Go to Post Thanks GDC for opening a can of Chuck Norris Brain Hurt - Garrett.d.w [more]
Home
Go Back   Chief Delphi > Other > FIRST Tech Challenge
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 14-04-2014, 16:39
Wingus&Dingus Wingus&Dingus is offline
Registered User
FTC #7440
 
Join Date: Dec 2013
Rookie Year: 2009
Location: New Zealand
Posts: 11
Wingus&Dingus is an unknown quantity at this point
[FTC]: TETRIX DC Motor Gearbox issues

So we've broken a couple of lift arm motors.... both V1 and V2. Mostly gearbox destruction.
We're reasonably confident everything we can do to prevent this happening has been done but we struck a new issue this morning.
If there's a loss of control due to communication issues sometimes motors get left running at whatever power they were last set to and with our lift arm that's not a good situation. Under normal circumstances the arm won't ever hit the mechanical stop points at full power (actually it's limited to +-70) and there's position feedback and limit switches so all is well but if communications stops we can quickly end up with another busted gearbox.

Do we need to manufacture a clutch so there's a last ditch mechanical safety system?
Has anyone else struck a similar problem and what did you do about it?
Reply With Quote
  #2   Spotlight this post!  
Unread 15-04-2014, 10:45
TRWSHSHLX TRWSHSHLX is offline
Registered User
AKA: Henry Lei
no team
 
Join Date: Jan 2011
Rookie Year: 2008
Location: OR
Posts: 71
TRWSHSHLX is an unknown quantity at this point
Re: [FTC]: TETRIX DC Motor Gearbox issues

If you have position feedback / limit switches, program the lift such that if the limit switch on top is hit (when the lift is at maximum height), it can only go down or stop.

The second way is to go into one of the default files (some other team did it and posted the code on here before - I will try and find it) which adds a logic that says if data isn't refresh in a certain amount of time, it sets all the joystick inputs to zero / default.

EDIT: here is the link with said thread.
__________________

Last edited by TRWSHSHLX : 15-04-2014 at 10:51.
Reply With Quote
  #3   Spotlight this post!  
Unread 15-04-2014, 11:55
Andrew Lobos Andrew Lobos is offline
Registered User
FRC #0225 (TechFire)
Team Role: Mentor
 
Join Date: Feb 2011
Rookie Year: 2011
Location: Lancaster, PA
Posts: 61
Andrew Lobos is a jewel in the roughAndrew Lobos is a jewel in the roughAndrew Lobos is a jewel in the rough
Re: [FTC]: TETRIX DC Motor Gearbox issues

Quote:
Originally Posted by TRWSHSHLX View Post
If you have position feedback / limit switches, program the lift such that if the limit switch on top is hit (when the lift is at maximum height), it can only go down or stop.

The second way is to go into one of the default files (some other team did it and posted the code on here before - I will try and find it) which adds a logic that says if data isn't refresh in a certain amount of time, it sets all the joystick inputs to zero / default.

EDIT: here is the link with said thread.
In the event of a NXT brick lockup or motor controller freeze (due to a bad battery connector or brownout), the only solution that guarantees safety of your robot is a mechanical solution.
Reply With Quote
  #4   Spotlight this post!  
Unread 16-04-2014, 00:15
Wingus&Dingus Wingus&Dingus is offline
Registered User
FTC #7440
 
Join Date: Dec 2013
Rookie Year: 2009
Location: New Zealand
Posts: 11
Wingus&Dingus is an unknown quantity at this point
Re: [FTC]: TETRIX DC Motor Gearbox issues

Thanks for the responses. We've implemented a mechanical safety to minimize shock loads on the gearbox. Ended up testing it by mistake today after accidentally disconnecting the arm position feedback! No more broken gearboxes.
Reply With Quote
Reply


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


All times are GMT -5. The time now is 08:01.

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