Broadcast Safety Telegrams for Multi-AGV Data Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing data transmission methods in automated guided vehicle systems, such as PROFIsafe and PROFINET, are not suitable for efficient, safety-oriented communication in mid-sized to large facilities due to high communication traffic and limited bandwidth, especially when using Bluetooth or WLAN systems, making it difficult to manage a large number of vehicles without overloading the network.
Innovation Solution
A method involving unidirectional multicast or broadcast data telegrams from a central control apparatus to decentralized devices, with monitoring of transmission duration to ensure safety, using time synchronization and diagnostic units to trigger safety reactions if duration exceeds a threshold, allowing efficient and safe data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bidirectional point-to-point communication is used for safety control, then functional safety is ensured, but communication traffic grows linearly with the number of AGVs and bandwidth is limited
Solution Approach 1:
The patent combines multiple safety control messages into a single broadcast telegram that can be received by multiple AGVs simultaneously. Instead of sending individual point-to-point messages to each AGV, the control apparatus transmits one consolidated message containing safety parameters for all devices, thereby reducing communication traffic while maintaining safety coverage.
Solution Approach 2:
The broadcast telegram serves multiple functions simultaneously: it transmits safety parameters, provides timing synchronization, and delivers control commands to multiple AGVs in one transmission. This multi-functional approach replaces multiple specialized point-to-point communication channels with a single universal broadcast mechanism.
2Reliability
If PROFIsafe protocol is used for safety communication, then functional safety is achieved, but the protocol is not suitable for broadcast or multicast transmission
Solution Approach 1:
The patent modifies the communication parameters of the PROFIsafe protocol to enable broadcast transmission. Specifically, it changes the addressing scheme from individual device addresses to a broadcast address, and adjusts the message structure to include multiple recipient identifiers, thereby adapting the protocol for multicast/broadcast while preserving safety functionality.
3Productivity
If unidirectional transmission is used to reduce communication traffic, then bandwidth efficiency improves, but systematic delay in transmission cannot be recognized
Solution Approach 1:
The patent introduces a feedback mechanism where AGVs send acknowledgment messages back to the control apparatus after receiving broadcast telegrams. These acknowledgments confirm successful reception and allow the control apparatus to detect transmission delays or failures. The feedback loop enables delay detection in the otherwise unidirectional transmission system.
4Reliability
If time synchronization is implemented to monitor transmission duration, then safety reaction is enabled, but device complexity increases
Solution Approach 1:
The patent performs time synchronization preliminarily during system initialization or at predetermined intervals, rather than continuously during operation. The control apparatus and AGVs establish synchronized time references in advance, which are then used for monitoring transmission durations. This preliminary synchronization approach reduces the ongoing computational and communication overhead while maintaining safety monitoring capability.
Data Source
AI summary
More efficient data transmission of safety-relevant data is achieved by a method for transmitting data between the central control apparatus and a plurality of decentralized devices, which includes generating, in the central control apparatus, a data telegram for the broadcast or multicast transmission of data to a plurality of devices, unidirectionally transmitting the data telegram from the central control apparatus to at least one decentralized device, monitoring the transmission duration of the transmission of the data telegram from the central control apparatus to the at least one decentralized device, and triggering a predetermined safety reaction if the transmission duration exceeds a predefined value. Further, a control and data transmission system designed to carry out the method, and means belonging to such a system.