Abstract
The basic concept of safety of machinery in a dangerous situation, which consists out of hazard and human was to separate both factors in housdorff-space and shut down energy to stop the machine. In case of Human-Machine-Interaction, people live together with hazards and therefore it means paradigm shift on safety. It is therefore necessary to set up certain condition for safety in case of Human-Machine-Interaction. In this case it is not avoidable to take consideration on four factors of safety,namely ethics, technology, economics and social system.
