Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
Finally got all the major parts together to get an overall idea of the finished product.
Arg, 17.5kg.
Looks like i gotta start over, or else find some lightweight action.
Sat Jul 30, 2011 3:41 pm
Jaemus Experienced Roboteer
Joined: 01 Apr 2009
Posts: 2674
Location: NSW
My favourite technique is to drill lots of holes in things until they are lighter!
usually results in them also being weaker but you have to break some eggs to make an omelette you see _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
Sun Jul 31, 2011 9:38 am
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
What most experienced builders do is come up with the design and then start a very detailed spreadsheet of parts and their weights - its the only way any of my robots stay remotely near to the weight limits and many times a design gets scrapped or radically changed.
The weight list needs to account for every nut and screw, cabling etc, but you can get most of that info from the supplier web sites.
Sun Jul 31, 2011 11:49 am
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
Yeah 17 half kg is beyond reduction i fear unless you've designed it from 20mm steel plate or something. Time for a rethink
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Perhaps its time to look at omniwheels again; that would save heaps of weight and achieve the same result. If you want a second opinion on anything just post the info here.
Sun Jul 31, 2011 12:04 pm
frogbiscuit
Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
Still overweight.
Found that you can only go so far gouging chunks with a holesaw, I saved 250g and nowhere near the 4kg needed. The weight has to be established at a more fundamental level. Guess I'll have to re-think the chassis and/or drivetrain.
Weapon is now fully functional, a joy to watch. After some evolution its more of a captive trebuchet. A single linear actuator retracts to cock it and then extends to trigger.
Sun Aug 21, 2011 10:49 am
dyrodium Experienced Roboteer
Joined: 24 Aug 2004
Posts: 6476
Location: Sydney
Sounds cool, would love pic/vid. Perhaps intially you can simply make a simple standard weapon platform to test the effectiveness? _________________ ( •_•)
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
That looks like some top-end machining work! My only advice would be to make it reload faster - the other bots will be wearing you down while the weapon resets and unless it is totally devastating, the opponents will beat you before you get to damage them. 10 out of 10 for originality.
Sat Sep 17, 2011 4:06 pm
Jaemus Experienced Roboteer
Joined: 01 Apr 2009
Posts: 2674
Location: NSW
interesting stuff! might be able to speed it up with more volts if the actuator can take it, and some fine tuning of the trigger / release mechanism. Alternatively hydraulics or pneumatics may be faster
are you planning to deploy it as an axe/hammer overhead weapon like the video suggests or as a flipper? _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
Sat Sep 17, 2011 4:29 pm
miles&Jules Experienced Roboteer
Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD
Hey looks cool!!! is it spring loaded? ...and a motor resets the spring?...vid was having trouble playing back on my computer. _________________ Miles Blow - Julie Pitts
www.mulesfilm.com.au www.wombokforest.com.au
-Pickasso- Vivid Sportsman champion 2015
Sat Sep 17, 2011 6:02 pm
frogbiscuit
Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
Nick:
There's a drillmotor and M8 threaded rod for a leadscrew. A real ball bearing screw would be better. So is it not plausible to duck-and dodge while the weapon locks & loads?
Jaemus:
I was thinking of a spike-studded steel ball on a short chain.
M&J:
A single linac loads and fires the weapon. It took some mechanical contriving to do that.
Footnote:
Haven't done anything in the last month, just chase up a vodeo camera. Don't you hate it when real life impinges on you robot life?
Sat Sep 17, 2011 10:17 pm
frogbiscuit
Joined: 26 Aug 2010
Posts: 82
Location: Wollongong
Raised voltage to 12V motor from 10 to 14V
Also, greased screw.
That hand-drilled coupling really sounds eccentric now. Wish I had a lathe.
That's considerably better. I'd consider going to 18V if you can though!
So is there some way to automate the reloading / firing process? It seems to me that you are doing the following (correct if im wrong)
1) bar is down
2) see this and position radio stick to retract bar
3) see the bar is fully retracted, then reverse stick to advance to point just prior to release
4) based on knowing how long this takes, stop before release occurs
5) move stick again to release (some lag here)
i would suggest that using microswitches and relays or a microcontroller, automate this such that you can have it retract and then cock itself again automatically, and then perhaps light a bright LED to make it very obvious it's ready to be fired
because there's no way you're going to be able to work out what its up to exactly during a match, which will result in a punishingly lengthy misfire and reset process if you overshoot it's cocked position and fire it unwillingly _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
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