3DOF High Resolution Inertial Piezoelectric Motor

Development of multi degree-of-freedom (DOF) high-resolution motors is becoming of increased importance for nanotechnology, micro-robotics, and laser technology. A novel design of 3DOF rotary type piezoelectric motor is proposed. It includes three novel 2DOF inertial piezoelectric actuators, housing, and hemispherical rotor. 2DOF actuator consists of a piezoelectric bimorph disc with the quadrilateral shaped waveguides in the inner circumference of the disc and carbon fiber rod. Such configuration of the bimorph disc is used to transform radial vibrations of the disc into rotational oscillations of the rod. The piezoelectric actuator operates in two vibration modes, i.e., the first out-of-plane bending mode of the disc at 20.5 kHz and the first radial mode of the disc at 138.2 kHz. The bending mode is used to rotate the rotor about x and y axes, while the radial mode is used to obtain rotation about the z-axis. Each piezoelectric actuator is supplied with sawtooth or square waveform voltage, therefore the rotor is driven based on friction - inertia principle. Numerical and experimental investigation of the piezoelectric motor was performed, and results are discussed.