Vehicle Road Slope Estimation Using Driving Condition Correction Maps
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Solution Overview
Problem
Existing methods for estimating road slope using acceleration sensors in vehicles often produce inaccurate results during turning, acceleration, or deceleration, leading to undesirable driving conditions when controlling engine and transmission systems.
Innovation Solution
A road slope estimation method that calculates a final slope by correcting the basic slope obtained from an acceleration sensor using acceleration/deceleration, turning, steering, starting, and braking correction maps, based on vehicle speed, acceleration, and other parameters to provide a more accurate representation of the road slope for efficient vehicle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If slope information is obtained using only the acceleration sensor output value, then the measurement process is simple, but the measurement precision deteriorates during turning, acceleration, or deceleration
Solution Approach 1:
The correction process is segmented into multiple independent correction maps (acceleration/deceleration correction map, turning correction map, steering correction map, starting correction map, braking correction map). Each map handles a specific driving condition separately, allowing the system to address different error sources independently while maintaining overall system manageability
Solution Approach 2:
Multiple correction maps are introduced as intermediary elements between the raw acceleration sensor data and the final slope calculation. These correction maps act as mediators that gradually refine the slope estimation by compensating for specific driving condition errors, transforming inaccurate basic slope data into accurate final slope information
2Measurement precision
If multiple correction maps are used to improve slope estimation accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system changes parameters (vehicle speed, acceleration, steering angle) to determine which correction map to apply and how to weight their contributions. By dynamically adjusting correction parameters based on current driving conditions, the system achieves high precision without requiring all correction maps to operate simultaneously, thus managing complexity
Solution Approach 2:
The correction system is designed to be dynamic rather than static. The controller selectively applies different correction maps based on real-time detection of driving conditions (acceleration, turning, steering, starting, braking). This dynamic adaptation allows the system to maintain high accuracy while keeping the active correction mechanism simple at any given moment
3Reliability
If basic slope calculation is used without corrections, then the calculation process is fast and simple, but the reliability of vehicle control deteriorates
Solution Approach 1:
Correction values are pre-calculated and stored in lookup tables (correction maps) during system development. During actual vehicle operation, the controller only needs to retrieve pre-computed correction values based on current sensor readings, rather than performing complex real-time calculations. This preliminary preparation ensures reliable corrections are applied quickly without significant computational delay
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 allows for more accurate road slope estimation, improving vehicle efficiency by correcting for variations in driving conditions, thereby enhancing the control of engine and transmission systems.
Implementation Method 1
calculating, by a controller, a basic slope based on an output value of an acceleration sensor of the vehicle
Implementation Method 2
The vehicle speed change rate of the acceleration/deceleration correction map may be a time-dependent change rate of a vehicle speed calculated by using an output value of a wheel speed sensor of a vehicle
Data Source
AI summary
Proposed is a road slope estimation method for a vehicle. The method includes: calculating, by a controller, a basic slope based on an output value of an acceleration sensor of the vehicle; calculating, by the controller, an acceleration/deceleration correction value from an acceleration/deceleration correction map; and calculating, by the controller, a turning correction value from a turning correction map. The method further includes: calculating, by the controller, a final slope based on the basic slope, the acceleration/deceleration correction value, and the turning correction value; and controlling the vehicle based on the final slope.