Design and Experimental Characterisation of a Novel Quasi-Direct Drive Actuator for Highly Dynamic Robotic Applications

This paper presents the design and experimen- tal results of a proprioceptive, high-bandwidth quasi-direct drive (QDD) actuator for highly dynamic robotic applications. A comprehensive review of the mechanical design of the PULSE115-60 actuator is presented, with particular focus on the design parameters affecting the dynamic performance of the actuator and a full specification is provided. Fundamental parameters to describe the dynamic behaviour of an actuator are discussed, and an experimental method to determine speed and torque bandwidth of the actuator is presented. A rigorous method to determine backdrive torque is also explained. Finally, experimental results quantifying the dynamic performance of the PULSE115-60 actuator are discussed. The PULSE115-60 actuator has a highly dynamic response, surpassing the torque bandwidth at low torque amplitudes showcased in state-of- the-art literature. The differences between current and torque bandwidth, two concepts often conflated in literature, are elucidated. Experimental procedures detailed in previous work are discussed and a novel standardised procedure is proposed for robust characterisation and fair comparison of different actuation systems. Finally, performance results for PULSE115- 60 are presented, demonstrating a torque bandwidth of 66.3 Hz at an amplitude of 6 N·m, ±0.11◦of backlash and 0.37 N·m of backdrive torque.