A two-layered control for backlash compensation and oscillation suppression in ball screw drives

Backlash in ball screw drives causes torque loss and engagement impact during motion reversal, resulting in tracking errors and oscillations. Existing compensation methods, which treat backlash as a lumped disturbance, fail to balance fast estimation and smooth compensation, leading to delayed or abrupt responses. This study introduces a two-layered composite control structure for backlash-affected ball screw drives, featuring a torque-loss compensation layer and an oscillation-damping layer to enhance tracking accuracy and suppress reversal oscillations. The backlash transition process is divided into three phases. Theoretical analysis demonstrates that tracking errors primarily occur in the first and third phases due to torque loss, while oscillations occur in the second phase due to engagement impact. A continuous prediction method for backlash transitions employs motor-side position increments after velocity reversal to achieve accurate phase switching and torque compensation. A combined backlash–friction feedforward strategy is developed to compensate for torque losses, while an extended state observer (ESO)-based controller rejects residual disturbances. An oscillation-damping layer with velocity-difference feedback suppresses engagement-induced vibrations, and a back-propagation artificial neural network characterizes position-dependent backlash using laser interferometer measurements. Comparative motion and milling tests validate the effectiveness of the proposed approach.