Robotic Lawnmower Boundary Control Using Grass Sensing

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Solution Overview

Problem

The installation of robotic work tools, such as robotic lawnmowers, in operational areas with irregular boundaries is cumbersome due to the difficulty in accurately defining these boundaries, necessitating a simplified method for boundary detection and operation.

Innovation Solution

A robotic work tool system equipped with a grass sensor, controller, and optional satellite navigation and visual navigation sensors, which determines its position relative to a rudimentary boundary and adjusts its operation by changing direction or continuing to operate within specified distances from the boundary, allowing for efficient navigation and mowing within the operational area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a robotic work tool uses traditional boundary definition methods in irregular operational areas, then the boundary can be accurately defined, but the installation becomes cumbersome and complex

Engineering Contradiction:
Improveboundary definition accuracyVSAvoidinstallation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a rudimentary boundary consisting of simple geometric shapes (lines, arcs, polygons) that can be easily defined and modified without permanent installation infrastructure. These virtual boundaries are lightweight, easily adjustable constraints that replace complex physical boundary markers while maintaining operational precision

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The system allows dynamic adjustment of boundary parameters including maximum distance from boundary, minimum distance from boundary, and turning distance. These parameter changes enable the same robotic work tool to adapt to different operational areas with irregular boundaries without requiring physical reconfiguration or complex reinstallation

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If a robotic work tool uses simple boundary definitions, then installation is simplified, but the robot may operate outside the operational area

Engineering Contradiction:
Improveinstallation simplicityVSAvoidboundary adherence reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The system pre-calculates and enforces distance constraints before the robotic work tool reaches problematic areas. By establishing maximum distance from boundary and minimum distance from boundary parameters in advance, the controller proactively prevents the tool from operating outside the operational area or in unsafe zones, ensuring boundary adherence through preventive control rather than reactive correction

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The controller continuously monitors the position of the robotic work tool relative to the rudimentary boundary and adjusts operation accordingly. Real-time feedback on distance from boundary triggers automatic direction changes when maximum or minimum distance thresholds are approached, ensuring reliable boundary adherence through continuous position verification and adaptive control

Inventive Principle:
Principle #23Feedback

3Measurement precision

If a robotic work tool continuously monitors position and grass edges, then operational accuracy is improved, but energy consumption increases

Engineering Contradiction:
Improveposition determination accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The grass sensor serves multiple functions: detecting grass edges for boundary determination, identifying operational areas, and providing feedback for navigation decisions. By making the sensor multi-functional rather than requiring separate systems for each detection task, the patent reduces overall system energy consumption while maintaining high measurement precision for position determination

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4368004A1Improved operation and installation for a robotic work tool
Publication Date: 2024.05.15 HUSQVARNA AB
  • EP4368004A1 patent drawingFigure 1A~1B
  • EP4368004A1 patent drawingFigure 2~3A
  • EP4368004A1 patent drawingFigure 3B~3C

AI summary

A robotic work tool system comprising a robotic work tool arranged to operate in an operational area at least partially covered with grass, wherein the operational area is bounded by a rudimentary boundary, and the robotic work tool comprising a grass sensor and a controller is configured to receive sensor input from the grass sensors, determine a position of the robotic work tool, determine that the robotic work tool is on grass, and then determine that the position is outside a maximum distance of the rudimentary boundary and then change direction of operation or determine that the position is inside the maximum distance of the rudimentary boundary and then keep operating.