Re: toughbox mini mecanum
 

Actually, I was presuming that since Hoover put the throttle control on the Z slider, that it was going to be adjusted during the match, so that you could switch (or actually grade) from "full speed" to "parking maneuvers". To reduce speed through gearing while allowing the high speed would require a shifter, no?

Re: toughbox mini mecanum
 

Yeah, ya know, I am not sure we are seeing how small of space we are in this year. First off we have half the court. Then quite a bit of the court is occupied by playing pieces. And then sharing this space with two other full size robots.

Then there will be things that will be detrimental to a team

1) Out of control driving into objects they don't want to hit.
2) Out of control steering into objects they don't want to hit.
3) Not having the speed to get to objects
4) Not having the finesse to manipulate objects
5) Competition for space or objects by other robots on their own 'alliance'.

All this shows that the game goes fast, slow, fast, slow...

The ideal robot should be able to move in all directions either fast or slow. If mecanum is used then does that mean that shifters are also needed for all 4 transmissions. What a nightmare if just one of the fails, then 2 above is probably going to happen to that team. Shifters are out of the question for out team anyway so my solution then is voltage regulation, i.e. limiting top voltage in a way convenient for the driver (to be determined).

Re: toughbox mini mecanum
 

What does "high speed" mean to you, in the context of this game? How many feet per second?

Re: toughbox mini mecanum
 

The point I was making (for the benefit of rookie teams reading this thread) was simply that reducing top speed by limiting motor voltage does not provide the same kind of fine control of slow small motions that is obtained by reducing the top speed of the bot via gearing.

Gearing a bot for a top speed of 18 fps and limiting the voltage to 6 volts does not provide the same fine control of slow motions as gearing the bot for 9 fps.

Re: toughbox mini mecanum
 

I suspect that most of this game will be played at speeds of less than 1fps. In this context, 2-4fps is high speed - what you'd want to use to carry that stack of totes over to the scoring platform - though you may make a dry run or a single game piece trip faster. Except in the first 30 seconds of the match, anything over 8fps is likely to cause more un-scoring than scoring.

Granted, a shifter is better at fine maneuvers in low gear, but its real purpose is to improve acceleration at low speeds.

Re: toughbox mini mecanum
 

I'm having trouble parsing your post.

Let me rephrase my question: For a robot with a single-speed gearbox, what do you think would be the correct top speed gearing for Recycle Rush?

For Recycle Rush, improving fine control of slow motions is a "real purpose" of gearing for low top speed... even arguably a more important purpose than acceleration.

Re: toughbox mini mecanum
 

More than I've seen in a number of years, ideal top speed is dependent on what a team's strategy is. Our strategy will require getting to a couple places on the floor quickly, so we have geared for a "high" top speed, which is still significantly slower (11 fps) than last year (17 fps); we are also forgoing the shifter. If another strategic approach is taken, 8 or 9 fps maybe plenty or even too much. There are legitimate strategies this year that require 0 fps.

Re: toughbox mini mecanum
 

To answer Hoover'squestion about the Toughboxes, I don't think you will have any problem using them with mecanum. Good for you and your team, for using the resources you have in a smart and creative way.

Re: toughbox mini mecanum
 

The AM14U2 is a nice package. But for FRC purposes what I would really like to see is a "toughbox multi". It would be similar to the mini but would come with alternate gears to give a team a choice of speeds.

When I began this reply I was going to say that I wish this chassis came with shifting transmissions but I know that is more expensive.

In either case, changeable gearing is a great teaching tool. The first year our mechanics mentor drew gearing on the board and asked us which would be for speed and which would be for power, more than half of us (mentors included) got it wrong.

Re: toughbox mini mecanum
 

Of course, it depends on your game strategy. For a robot that stacks on the field and carries the stack to the platform, and does not plan a bunch of trips back and forth from the alliance wall to the landfill, I think 6fps is about right. We plan to either carry a bunch of crates from the human station to the nearest platform, or clear the landfill (at least of the upright totes; we'll work on a tote-flipper after we get the forklift functioning well enough to tune the software practice driving). That said, we're gearing at about twice this speed (13fps), because this is our team's fourth season, and we've mis-analyzed game play three times so far. We want the flexibility to adapt to the game as it turns out to be played as opposed to being optimal for what we expect.