New Anticide

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Andrew_Hibberd
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New Anticide

Post by Andrew_Hibberd » Sun Jan 03, 2010 4:55 pm

I have been looking at a new version of anticide. I am going to use this thread as a blog with part updates/design changes. I hope that this will be a useful guide for anyone else wanting to build a pneumatic robot. Pneumatics are very hard work and i wouldn't recommend them to a beginner, however the results can be very fun.

The parts inside anticide are quite old now, i bought them way back for aws17.
Image

The current version parts and weights are as follows.
Image

Drive Motors
2 HP pololu motors (originally 50:1 not sure now i think one is 30:1)
20 g
http://www.pololu.com/catalog/product/998

Controller board
Barello ant 150 (Very heavy control board outdated now but has 3rd analogue output to control solenoid valve. This could be done easily with a simple rc switch)
14g
http://www.barello.net/ANT/150manual.pdf

Battery
3 cell 130mah battery from atomic workshop (Not the cheapest cells but nice C output)
11g
http://www.atomicworkshop.co.uk/catalog ... 6d74d99e1b

Air Tank
2 Gold Spot Breath Freshners (They were emptied, tops removed and joined end to end with a aluminium tube. A hole was drilled in the middle and a 2mm brass tube inserted as an input)
14g
Avaliable from lots of places, i got mine from ebay

Pneumatic Ram
1" stroke ram (Bought as a kit from when robotcombat sold pneumatics, made by robart)
20g
Avaliable in the uk http://technobots.co.uk/acatalog/Online ... s_144.html

Fill Valve
A one way valve used to pump up the pneumatics. Also bought from robotcombat, not sure about suppliers now other than robart.
4g
http://robart.com/air_systems/access.aspx

Solenoid Valve
A 3/2 valve called Hi-flow by inertia-labs. I have been looking for an alternative supplier however i haven't found one so the new one will use a different valve.
18g
This is a data sheet of something very similar
http://www.ascovalve.com/Common/PDFFile ... 407CR4.pdf

Tubing
Same as the one sold by technobots. About 3cm used in total
1g

Switch
Maplin slide switch
1g
http://maplin.co.uk/Module.aspx?ModuleNo=2476

Reciever
Spektrum AR6300
3g
lots of shops sell this. http://www.spektrumrc.com/Products/Defa ... =SPMAR6300

Wheels
Covered with lint roller
6g

Chassis
3D printed from shapeways.com
24g

Armor
Folded and bolted together 1mm polycarb
15g

Total 152g

=======================================================


So how to improve these parts and the impacts on the robot.

More powerful ram
More pressure: Not allowed due to pressure rule
Larger bore: more space in robot, uses more gas. Weight?

Faster actuation
More pressure: Not allowed
More flow: larger bore pipes, higher flow 3/2 valve as that is the limit point of flow

More flips
Larger storage: More volume in robot, weight?
Shorter Stroke ram/Less pipes: weight saving? Effectiveness of flip/self righting

Lighter parts
Lipo: could be 2 cell
Control board: could be replace with a smaller drive board
ram/valve: are the 2 heaviest parts of the robot and could be reduced

Armour
I have taken a lot of damage from spinners in the past - Weight!

Flip
Anticide does tend to flip robots up or backwards rather than forwards. I would like to try and improve the forwardness part of the flip but not sure how to achieve this yet.

=======================================================

Alternative parts:

Lego

After Snibston Scott and I did some tests with lego pneumatics. The lego pipes blow off at ~40psi which is lower than the allowed 100psi. Using higher pressure tubing with the same diameter (4mm outer 2.5mm inner) the pressure can be increased. Both the large bore ram and small bore ram can hold 100psi without leaking. The lego mechanical valve leaked at above 60psi. We also tried making a compressor using the small lego pump however this couldn't pump over 40psi.

The lego pneumatics have pin hole sizes limiters at the ports which can be drilled out up to 2mm. However for the valve this requires disassembly which can be difficult to reassemble correctly.

From these tests with the drilled out ram and re-lubricated at 100psi when activated the top flew off due to the speed and pressure increase. Therefore the top may need to be epoxied on, although the lifetime maybe reduced.

The lego ram seems like a good option at this point, a slightly larger bore ram with higher flow than the current version. However the lego valve can't handle the pressure so an alternative needs to be found.

fischertechnik pneumatics

I haven't had much time to play arround with these, however they seem to run on ~15psi. They are very low friction rams and have very neat valves. However the force and speed looks very low.

Valve

Finding a valve to replace the current solenoid valve has proven very difficult. Valves designed to run on higher pressures have less flow. And most solenoid valves are large and heavy. The only alternative i have found which looks reasonable is this one from RS http://uk.rs-online.com/web/search/sear ... &R=2898736. This takes the 4mm tubing similar tot he lego valve and has ~3 times the flow of the current valve. It is mechanical so requires a servo to activate it which requires a little more designing.

=======================================================

So this is where i am up to now:

Lego ram 11g (9g saving)
RS valve with small servo 10g (8g saving)
baby-orangutan control board 4g (10g saving)
possibly 2 cell lipo (4g saving)
redesigned tank (1-2g saving)

I would like to reduce the size of the fill valve as well but haven't found a nice alternative.

=======================================================

So feel free to add pneumatic parts to this thread for anyone who would like to build a pneumatic flipper.
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teamocean
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Post by teamocean » Sun Jan 03, 2010 7:27 pm

I was looking for a solenoid valve for an ant and came across this site

http://www.pneu-store.co.uk/cgi-bin/sh0 ... 267#a10267

I got in touch with them and they recommended this valve S070C-VDG-32 (Its just down the page)

According to the guy I spoke to it will handle 100psi with a reasonable flow rate at 6v

If anybody wants the datasheet I'll try and find the one they sent me
Will Thomas
Team Shock
www.shockbots.co.uk

Andrew_Hibberd
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Post by Andrew_Hibberd » Sun Jan 03, 2010 8:21 pm

A datasheet would be good if you have one
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EpicentrE
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Post by EpicentrE » Sun Jan 03, 2010 9:29 pm

Here is the datasheet for those valves. Maximum operating pressure is 72psi, which has a CV factor of 0.011, but I've got no idea how to calculate flow from that.
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk

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Post by Andrew_Hibberd » Sun Jan 24, 2010 9:50 pm

I haven't progressed much with the new anticide, bought some 2mm HDPE for armour and new motors and controller on the way.

I have also started a side project to see if it is possible. A full pressure antweight!

Marco has lent his mill/lathe to scott and myself while he looks for somewhere to store it in his new place in london, so i am learning to become better at turning at milling. Looking at the parts list this is going to be very heavy so getting it in the weight limit will be the challenge. The ram size will be 10mm bore and 11mm stroke with a front hinge flipper.

So here is the cad of the co2 system and the first part from today.

http://i23.photobucket.com/albums/b352/ ... 1264369592

http://i23.photobucket.com/albums/b352/ ... 1264369605
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Post by Andrew_Hibberd » Sun Mar 14, 2010 9:36 pm

The new anticide is going to be designed when i am away for the next few months but most of the parts have been bought. Once i have the parts in the correct arrangement and the shape right i should have it ready for august time.

I have made some progress on the full pressure antweight its looking like it could work now. I need to buy some longer m3 bolts to hold it together so for the pictures its just using nylon ones. The valve manifold was a pain to get right, lots of turning followed by milling the central part. This needs a couple of weight savings made and the input and exhaust ports put into it. The valve part with the 5 o rings has been this weekends project the first one sheared as I put the thread on. The 2nd one was much quicker to make and slides really easily in the manifold with no grease.

http://i23.photobucket.com/albums/b352/ ... 1268601881

http://i23.photobucket.com/albums/b352/ ... 1268601855
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Post by Philip » Fri Apr 30, 2010 9:24 pm

What do you need to do to use the baby-orangutan control board as a speedo in an ant?

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Post by Andrew_Hibberd » Thu Sep 02, 2010 7:51 pm

I don't think i saw the previous post, to use a baby-o you need a usb cable from pololu. You can then use the 3pi RC code directly from the web site and solder the wires to the board. Its a little more work than an off the shelf unit but you know what your board is doing.

Back to anticide, i have been playing arround with lego pneumatics. Following this guide:

http://www.techbricks.nl/My-pneumatic-L ... witch.html

you can rebuild the once great Rebel. The modding of the valve is really tricky and i do not recommend it. I then attached a piece of ali to the front and back of the valve so it could be used to 100psi. I would recommend buying the RS valve and using a small servo as it seems to produce better flips.

The lego finger pumps can generate about 38psi before their internal valve leaks. The lego pipes pop off at arround 40psi.

A video of my testing in the garden can be seen flipping a 5g kinder suprise capsule. The new anticide will have a shorter stroke to avoid the flipping the opponant over the back of the robot and more up. The pipes in the video are rated at 16bar so do not pop off.

http://www.youtube.com/watch?v=NLwDlqSKWnA
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Team Orr
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Post by Team Orr » Fri Sep 03, 2010 12:29 pm

looks awesome :)
"if it wasn't for Edison we'd be watching TV by candlelight"
Jack Orr
Team Orr Robotics

Panzerbot
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Post by Panzerbot » Sat Sep 04, 2010 2:28 pm

Lol it?s very hard.
I have maked this too at my Lego pneumatik.
I have tested it with 1,5 bar and my ant Black Carbon flews over 10 cm far :o

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Jonny
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Post by Jonny » Mon Sep 06, 2010 6:59 pm

any chance you could send me a link to the tubing you used and a video on how you modified your lego with aluminium?
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Post by Jonny » Mon Sep 06, 2010 7:42 pm

http://cgi.ebay.co.uk/4mm-OD-x-2-5mm-ID ... 439e3ddd11

found this on ebay, its rated to 250 psi.
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Post by Andrew_Hibberd » Mon Sep 06, 2010 9:36 pm

The description has a link how to modify the valve for extra flow. I just cut out two bits of ali wider than the valve, put a 2mm hole in each corner. Then 3 6mm holes in the front for where the pipes go in. I was intending to put m2 bolts through each corner to hold it together but the ones i had were about 1mm too short.

Again i must stress the mod to the valve is really difficult and even with this change and a ton of silicone lubricant the RS valve is the better valve.

The piping looks good, just remember it won't be as flexable as the lego pipe.
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Jonny
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Post by Jonny » Tue Sep 07, 2010 7:17 am

thanks :D i'll have a go with the lego switch before i think about getting the rs valve. by the way what are you using to pump it up?
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Post by Andrew_Hibberd » Tue Sep 07, 2010 4:19 pm

I used to use a bike pump, however i am lazy and now use a large 12V power supply and a car tyre inflator. I haven't tried this but you can modify an old inner tube valve to take a 4mm OD 2.5mm ID tube. I have been using a robart one valve #168. However i have just found this but you will need to check the pressure rating:

http://hobbycity.com/hobbycity/store/uh ... oduct=8369
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