New asymmetry monitoring techniques: Effects on attitude control

Borello, Lorenzo; Villero, Giuseppe; Vedova, Matteo Davide Lorenzo Dalla

doi:10.1016/j.ast.2009.07.006

Cited by 21 publications

(28 citation statements)

References 3 publications

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“…The authors proposed in previous works [6,[18][19][20][21] several simplified models intended to modify the two gains formulation (1), in order to account for pressure saturation, leakages and water hammer. Among those, the C-type models introduce a pressure saturation downstream the Flow Gain contribution.…”

Section: Previous Simplified Servovalve Modelsmentioning

confidence: 99%

“…The simulations shown in Figures 7 to 9 represent the dynamic response of the aforementioned actuator to a combination of position controls (Com), external loads (FR) and variations in the hydraulic supply pressure (PSR), for the different models of the second stage sliding spool valve. The sequence of input has been defined to appropriately highlight the performance of the proposed fluid-dynamic models and their effect on the dynamic behaviour of the simulation test bench [6,[18][19][20][21]. The dynamic response of the full actuator in combination with the HF model of the spool valve is reported in Figure 7, to be taken as reference for the comparison with the simplified models.…”

Section: Fig 6 Block Diagram Of the Simulated Test Benchmentioning

confidence: 99%

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Proposal of a new simplified fluid dynamic model for aerospace servovalves

Vedova

Berri

2019

MATEC Web Conf.

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Highly detailed computer models are required for design and development of modern flight control systems, capable of emulating with high accuracy the behaviour of on-board equipment. At the same time, different simplified models are needed, specifically intended for operations such as the optimization of preliminary design and the development of diagnostic or prognostic strategies. These simplified models are required to combine sufficient levels of accuracy and reliability with reduced computational costs, to minimize the computational burden associated with prognostic and optimization algorithms. In this work, we focus on electro-hydraulic actuators, since they are critical subsystems in terms of safety and availability of the aircraft. Advanced monitoring and prognostic algorithms require new numerical models, combining an acceptable computational effort with a satisfying ability to simulate their performance and dynamics. To this purpose, this paper proposes a new simplified numerical model of the servovalve fluid-dynamic behaviour. This numerical algorithm, based on a very compact semi-empirical formulation, is intended to take into account in a simplified but sufficiently accurate way several typical effects related to the SV spool geometry and the operating conditions. To evaluate the approximations introduced by this model into a system-level simulation, it has been integrated into a dedicated numerical model simulating a simple electrohydraulic on-board actuator, and compared with a higher fidelity servovalve model.

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Section: Previous Simplified Servovalve Modelsmentioning

confidence: 99%

Section: Fig 6 Block Diagram Of the Simulated Test Benchmentioning

confidence: 99%

Proposal of a new simplified fluid dynamic model for aerospace servovalves

Vedova

Berri

2019

MATEC Web Conf.

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“…For this reason, adequate monitoring is necessary [12]. The nozzle is held by a ring of alternate layers of molded elastomer and spherically formed sheet metals.…”

Section: Nonlinearity In Electro Hydraulic Actuator Systemmentioning

confidence: 99%

Nonlinearities in Control Description and Design of an Electro Hydraulic Actuator for Flexible Nozzle Thrust Vector Control

Nauparac¹,

Pršić

Miloš

2018

Actuators

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This paper presents all the significant nonlinearities that exist in the description of an electro hydraulic actuator for flexible nozzle thrust vector control. Starting from practical possibilities of the theory of a nonlinear system (which are based on the analyses of one nonlinearity or one equivalent nonlinearity in the proximity of the linear description of an actuator), this paper explores the possibilities of additional analyses of a nonlinear electro hydraulic actuator for flexible nozzle thrust vector control. These explored possibilities can provide information that is useful for the design of the control algorithm, as well as for the general design of a flexible nozzle and actuator system.

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“…The EMA Dynamical Model block simulates the mechanical effects within the motor and the transmission, by means of a single degree of freedom MCK model. Additionally, this model accounts for several non-linear effects that characterize the dynamic response of the mechanical system, such as dry friction [23,24], backlash [25], and mechanical end-stops [26].…”

mentioning

confidence: 99%

“…accounts for several non-linear effects that characterize the dynamic response of the mechanical system, such as dry friction [23,24], backlash [25], and mechanical end-stops [26]. 4.…”

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confidence: 99%

Model-Based Fault Detection and Identification for Prognostics of Electromechanical Actuators Using Genetic Algorithms

et al. 2019

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Traditional hydraulic servomechanisms for aircraft control surfaces are being gradually replaced by newer technologies, such as Electro-Mechanical Actuators (EMAs). Since field data about reliability of EMAs are not available due to their recent adoption, their failure modes are not fully understood yet; therefore, an effective prognostic tool could help detect incipient failures of the flight control system, in order to properly schedule maintenance interventions and replacement of the actuators. A twofold benefit would be achieved: Safety would be improved by avoiding the aircraft to fly with damaged components, and replacement of still functional components would be prevented, reducing maintenance costs. However, EMA prognostic presents a challenge due to the complexity and to the multi-disciplinary nature of the monitored systems. We propose a model-based fault detection and isolation (FDI) method, employing a Genetic Algorithm (GA) to identify failure precursors before the performance of the system starts being compromised. Four different failure modes are considered: dry friction, backlash, partial coil short circuit, and controller gain drift. The method presented in this work is able to deal with the challenge leveraging the system design knowledge in a more effective way than data-driven strategies, and requires less experimental data. To test the proposed tool, a simulated test rig was developed. Two numerical models of the EMA were implemented with different level of detail: A high fidelity model provided the data of the faulty actuator to be analyzed, while a simpler one, computationally lighter but accurate enough to simulate the considered fault modes, was executed iteratively by the GA. The results showed good robustness and precision, allowing the early identification of a system malfunctioning with few false positives or missed failures.Aerospace 2019, 6, 94 2 of 15 occurrence of a failure before the scheduled substitution of the interested system. Monitoring the behavior of an actuator could enable to detect the early signs of different progressive faults, in order to timely correct them. If a tool would be available with a high grade of robustness to isolate those incipient faults, most failure modes of the flight control system could be identified before they start affecting the performance of the system in terms of dynamical response, stability, stall force, or positioning accuracy. The discipline aimed to this purpose is called Prognostics and Health Management (PHM) (as reported in [1]). The application of PHM strategies involves the analysis of functional parameters of the system in form of electrical signals: for this reason, the use of electrical actuators someway represents an advantage, because no conversion of the signals (and therefore no additional sensors) is needed. Due to the complexity and to the multi-disciplinary nature of the monitored systems, the FDI task on EMA systems is particularly challenging, since several failure modes interact and an acceptable accuracy is hardly ac...

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New asymmetry monitoring techniques: Effects on attitude control

Cited by 21 publications

References 3 publications

Proposal of a new simplified fluid dynamic model for aerospace servovalves

Proposal of a new simplified fluid dynamic model for aerospace servovalves

Nonlinearities in Control Description and Design of an Electro Hydraulic Actuator for Flexible Nozzle Thrust Vector Control

Model-Based Fault Detection and Identification for Prognostics of Electromechanical Actuators Using Genetic Algorithms

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