Modelling of a Dual-Motor Robotic Drive with Estimation, Preload, and Guidance of Backlash

Inhalt:
The dynamic behavior regarding gearing backlash is investigated for the application as a joint-drive in an articulated industrial robot equipped with a milling spindle. A dual-motor capable of electrical preload of drive train is presented and a lumped parameter model of dynamics is derived. The equations are presented as a switching state-space system depending on the contact state of backlash play. Based on the system description, an estimator is developed in order to obtain information about current backlash position. During a passage of backlash, caused by a change of torque, the adaptive preload control law according to the state of the art is not capable of improving dynamics resulting from the impact of closing the backlash gap. An additional guidance control is presented and implemented ensuring a smooth transition. The proposed design is validated by a dynamic simulation demonstrating the functionality and improvement of dynamics.