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lnxfergy
06-22-2010, 05:10 PM
There has been a bit of discussion about ROS and Issy3 in my blog, and I figured I'd move it over here. Like his predecessors, Issy3 is a 3-DOF quadruped. Unlike the previous bots, he's carrying a FitPC for heavy processing, a stereo vision head for main sensor, ground tactile sensors on the feet, and has a tail in an effort to allow better dynamic balancing without as much body shift. My camera is currently out of town, and the build is only about 75% done, so a CAD rendering will have to do:
http://forums.trossenrobotics.com/gallery/files/1/7/6/8/issy3-final.png

and here are some pictures of the feet:
http://2.bp.blogspot.com/_qmthA_fNJ-Y/TBF7ToXYmYI/AAAAAAAAAJ0/v8hO0MXftcg/s320/img_1306.resized.jpg
His poor little AX-12s are going to be overwhelmed I fear, and I may have to upgrade to RX-24Fs in the legs at some point in the near future.

Now onto the more technical details. In addition to the FitPC2, Issy has an ArbotiX acting as the primary I/O device. The ArbotiX controls the 16 AX-12 servos, and reads inputs from the ground tactile sensors. Eventually it will read information from a 6DOF ArduIMU. Voltage monitoring is done by querying the individual AX-12s. I've dumped the XBEEs in this application and the ArbotiX is connected with an FTDI cable to the USB of the PC.

The ArbotiX is running a standard NUKE IK and gait engine, and a customized main loop that takes serial input from the ROS driver. The ROS driver currently sends high-level commands (x speed, y speed, rotation speed, etc), and can also poll/set the state of analog/digital lines. Since the ArbotiX handles all the real-time movement and keeps its own odometer, the PC is free to do high level planning and vision -- without worrying much about real time crap. All of the ROS code will be released shortly – it's taking a bit more time to get to a 0.1 release than I expected, as I had to rebuild a good portion of both of my test bots over the past week. I'm hoping we'll a full release + documentation out by the beginning of next week. The next version of NUKE, due out next month, will allow you to select whether you want the traditional “Commander-protocol” sketch exported with your IK engine, or the new “ROS-protocol” one.

When I eventually get Issy's feet sensors into the equation for terrain adaption, the ArbotiX will also handle those internally (although the PC can query the state of the foot sensors). Having a fast, closed-loop control out on the ArbotiX again frees up the PC to do other more interesting things.

Issy is one of my 3 ROS test bots right now, I'll post about the other 2 shortly.

-Fergs

billyzelsnack
06-22-2010, 07:41 PM
Very cool.

Did you ditch the fit-pc2 case? I made a custom case and shed at least 100grams, but it no longer can be passively cooled and needed a fan.

lnxfergy
06-22-2010, 09:56 PM
Very cool.

Did you ditch the fit-pc2 case? I made a custom case and shed at least 100grams, but it no longer can be passively cooled and needed a fan.

Thanks! I saw your custom case, but I haven't brought myself to ditching the case yet. I'm currently sharing the FitPC between 2 robots (it's held on by velcro!) and didn't want to mess around with non-passive cooling yet. Once I see how this guy walks, that may change. It currently looks like Issy will come in around 2.5kg, a bit heavier than my previous mechs -- although if he doesn't walk well under that weight, dumping the fit case is probably the single easiest/largest weight loss possible -- after that it'll be tough.

-Fergs

Adam
06-22-2010, 10:26 PM
Very nice. I'm a fan of onboard brains.

darkback2
06-23-2010, 12:07 AM
I have to say I really like the fit PC...if I didn't already have the wibrain I would get one in a heart beat. I can't wait to see what you come up with when your all done.

DB

RobotAtlas
06-23-2010, 07:40 PM
> I've dumped the XBEEs in this application and the ArbotiX is connected with an FTDI cable to the USB of the PC.

By PC you mean FitPC, right?
So there's no external connection to outside world? Is it going to be completely autonomous?

lnxfergy
06-23-2010, 08:12 PM
> I've dumped the XBEEs in this application and the ArbotiX is connected with an FTDI cable to the USB of the PC.

By PC you mean FitPC, right?
So there's no external connection to outside world? Is it going to be completely autonomous?

That is the plan. I also plan to have a PS3 controller (which already has ROS support) for playing around and the inevitable crowd demo (there' something about foot and a half long robotic lizards running around with kids, they love it!).

Mech Warfare is actually the only non-autonomous competition I've ever done -- and this little guy is not going into Mech Warfare....

-Fergs

darkback2
06-23-2010, 10:53 PM
Is the PS 3 remote running under linux or windows?

lnxfergy
06-23-2010, 11:02 PM
Is the PS 3 remote running under linux or windows?

ROS is currently Linux only.

-Fergs

Zenta
06-24-2010, 01:05 AM
Hi,

Wow!
Your Issy3 looks great, the custom made 3D printer (Makerbot) feet with sensor looks very interesting, any more details about the feet? (Oh, forget it, I checked your blog.. ;))
How many DOF on the head and tail, 2 on each?
I'm looking forward to see more of your very inspiring work. Thanks for sharing!

-Zenta

lnxfergy
06-24-2010, 09:46 AM
Hi,

Wow!
Your Issy3 looks great, the custom made 3D printer (Makerbot) feet with sensor looks very interesting, any more details about the feet? (Oh, forget it, I checked your blog.. ;))
How many DOF on the head and tail, 2 on each?
I'm looking forward to see more of your very inspiring work. Thanks for sharing!

-Zenta

Yeah, the part that's missing in the blog about the feet is that there is a piece of aluminum flashing inside that makes connection with the screw -- and acts as the switch. (and interesting note: aluminum flashing apparently has a non-conductive clear coat? I had to file that off to get the foot sensors to work).

The head is 2DOF, pan then tilt. The tail is currently 2DOF - I had planned to add some extra micro-servo driven sections at the end for looks, but that isn't going to happen right away as I'm concerned about Issy's weight.

-Fergs

lnxfergy
06-24-2010, 01:40 PM
Quick update, and a picture. The tail is printed, legs are assembled (still need to have the switches wired in). His camera mount is printed, but I still need to make his snout -- that's going to require getting my heated build platform installed on the Makerbot (it's still sitting in the bag from like 3 months ago).

-Fergs

http://forums.trossenrobotics.com/gallery/files/1/7/6/8/pict0007.resized.jpg

(and after taking this picture, I realized I need to change out those ugly white bushings for dyed black ones...)

darkback2
06-25-2010, 12:33 AM
That is pretty big, but it seams like it will all be well balanced. Any thought of mounting the PC virtically to save space...though that would throw off the cimatry so never mind. Also how will having such a wide stance effect your walking gates? I know you plan to use the tail for balance, but it seams like it would be mostly for balancing out the head? I guess you could always stick with dynamic gates?

DB

SteamAutomaton
06-25-2010, 04:53 AM
If I remember correctly, Issy is a play on the words 'Is he'. Are these the full names of all the Issys?
Issy1 = Issy done yet.
Issy2 = Issy better yet.
Issy3 = Issy lizard yet.
Issy4 = Issy cute yet.
:D

In humor,
SA;)

lnxfergy
06-25-2010, 02:11 PM
Good News: Issy can walk! I'm planning to spend a bit more time tuning in the gait before I post any videos, but I had him walking around last night using a mostly stock NUKE gait. After about 10 minutes his servos were still cool to the touch, so I'm hopeful he'll be able to go the full 30-40 minutes that his batteries can provide without overheating (especially once I have a nicely tuned gait).

Bad News: I knew I couldn't print the snout until I had upgraded the makerbot to use a heated build platform (the part was far too large, would certainly warp more than was acceptable). I ordered a Rev2 heater platform when they first became available back in March or so, but had yet to install it. Finally did that today. In the process of upgrading to V2 firmware on the extruder, the temperature tables became corrupted -- and I didn't notice at first. Anyways, while it was heating the extruder, it was way overheating it -- to the point where it melted the thermal block. To make a long story short, the makerbot extruder basically exploded on me this afternoon. I've ordered the repair parts, but it's sure to take a few days to get here, and them I'm sure to still have a day or so of tuning to get the thing fully ready to go again. So it looks like Issy won't have a snout anytime before mid-to-late next week.

-Fergs

jes1510
06-25-2010, 02:52 PM
Ouch!

RobotAtlas
06-25-2010, 07:46 PM
Sorry to hear about your makerbot Mike.
Tomorrow will be a better day :)

Is Issy3 wiggling its tale while walking?

Quantum
06-26-2010, 12:41 AM
Mike how happy are you with the makerbot? Just a general question.

lnxfergy
06-26-2010, 01:37 PM
Is Issy3 wiggling its tale while walking?

Just a bit, I'm still working on the gait. Eventually he'll be using body shift + tail swinging to balance his body. I want to make sure that he can get stable on 3 legs, so that I can do a nice, stable ripple over rough terrain using the foot ground sensors.


Mike how happy are you with the makerbot? Just a general question.

Pretty happy. I went in knowing it wouldn't be turn-key, and I've gotten a lot out of it. I really haven't used it to it's fullest potential, the bot really only runs a few hours a week. This is really the first major break I've experienced.

-Fergs

RobotAtlas
06-26-2010, 08:18 PM
I can't quite see on that picture, which cameras are you using?

lnxfergy
06-26-2010, 08:38 PM
I can't quite see on that picture, which cameras are you using?

I'm using 2 Microsoft LifeCam Cinemas. They are pretty much fully UVC compatible (so no funky drivers under linux), they have a very nice clear picture, and most importantly they seem do really well streaming 320x240 stereo at 15 or 30fps. The case is also the shape that I like for a set of stereo eyes (unlike, say, the Logitech 9000 that are on several of my other bots).

-Fergs

lnxfergy
06-30-2010, 08:49 PM
Haven't had much time to work on Issy this week. The parts for the Makerbot showed up today, so I'm hoping to have that operational on Friday and get his snout printed. In the meantime, I've been playing with the gait a bit:

YouTube- Issy3 Walking

My camera is also back in operation, so I snapped some shots of headless Issy:
http://forums.trossenrobotics.com/gallery/files/1/7/6/8/img_1799.resized.jpg

Psykoman
07-01-2010, 02:39 AM
Nice work. Looks really cool. Can't wait to see more

lnxfergy
07-05-2010, 04:05 PM
I've finally got Issy's head printed and assembled. It took a few tries:

http://forums.trossenrobotics.com/gallery/files/1/7/6/8/img_1851.resized.jpg

The first 3 tries at the snout, crashed for various reasons. The first was due to a broken extruder, the second/third due to the extruder shutting off, which I eventually traced to a serial drop-out. Once I switched to using the SD card for printing, the snout went along mostly OK, but 2 hours into a 3 hour print, the bed missed a few steps and the snout was shifted about 1/4" -- at that point I shut the print off and assembled it anyways.

Upon assembly, it was clear that the snout was taking up a visible portion of the camera view. I resized it to be a bit smaller, both to be more printable and to address the field of view issues -- I also increased the size of the camera mount part so that the snout didn't have to be as deep. 5 tries, and I finally had a snout + camera mount that worked. (I also reduced the camera base distance between them to 2" from 2.25" since I'm mostly concerned with up close when dealing with stereo).

And so, here's the final head:
http://forums.trossenrobotics.com/gallery/files/1/7/6/8/img_1858.resized.jpg

-Fergs

Pi Robot
07-07-2010, 06:51 PM
Hey Fergs,

Amazing construction work on Issy3! I was wondering how you guys are coming along on your ROS code. If you need a beta tester, I'd be happy to help out. I've brought myself up to speed on Python these past few weeks and I already have a ROS installation running on a Ubuntu machine. It seems to work fine with the Georgia Tech Robotis library.

--patrick

lnxfergy
07-07-2010, 07:15 PM
Hey Fergs,

Amazing construction work on Issy3! I was wondering how you guys are coming along on your ROS code. If you need a beta tester, I'd be happy to help out. I've brought myself up to speed on Python these past few weeks and I already have an ROS installation running on a Ubuntu machine. It seems to work fine with the Georgia Tech Robotis library.

--patrick

Thanks. We're coming along on software. I intend to have several major beta releases shortly (A new PyPose/NUKE beta, and a beta of the ROS code). It's taking a bit longer than I originally anticipated to prepare some of the documentation, and also integrate the odometry. I've also been a bit distracted on a few hardware projects, getting a few new/upgraded products prepared.

-Fergs

Pi Robot
07-08-2010, 08:01 AM
Thanks for the update--I'm looking forward to giving it a try when you make your first release. And yeah, I can sympathize with the juggling act between hardware and software development!

lnxfergy
07-11-2010, 02:07 PM
I've wanted to try an active spine on a fully actuated bot for some time, I was originally concerned with whether Issy could even carry all the weight I put on him so far -- since he can, I he was torn apart and everything between his front and rear legs was replaced. Instead of a static body, he's now got 2 servos for an actuated spine -- making him an 18 servo 3DOF Quad. Based on my experiments last fall with 2DOF Sally (http://forums.trossenrobotics.com/showpost.php?p=35983&postcount=4), this spine should really improve his walking capability -- especially since he has fairly short legs, and a lot of centralized mass that can be shifted around easily this way.

Upgrades partially done: the battery holder "rib cage" has been installed, the spine has been constructed:
http://forums.trossenrobotics.com/gallery/files/1/7/6/8/img_1865.resized.jpg

Upgrades completed: a new sheet metal plate mounts to the top and bottom of the rib cage, making a mounting spot for the FitPC2, and a skid plate on the belly.
http://forums.trossenrobotics.com/gallery/files/1/7/6/8/img_1880_1.jpg

I've just about got the IK reconfigured to do handle the body bending, hopefully I'll have some videos of walking in the next few days.

-Fergs

Zenta
07-13-2010, 01:45 AM
Hi,

I really like the actuated spine! (I've been thinking of doing the same one time too).
But I think a version of this robot using the smaller ArbotiX board would look even better than the rather big FitPC2 (IMHO). Do you have more pictures of the fully assembled Issy3?

As always, great work Fergs!

-Zenta

RobotAtlas
07-13-2010, 11:40 PM
Here's a link to tutorial on pairing PS3 control:

http://www.ros.org/wiki/ps3joy/Tutorials/PairingJoystickAndBluetoothDongle

lnxfergy
07-16-2010, 08:49 PM
As has been alluded to in several other threads, I decided to dump the spine after fighting with it for a short time (it probably could be done, but I just didn't want to continue down that path with the spine constantly shaking itself loose and/or overheating).

I designed up a new chassis, slightly longer and skinnier than the original one that I had. It's laser cut from 1/8" ABS and wraps around my 4300mAh 11.1V battery. The FitPC2 fits on top, and the control/interface board mounts to one of the upright risers:

http://forums.trossenrobotics.com/gallery/files/1/7/6/8/img_1893.resized.jpg

This picture doesn't show Issy's head -- his neck is still under reconstruction. Since the coxa servos butt up against each other, I have no room for a head pan servo to fit in there. I really disliked the look of his sticking so far off the front of the chassis, so I printed a set of brackets to construct an HS-81 based pan and tilt that is about 1/3 the size of the AX-12 one.

-Fergs