Abstract
In daily life, humans must compensate for the resultant force arising from interaction with the physical environment. Recent studies have shown that humans can acquire a neural representation of the relation between motor command and movement, i.e. learn an internal model of the environment dynamics. In this paper, we investigate motor adaptation of human arm movements to external dynamics. In the experiment, we examine whether humans can learn an internal model of a “mixed force field”(V+P) which is sum of a “velocity-dependent force field”(V) and a “position-dependent force field”(P). The experiment results show that the subjects did not learn the internal model of V+P accurately and they compensated the loads by using impedance control. Our results suggest that humans use impedance control when internal models become inaccurate because of the complexity of external dynamics.
