www.robowars.org

RoboWars Australia Forum Index -> Technical Chat

Oscillation?


Post new topic   Reply to topic
  Author    Thread
comanche



Joined: 22 Feb 2007
Posts: 22
Location: melburn


 Reply with quote  
Oscillation?

How would i make a turret oscilate up and down at say 0 - 70 degrees without having to reverse the polarities to go either way?
I will only be using one motor.
Simplistic is the best answer.

Post Tue Jul 24, 2007 10:55 pm 
 View user's profile Send private message
Valen
Experienced Roboteer


Joined: 07 Jul 2004
Posts: 4436
Location: Sydney


 Reply with quote  

servo or a cam
_________________
Mechanical engineers build weapons, civil engineers build targets

Post Tue Jul 24, 2007 10:59 pm 
 View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger MSN Messenger ICQ Number
dyrodium
Experienced Roboteer


Joined: 24 Aug 2004
Posts: 6476
Location: Sydney


 Reply with quote  

I would say a really low RPM gear motor and a simple machine called a cam.
http://en.wikipedia.org/wiki/Cam
Smile
_________________
( •_•)

( •_•)>⌐■-■

(⌐■_■)

YEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH

Post Tue Jul 24, 2007 10:59 pm 
 View user's profile Send private message Visit poster's website MSN Messenger
comanche



Joined: 22 Feb 2007
Posts: 22
Location: melburn


 Reply with quote  



Something along the lines or that?

Another question: Whats a good capacitance for a drive motor in order for steady acceleration. (I have tracks, not wheels) NO ESC.

Post Tue Jul 24, 2007 11:20 pm 
 View user's profile Send private message
Nick
Experienced Roboteer


Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW


 Reply with quote  

Servo - possibly modified for endless rotation. or a motor with a crank linkage such as used in windscreen wipers or steam engine drives.

EDIT: a crank and cam are very simlar, but the crank is easier to make and doesn't rely on gravity for the turret to follow the cam.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Post Tue Jul 24, 2007 11:27 pm 
 View user's profile Send private message
Glen
Experienced Roboteer


Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect


 Reply with quote  

yeah my suggestion would be a crank like the windscreen wipers.. least you have a positive force to bring it back down.

and making two pieces of flat steel for the cranks is easier than grinding out a cam anyway Smile
_________________
www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

Post Wed Jul 25, 2007 8:21 am 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
Valen
Experienced Roboteer


Joined: 07 Jul 2004
Posts: 4436
Location: Sydney


 Reply with quote  

you aren't going to be able to use a cap to give you a slow start on a motor.
not unless its measured in farads.
_________________
Mechanical engineers build weapons, civil engineers build targets

Post Wed Jul 25, 2007 10:33 am 
 View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger MSN Messenger ICQ Number
Spockie-Tech
Site Admin


Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


 Reply with quote  

Assuming the Tank is RC-Controlled - Why not just use a servo to directly control the turret elevation through a linkage ?

That way it doesnt just go up and down in a cycle, you can actually control it (if you have a spare RC Channel) - This place has some interesting high power servos and linkage and stuff - http://servocity.com/

If battery life/efficiency isnt as critical as it is in a combat robot (where carrying more battery power than you need is a waste of weight), the cheapest way to do soft-start without an ESC, is something like the Tamiya 3-speed resistive speed controller - provided your drive motors dont suck too many amps.

You could even cobble a more variable one up out of a big wirewound potentiometer (maybe a dashboard dimmer out of a 70's car ?) and a servo. Probably be ok for 10 - 20 amps if you dont get into a pushing/stalled motor situation.

How big is this tank and its motors ?
_________________
Great minds discuss ideas. Average minds discuss events. Small minds discuss people

Post Wed Jul 25, 2007 11:03 am 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
Knightrous
Site Admin


Joined: 15 Jun 2004
Posts: 8511
Location: NSW


 Reply with quote  

Maybe use one of those $5 Jaycar solinoids to raise the turret? on/off switch is all you need then Smile
_________________
https://www.halfdonethings.com/

Post Wed Jul 25, 2007 11:34 am 
 View user's profile Send private message
  Display posts from previous:      

Forum Jump:
Jump to:  

Post new topic   Reply to topic
Page 1 of 1


Forum Rules:
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

 

Last Thread | Next Thread  >
Powered by phpBB: © 2001 phpBB Group
millenniumFalcon Template By Vereor.