Moving Robot UWB Boundary Control on Uneven Terrain
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Solution Overview
Problem
Existing methods for controlling moving robots, such as lawn mower robots, face challenges in accurately defining operational boundaries outdoors due to uneven terrain and the need for extensive wire laying or costly ancillary devices, with GPS-based positioning offering insufficient precision and beacon-based systems having security and installation issues.
Innovation Solution
A moving robot system that corrects height errors in Ultra-Wideband (UWB) anchor installations without measuring ground heights, using a reference anchor and sensors to adjust position calculations, allowing for quick and remote correction of position errors and enabling accurate boundary setting without physical boundary markers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If GPS-based positioning is used for boundary definition, then the system is simple and low-cost, but the positioning precision is insufficient (2-5m error)
Solution Approach 1:
The patent replaces GPS satellite-based positioning with a local UWB (Ultra-Wideband) communication system for precise positioning. The UWB system uses time-of-flight measurement between anchors and the robot to achieve centimeter-level positioning accuracy, substituting the mechanical/satellite-based GPS system with a localized electromagnetic communication system that operates independently of satellite signals.
Solution Approach 2:
The patent introduces height dimension correction to the traditional 2D positioning problem. By measuring and correcting for height differences between UWB anchors and the robot, the system transforms the positioning from a flat 2D plane to a 3D spatial coordinate system, thereby improving positioning accuracy on uneven outdoor terrains where height variations can cause significant horizontal position errors.
2Measurement precision
If wires are laid under the ground to specify boundaries, then the boundary definition is accurate, but the installation time and effort are excessive
Solution Approach 1:
The patent replaces the mechanical wire-laying method with a wireless UWB-based virtual boundary system. Instead of physically installing wires under the ground to define boundaries, the system uses UWB signal transmission between anchors and the robot to create a virtual boundary that the robot can detect and follow, eliminating the need for extensive physical installation while maintaining accurate boundary definition.
Solution Approach 2:
The patent creates a virtual copy of the physical boundary that exists in the digital/UWB signal domain rather than requiring the actual physical wire boundary. The UWB system transmits boundary information as electromagnetic signals that the robot can detect, effectively copying the boundary definition from the physical wire-based system to a wireless signal-based system, thereby eliminating installation time while preserving boundary accuracy.
3Device complexity
If beacon technology is used to create virtual walls, then wire laying is eliminated, but the virtual wall can only be linear and requires multiple ancillary devices
Solution Approach 1:
The patent makes the UWB anchor devices multi-functional, serving both as positioning references and as boundary definition points simultaneously. Unlike beacon systems that require separate virtual wall creation mechanisms, the UWB anchors can define boundaries in any shape (linear, curved, irregular) by simply placing them at appropriate locations, eliminating the need for additional ancillary devices while maintaining installation simplicity.
Solution Approach 2:
The patent enables dynamic and flexible boundary definition using UWB signals that can adapt to any terrain shape. The virtual boundary is not fixed to linear paths but can dynamically conform to irregular outdoor areas by utilizing the spatial distribution of UWB anchors and the robot's ability to calculate position in 3D space, allowing the system to adapt to various boundary geometries without requiring physical reconfiguration of linear beacons.
4Ease of operation
If UWB anchors are installed at different heights on uneven terrain, then the system is easy to install, but position calculation errors occur
Solution Approach 1:
The patent implements a feedback mechanism where the system measures the height difference between UWB anchors and the robot, calculates the resulting position error, and then corrects the position calculation by compensating for this height difference. The control unit receives height information, computes the correction amount, and adjusts the final position coordinates accordingly, creating a closed-loop system that automatically compensates for installation height variations.
Solution Approach 2:
The patent changes the parameter space from 2D horizontal coordinates to 3D spatial coordinates by incorporating height (z-axis) information into the positioning calculation. By measuring and utilizing the height difference parameter between anchors and the robot, the system transforms the positioning problem from a flat 2D plane to a 3D space, thereby accounting for terrain unevenness and improving position calculation accuracy without complicating the installation process.
Data Source
AI summary
A moving robot has a body and at least one wheel for moving the main body. The moving robot has a transceiver to communicate with a plurality of location information transmitters located within an area. The moving robot also has a memory storing coordinate information regarding positions of the location information transmitters. Further, the moving robot has a controller that sets a virtual boundary based on location information determined using signals transmitted by the location information transmitters. The controller controls the wheel so that the main body is prevented from traveling outside the virtual boundary. The controller sets a reference location information transmitter and corrects the stored coordinate information by correcting height errors based on height differences between the reference location information transmitter and the other location information transmitters. The controller also corrects a current position of the main body based on the corrected stored coordinate information.