Ultrasonic Motor Driving Method for Stable Startup
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Solution Overview
Problem
Existing ultrasonic motor driving methods experience unstable operation and high drive noise due to abrupt excitation of traveling elastic waves, leading to sticking and slipping issues during startup.
Innovation Solution
A driving method that applies a preliminary vibration mode with a smaller amplitude or duty ratio before the main vibration mode to reduce frictional forces, followed by an ending vibration mode to smoothly halt the motor, preventing sticking and slipping and minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If alternating signals are applied to excite traveling elastic waves, then the ultrasonic motor can be driven efficiently, but large drive noise is generated during initial driving
Solution Approach 1:
The patent uses preliminary action by applying a vibration with smaller amplitude before the main driving vibration. This preliminary vibration reduces the frictional force at the contact portion, allowing the motor to start smoothly without abrupt excitation. As a result, large drive noise is prevented during the initial driving phase while maintaining driving efficiency.
2Power
If full amplitude vibration is applied immediately, then the motor achieves full power output, but frictional forces cause sticking and slipping
Solution Approach 1:
The patent applies preliminary action by generating a vibration with smaller amplitude than the substantially elliptical vibration before applying the full power driving signal. This preliminary vibration breaks the contact and reduces frictional force, preventing sticking and slipping. After the preliminary vibration domain, the driving alternating signal is applied to achieve full power output with smooth operation.
Solution Approach 2:
The patent implements dynamics by gradually changing the vibration amplitude from a smaller preliminary vibration to the full substantially elliptical vibration. The vibration amplitude is not fixed but transitions dynamically through different domains (preliminary vibration domain to main vibration domain), ensuring smooth operation while achieving full power output.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables stable and quiet operation of ultrasonic motors by reducing frictional forces and noise during startup and shutdown, ensuring smooth relative movement and efficient driving.
Implementation Method 1
applying a driving alternating signal to an ultrasonic vibrator to simultaneously generate two different vibration modes in the ultrasonic vibrator to cause a substantially elliptical vibration at an output terminal
Implementation Method 2
relatively moving the ultrasonic vibrator and a driven body in contact with the ultrasonic vibrator
Implementation Method 3
The preliminary vibration generated at the output terminal of the ultrasonic vibrator in this state can break this contact. In other words, the frictional force at the contact portion can be reduced.
Data Source
AI summary
A method for driving an ultrasonic motor includes the step of applying a driving alternating signal to an ultrasonic vibrator to simultaneously generate two different vibration modes in the ultrasonic vibrator to cause a substantially elliptical vibration at friction-contact members of the ultrasonic vibrator, thus relatively moving the ultrasonic vibrator and a driven body in contact with the ultrasonic vibrator. A preliminary vibration domain in which a preliminary vibration smaller than the substantially elliptical vibration is generated at the friction-contact members is provided prior to a main vibration domain in which the driving alternating signal is applied.