Frequency Control Circuit for Oscillatory Wave Motor
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Solution Overview
Problem
Conventional oscillatory wave motors face challenges in controlling the driven body's velocity with fine precision near the resonance frequency due to rough frequency and phase difference control in their driving circuits, especially when miniaturized and operating at high frequencies.
Innovation Solution
A frequency control circuit and method that sets a non-submultiple target value, using adding circuits to count and output alternating signals with phase differences between vibration modes, allowing for precise control of the next cycle's initial value based on exceeding the target, enabling finer control of oscillation frequency and phase difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the oscillatory wave motor is miniaturized and operates at high frequencies, then the motor size is reduced and power consumption is lowered, but the frequency control precision deteriorates and blind zones appear in velocity control near resonance frequency
Solution Approach 1:
The patent changes the control parameter from simple frequency division to a cumulative adding method where the set value is added to the counter value in each cycle. This parameter change enables precise frequency control even at high frequencies by continuously accumulating small increments rather than relying on coarse division ratios, thereby resolving the contradiction between miniaturization and control precision.
Solution Approach 2:
The patent implements a feedback mechanism where the counter value is continuously compared with a target value, and the initial value for the next cycle is set based on the difference (exceeding amount). This closed-loop feedback ensures that the oscillation frequency remains precisely controlled even near resonance frequency, preventing blind zones in velocity control while maintaining the benefits of miniaturization.
2Device complexity
If conventional frequency division method is used in the driving circuit, then the circuit structure is simple, but the phase difference control precision deteriorates and velocity control blind zones occur near resonance frequency
Solution Approach 1:
The patent replaces the conventional mechanical frequency division method with an electronic cumulative adding method using a counter and adding circuit. This substitution maintains circuit simplicity while achieving superior phase difference control precision by continuously accumulating set values and using the exceeding amount to adjust the next cycle's initial value, thereby eliminating velocity control blind zones near resonance frequency.
Solution Approach 2:
The patent introduces dynamic adjustment of the counter's initial value for each cycle based on the exceeding amount from the previous cycle. This dynamic approach allows the system to adapt and maintain precise phase difference control under varying operating conditions, particularly near resonance frequency, without increasing overall circuit complexity.
3Device complexity
If the driving frequency is controlled with coarse steps, then the control circuit is simple, but the velocity control precision deteriorates and blind zones appear near resonance frequency
Solution Approach 1:
The patent applies partial action by adding a set value (which may be smaller than one full cycle) to the counter value in each cycle. This partial accumulation approach enables fine-grained velocity control by allowing the counter to reach the target value with precise increments, thereby eliminating blind zones in velocity control near resonance frequency while keeping the control circuit simple.
Solution Approach 2:
The patent uses feedback by setting the initial value of the counter for the next cycle based on the exceeding amount (difference between target value and current counter value). This feedback mechanism ensures that velocity control precision is maintained even with simple circuitry, as the system automatically adjusts the starting point of each cycle to achieve the desired velocity without blind zones near resonance frequency.
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 allows for precise control of the driven body's velocity even near the resonance frequency, preventing blind zones in velocity control and improving the motor's performance by finely setting oscillation frequency and phase differences.
Implementation Method 1
an oscillatory wave (vibration type) motor called as an ultrasonic motor or a piezoelectric motor has been developed and put to practical use. The oscillatory wave motor, as is well-known, is a motor configured to apply an alternating voltage to an electromechanical energy conversion element such as the piezoelectric element or an electrostrictive element so as to allow the element to generate high frequency vibration
Implementation Method 2
allow a mobile member brought into contact with a vibrator vibrated by a piezoelectric element to relatively move by a friction force
Data Source
AI summary
A frequency control circuit including a control circuit for setting a set value, an adding circuit for adding the set value per unit time and effecting counting based on the adding result, and a signal output circuit for outputting an alternating signal of a cycle corresponding to the time necessary for the count result by the adding circuit to reach a target value. The control circuit sets the set value as a value which does not correspond to a submultiple of the target value, and the adding circuit starts the counting of a next cycle when the count result reaches the target value. The control circuit further sets an initial value of the counting of the next cycle in accordance with a value of a portion of the adding results, exceeding the target value when the count result reaches the target value.