Biology for Computer Engineers Course Handout.pptx
Team 12- Blind Eye.pptx
1. Team 12: Blind Eye
Aaron Castagna, Dawid Minorczyk, and Nikola Ivancevic
2. Introduction
● Over 7 million people in the US suffer from severe visual impairment
● Can we find a way to see without the use of eyes?
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3. Objectives
Grant the operator the ability to sense the environment without the use of sight or
light.
The device will be wearable and hands-free, providing a smaller and more
lightweight alternative to a cane.
The user will only need to switch the power on and adjust the volume knob on the
headphones in order to fully activate and operate the device.
Over the range of 0 [m] to 5 [m], sound sensing devices offer a cheaper
alternative to light based methods of sensing.
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5. Power Module: Batteries
2 MN1604 Batteries with 200 mAH charge capabilities.
Arranged in series connection with central node grounded.
Produces about +9.33 and -9.33 voltage at output rails.
Dual output power supply essential for proper amplification.
For timespan of 1 hour, [(200 mA) / (320 mA)]*60 = 37 minutes of operation.
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6. Power Module: Linear Regulators
MC7805, MC7808, and MC7908 linear
regulators with 1A current limits.
Two MC7805 regulators used to output
5.01 volts DC to Teensy 3.2 and ADC.
One MC7808 and MC7908 used to output
+7.998 and -7.955 volts for Op-Amps.
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7. Ultrasonic Sensing: Transmitter and Receiver
Following the idea of SONAR and how bats navigate we chose to use ultrasonic
transducers, which transmitted/received 40 kHz signals.
What are the limitations?
Why not LIDAR/RADAR?
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8. Ultrasonic Sensing: Inputs and Amplification
40 kHz, 3.6 volt square wave output from Teensy 3.2.
Sent through op-amp with an inverting amplifier configuration.
Op-amp has a gain of 2.1 to produce skewed 40 kHz. 7.56 volt square wave.
This amplified square wave will then be sent to the transmitter for emission.
Total of three transmitters and amplifiers used to allow for beam forming.
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9. Ultrasonic Sensing: Amplification and Output
Echoes from transmitted ultrasonic signal are picked up by the receiver.
Receiver has built in bandpass filter centered around 40 +/- 1 kHz.
Output from receiver is sent into another inverting op-amp circuit .
This op amp circuit has a gain of 13.75.
Total of three receivers and amplifiers used to allow for beam steering.
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10. Signal Modulation: Rectification and Clamping
TLC1518 ADC can only convert analog signals from 0 to 5 volts.
Thus, the amplified receiver signal must be modulated.
The signal is first rectified with a 1N5819 Schottky Diode and 33KΩ resistor.
The signal is then sent through a 1N4733A zener diode to clamp the amplitude at
5.1 volts.
A total of three circuits are built to match each of the receiver circuits.
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11. Beamforming and Beamsteering
Based off of the principle of
constructive and destructive
interference of waves
A line array of transducers can be
utilized to create and steer an
acoustic beam in a desired
direction.
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13. Digitization: ADC
The Teensy needs to be able to read the signals
coming from the receivers.
Needs a minimum total sample rate of 240ksps.
This was calculated from knowing Nyquist
sample rate is frequency x 2. Since we are
sending at 40 kHz need a sample rate of 80
kHz per channel.
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18. Output: Headphones
Model S6HBGY
Designed to output 3.6 volt square waves into audible frequencies
Higher frequencies indicate a close object (880 Hz Max)
Lower frequencies indicate a distant object (55 Hz Min)
Coupled with beam steering, operator can hear if object is in front of them to
within 1.2 meters
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