Motor distribution

What would you do in the following situation? You have a robot that needs at least a four motor drive, two motor lift, and two motor intake in order to operate. You can place the other two motors wherever you think they will make the biggest impact. Please vote after reading my case for each placement, and comment with your case for your decision. Assume all 393 motors.

For this game you want a four motor lift. Capacity is a defining trait for competitive robots, and the more you can lift the more you can score. What is the use of scoring small numbers of sacks if they can just be descored faster? No, you want to get over twenty objects and dump them all at once and protect them.

Reliability is king. Although your robot works on a four motor speed drive with no problems, you could stall if you get in a defensive struggle. Even if you just stall once it could cost you the match and the tournament. Although it might not make an obvious difference in a normal match, your six motor drive will hold up where four motors begin to falter, and this will be apparent in the rankings.

For maximum efficiency your robot should be able to pick up as fast as it can drive. This means you want a fast intake. You’ll be able to pick sacks off the floor or out of the trough with no difficulty whatsoever. Who knows, maybe you’ll even be able to push off pesky trough blockers with your powerful roller.

Did you see people making transmissions to switch motors from the lift to the base? That would sort of fix your problem if you are running out of motors.

Personally, we used:

4 393 High Speed on the Base (Mecanum, meaning that 6 motors was pointless)
4 393 High Power on the lift
Around 40 Rubber Bands on the lift
2 393 High Speed on the Intake
Pneumatic on the intake

Which worked just fine.

For the Circuit Breakers, we did:

2 Lift and 1 Base (Cortex 1-5)
2 Lift and 1 Base (Cortex 6-10)
2 Base and 2 Intake (Power Expander)

Was that your question?

I have to say Drive. Speed is big this year. We can lift 16 sacks with 2 motors on a 15:1 ratio with the motors set for speed.

We will probably be switching our intake motors to speed soon.

No doubt in my mind that the best option would be drive. The 6 motor high speed drive is the best option out there in my opinion. Without it, my team would not have made it nearly as far as we have at nationals last weekend. I’m not saying we made it that far (to division finals), but if we had placed our motors elsewhere that would’ve changed everything. It gives you enough power to hold back a robot from descoring your trough.

While it’s hugely situational, I personally haven’t found any reason you’d want 6 motors on your drive unless you plan on going faster then 1:1.6. Generally speaking sack attack isn’t much of a pushing game then it is a blocking game, so I see the 2 extra motors on the drive being pretty much a waste. I think the 2 other motors can be used for a longer lift, or a faster/more powerful intake (or both :p), depending on one’s goals. Of course if your strategy includes a lot of pushing, perhaps a slower 6 motor drive makes sense for your situation.

Lift or intake (or both). In my honest opinion extra motors on drive is just silly for sack attack.

If you guys are planning on using the 4 motors in high speed on the drive you’ll find yourself pushed against a wall by a bot with 6 high speeds on their drive. I think that little extra power on your drive will take you a long ways.

Thank you everyone for the suggestions!

I think we might just try out an eight motor robot to begin with and see if any of the subsystems I mentioned seem lacking. If they do, the motors can go there. Otherwise we might just stick them on the drive. (Bad experience with stalling at the most inconvenient time last year).

I’m not going to implement any sort of transmission as I feel that it adds a lot of unnecessary complexity and opens the door for all sorts of problems that outweigh the potential benefit.

Sack attack is designed well to give plenty of escape routes in cases like that. I found with a good coach and good positioning, you can see a robot planning to block you out from a mile away, and my team has been very successful against teams attempting to block us. Also designing your robot in such ways to anticipate this kind of interaction also helps :wink:

Yes, but if they do that for 5 seconds, they are now illegal, so they have to get out of my way or they get DQ’ed. :wink:

you assume the refs will call every bit of contact however. Even with the best refs, things go missed.

Let’s all be clear here. It seems like some people are still confused about the rules regarding robot to robot contact.

We can hit you. We can push you. We can shove you all around the field. We can hit you, back up, and hit you again as long as we don’t tip you.

The only thing that’s actually illegal is shoving you into a corner or wall and then continuing to drive into you, or confining you to less than a 2x2 area. That’s IT. Everything else goes.

sometimes we can be tipped too and its fine :stuck_out_tongue:

Note the ref wasn’t paying attention during the tipping. Things happen, and we’re planning to build around tipping attempts by other robots, but its not always avoidable, so build robustly.

Tipping is illegal and should ALWAYS be called unless <G8> has been invalidated by their expanding horizontally and playing defensively. Granted, if you build a top-heavy robot, and have the arm extended 30 inches in the air AND you are trying to take objects out of your OPPONENT’S trough I could see a referee not disqualifying your opponents for tipping you. But even then, under the rules tipping is illegal even then.

Issue a warning the first time, disable and disqualify the second. Remove from the tournament the third. Everyone should be playing by the same set off strictly enforced rules.

I saw this video and I was so disappointed in our partner. Trying to tip teams is no fun. I actually believe the team that tipped you was DQ’ed. At least that’s what I heard from the refs.

Sorry about that :frowning:

Oh were they? while a DQ is fun for neither side it is still appreciated that it was noticed, even if we potentially lost a win out of it. Either way, we didn’t have much of a chance in that match, so I’m not too upset about it. I just wanted to prove my point. Appreciate your kind words :slight_smile:

I’m unsure from the video, but I saw nothing illegal there… it was two teams ramming into each other, neither with the intent to tip, and neither of their arms were raised. Perfectly legal in my eyes. I find tipping a VERY common part of Sack Attack, and you should design robustly and carefully, as in most situations tipping is legal, as both robot’s are fighting over sacks/troughs.

Ha. If that’s the case, we are going to have a LOT of fun at Worlds. We learned to play extremely carefully in order to prevent tipping other robots. If we can suddenly drive like nutcases, I foresee a great deal of laughter to be had.

But that’s just not the rule. Read <G8> again.

I will reread, but there’s a difference between rules and what ref’s actually call. I’ve been tipped plenty of times in the past, and I’ve seen my fair share of DQ’s that have been deserved, but in most situations, it’s two robot’s battleing for control over a trough and one by accident tips over, there’s no reason for DQ.

If two robot’s collide in attempt for positioning, and one is design better not to tip then other, why are you punishing the robot that was better built?

back onto the topic of motor distribution, my teams robot has come a long way…

We started with a pneumatic lift, and an 8 motor drive/2 motor intake. This worked pretty well with a 1:2 gear ratio for speed on mecanum wheels. We were able to beat most teams to crucial areas on the field and were still able to push. This extra speed/strength helped us to win state, however, the lifting capacity was too low.

We redesigned and cut our drive motors in half, using only 4 on the drive (internally geared for speed), and 4 motors on the lift (still with 2 on the intake). this increased our lifting capacity and we didn’t have to worry about running out of air during matches. The pneumatics were better suited elsewhere.

I feel that without the lifting capacity we had with the 4 motors on the arm, we would not have won nationals. However, if we were going to worlds, I’m sure we would think about a 6 motor drive, as it seemed pushing could have been a problem if we weren’t too careful with driving. A 2 motor lift seemed sufficient as proved by Aftershocks amazing robot.