This document provides an overview of LabVIEW and how it is used for FIRST robotics competitions: 1. LabVIEW is a graphical programming language used with National Instruments hardware like the cRIO for robot control. Programs in LabVIEW are called VIs (virtual instruments). 2. The cRIO is a programmable automation controller that serves as the robot's brain. It uses an FPGA and can interface with sensors, motors, and other hardware. 3. LabVIEW is well-suited for robotics as it is graphical, supports real-time control, and integrates tightly with NI hardware. Programs can be tested virtually before deployment to the robot.

1. FIRSTFare 2010LabVIEW OverviewDennis C. Erickson ~ Senior Mentor for Teams 1510 and 2898Daniel Bramblett ~ Team 1510Amy Wiegand ~ Team 29151

2. IntroductionWorking with National Instrument’sHardware and SoftwareSpecifically:Software ~ LabVIEWHardware ~ cRIO2

3. IntroductionLabVIEWVI = Virtual InstrumentEW = Engineering WorkstationVI = Virtual Instrument or in other languages “Routine”, SubVI = Subroutine3

4. Why LabVIEW?Graphical Interface (Not Text Based)

5. Dataflow (All inputs must be updated before VI – Virtual Instrument – executes)

6. Self Documenting (You know what the code does)4

7. Why LabVIEW?Portable Code (VIs are easily reused)

8. Advanced set of diagnostic tools; probes, execution highlighting, error reporting, ability to surround the code with a “virtual world simulation environment” for testing.5

9. Why LabVIEW?Perfectly tailored for NI hardware

10. Automatically handles multiple cores and threads

11. Easily compiles to RT (Real-time) Operating Systems and FPGA (Field Programmable Gate Arrays) used in the cRIO processor6

12. Why Do More Than Necessary to Win the Contest?While it is entirely possible to win a contest with a robot that is “bare bones” the better goal is to learn how to do things along the way that may or may not be used.7

13. The FRC Topology8

14. The SoftwareUsed to Make Stuff MoveThis section offers a brief short course on the language LabVIEW9

15. To start a new projectLaunch LabVIEW to create a new project10

16. To start a new projectName your project .You might for example use your team name and year in the name:i.e., “Team 1510 for 2010 Robot Project”Be sure that you enter your team IP in the following format:10.15.10.0211

17. To start a new projectAdding a VI to your project:If its new, then right-click to “VI” and select and name it.If adding an existing one select the menu item “Add”.12

18. LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel13Numerical Controls and Indicators

19. LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel14Booleans

20. LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel15Strings and Paths

21. LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel16Arrays, Clusters, Matrices and Dialog Boxes

22. LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel17List Boxes, Tables and Trees

23. LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel182D, 3D Digital Charts and Graphs and Special Plots

24. LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel19Rings and Enums

25. LabVIEW Functions - DiagramSome example controls and indicators for the Diagram20Structures

26. LabVIEW Functions - DiagramSome example controls and indicators for the Diagram21Arrays

27. LabVIEW Functions - DiagramSome example controls and indicators for the Diagram22Structures, Classes and Variants

28. LabVIEW Functions - DiagramSome example controls and indicators for the Diagram23Numerics, Booleans and Files

29. LabVIEW Functions - DiagramSome example controls and indicators for the Diagram24Timing, Dialog Boxes, Waveforms, etc, etcHundreds of other functions

30. An Example of Virtual TestingTesting the Joystick Power Function VI25Task: Test the VI with 1000 simulated Joystick positions from 0 to +1 to 0 to -1 (White Line) and create 9 plots with the following function:Plotn = (motor speed)mWhere:Plotn = a series of plots(9 total)Motor speed = voltage input to the motor (from 1 to -1)m = power function (use to alter the forward sensitivity of the Joystick)

31. The HardwareUsed to Move StuffThis discussion touches on the following principle areas:The cRIO hardware (The Brain)

32. The Sensors, Motors and Actuators that can be used

33. The DS Drive Station (Link from the User to the robot’s brain)26

34. cRIO HardwarecRIO – Compact Real-time Input/OutputA PAC (Programmable Automation Controller) which is an industrial controller that is used in advanced systems incorporating software capabilities such as control, communication, data logging, and signal processing requiring rugged hardware performing logic, motion, process control, and vision. For FIRST applications, ideal for robot building.27A fully populated cRIO example

35. cRIO HardwareReal-time operating system28cRIO connected to a LaptopFPGA – Field Programmable Gate Arraylocated under the cRIO chassis

36. How to Set up a Virtual Test EnvironmentThe following Example code shows how to create an environment to test and calibrate VI modules. In this case we are testing the Camera Servo motors29Next run the test in a While loop. Note the Loop Sweep constant which defines the loop cycle (20ms). Here the loop is stopped using the Stop Test? command First Initialize the test (note the “Data Dependency” wire)Finally End the test by closing all references, etc. Again note the Data Dependency and use of a Frame structure as the SubVI has no wired input to use

37. State DiagramsThe following slides start with a State Chart to show what the State Diagram will do. The next slides show the State Diagram created.30

38. State Diagrams31State diagrams are extremely useful in creating small or large applications. Since LabVIEW is a DataFlow language, this approach adds to the robustness of the applicationThe Application starts by selecting the Initialize Test State (case). Note that we check for errors and if the Stop Test? Button is pressed. Note that the Enum (far left constant control) has 3 possible states; Initialize Test, Run Test and End Test

39. State Diagrams32These slides show a typical State Diagram that tests camera servos. Note the inputs from the joystick and a smoothing control to test filtering.Next if no errors, run the While loop until an error happens or the Stop Test? Button is pressed the go to the next State

40. State DiagramsOne of the interesting features of the State Diagram is confining the application code to one screen, thus self documenting code33Finally, there has been an error or the Stop Test? Button has been pressed so end the test by closing references, etc. Note that now the Boolean constant is now TRUE which stops the loop

41. Questions?Dennis C. Erickson - dcerickson1@comcast.net