Topic
Describing function
About: Describing function is a research topic. Over the lifetime, 1742 publications have been published within this topic receiving 26702 citations.
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01 Oct 2018
TL;DR: The design of HOSIDF (Higher Order Sinusoidal Input Describing Functions) based Chebyshev structured compensator is dealt with in order to increase the disturbance attenuation performance of the system involving actuator saturation.
Abstract: Disturbance attenuation problem is considered as an important topic in control literature. This paper deals with the design of HOSIDF (Higher Order Sinusoidal Input Describing Functions) based Chebyshev structured compensator in order to increase the disturbance attenuation performance of the system involving actuator saturation. This study consists of the proposed compensator design in addition to ℋ ∞ dynamic output feedback controller that already exists in the system. The simulation studies are carried out with an active suspension system which is known as a benchmark problem in control literature. The improvement in disturbance attenuation performance of the closed loop system involving HOSIDF-based compensator is illustrated with time-domain and harmonic plots.
TL;DR: In this paper, the application of the concept of information-theory has been tried to assess the performance of the human operator in multi-loop tasks and it was learnt that with the knowledge of the internal dynamics of the operator, there is some hope to determine performance indices for manual control systems with the methods of the informationtheory.
TL;DR: Baranyi and Ladvanszky as discussed by the authors investigated the stability of a nonlinear, tuned amplifier with two resonators at the input and the output, using describing functions and complex analysis and matrix algebra.
Abstract: Stability of a nonlinear, tuned amplifier has been investigated based on the describing function method. On stability, this paper means global asymptotic stability. The tuned amplifier comprises a saturated amplifying device with feedback and two resonators, at the input and the output. Describing function method here means introduction of the two-port describing functions.,Describing function method is applied, extended for two ports. Results from complex analysis and matrix algebra are heavily used. The two resonators have identical resonant frequency and bandwidth. Instability is represented by non-vanishing output perturbation for zero-input perturbation. Applying a simple transistor model with saturation and feedback, stability is analyzed in the form of output voltage as a function of input voltage.,Two-port scattering and admittance describing functions have been introduced. At a certain input voltage amplitude, instability appears in the form of unwanted sidebands, then at a higher input voltage, instability disappears, in good agreement with experiments. The hand calculated stability limits are in good agreement with the computer analysis.,The paper is based on an early publication of the author (Baranyi and Ladvanszky, 1984). Here, the full material is presented, explained step by step, extended and revised. All neglections that were earlier made in the author’s paper have been avoided here. This paper has significant tutorial value as well.
17 Mar 2013
TL;DR: In this article, a novel dynamical modeling for series-parallel resonant converters under optimized modulation is presented, which is based on the sampled-data method, and the dynamic interaction between power circuit and the digital optimized modulation control unit is considered properly.
Abstract: The series-parallel resonant converter is one of the most popular topologies among resonant converters. In order to achieve a further reduction of transistor switching losses, an optimized modulation strategy was proposed and implemented full digitally. This yields zero-current switching on one full bridge leg and zero-voltage switching on the other leg. Costs of the optimized modulation are the increased complexities in modeling and controller design, because the state-of-the-art extended describing function method is not suitable anymore. In this contribution a novel dynamical modeling for series-parallel resonant converters under optimized modulation is presented, which is based on the sampled-data method. The dynamic interaction between power circuit and the digital optimized modulation control unit is considered properly. Duty-ratio-to-output-voltage small-signal behaviors predicted by the proposed model are verified by circuit simulation and experimental results.
TL;DR: In this paper, aeroelastic analysis of a missile control fin is performed considering backlash and dynamic stiffness of actuator. And the analysis shows that the aero-elastic characteristics are significantly dependent on the backlash and the dynamic stiffness.
Abstract: Nonlinear aeroelastic analyses of a missile control fin are performed considering backlash and dynamic stiffness of actuator. Doublet-Hybrid method is used for the calculation of subsonic unsteady aerodynamic forces, and aerodynamic forces are approximated by the minimum-state approximation. For nonlinear flutter analysis backlash is represented by a free-play and is linearized by using the describing function method. Also, dynamic stiffness is function of frequency and is calculated by solving equation of motion for actuator. The linear and nonlinear flutter analyses show that the aeroelastic characteristics are significantly dependent on the backlash and dynamic stiffness. From the nonlinear flutter analysis, various types of limit cycle oscillations are observed in a range of air speeds below the linear divergent flutter boundary. The nonlinear flutter characteristics and the nonlinear aeroelastic responses are also investigated in the time domain.