Tested, dissimilar helicopter stability augmentation

Claim 2

A dissimilar, redundant stability augmentation system operable in a plurality of controlled attitude axes of an aircraft, comprising: a plurality of stability augmentation actuators each having a pair of electrical control inputs, each operable to provide a mechanical input to the corresponding one of said axes in response to the additive effects of signals applied to said pair of electrical control inputs thereof;

Claim 3

a plurality of analog amplifiers, one for each of said axes, each of said amplifiers being selectively connectable to one of the electrical inputs of the stability augmentation actuator of the corresponding axis; a digital computer system having analog inputs and having an analog output for each of said axes, each of said outputs being selectively connectable to the other of said electrical inputs of the stability augmentation actuator of the corresponding axis, said computer system comprising means for reading in analog input signals and for providing corresponding stability augmentation command signals to related ones of said analog outputs; a plurality of rate gyros, there being a pair of rate gyros corresponding to each of said attitude axes, one of the rate gyros of each pair having its output connected to the input of the amplifier of the corresponding axis of the aircraft, and the other rate gyro of each pair having its output connected to an analog input of said digital computer system; characterized by each of said rate gyros being responsive to a test signal input to provide a predetermined output signal when it is functioning properly, said digital computer system being connected to the test signal input of each of said gyros, said one rate gyro of each pair also being connected to an analog input of said digital computer system, said aircraft having means for providing preflight indication that the aircraft is stationary on the ground, said digital computer system comprising means operable in response to said preflight indication for providing a test signal to each of said gyros, for reading the test output of each of said gyros with said test signal applied thereto, and for providing a fault indication in the event that the test output of any one of said gyros differs from a permissible value by a predetermined amount, and operable in the absence of said preflight indication for comparing the output of one gyro in each pair with the output of the other gyro in such pair and providing a fault manifestation in response to the outputs of a pair differing by a predetermined amount.

Claim 4

a plurality of analog amplifiers, one for each of said axes, each of said amplifiers being selectively connectable to one of the electrical inputs of the stability augmentation actuator of the corresponding axis; a digital computer system having analog inputs and having an analog output for each of said axes, each of said outputs being selectively connectable to the other of said electrical inputs of the stability augmentation actuator of the corresponding axis, said computer system comprising means for reading in analog input signals and for providing corresponding stability augmentation command signals to related ones of said analog outputs; a plurality of rate gyros, there being a pair of rate gyros corresponding to each of said attitude axes, one of the rate gyros of each pair having its output connected to the input of the amplifier of the corresponding axis of the aircraft, and the other rate gyro of each pair having its output connected to an analog input of said digital computer system; characterized by each of said rate gyros being responsive to a test signal input to provide a predetermined output signal when it is functioning properly, said digital computer system being connected to the test signal input of each of said gyros, said one rate gyro of each pair also being connected to an analog input of said digital computer system, said aircraft having means for providing preflight indication that the aircraft is stationary on the ground, said digital computer system comprising means operable in response to said preflight indication for providing a test signal to each of said gyros, for reading the test output of each of said gyros with said test signal applied thereto, and for providing a fault indication in the event that the test output of any one of said gyros differs from a permissible value by a predetermined amount, and operable in the absence of said preflight indication for comparing the output of one gyro in each pair with the output of the other gyro in such pair and providing a fault manifestation in response to the outputs of a pair differing by a predetermined amount.

Claim 5

A stability augmentation system according to claim 1 further characterized by a feedback path from each electrical input of each of said stability augmentation actuators to said digital computer system, and said digital computer system comprising means for comparing the command signal provided to one electrical input of each actuator to the signal provided to the other electrical input of each actuator and for providing a fault indication in response to the signals provided to one of said actuators differing from each other by a predetermined amount.