Purpose

This paper aims to propose a novel system design and control algorithm of lower limb exoskeleton, which provides walking assistance and load sharing for the wearer.

Design/methodology/approach

In this paper, the valve-controlled asymmetrical hydraulic cylinder is selected for driving the hip and knee joint of exoskeleton. Pressure shoe is developed that purpose on detecting changes in plantar force, and a fuzzy recognition algorithm using plantar pressure is proposed. Dynamic model of the exoskeleton is established, and the sliding mode control is developed to implement the position tracking of exoskeleton. A series of prototype experiments including benchtop test, full assistance, partial assistance and loaded walking experiments are set up to verify the tracking performance and power-assisted effect of the proposed exoskeleton.

Findings

The control performance of PID control and sliding mode control are compared. The experimental data shows the tracking trajectories and tracking errors of sliding mode control and demonstrate its good robustness to nonlinearities. sEMG of the gastrocnemius muscle tends to be significantly weakened during assisted walking.

Originality/value

In this paper, a structure that the knee joint and hip joint driven by the valve-controlled asymmetrical cylinder is used to provide walking assistance for the wearer. The sliding mode control is proposed to deal with the nonlinearities during joint rotation and fluids. It shows great robustness and frequency adaptability through experiments under different motion frequencies and assistance modes. The design and control method of exoskeleton is a good attempt, which takes positive impacts on the productivity or quality of the life of wearers.

中文翻译：

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基于液压执行器的下肢外骨骼设计及初步评价

目的

本文旨在提出一种新颖的下肢外骨骼系统设计和控制算法，为佩戴者提供行走辅助和负载分担。

设计/方法论/途径

本文选用阀控非对称液压缸来驱动外骨骼的髋关节和膝关节。开发了以检测足底力变化为目的的压力鞋，并提出了一种利用足底压力的模糊识别算法。建立了外骨骼的动力学模型，并开发了滑模控制来实现外骨骼的位置跟踪。为了验证所提出的外骨骼的跟踪性能和助力效果，进行了一系列原型实验，包括台式测试、完全辅助、部分辅助和负载行走实验。

发现

比较了PID控制和滑模控制的控制性能。实验数据显示了滑模控制的跟踪轨迹和跟踪误差，并证明了其对非线性的良好鲁棒性。腓肠肌的表面肌电图在辅助行走过程中往往会显着减弱。

原创性/价值

本文采用阀控非对称气缸驱动膝关节和髋关节的结构为佩戴者提供行走辅助。提出滑模控制来处理关节旋转和流体过程中的非线性。通过不同运动频率和辅助模式下的实验，显示出良好的鲁棒性和频率适应性。外骨骼的设计和控制方法是一个很好的尝试，它对佩戴者的生产力或生活质量产生了积极的影响。