Surface Roughness Estimator for Vehicle Terrain Analysis
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Solution Overview
Problem
Existing vehicle control systems struggle to accurately estimate terrain surface roughness independently of vehicle speed, which affects driving mode selection and vehicle control, especially in off-road environments.
Innovation Solution
A surface roughness estimator that combines vertical, longitudinal, and lateral acceleration data, adjusting the combined value based on vehicle speed to generate a surface roughness index, and optionally considers torque differences to determine terrain roughness, allowing for selection of the most appropriate driving mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acceleration data is used to estimate surface roughness, then terrain information can be obtained, but the estimate becomes dependent on vehicle speed which reduces accuracy
Solution Approach 1:
The patent transforms the raw acceleration parameters by combining them in specific ways (e.g., taking absolute values, multiplying accelerations from different axes) and then adjusts the combined value based on vehicle speed to compensate for speed dependence. This parameter transformation approach converts speed-dependent acceleration data into a speed-independent surface roughness estimate.
Solution Approach 2:
The patent introduces an intermediary processing stage between raw acceleration measurement and surface roughness estimation. The combined acceleration value serves as an intermediary that is then adjusted using vehicle speed information to produce the final roughness estimate, effectively mediating between the conflicting requirements of using acceleration data while maintaining speed independence.
2Measurement precision
If multiple acceleration sensors are used to improve measurement accuracy, then more comprehensive terrain data is obtained, but system complexity increases
Solution Approach 1:
The patent makes the acceleration sensing system multi-functional by using a single accelerometer to perform multiple measurement tasks. The same sensor data is processed differently to extract various terrain characteristics, eliminating the need for separate sensors for different measurement purposes and reducing overall system complexity.
Solution Approach 2:
The patent merges multiple acceleration measurements from different axes into a single combined value that represents overall terrain roughness. By combining the absolute values of accelerations from vertical, longitudinal, and lateral axes, the system achieves comprehensive terrain assessment using integrated processing rather than separate dedicated sensors.
Data Source
AI summary
A surface roughness estimator for a vehicle configured to generate a first surface roughness index value indicative of terrain surface roughness and to output a signal in dependence at least in part on the first surface roughness index value, the estimator being configured to receive first acceleration information indicative of a first acceleration along a first axis, receive second acceleration information indicative of a second acceleration along a second axis, calculate a combined value in dependence on the first acceleration and second acceleration, and adjust the combined value in dependence on a speed of the vehicle to generate the first surface roughness index value.