Announcement

Collapse
No announcement yet.

Help in LabView 2012

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Help in LabView 2012

    Alright, so I'm still really new to this and last year i was just learning how to work everything in LabView. And now I've finally got my new version in for the Season and I'm looking at it wondering what the heck do I do with this?

    Could anyone give me a rundown on what i need to do to get started with a New program for the robot with this new year please?

  • #2
    Re: Help in LabView 2012

    The documentation here should help you get started:

    http://wpilib.screenstepslive.com/s/...abview-program

    You can also find a number of helpful "Getting Started" type resources on the NI FRC Community page.
    FIRST®
    FRC Robotics Engineer

    Comment


    • #3
      Re: Help in LabView 2012

      Alright, Thanks Kevin. I'll take a look at them here in a little bit. Thanks a lot.

      Comment


      • #4
        Re: Help in LabView 2012

        Alright so this is odd, when i look at what you have here i don't what i actually have on here. My start up screen for labview is completely different.

        Comment


        • #5
          Re: Help in LabView 2012

          Did you follow the directions for installing LabVIEW from http://wpilib.screenstepslive.com/s/...w-for-frc-2013 (Including installing all the updates)?
          Team 330 beta tester

          Comment


          • #6
            Re: Help in LabView 2012

            Alright I have everything fixed and working fine. thanks guys. Now i have one more question. Our robot is in the shape of a triangle this year. And i want to use omni wheels to drive our robot. How would i set it up to use only 2 wheels when driving forward and the third to turn while the other 2 move also?

            Robot would look something like this.
            http://www.alpha-crucis.com/2755-363...t-triangle.jpg
            Last edited by Dokusou; 01-23-2013, 12:07 AM.

            Comment


            • #7
              Re: Help in LabView 2012

              When using a platform like you have described, what you typically want to do is break the desired movement down into a vector and rotation, then resolve the components of the motion to a velocity for each wheel, then use the Motor Set Output VI to set the output for each motor individually (not using the Robot Drive Palette).

              Presentation about OmniDirectional Drives and Kinematics hosted by AndyMark
              Page specifically about physics of a 3 wheel platform
              FIRST®
              FRC Robotics Engineer

              Comment


              • #8
                Re: Help in LabView 2012

                so i should set up a specific run motor for each motor. So my y-axis will be for the back 2 motors while my x-axis will make all of them move in a specific motion correct? so per-say when i move my joystick forward the robot will start the back 2 engines while the front one will stay stationary and when i move the joystick around to turn it will follow the joystick with all the motors starting up?

                Second thing is in the picture that bot has 2 wheels set up for each motor. should we have a set up like that or is it not necessary?

                Comment


                • #9
                  Re: Help in LabView 2012

                  The method you are describing certainly would work, however you are limiting yourself well below the capabilities of the platform. The system you are describing allows the same two types of motion as a tank drive, forward/reverse and rotation. A platform with 3 omni wheels at 60 degree angles is capable of motion forward/back, left/right, and rotation as well as any combination of motion in these three degrees of freedom.

                  The math described in the two linked papers explains how to control a robot using this full capability by describing the linear translation as a vector (direction and magnitude of motion), typically from one joystick, and the rotation separately (twist of a joystick, throttle of a joystick, another joystick axis, etc.).

                  If you look closely at a pair of wheels in the picture you can see that they are slightly offset from each other so that the rollers of one align with the gaps of the other. From this information, you should be able to determine why this may be beneficial and evaluate if it is necessary for your wheels on your robot.
                  FIRST®
                  FRC Robotics Engineer

                  Comment


                  • #10
                    Re: Help in LabView 2012

                    Ok, i think i get what is being said here. But how would it allow us to move left and right with only 3 wheels? i would think you would need 4 wheels to accomplish that sort of movement. Where to move sideways you would have the wheels moving either towards or away from each other to achieve said movement. also how would you set this into the programming for labview? Would you have to set up the math in one of the motor vi's or is there a specific vi i would use?

                    Comment


                    • #11
                      Re: Help in LabView 2012

                      You can use the second page I linked to walk through what the wheel velocities look like for a straight sideways (in this case left, for right use a positive number) translational movement by setting v=(-1, 0) and w=0. Note that the dots used, for example in v•F0, refer to the dot product (the line beginning with "In two-dimensional space" may be the most helpful).

                      The most straightforward way of accomplishing this code in LabVIEW is likely to begin by writing out the math on paper, then translating that into LabVIEW code in your teleop VI. Once you have everything wired and functioning as you expect there, you can create a SubVI out of the math so you'll have a SubVI that takes your joystick values as inputs and provides the three wheel speeds as outputs.
                      FIRST®
                      FRC Robotics Engineer

                      Comment


                      • #12
                        Re: Help in LabView 2012

                        I found a holonomic vi in the functions pallet in labview. would using this work as well?

                        Comment


                        • #13
                          Re: Help in LabView 2012

                          Originally posted by Dokusou View Post
                          I found a holonomic vi in the functions pallet in labview. would using this work as well?
                          That VI is designed to work with mecanum or 4 wheel, 90 degree omni platforms and will not work with a three wheel omni platform.
                          FIRST®
                          FRC Robotics Engineer

                          Comment


                          • #14
                            Re: Help in LabView 2012

                            Oh ok. i was wondering what it was for. Thanks for clearing that up. I've got some of my teammates helping with the physics for this. Then i have to figure out how to put it into a vi to use.

                            Comment


                            • #15
                              Re: Help in LabView 2012

                              Alright so I believe i have everything set up for the programming for this year. Yet when i run the program and test it i get an issue of the fact that one of my motors jars every once in a while. It's like the motor is skipping a beat every 2 seconds or so. And when I'm running the program for our forward motion one of my motors doesn't even run that much. It starts for maybe 1.5 seconds and then shuts off. Is this a problem on my end with the programming or is the something wrong with my motors?

                              Comment

                              Working...
                              X