本研究對於膝下殘肢曲面修改的部分，提出以曲面偏置的方法來修改。為了接近義肢設計師實際修改的狀況，將偏置後的曲面修剪後，再以曲面縫合的方法將修改區域與非修改區域曲面縫合，來完成膝下殘肢曲面修改。
以往義肢承筒的製作多仰賴義肢設計師手工完成，不僅費時，製程也無法重複。若以逆向工程的技術導入義肢承筒的設計過程，除了可以省去製作殘肢石膏模型的繁複步驟，還可以為截肢者建立永久性的數位資料，當截肢者有需要再製作新的義肢承筒時，只需由義肢師單方面製作即可。
以逆向工程技術進行義肢承筒設計時，需透過3D雷射掃描取得殘肢點資料，並用逆向工程軟體重建殘肢曲面，同時針對受壓區/非受壓區的需求作修改。惟使用逆向工程的程序複雜，若無專業技術的人員來操作，義肢設計師較難獨立完成義肢承筒的設計。本研究提出之曲面修改方法，經由實際案例驗證後，將整合至義肢承筒設計自動化系統中。

In this research, a proposed algorithm of surface offset is used to modify the CAD surface models of blow-knee residual limbs. In order to approach the real conditions of modifying the gypsum models of residual limbs by a prosthetist, trim off the offset surface and stitch both the modified region and non-modified region of the CAD surface model.
Traditionally, the fabricating process of a prosthesis socket depends on the manual technique of prosthetist. It is not only time-consuming, but the fabricating process can’t be repeated. If the technique of the reverse engineering is used to aid the designing and fabricating process of the prosthesis sockets, the complicated steps of obtaining gypsum models of residual limbs will be simplified and the perpetual digital data of amputees’ residual limbs will be kept. When there is a need to make a new prosthesis socket for a specific amputee, the prosthetist can fabricate a new one only by the digitized information.
While starting to fabricate the prosthesis socket base on reverse engineering technique, it is necessary to get the data points of the residual limb by 3D laser scanning, then construct the CAD surface model by using an appropriate software, and last modify the regions within the pressure-tolerant and pressure-relief areas. However, shape modification is complicated and needs a specialized person with expertise of operating reverse engineering software. It is hard to request only the prosthetist to accomplish this job. The proposed algorithm of surface modification in this research is verified by a case study, and then integrated into the Prosthesis Socket Design Automated System.

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