Threshold-Based Sensor Data Acquisition for High Sampling Frequency
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Solution Overview
Problem
Conventional A/D conversion circuit devices face challenges in maintaining high sampling frequency and reducing processing load, leading to decreased responsiveness and increased power consumption, especially when dealing with a large number of sensors, as the time required for A/D conversion increases proportionally with the number of sensors, resulting in a trade-off between sampling cycle and spatial resolution.
Innovation Solution
A data acquisition device that includes sensors for detecting physical quantities, analog and digital storage circuits, difference circuits, and a control unit that calculates and compares differences in detected values with threshold values to determine when to update digital values, allowing for efficient A/D conversion only when necessary, thereby reducing processing load and maintaining sampling frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If A/D conversion is performed for all sensor data, then digital data is obtained, but the processing load of the control unit becomes high and power consumption increases
Solution Approach 1:
The patent applies partial action by performing A/D conversion only for sensor data that exhibits significant changes. The determination circuit identifies data with large changes using analog comparison, and only this subset of data undergoes A/D conversion. This selective approach reduces the overall processing load and power consumption while still capturing all meaningful data changes.
Solution Approach 2:
The patent extracts only the necessary data for digital processing by separating data into two groups: data with significant changes (requiring A/D conversion) and data without significant changes (retained in analog form). This extraction principle allows the system to process only essential data digitally, reducing power consumption while maintaining measurement precision for critical changes.
2Measurement precision
If A/D conversion is performed for all sensor data, then digital data is obtained, but the processing load of the control unit becomes high
Solution Approach 1:
The system performs A/D conversion only for data points that exceed a predetermined threshold of change, rather than converting all sensor data. This partial conversion approach significantly reduces the number of data points requiring digital processing, thereby lowering the control unit's processing load and improving overall processing efficiency while maintaining accuracy for significant changes.
Solution Approach 2:
The determination circuit segments sensor data into two distinct categories: data with significant changes (flagged for A/D conversion) and data without significant changes (kept in analog storage). This segmentation allows the control unit to focus processing resources only on the segmented data requiring conversion, improving productivity by avoiding unnecessary processing of stable data.
3Speed
If the number of sensors is reduced to shorten the sampling cycle, then sampling frequency increases, but the distribution density of sensors becomes sparse and spatial resolution deteriorates
Solution Approach 1:
The patent implements dynamic sampling where the sampling frequency for each sensor is adjusted based on its activity level. Sensors detecting significant changes are sampled more frequently and converted to digital data, while sensors with stable readings are sampled less frequently. This dynamic approach allows maintaining high spatial resolution with many sensors while achieving effective high sampling frequency for active sensors, resolving the contradiction between sampling rate and sensor density.
Data Source
AI summary
The disclosure provides a data acquisition device. The data acquisition device includes a sensor that detects a physical quantity as analog data; a digital storage circuit that stores the physical quantity as digital data; a difference circuit that calculates a difference between a previous value of the physical quantity stored in the digital storage circuit and a current value of the physical quantity detected as analog data; and a comparison circuit that compares the difference with a predetermined threshold value; and a control unit. The control unit stores a value calculated by adding or subtracting a predetermined change amount to a previous value of the physical quantity stored in the digital storage circuit as the current value, when the difference exceeds or falls below the threshold value. Since the physical quantity is updated without executing A/D conversion, a decrease in the sampling frequency is suppressed.