Team 47... Alchemists...

[Ellery]

Originally Posted by Joe Johnson

...almost nothing actually.

Many of you stopped by the pits in Atlanta to look at our Dewalt drill transmission and our modifications that allow us to drive the drill transmission with either a Chiaphua motor, Bosch drill motor, Fisher Price motor, Globe motor, or Keyang motor.

I told many of you that I was worried half to death that this transmission would end up being not as robust as I had hoped and then I would have 8 times as many problems. But in actual fact, we had almost zero problems with this transmissions. With 3 competitions on our "real" robot and hours and hours on our practice robot, I can't think of a single time we took a transmission off the robot because we had a problem with the motor or the transmission. I have never had as few problems with gearboxes and motors on a FIRST robot.

I am definitely going to be publishing a paper on these transmissions this summer. With some luck, we may even make contact with Dewalt in time to get some of these beauties in the kit next year.

They were awesome.

Joe J.

Joe, did you have any problems controlling the drives with this unit? As a typical planetary gear system the backlash is typically what most software guys complain about. Was the controllability of the drives at a high enough resolution? Adding encoders to this unit wouldn't seem to help it much becuase of that slop in the gear system.

Thanks Joe.

Ellery

[Joe Johnson]

There is some backlash, but to be honest, it is not all that much. With #35 Chain, it was often on the order of magnitude of our chain slack (if we let it get loose, which we did from time to time).

But, yes, the additional backlash can cause some problems for control loops at times. It is not that bad though. We ended up either living with the oscillations or adding damping to the system. The only joint we took steps to do something about were are fingers -- they are over powered and very lightly damped. We actually used some set screws on our finger axles, not to transfer torque (which everyone knows sucks) but to add drag to our pivots so that the extra damping removed the oscillations -- not exactly elegant but it worked.

Joe J.

[JVN]

Originally Posted by Joe Johnson

There is some backlash, but to be honest, it is not all that much. With #35 Chain, it was often on the order of magnitude of our chain slack (if we let it get loose, which we did from time to time).

But, yes, the additional backlash can cause some problems for control loops at times. It is not that bad though. We ended up either living with the oscillations or adding damping to the system. The only joint we took steps to do something about were are fingers -- they are over powered and very lightly damped. We actually used some set screws on our finger axles, not to transfer torque (which everyone knows sucks) but to add drag to our pivots so that the extra damping removed the oscillations -- not exactly elegant but it worked.

Joe J.

Joe,
I saw the "magic" in Atlanta and was very impressed.
I'm just wondering how long until you have that whitepaper out?

I understand you're busy (aren't we all)... but I'm eager to learn more.

Thanks in Advance,
John

[Joe Johnson]

Originally Posted by JVN

Joe,
I saw the "magic" in Atlanta and was very impressed.
I'm just wondering how long until you have that whitepaper out?

I understand you're busy (aren't we all)... but I'm eager to learn more.

Thanks in Advance,
John

Somethings got to give...

If I start to list the things I have going I will sound like a whiner so I will just leave it at that...

...I want to do it...

I think I will just have to get some pictures taken by one of our students. That should help me get the ball rolling.

Time will tell.

Joe J.

[Joe Johnson]

Originally Posted by Tristan Lall

You are a "Clever Sheep" indeed.

And the three-speed feature is a neat trick. Did you remove the shifting ability for use on the arm, or just securely lock out the shifter?

The cam that shifts, does not let them shift without moving the shifter. All we have had to do is put them in the gear we want and SURPRISE! they stay there -- make you wonder what all those other drill gearbox designer were thinking.

Joe J.