|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
|
|
Thread Tools | Rate Thread | Display Modes |
|
|
|
#1
|
|||||
|
|||||
|
Re: AM' swerve modules
If AM were to sell a complete swerve module...
...Would it not fall under the following? Quote:
Granted, you'd need 3-4 modules, but I could sure point out that all you need is one for steering... Why are the AM gearboxes, etc, not violations of this? Because you could use a Supershifter or a Gen 2 on your arm or intake. It would take more engineering, but it can be done. Gear ratios still have to be calculated. If AM sold a crab module, assembled or not, the team would bear the responsibility of showing that it had been designed into the robot's design. After a bit, teams would stop buying because of this (or because they prefer to make their own). Not exactly a profitable business venture. There are two further things that I would like to note: 1) the rules may change for next year and 2) this paragraph has been the same for just about as long as I can remember. |
|
#2
|
||||
|
||||
|
Re: AM' swerve modules
Quote:
good point Eric...... that could be a problem ![]() |
|
#3
|
||||
|
||||
|
Re: AM' swerve modules
Any team that says they simply don't have the resources to be able to make a swerve drive is deceiving themselves. This year the ausTIN CANs, team 2158, made a 3-wheel swerve drive completely out of 3/8" lexan, using a band saw, drill, and a jigsaw. It was plenty sturdy for this year's competition, and the modules never gave us any problems, it was the motors that we were using (i.e. back to the control part). We decided to use the two FP's and one BB motor for the drive, and the Banebots caught fire 4 times throughout the competition. Over the summer, we're redesigning the system to use CIM's with continuous rotation (this year's modules only rotated 270 degrees), also primarily out of lexan and made completely by hand, that can stand up to forces of a 120-pound robot reversing direction at full speed with high-traction wheels on carpet. We already have a design, and all of the parts look to be checking out. It CAN be done no matter what team you're on, and with what resources.
I will reemphasize the issue of control, also. We steered the modules independently with the two Nippon-Denso window motors and one globe motor. The window motors jammed many times before we could get them aligned correctly, and we had to replace the globe motor when the mounting screws sheered off and jammed themselves into the holes of the gearbox. To measure the angle, we had a 10-turn potentiometer on each wheel that meshed to the module with band saw-made 3/8" lexan gears (a small one for the pot shaft and a large one as the entire top part of the module). By not declaring the location of the pot inputs correctly, we ripped wires off the robot several times when the modules started rotating out of control. Not to mention, when centering the modules (take the gear off the pot and turn it slightly until the module rotates to center, then center the pot again and put the gear back on), my hand has been sucked into the robot. There was much blood, and I still have a scar. That gives you an indication of how precarious having a ton of moving parts on your robot can be. Controlling swerve drive is not all about trigonometry. The point of FIRST is not to have a level playing field. There are always teams out there with way more money and resources than your team ever will. The point of FIRST is to learn something and utilize the skills that your team DOES have to beat those teams. Selling a complete swerve module would probably detract many teams from their skills and make them think they would win if they just used swerve drive. If it's not in your repertoire, your team should either focus on getting it in your repertoire (i.e. LEARNING how to MAKE swerve drive), or focus on something you're already good at (like driving regularly). |
|
#4
|
|||
|
|||
|
Re: AM' swerve modules
I'm all for it.
We should try to raise the floor, not lower the ceiling. |
|
#5
|
|||||
|
|||||
|
Re: AM' swerve modules
Quote:
didnt want to resort to this ![]() |
|
#6
|
|||||
|
|||||
|
Re: AM' swerve modules
Quote:
![]() |
|
#7
|
|||||
|
|||||
|
Re: AM' swerve modules
Have you seen the new FP Planetary Gearbox?
|
|
#8
|
||||
|
||||
|
Re: AM' swerve modules
I would say that something like this could have its advantages. The problem of making a specific swerve module does present itself, this is a little too specific to really sell for a first competition. However, I could easily see AM selling a generalized turret module because whenever I would thing of making a turret, or swerve this was always the area that I got hung up on.
Don't get me wrong, i'm never a fan of standardizing any piece of the robot. I always built a custom frame when I was a student on a team, this was one major reason that I was never a fan of the kit bot. I was always disappointed when I walked into a team pit to find that they had used the kit frame cause I didn't get to see anything new. But to see the other side of the argument, I've been working on computer vision and specifically motion tracking on a mobile platform. The overall idea of the algorithms behind this task (ie. optical flow, image segmentation) are well within my grasp as a sophomore in college. However, I could never apply the linear algebra or the mechanics of the algorithms behind these, which is why I turn to libraries like Opencv which has the mechanics already finished for me. Yes I could learn a lot from writing my own mean shift segmentation on an image, but if I use the library I can write some very cool code much faster. In the same way, if AM offered a swerve module a team could get a working robot much faster and perhaps be able to implement some very cool control algorithms. |
|
#9
|
|||
|
|||
|
Re: AM' swerve modules
One thing that hasn't been mentioned is actually interfacing such a product with team designs. How would such a module be designed to be mounted on a team's frame, given the great variety in design and construction techniques between teams? I don't think it would be possible to make a module that fits the size, cost, and mounting constraints of enough teams to make it a commercially feasible venture.
|
|
#10
|
||||
|
||||
|
Re: AM' swerve modules
Quote:
When the test is effectively "I know it when I see it", the inspector doing the inspecting should be allowed to be flexible about the interpretation. Generally speaking, the most equitable way to enforce loosely- (or worse, poorly-) constructed rules is to give the teams the benefit of the doubt. Plus, even if a COTS assembly was intended for use in FIRST competitions, and provided a complete solution for a major robot function, and was thus impermissible, it could still provide a function that could be used in many different ways, rendering it acceptable. There's no priority given to one condition or the other, so which is it: legal or illegal? If the "rule" isn't a rule (in the usual sense), is blatantly unclear, and enforcing it requires a judgment of the designer's intent, I don't see any way that this can be reasonably and consistently applied over the range of possible COTS parts. That's different from being a safe bet, however: FIRST may think that there's no confusion, and act accordingly. The economics of the situation look good, though: charge $250 per module, and sell some accessories that can be arranged in several different configurations (like different motors, different wheels, or mounting strategies), and you've got a winner. |
|
#11
|
|||
|
|||
|
Re: AM' swerve modules
So, why aren't the andymark mechanum wheels against the "spirit of the competition" but a swerve module is? After all, by using AM mechanum wheels teams learn nothing about machining, CNC usage, roller molding, etc.
Same thing with the gearboxes. (This isn't directed at anyone in particular, just a general question) At some point you have to draw a line, what's the justification for putting it here? And what other things are prohibited by the same logic? |
|
#12
|
|||||
|
|||||
|
Re: AM' swerve modules
General answer: A set of mecanum wheels is not a "full mobility system". A set of swerve modules could be, or not, depending on how complete they are. A gearbox is not.
Using the examples in the rule is probably a reasonable way to evaluate it. |
|
#13
|
||||
|
||||
|
Re: AM' swerve modules
Quote:
As for rather it's in the spirit of FIRST I say it really just depends on the team. Some teams will have the resources to build a swerve drive and others will not. An Andy-Mark solution would not be the best choice for everyone anyways, so there would be plenty of teams building their own swerve drives. In fact I would hazard a guess that most teams that currently build swerve would keep building their own since they have it pretty much down pat. Currently you can basically buy all of the components you need from AM to build a robot without doing any machining.(Wheels, gear boxes, and kit frame.) So I don't see the harm in adding a swerve module. In fact, I can see the argument being made that having such a thing available could be better for creativity and the design process. It adds another area of thinking into design. "Do I invest the time and effort into designing and build a subsystem to my exact specifications, or do I spend money, save time, and attempt to use an off the shelf product not specifically designed for my machine?" Whether it would be economically feasible for AM to do it is a whole other story. Can't imagine swerve modules would be cheap to produce. |
|
#14
|
|||
|
|||
|
Re: AM' swerve modules
I'm all for AM to sell the swerve/crab/snake drive kits. I don't think that the basic kit would fall into the "COTS for FIRST only" there are lots of other roboteers that buy stuff from AM.
A few posters pointed out that the hard parts are not the swerve drive but the mounting onto the robot and the control system, and I agree. I don't see anything wrong with buying a part to make some robot assembly go faster. It's how its done in the "real world", COTS over custom, COTS wins a lot of the time. When we first started out we traveled to Canada each summer to hand dig 50 tons of aluminum ore and 100 tons of coal. Our grant from Alcoa gave us access to their smelters. We turned our coal into electricity and used it to smelt our ore into a thousand pound aluminum billet. We then machined the billet into the parts we needed for the robot. With a small team this left little time to do detailed design or control systems. Since then we've relied on suppliers like AM and McMaster. This has freed up lots of roboteer time to work on design, assembly and control systems. And it's paid off, our robot this year did not need any major repairs in the pits and we won an award for our design and control system. We did look at swerve drives for this year and instead built our 6+1=3 drive that worked very well. But it would be nice to have a swerve drive option that we could bolt into place and spend the more important time of integrating it into the system. |
|
#15
|
||||
|
||||
|
Re: AM' swerve modules
Let's think, for practicality's sake, about 'what IF' AndyMark DID make a generic swerve module. Let's think for just a second about the risk involved. AM put their shifting transmissions out, and for a time they sold well...that is, until 2009 rolled around. AM learned this year just what kind of impact niche products have on their ability to roll through inventory in FRC. How many teams bought Super Shifters this year? What if FIRST releases a game in the next couple of years that negates any need for a crab/swerve module in the future? The risks are great, whereas their efforts could be spent in other areas that FRC teams need. I for one am a fan of the hex bearing they recently put out ... such a small innovation that opens up a world of design for custom gearboxes built from COTS AM parts.
Besides, teams need to be able to create the partnerships necessary to manufacture something as complicated as a crab/swerve module. If you venture out, 30, 50 miles even just to find the right CNC'er or Waterjet facility then that's a relationship you'll use in other aspects of your bot -- not just the drive train. I say this because recently found a guy with a waterjet who's 20 miles away who we will negotiate a deal with for next year's bot. It took years to find him, but we finally did. Had we been given the items we needed for that particular robot piece this year, we wouldn't have even bothered looking for that relationship. Finally, upon attending 118's crab module conference in Atlanta, then seeing the multitude of very different designs that were in Atlanta (111, 118, 88, 548, 1885, and several others), one would have realized that there is NO one-size-fits-all solution to crab design. There are too many design parameters, too many external systems effected, and on top of that many decisions have to be made for control that also effect how the crab module is designed in the first place. Last edited by JesseK : 23-04-2009 at 12:42. |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| cRIO unused Modules | marisaDKNY | Electrical | 2 | 07-02-2009 16:58 |
| pic: 254/968 Swerve Modules! | Travis Covington | Robot Showcase | 52 | 23-02-2008 09:47 |
| VEX Swerve Drive Modules are Here! | Chuck Glick | General Forum | 3 | 12-11-2006 21:40 |
| Using CCP modules | steven114 | Programming | 7 | 13-02-2006 12:43 |
| RF Modules | archiver | 1999 | 1 | 23-06-2002 22:06 |