A force-feel system is implemented by mechanically coupling a
servo-actuator to and in parallel with a flight control system. The
servo-actuator consists of an electric motor, a gearing device, and a
clutch. A commanded cockpit-flight-controller position is achieved by
pilot actuation of a trim-switch. The position of the
cockpit-flight-controller is compared with the commanded position to form
a first error which is processed by a shaping function to correlate the
first error with a commanded force at the cockpit-flight-controller. The
commanded force on the cockpit-flight-controller provides centering
forces and improved control feel for the pilot. In an embodiment, the
force-feel system is used as the basic element of stability augmentation
system (SAS). The SAS provides a stabilization signal that is compared
with the commanded position to form a second error signal. The first
error is summed with the second error for processing by the shaping
function.