基于观测器和全局收缩映射的设定点控制

在没有速度测量和重力无法精确补偿条件下,研究了并联机器人的设定点控制。利用线性观测器理论对速度信号进行观测,设计了带有速度近似的比例拟微分(PD-proportion pseudo derivative) 有偏标称重力补偿的设定点控制方法。该控制器只能得到全局有偏稳定的控制结果。借助全局收缩映射定理,定义了参数修正算法,利用系统静差对观测器参数进行在线地重复修正,得到全局渐进稳定的控制效果。该观测器不需要系统模型,控制器-观测器结构简单,易于实用。对六自由度并行机器人的仿真实验表明:选择不同的设计参数可以获得不同收敛速度和输出震颤,但都能够确保系统输出收敛到标称点。

Set-point control based on an observer and globally contraction mapping

A set-point controller was developed for a parallel manipulator with unknown parameters when only the position signals are available.A linear observer was used to reconstruct the velocity signals.This pseudo velocity was the used in a set-point controller using P(proportion pseudo derivative) plus estimated nominal gravity compensation which guarantees that the closed-loop system is globally stable.The algorithm modifies the observer parameter using contraction mapping to compensate for steady-state positioning errors due to estimates of the gravitational term.Every time the system reaches steady state,the observer parameter is iteratively adjusted to provide globally asymptotic stability.Simulations with a 6 degree of freedom parallel manipulator demonstrate that various parameter values will lead to different convergence velocities and output vibrations,as the controller ensures that the system outputs converge into arbitrarily small neighborhoods of the desired equilibrium point.