Robot Vacuum Floor Detection Using Structured Laser Light

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Solution Overview

Problem

Existing robotic vacuum cleaners lack effective methods to detect the type of surface they are operating on, which affects dust pickup capacity and navigation, as current methods like accelerometers and brush roll current measurement are unreliable.

Innovation Solution

A robotic cleaning device equipped with a structured vertical light source, such as vertical line lasers, and a camera to illuminate and capture images of the surroundings, allowing the controller to determine the surface structure by analyzing the luminous sections in the images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If accelerometer or gyro is used to detect surface bumps, then vibration detection capability is provided, but it is hard to detect a difference in vibrations caused by the brush roll itself and vibrations caused by a bumpy floor

Engineering Contradiction:
Improvesurface structure detection accuracyVSAvoidvibration source differentiation reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a camera as an intermediary device to capture images of the floor surface, which then allows the controller to analyze surface structure indirectly through image processing. This intermediary approach avoids the direct vibration measurement problem by using optical information instead of mechanical vibration signals.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical vibration detection system (accelerometer/gyro) with an optical detection system (camera). By substituting the mechanical measurement approach with an optical imaging approach, the system can distinguish surface structure without being confounded by vibrations from the brush roll.

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

2Measurement precision

If brush roll current is measured to detect carpet thickness, then carpet detection capability is provided, but there are typically random variations in the current on all surfaces so the measured current needs to be low-pass filtered, making the detection slow

Engineering Contradiction:
Improvecarpet thickness detection capabilityVSAvoiddetection response time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the electrical measurement system (brush roll current measurement with low-pass filtering) with an optical imaging system. The camera captures surface information directly without requiring temporal filtering, enabling real-time surface type detection without the time delay introduced by filtering operations.

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

3Measurement precision

If downwardly oriented camera system and lighting element are used to capture and evaluate pictures of floor surface, then surface type determination capability is provided, but the patent does not specify how to handle varying light conditions or reflective surfaces

Engineering Contradiction:
Improvesurface type determination accuracyVSAvoidhandling of varying light conditions and reflective surfaces
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent uses a structured vertical light source as an intermediary to illuminate the floor surface in a controlled manner. This structured lighting creates consistent illumination patterns that help the camera capture reliable surface information regardless of ambient light conditions, and the vertical orientation minimizes reflections from glossy surfaces.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables improved dust pickup capacity and navigation by accurately identifying surface types, such as hard floors or carpets, and adjusting fan and brush speeds accordingly, reducing slipping and enhancing cleaning efficiency.

Implementation Method 1

The invention relates to a robotic cleaning device and a method at the robotic cleaning device of detecting a structure of a surface over which the robotic cleaning device moves

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

In a captured image, an emitted laser beam will appear as a luminous section which is detected by the controller

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3230814B1Using laser sensor for floor type detection
Publication Date: 2021.02.17 AB ELECTROLUX
  • EP3230814B1 patent drawingFigure 1
  • EP3230814B1 patent drawingFigure 2
  • EP3230814B1 patent drawingFigure 3a

AI summary

The invention relates to a robotic cleaning device (10) and a method at the robotic cleaning device of detecting a structure of a surface (31) over which the robotic cleaning device moves. The method for a robotic cleaning device (10) of detecting a structure of a surface (31) over which the robotic cleaning device moves comprises illuminating (S101) the surface with structured vertical light (30), capturing (S102) an image (37) of the surface, detecting (S103) at least one luminous section in the captured image, and determining (S104), from an appearance of the at least one luminous section, the structure of the surface.