Piezoelectric Actuator Generating 3D-Rotations of a Sphere

Investigation of a new design piezoelectric actuator based on research of compound ultrasonic systems called shaking beam is presented in the paper. It was developed to rotate the sphere about three different axes and can be used in sophisticated positioning devices. The actuator consists of a vibrating frame, four piezostacks and four overlays. Elliptical motions of the four driving tips, which rotate the sphere, are achieved by using multimode oscillations of the vibrating frame. Control of the sphere's motion is performed by managing the amplitude and phase of harmonic input signal on different piezostacks. Numerical modeling based on a finite element method is performed in order to obtain resonance frequencies and modal shapes of the actuator and to calculate the trajectories of contact points movements under different input regimes. A prototype actuator was made and the experimental outcomes of the actuator's working surfaces oscillations are given. Results of the numerical and experimental research are analyzed and discussed.