Research On High-precision Trajectory Tracking Control For Cable-Driven Parallel Robots

Different from conventional parallel robots that use rigid links to control mobile platform,cable-driven parallel robots(CDPRs)are a new type of parallel robots developed by replacing rigid links with flexible cables.The structural changes enable CDPRs to possess several advantages,including large workspace,low inertia,high load capacity,and the ability to be reconfigured according to environmental requirements.In order to solve the problems of trajectory tracking control with multi-cable coordinated motion,unmodeled dynamics and external disturbances,research on high-precision trajectory tracking control was studied.The main work in this dissertation is summarized as follows:(1)The general dynamic model of CDPRs is established,and a robust synchronization control(RSC)scheme is designed in the cable length space for high-precision trajectory tracking control.Moreover,the uniformly ultimate boundedness of the tracking error in the closed-loop system equation is proved using Lyapunov theory.Finally,the simulation and experiment of the trajectory tracking control are performed.The results show that the RSC scheme has high trajectory tracking accuracy and robustness.(2)Due to the problem of time-varying parameters for the dynamic model of the driving device and the problem of high gain introduced by the RSC scheme,a robust adaptive synchronization control(RASC)scheme is designed.The stability of the RASC scheme is proved,and experimental verification is performed on an actual CDPR.The experimental results show that the RASC scheme has high trajectory tracking accuracy and robustness.(3)In order to accelerate the convergence speed of parameter online updating,a novel composite adaptive control(CAC)scheme is designed by combining working space and cable length space,and the stability and robustness of the closed-loop system are analyzed.Finally,a trajectory tracking control simulation is designed.The simulation results show that the CAC scheme can guarantee that the parameters converge to their true value quickly and smoothly,thereby reducing the peak value of the trajectory tracking errors and accelerating the error convergence.