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Stobs
12-08-2010, 04:08 PM
I'm currently in the planning and parts procurement stages of my project "mech," but I'm announcing my robotic project for an entry in the the RG'11 Mech Warrior event, as follows:

Name: Armo Gettin
Type: Caterpillar-based vehicle
Class: Open League

Configuration:
Armament.Primary(Functionality.Active): Airsoft 6mm BB Gun(s) (see "Locomotion.OTS.Modified")
Armament.Secondary(Functionality.Selectable): Unannounced (Type/Mfg. TBD)
Armament.Tertiary(Functionality.Cosmetic): Laser(s) - Low Power (Type/Mfg. TBD)
Armament.Munitions: TBD
Armament.Munitions.Storage: Custom
Battery: TBD
Camera(s)/Controller: TBD
Controller.Brain: Fit-PC2 (http://www.fit-pc.com/web/), re-imaged w/Ubuntu (tentative)
Controller.Spine: ArbotiX (http://www.trossenrobotics.com/p/arbotix-robot-controller-starter-kit.aspx) (single controller if ~.Brain is not implemented)
Communications: XBee/XBee Pro
Locomotion.OTS.Modified: Super Panzer Airsoft (1/30 scale) (http://www.bananahobby.com/1924.html)
Sensors.(P)IR: TBD
Sensors.Ranging: TBD
Sensors.Color/Object Tracking (Software-based): TBD
Targeting.Plates: Trossen Robotics

That covers the basics for now. Once I actually start the build process, and have a dedicated website for it started, then I'll post under the Mech-Warfare roll call thread.

Regards,
Paul

jes1510
12-08-2010, 04:46 PM
I assume you noticed the "shooting range" on that tank is only 5 feet right? You may want to go with a better gun.

Stobs
12-08-2010, 05:20 PM
I was thinking of a 30-aught-6.... ;) Seriously though, I had decided to go with one or a pair of Defenders (http://cgi.ebay.com/Airsoft-Defender-World-Peace-Mini-Machine-Gun-aeg-Cl-/380289938289?pt=LH_DefaultDomain_0&hash=item588b0bf371), just didn't elaborate. Thanks for the heads-up anyway, much appreciated! :)

Regards,
Paul

PS: Previously I'd seen a three-pack of mechanisms for $27.xx, but I don't see that listed on ebay anymore - hopefully I'll be able to track down that or similar deal when I'm ready to, uh, pull the trigger on them. ^.^

Stobs
12-08-2010, 09:07 PM
Ok, I realize that needs a little more clarification, since I obviously referenced the tank airsoft guns from the Armament section.

When the entry of tracked vehicles was first bandied about (of which I was a strong proponent) and then the Open League was established, I was considering a 1/16th scale tank with metal gears and treads, like this Tiger (http://cgi.ebay.com/1-16-GERMAN-TIGER-RC-AIRSOFT-TANK-SUPER-METAL-VERSION-/250736491678?pt=Radio_Control_Vehicles&hash=item3a610f3c9e).

Somewhere along the line I started entertaining the thoughts of a legged mech and then a quad, since I did(do) really want to start working with servos right off, and that's about when the Defenders came in.

After giving it a bit of (too much) thought, I decided that it would be pretty lame of me to put in my 2-cents worth, in support of a beginner's entry point that would allow tracked vehicles into Mech Warfare (others proposed wheeled as well), and then not enter it as a beginner myself, so I'm back to the caterpillar-based mech.

I've subsequently decided to go with a different tank design all together, and as such I'd be looking at the task of reducing the number of bogeys and idlers for the caterpillars as well as the treads legnths - an unknown task to me. Well, just about everything invovled with Mech Warfare is an unknown task to me at this point...

While I was looking for current availability and pricing for tanks I stumbled upon the 1/30th scale tank referenced above, and immediately realized I'd likely not need to do any caterpillar alterations with it, and felt that the five foot range wouldn't be an issue since my strategy would've been to get in close anyway. Ok, I can't blame you for "letting the secret out," since I posted the tank's info linkage myself... :o

Ok, now that I got that off my chest I can get ready for my drive down to Tucson tomorrow for a five day trip! If I can't post from down there (my laptop's out of commission for now) I'll post an update late next week, presuming I make any headway on Armo Gettin.

Regards,
Paul

Stobs
12-15-2010, 10:09 PM
Just made my first ever eBay purchase O.o ...bought a three pack of Airsoft Defenders for $27.00 + $9.99 shipping & handling Somehow that totalled up to $39.62; I'll have to track down what I got charged the other $2.63 for, but at this point I'm just happy to finally get the ball rolling on a mech.

[Edit: PS: The $2.63 was for CA sales tax.]

Stobs
12-16-2010, 02:45 PM
Can the ArbotiX Starter Kit be "upgraded" to include the XBee Pro instead of the standard XBee?

I used the TR store page search to try and locate the scoring plates and transponder, but was unable to - anyone have a link to offer?

Thanks,
Paul

lnxfergy
12-16-2010, 03:25 PM
Can the ArbotiX Starter Kit be "upgraded" to include the XBee Pro instead of the standard XBee?

I used the TR store page search to try and locate the scoring plates and transponder, but was unable to - anyone have a link to offer?

Thanks,
Paul

Just a note, the pro doesn't fit that nicely it hits the 3.3V regulator -- of course, it'll also require you to upgrade the 3.3V regulator to a higher current version.

-Fergs

elaughlin
12-16-2010, 04:50 PM
The scoring plates and transponder are purchased directly from Fergs or Tybs. I'd PM them with your invoice for a set, and wait til they make up a batch to send out is all. I got mine from a participant who never made it to Robogames last year, and bought it that way. So you could look for any other re-sellers. Otherwise, its not really a product, its just a MechWarfare piece that the creators sell to make sure everyone has uniform gear to use for scoring.

lnxfergy
12-16-2010, 05:27 PM
Whoops -- I missed the second question in there. As Erik pointed out, we don't sell the transponder kits year-round. Note the "Roll Call" thread: http://forums.trossenrobotics.com/showthread.php?t=4368 asks you to post about transponder/target board needs.

We'll have a more official "order here" thread shortly (the hold up is deciding on pricing of the new mini transponder boards -- which are purely awesome (not much bigger than an XBEE), but still under development, I should know pricing in a week or two).

-Fergs

P.S. -- I don't want anyone to fret, older style transponders are still allowed, and you can still purchase a MINI to repurpose as a transponder. I just had so many requests for a smaller transponder, we had to go and do it!

Stobs
12-16-2010, 06:49 PM
Thanks for your replies elaughlin & lnxfergy, very much appreciated :)

I'll hold off on getting the plates and transponder until the "mini" pricing is set & posted. Sorry about the oversight on the rollcall thread Fergs, simply missed that one.

Regards,
Paul

gdubb2
12-17-2010, 01:34 PM
Hey Stobs,

One thing about the Pro Xbee. They do use a bunch more power than the standard version. They are fine for the Laptop end of things, but are a major drain on the Mech end. I tried it, and went back to the Standard Xbee for the Mech. For the ranges we are dealing with, the Pro is overkill anyway.

Gary

lnxfergy
12-17-2010, 02:00 PM
Hey Stobs,

One thing about the Pro Xbee. They do use a bunch more power than the standard version. They are fine for the Laptop end of things, but are a major drain on the Mech end. I tried it, and went back to the Standard Xbee for the Mech. For the ranges we are dealing with, the Pro is overkill anyway.

Gary

I think that Gary really is onto something -- if you want to use Pro models put them on the laptop end -- data going from controller->mech is way more important than mech->controller (and battery consumption for mechs should be kept low as possible)

-Fergs

RobotAtlas
12-17-2010, 02:25 PM
I read in XBee PRO spec that power output is limited well below maximum allowed in US and Japan.
So it surprises me that PRO consumes that much more power.

I thought the problem was that ArbotiX regulator does not support draw required by XBee Pro. At least that's what's written in ArbotiX manual.

To me the biggest attraction of XBee Pro is it can be used with a much better antenna.
You would want bigger antenna on both sides.
I wonder if the same antenna could be used for XBee if its default antenna was unsoldered.

lnxfergy
12-17-2010, 02:53 PM
I read in XBee PRO spec that power output is limited well below maximum allowed in US and Japan.
So it surprises me that PRO consumes that much more power.

I thought the problem was that ArbotiX regulator does not support draw required by XBee Pro. At least that's what's written in ArbotiX manual.

To me the biggest attraction of XBee Pro is it can be used with a much better antenna.
You would want bigger antenna on both sides.
I wonder if the same antenna could be used for XBee if its default antenna was unsoldered.

The current consumption is ~250-300mA vs 50mA -- a huge difference on a mobile bot. The 3.3V reg on the arbotix is rated for only 100mA.

You can buy XBEE modules (even the non-pro versions) with other types of antennas beside the standard whip antenna (such as a U.FL connector as seen on my XR-B3 robot).

-Fergs

gdubb2
12-17-2010, 04:07 PM
I use a standard Xbee with the built in whip antenna on the target transponder, but for control, I use a standard Xbee with a ufl connector and an antenna from my old crappy Airlink camera. At the laptop, I use a Pro at half power with a chip antenna.. It all works fine on Bheka.

The bigger antenna's do give a bit of Dba gain.

Gary

Stobs
12-17-2010, 07:10 PM
Thanks guys for the replies, all very much appreciated! Looks like I'll go with the XBee Pro on the laptop side, at least.

The extra draw on the bot side may not be that much of an issue for me, since I'm going with a caterpillar-based mech. That is to say, that since I'm in the parts acquisition stage of the process I'll be keeping an eye on the overall weight and may bypass the "mini" tank I linked above and go for metal gears; won't have a good grasp on that until towards the end so the locomotive parts will be pretty much the last "build" parts to be ordered. I really don't have to be particularly concerned about balance and CoG issues with Armo Gettin, and if I do wind up going with the metal gears then opting for a larger (heavier) battery at the end shouldn't be a problem...I'm guessing.

BTW, I was very pleasantly surprised to find that my three Defender guns had already arrived today - omgosh those beasts are BIG for a mech! O.o

I'm glad I got the three pack, as this way I won't hesitate to hack the first one apart (carefully, even so), since I'll have the two others to fall back on. I would love to be able to have the two guns mounted so that they can track independently, but getting the software programmed to keep the barrells from interferring with each other will more than likely have to wait until next year. Independent functionality, for tracking multiple targets simultaneously, is a pretty low priority for RG'11 - as I get closer to a functioning mech I'll commit to a single or double gun mounting [regardless of software implementation].

[Regards,
Paul]

Stobs
12-17-2010, 07:30 PM
Can the ArbotiX control small DC motors directly? I don't have spec's but this is the metal gear train I'm considering - it has a two-motor transmission (http://cgi.ebay.com/Metal-Gear-Heng-Long-Tiger-Panzer-Stug-1-16-RC-Tank-/290503995579?pt=UK_ToysGames_RadioControlled_JN&hash=item43a36330bb), which would allow the mech to spin around it's z-axis (presumably "yaw" wouldn't be applicable?).

If so, then I'm thinking I really wouldn't need to buy the radio controlled kit(s), since they'd be controlled through the ArbotiX and communications relayed through the XBee's.

Regards,
Paul

lnxfergy
12-21-2010, 04:23 PM
Can the ArbotiX control small DC motors directly? I don't have spec's but this is the metal gear train I'm considering - it has a two-motor transmission (http://cgi.ebay.com/Metal-Gear-Heng-Long-Tiger-Panzer-Stug-1-16-RC-Tank-/290503995579?pt=UK_ToysGames_RadioControlled_JN&hash=item43a36330bb), which would allow the mech to spin around it's z-axis (presumably "yaw" wouldn't be applicable?).

If so, then I'm thinking I really wouldn't need to buy the radio controlled kit(s), since they'd be controlled through the ArbotiX and communications relayed through the XBee's.

Regards,
Paul

The arbotix has two 1-Amp motor drivers integrated onboard. They may or may not be able to control that motor (I tend to think not).

However, just about any external motor driver can be controlled by the ArbotiX with a bit of custom code. For instance, robocontrollerlib contains a beta version of a library for the $50 Pololu Dual 30A H-Bridge called BigMotors. Many motor h-bridge kits exist that can work with standard hobby servo signals (which the ArbotiX can generate, either using hardware timers alone (up to 2) or using the new servo library (up to 12, but don't let the processor usage go to 100%)), such as the Sabertooth models.

-Fergs

Stobs
12-23-2010, 05:39 PM
Thanks Fergs, good to know that I'll be able to use the ArbotiX then, one way or another. Your support is sincerely appreciated.

Paul

Stobs
12-23-2010, 06:50 PM
BTW, I "hacked" one of the defender guns I'd gotten off of ebay a couple of nights ago; took all of maybe five minutes to take out the screws and caps to get the two primary body pieces apart - and that was being somewhat methodical about it. Have to admit that a bunch of the mechanism pieces popped out since I didn't try to restrain any of the internal spring. I studied the inner workings for a bit - mostly to see how the bb's were being feed into the chamber (wound just being the slotted end of the gun barrel itself), and then put it back together and got it working again right off. Undoubtedly the simplest part of this endeavor! lol I've registered my website and while I'm waiting for it to become accessible I'll redo the hack and take some pics and then do a first installment on the site ASAP.

Stobs
01-03-2011, 10:02 PM
Just realized I haven't made public a bit of a change in plans for RG'11 - I'm postponing the "Armo Gettin" project for a downsized version, named "Li'l Gettin." A number of reasons for it, but the three main o...five main ones are:

1) Lack of experience, with a quickly approaching deadline; and
2) My laptop took a nosedive and I can't send it out for repairs until...
3) I'm going back up to the Monterey, CA area this weeked for two or three months; and
4) I've postponed order parts for that reason as well; and
5) Please see item 1), above! ;)

I'll just keep posting under this thread, as well as my own site now, since I'd rather not create yet another "new" project, but I will move the discussion to the rollcall thread (http://forums.trossenrobotics.com/showthread.php?t=4368) once Li'l Gettin meets that thread's requirements.

Paul

Stobs
05-04-2011, 04:16 PM
Just a note, the pro doesn't fit that nicely it hits the 3.3V regulator -- of course, it'll also require you to upgrade the 3.3V regulator to a higher current version.

-Fergs

I do want to go with the xBee Pro's, so how difficult is it to swap out the 3.3V regulator on the current arbotiX, and what should it be upgraded to? Information/links on performing the swap would, as always, be greatly appreciated.

elaughlin
05-04-2011, 05:04 PM
The pro really isn't needed on the Arbotix side of things. It works just fine with the regular Xbee there, and with a Pro on the computer side.

But I guess it's your choice. I asked the same thing, and was told it draws a lot more, and doesn't fit. Sorry I don't know about switching out the regulator for you though, just adding in my thoughts about it.

darkback2
05-04-2011, 08:14 PM
The xbee pro is a bad fit on the arbotix. it sticks out the back about a centimeter and would hit some components on the board making it sit wrong, and it draws too much power. ( I tried shoving one on anyway a while ago.) I run an xbee pro on the PC side and a standard xbee on the arbotix. Seams to work just fine.

DB

Stobs
05-04-2011, 10:45 PM
Thanks for the prompt replies elaughlin & DB, much appreciated.

I'm just too dang stubborn to relinquish the idea entirely but, taking your comments with knowing you two from this site here and meeting you DB twice briefly, I will mothball the idea indefinitely for future review. Who knows, but probably by the time I have enough experience/knowledge to address the issue on my own I'd guess that Mike'll have an xBee Pro compatible arbotix available! lol

lnxfergy
05-06-2011, 03:15 PM
I do want to go with the xBee Pro's, so how difficult is it to swap out the 3.3V regulator on the current arbotiX, and what should it be upgraded to? Information/links on performing the swap would, as always, be greatly appreciated.

I don't believe we have any tutorial or whatnot. What I can say (from a previous email) is:


The little regulator behind the XBEE is an LP2950 (100mA). You need ~250mA for an XBEE Pro, unfortunately, there really aren't any 3.3V >250mA regulators in that TO-92 size package. One possible chip is the LM1117, but that is TO-292 package, similar in size to the main regulator. The best course of action is to cut the existing TO-92 package regulator off the board, and then wire the LM1117 to the backside of the board, respecting VIN, 3.3 Out and Ground.

One additional consideration is that all current to the LM1117 will be coming from the LM2940 5V regulator -- that could easily double the load on the regulator, creating additional heat, so you might want to add a heatsink to the LM2940.


Who knows, but probably by the time I have enough experience/knowledge to address the issue on my own I'd guess that Mike'll have an xBee Pro compatible arbotix available! lol

We don't currently have any plans for adding the extra current capacity or space for an XBEE Pro. There isn't a lot of demand for them, especially when you consider how much additional current they suck. Generally, putting a regular XBEE on the bot and a PRO on your controller is sufficient.

-Fergs

Stobs
05-06-2011, 03:34 PM
Ok, thanks very much for the heads-up Fergs, appreciated!

muc
05-06-2011, 05:36 PM
I also agree a Pro is not needed on the Bot side. But if you still want to make it happen then maybe this part will work for you. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7246-1-ND (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7246-1-ND) It has an absolute max current of 300mA and is a TO-92 package. This will not work if you’re using the x-Bee Pro RPSMA (340mA in Tx mode). You will definitely need to watch current draw on the 5V reg and add a heat sink like Fergs said. I would add one anyway because it gets dang hot already.

The xBee Pro specs list a peak current of 250mA. Average current draw will be less because you will in receive mode most of the time. If you want to decrease the Tx peak current draw on the xBee Pro just decrease the Tx output power. This can be done with Digi’s X-CTU software or by sending an AT command to the module with your micro.

There is one good reason for going with a Pro that I can see. It has a receive sensitivity of -100dBm whereas the regular xBee has sensitivity of -92dBm. That’s a pretty good gain in sensitivity.

Stobs
05-06-2011, 08:46 PM
@muc: Thank you very much for your reply - the information you provided is greatly appreciated. :) I've gone ahead and bookmarked that regulator for future reference, as eventually I do want to use the xBee Pro on the remote side too.

At this this time, essentially being a noob with robotics, I think it's more prudent to leave components intended to work "as-is" as they were designed. I simply haven't gained enough experience yet - especially in regards to trouble shooting, to determine whether or not an issue I might encounter is due to my tinkering with a pre-packaged component or not. I'm sure the day that I'll confidently de-solder components and replace them with ones of my own choosing will eventually arrive, just not today! :)