Safe calculation for industrial robotic control

Abstract

Two recent trends in industrial robotic applications demand for a new generation of control platforms. The first one is the paradigm shift from separating robots and human workers with fences and light curtains towards a work environment in which humans and machines work together very closely. The second one is the preference of commercial off-the-shelf hardware (COTS) over dedicated hardware for economical and performance reasons. Applying COTS hardware into safety critical systems is a trend that is already in wide use in areas like public transportation or public safety, assuming the possibility for designing lower priced systems as well as less hardware dependency to specific manufacturers. Increasing computational power implicating less need for specialized hardware, as well as ongoing development of virtualization technologies implying new possibilities dealing with redundancy press this development. Up to now, this approach is only used for non-safety relevant parts in the area of industrial automation. Increasing complexity of state of the art automation systems leads towards the use of more powerful CPUs, ideally standard industrial PCs. This work identifies and analyzes possible exclusion criteria for a COTS solution with respect to IEC 61508 safety integrity level (SIL) 3 on behalf of a proposed system concept. The concept is theoretically analyzed with respect to the performance of state of the art hardware. In addition an estimation of the order of magnitude for the performance impact of the calculation using arithmetic codes over the native execution is given.