The Sixi 3 robot arm is the result of many years of study and research. I’m trying to build my dream machine that avoids every problem discovered in my previous robot arms. My short list of desirable things include:
Easy manufacturing = use less unique parts = use repeating components.
Easy maintenance = daisy chain components.
Safer = no loose wires, always know where the arm is, responsive behaviour. (safety third!)
To that end I’m on my second attempt to design and program the board of my needs. Here’s where I’m at today, December 31, 2022. Read on for all the details.
So you built a Spot Micro (or you want to) and – because you’re very clever – you read the instructions first. You probably noticed there’s a section where you have to build a PCB from scratch. For a lot of people, that’s beyond their skill level …for now. In the meantime, nothing should hold you back from building a sweet walking robot dog, amiright? Cool.
Here’s a board we used in the past for a stewart platform, which are a type of robot you can read about elsewhere on this site. It’s a good start for driving a robot dog. ELEC-0132 stewart platform board was designed for 11 PWM signals out and 6 analog values in. I’m betting that one of them can be used as an extra out signal to drive all 12 motors in the Spot Micro’s legs.
Makes life easier by cleaning up all those messy wires in your prototyping. hanging off the side makes it easy to fit in a two part, 3D printed case. We use it as part of development for our Sixi Robot Arm.
You can get all the details and order them for you or a friend right now.
With this we can finally finish the hardware preparation for shipping
units, after which we can also get a final bill of materials and start
to package DIY kits. There will be two flavors:
DIY kits with all the non-printable parts.
DIY kits with everything, including the printed parts.
The software only lets each joint of the robot move within a safe
range to prevent wire twisting or other potential damage. That piece of
code does not consider the angle of joint A in relation to the value of
some other joint B. So it was still possible to make the arm hit
itself.
This new collision detection code prevents each bone of the arm from
colliding with other bones of the arm. At present it is a crude
collision detection system, using only the box around each joint.
Also now that these boxes have been calculated, the center of each
box is known. the mass of each bone can be pulled from the Fusion360
model, and then a point-mass physics model can be created to simulate
forces like gravity. This gets us closer to dynamics like push-to-teach
and telling the arm “please push on this item with a force of N
newtons”
Next
Next we’ll be assembling the new shoulder design with the PCBs that
should allow us to unplug the umbilical from the arm and the control
box. I’m thinking Twitch stream? Maybe just a Youtube Live, given the
recent Amazon protests. Choice of evil companies… hmm…
