Robotic Mower Boundary Navigation With False Obstacle Filtering
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Solution Overview
Problem
Robotic lawnmowers often fail to service areas completely due to false obstacle detections, particularly when obstacles such as branches or rocks hang over the boundary wire, causing the robotic lawnmower to take evasive action prematurely and skip areas that do not pose a collision risk.
Innovation Solution
The robotic work tool system deactivates its proximity sensors when it determines it is close to the boundary wire, relying instead on magnetic field sensors for navigation and obstacle avoidance. This allows the system to disregard false positive obstacle detections and maintain efficient area coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robotic work tool uses proximity sensors to detect obstacles, then collision avoidance capability is improved, but false positive detections cause unnecessary evasive actions and reduce work area coverage
Solution Approach 1:
The boundary wire acts as an intermediary element that provides a reference signal to the robotic work tool. By detecting the magnetic field signal from the boundary wire, the system can determine its proximity to the boundary and use this information to filter false obstacle detections. The boundary wire signal serves as a mediator between the proximity sensor detections and the evasive action decision-making process.
Solution Approach 2:
The system changes the operational parameter of the proximity sensor based on the detected distance to the boundary. When the robotic work tool determines it is within a threshold distance from the boundary (by detecting boundary wire signal strength), it deactivates or adjusts the sensitivity of the proximity sensor, thereby preventing false positive detections in boundary regions while maintaining normal operation in the center of the work area.
2Reliability
If the robotic work tool takes evasive action based on proximity sensor detections, then safety is improved, but unnecessary evasive actions increase time loss and reduce efficiency
Solution Approach 1:
The system uses feedback from the boundary wire detection to dynamically adjust the operation of proximity sensors. The robotic work tool continuously monitors the magnetic field signal from the boundary wire, and this feedback information is used to control the activation state of proximity sensors. When the feedback indicates proximity to the boundary, the proximity sensors are deactivated, preventing unnecessary evasive actions and time loss.
3Measurement precision
If the robotic work tool deactivates proximity sensors near the boundary, then false positive detections are reduced, but the ability to detect real obstacles near the boundary is also reduced
Solution Approach 1:
The system applies local quality by making the proximity sensor activation state dependent on the local position relative to the boundary. Instead of uniformly activating or deactivating proximity sensors across the entire work area, the system selectively deactivates them only in the local region near the boundary where false detections occur, while maintaining their operation in the central region where they are effective for real obstacle detection.
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 solution ensures that robotic lawnmowers can service areas more thoroughly by avoiding unnecessary evasive actions due to false obstacle detections, thereby maintaining the integrity of the work area coverage.
Implementation Method 1
a signal generator arranged to generate a control signal, wherein the work area is enclosed by a boundary wire through which the control signal is being transmitted thereby generating a magnetic field and wherein the robotic work tool further comprises at least one magnetic field sensor for detecting the magnetic field
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5B
AI summary
A robotic work tool system (200) comprising a boundary (230) enclosing a work area (205) and a robotic work tool (100) comprising a proximity sensor (180) arranged to sense an obstacle (S1, S2, O, B), the robotic work tool (100) being arranged to operate within the work area (205) and the robotic work tool (100) being configured to determine (610) a sensed obstacle (S1, S2, O, B); determine (620) a distance (d); determine (630) whether the distance (d) is inside a threshold distance (D), and if so disregard (640) the proximity sensor (180); and, if not, take (650) evasive action to avoid the sensed obstacle (S1, S2, O, B).