Flatness based GPI control for flexible robots

Abstract

In this article, a new method to control a flexible robotic arm using a conventional direct current (DC) motor with a gear actuator strongly affected by non-linear friction torque is proposed. This control method does not require friction compensation and hence the estimation of this term because the control scheme is robust with respect to this effect. In addition, the only variables to measure are the motor shaft and tip angular positions. Velocity measurements, which always introduce errors and noises, are not required. The use of filters to estimate velocities and bounded derivatives are not needed. The Generalized Proportional Integral GPI controller is designed using a two-stage design procedure entitling an outer loop, designed under the assumption of no motor dynamics, and subsequently an inner loop which forces the motor response to track the control input position reference trajectory derived in the previous design stage. Velocity measurements, which always introduce errors and noises, are not required. Experimental results are presented. © Springer Science+Business Media B.V. 2009.