Vehicle Pitch Angle Estimation via Frequency Component Filtering
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Solution Overview
Problem
Conventional pitch angle estimation methods for vehicles are inaccurate when traveling on roads with significant gradient changes, as the movement of feature points in images can be affected by both the vehicle's pitch angle and road gradients, leading to incorrect pitch angle calculations.
Innovation Solution
A pitch angle estimation apparatus that includes an image acquirer, movement amount calculator, pitch angle calculator, low frequency component calculator, and output determiner, which calculates and filters the pitch angle to account for road gradient changes, preventing the output of inaccurate angles by determining the magnitude of the low frequency component or correcting the pitch angle by reducing its low frequency component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feature point movement is used to estimate pitch angle, then pitch angle can be calculated from image data, but the estimation becomes inaccurate when the vehicle travels on roads with significant gradient changes
Solution Approach 1:
The pitch angle signal is segmented into high-frequency components (vehicle pitch motion) and low-frequency components (road gradient changes) using frequency analysis. This separation allows independent processing of each component to resolve the contradiction between measuring pitch angle accurately and adapting to varying road gradients.
Solution Approach 2:
A low-pass filter is introduced as an intermediary to extract and remove the low-frequency road gradient component from the pitch angle estimation. This intermediary element enables the system to eliminate gradient-induced errors while preserving the high-frequency vehicle pitch information.
2Measurement precision
If additional sensors are added to improve pitch angle estimation accuracy on gradient roads, then measurement precision improves, but device complexity increases
Solution Approach 1:
The existing camera system performs multiple functions: capturing images for feature point extraction and simultaneously providing data for frequency-based pitch angle estimation. The same image processing pipeline serves both feature tracking and spectral analysis, eliminating the need for additional dedicated sensors and reducing system complexity.
Solution Approach 2:
The image acquisition and processing system is designed to serve multiple purposes: traditional feature point-based pitch estimation and the new frequency-based estimation method. This multi-functionality allows accurate pitch angle measurement on gradient roads without adding specialized hardware.
3Measurement precision
If low frequency component filtering is applied to remove road gradient effects, then pitch angle accuracy improves, but some legitimate pitch angle information may be lost
Solution Approach 1:
The filtering approach dynamically adapts to the actual pitch angle signal characteristics by using frequency domain analysis. The system identifies and removes only the low-frequency components corresponding to road gradients while preserving high-frequency components representing vehicle pitch motion, preventing information loss through intelligent frequency-based differentiation.
Data Source
AI summary
In a pitch angle estimation apparatus, an image acquirer sequentially acquires images in a forward or rearward direction of a vehicle. Each image is referred to as a frame. A movement amount calculator extracts a feature point from each of the images acquired by the image acquirer and calculates an amount of movement of the feature point in a vertical direction of the image. A pitch angle calculator calculates a pitch angle of the vehicle based on the amount of movement of the feature point. An output unit outputs the pitch angle calculated by the pitch angle calculator. A low frequency component calculator calculates a low frequency component of the pitch angle calculated by the pitch angle calculator. An output determiner determines whether to output the pitch angle based on the magnitude of the low frequency component calculated by the low frequency component calculator.