Next large robot

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  • Anodizing adds about 0.001 inches dimensionally that has to be taken into account in some locations such as press fit bearing pockets.

    No name for the robot so far, been kind of waiting for it to take its first step first! Besides, I haven't been able to come up with anything catchy yet! Transporting the robot will be an issue in the future. If I can teach it to climb into the bed of my truck that will solve that problem. That would probably require that I teach it to climb stairs or a ramp also.
  • @Diverbob,

    if build together completely it will need to climb stairs to get out of your basement.

    You do not want to carry it all the time and it even has more legs as you. Riding it might be a challenge.

    Love your work and dedication.

    Mike
    I am just another Code Monkey.

    A determined coder can write COBOL programs in any language. -- Author unknown.

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this post are to be interpreted as described in RFC 2119.
  • I got the test leg re-attached to the robot body after validating the sensor wiring to the prop board and making up some new connectors. I had to make some 'adjustments' with a file on one encoder housing, the end of the shaft was rubbing against the bolt head and causing the linkage to rub against the housing. This required careful use of a file to get the parts to play nicely together without binding. Everything is now ready to calibrate each axis and start testing the programs. So there is still progress in a positive direction!

  • Go Bob GO!
    Infernal Machine
  • Apparently I miswired my encoders, got the CS and CLK wires switched around which explains why I haven't been able to get anything to work right on the leg. Got that sorted out now and when I started to run the calibration routines the wrong motor responses to the input commands. It's been very frustrating lately with the software, I may need to go back a software copy from a couple of versions ago where I know everything worked and start my mods for the magnetic encoder over again.
    Unfortunately I haven't spent as much time lately on the robot due to preparations for my upcoming retirement. Hopefully once I get all this behind me I can concentrate more on the software and get some quality time in. In the meantime I'll get some more work done over the weekend and maybe iron out some of the new issues.
  • Hi Bob
    While getting ready for retirement, please keep track of how many miles you are walking when doing your job.
    Match that with some type of activity after you are retired.
    Sometimes you will need to break away from your projects to clear your head.
    Don't ask me how I know this.
    ..
    Every time I see a DiverBob post, I jump immediately to read any new updates.
    Thanks
  • garyg wrote: »
    Hi Bob
    While getting ready for retirement, please keep track of how many miles you are walking when doing your job.
    Match that with some type of activity after you are retired.
    Sometimes you will need to break away from your projects to clear your head.
    Don't ask me how I know this.
    ..
    Every time I see a DiverBob post, I jump immediately to read any new updates.
    Thanks
    Thanks for the advice! I already have my scuba wreck diving, racquetball (3 times a week), bicycle riding.(20-30 miles daily once the weather warms up), a basement machine shop and a wife that likes to travel. I think we are rapidly filling up the event schedule so keeping busy shouldn't be a problem. The problem is having time to work in the basement on the robot, too many other activities all demanding time.
    Tonight will be dedicated to figuring out the issues with the Coxa routines and get them sorted out first before I start on the other motors.

    Bob
  • ercoerco Posts: 17,693
    Bob: Didja see this?

    http://forums.parallax.com/discussion/166558/man-carrying-mantis-hexapod

    You and that guy Matt can compare notes, although it doesn't look like he's done much recently.
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • The Mantis is a cool project! I think I've watched most of the videos out there in this hexapod. Lots of engineering went into it. You are right that I haven't really heard anything new on it for a couple of years now. And Mantis is a great name, wish I could come up with a cool name for my project too!
  • I didn't back out of the current version of the program but spent some time going though the logic to familiarize myself with code that I haven't spent a lot of time with lately. With that accomplished I decided the best way to fix things was to first write down a list of the items that were going wrong and attack them individually rather than jumping all over the code. Using this method I got the calibration routine working, mostly. One small issue remains on calibration to track down but that isn't a major concern and is now on the list!
    Once that was done I found that the coxa motor move routine is working once again, YEH! I see more backlash than expected showing up in the magnetic encoder output when reversing direction, looks to be around 100 counts or 0.8 degrees of motion. I'm contemplating methods that could remove/reduce the backlash, I like to physical location of the encoder and the connection to the leg using springs. I may try a miniature turnbuckle from model airplanes as a connecting rod, that could be adjusted to remove all slop in the connections.
    I found that I could get 0.16 degree movements out of the coxa motor now with the PID. I reduced the PID deadband to 2 counts to get this. I'm not sure I can go to a 1 count for deadband, that is an experiment for another day.

    Bob
  • Continuing work on setting up the magnetic encoders. I now have the coxa and tibia motors working properly to input commands. Got started on the femur routines and have a couple of more hours of coding/troubleshooting to go on it. The additional accuracy of the magnetic encoders has revealed that there is some backlash in the system, I don't know if its enough to cause issues with the overall leg movement yet.
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