Question - What is the force balance principle?
Answer -
Principle of force balance: a controller that produces a torque-opposed output signal. The input force is applied to the beam moving reference bellows. This breaks the backpressure of the nozzle.
The backpressure of the nozzle is felt by the rotating bellows that support the projector. The baffle movement for full-scale output is much less than 0.002.