Radial Acceleration Sensor Calibration Using Motion Phase Analysis
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Solution Overview
Problem
Current methods for calibrating radial acceleration sensors in motor vehicles are limited by constant error drift over time and temperature variations, and rely on simplistic assumptions such as zero radial acceleration when the vehicle is stationary, leading to measurement inaccuracies.
Innovation Solution
A method that calibrates radial acceleration sensors by acquiring signals during motion, detecting local extrema, determining wheel rotation frequency, low-pass filtering, and calculating constant error independently of vehicle speed, without assuming zero radial acceleration at rest, using quadratic interpolation and linear regression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If calibration is performed using simplified models assuming constant speed or neglecting sinusoidal components, then the calibration process can be implemented during nonspecific phases of travel, but measurement precision deteriorates due to simplistic assumptions
Solution Approach 1:
The patent changes the approach from assuming constant speed to utilizing variable speed phases, specifically using acceleration and deceleration phases where the derivative of speed is non-zero. This parameter change allows the system to exploit the relationship between radial acceleration, angular velocity, and angular acceleration to accurately determine constant error without requiring simplified models
Solution Approach 2:
The patent employs feedback by continuously monitoring the radial acceleration signal and comparing it with the expected sinusoidal pattern during acceleration and deceleration phases. The system uses the detected local extrema and phase information to iteratively refine the constant error determination, ensuring high precision while maintaining ease of operation during normal driving phases
2Loss of time
If calibration assumes zero radial acceleration when the vehicle is stationary, then the calibration can be performed during stationary periods, but measurement precision deteriorates due to the inaccurate assumption that radial acceleration is exactly zero
Solution Approach 1:
Instead of using stationary periods where radial acceleration is assumed to be zero, the patent inverts the approach by using motion phases (acceleration and deceleration) where the radial acceleration follows a predictable sinusoidal pattern. This inversion allows accurate constant error determination without relying on the inaccurate zero-acceleration assumption, while still utilizing readily available calibration time during normal vehicle operation
3Device complexity
If the radial acceleration sensor operates without calibration, then the device complexity is reduced, but measurement precision deteriorates due to constant error drift over time and temperature variations
Solution Approach 1:
The patent implements self-service calibration where the radial acceleration sensor calibrates itself using its own output signals during normal vehicle operation. The system automatically detects local extrema, determines phase information, and calculates constant error without requiring external calibration equipment or complex additional hardware. This self-calibration approach maintains low device complexity while significantly improving measurement precision by compensating for constant error drift
Solution Approach 2:
The patent employs periodic action by performing calibration during regular acceleration and deceleration phases that occur naturally during vehicle operation. The system periodically analyzes the radial acceleration signal during these phases to update the constant error value, ensuring continuous precision improvement without requiring dedicated calibration events or increasing system complexity
Data Source
AI summary
A method for calibrating a radial acceleration sensor of a wheel of a vehicle including the following steps: acquisition, by the sensor, of signals Si, each signal Si being acquired during a predetermined time window Wi when the vehicle is in motion, the windows Wi being different from one another; detection, for each time window Wi, of local extrema of the signal Si associated respectively with phase values and detection instants; determination, for each time window Wi, of a frequency Fi of the rotation of the wheel of the vehicle as a function of the phase values and of the detection instants for the local extrema detected; low-pass filtering of the signals Si, so as to obtain, for each time window Wi, a filtered value Zi; calibration of a constant error Ec of the radial acceleration sensor as a function of the filtered values Zi and of the frequencies Fi.