We have designed, developed, and evaluated the performance of a multi-degree-of-freedom discretely actuated steerable cannula with shape-memory alloy (SMA) actuators. This will enable us to deliver diagnostic as well as therapeutic devices to the target location through the hollow inner core of the cannula. We propose to use SMAs to generate bending forces due to its small size and high power density. We annealed the SMA wires through a customized training process in an arc shape and mounted them at discrete locations on the outer surface of the cannula to enable joint motion. A pulse-width modulation (PWM)-based control scheme was implemented to control all SMA actuators simultaneously to enable multiple joint motion using a single power supply. The proposed controller was validated through an experiment inside gelatin to mimic the motion of the cannula inside a medium which requires a significant amount of force to move the joints of the cannula. Trajectory planning using a suitable metric and trajectory execution were successfully implemented. To demonstrate the delivery of a diagnostic tool through our cannula, we demonstrate that we can pass an optical coherence tomography probe through the cannula and perform in situ microscale imaging.

中文翻译：

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迈向用于诊断和治疗程序的离散驱动的可操纵套管

我们设计、开发并评估了具有形状记忆合金 (SMA) 致动器的多自由度离散致动可操纵套管的性能。这将使我们能够通过套管的中空内核将诊断和治疗设备输送到目标位置。由于其小尺寸和高功率密度，我们建议使用 SMA 来产生弯曲力。我们通过定制的弧形训练过程对 SMA 线进行退火，并将它们安装在套管外表面的离散位置，以实现关节运动。实施了基于脉宽调制 (PWM) 的控制方案，以同时控制所有 SMA 执行器，以使用单个电源实现多个关节运动。建议的控制器通过明胶内部的实验得到验证，以模拟插管在介质内的运动，这需要大量的力来移动插管的关节。成功实施了使用合适度量和轨迹执行的轨迹规划。为了演示通过我们的套管提供诊断工具，我们证明我们可以通过套管传递光学相干断层扫描探针并进行原位微尺度成像。