Autonomous Vehicle Localization Using Dual Reference Frames
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Solution Overview
Problem
Conventional autonomous vehicles relying on Inertial Navigation Systems (INS) are not robust to GPS failures, leading to increased errors in vehicle localization, especially in environments with intermittent or absent GPS signals, which can result in unsafe vehicle motion due to unobservable linear speeds and accumulating errors.
Innovation Solution
A method and apparatus for determining a route for an autonomous vehicle using a combination of local and global reference frames, where local environment sensors measure parameters within the vehicle's environment and a high-error, low-drift sensor like GPS provides signals from a fixed Earth frame, allowing for route transformation and control, even with lower frequency GPS updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS signals are used for global localization, then low-drift positioning is achieved, but high-error and intermittent signal reception occurs
Solution Approach 1:
The patent divides the localization system into two independent segments: a global localization system using GPS for low-drift positioning and a local localization system using monocular vision for high-frequency observation. Each segment operates independently with its own reference frame, allowing the system to leverage the strengths of both approaches without being constrained by their individual weaknesses.
Solution Approach 2:
The patent changes the operational parameters of GPS usage by accepting lower update frequencies and higher individual errors, while compensating through the continuous high-frequency local localization data. This parameter change allows the system to use GPS more reliably without being bottlenecked by its intermittent nature.
2Duration of action of stationary object
If INS is used for localization, then continuous positioning is achieved, but error accumulates over time due to unobservable linear speeds
Solution Approach 1:
The patent introduces a local localization intermediary system using monocular vision that acts as a mediator between the global GPS reference frame and the vehicle's motion control. This intermediary provides continuous high-frequency observations that prevent error accumulation in the INS while maintaining compatibility with the global positioning system.
3Measurement precision
If high update rate local sensors are used, then collision detection accuracy is improved, but GPS dependence increases
Solution Approach 1:
The patent segments the localization functionality into global positioning (GPS) and local observation (monocular vision), allowing each to operate at its optimal update rate and accuracy level without being constrained by the other's limitations.
Solution Approach 2:
The patent implements preliminary anti-action by using the local monocular vision system to preemptively detect and compensate for potential GPS failures or signal degradations before they affect overall system performance, ensuring continuous safe operation.
Data Source
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AI summary
A method and apparatus for establishing a route for an autonomous vehicle (2), the method comprising: determining localisation information for the vehicle (2) with respect to a first frame of reference that is fixed with respect to a current 5 state of the vehicle (2); determining localisation information for the vehicle (2) with respect to a second frame of reference that is fixed with respect to an entity (e.g. Earth), the vehicle (2) being moveable with respect to the entity; establishing a route for the vehicle (2) with respect to the second frame using the localisation information for the vehicle (2) with respect to the second frame; transforming the route from the second frame to the first frame; and determining a route for the vehicle (2) with respect to the first frame using the localisation information for the vehicle (2) with respect to the first frame and the transformed route.