Vehicle Friction Potential Detection via Asymmetric Wheel Torque
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Solution Overview
Problem
Current methods for determining the friction coefficient potential of a road surface require operating a vehicle in a limit range or are not feasible for everyday driving, limiting the ability to plan and execute safe driving maneuvers.
Innovation Solution
A method that unequally distributes total torque among vehicle wheels to detect slip and calculate friction coefficient potential, allowing for continuous assessment without altering the vehicle's planned operation, using wheel torque and slip measurements to differentiate between instantaneously used and maximum friction coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the vehicle is operated in a limit range to determine friction coefficient potential, then the friction coefficient potential can be exactly determined, but the vehicle operation is restricted and not suitable for everyday driving
Solution Approach 1:
The patent applies partial action by generating only minor slip at selected wheels rather than operating in a full limit range. This partial slip is sufficient to determine friction coefficient potential while maintaining normal vehicle operation and not requiring the vehicle to be driven to its limits.
Solution Approach 2:
The system uses the vehicle's own wheel slip and torque data that are already available during normal operation to determine friction coefficient potential. No external test procedures or special operating conditions are required, as the vehicle's normal driving dynamics provide the necessary information.
2Measurement precision
If total torque is unequally distributed among wheels to generate slip for measurement, then friction coefficient potential can be determined without limit range operation, but the torque distribution becomes more complex
Solution Approach 1:
The patent applies local quality by selectively applying torque modulation to specific wheels (e.g., one or two wheels) rather than uniformly distributing torque across all wheels. This localized approach generates the necessary slip information at specific contact patches while keeping the overall torque distribution relatively simple.
Solution Approach 2:
The system intentionally creates asymmetric torque distribution among wheels to generate differential slip. By applying different torque levels to different wheels, the system creates measurable slip variations that reveal friction coefficient potential without requiring complex symmetric control strategies.
3Measurement precision
If slip is generated at wheels to determine friction coefficient, then real-time friction assessment is possible, but wheel wear and energy consumption may increase
Solution Approach 1:
The patent uses minimal slip generation rather than sustained high-slip operation. By creating only small amounts of slip momentarily to extract friction coefficient information, the system achieves real-time assessment while minimizing additional wheel wear and energy consumption compared to continuous high-slip testing.
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
Enables real-time determination of friction coefficient potential at any vehicle position, enhancing driving safety by creating a friction coefficient map that can be used by multiple vehicles to plan maneuvers, without increasing wear or energy consumption.
Implementation Method 1
The slip is dependent, among other things, on a vertical force of the wheel and a friction coefficient potential of the ground surface
Data Source
AI summary
A method for determining a friction coefficient potential of a road surface. A total torque for operating a vehicle is unequally distributed among at least two wheel torques at wheels of the vehicle. The friction coefficient potential is ascertained using a detected slip between the road surface and at least one of the wheels and the wheel torque present at the wheel.