Moving robot and method of controlling the same

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Solution Overview

Problem

Moving robots that use a rotating mop face difficulties in maintaining a desired velocity or distance due to slip issues, particularly with microfiber or fabric mops creating low friction, leading to shorter movement distances.

Innovation Solution

A method of controlling the travel of a moving robot by measuring and compensating for slip rates using gyro and acceleration sensors, allowing for adjustments in rotational and linear movements based on detected slip rates, especially when encountering changes in floor materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a rotating mop with microfiber or fabric is used for movement, then the robot can move autonomously, but the low friction between the mop and floor causes slip and reduces movement distance

Engineering Contradiction:
Improveautonomous movement capabilityVSAvoidmovement accuracy
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent employs feedback control by continuously measuring the actual movement distance through wheel encoders and comparing it with the expected distance calculated from motor rotation. The slip rate is calculated as the difference between expected and actual movement, and this feedback is used to adjust motor commands in real-time to compensate for slip and maintain accurate positioning.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces pure mechanical movement control with a hybrid control system that incorporates sensors (wheel encoders, inertial measurement units) and computational algorithms. Instead of relying solely on the mechanical transmission from motor to mop, the system uses electronic feedback and software-based slip compensation to achieve accurate movement control despite variable friction conditions.

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

2Speed

If the robot increases motor power to move faster or farther, then velocity and distance improve, but slip increases due to low friction

Engineering Contradiction:
Improvemovement velocityVSAvoidvelocity control accuracy
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The system uses real-time feedback from wheel encoders and inertial sensors to monitor actual velocity and position. When slip is detected (discrepancy between commanded and actual movement), the control algorithm adjusts motor power dynamically to compensate, allowing the robot to maintain accurate velocity control even at higher speeds where slip would normally be more severe.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent implements dynamic adjustment of motor commands based on real-time slip rate calculations. Rather than using fixed motor parameters, the system continuously adapts motor power and rotation commands based on current friction conditions, enabling velocity control that remains accurate across varying speeds and floor conditions.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If basic motion control without slip compensation is used, then the control system is simple, but the robot cannot achieve desired velocity or distance

Engineering Contradiction:
Improvecontrol system complexityVSAvoidtravel control accuracy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback-based slip compensation system that calculates slip rate by comparing expected movement (from motor encoder counts) with actual movement (from wheel encoders and inertial sensors). This feedback loop allows accurate travel control without requiring complex mechanical modifications, achieving high reliability through software-based compensation rather than hardware complexity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system uses multi-functional sensors (wheel encoders for both speed control and slip detection, inertial measurement units for both orientation and slip compensation) that serve multiple purposes. This approach achieves accurate travel control without adding dedicated slip-sensing hardware, maintaining relative simplicity while improving reliability through the versatile use of existing sensors.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 method effectively controls the travel of the moving robot by accurately determining and adjusting for slip rates, ensuring consistent movement velocity and distance, even when external factors like floor material changes occur.

Implementation Method 1

measuring the slip rate of the moving robot by a gyro sensor for detecting the rotational velocity of the moving robot

Methodology Applied
Scientific EffectGyroscopic effect: Gyroscope

Implementation Method 2

calculating the slip rate of the moving robot by an acceleration sensor for detecting the acceleration of movement of the moving robot

Methodology Applied
Scientific EffectAcceleration detection: Accelerometer

Implementation Method 3

microfiber or fabric mops create little friction against the floor when the moving robot moves on the rotating mop

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3571022B1Moving robot and method of controlling the same
Publication Date: 2023.08.09 LG ELECTRONICS INC
  • EP3571022B1 patent drawingFigure 1~2
  • EP3571022B1 patent drawingFigure 3a
  • EP3571022B1 patent drawingFigure 3b

AI summary

A method of controlling a moving robot is provided. The method of controlling a moving robot includes the steps of: (a) performing a basic motion of the moving robot which moves on a rotating mop; (b) measuring the slip rate of the moving robot; and (c) controlling the travel of the moving robot.