3-Axis Accelerometer Calibration Using Vertical Sample Buffers
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Solution Overview
Problem
Existing 3-axis accelerometers in vehicles face challenges in accurately aligning with vehicle axes due to measurement errors from GPS signals, such as signal delays and multipath distortions, which affect the accuracy of acceleration data.
Innovation Solution
A telematics system that uses a processor, acceleration sensor, and GPS receiver to determine vehicular acceleration information, stores vertical vector samples in a buffer, calculates an average vertical vector, and calibrates the accelerometer axes to align with the vehicle's axes, compensating for velocity information errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS velocity data is used to calibrate accelerometer data, then velocity information can be obtained, but measurement accuracy deteriorates due to signal delays and multipath distortions
Solution Approach 1:
The calibration process is segmented into multiple independent calibration vectors (vertical, forward, lateral) that can be determined separately using different GPS measurement combinations. This segmentation allows each vector to be calibrated using optimal measurement sets, reducing the impact of GPS errors on any single calibration parameter.
Solution Approach 2:
The patent introduces intermediate calibration parameters (calibration vectors and bias terms) that mediate between the raw GPS velocity data and the final accelerometer output. These intermediaries allow for error compensation through mathematical transformations that separate the calibration process from the raw measurements.
2Ease of operation
If 3-axis accelerometer is installed in vehicle, then acceleration data can be collected, but alignment accuracy with vehicle axes deteriorates due to installation variations
Solution Approach 1:
The patent transforms the physical alignment problem into a parameter transformation problem. By introducing calibration vectors and transformation matrices, the system can mathematically correct for installation misalignments without requiring precise physical alignment during installation. The calibration parameters (elements of calibration vectors) are determined through GPS-accelerometer correlation and used to transform accelerometer readings into vehicle-axis-aligned coordinates.
Data Source
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AI summary
Systems and methods for the calibration of 3-axis accelerometers using vertical sample buffers in accordance embodiments of the invention are disclosed. In one embodiment, a telematics system includes a processor, an acceleration sensor, a velocity sensor, and a memory configured to store an acceleration alignment application, wherein the acceleration alignment application configures the processor to receive a velocity information sample using the velocity sensor, determine vehicular acceleration information along at least one vehicle axes using the velocity information sample, receive at least one acceleration sensor acceleration information sample using the acceleration sensor, determine a plurality of vertical vector samples using the vehicular acceleration information, calculate an average vertical vector sample using at least one of the vertical vector samples, and calibrate at least one of the vehicle axes to an acceleration sensor axis using the vehicular acceleration information, the acceleration sensor acceleration sample, and the average vertical vector sample.