Mechanical Robotics

Wheel Hubs and other Modifications for my Kaya

Just a very short blog on some wheel hubs I designed for my Kaya. Following the build of my Jetbot, I wanted to experiment a bit with the Intel RealSense Depth Camera D435 in combination with the Nvidia Jetson Nano board, and decided to up the ante and build a Kaya robot as well.

This has been one of the more challenging projects I’ve done so far. I really enjoyed printing the very nicely designed plastic parts, but found it hard to source all the components as specified on the Kaya Github. In the end I managed to source all with the exception of the VEX 3.25″ Omni-Directional Wheel with SKU part number 217-4775 and the Terminal Block from McMaster with associated Terminal Block Jumpers.

After some more searching on the Internet, I found VEX 3.25″ Omni-Directional Wheel with SKU part number 276-3526. They have the same outside diameter, but have a slightly different arrangement of the rollers and have a different hub design. I was not able to find the Terminal Block for sale in Europe. Hence, I had to design and print custom wheel hubs and a look-a-like terminal block. You can download the design of the wheel hubs on Thingiverse if you’re running into the same issue as I was running into. I will add the design of the Terminal Block as soon as possible to Thingiverse as well.

As you can see from below pictures, the wheel hubs fit nicely on the servo motors and on the omni-wheels.

In below picture you can see how I resolved the issue of the unfindable terminal block, replacing it with a custom designed terminal block:

Custom Terminal Block for Nvidia Kaya
Custom designed terminal block on Kaya.

One more thing before I end this really short blog: I ran into trouble with powering up Kaya. Almost every time I switched the power on, the power light on the Jetson Nano board would light up only to turn off again after a few seconds. Really annoying, and it took me a some days to figure out what went wrong. Powering up using the power adapter worked fine, powering up using an USB cable worked too, but powering up over the batteries did only work in approximately 50% of the times.

Only once I changed out the 2.1 x 5.5mm Male Barrel Plug Pigtail, with a Male Barrel Plug Wire Adapter with thicker (larger diameter) wire, did I manage to resolved this. The Kaya robot now powers on without exception when on battery power.

Thick wire replacement of thin wire pig tail.

Although short, I do hope you will find this blog useful when you build your own Kaya or are running into the same issues as I ran into when building. Please do let me know if this has helped you somewhat or your missing information.