JP2010091317A - Radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar system which reduces false detection of an obstacle ahead of a vehicle. <P>SOLUTION: When it is determined that an obstacle is not a vehicle in the opposite lane (S1, S2) on the basis of the relative speed with respect to the obstacle and the distance thereto measured by the radar, whether or not the obstacle is at a stop is determined on the basis of the relative speed and the distance (S3). When the obstacle is at a sop (S3 Yes), whether or not the obstacle continues to exist within a virtual one's own lane having a predetermined width with respect to the vehicle travel direction for a predetermined period of time on the basis of the measurement result of the radar (S4 to S7). When the obstacle continues to exist for a predetermined period of time (S7 Yes), or when the obstacle is not at a stop (S3 No), whether or not the measured distance is shortest among the distances to the obstacles existing within one's own lane is determined (S8), and when it is shortest, the measured distance and relative speed are output (S9). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radar apparatus that measures a relative speed, a distance, and the like with a preceding vehicle or a stop (hereinafter referred to as an “obstacle”) in front of the vehicle.

The collision damage mitigation device reduces the damage at the time of collision by automatically operating a brake when collision with an obstacle is difficult to avoid. For the determination of the brake operation, a signal from a radar device that measures a relative speed, a distance, and the like with an obstacle is used. Similarly, an output signal from the radar apparatus is used in ACC (Adaptive Cruise Control) that keeps the inter-vehicle distance from the preceding vehicle constant. The radar apparatus transmits an electromagnetic wave such as a millimeter wave in front of the vehicle, and performs various measurements based on a reflected wave from an obstacle (Patent Document 1).
JP 2005-134266 A

  However, the radar apparatus may erroneously measure even obstacles in the vertical direction that are not obstacles, such as overpasses, road surface reflections such as manholes and road surface irregularities. For this reason, there is a possibility that the collision damage reducing device or the ACC may intervene in various controls at an unexpected timing of the vehicle driver and cause a brake or the like to malfunction.

  Therefore, in view of such a conventional problem, an object of the present invention is to provide a radar apparatus that reduces erroneous measurement of an obstacle, for example, in order to prevent malfunction of a brake by a collision damage reducing apparatus.

  For this reason, the radar apparatus according to claim 1 includes an obstacle measuring unit that measures a relative speed to an obstacle located in front of the vehicle and a distance to the obstacle, a vehicle speed measuring unit that measures a vehicle speed, and the obstacle. Obstacle determining means for determining the presence or absence of an obstacle based on the measurement result of the obstacle measuring means, and when the obstacle determining means determines that there is an obstacle, the obstacle measuring means and the vehicle speed measuring means Based on the relative speed and the vehicle speed respectively measured by the stop determination means for determining whether or not the obstacle is stopped, and when it is determined by the stop determination means that the obstacle is not stopped, A first output means for outputting the measured relative speed and distance, and a vehicle traveling direction based on a measurement result of the obstacle measuring means when the stop judging means determines that the obstacle is stopped. Vs. It is determined whether or not the obstacle continues to exist in a virtual own lane having a predetermined width for a predetermined time, and if the obstacle continues to exist for a predetermined time, the latest measured for the obstacle And a second output means for outputting a relative speed and a distance.

  The radar apparatus according to claim 2, wherein the stop determination unit determines that the obstacle is stopped when a ground speed of the obstacle that is a sum of the vehicle speed and the relative speed is within a predetermined range. It is characterized by doing. Here, the predetermined range is a stop speed range that delimits the stop of the obstacle, and when a fixed range in which the upper limit value and the lower limit value are fixed or a variable range in which the upper limit value and the lower limit value are changed based on the own vehicle speed is set. Good.

  The radar apparatus according to claim 3, wherein when the obstacle determining means determines that there is an obstacle, the radar apparatus is based on the relative speed and the vehicle speed respectively measured by the obstacle measuring means and the vehicle speed measuring means. An oncoming vehicle determining means for determining whether or not the object is an oncoming vehicle is further included, and the obstacle determination is performed only when the stop determining means determines that the obstacle is not an oncoming vehicle by the oncoming vehicle determining means. It is characterized by determining whether the thing has stopped.

  The radar apparatus according to claim 4, wherein the oncoming vehicle determining unit is configured such that the obstacle is an oncoming vehicle when the ground speed of the obstacle, which is the sum of the vehicle speed and the relative speed, is equal to or less than a predetermined value. It is characterized by determining.

  The radar apparatus according to claim 5, wherein the first output means and the second output means respectively calculate the relative speed and distance of an obstacle at the shortest distance among the distances to the obstacles in the own lane. It is characterized by outputting.

  The radar apparatus according to claim 6 is characterized in that the predetermined time is set to gradually decrease as the vehicle speed measured by the vehicle speed measuring means increases.

  The radar device according to claim 7, further comprising own lane width changing means for dynamically changing a predetermined width of the own lane based on a vehicle speed measured by the vehicle speed measuring means. To do.

  The radar apparatus according to claim 8, wherein a road curvature is estimated based on an angular velocity or rudder angle around a yaw axis of the vehicle, and the curvature of the own lane is changed based on the road curvature estimated by the estimation means. And a self-lane curvature changing means.

  According to the first aspect of the present invention, when the obstacle located in front of the vehicle is a moving object that is not stopped, the measured relative speed and distance are output, while the obstacle is stopped. Sometimes, it is monitored whether or not the obstacle continues to exist in the virtual own lane in the vehicle traveling direction for a predetermined time, and if it continues for a predetermined time, the latest measured relative speed and distance Is output. Since the road surface reflection determined as a stationary object disappears from the measurement range in a short time together with changes in the vehicle progress and environmental factors, it is possible to reduce erroneous measurement by excluding it from the measurement target.

  According to invention of Claim 2, when the ground speed of the obstruction which is the sum of a vehicle speed and a relative speed exists in the predetermined range, it determines with the obstruction stopping. As described above, the stop determination is made based on whether or not the ground speed of the obstacle is within the predetermined range. Therefore, the determination is simple and reliable, and the processing efficiency can be improved.

  According to the third aspect of the invention, the determination of whether or not the obstacle is stopped is started only when the obstacle is not an oncoming vehicle. For this reason, since the oncoming vehicle can be excluded from the measurement target before the obstacle stop determination, the processing efficiency can be improved.

  According to the invention of claim 4, when the ground speed of the obstacle, which is the sum of the vehicle speed and the relative speed, is equal to or less than a predetermined value, it is determined that the obstacle is an oncoming vehicle. As described above, since the oncoming vehicle is determined based on whether or not the ground speed of the obstacle is a predetermined value or less, the determination is simple and reliable, and the processing efficiency can be improved.

  According to the fifth aspect of the present invention, if the measured distance to the obstacle is the shortest distance among the distances to the plurality of obstacles existing in the own lane, the distance and the relative speed are output. For this reason, it is possible to output only signals of obstacles with high urgency among obstacles existing in the vehicle traveling direction.

  According to the sixth aspect of the invention, the predetermined time is gradually set smaller as the vehicle speed increases. For this reason, since the time to reach the obstacle is taken into account according to the vehicle speed, unnecessary processing that ends the judgment before the obstacle arrives or continues the judgment even after the obstacle passes is suppressed. The load can be reduced.

  According to invention of Claim 7 or Claim 8, based on the measured own vehicle speed or the estimated road curvature, the width | variety and curvature of the own lane are changed dynamically. For this reason, it is possible to measure only obstacles existing in the vehicle traveling direction among a plurality of obstacles existing in the measurement range, that is, obstacles existing in the own lane changed according to the driving state and road curvature. Measurement accuracy and processing efficiency can be improved.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows the overall configuration of a vehicle equipped with a collision damage reducing apparatus using a radar apparatus according to the present invention.

  The collision damage reduction apparatus includes a collision damage reduction electronic control unit (hereinafter referred to as “collision damage reduction ECU”) 10 having a built-in computer. The collision damage reduction ECU 10 receives various signals such as the vehicle speed, the angular velocity around the yaw axis, and the relative speed and distance from an obstacle located in front of the vehicle, and is stored in a ROM (Read Only Memory) or the like. Execute. The collision damage reduction ECU 10 outputs a brake operation command to the brake ECU 20 that electronically controls a service brake and the like and performs various control of the engine when it is difficult to avoid a collision with an obstacle located in front of the vehicle. A torque cut command is output to the engine ECU 30 that performs the operation.

  Of various signals input to the collision damage reduction ECU 10, the vehicle speed is output from the engine ECU 30, and the angular velocity around the yaw axis is output from the yaw rate sensor 40. On the other hand, the relative speed and distance to the obstacle are determined by the radar 50 that performs various measurements on the obstacle located in front of the vehicle, and the radar ECU 60 that performs various controls such as noise removal based on the output signal from the radar 50. Are output from a radar apparatus including the above.

  Here, the radar 50 is a millimeter wave radar that is not easily affected by environmental factors such as bad weather and dirt in order to function as an obstacle measuring means. Measure distance. Further, the radar ECU 60 executes the control program, so that the obstacle determination means, the stop determination means, the first output means, the second output means, the oncoming vehicle determination means, the own lane width changing means, and the own lane curvature changing means respectively. Embodied. Note that the vehicle speed is input from the engine ECU 30 to the radar ECU 60. In the present embodiment, the engine ECU 30 functions as vehicle speed measuring means, but a known vehicle speed sensor may be used as the vehicle speed measuring means.

  FIG. 2 shows the processing contents of a control program that is repeatedly executed by the radar ECU 60 while the vehicle is traveling.

In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), based on at least one of the relative velocity V _{r to the} obstacle and the distance L _r to the obstacle measured in front of the vehicle, Determine if there is an obstacle in place. If there is an obstacle, the process proceeds to step 2 (Yes), and otherwise, the process ends (No).

In step 2, it is determined whether or not the obstacle is an oncoming vehicle. First, the vehicle speed V _c is read from the engine ECU 30 and the ground speed V _a is calculated based on the relative speed V _r read from the radar 50. The ground speed V _a is the sum of the vehicle speed V _c and the relative speed V _r . Next, it is determined whether or not the ground speed V _a is equal to or less than _a predetermined value (V _s ). For example, as shown in FIG. 3, the predetermined value (V _s ) is the smaller of −3.6 [km / h] or − (less than 10% of the host vehicle speed V _c ). In FIG. 3, the sign of the speed is positive (+) in the vehicle traveling direction and negative (−) in the vehicle facing direction (oncoming vehicle traveling direction). If the ground speed V _a of the obstacle is equal to or less than _a predetermined value (V _a ≦ −V _s ), it is determined that the vehicle is an oncoming vehicle and the process ends (Yes). Otherwise, it is determined that the vehicle is not an oncoming vehicle. To step 3 (No).

In step 3, it is determined whether or not an obstacle determined not to be an oncoming vehicle is stopped. Here, as shown in FIG. 3, it is determined whether or not the ground speed V _a of the obstacle is within _a predetermined range (−V _s <V _a <V _s ). If the ground speed V _a of the obstacle is within _a predetermined range (−V _s <V _a <V _s ), it is determined that the obstacle is a stopped object and the process proceeds to step 4 (Yes Otherwise, it is determined that the obstacle is a moving object that has not stopped, and the process proceeds to Step 8 (No). In addition, although the lower limit value of the predetermined range is the same value as the predetermined value in Step 2, these may be different values.

In step 4, a predetermined time T _s is set according to the vehicle speed V _c . Here, the predetermined time T _s is set to a value that gradually decreases as the vehicle speed V _c increases, as in the map shown in FIG. That is, the predetermined time T _s is set small because the arrival time to the obstacle is short when the vehicle speed is high, and is set large because the arrival time to the obstacle is long when the vehicle speed is low.

  In step 5, the timer is reset and the time is started from an initial value of 0 seconds.

  In step 6, it is determined whether an obstacle exists in the own lane. Here, the own lane is a measurement range having a virtual predetermined width W, and a determination region having a predetermined width W with respect to the vehicle traveling direction is formed in the measurement range that can be measured by the radar 50. For this reason, it is possible to improve measurement accuracy and processing efficiency by measuring only obstacles existing in the own lane among a plurality of obstacles measured in the measurement range. For example, since the lane width between an expressway and a general road is often wider on the expressway, the predetermined width W of the own lane is set wider if the vehicle speed is high, while the own lane is set if the vehicle speed is low. The predetermined width W is set narrow to improve the measurement accuracy. Further, if the road curvature is estimated, the curvature C is provided in the own lane so as to follow the estimated curvature, and only the stopping object existing there is included in the measurement object to improve the processing efficiency. If there is an obstacle in the own lane, the process proceeds to step 7 (Yes). Otherwise, the measurement is incorrect and the process ends (No).

In step 7, the time the timer has timed determines whether a predetermined time has elapsed T _s. If the predetermined time T _{s has} elapsed, the process proceeds to step 8 (Yes), but if the predetermined time T _s has not elapsed, the process returns to step 6 (No), and the process is repeated.
In step 8, the distance L _r to the obstacle determines whether the shortest distance L _min of the distance L _n to the obstacle to be more determined by the own vehicle lane. If the measured distance L _r is the shortest distance L _min , the process proceeds to step 9 (Yes), and otherwise, the process ends (No).

In step 9, and outputs the relative velocity V _r and the distance L _r between the measured obstacle to collision damage reduction ECU 10, the process ends.

  According to such a radar apparatus, it is monitored whether or not the measured obstacle continues to exist in the virtual own lane in the vehicle traveling direction for a predetermined time. If the obstacle continues to exist in the own lane for a predetermined time, a signal is output as an accurate measurement. On the other hand, if the obstacle does not continue to exist, the measurement ends because the measurement is incorrect. For this reason, the radar apparatus can reduce erroneous measurements such as road surface reflections that disappear from the measurement range due to changes in the vehicle progress, environmental factors, and the passage of time.

  In the above embodiment, the own lane is set in a straight line if the road on which the vehicle travels is a straight road. On the other hand, if the road curvature is estimated based on the angular velocity ω around the yaw axis measured by the yaw rate sensor 40, the own lane is set to have the curvature C. The road curvature can be estimated by a steering angle sensor, a gyro sensor, or the like in addition to the yaw rate sensor 40. For example, the road curvature may be estimated based on the steering angle θ measured by the steering angle sensor.

  Further, the radar device may be provided with means for mechanically swinging the radar 50 to the left and right, and configured to swing the radar 50 to the left and right based on the estimated road curvature. According to this, the obstacle which exists on the curve road can be measured earlier.

Furthermore, in step 4 to step 7, but counts a predetermined time T _s based on the timer, for example, the providing counter, obstacle up the counter if present in the own lane, when this reaches a predetermined number Alternatively, the configuration may proceed to step 8.

  Furthermore, the radar apparatus according to the present invention can be applied not only to a collision damage reducing apparatus but also to an apparatus that uses measurement results relating to an ACC or an obstacle ahead of a vehicle for driving control.

Overall configuration diagram of a vehicle equipped with a collision damage reducing apparatus using a radar apparatus according to the present invention Flow chart showing processing contents of control program Relationship between the speed of obstacles to ground and the speed of oncoming vehicles, stops, or moving objects Explanatory drawing of the map for setting a predetermined time

Explanation of symbols

30 Engine ECU
40 Yaw rate sensor 50 Radar 60 Radar ECU

Claims (8)

Obstacle measuring means for measuring a relative speed to an obstacle located in front of the vehicle and a distance to the obstacle;
Vehicle speed measuring means for measuring the vehicle speed;
Obstacle determining means for determining the presence or absence of an obstacle based on the measurement result of the obstacle measuring means;
Whether or not the obstacle is stopped based on the relative speed and the vehicle speed respectively measured by the obstacle measuring means and the vehicle speed measuring means when the obstacle judging means determines that there is an obstacle. Stop determination means for determining;
First output means for outputting the measured relative speed and distance when it is determined by the stop determination means that the obstacle has not stopped;
When it is determined by the stop determination means that the obstacle is stopped, based on the measurement result of the obstacle measurement means, the obstacle is in a virtual own lane having a predetermined width with respect to the vehicle traveling direction. A second output means for determining whether or not the object continues to exist for a predetermined time, and outputs the relative speed and distance measured most recently for the obstacle if the object continues to exist for a predetermined time;
A radar apparatus comprising:   The stop determination means determines that the obstacle is stopped when the ground speed of the obstacle, which is the sum of the vehicle speed and the relative speed, is within a predetermined range. The radar apparatus described. Whether or not the obstacle is an oncoming vehicle based on the relative speed and the vehicle speed measured by the obstacle measuring means and the vehicle speed measuring means, respectively, when the obstacle judging means determines that there is an obstacle. Further comprising an oncoming vehicle determining means for determining
The stop determination unit determines whether or not the obstacle is stopped only when the oncoming vehicle determination unit determines that the obstacle is not an oncoming vehicle. The radar device described in 1.   The oncoming vehicle determination means determines that the obstacle is an oncoming vehicle when the ground speed of the obstacle, which is the sum of the vehicle speed and the relative speed, is a predetermined value or less. 3. The radar device according to 3.   The first output means and the second output means each output a relative speed and a distance of an obstacle at a shortest distance among distances to each obstacle in the own lane. The radar apparatus according to any one of claims 1 to 4.   The radar apparatus according to any one of claims 1 to 5, wherein the predetermined time is set to gradually decrease as the vehicle speed measured by the vehicle speed measuring unit increases. .   The vehicle lane width changing means for dynamically changing the predetermined width of the vehicle lane based on the vehicle speed measured by the vehicle speed measuring device is further comprised. The radar device according to any one of the above. Estimating means for estimating the road curvature based on the angular velocity or rudder angle around the yaw axis of the vehicle;
Self-lane curvature changing means for changing the curvature of the own lane based on the road curvature estimated by the estimating means;
The radar apparatus according to claim 1, further comprising:

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