Design and Control of a 1-DOF MRI Compatible Pneumatically Actuated Robot with Long Transmission Lines.
Design and Control of a 1-DOF MRI Compatible Pneumatically Actuated Robot with Long Transmission Lines.
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DOI：
10.1109/tmech.2010.2071393
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发表时间：
2011-12-01
期刊：
影响因子：
--
通讯作者：
Desai JP
中科院分区：
文献类型：
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作者：
Yang B;Tan UX;McMillan A;Gullapalli R;Desai JP
本文介绍了一种MRI兼容的1-DOF针驱动机器人的设计和控制及其精确的位置控制，采用气动驱动与长传输线。与其他成像模式（如CT或超声）相比，MRI提供了上级图像质量，但由于其强磁场，对材料和致动器的选择（以防止图像失真）施加了严格的限制。我们主要感兴趣的是开发一种在乳腺肿瘤射频消融（RFA）过程中具有大力带宽和精确靶向能力的气动驱动乳腺活检机器人，并探索使用从MRI室外部到磁体中的设备的长气动传输线的可能性，以防止任何图像失真。本文提出了一个模型的整个气动系统。气动管道近似为一阶时滞系统，因为其动力学由具有变系数和边界条件的电报方程控制，无法精确求解。长气动管线和阀门子系统的缓慢响应使得位置控制具有挑战性。这进一步由于装置中存在不均匀摩擦而变得复杂。滑模控制（SMC）被采用，其中摩擦被视为一个不确定项，以驱动系统的滑动表面。设计、开发并评估了三种不同的控制器，以实现RFA探头的精确位置控制。实验结果表明，所有的SMC都给出了令人满意的性能与长传输线。我们还使用连接到针驱动器的3-DOF光纤力传感器进行了几次实验，以评估该设备在连续成像下在MRI中的性能。
This paper presents the design and control of an MRI-compatible 1-DOF needle driver robot and its precise position control using pneumatic actuation with long transmission lines. MRI provides superior image quality compared to other imaging modalities such as CT or ultrasound, but imposes severe limitations on the material and actuator choice (to prevent image distortion) due to its strong magnetic field. We are primarily interested in developing a pneumatically actuated breast biopsy robot with a large force bandwidth and precise targeting capability during radio-frequency ablation (RFA) of breast tumor, and exploring the possibility of using long pneumatic transmission lines from outside the MRI room to the device in the magnet to prevent any image distortion whatsoever. This paper presents a model of the entire pneumatic system. The pneumatic lines are approximated by a first order system with time delay, because its dynamics are governed by the telegraph equation with varying coefficients and boundary conditions, which cannot be solved precisely. The slow response of long pneumatic lines and valve subsystems make position control challenging. This is further compounded by the presence of non-uniform friction in the device. Sliding mode control (SMC) was adopted, where friction was treated as an uncertainty term to drive the system onto the sliding surface. Three different controllers were designed, developed, and evaluated to achieve precise position control of the RFA probe. Experimental results revealed that all SMCs gave satisfactory performance with long transmission lines. We also performed several experiments with a 3-DOF fiber-optic force sensor attached to the needle driver to evaluate the performance of the device in the MRI under continuous imaging.