Closed-loop tire stiffness and friction estimation
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Solution Overview
Problem
Existing methods for estimating road friction and tire stiffness, particularly open loop approaches, fail to reliably calibrate tire characteristics during operation and do not provide measures of uncertainty, leading to inaccurate and unreliable estimates.
Innovation Solution
A closed-loop method using slip-related values from vehicle sensors, such as wheel speed and acceleration, to calculate and feedback tire stiffness and friction values, allowing for iterative refinement and uncertainty measurement, with optional vehicle connectivity for calibration and stiffness correction based on various factors like temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop approaches are used to estimate road friction based on tire identification, then the estimation process is simple, but the reliability and accuracy of the estimates deteriorate due to inability to calibrate during operation
Solution Approach 1:
The patent implements a closed-loop estimation system where the estimated tire stiffness is fed back into the friction estimation process. This feedback mechanism allows the system to continuously refine its estimates during operation, adapting to changing tire characteristics without requiring manual recalibration or complex identification procedures.
2Device complexity
If tire characteristics are assumed constant throughout tire lifetime, then the estimation process is simple, but the measurement precision deteriorates due to inability to account for variations
Solution Approach 1:
The patent transitions from static tire characteristic assumptions to dynamic estimation. The system continuously estimates tire stiffness during operation, allowing the parameters to adapt to changing conditions such as temperature, pressure, wear, and load variations throughout the tire's lifetime.
3Ease of operation
If open loop approaches are used without uncertainty measures, then the system is simpler to operate, but the reliability of estimates deteriorates due to lack of uncertainty quantification
Solution Approach 1:
The closed-loop system not only provides continuous refinement of friction and stiffness estimates but also generates uncertainty measures as part of the estimation process. This feedback mechanism enables the system to quantify the reliability of its estimates while maintaining automated operation.
4Reliability
If closed loop estimation is implemented to calibrate tire characteristics during operation, then the reliability and accuracy of estimates improve, but the device complexity increases
Solution Approach 1:
The patent employs a closed-loop feedback system where estimated tire stiffness is continuously fed back into the friction estimation model. This approach achieves reliable calibration during operation by using the vehicle's existing sensors and control systems, avoiding the need for additional complex hardware or manual intervention.
Solution Approach 2:
The system performs self-calibration during normal vehicle operation without requiring external intervention, specialized equipment, or manual procedures. The closed-loop estimation automatically adapts to changing tire characteristics using data from the vehicle's existing sensor suite.
Data Source
AI summary
The disclosed invention makes use of slip related values to calculate friction related values and tire stiffness related values and feeds back an estimated tire stiffness relates value or a calculated friction related as a basis for further calculations. In particular, the disclosure relates to methods, apparatuses and computer program products to achieve the mentioned objective.