1. Introduction of the 4ZDM Research
To improve quality and reduce the quality variation characteristics in multi‐stage productionprocesses the 4ZDM cluster considers the explicit modeling and realization of quality feedback loops at different levels.This multi‐level quality feedback aims to control productprocess‐system self‐adaptation in multi‐stage production systems in dynamically changing environmental conditions and customer requirements. The multi‐level quality feedback loops add the dynamic aspects to the 4ZDM static reference architecture. They are enabling ZDM self‐adaptation by modifying the behavior of existing controllers based on the comparison of measured and reference quality targets. In addition to self‐adaptation, the 4ZDM cluster vision aims at defining and elaborating the research agenda for selfoptimization mechanisms that adapt autonomously and dynamically the quality subtargets for each process in order to achieve the global quality optimized results for multi‐stage production processes. In other words depending on the dynamically assessed state of the product‐process‐system state the 4ZDM research vision aims at modifying the individual process quality target values in response to process deviations in previous process stages. These feedforward process quality target loops will allow through multi‐stage process coordination to increase the quality levels and to reduce the quality deviations of the final product quality characteristics.
Research is needed to formalize the explicit representation of the 4ZDM quality control loops together with an analysis of their properties. There is a need to understand which quality feedback loops are the most important, to verify if the proposed produc‐process‐system adjustments are adequate, to validate that the stability of the system is maintained and that the process time constraints are respected.
The main expected benefit of the modeling and realization of quality feedback loops is the systematic reduction of quality deviations in complex product quality characteristics and customer requierements. As a result the process capability in such dynamic situations will be significantly increased.
By Odd Myklebust and Paul Xirouchakis, October 1st, 2013