Road Surface Profiling Without Minimum Speed Limits
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Solution Overview
Problem
Inertial profilers require a minimum speed threshold to generate accurate surface profiles due to elevation drift caused by double-integration of accelerometer data, leading to exclusion of data from startup and stoppage sections, and necessitating road closures or traffic control in urban areas.
Innovation Solution
A surface profiler system that blends inertial profile data with running slope profile data using high-pass and low-pass filters, or Kalman filters, to generate accurate profiles at any speed without lead-in or lead-out distances, utilizing INS and GNSS data to eliminate secondary sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inertial profilers use double-integration of accelerometer data to generate surface profiles, then elevation measurements can be obtained, but elevation drift occurs over time leading to inaccurate data
Solution Approach 1:
The patent introduces GPS elevation data as an intermediary reference to correct the drift in inertial profiler measurements. The GPS provides absolute elevation references at multiple points along the travel path, which serve as mediators to adjust and correct the relative elevation measurements from the inertial profiler, thereby eliminating drift accumulation while preserving the high-precision short-wavelength surface profile data.
Solution Approach 2:
The patent implements a feedback mechanism where GPS elevation measurements are continuously compared with inertial profiler data, and the difference (drift) is used to generate correction factors that are applied back to the inertial profiler measurements. This closed-loop feedback system continuously eliminates elevation drift throughout the measurement process.
2Productivity
If profilers operate at low speeds or during stops, then more complete surface coverage is achieved, but data accuracy deteriorates due to elevation drift
Solution Approach 1:
GPS elevation data serves as an intermediary reference that enables accurate profiling during stops and low-speed operations. By providing absolute elevation references independent of vehicle speed, the GPS mediator allows the system to maintain measurement precision even when the vehicle is stationary or moving slowly, thereby achieving complete surface coverage without sacrificing accuracy.
3Measurement precision
If profilers require minimum speed threshold operation, then data accuracy is maintained, but lead-in and lead-out distances are required necessitating road closures
Solution Approach 1:
GPS elevation references act as intermediaries that eliminate the need for minimum speed thresholds. By providing absolute elevation data at any vehicle speed or stop, the GPS mediator allows accurate profiling to begin immediately without requiring lead-in distance to reach minimum speed, and can continue through stops without lead-out distance requirements, thereby eliminating road closure time losses.
4Productivity
If profilers collect data during accelerations and decelerations, then complete surface profiles are obtained, but artificial bumps appear in the data
Solution Approach 1:
GPS elevation data serves as a stable intermediary reference that is independent of vehicle dynamics. During accelerations and decelerations, the GPS provides accurate absolute elevation measurements that are not affected by vehicle motion, allowing the system to distinguish between real surface features and artificial bumps caused by vehicle dynamics, thereby maintaining data completeness and accuracy simultaneously.
Data Source
AI summary
A profiler arranged to be used on a host vehicle. The profiler is capable of (a) receiving data collected by the profiler while traveling over a surface and (b) generating a surface profile using the data collected with no minimum speed requirement. Since there is no minimum speed requirement, the profiler is capable of generating valid, repeatable and reliable road surface profiles in situations not previously possible, such as during a stop, during acceleration of the host vehicle, during deceleration of the host vehicle, or while the host vehicle is traveling at very low speeds below thresholds typically required for prior profilers.