Intermittent control explains human motor remnant without additive noise

Early work on modelling the human motion control system showed that only a part of the corresponding motion signals could be described in terms of a deterministic linear continuous-time model of the human control system. It was suggested that the unexplained part, called the remnant, could be modelled by adding a noise signal with a carefully chosen frequency spectrum. Intermittent control provides an alternative description of the human controller which includes a sampling mechanism. This paper suggests that the remnant can be explained by assuming that this sampling mechanism is not uniform; the addition of a noise signal is not required using this assumption. The approach of this paper is to compare the remnant frequency spectrum derived from experimental data with that from equivalent simulated data using each of the two models of the human controller in turn. It is found that both of the simulated models give similar remnant spectra to that of the experimental data. Further work is required to show which of the two models provides the best physiological explanation of remnant.