Nonlinear H∞ controller for flexible joint robots with using feedback linearization

Abstract -This paper proposes a new approach to feedback linearization of flexible link robots which have uncertain modeling. The flexibility of joints is performed by use of the solenoid nonlinear springs, which have damper property. The simplified nonlinear H∞ controller is used to control linearized flexible link robots. The new continues and smooth model of frictions is used for modeling the dynamics of flexible robots. The effect of parameters tolerance, external disturbances and also other nonlinearities are expressed by a nonlinear independent term in linearized dynamics. Simulation results demonstrate that the proposed feedback linearization with simplified nonlinear H∞ controller has ability to control flexible joint robots with a good performance. Also it is more efficient than the NL-H∞ based controller with nonlinear dynamics. This technique can be used to control the other nonlinear systems which have the dynamics similar to flexible joint robots.