Team Cookie Monsters




After seeing how much work a six legged robot would be, Simon began to realise the advantages of just two legs and so, Digit was born. The design was basic with just two servos, one to tilt the robot, thus moving his centre of gravity over one foot or the other, and the other to push the legs backwards and forwards.

The basic robot was built in an evening, then came the refinements. Stiffening his legs, making his feet bigger, and reducing flop in the joints.

Fortunately, Simon had already had some experience programming PIC's to control servos, noteable with Granny Weatherwax's head servo's. So it wasn't long before Digit was limping along. However Digit just wasn't fast enough for Simon's liking, so he stored him away and began work on Digit Evo 2.

Digit Evo 2 took a considerable length of time to build, although far more sophisticated than Digit Evo 1, he was a lot more wobbly on his little legs, and considerably more complicated to get walking initially. Simon had a lot of fun working on him though, but in the end he decided Evo 2 wasn't going to be finished in time for the 2006 UK Robotic Games. So he dusted off the original Digit and was pleasently surprised to find that with just a little more work Digit Evo 1 was good enough to enter in to the event.

The main change that helped Evo 1 achieve his event capability status was in mounting the batteries, and radio top and centre to help balance the centre of gravity. After sorting out the tables in the software that told the servo's what position they had to be and when, Simon decided the chassis needed to be stiffer.

This being just a few days before the event was a problem since it changed the centre of gravity again, which meant re-writing all the tables. However after extensive fiddling and re-itteration of the code, Digit Evo 1 managed 3 metres in 27 second down on our kitchen floor, that time and distance equated to 2 mins 42 seconds over the 18 metres, which we were reasonably happy with, so we packed everything up ready for the event.


So on the 8th July 2006 we went along to the event in Corby, Northampton where Digit Evo 1 weighed in at 700 grams, and passed the tech check with flying colours. Leaving us free to check out the competitors, and watch the other competitions whilst we waited for our turn to take part. We were thrilled to win the Biped Walker event with Digit Evo 1 achieving a time of 1 minute 46 seconds, despite having some steering problems, as you can see from the look on Simon's face in the first photo.

Digit Evo 3 - Last year, Simon had the idea of creating a walker based on Digit that could be 3D printed with the brains of an Arduino Nano, which could be a suitable robot for schools to build for potential competitions in the future. Other than the arduino there are a couple of servo's and a battery holder which houses 4 x AA batteries and a small interface board to wire it all together. All that this Evo of Digit requires is some coding of the arduino to drive the servos in sequence to make him walk. With the possibility of using blue tooth to connect to android phones for control thus circumnavigating the need for a radio contril set.