The Effect of coulomb friction and stiction on force control

We have studied the effect of Coulomb friction and stiction on force control with integral feedback. The force is applied through a compliant transmission by a velocity-controlled motor. Our results show that stiction can cause the applied force to enter a limit cycle. Coulomb friction can extend the system stability bounds but may lead to an input-dependent stability. Under certain conditions Coulomb friction causes an actuator limit cycle even though the applied force approaches the desired steady state force. Based on the analysis, we give design guidelines for increasing the performance.