基于指令滤波的柔性关节空间机器人固定时间轨迹跟踪控制

Command Filter Based Fixed-time Trajectory Tracking Control for Flexible-joint Space Robots

  • 摘要: 针对受到外部扰动和存在模型不确定性的柔性关节自由飞行空间机器人在运动过程中易产生弹性振动,导致机械臂末端控制精度降低的问题,提出了一种非奇异固定时间指令滤波反步控制方法。首先,针对反步控制中虚拟控制律多次求导造成的“计算爆炸”问题,采用了一种固定时间指令滤波器来获取虚拟控制律导数。进一步为消除指令滤波器引起的滤波误差,提出了一种非奇异固定时间滤波误差补偿算法,以提高系统的跟踪精度。基于李雅普诺夫稳定性理论设计了指令滤波反步控制器,该控制器能够保证系统的跟踪误差在固定时间内收敛到原点。仿真结果表明,所设计的控制器具有较快的收敛速度和较高的跟踪精度。

     

    Abstract: To resolve the susceptibility of flexible-joint free-flying space robots to elastic vibrations during motion owing to external disturbances and model uncertainties, which decrease control accuracy at the end of the manipulator, we propose a nonsingular fixed-time command filtering backstepping control method. Firstly, to avoid the “explosion of complexity” caused by the recursive differentiation of the virtual control law for backstepping, we utilize a fixed-time command filter to obtain the derivative of the desired virtual control law and its derivatives. Furthermore, to eliminate the filtering errors generated by the command filter, we propose a nonsingular fixed-time filtering error compensation algorithm to improve the tracking accuracy of the system. Subsequently, we present a command filtering backstepping tracking controller based on Lyapunov's stability theory, ensuring that the proposed controller can facilitate the convergence of system tracking errors to the origin within a fixed time. The simulation results demonstrate that the designed nonsingular fixed-time command filtering backstepping controller exhibits high convergence speed and tracking accuracy.

     

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