PURPOSE: To provide a human interface device capable of naturally controlling part of the body or the virtual body being the all model in the computer as himself and freely controlling the power, velocity and acceleration as well as the position.

CONSTITUTION: A surface electrode 1 is attached on the body of a user, which detects the power saving signal. Then it is amplified by a power saving signal amplifier 2 and then passed to a filter 3. Thus, the pseudo tension is outputted to a body dynamics model 4. The model 4 estimates the motion orbit and power orbit based on the pseudo tension. The motion simulation is performed based on the orbit estimating the virtual body in a computer 5.