Automobile transverse and longitudinal stability cooperative control method under extreme working condition

Abstract

The invention discloses an automobile transverse and longitudinal stability cooperative control method under an extreme working condition. The method comprises the steps: obtaining a four-wheel-hub-motor-driven electric automobile model through simulation software CarSim; designing a two-degree-of-freedom reference model, and deriving expected values of a lateral speed and a yaw velocity of the automobile through a two-degree-of-freedom reference model; adopting a double-layer control structure to reduce the solving complexity, employing an NMPC controller for the upper layer to ensure that transverse and longitudinal stability of the automobile is used as a control target, and carrying out optimized solution by considering transverse and longitudinal safety constraints to obtain virtual control variables, namely expected values of a tire slip rate and a slip angle; and finally, acquiring an additional torque acting on the hub motor according to the deviation between the actual slip rate and slip angle of the tire and the expected value given by the upper layer. Therefore, the transverse and longitudinal stability of the vehicle is ensured.

Description

technical field [0001] The present invention relates to a method for synergistic control of lateral and longitudinal stability of automobiles under extreme working conditions. More specifically, the present invention aims at the problem that four-wheel hub-driven electric vehicles are prone to instability in lateral and longitudinal movements under extreme working conditions. In the framework of model predictive control Next, a cooperative 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 very easy to lose stability and cause traffic accidents. At this time, the vehicle's transverse and longitudinal dynamics system presents strong coupling nonlinear characteristics, while the existing active safety systems often only focus on the stability of longitudinal or lateral motion. , without ...

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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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