davidbuckley.net
home  >  Ullr < Ajax > Libby 8 July 2023
Ajax - by David Buckley September 2022
Ajax is based on a Sainsmart Humanoid Robot kit which I purchased in 2017, it came with a game-controller/receiver and a controller which allowed set moves to be stored and replayed using the game-controller. There was no way to use the robot other than recording a series of moves and replaying them. Since I didn't want to play with a fighting robot the kit sat in a cupboard until September 2022 when I was persuaded by a friend to get it working.

To allow Ajax to power up from a stable position I rearranged the knee servos so Ajax could squat and sit on its heels and added some MDF spacers to compensate, I also added spacers in the arms and blocks in the knees to stop the knees bending the wrong way when powered down (the servos do not have any internal stops and can be rotated 360 degrees). The kit was supplied without a battery so I fitted a Ni-Mh 3700 mAh 6V 5 sub-C cell pack in the chest. I fitted a modified Arduino Mega 2560 STRONG on the back which is supplied through a 10A fuse for the servos and a 500mA fuse and diode for the electronics. I had to break a track to isolate the servos from the electronics and beef up the tracks to the servo connectors.

The software is based on the Bamduino's code, expanded to use the servo-library and incorporate Poses.
The desired range of movement for the limbs is scaled 0-9.
Unfortunately the servos are 'clever' and maintain their last commanded position and the only way of making them relax is to turn of the power so I fitted a 10A relay to do that.

The videos were taken as the software was developed, see Videos