Fault tolerant tracking of Mars entry vehicles via fuzzy control approach
In this paper, a fault tolerant attitude tracking control scheme is proposed for Mars entry vehicles (MEVs) with disturbances and actuator failures. The original attitude dynamics of MEVs is divided into two subsystems, named as slow subsystem and fast subsystem, respectively. For slow subsystem, the control-like angular velocity command is generated. For fast subsystem, the Takagi-Sugeno (T-S) fuzzy models are used to describe it at first. Based on these, the partial loss of actuator effectiveness with the generated angular velocity problem is transformed into solving the tracking problem with uncertain parameters. Then, a fault tolerant tracking control scheme is proposed by combining fuzzy line-integral Lyapunov function method with robust H∞control approach. The proposed controller design is simple and can guarantee the faulty closed-loop system to be stable with acceptable attenuation level. Finally, the effectiveness of the proposed design method is demonstrated in a MEVs attitude control system subject to loss of actuator effectiveness.