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Big AL
Experienced Roboteer


Joined: 16 Oct 2004
Posts: 436
Location: roleystone perth. WA


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feed back

i just need some thought on length and hight for my robot and need you to tell me if this would work.


outsite
steel frame
aluminium plateing steel on the back

weapon
steel disc with added teeth to snag and throw
driven by a electric drill moter geared up

inside
two seperate drill motors for wheel drive
chain with rubber attached for grip as wheels
a couple of batterys to run things

that's what ive thought of so far

just a few things

i don't know much of the electronics needed so i need help with that but i want this to happen

i want the disc so i can flick it on and off at the controler
and i need to know how to wire it all up

thanks for any help you can offer
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Post Thu Oct 21, 2004 11:12 pm 
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Ajax
Experienced Roboteer


Joined: 17 Jun 2004
Posts: 298
Location: Sydney


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The only thing that I think would need changing in the hardware side of things would be a bigger motor for the weapon.

Fan Motors form a car wreckers is on source. Another sourcecould be truck wreckers.

Or do the Arron trick.. one winch motor (super cheap auto's)

for the electronics, there are a couple of way to go
1. IBC. has all the functions that you will need. http://robowars.org/store.html
2. look at http://www.robotmarketplace.com/ for some other controllers
3. look at some other US & UK teams to see what they have.
4. There are some others that are devaloping some other type of controllers. (Can some please extend on this.)
5. make your own. (Not recomended)
6. go to a hobby shop, and watch there eyes pop out of there head when you explain what you want. (There are some that are very helpfull.)

The IBC is what I have as do others in australia.

for a weapon relay there are many choices, have a chat to some others for what they have done.

i am working on a micro processor controlled MosFet relay, with over current & temperature shut off. this will connect directly to the IBC, and if I get it working reliably can be connected directly to a channel of the radio.
But it is still in devalopment, then I need to test it.

some one else may be further with a simular design, or some thing else all together.
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Post Fri Oct 22, 2004 12:34 am 
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andrew



Joined: 16 Jun 2004
Posts: 3110
Location: Castle Hill, Sydney. N.S.W


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The Ibc and other speed controllers are not essential though. if i dnot have the money then u could modify a drill trigger for speed controlll or even uise microswitches to make it move. although its only on/off controlls.

The council cleanup masterpiece that is robort use switches for drive and is very easy to controll/steer and does very well.
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Post Fri Oct 22, 2004 6:43 am 
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Spockie-Tech
Site Admin


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


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Thats true, but Al, make sure you understand that to be legal to compete at any public-event (or anything other than a back-yard competition), some form of "failsafe" is required - A system that shuts down the robots weapon and drives when the radio link is lost.

Standalone Servo-driven switches will not failsafe and so are not allowed at RoboWars - the other (private) events usually do allow them at the moment, but this will probably change as those events grow.

You can make servo-switches legal with the addition of a small hobby failsafe-unit for about $30-$40 per channel, but by the time you get up to 3 channels (2 drive, 1 weapon), and have to add $100+ worth of failsafes suddenly they dont look so cheap any more.

I have heard that the modified drill-trigger method will shut-down when the radio fails, but havent seen this for sure yet, but that might be an option.

Depending on how tight the budget is, the easiest and most reliable method is always to just buy an electronic speed controller with failsafe, mixing, weapon control and so on built in, which is why 90% of teams go that way, but there are cheaper alternatives if you dont mind fiddling about a bit.
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Post Fri Oct 22, 2004 9:59 am 
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Glen
Experienced Roboteer


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


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hey big al,

not sure whether your an engineer with a massive lathe and mill or a 12 year old with a cordless drill but ill do my best to answer.

i would save your big gun ideas for later and get a basic bot moving. kang is now sittting on my table consisting of a computer case, two xu1 cordless drills, 2x 2.3ah SLAs and some servo switching controllers.

i would not consider an IBC or other controller a worth while investment unless you have some experience and know your electronics well to save you plugging your $320 investment in the wrong way and watching a cloud of magic smoke eventuate.

you seem on the right track though. i would suggest you read our build reports on this forum as i think its more worthwhile than reading about a 150kg flame throwing spinning monster.
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Post Fri Oct 22, 2004 5:31 pm 
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Windhammer



Joined: 19 Jun 2004
Posts: 338
Location: Roleystone WA


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Glen
[not sure whether your an engineer with a massive lathe and mill or a 12 year old with a cordless drill but ill do my best to answer.]

Laughing lol glen his a 14 year old with a cordless drill.

ALEX you can run a spinning disk with a drill but it wouldnt be worth it, even if you want to gear it up they only do 550-700 rpm and geared up thats going down to as low as 300-400rpm and spinning a flywheel and u wont be able to dish out damage worth the bother so just use a heater motor. i thought i told u at school

Post Fri Oct 22, 2004 5:56 pm 
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Glen
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Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect


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sounds like the WA scene encompasses windys school friends lol.

but anyways a cordless drill isnt a BAD weapon motor. its just not a GOOD one :p budget bot springs to mind. that had a cordless drill motor and gearbox behind it and hit pretty hard with its swinging arms.
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Post Fri Oct 22, 2004 6:23 pm 
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Totaly_Recycled
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Joined: 15 Jun 2004
Posts: 1346


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Brett all the servo dril triger type speed controlers i have made ((dont fail safe )) ..my servo board-fet controlers did most times as once the signal from the radio was shut off then they couldnt get any pwm so just stopped but could sometimes get a small jitter if they got an interferance signal like from a close unsupresed motor or a welder ect

Post Fri Oct 22, 2004 7:45 pm 
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prong
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Joined: 19 Jun 2004
Posts: 839


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here is a site i found with a fairly simple to build failsafe
http://www.rc-cam.com/rcfs.htm

but i think this is looking at everyhting the wrong way, no need for an electronic failsafe, as far as i can see if i put a spring/rubber band etc on my servo control horn so at full extend the servo has just enough power to activate a microswitch and hold itself there, and when power is taken off the servo the spring etc pulls the servo back into centre position.

Having a play with my servos they do not take much to move by hand, something fairly stiff and springy will easily haul them back to centre when their power is off.

this would count as a failsafe because if you turn off your controller then it will cut drive and weapon power. Also this has the bonus ability that if your receiver batteries die then it will still failsafe.

anyway this would seem like a very simple and cheap way to failsafe, unless there is something i have missed?

Post Sat Oct 23, 2004 8:12 pm 
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Big AL
Experienced Roboteer


Joined: 16 Oct 2004
Posts: 436
Location: roleystone perth. WA


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more questions

need some info weight by cm cubied to make my cauculations if you can get them to me

1 steel by cm2
2 aluminum by cm2
3 average weight of an electric drill motor and battery

as for the fail safe and drive controls i probably going to by a ibc controler plz tell me if it comes with a hand set or if you supply your own and if you do do you have to install your own crystles also dose it come with it's own transmiting equipment or is that also bought seperatly

thanxs
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For West ausies interested in robotics email me at: theoneshrug@hotmail.com
OR
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best quote ever:: "Those Gas-Turbine style warehouse heaters arent illegal, and neither is remote controlling one as far as I know."

Post Sat Oct 23, 2004 9:56 pm 
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Glen
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Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect


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density (g/cm^3)
steel 1020 7.75
steel stainless 201 7.86
Titanium grade 5 4.42
Brass C36000 8.498
Copper C110 8.885
Plywood 0.615
Lexan 1.2
aluminium 2.767
UHMWPE 0.944
Fibre glass 1.8
Carbon Fibre 1.57
Kevlar 1.384
Polyurethane foam 0.1

thats what i use.

as for the drills on jeffs scales i read 540g for the motor and gearbox and a red wheel (which weighs 150g on its own.)

drill battery? one 12v 1200mah figure about 600g or so
a 2.3ah SLA is about 1kg on the dot
a 7ah SLA weighs some 2.8kg

nope you have to buy your own radio set and they come with crystals. the IBC is just the controller that you plug your radio into (the radio you supply yourself..)
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Post Sat Oct 23, 2004 10:06 pm 
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colin



Joined: 16 Jun 2004
Posts: 102


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The internet is notorious for being full of information and there is even things to search it with like google

Post Sat Oct 23, 2004 10:45 pm 
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Big AL
Experienced Roboteer


Joined: 16 Oct 2004
Posts: 436
Location: roleystone perth. WA


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electricaly stumped

iv no idea abot the electronic i want to know what to do. im looking at a ibc but the price is kind of puting me off. what would be a cheaper alternative?

like i said befor i have NO experiance with electronics Shocked also diagrams mean very little to me as i haven't been shown how to read them .

any help would be great

Thankx
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For West ausies interested in robotics email me at: theoneshrug@hotmail.com
OR
dragoonarie@gmail.com
best quote ever:: "Those Gas-Turbine style warehouse heaters arent illegal, and neither is remote controlling one as far as I know."

Post Mon Oct 25, 2004 1:28 pm 
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Spockie-Tech
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Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


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While I'm admittedly biased (being the designer of the IBC), I dont know of any cheaper alternative that can do what the IBC does, or else I'd be using it ! Wink

Yes, they are one of the more expensive parts in your robot, but they are also the key component that turns a bunch of wires, batteries and motors into a remote controllable machine.

There are cheaper alternatives, but they all have some significant disadvantages to take into account..

Servo switches are the cheapest, but are fiddly to make, prone to mechanical failure, have no variable speed control, no mixing of throttle and steering, no failsafe (making them illegal for compeition use), no braking and no weapon control.. quite a list of disadvantages.

Drill-Trigger speed controllers are even fiddlier to make, but add variable speed control and a simple failsafe function, although they can only operate over a very narrow voltage range and still have the rest of the disadvantages of the servo switches.

Probably the next best step down from an IBC is the Electronize controllers from the UK.. http://www.electronize.co.uk/model_electronics_frames.htm . They use a single mosfet with relay reversing that makes them cheaper to build, but have the occasional problem of relay contacts welding together. You need one per motor and still would want mixing and so on, but some radios can do this..

There is however, a reason that practically *all* competitive combat robots use an ESC (Electronic Speed Controller) of one sort or another.. Most of the alternatives just dont work reliably.. Ask Jeff (Singularity's Driver) how many of his early losses were due to home-made switch-controller failure (and he's very electronics capable).

An ESC, Radio, Batteries and Charger will likely make up 80% of the cost of your robot to start with, but if you look after them, you should only need to make that investment once and hopefully its the cheap stuff (metal, wheels, drill motors etc) that gets broken and needs replacing in most matches.
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Post Mon Oct 25, 2004 1:57 pm 
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Big AL
Experienced Roboteer


Joined: 16 Oct 2004
Posts: 436
Location: roleystone perth. WA


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i heard some one was getting one for $200 second hand liked to have know where from and what was wrong with it.

how long should i have made mine i was thinking round about 40cm long by 30 cm wide by 20 cm tall are these good dimentions?and how thick tubing should i use

by the way what type of disks can i use for a spinning disk i was thinking of using a steel plate with teeth for it but i don't know it is ilegal in battles
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For West ausies interested in robotics email me at: theoneshrug@hotmail.com
OR
dragoonarie@gmail.com
best quote ever:: "Those Gas-Turbine style warehouse heaters arent illegal, and neither is remote controlling one as far as I know."


Last edited by Big AL on Mon Oct 25, 2004 5:06 pm; edited 1 time in total

Post Mon Oct 25, 2004 3:59 pm 
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