An ultrasonic standing-wave-actuated nanopositioning walking robot: Piezoelectric-metal composite beam modeling

This paper proposes a design for a precision positioning miniature walking robot using piezoelectric unimorph actuators. The theoretical working equations of a uniform piezoelectric unimorph beam are derived based on the linear piezoelectric relations, Hamilton's principle, and Euler-Bernoulli beam equation. The modal superposition method is used to determine the response of the forced transverse vibration of the beam under the effect of electrical signal inputs to the patterned piezoelectric element. Two standing waves corresponding to the third and fourth bending vibration modes are utilized to achieve the bi-directional walking mechanism for a miniature positioning robot. Design strategies and the fabrication method for the proposed walking robot are introduced. Preliminary performance tests of the robot prototype are carried out successfully, and the robot achieves speeds of 5.86 cm/sec and 3.37 cm/sec in forward and backward motion, respectively.