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-   -   2 Speed Transmissions in the Future (http://www.chiefdelphi.com/forums/showthread.php?t=57355)

=Martin=Taylor= 07-05-2007 22:10
Re: 2 Speed Transmissions in the Future
 
The assumption here also seems to be that tank-drive wheeled robots are the future of FIRST.

Omni and meccanum are barely controllable in low gear. Swerve drives are complex enough without the addition of multiple speeds. Track-drives have a tendency to throw belts at high speeds...

Not that these drive systems are incompatible with 2-speeds, its just that most teams are unlikely to build them.

There are other-ways to improve drivetrian usefulness then to add another gear...

Bharat Nain 07-05-2007 22:35
Re: 2 Speed Transmissions in the Future
 
The use of 2-speed transmissions has gone up a lot since AM came out. I think the reason they are used widely is because they are so readily available. Some teams decide to custom-build theirs and do a decent or excellent(254/968) job on it. I think the use of 2-speed gearboxes is going to go up in the years to come. FIRST has encouraged defense in the past 2 years and 2-speed transmissions are one way to face the challenge. I don't think they are going to change the rules because defense on the field is good to see within limits. Swerve drives, crab drives(45, 116, 1114 and so on..) etc are very cool but they are also complex to build and very time-consuming. That is why teams stick to tank-drive and do very well in competition. It also matters what a teams goals are when building a robot. Some build purely to win competitions while others build for the "cool" factor. Some are good at both and some have neither. 2-Speed transmissions will go a long way because they are ease to buy and install. They are also very effective.

114Klutz 08-05-2007 00:46
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by Rex114 (Post 625267)
I think that if FIRST keeps pumping out games with the same relatively flat field with maximum of 30? inclines to climb, you will see more and more 2 speeds. There just isn't a challenge for teams to design anything besides a basic 4"-8" diameter, 4 or 6 wheel drive train. Its related to the arms race thread, but on a broader scale. Most teams wont try to make a V6 or anything like that, but with all the previous designs out there, a 2 speed isn't that much of a stretch for any semi-experienced team.

And there are teams out there that have almost reached perfection as far as 2 speeds go. 254/968 has the most elegant and thought out drive train I have ever seen. And it helps that they have had at least since 2004 to work out their design. I'm not quite sure if you can get any better than a 1.4 pound 2 speed gearbox (great job Travis btw) and I would doubt their entire drive train came out to be over 35 pounds. Thats 85 pounds to do whatever else you want to do with the robot! Being the one who is always working on arms/manipulators, it would be nice to be able to make something without having to worry if the drive train is gonna take up all of the robots weight.

In short, yes, as long as games continue to have fairly repetitive field layouts, 2 speed will become better and popular-er (is that a word? :p)

Mike C.
More popular. But indeed, the issue with two speed gearboxes is now not mechanical skill or cost, both of them are now remedied by AndyMark.

The question is now, is it actually needed? For example, this year showed little advantage to be gained by using a two speed gearbox. The field was not open, and the two sides next to the rack could easily be blocked by opposing machines. I do not believe it was worth the time and weight to implement a two speed gearbox.

The second issue is - how easy is the gearbox to implement? Manpower is a significant issue. While AndyMarks are rather simple to implement - it may require the addition of subsystems, such as pneumatics, which might not be viable if time is short. Custom gearboxes are notorious in this respect - ours went over the deadline significantly. While this was fixed, it took time away from some other projects.

My personal preference has always been to eschew shifting - because it simply is complicated and time consuming. However, if two speeds actually does give a substantial advantage in game - then by all means, go for it.

Gabe 08-05-2007 00:52
Re: 2 Speed Transmissions in the Future
 
The use of any drivetrain will depend entirely on the game. As long as FIRST has a field with no serious obstacles, then 2-speeds will gain popularity. Although I was not there, the 2004 challenge didn't really seem to favor multi-speed transmissions because on top of the platforms there was no need for the high speed, with very little room to maneuver. If there is any serious obstacle the driver must slow down (except for the few who try to fly). The more obstacles, the fewer opportunities there are for the driver to use the fast speed. I know FIRST is itching for an obtacle field, so plan accordingly.

AdamHeard 08-05-2007 01:06
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by 114Klutz (Post 625346)
The question is now, is it actually needed? For example, this year showed little advantage to be gained by using a two speed gearbox. The field was not open, and the two sides next to the rack could easily be blocked by opposing machines. I do not believe it was worth the time and weight to implement a two speed gearbox.
I know several teams who would entirely disagree with you based on the success they had this year. I had to play defense first hand on 254/968 and 330 on many occasions... What made them stand out over other teams was their driver's ability to evade and maneuver in high gear, and resist pushing in low gear.

These are just first hand examples, I'm sure many other teams that were offensive robots can thank their success on the extra edge their drive gave them. 1114 and 1270 from curie are another two. Also, 45 and 1902 in Galileo used them well.

I think what is more important than perceived game environment is whether or not the driver can effectively utilize the advantage.

Usually the added cost in weight and work is minimal compared to not using them. I wish we had used shifters this year; They would actually weigh less than the 3 motor workaround we did and would be just about as complicated to install.

I.U.man_22 08-05-2007 08:30
Re: 2 Speed Transmissions in the Future
 
Two speed transmissions are great in FIRST. Our Team used a two speed pneumatic shifter this year. The best success for two speed transmissions is to use a pneumatic shifter.

Alan Anderson 08-05-2007 09:01
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by Gabe (Post 625347)
...the 2004 challenge didn't really seem to favor multi-speed transmissions because on top of the platforms there was no need for the high speed, with very little room to maneuver. If there is any serious obstacle the driver must slow down (except for the few who try to fly). The more obstacles, the fewer opportunities there are for the driver to use the fast speed...
One of my favorite tools for out-of-the-box thinking is to turn things around the other direction. In this case, you seem to be implying that the purpose of a second speed is to go faster. But it's just as reasonable to have a "normal" driving speed plus a second slow speed, used for extra torque when needed. Instead of a medium-speed robot that can switch into a higher gear to zip across the field quickly, consider a medium-speed robot that can switch into a lower gear to hold its ground or push others out of its way.

If the playing field is open, high speed tends to be an advantage. If the field is congested, pushing power tends to be an advantage. Both situations are well served by a shifting transmission.

Greg Needel 08-05-2007 11:29
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by Gabe (Post 625347)
I know FIRST is itching for an obstacle field, so plan accordingly.
State your source.

Brandon Holley 08-05-2007 11:32
Re: 2 Speed Transmissions in the Future
 
I'm seeing a lot of talk here about the 2004 game...

Imagine the 2004 game....with 2 more robots on the field....MADNESS

The sides of those platforms would get quite crowded, and that was with only 4 bots around the field!



I have no idea what relevance this has with the rest of the thread.

Greg Needel 08-05-2007 11:34
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by Brandon Holley (Post 625410)
I'm seeing a lot of talk here about the 2004 game...

Imagine the 2004 game....with 2 more robots on the field....MADNESS

The sides of those platforms would get quite crowded, and that was with only 4 bots around the field!



I have no idea what relevance this has with the rest of the thread.

Even better...think about 6 robots trying to hang at the same time...:ahh:

Gabe 08-05-2007 11:46
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by Greg Needel (Post 625409)
State your source.
No outside source, just a gut feeling after looking at the history of challenges over the years. Just imagine how much more trouble driving would be with an obstacle as simple as a 2 by 4 laid flat on the ground.

Lil' Lavery 08-05-2007 15:54
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by Gabe (Post 625416)
No outside source, just a gut feeling after looking at the history of challenges over the years. Just imagine how much more trouble driving would be with an obstacle as simple as a 2 by 4 laid flat on the ground.
Yes, but there were never more than 4 robots on the field at a time during that history of previous challenges. If alliances remain 3v3 (+), I don't see a 2000 hill/trough structure, 2001/2003 divider bar, 2003 ramp, or 2004 platform coming back. The 2005 goals and 2007 rack were plenty impeding enough with 6 robots on the field.

EricH 08-05-2007 20:04
Re: 2 Speed Transmissions in the Future
 
Quote:
Originally Posted by RyanN (Post 625217)
I would think that FIRST could get with some company to manufacture parts for a 2 speed transmission so that the total cost of each transmission is less than $50 each. Our 2005 and 2006 2 speed transmissions were custom made by us and they were very reliable, and I would say that the materials in it did not go over $30 per transmission.
OK, material cost $30. Now, how long, in man-hours, did it take to build each transmission? Now, take that number and figure a minimum of $10 per man-hour. (Which, by the way, is a very low-paid machinist.) Now, do you see why trannies are so expensive? Oh, and throw in a bit for design, while you're at it.

The cost for a transmission (no profit margin) is: materials+labor+overhead (electricity, etc.).

JesseK 09-05-2007 11:06
Re: 2 Speed Transmissions in the Future
 
I think in some instances it could be better for the team overall to figure out HOW to make a 2-speed transmission in their offseason, regardless of what next year's game could be. The fact that the mechanical team learns what it takes to design and manufacture a complex dynamic system with any sort of quality will take them alot further through the season than if they did not. They can translate that knowledge into building dynamic manipulators (etc) for whatever game is thrown at them.

That said, one of our team's offseason projects for the fall is to make a 2-speed prototype transmission. Details haven't been worked out yet, but we know that our '07 robot could have had more maneuverability or power had we been able to shift this year, hence that is our D/T improvement for next year.

If a team has these transmissions available in the KoP's, then they will hardly (if ever) be motivated to take steps in designing and creating their own. Hence, I don't think 2-speeds should be in the KoP. The BB gearbox worked for 1885 in 35 matches + practice this year and allowed us to focus our efforts on other parts of the robot. I believe that is sufficient for the expectations a team should have for the kit of parts -- nothing more.

CraigHickman 09-05-2007 18:18
Re: 2 Speed Transmissions in the Future
 
I have a feeling you'll be seeing a lot more 2 speeds in the upcoming games. With the growth of FIRST, the probability is fairly high that the field will remain decently open. However, a 2 speed can be very useful even if there is an obstacle.

Also, the 2 speed is becoming even more viable for the average team. I currently have a design that should be prototyped soon(ish) of a sub $100 tranny, designed specifically for 6 inch wheels.


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