Design of a Modular Rotary Actuator Characterization Test Station for Wearable Robotics

This paper presents the development of a benchtop actuator test platform designed to advance actuator design and performance for wearable robotic systems (e.g., powered prosthesis and exoskeletons). Designing actuators to assist human movement, it is critical to validate their performance to ensure safety and effectiveness. Custom designed actuators require rigorous testing prior to clinical deployment to reduce long term costs and safety risks. To address this need, we developed a Modular Rotary Actuator Characterization Test Station capable of performing static and dynamic tests with measuring real-time angular velocity and torque to evaluate high performance wearable robot actuators. In this initial evaluation, we characterized a metal planetary gearbox transmission with an attached brushless DC motor and evaluated the test station measurement capabilities. Such testing included actuator performance output of sinusoidal angular velocity at 0.25 Hz to evaluate a root mean square error of 0.95±0.03 rad/s. Further, an actuation torque output versus command current, to achieve a best fit linear regression of actuator control input-output relationship through the test station (r<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> = 0.997,n = 48,p << 0.001). These results demonstrate that the system produces reliable data consistent with other benchmark actuator test stations. In all, this platform establishes a practical and scalable framework for actuator validation, and enable characterization of actuator dynamics to optimize active wearable robotic actuators for improving human rehabilitation performance.