Vehicle Pitch and Road Grade Estimation Using Observer Software
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for accurately measuring road grade and vehicle pitch angles are costly and prone to inaccuracies due to measurement device offsets and noise, making it challenging for autonomous driving systems to differentiate between vehicle pitch and road grade movements.
Innovation Solution
A system using a three-axis inertial-measuring device and a correcting observer software module with tuned observer gains to estimate vehicle pitch and road grade angles simultaneously, improving accuracy and feasibility by processing pitch rate and angle data to estimate road grade angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated optical sensors or multi-antenna GPS arrangements are used to measure road grade and vehicle pitch angles, then measurement accuracy is improved, but system cost increases significantly
Solution Approach 1:
The patent uses a software-based observer to create a virtual model that copies and estimates the behavior of the physical system (vehicle pitch and road grade). Instead of using expensive physical sensors to directly measure these angles, the system uses a corrected accelerometer signal to drive a software observer that replicates the dynamics of pitch motion, providing accurate estimates without the high cost of optical sensors or multi-antenna GPS arrangements
Solution Approach 2:
The patent replaces mechanical/optical measurement systems with a software-based estimation system. The corrected accelerometer signal (free from pitch contamination) is used to drive a software observer that mathematically estimates pitch angle and road grade, substituting expensive physical sensing hardware with computational algorithms that process existing sensor data
2Measurement precision
If GPS units are used to detect pitch-direction movement, then pitch movement detection accuracy is improved, but the system cannot differentiate between vehicle pitch and road grade without accurate road grade data
Solution Approach 1:
The patent segments the pitch-direction acceleration signal into two distinct components: one component driven by road grade changes and another component driven by vehicle pitch motion. By using the corrected accelerometer signal to selectively drive the observer, the system separates these coupled motions and independently estimates both road grade angle and vehicle pitch angle, eliminating the ambiguity present in traditional GPS-based approaches
3Adaptability or versatility
If a three-axis inertial-measuring device is used to measure pitch rate, then measurement capability is improved, but measurement device offset and noise cause inaccuracies
Solution Approach 1:
The patent implements a feedback mechanism where the software observer continuously estimates pitch angle based on the corrected accelerometer signal, and this estimated pitch angle is fed back to correct the pitch rate measurements from the inertial-measuring device. The feedback loop compensates for offset and noise errors by comparing the observed pitch dynamics with the raw sensor measurements and adjusting the estimates accordingly
Solution Approach 2:
The patent changes the parameter being measured from raw pitch rate (which contains offset and noise) to estimated pitch rate derived from the observer. By transforming the measurement through the observer algorithm and using the corrected accelerometer signal as input, the system changes the parameter representation to eliminate the harmful effects of offset and noise while preserving the essential pitch motion information
Data Source
AI summary
A system for use at a vehicle to estimate vehicle pitch angle and road grade angle, in real time and generally simultaneously. The system includes a sensor configured to measure vehicle pitch rate, a processor, and a computer-readable medium. The medium includes computer-executable instructions that, when executed by the processor, cause the processor to perform operations comprising estimating, using an observer and the vehicle pitch rate measured by the sensor, an estimated vehicle pitch rate. The operations further comprise estimating, using an observer and the measured vehicle pitch rate, the vehicle pitch angle, and estimating, based on the estimated vehicle pitch rate and the vehicle pitch angle estimated, the road grade angle.