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-   -   Team 467 Driving while holding the ball (http://www.chiefdelphi.com/forums/showthread.php?t=63930)

Tsom467 12-02-2008 22:34

Team 467 Driving while holding the ball
 
The ball is fairly well locked in place too...

http://www.youtube.com/watch?v=a30z-o4CAqc

Jeff Rodriguez 12-02-2008 22:45

Re: Team 467 Driving while holding the ball
 
That robot better be named 'Scorpion'.

cloud_254 12-02-2008 22:46

Re: Team 467 Driving while holding the ball
 
:D i seriously agree it should be named scorpion

octothorpe 12-02-2008 22:55

Re: Team 467 Driving while holding the ball
 
Cool design, I like the rounded-triangle base. How do you plan on outfitting it with bumpers?

ggoldman 12-02-2008 23:06

Re: Team 467 Driving while holding the ball
 
Firstly...very nice design.

Secondly...just like when a fighter gets a ring fighting name....your robot should be called scorpion...because thats what the PEOPLE will call it :)

On to serious business...

I noticed that your robot has a point when you accelerate when the high COG (center of gravity) causes you to pop back. If you accelerate too quickly you might run the risk of falling over.

One way to combat this is to prevent very hard accelerations with you motors. You can do this by implementing a "ramping" algorithm into your motor code.

Basically, you program a shape to a ramp (either linear in the form of

motor speed = joystick_value *(x)

where x changes from zero percent to 100 percent over a set time period

You can also do sinusoidal ramps

motor speed = joystick_value * cos(theta)

where theta goes from 90 to 0. This will give you more of a ramping curve.


Hope this helps you some!

BenB 12-02-2008 23:48

Re: Team 467 Driving while holding the ball
 
You could also do a power ramp (e^x) or a quadratic (x^2) or a cubic (x^3). The posibilities are really endless...

Guy Davidson 13-02-2008 00:47

Re: Team 467 Driving while holding the ball
 
Quote:

Originally Posted by 2166BlueBotics (Post 697845)
You could also do a power ramp (e^x) or a quadratic (x^2) or a cubic (x^3). The posibilities are really endless...

Ahh, but they all return roughly the same result :P The easiest way to implement an exponential curve, I believe, is by using the Taylor (or Mclaurin, in this case) expansion. In the case of e^x, the expansion is 1+x/!+(x^2)/2!+(x^3)/3!... I would not be surprised if calculators do this same thing to compute powers.

Tsom467 13-02-2008 01:00

Re: Team 467 Driving while holding the ball
 
Re: Scorpion... LOL! That's what one of our team members said it looked like too! I have a feeling that is what it will be called.

Re: COG... while it did "pop" back a bit, it's actually quite stable.. there's plenty of weight in the bottom (the last weigh-in was 91 lbs), but there's still more to add, including the "skin", some more wiring, and we've already added more strength to the drive sections (all custom built, btw).

Re: ramping... we do have a ramping algorithm, that we've used successfully for the past couple of years, but I'll let our programmers comment on that. You can see last years (Rack & Roll) robot in the background too.

Tsom467 13-02-2008 01:02

Re: Team 467 Driving while holding the ball
 
Here's another one:

http://www.youtube.com/watch?v=rtEbJ1zsqgc

These are all in low gear, by the way.

Jimmy Nichols 13-02-2008 06:39

Re: Team 467 Driving while holding the ball
 
Have you drive it on carpet yet?

RMS11 13-02-2008 21:27

Re: Team 467 Driving while holding the ball
 
looks good but a video of the max hight would be awesome:cool: .

Tsom467 13-02-2008 22:43

Re: Team 467 Driving while holding the ball
 
I'll get one soon, but be assured that it reaches well above 6 1/2 feet :)

Leav 14-02-2008 09:21

Re: Team 467 Driving while holding the ball
 
who is the guy with the cool beard?
how does he work the lathe?? :ahh:

Tsom467 15-02-2008 00:13

Re: Team 467 Driving while holding the ball
 
Very carefully :D

Caio 15-02-2008 04:06

Re: Team 467 Driving while holding the ball
 
that is an amazingly slick looking robot...

i'll have to third, or fourth, the fact it should be called scorpion :)


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