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Wireless Bluetooth Controller For DC Motor

Wireless Bluetooth Controller For DC Motor. ECE 445 Spring 2007 TA: Brian Raczkowski Professor Gary Swenson. Project #5 Abhay Jain Reid Vaccari. April 26, 2007. Abhay Jain. Reid Vaccari. Group #5. Introduction. Motivation:. Wireless becoming more and more available and widely used

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Wireless Bluetooth Controller For DC Motor

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  1. Wireless Bluetooth Controller For DC Motor ECE 445 Spring 2007 TA: Brian Raczkowski Professor Gary Swenson Project #5 Abhay Jain Reid Vaccari April 26, 2007

  2. Abhay Jain Reid Vaccari Group #5

  3. Introduction Motivation: • Wireless becoming more and more available and widely used • Bluetooth is one of the major players • Interested in power and motor control

  4. Objectives Features: • Wireless Controller for DC Motor • Bluetooth Wireless Standard • Windows based GUI • 12 V Permanent Magnet Geared Motor • Battery powered • Variable speed

  5. Objectives Benefits: • Practical • Provides Flexibility • Economical • User-friendly • Can be ran from any PC running Windows

  6. Applications • Robotics • Remote control car • Industrial Uses • Household Uses

  7. Design Specs • Output voltage varying from 0-12 Vdc • Adjustable speed from 0 to 95 RPM and 0 to 6222 RPM on load side • Motor can turn in both directions • Continuous motor loads of 15 W • Maximum motor torque of 2.12 N-m • Wireless control up to 60 feet

  8. Block Diagram

  9. Hardware Layout

  10. Full Schematic

  11. User Interface • GUI developed in Visual C++ • User can accelerate, decelerate, start and stop motor • Motor direction can be chosen • Speed referenced to lower geared side • Maximum speed setpoint of 95 RPM • Displays Load side RPM as well

  12. User Interface • Speed is output to serial port by software • Control signal specifies direction • Transmitted via USB Bluetooth Module • When Stopped, speed is ramped down • Same for direction switch

  13. User Interface

  14. User Interface

  15. Bluetooth PC Side: • Bluetooth USB Receiver for PC • Set up as COM port • Transmits USART serial data to WML-C40 Bluetooth Module

  16. Bluetooth Motor Side: • BlueSMIRF WML-C40 Module • Vcc = 5 V, with internal regulator • Receives USART serial data from USB module • Transmits to PIC16F877 via serial TX

  17. Microcontroller • PIC16F877 40 pin DIP • Programmed in C using CSS Compiler • Receives speed control signal from user software • Translates desired speed to necessary duty cycle • 16 kHz internal clock used for timers • Sends duty cycle to H-bridge inputs using onboard PWMs

  18. H-Bridge • NJM2670D2-ND Dual H-Bridge Driver • Consists of 4 MOSFETS as switches • Duty cycle determines speed by controlling how long switches are active • Motor direction can be controlled • IN1 and IN2 fed from PWM • Adjusted voltage is output to motor terminals

  19. H-Bridge Image from Wikipedia

  20. Motor • Pittman GM9434 12 V Permanent Magnet DC Motor • 65.5:1 Gear Ratio • Max Rated Motor Speed = 93.9 RPM • Max Rated Torque = 2.12 N-m

  21. Functional Tests • Used HyperTerminal to get initial connection between Bluetooth Modules and another PC acting as the PIC • Sent serial input to PIC, tested basic outputs (LED, serial text echo) • Tested H-Bridge using hardwired controls to verify functionality • Motor operation verified using battery

  22. Operation Tests • For a given duty cycle, the resulting speed was measured • Using a collection of these points, a linear translation from duty cycle to speed was calculated • @ 2 RPM: Duty cycle = 110 • @ 108 RPM: Duty cycle = 950 • Y = mx + b  Duty = 7.92(speed) + 94.15

  23. Challenges • Replaced Voltage Divider consisting of resistors with Voltage Regulators • Original H-Bridge was Surface Mount • Replaced expired Bluetooth module with simpler model with internal voltage regulation • ASCII Translation Issues • Converting string control signal to usable decimal integer

  24. Successes • No voltage issues after switching to regulators • Solved ASCII formatting issues • New H-Bridge was capable • PWM operations didn’t provide difficulties

  25. Motor Operations • No-Load Motor Current vs. Terminal Voltage

  26. Motor Operations • Max Load Motor Current vs. Terminal Voltage Recommended Max H-Bridge Current = 1.2 A

  27. Results • Motor ran in both directions • 0-95 RPM on lower geared side • 0-6222 RPM on load side • Maximum continuous load = 15 W • Maximum continuous torque = 1.33 N-m

  28. Results

  29. Duty Cycle to H-Bridge PIC To H-Bridge Control Signal @ 48 RPM PIC To H-Bridge Control Signal @ 5 RPM

  30. Motor Duty Cycle Motor Voltage @ 48 RPM Motor Voltage @ 5 RPM

  31. Next Step • Designed feedback loop for closed system control • Installed Fairchild H21A1 Phototransistor Optocoupler • Designed optical encoder wheel on motor shaft with one notch to read RPM • Directed signal to PIC, began programming

  32. Next Step

  33. Next Step • Feed Forward can provide very tight speed control when load is known • With Feedback implemented, will respond to change in load and compensate • PDA instead of laptop

  34. Recommendations • Use an H-bridge with high current rating to maximize power produced • PIC Programming: C over Assembly • Stable Voltage Regulators = Good • Size Motor and components based on power needs

  35. Thank You • Brian Raczkowski • Alex Spektor • Wally Smith & Frank Dale (Parts Shop) • Scott McDonald (Machine Shop)

  36. Thank You

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