Active Control of Configuration-Dependent Linkage Vibration with Application to a Planar Parallel Platform

A new lightweight planar parallel platform aims to greatly improve operational speed of electronic manufacturing process and to realize a “smart parallel platform” through the integration of a parallel mechanism architecture, new sensing techniques and active vibration control using Lead Zirconate Titanate (PZT) transducers. Experiments using an accelerometer, an impact hammer, and PZT transducers are performed to accomplish Experimental Modal Analysis (EMA), which has not been thoroughly investigated on flexible mechanisms. Through EMA, vibration characteristics of flexible linkages, when the platform is stationary and in motion, are modeled, with configuration-dependent vibration observed. Based on assumptions made in EMA, a modal control strategy using constant mode shapes is designed to control configuration-dependent linkage vibration. Active vibration control experimental results, showing a 40%-50% reduction of vibration amplitudes, validate the effectiveness of the control strategy. This control strategy will be generalized to achieve configuration-dependent vibration control, hence realizing a true smart parallel platform.