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Unread 13-01-2004, 10:23
Chris Hibner's Avatar Unsung FIRST Hero
Chris Hibner Chris Hibner is offline
Eschewing Obfuscation Since 1990
AKA: Lars Kamen's Roadie
FRC #0051 (Wings of Fire)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1997
Location: Canton, MI
Posts: 1,488
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Misnomers - Please Don't Use

Quote:
Originally Posted by Rickertsen2
Line tracking?

Dead reckoning based on timing?

Dead reckoning based on encoders?

Dead reckoning based on gyros and accelerometers?
Rarely do I stand up on a soapbox and preach, but I'm going to do so here:

Dead reckoning comes from ded. reckoning, which is short for DEDUCED reckonking. Ask anyone with a pilot certificate or someone who has taken a large-water boating class and they should know the definition.

The reason it is called deduced reckoning: You know where you started, you have an approximate idea of your heading, and you have an approximate idea of your speed. So by using TIMING, you can DEDUCE where you are after a certain amount of time. Do you KNOW where you are? NO!!! You only have an approximate idea via deduction.

When you KNOW where you are, via sensing capability, it is NO LONGER dead reckoning - it is guidance and measurement. There is a HUGE difference. One method knows quite precisely where you are, and the other method is just a decent educated guess.

The reason that I am preaching is because is becomes very difficult to describe how your autonomous mode works when everyone uses incorrect terminology.

Here's a quick example: Our team last year had a guidance system. We tried to describe it to some teams, and here was a typical conversation:

Other team: "You guys say you are fast, you must use dead reckoning."
Us: "No, we use a guidance system."
Other team: "huh?"
Us: "We use an angular rate sensor and a measurement wheel to calculate our position on the field."
Other team: "So, you use sensors. You must be slow."
Us: "No, we're not slow."
Other team: "But I read on ChiefDelphi.com that dead reckoning is the fastest method. If you're not dead reckoning, you must be slow."
Us: "No, we're not slow. We use sensors so we can go as fast as possible."
Other team: "So, you follow the line? I hear that is REALLY slow."
Us: "No, we don't follow the line. We use angular rate sensors and a measurement wheel."
Other team: "Oooooohhhhh. You dead reckon. Why didn't you just say so?"
Us: "AAAAAAAAAAAHhhhhhhhhhhhhhhhhhhhh!!!!!!!!!!!"

This is pretty much an actual conversation from last year. Why does it ruffle my feathers so much? Because it lumped us (with our wonderful guidance system that was virtually impossible to throw off) in with the dead reckoners that could be thrown off with a well placed bin or a low battery.

Sooooo......

I would appreciate it if we could please start using correct terminology now, so that when I get to the competitions, I don't need to have a repeat of the above conversation.

Whew, that was a long one. Now, let's see if I can get off the soapbox without getting hurt.

-Chris
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