Robotic Lawn Mower Arc Path Control for Border Cutting

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Solution Overview

Problem

Robotic lawn mowers struggle to efficiently cut grass close to objects and borders due to their design, which often results in uncut grass near obstacles, requiring manual trimming.

Innovation Solution

A robotic lawn mower equipped with a control unit that controls a rotatable grass cutting disc and drive wheels to perform arcuate movements, allowing the mower to cut grass close to boundaries by moving parallel to the boundary extensions and adjusting its path to maintain efficient cutting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cutting unit is arranged at the underside of the lawn mower body, then the mower can systematically cut grass in straight lines, but the mower body and wheels hinder the cutting unit from reaching grass close to objects and borders

Engineering Contradiction:
Improvesystematic mowing efficiencyVSAvoidability to cut close to objects and borders
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent divides the cutting function into two separate units: a main cutting unit for systematic mowing and a separate edge cutting unit for trimming close to objects and borders. This segmentation allows each unit to be optimized for its specific function, resolving the contradiction between systematic mowing efficiency and adaptability to cut close to obstacles.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism (a movable arm or extension carrying the edge cutting unit) that connects the main mower body to the edge cutting function. This intermediary allows the edge cutter to reach areas that would otherwise be inaccessible to the main cutting unit, while the main body remains positioned for efficient systematic mowing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the mower body and wheels are positioned to maintain stability during systematic mowing, then cutting efficiency is improved, but the cutting unit cannot reach grass close to objects and borders

Engineering Contradiction:
Improvecutting efficiencyVSAvoidaccess to border areas
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The cutting system is segmented into a main cutting unit attached to the stable mower body and a separate edge cutting unit on a movable platform. This allows the main body to maintain stability for efficient cutting while the edge unit independently accesses border areas.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The edge cutting unit is mounted on a dynamic, movable platform that can extend and reposition independently from the main mower body. This dynamic configuration allows the edge cutter to reach border areas while the main body remains stable during systematic mowing operations.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If a separate manual grass trimmer is used to cut grass close to objects, then complete lawn coverage is achieved, but additional manual work is required

Engineering Contradiction:
Improvelawn edge cutting qualityVSAvoidneed for separate manual tool
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the edge cutting function with the automated robotic mower by integrating an edge cutting unit onto the mower platform. This combination eliminates the need for separate manual trimming operations, as the robotic system performs both systematic mowing and edge cutting in one automated pass.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The robotic mower is designed with multi-functionality, serving both as a systematic mowing machine and an edge trimming device. The integrated edge cutting unit enables the single device to perform multiple cutting tasks that previously required separate tools, reducing overall system complexity.

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

Data Source

PatentEP4631336A1A robotic lawn mower with enhanced cutting properties
Publication Date: 2025.10.15 HUSQVARNA AB
  • EP4631336A1 patent drawingFigure 1
  • EP4631336A1 patent drawingFigure 2
  • EP4631336A1 patent drawingFigure 3

AI summary

The present disclosure relates to a robotic lawn mower (100) comprising a control unit (110) and a first end portion (101) is facing a forward travelling direction (F) and having a longitudinal mower extension (C) extending between the end portions (101, 102). When the robotic lawn mower (100), during grass cutting in a cutting lane (208A, 208'A) having a main lane extension (LA, L'A), is approaching a boundary (220) with a main boundary extension (E), the control unit (110) is adapted to control the robotic lawn mower (100) such that the second end portion (102) performs a first arcuate movement in a first arcuate direction (D1) along a first cutting arc (210, 210') having a first angular span (φ1, φ'1) such that the mower extension (C) is positioned mainly parallel to the boundary extension (E). The control unit (110) is further adapted to control the robotic lawn mower (100) to move a cutting lane change distance (DL, D'L) mainly parallel to the boundary extension (E) in the forward travelling direction (F) to an adjacent further cutting lane (208B, 208'B) having a further main lane extension (LB, L'B), and to control the robotic lawn mower (100) such that the second end portion (102) performs a second arcuate movement in a second arcuate direction (D2), opposite the first arcuate direction (Di), along a second cutting arc (310, 310') having a second angular span (φ2, φ'2) such that the longitudinal extension (C) is positioned mainly parallel to the further main lane extension (LB, L'B).