Safety Vest System - Installation and Scalability

Installation in Existing Systems

The Safety Vest System has been designed with the specific intention of facilitating installation in existing (automated warehouse) systems with minimal interfaces and interventions in the infrastructure. There exist, however, some typical requirements regarding the facility where the Safety Vest System is to be integrated:

• A safety system must be in place that monitors access to the dangerous area and can bring the facility into a safe state e.g., by stopping all the dangerous machines.
• The environment should allow sufficient propagation of UWB radio signals.
• A Wi-Fi network must be available for the transfer of Safety Vest heartbeat signals to the Safety Vest Base Station.

These typical conditions can be modified wherever adoption of the Safety Vest System in different application scenarios is required, e.g. in less dangerous settings.

Emergency Stop Module Integration

Emergency Stop Modules are installed in each of the vehicles or robots to be protected by the Safety Vest System. An Emergency Stop Module is composed of three units – the Central Processing Unit and Power Supply (CPU&PS) unit and two UWB modules. The UWB modules are connected to the CPU&PS unit via flat cables.

There are no special requirements for positioning of the CPU&PS unit so it can be located anywhere convenient within or on the machine. The connections it requires, besides the cables that connect it to the UWB modules, are:

• a 24 VDC power supply e.g., from the AGVs battery,
• two independents normally open (NO) safety outputs that can be used to bring the machine into a safe state or communicate to the machine control system.

There is an optional CAN (Controller Area Network) interface that can be used for safe or non-safe communication with the machine control system.

Safety Vest Base Station Integration

The Safety Vest Base Station is intended to be mounted on a wall inside an access restricted space used to enter and exit the dangerous area. It has the following interfaces, as indicated in the picture below:

• a user interface composed of buttons and LED indicators
• two ports for connection and charging of SVs?
• an AC mains inlet and switch
• cable glands for exit button located inside the dangerous area; 1x safety output for enabling dangerous area entry/exit; 2x safety output for initiating a safe state of the facility

Number of Safety Vests

In the current prototype implementation of the Safety Vest System, two Safety Vests are supported. The system is fully scalable to support more Safety Vests.

Number of Emergency Stop Modules???

For an Emergency Stop Module to determine its distance to a Safety Vest, some UWB messages must be exchanged between them. This communication and the ensuing ranging calculations must be performed in a timely manner i.e. before the human and the machine come into dangerous proximity. This is not problematic until the number of machines in the proximity of the vest becomes large, at which point the available bandwidth of the Safety Vest may get used up and it cannot answer all incoming ranging requests from Emergency Stop Modules in good time.

The SVS circumvents this “crowding” problem by:

• ensuring that Emergency Stop Modules “hear” Safety Vest ranging broadcasts well before the respective machine comes within a dangerous distance of the human, and
• if the Safety Vest does not respond to an Emergency Stop Module’s ranging requests within a predefined time, the Emergency Stop Module will activate its safety outputs and bring the machine into a safe state.

With this approach, the human wearing the Safety Vest in the picture below is always safe. Emergency Stop Modules on any machines in proximity will either measure the distance and stop when the safety radius is breached or will be stopped because ranging communications failed.

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KON?AR - Electrical Engineering Institute is mainly focused on providing solutions in the area of railway and electric power equipment and systems. However, recognizing the huge potential of the developed technology of the Safety Vest System, we are publishing this blog post series to attract partners interested in bringing it to the market.?

This work has been supported by the European Union’s Horizon 2020 research and innovation program under grant agreement No. 688117 (SafeLog). SafeLog project consortium was comprised of:?

• Karlsruhe Institute of Technology
• Swisslog
• Czech Technical University in Prague
• The University of Zagreb, Faculty of Electrical Engineering and Computing?
• Fraunhofer Institute for Material Flow and Logistics?
• KON?AR - Electrical Engineering Institute?