Advice on robot leg design

[quarky]

Hi. I am with a team designing a tall humanoid robot. The total height to the shoulders will be 30 inches. The leg will be 9 inches from waist to knee, and 9 inches from knee to ankle. The robot will weigh close to 5.5kg when completed.

Here is the current design the mechanical engineers have come up with (electrical engineer here). We are looking for suggestions to improve the overall design, and pitfalls others have had when designing large robots. Thanks!

Below is a picture of the current design. There will be metal tubes bolted between the holes in the legs to add some strength.

[Gertlex]

What servos are you planning to use there?