Re: Implementing Traction Control for an advantage in the 2009 game
 

Sounds like the legendary 1978 Brabam BT46B Formula 1 car which used an enormous fan underneath to generate a vacuum and more normal force. The car won the one race it ever competed in but was declared illegal

Re: Implementing Traction Control for an advantage in the 2009 game
 

We were given a +/-3g accelerometer, and our robots can accelerate at around +/- .05g (based on the published COF). Therefore, we can only use a ridiculously small portion of the range of the ADC.

Re: Implementing Traction Control for an advantage in the 2009 game
 

Hi, i'm a rookie programmer this year, our team has gone with LabView. I was just wondering if anyone could explain to me how to filter the joystick to limit acceleration, and/or how the how the filtering will effect the acceleration.

Thanks in advance,
Charlie

Re: Implementing Traction Control for an advantage in the 2009 game
 

I used case structures in between the joystick subVIs and the drive VI. I believe I had one case structure to determine if the joysticks were at their "relaxed" position, then one to determine whether it was in a positive or negative position (foward and backwards), and finally one to determine if the output was equal to the input. Inside the last case structure, it the output was less than the input, it increases it by a constant value some each cycle of the while loop. There may be an easier way to do this, but this setup works exactly as we need it to.

Re: Implementing Traction Control for an advantage in the 2009 game
 

Gordon Murray's Brabham was copying Jim Hall's Chapparal 2J from 1970: http://www.photoessayist.com/canam/c.../chaparral.htm. It was a Can-Am racer that used a 45hp snowmobile engine to drive two ducted fans producing 1,000 pounds of static down force. If someone can move enough air with the limited power available I don't know why this wouldn't work for a FIRST robot. In some respects FRC robots have advantages over the "sucker" racers -- a perfectly flat "road" surface and no suspensions. I don't know how to do the math (sorry, Mark) on an aerodynamics problem like this, but a pair of CIMs driving 8-12" fans mounted vertically in cylinders open on the ends might generate some significant normal force. I wouldn't think it would approach 1,000 pounds, though.

EDITED: Here's a link to a Website of a model-builder who constructs battery-powered hovercraft: http://www.model-hovercraft.com/index.html. A hovercraft is only a Lunacy robot turned upside down.

Or... how about an electric hover-lawn mower? http://www.flymo.co.uk/node3126.aspx

Re: Implementing Traction Control for an advantage in the 2009 game
 

I can't locate the reference right now, but it was either a team update or a blog entry that said that down-force suction would not be allowed as the regolith is fairly fragile and any form of suction would deform and possibly damage the playfield resulting in a potential disqualification.

Before spending much time experimenting, you might want to investigate the updates, the blog, and the Q&A system.

Lynn (D) - Team Voltage 386

Re: Implementing Traction Control for an advantage in the 2009 game
 

It's in Bill's Blog for Jan. 4th.
http://frcdirector.blogspot.com/sear...&max-results=7

Re: Implementing Traction Control for an advantage in the 2009 game
 

Actually, the accelerometer seems good to us. But, there is definitely a LOT of mechanical noise on our chassis.....which the accelerometer dutifully reports.

Re: Implementing Traction Control for an advantage in the 2009 game
 

We've moved it onto a piece of foam to try and isolate it from the chassis, but due to a me-dropping-the-laptop incident this weekend, we haven't had a chance to see if it improved.

Re: Implementing Traction Control for an advantage in the 2009 game
 

With some help from a few mentors from my old team I did the math. Based on the horsepower output of a Cim motor your could use a fan that moves roughly 1000 cubic feet per minute. Two of those on the robot so 2000 cubic feet per minute. If you use the entire bottom surface of the robot leaving a 1/8" gap with the floor that is capable of generating a negative pressure of .72 psi multiplied across the area of the robot 1064 square inches that is approximately 766 additional pounds of down force. Added to the weight of the robot that is 886 pounds total downward force. I completely understand Bill's concern, but darn if it wouldn't be awesome to see.

The fan source I was considering is Cincinnati Fan Company.

Re: Implementing Traction Control for an advantage in the 2009 game
 

LabVIEW has a "Range and Check" (or something similar) block which allows you to cap a value to a range and/or check if it is in that range--may be useful to your purpose.

Re: Implementing Traction Control for an advantage in the 2009 game
 

Thanks, thats what we ended up doing.

----------------
Now playing: The Police vs. Rick James - Put On The Super Freak [Leebuzz]
via FoxyTunes

Re: Implementing Traction Control for an advantage in the 2009 game
 

A mechanical lowpass filter should theoretically help:
tightly couple the accelerometer to something massive (like the battery) and loosely couple that mass to the frame (mount in spongy foam).

Re: Implementing Traction Control for an advantage in the 2009 game
 

Until something goes all nonlinear on you -- then the Tinkerer with the duct tape gets you home.

I recommend "To Engineer is Human: The Role of Failure in Successful Design" by Henry Petroski for some good cases where engineers learn from the unintended consequences of engineering inadequately foretelling the future.

(And I know you know this, Don. I just love the idea of Red Green backing up engineers with his handyman's secret weapon.)

(Although My Father the Retired Aerospace Engineer swears he never built anything that didn't have "Missile Tape" on-board somewhere.)

Re: Implementing Traction Control for an advantage in the 2009 game
 

Rick,

I also have this book on my shelf. An excellent read...

Regards,

Mike