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Lecture 1: Your Boe-Bot's Servo Motors. Presentation based on: "Robotics with the Boe-Bot" By Andy Lindsay Parallax, Inc. Presentation developed by: Martin A. Hebel Southern Illinois University Carbondale College of Applied Sciences and Arts Electronic Systems Technologies 7/6/04.
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Lecture 1: Your Boe-Bot's Servo Motors Presentation based on:"Robotics with the Boe-Bot" By Andy LindsayParallax, Inc Presentation developed by:Martin A. HebelSouthern Illinois University Carbondale College of Applied Sciences and Arts Electronic Systems Technologies 7/6/04
Continuous Rotation Servo • Used to provide drive motion for the Bot. • Standard Servo: Used for positioning, such as with RC airplanes rudder and flaps. • Continuous Rotation Servo: Rotate in a certain direction and speed.
Tracking Time • PAUSE is used to have the BASIC Stamp wait a short amount of time.PAUSE duration • Duration is in milliseconds (mS) or 1/1000th of a second, 1-65535PAUSE 1000
Repeating Actions • A DO….LOOP is used to repeat a sequence of commands.DO 'Commands to performLOOP
Servo Signals • Servos are controlled with a high pulse lasting a short time, and repeated. • The PULSOUT instruction can be used to send a short pulse.PULSOUT Pin, Duration • Pin: Pin device is connected to. • Duration: Time in 2S (microsecond) intervals, 1-65535. Microsecond = 1 millionth of a second.PULSOUT 12, 1PULSOUT 13, 2
Servo Signals • Typical servos require a pulse of 1mS to 2mS to define the direction/position. • A 20mS pause be between each pulse. • What values of PULSOUT are in the valid range?
Centering the Servos The pulse width defines the direction and speed of the servo motor. • 1000 – Maximum speed one direction • 750 – Stopped • 500 – Maximum speed other direction • Use the servo center programs to ensure it is stopped at 750.
Storing and Counting Values • Variable are used to store values • Variables much be declared prior to being used. Declaring a variable is giving it a name, and a size to hold.VariableName var Size
DEBUG ? is short hand to display the value of a variable or pin.
Counting and Controlling Repetitions • FOR…NEXT loops can be used to control the number of repetitions a segment of code takes.FOR StartValue TO EndValue {STEP StepValue}…NEXT
What will this code do? Freq VAR Word DO FOR Freq = 1000 to 5000 Step 100 DEBUG ? Freq FREQOUT 4, 100, Freq TOGGLE 12 TOGGLE 13NEXT LOOP
Testing Servos • To control the servo, send a series of pulses with values between 500 to 1000 (1-2mS) • Changing the value will change the direction and speed to some extent.
FOR…NEXT to Control Servo Run Time • The FOR…NEXT Loop can be used to control how long to drive a servo.