Standars of a good bot

Reason for this thread: I really want to get a collaboration with senior vex bot builders on what standards a good robot should meet. (Outside the bounds of the competition or task it is supposed to compete)

By this I mean things such as:

  1. Battery Life while moving at full speed
  2. Battery Life while moving at half speed
  3. Average weight
  4. A good average full and half speed
  5. Balance
  6. Turning capability (spin on a dime or have to do a loop)
  7. Size (Length/Width/Height)
  8. Gear ratios
  9. Size or number of tires or set up of treads
  10. 2 wheel drive vs. 4 wheel drive (pros and cons)
  11. Number of motors
    and anything else you can think of to be a good standard for a robot.

Now before I get a bunch of flamings, I know many of these things depend on the task a robot is designed to complete. But this is just for ON AVERAGE which you prefer or which you believe works best.


And finally once I read through a lot of posts and see what people thing, I will type up the most picked and the pros and cons behind each.



**1. I dont really understand this question. It’s very hard to judge this!

  1. I dont really understand this question.**

  2. The lighter the robot is the easier and faster you will be able to climb with a faster gear ratio with less torque.

  3. I dont really understand this question.

  4. Well obviously you want it to evenly balanced to stop tipping but also a little bit more back heavy to compensate for the amount of tubes you can hold.

  5. Well spinning on the spot is alot better than having to do a full turn. So use Omnis on all 4 wheel’s so turning is much more efficent.

  6. The smaller the robot the more manoeuvrable it is meaning you can move around goals easier but also the downside is it’s not as stable well depending on your design. But the lighter the robot the better for hanging.

  7. Like i said above it all depends on your design but you can either have a 17.5 inch by 17.5 or a 13 inch by 13 inch it all depends on your design!!

  8. The wheel set ups depend you can have holonomic or non holonomic the downside is with holonomic is the extra wheels can add weight unless it’s X holonomic but then it means you need to power 4 wheels. The upside of holonomic is you can strafe side to side which makes scoring easier.

  9. There is not point talking about 2WD if its possible to do 4WD just do 1 to 1 ratio and 4WD is alot more effective! It won’t tip as easy etc while moving. and if you get stuck its easier to move off the tube etc.

  10. I would say 2-4 for drive , 4 for lifting and 2 for the intake or maybe a flag spinner. lol jks.

  1. you mean battery life in general? if you have the money to have a truck full of batteries, then it shouldnt really matter (unless they die in the middle of a match) generally in competition, we switch to a fresh battery every 3 matches
  2. it should be half of #1?
  3. 8-13 lbs lighter the better (use/cut aluminum if you can afford it)
  4. 1.6:1 on 4" omnis is our bare minimal :confused: (2.79 fps)
  5. make sure it will NEVER tip (arm fully up, drive spamming back and fourth trying to tip the robot on purpose)
  6. the smaller the wheel base, the better the turn handling (it will increase the chance of tipping though)
  7. the smaller it is, the easier it is to maneuver, an 18^3 tank will have a hard time moving around the bases
  8. look at #4
  9. usually 4 wheels tank treads are slow and redundant (there wont be a field full of snow/mud…)
  10. 4 wheel drive has more power. on a 2wd if the powered wheels get lifted above the ground (stuck on a tube) then you are stuck until someone pushes you off
  11. as much as you can afford (use the 2wire if you can afford all 10 too…)

addition: holo
using a X holo with small omnis WILL NOT WORK
X holo in general makes it hard to mount on your tower and pickup
X holo is usually VERY tippy
H holo is bad UNLESS you have the same number of motors going forward/back as left/right (trust me, our weak strafe wheel failed)

small omnis:
if your robot is too heavy, then it will cause your robot to sink INTO the foam and cause it not to roll

and try to have as solid of a robot as possible
no zap-straps to hold in a key component of your robot :wink:

Tell that to jgraber…
But yes, he spoke of the problems he had, hopefully most of those will be resolved when the new small omni wheels are available…


“unless you have the money to shave down 8 small omni’s to make them dual rollers -.-”
or you can wait until the said 3" dual omni to come out! ^^ so excited!

You don’t have to shave down the omnis for an X-drive to work:

Haha, like the edit. And also as a side note: I didn’t notice before that two of the small omni wheel-pairs were 1 roller off from each other, I had looked at the other two and thought he hadn’t done that. I wonder why he only did that on two of the wheels?

And yes I can’t wait for the new dual omni wheels come out either! :smiley: 1:3 (speed) mini-omni X holonomic robot anyone?


Hey it’s TechBrick!! Now I know that picture must have been from a long time ago. I mean, look! They aren’t using all aluminum! (By the way in the past year, the first year I got to use a single piece of aluminum, I must confess that I have been overly spoiled, and have completely thrown using steel out of my head. I’m sure many others can relate but I do still think I have been spoiled, haha.) But yes I enjoy the TechBrick teams, never really interacted much with their FVC/FTC team, (because the one year my team did FTC as well as VRC I unfortunately was not on the FTC team. :eek: ) but I know them to be very professional and kind, and have had some interaction with their FLL teams.

Sorry for the complete side-note, but anyway, yes it is completely possible for a robot to use the single-roller omni’s, and create an X holonomic, it just has it’s downsides. Again I say hopefully most of those will be resolved with the new dual-roller omni’s. :smiley:


:slight_smile: I was on their FLL team that year (2006)… (I’ve moved to a different state since then… :()

is that the crowne plaza? :wink:
and i would totally make my defense holo with the 3" omnis
and that robot looks light-middleweight… ish…
on topic:
have anything to add jordan?

Oh very cool! I am still on an FLL team, this will be my last year. And hey! I was on an FLL team in Maryland the same year! (2006!) That was my first year! I remember sitting directly behind a TechBrick team at the Maryland State Tournament, they won some sort of award. Wow that’s pretty interesting, haha. (Our team was the Blue Nano Knights or something like that, haha.) Being there was what inspired me to take robotics further, and after that me and my dad started a team. Then eventually I found out about Vex and now I’ve gone crazy with robotics.

Anyway, going off on a tangent again. Back on topic…


Hmm, defensive holonomic, with the new dual-roller omni’s… I’m liking the sound of it, and to think about it makes me want to continue designing my own idea for a <4" tall robot, and possibly even make it holonomic… now that’d be a crazy addition…


the only thing about my past design was that the wheels were 4"
and the height of the rung was also 4" (and then there was “real life” so the ladder sank into the foam tiles :()

Really what your asking for is unknown! There is no average since almost every single robot is different. All there is guidelines for robots.
with battery power, you want it to last you a specific amount of time, plus have at least a 10% battery power still remaining afterwards. As for weight, it must be reviewed constancy so your battery power rules are followed. As for size, it must be adjusted for weight and battery power rules are followed.

What you ask for is actually quite simple.

There are just a few measurements required:

  • speed on the field (in FPS)
  • speed in scoring (rings per minute?) (and this has to include both movable and high goals.)
  • speed with which you hang. (from approaching the tower, including lineup, to the time you are hanging)
  • and yes, the speed with which you “descore”

After that, you can’t really define a “good” robot. it is all relative. The “good” robots that most people are impressed with merely performed better than their counterparts, which earned them the attention.

It all really comes down to speed. You just have to be faster than the competition. (faster scoring = higher potential score for limited time)

I believe he is asking for outside of competition standards. Meaning not related or involved with the competition.

the double-catapult (Jordan’s link) has a lower CG than any other robot I’ve seen. All motors and batteries less than 1" from the floor.
It also did not work very well. Today’s dilbert comic strip explores the tradeoff between opinions based on experience, and opinions based on theories not yet tried; It resonants with me in both directions.

The concept was to offset them. They didn’t all get offset because my concepts exceed my craftsmanship. The old small omni line up the rollers even when flipping one wheel over, so to get offset rollers I needed to drill out the square hub and bolt it to the other wheel with an offset. It would be nice to think ahead and have half-angle alignment to the axle so you can get aligned or offset rollers depending which way the wheels are stacked. I can’t think of a counter tradeoff.

This is my observation also, and not limited to the old small omni-wheels.

“Design is an iterative process” - JVN
With my current concept (that likely again exceeds my craftsmanship),
will again be an X holo with a central tower, not quite such low CG…

  1. X holo with 4x 4" omni and 3-wire motors, drives fine on hard floor
  2. X holo with 4x 4" omni and 3-wire motors, won’t roll on foam floor!
  3. upgrade to HS 393 motors, still wont roll
  4. upgrade to total of 8x 4" omni ($200 of wheels), still wont roll
  5. 12x 4" omni wont fit my design.
    A. next step is M12:36w HS gears, not yet implemented
    B. if A doesn’t work, try the very laborous process of pulling all 96 rollers off the wheels and installing 10 packages of 4.6mm spacers in the roller gaps to increase the roller density beneath the roller tires. Maybe start with just 48 rollers and step 3 first?
    AB1: if A or B works, try changing the gearing on the 393 motors to speed

This year’s concept robot will rank poorly as judged by most of the standards (good to be speedy, lightweight, rapid-scoring, hang) listed in this thread.

how are you building your robot?
(any pics?)
a standard 1:1 4" wheel X holo should drive just fine

is your ratio too fast?
or are you not supporting the axles enough?

What I am asking is what do you prefer to use. A light robot that is a dart around the field, or heavy and scoring full sets of tubes at once. As for battery life I am asking how long you expect your bot to last. Nothing specific, just an average. I read that one team expects theirs to last for 3 rounds. Thats probably because they are using new batteries. Or it could be like my team and have crap batteries that are usually right about to die by the end of one round. I just want your general opinion on what you expect from a good robot.

Oh well in that case, I would try to build a moderate sized robot thats not heavy and can quickly move about, I would try and get the battery to last 2 rounds. I would also have it so its powerful in its respective area, so if it was high hanging then i would push more power into those functions so it performs better. it would have to be tank drive with geared wheels for speed. I would have it so the bot couldnt be deactivated for some reason during the match. E.g. another robot accidently pulls out a cable of high importance. Basically I like to have the robot do its primary function and not fail at all.