The next level of difficulty in bazel-ifying packages for mjmech was opencv.

First, for the impatient, Apache 2.0 licensed sources are available on github: https://github.com/mjbots/bazel_deps/tree/master/tools/workspace/opencv

OpenCV’s native build system consists of nearly 200 cmake files with over 20,000 total lines of code, plus assorted helper scripts and prototype files which are substituted into.  Fortunately, I didn’t need to support the full complexity of the opencv build system.  Things I didn’t bother to touch:

After the initial leg jumping with the prototype brushless actuator for SMMB, I spent some time actually tuning the control loops and making the firmware not incredibly convoluted to get started.  I also acquired a high speed camera for analysis.

So, here is a brief update of the final jump before I seem to have toasted one of my DRV8323 motor drivers.  It jumped for about 400ms of hang time, running at about half of the maximum current the system should be capable of pulling.

In my first foray into 80/20, I built a slightly more robust jumping fixture for the SMMB leg jumping test:

Overall it is much more rigid than the old one, and looks a little nicer.  To top it off, I laid down a neoprene sheet for surface protection and friction enhancement, which is a step up from the old cardboard surface both in aesthetics and function.

While working on the improved actuators for SMMB, I wanted to be able to perform some quantitative experiments to design the thermal transfer of the controller board and enclosure.  I figured that feeling with my fingers probably wasn’t scientific enough to make consistent progress.

Enter an inexpensive Chinese thermal imager, which you can find for under $300 from time to time.  A non-affiliate Amazon link: https://www.amazon.com/gp/product/B07BDJZ845

It has a resolution 220x160, reads up to 300C and being intended for construction inspection has at least a little software support for reading out actual temperatures and capturing images for reports.  The only downside is the focal length.  It really can’t focus on anything less than about a meter away.  That isn’t too great for PCB inspection.

This is part N in a series describing how I created the bazel infrastructure to build all the third party packages for mjmech.  Previously we have:

• Building mjmech software with bazel
• Configuring bazel to cross compile for the rpi3
• Building mjmech dependencies with bazel
• First bazel-ified packages

We left off with the first, very simple packages configured to build with bazel.  In this installment we will tackle those that require at least minimal configuration, i.e. those that have some files which are normally generated as part of the build process.

I continue to make progress on the improved actuators for SMMB.  To briefly recap, these are based on a home-built brushless servo consisting of off the shelf gears, bearings, 3d printed assemblies, and a custom control board.

Moving on from closed loop vector (FOC) control, I’ve now built up a second motor, set both of them communicating over the same RS485 bus, and wired up a minimal makeshift jumping fixture.  The leg didn’t jump as well as I had expected: I was only able to achieve about 300ms of air time and there are a lot of other minor problems/deficiencies as well.  But on the other hand, I don’t appear to have permanently broken anything yet, so improvement will hopefully be mostly continuous!