The quad A1 was the first robot I built with foam cast feet.  When I did the first feet, I jury rigged a fixture from some old toilet paper rolls to hold things in place while they were curing.  When I went to rebuild with my most recent leg geometry, I figured it was time to get at least a little more serious.  Thus, my new leg casting fixture:

When an insert is cast into place, it is set on one of the trays, the tray is inserted into a slot, and then a weight can be placed on top and constrained by the fixture.

Continuing in my series of developments with the Mech Warfare turret, I’ve now managed to replicate the primitive target tracking functionality I had in the v2 version of the turret.  This works using a pretty simple principle:

• raspicam is used to read the raspberry pi camera
• ArUco is used to find any fiducials in view
• The target closest to the center is deemed, the “active target”
• The pitch and yaw rate are set based on a simple P controller to bring that target to a known point

This works passably, as shown in the video below:

I finally got around to fixing a number of minor glitches in the quad A1’s chassis recently.

1. The raspberry pi is now far enough away from the left panel that you can connect the HDMI if you choose.

2. I no longer have vestigal studs for the pre quad A0 junction board on the other side.

3. The switch got moved down to between the legs.

As part of provisioning a quad A1, or anytime the mechanical configuration has been changed, I need to go and record where the zero position of all the joints is.  The “0” position for the software now is with the shoulders perfectly horizontal, and the upper and lower leg sticking straight down.

Up until now, every time I’ve done this it has just been by eyeballing and with lots of foam and bubble wrap to shim things into place long enough to record the level.  Sometimes I had to go back and try a few times, as even determining when something is straight is not, well, straightforward.

Like with the fdcanusb, I built a programming and test fixture for the moteus controllers.  The basic setup is similar to the fdcanusb.  I have a raspberry pi with a touchscreen connected via USB to a number of peripherals.  In this case, there is a STM32 programmer, a fdcanusb, and a label printer.  Here though, unlike with the fdcanusb fixture, I wanted to be able to test the drive stage of the controllers and the encoders too.

The Mech Warfare turret concept I’m developing involves having basically two independent robots, the actual robot and the turret.  To make that be controllable in a sane way, the control station will command and receive telemetry from both simultaneously, allowing control actions to be given in the camera frame of reference.  Otherwise, remote piloting is… very challenging.

This could be done just by having two separate transmitters.  Since the nrfusb that I’m using is spread spectrum, many transmitters can easily co-exist at the same time.  However, the protocol is designed such that a single transmitter can simultaneously communicate with multiple slaves at the same time, simply by switching channels more frequently.