Influence and compensation of Coulomb friction in industrial pointing and tracking systems

Simple stability conditions are specified for an elastic two-mass system with Coulomb friction. From these conditions linear and nonlinear stabilizing and compensating measures are derived and verified by simulation and with an electrically driven setup with adjustable parameters. A reference model polynomial state control for the linear position controlled system is described, which is distinguished by good robustness against parameter variations and short computing time. This control scheme ensures a stick-slip-free operation down to lowest speeds and standstill. The generally valid methods and results apply to position and force controlled robots and robot grippers, and to machine tools, antennas, telescopes, etc.<>