Regional & Division winners, did you shift gears or not?
 

We had a survey prior to the regionals on shifting gears or not. About 3/4 of the respondents felt that shifting was valuable. Now let's see what the winning robots actually did.

Of the winners in the regionals and the championship divisions, which robots shifted gears and which didn't?

If you did shift, what method did you use?

If you didn't shift, how did you overcome any possible handicap that caused?

Wildstang does not shift gears. We have it set in software so that the Speed Controller isn't running the motor at full speed when driving unless you are pushing a button. We dubbed this a Turbo" Button. This shouldn't be confused with a true geared transmission because it's just done in software and does not change the gear ratio.

No shifting here either. I think the reason we were able to do so well was a mix of the power and traction our robot had, and the strategy we used in our matches. But most of all I would say we did so well due to our driver. Every match he did basically the same thing, and doing this allowed him to become really good at it.

384 didn't use a gear box that allowd for shifiting of the gears.

45
 

45 has shifted gears since 1999 and we continue to do it today. We've progressed from using the standard FIRST provided gearboxes for shifting to designing our own custom shift on the fly transmissions (used in 2002 and 2003).

2003:
http://www.chiefdelphi.com/pics/bin/...99dscf1904.jpg (expect a white paper this summer)

2002:
http://www.chiefdelphi.com/forums/pa...gle&paperid=78 (our first shift on fly design)

2001:
http://www.chiefdelphi.com/forums/pa...gle&paperid=21 (back to back motor design)

2000:
http://www.chiefdelphi.com/forums/pa...ngle&paperid=9 (149669 download(s) :yikes: )

Well, we weren't a division winner, but we were division finalists. We used a custom 2-speed transmission on the CIM motors, just like we used last year.

Our robot was able to shift on the fly. If was really effective, expecially when teams that didn't scout robots, thought that we were only speed and no power. We had a high-speed gear and a low gear at a 3 to 1 ratio. Even though we didn't win, we had a eliminations appearance, a semi-finals twice, and we were a #1 seed in galileo.

We were the finalists at 2 regionals and the semi-finalists in our division at Nationals.

For the past few years we have mounted servos overhead of the drill motor's gearboxes.

It seems to work fine once you find all the bugs ;) ;)

We had shifting capabilities, but we found that we could push most robots simply by building momentum in high gear. By backing up and ramming, we were able to knock even suctioned robots off the ramp.

I see many people here saying "We didn't win, but...."

The author specifically stated people that won a regional. The fact that you shifted and still didn't do well, complements the arguments of the people who are against shifting. You're digging yourself into a hole here.


If you look at all 3 national winners, none of them shifted. Obviously an optimized non-shifting robot is far superior to a shifting robot. Less that can go wrong.

I disagree (somewhat). Just because the winners didn't shift doesn't mean that the best robots are those that don't shift. While the winning robots were all incredible machines, there is more to winning than simply your robot (for example skill and experience of driver).

We were winners along with 25 & 102 at rutgers & i don't believe any of us shifted. 25 used 4 motors for both speed & power. We along with 102 both went with good speed, good traction, & 1 gear. Sometimes, having less to think about can be better. The only times torque to speed change could have helped was getting to the stack, & getting to the top. The thing that really made a difference was a teams ability to do an auto-mode well, or even consistant. And knowing how long it would take to get on top.

shifting
 

When we won the Central Florida Regional, our robot couldn't run in our high gear (We also changed the transmission 11 times but thats a different story). For chiago and nationals we were able to shift on the fly.

254 shifts
 

This year team 254 shifted. We used servos to shift the drill transmissions. In low gear we went about 3ft/s and in high we went about 9ft/s. We made it up the hill during auton from 3.5-3.8 seconds. We won SVR (with 115 & 852) and were the finalists at Sacramento (with 599 &256). However, our partners did not shift at either event. At Nats, we paired up with 27 & 192. 192 shifts as well, but I believe 27 does not. We made it to the semifinals.
Last year (I know this is about this year) we used a shift-on-the-fly transmission with 1.5ft/s in low and 13ft/s in high that coupled the drills and the CIMs.

662 does not shift and we were part of the winning alliance at Sacramento. We are geared for about 9 fps. I think that we would have done better at the championships if we were geared lower or could shift.

Team 647 did not shift this year but we are working on it for next year. We won lone star and were quarter finalist in the Archimedes Division.

294 was a regional finalist but we did not shift gears. There are several reasons for this. One: We used our servos as shelves in our stackers. Two: If we were in high gear, if we could get enough torque to move, we would still go FAR to fast (I'm talking about 30fps).

IRON LYONS Team 912 - Canadian Regional Champions (this was the 2nd-annual Canadian Regional) along with rookie Canadian team 1088 S. W. A. T. T. and Delphi-sponsored 378 The Circuit Stompers.

Our robot, S. D. L., does not support any gear-shifting; we had our motors set to low gear all throughout.

I think it was more the strategy of our alliance's robot combination that took us to the top. 378's was one of those that could be classified as fast and compact; it went up the ramp in autonomous real fast and real smooth, spanning the entire width. 1088's was a slow-moving ultra-torque-&-traction-loaded brick that could bully any bot it wanted to. 912's (ours) was a mediocre bot that had pretty decent torque and speed that could stack, re-orient, and bulldoze with a front-arm that goes down.

378 was reliable for autonomous, 1088 was reliable for king-of-the-hill, and 912's bot partnered up with our skilled driver, made it strategic in both offensive and defensive play.

The rule of thumb, therefore, I suppose, is to have a combination alliance consisting of slow, mediocre (but ability to multi-task), and fast robots. (one of each type).

Verdict: No need for gear-shifting! ;) Although I think 378 had support for it, they were always menacing around in top-speed, so I don't believe they ever used it much.

may I ask a slightly different question?

how many teams out there (besides 45, everybody knows about them) shift gears while using a 4-motor drive? (and did it work reliably?)

We, the Techno Ticks, did not shift either.

Team 753 did not use a shifting mechanism. We found 6-7 feet per second and a drill/atwood drive to have more than enough power (we were able to spin our tank treads when pushing against a wall!) and enough speed to be effective.

We won the Pacific Northwest Regional, along with 368 and 233.

We had great success at St. Louis with out a transmission, but it could have been useful. In the end having a lot of traction with our 13" wheels and an even mix of torque and speed worked out. I'm a believer that if you have the means and a good design a transmission is the way to go.

We used a version of Team 45's shifter with the CIM's and BOSCH on each side using a pneumatic shifter. We won in Great Lakes and we were Semi-Finalists at Buckeye. To date there have been no failures on the transmissions and almost no signs of wear on the gears either. We modified the design a bit to use off the shelf gears and will definately use it again. Our failures this year were all tied to the brecoflex belts, we tore 8 this year in half including 4 of the solid center rib belts.

Next year we think we can make it much smaller, half as heavy and we are looking into other methods to shift other than the air cylinder.

Thanks for the info. If you don't mind my asking,
a) Did you ever have a problem with drawing so much juice from the battery that you lost power temporarily?

b) Why do you want to use something other than the air cylinders for shifting?

c) Since weight is always an issue with us, how do you plan to make your gear box smaller?

No Problem Doug,

a.)First, the gear ratio worked pretty well such that in high we had plenty of speed and power and we never drew so much that we had a power problem at all this year. Along the same line, next year we will make a specific left and right gearbox to keep the drills rotating the same direction to keep left right performance identical. Ratios:

From Drill to CIM Drill (Think it was 16 tooth to 48 tooth) welded to a 16 tooth and pressed onto the CIM motor. CIM mated to a 50 tooth gear which also drives a 20 tooth gear, output gears were a 50 tooth for high and a 80 tooth for low.

b.)Why would you want to use something other than air? Well our robot wasn't using the pneumatic system for anything else except for shifting this year, and if it was we ate at least one cylinder of the four for shifting some teams used two. Shifting with the 45 transmission can be done with a very light push or pull so I am looking into using a spring loaded linkage similar to a gas RC car throttle so that the servo will go to it's preset position and apply spring force until the shift is engaged. By using only 1 cylinder we also used up valuable space in the chassis for the linkage of the two transmissions. All in all it works fantastic as it is but I think we can get the same performance in a smaller lighter package (Team 45 also shrunk theirs this year)

c.)Weight & Size - The first thing to do is to look at the gear ratios. The final output stage was 1:1 in high and 4:1 in low with the High output gear an 80 tooth 20 pitch fairly heavy gear. Rather switch to 2:1 in high and 1:2 in low. We will get rid of the three finger dog mates and mill the mate into the output gears like 45 did this year. All of the heavy steel gears will not only be drilled but also the web between the hub and the teeth will be reduced considerably. The gears all start as solid steel with a large steel hub. To remove weight always look to the steel first for the biggest bang for the buck. Also for construction of the gearbox we will use some of the info gained from Team 111. Notice in many of their designs the nice 90 degree break on all of the flat plates, our gearbox plates were all 1/8" and all of them are wavy from the forces applied to them this year

Truly a wonderful design Team 45!

188 didn't shift (a shiftless lot we are), but we did have more than enough torque, with 6 motor drive. we were chosen in two regionals (finalist alliance CR, champ alliance WMR) and the Finals (qf only, Curie)

We were planning to shift, but didn't need it, and so rebuilt the gear box in a few days.

I'm actually somewhat surprised nobody noticed that our robot (469) had a transmission. It ran a drill and a CIM on each side (4 motors total). This is our third year with a transmission, and our second with a custom box.

The reason I'm so surprised is that our transmission had a 7:1 split. We avoided using our high gear much in the finals becuase we bent a driveshaft in our division semis, and at high RPM it threw the chains off the sprockets. We used high gear mainly for the autonomous portion in the finals, and low gear for the rest of the match. The unusually huge split in the transmission was nice, becuase we were pretty fast in high, and powerful in low.

The problem we encountered was that at our first regional, we were snapping shafts (1/4" hardened steel I believe). Once the problem was fixed, the actual transmission gave us no more trouble. However, the cantelievered output shaft was another story . . .

I think our transmissions have been a key part of our robot design for the past few years. Every game has an aspect where speed is necessary, and another where power is needed. Once the kinks are worked out, transmissions can be a very powerful feature.

Jeff Alpert
Team 469

No shifting for #171. The main reason that we won the St. Louis Regional was our working autonomous mode which many teams did not have.

We won the Arizona regional with just the drill motors.

In LA we added 2 more motors and a technokat inspired shift-on-the-fly transmission.

In LA we ended up seeded 1st without any practice matches (all Thursday we were adding the gearboxes and never got to go out on the field.)

We ended up in second place overall after losing to team 60's alliance in the final match.

I felt that the transmissions were extremely valuable. We would not have done as well as we did if we still had just the drill motors.

I also felt like our transmission was more reliable than the drill motors and the drill motor gearbox. We had some problems with the plastic drill motor gearbox and housing, and with our transmission, that problem was eliminated by not using it and gearing down the drill motor to match the rpm of the CIM motor.

If done properly I think a 2 speed (or more) transmission is very helpful.

For example, we rarely used high gear aside from the 15 sec autonomous period and the rare occasions where we needed to get across the field quickly.

BUT, that 15sec mad-dash to the top was essential this year! We were able to go 14fps and make it up to the top of the ramp (when our auto mode worked right) before most other teams, while still having alot of torque once we shifted into low.

We, 343, designed two systems. The first was a shifting drill motor system, the second a CIM/Drill combo that didn't shift. The combo didn't make the weight limit with our stacker so for our first regional we went with the shifting drills. Lost the quarterfinal because one of the transmissions slipped. We dropped the shifting and the stacker and went with the single speed CIM/Drill combo for Peach Tree and Nationals. At Peach Tree we tried a different track material and it changed traction all through the first day of competition, really messed up our autonomous. We made it to the finals. At nationals we went back to the original tracks, stayed with the dual drive no shift and finished top seed in Curie, won the division with 25 and 494 and went on to play in the finals.

Blizzard was supose to have shifting gears... But we had problems so we ditched it...

Canadian Regional Finalist
West Michigan Regional Winners

Miss Daisy, winner of the Galileo Division, is completely 2-speed free.

I think that our most useful robot ability was having a flawless autonomous mode. Our speed was medium, but that was perfect when it came down to staying on the ramp and pushing others off.

That's not to say that having multiple speeds is a bad thing... Team 341 plans to design one pretty soon. I personally feel that having anything but a multiple-speed drive will eventually become extinct (or something like that).

Team 322 used a two speed planetary gear box with 6 motors.

Winner Pittsburgh

Finalist Great Lakes Regional

Quarter Finalist West Michigan.

Semi-Finalist Currie Division.

368
 

team 368, mckinley was seeded 1st in Silicon valley, (regional finalist)
seeded 5th in the seattle, and regional winners
had a shift on the fly 4 motor transmission(technno cats design)
we were able to push almost any robot around with the exception of 254, (cheesypoofs) when they had their anchor down.

i was the robot controller, but when i drove around, i drove in high gear, (practice rounds)
and i flew over the ramp and dented another robot (sorry millilani)


we were able to clear out alot of the boxes in other zones because of the second gear

Team Rush 27 won the Buckeye Regional, runnered up in the Great lakes Regional, seeded #2 in the Newton Division and lost in the semifinal round.

We are a Bosch/Atwood combo planetary shifter trans bot. The trans was extremly durable this year. We had one of the fastest Auton modes in FIRST at 3.1 seconds to the top of the ramp and had plenty of pushing power.

Ours is a shift on the fly using pneumatic cylinders for crisp shifting. I posted a couple of JPEGS in the Gallery a few months back.

I wouldn't say the transmissions alone were the reason for our success this year. It was a combination of a durable chsis design, a strong arm mounted to a turret, pneumatic wheels, and having 6 wheel drive with the center wheel articulating up and down. :cool: