Team 1625 Introduces their 2011 Robot: Mr. Cringerpants

[Carrington]

Originally Posted by Drivencrazy

Looks great guys! Another innovative drive-train implementation and once again I'm impressed. Care to elaborate or point me to somewhere to show me how it works?

Basically, it is a normal 6 wheel west coast style drive, only with internal belt runs rather than chain. The gearbox transfers power through the center wheel which then runs belt to the outer wheels. From the outer wheels the axles are extended inward to act as a pivot for the "Lobster Tubes" to rotate around. On one side of the lobster tube it is merely a pivot for the tube to rotate around, but on the other side there is a set of bevel gears to transfer power to one of the lobster wheels. From that lobster wheel there is an axle going through one of the wheels and it extends to the back of the lobster tube. On the end of that axle there is a pulley which runs a belt down to the other side to power the other wheel.

Originally Posted by Grim Tuesday

Correct me if I'm wrong, but do you guys have TWO drivetrains? One for forward/back, and another for strafing?

I am at a loss for words due to awesomness.

It is one drivetrain, but not all wheels are touching the ground at all times.

Originally Posted by Chris is me

I have no idea how it works and I'm not sure if I am better off keeping it that way or not.

How do the strafing wheels come into play?

Why telescope instead of a higher arm joint?

Why is your arm joint a four bar kind of thing I'm so confused

WHY HAVE YOU TURNED MY WHOLE WORLD UPSIDE DOWN THE DAY BEFORE SHIP AGAIN

Strafing wheels or come down via a pneumatic cylinder. Telescope rather than a higher arm joint was based on some strategic and control decisions. The arm has a 4 bar support system for structural integrity.

Originally Posted by JesseK

I get how the lobster actuation works (downright ingenious imo) -- the front/rear wheels are the rotation axes for the lateral wheels. Yet what really blows my mind is how the belt running between the two lateral wheels ('lobster wheels' ?) doesn't get eaten when the robot turns in place during normal operation. Is there a differential not shown?


Awesome work!

As explained above there is a set of bevel gears on two opposite corners of the robot. Essentially when you drop down the lobster tubes forward becomes left strafe and backwards becomes right strafe. Here is a picture of the bevel gears on a lobster tube:



It's actually quite fun to watch drive around with no bumpers, because all wheels spin at all times. It can really mess with your mind sometimes.

[artdutra04]

Awesome work. Can't wait to see it compete!

Originally Posted by 1075guy

Seems to me like 1625's "lobster" drive shown here, is a relative of 148/217's Slide drive (Nonadrive) from 2010, at least in how it works. It looks to me like the strafing wheels are actuated up and down to lift the other 6 traction wheels off the carpet.

It's much more similar to 190's 2003 robot, which had a very similar (secondary drop-down drive train) arrangement.

[Jared Russell]

Amazing as usual!

Your team took a 6-wheel swerve drive to Einstein last season, and I would have bet money that we would have seen it again in 2011 (with the flat field, it seems perfect). On paper, at least, 6-wheel swerve has advantages over this drive system (strafing while translating...e.g. diagonal movement). Both drive systems are much more complex than a skid-steer drive, but clearly within the means of your team.

What was your decision process that led you to the "lobster-drive" over doing 6-wheel swerve again? Complexity/weight? Some perceived advantage that is elluding me? The cool/doing something novel factor? Just curious!

[Carrington]

Originally Posted by Jared341

Amazing as usual!

Your team took a 6-wheel swerve drive to Einstein last season, and I would have bet money that we would have seen it again in 2011 (with the flat field, it seems perfect). On paper, at least, 6-wheel swerve has advantages over this drive system (strafing while translating...e.g. diagonal movement). Both drive systems are much more complex than a skid-steer drive, but clearly within the means of your team.

What was your decision process that led you to the "lobster-drive" over doing 6-wheel swerve again? Complexity/weight? Some perceived advantage that is elluding me? The cool/doing something novel factor? Just curious!

6 wheel swerve is great and if properly put into use it definitely has advantages. The one obvious advantage is diagonal movement. We went back and rethought our entire season last year when going through this design process. We found that almost 100 percent of the time when the strafing capabilities were put to use it was only for lateral side to side movement. This led us to believe that the diagonal movement might not necessarily be worth the time, weight, complicated code, and maintenance that come with having a 6 wheel swerve. Another advantage of lobster is that as soon as you drop the lobster tubes you know that you can go straight side to side. With a 6 wheel swerve you have to worry about having modules aligned to properly do a perfect sideways strafe. Yet another advantage of lobster is the ability to put in a drift function. Beyond what all the capability differences may be this drivetrain offers something that the swerve can not. It is a much more direct link between driver input and robot motion. This drivetrain essentially offers us the same advantages that our 6 wheel swerve offered us last year and possibly has advantages even beyond that and we plan to push it to its limits.

[Don Wright]

Just curious about the reasoning behind the double fittings on all the pneumatic connections... (Mostly in reference to the claw pneumatics)

[Carrington]

Originally Posted by Don Wright

Just curious about the reasoning behind the double fittings on all the pneumatic connections... (Mostly in reference to the claw pneumatics)

We were waiting on the right pneumatic fittings to arrive. Until we got them we decided to leave some extra hose and adapt some fittings we already had.

[Josh Fox]

Am I correct in assuming that when the "lobster tubes" are touching the ground it functions similar to a wide orientation bot?

[Carrington]

Originally Posted by Josh Fox

Am I correct in assuming that when the "lobster tubes" are touching the ground it functions similar to a wide orientation bot?

Yes, you are correct.

[ratdude747]

I see a leadscrew in there... like 503's 2005 bot?

[Carrington]

Originally Posted by ratdude747

I see a leadscrew in there... like 503's 2005 bot?

Yes, there is a leadscrew on the robot. The motor is mounted on a pivot at the base of the arm. The leadscrew nut is located on a rotating block attached to part of the 4 bar. It'd say it is much more similar to our 07 or 08 bot rather than to 503 from 2005. Fun fact, there is zero chain on this robot

[daniel_dsouza]

[quote=TheLoneAsian;1029359]...there is a set of bevel gears to transfer power to one of the lobster wheels. quote]

I haven't used bevel gears since my old Lego mindstorms kit. Facinating!

Where did you get the bevel gears? Are they 5140061-65? Is there anything I should know if our team decides to try this? (parts you would have used, helpful advice, etc.)

[rochan]

I'm hazarding a guess that the left gearbox is chained to the front wheels and the right gearbox is chained to the back, or something similar. I'm excited to see how you do in competition, and how fast that minibot makes it up the bar

[Taylor]

above post reported