8 MINI-CIM SWERVE [Archive]

Kevin Ainsworth

26-09-2014, 14:58

nuclearnerd

26-09-2014, 15:22

I'm not averse to the rule change, especially if limiting total power is the aim of the rules. 8 mini cims ~= 6 cims.

The performance gain might not meet your expectations though. A tank drive will be better at putting that power to the ground (in a straight line anyway). When accelerating or pushing, the bot will "squat" toward the back wheels. As the weight comes off the front wheels, the force they can apply may become traction-limited, rather than power-limited. In a tank drive the front wheels and back wheels are chained together, so the weight distribution doesn't matter, but in a swerve drive, those front motors may spin uselessly.

The math on how big an effect this is is left as an exercise for the reader :)

Nuttyman54

26-09-2014, 15:23

I disagree 100% that there needs to be any rules allowing 8 Mini-CIM motors.

For one, there's already an incredible amount of power in the kit. The more motors, the more opportunity teams have to overload the system.

Part of the FIRST challenge is choosing how to allocate resources and weigh different design options. There's no requirement that any teams use a swerve vs 6wd vs mecanum vs ball drive vs walker. Each team must make a choice based on what their objectives are. Nobody's arguing that a walking robot should have special rules to allow them more motors so they can perform equivalently to a 6wd, or that a ball drive should be allowed 20 extra pounds because it's heavy. It's a design consideration that comes with choosing a swerve drive, you are probably trading some drive power to get the extra maneuverability. If you think 6wd has an advantage over swerve because it has much better acceleration, make a 6wd.

Lastly, it is possible to get 6 CIM power with swerve-style drive, but you can't do it with a module swerve. Concentric swerves that distribut power from two (or even one) gearbox to multiple swerve wheels but are steered independently is a way to do it.

Aren Siekmeier

26-09-2014, 15:28

Why does the number of motors need to be divisible by 4?

These types of drive are already very common. I think there's more room for creativity when you are forced to distribute 6 motors evenly, or use 3/4 motors more efficiently. And Z3 symmetry presents another challenge compared to Z4, since there are no proper subgroups.

Also 8 MiniCIMs would leave no room for additional 40A circuits, which wouldn't be fantastic if we need to do any heavy-lifting outside the drivetrain.

Lil' Lavery

26-09-2014, 15:36

Where's the option for "No, the motor allowances are already overkill"

Jon Stratis

26-09-2014, 15:38

nuclearnerd

26-09-2014, 15:45

We already have more power available than needed. Allowing even more would just serve to make things hit that much harder, break that much quicker, and overall decrease our purpose here. I'd rather we saw less motor power and fewer things breaking from impacts!

I'm not against this idea either, but the problem as stated is that the rules give hard numbers for each type of motor, regardless of application. You could theoretically have a 6-Cim + 2 mini-cim drive which would be completely legal, but cause far more of the impacts you're afraid of. What's being proposed here is a more nuanced application of the rules to allow teams more flexibility in choice of motor, without increasing the maximum power output. That sounds sensible to me!

nuclearnerd

26-09-2014, 15:56

This could be calculated by adding the watts of all motors used with a not to exceed. Or even more simply a CIM=1 and a MINI-CIM=.66 or .75 and a maximum of 6 when added up.

This kind of formula would even allow the GDC to dial back the maximum total power equivalent (TPE) if they wanted to (as some commenters propose). Hypothetically backing down the limit from 6, to say, 5, would result in *less powerful bots*, but still allow teams to use the following combinations (for example):

4-Cim (divisible by 2 and 4, TPE = 4)
6-Mini-Cim (divisible by 2, 3 and 6, TPE = 4.5)
2-Cim + 4 Mini-Cim (divisible evenly by 2 only, TPE=5)
8-9015 motors (divisible by 2, 4, and 8, TPE=~4.8)

Oblarg

26-09-2014, 15:58

And Z3 symmetry presents another challenge compared to Z4, since there are no proper subgroups.

I chuckled.

Of all the things to describe with group theory, I must confess drive base configurations hadn't occurred to me.

Max Boord

26-09-2014, 16:10

Where's the option for "No, the motor allowances are already overkill"

Overkill is underrated.

The robot I drove in season had a 6 cim powered shooter (flingapult) 4 mini cim mecanum drive and 3 banebots to pickup. 8 mini cim drive would have been truly awsome.

8 mini cims would allow all 6 cims to be used on mechanisms and still be able to have a strong omni drive. 6 cim + mini cim tank drives would be breaker trippers in most cases.

nuclearnerd

26-09-2014, 16:20

6 cim + mini cim tank drives would be breaker trippers in most cases.

Not with this year's PD board, and the ability to do closed-loop current monitoring :)

Max Boord

26-09-2014, 16:41

Not with this year's PD board, and the ability to do closed-loop current monitoring :)
Good point. Although something tells me figuring out the exact tripping curve of a given main breaker at a given temperature would make a closed loop system very complex. Also, if your are limiting power on your 6 cim+ 2 mini cim drive why wouldn't you go with a simple 6 cim (and software limiters)? With 6 cims only providing a 20-30% acceleration boost over 4 cims, i can't really see how adding mini cims would be much of a gain in top speed or acceleration, not to mention the added complexity of custom or additional COTS gearboxes.

Electronica1

26-09-2014, 17:44

EricH

26-09-2014, 19:17

How would you fit two motors inside a wheel?

You'd use one to drive the wheel and one to turn the module.

Electronica1

26-09-2014, 19:27

You'd use one to drive the wheel and one to turn the module.

But that would not allow you to have similar power to a 6 cim tank drive, which is the point of the 8 mini-cim argument right? (I might be missing something) You could have more than 4 modules in order to match the 6 cim power I guess.

AdamHeard

26-09-2014, 19:32

But that would not allow you to have similar power to a 6 cim tank drive, which is the point of the 8 mini-cim argument right? (I might be missing something) You could have more than 4 modules in order to match the 6 cim power I guess.

You could do a swerve using those fancy mercury free mechanical slip rings (http://www.vexrobotics.com/217-3344.html) and put the motors where they belong (external to the module), and easily do 2 per wheel.

Max Boord

26-09-2014, 19:38

How would you fit two motors inside a wheel?

6 inch wheels. Baxter Bomb Squad already uses them and it would give you 1/2 inch of clearance on ether side. How the gearing would work is a totally different story.

You could do a swerve using those fancy mercury free mechanical slip rings (http://www.vexrobotics.com/217-3344.html) and put the motors where they belong (external to the module), and easily do 2 per wheel.

But THIS (http://www.chiefdelphi.com/media/img/6ba/6ba0b020d9b26f4d0c8e6804b9d5395c_l.jpg)

EricH

26-09-2014, 20:15

But THIS (http://www.chiefdelphi.com/media/img/6ba/6ba0b020d9b26f4d0c8e6804b9d5395c_l.jpg)

But this nuttin'. Try one of THESE (https://www.youtube.com/watch?v=h3l6Xqts4to)! (Just swap the FPs for more CIMs.)

It's not about more/less points of contact with the ground, or about how much power you can put into the drivetrain, or how much traction a given wheel has. It's the balance of all of the above. I don't think that adding two more motors will do all that much--just make ya more likely to be traction-limited instead of torque-limited.

Tyler2517

26-09-2014, 20:24

But this nuttin'. Try one of THESE (https://www.youtube.com/watch?v=h3l6Xqts4to)! (Just swap the FPs for more CIMs.)

It's not about more/less points of contact with the ground, or about how much power you can put into the drivetrain, or how much traction a given wheel has. It's the balance of all of the above. I don't think that adding two more motors will do all that much--just make ya more likely to be traction-limited instead of torque-limited.

Look at what happen with the change from 4 cim drives to 6 cim drives. They are classes of there own.

Max Boord

26-09-2014, 20:31

But this nuttin'. Try one of THESE (https://www.youtube.com/watch?v=h3l6Xqts4to)!

Upgraded. (http://youtu.be/6fLf71xlVhE?t=1m20s)

JesseK

26-09-2014, 21:06

2 extra motor controllers, 2 fewer available 40A ports on the PDB - 8 Mini CIMs vs 6 CIMs is a lose IMO.

nuclearnerd

26-09-2014, 21:15

2 extra motor controllers, 2 fewer available 40A ports on the PDB - 8 Mini CIMs vs 6 CIMs is a lose IMO.

For me too, but If another team decides they would rather have all 40A circuits going to the drive, and only use lower power circuits for the rest of the bot, why should the rules keep them from making that trade-off on their own?

JesseK

26-09-2014, 22:27

For me too, but If another team decides they would rather have all 40A circuits going to the drive, and only use lower power circuits for the rest of the bot, why should the rules keep them from making that trade-off on their own?

Drive trains are easy to build. Without understanding the fundamentals, drive trains are very hard to perfect as part of a greater robot with other mechanisms. I feel that increasing the amount of power through to the drive trains is a cop-out low & mid-tier teams who don't bother to try to perfect their drive train. I'd much rather the GDC limit total electric power through the drive train if there were any rule changes in that respect. It would force the trade-offs to be actual engineering decisions rather than "BIGGER IS BETTER RAWR!1".

On top of that, I feel that anyone who mentions 6 CIMs as what led to success in an anecdote should have a gigantic caveat stickied across their post. I don't know about the exact wording, but perhaps it could say something like
Dear FRC participant, 6 CIM drive trains (or 8 MiniCIMs) may lead to some nice zippy acceleration if you "like to go fast". Yet here are some side effects you should consult your robot engineers about: Your drivers keep getting penalties for high-speed ramming Your robot "passes out" for about 30 seconds after getting into a pushing match Your batteries from last year's competition no longer hold a charge for the entire match Your other motor-driven subsystems are noticeably slower towards the end of a match The tread constantly strips off of your wheels when merely grazing another robot Your aluminum output shaft shears The chains snap apart at the master link or eat the teeth off of the sprockets after a quick reverse
These were witnessed, BTW.

Full disclosure, 1885 took a beating by powerful drivetrains at champs this past year. Getting double-teamed as a single-speed 11ft/s drive train got very aggravating very quickly. We endured, had some great matches and I know what to do for next year. We even had our very first actual zero-maintenance and very agile drive train this year across 4 competitions. Hopefully I've presented this in such as way that shows more thought has gone into it based upon several years of drive train design experience, rather than a single competition's worth of bias.

Oblarg

27-09-2014, 01:18

On top of that, I feel that anyone who mentions 6 CIMs as what led to success in an anecdote should have a gigantic caveat stickied across their post.

4464 used a 6-CIM drive last year, and I'd be the first to add caveats when we talk about the success it brought us (I've detailed the problems we encountered several times on these boards), but it is important to recognize that every single problem you've mentioned is something that can be either mitigated or avoided completely with proper diligence.

Yes, a young, inexperienced team naively going "MORE IS BETTER!" and mindlessly adding motors to their drive can easily do more harm than good, and designing a 6 CIM drive in a way that doesn't run into the mentioned problems is nontrivial (we had to swap our gearing before champs last year, and it wasn't because we hadn't put a lot thought into the gearing we originally had), but I don't think that every 6 CIM success story is necessarily ignoring or downplaying the negatives, or overstating the positives.

SoftwareBug2.0

27-09-2014, 01:28

Lastly, it is possible to get 6 CIM power with swerve-style drive, but you can't do it with a module swerve. Concentric swerves that distribut power from two (or even one) gearbox to multiple swerve wheels but are steered independently is a way to do it.

There are no limits on the number of swerve modules allowed. How about six?

EricH

27-09-2014, 01:44

There are no limits on the number of swerve modules allowed. How about six?

Winnovation already did that one. As I recall... they had a remarkable run that year, and then decided afterwards that they just might have made a mistake. (This was coming from a team that made it to Einstein with a 6-wheel swerve, if memory serves.)

The mistake in question, as I recall, was something to the effect of "Ya know, we didn't REALLY need a 6-wheel swerve for this game."

Chadfrom308

27-09-2014, 01:49

It would be hard and heavy to make us a 4 CIM, 8 Mini-CIM mechanum drivetrain. But, not impossible.

We will just keep adding motors to our drivetrain until we blow a breaker just by accelerating:yikes:

EricH

27-09-2014, 01:58

This little challenge has been posed before, but I think it's worth posing again.

Use every motor allowed (or as many as needed) in ONE gearbox. This gearbox could then shunt power to any use on the robot--drivetrain, shooter, arm, intake, whatever--via gears and belts. Imagine having 6 CIMs, a bunch of 775s and/or 550s, the full complement of BAGs, and some PG71s all powering drivetrain... or arm... or whatever...

This is, after all, the sort of thing used to power machine shops in the way olden times: one power source, every tool has a belt off of that source and a clutch to disengage itself...

RyanShoff

27-09-2014, 22:57

http://gallery.marswars.org/2014-build-season/JWG_3784.JPG.php

Our swerve was originally setup for 1 cim and 1 mini-cim per module. Ultimately we ended up cutting off the extra spot. Mostly because we wanted to use slip rings and not worry about ripping up wires.

asid61

27-09-2014, 23:19

8 mini-cim swerves would be pretty cool, but thinking about it, what advantage does more mini-cims allow?
A swerve drive that is compatible with 2 mini-cims is probably compatible with a cim and a mini-cim, because the mounting and speeds are similar.
So I don't think adding more mini-cims would be useful.

asid61

27-09-2014, 23:23

This is, after all, the sort of thing used to power machine shops in the way olden times: one power source, every tool has a belt off of that source and a clutch to disengage itself...

"In olden times" being the key word. I saw a thread on Practical Machinist a couple days ago showing a shop from the 1850's being powered up today, with the spindle running overhead.

I think it would be possible to do the shunting power method you suggest. And it would be super cool. But it would be easier to use 3 gearboxes; 2 for drive (6 cim + 4 minicim) and 1 for endgame and manipulators (4x RS-775 18v).

jman4747

28-09-2014, 11:10

Good point. Although something tells me figuring out the exact tripping curve of a given main breaker at a given temperature would make a closed loop system very complex. Also, if your are limiting power on your 6 cim+ 2 mini cim drive why wouldn't you go with a simple 6 cim (and software limiters)? With 6 cims only providing a 20-30% acceleration boost over 4 cims, i can't really see how adding mini cims would be much of a gain in top speed or acceleration, not to mention the added complexity of custom or additional COTS gearboxes.

This.

I don't see how anyone could ever get an advantage from actually using near all allowable motors even now, and I don't think the OP is saying that's the sort of design this encourages. Allowing more motors in this context is to allow more options. Sure you could build two 3 cim 4 mini-cim gearboxes for each side of a tank drive but you're not going to get to use all 3782 watts. Extremes aside... in reality reducing motor restrictions wouldn't change much as the physical and hardware constraints make using all allowed power imposable. As stated before the context is more options and maybe it's doesn't need to be exactly this but I think FRC could use some more variety.

Lil' Lavery

28-09-2014, 11:46

JesseK

28-09-2014, 12:32

This.

I don't see how anyone could ever get an advantage from actually using near all allowable motors even now,

Just because the advantage looks relatively small does not mean it doesn't have major impacts on gameplay. Do a few comparisons of speed vs distance while accelerating and it easy to see that 'mere' 20-30% quickly converts into much higher energy impacts since the energy imparted is proportional to the square of the velocity. These will inevitably occur more often during gamely since they don't require much room for the acceleration.

The advantage then becomes "find the robot who can't do much on offense and which has 6cims, then tell them to go push the other robots around. If they hit the opponents enough, maybe the opponents will just stop working and then we can win".

Oblarg

28-09-2014, 12:42

Just because the advantage looks relatively small does not mean it doesn't have major impacts on gameplay. Do a few comparisons of speed vs distance while accelerating and it easy to see that 'mere' 20-30% quickly converts into much higher energy impacts since the energy imparted is proportional to the square of the velocity. These will inevitably occur more often during gamely since they don't require much room for the acceleration.

The advantage then becomes "find the robot who can't do much on offense and which has 6cims, then tell them to go push the other robots around. If they hit the opponents enough, maybe the opponents will just stop working and then we can win".

Or, in more legitimate terms, if you hit them enough they will find it hard to position themselves to accomplish game tasks.

I think it is unfair to characterize tough defense as "hitting people with the hopes their robot breaks." We played defense a lot this past year, and our goal in robot-robot contact was never to cause damage. Good defense is about being in the right place at the right time and knowing how to interact with the robot you're trying to defend against, not simply hitting them as hard as possible. Having additional motors definitely helps with this, both by allowing you to push for longer when needed without tripping a breaker (especially if your opponent cannot do the same), and by allowing you to get to where you need to be faster (and, as a lot of defense is stop-and-go and rapidly-changing, acceleration is critically important for this).

Nick Lawrence

28-09-2014, 13:28

Would any one else like to see (8) MINI-CIM motors allowed so the swerves can be on par with the (6) CIM tank drives?

Looks like an 8 MINI-CIM motor swerve drive would be very close to power and weight of 6 CIM motor 6WD/8WD.

POWER
CIM 6 x 337 watts = 2022 watts total power
MINI-CIM 8 x 230 watts = 1840 watts total power
Within 10% instead of down 50%.

WEIGHT
CIM 6 x 2.80 lbs = 16.8 lbs
MINI-CIM 8 x 2.16 lbs = 17.28 lbs

Seems like the current rules favor a 6 CIM tank over a 4 CIM swerve for acceleration and top speed. I personally would like to see this somehow corrected. Maybe separating BAG motors from the MINI-CIM motors and a allowing 8 MINI-CIM motors?

This could be calculated by adding the watts of all motors used with a not to exceed. Or even more simply a CIM=1 and a MINI-CIM=.66 or .75 and a maximum of 6 when added up.

What's your thoughts?

While I'm all for having as many motors as we can get, I'm not sure I agree with your specific reasoning here. You're asking for more Mini-CIMs based on your team's specific swerve module design. While your swerve was absolutely beautiful and effective, there are ways to have the same power as a 6 CIM traditional 6WD via a coaxial setup. I don't feel that you are at a disadvantage by the rules at all by having a swerve - it was your choice, and the same amount of power is available to you. That being said, I would have to agree with Brendan about having difficulty of putting that power to the ground, even with 8 Mini-CIMS with two per module.

Personally, I would love to see the rules opened up to allow teams to use any number of a few models of motors, and it is up to them to design around tradeoffs of weight and battery consumption. I would never want to see an open field again if we had these rules, however. This year was violent enough.

-Nick

JesseK

28-09-2014, 13:58

Or, in more legitimate terms, if you hit them enough they will find it hard to position themselves to accomplish game tasks.

I think it is unfair to characterize tough defense as "hitting people with the hopes their robot breaks." We played defense a lot this past year, and our goal in robot-robot contact was never to cause damage. Good defense is about being in the right place at the right time and knowing how to interact with the robot you're trying to defend against, not simply hitting them as hard as possible. Having additional motors definitely helps with this, both by allowing you to push for longer when needed without tripping a breaker (especially if your opponent cannot do the same), and by allowing you to get to where you need to be faster (and, as a lot of defense is stop-and-go and rapidly-changing, acceleration is critically important for this).

What I really find striking is that you seem to being saying the point of defense is to hit and that the hits have no "legitimate" post-match impacts to the teams on the receiving end. You also follow that up with saying that more motors allows a team to hit harder, more often and for longer, all in the name of gaining position.

The reality of the season (particularly when examining 4464's video) is that the defender simply wants to use the acceleration to make up for the fact that it screwed up and was already out of position. This was evident even when examining other events' video (which I did a ton of while scouting for Champs) and correlating the teams who won via defense with teams who had 6 CIMs at champs.

The point of this thread, and the counter argument I'm making, is discussing whether or not increasing available power to the drive trains makes sense from a game design perspective. I don't know that you've argued in favor for either so much as you've tried to justify and/or glorify what 6 CIMs can do. Perhaps you could clarify for me?

Oblarg

28-09-2014, 14:27

What I really find striking is that you seem to being saying the point of defense is to hit and that the hits have no "legitimate" post-match impacts to the teams on the receiving end. You also follow that up with saying that more motors allows a team to hit harder, more often and for longer, all in the name of gaining position.

The point of defense is to prevent the opposing robot from completing the scoring task. The easiest legal way to do this is by hindering their movement. Hitting them does just that. There's a reason we have bumpers and the manual every year stresses that robots must be robust.

We did not incur a single penalty this year for overly-rough contact. I take that as pretty firm evidence that we were not causing undue damage to other robots out there. I'm sure we contributed a fair bit to other team's wear-and-tear (after DC we found a nice big dent on our AM14U), and I've made no claim that this isn't a "legitimate" effect, but if FIRST did not want this to happen the rules would not explicitly provide for bumper-to-bumper contact between robots.

The reality of the season (particularly when examining 4464's video) is that the defender simply wants to use the acceleration to make up for the fact that it screwed up and was already out of position. This was evident even when examining other events' video (which I did a ton of while scouting for Champs) and correlating the teams who won via defense with teams who had 6 CIMs at champs.

This argument seems to be along the line of "if you had perfect drivers, the extra acceleration would not be necessary/helpful." Which might be true (I reserve judgement, though I find it dubious), but it's completely irrelevant, because no one has perfect drivers and no one is in the exact right place at every moment.

The point of this thread, and the counter argument I'm making, is discussing whether or not increasing available power to the drive trains makes sense from a game design perspective. I don't know that you've argued in favor for either so much as you've tried to justify and/or glorify what 6 CIMs can do. Perhaps you could clarify for me?

I've made several very specific points as to why 6-CIM drives can be an advantage for certain strategies. In fact, in this response you've pretty much acknowledged one of them (giving your drivers more headroom to make up for mistakes). Moreover, I don't really understand your second-to-last sentence here - what would an argument in favor of 6 CIM drives as a design choice consist of if not "justifying what they can do" for a robot?

You seem to be making a blanket statement that "any team that claims success due to additional motors on their drive is either downplaying the negatives or was trying to damage other robots." I contend that this is clearly false.

Now, there is a discussion to be had about whether or not FRC, as a whole, is better for the move towards bigger and beefier drive-trains, but that is a separate question entirely.

JesseK

28-09-2014, 15:00

You seem to be making a blanket statement that "any team that claims success due to additional motors on their drive is either downplaying the negatives or was trying to damage other robots."

The statement is more like "Any team that claims success due to additional motors on their drive has accounted for the negatives in a single subsystem of their own overall robot and was oblivious to or completely ignored the damage they did to other robots multitudes of subsystems".

The rules allow this. It doesn't meant the rules should allow this. I don't fault 4464 for its defense this year since it was actually pretty clean relative to other matches I've watched.
- You capitalized on it - great, I'm glad your team got to move on
- at the expense of other teams - not so great
- whom you never acknowledged or offered to help afterwards - and here's the point of reducing the allowed power on the drive train. Most defenders didn't care ("undue damage"? Really, we deserved damage?)

To phrase it differently...

There's a very public story from 2007 about one team's entire mechanism, made out of 1/8" tube and securely attached, being ripped out by a defender with a powerful drive train (for that year) after the defender shoved the offensive robot into the Rack. The comment from a ref supposedly was "well the mechanism should have been made stronger". The very well-worded public counter argument was something like "to account for THAT type of defense, it is impossible to make a robust enough mechanism".

The story still applies 7 seasons later. There is no type of "robust", without going to extremes, that can be used to account for the amount of power available to drive trains these days and how teams are choosing to use it.

Oblarg

28-09-2014, 16:00

The statement is more like "Any team that claims success due to additional motors on their drive has accounted for the negatives in a single subsystem of their own overall robot and was oblivious to or completely ignored the damage they did to other robots multitudes of subsystems".

I still think this is overly-strong and not at all necessarily true.

The rules allow this. It doesn't meant the rules should allow this. I don't fault 4464 for its defense this year since it was actually pretty clean relative to other matches I've watched.
- You capitalized on it - great, I'm glad your team got to move on
- at the expense of other teams - not so great
- whom you never acknowledged or offered to help afterwards - and here's the point of reducing the allowed power on the drive train. Most defenders didn't care ("undue damage"? Really, we deserved damage?)

I don't see that our success this year was "at the expense of other teams." Granted, I don't have perfect knowledge or perfect memory, but I try to keep track of how the matches go so I can offer help to teams if their robots are damaged, and I can't think of any matches where our defense caused a lasting problem to another robot that cost them future success, and I certainly would not have advocated for a defensive strategy if I felt that this was an unavoidable consequence of it.

Moreover, "deserved" is a loaded term - rather, there is a certain level of damage that your robot will attain during normal competition that is deemed acceptable under the rules. This has to be the case if robot to robot contact is going to be permitted at all. Designing for and dealing with this is as much a part of the game as building mechanisms to manipulate the game pieces and score points. I do not think our strategy last year went past this standard in terms of impact on other robots.

To phrase it differently...

There's a very public story from 2007 about one team's entire mechanism, made out of 1/8" tube and securely attached, being ripped out by a defender with a powerful drive train (for that year) after the defender shoved the offensive robot into the Rack. The comment from a ref supposedly was "well the mechanism should have been made stronger". The very well-worded public counter argument was something like "to account for THAT type of defense, it is impossible to make a robust enough mechanism".

The story still applies 7 seasons later. There is no type of "robust", without going to extremes, that can be used to account for the amount of power available to drive trains these days and how teams are choosing to use it.

I don't think you can construe the benefit we gained from a 6CIM drive drain as being in this category. We did not benefit because we caused irreparable damage to sturdily-built mechanisms; indeed, I can't think of a time we caused serious damage to any other robot's mechanism.

And, again, whether 6-CIM drives are a good thing for FRC in general is a completely different question from how beneficial they are in robot design.

BBray_T1296

28-09-2014, 16:16

Wouldn't these modules exit the frame perimeter at various points in their rotation?

Looks like yes, but why couldn't they?

cgmv123

28-09-2014, 16:24

Wouldn't these modules exit the frame perimeter at various points in their rotation?

As long as they start inside the frame perimeter, those modules leaving the frame perimeter is legal under the 2014 rules, which didn't have a limit on appendages, just an extension limit (which the modules would not exceed.)

http://frc-manual.usfirst.org/upload/images/2014/1/Figure4-2.jpg

nuclearnerd

28-09-2014, 21:00

The point of this thread, and the counter argument I'm making, is discussing whether or not increasing available power to the drive trains makes sense from a game design perspective. I don't know that you've argued in favor for either so much as you've tried to justify and/or glorify what 6 CIMs can do. Perhaps you could clarify for me?

Actually, the point of this thread was simply whether to allow 8 mini-Cims. The argument "not to increase available power" has nothing to say on this question, given that 8 mini-cims have a smaller TPE than 6 Cims, which are allowed.

Tyler2517

28-09-2014, 21:29

Question on swerves in general.
If you had a 4 module swerve with 1 cim per wheel in the front.
Then 2 cims per wheel in the back. Could you use pid loops to make it work?

Aren Siekmeier

28-09-2014, 22:23

Question on swerves in general.
If you had a 4 module swerve with 1 cim per wheel in the front.
Then 2 cims per wheel in the back. Could you use pid loops to make it work?

Sure, if tuned properly. But the wheels with 2 CIMs will always be waiting for the wheels with 1 CIM to accelerate (for example if the 2s are on the left and the 1s are on the right), so you don't increase your top acceleration like you do with the motors evenly distributed.

Bryce Paputa

28-09-2014, 22:38

What's the issue with a 6 CIM 3 wheeled swerve? As far as I can tell, it would be lighter, have less parts, and be more powerful than a 4 wheel 8 mini CIM one. Is traction an issue, or is it just that nobody has done one recently? I would think that with the semi-recent perimeter rule change a 3 module swerve with a triangular or circular chassis would be a good idea.

JesseK

28-09-2014, 23:12

Electronica1

29-09-2014, 00:03

Out of curiosity, would it work if you were to have 4 modules, 2 with 1 cim and 2 with 2 cims (so you have a total of 6 cims), and set it up so that the 2 with 2 cims are diagonal to each other and the one cim modules are also diagonal to each other. That way you would have the power of 6 cims without messing up your movement by having one side of your robot more powerful than the other.

(I have little experience with swerve, so please correct me if this idea is flawed)

jman4747

29-09-2014, 09:54

Actually, the point of this thread was simply whether to allow 8 mini-Cims. The argument "not to increase available power" has nothing to say on this question, given that 8 mini-cims have a smaller TPE than 6 Cims, which are allowed.

Absolutely.

I can't see how allowing 8mini-CIMs will prompt teams to build drive trains with more power than 6 cims. At some point beyond that diminishing returns have to make that impractical. If anything Mechanum, Octocanum, Swerve, Crab, etc. and manipulators would benefit more.

Kevin Ainsworth

29-09-2014, 11:57

Thanks for all the replies about this topic. We know that the GDC won't change the rules, this was just a fun topic to bring up and discuss.

The ultimate goal would be for teams to have more flexibility on their CIM/ MINI-CIM usage. The intention that started this thread. The flexibility to be creative outside of the standardized FRC robot.

Our personal desire is added acceleration on a 4 wheel swerve drive that would match a 6-CIM tank drive. We currently could run a CIM and MINI-CIM on each wheel according to last years rules so what would dual MINI-CIMs hurt?

I fully agree that the swerve has it's advantages and tradeoffs.

-Running two CIMS on two of the four wheel modules would not be optimal as Aren explained.
-6wd swerves we feel have a hard time keeping all their wheels on the ground and using all the power available.
-3wd swerves remind up of the Reliant Robin and why they made ATC (3-wheelers) illegal. Though I would love to hear from the teams that have successfully used a 3WD swerve.

We understand that other teams have successfully utilized the above designs and appreciate their creativity and desire to try something different.

For those that are arguing there is too much power already.
-The 8 MINI-CIM drivetrain wouldn't be any more powerful than the existing 6-CIM drivetrains, less actually.
-We do not encourage or allow intentional high speed ramming from our drivers. This year we did not feel everyone else felt this way.
-What keeps a team from running (6) CIMS and (4) MINI-CIMS currently? Power/weight/diminishing returns

A special thanks to Brendan for being the open minded voice of reason in this discussion.

Whippet

29-09-2014, 12:11

This thread gave me inspiration for what could revolutionize robot drives. You're welcome. :P

Oblarg

29-09-2014, 15:34

This thread gave me inspiration for what could revolutionize robot drives. You're welcome. :P

I particularly like the wheels going right through the churro tubes. Erm, I mean, the parts of the frame machined to look like churro tubes, since the whole thing is one solid block of aluminum. ;)

Caleb Sykes

29-09-2014, 16:09

I particularly like the wheels going right through the churro tubes. Erm, I mean, the parts of the frame machined to look like churro tubes, since the whole thing is one solid block of aluminum. ;)

At least the wheels are round, even if they are 10 inches in diameter. Also, gotta love those Toughbox mini XLs.

asid61

29-09-2014, 20:45

This thread gave me inspiration for what could revolutionize robot drives. You're welcome. :P

Clearly you're drawing inspiration from this (http://www.chiefdelphi.com/forums/showthread.php?t=89768).

Whippet

29-09-2014, 21:14

Clearly you're drawing inspiration from this (http://www.chiefdelphi.com/forums/showthread.php?t=89768).

Some inspiration was taken from that thread, yes, but my team had decided that the advantage of decagon wheels was negated by having them on a six-wheel tank due to increased bearing friction. In addition, the holonomic configuration was removed due to the reduction in air resistance that resulted from angling all the wheels parallel to the direction of travel.

I am planning to develop a version in the future that uses every legal motor (including window motors to remove the risk of backdrive!)

EricH

29-09-2014, 21:17

I am planning to develop a version in the future that uses every legal motor (including window motors to remove the risk of backdrive!)

Don't forget some rotary pneumatics (or clever use of linear pneumatics, similar to a steam engine's drive rods) to add that extra pep for pushing matches! Should anybody be so foolish as to try pushing you, of course.

BBray_T1296

30-09-2014, 01:07

Some inspiration was taken from that thread, yes, but my team had decided that the advantage of decagon wheels was negated by having them on a six-wheel tank due to increased bearing friction. In addition, the holonomic configuration was removed due to the reduction in air resistance that resulted from angling all the wheels parallel to the direction of travel.

I am planning to develop a version in the future that uses every legal motor (including window motors to remove the risk of backdrive!)

Scouting at a regional:
"What does your robot do?"

"Well, uhm, it cant shoot, and it cant intake, and it cant score, and it cant turn, but it does fast really really well!"

http://s21.postimg.org/ta2uqfa79/too_much_fast.png

IronicDeadBird

15-10-2014, 20:13

The opening line of this is...
"Would any one else like to see (8) MINI-CIM motors allowed so the swerves can be on par with the (6) CIM tank drives?"

Yes I would love to see swerve drives and tank drives get in meaningful skirmishes. However how would that effect other drive base interactions? I wouldn't want FRC to move to a point where it would be you either make an 8 MC swerve or 6 CIM Tank drive.
Lets be real here for a second though. Not all teams prioritize beast mode drive bases... Would 8 mini cim's on drive be equal to those extra mini cim's on scoring?
That question is entirely rule dependent and would differ from year to year. If suddenly FRC makes a no contact game then what?
Either way I think a major point we are all missing is that 8 mc's would make making an AT-AT more viable.