Robo Challenge and uh... um...
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Robo Challenge and uh... um...
The 2 Dutch arenas , the well used Feather arena and the rarely used heavy arena both use OSB floor.
The German arena used in the past melamine covered particleboard, but has changed to OSB or plywood.
Well im guessing the robot being talked about is being built in England...so will be used in England for competitions.... the biggest competition for fw's in England is the UK champs.... which uses a steel floor.
I'm gonna use proper speed 900s, 1 per side, stick with reliability, and it's not a very high gear ratio, so it's gonna be quiet fast, but if its not powerful enough, with slow acceleration, then I will fit another, and steal the magnet idea for the robo chalange arena... Hopefully this robot is going to be more competetive than the last one...
What kind of gear ratio do I need to run a 1-2kg spinning bar from one of the fake eBay speed 900 like motors? 1:1, 2:1, 3:1, 4:1?
Depends on how many teeth you want, and how wide it is.
But the fakes, don't overvolt them to much, and use a large reduction gearing. (4/1 @12-18V sounds nice)
3000 rpm is a nice rpm for a disk.
It's a bar so 2 teeth- I will most probably run at 12-15v. I think 1:4 sounds good
Also- it says that the max rpm is 6700 so with a 4:1 ratio that would be 1675 not 3000?
Yes, 6700 rpm/4 = 1670 rpm
Maybe a 3 to 1 could work.
Sorry for all the questions- how many mah do I need for my battery pack when running one of the motors continuously for 3 mins to power the bar (so will sop and start and stall a fair bit)
I tried to work it out for myself but it came out as 60mah which sounds wrong so the correct equation to figure it out would be useful to!
Also, could I use this relay to control one of those motors? Could I control it directly from the receiver (connect the two terminals on the relay to the positive and negative terminals on the receiver without a battle switch?
@ 12V the original Speed 900 draws 54A max. Let us take that as a given. (I messured more, but hey, that's another matter)
54A for 3 minutes is 54/20= 2.7A used. LiPo doesn't like to be deep-discharged,so, we add 25% to that= 3.375A
A 3S 3500mAh 20C pack will do. Theoreticaly.
What kind of relay would you need to turn on and off 2 real Speed 900's? Something that can be linked directly to the Landing Gear PWM output of a transmitter would be good :)
i believe the set of you require is a battle switch linked to an automotive relay, I think 70 amp and upwards is the norm
However I don't have any first-hand experience
Get yourself a battle switch and one of these
http://www.jaycarelectronics.co.uk/prod ... rm=KEYWORD
The battle switch provides the RC interface to the receiver. You wire it up in such a way that when the battle switch is operated, it operates the solid state relay control side. The motor(s) are hooked up to the power side of the solid state relay. One of these will happily handle two speed 900s as long as it's attached to a metal panel to act as a heat sink
With little else to do this morning I have drawn up the following circuit diagram
http://imgur.com/skP9N
It should only be used as a guide! The important things to note are that the solid state relays are polarity sensative. Make sure that the negative pole goes to the negative connection on your batteries and same with the positive. You won't damage the relay if you hook it up the wrong way around but you will instead have a weapon system that will fire up when you put the removeable link in (not recommended)
I know it has been done in the past but will I have the only current robot with two speed 900's to power the weapon; just curious? I am also using a quite a low ratio 2.667:1 so the top speed will be really high (Approx 2500 RPM), I just hope that I can get it up to that in a fight!
Inertia XL uses 2 Speed 900s.
http://www.youtube.com/watch?v=5J6D7vZh6zk
2500 rpm is slow for a spinner and a single speed 900 will get there in seconds.
hi, omen runs 2 speed 900s.
2500 rpm in seconds pfft go brushless then get 0-8000rpm in 1 second :twisted:
http://www.madtomatoe.com/wp-content...Button-big.jpgQuote:
Originally Posted by mr_turbulence
Gadzooks! That was bigger than I was expecting :shock:
Rambunctious!
I guess Jamie REALLY likes the Brushless remark!
Well Dave posted that just after I worked out that the theoretical top speed from my brushless setup is going to be 7600rpm, so it really spoke to me, y'know :lol:
Does that mean I have invested in something which will be ineffective? Or will it work with the current quality of armour but not be as good as the brushless option? (which seems to cost about 4x more inc esc's!)
Speed 900s are a perfectly decent and extremely robust choice of spinner motor. It's just that your output RPM is a little on the low side compared to what most of us are used to. Using your ratio, I worked out that you're planning on running it at 12V, but you will get much more out the motor at 18V and more so at 24V. They can cope well with those voltages.
If running 12V is easier for you, I'd suggest buying bigger pulleys for your motors and having a ratio around the 1.5:1 mark. That gives you an output of approximately 4330rpm but factor in mechanical losses due to friction, plus the motor being under load and that figure will drop a little. Still, the motors would easily reach that speed within a second or two.
Alternatively, build it with your 2.667:1 ratio and try out some test hits on something that weighs close to 13.6kg. It might throw robots more than inflicting localised damage, but you'll be able to see what the weapon can do and then decide from there if you want to increase the ratio for more speed.
With the current battery set up they would run at 14.4V but I am looking into a 6 Cell Lipol to give me near 24, but I need to drop the voltage for the drive motors and finding a voltage regulator that does that particular conversion is proving extremely difficult!
And throwing robots is not exactly a bad thing :-), It looks great and I would rather knock someone out by putting them out of the arena or turning them over than having to resort to trashing their robot to beat them any day!
As long as your speedos can handle the extra voltage going through them, all you have to do is limit the travel of the transmitter channel to say 50% on each channel for the drive. This then in essance means that the drive motors only ever see 50% of the voltage from the batteries (there's a little more to it than that but that's the basics)
^ what Gary said. You will be able to ensure the drive isn't overloaded on the software side (easily if you've got a transmitter like the DX6 with option menus on-screen) rather than needing a physical regulator. Only hitch is the speed controllers will work a little less efficiently but that should be OK if they're large enough to dissipate some extra heat.
Quote:
Originally Posted by mr_turbulence
And getting good tooth engagment at that speed is very very easy....
According to me is 2000 rpm perfectly serviceable for a 350mm disk.
http://i157.photobucket.com/albums/t...ay11/o_rly.jpg
8000rpm engages fine with single tooth :) ... 2 teeth engage fine at 5000rpm... just talking from experience.
Been a while but now I have all the parts attached is the wiring diagram I think works... can anyone confirm?
[attachment=0:245taqkd]Weapon Relay Wiring Version 1 Diagram 1.pdf[/attachment:245taqkd]
Both systems work by controlling the negative. Part one... the power goes into the 100A relay's low Amp side then into the battle switch for control. When activated the battle witch lets the input from the 100A relay go to negative...
Now the other system kicks in... the 22.2v goes straight into both speed 900's then into the positive of the 100A relays high Amp side. When fired by the battle switch the 100A relay allows the speed 900's output to go to negative...
I hope I have explained that right... :?