A Human-Centered Kinematics Design Optimization of Upper Limb Rehabilitation Exoskeleton Based on Configuration Manifold

Shoulder repetitive training is of paramount importance for rehabilitation of stroke patients with hemiplegia. This article investigated kinematic structural optimization of an upper limb rehabilitation exoskeleton's shoulder structure, aiming to cover the range of motion (ROM) of human shoulder, achieve sufficient dexterity, obtain a compact structure, and avoid collisions with the user within the workspace. Based on the concept of configuration manifold, configuration parameters and joint angle parameters were fused, and parameter optimization was transformed into a searching problem in high-dimensional configuration space. Geometric constraints between human and exoskeleton were described parametrically. Upper limb movements were mapped to the exoskeleton's configuration space to calculate spatial vectors of joints, and determine whether vectors satisfy constraints. The formulated multi-objective optimisation problem was computed by multi-objective particle swarm optimization (MOPSO) algorithm to determine the shoulder configuration parameters. Experimental results demonstrate that functional rehabilitation exoskeleton (FREE) exhibits a wide ROM, excellent dexterity, and can assist users in completing most activities of daily life (ADLs). The design framework proposed in this article can help designers determining optimal exoskeleton configurations through formulated constraints.