Pivotable Beam Axle for Robotic Lawn Mower Traction

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Solution Overview

Problem

Robotic lawn mowers face challenges in maintaining traction on rugged terrain with obstacles due to torsional rigidity, leading to potential loss of traction and navigation issues, and existing solutions are either expensive or difficult to manufacture and assemble.

Innovation Solution

A robotic lawn mower system with two front wheels arranged on a pivotable beam axle attached to the chassis, allowing the wheels to balance each other and stabilize the chassis, using a minimal number of parts for robust and easy assembly and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If independent suspension is used to allow one wheel to move independently, then traction is improved, but manufacturing cost and assembly difficulty increase significantly

Engineering Contradiction:
Improvetraction maintenanceVSAvoidsuspension system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the two independent wheel suspensions into a single beam axle unit that allows both wheels to move independently while sharing a common pivot point. This combining approach maintains the traction benefits of independent wheel movement while significantly reducing the number of separate suspension components needed, thereby lowering manufacturing cost and assembly complexity

Inventive Principle:
Principle #5Merging (Combining)

2Difficulty of detecting and measuring

If complex suspension mechanisms are added to detect collisions and lift events, then detection capability is improved, but manufacturing and assembly difficulty increase

Engineering Contradiction:
Improvelift event detectionVSAvoidassembly ease
Core Design Contradiction:
Difficulty of detecting and measuringVSEase of manufacture

Solution Approach 1:

The beam axle's pivot point automatically serves as both the mechanical connection point and the sensor location. The pivot point's natural movement and position changes directly indicate lift events and collisions, eliminating the need for separate detection mechanisms. This self-service approach provides detection capability while keeping the system simple to manufacture and assemble

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If multiple separate suspension components are used, then wheel independence is achieved, but robustness and ease of maintenance decrease

Engineering Contradiction:
Improvewheel independenceVSAvoidmaintenance ease
Core Design Contradiction:
Adaptability or versatilityVSEase of repair

Solution Approach 1:

The patent combines multiple suspension functions into a single integrated beam axle assembly with a common pivot point. This merging reduces the total number of separate components that can fail or require maintenance, while the beam axle's design still allows each wheel to move independently to adapt to terrain variations, thereby improving robustness and ease of repair

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3157803B1Improved robotic working tool
Publication Date: 2020.05.06 HUSQVARNA AB
  • EP3157803B1 patent drawingFigure 1~2
  • EP3157803B1 patent drawingFigure 3~4
  • EP3157803B1 patent drawingFigure 5

AI summary

A robotic work tool system (200) comprising a robotic work tool (100), said robotic work tool (100) comprising two front wheels (130) and a chassis (140), wherein said robotic work tool is characterized in that the two front wheels (130) are arranged on a beam axle (145) being pivotably arranged to the chassis (140).