ROBOTC for VEX On-Site Professional Development

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ROBOTC for VEXOn-Site Professional Development
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Squarebot 3.0

• Features
• 2 Driving Motors
• 1 Arm Motor
• Ultrasonic Rangefinder
• Shaft Encoders
• Touch Sensors
• RF Receiver
• VEX PIC

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VEX Microcontroller

• Brains of the robot
• Controls up to 8 motors and/or servos
• Receives feedback from up to 16 analog and/or
  digital sensors
• Can run Autonomously, Tele-operated, or a
  combination of the two
• Stores and executes one program at a time
  (typically)
• Can be used to control pneumatic actuators, LCD
  screens

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ROBOTC

• Developed specifically with teachers and
  classrooms in mind
• Complete programming solution for the VEX plus
  several other robot platforms
• Only programming language for the VEX with a
  real-time debugger
• Youll learn more about this feature later on
• Very similar to industry-standard C programming
• ROBOTC demonstration

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Teaching ROBOTC for IFI VEX Robots (TRC4V)

• 40 tutorial videos
• 275 pages of printable guides aligned to the
  videos
• 50 pages of supplementary helper guides
• 35 programming challenges
• Freely available at www.robotc.net

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Student-Paced Instruction

• Everyone learns different things at different
  paces
• Everyone MUST move at a different pace
• Going too fast results in failure and frustration
• Going too slow results in loss of attention (i.e.
  future failure)
• TRC4V can be used as a teaching aid
• One instructor cant teach at 20 different paces
  simultaneously
• One instructor plus 20 computers can

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A Tale of Two Softwares

• Use TRC4V to update the VEX firmware in ROBOTC
  http//www.robotc.net/vex_full/

ROBOTC for IFI(the GREEN icon)
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Firmware Check

• What is Firmware?
• Does the robot need to be turned on in order to
  transfer firmware?
• What needs to happen after the firmware transfer
  is complete, before doing any programming?

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Get Your Motors Running

• Motor Check
• Right Motor is plugged into MOTORS 2
• Left Motor is plugged into MOTORS 3
• Download Sample Program
• Training Samples gt Motor Port 3 Forward
• Basic Movements
• Forward / Reverse
• Swing Turns / Point Turns
• Manual Adjustments

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Programming Discussion

• The Challenge The Labyrinth
• The Solution ???
• The Programmers (your) Role
• Plan out the robots path / actions -
  Pseudocoding
• Understanding Program Flow and Behavior Based
  Programming
• Translate the Pseudocode into real code
• The Robots role
• To carry out your instructions!
• The Solution Programmer and Robot working
  together, fulfilling their roles
• True for all robotic challenges!

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Movement Challenges

• TRC4V Videos (recommended)
• Watch videos in the Fundamentals Section
• Watch videos in the Movement Section
• The Labyrinth
• Remember to Pseudocode
• Turning Investigation
• Remember to Pseudocode
• Consider what you can teach with a robot
• Sentry Simulation

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Review Questions

• Why does the robot spin if both motors are set to
  the same power level?
• What are valid power levels on the VEX?
• All commands that we want the robot to follow
  must be in _________?
• Each command must end with a(n) _________?

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Troubleshooting

• Student I want my robot to move forward, then
  turn. I had it moving forward, and added the
  turn. Now its turning, then moving forward.

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Troubleshooting

• Student I want my robot to move forward, then
  reverse. I had it moving forward, and added the
  reverse, but it never actually backs up.

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Troubleshooting

• Student My code compiles, but ROBOTC gives me an
  error when I try to download it to the robot.
• Check
• Is the robot turned on and sufficiently powered?
  (blinking green light)
• Is the robot connected to the computer?
• Is the correct platform type selected in ROBOTC?
• Is the correct port selected in ROBOTC?
• Has the driver for the programming cable been
  installed?
• Has the firmware been loaded on the VEX?
• Does the Master Firmware need re-downloaded?
• Is another ROBOTC window open, using the debugger
  windows?

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Shaft Encoders
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Shaft Encoders

• How they work
• Digital counting sensor
• Capabilities and Resolution
• Quadrature vs. Standard
• Setting them up
• ROBOTC Motors and Sensors Setup window
• Using them
• The SensorValue command
• The while() loop

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Better Movement with Encoders

• Forward for a specific distance
• Advantages / Disadvantages
• Reverse for a specific distance
• Advantages / Disadvantages
• Clearing the encoder
• Turning
• Advantages / Disadvantages

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Variables

• What is a variable?
• Types of variables
• Integer, Boolean, Character
• Usage rules
• Capitalization, Spelling, Availability
• Usefulness
• Can store data to be manipulated by your robot
• Can improve the readability and expandability of
  your programs

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The M in STEM

• Current method for moving the robot
• Guess-and-check - true for wait states and
  encoder rotations
• Do it smarter!
• We can measure the distance for the robot to
  travel
• We can measure the circumference of the wheel
• We know 360 degrees 1 wheel rotation
• Ideas?
• Use your idea to move forward and reverse
• Discuss how well your ideas worked
• Discuss Turning
• Is having the robot turn 90 degrees the same as
  having the encoder turn 90 degrees? Why or why
  not?

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The M in STEM

• How did you solve the math problem?
• Some common methods
• Scale Factor (Scaling multiples of a known
  quantity)
• Rate Unit Ratio ( of X in a single Y, times the
  number of Ys)
• Rate relationship
• Find degrees/1in, then multiply that rate by the
  total
• What about degrees per floor-line?
• Rate Raw Ratio ( of X per of Y, times the
  number of Ys)
• Find 360degrees/8.6in, then multiply that rate by
  the total
• Direct Proportion (Traditional ratio equation)
• 8.6 in 24 in 360 deg X deg
• Solved mechanically using cross-multiplication
• Solved algebraically as a Linear Equation of One
  Variable

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The M in STEM

• Did you all solve the same problem?
• Did you all get the same answer?
• Did you all use the same method?

• Did it matter?

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The M in STEM

• Did we do something demonstrably useful?
• NCTM Numbers and Operations Standards (6-8)
• Select appropriate methods and tools for
  computing with fractions and decimals from among
  mental computation, estimation, calculators or
  computers, and paper and pencil, depending on the
  situation, and apply the selected methods
• Develop and analyze algorithms for computing with
  fractions, decimals, and integers and develop
  fluency in their use
• Develop and use strategies to estimate the
  results of rational-number computations and judge
  the reasonableness of the results
• Develop, analyze, and explain methods for solving
  problems involving proportions, such as scaling
  and finding equivalent ratios.

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The M in STEM

• Did we do something demonstrably useful?
• NCTM Algebra Standards (6-8)
• Represent, analyze, and generalize a variety of
  patterns with tables, graphs, words, and, when
  possible, symbolic rules
• Relate and compare different forms of
  representation for a relationship
• Model and solve contextualized problems using
  various representations, such as graphs, tables,
  and equations
• NCTM Geometry Standards (6-8)
• Understand both metric and customary systems of
  measurement
• Solve problems involving scale factors, using
  ratio and proportion

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The M in STEM

• Did we do something demonstrably useful?
• NCTM Problem Solving Standards (6-8)
• Build new mathematical knowledge through problem
  solving
• Solve problems that arise in mathematics and in
  other contexts
• Apply and adapt a variety of appropriate
  strategies to solve problems
• Monitor and reflect on the process of
  mathematical problem solving
• NCTM Communication Standards (6-8)
• Organize and consolidate their mathematical
  thinking through communication
• Communicate their mathematical thinking
  coherently and clearly to peers, teachers, and
  others
• Analyze and evaluate the mathematical thinking
  and strategies of others
• Use the language of mathematics to express
  mathematical ideas precisely
• NCTM Connections Standards (6-8)
• Recognize and apply mathematics in contexts
  outside of mathematics

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Everyone is a Math Teacher

• How did you solve the math problem?
• Many STEM teachers will not be teaching in Math
  class, yet Math is clearly what they are teaching
• Make the math explicit dont waste the
  opportunity!
• Embrace multiple methods of solving the same
  problem students need more tools at their
  disposal, not conflicting information about which
  ones are better than others (none are, use what
  works!)

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Moving Straight

• Even with the shaft encoders, the robot still
  veers (probably).
• Does it have to? Discuss.
• By comparing the values of the two encoders, we
  should be able to tell which side is falling
  behind, and adjust motor power in real time!
• Watch the Automated Straightening Video in TRC4V

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Moving Straight Check

• How will the robot be able to tell which side is
  falling behind?
• How will the robot be able to adjust its motor
  power?
• Will adjusting the motor power once solve the
  problem? Why or why not?
• Pseudocode the Moving Straight Code!
• Translate the Pseudocode into real code.
• Test! Did you notice any improvement?
• How does the program flow through the code?

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Moving Straight Discussion

• The automatic moving straight code works great,
  but imagine using it to solve the Labyrinth.
• Automatic moving straight code 20 lines
• 5 Forward movements needed for the Maze
• 5 x 20 100 Lines of code!
• And that doesnt include turns or other commands!
• Notice that the moving straight code is mostly
  comprised of the same exact code, over and over.
• What if there were a way to reuse the same set of
  code?
• There is Functions!

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Functions

• Functions are used to group together several
  lines of code, which can then be referenced many
  times in task main, or even other functions.
• Convenient uses in the Labyrinth
• Moving Straight
• Turning 90 Degrees Left
• Turning 90 Degrees Right
• Creating Functions
• Simplified Example Moving Forward
• Function Header (Part1 The name of the
  function)
• Function Definition (Part 2 The code that goes
  with the function)
• Using Functions
• Function Call (Part 3 Where you want the
  function code to run)

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Advanced Functions

• What about the very similar lines of code that go
  with the automatically moving straight code? Is
  there a way to include those lines in the
  function?
• Whats different each time we use the code?
• The number of degrees for the distance of the
  straight movement!
• What programming tool do we have that lets us
  store numbers in our code?
• Variables! Functions allow use for a special kind
  of variable, called a Parameter.
• Parameters allow you to pass values into
  functions to account for small differences, like
  the number of degrees to move forward.

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Advanced Movement Challenges

• TRC4V Videos (recommended)
• Watch Behaviors and Functions Parts 1 2, found
  in Sensing gt Autonomy (Encoders)
• The Labyrinth Revisited
• Remember to Pseudocode
• Seeing the Difference
• Remember to Pseudocode