First fare 2010 lab-view overview

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FIRSTFare 2010LabVIEW Overview

Dennis C. Erickson ~ Senior Mentor for Teams 1510 and 2898

Daniel Bramblett ~ Team 1510Amy Wiegand ~ Team 2915

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Introduction

Working with National Instrument’sHardware and Software

Specifically:Software ~ LabVIEW

Hardware ~ cRIO

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Introduction

LabVIEWVI = Virtual Instrument

EW = Engineering Workstation

VI = Virtual Instrument or in other languages “Routine”, SubVI = Subroutine

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Why LabVIEW?•Graphical Interface (Not Text Based)•Dataflow (All inputs must be updated before VI – Virtual Instrument – executes)•Self Documenting (You know what the code does)

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Why LabVIEW?•Portable Code (VIs are easily reused)•Advanced set of diagnostic tools; probes, execution highlighting, error reporting, ability to surround the code with a “virtual world simulation environment” for testing.

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Why LabVIEW?•Perfectly tailored for NI hardware•Automatically handles multiple cores and threads•Easily compiles to RT (Real-time) Operating Systems and FPGA (Field Programmable Gate Arrays) used in the cRIO processor

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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.

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The FRC Topology

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The SoftwareUsed to Make Stuff Move

This section offers a brief short course on the language LabVIEW

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To start a new project

Launch LabVIEW to create a new project

http://decibel.ni.com/content/servlet/JiveServlet/showImage/102-4584-1-4424/4-28-2009+10-30-26+AM.png

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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:10.15.10.02

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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”.

http://decibel.ni.com/content/servlet/JiveServlet/showImage/102-4584-1-4427/4-28-2009+10-33-31+AM.png

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LabVIEW Functions - Front PanelSome example controls and indicators for the Front Panel

Numerical Controls and

Indicators

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Booleans

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Strings and Paths

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Arrays, Clusters,

Matrices and Dialog Boxes

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List Boxes, Tables and Trees

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2D, 3D Digital

Charts and Graphs and

Special Plots

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Rings and Enums

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LabVIEW Functions - DiagramSome example controls and indicators for the Diagram

Structures

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Arrays

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Structures, Classes and Variants

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Numerics, Booleans and Files

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Hundreds of other functions

Timing, Dialog Boxes, Waveforms, etc, etc

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An Example of Virtual TestingTesting the Joystick Power Function VI

Task: 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)m

Where:

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)

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The HardwareUsed to Move Stuff

This discussion touches on the following principle areas:

•The cRIO hardware (The Brain)•The Sensors, Motors and Actuators that can be used •The DS Drive Station (Link from the User to the robot’s brain)

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cRIO HardwarecRIO – Compact Real-time Input/Output

A 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.

A fully populated cRIO example

http://decibel.ni.com/content/servlet/JiveServlet/showImage/102-1750-4-1356/cRIO.jpg

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cRIO HardwareReal-time operating system

FPGA – Field Programmable Gate Arraylocated under the cRIO chassis

cRIO connected to a Laptop

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How to Set up a Virtual Test Environment

The following Example code shows how to create an environment to test and calibrate VI modules. In this case we are testing the Camera Servo motors

First Initialize the test (note the “Data Dependency” wire)

Next 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

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

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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.

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State Diagrams

The 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

State diagrams are extremely useful in creating small or large applications. Since LabVIEW is a DataFlow language, this approach adds to the robustness of the application

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State Diagrams

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

These slides show a typical State Diagram that tests camera servos. Note the inputs from the joystick and a smoothing control to test filtering.

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State DiagramsOne of the interesting features of the State Diagram is confining the application code to one screen, thus self documenting codeFinally, 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

Questions?

Dennis C. Erickson - [email protected]

Technology

First fare 2010 lab-view overview