The inchworm type self-propelled microrobot using a vibration-type friction control mechanism

This paper reports an inchworm type self-propelled microrobot which uses piezoelectric elements. The squeeze film effect which controls the friction force is used. Some preliminary experimental results are also described. The main body of a microrobot consists of two stacked-type piezoelectric elements arranged in the shape of a straight line horizontally. They are inserted between friction control mechanisms. The friction force control mechanism is a piezoelectric element with metal plates at the bottom and an upper mass at the top. The stacked-type piezoelectric element for a vibration-type friction control mechanism is inserted between the plate and the mass. The vertical vibration with high frequency of the piezoelectric element generates air film under the lower plate by the squeeze film effect which levitates the friction control mechanism. The vertical levitation decreases the friction force. The levitating friction control mechanism moves by the push and pull of the propulsion horizontal piezoelectric element. In order to isolate the vertical vibration of the friction control mechanism from a propulsion mechanism, leaf springs are used. Trapezoidal waveforms with low frequency are applied to the horizontal piezoelectric elements which give horizontal displacement. In order to realize the linear displacement of the microrobot by the principle of an inchworm, the trapezoidal waveforms are in different phase. In the experimental, first the floating height of the friction control mechanism was measured. Then the bidirectional linear displacement of the microrobot, was realized.