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)