Friction observer and compensation for control of robots with joint torque measurement

Author

Le Tien, Luc ; Albu-Schäffer, Alin ; De Luca, Alessandro ; Hirzinger, Gerd

Author_Institution

German Aerosp. Center, Wessling

fYear

2008

fDate

22-26 Sept. 2008

Firstpage

3789

Lastpage

3795

Abstract

In this paper we introduce a friction observer for robots with joint torque sensing (in particular for the DLR medical robot) in order to increase the positioning accuracy and the performance of torque control. The observer output corresponds to the low-pass filtered friction torque. It is used for friction compensation in conjunction with a MIMO controller designed for flexible joint arms. A passivity analysis is done for this friction compensation, allowing a Lyapunov based convergence analysis in the context of the nonlinear robot dynamics. For the complete controlled system, global asymptotic stability can be shown. Experimental results validate the practical efficiency of the approach.

Keywords

Lyapunov methods; MIMO systems; asymptotic stability; compensation; friction; low-pass filters; medical robotics; observers; position control; robot dynamics; torque control; DLR medical robot; Lyapunov based convergence analysis; MIMO controller design; flexible joint arms; friction compensation; friction observer; global asymptotic stability; joint torque measurement; joint torque sensing; low-pass filtered friction torque; nonlinear robot dynamics; passivity analysis; positioning accuracy; robot control; torque control; Actuators; Frequency modulation; Friction; Joints; Observers; Robots; Torque; Friction compensation; flexible joint robots; friction observer;

fLanguage

English

Publisher

ieee

Conference_Titel

Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on

Conference_Location

Nice

Print_ISBN

978-1-4244-2057-5

Type

conf

DOI

10.1109/IROS.2008.4651049

Filename

4651049