Robotic Boundary-Wire Offset Control for Uniform Edge Mowing

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Solution Overview

Problem

Existing robotic work tools often fail to uniformly treat areas near boundary wires due to fixed offset settings, leading to incomplete lawn mowing or other tasks, and increased risk of getting stuck, especially in varying ground conditions and weather.

Innovation Solution

A method and system allowing the robotic work tool to dynamically switch between multiple offset settings based on detected events such as position, time, weather, and terrain conditions, using sensors and GPS/GNSS for precise positioning, enabling adaptive operation within demarcated work areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a fixed offset setting is used for boundary wire crossings, then the robotic work tool can operate with simple control logic, but it fails to uniformly treat areas near boundary wires and increases the risk of getting stuck in varying ground conditions

Engineering Contradiction:
Improvecontrol logic simplicityVSAvoidoperational reliability near boundaries
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies dynamics by transitioning from a fixed offset setting to a dynamic offset system that automatically adjusts the crossing offset based on detected ground conditions, weather conditions, and position information. The controller modifies the offset value in real-time to match actual environmental conditions, resolving the contradiction between simple control logic and operational reliability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of offset value from constant to variable. The system detects ground conditions (e.g., slipperiness, terrain type) and weather conditions (e.g., rain, temperature), then adjusts the offset parameter accordingly. This allows the robotic work tool to adapt to varying conditions while maintaining reliable operation near boundaries.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If a fixed offset setting is used, then the device structure remains simple, but it cannot adapt to different ground conditions and weather conditions across the work area

Engineering Contradiction:
Improvedevice structureVSAvoidadaptation to varying conditions
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements multi-functionality by equipping the robotic work tool with multiple sensors (e.g., ground condition sensors, weather sensors, GPS/GNSS receivers) that enable the single device to detect and adapt to various ground conditions and weather conditions across different locations in the work area, rather than requiring separate devices for different conditions.

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

Solution Approach 2:

The system uses feedback from sensors that continuously monitor ground conditions, weather conditions, and position information. The controller receives this feedback and automatically adjusts the offset setting based on the detected conditions, enabling the device to adapt to varying environments without increasing structural complexity.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If the robotic work tool crosses the boundary wire with offset to treat edge areas, then it can achieve uniform treatment of the entire work area, but it increases the risk of getting stuck in difficult terrain near boundaries

Engineering Contradiction:
Improveedge treatment precisionVSAvoidrisk of getting stuck
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent dynamically changes the offset parameter based on detected ground conditions near the boundary wire. When difficult terrain is detected (e.g., slippery ground, steep slopes), the system reduces the offset value to prevent getting stuck. When conditions are favorable, it increases the offset to achieve uniform edge treatment, thus resolving the contradiction between precision and reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system transitions from a static offset setting to a dynamic one that adjusts in real-time based on detected conditions. The controller continuously monitors ground conditions and modifies the crossing offset accordingly, allowing the robotic work tool to maintain both precise edge treatment and reliable operation by adapting to terrain difficulties as they are encountered.

Inventive Principle:
Principle #15Dynamics

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 uniform treatment of entire work areas, including edges, by adjusting offsets for different conditions, reducing the risk of getting stuck and improving operational efficiency across varying environments.

Implementation Method 1

The outer limits of a working area of the robotic tool are usually defined, such as by walls or by an electric cable, which emits a magnetic field

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP4068943B1Robotic work tool, system, and method for operation thereof
Publication Date: 2024.04.17 HUSQVARNA AB
  • EP4068943B1 patent drawingFigure 1
  • EP4068943B1 patent drawingFigure 2
  • EP4068943B1 patent drawingFigure 3

AI summary

A method for operating a robotic work tool (1) comprising a sensor for detecting a boundary wire (3) demarcating a work area (2). The method comprises the steps of detecting (9) at least a partial crossing of the boundary wire (3), allowing (12) a crossing of the boundary wire (3) by an offset, switching (8) between a first offset setting and at least a second offset setting of the work tool (1) based on one or more events (7). A robotic work tool (1) comprises a controller for controlling the operation of the robotic working tool (1). The controller is configured to: control the work tool (1) to operate within the work area (2), determine whether the work tool (1) crosses the boundary wire (3), allow a crossing of the wire (3) by the offset, and switch (8) between at least two offset settings stored in the work tool (1).