Optical Road Friction Sensing With Radiance-Based Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle vision systems lack normalized, linearized, and calibrated assessment and processing capabilities for objects and road surfaces, which are crucial for accurate object detection and recognition in varying environmental conditions.
Innovation Solution
The system employs calibrated imaging sensors with boresight angles parallel to the vehicle's axis of travel, uses radiance values instead of intensity, and incorporates look-up tables for pixel-level radiance conversion to achieve normalized and linearized photodetector elements, enabling enhanced object condition assessment and HD Map creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intensity values are used for object detection and recognition, then the system can operate with simpler processing, but the assessment accuracy and reliability are insufficient under varying environmental conditions
Solution Approach 1:
The patent transforms the measurement parameter from intensity values to radiance values. This parameter change enables accurate assessment under varying environmental conditions because radiance is a physically meaningful quantity that accounts for lighting conditions, whereas intensity alone does not provide sufficient information for reliable object detection and friction coefficient determination.
2Reliability
If calibrated imaging sensors with radiance conversion are implemented, then normalized and linearized photodetector elements are achieved, but the device complexity increases
Solution Approach 1:
The patent implements preliminary calibration procedures that establish look-up tables mapping pixel values to radiance values before actual object detection. This preliminary action normalizes and linearizes the photodetector elements, ensuring reliable and consistent measurements across different environmental conditions. The calibration is performed once, and the resulting look-up tables are reused, making the initial complexity worthwhile for ongoing reliability.
3Measurement precision
If look-up tables for pixel-level radiance conversion are used, then accurate radiance values are obtained, but the processing time and computational load increase
Solution Approach 1:
The patent pre-computes radiance conversion values and stores them in look-up tables during a calibration phase. During actual object detection, the system simply retrieves pre-computed values from the look-up tables based on pixel measurements, rather than performing complex radiance calculations in real-time. This preliminary computation dramatically reduces processing time during operational use while maintaining high accuracy.
4Ease of operation
If existing vehicle vision systems are used without normalized processing, then the system operation is simpler, but the object detection and recognition accuracy in varying environmental conditions deteriorates
Solution Approach 1:
The patent changes the fundamental measurement parameter from intensity to radiance, which is inherently more robust to environmental variations. Radiance values account for lighting conditions and enable reliable object detection and friction coefficient determination across different environmental conditions, whereas intensity-based systems lack this environmental compensation capability.
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 provides real-time, accurate object detection and recognition, allows for dynamic coefficient of friction determination, and generates authenticated HD Maps without relying on GNSS, enhancing vehicle navigation and safety.
Implementation Method 1
an array of photodetector elements
Data Source
AI summary
Friction plays a vital role in keeping vehicles on the road, as adequate surface friction is necessary for a driver or control system to control/maneuver a vehicle safely, in both longitudinal and lateral directions. Providing adequate friction for safe driving is a key input for highway geometric design, as it is used in determining the adequacy of minimum stopping sight distance, minimum horizontal radius, minimum radius of crest vertical curves, and maximum super-elevation in horizontal curves. Roadway safety is enhanced with a system that determines the coefficient of friction of a road surface prior to a vehicle traversing a roadway. In embodiments, an optical system that determines a coefficient of friction for the road surface in real-time allows a driver or a vehicle safety system to take corrective action in response to changes in road surface friction and to adjust speed or trajectory for roadway topology based on such changes.