Abstract
Background: Needle insertion is commonly used in minimally invasive surgery. Cannula flexible needle, as one of the insertion needles is composed of a flexible cannula and a flexible stylet, both of which need to be driven independently. The coordination control of both motions can achieve a variety of 3D insertion paths according to recent patents.
Objective: This paper is to innovatively design an insertion mechanism for the cannula flexible realizing the coordinated motions of both the cannula and the stylet.
Methods: Based on the analysis of the required degrees of freedom and motion models of the cannula flexible needle, the general scenario of the insertion mechanism was designed by using TRIZ theory. The condition for achieving the linear insertion path was obtained based on the analysis and calculation of the screw motion by using the screw theory.
Results: The general scenario of the insertion mechanism was innovatively obtained, the spiral slide and the cross linear slide were adopted, and furthermore, the parameters of the spiral slide were determined, along with the design of cross linear slide. At last, the virtual prototype was achieved.
Conclusion: In this paper, the TRIZ theory was used to innovatively design an insertion mechanism for the cannula flexible needle, and both the general scenario and the concrete parts were achieved. The result showed rationality of the designed insertion mechanism fulfilling all the requirements for the cannula flexible needle.
Keywords: Cannula flexible needle, insertion mechanism, motion analysis, mechanical design, TRIZ, minimally invasive surgery.
Graphical Abstract