A self-adjusting knee exoskeleton for robot-assisted treatment of knee injuries

Abstract

In this study, we present a novel active device for robot-assisted rehabilitation that accommodates transitional movements of the knee joint as well as its rotation, enabling a perfect match between human joint axes and the device axes. Automatically adjusting its joint axes, the proposed device is not only capable of guaranteeing ergonomy and comfort throughout the therapy, but also extends the usable range of motion for the knee joint. Moreover, the adjustability feature significantly shortens the setup time required to attach the patient to the exoskeleton, allowing more effective time be spend on exercises instead of wasting it for adjustments. The proposed system is different from the similar works in literature in that it supports both passive translational movements of the knee joint and independent active control of these degrees of freedom. In particular, we introduce implementation details of a prototype that features compact design and combines the power of three actuators to achieve high rotational torques, detail the model based impedance controller utilized to adjust interaction forces and present the experimental characterization of the exoskeleton.

Misalignment Compensation for Full Human-Exoskeleton Kinematic Compatibility: State of the Art and Evaluation

“…Researchers in the same group were also responsible for the design of a novel three-RRP mechanism for the realization of a self-aligning knee joint [109]. The mechanism is shown in Fig.…”

“…Due to the variability of the designs, it is difficult to provide a single score for the entire category. Some devices are very heavy and lead to bulky architecture [60,71,109], while some offer an elegant solution for the problem of misalignment [105,113]. The disadvantage of the latter is that they were specifically designed for the elbow and the design is therefore not directly applicable to other joints.…”

Self-adjustment mechanisms and their application for orthosis design

“…This paper extends the results of previous research [19] by presenting a more complete model of the horizontal self-adjustment movement together with the analysis of the vertical self-adjustment movement. In contrast to other designs, employed more particularly in active orthoses, where additional DOFs remain free all throughout the joint movements [20][21][22][23][24][25], we focus in this work on passive orthoses. The extra DOFs are blocked after a short period of self-adjustment, after which the orthosis can work normally to protect the anatomical joint.…”

Multi-joint soft exosuit for gait assistance

“…Alternately, self-aligning mechanisms may be bulky and heavy [12], [13]. Rigid exoskeletons may also have large inertias which can further hinder motion if the wearer is imperfectly tracked by the control system.…”