JP7296064B2 - Platoon follow-up control method - Google Patents

Description

The present invention relates to the application of the "path following control rule" (Non-Patent Document 1) in platooning follow-up control of vehicles (see FIG. 1).

A control law known as a "path following control law" is applied to follow-up control in platooning of vehicles (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 truck Takanori Fukao et al. Transactions of the Japan Society of Mechanical Engineers (C edition) Vol.77 No.783 (2011-11) Control Technology for Truck Platoon Takanori Fukao et al. System/Control/Information Vol. 58, No. 5 pp. 175-180, 2014

When applying the "path following control law" (formulas (1) and (2)) to platooning follow-up control that requires vehicle-to-vehicle distance maintenance, the value of the azimuth angle deviation in the control law formula (2) is given by formula (5). Using the azimuth angle deviation between the preceding and following vehicles 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 laws of equations (1) and (2) are such that the trajectory of the preceding vehicle running under the non-holonomic constraint conditions shown in equations (6) and (7), that is, the trajectory of the center of rotation (center of gravity) of the preceding vehicle, is the same. It has the characteristic that the center of rotation (the center of gravity) of the following vehicle that runs under non-holonomic restraint conditions, that is, the following vehicle, can be accurately traced.

Therefore, in the platooning follow-up control that follows the preceding vehicle while maintaining the inter-vehicle distance, the deviation from the preceding vehicle is used as the values of the longitudinal deviation, lateral deviation and azimuth angle deviation in equations (1) and (2). Accurate follow-up characteristics of this control law can be obtained by using the deviation from the position and azimuth angle of the preceding vehicle at the point where the preceding vehicle has passed the inter-vehicle distance L before.

When following a turning preceding vehicle while maintaining the inter-vehicle distance, if the azimuth angle deviation from the preceding vehicle is used as a control amount in Equation (2), a lateral deviation will inevitably occur. This point will be explained below.

Since the yaw angular velocity of the following vehicle is equal to the yaw angular velocity of the preceding vehicle during a steady turn, the second term of Equation (2) is zero. Therefore, the sum of the two terms in the parenthesis of the second term of the formula (2) is 0, but since the vehicle is turning while maintaining the inter-vehicle distance, there is an azimuth angle difference with the preceding vehicle. Therefore, if the azimuth angle difference is positive (left turn), a negative lateral deviation will occur, and if the azimuth angle difference is negative (right turn), a positive lateral deviation will occur.

R is the radius of curvature of the road, L is the inter-vehicle distance (here, the distance between the center of gravity of the preceding vehicle and the following vehicle), and considering the range of L/R<<1, the azimuth angle deviation is L/R. From the condition that the sum of the two terms in the parentheses of the second term in 2) is 0, the value of the lateral deviation is calculated by equation (8).

If the constant of the denominator of equation (8) is increased, the value of the lateral deviation will be decreased, but there is a limit to the stability of the control system when increasing this constant. This point will be explained below.

In the platooning follow-up control system shown in FIG. 1, the dynamic characteristics of the vehicle (in FIG. ) is ignored and the yaw rotation motion system of the control system in FIG. ) (Non-Patent Document 1).

On the other hand, the vehicle rotational motion (yaw rotational motion) system linearized at a constant speed is also a quadratic system, and its natural angular frequency is calculated from the speed and vehicle specifications. From the standpoint of stability of the control system, the natural angular frequency of equation (9) must be sufficiently smaller than the natural angular frequency of the vehicle rotational motion system, and the value of the control constant is limited.

Also, if the damping constant of the equation (9) is selected to be around 1, the value of the control constant is also restricted from this point of view.

When the radius of curvature is sufficiently larger than the inter-vehicle distance to be maintained, such as on a highway main line, it is possible to eliminate the lateral deviation during turning by correcting the azimuth angle deviation by the L/R portion. is resolved. Since the radius of curvature R is obtained from the ratio of the velocity and the yaw angular velocity, the correction term has the form shown in Equation (2a) (Solution 1).

As a general-purpose solution, obtain accurate follow-up characteristics of the control laws (1) and (2) by a method of passing the speed yaw angular velocity and position and azimuth angle data at the time when the preceding vehicle passed the distance L ahead to the following vehicle. is made, and the problem of the present invention is solved (solution 2).

Lateral deviation can be suppressed even in platooning turns at the minimum radius of curvature of the highway main line (solution 1, solution 2).

Even when the vehicle turns at the minimum turning radius level, it is possible to trace and follow the trajectory of a vehicle of similar size (Solution 2).

Since it does not depend on road white line detection (see Non-Patent Document 3), lane changes can be handled (solution 2).

2 shows a block diagram of a platooning follow-up control system; FIG. A control system in which the following vehicle receives speed yaw angular velocity data from the preceding vehicle, detects the deviation from the preceding vehicle, and gives the operation amount calculated by the path following control rule to the speed control device and the steering angle control device to perform follow-up control. show. The following vehicle here is the leading vehicle of the following vehicle in the platoon. Definitions of longitudinal deviation, lateral deviation, and azimuth angle deviation, which are control amounts of the path following control law, are shown.

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

Solution 2 is on the preceding vehicle side. A buffer for storing velocity yaw angular velocity and position azimuth angle data for each position and a buffer for storing 600 numerical values for each velocity yaw angular velocity and position azimuth angle data are prepared.
(2) Integrate the velocity to obtain the cumulative distance traveled, reset the integrator each time the integrated output reaches s [m], and store the velocity yaw angular velocity and position azimuth angle data at that time in the frontmost stage of each buffer. The data may be stored in the position and shifted by one stage, the data in the last stage may be discarded, or circular shift may be performed.
(3) At a certain time interval, for example, every 5 [ms], the data on the (L/s)th buffer, that is, the speed, yaw angle, and position/azimuth angle data at the time when the following vehicle passed the distance L before. Send to following vehicle.

(4) Using the position and azimuth angle data transmitted from the preceding vehicle, the following vehicle calculates the deviation according to the deviation definition formulas (3), (4) and (5), and calculates the deviation with the speed yaw angular velocity data also transmitted by the formula (1 ) and (2) are calculated and updated.

(5) The yaw rotation speed can be detected by a yaw rate sensor.
(6) The azimuth angle detection can be calculated by integrating the azimuth angle obtained from the integration of the yaw rate sensor output, the magnetic azimuth sensor output, and the GPS Doppler.
(7) Position detection can be calculated by integrating the values obtained by integration of equations (6) and (7) and the position data obtained from the GPS-RTK receiver.
(8) Velocity is obtained by integrating velocity signals obtained from wheel rotation and velocity data obtained from GPS Doppler.

Platoon follow-up control system for trucks, buses, etc.

Claims (1)

In a vehicle platoon following control method for maintaining and following a distance between vehicles, position coordinates of a preceding vehicle and a following vehicle are set to (x _r , y _r ) and (x _c , y _c ), respectively, and the preceding vehicle and the following vehicle are Let θ _r and θ _c be the azimuth angles of , respectively, and x _e , y _e , and Let _{θe be} the velocities of the preceding and following vehicles, _vr and _vc respectively, the yaw rate of the preceding vehicle be _ωr , the distance between the centers of gravity of the preceding and following vehicles be L, and the control constants be _Kx and _Ky , K _θ as the control law, by adding a correction term as shown in Equation (2a) to the argument of the sine function in the second term on the right side of Equation (2), A platooning follow-up control method that enables platooning follow-up control without causing lateral deviation during steady turning.
(Number 1)
v = v _r cos θ _e + K _x x _e ... (1)
ω = ω _r + v _r (K _y y _e + K _θ sin θ _e ) ... (2)
ω = ω _r + v _r (K _y y _e + K _θ sin(θ _e - (ω _r /v _r )L)) ... (2a)
x _e = (x _r - x _c ) cos θ _c + (y _r - y _c ) sin θ _c ... (3)
y _e = -(x _r - x _c ) sin θ _c + (y _r - y _c ) cos θ _c ... (4)
θ _e = θ _r - θ _c ... (5)

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