Proposed solution for torque calculation. Please Check.

Hi!
I have a proposed solution but I'm not sure if it's right. I first did an analysis with the shank/lower leg given the angular velocity and acceleration of the shank at a certain time. I can draw free body diagrams from where I can generate the free body equations according to Newton's 2nd Law (please refer to the figures I've provided). From there, I can compute for the reactions at the knee joint by summing the forces along x and along y. I can now use these reactions to get the torque about the hip joint.

You see that I isolated the shank first assuming that the knee joint is fixed. Did I made the right assumption?

[IMG] Bipedal Robot Design

[IMG] Robot Leg
[IMG] Shank Free Body diagram
[IMG] Thigh Free Body Diagram
[IMG] Equation for Angular Acceleration
[IMG] Solving for Ax
[IMG] Solving for Ay
[IMG] Solving for the torque