Accessible Torque Bandwidth of a Series Elastic Actuator Considering the Thermodynamic Limitations

TL;DR

This paper investigates the thermodynamic limitations affecting the torque bandwidth of a series elastic actuator and proposes an adaptive control method to improve torque accessibility, demonstrated on a robotic actuator.

Contribution

It introduces a thermodynamic model for the actuator and an adaptive control strategy to enhance torque bandwidth considering thermal effects.

Findings

Thermodynamic limitations restrict torque bandwidth.

Adaptive control improves torque bandwidth accessibility.

Case study validates the proposed methodology.

Abstract

Within the scope of the paper, electromechanical and thermodynamic models are derived for a series elastic actuator and open loop and closed loop torque bandwidth parameters are analysed considering the thermodynamic behaviour of the actuator. It was observed that the closed loop torque bandwidth of the electromechanical subsystem of the actuator was not accessible in the entire torque reference amplitude range due to thermodynamic limitations. Therefore, a stator winding temperature estimation based adaptive controller is utilised and analysed to improve the accessibility of the controller based torque bandwidth. This paper implements the methodology on a HEBI Robotics X5-9 actuator as a case study.