Wallbot Development -- INPUT ADVICE HERE

When we first read the game manual for Starstruck, we got in our heads that the best way to win was to prevent the opposing team from scoring, or at least make it really hard to. So we came up with a design (later I discovered it is referred to as a wallbot) based on something similar to this:


Except with an extra couple of folding arms. Other than that it’s currently planned to have a few extra key features: the 3rd subsystem rotates. Reason being so that we can switch to a strafe mode, moving easily along the fence. Why not just use Omni wheels? Mostly because we don’t have any, but it’s also very hard to push the bot when the normal wheels are perpendicular to the force. Oddly the only problem with it’s play (if it works) is it has a particular potential weakness to launcher bots and pushbots. The good news is that the main competition is dumping claw and low altitude catapult bots, but the ‘easy’ ones are a particular issue. So really, I figure if we can flop through the qualifiers we can do very well against the main competitors, which is the type of build it’s made to counteract.

So the motors… it got a little sketchy in distribution, but I’m thinking it’s gonna end up using -4x drive motors -4x arm controls -2x turret rotation system -1x arm pitch control -1x anti-tip arm deployment

So the strategy is basically get to the fence, push all of the stars off (ability you get when you have that huge bar), and block. Switching high/low as needed. Teamwork is gonna be a big deal so we can keep our ally scoring, but it is a team game so why not.

And this is where you guys come in. One issue I know about is just a motor power/gearing issue; will the 4 arm lifting motors be able to lift the 8ft of those bars. Well they can, the question is will it be able to without having to gear it to a dismal speed, if not then it won’t be able to switch to guarding the bottom quick enough. Other than that just general advice, especially anything past wallbot competitors have to say.

TL;DR - Building Wallbot, Advice?

other than don’t do wallbot that’s a terrible idea…

I’d say 1:7 on your arm would definitely pick it up and a lot of stuff I’d also consider 1:5. The base prob should be as heavy as possible so you can pick up a bunch of stuff without tipping. You also wouldn’t want to get pushed around. As for the drive you prob want lots of torque and strafing ability so I’d go for mechanum wheels on high torque motors.

Build two bases with 2 lifts connected by antislip mat

The anti-slip mat acts as a net, I believe.

yes, their lifts are connected by antislip mat, which acts as a net to stop the opponents from scoring. Much better than one base with a super wide lift to stop scoring

Is an antislip mat something we can legally add? If so I can see that as a perfectly viable backup plan, seeing that the arm proves too heavy/unstable. Forgive me if this sounds dumb, but what do you mean by two lifts and two bases?

Also thanks for the gear ratios, I was lost on that.

Yes; it’s a vex product

Look up 127C or 1471A from Toss Up

Basically, have your robot split in 2. Both sides of the robot should be able to move independently. On each side there’s a tower where your wall will raise up from (a lift). The 2 towers should be connected by the anti slip mat. When both towers raise their arms the anti slip mat should raise creating a wall.

Links for antislip mats: http://www.vexrobotics.com/mat-g.html

Ask away if you need any clarification.

Oh ok, <G11> discouraged me from trying something like that. I see what you’re getting at though.

Would you say have both bases use a scissor lift mechanism and just make them both heavy as bricks? Just thinking how to keep that net tight enough to block effectively.

I’m not too sure about the scissor-lift idea; elevator lifts seems more appropriate to me (you don’t want to risk tension in the net lowering your lifts). But yes, your bases need to be heavy as bricks. Maybe even add some passive anti-tips that extend out in the direction of the net/other base.

Also, given that the 2 parts are still connected (by friction mat), you wouldn’t be violating <G11>.

Well it also has to be connected by some sort of tether that carries the wires.

In Colorado we have 2 pretty interesting wallbots. Sadly neither qualified for worlds, but I will share a bit here.

The first one wan’t very effective, mostly serving as a minor annoyance for us to play against. They were mildly effective at blocking cubes, but weren’t fast enough or large enough to consistently block back dumping clawbots from scoring. However they did manage to block ~40% of the cubes scored against them.

Then second wallbot was more effective than the first one. This robot is actually a tether-bot, with a back dumper and a wallbot. The wallbot part (powered by 6 motors) was a double reverse 4 bar with an horizontally expanding scissor lift attached to the top member of the dr4b which covered a third of the field. It was definitely interesting, but the 6 motor back dumper was pathetic, barely managing to score once or twice a match. This design failed because of how huge the robot ended up being; despite being allied with one of the best teams in Colorado in a qualification round they lost because they simply took up too much of the field without scoring much.

Personally I don’t think wallbots are going to be very effective, especially if they can’t score. The inability to score makes a wallbot less likely to win matches.

If you see the defense played by a lot of bots, namely “claw dumpers” that have standoffs underneath, it is pretty easy to play defense with a good scoring bot. I think defense is critical in a lot of matches; blocking objects is as good as scoring them back over by yourself.

Cant remember where I found this image, but it was saved on my computer…

I have seen 2 wallbots at the 3 tournaments I have been to. One of them did very poorly, as it used a weaved wall of rope which kept getting tangled up. Another one I saw used pullies to lift a steel plate, and ended up loosing in the finals (still pretty good for a defensive bot).

I’m not saying defense is not important. I’m saying a robot that can only play defense is not effective.

I was talking about playing defense with a scoring bot as being effective.

In that case I agree – I thought we were talking about wallbots.

To rephrase - why have a mediocre wallbot when you can have a scoring bot that plays the same level of defense?