A collaborative control method for vehicle lateral and longitudinal stability under extreme conditions

Abstract

The invention discloses a cooperative control method for the lateral and longitudinal stability of automobiles under extreme working conditions. First, the four-wheel hub motor-driven electric vehicle model is obtained by using the simulation software CarSim; second, a two-degree-of-freedom reference model is designed, and the two-degree-of-freedom reference model Deduce the expected value of the vehicle lateral velocity and yaw rate; then, in order to reduce the complexity of the solution, a two-layer control structure is adopted, and the upper layer uses the NMPC controller to ensure the lateral and longitudinal stability of the vehicle as the control goal, and consider the lateral and longitudinal safety constraints for optimization Solve to get the virtual control quantity—the expected value of tire slip rate and side slip angle; finally, the lower layer obtains the additional torque to act on the wheel hub according to the deviation between the actual slip rate and side slip angle of the tire and the expected value given by the upper layer motor, so as to ensure the stability of the vehicle in the transverse and longitudinal directions.

Description

technical field [0001] The invention relates to a coordinated control method for the lateral and longitudinal stability of an automobile under extreme working conditions. Under the present invention, a collaborative control method for lateral and longitudinal stability with low computational complexity is designed, which belongs to the technical field of vehicle safety control. Background technique [0002] Under extreme driving conditions, the vehicle is easily unstable and causes traffic accidents. At this time, the lateral and longitudinal dynamic systems of the vehicle exhibit strong coupling and nonlinear characteristics, and the existing active safety systems often only focus on the stability of longitudinal or lateral motion. , without considering the mutual influence and coupling effect of other systems, it is difficult to function under extreme conditions due to control target conflict, actuator interference and other reasons. Therefore, it is necessary to carry out...

AI Technical Summary

Problems solved by technology

Most traditional control algorithms simply set the expected value of the lateral velocity to zero, or only track the yaw rate, which makes the design of the reference model not completely reasonable and affects the control performance of the controller

[0004] 2. Under extreme working conditions, the longitudinal force and lateral force of the tire will affect each other, and there is a coupling nonlinear relationship between the longitudinal and lateral force, the slip rate and the side slip angle

Most traditional control algorithms do not consider the composite slip characteristics of the tire when using the tire model to calculate the tire longitudinal and lateral force, which makes the tire force calculation inaccurate and affects the prediction model accuracy

[0005] 3. The tire slip rate is used as an index to evaluate the longitudinal stability of the vehicle. Most control methods track the tire slip rate as a state variable. Although it can be controlled, the dynamic model of this method is complex and it is difficult to set a reasonable slip rate. expectations

[0006] 4. The additional torque is a control quantity that directly affects the motion state of the vehicle. Most control methods calculate it mainly by distributing the total additional torque obtained from the solution to each wheel, ignoring that each wheel may be in a different driving / The additional torque obtained in this way is not accurate enough; or the controller is designed for each wheel according to the state quantity of each tire to obtain the additional torque, which makes the structure of the control system more complicated

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