Conception, design and development of a low-cost intelligent prosthesis for one-sided transfemoral amputees

Introduction Modern transfemoral knee prostheses are designed to offer comfort and self-confidence to amputees. These prostheses are mainly based upon either a passive concept, with a damping system, or an active computational intelligent design to control knee motion during the swing phase. In Brazil, most lower extremity amputees are unable to afford modern prostheses due to their high cost. In this work, we present the conception, design and development of a low-cost intelligent prosthesis for one-sided transfemoral amputees. Methods The concept of the prosthesis is based on a control system with sensors for loads, which are installed on the amputee’s preserved leg and used as a mirror for the movement of the prosthesis. Mechanical strength analysis, using the Finite Element Method, electromechanical tests for the sensors and actuators and verification of data acquisition, signal conditioning and data transferring to the knee prosthesis were performed. Results The laboratory tests performed showed the feasibility of the proposed design. The electromechanical concept that was used enabled a controlled activation of the knee prosthesis by the two load cells located on the shoe sole of the preserved leg. Conclusions The electromechanical design concept and the resulting knee prosthesis show promising results concerning prosthesis activation during walking tests, thereby showing the feasibility of a reduced manufacturing cost compared to the modern prostheses available on the market.

引言：现代经股膝关节假肢旨在为截肢者提供舒适体验与自信心。此类假肢主要分为两类设计方案：一类为搭载阻尼系统的被动式设计，另一类为采用主动计算智能架构以控制摆动阶段膝关节运动的主动式设计。在巴西，多数下肢截肢者因现代假肢成本高昂而无力负担购置费用。本研究针对单侧经股截肢者，提出一款低成本智能假肢的构思、设计与开发方案。
方法：该假肢的设计理念基于一套搭载载荷传感器的控制系统：传感器安装于截肢者的健侧肢体，用于作为假肢运动的镜像参照，实现动作同步。本研究开展了有限元法（Finite Element Method）机械强度分析、传感器与执行器机电性能测试，并对数据采集、信号调理以及向膝关节假肢传输数据的流程进行了验证。
结果：本次开展的实验室测试证实了所提设计方案的可行性。所采用的机电设计理念，可通过健侧鞋底搭载的两个称重传感器，实现膝关节假肢的可控激活。
结论：该机电设计理念及所研制的膝关节假肢，在步行测试中的假肢激活效果表现优异，证实了其相较于市售现代假肢可显著降低制造成本的可行性。