Safety Data Broadcast for Decentralized Transport Device Control
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Solution Overview
Problem
Existing communication systems in driverless transport systems, such as those used in automatic warehouses and logistics, face challenges in efficiently transmitting data between a central control device and multiple decentralized devices, particularly in medium to large systems, due to high communication volume and bandwidth limitations.
Innovation Solution
A procedure involving unidirectional multicast or broadcast data transmission from a central control system to a majority of decentralized devices, with monitoring of transmission duration to prevent systematic delays, using time synchronization and bidirectional diagnostic units to ensure secure and efficient data transfer.
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 volume increases linearly with the number of AGVs and bandwidth is severely 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 device transmits one consolidated message containing safety commands for multiple devices, thereby reducing communication volume while maintaining safety control.
Solution Approach 2:
The broadcast telegram serves multiple functions simultaneously: it transmits safety commands to multiple AGVs, provides synchronization information, and enables monitoring of transmission quality. This multi-functional approach replaces multiple specialized 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 and multicast transmission. By changing addressing parameters and message structure, the protocol maintains its safety functionality while gaining the ability to address multiple devices simultaneously, thus achieving both safety and broadcast capability.
3Productivity
If unidirectional transmission is used to reduce communication volume, then bandwidth efficiency improves, but systematic delays cannot be detected
Solution Approach 1:
The patent incorporates feedback mechanisms into the unidirectional broadcast transmission. The control device monitors transmission quality by analyzing acknowledgments or diagnostic information returned from AGVs, enabling detection of systematic delays while maintaining the efficiency benefits of unidirectional transmission.
Solution Approach 2:
The patent implements preliminary timing synchronization between the control device and AGVs before safety-critical transmissions. By pre-synchronizing clocks and establishing expected transmission time windows, the system can detect delays without requiring bidirectional confirmation for each message, thus maintaining efficiency while enabling delay detection.
Data Source
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AI summary
The aim of the invention is the more efficient data transmission of safety-relevant data. This aim is achieved, according to the invention, by a method for transmitting data between the central control apparatus (200, 200') and a plurality of decentralised devices (101, 102, 100'), comprising the generating in the central control apparatus (200, 200') of a data telegram for the broadcast or multicast transmission of data to a plurality of devices, the unidirectional transmission of the data telegram from the central control apparatus (200, 200') to at least one decentralised device (101, 102, 100'), the monitoring of the transmission duration of the transmission of the data telegram from the central control apparatus (200') to the at least one decentralised device (101, 102, 100'), and the triggering of a predetermined safety reaction if the transmission duration exceeds a predefined value. The invention further relates to a control and data transmission system designed to carry out the method, and to means belonging to such a system.