Adaptive PID fault-tolerant control with output constraints for flexible space robotic arms considering the influence of gravity
This paper proposes an output constrained adaptive proportional integral derivative ( PID) fault-tolerant control strategy based on singular perturbation to address the trajectory tracking problem of space flexible robotic arms with actuator faults. Using the method and principle of singular perturbation,the control system of a space flexible robot-ic arm is decoupled into fast and slow subsystems. The slow subsystem control strategy treats actuator faults as an unknown control direction problem with fixed symbols but not fixed sizes,and uses the Nussbaum function to handle this problem,while using the barrier Lyapunov function ( BLF) to constrain the output;add a damping term to the fast subsystem to suppress oscillations. The stability of the control strategy has been proven using Lyapunov func-tions and related theorems. The simulation results show that when the system is affected by actuator faults and var-ying gravitational accelerations,the control strategy can enable the flexible space manipulator to accurately track the target trajectory.
space robotic armsingular perturbationadaptiveNussbaum functionbarrier Lyapunov function(BLF)fault-tolerant control
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