Wheel Free-Rolling Control for Accurate Vehicle Speed Estimation
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Solution Overview
Problem
There is a need for reliable and cost-effective methods to determine vehicle speed over ground for heavy-duty vehicles, particularly in challenging environments and operating conditions such as low friction, split friction, and during maneuvering involving large wheel forces.
Innovation Solution
A Vehicle Motion Management (VMM) system that combines wheel speed sensors and inertial measurement units (IMUs) to estimate vehicle speed over ground. The system includes a motion estimation function that models errors in the estimated vehicle motion state and outputs a free-rolling request to reduce wheel slip set-points when errors exceed an acceptance criterion, ensuring accurate speed determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wheel speed sensors are used to determine vehicle speed over ground, then the measurement is simple and cost-effective, but the accuracy deteriorates in low friction conditions and during maneuvering with large wheel forces due to wheel slippage
Solution Approach 1:
The patent combines multiple measurement methods (wheel speed sensors, IMU, GPS, camera systems) into a hybrid system that leverages the strengths of each while compensating for their weaknesses. The wheel speed sensors provide cost-effective baseline data, while complementary systems correct for slippage errors in low-friction conditions.
Solution Approach 2:
The patent introduces intermediary systems such as IMUs and friction estimation algorithms that act as mediators between the wheel speed sensors and the final vehicle speed calculation. These intermediaries detect wheel slippage conditions and provide correction factors to maintain accuracy.
2Speed
If wheel slip based control is used for heavy-duty vehicles, then the control response is faster and more accurate, but the reliability of vehicle speed determination deteriorates in challenging environments due to wheel slippage
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor wheel slip conditions and vehicle dynamics. When slippage is detected through sensor data analysis, the system adjusts control parameters and switches to alternative speed determination methods, ensuring reliable operation across varying conditions.
Solution Approach 2:
The patent employs dynamic control strategies that adapt the wheel slip set-points in real-time based on road friction conditions and vehicle state. The system transitions between different control modes (wheel slip-based vs. alternative methods) depending on the reliability of speed determination, maintaining both responsiveness and reliability.
3Reliability
If IMU and wheel speed sensor combination is used for vehicle speed determination, then the measurement is more robust, but the device complexity increases
Solution Approach 1:
The patent segments the vehicle into multiple independent measurement zones (front wheels, rear wheels, left side, right side), each with its own sensors and processing. This allows the system to selectively use data from reliable wheels and reduces the impact of slippage in any single location, maintaining reliability without requiring a complete system overhaul.
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 VMM system provides accurate and reliable estimation of vehicle speed over ground, even in conditions with high wheel slip, by selectively reducing wheel slip to improve data accuracy and maintain efficient wheel slip-based control of heavy-duty vehicles.
Implementation Method 1
at least one wheel speed sensor configured to output a wheel speed signal indicative of a rotation speed of a respective wheel on the vehicle
Implementation Method 2
at least one IMU configured to output an IMU signal indicative of an acceleration of the vehicle
Data Source
AI summary
A vehicle motion management, VMM, system for a heavy-duty vehicle has at least one wheel speed sensor to output a wheel speed signal indicative of a rotation speed of a respective wheel on the vehicle, at least one inertial measurement unit, IMU, to output an IMU signal indicative of an acceleration of the vehicle, a motion estimation function to estimate a vehicle motion state comprising vehicle speed over ground, based at least in part on the wheel speed signal and at least in part on the IMU signal, and a motion support device, MSD, coordination function to coordinate actuation of a plurality of MSDs of the heavy-duty vehicle in dependence of a vehicle motion request and the vehicle motion state. The motion estimation function models an error in the estimated vehicle motion state, and to output a free-rolling request to the MSD coordination function in case the modelled error fails to meet an acceptance criterion. The MSD coordination function reduces a wheel slip set-point of one or more wheels of the heavy-duty vehicle in response to receiving the free-rolling request from the motion estimation function.