Mobile Goal Manipulation

For those of us who are choosing to build an internal stacker, that is a robot who carries around a mobile goal and stacks cones on top of it, how are you planning on manipulating the mobile goals?

Some ideas I’ve run across, or come up with:

  • Mobile Goals fit perfectly into C-Channels
  • You have to have two degrees of motion: lateral and vertical, to get the goal into the 20pt zone
  • In VRC 2010-2011 Round Up, teams were also challenged with stacking objects on mobile goals, which were heavier, and often lifted them into a zone. See Team 44’s reveal for more information
  • It might be best to have some sort of mechanism which extends out to manipulate the goals, similar to @antichamber 's design
  • Because internal stackers differentiate cone lift and mobile base lift, both have to be fairly compact. To have a rd4b, you’d probably need a manipulator that’s close to the ground, and one that doesn’t go very high
  • The manipulator must be in a position where depositing cones is easy


Edit: Alternative Tip - use a really wide DR4B for an internal stacker.

The problem with that is that is does not permit an extensible distance between the base, and your stacks will be quite short

My idea for the DR4B still gets the height, but tries to keep the width so you could stack 8 to 9 cones internally without knocking them over with the midsection. We are short on aluminium C channels though, so it has been on hold. Just got our game pieces today though, so might try it out soon.

This is a little hard to visualize. Are you stacking your cones inside your RD4B?

Well, the stacker idea isn’t that difficult to think of, is it. You have a claw that has only a vertical movement ability up or down. It grabs a cone, moves up, robot drives into a cone, claw moves down and stacks, grabs the lower cone, lift up, and repeat. This can be done with a little bit of automated programming and it would be as simple as drive into the cone - press a button. This idea can be achieved relatively easily, and I see the functionality would probably be pretty robust. See 2016 FIRST game for some inspiration. And the entire assembly can be lifted up to stack cones on stationary goals. (I would strongly advocate for a nice Curahee quality elevator as lift for some nostalgia.) Only challenge is to get it to easily and reliably pick up cones near walls. But I presume this is not the challenge.

The challenge is, in addition to this, how do you fit some mechanism below or around it to manipulate the goal into the zone? As you’ve said it perfectly, two degrees of movement are required. Forward and vertical.

Well, I can’t give you an exact description of a mechanism yet, because whatever’s in my head I’m pretty sure is just some initial complicated crude designs that will be streamlined as I think more. But three comments:

  1. I’d probably never never ever even think of that Green Egg way of doing this. I would not recommend that to any regular high school team that have ~average time resource. It’s mind explodingly fascinating and awesome, but based on my experience, the design evolution every season has always found very simple methods to solve very daunting challenges, and I wouldn’t go that far at all.
  2. Commenting off your “two degrees of movement” conclusion, I think it’s absolutely possible and necessary to combine your “vertical” and “forward” movement into one movement, if you have to go that thinking route.
  3. You could chop off the front end of your base such that your manipulators are completely hanging in front. So after you lift up your mobile goal and drive in front of the bar, it will already be hanging right above 20 pt zone. But this would possibly raise issues in driving, tipping and robot pushing.

Some comments for right now that will definitely prove obsolete in the matter of days. Keep the discussion going. I envy you guys who are able to build bots… I’m too old and I can’t do awesome vex, partially because of money and college peer pressure or what not. lol.

Yes, essentially. Once we pick up a mobile base, it will sit centered on the base of the robot while we stack cones on it. Then I have an ejector idea since cones don’t seem to fall off a base if you keep it under 10 high and the drop under a few inches.

You could do some sort of elliptical movement. Like this.

However, if I am reading this correctly, you are suggesting that your claw picks up a cone, places it on another, then lifts that pair of cones to place on another cone, then picks up the trio of cones to place on another, and so on? If that is what you are suggesting, that is illegal. You may only manipulate one cone at a time, unless the cones are “stacked” and the game definition of “stacked” means that they are on a mobile goal. Therefore, you cannot lift a group of nested cones that are not on a mobile goal.

You’re right. I didn’t pay attention to the definition of “Stacked”. I do apologize for previous potentially misleading comments. Please carry on the discussion.
On a side note, I imagined teams were gonna stack cones inside robots up to epic heights and score them at last moments. Well that’s never gonna happen. Game instantly appeared a lot more dull to me. :frowning:
I’d strongly recommend an active rather than passive cone manipulator, both intake and release. If a manipulator is gonna be used so often in a game, I would spare some good motors to make it reliable.