Inertial Sensor Calibration via Weighted Offset Drift Correction
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Solution Overview
Problem
Low-cost inertial sensors used in safety systems, such as those in automobiles, experience long-term drift in their null output values, leading to inaccurate readings over time, which can invalidate factory calibration settings and compromise the reliability of safety systems.
Innovation Solution
A method and system for calibrating inertial sensors by calculating a new offset value using a weighted average of sensor output values and prior offset values, with the ability to discard values outside a predetermined range and notify users of potential issues, ensuring accurate recalibration and mitigating the impact of drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-cost inertial sensors are used in safety systems, then the cost of the system is reduced and accessibility is improved, but the sensors experience long-term drift in null output values leading to inaccurate readings over time
Solution Approach 1:
The system performs preliminary calibration actions by storing multiple pre-determined offset values in memory before normal operation begins. These offset values are calculated during manufacturing or initial setup to compensate for expected drift at specific time intervals, allowing the sensor to maintain accuracy without continuous recalibration
Solution Approach 2:
The system dynamically changes the offset parameter used in sensor readings based on elapsed time or operational conditions. By selecting from multiple pre-calculated offset values corresponding to different time periods, the system adapts to drift while maintaining reading accuracy throughout the sensor's operational life
2Measurement precision
If factory calibration settings are used, then the sensor provides accurate readings initially, but long-term drift invalidates the calibration settings over time
Solution Approach 1:
Multiple offset values are pre-calculated and stored in memory during manufacturing or initial calibration, anticipating future drift patterns. This preliminary action ensures that accurate calibration data is available at various time points without requiring continuous factory intervention
Solution Approach 2:
The system incorporates a calibration module that continuously monitors sensor output and automatically selects or updates the appropriate offset value based on elapsed time or detected drift patterns, providing ongoing correction to maintain accuracy throughout the sensor's operational life
3Measurement precision
If continuous calibration is performed to maintain accuracy, then reading precision is maintained over time, but system complexity and computational requirements increase
Solution Approach 1:
Instead of performing full continuous calibration, the system applies partial calibration by selecting from multiple pre-calculated offset values at specific time intervals or operational milestones. This partial action maintains sufficient accuracy for safety applications without the complexity of continuous recalibration algorithms
Solution Approach 2:
The calibration system simplifies complexity by changing only the offset parameter based on time or operational conditions, rather than performing complete sensor recalibration. This selective parameter adjustment maintains accuracy while minimizing computational burden and system complexity
Data Source
AI summary
A calibration system for an inertial sensor includes a calibration module for processing an output value produced by the inertial sensor, the output value related to a detected movement of an object, wherein the calibration module calculates an offset value from a plurality of output values, and memory operatively coupled with the calibration module, the memory capable of storing the plurality of output values and/or the offset value, wherein the inertial sensor is calibrated using the calculated offset value.