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Boeing B-777: Fly-by-Wire Flight Controls
Published in Cary R. Spitzer, Uma Ferrell, Thomas Ferrell, Digital Avionics Handbook, 2017
The primary surface actuators on the 777 are replaced in the same manner as on conventional airplanes. The difference is how they are adjusted. Each elevator, aileron, flaperon, and rudder actuator has what is referred to as a null adjust transducer, which is rotated by the mechanic until the actuator is positioned correctly. For example, when a rudder actuator is replaced, all hydraulic systems are depressurized except for the one that supplies power to the actuator that has just been replaced. The null adjust transducer is then adjusted until the rudder surface aligns itself with a mark on the empennage, showing that the actuator has centered the rudder correctly.
X-29 flight control system: lessons learned
Published in Mark B. Tischler, Advances in Aircraft Flight Control, 2018
Robert Clarke, John J. Burken, John T. Bosworth, JEffrey E. Bauer
The vertical fin excited the roll rate gyro and, through high-gain feedback, caused the flaperon actuators to attempt to track this high-frequency signal. Flight tests showed that an unexpected hydraulic system problem resulted from this flaperon command. During a 360° full stick aileron roll, the left outboard flaperon (LOF) hydraulic logic indicator showed a failure of the control logic for this actuator. The most probable explanation was that a flow restriction existed in the hydraulic lines driving the LOF and that this restriction showed up when large, high-frequency demands were placed on the actuator. Postflight analysis also showed that the measured LOF rates were approximately 7 to 8 degs–1 lower than for the right outboard flaperon.
Explicit reference governor for linear systems
Published in International Journal of Control, 2018
Emanuele Garone, Marco Nicotra, Lorenzo Ntogramatzidis
This example applies the proposed method to the flight path control of an F-16 aircraft. The aircraft is open-loop unstable and can become closed-loop unstable in response to large command changes due to actuator saturation. The linearised system dynamics are described by the following state-space model (Sobel & Shapiro, 2013): where The state vector x = [γ, q, α, δe, δf]T comprises the flight path angle, the pitch rate, the angle of attack, the elevator deflection and the flaperon deflection. The input vector v = [θc, γc]T consists of the desired pitch angle θC = γC + αC and the desired flight path angle γC. The components of the output vector on which the constraints are imposed, , represent, respectively, the angle of attack, the elevator deflection, the flaperon deflection, the elevator deflection rate and the flaperon deflection rate. The system is subject to the set of linear constraints