Robot Cleaner Straight-Travel Control on Carpet Slippage

Solution Overview

Problem

Robot cleaners struggle to maintain straight travel on carpets due to uneven slippage of drive wheels, leading to frequent swerving, as existing designs to reduce slippage either fail to prevent swerving on carpets or result in low contact force and wear on hard floors.

Innovation Solution

A robot cleaner equipped with a caster wheel and a heading angle detection unit, using an encoder to detect deviation angles and adjust drive wheel rotations to maintain straight travel, regardless of floor texture, by controlling the number of rotations based on detected angle information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drive wheels are designed with protrusions like snow tires to reduce slippage on carpets, then slippage is reduced on carpets, but contact force with hard floors decreases and wear increases

Engineering Contradiction:

Improveslippage prevention on carpetsVSAvoidcontact force on hard floors

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The robot dynamically adjusts the rotation speeds of individual drive wheels based on real-time feedback from the caster wheel angle sensor. Instead of using fixed protrusion patterns on wheels, the system dynamically compensates for slippage by varying wheel rotation rates, allowing the same wheel design to perform optimally on both carpets and hard floors

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses a caster wheel with an angle sensor to detect deviations from straight travel and feeds this information back to the control unit. The control unit then adjusts the rotation speeds of the drive wheels accordingly, creating a closed-loop control system that maintains straight travel without requiring different wheel designs for different floor types

Inventive Principle:

Principle #23Feedback

2Duration of action of stationary object

If drive wheels are designed to have high contact force on hard floors, then wear is reduced on hard floors, but slippage increases on carpets causing swerving

Engineering Contradiction:

Improvewheel life on hard floorsVSAvoidstraight travel on carpets

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The robot dynamically adjusts the rotation speeds of individual drive wheels based on real-time feedback from the caster wheel angle sensor. Instead of using fixed protrusion patterns on wheels, the system dynamically compensates for slippage by varying wheel rotation rates, allowing the same wheel design to perform optimally on both carpets and hard floors

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses a caster wheel with an angle sensor to detect deviations from straight travel and feeds this information back to the control unit. The control unit then adjusts the rotation speeds of the drive wheels accordingly, creating a closed-loop control system that maintains straight travel without requiring different wheel designs for different floor types

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If simple drive wheel design is used, then manufacturing is easier, but the robot cannot travel straight on carpets due to uneven slippage

Engineering Contradiction:

Improvedrive wheel manufacturingVSAvoidstraight travel on carpets

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The system uses a caster wheel with an angle sensor to detect deviations from straight travel and feeds this information back to the control unit. The control unit then adjusts the rotation speeds of the drive wheels accordingly, creating a closed-loop control system that maintains straight travel without requiring different wheel designs for different floor types

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The robot self-corrects its travel path by using the caster wheel as a passive sensor that automatically detects slippage-induced angle changes. The system serves itself by using the natural physical response of the caster wheel to detect and correct travel deviations without requiring complex active sensing mechanisms

Inventive Principle:

Principle #25Self-service

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 the robot cleaner to effectively travel straight on both hard floors and carpets by correcting for slippage-induced deviations, ensuring consistent cleaning performance across different floor types.

Implementation Method 1

The heading angle detection unit may include an encoder provided at the caster wheel to detect a deviation angle of the caster wheel signifying left or right deviation due to slippage of the robot cleaner

Methodology Applied

Scientific EffectEncoder:

Data Source

PatentUS8560119B2Robot cleaner and method of controlling travel of the same

Publication Date: 2013.10.15 SAMSUNG ELECTRONICS CO LTD

AI summary

A robot cleaner that travels straight through alignment of drive wheels to move the robot cleaner and a method of controlling travel of the same. Information related to a movement angle of the robot cleaner is detected from angle information of a caster wheel rotating depending upon a state of a floor, such as a carpet in a state in which texture of the carpet occurs in one direction, and, when the movement angle of the robot cleaner deviates due to slippages of the drive wheels, rates of rotation of the drive wheels are adjusted to correct the slippages of the drive wheels such that the robot cleaner easily travels straight.