Hello,
I want to know is there is any method through which I can have the position feedback from servo motor? without modifying the servo.
I want to find the error between required angle and actual angel servo had moved.
I am working on hexapod using 18 servo motors and feedback for accurate movement.
Looking for any help.
I have HS485.I am not using Arduino or any other servo controller as we are not allow to use any already built kits or servo controllers. In simples words I have to build my own servo controller system. From last 2weak I am not making any progress due to feedback thing.
HELP PLZ 
one way would be to use servos that offer feedback. The other option is to modify your servos or use an external pot on the joint so that can read the joint angle. those values can then be used to accomplish your goal.?
As innerbreed indicated, there really is no way to get feedback from a normal R/C servo. There are three wires:
voltage and ground and signal. The signal wire is input only (no values are sent from the servo). You would need a smart servo: robotshop.com/en/smart-servo-motors.html