Henselmans Paul Wj, Gottenbos Stefan, Smit Gerwin, Breedveld Paul
Department of BioMechanical Engineering, Delft University of Technology, Delft, The Netherlands.
Proc Inst Mech Eng H. 2017 Dec;231(12):1213-1223. doi: 10.1177/0954411917740388. Epub 2017 Nov 10.
Follow-the-leader propagation allows for the insertion of flexible surgical instruments along curved paths, reducing the access required for natural orifice transluminal endoscopic surgery. Currently, the most promising follow-the-leader instruments use the alternating memory method containing two mechanical memory-banks for controlling the motion of the flexible shaft, which reduces the number of actuators to a minimum. These instruments do, however, require concentric structures inside the shaft, limiting its miniaturization. The goal of this research was, therefore, to develop a mechanism conforming the principles of the alternating memory method that could be located at the controller-side instead of inside the shaft of the instrument, which is positioned outside the patient and is therefore less restricted in size. First, the three-dimensional motion of the shaft was decoupled into movement in a horizontal and vertical plane, which allowed for a relatively simple planar alternating memory mechanism design for controlling planar follow-the-leader motion. Next, the planar movement of the alternating memory mechanism was discretized, increasing its resilience to errors. The resulting alternating memory mechanism was incorporated and tested in a proof-of-concept prototype called the Memo Slide. This prototype does not include a flexible shaft, but was fully focused on proving the function of the alternating memory mechanism. Evaluation of the Memo Slide shows the mechanism to work very well, being able to transfer any planar path that lays within its physical boundaries along the body of the mechanism without accumulating errors.
跟随式传播允许沿着弯曲路径插入柔性手术器械，减少了经自然腔道内镜手术所需的操作空间。目前，最有前景的跟随式器械采用包含两个机械记忆库的交替记忆方法来控制柔性轴的运动，这将致动器的数量减至最少。然而，这些器械在轴内部需要同心结构，限制了其小型化。因此，本研究的目标是开发一种符合交替记忆方法原理的机构，该机构可以位于控制器端而非器械轴内部，控制器位于患者体外，因此在尺寸上限制较少。首先，将轴的三维运动解耦为水平和垂直平面内的运动，这使得能够设计相对简单的平面交替记忆机构来控制平面跟随式运动。接下来，将交替记忆机构的平面运动离散化，提高其抗误差能力。所得的交替记忆机构被整合到一个名为Memo Slide的概念验证原型中并进行测试。该原型不包括柔性轴，而是完全专注于证明交替记忆机构的功能。对Memo Slide的评估表明该机构运行良好，能够沿着机构主体传递位于其物理边界内的任何平面路径而不累积误差。
