Adaptive control techniques for friction compensation

We design two adaptive controllers for a second-order mechanical system which incorporates frictional effects such as Coulomb, static, Stribeck, and viscous friction. First, we design a modular position tracking controller that can accommodate a variety of adaptive update laws. The proposed controller is shown to compensate for uncertainty associated with the friction parameters which appear linearly in the model. In the second control scheme, we show how a Lyapunov-based adaptive position setpoint controller can be designed to compensate for parametric uncertainty throughout the mechanical system including the Stribeck effect related constant which does not appear linearly in the model. Experimental results are provided to illustrate the performance of the proposed controllers