Small size 2-DOF piezoelectric platform for unlimited locomotion

Abstract

The paper represents a numerical and experimental investigation of a 2DOF piezoelectric positioning platform that can provide unlimited displacement in the plane. The platform consists of three piezoelectric bimorph plates that are located around the triangle-shaped supporting structure by an angle of 120 degrees. Spherical alumina contacts are glued at the bottom surface of each bimorph plate. The platform is an active part of the system and can move on the hard surface in an unlimited displacement range. The platform's operation principle is based on the excitation of the first bending mode of piezoelectric bimorph plates. Two thin connecting beams are placed at nodal lines of the bimorph plate's vibration and are used for plate clamping to the supporting triangle structure. The direction of the platform motion is controlled by corresponding excitation regimes of the piezoelectric bimorph plates. Linear movement of the platform is achieved when the harmonic signal is applied to the single bimorph plate. The remaining two plates operate as passive supports in this case. Moreover, in order to obtain the nonlinear trajectory of the platform motion, the bimorph plates are excited using harmonic electric signals with different amplitudes. A numerical investigation of the 2-DOF platform was performed, and it was found out that the suitable vibration mode of the bimorph plates occurs at 23.54 kHz. Harmonic response analysis showed that the maximum displacement amplitude of the contact reached 561.12 μm in the Z direction while an excitation signal of 210 Vp-p was applied. Prototype 2-DOF piezoelectric platform was made, and an experimental study was performed. Impedance–frequency measurements showed that the operating frequency of the platform is at 23.15 kHz. The maximum linear velocity of 44.45 mm/s was obtained while load of 55.68g N and applied and electrical signal of 210 Vp-p was used. [...]