Wednesday, May 27, 2020

Two Year Anniversary

It has been an interesting year, who would have thought!

It is now Two Years since I started my Totally-Not-Evil-Robot-Army!  

For this blog, I have had over 14,500+ visits.  Hopefully, this is a sign of more Makers becoming interested in the building robots.  

However, I am savvy enough to understand that many (possibly evil - Internet software Robots) have driven some of my numbers.  Web-Crawlers and Search Engines regularly pass through the Blogger collecting information, pictures etc. I have been directly crawled from an Israeli base search engine responsible for at least 3k hits in the last year, by my estimates. Also, this humble blog had been the target of some Ukrainian SEO- Search Engine Optimization hackers, trying to make comments that cross link URLs and drive up results for their customers. I have removed their posts, but I believe I am still in *their* logs, which results in a lot of other victims in their bot army cross-linking to my site.  Thus, I have a lot of referrals from random non-robot, non-educational sites.  <sigh> unfortunately this is part of our modern Internet.  And, it also make the Ukraine the most popular country amongst our visitors.

The Covid-Crisis has also brought in a number of visitors. Perhaps people are building robots while in lockdown?  some of the most popular locations have been from Hong Kong - perhaps a future robot hot-spot?

The year in passing

Well, I did take a bit of a sabbatical for a few months. I had a lot of personal work in relocating to a new home, and even more effort in  starting a new software business.  I am still thoroughly enjoying robot building and will continue to post my adventures in robotics in a public journal. There are many many robots to be built. As we all know, the robots can't build themselves... until they can. ;)

This years robots include a new design for a Robotic Dog - Mojo3.  In addition (as a distraction?) I worked on a Millipede based robot call Milli (original, eh?).  Both of these robots are still in active design stages. Mojo3 is going through walking tests. For the Millipede, I am exploring better ways to drive the robot using recycled printer motors.

Let keep building!

Friday, May 8, 2020

Mojo3 - A Robotic Dog (#10) - New Video Out

 New Video Out

There is a new Video on YouTube showing Mojo3's first (stumbling) steps.  Check it out to see what it is like to try to tune this little robot in both physically and with software.

Only 9g Servos

The biggest challenge with this little robot is trying to only use inexpensive 9g servos.  These are great hobby servos, easy to use and code, and inexpensive if you burn one out. They do have their challenges in the amount of force that they have. I found this to be restrictive in my first attepts with the original Mojo robot dog design.

I believe with good design and engineering, it should be possible to build a little quadruped robot with them. You can see in the video that my in my first tests, the rear servos were struggling to meet the position commands issued by the controller.  The front and back "hips" and "knees" were given the exact same position commands literally using the same computer array of positions.

Then I changed the rear "hip" leg gear positions. I rotated the rear/hind "hip" leg out by about 30-40 degrees. This was easy to do in my new leg design. I simply pulled the hip off of the mount, rotated it back and put it back on.  There are marks for calibration visible in the pictures. The result was a much smoother "hip flex" motion.

New Hind Leg Configuration

The next step in developing the walking gait is to explore how each leg should move to proppell the robot forward. I am starting with just basic movements of the hind/rear legs.  I have replaced the front feet with "training wheels" (like a kids first bicycle). Now the hind legs can attempt to walk without any resistance to the front legs.

More work to come! 

Mojo3 Robot Dog
Mojo3 with 'training wheels' for front feet.

PS:  Quadrupeds on Wheels is going to be a thing!!  Check out this video of Hybrid Locomotion by ETH - ANYmal.