Robot Orientation Detection Using UWB Anchors and Visual Markers
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Solution Overview
Problem
Traditional UWB localization systems can determine the position of a mobile robot but not its orientation, which is essential for fully autonomous operation in environments.
Innovation Solution
Incorporating visual markers on UWB anchor stations and using a camera on the robot to detect these markers, along with UWB signals, to calculate the robot's orientation by determining the camera orientation angle and distance to the anchors, and iteratively optimizing this orientation using learning gains and reprojection error minimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional UWB localization systems are used, then the position of the mobile robot can be determined, but the orientation of the robot cannot be determined
Solution Approach 1:
The patent combines UWB distance measurement technology with visual marker recognition technology into a unified localization system. The UWB anchor provides distance information while the visual marker on the same anchor provides orientation information, allowing both position and orientation to be determined simultaneously through data fusion of these two measurement modalities
Solution Approach 2:
The visual marker serves as an intermediary element that bridges the gap between the UWB anchor and the robot's camera system. By placing a recognizable visual pattern on the anchor, the system enables the camera to detect the anchor's position and orientation in the image plane, which is then used to calculate the robot's orientation angle relative to the anchor
2Loss of information
If visual markers are added to UWB anchors, then orientation can be determined, but device complexity increases
Solution Approach 1:
The UWB anchor is enhanced to serve multiple functions: it continues to provide distance measurement via UWB signals while simultaneously displaying visual markers for orientation detection. This multi-functionality allows a single device to fulfill both localization and orientation determination roles without requiring separate systems
Solution Approach 2:
The visual marker uses distinct color patterns and visual characteristics that make it easily distinguishable by the robot's camera system. The marker's visual properties (color, pattern, contrast) are specifically designed to be detectable and recognizable, enabling reliable orientation calculation through image processing
3Measurement precision
If camera and UWB detection are combined, then both position and orientation can be determined, but computation complexity increases
Solution Approach 1:
The system employs iterative optimization where the initially calculated orientation angle is refined through feedback from the reprojection error. The reprojection error measures the discrepancy between the observed visual marker position in the image and the expected position based on the calculated orientation, and this feedback is used to adjust and optimize the orientation estimate until convergence
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 enhances the accuracy and speed of mapping and localization by enabling the determination of both position and orientation of the mobile robot, improving its autonomy in complex environments.
Implementation Method 1
capturing, by a camera device on a mobile robot moving in an environment, an image frame
Implementation Method 2
calculate its distances to the at least three anchors by measuring time of flight of signals to each of the at least three anchors
Data Source
AI summary
The method and system disclosed herein presents a method and system for capturing, by a camera device on a mobile robot moving in an environment, an image frame at a first location within a portion of the environment. In accordance with a determination that the image frame contains a first visual marker: the method includes determining a camera orientation angle from the camera device to a first anchor associated with the first visual marker based on the image frame; detecting, by a detector on the mobile robot, a first beacon signal emitted by the first anchor. The method includes determining a distance between the mobile robot and the first anchor; and determining an orientation angle of the mobile robot based on the camera orientation angle, and the distance between the mobile robot and the first anchor.