Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
If you are tight for size and weight, the Banebots motors might help:
http://banebots.com/c/PLANETARY
. They are longer than the Jaycar motors but the same diameter. They have an easy to use output shaft and mounting points so they can save space compared to drill motors. They cost more than drill motors butthe Aussie dollar makes them more atteactive at the moment.
Mon May 09, 2011 11:23 am
frogbiscuit
Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
Thanks Nick.
If they're not too much longer they might just work.
Even my own team complain that the 160rpm J-motors will probably be too slow. I may have to yield to the numbers. What's the best ratio if running the ubiquitous Bunnings red wheels?
Mon May 09, 2011 11:49 am
Jaemus Experienced Roboteer
Joined: 01 Apr 2009
Posts: 2674
Location: NSW
I think 600rpm is about what most of the drill motor conversions end up producing _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
Mon May 09, 2011 11:53 am
Knightrous Site Admin
Joined: 15 Jun 2004
Posts: 8511
Location: NSW
550rpm drills with a red bunnings wheels gives you roughly 10km/h top speed. It's a pretty average speed for a robot.
800rpm drills with red bunnings wheels gives you roughly 14km/h top speed. Bit faster and pretty nippy when driving.
1200rpm drills (2-speed drills / some hammer drills) with red bunnings wheels gives you roughly 21km/h top seed. A lot faster, great for a rammer but a bit more of a handful to drive.
You can also overvolt a bit to get some extra speed and torque, but you might stress the motors out too much and end up with some smoke sessions _________________ https://www.halfdonethings.com/
Mon May 09, 2011 1:06 pm
frogbiscuit
Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
Bear in mind that most fighting robots have only 2 drive motors, employing "tank drive".
My config has 6 motors sharing a load traditionally borne by 2 so each one doesn't have to be as big. The beauty of it is that there are no dedicated steering motors, every motor is a drive motor.
In theory yes in practice... maybe. _________________ Steven Martin
Twisted Constructions
http://www.botbitz.com
Mon May 09, 2011 1:39 pm
Knightrous Site Admin
Joined: 15 Jun 2004
Posts: 8511
Location: NSW
3 drill motors works fine for a 3-axis omnibot, QLD bot Sidewinder has proven that. You could also save yourself a lot of time, effort on custom micros and programming rigs and just buy a premade 3-ch omnibot mixer. http://www.robotmarketplace.com/products/RL-OMX3.html Would get you up and running a lot quicker and get your bot into the arena. _________________ https://www.halfdonethings.com/
Mon May 09, 2011 1:48 pm
Jaemus Experienced Roboteer
Joined: 01 Apr 2009
Posts: 2674
Location: NSW
do you have any sketches or cads you'd be willing to share? _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
Mon May 09, 2011 2:42 pm
frogbiscuit
Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
Yah, as soon as I figure how out to load it into this site's editor. Ya gotta reference from the site's picture archive?
Mon May 09, 2011 3:22 pm
Jaemus Experienced Roboteer
Joined: 01 Apr 2009
Posts: 2674
Location: NSW
use an image hosting service like photobucket _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
Mon May 09, 2011 3:30 pm
frogbiscuit
Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
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Mon May 09, 2011 3:49 pm
Jaemus Experienced Roboteer
Joined: 01 Apr 2009
Posts: 2674
Location: NSW
Cool!
That's going to be a huge robot.
I think the main concerns are that your wheels are likely to be hit by horizontal spinners, and that the whole bot is likely to be thrown up and crash down again by vertical spinner or flipper hits - so you'd want some beefy axles / output shafts on your motors to withstand that
I can see how you'd need a redesign though, looks like there's not enough room for a pair of drill sized gearmotors end to end between those wheels. Can you offset them and put the gearmotors side by side? _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
Mon May 09, 2011 4:07 pm
Knightrous Site Admin
Joined: 15 Jun 2004
Posts: 8511
Location: NSW
Ah, very interesting. Been a while since I've seen someone use that approach to an omni bot, although not a 100% true omnibot due to the nature of the bogies having to turn before the translation occurs.
Interesting but I worry about weight, how you are going to track position of the wheels and the time it will take to rotate the wheels to the direction you want to travel.
For your first bot something simpler might be wise.
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