Lower limb exoskeleton robot (LLER) can help patients with lower limb paralysis to carry out effective rehabilitation training. However, LLER is a kind of nonlinear system with the strong dynamic coupling between joints and the parameter perturbation following different poses of the robot. They will damage the control performance in the process of trajectory tracking. To solve these problems, a novel control strategy, Mass-Gravity modal space sliding mode control (M-GMSSMC), is proposed. The objective for this paper is to develop a novel decoupling control framework for an electrical actuators driven LLER to track a predefined gait trajectory. The controller design aims to improve trajectory tracking accuracy, reduce dynamic coupling between hip joint and knee joint and weaken the chattering phenomenon of the sliding mode controller. The decoupling condition and the robust stability condition are analyzed in this work. Experimental results validate the correctness of the presented conclusions and show the effectiveness of the proposed M-GMSSMC.

下肢外骨骼机器人（LLER）可以帮助下肢瘫痪患者进行有效的康复训练。然而，LLER 是一种非线性系统，关节之间具有很强的动态耦合，并且随着机器人的不同姿态而参数扰动。它们会在轨迹跟踪过程中损害控制性能。为了解决这些问题，提出了一种新的控制策略，即质量重力模态空间滑模控制（M-GMSSMC）。本文的目标是为电动执行器驱动的 LLER 开发一种新颖的解耦控制框架，以跟踪预定义的步态轨迹。控制器设计旨在提高轨迹跟踪精度，减少髋关节和膝关节之间的动态耦合，减弱滑模控制器的抖动现象。本文分析了解耦条件和鲁棒稳定性条件。实验结果验证了所提出结论的正确性，并表明了所提出的 M-GMSSMC 的有效性。