Methodology for simultaneous robot system safety design: Dissertation

The design of a production system is a challenging and varied task. The designer of a robot system must realize that a technical solution alone cannot create a safe and effective workplace for people. Industrial robots represent a high degree of automation. The design of robot systems can offer examples for many other manufacturing systems. This study was done from the point of view of the desig- ner. It concentrates on a narrow design task in order to give the operators of the system a workplace that is as good and sensible, as productive, and as safe as possible. The central objective of this study was to present a simultaneous methodology for the safety design of an industrial robot system. A second objective was to evaluate the results of preliminary safety analyses based on the computer models of robot systems in comparison to the safety analyses of the actual robot systems built. The decisions made by designers and the robot user concerning the safety level and production were evaluated, and the recommendations of robot safety standards were tested under realistic conditions simulated in the laboratory. The case studies carried out to test the research questions investigated in this thesis supported the hypothesis that the new software tools can effectively be applied to the safety design of a robot system. The hazards can be identified and the risks can be assessed during the design phase of the system. The human aspects can be taken into account better. During the design phase, the operators of the system can create a clear picture of the system, can make comments, and can improve the system. They can also evaluate the importance of the changes with regard to their work and work environment. This new, even technical, tool can create a concrete visual bridge from the "human-oriented design approach" to the real design work of a robot system. The evaluations indicated that it is practicable to use a 3D-model of the system to make a reliable safety analysis from the model. A safety analysis can be made from the model far before the actual investment decision is made. The comparison of the three different safety strategies - basic level strategy, advanced level strategy and production adapted strategy - showed that the effect of a well-designed and production-adapted safety system is significant from the viewpoint of production. More attention should be paid to efforts to create and test procedures for practical design work, and to the training of designers. These measures would yield good results and would not require strict and limiting stan- dards and orders.