Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System, Yanshan University, Qinhuangdao 066004, China.
Academy for Engineering & Technology, Fudan University, Shanghai 200433, China.
Sensors (Basel). 2022 Oct 12;22(20):7746. doi: 10.3390/s22207746.
A stroke is a common disease that can easily lead to lower limb motor dysfunction in the elderly. Stroke survivors can effectively train muscle strength through leg flexion and extension training. However, available lower limb rehabilitation robots ignore the knee soft tissue protection of the elderly in training. This paper proposes a human-robot cooperative lower limb active strength training based on a robust admittance control strategy. The stiffness change law of the admittance model is designed based on the biomechanics of knee joints, and it can guide the user to make force correctly and reduce the stress on the joint soft tissue. The controller will adjust the model stiffness in real-time according to the knee joint angle and then indirectly control the exertion force of users. This control strategy not only can avoid excessive compressive force on the joint soft tissue but also can enhance the stimulation of quadriceps femoris muscles. Moreover, a dual input robust control is proposed to improve the tracking performance under the disturbance caused by model uncertainty, interaction force and external noise. Experiments about the controller performance and the training feasibility were conducted with eight stroke survivors. Results show that the designed controller can effectively influence the interaction force; it can reduce the possibility of joint soft tissue injury. The robot also has a good tracking performance under disturbances. This control strategy also can enhance the stimulation of quadriceps femoris muscles, which is proved by measuring the muscle electrical signal and interaction force. Human-robot cooperative strength training is a feasible method for training lower limb muscles with the knee soft tissue protection mechanism.
中风是一种常见的疾病，容易导致老年人下肢运动功能障碍。中风幸存者可以通过腿部屈伸训练有效地锻炼肌肉力量。然而，现有的下肢康复机器人在训练过程中忽略了老年人膝关节软组织的保护。本文提出了一种基于鲁棒导纳控制策略的人机协作式下肢主动力量训练方法。该方法根据膝关节生物力学设计导纳模型的刚度变化规律，可以引导使用者正确发力，减少对关节软组织的压力。控制器将根据膝关节角度实时调整模型刚度，从而间接控制使用者的施力。这种控制策略不仅可以避免对关节软组织的过度压缩力，还可以增强股四头肌的刺激。此外，还提出了一种双输入鲁棒控制方法，以提高在模型不确定性、交互力和外部噪声干扰下的跟踪性能。通过对 8 名中风幸存者进行的控制器性能和训练可行性实验表明，所设计的控制器可以有效地影响交互力，降低关节软组织损伤的可能性。机器人在干扰下也具有良好的跟踪性能。通过测量肌肉电信号和交互力，证明了该控制策略还可以增强股四头肌的刺激。人机协作力量训练是一种具有膝关节软组织保护机制的下肢肌肉训练的可行方法。
