I'm designing the actuation of a throttle for an engine.I thought to put a servo to move the plate.
Very interesting are the smart servos used for the robotics(for example dynamixel AX-12W http://www.trossenrobotics.com/p/ax-12w-dynamixel-robot-servo.aspx).
I need that when I push the shutdown button(for emergency) the plate of the throttle returns to the idle position.The throttle already has two return springs.
I have some ideas to calculate the right reduction to move the plate when the servo is powered on but where I can find the torque value that i need to rotate the servo when it's powered off?
If I knew that value I'll know the right spring constant.