String stability and flow stability for nonlinear vehicular platoons with actuator faults based on an improved quadratic spacing policy

This paper investigates the string stability and traffic flow stability based on an improved quadratic spacing policy for heterogeneous vehicular platoons with actuator faults. Due to the occurrence of actuator faults, the maximum acceleration changes, which may invalid the traditional quadratic spacing policy. To tackle the dilemma, an improved quadratic spacing policy with the lower bound of fault factor is proposed. Furthermore, the improved quadratic spacing policy removes the assumption of zero initial spacing errors. Then, by employing the adaptive fuzzy logic system technique and the PID-type sliding mode control method, an adaptive fuzzy fault-tolerant controller is designed to guarantee individual vehicle stability and string stability after reaching the sliding surface. In addition, traffic flow stability is also ensured thanks to the improved quadratic spacing policy. Finally, simulation results have demonstrated the reliability and effectiveness of the presented method.