15-11-2011 07:25

sgreco

Re: pic: Uber3.0 - prototyped

That is one sweet looking frame.

Want to give us some specs?

15-11-2011 08:04

kajeevan

Re: pic: Uber3.0 - prototyped

The cad and specs are both in this link.

http://www.chiefdelphi.com/media/photos/36993

15-11-2011 23:24

Hawiian Cadder

Re: pic: Uber3.0 - prototyped

We completed a prototype this fall geared similarly to this, I completely see why you chose a faster speed, with a reasonable amount of practice it is very controllable and highly useful.

15-11-2011 23:31

Re: pic: Uber3.0 - prototyped

I'm a bit mechanical dumb, so sorry if this is obvious, but how do you achieve the speed of 16 ft/s? I see it's through CIMple Boxes, but is that it?

Thanks!

P.S: After reading the CAD paper again, it says it goes through CIMplex Boxes, not CIMple Boxes. What are CIMplex Boxes? Are they like CIMple Boxes?

15-11-2011 23:41

Chris is me

Re: pic: Uber3.0 - prototyped

16 FPS single speed sounds brutal. Not enough room for error there... A 12 feet per second skid might have that.

Did you not account for frictional losses? If you didn't, then your drive is very similar to 1503's this year.

16-11-2011 00:40

kajeevan

Re: pic: Uber3.0 - prototyped

Off the gearbox I'm running 32:38 for a total ratio of about 5.55:1. The wheel well layout is inspired by 1503 but instead of 35 chain I went 25 and threw in bolt action tensioners to pull the end wheels to take up any slack. Also I decided dead shafts opposed to live. Also I'm not worried about to much speed, we enjoy going fast, plus we have the option to throw in an electronic shifter as we have in past years.

P.S. My mistake it is CIMple not cimplex.

16-11-2011 08:49

Brandon Holley

Re: pic: Uber3.0 - prototyped

In high gear this past year, we were moving faster than this (actual speed). It required some pretty sophisticated control software that 254 helped to develop. Once we had this setup, it made driving at that speed much simpler.

I would not recommend trying to drive that fast without some software support. I think a simple 2 stick, or 1 stick drive setup would be quite difficult to handle. However, every driver is different, so YMMV.

-Brando

16-11-2011 10:04

JamesCH95

Re: pic: Uber3.0 - prototyped

Care to elaborate about what it did? Balance wheel speeds using encoder feedback?

16-11-2011 13:51

Brandon Holley

Re: pic: Uber3.0 - prototyped

We utilized both encoders in the drive system, and a gyro.

We basically just elaborated on Cheesy Drive. 2 stick drive system- 1 stick is essentially "throttle" the other stick is essentially "steering". There was a button on each stick. One button for shifting, the other button for "quick turn". Quick turn essentially turned the steering stick into a single stick drive system for turning in place.

As we traveled at a faster rate of speed, the gains in the turning loop would adjust so that dumping the steering stick all the way to one side or the other would create a smooth, controlled turn. This occurred even at 16+ ft/s top speed when we traveled back and forth across the field. Additionally, even at low speeds, the robot could only turn in place using the quick turn button, otherwise it would drive in a small arc.

I did not do the actual coding of it, so I'm speaking more from a theoretical/design point of view, but that's essentially what it did.

Driving without this setup at top speed was quite difficult. We noticed right away as our driver began driving just the drive system in week 3 or so. He practiced driving the full field and then dipping into/out of the human player lanes over and over again. We continued to tune the system until he felt it was solid, and we were satisfied with the results.

-Brando

17-11-2011 11:11

JamesCH95

Re: pic: Uber3.0 - prototyped

So, if I'm understanding you correctly, turning rate limits were controlled based upon the speed of the robot.

That does seem like it would make the robot easier to control. I also like the idea of a "quick turn" button too. I assume that made the robot to a very fast about-face?

17-11-2011 14:01

Brandon Holley

Re: pic: Uber3.0 - prototyped

That is correct. As the robot moved faster, the turning became less "sensitive". It essentially allowed the driver to still use coarse controls to maneuver at high speeds.

Quick turn would change the control scheme to allow turning in place. If you held the button down and moved the stick left and right, you essentially created the control scheme you get from moving one stick forward and the other backward in a standard 2 stick setup.

-Brando

17-11-2011 14:09

AdamHeard

Re: pic: Uber3.0 - prototyped

Just to clarify, this means turning in place is exclusive to quick-turn, and in all other modes turning is in arcs?

17-11-2011 14:23

Brandon Holley

Re: pic: Uber3.0 - prototyped

That is correct.