Experiment on vibration control of a two-link flexible manipulator using an input shaper and adaptive positive position feedback

Zhongyi Chu,Jing Cui

doi:10.1177/1687814015610466

Abstract

This article presents a novel approach for actively suppressing the vibration within a two-link flexible manipulator to adapt the variation in the model parameters, which is composed of an input shaper and multimode adaptive positive position feedback. Input shaper is applied to shape the command to avoid the flexible vibration in the manoeuvre motion, and the residual vibration can be suppressed by a piezo actuator with the adaptive positive position feedback approach. To demonstrate the approach, two sets of piezoelectric actuator/stain gauge sensor pairs are bonded to the surface of the two-link flexible manipulator; slewing of the flexible link induces vibrations in the link that persist long after the motors stop moving. Vibration suppression is achieved through a combined scheme of input shaper–based motor motion control and an adaptive positive position feedback–based piezo actuator controller. Experimental results show the effectiveness of the proposed approach and its suitability for implementation in an existing robot.

Highlights

Compared with rigid manipulator systems, flexible parts provide a series of advantages in terms of lower overall mass and safer operation due to reduced inertia, faster system response, lower energy consumption, relatively smaller actuators and so on.[1]
We focus on simultaneous positioning and vibration suppression for a two-link flexible manipulator driven by linear motors and surface-bonded piezoelectric actuators
40 ms 110 ms seen that since the proposed approach for active suppression vibration can adapt the variation in the model parameters exactly, compared with only input shaper or adaptive positive position feedback (APPF) approach, it can avoid the flexible vibration in the manoeuvre motion and suppress the residual vibration effectively (Figure 10)

Summary

Introduction

Compared with rigid manipulator systems, flexible parts provide a series of advantages in terms of lower overall mass and safer operation due to reduced inertia, faster system response, lower energy consumption, relatively smaller actuators and so on.[1]. To enhance the flexible link’s vibration damping property, additional sensors and actuators can be applied; in this area, research has been intensifying over the past two decades regarding active vibration control methods for structures using smart materials, such as piezo ceramic (PZT) actuators bonded to the flexible link, suppressing link vibrations through the control of PZT actuators,[7] resulting in more effective vibration damping control Many control strategies such as velocity feedback, neural networks, genetic algorithms, adaptive control and fuzzy control have been reported by various researchers; among them, positive position feedback (PPF) is essentially a second-order filter, which has been shown to be an effective vibration control method for the flexible systems embedded with smart materials.[8,9] to apply PPF, the natural frequencies of the system must be determined exactly; otherwise, if the systematic parameters are poorly known or have varied due to, such as, the presence of the unmodelled dynamics, the effect of the PPF will be worsen.[10] A few forms of adaptive PPF have been developed for flexible structures,[11,12] which vary in the way they are implemented. Qffiffiffiffiffiffiffiffiffiffiffiffi4ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi p3Sffiffi2ffiffiffiÀffiffiffiffi(ffiffiXffiffiffiAffiffiffiÀffi XB)[2] L2 À ZJ 3 ZJ1

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Experimental study

Conclusion