Command Generation for Flexible Systems by Input Shaping and Command Smoothing

摘要

Aggressive motions are often discouraged when a system has flexible dynamics. Common practice suggests that smooth commands, such as S-curves, should be used to drive the system. However, smooth commands cannot be implemented on some actuators, such as the on/off thrusters used on spacecraft or on/off valves used with hydraulics and pneumatics. Furthermore, smooth commands can lead to sluggish response. A rigorous comparison of smooth and nonsmooth reference commands is presented in this paper. The evaluation is performed by treating smooth command profiles as input-shaped functions. Input shaping is a method of reducing residual vibration by convolving a sequence of impulses with a baseline reference command. By interpreting smooth commands as input-shaped functions, a common criterion for comparing smooth and nonsmooth commands is developed. The results of this comprehensive comparison indicate that input-shaped step functions are usually more efficient for reducing vibration than commonly used smooth commands. A portable tower crane is used to experimentally verify the comparison between input-shaped and smooth commands.