my first design is to use ball joints instead of u-joints, i'm so much confused if i will use pulleys or gear trains in my robot project. and i'm not sure if my servo would actually carry the weight. the socket part of joint is the one which is connected to the load and i pulled it over a double tackle pulley connected to a servo motor to reduce the load taken by the motor(pitch and yaw movement). i also have a problem computing torques required by the motor. and lastly, how can i connect a motor for a roll movement? Anyone please help.