Development of Micro Linear Ultrasonic Motor

We propose a micro linear ultrasonic motor, which is one of the smallest linear actuators that can generate practical force. Further miniaturization of devices with the linear actuators has been expected to produce thinner and smaller applications, such as cell phones and endoscopes. Actually, miniature linear actuators have been used to generate the translational motion of small objects in certain devices, such as auto-focus systems. In this paper, we propose a new micro linear ultrasonic motor involving a cuboid stator with a side length of approximately 2 mm. The micro linear ultrasonic motor prototype shows an output force of approximately 7.75 mN at low voltage. By optimizing the preload between the stator and slider experimentally, the motor thrust force has been improved to over 10 mN. This thrust force is a practical force for moving small objects.