Inertial Sensor Roll Bank Estimation
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Solution Overview
Problem
Existing methods for accurately measuring road bank and vehicle roll angles in autonomous driving systems are costly and prone to inaccuracies due to device offsets and noise, making it challenging to differentiate between vehicle roll and road bank 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 roll and road bank angles simultaneously, improving accuracy and reducing costs by leveraging roll-rate sensors and processing data with Luenberger-type observers and single degree-of-freedom dynamics models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated optical sensors or multi-antenna GPS arrangements are used to directly measure road bank and vehicle roll angles, then measurement accuracy is improved, but system cost increases significantly
Solution Approach 1:
The patent uses a simplified inertial measurement approach that copies the essential functionality of expensive dedicated optical sensors or multi-antenna GPS systems. Instead of directly measuring bank and roll angles with complex hardware, the system uses a standard three-axis inertial measuring device to capture motion data and computationally derives the angle information, providing accurate measurements at a fraction of the cost.
Solution Approach 2:
The patent replaces mechanical/optical measurement systems with an inertial sensing and computational approach. Rather than using dedicated optical sensors or satellite-based GPS arrangements, the system substitutes these with a three-axis inertial measuring device combined with observer algorithms that mathematically estimate bank and roll angles from acceleration and rate data.
2Device complexity
If standard inertial measuring devices are used to detect roll-direction movement, then device cost is reduced, but measurement accuracy deteriorates due to inability to differentiate vehicle roll from road bank
Solution Approach 1:
The patent implements feedback through observer algorithms that continuously process inertial measurement data and refine estimates of vehicle roll and road bank angles. The observer uses the measured roll rate from the three-axis device as feedback to compute and update angle estimates, allowing the system to differentiate between vehicle roll and road bank effects even with standard, lower-cost sensors.
Solution Approach 2:
The patent introduces computational observers as an intermediary between the raw inertial measurements and the final angle estimates. These observers act as a mediator that processes the ambiguous roll-direction data from the three-axis device, separating the contributions of vehicle roll and road bank through mathematical estimation, thereby enabling accurate differentiation with standard sensors.
3Measurement precision
If measurement devices with high accuracy are used, then angle measurement precision is improved, but susceptibility to device offset and noise increases
Solution Approach 1:
The observer-based estimation system uses feedback to continuously monitor and correct for device offsets and noise. By comparing estimated angles with expected vehicle dynamics behavior, the system can identify and compensate for sensor errors, maintaining accuracy even when using standard inertial devices that are more susceptible to such harmful factors.
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 provides accurate real-time estimation of road bank and vehicle roll angles, enhancing autonomous driving functions, especially on banked or pitched roads, by improving data interpretation and vehicle control, while being more cost-effective than traditional direct measurement methods.
Implementation Method 1
a sensor configured to measure vehicle roll rate
Implementation Method 2
estimating, using an observer and a measured vehicle roll rate, a vehicle roll rate. The operations also include estimating, using an observer and a measured vehicle roll rate, vehicle roll angle. And the operations include estimating, based on the vehicle roll rate estimated and the vehicle roll angle estimated, a road bank angle
Data Source
AI summary
A system, for use at a vehicle to estimate vehicle roll angle and road bank angle, in real time and generally simultaneously. The system includes a sensor configured to measure vehicle roll rate, a processor; and a computer-readable medium. The medium includes instructions that, when executed by the processor, cause the processor to perform operations comprising estimating, using an observer and the vehicle roll rate measured by the sensor, a vehicle roll rate. The operations also include estimating, using an observer and a measured vehicle roll rate, the vehicle roll angle, and estimating, based on the vehicle roll rate estimated and the vehicle roll angle estimated, the road bank angle.