Codey Lozier Christian Thompson Advisor: Dr. Mohammad Saadeh Stability Control System for a Propeller Powered by a Brushless DC Motor (BLDC) Codey Lozier Christian Thompson Advisor: Dr. Mohammad Saadeh

Introduction Control Systems Stability Control System Setup Objectives Components of Stability Control System Current Progression Future Progression

Control Systems Goal is to modify a system so it behaves in a desirable way over time Arrows (signals) represent vector-valued functions of time Basic Control System Plant Controller Sensor r- reference input v- sensor output u- actuating signal d- external disturbance y-measure signal n- sensor noise

Stability Control System Setup

Stability Control System Modification Old Shaft New Shaft

Objectives A 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 angle The 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 beam Every time the motor rises or falls the shaft connected to the rotary encoder rotates This “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 pins 14 digital I/O can be used for PWM User friendly programming environment

Brushless DC Motor (BLDC) Fixed on shaft coupler Goal is to use the propeller to create a lift force Electrically commutated, does not use brushes Powered using brushless speed controller Commutation 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 Force Of the four forces of flight, we are only concerned with two: Lift Force and Weight Force Opposing 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 Continued Air 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 systems Receives 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

Image Retrieved from 3133 Micro Load Cell CZL635 datasheet A load cell is a force sensing element Small components called strain gauges mounted in precise locations Change in electrical resistance Image Retrieved from: http://ueidaq.wordpress.com/2013/08/02/the-twists-of-strain-gauge-measurements-part-1/ Image Retrieved from 3133 Micro Load Cell CZL635 datasheet

Phidget Bridge Contains 4 Wheatstone Bridges USB interface ( 2 ) Amplifies signal sent from micro load cell ( 1 ) Demo applications are provided Users 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

YUMO Rotary Encoder Measure change in angle, direction, and speed Resolution of 2000 pulses/rev Manufacturer provides a demo application Produces a signal that represents an “index” or angular position Signal for direcion a

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 interface Interfaced with rotary encoder Includes application demo Users can develop their own applications Image retrieved from US Digital USB4 Encoder Data Acquisition USB Device User Manual

Current Progression The experimental setup has been established Two 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 force Measure lift force of BLDC using micro load cell (current) Youtube Video

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 Progression September-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)