Analysis Design and Control of a Stiffness-Tunable 3-DOF Elastomeric Bearing Positioning Stage

Abstract

A 3-DOF Y-θX-θZ rubber bearing stage with stiffness-adjustment capability is designed realized and controlled in this work The stiffness of rubbers can be adjusted easily by adding a pre-compression Base on elastomeric mechanics analysis the stiffness of rubber and therefore dynamic characteristics of the stage can be changed with such a preload In comparison with positioning stages designed by compliance mechanism approach such characteristics could be an opportunity to improve the performance by replacing compliant bearing with rubber-bearing one The effect of different pre-compression displacement on dynamics characteristics of the stage such as stiffness natural frequency damping ratio have been tested The dynamic testing results show that with a compression of 0 6mm on a 1 5mm thick rubber the stiffness and natural frequency increased to 140% and 118% in Y-axis and even to 280% and 168% in θ_Z-axis respectively Associated PID and integral sliding mode controllers are then implemented for characterizing the position control performance Currently the rubber bearing stage can achieve 253Hz 110Hz and 128Hz control bandwidths by using integral sliding mode control (ISMC) with decoupled compensator respectively in Y-θX and θZ axes motion With adjusting stiffness of the rubber bearing the stage can reach the control bandwidths 307Hz 114Hz and 166Hz in Y-θX-θZ axis The application of stiffness-tunable mechanism in rubber bearing stage can be taken as reference for precision positioning technology in the future

Date of Award	2020
Original language	English
Supervisor	Kuo-Shen Chen (Supervisor)