Robotic Work Tool Slope Control by Reversing Downhill

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Solution Overview

Problem

Robotic work tools experience impaired steering control when operating on slopes due to gravitational forces affecting traction, leading to potential sliding or loss of accuracy.

Innovation Solution

A robotic work tool system with at least two rear wheels and one front wheel, equipped with a controller and level detection device, which detects downwards slopes and reverses direction to maintain traction and control by utilizing gravitational force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the robotic work tool moves forward down a slope, then it can cover ground efficiently, but steering control is impaired and traction is reduced due to gravitational forces shifting load to front wheels

Engineering Contradiction:
Improveground coverage efficiencyVSAvoidsteering control accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The robotic work tool reverses its direction of travel when detecting a downward slope. Instead of moving forward down the slope where gravitational forces cause loss of control, the robot moves backward down the slope, which shifts the gravitational load to the driven rear wheels, thereby improving traction and steering control while maintaining ground coverage efficiency

Inventive Principle:
Principle #13The other way round (Inversion)

2Speed

If the robotic work tool moves forward down a slope, then it can maintain forward momentum, but traction is reduced and sliding occurs due to extra load on front wheels

Engineering Contradiction:
Improveforward momentumVSAvoidtraction stability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The robotic work tool reverses direction when detecting a downward slope, moving backward instead of forward. This inversion of direction transfers the gravitational force to the driven rear wheels, maximizing traction and preventing sliding while maintaining the ability to cover ground efficiently

Inventive Principle:
Principle #13The other way round (Inversion)

3Device complexity

If the robotic work tool uses traditional steering control on a slope, then the control system remains simple, but accurate turning becomes difficult due to gravitational forces

Engineering Contradiction:
Improvecontrol system simplicityVSAvoidturning accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The robotic work tool performs preliminary detection of slope conditions using a level sensor before executing turning maneuvers. When a downward slope is detected, the system proactively reverses direction before attempting to turn, thereby preventing loss of control and ensuring accurate positioning without requiring complex slope-compensation control algorithms

Inventive Principle:
Principle #10Preliminary action

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

Enhances steering accuracy and traction by reversing down slopes, preventing sliding and ensuring precise turns, even on inclines.

Implementation Method 1

detect a downwards slope

Methodology Applied
Scientific EffectGravitation: Gravitation

Implementation Method 2

full advantage may be taken of the gravitational force to provide better traction and steering control

Methodology Applied
Scientific EffectGravitation: Gravitation

Data Source

PatentEP3237986B1Control of downhill movement for an autonomous guided vehicle
Publication Date: 2022.01.26 HUSQVARNA AB
  • EP3237986B1 patent drawingFigure 1~2
  • EP3237986B1 patent drawingFigure 3~5
  • EP3237986B1 patent drawingFigure 6~7

AI summary

A robotic work tool system (200) comprising a robotic work tool (100) comprising a collision detection sensor (190), said collision detection sensor (190) comprising a first sensor element (191) and a plurality of second sensor elements (192), wherein said first sensor element (191) is movably arranged with respect to said plurality of second sensor elements (192), wherein said robotic work tool (100) is configured to detect that said first sensor element (191) is proximate a peripheral second sensor element (192) and in response thereto determine that a collision has been detected, and detect that said first sensor element (191) is not proximate any peripheral second sensor element (192) and in response thereto determine that a lift has been detected.