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arXiv · 2406.07670

Design and Control of a Compact Series Elastic Actuator Module for Robots in MRI Scanners

Binghan He·Naichen Zhao·David Y. Guo·Charles H. Paxson·Alfredo De Goyeneche·Michael Lustig·Chunlei Liu·Ronald S. Fearing
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Abstract

Robotic assistance has broadened the capabilities of magnetic resonance imaging (MRI)-guided medical interventions, yet force-controlled actuators tailored for MRI environments remain limited. In this study, we present a novel MRI-compatible rotary series elastic actuator (SEA) module that employs velocity-sourced ultrasonic motors for force-controlled operation within MRI scanners. Unlike prior MRI-compatible SEA designs, our module uses a transmission force sensing SEA architecture, with four off-the-shelf compression springs placed between the gearbox and motor housings. To enable precise torque control, we develop a controller based on a disturbance observer, specifically designed for velocity-sourced motors. This controller improves torque regulation, even under varying external impedance, enhancing the actuator's suitability for MRI-guided medical interventions. Experimental validation confirms effective torque control in both 3 Tesla MRI and non-MRI settings, achieving a 5% settling time of 0.05 seconds and steady-state error within 2.5% of the actuator's maximum output torque. Notably, the controller maintains consistent performance across both low and high impedance conditions.

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Binghan He, Naichen Zhao, David Y. Guo, Charles H. Paxson, Alfredo De Goyeneche, Michael Lustig, Chunlei Liu, Ronald S. Fearing. 2024-06-11. Design and Control of a Compact Series Elastic Actuator Module for Robots in MRI Scanners. https://arxiv.org/abs/2406.07670

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