I found a model for a quadruped on thingiverse, and I want to use it as a way of learning basic spider-style robot control as well as 3D CAD. The model provides only a basic chassis, so I will have to do all the control board and sensor mount design.
I have an OpenSCAD model done up for the base plate; I'm new at 3D CAD so this is mostly a matter of trial and error. I targeted a basic plate with M3 mounting screws (matching the Qu4druped model base plate) and a pair of mounting holes for an 18650 battery pack. The first print shows my screw holes are a little small.
I have one leg (a mirrored leg) printed and assembled correctly. I've had a lot of trouble printing parts for this, which I'll talk about in a future log.
The picture also shows the control system that I'm using to experiment: a Sparkfun Blackboard and a Sensor Shield 5.0 that I got in some kit at some point. It works, but I've got a Teensy 4.0-baesd control board that just left for the fab tonight. The first experiments were... a little twitchy.
My plan is to use this to develop a serial-based gait test platform. Basically, it will receive lines over the serial console in the form
3 15 15 145
That's the leg number (number three is the back right leg), the servo angle (0-180º, with 90º as the "neutral" position) for the first (innermost) to third (outermost) servo. I'm building out a chart of general servo settings to help develop the gaits, and I'll probably use a Python program on my laptop to test out gaits - that will help me figure out gaits for walking, turning, obstacle navigation, etc.
Eventually, I might go to a Raspberry Pi/ROS-based system with maybe a TFLite model for motion planning. This will go hand-in-hand with a general pan/tilt sensor system that I'm designing. I have some drawings, but my CAD skills are not up to par yet.
I still need to print another mirrored leg, and I have segments 1-3 of the non-mirrored legs. I'm debating printing out section 4 (the black leg tip) in PETG because I've had a lot of problems with cracked parts, even right out of the printer. I think PETG might be helpful because it's more flexible but I need to install the high-temperature nozzle in order to do that.
I used ABS, 20% infill, 235°C, with rafts. Leg 4 needs supports, though I would only print supports from the print bed up (I ran into issues with rafts filling the mounting holes).