JP2019128929A - Convoy travel tracking control method and device - Google Patents

Abstract

To provide a convoy travel tracking control method and device which suppress a value of lateral deviation occurring upon turning as a result of use of a path following control law in convoy travel tracking control which requires maintaining of an inter-vehicle distance.SOLUTION: This is attributable to use of azimuth deviation from a proceeding vehicle as a value of azimuth deviation in a control law. Providing azimuth deviation with a correction term in accordance with a turn curvature radius so that a path following control law works effectively while maintaining an inter-vehicle distance makes it possible to suppress lateral deviation in travelling with a minimum curvature radius of a highway main line. Moreover, more generally, velocity yaw angular velocity and position azimuth of the proceeding vehicle at a time point at which the proceeding vehicle has passed before a distance corresponding to the inter-vehicle distance are transmitted to the following vehicle, and the following vehicle is caused to trace a locus of the proceeding vehicle based on the path following control law to follow the proceeding vehicle.SELECTED DRAWING: Figure 1

Description

The present invention relates to an application of “path following control law” (Non-patent Document 1) in vehicle platooning follow-up control (see FIG. 1).

A control law known as a “path following control law” is applied to follow-up control in vehicle platooning (see Non-Patent Documents 2 and 3).

"A Stable Tracking Control Method for an Autonomous Mobile Robot" by Kanayama, Yutaka et al. , In Proc. IEEE International Conference on Robotics and Automation, pp. 384-389, May 1990. Autonomous driving based on path-following control of trucks Takanori Fukao et al. Transactions of the Japan Society of Mechanical Engineers (C) Volume 77 Issue 783 (2011-11) Control Technology for Truck Convoy Takanori Fukao et al. System / Control / Information VoL. 58, no. 5 pp. 175-180, 2014

When applying the "path following control law" (Equations (1) and (2)) to a row running follow-up control requiring maintenance between vehicles, the value of the azimuth angle deviation of the control law equation (2) is Using the azimuth deviation between the leading vehicle and the following vehicle according to the definition, a lateral deviation (equation (4)) occurs when turning. It is an object of the present invention to suppress this lateral deviation.

The control rules of equations (1) and (2) are the same as the trajectory of the preceding vehicle traveling with the non-holonomic constraint condition shown in equations (6) and (7), ie, the trajectory of the center of rotation (center of gravity) of the preceding vehicle It has a characteristic that it is possible to accurately trace the center of rotation (center of gravity) of a following vehicle which travels with nonholonomic constraint conditions, that is, the following vehicle.

Therefore, in the formation traveling follow-up control that causes the preceding vehicle to follow while maintaining the inter-vehicle distance, the deviation from the preceding vehicle is used as the values of longitudinal deviation, lateral deviation, and azimuth deviation in Equations (1) and (2). An accurate tracking characteristic of this control law can be obtained by using the deviation from the position / azimuth angle of the preceding vehicle at the point where the preceding vehicle has passed by an inter-vehicle distance L, instead of using it.

In the case where the leading vehicle which is turning is followed while maintaining the inter-vehicle distance, if the azimuth deviation from the leading vehicle is used as the control amount in the equation (2), a lateral deviation inevitably occurs. This will be described below.

During steady-state turning, the yaw angular velocity of the following vehicle is equal to the yaw angular velocity of the preceding vehicle, so the second term of equation (2) is zero. Therefore, although the sum of two terms in the parenthesis of the second term of the equation (2) is 0, the vehicle is turning with the distance between the vehicles maintained, so that an azimuth difference with the preceding vehicle occurs. Therefore, if the azimuth difference is positive (in the case of left turn), a negative lateral deviation occurs, and if the azimuth difference is negative (in the case of right turn), a positive lateral deviation occurs.

Assuming that the curvature radius of the road is R, the inter-vehicle distance (here, the distance between the center of gravity of the preceding vehicle and the following vehicle) is L, and the azimuth deviation is L / R considering the range of L / R From the condition that the sum of the two terms in the parenthesis of the second term of 2) is 0, the value of the lateral deviation is calculated by equation (8).

Although increasing the constant of the denominator of equation (8) reduces the value of the lateral deviation, there is a limit in terms of control system stability in terms of increasing this constant. This will be described next.

In the row-following control system shown in FIG. 1, the dynamic characteristics of the vehicle (in FIG. (1), "straight-forward motion of the vehicle", "rotational motion of the vehicle", "speed control device" and "steering angle control device If the azimuthal angle deviation is linearized in a small range with the velocity constant and the constant angular velocity is constant, the yaw rotational motion system of the control system in Figure 1 becomes a second-order system, and its natural angular frequency and damping constant (Non-Patent Document 1).

On the other hand, a vehicle rotational motion (yaw rotational motion) system linearized with a constant speed is also a secondary system, and its natural angular frequency is calculated from the speed and vehicle specifications. From the viewpoint of the stability of the control system, the natural angular frequency of Equation (9) needs to be sufficiently smaller than the natural angular frequency of this vehicle rotational motion system, and the value of the control constant is limited.

If the damping constant of the equation (9) is selected to be around 1, the value of the control constant is also limited from this aspect.

If the curvature radius is sufficiently larger than the inter-vehicle distance to be maintained, as in the case of a highway main line, the lateral deviation during turning can be eliminated by correcting L / R for the azimuthal angle deviation. Is resolved. Since the radius of curvature R is obtained from the ratio of the velocity to the yaw angular velocity, the correction term has the form shown in equation (2a) (solution 1).

As a general-purpose solution, obtain accurate tracking characteristics of control law (1) (2) equation by passing speed yaw velocity and position azimuth angle data of preceding vehicle at distance L before passing to distance L And the problem of the present invention is solved (solution 2).

The lateral deviation can be suppressed even in the platooning turn with the minimum curvature radius of the main highway (Solution 1, Solution 2).

Even when the vehicle is turning at the minimum turning radius level, it is possible to follow the trajectory of the vehicle of the same size (Solution 2).

Since it does not depend on road white line detection (refer to non-patent document 3), it is possible to cope with lane change (solution 2).

  The block diagram of a row running follow-up control system is shown. A follow-up vehicle receives the speed and yaw angular velocity data from the preceding vehicle, detects the deviation from the preceding vehicle, and gives the speed control device and steering angle control device a control system that follows the control amount calculated by the path following control law. Show. The following vehicle is the preceding vehicle of the next following vehicle in formation.   path following Indicates the definition of longitudinal deviation, lateral deviation and azimuth deviation, which are control quantities of control law.

Solution 1 can be incorporated into existing equipment by adding division and addition operations. Take measures to prevent division by zero, such as biasing a small positive value to the velocity signal.

Solution 2 is on the preceding vehicle side. (1) A distance with a margin with respect to the inter-vehicle distance L [m], for example, 30 [m], a constant distance interval s [m], for example 0.05 [m] A buffer for storing speed yaw angular velocity and position azimuth angle data, and a buffer for storing 600 numerical values for each speed yaw angular velocity and position azimuth angle data are prepared.
(2) The velocity is integrated to obtain the cumulative distance, and the integrator is reset each time the integral output becomes s [m], and the velocity yaw angular velocity and position azimuth data at that time are the first stage of each buffer. The data is stored in the position and the buffer is shifted by one stage, the last stage data is discarded, or it may be a circular shift.
(3) At a certain time interval, for example, every 5 ms, the data on the (L / s) th buffer of the following vehicle, that is, the velocity yaw angular velocity and position azimuth data at the time of passing before the distance L Send to the following car.

The following vehicle calculates deviation according to deviation definition equations (3), (4) and (5) using (4) position and azimuth angle data transmitted from the preceding vehicle, and together with the speed yaw angular velocity data transmitted in the same manner, ) And (2) are calculated and updated.

On the leading vehicle side and following vehicle (5) The yaw rate can be detected by the yaw rate sensor.
(6) Azimuth angle detection can be calculated by integrating the yaw rate sensor output integration, the magnetic azimuth sensor output, and the azimuth angle obtained from GPS Doppler.
(7) The position detection can be calculated by unifying the values obtained by integration of the equations (6) and (7) and the position data obtained from the GPS-RTK receiver.
(8) The speed is obtained by integrating speed signals obtained from wheel rotation and speed data obtained from GPS Doppler.

  Track and follow control system for trucks, buses, etc.

When applying the "path following control law" (Equations (1) and (2)) to a row running follow-up control requiring maintenance between vehicles, the value of the azimuthal angle deviation of the control law (2) is Using the azimuth deviation between the leading vehicle and the following vehicle according to the definition, a lateral deviation (equation (4)) occurs when turning. It is an object of the present invention to suppress this lateral deviation.

Claims (4)

The correction term shown in the equation (2a) in the equation (2) of the “path following control rule” (FIG. 1 and the equation (1) (2)) in the row running follow-up control of the vehicle maintaining and following the inter-vehicle distance A control method that enables formation traveling follow without adding lateral deviation during steady turn (Fig. 2). The correction term shown in the equation (2a) in the equation (2) of the “path following control rule” (FIG. 1 and the equation (1) (2)) in the row running follow-up control of the vehicle maintaining and following the inter-vehicle distance In addition, a control device that enables platooning follow-up without causing lateral deviation (FIG. 2) during steady turning.   In the formation follow-up control of a vehicle applying the "path following control rule", the speed yaw angular velocity and position azimuth angle data at the time when the preceding vehicle passes a distance equivalent to the distance between vehicles is transmitted to the following vehicle A control method capable of maintaining the inter-vehicle distance and tracing the trajectory of a preceding vehicle by making the following velocity yaw angular velocity and position azimuth angle follow. In formation control following control applying "path following control law", every time the preceding vehicle travels a fixed minute distance, the value of the speed yaw angular velocity and position azimuth angle at that time should be stored and stored, and the following vehicle should be maintained The speed yaw angular velocity and position azimuth angle data at the time when the preceding vehicle passed before the distance corresponding to the inter-vehicle distance is transmitted to the following vehicle at a certain time interval, and the following vehicle follows the locus of the preceding vehicle by following the above control law. Control device that can do that.

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