Multi-Robot Trajectory Following with Dynamic Path Simplification

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Solution Overview

Problem

Existing mobile robot systems face challenges in efficiently following complex moving paths and maintaining communication, leading to potential collisions and delays in cleaning operations, especially in complex environments or when different types and specifications of robots are involved.

Innovation Solution

A mobile robot system that stores and follows trajectory information of a leading robot, allowing flexible follow-up by omitting parts of the path based on obstacle detection, sensor data, and communication signals, enabling efficient navigation and minimizing completion delays even in complex regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the slave robot determines the position of the master robot through server communication, then the position information can be obtained, but the communication may be disconnected when located at places difficult to communicate with the server

Engineering Contradiction:
Improveposition determination reliabilityVSAvoidcommunication system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a dual communication architecture where the server acts as an intermediary for normal operations, but direct peer-to-peer communication between robots serves as a backup intermediary when server communication fails. This resolves the contradiction by providing multiple communication pathways without requiring a completely complex system redesign.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically changes communication parameters by switching between server-based communication and direct robot-to-robot communication based on connection status. When server communication is unavailable, the slave robot changes its communication mode to receive position information directly from the master robot, maintaining reliability without permanent system complexity.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the following robot strictly follows the complex moving path of the leading robot, then the cleaning coverage can be maximized, but the completion time is delayed

Engineering Contradiction:
Improvecleaning coverage efficiencyVSAvoidcleaning completion time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The following robot dynamically adjusts its behavior based on real-time conditions. It transitions from strict path following to selective path following when complexity is detected, and can further adapt by creating shortcut paths. This dynamic adjustment resolves the contradiction between maximizing coverage and minimizing time loss.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The cleaning task is segmented into phases: initial strict following for coverage, then selective following when complexity is detected, and finally shortcut creation for time-critical sections. This segmentation allows the system to optimize for coverage in some phases and speed in others, resolving the time-coverage tradeoff.

Inventive Principle:
Principle #1Segmentation

3Area of stationary object

If the robot cleaner changes moving direction frequently to clean complex spaces, then the cleaning coverage is improved, but the trajectory becomes complex and difficult to follow

Engineering Contradiction:
Improvecleaning space coverageVSAvoidtrajectory complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The following robot creates a simplified copy of the leading robot's trajectory by identifying and following only key waypoints rather than every movement. This copying approach maintains cleaning coverage benefits while reducing trajectory complexity to a manageable level.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The system performs preliminary analysis of the trajectory to identify complex sections before the following robot attempts to follow them. By detecting complexity in advance, the system can prepare alternative strategies such as creating shortcut paths or adjusting follow-up parameters, preventing the propagation of excessive complexity.

Inventive Principle:
Principle #10Preliminary action

4Extent of automation

If the slave robot receives position information only through the server, then centralized control is maintained, but the communication may be disconnected when the master or slave robot is located where it is difficult to communicate with the server

Engineering Contradiction:
Improvecentralized control capabilityVSAvoidcommunication reliability
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The control architecture dynamically shifts between centralized (server-mediated) and decentralized (direct robot communication) modes based on server availability. This dynamic adaptation maintains centralized control when possible while ensuring reliability through decentralized fallback, resolving the contradiction between control centralization and communication reliability.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3787458B1A plurality of robot cleaners
Publication Date: 2024.01.31 LG ELECTRONICS INC
  • EP3787458B1 patent drawingFigure 1
  • EP3787458B1 patent drawingFigure 2~3
  • EP3787458B1 patent drawingFigure 4

AI summary

A mobile robot according to an embodiment of the present disclosure may include a traveling unit configured to move a main body; a memory configured to store trajectory information of a moving path corresponding to the movement of the main body; a communication unit configured to communicate with another mobile robot that emits a signal; and a controller configured to recognize the location of the another mobile robot based on the signal, and control the another mobile robot to follow a moving path corresponding to the stored trajectory information based on the recognized location. In addition, the controller may control the moving of the another mobile robot to remove at least part of the stored trajectory information, and allow the another mobile robot to follow a moving path corresponding to the remaining trajectory information in response to whether the moving path corresponding to next trajectory information to be followed by the another mobile robot satisfies a specified condition.