Identification of a Lumped-Parameter-Model for a Dual-Motor Robotic Drive Train with Backlash and Electrical Preload

The mechanical interface of rotating robot joints require torque to speed ratios that are not suitable for an elec-tromagnetic direct drive. Typically, gearboxes are used to convert torque and speed, although these introduce non-linear backlash into the system. By using a dual-motor drive train, it is possible to electrically preload the gearbox and compensate for the backlash. In order to describe the system dynamics, a lumped-parameter-model is presented for which the parameters are determined to represent an experimental setup. Measurements are carried out in various coupling scenarios and the associated parameters of the subsystems of the models are identified. The measurement and the model are further adapted through optimization. Based on the evaluated transfer functions, the model is able to describe the basic behavior of the system. The measurements with coupled motors and activated preload indicate persistent differences from the actual system. However, the presented model may be applied in simulation and control to improve the dynamics of a dual-motor robot drive train with backlash-prone gearing and the possibility of electrical preload.