  There is a desire to move towards more flexible and automated factories. To
enable this, we need to assure the safety of these dynamic factories. This
safety assurance must be achieved in a manner that does not unnecessarily
constrain the systems and thus negate the benefits of flexibility and
automation. We previously developed a modular safety assurance approach, using
safety contracts, as a way to achieve this. In this case study we show how this
approach can be applied to Autonomous Guided Vehicles (AGV) operating as part
of a dynamic factory and why it is necessary. We empirically evaluate
commercial, indoor fog/edge localisation technology to provide geofencing for
hazardous areas in a laboratory. The experiments determine how factors such as
AGV speeds, tag transmission timings, control software and AGV capabilities
affect the ability of the AGV to stop outside the hazardous areas. We describe
how this approach could be used to create a safety case for the AGV operation.
