Steering Pulse Road Friction Estimation During Vehicle Motion
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Solution Overview
Problem
Existing methods for automatically determining road friction are not versatile or accurate enough, particularly when a vehicle is in motion, and there is a need for methods that can provide reliable and adaptive friction estimation without significantly affecting vehicle motion.
Innovation Solution
A method for estimating road friction in a control unit of a heavy-duty vehicle involves generating a steering pulse with limited duration and magnitude, measuring the vehicle's response, and adapting the pulse based on vehicle dynamics and conditions to ensure minimal impact on motion, using sensors to analyze the response for friction estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a steering pulse is applied to estimate road friction, then measurement precision is improved, but vehicle motion stability deteriorates
Solution Approach 1:
The patent applies a steering pulse with limited magnitude and duration - not a full steering action - to generate measurable vehicle response while maintaining stability. The partial action provides sufficient data for friction estimation without causing excessive vehicle motion that would compromise stability or safety.
Solution Approach 2:
The steering pulse is applied as a periodic, time-limited action rather than a continuous steering input. This allows the system to gather measurement data at specific intervals while maintaining normal vehicle operation between pulses, thus balancing measurement needs with operational stability.
2Measurement precision
If the vehicle is stationary for friction estimation, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The system performs friction estimation during normal vehicle operation rather than requiring the vehicle to be stationary first. By conducting measurements during regular driving, the system eliminates the need for separate stationary testing phases, thus maintaining productivity while obtaining friction data.
Solution Approach 2:
The vehicle uses its own normal driving motion to generate the necessary response data for friction estimation. The regular vehicle operation serves dual purposes: transportation and friction measurement, eliminating the need for dedicated stationary testing time and thus maintaining productivity.
3Measurement precision
If steering pulse magnitude is increased to improve measurement signal, then measurement precision is improved, but object-affected harmful factors increase
Solution Approach 1:
The patent uses a steering pulse with limited magnitude that is sufficient to generate measurable vehicle response but not so large as to cause harmful motion disruption. This partial action provides the necessary measurement signal while keeping the vehicle motion disruption within acceptable limits.
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 allows for reliable and adaptive road friction estimation while the vehicle is in motion, providing accurate results with minimal disruption, enhancing vehicle safety and performance by accounting for various factors like vehicle type, load, speed, and environment.
Implementation Method 1
Road friction plays an important part in the control of most vehicles, mainly since it limits the wheel forces that can be generated by the vehicle at any given point in time.
Data Source
AI summary
A method performed in a control unit of a heavy-duty vehicle for estimating road friction, the method comprising, while the vehicle is in motion, generating a steering pulse having a limited time duration and a limited magnitude, measuring a response by the vehicle to the steering pulse, and estimating a road friction value based on the measured response by the vehicle.