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Thread: PhantomX Hexapod with Nuke - Question on how I am using it

  1. #1
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    PhantomX Hexapod with Nuke - Question on how I am using it

    I have a question on using Nuke with the PhantomX hexapod - I finally this past weekend focused my time and completed the Hexapod - I started a long time ago. So I have Nuke setup, I am using OS X and running everything in a Parallels VM - 32-bit Windows 7, I have found zero issues getting all the software setup, using the Arduino 0018 version, which seems to work nicely with arbotix libraries 0014. I see arbotix2 beta, but decided just to get things working - then I will experiment with newer version and look into ROS, I know Fergs is pushing us to go that route - I do intend to.

    Anyway most seems to be going well, I tried to mess with the downloaded version of the PhantomX nuke gaits, etc, didn't compile up for me and I wanted to go through Nuke. I dug into the files PhantomX files and confirmed the measurements I had taken, they pretty much match up so I used those. I went through the capture process and feel like I did a pretty consistant job with it. I setup the neutral position - that looked good I went to test/signs and that is where stuff goes wrong - doing it twice I had 2 or 3 Tibia on a specific side, go up instead of down - so I had to no/cancel out of the test for all the moves. I saved the project and then went into PyPose pose editor, the neutral looks good, and the ik_min and ik_max I think is okay if I am correct, Min and Max should end up having the hex go into a state where the coxia, femur and tibia are mirrored, so if min has left side coxia forward, femur down, tibia down -> right side coxia would be back, femur up, tibia up. When I do max that reverses - so I am confused why the test setup is moving 2 or 3 of the tibias on the one side (it was left side) to the upward position. The coxia and femur looked to be correctly positioned. Am I moving the tibia too far, I move til it cannot, then back the down, using key visual points - bolts,corners to make sure I am fairly even.

    I am pretty sure I have the robot constructed correctly and having the femur and tibia aligned is pretty straight forward. The default PhantomX build has you swapping the left/right side servo ids from what comes up default on Nuke. I want to get this working with the robot commander test program - then I get into more messing around. Not sure what I am doing wrong - I will likely tonight, step things through and note all of the servo position settings - next step I guess is try to debug Nuke. - or should I just go arbotix2 beta? Is there another arbotix board? I got mine a while back

    Chuck Durham
    "cdraptor"

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    Re: PhantomX Hexapod with Nuke - Question on how I am using it

    A couple notes:

    1) Don't use the arbotix2 beta software, it is for a different board (that is not publicly available). The ROS stuff is also pretty separate from NUKE right now, at some point their code base will merge back and be more tidy.

    2) Don't set the robot to the ik_min or ik_max pose via pose editor -- it's used internally for the NUKE calculations, but it really isn't a valid pose (things might crunch as hitting all the mins/maxes at once typically causes body collisions).

    3) Don't worry about the defaults being different, they are just a quick default inside the program, many people change from teh default IDs.

    The next step really is to export the NUKE sketch, compile it with Arduino, and download it to the ArbotiX to run the test drive. If you have trouble compiling, please post the exact error message that comes out of Arduino IDE.

    -Fergs

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    Re: PhantomX Hexapod with Nuke - Question on how I am using it

    I have an update from my work with this last night. Even with my messed up leg configuration on the one side I ran the Arduino IDE and went to compile the nuke generated sketch. I got an error on commander.h not being present - so I checked the archive file for the 0014 arbotix library - it's missing, the were no Commander folder in libraries. So I downloaded the older 0013 and got the Commander load in, compiled okay, installed - no go, the legs were messed up. I downloaded the PhantomX pre-done sketch from Trossen PhantomX project page, compiled that it worked okay, then installed that on the Arbotix, so now I am playing around. I am going to revert back to 0013 and see if the pyPose/Nuke combination in that works for me. I do have Python 2.7 on my machine, wasn't sure if that is an issue, but next step will be to get Python2.5 on and try that if the reverting back to 0013 doesn't work.


    When I get some time I will dig around in the PyPose & Nuke code more to see what I find but for now it's walking

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    Re: PhantomX Hexapod with Nuke - Question on how I am using it

    Make sure you install the robocontrollerlib libraries http://code.google.com/p/robocontroller/. This will include Commander and many other non-arbotix specific libraries.

    -Fergs

  6. Re: PhantomX Hexapod with Nuke - Question on how I am using it

    I had the same problem getting started. Either one or two of my legs would always shoot out of range after setting the signs in NUKE. At first i thought the mins and maxes were out of range but the true problem was assigning the correct sign. The final set of sign tests are very tricky to get right. This might be related to how my legs were setup but for me it was very hard to tell if the servo was actually moving up or down. I went through the test about 10 times before I finally got it right, but even so I'm not sure if I could do it again! Perhaps you can go in to the test(in the python files) and make it move a bit further so you could better see whats happening. I would defintely go this route if I had to do it over again.

    I tried to reverse the sign in the code but I could not find where the signs where being set.

    Also I would like to know how the endpoints are defined.

    more specificially how they work so I could further understand and use them.
    Such as what joints does X,Y, and Z control? Do they control all three or is there any that only control one? or maybe one that controls both? It says you can modify the start position from there but it says nothing about how to.

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