Open Access

In the presented project, new approaches for the prevention of hand movements leading to hazards and for non-contact detection of fingers are intended to permit comprehensive and economical protection on circular saws. The basic principles may also be applied to other machines with manual loading and/or unloading. Two new detection principles are explained. The first is the distinction between skin and wood or other material by spectral analysis in the near infrared region. Using LED and photodiodes it is possible to detect fingers and hands reliable. With a kind of light curtain the intrusion into the dangerous zone near the blade can be prevented. The second principle is video image processing to detect persons, arms and fingers. In the first stage of development the detection of upper limb extremities within a defined hazard area by means of a computer based video image analysis is investigated.

Although extensive safety measures and safe working procedures have been applied to improve and secure metal working machines, they still put their operators at risk. These risks might often result from manipulation errors, in particular if safety measures are ignored. In this contribution, a safety evaluation strategy has been developed that applies VR and mixed reality technologies to investigate the usability of working machines. An automatically controlled machine tool was simulated and connected to a real input panel, usually employed in industrial settings. However, Human-Machine Interfaces are sometimes built in a way that does not prevent the operator from cognitive misinterpretations which in turn might result in mistakes. To take that into account, a control program for a lathe was altered by hiding a typical programming mistake in the lines of code. Subjects were given the task to evaluate the program in single step mode and to report abnormalities while running the simulated lathe, comparable to new control program checks at real machines. An evaluation of the study demonstrated that even experienced metal workers accepted the simulation and reacted as if the given task was real. Behavioural data of considered subjects showed comparable profiles and most subjects rated the VR- based approach as a reasonable means for investigating work safety problems.