Boeing 747 Flight Simulator Architectural Study

1. Boeing 747 flight simulator in action – from http://www.bornrich.org/entry/plane-fanatic-builds-30k-boeing-747-flight-simulator-in-his-bedroom/. Flight Simulation – Ch 8 A Case Study in an Architecture for “Integrability” Before software - the Wallingford Improved Flight Trainer, 1942. From www.janusmuseum.org/flight/flight.htm .

2. Coming Up • Today… • Term paper - Intro • Ch 08 – Flight Simulation – this  • Intro – see for example YouTube vids: http://www.youtube.com/watch?v=JGyJqXJWkuY . • Thursday • Present outcomes for Project 2 • Turn in Thurs night (and HW 3 - Yikes!) “How to clean the Gherkin”

3. Overview • Structural Model • Minimize modules • N-Square charts • Requirements and Qualities • Three roles • Lots of constraints • Architectural Solution • Treatment of time (real-time)

4. Pattern - Structural Model • Simplicity and similarity of the system’s substructures • Decoupling of data- and control-passing strategies from computation • Minimizing module types • A small number of system-wide coordination strategies • Transparency of design

5. Structural Model

6. Roles • The Crew • The people being trained • The Simulator Instructor • Monitors crew performance • Initiates training situations • The Environment • Atmosphere, threats, weapons, other aircraft “Maybe that one’s not one of ours? Modern simulator from the outside.

7. Requirements and Qualities • Real-time performance constraints • Continuous development and modification • Maintains “verisimilitude” = realism, as the airplanes changed specs • Large size and high complexity • Developed in geographically distributed areas

8. Problems • Expensive to debug, test, and modify • Increased cost of integration • Unclear mapping between software structure and aircraft structure • Many coupling effects to be considered • E.g., pilot moves the rudder and aileron controls, which move the control surfaces, which affects the aerodynamics and causes the aircraft to turn. • Performance “fidelity” is # 1 goal

9. Architectural Solution Treatment of Time • Periodic time management • A fixed time quantum based on frame rate • Non-preemptive cycle scheduling – invokes each process for a fixed time quantum • Event-based time management • “Interrupt” based • Adds new events into event queue • Does in order of soonest needed • But all messages from a single source must be done in order! • Mixed-time systems • The two above systems must interact

10. Architectural Solution, cntd Structural Model Architectural Pattern • Executive • Handles the coordination issues • Application • Handles computation of the simulation • Functions are implemented by subsystems

11. Modules • Executive • Timeline Synchronizer • Periodic Sequencer • Event handler • Surrogate • Connects air vehicle model to environment model • Application • Subsystem controller • Controller children

12. Allocation of Functionalityto controller children Based on OO modeling of the “objects” of the real airplane: • Kinetics – the physics • Aircraft systems – distribution of energy within the airframe • Avionics – ancillary support • Environment

13. Decomposition • n-Square Charts • What “Partition 2” communicates with…

14. An example… Air Vehicle Model Domain

15. Summary How the architecture achieves… • Performance • Executive with time budgets, and • Periodic scheduling strategy • Integrability • All data and control pass through a subsystem controller as an intermediary • Each partition was restricted in inputs and outputs • Modifiability • Few base module configurations for the designer and maintainer to understand

16. Questions?