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 & Objectives This system consists of a propeller that is powered by a BLDC motor. When the BLDC is operated, the propeller will create a lift force. This force (if controlled properly) will allow the BLDC to move to the horizontal axis and maintain it there. The BLDC (with the propeller) are installed at one end of a rod that is pivoting around the shaft of an encoder. Later, another BLDC can be installed on the other side of the rod and control both motors to reach stability. The BLDC motor is mainly used in applications where rotary motion for extended period of time is needed. Due to their powerful performance, BLDC motors are used in remote controlled (RC) cars, helicopters, and planes.

Experimental setup

Components of the Design Project Brushless dc motor (BLDC a2208) Phidgets micro load cell Phidgets Wheatstone bridge interface Brushless speed controller Incremental rotary encoder Arduino Mega2560

Brushless DC Electric Motor A2208/12 Rotational speed = 1800rmp/v Max efficiency current = 8~10a (>74%) Weight = 36g Electrical resistance = 90mΩ To study the lift forces generated by the BLDC, a micro load cell is used to measure this force. First, the load cell needs to be calibrated. We used a calibration weight set to identify its readings using small weights (10g, 20g, 50g, and 100g). Once identified, the BLDC is mounted on top of the load cell to measure the lift force generated at different operating voltages.

Lift force Of the four forces of flight, we are only concerned with two: Lift Force and Weight Force Opposing forces (act against one another) Just like a propeller blade an airplanes wing is shaped with one side having more surface area (curved) than the other

Lift force continued From a side view, Air on the top side of an airplane wing has to move faster over a greater surface area to keep up with the air on the bottom. According to Bernoulli's Principle, which states an increase in speed will result in an proportional decrease in pressure: There must be a pressure difference between the top and bottom of the wing.

LIFT FORCE CONTINUED The result in the difference in the air pressure is a net upward force called LIFT The air under the wing (or in our case propeller blade) moves slower and exerts more of a force than the air moving above the blade. Since the force under the blade is greater than the force above the blade, the resulting force is UP.

Hobbywing Brushless Speed Controller Output: 30a continuous, 40a burst for 10 seconds Input voltage: 5.6v-16.8v/2-4s BEC (battery elimination circuit) output: 2a linear mode Max speed: 210,000 rpm for 2 poles; 70,000 rpm for 6 poles; 35,000 rpm for 12 poles Weight = 25g

Micro load cell A load cell is a force sensing element. Strain gauges mounted in precise locations measure the deformation of the cell, thus deforming the gauges. Deformation of strain gauges results in a change in the electrical resistance. Load cell is interfaced with the Phidgets Wheatstone Bridge Device to translate signal from load cell to a weight.

Phidget Bridge The single point load cell is mounted down at the two points shown Force is applied in the other of the arrow on the load cell The load cell measures the shearing effect on the beam The Phidgetbridge allows four connections for various load cells, gauges, etc The data values can be configured in a software

Incremental Rotary Encoder Used to measure speed, direction, and position of rotating shaft Interfaced with the USB4 with the encoder data acquisition device Power supply voltage 5v to 12v dc

Encoder data acquisition device Designed to measure 4 incremental encoders Interfaced with rotary encoder Includes libraries for various programming languages so users can develop their own applications Includes application demo as a graphical user interface

ARDUINO MEGA 2560 Microcontroller board based on the ATmega2560 Contains 54 digital I/O pins, of which 14 can be used for pulse-width modulation Will be interfaced with micro load cell, rotary encoder, and brushless DC motor

Current Progression The experimental setup has been established. The encoder is fixed to a wooden plate using a mounting bracket. Two couplers and two rods are connected to the encoder’s shaft. The load cell was calibrated using a calibration weight set.

Future Progression April – May 2014 Mount the BLDC on the load cell to study the lift force generated at different operating voltages. Select a propeller that can achieve the best lift within the range of voltage used. August – September 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 is used as a 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 October – November 2014 Include a second BLDC on the other end of the rod. Repeat the control algorithm for the new two-BLDC system.