Frication compensation and disturbance observer design for a high acceleration precision direct drive motion stage

Friction compensation and disturbance observer design in velocity loop for a high acceleration precision motion stage actuated by linear motor is considered. The friction compensator divides the friction into linear and nonlinear part basing on LuGre model, linear part is treated as damping together with other part in system, and nonlinear part is compensated basing on the model. Internal state z in LuGre model is calculated according model and position real time instead of using state observer, which can reduce calculation and as far as possible to ensure the precision of friction model. The disturbance observer proposed here account for time delay in system which caused by discrete sampling, signal process, transport distance, and so on. Simulation results demonstrate the effectiveness of the approach.