Pilot-Induced Oscillation Prevention During the Aircraft Landing

The paper focuses on a manned aircraft landing control system. It is known that actuator level and rate limitations can cause pilot-induced oscillations. This phenomenon occurs during intensive pilot control in a closed-loop system under certain initiating conditions associated with both the influence of the external environment and changes in the system dynamics. Oscillations appear unintentionally and unexpectedly for the pilot, which jeopardizes flight safety. The study shows the possibility of preventing aircraft oscillations using the method of nonlinear correction of systems by sequential introduction of a pseudo-linear correcting device into the control loop, the phase-frequency characteristic of the device not depending on the amplitude of the input signal. The airplane-pilot closed-loop system for various parameters of the input signal is analyzed by calculating the generalized function of sensitivity and the excitation index. The results of the study are presented in the form of angle and the pitch rate time processes, and landing trajectories.

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Two Degree-of-Freedom Hysteresis Compensation for a Dynamic Mirror With Antagonistic Piezoelectric Stack Actuation

Volume 3: Nonlinear Estimation and Control; Optimization and Optimal Control; Piezoelectric Actuation and Nanoscale Control; Robotics and Manipulators; Sensing; System Identification (Estimation for Automotive Applications, Modeling, Therapeutic Control in Bio-Systems); Variable Structure/Sliding-Mode Control; Vehicles and Human Robotics; Vehicle Dynamics and Control; Vehicle Path Planning and Collision Avoidance; Vibrational and Mechanical Systems; Wind Energy Systems and Control ◽

10.1115/dscc2013-3869 ◽

2013 ◽

Cited By ~ 1

Author(s):

James A. Mynderse ◽

George T. C. Chiu

Keyword(s):

Input Signal ◽

Control Strategy ◽

Closed Loop ◽

Loop System ◽

Degree Of Freedom ◽

Closed Loop System ◽

Loop Control ◽

Hysteresis Compensation ◽

Hysteresis Control ◽

Two Degree Of Freedom

A methodology for designing a low-computation, high-bandwidth strategy for closed-loop control of a hysteretic system without a priori knowledge of the desired trajectory is presented. The resulting two degree-of-freedom hysteresis control strategy is applied to a dynamic mirror with antagonistic piezoelectric stack actuation. Hysteresis compensator is performed by a finite state machine switching polynomials for hysteresis inversion based on the input signal slope. Residual error after hysteresis compensation is corrected by an LQR feedback controller. Experimental results demonstrate effectiveness of the hysteresis compensator and closed-loop system under the proposed hysteresis control strategy. For the triangular input signal tested, the closed-loop system achieves a 91.5% reduction in hysteresis uncertainty with 60 kHz sample rate.

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Simulation of the effects of load on hydraulic servo actuators

SIMULATION ◽

10.1177/003754976901200309 ◽

1969 ◽

Vol 12 (3) ◽

pp. 145-151 ◽

Cited By ~ 1

Author(s):

Myron Glickman

Keyword(s):

Control System ◽

Closed Loop ◽

Block Diagram ◽

System Simulation ◽

Loop System ◽

General Description ◽

Control Loop ◽

Closed Loop System ◽

Servo Actuator ◽

Hydraulic Servo

Control system analysts are frequently called upon to include a hydraulic servo actuator as part of the loop in a complex closed-loop system simulation. This article presents a general description of several common types of hydraulic servo actuators and several methods for inclusion of the effects of load on the simulation of the actuator in the control loop. These methods are pre sented in block diagram form and are suitable for inclu sion in a larger simulation loop. The block diagrams themselves may be somewhat condensed and modified before inclusion in a larger simulation, but are presented here with all the details shown explicitly for clarity.

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