Delay Time of Human Motion Generation in Response to Changing Periods in Force Tracking Task

It is important to understand how humans gen-erate tracking forces when considering the increase of human- robot interactions. Previous research has mostly focused on po-sitional target tasks. A recent study was conducted to investigate the basic characteristics of the force tracking task. That study suggested predictive compensatory behavior in humans during fast rhythmic movements. In this paper, we investigated the relationship between the frequency of rhythmic force generation and predictive compensation in humans. Here we conducted experiments using four square waves with different periods as target values with four healthy young subjects. Subjects were instructed to control the force exerted at the tip of their fingers during a force pursuit tracking task. The results suggest the following: the faster the tracking period, the faster the delay time converges to a steady value; the relationship between the motion period and the rate of convergence is not linear; individual differences in delay time are large when the force generation is transitioning from slow to very fast, which corresponds to the rhythmic task; when the period is extremely short (the period is 1 sec), the ascent and descent force characteristics are different.