Go to Post People misuse GP because they see Dean as some sort of whimsical cross between the Nutty Professor and Mister Rogers and think that FIRST is Disney World and we're all going to happily hold hands around the campfire and sing happy songs all day long. - Koko Ed [more]
Home
Go Back   Chief Delphi > Technical > Electrical
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
 
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 19-01-2005, 16:48
zdeswarte's Avatar
zdeswarte zdeswarte is offline
Registered User
AKA: Zack
None #1240 (LHS Robotics)
Team Role: Electrical
 
Join Date: Nov 2004
Rookie Year: 2004
Location: Manitowoc, WI
Posts: 43
zdeswarte is on a distinguished road
Send a message via MSN to zdeswarte
Accelerometer vs Gear Tooth Sensors

I was just wondering if my team should use an accelerometer or two gear tooth sensors on each side of our bot to make sure it is moving straight. It seems like the accelerometer is way too touchy to set up on the robot but the gear tooth sensors seem pretty easy to put on and overall more practical. With the gear tooth sensors, we would just compare the gear tooth rate on each side and regulate voltage going to the motors until the gear tooth rates of each side are equal. We have no clue what we would do with the accelerometer. Our team is a complete rookie team but we have a bunch of seniors that are in advanced electronics and advanced engineering, so we have a strong base. What would everyone recommend we do?
  #2   Spotlight this post!  
Unread 19-01-2005, 17:02
geeknerd99's Avatar
geeknerd99 geeknerd99 is offline
Fire Hazard
AKA: Daniel Lin
FRC #0401 (Hokie Guard)
Team Role: Programmer
 
Join Date: Oct 2004
Rookie Year: 2005
Location: Blacksburg, VA
Posts: 276
geeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud ofgeeknerd99 has much to be proud of
Send a message via AIM to geeknerd99 Send a message via MSN to geeknerd99 Send a message via Yahoo to geeknerd99
Re: Accelerometer vs Gear Tooth Sensors

This is my rookie year, and I already got delegated to figuring out how to use the camera, gear counters, and the accelo-thingie.

Counting the gear teeth is probably the only logical thing to do with the counters (duh), unless you felt like gearing a manipulator that couldn't be brute-forced safely.

As for the accel., I guess the best use for it is to detect side-to-side movement during the auto period. Just because your bot moved to the side does not mean that the gears turned, especially with this year's gearboxes. So, the accel. may (or may not) cover this angle.

Once I find the code, I'm going to try to combine the two to create a point-to-point system. The only trouble is that the accel. seems like it would be a bit twitchy, and figuring out how far it was bumped using g-forces seems like it would be hard. Also, figuring out how to code the auto period so that any recovery manuevers aren't counted as going to the given point is going to take a while.

Oh well. I might post some code up later, since the meeting is tonight.
__________________

Last edited by geeknerd99 : 19-01-2005 at 17:06. Reason: Didn't fully comprehend the post and forgot to answer a question...
  #3   Spotlight this post!  
Unread 19-01-2005, 17:28
zdeswarte's Avatar
zdeswarte zdeswarte is offline
Registered User
AKA: Zack
None #1240 (LHS Robotics)
Team Role: Electrical
 
Join Date: Nov 2004
Rookie Year: 2004
Location: Manitowoc, WI
Posts: 43
zdeswarte is on a distinguished road
Send a message via MSN to zdeswarte
Re: Accelerometer vs Gear Tooth Sensors

Its our meeting tonight too... I was just talking with someone on my team and we came to the idea of having the gear tooth rate balancing program on a toggle switch- turn it on when going straight, turn it off when turning. Whatcha think about that idea?
  #4   Spotlight this post!  
Unread 22-01-2005, 14:55
Tom Bottiglieri Tom Bottiglieri is offline
Registered User
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: Jan 2004
Rookie Year: 2003
Location: San Francisco, CA
Posts: 3,182
Tom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond repute
Re: Accelerometer vs Gear Tooth Sensors

Quote:
Originally Posted by zdeswarte
Its our meeting tonight too... I was just talking with someone on my team and we came to the idea of having the gear tooth rate balancing program on a toggle switch- turn it on when going straight, turn it off when turning. Whatcha think about that idea?
It might be alot easier if you just check to see if the joystick's values are within a certain window. This way the driver does not have to flip a switch when he wants to turn.
  #5   Spotlight this post!  
Unread 22-01-2005, 15:35
Joe Johnson's Avatar Unsung FIRST Hero
Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
Location: Raynham, MA
Posts: 2,629
Joe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond repute
Re: Accelerometer vs Gear Tooth Sensors

Closed loop feedback is beautiful.

I would recommend that you use the joysticks to command desired speed and robot turn rate (0 = straight).

Using gear tooth encoders (and a gyro if you want to deal with the slipping wheels problem) you can measure both these actual values.

Compare the Actual to the Desired values to generate error signals. There are many well know methods (including PID control) that allow you to calculate the output you need to drive the error toward zero.


It is a beautiful thing. Your machine goes straight when it should and turns beautifully too -- easy on the operator and easy to control.

Joe J.
__________________
Joseph M. Johnson, Ph.D., P.E.
Mentor
Team #88, TJ2
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
gears Michael Leicht Inventor 12 16-09-2004 10:52
Reverse Gear FizMan Technical Discussion 12 26-04-2004 01:29
Coupling the drill motor with out the 15 tooth gear Chopper_Dave Motors 1 17-01-2004 01:06
Thunder Chicken CCT Simon G Motors 4 03-01-2003 13:18
"Motors and Drive train edition" of Fresh From the Forum Ken Leung CD Forum Support 6 29-01-2002 12:32


All times are GMT -5. The time now is 04:39.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi