C

callen

Member

Last active 6 hours ago

  1. 13 hours ago
    Wed Jan 23 19:21:26 2019
    C callen posted in Multi angle linear Ball Puncher.

    Much easier than linear: rotate a gear on either the tilting part or the base. Connect the other part with a bar to a hole near the edge of the gear. Then as the gear rotates the bar pushes them apart or pulls them together. While using a second motor is pretty straight-forward this way, it isn't necessary. Since it's on a gear, if you want you can use sprockets to get a single motor rotating one way to work the firing mechanism and rotating the other way to tilt it.

  2. 3 days ago
    Sun Jan 20 15:41:46 2019
    C callen posted in 36 Inches.

    @sankeydd I still think I'm right, but I'm open to interpretation. I have posted a new Q&A to clarify.

    You know your interpretation allows a robot to measure nearly 6' across in every direction, right? (To be stable you'd probably have to limit it to 5' or so.) That robot would occupy nearly a quarter of the entire field.

    A is illegal. B is legal. (And it looks like they've now replied to your post to state that officially.)

    @sankeydd The robot would easily pass the test as long as the tool is held horizontally.

    This isn't the right way to use it, though it will suffice in many instances. I'll explain how to use it properly for the dimensions being analyzed. Look at the third image on this page:
    https://www.vexrobotics.com/276-5942.html
    You'll see the sizing tool should be held in a vertical plane. You can then spin it around a vertical axis so it measures different horizontal directions while remaining in a vertical plane. Check from one outer spot (meaning hold it against that spot while rotating around a vertical axis through that spot) and then translate it horizontally as needed to check other outer spots. If you can get it to go around the entire robot without touching, the robot is legal. If going around the entire robot this way cannot (not "isn't," but "cannot" - don't want unsteady hands to be a factor) be accomplished, it's illegal. Technically, the sizing tool should be infinitely thin, but that's not possible, and it's highly doubtful that will matter, as if it does matter a little bit of vibration or wobbling is likely to take that 35.99" robot to 36.01". Note, you might have to tilt the sizing tool a little while keeping the top bar horizontal if a robot is in the expansion zone and a tall piece blocks using a vertical plane.

  3. Sun Jan 20 14:27:44 2019

    @Unionjackjz1 Personally, my favorite screw length is custom screws made out of shafts. (I do this a lot and have many on my robots for many different reasons)

    What size screws do you end up with? I figure the diagonal is about the outer diameter of a #8 since we can use #8s as axles, so you'd likely be missing a lot if you go for #8. But maybe not too much? Since you can use commercially available nuts for size #4 and #6 screws, you've got plenty to work with.

  4. 4 days ago
    Sun Jan 20 05:11:56 2019
    C callen posted in 36 Inches.

    @sankeydd Why?

    Any horizontal dimension is under 36". The robot would easily pass the test as long as the tool is held horizontally. In order for it too not for you would have to twist the tool. That isn't horizontal.

    What that means is you measure from any point to any other point in the robot, and you ignore the vertical dimension, thus limiting yourself to any horizontal dimension. That circled number shows you a horizontal dimension measuring more than 36".

    If everyone were used to math/physics speech, we would talk about projections onto a plane, but what is written gets the same idea across to most people better.

    Edit: You're confounding measurement in any horizontal plane with measurement of any horizontal dimension.

  5. Sun Jan 20 04:23:04 2019
    C callen posted in 36 Inches.

    @TaranMayer I made a quick Inventor Sketch of the part of their robot I was talking about.

    The robot you drew is illegal.

  6. Sun Jan 20 04:22:25 2019
    C callen posted in 36 Inches.

    @AlexM_4478X I believe that the best way to visualize it is to look at the top of a robot as if it were a 2D image and if any point on the bot is >36 inches away from any other point on the robot then it is out of size

    Yes.

    @tabor473 That's a cylinder you just described.

    No, he did not just describe a cylinder. Look here for further explanation:
    https://en.wikipedia.org/wiki/Curve_of_constant_width

  7. Sat Jan 19 23:05:30 2019
    C callen posted in 36 Inches.

    @sankeydd It's also like a slinky in that it can shift as you go up vertically.

    I don't think that's the case. Otherwise you could make a robot that at 4" above the floor sticks out a foot beyond its 18" cube, at 5" above the floor sticks out a foot on a side 90 degrees off from the 4" one, etc. Then you've got a robot making a + shape measuring 42" along each line of the +. Make more of them at different angles, and occupy a circular projection with a 42" diameter. Alternatively, you could put an tower on one end with an arm that swings from its top, and when it first swings up it expands to 30" or so horizontally in addition to some upward, so that you can aim it up and away from the end of your robot with the tower; this would allow you to be in the expansion zone and contact the high flags on either end of the field.

  8. Sat Jan 19 21:01:05 2019
    C callen posted in 36 Inches.

    @TaranMayer At a recent tournament, a team was pushing the limit in terms of horizontal expansion. I brought it up, and the refs were adamant that it was a 36 inch square, not a cylinder like I thought. Which is it?

    If the refs said that, they're totally wrong. But yours isn't quite right, either. It is neither a square prism nor a cylinder. The link @TeamTX gave is good. The actual shape is closer to the cylinder idea, but the robot can extend outside of such a cylinder by a little bit while still remaining within the allowed expansion. Think of it more like a cross between a right cylinder and a right, equilateral, triangular prism. Look here for further explanation:
    https://en.wikipedia.org/wiki/Curve_of_constant_width

  9. Sat Jan 19 11:18:44 2019

    Usually in robot-config.h, just like in a non-competition file. You could do otherwise, but this helps keep things organized, leaving less clutter around the code you want to read.

  10. 5 days ago
    Fri Jan 18 18:42:22 2019
    C callen posted in Slowing Down V5 Motors.

    You have ".spin(fwd" instead of ".spin(vex::directionType::fwd" twice. Your arm and claw control if statements are outside of your user control function, which is a big problem and is what you've identified. I also note that you have two while(true) statements embedded within each other.

View more