The principle of a 6 DOF (degrees of freedom) input device using ultrasonic distance measurement is presented in this paper. The system employs the method of measuring the time of flight. In addition, some techniques, including automatic gain control, self-adaptive variable threshold and temperature compensation, are also used to improve precision. Then, the positions and orientations of the input device can be calculated by the method of spatial analytic geometry. Meanwhile, commands from the 3-D input device are detected and carried out. The validity and precision of the input device are verified by the experiment in a robot system. The proposed device not only can be used for end-effector position and orientation measurement in telerobotics, but also can be an interactive device in virtual reality systems, such as helmet tracking, viewpoint navigation and object manipulation.
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