View Full Version : Wheel Diameter of Mecanums
xForceDee
25-11-2013, 12:07
During my experience with FIRST, I have observed teams using several different wheels for their drive trains. One thing I have noticed is that teams with mecanum wheels generally choose large diameter wheels (8" or above) while teams with non-mecanum wheels choose generally smaller wheels (4"-6"). I am wondering what the reasoning behind this is. Obviously if you can get the same angular velocity on a larger diameter wheel, then that results in a greater linear velocity of the robot but besides that, I don't understand the advantages of choosing larger wheels, specifically the reason for not choosing the 6" versions offered by Andymark (http://www.andymark.com/product-p/am-0732.htm)and Vex (http://www.vexrobotics.com/vexpro/wheels-and-hubs/mecanum-wheels.html). Does the size increase improve the mecanum's performance in some way? Do smaller mecanum wheels have a greater tendency to break?
Having used both 6'' mecanums and 8'' AndyMark mecanums extensively, I've had far better results with the former, both in terms of performance and quality of the product.
I don't know why anyone would specifically go for larger mecanum wheels; this past year 4464 used 8'' AndyMark mecanums because they were donated, but we honestly would have done better to just buy a set of 6'' given the problems we've had with them.
I look forward to trying out 4'' mecanums (probably in an octanum setting) when they (likely) become available.
Having used both 6'' mecanums and 8'' AndyMark mecanums extensively, I've had far better results with the former, both in terms of performance and quality of the product.
Could you please give more detail about what you mean by performance and quality in this context?
I don't know why anyone would specifically go for larger mecanum wheels; this past year 4464 used 8'' AndyMark mecanums because they were donated, but we honestly would have done better to just buy a set of 6'' given the problems we've had with them.
What kind of problems did you have with the 8" wheels that you did not have with the 6" wheels?
BBray_T1296
25-11-2013, 14:02
We always used 6" mecanums. Even in 2012 while crossing the bump (http://www.youtube.com/watch?v=jl8pHpCjQtY). They are by far and away lighter and massively smaller profile than the larger variants. The large mecanum wheels also don't look near as cool
Could you please give more detail about what you mean by performance and quality in this context?
In my experience, 6'' wheels run smoother (less vibration) and track straighter while strafing (in the absence of a gyro).
We also had several defective 8'' mecanum plates, and one of the backup wheels we purchased was so deformed that not a single roller could turn since they were all in contact with their neighbors. They're also heavier, and the rollers jam far more often.
I've had no quality problems with the 6'' models, ever, nor any major issues with their performance since 2008 (when the plate was flimsy and required constant maintenance to keep it from bending in on the rollers).
Brandon Zalinsky
25-11-2013, 15:48
Could you please give more detail about what you mean by performance and quality in this context?
I'd just like to add my two cents on this.
We used 8" AndyMark mecanum wheels in 2010. We wrecked two sets over 7 events, after the constant bashing from climbing over the bump. I have no comparison for the 6 inch, as we didn't try those, but draw your own conclusions about the 8" wheels' durability.
Can anyone attest the the 6" VexPro mecanum's durability as opposed to the AndyMark ones? We'd like to try those this year.
BBray_T1296
25-11-2013, 16:14
In 2011 we used the standard AM 6" mecanum wheels. In 2012, we used the HD wheels, due to the bump and related forces (even though after calculations, the standard wheel specs would not have been exceeded). After 2 regionals and an offseason, and extensive testing (our first year using mecanums) in 2011, we did not, and still to this day, have not replaced any of the rollers on the wheels. On our 2012 robot, after our 2nd regional we had to replace about 10 rollers, some from each of the 4 wheels. This was probably not due to any difference between the standard and HD wheels, but likely due to slight skidding on the ramps and testing on linoleum floors that wore down the rubber rollers over time.
I have not used any VexPro mecanum wheels, but I would trust the construction of the plastic plates, because of the rigidity other plastic VexPro products (ballshifter housing, versa-wheels). I do not know about the rollers on those wheels, but if they are similar in tread to a Versa-wheel, I would be careful and monitor the tread wear on your mecanum rollers. Damaged and missing tread will cause your robot to "hobble" as it bounces every time the wheel reaches the missing spot. Remember, a mecanum wheel is not a circle, it is a N-gon. With a missing vertex, irregularities occur. This will make actions such as strafing behave a little weird.
We wrecked two sets over 7 events, after the constant bashing from climbing over the bump.
Could you please describe in a bit more detail what you mean by "wrecked"?
e.g. the plates got bent, or the roller axles got bent, or the rollers got chewed up, etc
Remember, a mecanum wheel is not a circle, it is a N-gon.
It is possible to design a mecanum wheel whose profile is a true circle. For anyone interested you can find more info here (http://www.chiefdelphi.com/media/papers/download/2777), here (http://www.chiefdelphi.com/media/papers/download/2749), here (http://www.chiefdelphi.com/media/papers/download/2751), here (http://www.chiefdelphi.com/media/papers/download/3187), and here (http://www.chiefdelphi.com/media/papers/download/2770).
We used the 8-inch AndyMark ones and we were impressed. The wheels allowed us to not only move nicely and freely, but also allowed us to push other robots and sideload them! Our drivetrain was quite effective. On the other hand, I saw many teams with ginormous mecanums. I, myself, cannot understand why they did that. It only seems like more weight and it takes a lot of room! :confused:
MichaelBick
25-11-2013, 19:09
We used the 8-inch AndyMark ones and we were impressed... On the other hand, I saw many teams with ginormous mecanums. I, myself, cannot understand why they did that. It only seems like more weight and it takes a lot of room! :confused:
Why didn't you use 6" mecanums then?
BBray_T1296
25-11-2013, 19:13
It is possible to design a mecanum wheel whose profile is a true circle.
This is true. And the VexPro wheels are a good example. The problem arises when one (or more) rollers is removed (physically or due to wear), suddenly you have a round wheel with a flat spot. Like a train wheel.
http://www.tsb.gc.ca/eng/rapports-reports/rail/1996/r96t0095/r96t0095.jpg
(someone had a bad day)
Well, we tried the 8 inch wheels and they went past our expectations. So, we just stayed with that! :D
Also, how does that happen to a train wheel? Does it go, Thump...Thump...Thump...?
Why is it red hot? :D
Well, we tried the 8 inch wheels and they went past our expectations. So, we just stayed with that! :D
Having used both, I would recommend you at least consider the 6'' models, if only for the significant weight decrease.
I will talk to our team captain about that!
The funny thing is that every Wednesday (robotics day), I enter the classroom and blast the mentor and the captain with outrageous ideas:D. That's just me, the curious one :D
BBray_T1296
25-11-2013, 19:31
That's just me, the curious one :D
edited for truth: That's just you, the team Chief Delphi prowler.
edited for truth: That's just you, the team Chief Delphi prowler.
Yeah. I agree. However, it should be the curious Chief Delphi prowler! I have been going through every post, but have been posting a little less these days ;), especially because finals are coming :(
Yeah, and those lines of green faces have disappeared!
:D :D :D
^^Let that be an exception^^
artdutra04
25-11-2013, 19:35
Also, how does that happen to a train wheel? Does it go, Thump...Thump...Thump...?
Why is it red hot? :DRarely do train wheels get that bad, but there have been several times I've ridden on commuter trains (Metro North and MBTA) that have minor flat spots. At 80mph, it sounds like tick-tick-tick-tick-tick-tick-tick-tick-tick and feels like someone keeps tapping your chair. Generally they are only noticeable on track that has continuously welded rail instead of the outdated 39ft sections (which itself makes the old clickity-clack sounds).
Lol, I wonder how bad it is in India! Most of the transit is by trains, and with the meagre funds and little income, I am pretty sure they do not do much maintenance, especially in the regular cabins, without even an A/C ^~^ (Crabby face. CD is missing that :() :D
I thought most trains can easily handle those speeds!
BBray_T1296
25-11-2013, 19:41
^ (2 posts up [artdutra04]) you are a VEX engineer, surely at some point you guys compared the leading competition's (AndyMark) products to your own, to create a competitive product. Obvious bias aside, what do you personally think is better?
(and don't worry, your opinion is safe here)
I have no preference. I just get what I need as long it will get the job done to my requirements and standards (As high as the sky)!
Brandon Zalinsky
26-11-2013, 08:04
Could you please describe in a bit more detail what you mean by "wrecked"?
e.g. the plates got bent, or the roller axles got bent, or the rollers got chewed up, etc
The plates were bent all out of shape and the bolt "axles" that we had bent and broke. Most of them were fixable, but with more resources than those that are available to teams at a competition, such as a large finger brake.
pfreivald
26-11-2013, 09:29
We switched from AM 6" to VEXPro 6" last year, and here's what we found:
VEXPro wheels are lighter, every bit as durable, and drive pretty much the same.
We switched from AM 6" to VEXPro 6" last year, and here's what we found:
VEXPro wheels are lighter, every bit as durable, and drive pretty much the same.
Silly question: do VEXPro and AndyMark have the same mounting configurations? That is to say, can we use AndyMark hubs with VEXPro wheels without modifying either?
Silly question: do VEXPro and AndyMark have the same mounting configurations? That is to say, can we use AndyMark hubs with VEXPro wheels without modifying either?
The mount pattern is the same. (6 Size 8 holes on a 1.875” circle). I don't know how well they work together though.
xForceDee
26-11-2013, 10:25
Thanks everyone for your input so far. It seems like many of you claim that not only 6" wheels just as durable and effective, but in some cases even more so. This sort of surprises me a little bit, but I guess my viewing experience is limited to only a couple regionals and some YouTube videos. I do have one additional question to ask. I have heard (and seen) that a four wheel configuration does not turn very well in a long drive base. I am curious as to how the wheel diameter would affect this capability in a long mecanum setup. Watching this video (http://www.youtube.com/watch?v=mKcHXxC8aJY), it seems like AndyMark has a setup that turns admirably well in a long configuration on 8" wheels.
Tmaxxrox97
26-11-2013, 10:46
Can anyone attest the the 6" VexPro mecanum's durability as opposed to the AndyMark ones? We'd like to try those this year.
As a team that used these wheels this year they are great as long as you don't misuse them. Ie. Drive them on black top or other non-smooth surfaces. They are much lighter, drive the same and are worth using.
Silly question: do VEXPro and AndyMark have the same mounting configurations? That is to say, can we use AndyMark hubs with VEXPro wheels without modifying either?
The mount pattern is the same. (6 Size 8 holes on a 1.875” circle). I don't know how well they work together though.
You can use the Andymark hubs if you modify the wheels slightly. In order to make the hub butt up against the wheel side plate you will need to sand off the little nubs that are designed to connect to the Vex Versahubs.
BurkeHalderman
26-11-2013, 11:00
Silly question: do VEXPro and AndyMark have the same mounting configurations? That is to say, can we use AndyMark hubs with VEXPro wheels without modifying either?
As mentioned above the mounting pattern is the same (6 holes spaced evenly on a 1.875" circle) however the pattern on VexPro products are designed for a #8 bolt while the pattern on AndyMark products are for a #10 bolt. So an AM hub on a VexPro wheel might not be completely centered, unless the wheel is bored out for a #10 bolt.
I have heard (and seen) that a four wheel configuration does not turn very well in a long drive base.
If the mecs are designed, manufactured, assembled, and mounted properly, and the vehicle allows each of the 4 wheels to touch the floor with sufficient force to prevent slipping, a long drive base should work fine.
We are switching vex because it is lighter, as previously mentioned. They are mask of abs (mostly), so they are strong.while staying light
wilsonmw04
26-11-2013, 13:46
We are switching vex because it is lighter, as previously mentioned. They are mask of abs (mostly), so they are strong.while staying light
Can you show me where you got this data?
It didn't sound right to me so I checked the websites:
Vex 6": 1.33 lbs
http://www.vexrobotics.com/vexpro/wheels-and-hubs/mecanum-wheels.html
AM 6": 1.3 lbs
http://www.andymark.com/product-p/am-0136L.htm
Thanks!
Can you show me where you got this data?
It didn't sound right to me so I checked the websites:
Vex 6": 1.33 lbs
http://www.vexrobotics.com/vexpro/wheels-and-hubs/mecanum-wheels.html
AM 6": 1.3 lbs
http://www.andymark.com/product-p/am-0136L.htm
Thanks!
That didn't seem right, so we threw some on the scale:
6" VEXpro Mecanum Wheel: 1.25 lb
8" VEXpro Mecanum Wheel: 1.90 lb
Note, this includes the internal threaded standoffs used for mounting a sprocket or hub onto the wheel.
I'll have our guys update the website.
holygrail
26-11-2013, 14:22
We really liked the 6 inch VEX Pro mecanums this year for the most part. However, after 2 regionals and championships and several demos, they decided to eat themselves. Within two weeks of each other rollers started breaking off of 3 of the wheels. During one demo, 10 of the 12 rollers broke off of one of the wheels in rapid succession. It made for a clunky performance, but we gave the rollers to the kids we were demoing for as souvenirs. Since our robot looks like a rabbit, we just called the rollers "droppings."
We had to replace all 4 wheels before Cowtown Throwdown. It would have been devastating if it had happened during competition though.
That said, I have generally been very impressed with the products that VEX Pro puts out and I plan to continue usung their products regularly.
AdamHeard
26-11-2013, 14:25
We really liked the 6 inch VEX Pro mecanums this year for the most part. However, after 2 regionals and championships and several demos, they decided to eat themselves. Within two weeks of each other rollers started breaking off of 3 of the wheels. During one demo, 10 of the 12 rollers broke off of one of the wheels in rapid succession. It made for a clunky performance, but we gave the rollers to the kids we were demoing for as souvenirs. Since our robot looks like a rabbit, we just called the rollers "droppings."
We had to replace all 4 wheels before Cowtown Throwdown. It would have been devastating if it had happened during competition though.
That said, I have generally been very impressed with the products that VEX Pro puts out and I plan to continue usung their products regularly.
Were these demos on a non-flat non-carpeted area?
It'd be nice if all wheels are great on all surfaces, but with something as funky as mecanums I'd certainly be happy with merely lasting great on flat, carpeted surfaces.
During one demo, 10 of the 12 rollers broke off of one of the wheels
? Where did the 12 number come from
holygrail
26-11-2013, 18:25
Were these demos on a non-flat non-carpeted area?
It'd be nice if all wheels are great on all surfaces, but with something as funky as mecanums I'd certainly be happy with merely lasting great on flat, carpeted surfaces.
This particular demo was on a flat gym floor. No carpet, but once one fell off the rest were doomed because of the additional strain on the rollers.
holygrail
26-11-2013, 18:31
? Where did the 12 number come from
I dont have one of the wheels in my hand right now, but I believe there are either 10 or 12 of the diagonal rollers on each of the wheels. All but two broke off.
As for where the number twelve came from, that goes back to some ancient paleolithic people that had one more than eleven of something and had to come up with a name for it. Just a guess. :D
bbradf44
29-11-2013, 21:45
We use 6in AM just because they're cheaper then the 8in and we were tight when we got them. Haven't had any issues
So, we are debating about 6 inch or 8 inch mecanums, I think! I really think 8 inch wheels are ideal. They aren't massive, nor are they small. You wan't a balance. That will allow you to get the best out of both worlds! If you have too big of a wheel, it will be heavy, and wouldn't have as high of a torque. If you had too small of a wheel, you would have a high torque, low speed drivetrain. This can all be compensated for within the transmission! If you have a smaller wheel, it would need to turn faster. Wouldn't that mean that the rollers would be turning faster, meaning more maintenance would be needed? If the rollers are turning faster, doesn't that mean that a greater consistency between wheels would be needed to keep the robot from strafing?
AndyMark should make 7 inch wheels :cool: ;)
If you have too big of a wheel, it will be heavy, and wouldn't have as high of a torque. If you had too small of a wheel, you would have a high torque, low speed drivetrain. This can all be compensated for within the transmission! If you have a smaller wheel, it would need to turn faster. Wouldn't that mean that the rollers would be turning faster, meaning more maintenance would be needed? If the rollers are turning faster, doesn't that mean that a greater consistency between wheels would be needed to keep the robot from strafing?
AndyMark should make 7 inch wheels :cool: ;)
What constitutes "too big?" What constitutes "too small?" Do you have any actual data or experience on the performance of different wheel size that indicates that 8'' is the "proper size?" Your mention of 8'' as being a "balance" in the absence of any empirical justification seems more like anchoring (http://en.wikipedia.org/wiki/Anchoring) than anything else, and your anchor here seems fairly arbitrary.
The first effect you mentioned (roller speed resulting in more wheel maintenance) is completely marginal; most of the wear on your wheel is most certainly not going to be wear from the rollers rolling, and besides I can attest that haven't had to do any serious maintenance on a mecanum wheel of any size since AndyMark's thin-plate 2008 6'' models. The second effect doesn't, in general, match my observations - 6'' have always seemed to strafe far better for me than 8'', though I admit this is likely confounded by center-of-mass placement on the robots I've worked with. Perhaps someone could actually test this, if they've got a practice frame and some time on their hands?
What constitutes "too big?" What constitutes "too small?" Do you have any actual data or experience on the performance of different wheel size that indicates that 8'' is the "proper size?" Your mention of 8'' as being a "balance" in the absence of any empirical justification seems more like anchoring (http://en.wikipedia.org/wiki/Anchoring) than anything else, and your anchor here seems fairly arbitrary.
The first effect you mentioned (roller speed resulting in more wheel maintenance) is completely marginal; most of the wear on your wheel is most certainly not going to be wear from the rollers rolling, and besides I can attest that haven't had to do any serious maintenance on a mecanum wheel of any size since AndyMark's thin-plate 2008 6'' models. The second effect doesn't, in general, match my observations - 6'' have always seemed to strafe far better for me than 8'', though I admit this is likely confounded by center-of-mass placement on the robots I've worked with. Perhaps someone could actually test this, if they've got a practice frame and some time on their hands?
No. I haven't played around with the wheel diameter. This is just stuff that seems true, especially when you are at competition, watching a team with 6 inch wheels driving, with their wheels turning at 500 RPM, whereas you can beat them running your 8 inch wheels running at 400 RPM. Also, when you have more moving parts, and when your moving parts are moving even faster, more maintenance is required. Yes. I agree it is marginal, but it can be noticeable, to an extent. We never had to worry about our mecanums during competitions, but there were teams who were fixing theirs. I could test the effect of moving the center of gravity on my Vex OmniBot. It isn't mecanum, but something similar. I can just place a weight on it, move it around, and see how the drivetrain reacts to the weight! Also, I did not say that 8 inch is balanced. I said, pick the wheel diameter that is in the middle, to get the most out of bot worlds. In this case, it would be 7 inch. However, you can disregard that because AndyMark doesn't sell 7 inch mecanum wheels!
No. I haven't played around with the wheel diameter. This is just stuff that seems true, especially when you are at competition,
First rule of engineering: Use your gut to make decisions ONLY when you don't have the numbers and cannot afford to wait until you get them. Ditto for saying "That seems like it'll work" and not applying numbers.
Also, just because omni and mecanum are similar does not mean that one can be used to prototype the other. They won't behave exactly the same, and the frame setup is vastly different.
And just to go one step further: Those teams working on their mecanums during competition. Are you sure they were maintaining the rollers, and not repairing chain, or installing encoders, or retweaking side plates, or any one of a number of other repairs that might not be related to the wheels at all, but be near the wheels? And forgive me for doubting this, but are you absolutely sure that you didn't have some worries about your mecanum wheels? The one time I had a set of competition mecanum wheels, we had two worries, and both were so minor they were fixed within minutes, not taking long at all--not long enough to let the code recompile once we got the parts in--but we spent a lot of time working around them, near the arm.
Also, I did not say that 8 inch is balanced. I said, pick the wheel diameter that is in the middle, to get the most out of bot worlds. In this case, it would be 7 inch. However, you can disregard that because AndyMark doesn't sell 7 inch mecanum wheels!
Again, this is reliance on an arbitrary anchor. 6'' and 8'' happen to be the sizes of wheel that are commonly sold - unless you have a firm reason to think that 6'' are "too small" and 8'' are "too big," your judgment here that 7'' wheels would be "ideal" has little to do with the actual properties of different-sized mecanum wheels, and rather is just a product of the numbers you've been presented with.
If you want to make good design choices, you need to be able to recognize this sort of arbitrary judgment and try to minimize it. If you have firm evidence that 8'' mecanums are more reliable than 6'', then that should factor into your decision - having worked with mecanums for many years now, I will note that I have not observed this to be the case. What you've put forward as your reasoning, however, does not seem to me to be well-founded, and I suggest you re-examine it.
BBray_T1296
30-11-2013, 02:53
On our robots we used 6" wheels with one ratio of a toughbox nano (I actually don't know the ratio). I know we were getting over 12fps out of them. We only had to change rollers once on one robot after skidding up the Rebound Rumble ramps one match. We had not much wear other than that after 2 regionals for both of our robots running mecanum. We used the 6" standard in 2011, and the 6" HD in 2012. I would recommend both. They both worked well, and performed exactly as we wanted them to.
Of course I have never ran 8" wheels, so I am obviously going to be biased away from them, but seeing as torque/rpm can be compensated for in a slightly different geared (but exactly same size/basically same weight) gearbox, the 6" wheels are themselves lighter than 8" wheels, and a 6" wheel drive-train will by definition take up less room on the robot
On our robots we used 6" wheels with one ratio of a toughbox nano (I actually don't know the ratio). I know we were getting over 12fps out of them. We only had to change rollers once on one robot after skidding up the Rebound Rumble ramps one match. We had not much wear other than that after 2 regionals for both of our robots running mecanum. We used the 6" standard in 2011, and the 6" HD in 2012. I would recommend both. They both worked well, and performed exactly as we wanted them to.
Of course I have never ran 8" wheels, so I am obviously going to be biased away from them, but seeing as torque/rpm can be compensated for in a slightly different geared (but exactly same size/basically same weight) gearbox, the 6" wheels are themselves lighter than 8" wheels, and a 6" wheel drive-train will by definition take up less room on the robot
As far as I remember, our mecanums outperformed what we were expecting and required little, if any maintenance. We placed quite some stress on our wheels, especially when we were defending (Most people say that mecnums cannot defend, but we were able to), and our wheels didn't fail upon those stresses. Also, we didn't fall all the way to the ground on our 30 point climbs! I really think that the thought of Mecanum wheel diameter is more-or-less, what everyone thinks. There is no "perfect" size.
Again, this is reliance on an arbitrary anchor. 6'' and 8'' happen to be the sizes of wheel that are commonly sold - unless you have a firm reason to think that 6'' are "too small" and 8'' are "too big," your judgment here that 7'' wheels would be "ideal" has little to do with the actual properties of different-sized mecanum wheels, and rather is just a product of the numbers you've been presented with.
If you want to make good design choices, you need to be able to recognize this sort of arbitrary judgment and try to minimize it. If you have firm evidence that 8'' mecanums are more reliable than 6'', then that should factor into your decision - having worked with mecanums for many years now, I will note that I have not observed this to be the case. What you've put forward as your reasoning, however, does not seem to me to be well-founded, and I suggest you re-examine it.
Sorry about that. I am not interested in wasting others' and my own time in arguments. My idea of 7" wheels was an average between 6 and 8. But, let's just forget about that ;).
First rule of engineering: Use your gut to make decisions ONLY when you don't have the numbers and cannot afford to wait until you get them. Ditto for saying "That seems like it'll work" and not applying numbers.
Also, just because omni and mecanum are similar does not mean that one can be used to prototype the other. They won't behave exactly the same, and the frame setup is vastly different.
And just to go one step further: Those teams working on their mecanums during competition. Are you sure they were maintaining the rollers, and not repairing chain, or installing encoders, or retweaking side plates, or any one of a number of other repairs that might not be related to the wheels at all, but be near the wheels? And forgive me for doubting this, but are you absolutely sure that you didn't have some worries about your mecanum wheels? The one time I had a set of competition mecanum wheels, we had two worries, and both were so minor they were fixed within minutes, not taking long at all--not long enough to let the code recompile once we got the parts in--but we spent a lot of time working around them, near the arm.
Thanks. That is a great idea. I am not saying that they will act exactly like mecanum. I am saying that they will act similar to mecanum. That's why my OmniBot can try climbing walls and flip itself over, whereas, the mecanum robot would just sit their, gnawing at the wall! We may have once-in-a-while, greased the rollers, but we never had to do anything large, like replacing rollers or wheels! The only worries about our mecanums were when we were facing team 1717. With their state-of-the-art swerve, they were able to push us continuously, and pin us down. It seems as though if the ten-second rule didn't exist, and if they didn't have so good of a sportsmanship, we would have lost some mecanums! I believe that we brought with ourselves, an extra set of mecanums, just of in case something happened. The AndyMark mecanums worked well outside too. We had no problems in driving it around a concrete sidewalk (We were driving it outside for a presentation).
Sorry for the long post :yikes:
MichaelBick
30-11-2013, 15:53
Thanks. That is a great idea. I am not saying that they will act exactly like mecanum. I am saying that they will act similar to mecanum. That's why my OmniBot can try climbing walls and flip itself over, whereas, the mecanum robot would just sit their, gnawing at the wall! We may have once-in-a-while, greased the rollers, but we never had to do anything large, like replacing rollers or wheels! The only worries about our mecanums were when we were facing team 1717. With their state-of-the-art swerve, they were able to push us continuously, and pin us down. It seems as though if the ten-second rule didn't exist, and if they didn't have so good of a sportsmanship, we would have lost some mecanums! I believe that we brought with ourselves, an extra set of mecanums, just of in case something happened. The AndyMark mecanums worked well outside too. We had no problems in driving it around a concrete sidewalk (We were driving it outside for a presentation).
Sorry for the long post :yikes:
1717's swerve isn't any more powerful than a tank drive. In fact, I would bet our 6wd has more pushing power considering it has 6 motors and 2" wide wheels.
Yes. Tank drive would give good power and traction, however, swerve would give them traction and maneuverability. Whenever someone tried to stop us, we could drive sideways and confuse them. In this case, they could follow us with their swerve!
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