Spin Mop Robot Position Correction for Slip-Aware Distance Tracking

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Solution Overview

Problem

Mobile robots without wheels, which rely on frictional force for movement, face challenges in accurately detecting position and correcting for slipping, especially when using image sensors, leading to inefficient cleaning patterns and incomplete coverage around corners and walls.

Innovation Solution

A mobile robot design incorporating a sensing module that detects moving distance and speed without relying on wheel rotation, using a combination of encoders, obstacle sensors, and image sensors to correct for slipping and maintain accurate position tracking, allowing for patterned cleaning regardless of water level changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a lower image sensor is used to detect position, then position detection capability is improved, but power consumption increases and data processing becomes difficult

Engineering Contradiction:
Improveposition detection accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent divides the sensing system into multiple components: upper image sensor for absolute position, lower image sensor for relative position correction, and encoder for rotation detection. Each sensor handles a specific aspect of position detection, allowing the system to achieve high accuracy without overloading a single sensor with excessive processing requirements

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lower image sensor acts as an intermediary that corrects position errors detected by the upper image sensor. Instead of relying solely on the power-intensive lower sensor, the system uses the lower sensor to provide correction data that refines the overall position accuracy while reducing the processing burden on the lower sensor

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the robot moves only by frictional force of the spin mop, then wheel structure is simplified, but position correction becomes difficult without wheel rotation data

Engineering Contradiction:
Improvemechanical structure simplicityVSAvoidposition correction accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional wheel-based mechanical system with a spin mop-based frictional propulsion system. Position correction is achieved not through wheel rotation counting but through image sensor data processing and encoder detection of spin mop rotation, substituting mechanical measurement with optical and electromagnetic sensing

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system implements feedback control by continuously comparing the expected position (calculated from spin mop rotation) with the actual position (detected by image sensors). The encoder provides rotation feedback, and image sensors provide position feedback, allowing the system to correct for slipping and maintain accurate position tracking despite the lack of traditional wheel rotation data

Inventive Principle:
Principle #23Feedback

3Device complexity

If random traveling is used for cleaning, then navigation complexity is reduced, but cleaning thoroughness decreases especially near corners and walls

Engineering Contradiction:
Improvenavigation control simplicityVSAvoidcleaning effectiveness
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The image sensors provide continuous feedback about the robot's position and the cleaning coverage achieved. This feedback enables the system to transition from purely random traveling to a more intelligent navigation pattern that can identify and target areas requiring cleaning, including corners and walls that would be missed by random motion alone

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The navigation system dynamically adjusts its behavior based on real-time sensor data. Rather than sticking to a fixed random traveling pattern, the robot can modify its path in response to detected surfaces, obstacles, and cleaning status, enabling it to adaptively cover difficult-to-reach areas while maintaining the overall simplicity of the navigation approach

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 enables accurate position detection and correction for slipping, ensuring thorough and efficient cleaning patterns even around corners and walls, improving cleaning effectiveness and reliability.

Implementation Method 1

a mobile robot, which is not driven by wheels but moves by a frictional force between a spin mop and a floor

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

a sensing module which is disposed at a lower surface of the body, and obtains at least any one data of a moving distance or a moving speed during a predetermined period of time by detecting a lower part of the body

Methodology Applied
Scientific EffectImage sensing: Photography

Data Source

PatentEP3771394B1Mobile robot and method of calculating moving distance of the same
Publication Date: 2023.09.27 LG ELECTRONICS INC
  • EP3771394B1 patent drawingFigure 1
  • EP3771394B1 patent drawingFigure 2
  • EP3771394B1 patent drawingFigure 3

AI summary

The present disclosure relates to a mobile robot and a method of calculating a moving distance of the mobile robot, the mobile robot including: a spin mop which includes a rotary plate, which is rotatable transversely, and slips while moving; an encoder which obtains any one or more data from the rotary plate, and transmits the obtained data to a controller; a sensing module which obtains at least any one data of a moving distance or a moving speed during a predetermined period of time by detecting external circumstances; and a controller configured to process the data, in which by calculating a moving distance or a rotation angle based on the data obtained by the encoder, and by correcting the moving distance or the rotation angle based on the data obtained by the sensing module, a final moving distance or rotation angle may be calculated accurately.