Optimal Input Design for Fault Identification of Overactuated Electric Ground Vehicles

Abstract

The design of optimal input for fault identification in electric ground vehicles (EGVs) that use four independent in-wheel motors and four-wheel steering is presented in this paper. As the number of motors and steering actuators increases beyond the number of controlled variables, an EGV becomes an overactuated system, which provides actuator redundancy and the possibility of fault-tolerant control in the case of faults that occur in vehicle elements, such as its sensors and actuators. To ensure the reliability of the EGV during driving, online fault identification is needed, and its performance is directly dependent on the input signals. The input can be designed using the control allocation method, which is one approach to manage actuator redundancy. The proposed control allocation maximizes the sensitivity of the system output to parameters related to the fault position, while the system output is simultaneously controlled to maintain stability and follow the desired vehicle motions, even when faults occur. Simulations using the commercial software CarSim are performed to show the effectiveness of the proposed optimal input design method for fault identification; the performance of the system is compared with the conventional white noise perturbation input with equal power.