April 23, 2017, 09:38:56 pm
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Messages - satacoy

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I feel good knowing that I've eliminated one small reason to keep IE around!  :-)

Pete - Team Cosmos

I found some time to crack open the Machinery's Handbook to see if I can make sense of the units.  According to the handbook, there are three types of Moment of Inertia calculations typically used in engineering:  Moment of inertia of plane area, Polar moments of inertia of plane areas, and polar moments of inertia of masses.  I followed the equations for that third kind, which are specified to be used in equations involving rotational motion.

For this type of calculation, the units are described as thus:  "If units are in the foot-pound-second system, the units are ft-lbs-sec^2".  That does differ than the label that I give it on screen of "fp/s^2".  I abbreviated this "ft lb/sec^2" on the original version.  According to the above quote, this would properly be labeled as "ft-lb-sec^2", or something similar.  This is equivalent to slug-ft^2.

But, that doesn't agree with your findings of a timeless unit.  The other two types of MOI appear to have units of Inches cubed.

So, I'm not sure what the right answer is.  I'll update the page to reflect ft-lb-sec^2, since that matches more closely my source material.

Pete - Team Cosmos

Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: February 28, 2017, 09:56:29 am »
My phrasing was bad as well, I realize you're only talking about the unit label I'm using.  And my memory isn't that good, I remember talking to you in '07, but I don't remember fighting Scurry.

I couldn't find the old Delphi thread on the calculator.  I'm not sure if it was in the SubLight forum, the Battlebots forum, the RFL forum, etc.  I remember Eric Scott being pissy about the calculator, but then he was pissy about most things. :-)  I did get a kick while searching the forums on seeing old names and topics pop up.

Once I'm back in Boulder I'll dig out the handbook and see if I can understand why I used that label.  I bet you're right about it being off, I just want to look at the source one more time to see if I had a good reason.  I think I wrote that original calculator in like a day, didn't know javascript or the math behind KE, but just ran with it and it seemed to work.  The original version would only work on IE, if I remember correctly.

Pete - Team Cosmos

Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: February 28, 2017, 01:24:04 am »
Hey Zac,

First, I'm tickled that people are still using the KE calculator.  It's quite possible that the units are wrong, I faintly remember there being some debate on the proper units back in the day.  I'll see if I can dig up the old Delphi Forum posts on it.  Eventually it seemed everyone agreed they were correct, and I believe that I got the math and units out of Machinery's Handbook, but it's always possible that it's wrong.

Secondly, it was great chatting at Motorama, but we've met before, back in the day.  I distinctly remember taking this picture:

Pete - Team Cosmos

Progress Reports / Re: Team Anarchy Robotics
« on: February 13, 2017, 12:44:07 am »
Ah, the last minute panic and associated costs.  I don't miss that part of the sport.

Pete - Team Cosmos

Progress Reports / Re: Team Anarchy Robotics
« on: January 23, 2017, 01:43:07 pm »
I see you are a disciple of the Al Kindle School of All Thread.   :)

Pete - Team Cosmos

Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: January 17, 2017, 11:48:19 am »
I'll take it. Been looking forward to meeting you half my life :P

Don't get worked up too much, I'm not that impressive in real life.  :-)

Pete - Team Cosmos

Progress Reports / Re: Team Anarchy Robotics
« on: January 16, 2017, 11:18:36 pm »
Pete, it'd be great to see you out our way! You can always guest judge a few fights if you'd like..  ;D  I do want to make it out your way some time for Bolder; looks like such a fun time (hope for next year?). This time around, it's such a balancing act. I'm still training for a marathon in March and 50 miler in April on top of this, and then have to financially recoup. Hoping the investments made now will hold up over a few tournaments so that I can do proper upgrades instead of bandages.

If you make it out here for the Bolder Boulder, be sure to let me know.  I've been running it for a good long time, each year seems crazier than the previous.  Here's the running group from a few years back.

Pete - Team Cosmos

Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: January 16, 2017, 11:08:17 pm »
I'm getting more optimistic about making it to Moto, it looks like the timing will work out.  Just as a spectator though.

Pete - Team Cosmos

Progress Reports / Final Notes
« on: January 16, 2017, 12:34:56 am »
I just realized I never really closed this topic up.

The electronics work on Angry 3 took a long time.  I switched from using Bluetooth to a normal 2.4ghz receiver.  It was smaller, gave me channel data on a single PPM line that I could decode with the Arduino, and didn't have any binding issues, unlike the Bluetooth module.  Soldering the drive ESCs, the brushless weapon controller, the Arduino, and the receiver into a tiny 1.3" X .85" X .65" cube was challenging.  I shorted something out twice, blowing up a few components in the process.  The third time was the charm.

I competed at the SparkFun AVC contest in September.  I had some driving issues, Angry didn't like to drive straight.  But she stood up to some big hits.  There was some cosmetic damage, but all-in-all did well, getting 3 wins and 2 losses.

I'm planning on heading to RoboGames in April to compete with her, and it sounds like another Ant/Beetle competition will be held in Boulder in April as well.

Meanwhile, I created a Team Cosmos Facebook page, and have been posting updates there.  You can find that here:  https://www.facebook.com/TeamCosmosBots/

Pete - Team Cosmos

Progress Reports / Re: Team Brain Damage
« on: January 16, 2017, 12:03:13 am »
Hey Pete! I have to say that one of the reasons I do these build reports is how much I enjoyed reading through the ones you and Toni did back in the day. Your work was an inspiration to me and a host of other builders. With all the people coming out of the woodwork for Motorama this year I was hoping to see you guys up again too, but it is quite a trip. Hope the snowboarding is great this year.


Thanks for the kind words! 

The snowboarding is great this year, we're getting crazy snowy weather, like a lot of the country.  On the other hand, I am spending a lot more time in the garage and am enjoying making the chips fly.

I'm trying for Motorama, the main challenge there is more work related than snow related.  It'd be a lot of fun to be back in the thick of things, even as a spectator.

Pete - Team Cosmos

Progress Reports / Re: Team Anarchy Robotics
« on: January 11, 2017, 04:29:15 pm »
Hey Jon!  Great to see you getting back into it.

I'm going to try to swing by Motorama as a spectator this year.  No promises, but I'll definitely say Hi if I make it out that way.

Pete - Team Cosmos

Progress Reports / Re: Team Brain Damage
« on: January 08, 2017, 12:50:18 pm »
Very cool stuff, Zac!

Pete - Team Cosmos

Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: October 12, 2015, 11:07:10 pm »
I added a motor guard with a bit of the weight I had left over.  Things are pretty protected at this point, have to admit that I'm happy with the design.  I have almost an ounce left for weight, I'm still toying what to do with that.  I still need a new weapon blade, weapon shaft, and a few holes in the top plate for power access and radio use.

Pete - Team Cosmos

Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: September 20, 2015, 05:53:09 pm »
Progress has slowed down a bit, but I'm making a bit here and there.

Here are the electronics wired up and working.  Things barely fit in the body, it's a tight fit.  Note the classic electrical tape, hopefully preventing shorts of any sort.

I can drive angry around via a telnet session, but that's pretty rough.  Next step is to write a test program so I can have more intuitive controls.  I'll post some video once I have that working.

Pete - Team Cosmos

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