IEEE Int Conf Rehabil Robot. 2022 Jul;2022:1-6. doi: 10.1109/ICORR55369.2022.9896599.
Insufficient push-off is a common problem for stroke hemiplegia patients. Assistive systems using extension spring to store energy during stance phase of gait to provide push-off assistance have been developed. However, patients could also suffer poor ankle rocker function; that is, poor dorsiflexion movement in stance phase. In such case, the spring could reversely become a burden for ankle movement. In this research, we proposed a system that combines a pneumatic artificial muscle and a tension spring. The artificial muscle mimics a human's tibialis anterior muscle, while the spring mimicking the Achilles tendon. Upon foot flat event of gait, the artificial muscle contracted to assist ankle rocker function and stretched the spring to store energy simultaneously. After heel off, the artificial muscle extended and the spring was released to provide push-off assistance. A feasibility study in seven healthy participants was conducted to verify assistance effects on their ankle rocker function and push-off movements. The results show significant increase in ankle rocker angle, push-off angle, and push-off torque compared with those during normal walk when the participants were assisted by our system. Therefore, we believe that the proposed system has great potential to assist stroke survivors with problems of poor ankle rocker function and push-off movements.
足蹬力不足是脑卒中偏瘫患者的常见问题。为了在步行的支撑相提供足蹬助力，已经开发出了利用拉伸弹簧在步态支撑相储存能量的助行系统。然而，患者也可能存在踝关节跖屈功能不良的情况，即在支撑相时，背屈运动不佳。在这种情况下，弹簧可能会对踝关节运动造成反作用。在这项研究中，我们提出了一种结合气动人工肌肉和拉力弹簧的系统。人工肌肉模拟了人类的胫骨前肌，而弹簧则模拟了跟腱。在步态的足底接触事件中，人工肌肉收缩以辅助踝关节跖屈功能，并同时拉伸弹簧以储存能量。在脚跟离地后，人工肌肉伸展，弹簧释放，提供足蹬助力。我们对七名健康参与者进行了可行性研究，以验证该系统对他们的踝关节跖屈功能和足蹬运动的辅助效果。结果表明，与参与者在正常行走时相比，当他们被我们的系统辅助时，踝关节跖屈角度、足蹬角度和足蹬扭矩显著增加。因此，我们相信，所提出的系统具有很大的潜力，可以帮助患有踝关节跖屈功能不良和足蹬运动问题的脑卒中幸存者。
