Boeing F-18 E/F Flight Control System Test Station
Background
The development of flight control hardware frequently requires validation with a high fidelity simulation of the airframe. Most developmental applications of simulations interfaced with the flight control hardware dictate the connection of the hardware to a large scale engineering
simulation of the airframe in order to get the required fidelity and frame rates. Unfortunately, in most current environments, the access of the engineering simulation by the hardware engineers is limited and expensive, and frequently complicated by the physical accessibility of the
test station hardware. In an application of D-Six at the Advanced Hardware Development Labs at Boeing, St. Louis, they were able to interface an existing high fidelity model of the F-18E/F into the airplane’s flight control hardware and demonstrate the flexibility of a low cost dedicated
simulation environment for flight control hardware interfacing.
Test Station Description
The test station is a hardware implementation of the F-18 E/F flight control system. D-Six is used as a control station to implement a hardware in the loop simulation. The complete F-18 E/F simulation model (aerodynamic model, engine model, hinge moment model, actuator and sensor
models, and the flight control model – 1.4 million data points and 30k lines of FORTRAN code) is loaded into D-Six. The portions of the flight control system code replicated by the hardware is disabled (but other portions, such as sensor and engine control modules, remain active),
and the required state variable inputs redirected to the flight control test station hardware over an Ethernet connection using UDP/IP. The flight control hardware generates new surface position commands using the state variable inputs that are in turn transmitted back to the sim for
the next time step integration. This sim/hardware loop is currently run at the same 80 hz frame rate as the flight hardware operates at. Within this operational loop, several other hardware communication tasks are also conducted. Pilot cockpit control inputs, as well as cockpit switch
states, are brought in using digital and analog I/O cards installed in the same PC running D-Six. Finally, D-Six also provides the out the window graphics through a pair of high resolution graphics cards, also plugged into the same PC running D-Six. The functionality needed to
communicate to the test station, I/O cards, and graphics boards are all added to D-Six dynamically through plug-in modules. This alleviates the need to re-code the simulation every time a change in the hardware or the communication protocol is required. The F-18 E/F model itself is also
loaded as a separate dynamic link library into D-Six.
Summary
Several aspects of this hardware and software integration are unique. First, because F-18E/F simulation mechanized was the current F-18E/F simulation used in the support of flight test at St. Louis and at Patuxent River, the highest fidelity simulation model available was used for the
hardware application. Since a D-Six version was already developed and in use by the Navy, the model was immediately available for this application by merely transferring the project to the users at St. Louis. The novel utilization of a UDP/IP hardware interface, rather than a more
costly shared memory interface, in the application of real time hardware interaction is also unique. It is important to note, all of the software modules used to connect hardware to D-Six were developed completely separately from D-Six simulation environment. No changes were made to the
model code or compiled executables as they were transferred from the Navy’s application of the same flight model. D-Six brings in all the required functionality as separate plug-in modules. The modules use a well defined interface and are guaranteed to work with future versions of
the simulation, and any new hardware or software modules developed for future applications will also run seamlessly in conjunction with simulation models built on earlier versions of D-Six.
Other D-Six Success Stories
Implementation of Wright Laboratory
F-16 MATV Simulation into D-Six
Application
of D-Six at Air Force Research Laboratory
Italian
AV-8B II+ Mission Simulator Aerodynamics Model Development
Fokker
Control Loading and Motion
Utilization
of D-Six for ACAS Development
Pilatus
Aircraft Engineering Flight Simulator
Boeing
F-18 E/F Flight Control System Test Station
Aerial
Refueling Application
