An Attiny85 IR Biped Robot

Although wheeled robots would be better for beginners I wanted to build a legged robot. Mostly because there were no continuous motors in reach and my attempt to modify a servo failed miserably.

One of the simplest solutions is a biped robot that moves as it shifts its weight. Two servos are needed for the feet and another two to move the legs to go forward or backwards. It is boring to just make the robot walk until the batteries are dead. So I decided to use infrared to receive commands.

The whole thing would be way too easy if you could just plug the servos into an Arduino. A small 90ct Attiny85 chip has 5 (actually up to 6) programmable pins which is enough for the project. There is a nice tutorial about how to program the Attiny over an Arduino:

http://hlt.media.mit.edu/?p=1695

The real problem was finding libraries for servos and infrared:

http://forum.arduino.cc/index.php/topic,17965.0.html

http://www.cunningturtle.com/attiny4585-servo-library/

The infrared sketch works fine with my TV remote so I only had to change the codes.

On the hardware side I used aluminum and a lot of glue. The feet have rubber soles to prevent the robot from ruining the furniture. A prototyping PCB was cut in half to connect the few components. Four turnigy 1800A servos are running well with the 3.7V battery, there are no clocks or voltage regulators. The Attiny itself is not soldered in, it can be taken away easily for programming.

I would say the project was successful although I did not have the time to program it well (making turns is still difficult). The solution is also very cheap because of the small microcontroller. The only relatively expensive thing is an Arduino for programming.