Background
Hinges (rotation) and sliders (translation) are two of the most widely used mechanisms in robotics. Each joint, and thus each direction of motion (DOF), correspond to one degree-of-freedom of the system. Systems with more than one DOF use multiple actuators that increases complexity and cost to miniature robotic systems.

Invention Description
The subject invention is a multiple function piezoelectric device. Using a single actuating body, the invention has multi-DOF; rotation and linear motor. This multi-DOF motor utilizes two distinct vibration modes at two different frequencies each of which are responsible for one operating mode. (translation or rotation). The invention does not require mode coupling and dual phase drive, even though it can provide bidirectional dual function on the same shaft. In addition to its mechanically simple structure, eliminating mode coupling and a dual phase drive by using a single source electric drive, the motor’s simplicity allows for broader operating conditions at cost effective means. The inventors have also determined experimentally the optimum piezoelectric material’s orientation, maximum effective coupling coefficient and vibration amplitude for translation and rotary operating modes.

Using low-cost materials, the invention has been reduced to practice at a benchtop level. A prototype of the motor having a cylindrical-joint type configuration with a 5 mm diameter and 30 millimeter total length produced a 5 mm/sec (translational) and 3 rad/sec (rotary) speed even under a 4 mN blocking force, when the input signal is 50 Vp_p square wave. The researcher continues to conduct experiments to explore the versatility of this motor. Prototype samples may be available for evaluation under an appropriate transfer agreement. This translational and rotary ultrasonic motor may allow for further miniaturization of robotic systems.

File Number: 3690