Per-Wheel Friction Circle Visualization for Tire Load-Adaptive Slip Limits
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Solution Overview
Problem
Existing driving assistance systems fail to accurately inform drivers about tire slip limits and tire usage, as these limits vary with tire load, and merely displaying vehicle acceleration does not convey tire usage effectively.
Innovation Solution
A driving assistance apparatus that calculates and displays a friction circle for each wheel, showing tire force magnitude and direction, allowing drivers to understand tire usage and potential slip through visual feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acceleration limit values are set before vehicle traveling, then comparison with actual acceleration can be performed, but the accuracy of tire slip detection deteriorates because acceleration limit values vary significantly with tire load
Solution Approach 1:
The friction circle is dynamically adjusted based on real-time tire load conditions. The calculation unit computes the friction circle radius according to the current vertical load on each tire, allowing the acceleration limit values to adapt continuously to changing tire load conditions during vehicle operation
Solution Approach 2:
The patent changes the parameter of acceleration limit values from fixed pre-set values to dynamically calculated values based on tire load. By computing the friction circle radius as a function of tire vertical load, the system adjusts the acceleration thresholds to match actual tire conditions
2Ease of operation
If only magnitude and direction of vehicle acceleration are displayed, then simple visual feedback is provided, but the driver cannot understand how appropriately the tire is being used
Solution Approach 1:
The patent adds a new dimension to the display by introducing the friction circle concept. Instead of only showing acceleration magnitude and direction, the system visualizes the friction circle that represents the tire's friction capability, allowing drivers to understand tire usage by comparing the acceleration vector against the friction circle boundary
Solution Approach 2:
The friction circle serves as an intermediary visual element between the raw acceleration data and the driver's understanding of tire usage. It translates complex tire friction characteristics into an intuitive visual representation that shows whether the tire is being used within its capability limits
Data Source
AI summary
A driving assistance apparatus according to the present disclosure includes: a vehicle acceleration detection unit configured to detect vehicle acceleration including lateral acceleration and longitudinal acceleration of a vehicle; a calculation unit configured to calculate for each wheel a friction circle, and a lateral force generated at each wheel and a longitudinal force generated at each wheel on the basis of a result of detection by the vehicle acceleration detection unit; and a display unit configured to display an image based on the friction circle, and a magnitude and/or a direction of a resultant force of the lateral force and the longitudinal force generated at each wheel based on a result of calculation by the calculation unit.