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Array Processors in Real-Time Flight Simulation

IP.com Disclosure Number: IPCOM000131618D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Nov-11
Document File: 9 page(s) / 35K

Publishing Venue

Software Patent Institute

Related People

Karl S. Forsstrom: AUTHOR [+3]

Abstract

The use of digital computers in flight simulation calls for the efficiency of array processor execution -- if the inherent programming limitations can be managed. Real-time pilot-in-the-loop flight simulation presents a number of unique computational problems: fast and efficient execution of differential equations, linear interpolation of many large tables, and a computer operating system that allows for timely interrupt handling without unnecessary interference. Special-purpose digital computers, such as array processors, can significantly enhance the performance of a simulation computer system by handling some of these tasks.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

This record contains textual material that is copyright ©; 1983 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Contact the IEEE Computer Society http://www.computer.org/ (714-821-8380) for copies of the complete work that was the source of this textual material and for all use beyond that as a record from the SPI Database.

Array Processors in Real-Time Flight Simulation

Karl S. Forsstrom,

Northrop Aircraft Group

The use of digital computers in flight simulation calls for the efficiency of array processor execution -- if the inherent programming limitations can be managed.

Real-time pilot-in-the-loop flight simulation presents a number of unique computational problems: fast and efficient execution of differential equations, linear interpolation of many large tables, and a computer operating system that allows for timely interrupt handling without unnecessary interference. Special-purpose digital computers, such as array processors, can significantly enhance the performance of a simulation computer system by handling some of these tasks.

Aircraft systems

The motion of an aircraft or its control surfaces is continuous; that is, the motion is smooth and without discrete steps. A true mathematical representation or simulation of these motions must therefore be done with differential equations that reflect the continuous nature of the changes in motion. Continuous solutions to this set of equations can be performed only on a continuous computing device such as an analog computer. For discrete solutions, approximations to the aircraft differential equations are derived by using difference equations that can then be solved on a discrete computing device -- a digital computer. The digital solution gets closer to the true analog solution as the step size (fram,e time) decreases.

Fidelity is the ability to re-create the amplitude and phase of the aircraft variables. In a digital aircraft simulation, fidelity is modified by computer-generated transport delays, frame-time- dependent frequency response, and precision of computation. Fidelity is important to aircraft designers because it influences the flying qualities of the aircraft, and to aircraft pilot training specialists because it affects transfer of training between a simulator and the actual aircraft.

Aircraft simulation is usually divided between analysis simulations, which are executed in what is known as nonreal time, and pilot-in-the-loop or hardware-in-the-loop simulations, which are executed in so-called real time.

The term real time is used to define a computation process in which the execution time of the computer is synchronized with tha~hysical-event time (wall-clock time) being modeled. Analog computers excel at real-time simulation and can, in fact, execute faster or slower than real time for certain applications. In a real-time digital computer simulation, the execution tim...