JP2676831B2 - Automatic guided vehicle position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a position detection device for an automated guided vehicle.

B. Outline of the Invention Although it is not possible to detect an accurate two-dimensional position by simply measuring the distance traveled along the traveling direction of the automatic guided vehicle, a lateral shift occurs, for example, when a corner is curved. In the present invention, since the moving distance measuring device having the measurement directions orthogonal to each other is installed, the two-dimensional position can be calculated by measuring the lateral moving distance. If a measuring device using a spatial filter is used as the moving distance measuring device, it is possible to avoid a measurement error due to wheel slip or wear.

C. Conventional technology Conventionally, in automated driving of automated guided vehicles, a method of laying an electromagnetic induction wire or optical reflection tape on the road to form a travel guide, or attaching an encoder or tachogenerator to the axle or measuring wheel. Then, there is a method of measuring the speed and moving distance of the unmanned vehicle from a pulse or analog voltage corresponding to the rotation of the wheel.

However, these methods require processing of a traveling path in which a guide wire, a reflective tape, etc. are laid on the road surface, and the processing work is troublesome and the wheel slippage and wheel wear due to unevenness of the road surface, external force, etc. are accurate. I could not measure.

For this reason, a distance measuring method using a spatial filter has been developed as a method of measuring a moving distance in a non-contact manner without requiring guidance from the outside.

D. Problems to be Solved by the Invention When distance is measured by using a spatial filter, errors due to wheel slip and wear can be avoided, but the distance traveled along the traveling direction is measured. For example, when turning a corner, it is difficult to obtain an accurate two-dimensional position because steering causes the wheels to skid outward.

It is an object of the present invention to provide a position detecting device for an automatic guided vehicle, which can obtain an accurate two-dimensional position / speed even when the wheels are laterally displaced.

E. Means and Actions for Solving the Problems Since the automatic guided vehicle is provided with the moving distance measuring device orthogonal to the measuring direction and the detector for detecting the steering angle, it is possible to steer the vehicle when, for example, turning a corner. As a result, the automated guided vehicle will skid outward, but the travel distance measured by the two travel distance measuring devices and the travel distance in the direction orthogonal thereto and the inclination of the vehicle body detected by the steering angle detector. Since the sideslip can be calculated by calculating from, the two-dimensional position of the automated guided vehicle after the curve can be calculated.

F. Examples Hereinafter, the present invention will be described in detail according to Examples shown in the drawings.

1 to 3 show an embodiment of the present invention. As shown in FIG. 2, the automatic guided vehicle 1 is a three-wheeled vehicle having a front wheel 2 and rear wheels 3 and 4, and the front wheel 2 is a drive wheel that is driven and rotated by a traveling motor 5 and is turned by a steering motor 6. It is also a steering wheel. The front wheel 2 is provided with a potentiometer 7 that detects the steering angle. The rear wheels 3 and 4 are both driven wheels, and a moving distance / velocity detector 8 and a velocity detector 8 based on a spatial filter are located on the center line of the vehicle body, which is an intermediate position between them.
9 are installed. These moving distance / speed detectors 8,9
Is the same as the normal one except that the detection direction is parallel or perpendicular to the traveling direction and is orthogonal. That is, the third
As shown in the figure, the moving distance / velocity detectors 8 and 9 by the spatial filter both receive the light reflected from the road surface by the line sensors 12 and 13 via the optical systems 10 and 11, and the read circuits 14 and 15 It is sampled at a specific cycle, converted into a digital signal by the AD converter 16, and then input to the calculation unit 17. The calculation unit 17
It has a CPU18, RAM19 and ROM20, and extracts an arbitrary frequency component by multiplying the input signal by a sine wave and a cosine wave and integrating it in a predetermined range, and converts it to a vector corresponding to the moving distance, and then the speed Calculate Furthermore, the calculation unit 17
Is input after digitizing the steering angle of the front wheels 2 from the potentiometer which is the steering angle detector 7, and calculates the two-dimensional position / velocity of the automatic guided vehicle according to the calculation system system diagram shown in FIG.

Here, FIG. 4 is based on the result of simulating an automatic guided vehicle by a two-wheeled vehicle model as shown in FIGS. 5 and 6.

That is, although the automated guided vehicle 1 of this embodiment has one front wheel and two rear wheels, the front wheel 1 is based on Ackermann-Junt's theory.
It can be approximated as a two-wheeled vehicle with one wheel and one rear wheel.
In the figure, at the steering angle θ, the front wheels move from point C to point C ′, and the rear wheels move from point D to point D ′. At this time, the following formula is established.

Where ρ is the inclination of the vehicle body with respect to the y-axis, θ is the steering angle with respect to the vehicle body, x, y is the position of the rear wheels, V is the speed (rear wheels), L is the length between the front wheels and the rear wheels, and the automated guided vehicle 1 is C. Assuming that each point moves from point D, point C'to point D'for 1 sampling time (T _S ), the change Δ during this time is given by the following equation based on the geometrical relationship in FIG. .

Here, S _V is the distance in the traveling direction detected by the moving distance / speed detector 8 by the spatial filter.

The above equations (4), (5), and (6) do not take into consideration the sideslip of the vehicle body, but when the vehicle bends, it actually causes sideslip and causes a point D'to change from the point C'to the point C ". To the D ″ point. Therefore, the correction is made as follows.

_{Δx = S V · sinρ-S} W · cos (ρ + Δρ) ≒ S V · sinρ-S W (cosρ-Δρsinρ) ... (8) Δy = S V · cosρ + S W · sin (ρ + Δρ) ≒ S V · cosρ + S W ( sinρ + Δρcosρ) ... (9) wherein said S _W is the moving distance transverse to the vehicle body detected by the moving distance and speed detector 9 by the spatial filter.

Therefore, the two-dimensional position and direction of the automatic guided vehicle can be calculated by the equations by the distances S _V and S _W detected by the moving distance / speed detectors 8 and 9 by the spatial filter and the steering angle θ obtained by the steering angle detector 7. It is calculated by the equations (7) to (9) and then cumulatively added as shown in the following equation. However, the subscript is the number of times of sampling.

ρ _n = ρ _n-1 + Δρ (10) x _n = x _n-1 + Δx (11) y _n = y _n-1 + Δy (12) A spatial filter is used as the measuring device for measuring the moving distance. It is not limited to only things. For example, as shown in FIG. 7 showing another embodiment of the present invention, the lateral movement distance is detected by a movement distance detecting device 10 using a spatial filter, and the movement distance along the traveling direction is measured by providing a measuring wheel 11. It may be done. Further, as shown in the figure, a gyro may be provided as the steering angle detector instead of the potentiometer.

G. Effects of the Invention As described above in detail based on the embodiments, in the present invention, since the unmanned guided vehicle is provided with the moving distance measuring device orthogonal to the measuring direction and the detector for detecting the steering angle, Even if skidding occurs when the transport vehicle bends, it is estimated from the travel distance measured by the two travel distance measuring devices and the travel distance in the direction orthogonal thereto, and the inclination of the vehicle body detected by the steering angle detector. The sideslip can be obtained by calculation based on the equations (8) and (9) described above, and the accurate two-dimensional position and direction of the automatic guided vehicle can be obtained.

[Brief description of the drawings]

1 and 2 are a plan view and a perspective view, respectively, of an automated guided vehicle, FIG. 3 is a block diagram of a position detecting device according to an embodiment of the present invention, and FIG. 4 is an explanatory diagram showing an arithmetic system. FIG. 5 is a motorcycle model diagram based on Ackermann-Jand's theory, FIG. 6 is a motorcycle model diagram with skidding, and FIG. 7 is a plan view of an automated guided vehicle according to another embodiment. In the drawing, 1 is an automated guided vehicle, 2 is a front wheel, 3 and 4 are rear wheels, 7 is a steering angle detection device, 8 and 9 are movement distance / speed detectors using a spatial filter, 11 is a measurement wheel, and 12 is a gyro. is there.

Continuation of front page (56) Reference JP 62-112069 (JP, A) JP 63-233413 (JP, A) JP 62-105206 (JP, A) JP 54-61972 (JP , A)

Claims (1)

(57) [Claims] 1. A moving distance measuring device having two measuring directions orthogonal to each other is installed on a center line of an automatic guided vehicle, and a detector for detecting a steering angle is attached to the automatic guided vehicle. In a position detecting device provided with a calculation circuit for calculating a two-dimensional position and direction of the automatic guided vehicle from a steering angle, the calculation circuit is configured to move in a traveling direction measured by one of the movement distance measuring devices. Based on the product of the distance and the sine component of the inclination of the vehicle body measured by the steering angle detector, the movement distance in the lateral direction with respect to the traveling direction measured by the other of the movement distance measuring devices and the steering angle detection. A value obtained by subtracting the product of the cosine component of the sum of the change of the vehicle body tilt measured by the measuring device is defined as one of the two-dimensional sideslip of the automatic guided vehicle, and one of the moving distance measuring devices is used. Measured by The product of the traveled travel distance in the traveling direction and the cosine component of the inclination of the vehicle body measured by the steering angle detector, and the lateral travel with respect to the traveled direction measured by the other of the travel distance measuring devices. The value obtained by adding the product of the distance and the inclination of the vehicle body measured by the steering angle detector and the sine component of the sum of the changes is used as the other skid of the two-dimensional position of the automatic guided vehicle. Position detection device for automated guided vehicles.