Inductive Position Encoder Circuits for Low-Latency Calibration
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Solution Overview
Problem
Inductive position encoders have higher latency and lower update rates compared to optical encoders, making them less reliable for applications with quickly moving objects, and they require a clean environment to function effectively.
Innovation Solution
The development of new processing and excitation circuitry for inductive position encoders, including dual measurement circuits that process sensor signals in a time division manner to improve accuracy and reduce latency, with features such as calibration data mapping, breakthrough offset correction, and phase tuning to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inductive position encoders are used, then cost is reduced compared to optical encoders, but latency increases and update rate decreases
Solution Approach 1:
The measurement process is divided into multiple segments using separate measurement circuits for different signal processing paths. One circuit handles breakthrough offset correction while another handles phase measurement, allowing parallel processing that reduces overall latency while maintaining the cost-effective inductive encoder architecture
Solution Approach 2:
Breakthrough offset calibration is performed in advance and stored for later use during normal operation. This preliminary calibration action eliminates the need for continuous offset correction computations during real-time measurement, reducing processing latency and update time
2Ease of manufacture
If inductive position encoders are used, then cost is reduced compared to optical encoders, but measurement accuracy and reliability decrease
Solution Approach 1:
The system implements feedback through breakthrough offset calibration where measured offset values are stored and used to correct subsequent measurements. This feedback mechanism continuously improves measurement accuracy by compensating for systematic errors inherent in inductive encoder architecture
Solution Approach 2:
Breakthrough offset calibration serves as an intermediary correction layer between the raw sensor signals and final position measurements. This intermediate processing step filters out systematic errors and improves the accuracy of the final position reading while maintaining the low-cost inductive encoder design
3Ease of manufacture
If inductive position encoders are used, then cost is reduced compared to optical encoders, but the encoder requires clean environment to function effectively
Solution Approach 1:
The breakthrough offset calibration feature enables the inductive encoder to self-correct for environmental interference and signal degradation. By continuously calibrating and storing offset values, the system compensates for the effects of dirty environments without requiring external intervention or cleaner conditions
4Loss of time
If dual measurement circuits with time division processing are implemented, then latency is reduced and update rate increases, but device complexity increases
Solution Approach 1:
The dual measurement circuits operate in periodic time-division fashion, with each circuit dedicated to specific measurement tasks at different time intervals. This periodic operation allows parallel processing capability while using a single physical ADC, reducing hardware complexity compared to fully parallel architectures
Solution Approach 2:
Multiple measurement functions (breakthrough offset correction, phase measurement, position calculation) are merged into a unified processing architecture that shares common hardware resources including the ADC and processing unit. This consolidation reduces device complexity while maintaining the latency benefits of dual-circuit time-division processing
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 proposed solution reduces latency and improves the accuracy of inductive position encoders, making them more reliable for applications with fast-moving objects and allowing them to operate in less clean environments, effectively bridging the performance gap with optical encoders.
Implementation Method 1
stationary sensor coils which are inductively coupled to the moving target. The sensor coils provide electrical output signals
Implementation Method 2
The magnetic field generator and the sensor coils are arranged so that the magnetic coupling between them varies with the position of the movable member relative to the stationary member
Data Source
AI summary
Position sensors include processing circuits. The processing circuits include first and second measurement circuits that each process at least one common sensor signal. A measurement processing circuitry is arranged to use the measurements from each measurement circuit, typically in a time interleaved manner, so that whilst the measurement processing circuitry is using the measurements from one measurement circuit, measurements obtained in the other measurement circuit can be used to determine calibrations that can be used to calibrate subsequent measurements obtained from that measurement circuit.