Friction Compensation for Nonlinear Systems Based on the LuGre Model

Friction may be a major obstacle for stability and control performance. Based on a nominal control law, which stabilizes a nonlinear dynamical system to an equilibrium or to a desired limit cycle motion and which is derived without taking the friction disturbance into account, a method for compensating the impact of the friction is presented and stability analysis for the closed loop system is presented. The result can be interpreted as a nonlinear observer-based solution for the LuGre friction model with new design for the nonlinear injection function. An illustrative example is given for the Furuta pendulum