Vehicle Speedometer Calibration via Acceleration Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle speedometer systems become inaccurate due to changes in tire rolling radius, tire size modifications, and other factors, leading to errors in vehicle speed measurement, which are not adequately addressed by current calibration methods that rely on specific acceleration and deceleration events.
Innovation Solution
The method involves integrating longitudinal acceleration sensor data between defined reference points to obtain vehicle velocity, comparing it with wheel speed sensor data, and updating relevant parameters like tire diameter or final drive ratio based on slope errors, ensuring accurate vehicle speed measurement by using strict criteria for data acquisition during acceleration and deceleration events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If longitudinal acceleration sensor data is integrated to obtain vehicle velocity during acceleration/deceleration events, then vehicle speed measurement accuracy can be improved, but errors due to improper reference point selection and offset compensation can cause stack-up errors that worsen measurement accuracy
Solution Approach 1:
The patent applies preliminary action by compensating for the longitudinal acceleration sensor offset before integrating the acceleration data to calculate vehicle velocity. The controller determines an offset value during a calibration phase and uses this compensated value as the basis for integration, preventing systematic errors from accumulating during the integration process. This preliminary correction ensures that the integrated velocity calculation starts from an accurate baseline.
Solution Approach 2:
The patent uses wheel speed sensor data as a reference copy to validate and calibrate the vehicle velocity calculated from integrated acceleration data. By comparing the integrated velocity against the wheel speed sensor measurements during controlled acceleration and deceleration events, the system can verify accuracy and make necessary adjustments to the calibration parameters, ensuring the primary measurement system remains reliable.
2Measurement precision
If calibration is performed during acceleration/deceleration events, then vehicle speed accuracy can be improved, but selecting inappropriate events can lead to erroneous calibration and worsen measurement accuracy
Solution Approach 1:
The patent applies parameter changes by establishing specific criteria for selecting valid acceleration and deceleration events based on multiple parameters: the vehicle must be traveling on a level surface (slope within threshold), the acceleration or deceleration rate must fall within predetermined ranges, and the event duration must meet minimum requirements. By dynamically evaluating these parameters, the system ensures that only appropriate calibration events are used, preventing erroneous calibration from occurring during unsuitable conditions such as uphill driving or excessive acceleration.
3Productivity
If tire size or final drive ratio is modified, then vehicle performance can be improved, but speedometer accuracy deteriorates due to changes in rolling radius
Solution Approach 1:
The patent applies self-service by enabling the vehicle's control system to automatically detect and adapt to changes in tire size or final drive ratio through the calibration process. When a driver initiates calibration during a valid acceleration or deceleration event, the system uses the integrated acceleration data and wheel speed sensor data to recalculate the relationship between wheel rotations and actual vehicle distance traveled. This automatically updates the speedometer calibration parameters, allowing the vehicle to self-correct without requiring manual intervention or knowledge of the specific modification made.
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 approach improves the accuracy of vehicle speed measurement by precisely updating relevant parameters, reducing errors in calibration and enhancing the reliability of vehicle speed data used by electronic controllers.
Implementation Method 1
integrating signals of a longitudinal acceleration sensor to obtain a first vehicle velocity
Implementation Method 2
obtaining a second vehicle velocity from a wheel speed sensor
Data Source
AI summary
Methods and systems are provided for updating a relevant vehicle parameter in a vehicle so as to improve accuracy of a vehicle velocity determination. In one example, a method comprises integrating signals of a longitudinal acceleration sensor to obtain a first vehicle velocity and obtaining a second vehicle velocity from a wheel speed sensor between a first and a second reference point, and updating the relevant vehicle parameter as a function of a difference between a slope associated with the first vehicle velocity and another slope associated with the second vehicle velocity. In this way, accuracy of vehicle speed determination via one or more wheel speed sensors may be improved.