JPH07101370B2 - Automatic steering control system - Google Patents

Description

The present invention relates to an automatic steering control system for an automated guided vehicle traveling on a course formed by a combination of straight and circular arc shapes.

In the conventional automatic steering control method for unmanned guided vehicles that steers by the rotational speed difference between the left and right drive wheels, in addition to detecting and feeding back the deviation between the center of the unmanned guided vehicle and the running course, it also detects the vehicle body angular velocity as a steering state. The automatic steering control is performed by calculating and outputting the rotation speed command value for controlling the rotation speed of any drive motor of the left and right drive wheels based on the difference between the feedback amount and the target value. Since the feedback of the steering state is performed in the same form regardless of whether the shape of the traveling course is a straight line or an arc, even if the feedback gain of the lateral displacement is increased on the arc-shaped traveling course, the lateral displacement does not completely disappear.
There is a problem that an unstable phenomenon occurs due to increasing the gain.

In order to solve these problems, the present invention subtracts an offset amount according to the radius of curvature and the traveling speed of the traveling course from the feedback of the steering state on an arc-shaped traveling course, and the target value of the reciprocal of the turning radius is It is characterized by introducing a process that determines the reciprocal of the radius of curvature of the course, so that the same stable and accurate automatic steering control as on a straight course can be performed even on a circular course. Is to

FIG. 1 is an example of an unmanned guided vehicle that steers by the rotational speed difference of the left and right drive wheels to which the present invention is applied, and travels on an arc-shaped travel course with zero deviation from the travel course. It shows the state of doing. 1 is a vehicle body of an automatic guided vehicle (hereinafter referred to as a vehicle body), 2 and 2 are drive wheels, and a vehicle body 1
A pair of drive wheels 2 and 2 are arranged on the left and right in the width direction of the vehicle. The number of rotations is known by an encoder (not shown) provided on the drive wheels 2 and 2, and the vehicle position, that is, the amount of lateral deviation between the vehicle and the traveling course is obtained. It is possible to detect the lateral displacement of.

In the state of FIG. 1, the turning radius of the vehicle body 1 matches the curvature radius R of the course, and the vehicle body angular velocity ω ₀ is the curvature radius R of the course.
And the traveling speed V, it is expressed as in equation (1).

FIG. 2 is an example of a block diagram of an automatic steering control system when the present invention is applied to a vehicle body that steers with left and right drive wheels 2 and 2 as shown in FIG. 1, and 3 is a drive motor / motor controller / Left and right drive mechanisms including a reduction mechanism and drive wheels, 1 is a lateral displacement that is the lateral displacement of the vehicle body with respect to the traveling course, ε is a deviation feedback amount, and the feedback amount is a lateral displacement 1 and a lateral displacement l. Gains Gl, Gsl, G, and Gψ are detected for each of the integrated value ∫l · dD depending on the traveling distance, the time differential value dl / dt of the lateral displacement l, and the differential value dl / dD of the lateral displacement l for the traveling distance D of the vehicle body 1. It is a value obtained by multiplying each by and adding each. ω is the vehicle body angular velocity, ω ₀ is the vehicle body angular velocity offset amount, Gω is the vehicle body angular velocity feedback gain, 1 / GR ′ is the gain that determines the target value of the reciprocal turning radius, and 1 / R ₀ is the reciprocal turning radius offset Amount, 1 / R 'is the target value of the reciprocal of the turning radius, f is the target value of the reciprocal of the turning radius 1 /
Contents of calculating the steering command value from R ', ΔT is the steering command value (command value for increasing / decreasing the rotational speed of the left and right drive motors from the traveling speed command value), T is the traveling speed command value, and _TL is the rotation of the left driving motor. speed command value, T _R is the rotational speed command value of the right driving motor.

In the automatic steering control system shown in FIG. 2, the rotational speed command values T _L and T _R of the left and right drive motors are expressed by the equation (2).

The content f for calculating the steering command value (command value for increasing / decreasing the rotational speed of the left and right drive motors from the traveling speed command value) ΔT is expressed by the equation (3).

In the equation (3), V is the traveling speed detection value, and W is the distance between the left and right driving wheels shown in FIG.

Also, the target value 1 / R 'of the reciprocal of the turning radius of the vehicle body 1 is (4)
It is expressed as an expression.

In the equation (4), when the deviation between the vehicle body and the traveling course is zero, and the detected value of the vehicle body angular velocity ω becomes equal to the offset amount ω ₀ , the target value 1 / R ′ opposite to the turning radius becomes the offset amount 1 / R ₀ . Will be equal. Therefore, when the running course is straight,
Both ω ₀ and 1 / R ₀ are zero. On the contrary, in the case of an arc shape,
Even if the running course is straight, if 1 / R ₀ is made equal to the reciprocal 1 / R of the curvature radius of the course, and ω ₀ is an offset amount of a value according to the curvature radius of the course and the traveling speed as shown in equation (1). Even with an arcuate shape, the same stable and accurate automatic steering control can be performed.

The calculations of the expressions (1) to (4) are processed by a computer or an equivalent calculation by an electric circuit or the like. Also,
It is necessary to know the value of the offset amount when the traveling course has a linear shape and when the traveling course has an arc shape. This is based on the value of the rotation of the left and right drive wheels 2 and 2 detected by an encoder or the like. Is calculated by a computer or the like, or is detected by a magnet and a magnetic sensor embedded on the traveling course.

S is a steering command value (steering motor rotation speed command value).

As explained above, on the arc-shaped running course,
Since the steering state (turning radius, vehicle body angular velocity) corresponding to the radius of curvature of the traveling course and the traveling speed can be generated in the vehicle body 1, stable and accurate automatic steering control similar to that on a straight traveling course can be performed. There is an advantage.

[Brief description of drawings]

FIG. 1 is an example of a vehicle body which is steered by left and right driving wheels to which the present invention is applied, and FIG. 2 is an example of a block diagram of an automatic steering control system when the present invention is applied to a vehicle body as shown in FIG. is there. 1 ... Car body 2 ... Drive wheel 3 ... Drive mechanism

Claims (1)

[Claims] 1. A lateral displacement as a deviation between a vehicle body and a traveling course, a differential value or a posture angle of a lateral displacement according to a traveling distance, a time differential value of the lateral displacement, and an integrated value according to a traveling distance of the lateral displacement are detected. The steering angle and the vehicle body angle detection value are detected as the steering state of the vehicle, and each amount of the deviation between the vehicle body and the traveling course and each amount of the vehicle steering state are fed back, and the turning radius of the vehicle body is calculated from the sum of all feedback amounts. In an unmanned guided vehicle that determines the target value of the reciprocal number and calculates the rotation speed command value of the left and right drive motors according to the target value and the traveling speed command value to perform automatic steering by the difference in the rotation speed of the left and right drive wheels, When traveling on an arc-shaped traveling course, the vehicle body, which is determined by the traveling speed and the radius of curvature of the traveling course from the vehicle body angular velocity detection value that is the feedback amount of the steering state, is biased on the arc-shaped traveling course. The vehicle body angular velocity required to maintain zero is subtracted as an offset amount and fed back, and when the target value of the reciprocal of the turning radius is set, the reciprocal of the radius of curvature of the traveling course is added to determine the target value. The automatic steering control method is characterized by performing stable and accurate automatic steering control similar to that on a straight course.