28-08-2011 16:04

CalTran

Re: pic: 8-chain drivetrain (white background)

Mind if I ask for the specs again and if you made any improvements, besides improving the picture?

28-08-2011 19:46

Jeffy

Re: pic: 8-chain drivetrain (white background)

While we are at it...
I have a few questions because I don't understand the purpose of this sort of drive train.
Mind clarifying a few things for the curious and naive?
1. Why does 4 gearboxes give better efficiency than just two?
2. What is the purpose of the shifting wheel sets?

28-08-2011 19:59

O'Sancheski

Re: pic: 8-chain drivetrain (white background)

Yes... I agree. 148s system has a omni wheel in the center of the chassis where the actuate it to the floor which allows them to strafe side to side. On your chassis i don't see any omni perpendicular to the main drive wheels. So the shifting wheel sets are useless. You can get the same results with a 4wd with the fronts being IFIs and the rears just omnis.

Just my $0.02

28-08-2011 20:05

Arjun Namineni

Re: pic: 8-chain drivetrain (white background)

I believe 148 eventually took out their middle strafing wheel later in the season. If I recall correctly, they used the IFI traction wheels when put up against defense and used the omni wheels while trying to maneuver and move about the field.

But I too have the same question, what is the point of having four gearboxes?

28-08-2011 20:15

crazyStone

Re: pic: 8-chain drivetrain (white background)

No improvements have been made in this render over the orginial besides the color change on the background. I didn't have time to work on lately, should be able to fix the parts so that the assembly becomes more realistic. The Ratios have not been totally finalized but they are approximenly:

Traction Wheel (High) 1:24 (Low) 1:48
Omni Wheels (High) 1:6 (Low) 1:12
Weight of each drive module : 3.5 lbs (x4)
Weight of each transmission : 4.5 lbs (x2) (<-this is a design change here)
Weight of each CIM : 2.7 lbs (x4)

Weight overall : ~35 lbs for the drivetrain + 15 lbs for the frame.

total weight is 50lbs


The shifting wheel sets gives the ability for the drive train to aquire 3 different configurations.



configuration #1: push almost anything while the tractions are down (especially in low gear).
>..... > > = traction wheel
( no rotation is available)
>..... >


configuration #2: is all trick omnis down which rotates the robot around in a circle very effectively

o.....o
...r
o.....o

configuration #3 is trick omni's down in the front ( or back) and then traction down on the other side this changes the axis of rotation.

>......o
r
>......o

Those are the configurations and some of the advantages very good traction and torque coupled with 360 deg donuts at the push of a button.

28-08-2011 20:15

crazyStone

Re: pic: 8-chain drivetrain (white background)

double posted

28-08-2011 20:28

crazyStone

Re: pic: 8-chain drivetrain (white background)

It was something I was told by some mentors but have now had cleared up by several members of CD. They were concerned with the loss of power due to the inefficency of running 2 CIM's on the same shaft since the CIM's have very slight differences in preformance curves due to differences with wrappings and the fields within the motors themselves. They had expressed concern over loss of preformance which the reason for the 4 transmission. In addition it was CAD practice so I took the transmissions as a challange to attempt and create a 2 speed transmission cheaper and lighter than (1/2 of ) a AndyMark Supershifter. In reality the design will probably use AndyMark Supershifters because they are much easier to obtain then it is to manufacture custom gear boxes with little experince and limited time. The 4 transmissions would be useful if in the future the team used this platform and diecided to exchange the omnis for mecanum in which case 4 gearboxes would be nessecary. Those are the main reasons for the 4 transmissions.

28-08-2011 20:57

Aren Siekmeier

Re: pic: 8-chain drivetrain (white background)

A fair amount of discussion has already taken place here. This is a newer render.

29-08-2011 13:47

roboticsgoof95

Re: pic: 8-chain drivetrain (white background)

What CAD software did you use?

29-08-2011 23:29

crazyStone

Re: pic: 8-chain drivetrain (white background)

Autodesk Inventor Professional 2012
with the lovely education watermark on the printed drawings.
The rendering is just in Inventor Studio, haven't gotten around to learning maya or 3d-max enough to render the image in either of those suites.

30-08-2011 08:17

roboticsgoof95

Re: pic: 8-chain drivetrain (white background)

Well, I must say that is pretty sweet.