Shoulder Kinematics Assessment towards Exoskeleton Development

Abstract

Neuromuscular and sensorimotor degeneration caused by stroke or any other disease significantly reduce the physical, cognitive, and social well-being across the life span. Mostly, therapeutic interventions are employed in order to restore the lost degrees-of-freedom (DOF) caused by such impairments and automating these therapeutic tasks through exoskeletons/robots is becoming a common practice. However, aligning these robotic devices with the complex anatomical and geometrical motions of the joints is very challenging. At the same time, a good alignment is required in order to establish a better synergy of human-exoskeleton system for an effective intervention procedure. In this paper, a case study of an exoskeleton and shoulder joint alignment were studied through different size and orientation impairment models through motion capture data and musculoskeletal modeling in OpenSim. A preliminary result indicates that shoulder elevation is very sensitive to misalignment and varies with shoulder joint axes orientation; this is partly due to drastic displacement of the upper arm axes with respect to the shoulder joint origin during elevation. Additional study and analysis is required to learn any possible restraint on shoulder elevation that could potentially help in the exoskeleton development.

Kinematic of the Position and Orientation Synchronization of the Posture of a n DoF Upper-Limb Exoskeleton with a Virtual Object in an Immersive Virtual Reality Environment

“…However, many unsolved issues for natural interaction with the human body remain, especially in terms of kinematic singularities [20] and upper-limb biomechanics [21][22][23], e.g. shoulder elevation [24][25][26].…”

Wheelchair-Mounted Upper Limb Robotic Exoskeleton with Adaptive Controller for Activities of Daily Living

“…This gap was filled with a plastic foam to restrict the upper arm from slipping during exoskeleton control. The shoulder’s complex anatomy makes it very difficult to design an exoskeleton that mimics the rotation axis of the exoskeleton joint that can align with the human joint and offer all degrees of freedom when the exoskeleton robot is attached to the exterior of the human body [ 26 , 27 ]. Future designs of the prototype can include an angular joint assembly of the upper arm exoskeleton that can reduce the gap between the exoskeleton and upper arm assembly.…”

A 4-DOF Upper Limb Exoskeleton for Physical Assistance: Design, Modeling, Control and Performance Evaluation

“…The dynamic model of an exoskeleton can be derived using the Lagrange formulation and can be expressed by the following equation M(q) q + C(q, q) q + τ g = τ (6) where q ∈ is a position vector, M(q) is inertia matrix, C(q, q) represents the Coriolis forces and τ g is the torque due to gravity. Although we have used the model-free PD/PID control scheme, the dynamic model of the system is still provided in (4) to simulate the dynamic response of the robotic exoskeleton.…”

“…However, given the utility and growing demand of exoskeletons for physical assistance, the technology still faces challenges in mechanical design, controls, and humanrobot interaction. Of them, the mechanical design of a shoulder exoskeleton, including kinematic and kinetic analysis, is a major issue in developing an ergonomic system [6]. Christensen et al [7] proposed a new three degrees of freedom (DOF) spherical mechanism to comply with the human glenohumeral joint movements.…”