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| View Poll Results: Do you think 8 MINI-CIMS allowed would be a good idea? | |||
| Yes, I'ld love to see what people come up with using 8 MINI-CIMS. |
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46 | 41.07% |
| No, I like the motor rules the way they are! |
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66 | 58.93% |
| Voters: 112. You may not vote on this poll | |||
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#1
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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? |
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#2
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Re: 8 MINI-CIM SWERVE
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 ![]() |
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#3
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Re: 8 MINI-CIM SWERVE
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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) Last edited by nuclearnerd : 26-09-2014 at 16:14. |
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#4
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Re: 8 MINI-CIM SWERVE
How would you fit two motors inside a wheel?
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#5
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Re: 8 MINI-CIM SWERVE
You'd use one to drive the wheel and one to turn the module.
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#6
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Re: 8 MINI-CIM SWERVE
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.
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#7
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Re: 8 MINI-CIM SWERVE
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#8
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Re: 8 MINI-CIM SWERVE
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.
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Last edited by Max Boord : 26-09-2014 at 19:43. |
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#9
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Re: 8 MINI-CIM SWERVE
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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. |
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#10
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Re: 8 MINI-CIM SWERVE
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#12
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Re: 8 MINI-CIM SWERVE
2 extra motor controllers, 2 fewer available 40A ports on the PDB - 8 Mini CIMs vs 6 CIMs is a lose IMO.
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#13
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Re: 8 MINI-CIM SWERVE
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?
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#14
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Re: 8 MINI-CIM SWERVE
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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 Quote:
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. Last edited by JesseK : 26-09-2014 at 22:34. |
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#15
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Re: 8 MINI-CIM SWERVE
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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. Last edited by Oblarg : 27-09-2014 at 01:22. |
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