Abstract

1. Stepper Motor Control with a Microprocessor for Laser Beam Data Analysis Colin Gregory, ErkanGulturk Bridgewater State University, Bridgewater MA 02325 Mentor: Edward F. DeveneyPh.D Abstract   Our goal is to construct a mechanism that allows us to precisely launch laser light through a fiber optic cable and measure the collimated output. We currently have no measurement equipment with fine enough resolution to sample the angular intensity of the beam. Using an Arduino UNO microcontroller, 5V Unipolar Stepper Motor, and proper gearing we can control the fiber optic outputs angular movement precisely. The code for our stepper motor was written in the open source Arduino environment. We are continuing our effort to set up the mechanical system that will rotate the platform holding the fiber optic output. Materials We are attempting to create a stepper motor driven platform that allows precise angular control of the laser output. Below is an image of the fiber optic laser set-up. Our 5V, 1A, 4-Phase Unipolar Stepper Motor and Arduino Uno microcontroller were purchased from Jameco Electronics. The Arduino is being used to control the stepper motor. A 2004 Darlington Array was also used to properly transfer the Arduino’s output to the stepper motor. • Methods • Within the stepper motor are a series of magnets and electromagnetic coils that can be charged in such a fashion as to move the stepper motor in small increments. The motor can make full steps, half steps, or a combination of both. The diagrams below display this concept. • The image below shows the circuitry for our stepper motor. We are using a 9V battery in combination with a 5V regulator for power. We powered the stepper motor from a separate power source using a powered breadboard. • Our code is written in the open source Arduino environment as seen below. Current Status With the ability to control the stepper motor using code written to the Arduino, we will continue our efforts to set up a mechanical system that will optimize our precise control of the laser beam output. Our options include using a Tamiya High Efficiency worm gear box (below) that offers both 216:1 and 336:1 gear ratios. Our second option includes a simple gear transfer using an inexpensive gear set that can be seen below. The 5V Unipolar Stepper Motor makes 1.8°+/- 5% steps, making 200 steps equivalent to one full rotation. A 216:1 ratio would result in each step moving the output 0.008°. To reduce error in the calculated angular displacement we would move multiple steps before each output measurement. References "12 Volt Unipolar Stepper Motor." Www.parrallax.com. Web. 3 Apr. 2012. <http://dscl.lcsr.jhu.edu/wiki/images/9/98/Stepper_Motor_27964.pdf>. "Arduino - StepperUnipolar." Arduino. Web. 4 Apr. 2012. <http://arduino.cc/hu/Tutorial/StepperUnipolar>. "Getting Started with Arduino (Make: Projects) [Paperback]." Amazon.com: Getting Started with Arduino (Make: Projects) (9780596155513): Massimo Banzi: Books. Web. 2 Apr. 2012. <http://www.amazon.com/Getting-Started-Arduino-Make-Projects/dp/0596155514>. "Tamiya America Item #72004 | Worm Gear Box H.E." Tamiya America. Web. 11 Apr. 2012. <http://www.tamiyausa.com/product/item.php?pro duct-id=72004>.