目的 针对膝-踝-趾动力型假肢系统支撑期强耦合性会导致假肢系统控制精度下降的问题,提出精确反馈线性化方法对动力型假肢系统解耦。 方法 采集人体下肢步态信息,将支撑期划分为支撑前中期和支撑末期,建立两个模态的动力学模型;使用精确反馈线性化解耦方法对支撑期假肢系统解耦,结合滑模控制设计动力型下肢假肢控制器;搭建联合仿真平台验证方法的有效性。 结果 解耦后系统相较于解耦前控制精度提高,解耦后支撑前中期膝、踝计算平均绝对误差( mean absolute error,MAE) 分别减少至 0. 001 1°、0. 002 6°,均方根误差( root meansquare error,RMSE) 分别减少至 0. 014 7°、0. 023 6°;支撑末期膝、踝、趾 MAE 分别减少至 0. 011 1°、0. 005 1°、0. 006 5°,RMSE 分别减少至 0. 021 9°、0. 021 0°、0. 012 9°,总体控制误差减少,响应速度加快,并且假肢能够在仿真环境中稳定运行。 结论 本文提出的解耦方法可有效简化下肢假肢系统的控制,并为假肢系统的进一步研究奠定基础。

Objective Aiming at the problem that the strong coupling characteristics of knee-ankle-toe active prosthesis system in stance phase will lead to the decrease in control precision of prosthesis system, the method of exact feedback linearization was proposed to decouple the active transfemoral prosthesis system. Methods Gait data of human lower limbs were collected. Stance phase was divided into the early and middle stance phase and the last stance phase. The dynamic model of two stance phases was established. The prosthesis system in stance phase was decoupled based on exact feedback linearization decoupling. The integral sliding mode controller was designed to control the active transfemoral prosthesis. The co-simulation platform was built to verify effectiveness of the method. Results The decoupled system could improve the control accuracy. After decoupling, the calculated mean absolute error (MAE ) of knee and ankle in the early and middle stance phase was reduced to 0.001 1 ° and 0.002 6°respectively. Root mean square error ( RMSE ) was reduced to 0.014 7°and 0.023 6° respectively. At the last stance phase, the MAE of knee, ankle and toe was reduced to 0.011 1°,0.005 1° and 0.006 5° respectively, and the RMSE was reduced to 0.021 9°,0.021 0° and 0.012 9° respectively. The overall control error was reduced and the response speed was accelerated, and the prosthesis could operate stably in the co-simulation environment. Conclusions The decoupling method proposed in this study can effectively realize the decoupling of the transfemoral prosthesis system and lay the foundation for the prosthetic system.

国家重点研发计划项目(2022YFC2009504,2021YFC0122704),国家自然科学基金青年项目( 61803143),河北省高等学校科学技术研究项目(QN2020252),河北省自然科学基金项目(F2021202021)