Team 2425 Hydra: "Reminiscence"


Theoretical Strategy/Mindset: Looking at past games, We focus on being as disruptive as possible. We use our sideways intake ability to quickly grab wall sacks and trough sacks. We also use this ability to spread out the sacks in our trough to slow opposing de-score, reduce overflow, and to quickly de-score/re-score. To avoid tempo loss, we target the wall sacks while traveling to the goals. Then, to win the edge, we target the “neutral” trough sacks.

Actual Strategy/Mindset: In competition, we faced major connection problems. In all honesty, we have no clue what causes our connection issues([ So, we focused on grabbing the bonus sack on the left side of the field under the trough in autonomous and used our pre-loads to quickly secure 50 points in the high goal. Connection got so bad that was usually as much as we got done. If we did survive a bit longer, we were able to de-score a few sacks and park. With strategic alliance selection and game play, we were captains of the 6th rank alliance and advanced to the finals, where we eventually lost due to connection failures.

-Holonomic (mecanum)
-Lowered Drive
-Geared 1:1 (ignoring holonomic properties) on four 393 motors in high torque

-Offset Reverse double 4 bar (angle gets less steep as it raises)
-four 393 motors
-Geared 5:1 torque
-elastic assistance

-Side rollers with standoffs & non slip pad
-geared 1:1
-Elastic powered expansion
-Elastic powered deceleration + padding


  • 4 encoders
  • 2 line followers

-Sideways intake: Can strafe and grab without backing up
-Holonomic: Omni-Directional Drive
-Vacuum: Any offset sack gets pushed towards the center of the intake
-High goal score: Reaches 35"
-Doesn’t stall when pushed
-Usually holds 2-4 sacks; Can Hold 6 using pre-loads
-Doesn’t tip with interference when lift is up and driving
-Expands at the start of the match

Feel free to leave Questions, Comments, and Advice]( So, we focused on grabbing the bonus sack on the left side of the field under the trough in autonomous and used our pre-loads to quickly secure 50 points in the high goal. Connection got so bad that was usually as much as we got done. If we did survive a bit longer, we were able to de-score a few sacks and park. With strategic alliance selection and game play, we were captains of the 6th rank alliance and advanced to the finals, where we eventually lost due to connection failures.)

Any videos? What advantages have you found with the side rollers as opposed to the top rollers which have been pretty popular so far? Looks very nice overall :).


We have a few, but i have no clue how to post them.

Our biggest advantage is definitely the sideways grabbing. We avoid unnecessary movements in de-scoring. Typically top rollers need to back up, readjust, grab again, maybe even shift the drive back and forth to agitate sacks, re-raise lift, etc. With the side rollers we can simply set the rollers, grab and start strafing left or right and completely clear out the trough. This sideways grabbing ability also applies towards the wall sacks and trough sacks. We don’t need to back up slightly and readjust the intake. We can just strafe and grab. By doing this, we can shave seconds off our time and reduce driving complexity. Even if top rollers are wider than the intake, the rollers push a few sacks towards the center. Also, if you grab a large compressed pile typically seen when scooper robots de-score or in goals (lets say like 5 or so sacks), the rollers adjust to the size using the hinges and keep it as one big pile. A few top rollers tend break the pile(like ones made of tanktread expansions), causing them to dispense slower because they gradually grab it instead of one big stack.

but ill admit there are problems with this intake. It’s difficult to grab single sacks at a time. Also, when building it, you’ll face all the problems you’ve had with the top roller x2.

There were a couple of side roller intakes at Asia Pacific too, very interesting. Yours looks different though, you have stand offs as the intakes so I suppose that could be better.

Have you got any videos of your robot in action?



You could try uploading them to youtube and posting the link. If you have a dropbox, you could also save the video there and share the link.

I like your design, I had thought of something similar with the lift at first but found it too complicated to adapt to my design. Nevertheless, I like what I see.

I looked at the videos we filmed and noticed like 2 of the 3 we have were just us talking to other teams. We’ll probably do a bit more filming Friday and Saturday and have them posted On Sunday.

I haven’t seen any other version of side rollers. My guess is that if they used tank tread expansions, they probably didn’t do well. You need something firm and long to reach deep within the sacks/troughs. If they used solid metal, my guess is that they have jamming issues.

Thanks. I have a feeling we built the lift incorrectly though. Even though it raises, we’re noticing other teams can pull off the same height with less power ( Also, in the heat of competition, we noticed the axles started to bend. We’re filling up with spacers in hopes the stress will be less significant.

There are a few ways to avoid this:

Don’t make your axles any longer then they need to be
Bolt the arm (metal) to the gears
Make sure the axle is supported on both sides

I can only help so much without an up-close picture of your gear tower.

Good Luck! I hope this helps.

The website was edited with a photo of the rd4b. There are a few things different with the photo and the actual robot. The robot uses 393 motors, not 269s. We also use high strength, not regular. The axles go completely through the arm system. And the outermost bar(the one thats furthest from the gears) is connected to the center bar by 2, two inch standoffs.

We did suggestion 2 and 3, however we were uncertain about suggestion 1. We felt like it was better that we divide the weight with the center bar and make the axle slightly longer, rather than have an extremely long bar that isn’t supported in the center and carry the full weight of the lift.

Congrats on your results at the tournament. We (5900C and my friend from 5900W) went against you in the finals. I have to say your alliance was a nice surprise going to the finals. You definitely had the crowd cheering as you won your semi-finals as the underdogs and we enjoyed playing with you in the finals. I was wondering if you had an autonomous routine and what was it like if so? Also, did you compete in skills challenges?
As far as your connection issues go I’m not sure. One issue our team has encountered before was forgetting the unplug our 9 volt backup batter after matches. This sometimes cause odd connection problems like your having. Make sure you follow the Robot Startup Sequence exactly and this may help. Other than that I am not sure. None of 6 teams from our school encountered any connection issues during the day.

Ah yes, i remember you guys. Congratulations on winning the tournament:). Your autonomous that started on the right tile and grabbed both clustered sacks and some sacks underneath the trough was terrifying.

Unfortunately we didn’t do any skills challenges. We were waiting in line for judging at the time, and knowing our driving experience (about an hour), we knew it was pointless to try reaching world ranking driver skills. Plus, our connection issues were terrible

And as for autonomous codes we have 3. The first one, which we used in competition was an autonomous to simply get close to the bonus sack, raise our lift to show off (gotta catch judges attention :cool:), and drop a sack on the tile. The second one was to grab the wall sacks, score them in the trough, and de-score the center blue trough. We didn’t use that autonomous because we damaged our back left encoders a few days before competition. Our third autonomous is a bit secret for now. We plan on using it in the competition in February. We do plan on starting on the left alliance tile, and we plan on using the full 15 seconds.

That was my friend from team 5900W’s autonomous mode. Ours was to grab the sacks along the wall and score them for 30 points.
Did you always unplug your backup battery after matches? I know you’re supposed to so that may be an easily overlooked issue. Also make sure your keys are secure not only on your robot but also on your joystick.
I’m very curious to see what you have in February. When we got to competition we were surprised by how short 15 seconds was (we haden’t timed our autonomous before :rolleyes: and had to speed it up between matches). Keep in mind that if you make an autonomous routine for only the left tile that you may end up on the right tile, so make sure you can choose to not run your routine (learned that the hard way a few years back) by pressing a button or something if you don’t already have that.
I reprogrammed the robot a few days ago and I’ve come up with a few secrets too :wink:
And if you ever have any problems; broken motor, encoder, etc. make sure you stop by our table. If we have what you need we’d be more than happy to lend the parts and time.

Ah woops my bad:o Both of you were amazing in competition. But no we didn’t unplug the backup batteries(maybe that’s an isue?). We did try unplugging it and replugging it during a match, but there was no success. I really hope its a vex net issue. We knew our vexnets aren’t reliable (you can hear loose pieces inside). Yeah the autonomous period is quite short, so we really had to focus on combining as many tasks as possible and minimize repeated trips. Actually I never thought much of the tile problem. Luckily we can use the shifting rule and angle the robot slightly so it doesn’t move around until we want it to;) haha pre-competition alliance forming XD? Ill look into it:). By the way, I heard that my school and middleton(minotaur and theseus) may have a scrimmage. I don’t know the details yet but your always welcome to come.

We’d be glad to come! Is it going to be in the Tampa Bay area? That’s only an hour away for us. Definitely make sure you unplug your backup batter after each match, its part of the Official On/Off Sequence. If problems persist I’m sure you can call up VEX, they’ll help you troubleshoot the problem. Besides February, are you planning on attending any other competitions?

Yep it’s in Tampa. I believe it’s at Middleton, i need to get more info from my mentor. We’ll try that, hopefully that was the problem:). But if we still have problems do you mean contact vex with the official forums? I know for sure February is the next competition we’re going to, January is a bit to hectic with frc and ftc. If there’s another after February and we’re probably going to attend it. What competitions are you attending?

I believe that the only reason you are supposed to unplug the backup battery is so that the Cortex actually shuts off when you have the on/off switch flipped to the “off” position. (Sometimes the backup battery continues to supply power to the Cortex, even when the Cortex is turned off.) So if all the lights on your Cortex are already off, you should not need to unplug the backup battery.


I’d call VEX support. They won’t be back in until the new year. Likewise we are going to be busy January with FRC. We have a league going on at our school that we’re competing in (Bayshore High). In January we may break off and go to the space coast depending on how hectic FRC is. Then in February there’s Tampa Prep Throwdown, the Battle in Brandon, and the Robot Apocalypse in Fort Myers. The Battle in Brandon conflicts with our district TSA competition, so our attendance is tentative at this point. Otherwise, we are going to try and attend as many of the above as possible.