Intrinsic Sensing and Evolving Internal Model Control of Compact Elastic Module for a Lower Extremity Exoskeleton

Abstract

To achieve strength augmentation, endurance enhancement, and human assistance in a functional autonomous exoskeleton, control precision, back drivability, low output impedance, and mechanical compactness are desired. In our previous work, two elastic modules were designed for human–robot interaction sensing and compliant control, respectively. According to the intrinsic sensing properties of the elastic module, in this paper, only one compact elastic module is applied to realize both purposes. Thus, the corresponding control strategy is required and evolving internal model control is proposed to address this issue. Moreover, the input signal to the controller is derived from the deflection of the compact elastic module. The human–robot interaction is considered as the disturbance which is approximated by the output error between the exoskeleton control plant and evolving forward learning model. Finally, to verify our proposed control scheme, several experiments are conducted with our robotic exoskeleton system. The experiment shows a satisfying result and promising application feasibility.

Sensors and Actuation Technologies in Exoskeletons: A Review

“…In addition, the proposed classification strategy could penalize the number of papers actually classified in the category f1 Sensors. In fact, several works focus on algorithms, data fusion techniques and control strategies, particularly among the most recent literature: those contributions, though, are primarily assigned to the category Others (e.g., [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]).…”

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Study on the Control Method of Knee Joint Human–Exoskeleton Interactive System

“…The mechanism of a rigid exoskeleton is parallel to the human limbs, which is convenient for weight bearing and rehabilitation training. The corresponding control methods [ 7 , 8 ] have also been studied. However, due to structural and inertial limitations, rigid exoskeletons are unsatisfactory in assisting healthy individuals to walk.…”

A Novel Weight-Bearing Lower Limb Exoskeleton Based on Motion Intention Prediction and Locomotion State Identification

“…However, the main drawback is mainly manifested in the aspect that since the bundling components are generally placed at the connection position with the thigh, the calf and the foot, the measured HRI forces vary with the wearing status and physical response of the human body, which will lead to measurement deviations and decoupling interference of the HRI value. Thus, an adaptive control strategy based on intrinsic sensing is necessary to ensure that the extraction of HRI is independent of wearing status [22]. Since the connecting rod is both a transmission component and an elastic measuring and sensing unit in the transmission structure, the arrangement positions of the connecting rod determine the size and force characteristics.…”