Vehicle Acceleration Sensor Calibration Using Height Position Data
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Solution Overview
Problem
Existing acceleration sensors in motor vehicles struggle to accurately measure longitudinal acceleration due to gravitational influences during uphill or downhill travel, leading to calibration errors and increased tolerances, which can result in residual errors affecting safety-critical monitoring.
Innovation Solution
A calibration method that accounts for the change in height position during a measuring section, using global positioning system data and air pressure measurements to adjust sensor parameters, ensuring accurate longitudinal acceleration measurement by separating gravitational influence from vehicle acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If calibration is carried out using wheel speed measurement, then the calibration process is simple, but calibration errors result because the wheel speed signal includes gravitational influence while the sensor does not
Solution Approach 1:
The patent introduces an intermediary variable (height position change) that mediates between the wheel speed measurement and the acceleration sensor calibration. By using height position data from GPS or barometric pressure as a mediator, the system can separate gravitational influence from actual vehicle acceleration, enabling accurate calibration without direct gravitational measurement.
Solution Approach 2:
The patent replaces the mechanical wheel speed-based calibration system with a hybrid system that incorporates atmospheric pressure or GPS-based height measurements. This substitution allows the system to account for gravitational effects that pure mechanical wheel speed measurements cannot detect, thereby improving calibration accuracy.
2Reliability
If calibration is carried out over a long period to reduce gravitational influence, then gravitational effects are minimized, but height differences between start and end points result in residual errors
Solution Approach 1:
The patent implements feedback by continuously monitoring height position changes during the calibration process and using this information to adjust the calibration calculation. The system measures height at multiple points during the drive cycle and feeds this information back into the calibration algorithm to compensate for gravitational effects, eliminating the need for long calibration periods and avoiding residual errors from height differences.
Solution Approach 2:
The patent performs preliminary measurement of height position at the beginning of the calibration process using GPS or barometric pressure sensors. This preliminary action allows the system to pre-calculate or pre-compensate for gravitational effects before they interfere with the acceleration measurements, enabling accurate calibration even during short drive cycles with elevation changes.
3Adaptability or versatility
If acceleration sensor is used for monitoring, then driver input torque can be appropriately adapted, but gravitational influence during uphill or downhill travel causes incorrect acceleration values
Solution Approach 1:
The patent changes the parameters used for acceleration calculation by incorporating height position data into the acceleration computation. Instead of relying solely on raw acceleration sensor data or wheel speed derivatives, the system modifies the calculation parameters to include gravitational compensation based on measured height changes, thereby improving the precision of longitudinal acceleration measurements while maintaining the adaptability benefits of using an acceleration sensor.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides a more accurate calibration of acceleration sensors, reducing tolerances and enhancing the reliability of safety-critical acceleration monitoring by effectively accounting for gravitational influences during calibration.
Implementation Method 1
accelerations which are caused by gravitational force cannot be measured using this measurement principle... the measurement of the acceleration with the aid of the acceleration sensor does not include the gravitational influence during uphill or downhill travel
Data Source
AI summary
A method is provided for calibrating an acceleration sensor for ascertaining a longitudinal acceleration of a motor vehicle. One or multiple sensor parameter(s) of a sensor model of the acceleration sensor is/are determined, via which the actual longitudinal acceleration of the motor vehicle is ascertainable from a physical sensor variable. The method includes the following steps:ascertaining a change in a vehicle speed during travel over a measuring section;ascertaining a change in the longitudinal acceleration of the motor vehicle during travel over the measuring section with the aid of the acceleration sensor to be calibrated;ascertaining a change in the height position of the motor vehicle during travel over the measuring section; andascertaining the one or the multiple sensor parameter(s) of the sensor model based on the change in the vehicle speed, the change in the longitudinal acceleration of the motor vehicle, and the change in the height position of the motor vehicle during travel over the measuring section.