Feedback Control Design for Robust Comfortable Sit-to-Stand Motions of 3D Lower-Limb Exoskeletons
Feedback Control Design for Robust Comfortable Sit-to-Stand Motions of 3D Lower-Limb Exoskeletons
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DOI：
10.1109/access.2020.3046446
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
M. E. Mungai;J. Grizzle
中科院分区：
文献类型：
--
作者：
M. E. Mungai;J. Grizzle
下肢外骨骼为遭受下肢障碍的人提供了站立和行动的机会，这是下limb外骨骼的至关重要的任务，因为它允许用户从轮椅上转移到外骨骼上并且可以成为行走的先驱。通过使用约束优化来成功实现安全的坐姿动作，以更改用户特征和用户的环境。 。基于程序的计算机控制器，以实现静坐运动，并安全地停止站立位置。出于身体动机的鲁棒性测试。 （ZMP），摩擦和联合约束。
Lower-limb exoskeletons provide people who suffer from lower limb impairments with an opportunity to stand up and ambulate. Standing up is a crucial task for lower-limb exoskeletons as it allows the user to transfer to the exoskeleton from a wheelchair, with no assistance, and can be a precursor to walking. Achieving a safe sit-to-stand motion for the exoskeleton + user system can be challenging because of the need to balance user comfort while respecting hardware bounds and being robust to changes in the user characteristics and the user’s environment. We successfully achieve safe sit-to-stand motions by using constrained optimization to generate two types of dynamic sit-to-stand motions based on two hybrid system descriptions for the exoskeleton, Atalante. Due to the highly constrained nature of the equations of motions, we introduce a method to systematically design virtual constraints for highly constrained systems. We also design two quadratic program-based computed-torque controllers to achieve the sit-to-stand motion and to safely come to a stop in a standing position. We then analyze the closed-loop behaviors of the two sit-to-stand motions under the two controllers using physically motivated robustness tests. The criteria used to determine a successful sit-to-stand motion are: tracking error, the pitch acceleration of the torso, the amount of user force needed to perform the motion, and the adherence to the Zero Moment Point (ZMP), friction, and joint constraints.