• Hands and Handles

    Radomir Dopieralski • 07/28/2016 at 11:56 • 0 comments

    The acrylic rods just arrived, so with help of a lighter and a bit of glue I was able to make the "handles":

    Since I had the rods already, I decided to also use them for the forearms of the hands:

    Finally, I found some LED lenses that glued together made a good "snout". It's slowly starting to look like a proper Logikoma:

  • Eye Socket

    Radomir Dopieralski • 07/06/2016 at 11:12 • 0 comments

    If you look at the plastic Logicoma toys, you will see that the "turret" is pretty detailed -- it has all sorts of bolts, handles, grooves, etc. Mine is smooth, because it's just an acrylic ball. But I do plan on adding all those details, eventually. I decided to start with the eye socket, because I have a theory about how to make it, and I want to test it.

    Since the eye hole in the acrylic ball is cut by hand so that the eye fits in it, I don't know the exact dimensions. So I just placed it against a piece of acrylic and traced with a pen. Then just added the details.

    Next, some dremeling. Who needs a laser cutter. It's maybe not perfect, but it's cheap and fast.

    Then, I placed the soon-to-be eye socket in a metal ball that I had lying around (it was a box of chocolates for Christmas or something like that) and placed it in an oven. When the acrylic softened, it got this nice covex shape. I adjusted the "ears" manually a little (careful, hot!), and got something that fits on my acrylic ball just right (also drilled the holes):

    Next, I drilled corresponding holes in the ball and used the rest of my plastic bolts to secure it in place.

    It's not exactly as in the movies, but I think it's close enough.

  • Early Prototypes

    Radomir Dopieralski • 06/27/2016 at 09:06 • 0 comments

    I just realized I didn't put here the videos of the early prototypes that I made to test if the idea is possible.

    Here are they, first, the wheeled mode:

    And then the legged mode:

    Hopefully I will program the final robot soon and upload a video of its operation.

  • New Brains

    Radomir Dopieralski • 06/22/2016 at 11:54 • 0 comments

    For a long time I couldn't decide what to use for brains for Logicoma-kun. The initial experiments were done with Arduino, but I'd like something stronger and with the possibility of remote programming. For a time I had high hopes for the WiPy -- I waited for it to be released and then for the Timer bugs to be fixed, so that I could use it to control servos. But when it was finally fixed after several months, it turned out that I can't control enough of them at once easily, and that programming WiPy over FTP is quite awkward.

    Now that the Micropython for ESP8266 is re-done and working great, I decided to use the old combo: Arduino Pro Mini as a servo controller, and an ESP8266 module for the main brain. Promptly, I put together the whole thing on one of my breakout boards:

  • Reversing a Servo

    Radomir Dopieralski • 12/20/2015 at 16:11 • 0 comments

    It's been a long time since I worked on this robot, mainly because I got stuck with the hands mechanism. You see, I want it to have hands like the original Logikoma had, and since I have one free servo channel, I wanted them to move, allowing me to grab things with them. This gets rather difficult to do if you don't want to make custom 3D-printed or laser-cut parts, and I didn't think about it when I was ordering the laser-cut chassis.

    I finally had this idea -- I can just mount the hands directly on two servos, and connect both servos to the same signal -- pretty much what I already do with the wheels. But then there is a tiny complication -- I need the servos to move in opposite directions. There is really no room to mount one of them up-side down, so I still had a problem.

    Then it occured to me. If you open a servo, you will see the PCB with the electronics, and some leads going to the motor and to the potentiometer:

    Swapping just the motor leads won't work -- the servo will go crazy and try to move in the opposite direction than it wants. But if you also swap the potentiometer leads, then all is good again -- both the motor direction and the position feedback are reversed. Voila, a reversed servo!

    Now all I need is to attach them under Logicoma-kun's body, and connect to the one servo channel:

    Then attach the hands to them, and we are done!

  • The Eye

    Radomir Dopieralski • 08/29/2015 at 17:30 • 0 comments

    I still don't have a nice solution for the hands, but I'm leaving that for later. Today I decided to work on the eye.

    As I probably mentioned before, I plan to put a distance sensor inside that rotating eye. That means I need a distance sensor that is small enough. Fortunately, I have bought several of those time-of-flight sensors that were described on Hackaday some time ago, so I decided to use those. Some time ago I made breakout boards for them, so it was time to actually cut them out and try the thing.

    Turns out that soldering QFN packages with a soldering iron, and with the pads not sticking out even a tiny bit, is practically impossible. But I remembered that in the FabLab nearby they had a hot air gun. That should do it nicely.

    Read more »

  • Wiring and Hands

    Radomir Dopieralski • 08/28/2015 at 17:58 • 0 comments

    I attached the PCB with the brains for this robot (I'm using one of the old PCBs I made for #Tote, affordable spider robot), and connected all the wires. Getting them to the right place was a little tricky, but making a few extra holes helped with that. The power switch is at the back, under the weapons box.

    I'm also working on the hands (the two light-blue parts connected with copper wire), prototyping the mechanism for them. I need them to both move controlled with a single servo, that you can see on the photo. So far I came up with something like this:

    I'm still not happy with this design, I will keep on trying different things.

    In other news, the breakout board for the distance sensor arrived, so I can try if it works and try to put it in the robot's eye. More on that soon.

  • Weapons Box

    Radomir Dopieralski • 08/27/2015 at 13:55 • 0 comments

    In the universe of Ghost in the Shell, the name "Logikoma" comes from "logistics robot". Those robots are supposed to be a fast all-terrain vehicles for transporting weapons and ammo, basically. To do that, they need some storage space, and that's what the box on their backs is for.

    I just finished making that box for Logicoma-kun. It's empty, and opens just like in the movie. It consists of several pieces of acrylic sheet, with paperclips for hinges, all hotglued together.

    I might add some magnets there at some point, to make it snap in place better.

  • Hotglue Everything!

    Radomir Dopieralski • 08/24/2015 at 17:17 • 0 comments

    The acrylic nuts and bolts finally arrived, so I can put it all together. Since I wasn't really sure how everything will be attached when I designed the laser-cut parts, I simply hotglue them together where there is no room for bolts.

    Next step is connecting all the wires properly and programming. I also want to try and fit a distance sensor in the eye, and add the hands and snout.

  • Early Experiments

    Radomir Dopieralski • 08/13/2015 at 13:57 • 0 comments

    So this project actually started some time ago with some simple experiments. First, I modified #Katka, a mammalian robot to walk more like a spider, and then I added wheels to #Tote, affordable spider robot to qualify for a prize draw. And that paid off, as in one of those prize draws I won a coupon for laser-cutting service. Then I decided to rebuild this robot into a proper Logikoma lookalike, using that coupon.