I needed a simple robotic platform for an Arduino DOJO workshop organised by BeJug. I started out with a quadpod (8 to 12 servo’s) because I didn’t want the complexity of a hexapod (18+ servo’s). Once completed I started working on gathering information on the walking routine for the 8 servo powered quadpod.
It didn’t take long to discover the much simpler (3 servo’s only!) hexapod tripod configuration at pololu.com. Everything that follows is inspired on this simple hexabot from pololu.com.
I have 2 versions of this bot. If you really want to keep it simple and cheap you can go for the micro version using 3.5g servo’s. Options on that one are limited though because of the minimal weight it can carry.
If you want to experiment with more sensors I would go for the bigger 9g servo’s. It’s basically the same but using bigger servo’s. If you want to carry more load you’ll also nee stronger steel wire.
- 1x Arduino pro mini (the brains)
- 3x 3.5g servo (the muscles)
- 1x 3.3v bec OR 5v bec (OR none if you use a life or 1s lipo instead)
- 1x small 1-2s lipo of around 300mAh (OR life OR any other type of battery)
So you can skip step 1 and 2 from that tutorial. Instead I made a small pcb with a common power rail (+ and -) with 3x 3 pin headers to connect the servo’s to. The signal wires from the servo’s (often white wire) go directly to the corresponding arduino pins. In my case pins 10, 11 and 12 (change these pins in the sketch if you use different ones).
The servo’s are glued together using hot glue. Once together I glued them on the pcb with the arduino pro mini in front of the middle legs, center servo. This way I have the complete pcb underneath the center legs so I can attach the battery on the bottom of that plate at the middle of the spider. This thing needs to be balanced and the biggest weight we have is the lipo.
Once the legs are attached you’re good to go. Make sure not to force the servo’s. Use the sketch instead to center servo’s before putting the arms on with the legs. Make sure the legs are all the same length. Play with the position of the battery to balance everything.
- better steel wire (lhs)
- try on a single cell
- glue steel wire underneath the servo horns
- legs better cut and formed to equal size
- tweak amount of servo travel!