Diego – the humanoid biped

One of my long time favorite topics in robotics is visual servoing. In order to be able to do this, my robot needed fairly sophisticated arms and hands. Each of the old hands had 2 degrees of freedom: one in the shoulder and another in the elbow.  The new construction sports 5 DOFs: two in the shoulder and one in the elbow, wrist and hand.

The upper three servos are regular sized Hitec HS-475HB, while the lower two  (wrist and hand) are micro sized Hitec HS-85BB. The frame of the arm is built of Lynxmotion Servo Erector Set elements, just like the legs. The hand is a gripper device produced by Robix and sold by Lynxmotion.

After the construction was completed, I wanted to test the hand’s precision. I connected the arm servos to the Roboard unit and sent a series of pre-programmed movements to grab a small red ball.

This worked out quite well as you can see it in the above video, which encouraged me to continue with my visual servoing ambitions.

After an epic night of mechanical work, I finally added Diego’s head and arms, thus making him a fully assembled humanoid biped:

Each arm has 2 degrees of freedom so far. I intend to add at least one more DOF in the shoulder and some kind of a gripper as the hand (note exactly sure yet which kind).  The shoulder DOF is a full sized Hitec servo (HS475), while the elbow joint is a micro servo (HS85).  The design of the head might be changed too in the future. It has pan & tilt capabilities (2 DOFs). This will enable the cameras (to be installed) to get an all around image. I already ordered two nano on-chip cameras (Toshiba TCM8230MD), which I will soon add to Diego.

The next step in development should be to cover the frame structure of the robot with some kind of lightweight material. Read more on this in my next post.