Vehicle Control Using Slip Ratio-Based Road Friction Estimation
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Solution Overview
Problem
Existing control methods for unmanned vehicles struggle to accurately adapt to road surfaces with varying friction coefficients, particularly ice and snow, leading to potential loss of vehicle control due to noise contamination in real-time data updates.
Innovation Solution
A method involving the calculation of road friction coefficients using different strategies based on slip ratios, incorporating slip ratio intervals and least square methods with forgetting factors, to enhance precision and adapt vehicle control in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If real-time data updates are used to adapt to varying road surfaces, then adaptability is improved, but noise contamination causes loss of vehicle control
Solution Approach 1:
The system pre-calculates and stores friction coefficient lookup tables for different slip ratio intervals before actual vehicle operation. When the vehicle encounters varying road surfaces, it directly queries these pre-prepared tables rather than calculating in real-time, thus adapting to road conditions without introducing noisy real-time calculations that could compromise control stability
Solution Approach 2:
The patent introduces slip ratio intervals as an intermediary layer between raw slip ratio data and friction coefficient determination. By categorizing slip ratios into discrete intervals and associating each interval with a pre-calculated friction coefficient, the system mediates between real-time vehicle state data and control decisions, filtering out noise while maintaining adaptability to road surface changes
2Measurement precision
If friction coefficient lookup tables are updated in real-time, then precision is improved, but noise contamination occurs
Solution Approach 1:
Friction coefficient lookup tables are pre-calculated and stored for various slip ratio intervals before vehicle operation begins. This preliminary preparation allows the system to achieve precise friction coefficient determination by simply querying stored values based on current slip ratio, without performing noisy real-time calculations
Solution Approach 2:
The patent extracts the friction coefficient calculation from the real-time control loop by pre-computing and storing these values in lookup tables. This separation removes the potentially noisy calculation process from the time-critical control path, maintaining precision while eliminating noise generation during actual vehicle operation
3Manufacturing precision
If multiple calculation strategies are invoked based on slip ratio intervals, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the continuous slip ratio range into discrete intervals, with each interval associated with a specific pre-calculated friction coefficient. This segmentation transforms a complex continuous calculation problem into a simpler discrete lookup process, maintaining control accuracy while reducing computational complexity
Solution Approach 2:
The system changes the parameter representation from continuous friction coefficient calculations to discrete slip ratio interval categories. By transforming the problem from calculating continuous values to selecting from discrete pre-computed values based on slip ratio intervals, the patent maintains precision while simplifying the computational approach
Data Source
AI summary
A method for vehicle control, including: obtaining a slip ratio in a current control cycle of a vehicle; calculating a road friction coefficient in the current control cycle of the vehicle by invoking a corresponding calculation strategy according to the slip ratio; and controlling the vehicle in real time by inputting the road friction coefficient into a vehicle control optimization model to obtain a control instruction for the current control cycle of the vehicle.