Outdoor Robot Boundary Control Using Adjustable UWB Antennas
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Solution Overview
Problem
Existing methods for setting boundaries for outdoor moving robots, such as lawn mower robots, are inefficient and costly, with GPS-based positioning having high errors, beacon-based systems requiring multiple devices, and UWB technology facing accuracy issues due to multipath interference and antenna installation limitations.
Innovation Solution
A moving robot equipped with a communication unit featuring adjustable antennas that determine relative location using UWB signals, allowing accurate boundary setting without physical wires and minimizing errors through adjustable antenna distances and combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If GPS-based positioning is used for boundary determination, then the positioning range is extended, but the positioning accuracy deteriorates with average errors of 2 to 5 meters
Solution Approach 1:
The patent introduces UWB tags as intermediary devices that are placed at specific boundary locations. These tags act as mediators between the GPS system and the robot, providing precise local reference points that correct GPS errors. The robot determines its position relative to these fixed UWB tags, achieving centimeter-level accuracy despite GPS's meter-level errors.
Solution Approach 2:
The patent replaces the purely GPS-based positioning system with a hybrid system that uses UWB radio frequency signals for precise distance measurement. This substitution of measurement mechanism allows the system to achieve high positioning accuracy by calculating distances based on signal travel time between the robot and fixed UWB tags, rather than relying solely on GPS satellite signals.
2Measurement precision
If DGPS, cameras, LiDARs, or Radars are used to reduce GPS error, then the positioning accuracy is improved, but blind zones are caused and cost increases
Solution Approach 1:
The patent implements a self-service positioning system where fixed UWB tags at boundary locations automatically provide positioning references without requiring active scanning or complex processing by the robot. The robot simply receives signals from these passive tags and calculates its position, eliminating the need for expensive active sensors like LiDAR or Radar on the robot itself.
Solution Approach 2:
Instead of equipping the moving robot with complex active sensors to detect boundaries, the patent inverts the approach by placing passive UWB tags at the boundaries and having the robot detect them. This reversal simplifies the robot's hardware while maintaining high positioning accuracy, as the boundary markers become the active signal sources.
3Measurement precision
If UWB technology is used for positioning, then the positioning precision is improved to about 30 cm or shorter, but multipath interference causes signal disturbances
Solution Approach 1:
The patent uses multiple fixed UWB tags at different boundary locations as reference copies of the positioning system. By having multiple distributed tags rather than a single source, the system can triangulate the robot's position from multiple angles, which helps eliminate multipath interference effects and provides redundant measurement paths for more reliable positioning.
4Measurement precision
If wires are laid under the ground for boundary setting, then the boundary definition is precise, but the setup time and effort increase significantly when changing boundaries
Solution Approach 1:
The patent replaces the mechanical wire-based boundary system with a wireless UWB signal-based system. Instead of physically laying and removing wires to define boundaries, the system uses wireless UWB tags that can be easily deployed and repositioned. This substitution maintains precise boundary definition through signal-based virtual walls while dramatically reducing setup and reconfiguration time and effort.
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
Enables precise boundary determination for outdoor robots, overcoming signal disturbances and antenna limitations, thus enhancing accuracy and reducing setup costs.
Implementation Method 1
a method of restricting the travel of a moving robot by using a low-cost Ultra-Wideband (UWB) communication technology known to have precision of about 30 cm or shorter has been studied
Data Source
Figure 1~2a
Figure 2b~2c
Figure 3~4a
AI summary
A moving robot and a controlling method thereof are disclosed. A moving robot according to the present disclosure includes a traveling unit to move a main body, a communication unit to communicate with a location information transmitter for transmitting signals within an area, and a control unit to set a virtual boundary with respect to a location calculated based the signals, and to control the traveling unit to move the main body without departing from the boundary. The communication unit includes first and antennas provided at respective transceivers that transceive signals with the location information transmitter, and the first and second antennas have an adjustable distance. When signals are received through the first and second antennas, the control unit determines a relative location of the location information transmitter based on a current location of the main body using a frequency corresponding to the distance between the first and second antennas.