Team 2175 Logo Motion Robot Design

[Aren Siekmeier]

Does the CAD have 6 Jaguars on it?

Right now it only includes the jags for the drivetrain. There will be at least one more for the lift mechanism, and possibly more depending on minibot deployment, gripper design, etc.

1.) How do you plan on picking up the tubes from the floor easily with the telescoping lift centered in the bot?
2.) The placement of your batter seems a little difficult to reach from the views that you have provided. Have you guys planned on an easy way to change out your batteries?

1. The gripper will have two positions powered by a cylinder. Vertical for starting the match within the frame perimeter and for scoring. And horizontal for picking tubes up off the ground. In the latter orientation, it will have to reach forward and over the bumpers to the ground.
2. The battery can just be lifted a few inches, tipped, and dropped out the bottom. That's the idea anyway, we haven't checked that the clearance will actually allow that. If not, there will probably just be thumb screws or something on the brackets holding in. Either way, it will be accessed from the bottom.

What gear reduction are you thinking for the FP?

A 20lb arm climbing 10 ft in 1s is about 270W, appropriate for an FP it seems. With a 1" radius pulleys, we're looking about 8.5:1 off the FP. We're also considering two RS 775s, but we're unsure of the transmission options for that.

And actually, with four equally powered wheels, the robot goes slower diagonally, just with more torque (the wheel speeds don't add up, but the torques do). However, we can go twice as fast in one direction by doubling the CIMs there. Since we don't care as much about strafing, we demote them to RS 775s.

Yes, the belt is fixed to the final (gripper) stage. Powering the belt pulls this up and down at the same time as the first stage (or perhaps in sequence...). We realized that a closed belt would simplify things a lot, but at first were failing to see how to make it work. But conveniently the length lost between the stages will always equal the height change of the final stage, so the belt stays the same length (assuming its vertical). We actually verified this in Solidworks down to a thousandth of an inch. Pretty sweet. Of course, who knows if the real mechanism will work that well. The double clamp on the gripper stage also allows us to quickly tension the belt as needed while keeping it all working smoothly.

@Dr Theta: We might also be attending Lake Superior, depending on funding, so perhaps we'll see each others' handiwork there?

[AllenGregoryIV]

Originally Posted by compwiztobe

And actually, with four equally powered wheels, the robot goes slower diagonally, just with more torque (the wheel speeds don't add up, but the torques do). However, we can go twice as fast in one direction by doubling the CIMs there. Since we don't care as much about strafing, we demote them to RS 775s.

I'm not sure how to explain this better than other people already have before me.

This gif file on this page shows the relationship between standard drives, omni drives, and Mecanum drives. Ether does a great job of explaining the math and if you have questions he is usually happy to answer them.

The source I sited above also shows how the other motors are able to induce velocity (not force) perpendicular to the direction of rotation of any one wheel.

In fact wheel torque is .707 (1 over root 2) that of any individual wheel when traveling at a 45 degree angle to any wheel.

[Dr Theta]

We're actually attending 10000 lakes. Anyway it looks very good. Out of curiosity what were you planning on using for the belt material?

[mplanchard]

Very nice and thank you for sharing.

For all robot designers, learn from this example:let SolidWorks or any other cad system take the math values out many decimal places. Don't round and put in values. Keep them out to as many places as the software can handle in the part and assembly files.

The in the drawing you specify tolerance and precision for machining.

Marie