How does the disc always hit near the neutral goal? Is that programmed or is it just you driver aiming?
Fast builds are really impressive. Big congrats
I guess a scissor mech with the ratchet to prevent people from pushing it back in? Any plans for defense against people defending your expansion?
Why did you opt for a mechanum drive? Just curious because I dont fully see how strafing will be very useful this competition, not insulting, just curious.
I would, in fact, argue that any drive constitutes a mechanism.
Because this bot doesn’t appear to have a turret, A mechinum drive could allow a driver to stay pointed at the high goal while being fully able to traverse the rest of the course in a 2-dimensional plane. with a normal tank drive, a robot facing the high goal would be limited to a 1-dimensional line of movement
@Sidoti careful now…
That my useless phone keyboard at work there lol
Well at first that’s what I thought, but when i thought about it, it actually seems less efficient than a tank drive, would it not take more time to move forward to intake a disk and likely have to move backwards then strafe to the next disk versus having to go in one line and then turning? Personally I think it would be more usefull if the intake loads disks from the sides of the robot. Again, not trying to insult anyone here because I do think the robot is really impressive especially for a 24hr one.
It’s because you are both shooting and moving at the same time. consider this. With a tank drive, it takes 1 sec to move to a new disc. with a Mechinum drive, it takes 2 sec. for both bots, it takes 1.5 seconds to line up and shoot the disc. the tank drive would have a time of 1 + 1.5 = 2.5 sec for a cycle. the mechinum would only have a 2-sec cycle because it does two actions at the same time.
I also figured this but if you do focus on intaking 3 disks at a time it would be overall more efficient with a tank drive, as a matter of fact unless you have to, I think shooting one disk at a time is a bad idea because there is a lot of time being thrown out the window each time you align to shoot, furthermore a mecanum drive would most likely still have to do minor adjustments for aim before shooting, faster than a tank but still needs to adjust. Using your method, intake+shooting 1 disk at a time with with a mecanum drive x3 = 6 seconds versus intaking 3 disks and then shooting with a tank drive: 3 disks = 3 seconds + 1.5 = 4.5 total seconds.
I did just realise there the benefit intaking the disks that are placed on the border of the low goals most likely being more efficient, and might save time.
FTFY
with a mecanum drive you can still turn to pick up discs just like with a tank drive, you just also have the option to strafe. So really, there is nothing inherently less efficient about a mecanum drive compared to tank, and in fact I’d argue the added maneuverability options will make it on average faster to collect each disc, if the driver properly utilizes it.
Why then, I ask you, do world champion teams never (to my knowledge) use mecanum? If it’s inherently better, why do teams use omni wheels at all?
I see the argument that there isn’t room, or that the game isn’t really designed for it. But there is no way that is true for all past games, so I don’t see the validity in that.
One last note, it seems that most people don’t agree with your reasoning
I don’t think there is anything inherently better about mecanum wheels either, but there are some advantages and disadvantages to them which make them a very viable and competitive option in the right hands.
There are many reasons why mecanum (and to a greater extent, all non-tank drives) do not typically win worlds. Like you mentioned, many seasons are less suited to holonomic drives. Holonomic drives also require a lot of investment before they benefit a team. You have to put in a lot of additional programming and driver work to make them competitive, and the vast majority of teams make the decision to instead focus efforts on refining a simple robot. Simplicity is almost always when ends up winning in the end, just because by the very nature of vrc, having a super consistent, simple bot with a ton of driver skill will usually win in the end. As to why mecanum drives are generally disliked, I figure there is a number of reasons as well. Many teams are unable or unwilling to put the necessary effort and skill into properly using holonomic drives (which is totally a competitive and viable decision to make, I would never recommend holonomic drive to a team that prefers tank.) Also I see a lot of people bashing mecanum wheels in particular, which causes teams who have never even tried them to just assume they must be bad.
of course they have their tradeoffs, they are bulky, heavy, worse at pushing and defense, and I’ve heard they suffer under inconsistent and unwieldy center of mass. X drives as well have other disadvantages, they are arguably bulkier than mecanum, and much more complicated and difficult to build than mecanum.
But to everyone who thinks mecanum wheels are inherently bad or non-competitive, I suggest you give this a watch and reconsider your perspective.
In the right hands, mecanum wheels can be a very competitive and perfectly viable option, and I do think this game might have the most potential as a mecanum-friendly season yet. There is no robot expansion, so center of mass will remain constant and central to the bot. There are not really any climbing obstacles (other than potentially the low goal barrier, which is pretty small and could easily be driven around, as I imagine intakes on most bots might get in the way of traversing that). And strafing seems particularly useful in this game, for efficiently collecting and aiming shots.
I have experimented with mecanum wheels before, but never used them in competition, as I, like the large majority of teams, was perfectly comfortable with tank drive, and I knew that my programming ability was not good enough to make good use of them, and though I knew I could certainly improve my programming ability to make mecanums competitive for me, I chose to instead use my time to improve other aspects of my robots. But I think if I was still competing this season, I would be seriously considering mecanum wheels. Possibly with a 6 motor 6 wheel setup, similar to interesting asterisk drive setup mentioned here.
Well in my opinion the tank drive would be easier to gear up to make faster than a mecanum drive, not to say that it is impossible on those drives though.
This may seem like a stupid question. How exactly did you rig the two blue motors to the single fly wheel? Did you use a chain to attach them or just attach the 84t to the 12t?
I knew this video would come up sooner or later.
Back to the discussion, yes 7K was incredibly good, but not because they had mecanum. They barely used it during the driver round, and nothing they did couldn’t be just as easily done with tank.
I do see your point that in the right hands mecanum can be good, but I think in VEX, it is very very difficult to be superior to tank with mecanum. So much so that it is not really worth it to put the extra work in to do mecanum.
In the end though it comes down to personal preference. There is a reason that both are used. Thanks for the explanation.