Inertial Drive Actuator Position Control via Friction Compensation
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Solution Overview
Problem
Conventional inertial drive actuators face challenges in achieving accurate positioning due to varying frictional forces between the drive shaft and the lens holding frame, leading to errors in movement per drive pulse, which pile up and prevent precise positioning of moving bodies.
Innovation Solution
A position control method for inertial drive actuators that involves setting the amount of movement per driving waveform, detecting relative positions using electrostatic capacitance, comparing target and actual positions, and adjusting drive voltage patterns to control frictional forces between the moving body and the vibration substrate, ensuring accurate positioning by synchronizing with the movement of the vibration substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional position detection using MR sensors and drive pulse counting is used, then the actuator can achieve basic positioning function, but positioning accuracy deteriorates due to frictional force variations causing inconsistent movement per drive pulse
Solution Approach 1:
The patent applies feedback by detecting the actual position of the moving body using an MR sensor and comparing it with the target position. Based on this comparison, the system adjusts the drive voltage pattern to correct positioning errors. This closed-loop feedback mechanism compensates for frictional force variations and ensures accurate positioning despite inconsistent movement per drive pulse.
Solution Approach 2:
The patent changes the drive voltage pattern parameters based on the detected position and target position. By adjusting voltage amplitude and pulse width dynamically, the system compensates for frictional force variations and achieves consistent positioning accuracy regardless of the moving body's position or load conditions.
2Measurement precision
If the number of drive pulses is increased to improve positioning precision, then positioning accuracy improves, but response time deteriorates due to accumulated errors and multiple adjustment cycles
Solution Approach 1:
The feedback mechanism detects the actual position after each drive pulse and immediately adjusts subsequent drive patterns to correct errors. This real-time correction prevents error accumulation and achieves high positioning precision in fewer pulses, thereby reducing response time.
Solution Approach 2:
The drive voltage pattern is dynamically adjusted based on real-time position detection. The system optimizes the number and intensity of drive pulses needed to reach the target position, achieving precise positioning faster by adapting to actual frictional conditions rather than using a fixed pulse sequence.
3Reliability
If frictional force between drive shaft and lens holding frame is reduced to improve movement consistency, then movement per drive pulse becomes more consistent, but positioning accuracy deteriorates due to insufficient control over frictional variations
Solution Approach 1:
The feedback system detects positioning errors caused by frictional force variations and compensates for them by adjusting the drive voltage pattern. This allows the system to maintain movement consistency while achieving high positioning accuracy through active compensation rather than passive friction reduction.
Solution Approach 2:
The drive voltage parameters are changed dynamically to compensate for frictional force variations. By adjusting voltage amplitude and pulse width based on detected position and target position, the system maintains consistent movement characteristics while achieving accurate positioning.
4Device complexity
If simple drive pulse counting is used to reduce device complexity, then the actuator structure remains simple, but positioning accuracy deteriorates due to accumulated errors from inconsistent movement per pulse
Solution Approach 1:
The patent introduces a feedback mechanism using an MR sensor to detect actual position and compare it with target position. This feedback loop enables accurate positioning by correcting errors in real-time, maintaining simplicity while achieving high precision through intelligent control rather than complex mechanical structures.
Solution Approach 2:
The patent replaces complex mechanical positioning mechanisms with an electronic control system that uses MR sensor feedback and adaptive voltage pattern generation. This substitution achieves high positioning accuracy through electronic intelligence rather than mechanical complexity.
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 method enables accurate and prompt positioning of moving bodies by compensating for frictional force variations, improving positioning accuracy and response time by adjusting drive voltage patterns based on real-time position detection.
Implementation Method 1
When a drive pulse of a waveform formed of a gently rising part and a rapidly falling part is applied to an electromechanical transducer such as a piezoelectric element, at (in) the gently rising part of the drive pulse, the piezoelectric element is displaced by being extended gradually in a direction of thickness, and at the rapidly falling part, the piezoelectric element is displaced by being contracted rapidly.
Implementation Method 2
When the magnetic resistive element 236 is displaced along the drive shaft 222 due to a displacement of the holding frame 226, since the magnetic resistive element 236 intersects the leakage magnetic flux of the magnetic pole 238, a value of resistance of the magnetic resistive element 236 changes periodically, and generates a predetermined position detection pulse.
Implementation Method 3
driving the moving body by controlling a frictional force between the vibration substrate and the moving body, by making an electrostatic force act on both
Data Source
AI summary
A position control method of inertial drive actuator includes a movement-amount setting step of setting an amount of movement, a target-position setting step of setting a target position of a moving body, a position detection step of detecting a relative position of the moving body, a comparison step of comparing the target position and the relative position, a drive-voltage pattern setting step of setting a drive voltage pattern which is to be applied to the moving means, a first electrode, and a second electrode, based on the amount of movement which is set, and a comparison result, and a driving step of driving the moving body by controlling a frictional force between the vibration substrate and the moving body, by making an electrostatic force act on both, while synchronizing with a movement of the vibration substrate, by applying a drive voltage pattern which is set at the drive-voltage pattern setting step, between the first electrode and the second electrode, and the moving body is moved to the target position by repeating steps from the comparison step to the driving step.