Stochastic evaluation of dissipative observer for multivalued nonlinear system with Coulomb friction

In this paper, using the stochastic friction approximation, we present a simulation model of a multivalued system in order to validate the performance of the observer for the 2-cart system with Coulomb friction as a multivalued system proposed by Osorio et al.. We show that the stochastic approximation of the multivalued function affects the estimation performance and it is impossible to estimate the friction force near the zero velocity. Finally, we design the adaptive update law to estimate the Coulomb sliding friction force.