Piezoelectric Drive Control for Minute Motion Under External Force
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Solution Overview
Problem
Existing piezoelectric driving apparatuses face challenges in accurately controlling minute movements of driven bodies due to external forces such as gravity, which affect the precision and direction of movement.
Innovation Solution
A method is introduced to control a piezoelectric driving apparatus by switching between two drive modes: a first mode where the separation amplitude of longitudinal vibration is changed while the feed amplitude of bending vibration remains constant, and a second mode where both amplitudes are adjusted, allowing the apparatus to adapt to external forces and maintain accurate movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bending vibration is excited after longitudinal vibration at activation to suppress drop of driven body, then gravity influence is reduced, but control of minute movement becomes difficult
Solution Approach 1:
The patent applies dynamics by making the drive algorithm adaptable and switchable between different modes (first drive mode and second drive mode) based on external force conditions. The control system dynamically adjusts which amplitude parameters are changed based on real-time detection of external forces, allowing the system to optimize between preventing driven body drop and enabling precise minute movement control depending on the operational context.
Solution Approach 2:
The patent utilizes parameter changes by selectively modifying either the separation amplitude or the feed amplitude (or both) based on the detected external force magnitude and direction. In the first drive mode, only separation amplitude is changed while feed amplitude remains constant, whereas in the second drive mode, both amplitudes are changed. This selective parameter adjustment resolves the contradiction by adapting the vibration characteristics to the specific external force conditions.
2Measurement precision
If separation amplitude is changed to control minute movement, then movement precision improves, but ability to counteract external forces may be reduced
Solution Approach 1:
The control system dynamically switches between drive modes based on external force detection. When external forces are significant, the system transitions to the second drive mode where both separation amplitude and feed amplitude are changed, providing sufficient force to counteract external influences. When external forces are minimal, the system uses the first drive mode with only separation amplitude changes, optimizing for precise minute movement control.
Solution Approach 2:
The patent implements conditional parameter changes by modifying only the separation amplitude in the first drive mode for precision work, and modifying both separation amplitude and feed amplitude in the second drive mode when force counteraction is needed. This selective parameter adjustment strategy resolves the contradiction by matching the degree of parameter modification to the specific operational requirements.
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 effectively reduces the influence of external forces, enabling precise and accurate control of minute movements by optimizing the drive algorithm based on the received external forces, thereby improving the positional accuracy of the driven body.
Implementation Method 1
a vibration section (511) having piezoelectric elements (51A to 51F) and a transmission section (514)... by energization of the piezoelectric elements (51A to 51F), vibrates the vibration section (511) in a combination of longitudinal vibration and bending vibration
Implementation Method 2
vibrates the vibration section (511) in a combination of longitudinal vibration and bending vibration to cause the transmission section (514) to perform an elliptical motion
Implementation Method 3
moves a driven body using the friction force of the elliptical vibration as a thrust force
Data Source
AI summary
A method of controlling a piezoelectric driving apparatus including a vibration section that has a piezoelectric element and a transmission section that transmits vibration of the vibration section to a driven body, and, by energization of the piezoelectric element, vibrates the vibration section in a combination of longitudinal vibration and bending vibration to cause the transmission section to perform an elliptical motion and to move the driven body by the elliptical motion, the method of controlling the piezoelectric driving apparatus including switching, according to an external force received by the driven body, a drive algorithm of the piezoelectric driving apparatus between a first drive mode in which a separation amplitude, which is an amplitude of the longitudinal vibration, is changed while a feed amplitude, which is an amplitude of the bending vibration, is constant and a second drive mode in which both the feed amplitude and the separation amplitude are changed.