Open-Loop Intermittent Feedback Optimal Control: a probable human motor control strategy

Recent studies on human motor control have been largely innuenced by two important statements: (1) Sensory feedback is too slow to be involved at least in fast motor control actions; (2) Learned internal model of the systems plays an important role in motor control. As a result , the human motor control system is often described as open-loop and particularly as a system inverse. System inverse control is limited by too many problems to be a plausible candidate. Instead, an alternative between open-loop and feedback control is proposed here: the "open-loop intermittent feedback optimal control". In this scheme, a prediction of the future behaviour of the system, that requires feedback information and a system model, is used to determine a sequence of actions which is run open-loop. The prediction of a new control sequence is performed intermittently (due to computational demand and slow sensory feedback) but with a suucient frequency to ensure small control errors. The inverted pendulum on a cart is used to illustrate the viability of this scheme.