The distributed engine controls (DEC) task seeks to investigate the capabilities of a distributed network for aircraft engine controls. Traditional aircraft engine control systems use analog systems to communicate with sensors and actuators. The ability to upgrade an engine after manufacture, by swapping out sensors or actuators, is limited due to the analog signal component. Digital signals do not have this limitation, and additionally they do not require dedicated cabling, which may decrease engine weight. To understand the interactions between a new digital network and the engine controller, a representative model of the networks is required.
To construct this network model, a representative aircraft engine control network was constructed using Arduino™ microcontrollers and a custom protocol. This custom protocol called Engine Area Distributed Interconnect Network (EADIN) Lite, was created based on initial guidance documents released by the Distributed Aircraft Engine Working Group (DECWG). While other networking protocols do exist for simplex (single channel) networks, the software is too slow for hardware-in-the-loop testing, which is essential to testing real sensor and actuator hardware for the DEC program.
The EADIN Lite communication protocol allows the microcontrollers to talk with each other in a structured fashion over a simplex RS-485 network. As such, it is embodied in C++ code that runs on the microcontroller. The software is not mission- certified, and is being used for demonstration and testing purposes only. The software has been released open source on the NASA github website to enable community participation.
The program, coded in C++, allows a single master microcontroller to communicate to a series of slave microcontrollers in real time. This allows the master to send and receive information from the slaves such as commands or requests for information. Statistical data on the protocol performance is being used to develop Simulink models of expected network behavior such as cable failure effects, packet loss probability, and network delay times.