Download wind sensor

ECE445 Presentation
Smart Umbrella
Group 35 : Dominic Antonacci,
Jonathan Buie, Martin Miller
TA: Cara Yang
Objective
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Wheel chair mounted
system to adjust
umbrella according to
wind speed and
direction
Consists of 3 elements
– Wind Sensors
– Control System
– Motor system
Block
Diagram
WIND SENSOR
Wind Sensor Requirements
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Physical Integrity of Flex Sensors
Measure the direction of the wind
Measure Wind Speed within 3.5 mph
Original Wind Sensor
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Non conventional method
of wind speed detection
using flex sensors
Significant outdoor testing
required to measure response
across wind range (0-25mph)
Sensors are delicate and
require individual calibration
Wind
Wind Sensor Challenges
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Expected Resistances between 10kΩ (neutral),
60kΩ – 110kΩ
Small dynamic Range for Resolution of ADC in
controller
Cup Anemometer and Wind Vane Simple and
more reliable
Wind Sensor Components
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Cup Anemometer
– Measure the wind speed
– Output Square Wave
•
Wind Vane
– Measure direction of wind
– Degree measure corresponds to resistance value
– Voltage Divider for A/D output
Wind Vane Circuit
Voltage Divider
• Need to drop
Voltage before 1.5 V
for ADC in MSP430
•
MOTOR
Mechanical Requirements
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Umbrella should be able to withstand 20 mph
winds.
Umbrella should be able to quickly adjust with
changes in wind speed
Power should come from a 12V wheelchair
battery
Motors Chosen
Banebots RS555-12V
• 12V Brushed Motors
• 15A Stall Current
• Peak Efficiency
•
– 6660 RPM
– 4.76 oz-in
Source: http://banebots.com/pc/MOTOR-BRUSH/M5-RS555-12
Motor Controller I
Designed a motor
controller to be able
to power these
specific motors
• Drives motor from
PWM signal
• Capable of driving
motors in either
direction.
•
Source: https://en.wikipedia.org/wiki/H_bridge
Motor Controller II
Motor Controller III
Issues With Motor Controller
Gate switching times
were too fast
• Lack of decoupling
capacitors
• Motor Drivers rated
to 12V. Battery can
be charged to
around 13.8V
•
MICROCONTROLLER
Controller Requirements
• Able to rotate the umbrella at least 360 degrees
• Able to pitch the umbrella a maximum of 45
degrees.
• Can move to any location in range within 2
degrees.
• Non-oscillatory output
Microcontroller
• INPUT from sensors
• Wind sensors
• Positions sensors
• OUTPUT PWM signals
• Use PID to determine duty cycle
Microcontroller Build and Testing
• PWM output
• Use serial to set period and duty cycle
• Measure output on scope
• Measure frequency
• Measure duty increment
• Pure hardware interrupts a must for high
frequency PWM
Microcontroller Build and Testing II
• ADC Input
• Setup ADC to read 4 channels in sequence
• Use a potentiometer as a test input and write
output to serial to verify
• Known good inputs and outputs eased testing of
internals.
PID Issues
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Gain tuning
Discrete Measurements
System Identification
What’s NEXT
Future Work
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Redesign circuit schematic
Improve PCB layout
Redefine Requirements
– Meeting requirements did not mean circuit
functioned as expected
Conclusion
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In all, we created a
hands free device for
use on a wheel chair
Future improvements
– Field Testing
– Potential handheld
implementation
– Lower Cost of system
– Wind Sensing Accuracy
Special Thanks
• We wish to thank the ECE Machine Shop for
their time, advice, and effort towards the
construction of the mechanical structure.
• The members of the Electronics Shop for PCB
construction and help with overall
– Our project would not have looked nearly as
impressive if it wasn't for their massive assistance!
• Special Thanks to Cara Yang our TA as well as Dr.
Makela and Dr. Oelze
Works Cited
•
Banebots Motor Graphic
– http://banebots.com/pc/MOTOR-BRUSH/M5-RS555-12
•
Wikipedia H-Bridge Graphic
– https://en.wikipedia.org/wiki/H_bridge
•
Wind Sensor Data Sheet
– https://www.sparkfun.com/datasheets/Sensors/Weather/W
eather%20Sensor%20Assembly..pdf
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Flex Sensor Data Sheet
– https://cdn.sparkfun.com/datasheets/Sensors/ForceFlex/F
LEXSENSORREVA1.pdf