Boeing 747 flight simulator in action – from
http://www.bornrich.org/entry/plane-fanatic-builds-30kboeing-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 .
Slide 1
Coming Up
• Today…
– Term paper - Intro
– Ch 08 – Flight Simulation – this 
“How to clean the Gherkin”
• Intro – see for example YouTube vids:
http://www.youtube.com/watch?v=JGyJ
qXJWkuY .
• Thursday
– Present outcomes for Project 2
– Turn in Thurs night (and HW 3 Yikes!)
Slide 2
Overview
• Structural Model
– Minimize modules
• N-Square charts
• Requirements and
Qualities
– Three roles
– Lots of constraints
• Architectural Solution
– Treatment of time (realtime)
Slide 3
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
Slide 4
Structural Model
Slide 5
Roles
• The Crew
– The people being trained
“Maybe that one’s
not one of ours?
• The Simulator Instructor
– Monitors crew performance
– Initiates training situations
• The Environment
– Atmosphere, threats,
weapons, other aircraft
Modern simulator
from the outside.
Slide 6
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
Slide 7
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
Slide 8
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
Slide 9
Architectural Solution, cntd
Structural Model Architectural Pattern
• Executive
– Handles the coordination issues
• Application
– Handles computation of the simulation
– Functions are implemented by subsystems
Slide 10
Modules
• Executive
– Timeline Synchronizer
– Periodic Sequencer
– Event handler
– Surrogate
• Connects air vehicle model to environment model
• Application
– Subsystem controller
– Controller children
Slide 11
Allocation of Functionality
to 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
Slide 12
Decomposition
• n-Square Charts
– What “Partition 2” communicates with…
Partition 1
Outputs
Inputs
Partition 2
Outputs
Partition 3
Inputs
Slide 13
Air Vehicle Model Domain
• An example…
Kinetics Group
Loads
Vehicle State
Vector
Power
Aircraft
Systems Group
Power
Inertial State
Loads
Avionics Group
Ownship
Emissions
Environment
Emitter Data
Environment
Group
Atmosphere,
Terrain, and
Weather
Vehicle
Position
Slide 14
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
Slide 15
Questions?
Slide 16