Yet another 3d printed hexapod, but this one is mine! (and it's matte black)
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The robot will first run tethered to a computer and PSU while I develop the software for it. It runs on ROS Melody using Ubuntu 18.04.
I will eventually upgrade it to have a LattePanda Alpha on it's back so that I can run ROS on board and experiment with vision/SLAM and an IMU.
I plan on making the CAD files available once all the issues are fixed.
I am currently working on the startup routine. I am coding a finite state machine to manage the different states and their transitions into one another. For example, I currently have idle, sitting, standing and walking states set up with events to transition from one to the other.
I'm in the process of coding the standing state, which will consist of sensing where each leg is, bring them in a safe sitting position, then stand up.
There won't be any cool build pictures for a while. I'll be working on the software until I'm comfortable letting it run outside of the simulator. I still have a bunch of stuff to do before I can do this. After tuning the model in gazebo I have to code a startup routine where it will sense its limbs and safely bring them into a "sitting" position before standing up. Then I'll need code to manage switching leg distance from the body, so that I can reduce the large footprint that the long tibias is causing during the standup procedure before walking.
It can't move yet, but I made a first powered test to make sure that the motors were able to withstand the mass of the thing. It feels a little weak when I put it in a tripod configuration, I'll have to check if it's the motor or the power supply that's the issue on that one.
Disclaimer: I will properly fuse and mount it in an enclosure. For the time being, don't worry, this is in a tupperware so that neither me nor my cats can put their paws on the exposed live wires.
Every time I have to solder one of these I end up with the wrong plug on the wrong cable. The fact that the male metal plug goes in the female plastic plug confuses me. At least positive/negative are on the proper side, just don't connect a battery directly to a power supply or another battery by mistake.
2019-04-01 Printed and assembled the tibias.
I started to be scared that the servos wouldn't be strong enough at that point. I really ended up being heavier that I thought. I still have to eventually stick a computed on it's back and a battery inside of it. I could have made all the calculations in advance, but where's the fun in that?
Seeing it outside of Fusion360 for the first time I realize that the tibias a too long. It's not a practical position to start from in order for it to stand up. It can't bring the legs closer to the body like this and will use more energy getting up. It will also have to reposition its feet before walking as this is probably too wide of a stance to start with.
2019-03-31 Printed and assembled the femurs
2019-03-31 Printed and assembled the coxas.
Unfortunately, I had designed the parts with enough clearance for a 0.2mm print but I decided to go with 0.3 at the last minute. So the slicer didn't round the values in my favor everywhere and I had to remove material with a knife to make the femur motor fit. Some screw holes even cracked as I was putting the screws in. It looks like it still holds for now but I definitely have to add more material around the coxas side tabs and maybe print in the other direction to make them stronger over the servo horn ones.
2019-03-30 Printed and assembled the body during the weekend.
I didn't trust the original cables to be beefy enough for the power required to handler the load on 9 servos per board, so I replaces a connector with male headers onto which I soldered my power distribution. It will eventually have to change as my final goal is to have it run untethered with an on-board battery.
The finish on a 0.3mm print is not that great but I wanted my parts to be more solid. On a positive note, the matte black PLA from ColorFabb looks so good!
2019-03-28 Started testing, numbering and grouping motors by leg.
2019-03-27 Received the additional fifteen servos and a bunch of accessories. This is starting to get real, I can't wait to build the robot now.
Brilliant project! I've always wanted to try some robotics, but I've never had the skill!
Nicely done! Love the design, but maybe I'm biased :)
Looking forward to seeing your progress!
Hehe thanks! I've always wondered why more people don't go for that longer leg design, it looks so good! I guess it has to do with the required torque (a thing I still haven't figured if I'm in the clear with my xl430s).
Thanks again for passing by, I'm not feeling any pressure at all now that I know that you are here looking ;)
Awesome design, What a beast! I just sent Matt Buenting a link to this project.
Thanks! I'd be humbled if he looks at my project. I'm such an amateur in this field.
Glad to see your project in here too! I thought you are only active on Instagram.
Thanks, I don’t know why I didn’t think about it earlier ;)
Looks amazing! Glad you got the standing test to work. The modelling software is amazing, yet still interesting to me that it's not until the first version is printed that you really get an intuitive idea of scale (weight and leg length). Keep going, I love seeing it come together!
It’s my first time designing something that extensive in Fusion360, I guess those are things you get better at with experience.
Maybe. But for me, the ability to zoom in EDA software just by rotating the scroll wheel means I can't really tell how big things are going to be. With PCBs I print out the board artwork to get a true gauge of the size. Your experience feels the same, which I like because it validates my thought that this is just how it is ;-)
I think it is great that you did not have enough experience! your spider looks so different from the other ones and I think this is what makes it standout. So to me, I am glad it turned out this way. I just hope your servos can handle everything. IMHO 80% of the love you have and will receive for this project come from its long legs and cooler look :D
I can't reply to your reply on my reply, but yes, how many times have I been zoomed in, adding .5mm chamfers to everything, only to realize it only looks pretty in the renders but will never show up in my .3mm 3d print.
François Ubald Brien
I don't know why, I always enjoy having a bunch of similar objects that pack nicely together.
Joseph Marlin
Apollo Timbers
pRoFiT
Les Hall
Looks awesome! Do you share your 3D Model/3D parts of your hexapod. I'm planning to use dynamixel xl430s too, but cannot find 3D parts anywhere! Thx