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Vyrt - Team Chuck - England


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mark_m



Joined: 23 Apr 2005
Posts: 23
Location: Cambridge, uk


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Vyrt - Team Chuck - England

Robot name: Vryt

Builder/driver: Mark Mellors

Location: Hitchin, Uk (hope you guys don't mind me using your forum)

Weight Class: Feather 13.6 kg

Drive: 4 x 9.6V Drill Motors on 12V & 95mm Scooter wheels

Chassis: 10mm Polycarbonate/4mm glassfibre

Armour: 1mm stainless stell over 10mm polycarbonate

Weapon: lifter/hammer driven by a 7.2V makita drill/driver running on 12V through a fusee pulley

Batteries: 12V 3000mAh Nicad botpack

Controller: Electronize 30A external relays

Tx, Rx: FF6

Website: http://www.hyperdynamic.co.uk/newrobot.htm

Current CAD:


Current build state:

Post Tue Jan 15, 2008 11:59 pm 
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Jason Team Grimlock



Joined: 06 Jan 2007
Posts: 95
Location: Sydney-nsw-bondi


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Welcome to the madness!

Hi Mark!-Hitchins fine,welcome aboard!

Im gathering you are based in England(?), but its always
good to hear from roboteers OS!

Is that polycarbonate. if so thats a lot work youve done there,wed
love to see some more pics(maybe a vid?) of Vyrt in action!

If you ever get over here, come out to a meet, OK?-Good luck,
Jas.
Team Grimlock

Post Wed Jan 16, 2008 7:35 pm 
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mark_m



Joined: 23 Apr 2005
Posts: 23
Location: Cambridge, uk


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Thanks

yeah, I'm based in England. I like Oz bots more than the uk and US ones and at least you can post pictures on your forum. I've been trying to keep the website updated but it seems to take much longer than just posting to a forum.

The bulkheads and motor mounts are all cut from polycarbonate which meant lots of filing to start with until I realised I could use a roughing bit in a dremel to do the finishing. I still need to do some of the routing to radius the edges.

No videos yet as none of the electrics are done. I shouldn't be far off moving but I'm delayed a bit because my cad was wrong - the wheel holes are in the wrong place. I'm not sure whether to recut the wheels holes bigger, or make new wheel inserts and keep the bot the same size.

Post Wed Jan 16, 2008 10:56 pm 
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cerberus3112



Joined: 05 Dec 2005
Posts: 497
Location: Mt Druitt,Sydney,NSW


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NIce it looks awesome
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A journey of a million miles begins with a single step followed by a hell of a lot of other steps so get walking

Post Thu Jan 17, 2008 4:41 pm 
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seanet1310



Joined: 08 Nov 2006
Posts: 1265
Location: Adelaide


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looks very nice. i love all the polycarb

Post Thu Jan 17, 2008 5:44 pm 
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Glen
Experienced Roboteer


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


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looks like itll fit if you flip the base plate over Razz

but just enlarging the wheel slots would be the go. worse case weld some plate over the excess space.
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http://www.youtube.com/user/HyzerGlen - Videoooozzz

Post Thu Jan 17, 2008 5:46 pm 
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mark_m



Joined: 23 Apr 2005
Posts: 23
Location: Cambridge, uk


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wiring diagram

Glen: welding some plate over the holes might be a bit difficult: its a fibreglass base! I think I will cut the holes bigger and once everything's running I'll cut another base and keep this one as a spare. I've managed to get hold of some scrap carbon fibre (about 4mm thick) so I'll use that next time.

Does this wiring diagram cover everything I need in the robot?
You should be able to guess what most of the shapes represent but circles represent connections. Mixing will be done in the radio (PCM so no fail-safes either) but I'm a bit worried I've forgotten something.



Does anybody run with fuses? If you do, what holders do you use? What do you use for distribution blocks? I've just soldered wires together before or put two wires into one crimp connector. My wires are too fat to fit two wires into one connector this time and I wanted to make it quicker to change parts out without soldering so was looking for something with screw terminals or similar. I've got an idea I'm going to try but was wondering what everyone else uses.
cheers

Mark

Post Mon Jan 21, 2008 8:56 pm 
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Daniel
Experienced Roboteer


Joined: 30 Aug 2005
Posts: 2729
Location: Gold Coast


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A fuse? Isn't that when the solder melts off the connections?
Nobody uses fuses.

Post Mon Jan 21, 2008 10:24 pm 
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mark_m



Joined: 23 Apr 2005
Posts: 23
Location: Cambridge, uk


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Progress!

Woo hoo! It rolls!
Just had the best lunch break ever, 20 minutes of driving practice.



Here's a link to a video from last nights test drive:
http:///www.hyperdynamic/images/robots/VyrtTest1.avi
Sorry, it's ~25Mb I need to find out how to compress it.

I'm getting about ten minutes of driving off a single pack, which I'm really happy with. At the moment I'm using a resetable circuit breaker (30amp) to protect the whole system. It's not tripped yet so I might lower that and see what happens.

I think the relays are sticking on one side, sometimes I only have reverse on one side, other times I only have forward. If I stop and fiddle with the wires, it swaps Neutral

I've also noticed some of my screws are coming loose. They're M4x16 going into edge tapped 10mm polycarbonate. I'm going to get some M4x 25 but I want to thread lock them somehow. I know loctite messes with poly so what can I use?

Tyres are wearing down worryingly quickly, hopefully they won't wear down as fast on plywood arenas, I've got some MDF at home I'm going to have start using for testing. In the vid you can see I'm practicing in a carpark and the tarmac's really rough.

Next ups the weapon and some armour.

Post Mon Jan 28, 2008 11:35 pm 
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mark_m



Joined: 23 Apr 2005
Posts: 23
Location: Cambridge, uk


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wrong link

sorry mistyped the video url:
http://www.hyperdynamic.co.uk/images/robots/vyrttest1.avi
still 25Mb

Post Mon Jan 28, 2008 11:38 pm 
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Woody



Joined: 07 Oct 2004
Posts: 202
Location: UK


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Have you added quench diodes across you're relay contacts to help prevent them arcing and sticking together? ... have you picked the correct relay rating based on the inductive value rather than the resistive?

Here's some info on relay contacts ..plus there is a selection of quenching methods mentioned :-

http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3236.pdf


This is odd ...We only live about 30 miles apart in the U.K. and chat via Australia!!!

Post Tue Jan 29, 2008 12:49 am 
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mark_m



Joined: 23 Apr 2005
Posts: 23
Location: Cambridge, uk


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relay arching

The relays are wired as per the technobotys datasheet:
http://www.technobots.co.uk/Data%20Sheets/1500-021.pdf
The relays are the 30amp ones that came with the electronizes.

No resistors, no capacitors, no diodes. the entire wiring diagram is in my post earlier in the thread) I've followed some threads on quenching arcs, but I thought that since my stall current should be less than the relays continuous rating, I should be ok. I suppose the current during reversals could be higher, I'm not sure. I had major relay problems on my last but but that was 9.6V drills on 24V in a 5kg robot.
Can you determine motor inductance using a scope? I've got quite a few different diodes and most resistors on hand but I've only got a few electrolytic caps so I guess I'm going to have to buy some none polarised ones. Can anyone suggest a good starting point as I've not sized anything like this before.
The datasheet suggests a 1uFarad cap for 28V, 5Amp but that doesn't seem to be based on either the inductance or the current, which seems a bit odd.

I've just realised I've got no caps on my motors either, could you suggest a suitable size for those too?

Thanks for the help

Mark

Post Tue Jan 29, 2008 3:27 am 
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mark_m



Joined: 23 Apr 2005
Posts: 23
Location: Cambridge, uk


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diode positions

Given that the relays don't have internal diodes, I guess that adding diodes like this will help:



Or have I got the wrong idea? Most H-bridge diagrams I've seen have flywheel diodes arranged like that.

I've managed to reduce the size of the video, it's now <5Mb:
http://www.hyperdynamic.co.uk/images/robots/VyrtTest1sm.divx

Post Tue Jan 29, 2008 7:40 am 
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Woody



Joined: 07 Oct 2004
Posts: 202
Location: UK


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The addition of a 10n snubbing capacitor across the motors should be fine and the capacitor should also be capable of handling a voltage of twice the drive voltage to the motor.

The flywheel diodes arrangement looks fine.

Post Tue Jan 29, 2008 9:29 pm 
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