Active vibration control of an equipment mounting link for an exploration robot

Abstract

This research seeks a practical, reliable and effective solution to the problem of nuisance vibrations experienced within robot systems. This research suggests a potential application of a thin, lightweight camera mounting arm on a robot manipulator for use during search and rescue missions and exploration. Envisioning the robot arm mounted upon a drone or a rover vehicle, the control system will need to be both small and lightweight. The environment for such an application is likely to be dangerous, and as such the chosen components should be inexpensive and easily maintainable. Thus, components were selected whilst considering these constraints. The utilisation of piezoelectric sensors and actuators has been driven by their desirable electro-mechanical properties and their almost negligible influence on the functionality of a system. However, their inclusion within the control system, which applies control proportionally to the sensors, produced an interesting response from the closed loop system. This work builds upon previous research through the observation and understanding of this response, which proves to be more akin to proportional-derivative control. The electro-mechanically coupled analytical model of the link and surface mounted sensors/actuators, that is developed in this paper using Euler-Bernoulli Beam theory, provides insight into this unconventional response. This analytical model of the link structure in addition to a kinematic model of the robot are validated through their representation of experimental results. A comparison of the designed controlled system with a purpose-built alternative has been conducted to observe the performance of the former justifying the exchange of processing capacity for lower mass and cost. Through this comparison the effect of the control system parameters on the proportional-derivative response of the closed loop system is further explored. Finally, the effectiveness of the designed control system is observed when the link is mounted upon the manipulator for an array of excitation types.