A Methodology to Quantify Alterations in Human Upper Limb Movement During Co-Manipulation With an Exoskeleton

Abstract

While a large number of robotic exoskeletons have been designed by research teams for rehabilitation, it remains rather difficult to analyse their ability to finely interact with a human limb: no performance indicators or general methodology to characterize this capacity really exist. This is particularly regretful at a time when robotics are becoming a recognized rehabilitation method and when complex problems such as 3-D movement rehabilitation and joint rotation coordination are being addressed. The aim of this paper is to propose a general methodology to evaluate, through a reduced set of simple indicators, the ability of an exoskeleton to interact finely and in a controlled way with a human. The method involves measurement and recording of positions and forces during 3-D point to point tasks. It is applied to a 4 degrees-of-freedom limb exoskeleton by way of example.

Analysis of human-exoskeleton interactions: an elbow flexion/extension case study

“…Overall, wearing ABLE led to a clear slowing down of spontaneous motion pace. Jarrassé and colleagues also observed this reduction of speed during 3D pointing movements with and without ABLE (Jarrassé et al 2010). This implicit slowing down of movement might be due to the fact that compliant (with exoskeleton) and unconstrained (without exoskeleton) movements involved different control strategies (Desmurget et al 1997) and to interaction forces.…”

“…How do people adapt movement kinematics and muscle activities? Some researchers addressed similar questions in the past, but the motor task concerned complex three dimensional movements with few repetitions and participants, which made difficult to draw definite conclusions (Jarrassé et al 2008;Jarrassé et al 2010;Pirondini et al 2016). In contrast, the present study focused on simple elbow flexions/ extensions performed without and with an exoskeleton (programmed in transparent mode), for different ranges of motion and for several repetitions.…”

Development and validation of a soft robotic exosuit for assistance of the upper limbs

“…Unfortunately, no investigation performing such assessment on soft exosuits exists in literature, but our results echo the findings from Jarassé [113] and Pirondini [114], reporting an increase in movement jerk and number of peaks, respectively, when subjects were assisted by a rigid exoskeleton.…”

Ergonomic considerations for anthropomorphic wrist exoskeletons: A simulation study on the effects of joint misalignment

“…As mentioned in [4], kinematic discrepancy is one of the causes for reaction forces. Since our exoskeleton is located on the volar side of the wrist, it causes asymmetric kinematic mismatch between exoskeleton and wrist for flexion rotations in presence of misalignments.…”

“…Such forces result from 'kinematic discrepancies' [4], due for example to oversimplified models of human kinematics and/or misalignments between human and exo joints [5].…”