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Stability Control System for a Propeller Powered by a Brushless
DC Motor (BLDC)
Codey LozierChristian Thompson
Advisor: Dr. Mohammad Saadeh
Introduction
Control SystemsStability Control System SetupObjectivesComponents of Stability Control SystemCurrent ProgressionFuture Progression
Control SystemsGoal is to modify a
system so it behaves in a desirable way over time
Arrows (signals) represent vector-valued functions of time
Basic Control SystemPlantControllerSensor
r- reference inputv- sensor outputu- actuating signal d- external disturbancey-measure signaln- sensor noise
Stability Control System Setup
Stability Control System Modification
Old Shaft New Shaft
ObjectivesA brushless DC motor is attached to a propeller,
and fixed onto the end of a horizontal beam. A shaft will be fixed onto the horizontal beam
creating a 90 degree angleThe opposite end of shaft will be attached to
rotary encoder. When the motor is energized, the propeller will
produce a lift force that will stabilize the beamEvery time the motor rises or falls the shaft
connected to the rotary encoder rotatesThis “index” value will be used as an error signal
Arduino Mega 2560
Microcontroller board based on the ATmega2560
Contains 16 analog input pins
Contains 54 digital I/O pins14 digital I/O can be
used for PWMUser friendly programming
environment
Brushless DC Motor (BLDC)
Fixed on shaft couplerGoal is to use the propeller
to create a lift forceElectrically commutated,
does not use brushesPowered using brushless
speed controllerCommutation is induced
through PWM
Brushless DC Motor Modifications
Original propeller could not generate enough lift force
Had to be replaced with 8 x 4.5 carbon fiber (10g) propeller
New propeller generates force that can stabilize the beam
Propellers
Carbon Fiber
Weight: 10 g for each propeller
Size 8 X 4.5
Lift ForceOf the four forces of
flight, we are only concerned with two:
Lift Force and Weight ForceOpposing forces The airfoil of an
airplane’s wing is just like a propeller blade
Schematic of Air Flow Through the Propeller
Y
X
Pressure Variation Along Slipstream
P2 < P1 & P3 > P4 = P1 = Patm
Lift Force ContinuedAir under the propeller blade, moves slower
and exerts more of a force than the air moving above the blade.
Force under the blade is greater than the force above the blade
Brushless Speed Controller
Electronic speed controller (ESC)
Powers motor (17Vdc)Used in high power RC
systemsReceives PWM signals
from Arduino Mega
Brushless Speed Controller
Potentiometer can be used to change the frequency and duty cycle of PWM
Change in resistance increase/decreases speed of motor
Micro Load Cell
A load cell is a force sensing element
Small components called strain gauges mounted in precise locations
Change in electrical resistance
Image Retrieved from 3133 Micro Load Cell CZL635 datasheet
Image Retrieved from: http://ueidaq.wordpress.com/2013/08/02/the-twists-of-strain-gauge-measurements-part-1/
Phidget BridgeContains 4 Wheatstone BridgesUSB interface ( 2 )Amplifies signal sent from micro load cell ( 1 )Demo applications are providedUsers can develop own applications
Image Retrieved from 1046 PhidgetBridge 4-Input Product Manual
Microload Cell Calibration
Used demo program provided by manufacturer
Performed several trials
Values produce were stable
Need to amplify signals being sent from load cell
Measure change in angle, direction, and speedResolution of 2000 pulses/revManufacturer provides a demo
applicationProduces a signal that represents an “index” or angular positionSignal for direcion a
YUMO Rotary Encoder
YUMO Rotary Encoder
Shaft is stabilized with pillow block
Device is fixed to table
Encoder is interfaced with data acquisition device
Encoder data acquisition device
Designed to measure 4 incremental encoders
USB interfaceInterfaced with rotary
encoder Includes application demoUsers can develop their own
applications
Image retrieved from US Digital USB4 Encoder Data Acquisition USB Device User Manual
The experimental setup has been establishedTwo couplers and two rods are connected to the
encoder’s shaft.The load cell was calibrated using a calibration
weight set.Selected propeller for the desired lift forceMeasure lift force of BLDC using micro load cell
(current)
Youtube Video
Current Progression
Future Progression
June - August 2014 Setup a control algorithm with the following components:
The goal is to stabilize the output rod in the horizontal position
The encoder reading serves as a good reference point. It can be used as feedback
The driving signal is the error in encoder reading (difference between reference and actual readings)
This error controls the magnitude of the BLDC operating voltage
Future ProgressionSeptember-November 2014 Include a second BLDC on the other end of the rod.
Repeat the control algorithm for the new two-BLDC motors system
Integrate all components using a data acquisition system, and a control algorithm in real time environment (e.g. LabVIEW)