IEEE Access (Jan 2021)
MAS-Based Slip Ratio Fault-Tolerant Control in Finite Time for EV
Abstract
The driving torques of all four wheels of distributed drive electric vehicles are independently controllable, and acceleration slip regulation (ASR) can be realized through the coordinated effort of torque actuators. Considering the multiple actuator coupling, nonlinearity, uncertainty and actuator faults in an ASR system, an adaptive nonsingular terminal sliding mode (NTSM) fault-tolerant control method-based multi-agent system (MAS) is proposed to address the above problems of an ASR system in this paper. First, based on multi-agent theory, a four- wheel independent drive ASR system is decomposed into four separate driving wheel agent systems to reduce the model dimension and transform the design of the ASR system controller into the design of a single driving wheel agent controller to reduce the computational complexity. Second, to address the unknown uncertainty of an actuator fault in an ASR system, an adaptive NTSM controller for a single driving wheel agent is designed to make the actual slip ratio track the ideal slip ratio for the ASR system in finite time. The controller switch item gains are selected by using an adaptive estimation mechanism for a single driving wheel agent controller to address the gain overestimation problem. This approach ensures that the actual control signal is smooth and that chattering phenomena and energy consumption are reduced. For actuator faults, a Lyapunov function based on multiagent theory is designed for a single driving wheel agent to avoid the impact of the coupling subsystem fault. Third, the Simulink and CarSim cosimulation results show that the proposed method improves the fault tolerance and robustness. The system can realize the actual slip ratio, track the optimal slip ratio in a finite time under different road adhesion conditions and effectively avoid the wheel slippage problem.
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