Team 610 pre-season drivetrain

[waialua359]

Originally Posted by Rob Stehlik

I doubt it. In my opinion, two speed transmissions are silly and largely unnecessary. In most robot games, the vast majority of your movements will be short sprints from game piece to goal, and avoiding other robots in between. This calls for acceleration, not a high top speed. Slower is faster.

Over the years based on our experiences, I find this very true.
However, when we had our software controlled auto transmission in a previous year, we found that to be highly effective......except we scrapped it when our roll pin from the dog gear went sour in matches. We didnt last an entire tournament without having issues with it.

The first time I saw shifting was 2001 (I think) at the SVR regional when 254 used low gear shifting to balance on the bridge much easier. It was very quick that year. EJ drove......maybe he can comment if it was worth it.

[DampRobot]

Originally Posted by waialua359

Over the years based on our experiences, I find this very true.
However, when we had our software controlled auto transmission in a previous year, we found that to be highly effective......except we scrapped it when our roll pin from the dog gear went sour in matches. We didnt last an entire tournament without having issues with it.

The first time I saw shifting was 2001 (I think) at the SVR regional when 254 used low gear shifting to balance on the bridge much easier. It was very quick that year. EJ drove......maybe he can comment if it was worth it.

I'm kinda lolling at the thought of EJ driving a robot in a FRC competition.

I used to share this thought, but have found through experience that the idea that slower top speed=faster isn't necessarily true. My current belief is that you should optimize your acceleration by reducing the mass of the robot as much as possible, and as a last resort, adding more power. Limiting your top speed to improve your acceleration is a risky proposition at best. We geared our robot too low in 2012 (where conventional wisdom would say that you needed acceleration a lot more than speed), and we really found it limited our performance. Sure, we accelerated quick, but it took forever to go anywhere.

This offseason, we played with an approximately 90lb bot (not including bat and bumpers), and geared to go around 18fps with a WCP DS. Simply put, the acceleration and speed were fantastic, even compared to a bot only 30lbs heavier. 18fps adjusted was a good speed for short runs around defense too. We got heavy d played on us all through quals, and we only really started shifting in elims. That robot flew, and it was because it was light and we geared really fast.

My opinion tends to be that for robots with a decent center of gravity, speeds of 16+fps are reasonable for most games (with a shifter). Of course, others have different well supported ideas about the "best" top speed.

[MichaelBick]

Originally Posted by DampRobot

I'm kinda lolling at the thought of EJ driving a robot in a FRC competition.

I used to share this thought, but have found through experience that the idea that slower top speed=faster isn't necessarily true. My current belief is that you should optimize your acceleration by reducing the mass of the robot as much as possible, and as a last resort, adding more power. Limiting your top speed to improve your acceleration is a risky proposition at best. We geared our robot too low in 2012 (where conventional wisdom would say that you needed acceleration a lot more than speed), and we really found it limited our performance. Sure, we accelerated quick, but it took forever to go anywhere.

This offseason, we played with an approximately 90lb bot (not including bat and bumpers), and geared to go around 18fps with a WCP DS. Simply put, the acceleration and speed were fantastic, even compared to a bot only 30lbs heavier. 18fps adjusted was a good speed for short runs around defense too. We got heavy d played on us all through quals, and we only really started shifting in elims. That robot flew, and it was because it was light and we geared really fast.

My opinion tends to be that for robots with a decent center of gravity, speeds of 16+fps are reasonable for most games (with a shifter). Of course, others have different well supported ideas about the "best" top speed.

I agree with this thought. 6 motors is just so easy now, especially if they keep even half of the motors available. If you have the motors I see little reason in not going 6 motor drive.

[DampRobot]

Originally Posted by MichaelBick

I agree with this thought. 6 motors is just so easy now, especially if they keep even half of the motors available. If you have the motors I see little reason in not going 6 motor drive.

Tripping the main breaker is a serious concern with a 6 CIM drive.

Originally Posted by MichaelBick

I agree with this thought. 6 motors is just so easy now, especially if they keep even half of the motors available. If you have the motors I see little reason in not going 6 motor drive.

Michael, Damp's argument is that he'd rather shift on a light bot than add more motors to the drive.

[MichaelBick]

Originally Posted by Andrew Lawrence

Michael, Damp's argument is that he'd rather shift on a light bot than add more motors to the drive.

Ok, I misunderstood. Regardless, 6 CIMs is overkill unless you are running a PTO. Otherwise I would max out at 4 CIM + 2 Mini CIM.

[cadandcookies]

Perhaps this discussion of acceleration versus top speed should be split off...

Regarding top speed versus acceleration, I think it's important to remember what (I believe it was BJC) said in a whitepaper: the goal of a drive train is to get you where you need to be, when you need to get there. To that end, I'd focus on time to go a given distance: a very nice calculator for this can be found here, which was written up by Andrew Schreiber (based on the drive train acceleration model, which Ether provides a link to in the next post). It's a little bit out of date but it's good for giving reasonably accurate numbers.

Other than that, it's all about team preference. Obviously there's some math behind it (if it's going to take you longer than 25 feet or so to reach your top speed, it probably isn't worth it), but nothing that hasn't already been mentioned elsewhere.

[Joe Ross]

Originally Posted by Rob Stehlik

It should be driving soon!

You've probably fixed this by now, but your cRIO modules are not in the correct slots.

I assume you purposely wired the Digital Sidecar and Radio the way you did? The 5v supply on the PDB has a worse dropout then the 12v supply.

[Nathan4567a]

Fantastic job! I love the nice and neat cable runs. Our team needs to have clean electronics like that this year. Good choice with the talons too. I love the fact there is no annoying fan on them

[z_beeblebrox]

^Reported

[magnets]

This is pretty cool. I agree with the whole shifting is overrated thing, and the rear-turning 8 wheel drive thing is pretty neat. Where do you get the fiberglass for the bellypan?

on a totally unrelated note-that spam post 2 above this one is crazy. It has the word movie in it 445 times.

[Tem1514 Mentor]

I sure that you guys will show off that bot during the quick build as it will give all the new teams a good idea of what may be done outside of the KOP

I have my bag already packed with those must have tools ready to help all our new teams get a good start on the season with a working drive train.

[Mr. Lim]

Originally Posted by Tem1514 Mentor

I sure that you guys will show off that bot during the quick build as it will give all the new teams a good idea of what may be done outside of the KOP

I have my bag already packed with those must have tools ready to help all our new teams get a good start on the season with a working drive train.

Yes! I actually plan on using this drivetrain for the Java Workshop at Quick Build. I'll be doing code for the robot from the ground up starting from a bare laptop with no tools installed.

The goal is to progress to a driveable base, and a simple autonomous by day's end - and to touch on any additional topics the Rookie Teams are interested in learning about.

[brennonbrimhall]

Originally Posted by Mr. Lim

Yes! I actually plan on using this drivetrain for the Java Workshop at Quick Build. I'll be doing code for the robot from the ground up starting from a bare laptop with no tools installed.

The goal is to progress to a driveable base, and a simple autonomous by day's end - and to touch on any additional topics the Rookie Teams are interested in learning about.

Would you mind recording it? Something like that would be an awesome resource for all.

[Mr. Lim]

Originally Posted by brennonbrimhall

Would you mind recording it? Something like that would be an awesome resource for all.

The Quick Build workshop is really a group of mentors helping Rookie teams get their tools setup, programming and downloading their first program to a robot, etc. It's over 8 hours long, and is just a "get work done" session where we veteran mentors help out. It doesn't make for good recordings, nor is it all that effective to watch the recordings after the fact.

We've tried to record it in the past I believe, and I don't think anyone was willing to watch 8+ hours of a lot of different teams working on their robots.

Sorry!