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Since we now have a few robots I thought we'd make a new thread for the team and put everything there.
First up some photos!
http://i1228.photobucket.com/albums/.../AllRobots.jpg
http://i1228.photobucket.com/albums/...zaMk2Close.jpg
http://i1228.photobucket.com/albums/...Mk2CloseUp.jpg
http://i1228.photobucket.com/albums/...a/BitzaMk1.jpg
http://i1228.photobucket.com/albums/...tza/Spinza.jpg
Some help required.
I need to control, via R/C what I believe to be a SPDT/CO switch...
The actual switch has three positions, centre is off left is on on and right is the other. Can someone advise a suitable RC switch to control this please?
Don't want to use servos.
Thanks!
Any one?
I think this will do it:
http://www.ebay.co.uk/itm/2-WAY-Radio-C ... 3379e61eb9
What MOD gears do people typically use in FWs?
As far as I can tell MOD is simply the distance between teeth on the gear, is that correct?
Also, am I correct in thinking that gearing ratio between 2 gears to be the division of how many teeth each has?
So a 5:1 reduction would be achieved with a 10T pinion and a 50t spur?
Yep, nailed it in 1.
I use Mod 1 gears in Satanix. Not had them wear out yet.
What sort of top speed do people aim for when doing their gearing reductions? About 10mph? Or higher?
Our machine can do about 10mph and it feels plenty fast for a small arena. A 12v drill setup at 12v does about 7mph. Maybe use that as a guide?
Unless you're confident your drive motors will get you to 10mph quickly it's perhaps best to aim a little lower?
Is this for a new machine or Bitza upgrades? :o
New machine, on paper works out at 3hp in the drive! All made from bits and bobs, just trying to figure out a suitable gear reduction.
THATS my kind of robot:)
that's like 20x more powerful than gimsons
i don't beleive it will work but just hope someone is clearing out their cellar and saying,
do i really need this binfull of rare earth magnets.
3hp isn't going to stick to the floor
and guess what.
USLESS POINT OF REFERENCE:
http://shop.mobileweb.ebay.co.uk/search ... Kw=true&cm
d=SREF
nope
No magnets, unless we happen to find some, we do have some incredibly wide wheels though!
So what sort of top speed do people aim for? Cobalt seemed a good speed, Satanix perhaps too high, the new Aftershock had good drive, 540 moved like a fly!
i think its good to have a higher top speed than you would maybe use all the time, however you don't want it crazy so you can't control it. Plus i'm guessing you'll only be using this in the RC arena which isn't huge so i think 10mph top end would be good
Given these statements would it be a good idea to gear for a top speed double what you want so you're running 100-50% Torque and 0-100% Horsepower over the speed range you'll actually likely achieve?Quote:
PMDC motors have the following characteristics:
They produce their maximum torque at zero RPM.
They produce zero torque at their maximum RPM.
They develop their maximum horsepower at 50% of their maximum RPM.
At 50% of maximum RPM, they produce 50% of their maximum torque.
At maximum horsepower, they are no more than 50% efficient.
No... The balance to be made is between torque and speed, making your gear reduction half what it would otherwise be will slow you to a ridiculous extent as your acceleration would be hopeless. 'Horsepower' doesn't really matter, it's just a hint at torque/speed characteristics which you should be designing around. The best thing is to use the tentacle calculator to try some gearing combinations with a motor similar to yours, and enter a realistic tire coefficient then you can click the 'acceleration' button for more information: http://www.architeuthis-dux.org/torquecalc.asp
Thanks for this.
I think I found an appropriate motor, not sure what I'm looking at though or what my tyre friction coefficient would be, or how I can find it.
Any idea how big the RC arena is corner to corner?
Also what's a good effective pushing force figure / time to top speed?
I get 27lbs and 0.7s
Cheers,
care to share your link to the mythical motors?
or are they your secret?
Pretty sure it's 5m x 4mQuote:
Originally Posted by PJ-27
the 3 horeswpower ones i meantQuote:
Originally Posted by archie2000
sorry if that was confusing
I was going to keep it a secret, but I think it'll be a bit anti-climatic so I'll just say.
They're car fan motors, overvolted to 24v. Managed to find a matching pair, also found some incredible wide wheels to put the power down with.
Next question!
On a spinning disk with 3 legs connecting the outter rim to the middle will it throw the balance if I put 2 teeth on opposite sides?
it shouldn't if there even
Since no one wanted to come play with the wooden robot idea and I had already made one I figured I'd do something worth while with it!
And so was born BitzaWood Revo
In keeping with the Bitza theme the disk is a master pulley from a V6 Modeo (Ditching the saw disks as they'll in ineffective against metal)
The armour is 2mm Stainless that I was given (odd shapes hence the multiple parts)
And I'm swapping out the MDF lid for a HDPE one courtesy of Mr Weston!
http://i1228.photobucket.com/albums/.../WODiskTri.jpg
No disk yet, but shows off the Ti front skid (Left over Ti from Bitza)
http://i1228.photobucket.com/albums/...ODiskFront.jpg
Got some Polycarb for the link cover. That way the light can shine through.
http://i1228.photobucket.com/albums/...iskbacktri.jpg
Disk, Bush and Tool Steel for the teeth:
http://i1228.photobucket.com/albums/...evelopment.jpg
Milling the Teeth:
http://i1228.photobucket.com/albums/...ngtheTeeth.jpg
I am in on the wooden robots but its back home so no pics, imagine La Machine with 4 gr01's, has the potential to have a saw blade fitted to it. Don't loose Bitza Wood!
I'm designing it so it can just got back to being only wood.
Don't know why the images are no longer loading. Here's the album:
http://s1228.photobucket.com/albums/ee4 ... od%20Revo/
I was watching your robot on youtube and in every video I've found Bitza is still wandering around at the end! It's like the most rugged thing ever! Fair play to you for recycling parts n still having an uber reliable robot lol! :D
Dave
Its kind of ironic... Bitza would keep going through pretty much anything. Now Bitza 2 gets stuck on pretty much anything. Go back to the original design :-)
Haha Cheers!
Bitza Mk1 was very tough but had no offensive capabilities, it just sort of bumbled about surviving.
Bitza Mk2 was a rush at the end and as a result had some serious flaws, hopefully next April we'll have found a common middle ground of offense and reliability.
I'm two thirds of the way through building the most basic of basic robots and it's really hard lol. I have this huge new respect for the people that do this and compete, even with a basic robot as there's loads and loads to learn. I'm a computer/server engineer by trade so I'm not clueless, but 'making stuff' from scratch is ace, and your robot has the whole ethos I have, ie 'what do I have lying around I can use to make this'. :D
Unfortunately it makes everything inherently heavy! Which at 13.6kgs is a real problem, but the amount we've learnt is invaluable.
Luckily Dan is now at Uni and has access to some nice equipment, so we've pivoted a bit and aren't quite as Bitza as before but still having fun and that's all that matters.
Question:
What is the reduction relationship between planetary gears (The Pinion and Ring gear)?
Am I correct in thinking it's the same as Spur gears, as in a division between the amount of teeth/circumference/diameter on each gear?
Cheers!
Yep, its identical
Thanks!
What's the catch?
http://www.ebay.co.uk/itm/Solid-State-R ... 35bb7a92d5
I stupidly blew the nice (albeit fragile!) Jaycar SSR we use for weapon control (reverse polarity, d'oh!) but at a 3rd the price what am I missing?
That's your catch :wink:Quote:
Output voltage: AC 24-380V
Output current: 100A
Input voltage: DC 3-32V
Control Method: DC to AC
Whether it has the potential to work like a Jaycar SSR I don't know (depends on the internal make-up). I'm not so clued up on cross compatibility with things like this.
Doesn't the jaycar one say a similar thing? I'll have to dig out my blown one. I figured the load side was just a big switch AC or DC?
From the Jaycar website:
http://www.jaycarelectronics.co.uk/prod ... ?ID=sy4086
Doesn't appear to be any mention of AC here, but again, I'm not sure if they can be used for both.Quote:
Output Circuit
€ Load Voltage: 0-30VDC
€ Load Current: 0.02-100A
€ Max On-State Resistance: 0.007Ohms
€ Max On-State Voltage Drop: 0.35V
€ Max Turn On Time: 0.5ms
€ Max Turn Off Time: 0.5ms
€ Max Surge Current: 240A (10ms)
Input Circuit
€ Control Voltage: 3-32VDC
€ Control Current: 28mA max.
€ Min Turn Off Voltage: 1.0VDC
€ Input Resistance: 1.2kOhm
It appears Jaycar do 2, one with a VAC output and one with a VDC.
Searching SSR on eBay and omitting VAC brought up some results, although finding a DC one (that actually is!) with a decent amp rating (80s +) is porving impossible let alone a good price.
This is the best I could do:
http://www.ebay.co.uk/itm/SSR-60DD-DC-t ... 20cd90f6c6
60a
And 80a at a premium:
http://www.ebay.co.uk/itm/Solid-State-R ... 230ffeaafb
PJ, I have another of the ones I sold you a while back, would you be interested in that? I don't have anymore spare so don't immediately blow it up this time :lol:
Hey Tony, that would be great! I'll try and make this one last longer!
I need to regulate the 24v in Bitza down to 12 for some cooling fans what's the best way to do this?
Most BECs regulate to 6-8v, or boosters increase voltage. Anyone know of a solution?
I doubt the current draw would be much so resistors could be a possibility?
Found this:
http://www.blackfiveservices.co.uk/fans ... &Target=12
http://www.technobotsonline.com/hv-s...regulator.html
Would this do?
Bit pricey but thanks for the link.
Given the low current draw of the fan I'm hoping a resistor will do but without knowing the exact amperage I can't calculate which resistor. Time to experiment!