ROBOTC for VEX On-Site Professional Development

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ROBOTC for VEXOn-Site Professional Development
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Troubleshooting

• Student My robot wont stop turning.

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Troubleshooting

• Student I used the auto straightening code, and
  it compiles, it isnt working, its just being
  weird.

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Troubleshooting

• Student One of my encoders is counting down even
  though its spinning forward.

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Troubleshooting

• Student My code wont compile.

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Radio Control
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Radio Control

• An out-of-box VEX Microcontroller comes with
  basic built-in Radio Control functionality
• The Radio Control Transmitter can be configured
  to allow some customization of that built-in
  functionality
• Still very limited customizability and
  usefulness!
• The ROBOTC firmware enables full customization of
  how the Radio Control Transmitter signals
  controls the VEX
• By default ROBOTC turns off reception from the
  transmitter to save battery life during
  autonomous programming
• One line of code turns it back on

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Radio Control

• One Transmitter continuously sends out 6 separate
  values over 6 separate channels
• Values range from -127 to 127
• Doesnt something else have values that range
  from -127 to 127?
• The crystal number must match on the
  transmitter and receiver
• The crystal is what controls the frequency of the
  transmission
• One transmitter can control multiple robots, so
  be careful in your classrooms
• 13 different crystals/frequencies are available

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Radio Control Reset

• Since the Radio Control Transmitter can be
  configured, theres the possibility that its
  configured inappropriately for our purposes.
• Watch the Radio Control Setup and Values and Axes
  (Part 1) Videos in TRC4V, found in Radio Control
  gt Control Mapping
• Be sure to follow along with the Radio Control
  Setup Video!

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Radio Control Signals
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Radio Control

• Direct Value Mapping
• Values from the transmitter are directly used to
  control the motors (11 ratio)
• Program Flow Tracing
• Radio Control with Wait States
• Radio Control with a Loop (real-time control)
• Indirect Value Mapping
• Values from the transmitter are modified before
  being used to control motors
• Can make the robot easier to control
• Appropriate in situations that require more
  delicate movements
• Notice the robot reads the right side of the
  equal sign first

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Advanced Radio Control

• Attach the Arm!
• Use the Transmitter buttons to control the arm
• The Transmitter buttons send values of -127, 0,
  or 127
• Would direct mapping or indirect mapping be most
  appropriate for controlling the arm? Why?
• More loop control please?
• Is remote controlling the robot forever always
  appropriate?
• Question Where would the wait statement go if we
  wanted the robot to be remote controlled for a
  controlled amount of time?
• Answer Nowhere! We need something else.
• Solution Timers
• Can be thought of as internal stopwatches (4
  available)
• Like encoders, timers should be cleared anytime
  before they are used
• Watch where you clear them!

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Advanced Radio Control

• Wasting Time?
• The time it takes to turn on the VEX and start
  Radio Control is wasted time.
• Could we make the robot wait to start its timer
  until we were ready? Any ideas?
• Wait for a Transmitter Button press
• The robot wont start the timer until we say so
• The robot also cant move until we says so
• Program Flow Trace
• Could this idea also be used to make a more
  friendly start button on a non-radio controlled
  robot?
• Other ideas of how to improve radio control?
• Use the buttons to initiate common actions
• Turn 90 degrees, move straight forward, ect

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Advanced Radio Control

• Assigning a function to a button press
• Auto pickup

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Radio Control Challenges

• TRC4V Videos (recommended)
• Watch remaining Control Mapping videos 3-5
• Race to the Finish
• Remember to Journal
• Remember to Pseudocode
• Shut off your transmitter when its not in use!
• Drastically saves the battery life (and your
  ears)
• The transmitter is always transmitting, even if
  the robot isnt on

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Advanced Radio Control Challenges

• TRC4V Videos (recommended)
• Watch remaining Radio Control Videos (Control
  Mapping, Timers, Buttons sections)
• Minefield Level 1 Challenge
• Remember to Pseudocode
• Remember to Journal
• RoboDunk
• First try it
• Tele-Operated,
• then Autonomously

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Competition Templates

• VEX Competitions have a Field Management System
  in place
• Manages when robots are enabled/disabled
• Determines whether the robots are in
  autonomous/tele-operated mode
• A Competition Template is available that can be
  programmed in to work with the Field Management
  System
• Contains autonomous and tele-operated sections
• Found in the Sample Programs gt Competition folder

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Troubleshooting

• Student My loop should only be running for 1
  minute, but it never stops.

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Touch Sensors

• Touch Sensor Check
• Front sensor plugged into A/D 1
• Rear Sensor plugged into A/D 4
• How they work
• Digital sensor - Pressed or Released
• Watch out for bouncing
• Two Types
• Limit Switches on Squarebot 3.0
• Bumper Switches
• Setting them up
• ROBOTC Motors and Sensors Setup window
• Using them
• The SensorValue command

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Touch Sensors

• Start Button
• Remember back to how we used the Transmitter
  button to start the timer portion of the program.
  How would we implement the same thing with the
  limit switch?
• Fine-tuned arm control
• Using the limit switches to tell the robot when
  it has reached its minimum and maximum points

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Touch Sensor Challenges

• Quick-tap Challenge
• Incorporating Sensors, Variables, Loops, If
  Statements, Timers, Boolean Logic, Pseudocoding,
  and FUN all into one activity
• Addition Subtraction
• Everything you just learned, but with another
  twist

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The Ultrasonic Rangefinder

• Ultrasonic Rangefinder Check
• Input wire plugged into A/D Port 5
• Output wire plugged into INT Port 1
• How they work
• Similar to how bats and submarines work
• Digital sensor but returns distance values
  between 0 255
• (Can also return values of -1 or -2 if used
  improperly)
• Resolution is in inches (a value of 5 5 inches
  away)
• Setting them up
• ROBOTC Motors and Sensors Setup window
• Using them
• Be careful not to use them immediately as your
  program starts they take time to initialize and
  will return negative values
• The SensorValue command

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The Ultrasonic Rangefinder

• Forward until Near
• Move forward until the robot is near an object,
  then stop
• Thresholds
• Automatic Pick-up
• Forward until Near picking up the mine
• Assign to a button

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Sensor Challenges

• TRC4V Videos (recommended)
• Watch Remaining Sensing Section Videos
• Minefield Level 2 Challenge
• Remember to Pseudocode
• Remember to Journal
• The two are not mutually exclusive!
• The Speed of Sound
• Sonic Scanner Level 2 (Start)

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Potentiometers

• Potentiometer Check
• Sensor plugged into A/D 1
• How they work
• Analog sensor
• Measures rotation of a shaft between 0 and 265
  degrees
• Returns values 0 1023
• Internal mechanical stop
• Setting them up
• ROBOTC Motors and Sensors Setup window
• Using Analog and Digital Sensors
• Using them
• The SensorValue command

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Potentiometers

• Variable Speed Program
• Use the rotation of the potentiometer to control
  how fast the robots motors spin
• Arm Control
• Instead of using the limit switches, use the
  potentiometer to control how far the arm is
  allowed to swing up and down

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Servo Motors

• Very similar in appearance to the normal motor
• Very different in operation
• Rotates between 0 and 120 degrees
• Where the motor is set to a power value the
  servo is set to a position value
• -127 0 degrees, 0 60 degrees, 127 120
  degrees, ect
• Servo motors are programmed exactly the same way
  as normal motors in ROBOTC, so the programmer
  must know the hardware and intent

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Pneumatics

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Pneumatics

• Solenoids operate as Digital Outputs
• Are plugged into Analog/Digital Ports
• Are set to open by setting them to 1
• Are set to close by setting them back to 0
• Demo in ROBOTC

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End of Day Challenge

• Minefield Level 2
• Incorporate an autonomous scoring behavior before
  your tele-operated code begins
• One mine should always be in the same place,
  near the goal