Robotic Floor Cleaner Reverse Movement for Liquid Accumulation Control

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Solution Overview

Problem

Existing robotic vacuum cleaners face issues with liquid distribution and contamination during wet cleaning, leading to unsightly traces, component damage, and reduced cleaning effectiveness due to improper placement of wet and dry cleaning modules.

Innovation Solution

A method for controlling a mobile, self-driving device that involves driving forward with a dry cleaning module, detecting liquid accumulations, reversing before contact, and using the wet cleaning module to wipe up liquids, ensuring the dry module remains clean and preventing liquid spread.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the wet cleaning module is placed at the rear of the device, then the dry cleaning module can effectively vacuum and sweep the floor, but the sealing lip will push liquids ahead or spread them across the floor, causing unsightly traces and potential contamination

Engineering Contradiction:
Improvecleaning effectivenessVSAvoidliquid spread
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional cleaning sequence by detecting liquid accumulations ahead of time and reversing the cleaning approach: instead of moving forward through liquid (which spreads it), the robot detects the liquid, turns around, and moves backward through the liquid accumulation. This inversion allows the wet cleaning module to absorb liquid without the sealing lip pushing it ahead, eliminating the harmful spreading effect while maintaining effective cleaning.

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

Solution Approach 2:

The patent applies preliminary action by using detection devices (optical sensors, capacitive sensors, or contact sensors) to identify liquid accumulations before the dry cleaning module encounters them. This advance detection allows the system to switch to reverse movement mode proactively, preventing the sealing lip from contacting and spreading the liquid in the first place.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If the robot moves forward through liquid accumulation, then the wet cleaning module can mop up the liquid, but the drive units will roll over wet areas and contaminate the floor with tracks due to damp wheels

Engineering Contradiction:
Improveliquid removalVSAvoidfloor contamination
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent inverts the movement direction when liquid is detected: instead of moving forward through the liquid accumulation (which would wet the drive units and create tracks), the robot turns around and moves backward through the liquid. This reversal ensures that the drive units remain on dry floor sections, preventing them from becoming damp and leaving contaminating tracks on the cleaned floor.

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

3Quantity of substance

If the robot partially sucks up liquid with the dry cleaning module, then the liquid enters the dust container, but it mixes with dust and potentially becomes trapped in the filter or damages internal components

Engineering Contradiction:
Improveliquid absorptionVSAvoidcomponent protection
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent applies preliminary action by using detection devices to identify liquid accumulations before the dry cleaning module encounters them. This advance detection allows the system to switch to reverse movement mode proactively, preventing the sealing lip and dry cleaning components from contacting the liquid, thereby avoiding liquid-dust mixing and potential filter damage.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent extracts the liquid removal function from the dry cleaning module by dedicating it solely to dry cleaning operations. The wet cleaning module handles all liquid absorption, and the dry cleaning module is protected from liquid contact through the reverse movement strategy, ensuring that liquid never enters the dust container or filter system.

Inventive Principle:
Principle #2Taking out (Extraction)

4Object-affected harmful factors

If the wet cleaning module is placed at the front of the device, then liquid can be removed before dusting, but the floor is mopped before dusting causing dirt to accumulate quickly on the mop pad, reducing cleaning effectiveness

Engineering Contradiction:
Improveliquid spread preventionVSAvoidcleaning effectiveness
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent inverts the conventional cleaning sequence by performing dry cleaning first (moving forward with the dry cleaning module) and then handling liquid accumulations separately (by turning around and moving backward through detected liquid). This inversion ensures that the mop pad remains relatively clean during the primary cleaning phase, maintaining its effectiveness, while liquid is removed through a separate reverse-movement process.

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

Data Source

PatentEP4461190B1Method and device for mopping up a liquid accumulation
Publication Date: 2026.03.25 BSH HAUSGERATE GMBH
  • EP4461190B1 patent drawingFigure 1A~2A
  • EP4461190B1 patent drawingFigure 2B~2C
  • EP4461190B1 patent drawingFigure 3A~4C

AI summary

A method for controlling a mobile, self-propelled device (10), in particular a floor cleaning device such as a vacuum and/or sweeping and mopping robot, for wiping up a liquid accumulation (7) is described, comprising the following steps: driving over a floor area intended for cleaning in the direction of travel in forward motion of the device (10) and cleaning the floor area with a dry cleaning module (1) and/or a wet cleaning module (2) of the device (10); detecting the liquid accumulation (7) in the direction of travel in front of the device (10) in a wet area; stopping the forward movement before the wet area and turning the device (10) substantially 180°; driving over the wet area in reverse in the direction of travel of the device (10) and wiping up the liquid accumulation (7) with the wet cleaning module (2).