Absolute Disk Capacitive Sensor for Wide-Angle Measurement
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Solution Overview
Problem
Conventional absolute-type capacitive sensors are limited in measuring wide angles due to capacitance constraints, and incremental-type sensors face challenges with high-speed signal processing, calibration errors, and power reset requirements, making them unsuitable for precise and efficient wide-angle measurements.
Innovation Solution
An absolute disk capacitive sensor device combining disk capacitive grid technology with microprocessor processing, featuring independent rough and fine division sensors and a microprocessor unit for data integration, enabling high precision and resolution while simplifying data processing and avoiding continuous detection requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If incremental-type capacitive sensors are used for wide-angle measurement, then measurement range is improved, but calculation response speed must be increased to match high-speed phase signal changes
Solution Approach 1:
The patent divides the measurement system into two independent sensor systems: a rough division sensor for wide-angle measurement and a fine division sensor for high-precision measurement. This segmentation allows each sensor to operate independently with optimized parameters, where the rough sensor handles large angular displacements and the fine sensor provides high-resolution data, eliminating the need for high-speed continuous calculation of periodic phase signals.
Solution Approach 2:
The patent introduces a microprocessor as an intermediary that integrates data from both rough and fine division sensors. The microprocessor performs the complex calculation operations, relieving the real-time processing burden from the signal processing circuit. This intermediary handles the integration of coarse and fine measurements, providing absolute position data without requiring high-speed continuous calculation.
2Length of moving object
If incremental-type capacitive sensors are used, then wide-angle measurement is achieved, but calibration errors propagate and multiply
Solution Approach 1:
The patent implements preliminary action by providing a reference mark on the movable member that establishes an absolute reference position. The rough division sensor detects this reference mark to determine the initial position and count rotation cycles. This preliminary establishment of reference eliminates the need for continuous calibration and prevents error propagation, as each measurement cycle starts from a known absolute reference.
Solution Approach 2:
The system achieves self-service through the reference mark mechanism that automatically re-establishes the absolute reference position without external intervention. When the movable member returns to the reference mark position, the system automatically resets the cycle counter and establishes a new reference, eliminating the need for manual calibration and preventing cumulative errors.
3Use of energy by moving object
If power is turned off for incremental-type sensors, then energy is saved, but reference position must be reset before further use
Solution Approach 1:
The absolute-type capacitive sensor system provides self-service by maintaining absolute position information through its sensor design. The rough division sensor continuously tracks absolute position using the reference mark, and the fine division sensor maintains high-resolution data. Upon power restoration, the system automatically reacquires the reference position and resumes measurement without manual intervention, eliminating the need for reset operations.
4Measurement precision
If multiple different periodic phase signals are used for absolute position measurement, then absolute position can be determined, but data processing process becomes complicated
Solution Approach 1:
The patent segments the measurement function into two independent sensor systems with different resolutions: rough division sensor for coarse position and fine division sensor for fine position. Each sensor processes its own signal independently without requiring complex integration of multiple periodic phase signals. The rough sensor provides absolute position over wide angles while the fine sensor adds precision, and a simple microprocessor combines these independent measurements.
Solution Approach 2:
The patent replaces complex mechanical signal processing circuits with a microprocessor-based system. Instead of using complex synchronous modulation control and logical operations to process multiple periodic phase signals, the system uses a microprocessor to read and integrate simple digital outputs from the rough and fine division sensors, dramatically simplifying the data processing architecture.
5Measurement precision
If three different signal patterns are used to increase measurement precision, then resolution is improved, but data processing speed must be increased
Solution Approach 1:
The patent segments the resolution function into two independent sensor systems: rough division sensor for coarse measurement and fine division sensor for fine measurement. This segmentation eliminates the need for three different signal patterns, as the fine division sensor alone provides the necessary high resolution. The independent operation of these sensors avoids the complex data processing required when using multiple signal patterns simultaneously.
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 high-resolution, wide-angle position measurement with reduced complexity and cost, maintaining precision and accuracy even at high data processing speeds, suitable for both manual and automated applications.
Implementation Method 1
By detecting the capacitance change of a movable pole piece relative to a fixed pole piece, angle variation can be measured
Data Source
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AI summary
An absolute position measuring device is suitable for wide-angle range measurement and providing the advantages of high precision, high resolution and easy data processing. The measuring device comprises a disk capacitive sensor, a measurement signal processing unit, a data processing unit, and a display unit. The disk capacitive sensor comprises a rough division sensor and a fine division sensor. The pitch point value of the fine division sensor is at least two times higher than two resolutions of the rough division sensor. The rough division sensor and the fine division sensor have the same zero position. The grids of the two rough division and fine division sensors are independent to each other, are free of electric coherence, and are fixed relatively to each other. The grid has an exclusive absolute displacement value within a single pitch measurement range.