Surface Roughness Estimation for Off-Road Vehicle Speed Control
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Solution Overview
Problem
Off-road vehicles face challenges in maintaining accurate path tracking due to ground surface irregularities, leading to operator fatigue and uneven application of crop inputs, as existing automatic guidance systems struggle to account for varying soil conditions and hidden surface irregularities.
Innovation Solution
A method and system that estimate surface roughness by using motion and attitude data from sensors, including location-determining receivers, accelerometers, and gyroscopes, to calculate a surface roughness index, which is then used to adjust the ground speed of the vehicle and its implement, ensuring precise tracking and efficient application of inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automatic guidance system is used to guide vehicle to track path plan, then path tracking capability is improved, but vehicle still deviates from target path plan due to ground surface irregularities
Solution Approach 1:
The system performs preliminary detection of ground surface irregularities using sensors (accelerometers, gyroscopes, location-determining receivers) before the vehicle encounters them. A surface roughness index is calculated in advance, and ground speed adjustments are pre-determined based on predicted deviations, allowing the vehicle to maintain accurate path tracking despite terrain variations.
Solution Approach 2:
The system continuously monitors vehicle position, heading, and yaw rate, comparing actual performance against the target path plan. Based on detected deviations and calculated surface roughness index, the system dynamically adjusts ground speed commands to compensate for terrain effects, creating a closed-loop feedback system that maintains reliable path tracking.
2Productivity
If ground speed is increased to improve productivity, then work area coverage speed is improved, but path tracking accuracy deteriorates due to increased vehicle response to surface irregularities
Solution Approach 1:
The system dynamically adjusts ground speed based on real-time surface roughness index and detected vehicle deviations. In smooth terrain areas, higher speeds are permitted to maximize productivity. In areas with surface irregularities, the system automatically reduces ground speed to maintain path tracking accuracy, creating an optimal balance between productivity and precision throughout the work area.
3Measurement precision
If optical sensors are used to detect surface irregularities, then surface roughness detection capability is improved, but detection accuracy deteriorates due to concealment by crop residue, surface soil, vegetation, or poor visibility
Solution Approach 1:
The system uses the vehicle's motion response as an intermediary indicator of surface roughness. Instead of directly detecting ground characteristics through optical sensors that are blocked by crop residue and vegetation, the system measures vehicle pitch, roll, and heading changes caused by surface irregularities, inferring surface conditions from vehicle dynamics rather than direct optical observation.
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 effectively controls ground speed based on real-time surface roughness data, reducing operator fatigue, improving path accuracy, and ensuring uniform application of crop inputs by dynamically adjusting speed according to the terrain, thereby enhancing operational efficiency and precision.
Implementation Method 1
A location-determining receiver provides a respective position of the vehicle, or its implement, for the sampling interval
Implementation Method 2
A first sensor is adapted to detect pitch data of the off-road vehicle for the sampling interval (e.g., to obtain pitch acceleration)
Implementation Method 3
A second sensor is adapted to detect roll data of the off-road vehicle for the same sampling interval (e.g., to obtain roll acceleration)
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A method and system for estimating surface roughness of a ground for an off-road vehicle to control ground speed comprises detecting motion data of an off-road vehicle traversing a field or work site during a sampling interval. A pitch sensor is adapted to detect pitch data of the off-road vehicle for the sampling interval to obtain a pitch acceleration. A roll sensor is adapted to detect roll data of the off-road vehicle for the sampling interval to obtain a roll acceleration. An electronic data processor or surface roughness index module determines or estimates a surface roughness index based on the detected motion data, pitch data and roll data for the sampling interval. The surface roughness index can be displayed on the graphical display to a user or operator of the vehicle, or applied to control or execute a ground speed setting of the vehicle.