Vibration Actuator Control via Frequency Response Stabilization
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Solution Overview
Problem
Existing vibration type actuators face challenges in accurately controlling frequency and frictional force due to environmental and individual differences, leading to unstable frequency-response characteristics, especially at low speeds and near resonant frequencies, and require improved phase characteristic stabilization.
Innovation Solution
A controlling device that measures and adjusts the frequency, amplitude, and phase of the AC voltage applied to the vibrating member, using a frequency-response characteristic measuring unit to stabilize the frequency and phase characteristics, ensuring accurate control even at low speeds and varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the vibration type actuator is controlled by changing the frequency of AC voltage to reduce resonant frequency variation, then the speed control is improved, but the circuit efficiency varies and frequency-response characteristics change due to temperature and individual differences
Solution Approach 1:
The patent applies feedback by detecting the actual resonant frequency of the vibrating member and using this information to adjust the AC voltage frequency. The control device measures the frequency-response characteristics and feeds back this information to maintain optimal operating conditions, thereby stabilizing both speed control and frequency-response characteristics despite temperature variations and individual differences.
Solution Approach 2:
The patent changes the operating parameters by adjusting the AC voltage frequency and amplitude based on detected resonant frequency variations. By dynamically modifying these parameters in response to environmental changes and individual differences, the system maintains stable frequency-response characteristics while achieving accurate speed control.
2Measurement precision
If the vibration type actuator is driven at the resonant frequency, then the control accuracy is improved, but the control band becomes narrow and sufficient performance cannot be achieved for wideband control applications
Solution Approach 1:
The patent implements dynamic control by continuously adjusting the AC voltage frequency and amplitude based on real-time detection of resonant frequency and frequency-response characteristics. This dynamic adaptation allows the system to maintain high control accuracy at the resonant frequency while also being capable of operating across a wider frequency range for wideband control applications.
Solution Approach 2:
The patent performs preliminary measurement of frequency-response characteristics to identify optimal operating parameters before actual control execution. By pre-characterizing the system's frequency response, the controller can anticipate and adapt to resonant frequency shifts, maintaining accuracy across a broader control band.
3Measurement precision
If the amplitude of the vibrating member is small, then the detection sensitivity is improved, but an offset is superimposed on phase difference due to pressure-contact state changes causing unstable conditions
Solution Approach 1:
The patent introduces an intermediary measurement approach by detecting frequency-response characteristics rather than directly measuring phase difference at small amplitudes. This intermediary method avoids the offset problem caused by pressure-contact state changes while maintaining detection sensitivity, as the frequency-response measurement is less susceptible to contact state variations.
Solution Approach 2:
The patent changes the measurement parameter from direct phase difference measurement to frequency-response characteristic measurement. This parameter change allows the system to maintain high detection sensitivity while avoiding the instability caused by offset superposition in phase difference measurements at small vibration amplitudes.
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
The solution enables precise control of the vibration type actuator's frequency and frictional force, improving stability and performance across a wide range of conditions, including low-speed operations, by accurately following changes in frequency-response characteristics and stabilizing phase characteristics.
Implementation Method 1
applying an AC voltage to an electrical-mechanical energy conversion element provided in the vibrating member
Implementation Method 2
causing a vibrating member to generate the vibration wave by applying an AC voltage
Implementation Method 3
the resonant frequency of the vibrating member caused by a temperature or an individual difference
Implementation Method 4
frictionally drives a moving member by a vibration wave by using a frictional force generated by the vibration wave
Data Source
AI summary
A controlling device for a vibration type actuator includes an AC voltage generating unit in which at least one of parameters, namely a frequency, an amplitude, and a phase of an AC voltage for use in applying an excitation force to a vibrating member, is settable; a measuring unit which measures some physical quantities caused by a vibration of the vibrating member; a variation imparting unit which imparts a predetermined variation to at least one of the parameters of the AC voltage; a frequency-response characteristic measuring unit which finds a frequency-response characteristic of at least one predetermined frequency between a first signal according to the variation and a second signal according to the measured physical quantity; and a frequency controlling unit which controls the frequency of the AC voltage according to the frequency-response characteristic.