Toward Lower Limbs Functional Rehabilitation Through a Knee-Joint Exoskeleton

Abstract

This paper presents a bounded control strategy of a knee-joint exoskeleton that ensures knee flexion/extension movements during the assistance and rehabilitation processes. The control strategy is easy to implement, since it does not require any prior knowledge of the human effort. The proposed control law is based on nested saturations with the main advantage of explicitly avoiding the actuator's saturation, guaranteeing and enhancing the wearer's security. Lyapunov-based analysis is stated to prove: 1) the asymptotic stability of the shank-foot-exoskeleton in the absence of a human active effort; 2) the trajectories ultimate boundedness in the presence of parameter uncertainties; and 3) the input-to-state stability with respect to a bounded human active torque. Preliminary realtime experiments show satisfactory results in terms of assistanceas-needed and passive/resistive rehabilitation performances following desired trajectories expressing knee flexion/extension movements.

A Review on Human–exoskeleton Coordination Towards Lower Limb Robotic Exoskeleton Systems

“…In [27], an ankle rehabilitation exoskeleton uses a similar position control structure, while the controller replaces the BASMC with an adaptation law. Rifai et al [28], [29] apply a different control method in their EICOSI exoskeleton robot. In [28], they put forward an L1 augmented adaptive controller for position control.…”

“…State errors are measured between various, whilst a projection method ensures the boundedness of the system. In [29], the EICOSI uses a bounded control strategy to avoid saturation of the actuators when tracking a desired trajectory. The lowest self-defined threshold saturations for joint angles and joint velocity errors are used to avoid actual saturation.…”

“…Included here is a user interface where a therapist can adjust the gait pattern easily. The EICOSI [28], [29] exoskeleton robot employs a therapeutic doctor defined gait trajectory. POGO [52], Mina [53], [54], KNEXO [19] and CUHK-EXO [33] all have a zero torque mode that obtains reference trajectories from normal people.…”

“…Index of articles Gait trajectory based [14], [15], [16], [17], [18]- [20], [21], [22], [23], [24], [25], [26], position assistance [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43]- [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58] Posture estimation based [59], [60], [61], [62], [63], [64], [65] position assistance I...…”

Connected Elbow Exoskeleton System for Rehabilitation Training Based on Virtual Reality and Context-Aware

“…There are other works that focus on the study of injuries from other areas such as the ankle [7][8][9]. Other works focused on one of the Sensors 2020, 20, 858 3 of 17 most important joints of the lower extremities such as the knee [10][11][12][13][14][15]. In all these works, the use of robotic exoskeleton systems is another part of the traditional physiotherapeutic rehabilitation that is advised by an expert and is performed in a traditional clinical setting.…”