SUMMARYAccurate torque control is a critical issue in the compliant human–robot interaction scenario, which is, however, challenging due to the ever-changing human intentions, input delay, and various disturbances. Even worse, the performances of existing control strategies are limited on account of the compromise between precision and stability. To this end, this paper presents a novel high-performance torque control scheme without compromise. In this scheme, a new nonlinear disturbance observer incorporated with equivalent control concept is proposed, where the faster convergence and stronger anti-noise capability can be obtained simultaneously. Meanwhile, a continuous fractional power control law is designed with an iteration method to address the matched/unmatched disturbance rejection and global finite-time convergence. Moreover, the finite-time stability proof and prescribed control performance are guaranteed using constructed Lyapunov function with adding power integrator technique. Both the simulation and experiments demonstrate enhanced control accuracy, faster convergence rate, perfect disturbance rejection capability, and stronger robustness of the proposed control scheme. Furthermore, the evaluated assistance effects present improved gait patterns and reduced muscle efforts during walking and upstair activity.

中文翻译：

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具有延迟变化输入的柔性辅助外骨骼的连续有限时间扭矩控制

摘要准确的扭矩控制是顺从的人机交互场景中的一个关键问题，然而，由于不断变化的人类意图、输入延迟和各种干扰，这具有挑战性。更糟糕的是，现有控制策略的性能由于精度和稳定性之间的折衷而受到限制。为此，本文提出了一种不折不扣的新型高性能转矩控制方案。在该方案中，提出了一种结合等效控制概念的新型非线性扰动观测器，可以同时获得更快的收敛速度和更强的抗噪声能力。同时，利用迭代方法设计了连续分数功率控制律，以解决匹配/不匹配干扰抑制和全局有限时间收敛问题。而且，有限时间稳定性证明和规定的控制性能是使用构造的Lyapunov函数和增加功率积分器技术来保证的。仿真和实验都证明了所提出的控制方案具有更高的控制精度、更快的收敛速度、完美的抗扰能力和更强的鲁棒性。此外，评估的辅助效果在步行和上楼活动期间改善了步态模式并减少了肌肉力量。