Brake And Traction Force Coordination And Active Fault Tolerant Control For Distributed Electric Vehicles

In order to improve the driving performance of distributed electric vehicles, theresearch on lateral stability and fault tolerance and the designing of related controlsystem are necessary. Focusing on the limit yaw moment generated by traction forcecoordination and the inaccuracy of traditional electric stability control system, and thereliance of fault diagnosis system to cope with limited failure modes of the existingfault-tolerant distributed control systems, brake and traction torque coordination basedon MPC and self-tuning fault-tolerant control for vehicle multiple actuator system isproposed.To improve the lateral stability under extreme conditions, brake and traction forcecoordination based on model predictive control is proposed. In this paper, based onMPC structure, the vehicle dynamics model towards predictive control is built, costfunction to trace lateral motion and multi-input multi-output system predictive controllaw is designed. Then, driver input is taken as reference, braking capacity and roadadhesion is taken as constraints, MPC system predicts the state of certain samplingperiods of the vehicle, to generate vehicle traction and brake force increments,minimizes the errors. The classical quadratic programming method andoffline-linearization online-synthesis is used for solving the receding horizon problem,and the tuning of controller parameters is done to obtain optimal control results. Then,linear matrix inequalities method is applied to improve the robustness and the stabilityis proved. For multi-actuator fault tolerant control system of distributed electric vehiclesequipped with electronic controlled steering, model-free adaptive control theory isapplied for the self-tuning active fault tolerant control system. Firstly, fault pattern isanalyzed and a system model includes steering system and motor fault condition iscreated, then measurement information and error based estimation with input constraintsis used to fulfill the controller, since, longitudinal and lateral tracking is achieved; thendecoupling longitudinal and lateral control, tuning parameters to get better results.Finally, the error convergence and bounded input and bounded output stability isproved.In order to verify the effectiveness of the control system, the development of asimulation platform based on professional vehicle model and a flexible experimental platform with distributed drive and distributed hydraulic brake is done, the simulationand experimental results show that the proposed brake and drive coordinated controlstrategy improve vehicle yaw response, expanding the range of driving stability, and theproposed self-tuning fault-tolerant control method ensures driving safety, improvesoverall vehicle tracking performance when actuators failure.