Stereo Line-Scan Camera Road Deflection Measurement
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Solution Overview
Problem
Current methods for measuring road surface deflection and vehicle-surface interaction are inefficient, lack accuracy, require significant user intervention, or are prohibitively expensive, failing to account for viscoelastic properties and dynamic vehicle-road interactions.
Innovation Solution
A system utilizing stereo line-scan camera pairs, a digital electro-optical camera, an inertial measurement unit, and a processor to capture 3D images of the road surface, compensate for acceleration and vibration effects, and calculate surface deflection by comparing unloaded and loaded road surface data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FWDs apply pulse load to measure deflection, then measurement accuracy is improved, but time efficiency deteriorates due to delays on public infrastructure
Solution Approach 1:
The patent replaces the mechanical pulse loading system of FWDs with a passive optical measurement system using stereo line-scan cameras. The vehicle's own weight serves as the load, and deflection is measured optically without mechanical impact devices, eliminating the time-consuming pulse load application while maintaining measurement capability.
Solution Approach 2:
The patent uses optical copying through stereo vision to capture 3D images of the road surface. Instead of mechanical measurement, the system creates digital 3D models of the surface geometry, allowing deflection calculation through image processing and comparison of surface positions before and during load application.
2Productivity
If RWDs use laser ranging to measure deflection, then time efficiency is improved, but measurement precision deteriorates compared to FWDs
Solution Approach 1:
The patent replaces laser ranging technology with stereo line-scan camera systems. While both are non-contact optical methods, the stereo camera approach provides higher precision by capturing detailed 3D surface geometry through photogrammetry, enabling more accurate deflection measurements while maintaining the time efficiency of continuous rolling measurement.
3Measurement precision
If novel FEMs are used to model viscoelastic properties, then accuracy in predicting pavement distress is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables the road surface to serve itself as the test object by using the vehicle's own weight as the load and the surface's own deformation as the measurement target. This eliminates the need for complex external loading equipment and sophisticated FEM models, achieving practical measurement through direct observation of surface behavior under realistic loading conditions.
4Ease of operation
If existing measurement methods are used, then implementation is simpler, but accuracy in measuring dynamic vehicle-surface interaction deteriorates
Solution Approach 1:
The patent implements continuous measurement during vehicle rolling rather than discrete spot measurements. The line-scan cameras continuously capture surface geometry as the vehicle moves, enabling measurement of dynamic vehicle-surface interaction throughout the rolling process, not just at static points before and after loading.
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
The system provides accurate, efficient, and cost-effective measurements of road surface deflection and stress, enabling detailed analysis of road health and performance without the need for extensive user intervention or expensive equipment.
Implementation Method 1
an inertial measurement unit (IMU) to detect inertial forces acting upon the sensor rig
Implementation Method 2
a first stereo line-scan camera pair mounted on a sensor rig, wherein the first stereo line-scan camera pair captures a first set of 3D images of a road surface
Data Source
AI summary
A system for measuring surface deflection of a road includes a first stereo line-scan camera pair on a sensor rig and for capturing a first set of 3D images of a road surface; a second stereo line-scan camera pair on the sensor rig and for capturing a second set of 3D images of the road surface; at least one digital electro-optical (EO) camera rigidly attached to the sensor rig; an inertial measurement unit (IMU) detecting inertial forces acting upon the sensor rig; and a processor compensating for acceleration and vibration effects upon the sensor rig; and calculating the surface deflection of the road based on the first and second sets of 3D images. The processor utilizes imagery from the EO camera and inertial measurements from the IMU to produce 2D mosaics and 3D reconstructions of the road surface from the first and second sets of 3D images.