Estimation method of arm stiffness for evaluation of physicality in arm self-rehabilitation

This paper presents an evaluation method of arm stiffness to show utility of the developed arm self-rehabilitation system. Purpose of this research is an improvement of the arm´s physical function of patients with hemiplegia. Their arm character is high arm stiffness due to the strong paralysis. So, we aim that their arm stiffness will decrease after rehabilitation using our developed system. As mechanical property of stiffness, reaction force on hand is depend on the arm stiffness and displacement when the hand will be moved for some reason. In other words, we have to use the displacement and reaction force on hand to estimate arm stiffness. Our developed rehabilitation support system can measure the position and force response of patient´s hand because of bilateral control. Arm stiffness changes depending on patient´s arm posture. In this paper, the accuracy of the proposed arm stiffness estimation method is verified from the experimental results under the condition of several different arm postures.