# Gateway Lifts

Hello,

I wanted to start this thread becuase i havent seen a thread that shares all the possibilities on how we can expand,reach,or slide to reach past the 30" what is needed for this years game gateway. I want to think outside the box on all the possible ways we can reach 30". Even if its similar to others or even rare.

Thanks

A few come off the top of my head.

Two to three stage rack and pinion.
Continuous chain loop two stage elevator
7 (i think it was a 7?) bar linkage
Arm pivot
scissor lift

We are using a 6 bar linkage for our intake, 30" can just be reached with a 4 bar though, or even a single arm if you don’t mind it rotating or rotating is an advantage. Your intake could even help you reach to 30" if it moved the elements along the arm as then you can easily reach 30" with just a rotating intake.

If you didn’t understand that i will explain each of them more in detail

The college competition had four 30" goals last season. We did a little bit of math and found out that if you use close to the 18" height and length, you can reach 30 with just a four -linkage. That does pose a few issues, so KTOR wound up using a two stage lift. The first stage for both robots was a linear lift that gave us quite a bit of travel, can’t remember exactly how much, but it got us most of the way there. Our snorkel robot had a short pivot arm as the second stage, and could score rings comfortable from about 34". We wanted to be able to descore from the 30" posts with our claw bot, so a four-bar was attached to the top of the linear lift, giving us a staggering 40some inches of scoring height. I’ll see if I can dig out some pictures and post them in the next few days.

4 bar lifts would be the easiest option, but it would be very hard to have a stable robot with this lift. I would saw the stablest lifts would be: scissor lifts, rack and pinion lifts, and the Titan lift. ( i forgot the name of that chain lift )

Are you referring to Supersonics bot? Its not a 7 bar or anything fancy like that its simply an Extended 4 bar.

In fact I think thats a good name to call that (if I am thinking of what you meant be “7 bar”)

Can we start calling this the “Extended 4-Bar”?

I think how tall you lift matters directly upon your intake. If you can score off of the top of the robot or intake, then you only need to life ~18in. However, if you score from the bottom of the robot or intake, then you have to lift ~30-36in. Also you might want to lift higher if you want to be capable of descoring objects above the top plane of the goal.

I think if you need to lift ~30-36in, using only 2 stages with a rack and pinion or a chain lift will be tough. While it is possible to lift up to 33-34in with two stages, that leaves you with only 1-1.5in of overlap on the sliders, which is not very stable. And actually you can’t get that much reach with the chain lift because you have to have 2 stationary idlers attached to the robot frame that the chain goes around. Therefore it is nearly impossible to reach 30in with a 20stage chain lift. And if you are able to lift 30in, you won’t be able to reach higher to descore objects.

I would suggest 3stages. While adding a little more then 1/2 pound, you’ll be able to reach higher, and have more overlap on your sliders giving the entire lift more stability. Adding a 3rd stage really doesn’t make the lift any more complex, wo I would say the pros certainly outweigh the cons.

I’m not sure if a 4-bar system (or anything that has an arcing motion) will be good for this game. No one can be sure but considering you will be at least 30" tall, having to add that dimention to lining up to score will greatly decrease the driving capability. But maybe that’s just me.

Also, while that peacillier (I don’t think I spelled that right, but I don’t feel like looking it up) is great because it has vertial movement, is does take up quite a bit of room and I think this year many teams will need room for an intake system. This might also put constrictions on other kinds of four-bar systems. Really that part just all comes down to how you can fit all of your modular parts together.

I don’t have a ton of experience with scissor-lifts so I don’t feel educated enough to comment on them. I’m still not sure if the way they acelerate when going up is a good thing or a bad thing for this game.

If I think of other things, I’ll post them up.

Why do you think an arching motion is bad for this game? I would say it would be beneficial to have a 4 bar link or extended 4 bar because you have more room for a manipulator. And while center of gravity is a potential problem, it can be overcome by balancing the weight and keeping it low to the ground. As we saw in Round Up, it is very possible to master the driving of a 4 bar link even when all the goals are vertical posts and would suggest linear motion. In Gateway, it is even easier to drive a 4 bar because there are no vertical axes to aim for. All you have to do is pick up the objects, lift them, and drop them into whichever goal you want.

Programming and Robot Skills have vertical axes that are important to aim for.

Very true. At one point I considered designing the robot around that, but then I figured I would prefer to win the competition than to win robot or programming skills :D. But it is something to consider.

A perspective I looked at it from is based off of what I noticed from this past season in FRC: Logomotion. The vertical lifts out-performed the rotating arms because it was one less dimension of lining up to score that they had to worry about. All they had to do was drive it up to the right height and then drive forward to put the tube on the peg. idk, I suppose it’s personal preference, but one of the many things I’ve learned from FRC (and VEX) is make it as easy on the driver as possible.

Using potentiometers one can achieve the same simplicity. Using pre-determined values you can lift the 4 bar link up to the correct height, then simply drive up to the goal and deposit. I agree with keeping it as simple as possible for the driver though, which is one benefit of having two drivers. That way one person can focus all their thought on the lift while the other can focus on driving the robot.

I see what you are saying; however, I believe in Logomotion that may have been true while in Gateway it is not. In Logomotion, you had the added complexity of scoring which involved hooking the piece of the logo on a hook. In this way, Logomotion became more similar to Vex Round Up because it added a linear component (similar to putting a tube down over a post). In Gateway, as Thorondor (my teammate) said, you merely have to lift it to the correct height and drop the object. We’ll see, but I think the time it takes to make it easier to drive the robot could be better used in testing and driver practice.

the one my team and I are working on was reaching about 40-45 inches but I set it to only go 30.5 inches.

why would you want your lift to reach 45 inches?

I think he simply meant that their lift was able to reach there, but they modified it/programmed it to only reach 30.5", as 40-45" is a bit unnecessary.

~Jordan

oh i see. makes more sense.

A question to all you four bar people: Why is it so important that you maintain the manipulator’s orientation relative to the ground?

A prototype I’m working on actually counterrotates the manipulator as it goes up - an anti four bar if you will.

I would say that most people want to keep theyre manipulators level to the ground because they believe it could help with scoring of the objects. I personaly think that wether or not your manipulator needs to stay level is completley based on what your manipulator is. I you have one that dosen’t raise above the post or it does just barley to score out the top than i think it should move onto an angle to help score however, if yours goes greatly above the goal to score out of the bottom of it than you will probably want to keep it level.

If your manipulator can pickup from any angle, then it is less important.
If your game plan includes pickup from only floor level, (not top of a stack), then it is less important.
If your manipulator can score from any angle, then it is less important.

Constant orientation was helpful for the Object shape and scoring/descoring orientations required for RoundUp, but not for CleanSweep. Depends on whether you are playing the game more like RoundUp or Cleansweep.
To me, the college game looks like RoundUp in the Isolation area, and Cleansweep in the Interaction area.