Vibration Actuator Control Gain Adjustment for Stop Accuracy
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Solution Overview
Problem
Existing control apparatuses for vibration actuators face challenges in enhancing stop operation responsivity without deteriorating controllability, often resulting in overshoot and prolonged stabilization times due to difficulties in accurately controlling the deceleration process.
Innovation Solution
A control apparatus that calculates a control amount using a first deviation between the relative position of a vibrator and a driven member, and a second deviation from the target position, with a gain control unit reducing the gain output as the second deviation decreases, allowing for precise control of the AC signal driving the vibrator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gradual deceleration control is performed to avoid overshoot, then stop accuracy is improved, but driving time increases
Solution Approach 1:
The gain value is dynamically adjusted based on the distance to target position. When the driven member is far from the target, a smaller gain value is used for smooth deceleration. When close to the target, the gain value is increased to enhance stop responsivity and reduce stabilization time, thereby resolving the contradiction between stop accuracy and driving time.
Solution Approach 2:
The control gain parameter is changed according to the position of the driven member relative to the target position. This parameter adjustment allows the system to achieve both gradual deceleration for accuracy and rapid response for time efficiency at different stages of the positioning process.
2Loss of time
If high gain is used to enhance stop responsivity, then stabilization time is reduced, but controllability deteriorates
Solution Approach 1:
Different gain values are applied at different positions during the deceleration process. A smaller gain value is used when the driven member is far from the target to maintain controllability, while a larger gain value is used when close to the target to reduce stabilization time. This localized adjustment of gain quality resolves the contradiction between responsivity and controllability.
3Loss of time
If voltage is turned off for stop operation to achieve rapid deceleration, then driving time is reduced, but stop accuracy deteriorates
Solution Approach 1:
Instead of abruptly turning off voltage, the control system dynamically adjusts the gain value based on real-time position feedback. This dynamic control maintains controllability during deceleration while achieving rapid stopping and high stop accuracy by optimizing the gain at each stage of the process.
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 enhances the responsivity of the stop operation, reduces overshoot, and shortens stabilization time without compromising controllability, enabling more accurate and efficient positioning of the driven member.
Implementation Method 1
a piezoelectric element, to generate high-frequency vibration by applying AC voltage on the element
Data Source
AI summary
A control apparatus of a vibration actuator performs control of the vibration actuator using a control amount calculated using both of a first deviation which is a difference between a command value and a relative position, and a gain changed in accordance with a second deviation which is a difference between a target position and the relative position, so as to reduce the gain in accordance with reduction of the second deviation.