Mobile Robot Follow-Up Control Using Direct Wireless Position Signals

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Solution Overview

Problem

Existing mobile robots face challenges in efficiently following each other without server communication, particularly when changing directions, leading to collisions and disruptions in collaborative tasks like cleaning or air conditioning, and require improved methods for collision-free and stable follow-up control.

Innovation Solution

Mobile robots transmit and receive signals to determine relative positions, adjust speeds based on trajectory lengths, and perform avoidance maneuvers to maintain planned paths without server intervention, ensuring uninterrupted and visually stable follow-up even when directions change.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If robot cleaners communicate through a server using WLAN technology, then communication coverage can be extended, but communication reliability deteriorates when robots are located where server connection is difficult

Engineering Contradiction:
Improvecommunication coverage areaVSAvoidcommunication reliability
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent introduces direct short-range wireless communication as an intermediary communication path between master and slave robots, bypassing the server for critical position data exchange. This dual-path approach (server for general coordination, direct communication for position data) resolves the contradiction by maintaining reliability through direct links while preserving extended coverage through server infrastructure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The communication system is segmented into two independent channels: server-based WLAN for general control and coordination, and direct peer-to-peer short-range wireless for position information exchange. This segmentation allows each channel to optimize for its specific function, with direct communication ensuring reliability for position data regardless of server connectivity status.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If the master robot determines position of slave robot using obstacle detection device, then position information can be obtained, but the slave robot cannot determine position of master robot

Engineering Contradiction:
Improveposition measurement capabilityVSAvoidbidirectional position recognition
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The master robot detects the slave robot's position using its obstacle detection device, then feeds back this relative position information to the slave robot via direct wireless communication. The slave robot uses this feedback to calculate the master robot's position relative to itself, achieving bidirectional position awareness through unidirectional detection combined with information feedback.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system merges the master robot's detection capability with wireless communication functionality to create a shared position awareness system. Instead of equipping each robot with full detection capabilities, the master's detection results are combined with communication to provide both robots with mutual position information.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If the head cleaner changes moving direction frequently to adapt to cleaning space shape and obstacles, then cleaning coverage is improved, but position reversal occurs between head and follower cleaners

Engineering Contradiction:
Improvecleaning space adaptabilityVSAvoidrelative position stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The system implements dynamic role assignment where master and slave roles are not fixed but can switch automatically based on real-time relative position detection. When position reversal is detected through continuous wireless communication of position data, the robots dynamically exchange roles to maintain proper formation, allowing frequent direction changes while preserving formation stability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the control parameter from fixed master-slave assignment to dynamic role assignment based on relative position. By monitoring position parameters in real-time and switching roles when reversal occurs, the system adapts to frequent direction changes while maintaining stable collaborative operation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3846978B1A robot cleaner and a controlling method for the same
Publication Date: 2026.04.08 LG ELECTRONICS INC
  • EP3846978B1 patent drawingFigure 1~2
  • EP3846978B1 patent drawingFigure 3~4
  • EP3846978B1 patent drawingFigure 5a~5b

AI summary

A mobile robot according to an embodiment of the present disclosure may include a driving unit, a communication unit, and a controller configured to recognize the location of another mobile robot using the signal, and control a moving speed of the main body such that the another mobile robot follows a trajectory corresponding to the movement of the main body based on the recognized location. In addition, the controller may transmit a first signal to the another mobile robot in response to the main body approaching the another mobile robot in a direction of being close to the another mobile robot according to a change of the moving direction, and control the avoidance moving of the main body and the another mobile robot based on a second signal of the another mobile robot responding to the first signal.