Active Doppler Sensor Localization in GPS-Denied Vehicle Navigation
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Solution Overview
Problem
Current methods for determining the location and orientation of autonomous vehicles are unreliable, especially in GPS-unavailable areas and lack sufficient accuracy, as they rely on GPS, IMU, or wheel encoders without verification from another source.
Innovation Solution
The system employs active Doppler sensors to obtain Doppler signatures from entities like road signs, trees, and curbs, determining calibration parameters such as mounting location, offset angle, linear ego-velocity, and rotational velocity, and integrates these to determine the vehicle's location, which is then verified against GPS or IMU data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS, IMU, or wheel encoders are used to determine vehicle location and orientation, then the system can obtain location data, but the reliability and accuracy are insufficient and cannot be verified by another source
Solution Approach 1:
The patent uses Doppler sensor measurements to provide feedback verification of location and orientation data obtained from GPS, IMU, or encoders. The system continuously compares Doppler-derived position with other sensor readings, enabling cross-validation and improving overall reliability of the navigation system.
Solution Approach 2:
The Doppler sensor acts as an intermediary measurement tool that independently verifies location data from other sensors. By measuring Doppler shift from stationary objects, it provides an alternative measurement path that mediates between GPS and inertial/encoder systems, enhancing both reliability and precision.
2Reliability
If GPS is used to determine vehicle location, then location data can be obtained, but GPS may be unavailable in certain locations such as tunnels
Solution Approach 1:
The system pre-establishes a database of stationary objects (buildings, trees, signs) with their known locations before GPS becomes unavailable. When entering GPS-denied environments like tunnels, the Doppler sensor immediately begins measuring these pre-identified objects, allowing seamless transition without loss of location capability.
Solution Approach 2:
The Doppler sensor serves as an intermediary system that takes over location determination when GPS is unavailable. It measures Doppler shift from stationary objects visible through the tunnel or in urban canyons, providing continuous location data independent of satellite signals.
3Device complexity
If current location determination techniques are used, then the system can operate without additional sensors, but the accuracy is not sufficiently verified
Solution Approach 1:
The Doppler sensor performs multiple functions: it measures velocity for navigation, identifies stationary objects for location verification, and provides cross-validation for other sensor systems. This multi-functionality allows a single additional sensor to address multiple accuracy verification needs without proportionally increasing system complexity.
Solution Approach 2:
The Doppler sensor acts as an intermediary verification layer that adds measurement precision without requiring a complete sensor suite overhaul. It provides independent verification of location data through Doppler shift measurements, enhancing accuracy while maintaining relatively simple system architecture.
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
This method provides a reliable and accurate means of determining vehicle location and orientation, even in GPS-denied environments, by using Doppler signatures to calibrate sensors and integrate velocity data over time, enhancing navigation precision and safety.
Implementation Method 1
obtaining a Doppler signature from each of one or more entities... determining one or more calibration parameters of the active Doppler sensor based on the Doppler signature
Data Source
AI summary
Provided herein is a system on a vehicle, the system comprising an active Doppler sensor; one or more processors; and a memory storing instructions that, when executed by the one or more processors, causes the system to perform: obtaining a Doppler signature from each of one or more entities; and determining one or more calibration parameters of the active Doppler sensor based on the Doppler signature from at least a portion of the one or more entities.