CN114280922A

CN114280922A - Path tracking control method under high-speed scene

Info

Publication number: CN114280922A
Application number: CN202111614906.9A
Authority: CN
Inventors: 李悦; 李凯; 田小青; 江辉; 陈静
Original assignee: Dongfeng Yuexiang Technology Co Ltd
Current assignee: Dongfeng Yuexiang Technology Co Ltd
Priority date: 2021-12-27
Filing date: 2021-12-27
Publication date: 2022-04-05

Abstract

A path tracking control method under a high-speed scene comprises the steps of obtaining position and speed information of a vehicle at the moment when the vehicle runs on a reference path, obtaining coordinates (x, y, psi) of the vehicle under a coordinate system and speed v of the vehicle according to a set expected geometric path, and obtaining a yaw rate r of the vehicle.

Description

Path tracking control method under high-speed scene

Technical Field

The invention belongs to the field of automobiles, and particularly relates to a path tracking control method in a high-speed scene.

Background

In recent years, with the progress of computer technology and sensor technology, research into autonomous vehicles has been made with enormous success. Path tracking is one of the important components of an autonomous vehicle, whose purpose is to follow a desired path or trajectory by controlling the lateral and longitudinal movement of the vehicle. It is well known that vehicle kinematic models are not suitable for high speed path tracking because they are inaccurate area tire force saturation, and the controller follows the required path based on the kinematic model, from low speed to high speed and even at the limit of processing. . The PI active front wheel steering control is adopted to control the yaw rate tracking error, so that the comprehensive influence of continuous disturbance and parameter change is overcome while the vehicle steering dynamics performance is improved. The yaw rate reference is taken as a control input to an outer control loop that employs PID control of lateral offset to suppress perturbations in curvature that increase linearly with time.

Disclosure of Invention

The vehicle motion model according to the above is not suitable for high-speed path tracking. In order to solve the technical problems, the invention is realized by the following technical scheme:

a path tracking control method in a high speed scenario, the method comprising the steps of:

step 1: when the vehicle runs on a reference path, acquiring the position and speed information of the vehicle at the moment, and constructing a coordinate system by taking a target tracking point as an origin according to a set expected geometric path;

acquiring position information (x, y, psi), speed v and yaw rate r of a vehicle at the current moment through a vehicle ECU;

step 2: outputting the obtained vehicle coordinate information and speed information to an MPC controller of a motion model with sideslip compensation and a target equation as follows to obtain a desired yaw rate r (d)

s.t.z₀＝z(t),u_-1＝u(t-t_s)；

z_i+1＝f(z_i,u_i)；i＝0,Λ,H_p-1；

And step 3: the desired yaw rate r (d) and yaw rate r, velocity v, obtained from the MPC controller are input to the PID to give δ (f),

where a0 is the additional control introduced in the dynamic control, Kp1 is the proportional control parameter, Ki1 is the integral control parameter value, and the feedback from the yaw rate r improves the transient by changing the characteristic displacement of the steering dynamics;

and 4, step 4: then the obtained data information delta is processed_fAnd transmitting the information to a vehicle ECU, adjusting the vehicle state by the ECU, then performing motion control at the next moment, and repeating the steps 1, 2 and 3 to form a loop.

The invention has the beneficial effects that: a series control loop of a hybrid MPC and a PID is designed, a motion model MPC with sideslip compensation generates a yaw rate reference signal, an inner PID control loop quickly tracks a signal from an external yaw rate reference, and the tracking error of a driving maneuver is obviously reduced by adding yaw rate feedback.

Drawings

FIG. 1 is a diagram of MPC experimental data feedback;

fig. 2 is an architectural diagram of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example (b): as shown in fig. 1 and 2, a method for controlling path tracking in a high-speed scenario includes the following steps:

s.t.z₀＝z(t),u_-1＝u(t-t_s)；

z_i+1＝f(z_i,u_i)；i＝0,Λ,H_p-1；

and 4, step 4: then the obtained data information delta is processed_fTransmitting the data to the vehicle ECU, adjusting the vehicle state by the ECU, and then carrying out the next timeAnd (3) controlling the motion, and repeating the steps 1, 2 and 3 to form a loop.

The information obtained by the curve test of the vehicle at the speed of 60 km/h is shown in fig. 1, wherein blue is the actual effect of the proposed scheme, black is the modified dynamic model MPC, and green is the dynamic model MPC; through comparison, the scheme that the tracking error of the driving maneuver is obviously reduced by the aid of the additional yaw rate feedback can be obtained.

The invention designs a hybrid MPC and PID cascade control loop, an external control loop adopts a motion MPC controller with vehicle sideslip compensation to generate a yaw rate reference signal, an internal PID control loop is used for quickly tracking a yaw rate reference from the outside, and the tracking error of driving maneuver is obviously reduced by adding yaw rate feedback.

The method is based on MPC and PID control to design a transverse control model, wherein the transverse control model comprises an MPC controller with a sideslip compensation motion model, a proportion-integral-derivative PID regulation and a vehicle ECU; firstly, acquiring running information of a vehicle through a vehicle ECU, and determining a vehicle state of the vehicle according to the running information; secondly, the external control loop MPC controller receives the vehicle instantaneous state parameters and the corresponding reference path output to generate the reference signal of the expected yaw rate, and then the ratio-integral-derivative PID processes the obtained real yaw rate and the expected yaw rate output by the vehicle, and the obtained data is transmitted to the vehicle to form a closed loop. This method, with feedback of yaw rate, can significantly reduce the tracking error for almost all driving maneuvers, as it improves the system's transients.

A vehicle ECU readable storage medium, characterized in that the vehicle ECU readable storage medium stores one or more program instructions which, when executed by a processor, perform the respective steps of the method of claim 1. The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A path tracking control method under a high-speed scene is characterized by comprising the following steps:

step 1: when the vehicle runs on a reference path, acquiring the position and speed information of the vehicle at the moment, and acquiring the coordinates (x, y, psi) of the vehicle in a coordinate system, the speed v of the vehicle and the yaw rate r of the vehicle according to a set expected geometric path;

step 2: outputting the obtained vehicle coordinate information and speed information to an MPC controller of a motion model with sideslip compensation, further processing the vehicle position information and the speed information at the current moment of the vehicle, substituting the information into the following optimization objective equation to obtain the expected yaw rate r (d),

s.t.z₀＝z(t),u_-1＝u(t-t_s)；

z_i+1＝f(z_i,u_i)；i＝0,Λ,H_p-1；

and step 3: the desired yaw rate r (d) and yaw rate r obtained by the MPC controller, the vehicle speed v, are output to the controller PID, yielding δ (f),

and 4, step 4: then the obtained data information delta is processed_fAnd transmitting the data to a vehicle ECU, and adjusting the vehicle state by the ECU and then controlling the motion at the next moment.

2. The path tracking control method under the high-speed scene as claimed in claim 1, wherein the vehicle constructs a coordinate system with a target tracking point as an origin.

3. A vehicle ECU readable storage medium, characterized in that the vehicle ECU readable storage medium stores one or more program instructions which, when executed by a processor, perform the respective steps of the method of claim 1.