Why does the robot have articulated legs? It is going to be very complicated to calculate what is going on and getting the thing to balance, plus you end up with a lot of weight.
Why not just have vertical air jets in the corners to raise the robot off the ground, then horizontal thrusters to move around.
There was a device called the "flying beadstead" it used one central jet engine for the main lift, I am not sure how they stabilised it.