Downward-Looking Sensor Layout for Robot Vacuum Cliff Detection

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Solution Overview

Problem

Conventional self-moving intelligent devices, such as vacuum cleaners, face issues with falling and energy waste due to inadequate detection of suspending states, leading to potential damage and pollution, especially in tight spaces like under furniture, where traditional fall protection mechanisms like floating drive wheels are impractical.

Innovation Solution

The installation of multiple downward-looking sensors at the bottom of the device, including some at the outer edge and inner sides of drive wheels, sends signals to a control module to determine the device's position state, enabling timely action to prevent falls and energy loss, with an optional alarm module for operator notification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a floating drive wheel with travel switch is installed for fall detection, then fall protection capability is improved, but device height increases making it unsuitable for cleaning under furniture

Engineering Contradiction:
Improvefall protection capabilityVSAvoiddevice height
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The invention extracts the fall detection function from the mechanical floating drive wheel structure and relocates it to optical sensors positioned at the bottom of the main body. This removes the need for the floating drive wheel assembly, thereby reducing device height while maintaining fall detection capability through downward-looking sensors that detect the absence of ground reflection.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical travel switch system with an optical sensing system. Instead of using a mechanical float that rises and triggers a switch, the patent uses downward-looking sensors to detect ground presence optically, substituting mechanical detection with optical field detection to achieve the same safety function without the height penalty.

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

2Productivity

If the device continues operating after being lifted or knocked over, then operational continuity is maintained, but energy is wasted and pollution occurs from brush rotation

Engineering Contradiction:
Improveoperational continuityVSAvoidenergy waste
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The invention implements feedback control by continuously monitoring the operational state through downward-looking sensors. When the sensor detects that the device is in an abnormal state (lifted or knocked over), this feedback signal triggers the control module to immediately stop the driving wheel and brush rotation, preventing energy waste and pollution while maintaining operational awareness.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention takes preliminary action by detecting abnormal states before significant energy waste or pollution occurs. The downward-looking sensors continuously monitor the operational environment, and upon detecting suspension or abnormal positioning, the system proactively stops operation in advance, preventing the harmful effects rather than reacting after they occur.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If downward-looking sensors are installed at the outer edge of the bottom, then fall detection capability is improved, but the device requires more space to turn away from edges

Engineering Contradiction:
Improvefall detection capabilityVSAvoidturning space requirement
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The invention addresses the turning space issue by using multiple downward-looking sensors positioned at different locations (front, rear, and side edges) to create a comprehensive detection zone. This multi-dimensional sensor arrangement allows the device to detect edges from various angles and perform more compact turning maneuvers while maintaining reliable fall detection coverage.

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

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

This solution effectively prevents falls and energy waste by accurately detecting suspending states without human intervention, ensuring reliable operation and reducing pollution, while maintaining a compact device design suitable for various cleaning areas.

Implementation Method 1

two or more downward-looking sensors, which are located at the bottom of a main body, collecting suspending signals

Methodology Applied
Scientific EffectOptical reflection detection: Reflection

Data Source

PatentEP3007023B1Self-moving device and control method therefor
Publication Date: 2018.11.28 ECOVACS ROBOTICS CO LTD
  • EP3007023B1 patent drawingFigure 1~2

AI summary

A self-moving device is disclosed, comprising a main body (1), downward-looking sensors (2) and a control module, wherein the number of the downward-looking sensors (2) is two or more, and all the two or more downward-looking sensors (2) are installed at the bottom of the main body (1); the control module is installed within the main body (1) and is connected to the downward-looking sensors (2), and the control module controls actions of the main body (1) according to the number of suspending signals sent from the downward-looking sensors (2). The self-moving device enables the main body (1) to make correct actions, thereby avoiding falling caused by the turning to another suspending position, and avoiding power waste and possible pollution caused by the idling during suspending.