Feed-forward friction observer (FFFO) for high-dynamic motion control

The dynamic friction in motion systems is mostly not directly measurable and has to be observed for an efficient compensation. A novel feed-forward friction observer (FFFO) is proposed based on the two-state dynamic friction model with elasto-plasticity abbreviated by 2SEP friction model. Being involved in the underlying closed control loop the FFFO uses the control error to adjust the friction dynamics which is computed in feed-forwarding based on the reference velocity. The friction compensation is evaluated on the actuated motion system with multiple coupled frictional surfaces. The proposed FFFO approach proves to be superior in comparison to the common friction observer which uses the output velocity value.