Transcript BRAD Bio Robotic Aquatic Demonstration

BRAAD
Bio Robotic Autonomous Aquatic
Demonstration
Uzma Alam and Danielle Osler
ECE 345
Group 9
Background

Weakly Electric Fish


Generate and detect Electric fields
Electro receptive

Ability to sense Electric Fields



Monitor changes in receptors on skin
On the order of milli-volts
Passive Sensing
Objective

Principal deliverables
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
Accurate sensing
Autonomous movement

Simulate the passive sensing of
electroreceptive fish

Modify an RC boat and add autonomous
functionality
Original Design
Original Design
Sensor Theory
Two Possible Configurations
EKG Sensors
Need to use sensors in pairs
Use second configuration
Sensor Testing
Signal Strength (Actual)
Voltage
30
25
20
Voltage (12cm)
15
Voltage (6 cm)
10
5
kp cos( )
V
, r  d
2
r
  cos1 (dist. between sensor and wall) : 0 to12 cm
kp  dipole constant
d  dipole length: 1.5cm
22
20
18
16
14
12
10
8
6
4
2
0
Di
st a
nc
e
0
Amplification

Use High Precision Instrumention Amps

Options: AD524, LM741, LF357N

Documented applications – Analog signals

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Heart rate – Frequency .05Hz to 150 Hz
Pulse on finger – Frequency starts at .03 Hz
A to D can take 20 mV and convert it

Use more precise sensing for Microcontroller
Amplification
Final Sensor Configuration
Microcontroller Flowchart
Power Up A/D
Start
Sets Initial PWM for Motor/Steering
Initialize
Sets ATDCTL5 to 8 bit conversion
Samples and stores digital values
GetAtoD
Linear compare of voltage difference
CompVolt
Updates duty cycle of Steering PWM
Update
Uses RTI to sample A/D every 0.25s
Delay
Motorola HC12
Assembly
Language
Microcontroller Testing

A/D Conversion
 Accurate to 2 lsb
 Possible to use unamplified signal
Motor and Steering Control

Servos
 Steering – TS-11
Microservo
 Motor – Hitec
HT7001A
Motor and Steering

Interface Boards
 Toggle between uC
and receiver
 Power from receiver
voltage regulator
Motor and Steering
Pulse Width Modulation
Reverse
Motor
Steering
Forward
Left
Right
Power Theory
All power from one battery
 Simulations:

Battery Voltage
10
9
8
Voltage (V)
7
6
Voltage on 9V
5
Voltage w/ Motor
Voltage with both
4
3
2
1
0
0
10
20
30
Tim e (sec)
40
50
60
Power Design:
Connect all components to the same common:
Physical Layout
Results
Successes
 Communication
Between Modules
 Unique Solution to
EKG sensing
 Teamwork
Challenges
 Amplification of DC
signals
 Size reduction
 Physical construction
Recommendations

Amplify signals

Add smoother turning capability

Add Stop functionality

Make boat smaller

Add more sensors
Acknowledgements
Professor Nelson
Professor Swenson
Julio Urbina
Braad