ECE 353 - GoLogic Tutorial - UMass Amherst

ECE 353 - GoLogic Tutorial - UMass Amherst

Insect Photography Rig MDR Team Fischetti: Nafis Azad Brendan Kemp Rob Leveille Team 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 isnt fast enough Your cameras reaction time isnt 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 Team Fischetti 2 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? Team Fischetti 3 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 Team Fischetti 4 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 Team Fischetti 5 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 Team Fischetti 6

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

Team Fischetti 7 Circuit Diagram One More Time Team Fischetti 8 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 closes the shutter, snapping a picture of the insect. Team Fischetti 9 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 Team Fischetti 10 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 Team Fischetti 11 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 Dont 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 Team Fischetti 12 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 Team Fischetti 13 The Prototype MDR Specs Laser Trip System Shutter trip Timing System Team Fischetti

14 The Working Prototype: Part II Laser/Sensor Pairs 5mW Keychain lasers Photodiode with sufficient sensitivity to red light (650 nm ) 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

Team Fischetti 15 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

Team Fischetti 16 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 cameras specs

Add more detection points Crisscross net of 6 lasers, 6 sensors Ensure maximization of capture probability Will be difficult to fit, physically Team Fischetti 17 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 dont 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 Team Fischetti 18 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 Team Fischetti 19 Laser Shutoff Future Challenges Lasers are great for detection, attracting insects They arent 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 Team Fischetti 20 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? Team Fischetti 21

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