Optimal Dimensional Synthesis of a Symmetrical Five-Bar Planar Upper-Extremity Neuromotor Device

Individuals with hemiplegia suffer from impaired arm movements that appear as a marked change in arm stiffness. A quantitative measure of arm stiffness would characterize rehabilitation therapy effectively, while little mechanism is designed to implement the function. A symmetrical five-bar linkage consisting of two revolute joints and three prismatic joints is presented. Inverse kinematics and forward kinematics are obtained first. Then inverse singularities and direct singularities of the mechanism are gained. The global stiffness index is defined based on the results of kinematics analysis. Finally, optimal dimensional synthesis of the mechanism in terms of maximum stiffness is conducted by genetic algorithms. The calculation results show that with the length of both the two linkage a=830 mm, the interacting angle of the two guides 2δ=4.48 radian, and the maximum range of displacement of the two carriers dmax=940 mm, the mechanism achieves highest rigidity and its workspace is singularity-free, which covers the human left and right arm range of motion. The proposed novel mechanism featuring high rigidity and a singularity-free workspace can provide rehabilitation training, also solve the problem of quantitative measure of arm stiffness.

A novel glasses-free virtual reality rehabilitation system on improving upper limb motor function among patients with stroke:A feasibility pilot study

Background:Virtual reality(VR)technology is increasingly used in stroke rehabilitation.This study aimed to investigate the effectiveness of using the glasses-free VR training to improve motor function of upper limb in patients with stroke.Methods:Twelve patients with stroke were recruited to participate in the intervention of 3 weeks.At the baseline and post intervention,two times of evaluation including Fugl-Meyer upper-extremity scale(FMS-UE),transcranial magnetic stimulation(TMS)measurement and motion evaluation were performed.Results:No significant difference was observed between two groups at baseline evaluation.After the intervention,the FMS-UE scores presented a greater improvement in the VR group compared with the control group.TMS measurement showed that there was significant difference in cortex latency and central motor conduction time between two groups after the intervention,but no significant difference in the amplitude of motor event potential was observed.In addition,there was a significant correlation between game scores and FMS-UE scores.Conclusions:The novel glasses-free VR training was at least as effective as conventional occupational therapy in upper limb motor function,improving nerve conduction time and corticospinal excitability in patient with stroke.