Finite-time And Fault-tolerant Control For H-type Gantry Stage

H-type truss robots have been widely used in industrial processing and warehouse fields due to their advantages such as simple structure,ease of operation,large operating range,and strong versatility.However,with the increasing complexity and variability of social demands and operating condition,the existing automation level of H-type truss robots gradually cannot meet the requirements.Improving the transient and steady-state performance,as well as the fault-tolerant capability for these systems have become hot topics of research at present.On one hand,the control system of H-type truss robot has nonlinear system characteristics,including nonlinear dynamics,nonlinear friction,nonlinear coupling,etc.,which will increase the difficulty of robot control.Meanwhile,different operating environments can bring unpredictable external disturbances to the system.These uncertainties create great challenges to the improvement of the transient and steady-state performance of the system.On the other hand,the H-type truss robot often operates for long-time,inevitably causing actuator wear,stuck and other failures.How to ensure the stable operation of the system within the preset performance indicators when failures occur is also a huge challenge.The main content of this thesis is to design the corresponding control strategy for the uncertain H-truss robot system to obtain excellent transient and steady state performance and fault-tolerant control ability.The main research work of the thesis is as follows:(1)A continuous finite-time control strategy based on time-delay estimation(TDE)is proposed for the uncertain H-type truss robot system.Firstly,a time-delay estimator is constructed to reduce the impact of system uncertainties.Secondly,a continuous nonsingular terminal sliding mode controller is designed using a terminal sliding surface to handle the estimation error caused by the time-delay estimator.Thirdly,a continuous finitetime control strategy is given by combining the time-delay estimator and the nonsingular terminal sliding mode controller.Finally,based on the Lyapunov stability theory,sufficient conditions for implementing the continuous finite-time control of the H-type truss robot system are given,and it is theoretically proved that all signals of the closed-loop system are ultimately bounded in finite time.(2)A PID-like finite-time fault-tolerant control strategy is proposed for the uncertain H-type truss robot system.Firstly,a time function with adjustable convergence is designed,whose convergence time,range and rate can be adjusted by parameters.Secondly,the generalized tracking error is defined,the PID-like controller is constructed,and the adaptive rate of the gain parameters is designed to solve the influence of system uncertainty.Next,based on reasonable actuator fault assumptions,a finite-time fault-tolerant control strategy is designed to make the control system obtain excellent fault-tolerant control ability.Finally,based on the Lyapunov stability theory,sufficient conditions for implementing finite-time fault-tolerant control of the H-type truss robot system are given,and it is theoretically proved that all signals of the closed-loop system are ultimately bounded in finite time.