Magnetic resonance (MR)-guided interventional robots have recently been developed for a variety of surgeries, such as biopsy, ablation, and brachytherapy. The actuators and encoders that power and track such robots must be MR conditional. In this paper, we propose an MR-conditional pneumatic motor with an integrated and custom-built fiber-optical encoder that provides powerful and accurate actuation. The motor is coupled with a modular plastic gearbox that provides a variety of gear ratio options so that the motor can be adapted to application requirements. With a 100:1 gear reduction at 0.55 MPa, the motor achieves 460 mN⋅m stall torque and 370 r/min no-load speed, which leads to the peak output power of 6 W. The motor has the bandwidth of approximately 1.1 and 3.5 Hz when connected to 8 and 0.2 m air hoses, respectively. The motor was tested in a 3T magnetic resonance imaging (MRI) scanner. No image artifact was observed and maximum signal-to-noise ratio (SNR) variation was less than 5%. Different from most of the existing MR-conditional pneumatic actuators, the proposed motor shape is more like the traditional electric motors, which offers more flexibility in the MR-conditional robot design.

中文翻译：

---

用于 MR 条件机器人应用的气动电机的表征和控制

磁共振（MR）引导的介入机器人最近已被开发用于各种手术，例如活检、消融和近距离放射治疗。为此类机器人提供动力和跟踪的执行器和编码器必须具有 MR 条件。在本文中，我们提出了一种带有集成定制光纤编码器的 MR 条件气动电机，可提供强大而准确的驱动。该电机与模块化塑料齿轮箱相结合，提供多种齿轮比选项，使电机能够适应应用要求。通过 0.55 MPa 下的 100:1 齿轮减速，电机可实现 460 mN·m 的堵转扭矩和 370 r/min 的空载转速，从而实现 6 W 的峰值输出功率。电机的带宽约为 1.1，分别连接到 8 和 0.2 m 空气软管时为 3.5 Hz。该电机在 3T 磁共振成像 (MRI) 扫描仪中进行了测试。未观察到图像伪影，最大信噪比 (SNR) 变化小于 5%。与大多数现有的 MR 条件气动执行器不同，所提出的电机形状更像传统的电动机，这为 MR 条件机器人设计提供了更大的灵活性。