I thought it was about time to make an update about the MorpHex robot.
The main challenge with MKI was that it wasn’t able to roll in a straight line of path, only in a curved direction. I believe the main reason was the constrained motion of the upper sphere sections.
Having only one DOF (degree of freedom), or only one servo motor for each of the six upper sections made it very challenging.
The challenge was to make the motors fit inside the upper section without getting in conflict with the electronics. Compared to the leg section, the femur and tibia sections are mounted very different.
One advantage is that the servos in the upper section draw very little energy when holding the ball shape. To make enough space for the upper sections I also had to make new leg sections.