Vibration Suppression for a Flexible Link Robot Using Acceleration and/or Angular Rate Measurements and a Flatness Based Trajectory Control

Abstract

This paper focuses on trajectory control of an articulated robot with two flexible links and three joints, for a base, a shoulder and an elbow. The aim of the present contribution is to use angular rate and acceleration sensors for vibration damping instead of strain gauges measurements. Applying strain gauges for the measurements of curvatures on industrial applications is often technically difficult and expensive. Operating with model based control approaches, the equations of motion are the essential prerequisites and therefore various mathematical models and assumptions are introduced. The first model is developed assuming Euler-Bernoulli-Beams and the Ritz approach. Under the condition of small elastic deformations a second model is computed, approximating the beam elasticity with linear springs and dampers. This so called lumped element model is modified in a further step, in order to apply common flatness based approaches. With these preparations a flatness based control, consisting of a feedforward and a feedback part, is shown. The latter one uses angular rate or acceleration measurements. The proposed control strategies are finally validated by several experiments.