airborne imaging line scanner modernization patrick o’brien matthew weinstock
Post on 22-Dec-2015
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Design Overview
Modernizing a Vietnam War era scanner used to obtain visible and infrared images from low speed aircraft (converted from high speed aircraft (F-4 Phantom ‘Wild Weasel’) ran scanner from an aircraft speed near Mach 1 and obtained infrared images only)
Airborne Line Scanner
Two sets of mirrors: flat and curved Four flat mirrors rotated by variable
controlled DC motor One stationary curved mirror and one
stationary flat mirror
Rotating flat mirrors obtain one dimension of the image, while aircraft’s forward motion provides the second dimension
DC Motor
Variable Controlled from DC sourceMaximum of 10 HzAbsolute shaft encoder used to determine position of motor (rotating mirrors)Enclosed in scanner chassis
PCB123 and Front End Analog
Company used to design and produce PCB boards used in projectDesign program from PCB123 similar to that of P-Spice combined with VLSI design
Absolute Shaft Encoder
Precision guaranteed because every position is definableAble to obtain current position without needing a reference pointAttached to scanner chassis through bracket
Analog to Digital Converter
Portable USB-Based DAQ with Simultaneous Sampling (Windows) produced by National InstrumentsFIFO technology System made for continuous data
acquisition Data held in continuous memory
Needs to have 12-bit resolution, will have at most 16 bits of digital I/O
Analog to Digital Converter
Sampling rate of A/D is at most 60,000 samples/second Sample rate = mirror speed * number
of samples per revolution Maximum mirror speed is 10 Hz Number of samples is 6,000
A/D includes software drivers that will be customized for scanner
Controlling Unit
‘Briefcase Computer’ with AMD/Intel technologyCPU will run ActiveX controls and Visual Basic Code which will control data input and motor control
ActiveX and the A/D
‘Click and Drag’ programming abilityWide variety of controlsInterfaces with most technologies Will be used to interface A/D with the
‘Briefcase Computer’
Visual Basic Software and The Motor
Visual Basic offers ease of design for GUIProcesses will be triggered by movement and clicking of slider and buttonsGUI will also relay information gathered from motor and encoder
User Interface
User Interface: Start and stop system Controls how many times the flat
mirrors will turn Controls the speed of the motor Will show a preview of the image
captured, a numeric value for mirror speed, and the sensor temperature