Axon – A biped robot

Axon is basically a handmade version of the robot called “BoB the Biped”. When I found an article on BoB the Biped on the internet, I fell in love with the design immediately and wanted to build one so bad. But it had a 3D printed body. Although 3D files were available, 3D printing was very expensive in Bangladesh back then.

So I decided to make the body using 5mm PVC sheet. Guess what, my first design failed miserably. I ended up with an okayish build after a few iterations.

That’s when I faced the second roadblock. The robot wasn’t being able to balance on one leg, so it couldn’t walk. I initially thought the servo motors I was using were too weak. But I found out afterwards that it was more of a physics problem. I studied a bit about how humans walk, and then mimicked the movements using code. And blam, it worked!

It was so fun to build Axon!

Technical details

The hardware part consisted of:

  • Arduino Nano, to control everything.
  • 4x Micro Servos (SG90).
  • 1x Ultrasonic Sensor, for the obstacle avoiding part. However, I never got around actually coding that part.
  • 1x 3mm Blue LED, to look cute.

I made the body out of PVC sheet, and glued random stuff inside and outside the body for weight balance. See the round black object on the right side? That’s actually a defective speaker attached simply to counterbalance some extra weight on the left side.

Due to space shortage and weight balancing issues, I couldn’t place any batteries inside. Axon was powered by an external power supply, via a power cable.

Things I wish I did better

  • Improving the design process by sketching out the blueprint on paper before beginning the build, and cutting parts with precision rather than relying on intuition. The structure ended up being very unreliable and required a lot of weight balancing.
  • Choosing better servo motors. The SG90 had plastic gears and was very flimsy in design. They were fine for light use. But when it came to making Axon balance on legs consisted of those servo motors, it was a nightmare to work with.

Looking back, I probably should have just gone with the 3D printing method – that would have saved me a lot of headache. However, the mistakes I made in this project taught me how important it is to make sketches of projects before starting to build.

These days, I always make sure to sketch out my designs before starting any build, in order to identify and address any potential design issues beforehand.