Robotics Research Center, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, Singapore.
Ann Biomed Eng. 2020 Jun;48(6):1837-1849. doi: 10.1007/s10439-020-02495-z. Epub 2020 Mar 30.
In flexible endoscopy, the endoscope needs to be sufficiently flexible to go through the tortuous paths inside the human body and meanwhile be stiff enough to withstand external payloads without unwanted tip bending during operation. Thus, an endoscope whose stiffness can be adjusted on command is needed. This paper presents a novel variable-stiffness manipulator. The manipulator (Ø15 mm) has embedded thermoplastic tubes whose stiffness is tunable through temperature. Temperature is adjusted through joule heat generated by the electrical current supplied to the stainless steel coils and an active air-cooling mechanism. Tests and modeling were conducted to characterize the performance of the design. The manipulator has a high stiffness-changing ratio (22) between rigid and flexible states while that of its commercial Olympus counterpart is only 1.59. The active cooling time is 11.9 s while that of passive ambient cooling is 100.3 s. The thermal insulation layer (Aerogel) keeps the temperature of the outer surface within the safe range (below 41 °C). The models can describe the heating and cooling processes with root mean square errors ranging from 0.6 to 1.3 °C. The results confirm the feasibility of a variable-stiffness endoscopic manipulator with high stiffness-changing ratio, fast mode-switching, and safe thermal insulation.
在软性内窥镜中，内窥镜需要足够的柔韧性以通过人体内部的曲折路径，同时又需要足够的刚性以在操作过程中承受外部负载而不会出现不必要的尖端弯曲。因此，需要一种能够根据指令调整刚度的内窥镜。本文介绍了一种新型的可变刚度操纵器。该操纵器（Ø15 毫米）内部嵌入了热塑性管，其刚度可以通过温度进行调节。通过对不锈钢线圈施加电流产生焦耳热，并采用主动风冷机制来调节温度。进行了测试和建模以表征设计的性能。该操纵器在刚性和柔性状态之间具有很高的刚度变化比（22），而其商业竞争对手奥林巴斯的刚度变化比仅为 1.59。主动冷却时间为 11.9 秒，而被动环境冷却时间为 100.3 秒。隔热层（气凝胶）将外表面的温度保持在安全范围内（低于 41°C）。模型可以描述加热和冷却过程，均方根误差在 0.6 到 1.3°C 之间。结果证实了具有高刚度变化比、快速模式切换和安全隔热的可变刚度内窥镜操纵器的可行性。
