Over the last few decades, the appearance of robot applications has been continuously increasing in rehabilitation treatment due to the increasing numbers of stroke patients. In this paper, a novel fractional-order active fault-tolerant controller (FOAFTC) based on an adaptive nonlinear observer is proposed to detect, estimate, and compensate faults of a knee joint orthosis. The controlling term is derived based on the fractional-order sliding mode control (FOSMC) approach, while the switching term of this controller is designed by the fractional-order interval type-2 fuzzy logic control (IT2FLC) technique. In this regard, a nonlinear disturbance observer (NDO) is combined with this controller to estimate the muscular torque inserted by the patient, while increasing the accuracy and speed of the system performance. Adopting the Lagrange equations, a unique model is presented for the orthosis and the human lower-limb. The proposed strategy reduces modeling difficulties and the chattering phenomenon of the SMC technique. Additionally, the number of rules in the fuzzy controller is decreased as well. Following on, the closed-loop system stability is proved theoretically. Finally, the system performance based on the suggested controller is evaluated and compared with the results of two other different controllers including the conventional SMC and the fractional-order terminal sliding mode controller. Implying the proposed controller to the system leads to the smaller frequency and magnitude of the chattering effects, which provides more convenience for patients. Moreover, the efficiency of the suggested controller is illustrated in the presence of both actuator and sensor faults.

在过去的几十年中，由于中风患者数量的增加，机器人在康复治疗中的应用一直在不断增加。本文提出了一种基于自适应非线性观测器的新型分数阶主动容错控制器（FOAFTC），用于检测，估计和补偿膝关节矫形器的故障。该控制项是基于分数阶滑模控制（FOSMC）方法得出的，而该控制器的切换项是通过分数阶间隔2型模糊逻辑控制（IT2FLC）技术设计的。在这方面，非线性干扰观测器（NDO）与该控制器结合在一起，可以估算患者插入的肌肉扭矩，同时提高系统性能的准确性和速度。采用拉格朗日方程，针对矫形器和人类下肢提出了一个独特的模型。所提出的策略减少了建模技术的难度，并降低了SMC技术的抖动现象。另外，模糊控制器中的规则数量也减少了。随后，从理论上证明了闭环系统的稳定性。最后，评估基于建议控制器的系统性能，并将其与其他两个不同控制器（包括常规SMC和分数阶终端滑模控制器）的结果进行比较。将建议的控制器暗示给系统会导致颤振效果的频率和幅度较小，从而为患者提供了更多便利。此外，在存在执行器和传感器故障的情况下，说明了所建议控制器的效率。