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AUTOMATIC GUIDED FAN

AUTOMATIC GUIDED FAN. Group 15 Alphonse Shiwala Cho Whan Park Girum Kassa ECE 445: Senior Design November 29 th , 07. INTRODUCTION.

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AUTOMATIC GUIDED FAN

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  1. AUTOMATIC GUIDED FAN Group 15 Alphonse Shiwala Cho Whan Park Girum Kassa ECE 445: Senior Design November 29th, 07

  2. INTRODUCTION Our project is to design and build an automatic guided fan. The fan will take the signal from the tracking device on fan. Thus fan will follow a user any direction he or she goes. The Fan will control the power of the fan automatically according to the distance of the object from the fan.

  3. Design Overview • Beacon • Fan Direction Control System • Infrared Receiving System • Unipolar Stepper Motor and Driver • Speed Control System

  4. OBJECTIVES • Beacon • Tracking system for fan movement • Range finder for wind speed control • Stepper motor • Low power consumption

  5. Modification from Original Design • We have accomplished all our proposed goals except range detection distance • In order to make our product more practical and functional, we made some improvements. • Increase IR signal range of beacon • Immunity against ambient light

  6. FEATURES • Automatic Speed Control • 3 Speeds (Low, Medium & High) • Error Detection • Motion Tracking • 180 degrees turning angle • Search mode • 3 Modes of operation • Normal • Motion Tracking • Automatic Speed Control

  7. Motor Control System • Parts Used: • Uni-Polar Stepper Motor • Uni-Polar Stepper Motor Controller • Uni-Polar Stepper Motor Driver

  8. Motor Control System (Cont’) • Uni-Polar Stepper motor • Less complexity to controller the motion of the stepper motor. • More flexibilities to control different positions. • Appropriate torque to move the fan and some sensors. • High torque-to-inertia for faster start and stop. • It Consume less power.

  9. Motor Control System (Cont’) • SPECIFICATIONS • Holding Torque.. 53 oz-in • Rotor Inertia...... 0.547 oz-in^2 • Step Angle........1.8 deg/step • Weight................1.17 lbs • Step Angle (Өº)=1.8º(N of Pulse) • Pmax=5v*1A=5W • Pmin=5v*.68A=3.4W • 2 Phases

  10. Motor Control System (Cont’) • Torque Curves • Half-Step • Speed (Revolutions/Second) • Torque (oz-in)

  11. Motor Control System (Cont’) • Uni-Polar Stepper Motor Controller • Universal Shift Register (SN74LS194AN) –Logic Chip • The stepper motor steps when there is a transition ↑(0 to 5v) on the clock • The speed of the rotation is control by the number of transition on the clock

  12. Motor Control System (Cont’) • Controlled by three inputs: Clock, So, and S1.

  13. Controller input and out puts values Vcc=4.5v to 5.5v We used Vcc=5V I input=23mA Vo max=3.4v Vo min=2.7v Io max=.8mA Io min=.4mA Power out put Pmax=2.72mW Pmin=1.08mW Motor Control System (Cont’)

  14. Motor Control System (Cont’) • Uni-Polar Stepper Motor Driver • Four NPN Transistors and four diodes • NPN transistor will allow a large current to flow from collector to emitter when there is small current from base to emitter. • Diodes are used to protect the transistors from reverse current generated by the motor.

  15. Motor Control System (Cont’) • Uni-Polar Stepper motor Controller and Driver (Schematic)

  16. Infrared Beacon • Operating Frequency: 38 KHz • Modulated Frequency: 5 Hz • Power supply: 9 V • 4 IR emitters

  17. Infrared Beacon (Schematic)

  18. Infrared Beacon (Parts) • 2 x LM555 • 4 x IR LED • Resisters and Capacitors for modulation • Power Supply (9V Battery)

  19. Infrared Beacon (2 X LM555) • Supply Voltage • Min = 4.5 V Max = 16 V • Supply Current • @Vcc = 5V avg = 3 mA max = 5 mA • @Vcc = 15V avg =10 mA max = 15mA

  20. Infrared Beacon (2 X LM555) • Oscillating current - 0.6 mA • Both use astable mode - 5 kHz, 38 kHz • Frequency of Oscillation • Duty Cycle

  21. Infrared Beacon (Astable mode)

  22. Infrared Beacon (Signal Output)

  23. Infrared Beacon (modulation)

  24. Infrared Receiving System

  25. Infrared Receiving System (Mech.) • Use 36 degree separator - minimum motor step angle is 1.8 degree - using multiplier of 1.8 makes control more precise • Use black color for receiving system to minimize bouncing off signals • Insulating materials

  26. Infrared Receiving System • Infrared receiver module for remote control system • TSOP41 • Output active low • Low power consumption • High immunity against ambient light • Carrier frequency of 38 kHz

  27. Infrared Receiving System • TSOP41 Characteristics • Supply current • Min = 0 8 mA avg = 1.1 mA max = 1.5 mA • Supply Voltage • Min = 4.5 V Max = 5.5 V • Transmission distance • 35 m • Directivity • 45 degree

  28. Infrared Receiving System • 5 IR receivers are connected to PIC16F877 • PIC processes received signal • There are 4 outputs upon processing • S0 and S1 for direction of stepper motor • Clock output for driver • Range detector interrupt

  29. SPEED CONTROL SYSTEM Hardware: • EZ4 Ultrasonic Sensor • 16F877 PIC • CD74HCT4053E Analog MUX • 741 Op Amp • Other parts

  30. SPEED CONTROL SYSTEM(Schematic)

  31. SPEED CONTROL SYSTEM • EZ4 Ultrasonic Sensor • VOUT = (VCC/ 512)*distance (in) • Min distance = 6 in (58.6 mV) • Max distance = 254 in (2.48V) • Stable input: (6 in  7 ft) • Provides 3 simultaneous outputs (analog voltage, pulse width, and serial)

  32. SPEED CONTROL SYSTEM • Provides a narrower beam width than other sensors.

  33. SPEED CONTROL SYSTEM • Voltage Regulator • Input Voltage: 5V • Output Voltages: 2V, 3V & 5V • Analog Multiplexer • input Voltage: 4.5V – 5.5V • Max Current: 0.0018 A • 2 bit select input (from PIC)

  34. SPEED CONTROL SYSTEM • Non-inverting Voltage Amplifier (LM 741CN) • Max Output Current: 0.025 A • Power Consumption: 75 – 100 mW

  35. SPEED CONTROL SYSTEM • PIC Software • Analog input (255  5V) • 2 Threshold Values • VTH_LO = 1V  ~ … in • VTH_HI = 2V  ~ … in • Pseudo Code: VIN = read_adc(); if(VIN <= VTH_LO)  Low Speed else if(( VTH_HI > VIN > VTH_LO)  Medium Speed else if(VIN > VTH_HI)  High Speed

  36. SPEED CONTROL SYSTEM • Error Detection Algorithm • Read data and save it • Read data (2nd time), compare with previous one • If new value < old value, replace it by the new one. Else, Discard new value • Repeat 150 times to minimize error • Obstacle Detection • Unwanted transitions: • Low  High • High  Low • Solution: • Keep fan at the same speed for ~10 s • Change it to appropriate speed

  37. SPEED CONTROL SYSTEM (Measurements) • Power Supply: • VMAX = 5.05 V • Max Ripple = 15.9 mV • Freq = 13.46khz

  38. SPEED CONTROL SYSTEM (Measurements) • Current source Output w/ Fan On (Low Speed) • Max Ripple = 2.50 V • Freq. = 100khz • VMAX = 3.78 V

  39. Other Tests • To test the distance detection sensor we used different distances values and the out put of the voltage and compare it with real value from calculation formula • We test the receiver by sanding signal form different distances and angles whither we are receiving signal or not.

  40. Recommendation • Continuous IR signal at 38 kHz or more. • It should be used by one person with beacon • It should be used with less obstacle area. where the receiver and the beacon can communicate very well. • It should be used with a distance of 7 ft with no error.

  41. Strengths: Obstacle detection Ability to track the user within a long range Low power dissipation Weaknesses: Inconsistency of the stepper motor System is not 100% immune to external IR signals No distance detection while the fan is moving Not able to get stable data beyond 7ft. Improvements: Longer Ranger 360° Motor Rotation Smoother motor rotation Vertical Tracking Conclusions: Strengths, Weaknesses and improvements

  42. Credits • Professor Scott Carney • TA Tomasz Wojtaszek • Professor Yidnekakchew Mekonnen

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