CoCPN-ng – Cooperative Cyber-Physical Networking: Next Generation

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From an abstract point of view a cyber-physical system can be modeled as a set of coexisting application control loops that share communication resources. The key idea of CoCPN is to implement cooperative sharing of communication resources among application control loops by balancing the quality of control (QoC) that each loop shall reach. Within the current project CoCPN we considered independent control applications each consisting of a single application control loop. The objective of CoCPN-ng is to further improve CoCPN to be able to cope with complex, elastic control applications that consist of multiple probably interdependent application control loops, e.g., in emerging smart factories. In contrast to the first funding period, CoCPN-ng considers interdependent application control loops, i.e., loops that affect each other in the physical (analog) world, e.g., inverted pendulums that could touch each other. Due to the increased dynamics envisioned in future cyber-physical systems, detailed manual pre-configurations of the system are not considered as a vital option. Therefore, within CoCPN-ng we plan to provide the CoCPN-translator with self-learning capabilities. We will investigate nonparametric online regression techniques as one possible approach. Furthermore, the impact of the interdependencies between application control loops on the newly developed metrics QoC and QM will be investigated based on systematic simulation experiments with our simulation and evaluation framework CoCPN-Sim. Regarding application control, more sophisticated control approaches will be pursued that send complete control laws to the actuators instead of plain input sequences. Furthermore, it will be researched how the control application specific “value” (e.g., criticality) of a transmitted control data packet can be utilized in the communication system in order to forward the most valuable information and discard information of less value. This requires suited mechanisms in the communication system (e.g., ARQ mechanisms, value-oriented queueing) that will be researched. Based on these mechanisms, we will design a control-aware transport protocol that is tailored to the needs of elastic control applications. We will conduct systematic simulation studies to investigate the applicability of CoCPN-ng in scenarios with varying numbers of control applications under changing communication conditions. We will use CoCPN-Sim that was successfully developed in the first funding period. Researching suitable trade-offs, for example regarding the detail of information being exchanged versus the achievable QoC is an important goal of the proposed project. Furthermore, trade-offs regarding communication and control complexity and the availability of resources (e.g., computing, storage, and communication capacity of resource-constrained sensors and actuators) will be investigated.