Robot Vacuum Cleaner Wheel Assembly for Integrated Cliff Detection

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Solution Overview

Problem

Conventional robot cleaners face challenges in effectively mopping and navigating due to limited friction force, difficulty in adjusting traveling direction, and inefficiencies in cleaning corners and areas adjacent to walls, primarily due to reliance on friction and variable water levels.

Innovation Solution

A cleaner design featuring a wheel assembly that integrates a dust housing and agitator, with a cliff sensor detecting vertical wheel movement, allowing for reduced friction, increased cleaning area, and precise navigation by using eccentrical spin mop rotation axes and a storage space for collected debris, enabling pattern driving and meticulous cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate cliff sensor is installed on the body, then cliff detection capability is improved, but device complexity and size increase

Engineering Contradiction:
Improvecliff detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The wheel assembly is designed to serve multiple functions: it supports the body weight, enables movement, and simultaneously detects cliffs through vertical movement detection. The cliff sensor detects the vertical movement of the wheel assembly itself, making the wheel assembly a multi-functional component that eliminates the need for a separate dedicated cliff sensor system.

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

Solution Approach 2:

The cliff detection function is merged with the wheel assembly structure. The wheel assembly becomes an integrated system that combines mechanical support, locomotion, and sensing functions, thereby reducing overall device complexity while maintaining reliable cliff detection capability.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of operation

If the body has a circular shape, then rotation in place is improved, but agitator width is limited

Engineering Contradiction:
Improverotation in place capabilityVSAvoidagitator width
Core Design Contradiction:
Ease of operationVSArea of moving object

Solution Approach 1:

The storage space for collected foreign material is positioned in front of the agitator, utilizing the longitudinal dimension of the body rather than lateral space. This dimensional arrangement allows the agitator to extend further laterally within the circular body footprint, maximizing cleaning width without compromising rotational capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The wheel assembly is designed to be movable vertically, allowing dynamic adjustment of the body's contact point with the ground. This dynamic positioning enables the circular body to rotate smoothly in place while maintaining stability, and the storage space placement in front of the agitator optimizes the distribution of mass to facilitate rotational movement.

Inventive Principle:
Principle #15Dynamics

3Area of moving object

If spin mop rotation axes are eccentrical, then cleaning area is maximized, but friction with obstacles increases

Engineering Contradiction:
Improvecleaning areaVSAvoidfriction with obstacles
Core Design Contradiction:
Area of moving objectVSObject-affected harmful factors

Solution Approach 1:

The spin mop system uses multiple mops with eccentrical rotation axes arranged in specific positions. Each spin mop operates independently with its own rotation axis, allowing the system to maximize cleaning coverage through strategic placement while the modular segmented structure helps manage friction forces from individual mops separately.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spin mops are configured with eccentrical rotation axes rather than symmetric central mounting. This asymmetric arrangement allows the mop heads to extend further in certain directions, maximizing the cleaning area coverage. The asymmetric positioning also distributes contact points with obstacles unevenly, which can reduce overall friction compared to symmetric configurations where all mops contact obstacles simultaneously.

Inventive Principle:
Principle #4Asymmetry

4Reliability

If friction force is increased for effective mopping, then mopping capability is improved, but traveling and direction adjustment become difficult

Engineering Contradiction:
Improvemopping capabilityVSAvoidtraveling and direction adjustment
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system applies different friction characteristics to different components: the spin mops are designed with high friction contact with the floor to ensure effective mopping action, while the wheel assembly maintains optimized friction properties for smooth traveling and direction adjustment. This local differentiation of friction properties allows simultaneous achievement of effective mopping and easy navigation.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The wheel assembly incorporates vertical movability, allowing dynamic adjustment of the body's weight distribution and contact pressure. This dynamic capability enables the system to modulate friction forces during movement, facilitating easier direction changes and traveling while maintaining sufficient friction for effective mopping when needed.

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

The solution enhances cleaning efficiency by maximizing the cleaning area, reducing friction with obstacles, and allowing for accurate navigation and cliff detection, enabling effective mopping and pattern driving regardless of water levels.

Implementation Method 1

a wheel elastic member that moves the wheel body downward in a vertical direction by elastic force

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 2

a cliff sensor for detecting a movement of the wheel body

Methodology Applied
Scientific EffectPhysical vertical movement detection: Displacement

Data Source

PatentEP4005456B1Vacuum cleaner
Publication Date: 2025.01.15 LG ELECTRONICS INC
  • EP4005456B1 patent drawingFigure 1~2
  • EP4005456B1 patent drawingFigure 3~4
  • EP4005456B1 patent drawingFigure 5~6

AI summary

Disclosed is a cleaner includes a body forming an appearance or an exterior, a mop module, and a sweep module. The mop module is disposed at a lower side of the body, supports the body, and includes a pair of spin mops for rotating and mopping a floor. The sweep module is disposed at the body and sweeps up a foreign material on the floor by a rotation of an agitator. The sweep module includes a dust housing, the agitator, and a wheel assembly. The dust housing includes a collection opening surface opened to the floor and a storage space where the foreign material collected through the collection opening is stored. The agitator is exposed at the collection opening surface, is rotatably assembled to the dust housing, and moves the foreign material on the floor to the storage space when rotating. The wheel assembly is assembled to the dust housing and is in contact with the floor to support the dust housing. The wheel assembly includes a wheel body assembled to the dusting housing to be movable in a vertical direction, a wheel assembled to a lower side of the wheel body and in contact with the floor to support the wheel body, a wheel elastic member disposed between the dust housing and the wheel body and providing elastic force to the wheel body to move the wheel body, and a cliff sensor disposed at the body and detecting a movement of the wheel body when the wheel body is moved. According to the present disclosure, the wheel assembly not only supports the body but also is used as a detection factor of the cliff sensor that detects a cliff, and thus, a number of elements or components can be reduced by function integration.