Download Advanced Arduino – Robot – Presentation

Microprocessors Tutorial 2:
Arduino Robotics
Agenda
1. Robot Anatomy
2. Sensor Review
3. PWM
4. MAKE: Fade
5. Motors
6. H Bridge
7. Robot Control library
8. MAKE: Robot react
9. Challenge: Solve Maze
10. Links
Robot Anatomy
Robot Anatomy
Sensor Review
• Analog Arduino mapping: 0-5V  0-1023
• 3 connections: V+, pin, GND
• Serial Monitor:
• Use Serial.begin(9600) to start communication
• Use custom function serialOutputValue(“msg”, value)
to see sensor value in serial monitor
• This robot has IR range sensor:
Outputs 0.0 - 2.6V (0-600 in Arduino)
Peaks at 15cm, farther objects create lower voltage
BUT code inverts relationship!
Pulse Width Modulation
• Duty cycle = percentage of time signal is positive in
square wave
• Min-Max voltage: 0 – 5v
Min-Max Arduino mapping: 0 – 255
• PWM pins have a ~ on Arduino
10% average
50% average
90% average
Make: Fade
• Use analogWrite(pin, value) to fade light on/off
using for loop to vary value
• Remember PWM range is 0-255
• Recall LED connection:
long leg = positive
small resistor in series necessary
Challenge: Fade Increments
• Use PWM to
1. fade the led from 0 to full in 5 seconds,
2. hold for 2 secs,
3. fade back down in 7 seconds.
• Then each loop would do it faster and faster or
brighter and brighter!
Motors
• They draw more current than USB/Arduino can supply
(40mA per pin, 200mA in total)
so need another power supply: batteries
• Current through in 1 direction turns them in 1 direction
• More voltage = More speed, how to control voltage?
• Use electronically controlled switch (transistor)
between motor and batteries
• Use PWM pin to control switch
• Motors in this robot run on 4.5-7.0V
and have a peak current of 1A.
H- Bridge
• Used to make 1 motor turn in either direction by
directing current
• use 4 switches controlled by 2 signals
H- Bridge
• The IC we will use (SN754410N) has 2 H-Bridges to
control 2 motors
• PWM is used here at the enable pin to control speed
A
CHALLENGE: solve the maze!
Create your own algorithm to beat the maze using
Example 0: Template
Or start from our other example codes
Example 4, 5, 6
Useful Links
Arduino Examples
http://arduino.cc/en/Tutorial/HomePage
MAKE projects
http://makezine.com/arduino/
http://makezine.com/category/electronics/arduino/?post_type=pr
ojects
Jeremy Blum Tutorials (#5: motors and transistors)
http://www.jeremyblum.com/category/arduino-tutorials/
Questions? Comments? Suggestions?
[email protected]
ieee.concordia.ca