Cloud Conveyors System: A Versatile Application for Exploring Cyber-Physical Systems

We present a versatile application for cyber-physical systems (CPS), called the

Cloud Conveyors System

(CCS). This system comprises a collection of mobile conveyor units with simple periodic behavior; the units move back and forth along fixed tracks. The system-level objective is to transport entities from some input port to an output port when each entity has its own target output port, deadline, and end-to-end QoS constraints. Entities ride on the mobile units to physically move from one location to another. Entities may transfer instantaneously between two units — or when the unit is at an input or an output. We refer to these transfers as cyber transfers because they involve decision-making and the entities do not have to transfer at every possible opportunity. We view the transport of each entity in CCS as a

CPS-Task

that evolves both in space and in time; more precisely, a CPS-Task is an alternating sequence of cyber transfers and physical moves that starts at an input and ends at the output of the entity. This novel model for a CPS-Task allows one to explore solutions to some of the principal CPS challenges namely, Composition, Control Strategies, Computational Abstractions, Model-driven Engineering, and Verification & Validation. Further, this abstract and well-defined problem is useful in CPS Education and Training because it has a rich structure with intertwined cyber and physical dynamics; also, the scale and complexity of the problem can be increased by adding more units or changing the configuration of the system without increasing the implementation burden, which is critical to validating CPS solution techniques on physical testbeds.