Design and Control of a Compact Series Elastic Actuator Module for Robots in MRI Scanners
<|reference_start|>Design and Control of a Compact Series Elastic Actuator Module for Robots in MRI Scanners: In this study, we introduce a novel MRI-compatible rotary series elastic actuator module utilizing velocity-sourced ultrasonic motors for force-controlled robots operating within MRI scanners. Unlike previous MRI-compatible SEA designs, our module incorporates a transmission force sensing series elastic actuator structure, with four off-the-shelf compression springs strategically placed between the gearbox housing and the motor housing. This design features a compact size, thus expanding possibilities for a wider range of MRI robotic applications. To achieve precise torque control, we develop a controller that incorporates a disturbance observer tailored for velocity-sourced motors. This controller enhances the robustness of torque control in our actuator module, even in the presence of varying external impedance, thereby augmenting its suitability for MRI-guided medical interventions. Experimental validation demonstrates the actuator's torque control performance in both 3 Tesla MRI and non-MRI environments, achieving a settling time of 0.1 seconds and a steady-state error within 2% of its maximum output torque. Notably, our force controller exhibits consistent performance across low and high external impedance scenarios, in contrast to conventional controllers for velocity-sourced series elastic actuators, which struggle with steady-state performance under low external impedance conditions.<|reference_end|>
@article{he2024design,
    title={Design and Control of a Compact Series Elastic Actuator Module for
  Robots in MRI Scanners},
    author={Binghan He, Naichen Zhao, David Y. Guo, Charles H. Paxson, and Ronald
  S. Fearing},
    journal={arXiv preprint arXiv:2406.07670},
    year={2024},
    archivePrefix={arXiv},
    eprint={2406.07670},
    primaryClass={cs.RO}
}