Fault Tolerant Control in a Semi-Active Automotive Suspension

A new active Fault Tolerant Controller (FTC) is proposed for an automotive semi-active suspension, by considering a quarter of vehicle model. The design is composed by: (1) a robust non-linear controller used to isolate vibrations into the vehicle caused by external disturbances and (2) a mechanism of compensation used to accommodate additive faults in the damping force. The compensation mechanism uses a robust fault detector, based on parity space, to estimate the fault; this information allows the computation of the compensation signal by using the inverse dynamics of a damper model to reduce the fault effect into the vertical dynamics of the suspension. The non-linear controller, based on the Linear Parameter-Varying (LPV) control theory, is designed to increase the passengers comfort and ensure the wheel-road contact. When a fault occurs in the damping force, the active FTC must hold the performances of comfort and road holding by using the interaction between the LPV controller and the compensatory module. Simulation results in CarSimTM show the effectiveness of the proposed active FTC versus a passive FTC and an uncontrolled damper; the passive FTC needs to include all faults into its design for having a good fault-tolerant capability, while the proposed active FTCimproves a 50.4% in comfort and 42.4% in road holding when a fault occurs, in contrast with the uncontrolled damper that loses completely its effectiveness