18-02-2004 23:27

Max Lobovsky

Re: pic: Team 188 Closer Look

This appears to just drive one side of the robot. If thats true, how can you possibly use even 1/2 of the power available to you here? Wouldnt your draw much more than 120 amps with the six biggest motors running simulataneously and then say... trying to push something immovable? Can your wheels utilize this much power?

18-02-2004 23:37

thoughtful

Re: pic: Team 188 Closer Look

this has been done before, your motors dont have as much load on them when they are in a gearbox like that, coupled with other motors. The share the load. Also this might be a problem becuase of the extended use of motors this year but i doubt it. I hope it works out for these guys, and yes they will use that power to bully the 2-motor drives around

18-02-2004 23:50

Steve W

Re: pic: Team 188 Closer Look

True this has been done before. We did last year. No blown fuses, just broken chains. Using 35 chain this year with some improvements.

18-02-2004 23:51

Max Lobovsky

Re: pic: Team 188 Closer Look

well assuming two motor limited 2+ motor robots get into a pushing match. Their current draw can sky rocket to over 450 amps for a drill+chip or nearly 600 for this beast! Now what i was imagining is this robot locks its motors. I dont know the specific types of breakers used, but its possible to destroy stuff before something blows. if they dont have all the breakers working properly, they could probably melt even the 6 gauge wire itself pretty quickly.

I understand that locking the drivetrain is unlikely with so much power (unless of course a screw driver some how gets jammed in there ) But regardless, three motors seems useless. Basically, i dont understand why anything more than a drill and an FP is needed because when running both at max power, the total current draw is already pushing 130 or so. Why design something that has a maximum power that you cant even utilize. Also, three motors must introduce a very large amount of ineffeciencies because of motor curves not matching.

Because of the proliferation of 2 and 3 drive systems, I must have something very wrong in my analysis, or maybe i have discovered the key to the perfect drivetrain

19-02-2004 00:09

thoughtful

Re: pic: Team 188 Closer Look

maxlobovsky, your concerns are right that the "theoratical" current draw of their robot will be very high, coupled with their spikes, e.t.c it might even be 500 AMP. But will they ever hit tht point?, i mean if there are in a pushing match against someone who has a 2 motor drivetrain, whose fuse will reset first? the 2 motor drive train because it has more load on individual motors. The motor curves can be very accurately matched with some testing and good programming, basically making tables and having different values at different point for the motors so they run on almost same RPMs always. Also if there is a very minor different its unnoticeable, and because they are not using the transmission on their drill, all are raw DC motors, they will help each other, not overlaod each other.

Though it would be interesting to see them go against someone with 3 motor drive. They both might reset their breakers .

19-02-2004 00:16

Max Lobovsky

Re: pic: Team 188 Closer Look

I've updated my post slightly. What im really saying is that it is useless to sue the 6 biggest motors when you could get essentially the same effective power out of 2 motors (and not even the drill and chip). Of course they may be trying to keep their motors in the most efficient part of the curve, but all the extra stuff that this drivetrain requires (bigger, heavier gearbox, more wiring and controller, etc) probably kills that gain in efficiency

19-02-2004 00:16

pras870

Re: pic: Team 188 Closer Look

I've seen a number of teams using multiple motors for their drive system this year. Personally, I don't see this game as being like last year and being 1 big shoving match. I think that even a simply drive system using a very simple motor will be fine. However, This drive train looks immense. Looks like the Fisher Price motor, Drill, and Atwood. This must be one of the fastest and most powerful robots i have seen so far this year.

19-02-2004 00:20

thoughtful

Re: pic: Team 188 Closer Look

I totally agree with you, i am sure they have their own reasons for doing that. But i just wanted to get it clear that it gives you some superiority in you drivetrain. Though you might have to compropise a bit on your arm or lifter, unless you use a clutch, but that would need a lot of experience.

19-02-2004 00:26

Hinkel Y.

Re: pic: Team 188 Closer Look

It worked well with us last year with Blizzard 4 although last year we broke a chain every few matches... But we might see some pushing matches like last year's...
The image of the gearbox is pretty much to scale about an inch give or take...

19-02-2004 00:31

Hinkel Y.

Re: pic: Team 188 Closer Look

I'm just gonna say, we're overweight (counting in battery and everything) and finding stuff to drill out/sand down... But thanks to our genius we've got this gearbox together to work perfectly...

19-02-2004 00:33

Soukup

Re: pic: Team 188 Closer Look

OMG....

u guys got it to work. Amazing. If it works like last years in the slightest way.....u will win big. Many teams have no idea how much speed and power these guys had last year.

19-02-2004 00:35

Max Lobovsky

Re: pic: Team 188 Closer Look

depends on your monitor

I guess i can't really argue about drivetrains until i get more experience. Its just that i dont understand why my analysis is incorrect.

19-02-2004 00:36

thoughtful

Re: pic: Team 188 Closer Look

i remember and look forward to meet them again this year, their robot was great only the yellow delphi and the little blue robot with cross bars had power to match theirs

19-02-2004 01:29

pras870

Re: pic: Team 188 Closer Look

I agree we might see some pushing matches, but they will be minimal at most. With the way the game was designed last year, a lot for teams figured it would be like battle bots from the begginning. It turned out they were right. With the Hill having 25 points (don't really remember), it was obvious a lot of teams would try for this, and they did. That meant keeping other teams off to optimize points.

However this year, reminds me of 2001? I'm not sure which one, but it was the year with the ramp and balancing the 2 goals. It seems like FIRST looked at the game this year, and realized they were going in the wrong direction. Looking at how the game is described and going to be played, it seems like pushing will be at very minimal.

I am not saying pushing will not be a factor, because it will in very rare instances. This game is more about strategy and robot effectiveness, not so much brute strength. Adding the 2x ball and the maneuvers it take, is very reminiscent of past FIRST games, which it seems like they are going back to, which I'm glad to see.

19-02-2004 01:43

Karthik

Re: pic: Team 188 Closer Look

Congratulations to Woburn for once again creating a fabulous gearbox. For those who aren't familiar with team 188, this will be their third consecutive year using a six motor drive system. The addition of the shifter makes them even more dangerous.

How has it been performing during the testing? Has the new chain held up well?

I look forward to facing you guys in Pittsburgh and Toronto. Wow, it sure will be weird being on the other side.

19-02-2004 07:01

Steve W

Re: pic: Team 188 Closer Look

We also do not believe that there will be tons of pushing. Speed and precision are what will be important. Shifting gears will allow both. If and when power is needed ...... If you think that pushing will not be important, what would you be doing if someone where trying to uncap your goal or cap theirs for the win?

19-02-2004 08:04

jonathan lall

Re: pic: Team 188 Closer Look

You and Ian can always do something about that you know . your swerve/strafe drive is pretty freaking impressive too.

Thanks everyone for the commentary. Let me just address a few things. First, you are all welcome to take a look at the regionals, I'd be happy to explain it, and get into an argument as to why it'll work . From experience, we have found that blowing breakers is very rare, and in fact we never did last year, despite having a non-shifting three-motor box. While there are hungrier F-Ps this year, we believe the ability to shift in conjunction with the backup battery keeping our controller on, will allow us to not overtax ourselves in matches. max is absolutely correct in saying that the three motors should not peak, because their current draw at that level is far higher than the motors will ever take. The gears are optomized and mated in such a way that something near the peak efficiency of each motor is used. The current is equally distributed. As a result, we will be able to get slightly more pushing power at the same amount of draw, divided over three motors; it won't be a full 'motor's worth' more, but it'll be enough to seriously mess with teams that thought they were powerful. According to the current curves, after about 10-15 seconds at stall in high gear, our robot will probably nuke itself, but we do not expect this to happen in normal match activities. It was also mentioned that versus a two-motor gearbox, we are not overtaxing our breakers, but the other robot will be. We will prevail. Bottom line, six-motor drive is a tried and true method for Woburn (although I have seen two other teams do it). Ask anyone at West Michigan or Toronto and they'll agree. Just try pushing us.

As it happens, we don't believe a huge amount of pushing will occur this year. That doesn't mean in our minds that we shouldn't be able to do it. Maybe more on the gearbox later from the source, but we'd like to keep a little mystery .

19-02-2004 09:12

Joe Johnson

Re: pic: Team 188 Closer Look

I concur. In addition to all your comments I will add that it is almost impossible to trip the main breaker with the battery we have -- really.

As to whether 3 motors per side with a shifting transmission is needed, that is a topic for another discussion. Awesome job of engineering regardless of whether or not you acually need all that power.

Joe J.

19-02-2004 21:33

Andrew Rosselet

Re: pic: Team 188 Closer Look

So it has finally been noticed- our capability to shift.

Let's all point and stare, and then pat Tristan on the back for an amazing job

19-02-2004 23:39

Hinkel Y.

Re: pic: Team 188 Closer Look

I don't think the chain might break, but there's always a small possibility in low gear... Like last year for example, our three motor gearbox with our 25 chain was really weak... If you've seen us last year, every few matches, there was at least one chain broken and 3 at one point I think.

Good luck to everyone with their bot with only 6 days left...

19-02-2004 23:43

Yan Wang

Re: pic: Team 188 Closer Look

Team 639 will bring extra chains

19-02-2004 23:48

thoughtful

Re: pic: Team 188 Closer Look

25 mm chain saves a lot of weight, though i hope it doesnt break. We will have our pockets full with chains