CLOSED–LOOP CONTROL FOR VIBRATION SUPPRESION OF A SINGLE–LINK FLEXIBLE MANIPULATOR USING COMMAND SHAPING TECHNIQUES

Abstract

In today’s fast growing world, the motivation to utilize robotic manipulators has also been actuated by the needs and demand of the industrial automation. Most of the existing manipulators were designed with maximum stiffness in order to minimize the vibrations induced within the manipulator and also to maintain the required positional accuracy. This high stiffness is achieved by using heavy materials and bulky design, which require high power consumption and have reduced speed of operations, the downside in conventional manipulators. That is where the need of flexible manipulators arise and attention is focused more towards the flexible manipulators than rigid manipulators owing to various advantages like small actuators, reduced inertia, high mobility, less power consumption, greater payload-to-robot-weight ratio, larger work volumes of such manipulators. However, how to handle structural vibrations, which are inherent with flexible manipulators, is a challenging task both in the modeling and control phase. Various research methodologies has been developed by researchers to cope with vibrations of flexible systems. In this thesis, a theoretical investigation is presented for dynamic modeling as well as vibration suppression of a single-link flexible manipulator. A mathematical model is developed on the basis of finite element method considering flexibility, inertia and damping effects in nature. The developed dynamic model is validated by comparing the results with published literature. As structural vibrations are inherent with flexible manipulators, the concept of command shaping has been utilized to minimize the vibrations. Moreover, a hybrid controller is developed, which is a combination of linear feedback control and input shaping. Simulation results on a single-link flexible manipulator demonstrate the efficacy of the proposed controller in achieving the positioned accuracy and reducing the vibration levels.