Ningbo Research Institute, Zhejiang University, Ningbo 315100, China.
School of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China.
Sensors (Basel). 2020 Dec 16;20(24):7216. doi: 10.3390/s20247216.
With the help of wearable robotics, the lower limb exoskeleton becomes a promising solution for spinal cord injury (SCI) patients to recover lower body locomotion ability. However, fewer exoskeleton gait planning methods can meet the needs of patient in real time, e.g., stride length or step width, etc., which may lead to human-machine incoordination, limit comfort, and increase the risk of falling. This work presents a human-exoskeleton-crutch system with the center of pressure (CoP)-based gait planning method to enable the balance control during the exoskeleton-assisted walking with crutches. The CoP generated by crutches and human-machine feet makes it possible to obtain the overall stability conditions of the system in the process of exoskeleton-assisted quasi-static walking, and therefore, to determine the next stride length and ensure the balance of the next step. Thus, the exoskeleton gait is planned with the guidance of stride length. It is worth emphasizing that the nominal reference gait is adopted as a reference to ensure that the trajectory of the swing ankle mimics the reference one well. This gait planning method enables the patient to adaptively interact with the exoskeleton gait. The online gait planning walking tests with five healthy volunteers proved the method's feasibility. Experimental results indicate that the algorithm can deal with the sensed signals and plan the landing point of the swing leg to ensure balanced and smooth walking. The results suggest that the method is an effective means to improve human-machine interaction. Additionally, it is meaningful for the further training of independent walking stability control in exoskeletons for SCI patients with less assistance of crutches.
在可穿戴机器人的帮助下，下肢外骨骼成为脊髓损伤 (SCI) 患者恢复下肢运动能力的一种很有前途的解决方案。然而，很少有外骨骼步态规划方法能够实时满足患者的需求，例如步长或步宽等，这可能导致人机不协调、限制舒适度并增加跌倒的风险。本工作提出了一种带有人-外骨骼-拐杖系统的压力中心 (CoP) 步态规划方法，以在外骨骼辅助拐杖行走过程中实现平衡控制。拐杖和人机脚产生的 CoP 使得在外骨骼辅助准静态行走过程中获得系统整体稳定性条件成为可能，从而确定下一步的步长并确保下一步的平衡。因此，外骨骼步态是在步长指导下进行规划的。值得强调的是，采用标称参考步态作为参考，以确保摆动脚踝的轨迹很好地模拟参考轨迹。这种步态规划方法使患者能够自适应地与外骨骼步态进行交互。对五名健康志愿者进行的在线步态规划行走测试证明了该方法的可行性。实验结果表明，该算法可以处理感测信号并规划摆动腿的着陆点，以确保平衡和平稳的行走。结果表明，该方法是提高人机交互的有效手段。此外，对于需要较少拐杖辅助的 SCI 患者进一步训练外骨骼独立行走稳定性控制也具有重要意义。
