical vibration of the vehicle body 105 is modeled with one degree of freedom. 12, the absolute vertical displacement of the vehicle body 105 is Z _b , the unsprung absolute vertical displacement is Z ₀ , the spring constant is k, the damping coefficient is c, the external force acting on the vehicle body 105 is f, and the mass of the vehicle body 105 is m. It is said.

ここで、相対変位を可観測出力とするため、状態変数としてばね上とばね下の相対変位ｚ₂₀、ばね上の絶対速度ｚ_bとして式（２）とおくと、状態方程式は、式（３）となる。
ｚ₂₀＝ｚ_b-ｚ₀ …（２） As a result, the equation of motion of this system is as shown in Equation (1).

Here, in order to make the relative displacement an observable output, when the equation (2) is set as the relative displacement z ₂₀ between the sprung and unsprung as the state variables and the absolute velocity z _b over the spring, the state equation is expressed by the equation (3 )
z ₂₀ = z _b -z ₀ (2)

とおき、出力を相対変位ｙ＝ｚ₂₀、入力を車体５にかかる外力ｕ＝ｆ、外乱を路面上下速度

としている。また、ν（ｔ）は観測雑音とし、これらはGauss性白色雑音で、いずれもその平均値、共分散は既知で、式（４）であるとする。

Where the state variable is

The output is the relative displacement y = z ₂₀ , the input is the external force u = f applied to the vehicle body 5, and the disturbance is the road surface vertical speed.

It is said. Further, ν (t) is an observation noise, and these are Gaussian white noises, both of which have an average value and a known covariance, and are assumed to be represented by Expression (4).

Moreover, it is supposed that it is Formula (5).

Therefore, considering that the relative displacement can be measured, the observer is configured as shown in Expression (6) from Expression (3).

Here, L is an observer gain. This observer gain L is solved by Kalman, and is shown in Expression (8) from a positive definite solution P of the Riccati equation AP + PA ^T −PC ^{TR −1} CP + Q = 0 (7) shown in Expression (7). To be determined.
L = PC ^T R ⁻¹ (8)

Further, when applied to a system using a shock absorber as in the fourth embodiment, the damping constant c in the equation (5) becomes variable, and this point needs to be taken into consideration.
In the third embodiment, the damping force actually generated by the shock absorber 103 using the damping force variable calculation unit 130 from the relative speed obtained by differentiating the estimated relative displacement and the control command value of the controller 112. The disturbance observer is configured to input the estimated value as an external force acting on the vehicle body 105 to the observer as f, and the fluctuation of the relative speed due to the variable damping force is cancelled.
In the fourth embodiment, the sprung speed estimation circuit 115 is configured by a Kalman filter. However, other types of observers may be used.

As shown in FIG. 13, the warp calculation unit 116 calculates the difference between the sprung speed vFR of the right front wheel of the vehicle body from the integration circuit 114 and the sprung speed vRL of the left rear wheel of the vehicle body from the sprung speed estimation circuit 115 (vFR -vRL), and the warp wp is calculated by dividing by these distances [distance between the right front wheel portion of the vehicle body and the left rear wheel portion of the vehicle body].
As shown in FIG. 14, the pitch estimation unit 117 calculates an average value of the wheel speeds of the left and right front wheels 102FL and 102FR detected by the wheel speed sensors 111FR and 111FL, and differentiates the obtained average value to obtain a wheel acceleration. calculate. The difference between the wheel acceleration and the longitudinal acceleration detected by the longitudinal acceleration sensor 108 is taken, the obtained signal is integrated, the filter processing and the amplification processing are performed, and the pitch rate pt is estimated. By calculating the average value of the wheel speeds of the left and right front wheel parts of the vehicle body, vehicle speed fluctuations due to acceleration / deceleration are canceled.
As illustrated in FIG. 15, the roll calculation unit 118 calculates a roll rate rol that is a roll component by subtracting the pitch component pt estimated by the pitch estimation unit 117 from the warp wp calculated by the warp calculation unit 116.

As shown in FIG. 16, the bounce estimation unit 119 receives the sprung speeds vFR and vRL of the right front wheel portion and the left rear wheel portion of the vehicle body, and further uses these data to And spring right speed vFL, vRR of the right rear wheel part of the vehicle body and the sprung speeds vFL, vRR at each wheel position together with the sprung speeds vFR, vRL of the right front wheel part and left rear wheel part of the vehicle body. , VFR, vRL, and thus the bounce motion of the vehicle body 105 is estimated.
The sprung speed vFL of the left front wheel part of the vehicle body is the distance between the sprung speed vFR of the right front wheel part of the vehicle body obtained by the integrating circuit 114, the roll rate rol obtained by the roll calculating unit 118, and the shock absorbers 103FL and 103FR of the left and right front wheels. Use to calculate.
The sprung speed vRR of the right rear wheel portion of the vehicle body includes the sprung speed vRL of the left rear wheel portion of the vehicle body obtained by the sprung speed estimation circuit 115, the roll rate rol obtained by the roll calculating unit 118, and the shock absorbers of the left and right rear wheels. Calculation is performed using the distance of 103RL and 103RR.

  As shown in FIG. 17, the front wheel relative speed estimation unit 120 is provided with a variable damping force calculation unit (two are provided, and hereinafter referred to as first and second variable damping force calculation units 130A and 130B as appropriate). And a Kalman filter to which modern control theory is applied (two are provided, hereinafter referred to as first and second Kalman filters 131A and 131B as appropriate), and is detected by the sprung acceleration sensor 107 (right front wheel part). ), The roll rate rol of the roll calculation unit 118, and the sprung speeds vFR, vRR, vFL, and vRL of the bounce estimation unit 119, and the relative speed vsFR of the right front wheel and the relative speed vsFL of the left front wheel. presume. When the absolute value of the roll rate rol of the roll calculation unit 118 is smaller than a predetermined threshold value, the left and right speeds are the same, that is, the relative speed FR = relative speed FL is output. The values (relative speed vsFR, vsFL of the front right wheel and the front left wheel) calculated from the sprung speed (vFR, vRR, vFL, vRL) estimated by the unit 119 using the first and second Kalman filters 131A, 131B are calculated. Select and output.

、出力を上下加速度

、入力を車体１０５に働く外力ｕ＝ｆ、外乱をばね下加速度

とした。 Here, the Kalman filter (131A, 131B) used in the front wheel relative speed estimation unit 120 will be further described. Note that the description of the same parts as the Kalman filter used in the sprung speed estimation circuit 115 is omitted.
The Kalman filter (observer) is designed using a model equivalent to the Kalman filter 131 of the sprung speed estimation circuit 115 (see FIG. 12).

, Output vertical acceleration

, Input is external force u = f acting on the car body 105, disturbance is unsprung acceleration

It was.

Here, it is as shown in Formula (9).

Therefore, when it is considered that the absolute acceleration on the spring can be measured, the Kalman filter (observer) is configured as shown in Expression (10) from Expression (7).

  The observer gain L is the same as that of the Kalman filter 131 of the sprung speed estimation circuit 115 [see Expression (8)]. In order to take into account the damping force variable, the first and second damping force variable calculation units 130A and 130B, like the sprung speed estimation circuit 115, calculate the relative velocity estimation values obtained by the first and second Kalman filters 131A and 131B. The damping force change is calculated using the control command value calculated by the skyhook control unit 123 and fed back to the first and second Kalman filters 131A and 131B.

Next, the rear wheel relative speed estimation unit 122 will be described. As shown in FIG. 18, the rear wheel relative speed estimation unit 122 differentiates the detection value of the vehicle height sensor 110 provided corresponding to the left rear wheel, the left rear wheel relative speed vsRL, and the roll calculation unit 118. Is input of the roll rate rol calculated by the above-mentioned, and the sprung speed (estimated value) [(vFR, vRL, vFL, vRR]] of the bounce estimating unit 119. Here, the calculated value (roll rate rol) of the roll calculating unit 118 When the absolute value is smaller than the threshold value, the left and right relative speeds are the same, that is, relative speed vsFR = relative speed vsFL is output. When the absolute value is larger than the threshold value, the Kalman filter 131C is used from the sprung speed estimated by the bounce estimating unit 119. Then, the values (relative speeds FR and FL of the right front wheel part and the left front wheel part) calculated relative speed are selected and output.
The Kalman filter 131C is the same as that used in the front wheel relative speed estimation unit 120.

  As described above, the pitch rate pt, the roll rate rol, the sprung speed of each wheel, and the relative speed are calculated, and the skyhook control unit 123 generates a control command value using the calculated signals. And output to each shock absorber 103.

  According to the present embodiment, the relative speeds of the wheels 102 and the vehicle body 105 are calculated and used to calculate the control command value for skyhook control. For this reason, a control command value can be individually generated for the shock absorber 103 corresponding to each wheel, and hence the damping force generation control of the shock absorber 103 corresponding to each wheel can be performed with high accuracy.

  Further, in this embodiment, the warp wp of the vehicle body 105 is obtained from the sprung speeds of the two diagonal portions of the vehicle body 105, and the roll rate rol is obtained by subtracting the pitch rate pt obtained from the wheel speed from the warp wp. Calculate and obtain the sprung speed of the part corresponding to the four wheels of the vehicle body 105 and the relative speed of each wheel 102 and the vehicle body 105 from the sprung speed and roll rate rol of one of the two diagonal parts. And can be used to generate a control command value for skyhook control. In order to detect the sprung speed at the two diagonal parts of the vehicle body 105, two corresponding sensors, such as an acceleration sensor and a vehicle height sensor, need only be prepared, so that the device configuration can be simplified and the cost can be reduced. Can be achieved.

In the fourth embodiment, the case where the sprung acceleration sensor 107 and the vehicle height sensor 110 are provided diagonally to the vehicle body 105 is exemplified. However, two sprung acceleration sensors may be provided or two vehicle heights may be provided. A sensor may be provided. The two sensors can be arranged at various positions unless they are arranged in parallel to the pitch direction. This is because if the position is slightly shifted in the roll direction (left-right direction), the detected warp motion includes a roll component, and thus the roll can be calculated by subtracting the pitch motion.
Further, although the vehicle height sensor 110 is used in the fourth embodiment, the vehicle height sensor is used for a vehicle that already has a vehicle height sensor mounted on the rear, such as an optical axis automatic adjustment system vehicle. It may be used as the vehicle height sensor 110 of the third embodiment so as to suppress the number of additional sensors and to avoid complication of configuration and cost increase.

In the fourth embodiment, the roll rate rol is obtained by subtracting the pitch rate pt from the warp wp as described above, and the bounce and thus the sprung speed of the corresponding part of the four wheels is obtained using the roll rate rol thus obtained. At the same time, the detection results are used to obtain the relative speeds of the wheels and the vehicle body, thereby obtaining the control command value for the skyhook control. On the other hand, the pitch rate pt is obtained by subtracting the roll rate rol from the warp wp, and the bounce and the sprung speed of the four wheels are obtained by using the pitch rate pt thus obtained, and this detection result is used. Thus, the relative speeds of the wheels and the vehicle body may be obtained, and thus the control command value for skyhook control may be obtained.
In the fourth embodiment, the pitch rate and roll rate are estimated and obtained, but a gyro sensor may be attached. Of course, the pitch rate and roll rate signals of other systems such as a car navigation system may be acquired and used via a vehicle body network (such as CAN).
As is apparent from the fourth embodiment, the sprung speeds at the two diagonals of the vehicle body 5 are used to obtain the sprung speeds of the four-wheel corresponding portions and the relative speeds of the respective wheels and the vehicle body. Since the control command value of the skyhook control for the shock absorber 3 corresponding to is calculated, the control accuracy can be improved.
Note that the skyhook control of the above embodiment does not require relative velocity data when using a damping force reversal type shock absorber (in which the magnitude of the change in damping force on the expansion side and the contraction side is reversed). It is.
Although the above embodiment has been described based on the skyhook control, if the damping force of the shock absorber can be determined from the data (movement, displacement, speed, acceleration) on the four-wheel spring using the control theory. For example, it may be used for H∞ control or control using modern control theory.

<Fifth Embodiment>
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIGS.
In FIG. 19, a spring 212 and a damping force variable damper capable of adjusting damping characteristics are provided between a vehicle body constituting an automobile (vehicle) and four wheels 211 (only one wheel is shown in the figure). 213 are interposed in parallel, and these support the vehicle body 214. Four dampers 213 and four springs 212 are provided corresponding to the four wheels, but only one of them is shown for convenience.
A sprung acceleration sensor 201 is provided at one location of the vehicle body 214 to detect vertical acceleration (sprung vertical acceleration, hereinafter referred to as sprung acceleration as appropriate) at that location.
The damper 213 includes a damping force generation unit (not shown) and an actuator 215 that drives the damping force generation unit.

Further, as shown in FIG. 20, the vehicle is provided with a steering angle sensor 216, a vehicle speed sensor 217, a lateral acceleration sensor 218, and a wheel speed sensor 205 arranged corresponding to the four wheels.
A controller 220 is connected to the sprung acceleration sensor 201 and the actuator 215, the steering angle sensor 216, the vehicle speed sensor 217, the lateral acceleration sensor 218, and the wheel speed sensor 205.
As shown in FIG. 20, the controller 220 includes a differentiation processing unit 221, a BPF processing unit (hereinafter referred to as a pitch acceleration BPF processing unit) 222, a coefficient multiplication unit (hereinafter referred to as a first coefficient multiplication unit) 223, and an estimated horizontal. Acceleration calculator 224, road surface input influence lateral acceleration calculator 225, BPF processor (hereinafter referred to as roll acceleration BPF processor) 226, coefficient multiplier (hereinafter referred to as second coefficient multiplier) 227, four-wheel spring An upper acceleration calculation unit 228, an integration processing unit (hereinafter referred to as a four-wheel integration processing unit) 229, a four-wheel relative speed calculation unit 230, and a skyhook calculation unit 231 are provided.

The differential processing unit 221 obtains wheel acceleration from the wheel speed information obtained by the wheel speed sensor 205.
The pitch acceleration BPF processing unit 222 performs a BPF (band pass filter) process on the wheel acceleration signal from the differentiation processing unit 221 to extract a pitch acceleration component.
The first coefficient multiplication unit 223 calculates the pitch acceleration by multiplying the pitch acceleration component extracted by the pitch acceleration BPF processing unit 222 by a predetermined coefficient.

The estimated lateral acceleration calculation unit 224 obtains “lateral acceleration due to turning” (estimated lateral acceleration) generated by steering from the steering angle information obtained by the steering angle sensor 216 and the vehicle speed information obtained by the vehicle speed sensor 217.
The road surface input influence lateral acceleration calculation unit 225 calculates the “road surface input influence lateral acceleration” from the “turning influence lateral acceleration” obtained by the estimated lateral acceleration calculation section 224 and the lateral acceleration information obtained by the lateral acceleration sensor 218. Ask.
The roll acceleration BPF processing unit 226 performs BPF processing on “lateral acceleration due to road surface input influence” to extract a roll acceleration component.
The second coefficient multiplication unit 227 multiplies the roll acceleration component extracted by the roll acceleration BPF processing unit 226 by a predetermined coefficient to calculate the roll acceleration.

The four-wheel sprung acceleration calculation unit 228 includes sprung acceleration (sprung vertical acceleration) information obtained by the sprung acceleration sensor 1, the pitch acceleration from the first coefficient multiplier 223, and the second coefficient multiplier 227. From the roll acceleration, the vertical acceleration on the four-wheel spring corresponding to the vertical acceleration of the corresponding part of each of the four wheels in the vehicle body 214 (hereinafter referred to as the four-wheel spring acceleration) is obtained.
The four-wheel integration processing unit 229 obtains a four-wheel spring up-down speed (hereinafter, referred to as a four-wheel spring up-speed as appropriate) from the four-wheel spring up-down acceleration obtained by the four-wheel spring up-acceleration calculation unit 228.
As shown in FIG. 24, the four-wheel relative speed calculation unit 230 includes a Kalman filter 240 (observer) and a damping force variable calculation unit 241, and the four-wheel spring acceleration calculation unit 228 calculates the four-wheel spring. From the upper acceleration, the relative speed between each of the four wheels and the corresponding portion of the four wheels in the vehicle body 214 (sprung / unsprung relative speed, hereinafter referred to as the four-wheel relative speed as appropriate) is obtained.
The skyhook calculation unit 231 is a command for skyhook control for each actuator 215 from the four-wheel sprung speed obtained by the four-wheel integration processing unit 229 and the four-wheel relative speed obtained by the four-wheel relative speed calculation unit 230. Each damper 213 is controlled by generating a current (damping force command value; control command value) and inputting the current to the corresponding actuator 215.

  In this embodiment, the four-wheel sprung speed and the four-wheel relative speed are obtained using the pitch acceleration obtained by performing differential processing (differential processing unit 221) on the wheel speed from the wheel speed sensor 205. Yes. According to this embodiment, since the calculation is made using the pitch acceleration obtained from the wheel speed detected by the wheel speed sensor 205, the influence of the vehicle body acceleration / deceleration can be minimized.

In this embodiment, by estimating the rear sprung vertical acceleration based on the sprung vertical acceleration and the pitch acceleration, no error is caused by using the detected value of the sprung acceleration sensor 201 as it is for the sprung vertical acceleration.
Regarding wheel acceleration estimation, it is not limited to a certain narrow frequency component (for example, sprung resonance), as in the case of wheel speed estimation, and is extremely low frequency region (for example, 0.05 Hz) or less and extremely high frequency region (for example, 15 Hz) or more. It can be estimated by extracting the frequency domain, and the frequency is not limited. Thus, it is possible to accurately estimate the pitch acceleration estimation based on the wheel acceleration, and the sprung vertical acceleration and the rear sprung vertical acceleration based on the pitch acceleration.

In this embodiment, the state quantity that can be estimated by the estimation by the Kalman filter 240 (observer) that receives the four-wheel sprung vertical acceleration as input data is the sprung / unsprung relative speed. Therefore, in this embodiment, calculation processing can be shortened, calculation errors caused by differential processing and filter processing can be eliminated, damping force instruction values can be generated with high accuracy, and suspension control can be performed satisfactorily. It can be performed.
Further, in this embodiment, by correcting the roll change based on the roll acceleration estimated from the steering angle, the vehicle speed, and the lateral acceleration, the sprung vertical acceleration, the sprung vertical speed, and the sprung / unsprung distance of all four wheels are corrected. Relative speed is calculated, which improves the estimation accuracy and vibration control performance. For this reason, in this embodiment, excellent vibration damping performance can be ensured.

Here, the processing content of the controller 220 will be described using the flowchart of FIG. 21, and the operation of the present embodiment will be described in more detail.
In FIG. 21, power is supplied to the controller 220, and execution of the control software starts (step S1). First, the controller 220 is initially set (step S2). Next, it is determined whether or not a predetermined control cycle has been reached (step S3). If it is determined in step S3 that the control cycle has not yet been reached, the process returns upstream and it is determined again whether the control cycle has been reached. If it is determined in step S3 that the control period has been reached (YES), the control amount calculated in the previous control period is output to the actuator 215 (step S4). Thereafter, each sensor information is read (step S5).
Next, sensor information is input to the corresponding part (step S6). Based on the input sensor information, the control calculation execution unit (control calculation execution subroutine) of step S7 sets the sprung speed, sprung / spring. The lower relative speed is estimated and calculated, and the actuator command value (actuator command current, damping force command value) is calculated.

The processing content of the control calculation execution unit will be described with reference to FIG. 22 (flow chart) and FIG. 23 (corresponding relationship diagram of sprung vertical acceleration, pitch acceleration, roll acceleration).
In FIG. 22, first, the wheel acceleration is calculated by differentiating the front wheel speed signal (step S11). Next, the wheel acceleration signal is subjected to bandpass filter processing to extract a pitch acceleration component having a predetermined frequency component (step S12).
Next, the estimated lateral acceleration generated by the turning motion is calculated from the steering angle and the vehicle speed (step S13). If a linear model of the vehicle is assumed and dynamic characteristics are ignored, the estimated lateral acceleration ay can be expressed by the following equation.

ay = [1 / (1 + AV2)]. [V2 / (Lh)] δf
V is the vehicle speed [m / s], A is the stability factor [s 2 / m 2], δf is the front wheel steering angle [rad], and Lh is the wheel base [m].

  On the other hand, the lateral acceleration detected by the lateral acceleration sensor 218 includes both the turning lateral acceleration generated by steering and the lateral acceleration generated by the vehicle body roll motion due to the influence of the road surface input (“lateral acceleration due to the road surface input effect”). The lateral acceleration is included. Therefore, by subtracting the estimated lateral acceleration estimated from the steering angle and vehicle speed from the lateral acceleration detected by the sensor (actual lateral acceleration), the “lateral acceleration due to road surface input” [= (actual lateral acceleration)-(estimated lateral acceleration) Acceleration)] is calculated (step S14).

  “Lateral acceleration due to road surface input” (lateral acceleration generated by vehicle body roll motion due to road surface input) is a tangential acceleration of roll acceleration, and therefore, the lateral acceleration is subjected to bandpass filter processing to obtain a predetermined frequency component. The roll acceleration component is extracted (step S15).

Next, the sprung acceleration of the four wheels is calculated (step S16). Here, as shown in FIG. 23 (a), the vertical acceleration at an arbitrary position of the vehicle body 214 is determined by assuming that the vehicle body 214 is a rigid body. Is determined geometrically. A method for calculating the on-spring sprung vertical acceleration when the sprung acceleration sensor (sprung vertical acceleration sensor) 201 is arranged as shown in FIG. 23B will be described below.
G sensor is the vertical acceleration [m / s ² ] on the spring at the mounting position of the spring acceleration sensor 201, G FR is the vertical acceleration on the front spring [m / s ² ], and G RR is the vertical on the rear spring. Acceleration [m / s ² ], L1 is the distance from the mounting position on the sprung acceleration sensor 201 to the front spring vertical acceleration to be observed, L2 is the distance from the mounting position on the spring acceleration sensor 201 to the vertical acceleration on the rear spring, AGy represents pitch acceleration [rad / s ² ].

The front sprung vertical acceleration G FR can be obtained by the following equation.
G FR ＝ G sensor ＋ AGy × L1
Further, the vertical acceleration G RR on the rear spring can be obtained by the following equation.
G RR = G sensor-AGy × L2

Thus, if the distance from the position where the sprung acceleration sensor 201 is located to the position to be observed and the rotational speed are known, the sprung vertical acceleration at the position to be observed can be obtained.
The sprung vertical acceleration at the position arranged on the left and right axis by the roll acceleration can also be obtained in the same manner as the estimation by the pitch acceleration.

Next, as shown in FIG. 23 (c), in the vehicle in which the sprung acceleration sensor 201 is arranged, a method for calculating the sprung vertical acceleration at the position of the damper 213 of each wheel will be described below.
G sensor is the sprung vertical acceleration [m / s ² ], G FR is the front right sprung vertical acceleration [m / s ² ], and G FL is the front right sprung vertical acceleration. [M / s ² ], G RR is the right rear sprung vertical acceleration [m / s ² ], and G RL is the left rear sprung vertical acceleration [m / s ² ]. L1 is the distance on the y-axis from the mounting position on the sprung acceleration sensor 201 to the vertical acceleration on the front spring to be observed, and L2 is on the y-axis from the mounting position on the spring acceleration sensor 201 to the vertical acceleration on the rear spring. The distance, Wf1 is the distance on the x-axis from the mounting position of the sprung acceleration sensor 201 to the front right spring up-and-down acceleration, and Wf2 is the distance from the mounting position of the sprung acceleration sensor 201 to the front spring-upper vertical acceleration to be observed. The distance on the x-axis, Wr1 is the distance on the x-axis from the mounting position on the sprung acceleration sensor 201 to the rear right sprung vertical acceleration to be observed, and Wf2 is the spring on the left rear to be observed from the mounting position on the sprung acceleration sensor 201 Distance on the x-axis to vertical acceleration, AGy indicates pitch acceleration [rad / s ² ], and AGx indicates roll acceleration [rad / s ² ].

From this, the front right sprung vertical acceleration GFR can be obtained by the following equation.
G FR = G sensor + AGy × L1-AGx × Wf2
The front left sprung vertical acceleration G FL can be obtained by the following equation.
G FL = G sensor + AGy × L1 + AGx × Wf1
Further, the rear right sprung vertical acceleration G RR can be obtained by the following equation.
G RR = G sensor-AGy x L2- AGx x Wf2
Further, the rear left sprung vertical acceleration G RL can be obtained by the following equation.
G RL = G sensor-AGy × L2 + AGx × Wf1
The four-wheel sprung vertical acceleration thus obtained can be obtained, and the four-wheel sprung vertical acceleration is input to the Kalman filter 240 to calculate the relative speed of the four wheels (step S17).

  Here, the four-wheel relative speed calculation unit 230 will be further described. As shown in FIG. 24, the four-wheel relative speed calculation unit 230 is provided with four damping force variable calculation units 241 (four corresponding to the four wheels. Of these, only two are described corresponding to the left and right front wheels. And the Kalman filter 240 to which modern control theory is applied (four are provided corresponding to the four wheels, of which only two are shown corresponding to the left and right front wheels). ing. Then, the four-wheel relative speed calculation unit 230 calculates the four-wheel spring acceleration acceleration unit 228 (four-wheel spring vertical acceleration) and the second coefficient multiplication unit 227 to calculate the four-wheel spring acceleration calculation unit 228. The roll acceleration (estimated value) obtained and the pitch acceleration (estimated value) calculated by the first coefficient multiplication unit 223 and obtained through the four-wheel sprung acceleration calculation unit 228 are input. Here, when the absolute value of the roll acceleration (estimated value) is smaller than a predetermined threshold value, the left and right speeds are the same, that is, output as relative speed FR = relative speed FL and relative speed RR = relative speed RL. If larger, a value obtained by calculating the relative speed using the Kalman filter 240 from the four-wheel spring acceleration estimated by the four-wheel spring acceleration estimation unit is selected and output.

、
出力を上下加速度

、
入力を車体２１４に働く外力ｕ＝ｆ、外乱をばね下加速度

とした。 Hereinafter, an observer for estimating the relative speed from the sprung acceleration will be described. The observer is a 1/4 body model in which the vertical vibration of the vehicle body 214 shown in FIG. 25 is modeled with one degree of freedom [Z _b : absolute vertical displacement of the vehicle body 214, Z ₀ : absolute vertical displacement under the spring, k: spring constant. , C: damping coefficient, f: external force acting on the vehicle body 214, m: mass of the vehicle body 214], the state variable is

,
Output vertical acceleration

,
External force u = f acting on the vehicle body 214 as input, disturbance under unsprung acceleration

It was.

  Here, it is as shown in Formula (9).

  Therefore, considering that the absolute acceleration on the spring can be measured, the Kalman filter (observer) is configured as shown in Expression (10) from Expression (9).

For the observer gain L, the Kalman filter 240 is used. In order to take the damping force variable into consideration, the damping force variable calculating unit 241 calculates the damping force change using the estimated relative velocity of the Kalman filter 240 and the control command value calculated by the Skyhook calculating unit 231, and the Kalman filter 240. Have feedback.
According to this embodiment, the relative velocity and the relative displacement can be directly estimated from the Kalman filter by estimation from the sprung acceleration.

The target damping force of the four wheels is determined based on the four-wheel sprung vertical speed obtained by integrating the four-wheel sprung vertical acceleration calculated as described above and the relative speed of the four wheels (step S18). By giving an instruction to the actuator 215 with the determined target damping force, the damping force of the four-wheel damper 213 (four-wheel suspension) is controlled (step S19).
In the above embodiment, in order to perform skyhook control, control is performed by determining the sprung vertical speed and relative speed of each wheel, but a damping force adjusting type hydraulic shock absorber of a type in which the damping force expands and contracts is reversed. When used, relative speed is not required.
In the above embodiment, an example in which the skyhook control unit 231 is used to perform the skyhook control is shown. However, the present invention can also be used for control using H∞ control or various modern control theories. Good. In this case, since necessary data such as absolute speed and relative speed can be calculated from the sprung acceleration of each wheel obtained by the four-wheel sprung acceleration calculation unit 228, the data can be used to support various control theories. It is.

It is a perspective view which shows typically the components layout of the vehicle provided with the suspension control apparatus of 2nd Embodiment of this invention. It is a block diagram for demonstrating the control function of the control apparatus of FIG. It is a block diagram which shows the longitudinal acceleration estimation means of FIG. It is a block diagram for demonstrating the control function of the engine-derived longitudinal acceleration estimation part of FIG. It is a block diagram for demonstrating the control function of the longitudinal acceleration estimation part (hydraulic pressure origin longitudinal acceleration estimation part) by the brake fluid pressure of FIG. It is a block diagram for demonstrating the control function of the longitudinal acceleration estimation part (air resistance origin longitudinal acceleration estimation part) by the air resistance of FIG. It is a block diagram showing typically control device 8A with which a suspension control device of a 3rd embodiment of the present invention is provided. It is a block diagram which shows typically the control apparatus 8B with which the suspension control apparatus of 4th Embodiment of this invention is provided. It is a perspective view which shows typically the motor vehicle by which the suspension control apparatus which concerns on 4th Embodiment of this invention is employ | adopted. It is a block diagram which shows the structure of the controller of FIG. It is a block diagram which shows the sprung speed estimation circuit of FIG. It is a figure which shows the analysis model of 1/4 vehicle body vertical vibration. It is a block diagram which shows the warp calculation part of FIG. It is a block diagram which shows the pitch estimation part of FIG. It is a block diagram which shows the roll calculation part of FIG. It is a block diagram which shows the bounce estimation part of FIG. It is a block diagram which shows the front-wheel relative speed estimation part of FIG. It is a block diagram which shows the rear-wheel relative speed estimation part of FIG. It is a figure which shows typically the suspension control apparatus which concerns on 5th Embodiment of this invention. FIG. 20 is a block diagram illustrating a configuration of the controller in FIG. 19. It is a flowchart which shows the main control content of the controller of FIG. It is a flowchart which shows the processing content of the control calculation execution part of FIG. (A) shows the correspondence between sprung vertical acceleration, pitch acceleration and roll acceleration acting on the vehicle body, (b) shows the correspondence between sprung vertical acceleration and pitch acceleration, and (c) shows the arrangement of acceleration sensors. It is the figure shown typically. It is a block diagram which shows the four-wheel relative speed calculating part of FIG. It is a figure which shows the analysis model of 1/4 vehicle body vertical vibration.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Suspension control apparatus, 4 ... Damping force variable type shock absorber (damping force adjusting type shock absorber), 8 ... Control apparatus, 20 ... Longitudinal acceleration estimating means (longitudinal acceleration calculating means, pitch rate estimating apparatus), 21 ... Pitch rate Estimating means (pitch rate estimating apparatus), 31... Wheel speed time change rate calculating means (pitch rate estimating apparatus), 32... Calculating means (pitch rate estimating apparatus), 52. ... vertical motion calculation means, 53A ... vertical motion calculation means, 54 ... control unit, 61 ... first vertical acceleration calculation means, 62 ... second vertical acceleration calculation means.

Claims (9)

A suspension control device comprising a damping force adjustment type shock absorber that is interposed between a vehicle body and wheels of a vehicle and changes a damping characteristic according to an external command, and a control device that controls the damping characteristic, The control device
First vertical motion calculation means for calculating vertical motion of a first point set at an arbitrary position of the vehicle body;
Roll motion estimation means for estimating the roll motion of the vehicle body;
Pitch motion estimating means for estimating the pitch motion of the vehicle body;
Each part vertical motion calculating means for calculating vertical motion of each part of the vehicle body from the vertical motion, the roll motion and the pitch motion;
A command is calculated according to the vertical movement of each part, and the command is sent to the damping force adjusting shock absorber.
The pitch motion estimation means includes
A wheel speed time change rate calculating means for detecting rotation of the wheel and calculating a wheel speed time change rate from the detection result;
Longitudinal acceleration acquisition means for detecting or estimating the longitudinal acceleration of the vehicle body without using the rotation of the wheel;
A suspension control apparatus comprising: a subtracting means for calculating a pitch rate from a difference between a wheel speed time change rate calculated by the wheel speed time change rate calculating means and a longitudinal acceleration acquired by the longitudinal acceleration acquiring means .   2. The suspension control device according to claim 1, wherein the vehicle has a pair of wheels on the left and right sides of the vehicle body, and the wheel rotation is an average value of wheel rotations of the pair of wheels. A suspension control device. The suspension control device according to claim 2 , wherein the pitch rate is not calculated when wheel rotations of the pair of wheels are in opposite phases.   2. The suspension control apparatus according to claim 1, wherein the vehicle has a motor torque detecting means for detecting a torque of a prime mover, and the longitudinal movement is obtained from an output of the prime mover torque detecting means. apparatus.   The suspension control device according to claim 1, wherein the vehicle has a braking mechanism, and the longitudinal motion is obtained from a braking force generated by the braking mechanism.   2. The suspension control apparatus according to claim 1, wherein the longitudinal motion is obtained from position information of the vehicle by GPS. The suspension control apparatus according to claim 1, wherein
The control device has integration means,
The vertical motion calculating means calculates vertical acceleration of the point of the vehicle body,
The roll motion estimation means estimates the roll acceleration of the vehicle body,
The pitch motion estimation means estimates the pitch acceleration of the vehicle body,
Each part vertical motion calculation means calculates the vertical acceleration of each part of the vehicle body from the vertical acceleration, the roll acceleration and the pitch acceleration,
The integrating means calculates the vertical speed of each part by integrating the vertical acceleration of each part,
The controller calculates a command according to the vertical speed of each part and sends the command to the damping force adjustment type shock absorber. The suspension control apparatus according to claim 1, wherein
Second vertical motion calculating means for calculating vertical motion of a second point set at a position away from the first point in a direction different from the pitch direction of the vehicle body;
Warp motion calculating means for calculating a warp motion from the vertical motion of the first point and the vertical motion of the second point;
The suspension control device, wherein the roll motion estimation means estimates a roll motion of the vehicle body from a difference between the warp motion and the pitch motion. The suspension control apparatus according to claim 1, wherein
Second vertical motion calculating means for calculating vertical motion of a second point set at a position away from the first point in a direction different from the roll direction of the vehicle body;
Warp motion calculating means for calculating a warp motion from the vertical motion of the first point and the vertical motion of the second point;
The suspension controller according to claim 1, wherein the pitch motion estimation means estimates the pitch motion of the vehicle body from a difference between the warp motion and the roll motion.

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