Decentralized Material Flow Control Using Logical Clocks

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Solution Overview

Problem

Existing material flow systems in the intralogistics sector face challenges in adapting to changing conditions without losing efficiency, particularly in preventing deadlocks and ensuring coordinated movement of goods packages across decentralized systems.

Innovation Solution

A method for controlling material flow systems where vehicles communicate autonomously and move along a material flow path with logical clocks, ensuring monotonically increasing time stamps for movement steps and allowing tandem movements to prevent deadlocks and optimize path selection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a decentralized control system is used to allow flexible adaptation of material flow systems, then adaptability is improved, but coordination complexity and deadlock risk increase

Engineering Contradiction:

Improveflexibility of material flow systemVSAvoidcoordination complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by introducing logical time stamps and velocity parameters that vehicles use to coordinate their movements. Each vehicle carries information about its logical position and speed, allowing decentralized coordination without centralized control. This resolves the contradiction by enabling flexible adaptation while maintaining coordination through standardized parameter exchange.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback mechanisms where vehicles continuously exchange information about their position, speed, and intended movements with other vehicles in the system. This decentralized feedback loop allows vehicles to adapt to changing conditions while maintaining system-wide coordination, preventing deadlocks without requiring centralized control.

Inventive Principle:

Principle #23Feedback

2Reliability

If vehicles move autonomously without centralized control, then system robustness is improved, but risk of deadlocks increases

Engineering Contradiction:

Improvesystem robustnessVSAvoiddeadlock risk

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by having vehicles perform safety checks and coordinate their movements in advance before actual movement occurs. Vehicles exchange information about their intended paths and speeds before committing to movements, preventing deadlock situations before they can arise. This maintains autonomous operation while reducing deadlock risk through proactive coordination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements preliminary anti-action by having vehicles proactively prevent potential deadlocks through advance coordination and speed adjustment. Vehicles monitor the system state and adjust their movements to prevent situations that would lead to deadlocks, countering the harmful effect before it manifests.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If logical clocks with time stamps are used for coordination, then deadlock prevention is improved, but communication overhead increases

Engineering Contradiction:

Improvedeadlock preventionVSAvoidcommunication overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent applies partial action by having vehicles exchange only the necessary minimal information (time stamps and velocity parameters) required for coordination, rather than complete state information. This reduces communication overhead while still providing sufficient data for deadlock prevention through logical clock comparison.

Inventive Principle:

Principle #16Partial or excessive action

4Productivity

If multiple vehicles operate simultaneously, then productivity is improved, but coordination difficulty and deadlock risk increase

Engineering Contradiction:

Improvethroughput of material flow systemVSAvoidcoordination difficulty

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements self-service by enabling vehicles to autonomously coordinate their own movements using the logical clock mechanism and velocity parameter exchange. Each vehicle independently determines its movement strategy based on information from other vehicles, eliminating the need for complex centralized coordination while maintaining high throughput.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9809395B2Method for controlling a material flow system

Publication Date: 2017.11.07 KARLSRUHER INST FUR TECH

AI summary

A method for controlling a material flow system, wherein the material flow system includes vehicles for transporting goods packages, wherein the vehicles communicate autonomously among one another in the material flow system, wherein the vehicles move by movement steps along a material flow path from a starting node to a target node, and wherein a logical clock is associated with each node. The method includes providing each movement step of a first vehicle with a time stamp, carrying out movement steps such that for the first vehicle, successive movement steps assume monotonically increasing values for the time stamp, and for each node that is traversed, providing an outgoing movement step of the first vehicle with value of a time stamp which is less than or equal to a value of a time stamp for a subsequently incoming movement step of a second vehicle.