It's alive!

 Hi!

In this entry, I'll go over the Wolfie assembly process and in the end, I'll show you the full-body kinematics demo of the robot. It's been a very rewarding time for me, especially when I saw the robot stand on its feet for the first time :) 

Let's start with the hip actuators mounted to the 3D-printed frame:

As you can see I started with assembling first four actuators and two opposing parts of the torso. I wanted to make sure the length of the power supply and CANFD cables I estimated is correct. They couldn't be too long as there is very little free space to fit all the actuators' cables. The two parts were joined by these side covers made from epoxy laminate. My initial idea was to make them from bent aluminum sheets, however, the bending process could be a little tricky without proper tools so I went for the laminate. I cut these on my CNC mill, making two grooves along the bend line:

Later on, I screwed them to the 3D printed frame and added epoxy adhesive in the grooves. This made them very stiff. Overall the robot structure feels stiff which is great, considering it is mostly held together by these two covers and the bottom plate. In the next revision (this is just a first prototype) I'll definitely go for inserts so that I can easily unscrew the side covers and the whole torso assembly. 

Next up there were the four thigh actuators that are mounted to the hip actuator output harnesses:

As you can see I also prepared the cables for both hip and thigh actuators, and for latter pulled them through a special duct right to the inside of the torso. Tibia actuators were mounted in the end:

They whole actuator structure is actually pretty hard to assemble, but since it's just a hobby project I decided to leave it as it is and not optimize it for now :P. 

I think just by looking at the last picture you can see the amount of connectors and cables inside the torso - its really dense in there. My plan was to use distribution PCBs like in the picture below:

unfortunately my PCB parcel got stuck in the customs and I had to mill these two by myself:

The cables look much nicer when these distribution boards are in place:   

The laminate barrier part that you see inside the torso is just a piece of epoxy laminate with some nuts glued to it: 

             

One of the last things was to put a sticky black foil on the covers so that they matched the rest of the assembly:

And finally! Wolfie the quadruped: 

I know, its missing a few parts, but still it was a big event to put all the parts together :) Moreover I got it to move a bit: 

This is just a simple demo, with kinematics implemented fully on the computer in a python script which then sends the commands to the actuators through USB<>FDCAN converter. When I finally receive the PCBs I will implement it on the raspberry PI so that it could be completely standalone. 

In the end I want to mention the presentation about Wolfie which I gave during the Reddit r/Robotics Showcase. The whole event was recorded so feel free to check that out (my presentation starts at 01:04:30): 

https://www.youtube.com/watch?v=HLFfAnheun8&t=137s&ab_channel=theredditroboticsshowcase

Now I want to tweak the walking algorithm which I'm not totally satisfied with (that's why I didn't publish it yet) and eventually implement some more advanced walking techniques, which require doing some more research :) I'll keep you posted!