9. The method of claim 6 , further comprising the step of: decreasing the resistive force supplied by said electric motor when output of said sensor indicates sticking point reduced motion of said primary user interface.
6. The method of claim 1 , further comprising the step of: using a sensor to measure at least one of: force applied by the primary user to the primary user interface; a physiological measure of the primary user; acceleration of the primary user interface; and motion of the primary user interface.