Team MedBots

[Max]

Re: Team MedBots

Tested the pneumatic system again- it went badly!
I had the system piped up and turned on the co2 from a paintball bottle, I had the nut on the regulator fully undone then I screwed it up, it was at 2 bar and I tried firing the ram but it didn't have enough power. So I turned the regulator nut a little bit more then the prv (10 bar) fired and all the co2 came out. On my pressure gauge it went further than it measures. The pvr was covered in frost and the bottle froze to the ground. There was a lot of pressure when the pvr went off.

Is my Trevor regulator Brocken?

[Max]

Re: Team MedBots

What kind of forces so fw hydraulic crushers like cobalt have at the tip? And what about electric crushers rather than just grabbers?
I'm after the force at the tip rather than the pressure
Thanks!

[psycho_fling]

Re: Team MedBots

in theory my crushers actuator produces 10000N pushing (electric) and with losses calculated it would be 7000N on the tip which equates to roughly 700kg on the tip

I think Kenny said that cobalts tip force was 2000kg, naturally hydraulics are going to produces far bigger numbers than electric but the downside is, the expensive parts needed etc

[Max]

Re: Team MedBots

Bit more progress on flipper;
And got Some pneumatics done:

[Max]

Re: Team MedBots

Hi all,
Looking but the event at Guildford I don't think my flipper was very effective, it more turned people over rather than throwing them up, does anyone who saw it know what might be wrong?

[psycho_fling]

Re: Team MedBots

the angle of the flipper arm looked quite high i would say reducing this will help so it makes robots run up it giving a better flip

[Anttazz]

Re: Team MedBots

What sort of size is the ram?

[Max]

Re: Team MedBots

I think it is a 63mm bore and 125mm stroke but it doesn't use all the stroke.
I had a horizontal plate at the bottom of the flipper to get under people but I see what you mean about the slope. But even when I put a brick right up on the flipper arm it didn't go very far.

[Anttazz]

Re: Team MedBots

Quite a bit bigger than Jr then.

I just watched the video of it and it didn't look too bad, its not going to get the same sort of force as a FP flipper is but if its getting people over at least then thats a good sign. I noticed Jr had trouble flipping robots unless it was just under them and they were near to the ground. I think theres a video of my trying to right Jamie's MDF bot at Edinburgh and because of the unusual shape it was when it was upside down it couldn't get at it properly.

So maybe its just the limitation of the system? If not, test the setting on the reg as at the highest for your system and similarly for the PRV.

[Max]

Re: Team MedBots

I'd just like to point out that I only had one drive motor working in that video and that's why the driving is terrible.

[jonny]

Re: Team MedBots

could be a flowrate issue

[Max]

Re: Team MedBots

I think the regulator was set a bit low so I'll get a pressure gauge and test.
Could you make a crude speed controller by having a circuit with a variable resister, a capacititor then one side of a relay and a small battery (3v) then to the other side of the relay attach the motor. Then use a servo to control the variable resistor and have a simular setup for reverse?
I know it wouldn't be the best but would it work?

[razerdave]

Re: Team MedBots

You could do. That is how some of the really old RC cars used to work, and also how th 4WD's worked before they made an interface for it (Look up Hypno-disc's build diaries)

[Max]

Re: Team MedBots

Right I am thinking of rebuilding my flipper with a fatter shorter ram.
I am thinking of a 100mm bore 80mm stoke running at 10bar.
To keep it as compact as possible I want to make it my self by using a piece of aluminium tube then having a piece of 20mm hdpe as end caps. I plan on drilling holes in the corners of the hdpe and using threaded bar to hold the end caps together with the tube in between.
Then make a aluminium plunger and then weld a peice of aluminium rod to the plunger.
Would this work? What thicknesses would I need? How would I get a good seal between the pipe and the end caps and between the plunger and tube?
Thanks,
Max

[psycho_fling]

Re: Team MedBots

first off i have no experience in this area but i would have a feeling that precision is very critical both for safty and to make the ram actually work. the best and easiest way to do so is using computer controlled machines with CAD models

like I say i might be wrong ....... dont let this stump your ambitions though