Team Fischetti Insect Photography Rig – MDR Team Fischetti: Nafis Azad Brendan Kemp Rob Leveille.
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Transcript of Team Fischetti Insect Photography Rig – MDR Team Fischetti: Nafis Azad Brendan Kemp Rob Leveille.
Team Fischetti
Insect Photography Rig –
MDRTeam Fischetti:
Nafis AzadBrendan Kemp
Rob Leveille
2Team Fischetti
A Beautiful Day in a Field of Flowers – A Scenario
You want to take pictures of the flying bugs But they move too fast
• Your reaction time isn’t fast enough• Your camera’s reaction time isn’t fast enough
• It has to calculate several variables• Aperture• Shutter Speed• Focal Length
• The mechanical adjustments take too long
You need a way to bypass human and machine…
3Team Fischetti
The Insect Photography Rig
Will bypass the human aspect• Insect trips a laser when it is in the frame
Will bypass the machine aspect• All variables are preset• No calculations or adjustments need to be done
Just hold the rig where insects will fly• The insect will trip the laser when it is perfectly in place• The camera will be preset, in manual mode• Our circuitry commands the photo
How do we do it?
4Team Fischetti
Outline
The Problem – A Photography Scenario The Solution – The Insect Photography Rig The Design
• Frame and Sensors• Logic and IR Transmitter• IR Transmitter and Camera
The Challenges• Past: Timing, Logic, Remote• Present: Working Prototype• Future: Intersection Probability, Response Time, Frame,
Laser Shutoff
5Team Fischetti
Design Overview
Lasers and Sensors• Produce low when broken• Crisscross to triangulate• Create “mesh” of points• Output to logic
Logic Circuitry• Finds coincidence – AND• Sends signal to
transmitter• Transmitter sends IR
signal Camera
• Snaps photo
6Team Fischetti
Frame and Sensors – Design
Frame consists of base to securely attach the camera, two arms extending to the left and right of focal plane, and vertical mounts for the laser/sensor pair
Laser beams cross in the focal plane of the camera detect when an insect is in position
Sensor information is processed and communicated to camera via Nikon IR transmitter
7Team Fischetti
Logic and IR Transmitter – Design
During standby mode all photodiodes are collecting light from the lasers, producing a high logic on the inputs to the NAND gate
When a beam is broken an input of the NAND goes low thus producing a high logic at the output
When two intersecting beams are broken both NAND gates are pulled to high logic and the IR transmitter is turned activated
8Team Fischetti
Circuit Diagram – One More Time
9Team Fischetti
IR Transmitter and Camera – Design
The IR transmitter (shown below) was taken apart in order to be able to control it using the coincidence circuitry.
The button initiating the IR sequence to the camera is shorted and leads to the battery are now connected to a PMOS switch.
Once the coincidence circuitry has detected an object in the focal plane the IR transmitter is temporarily turned on via the PMOS switch which sends the IR signal to the camera.
The camera receives the signal and closesthe shutter, snapping a picture of the insect.
10Team Fischetti
Outline
The Problem – A Photography Scenario The Solution – The Insect Photography Rig The Design
• Frame and Sensors• Logic and IR Transmitter• IR Transmitter and Camera
The Challenges• Past: Timing, Logic, Remote• Present: Prototype• Future: Intersection Probability, Response Time, Frame,
Laser Shutoff
11Team Fischetti
Timing – Past Challenges
Need accurate measurement of lag• Ensure specifications, optimize design
Timing events within .5 second• Need microcontroller and two electric signals (start
& stop)
Start signal is easy• Use the photodiode signal
Stop is harder• Time when light is transmitted to chip• Mechanical process – electronics internal
12Team Fischetti
Timing – Past Challenges
SLR – Single Lens Reflex• Scene through lens is reflected to viewfinder• On capture, mirror snaps up blocking viewfinder
Laser into lens, out viewfinder, into photodiode• Don’t want to fry the camera sensor
Laser into viewfinder, out lens, into photodiode• Added benefit of variable focal length from lens
Hook both photodiodes to microcontroller• Insect one starts counter, lens one stops• Use interrupt based negedge detection• Output to LED bar
13Team Fischetti
Logic – Past Challenges
Original design was microcontroller• Obvious, but necessary?
Just want coincidence circuitry• Can be accomplished with logic – NAND gates• Faster and more elegant
Problem of interfacing photodiode to gate• Too much voltage with ambient light• Logical low was not registered
Reduce operating voltage• Registers high and low
14Team Fischetti
The Prototype
MDR Specs• Laser Trip System• Shutter trip• Timing System
15Team Fischetti
The Working Prototype: Part II
Laser/Sensor Pairs• 5mW Keychain lasers• Photodiode with sufficient sensitivity to red light (650 nm λ)
Prototype of Mounting Rig• Two arms complete with mounts for laser and sensor pairs• Lasers are to cross in the focal plane of the camera
Sensing Circuitry• Coincidence circuit detects presence of insect within the focal
plane of the camera
System lag circuitry• Microprocessor is used to test the lag of the system
16Team Fischetti
Outline
The Problem – A Photography Scenario The Solution – The Insect Photography Rig The Design
• Frame and Sensors• Logic and IR Transmitter• IR Transmitter and Camera
The Challenges• Past: Timing, Logic, Remote• Present: Working Prototype• Future: Intersection Probability, Response Time,
Frame, Laser Shutoff
17Team Fischetti
Intersection Probability – Future Challenges
What is the probability an insect will just fly through?• Randomly: infinitesimal• Fortunately, not random: traffic patterns, flowers
What can we do to increase our chances?• Our capture area is limited by the camera’s specs• Add more detection points• Crisscross ‘net’ of 6 lasers, 6 sensors• Ensure maximization of capture probability• Will be difficult to fit, physically
18Team Fischetti
Frame – Future Challenges
Requirements: light, stable, space constraints Needs to be worn with shoulder strap
• Usage could be fatiguing on its own
Minimal warping: 1mm^2 photodiode target• Real world stresses – don’t want to recalibrate• Needs to hold ungainly laser pointers securely
Need to fit 6 photodiode/laser pairs• The prototype is already crowded
Needs to be adjustable for lenses, focal lengths• Allow for flexibility, other lenses and camera bodies
19Team Fischetti
Response Time – Future Challenges
We believe our timing optimizations are sufficient• Not yet field proven
Our main sources of lag are transmit and mirror• IR transmit: .150 seconds• Mirror/camera: ~.2 seconds• Logic: 2 microseconds
Use a secondary shutter• Leave the main shutter open and ready• Use logic to drive secondary shutter• Response time on magnitude of microseconds
20Team Fischetti
Laser Shutoff – Future Challenges
Lasers are great for detection, attracting insects• They aren’t aesthetically pleasing
We need a way to shut them off Start with integrating power source
• Dismantle case and wire leads to main source
Use logic to control laser power• Ready mode: lasers on• Photo snap: lasers off• Back to ready mode
Use logic command to drive transistor
21Team Fischetti
Conclusions
The Problem – A Photography Scenario The Solution – The Insect Photography Rig The Design
• Frame and Sensors• Logic and IR Transmitter• IR Transmitter and Camera
The Challenges• Past: Timing, Logic, Remote• Present: Prototype• Future: Intersection Probability, Response Time, Frame,
Laser Shutoff Questions?