Nasiri Rezvan, Dinovitzer Hannah, Manohara Nirosh, Arami Arash
Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, Canada.
Toronto Rehabilitation Institute (KITE), University Health Network, Toronto, ON, Canada.
PLoS One. 2025 Jan 22;20(1):e0292334. doi: 10.1371/journal.pone.0292334. eCollection 2025.
Lower-limb exoskeletons have demonstrated great potential for gait rehabilitation in individuals with motor impairments; however, maintaining human-exoskeleton coordination remains a challenge. The coordination problem, referred to as any mismatch or asynchrony between the user's intended trajectories and exoskeleton desired trajectories, leads to sub-optimal gait performance, particularly for individuals with residual motor ability. Here, we investigate the virtual energy regulator (VER)'s ability to generate coordinated locomotion in lower limb exoskeleton. Contribution: (1) In this paper, we experimented VER on a group of nine healthy individuals at different speeds (0.6m/s - 0.85m/s) to study the resultant gait coordination and naturalness on a large group of users. (2) The resultant assisted gait is compared to the natural and passive (zero-torque exoskeleton) walking conditions in terms of muscle activities, kinematic, spatiotemporal and kinetic measures, and questionnaires. (3) Moreover, we presented the VER's convergence proof considering the user contribution to the gait and introduced a metric to measure the user's contribution to gait. (4) We also compared VER performance with the phase-based path controller in terms of muscle effort reduction and joint kinematics using three able-bodied individuals. Results: (1) The results from the VER demonstrate the emergence of natural, coordinated locomotion, resulting in an average muscle effort reduction ranging from 13.1% to 17.7% at different speeds compared to passive walking. (2) The results from VER revealed improvements in all indicators towards natural gait when compared to walking with a zero-torque exoskeleton, for instance, an enhancement in average knee extension ranging from 3.9 to 4.1 degrees. All indicators suggest that the VER preserves natural gait variability and user engagement in locomotion control. (3) Using VER also yields in 13.9%, 15.1%, and 7.0% average muscle effort reduction when compared to the phase-based path controller. (4) Finally, using our proposed metric, we demonstrated that the resultant locomotion limit cycle is a linear combination of human-intended limit cycle and the VER's limit cycle. These findings may have implications for understanding how the central nervous system controls our locomotion.
下肢外骨骼已在运动功能受损个体的步态康复中展现出巨大潜力；然而，维持人与外骨骼的协调性仍是一项挑战。这种协调问题，即用户预期轨迹与外骨骼期望轨迹之间的任何不匹配或不同步，会导致步态表现欠佳，尤其是对于仍有残余运动能力的个体。在此，我们研究虚拟能量调节器（VER）在下肢外骨骼中产生协调运动的能力。贡献：（1）在本文中，我们让一组九名健康个体以不同速度（0.6米/秒 - 0.85米/秒）对VER进行实验，以研究大量用户群体所产生的步态协调性和自然度。（2）将所产生的辅助步态在肌肉活动、运动学、时空和动力学指标以及问卷调查方面与自然和被动（零扭矩外骨骼）行走条件进行比较。（3）此外，我们给出了考虑用户对步态贡献的VER收敛证明，并引入了一种衡量用户对步态贡献的指标。（4）我们还使用三名身体健全的个体，在肌肉用力减少和关节运动学方面将VER性能与基于相位的路径控制器进行比较。结果：（1）VER的结果表明出现了自然、协调的运动，与被动行走相比，在不同速度下平均肌肉用力减少了13.1%至17.7%。（2）与零扭矩外骨骼行走相比，VER的结果显示所有指标都朝着自然步态有所改善，例如，平均膝关节伸展增加了3.9至4.1度。所有指标表明VER保留了自然步态变异性以及用户在运动控制中的参与度。（3）与基于相位的路径控制器相比，使用VER还能使平均肌肉用力分别减少13.9%、15.1%和7.0%。（4）最后，使用我们提出的指标，我们证明所产生的运动极限环是人类预期极限环和VER极限环的线性组合。这些发现可能对理解中枢神经系统如何控制我们的运动具有启示意义。
