Time-varying input shaping technique applied to vibration reduction of an industrial robot

It is widely and frequently observed that industrial robots conducting fast motion involve serious residual vibration, the period of which varies with time. To address this time-varying residual vibration problem, this paper presents a practical solution based on a time-varying input shaping technique (TVIST). First, to suppress the time-varying vibration, a guideline for designing a practical TVIST is presented. Following the guideline, a TVIST for a heavy 6 DOF industrial robot is designed. In doing so, a simple yet effective equation is derived from robot dynamic equations to schedule the time-varying period. Furthermore, a simple payload-adaptation scheme is also included. Then, experiments are performed by using the TVIST for the industrial robot under spatial motion and payload variation. The experimental results show that the residual vibration is reduced to less than 14% of the original level in magnitude and the time delay caused by pre-filtering is shortened, demonstrating the efficiency and effectiveness of the proposed TVIST.