NASA - National Aeronautics and Space Administration

F-18 simulator

The Simulation Engineering Branch is known for developing high-fidelity engineering simulations that can support various research phases ranging from conceptual studies through flight testing as well as providing a research tool that enhances the quality, quantity, and feasibility of the research objectives. This branch provides an engineering service that is positively recognized by its customers for its responsiveness, quality and productivity.

Research Aircraft Integration Facility (RAIF) Functions
The key to ground test operations in the RAIF is the ability to perform real-time operations with the actual flight vehicle, simulating the in-flight environment while remaining on the ground. Testing in the RAIF is carried out through automated techniques in which each aircraft is interfaced to a high-fidelity, real-time simulation. The process is controlled by an engineering workstation that establishes initial conditions for the test, initiates the test run, monitors its progress, and records and stores generated data. The workstation also analyzes results of individual tests, compares results of multiple tests, and produces reports.

Simulation computers used in the automated, aircraft-testing process are also capable of operating in a stand-alone mode with a fixed-base laboratory cockpit, complete with its own instruments and controls. Development and modification of control laws; qualification of aerodynamic, propulsion and guidance models; and flight planning functions traditionally associated with real-time simulation also can be carried out in this manner.

Workstations provide test engineers with computer-aided test tools, minimizing the time required to qualify new flight software. Laboratories within the RAIF can be linked to Dryden's mission control rooms and other facilities. This gives researchers and engineers real-time comparisons of flight and simulation results and allows for immediate clearance of flight test points. This same capability also provides realistic training for mission controllers.

Simulation
Simulation systems in the RAIF support many configurations for each project, with varying levels of aircraft hardware included. Simulations are used for a variety of research purposes such as generating and capturing frequency responses and time histories, conducting redundancy management tests, failure modes and effects tests, and pilot evaluations. Simulations also support pilot training, flight-research mission planning and report writing.

Point of Contact
Gary Kellogg
Chief, Simulation Engineering Branch
661.276.3779
gary.v.kellogg@nasa.gov C-17 simulator Scalable Configuration

• Faster-than-real-time (batch)
  • Expedited dynamics calculations for numerous repeated runs
• Soft and hard real-time (interactive)
  • Cockpit
  • 3-D Visuals
  • Controlled execution rate for synchronization to hardware and proper handling qualities
• Hardware-in-the-loop
  • Mission Computers
  • Flight Control Computers
  • Actuators
  • Health Monitors
  • INS/GPS
  • Whole Aircraft

Operational

• Fixed-based engineering simulations
  • Cockpit Interface Unit
  • Simulation Electric Stick (SES)
• Pilot Evaluations
• Operable by One Person
• Interfacing with Flight Hardware is routine
  • Mil-STD-1553
  • ARINC 429
  • Ethernet
  • RS-232/RS-422
  • Analog and Discrete I/O
  • PCM streams
• Non-linear 6-DOF (Degree of Freedom)
  • Oblate, rotating earth, LEO capable
  • Traceability to certified Shuttle simulation, X-30 (NASP), and X-33
• Place simulation product in the hands of the customers
  • Provide source code and documentation
  • Remote access
• Flexibility
  • Many types of aircraft simulated, including unique vehicles
  • Multiple platforms (Solaris and Linux)
  • Multi-language support (Fortran, C, C++, Java, Ada)
  • Rapid development
• Real-time 3-D graphics
  • Multiple simulated aircraft
  • HUD (Heads up Display) Symbology
• Real-time displays
  • Control room displays driven directly from the simulation (GRIM, PDS, IADS)
  • Allows for display prototyping
  • Connects prototype displays with simulated flight conditions
• Telemetry encoding (PCM)
• Real-time frame synchronized recording (time history data)
• Real-time data playback
  • Flight data
  • Previous simulation run
• Linear model output for analysis

Modeling and Core Capabilities

• Vehicle Specific Models
  • Actuators/Effectors
  • Aerodynamics
  • Control System
  • Engine
  • Guidance and Navigation
  • Landing Gear
  • Sensors
  • Mass Properties
• Core Framework
  • Equations of Motion
  • Atmosphere/Winds
  • Terrain
  • Batch / Real-time Operation Mode Selection
  • User Interface
  • Command Processor
  • Scripting Language
  • Event Logging
  • Code Generators
  • Automated Testing
  • Data Recording/Playback
  • Linear Model Generator
  • Telemetry Encoder
  • Hardware Interfaces
  • External Application Interfaces
  • Help System

User Interface

• Graphical Displays are programmed in Java for portability
• Simulation is command driven, so all GUI features can also be scripted.
• Model details are shown on plain text or HTML display pages, coded in C++, C, or Fortran.
• Display pages also process model-specific commands.
• User can customize and save window layout.

Mil-Std-1553 Data Bus

• The data bus code is automatically generated from bus description files
  • Eliminates coding errors
  • Reduces development time
• Data bus is simulated in software-only simulations to ensure similar latency and quantization effects
• Simulated avionics are interchangeable with flight hardware.

Data Dictionary

• Defines all public data, including data type, dimensions, description, units, sign convention, and limits.
• C and Fortran data structures are generated automatically from the data dictionary.
• Symbol table provides runtime access of a variable's value and all dictionary info.

Scripting

• Scripting Language
  • All commands can be scripted
  • If-Then-Else logic
  • Argument substitution
  • Nested scripts
• Calc Language
  • C-like interpreted language developed in-house to add test conditions (faults, diagnostic messages, etc.) into the execution sequence of the simulation
  • Used to dynamically configure many Core modules such as: File I/O, Network Interface, and the Telemetry Encoder.

Automated Testing

• Test Framework
  • User enters Calc language code at predetermined test points.
  • Introduce faults, noise, off-nominal conditions for one or many models
  • Scripted pilot inputs
• Rule-Based Diagnostic Message Stack
  • User defined conditions and responses
  • Color coded severity levels
  • Capable of testing any simulation parameter

External Application Interface

• Generic network interface to external application:
  • Matlab/Simulink
  • Sim-to-sim
  • Display applications
• Provides access to all symbol table data.
• Permits external application to control the simulation.
• Simulink models can be tested in real-time. After the model is finalized, C code can be generated and compiled into the simulation.