Investigations of a Robotic Testbed with Viscoelastic Liquid Cooled Actuators

TL;DR

This paper introduces a novel viscoelastic liquid cooled actuator (VLCA) designed for robotics, demonstrating high efficiency, torque density, impact resistance, and precise control through extensive design, material analysis, and experimental validation.

Contribution

The paper presents the design, analysis, and testing of a new VLCA with enhanced performance metrics and a robotic system capable of high payload lifting and precise impedance control.

Findings

VLCA achieves high energy efficiency and torque density.

The robotic testbed can lift 32.5 kg payloads and perform precise trajectory control.

The system demonstrates robustness against impacts and external forces.

Abstract

We design, build, and thoroughly test a new type of actuator dubbed viscoelastic liquid cooled actuator (VLCA) for robotic applications. VLCAs excel in the following five critical axes of performance: energy efficiency, torque density, impact resistence, joint position and force controllability. We first study the design objectives and choices of the VLCA to enhance the performance on the needed criteria. We follow by an investigation on viscoelastic materials in terms of their damping, viscous and hysteresis properties as well as parameters related to the long- term performance. As part of the actuator design, we configure a disturbance observer to provide high-fidelity force control to enable a wide range of impedance control capabilities. We proceed to design a robotic system capable to lift payloads of 32.5 kg, which is three times larger than its own weight. In addition, we experiment with Cartesian trajectory control up to 2 Hz with a vertical range of motion of 32 cm while carrying a payload of 10 kg. Finally, we perform experiments on impedance control and mechanical robustness by studying the response of the robotics testbed to hammering impacts and external force interactions.