Generation of Spontaneous Reaching Movement Based on Human Anatomical Constraints

A neuro-musculo-skeletal model is constructed that can spontaneously generate natural reaching motion without priorly forming trajectory. The musculo-skeletal structure of human upper extremity is modeled as three rigid links with eight muscles. A viscoelastic element is attached around each joint to represent passive joint structure. The nervous system is modeled as a recurrent neural network which incorporates a potential defining body mobility due to the anatomical constraints, with a spatial potential defining a goal position. Given a goal position, the nervous system autonomously generates muscular activation signals that tend to move the hand to the goal. Due to the dynamic interaction among the entire neuro-musculo-skeletal systems, motion is naturally induced from the anatomical constraints. The simulated motions agree with those of humans, suggesting that the proposed neural mechanism may be incorporated into actual human motor control.