JPH07101369B2 - 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 an automated guided vehicle that steers by the steered wheels, in addition to detecting and feeding back the deviation from the traveling course, the steering angle and the vehicle body angular velocity are also detected and fed back as the steering state to determine the total feedback amount. Automatic steering control is performed by calculating and outputting the rotation speed command value of the steering motor from the deviation of the target value, but since the steering state feedback is performed in the same form regardless of whether the shape of the traveling course is straight or arc, Even if the feedback gain of the lateral displacement is increased on the arc-shaped course,
There is a problem that the lateral displacement is not completely eliminated, and an unstable phenomenon occurs due to increasing the gain.

In order to solve these problems, the present invention is characterized by introducing a process of subtracting an offset amount according to a radius of curvature of a course and a traveling speed from feedback of a steering state on an arc-shaped traveling course, and its purpose. Is to enable stable and accurate automatic steering control similar to that on a straight course even on a circular course.

FIG. 1 is an example of an unmanned guided vehicle that is steered by steered wheels to which the present invention is applied, and shows a state where a vehicle is traveling on an arc-shaped traveling course with zero deviation from the traveling course. There is. 1 is a vehicle body of an automated guided vehicle (hereinafter referred to as a vehicle body), 2 is a steered wheel, 3 is a fixed wheel (a wheel that does not perform steering), and a pair of fixed wheels 3 and 3 are arranged on the left and right in the width direction of the vehicle body. An encoder (not shown) provided on this fixed ring 3,3
Thus, the vehicle body position can be calculated by the rotation speed of the encoder, and the lateral displacement of the traveling course can be detected by this calculation.

In the state shown in FIG. 1, the vehicle body 1 must generate a steering angle ₀ and a vehicle body angular velocity ω ₀ , and these are calculated from equations (1), (2) based on the curvature radius R of the traveling course, the traveling speed V, and the wheel base L. ) Is expressed as

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 steering wheels as shown in FIG. 1, and 4 is a steering motor / motor controller /
A steering mechanism including a speed reduction mechanism and steered wheels, 1 is a lateral displacement which is a lateral displacement amount of a vehicle body with respect to a traveling course, ε is a feedback amount of a deviation expressed below, and a lateral displacement l is
The integrated value of the lateral displacement 1 according to the traveled distance is obtained by adding the product of the lateral displacement 1 and the sequential travel distance, and the integrated value ∫l · dD of the lateral displacement 1 due to the traveled distance D of the vehicle body 1 for preventing steady deviation
The time derivative dl / dt of the lateral displacement 1 indicating the rate of change of the lateral displacement with respect to time and the derivative dl of the lateral displacement l according to the traveling distance D of the vehicle body 1 showing the rate of change of the lateral displacement with respect to the posture angle ψ or the travel distance. Gains Gl, Gsl, G, Gψ for each detected value of / dD
Is a value obtained by multiplying each by and adding each. Further, the steering angle, ₀ is the offset amount of the steering angle, ω is the vehicle body angular velocity,
ω ₀ is the offset amount of the vehicle body angular velocity, G is the feedback gain of the steering angle, Gω is the feedback gain of the vehicle body angular velocity, and S is the steering command value (steering motor rotation speed command value).
Is.

However, while the differential value of the lateral displacement according to the traveling distance is an element that does not change with the traveling speed, the time differential value of the lateral displacement with respect to time is an element that changes with the traveling speed. The percentage of contribution of the feedback to the stability of steering control increases.

In the automatic steering control system shown in FIG. 2, the steering command value (steering motor rotation speed command value) S is expressed by equation (3).

S =-{ε + G · (− ₀ ) + Gω · (ω−ω ₀ )}
(3) In the equation (3), when the deviation ε from the traveling course is zero and the steering angle detection value becomes equal to the offset amount ₀ , the steering command value S becomes zero and the steered wheels 2 stand still. When the running course of the linear shape Therefore, _0, omega ₀ both zero, when the arc _0, depending on the curve radius and the traveling speed of the traveling course, such as omega ₀ respectively (1) and (2) If the offset amount is a different value, it is possible to perform stable and accurate automatic steering control for a traveling course similar to a straight line shape or an arc shape.

The calculations of the expressions (1) to (3) are processed by a computer or an equivalent calculation by an electric circuit or the like. In addition, in order to determine the value of the offset amount, it is necessary to know the transition time between the linear running course and the arcuate running course.This is based on the value detected by the encoder etc. of the rotational speed of the left and right fixed wheels. This can be done by calculating the vehicle body position by a computer or the like, or by detecting it with a magnet and a magnetic sensor embedded on the traveling course.

As described above, since the steering state (steering angle, vehicle body angular velocity) according to the radius of curvature of the course and the traveling speed can be generated on the vehicle body on the arc-shaped traveling course, There is an advantage that the similar stable and accurate automatic steering control can be performed.

[Brief description of drawings]

FIG. 1 is an example of a vehicle body that is steered by steered wheels to which the present invention is applied, and FIG. 2 is an example of an automatic steering control system block diagram when the present invention is applied to a vehicle body as shown in FIG. . 1 …… Car body 2 …… Steering wheel 3 …… Fixed wheel …… Attitude angle 4 …… Steering 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 angular velocity are detected as the steering state of the vehicle, the amounts of deviation between the vehicle body and the traveling course and the amounts of the vehicle body steering state are fed back, and the steering motor is adjusted so that the sum of all feedback amounts becomes zero. In an unmanned guided vehicle in which automatic steering control is performed by steered wheels by calculating and outputting the rotation speed command value of the steering wheel, the steering angle detection value, which is the feedback amount of the steering state when traveling on an arc-shaped traveling course, the vehicle body Determined from the angular velocity detection value by the radius of curvature of the course. By subtracting the vehicle body angular velocities necessary for maintaining zero deviation on the arc-shaped traveling course as an offset amount and feeding them back, the same stability and stability as on a linear traveling course can be achieved even on an arc-shaped traveling course. An automatic steering control method characterized by performing highly accurate automatic steering control.