Control of wearable motion assist robot for upper limb based on the equilibrium position estimation

In this paper, we propose a robotic system for assisting patients who have upper limb dysfunction in performing reaching movements through flexion. Since upper limb motion is more strongly needed than lower limb mobility for near work, a patient's level of recovery of upper limb function influences daily life. Recently, with the widespread application of robotic technology in rehabilitation medicine, active movement has often been noted to be more important than passive movement for rapid recovery. A novel control method for assisting upper limb movement by using a control system with two degrees of freedom is proposed. In the process of estimating the trajectory, the minimum jerk criterion is used to compute the velocity trajectory and to determine the reach position. The aim is to eventually develop a movement assistance system for the upper limb which will enable wearers to perform flexion and extension covering ranges of motion which are otherwise impossible to achieve autonomously. The effectiveness of the developed system is demonstrated experimentally.