Dithered Calibrated Sensors for Zero-Bias and Low-Noise Navigation
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Solution Overview
Problem
High precision sensors face challenges in maintaining zero-bias and low-noise outputs due to environmental factors like temperature variations, power cycling, and mechanical shocks, which are difficult to model during factory calibration, affecting navigation algorithms.
Innovation Solution
The use of dithered calibrated sensors arranged orthogonally to provide low-noise and zero-bias measurements, where one sensor offers low noise along one axis and zero bias along another, allowing a processing unit to combine measurements for accurate calibration and error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If factory calibration is performed to eliminate bias errors, then zero-bias output is achieved, but bias errors reappear under environmental variations such as temperature, power cycling, and mechanical shock
Solution Approach 1:
The system performs preliminary calibration actions by dithering the sensor input axis during calibration mode to measure and store bias error characteristics. This preliminary measurement of bias under various conditions enables the system to compensate for environmental variations when operating in navigation mode, preventing bias errors from reappearing despite temperature, power cycling, or mechanical shock variations.
Solution Approach 2:
The system changes the operational parameters of the sensor by rotating the input axis through dithering motion during calibration. This parameter change allows the system to measure bias errors at multiple orientations and accumulate statistics to characterize bias behavior under different conditions, enabling more robust compensation for environmental variations.
2Measurement precision
If dithered calibration is performed to remove bias error, then zero-bias measurement is achieved, but noise increases due to the dithering motion
Solution Approach 1:
The system applies partial dithering action by rotating the input axis through a limited angular range rather than continuous rotation. This partial action is sufficient to measure bias error characteristics and enable compensation, while minimizing the introduction of noise. The dithering is applied only during calibration mode, not during normal navigation operations.
Solution Approach 2:
The system segments the operational modes into calibration mode and navigation mode. During calibration mode, dithering is applied to measure and remove bias errors. During navigation mode, the sensor operates without dithering to provide low-noise measurements. This segmentation allows bias removal without continuous noise generation.
3Measurement precision
If multiple dithered calibrated sensors are used to provide low-noise and zero-bias measurements, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The system merges the outputs of multiple dithered calibrated sensors through algorithmic combination in the processing unit. By combining measurements from multiple sensors that have been calibrated to provide both low-noise and zero-bias characteristics, the system achieves improved measurement accuracy while sharing the calibration burden across multiple components.
Solution Approach 2:
The dithered calibrated sensors serve multiple functions: they provide both low-noise measurements and zero-bias measurements depending on the axis of measurement. This multi-functionality reduces the need for separate dedicated sensors for noise reduction and bias correction, thereby managing device complexity while improving measurement precision.
Data Source
AI summary
Systems and methods for noise and drift calibration using dithered calibration, a system comprising a processing unit; and two or more dithered calibrated sensors that provide directional measurements to the processing unit, wherein a dithered calibrated sensor in the dithered calibrated sensors has an input axis that rotates about an axis such that bias error can be removed by the processing unit; wherein the dithered calibrated sensor provides a zero-bias measurement along a first axis and a low-noise measurement along a second axis, the second axis being orthogonal to the first axis; wherein the dithered calibrated sensors are arranged such that the dithered calibrated sensor provide low-noise and zero-bias measurements along the measured axes; and wherein the processing unit executes an algorithm to combine measurements that are along the same axis to produce a measurement for each measured axis that has both low-noise and zero-bias.