Experimental Development of a Health Monitoring Method for Electro-Mechanical Actuators of Flight Control Primary Surfaces in More Electric Aircrafts

This paper presents a health monitoring approach for Electro-Mechanical Actuators (EMA). We define four different indicators to continuously evaluate the health state of the system. The four indicators are computed by leveraging the output from a Statistical Process Monitoring (SPM) method based on multivariate statistics, such as the Hotelling's T2 statistic and the Q statistic. SPM approaches give a dichotomous answer, i.e. the presence/absence of a fault. In this work, we propose four ways to compute a continuous indicator starting from the discrete SPM output, that is better suited for health monitoring. We test the approach using a dataset collected from a large experimental campaign on a 1:1 scale EMA for primary flight controls of small aircrafts, that led to EMA failure. Results show the effectiveness of the method

Sviluppo di un Materiale Innovativo da Granuli di Pneumatici Usati per Applicazioni Acustiche

Il lavoro si pone l’obiettivo di studiare una possibile forma di valorizzazione dei pneumatici fuori uso, favorendo il recupero di materia. Oggetto del presente lavoro è infatti lo studio di nuovi materiali fonoisolanti, prodotti con granuli di pneumatici usati (in seguito abbreviati con “PG”); si sono in particolare investigate le proprietà acustiche e meccaniche di questi materiali, al fine di valutare le effettive prestazioni raggiungibili. L’interesse per questo tipo di materiali è dimostrato in letteratura da numerosi Autori, unitamente alla fattibilità tecnica di validi processi industriali per questi materiali, e alla loro commerciabilità

Proprietà termofisiche di pannelli fonoassorbenti e trasparenti per barriere antirumore

La possibilità di coniugare, in un’unica soluzione costruttiva, delle buone prestazioni di assorbimento delle onde sonore con proprietà di trasparenza ottica si rivela importante in diverse applicazioni. Il contenimento dell’impatto visivo delle opere antirumore per infrastrutture di trasporto rappresenta infatti uno dei principali requisiti richiesti in fase di progettazione, sia in termini di sicurezza e comfort degli utenti dell’infrastruttura, sia in termini di “accettabilità” dell’opera da parte di coloro che vivono nell’ambiente circostante; l’impiego di materiali trasparenti è una delle soluzioni più comunemente adottate a questo scopo. D’altra parte, l’efficacia di un’opera antirumore può essere ridotta in presenza di superfici scarsamente fonoassorbenti e di riflessioni multiple. Il lavoro si propone di investigare, teoricamente e sperimentalmente, la realizzabilità tecnica di pannelli fonoassorbenti trasparenti, basati sull’impiego di lastre micro-perforate accoppiate ad intercapedini d’aria. Si sono considerate sorgenti di rumore a banda larga, in particolare le infrastrutture di trasporto su strada, optando quindi per configurazioni a più lastre, che consentono un significativo incremento delle prestazioni in un ampio range di frequenze. Oltre ad una breve disamina del modello teorico usato per la previsione delle prestazioni acustiche, sono riportati i risultati delle prove sperimentali condotte in condizioni di incidenza normale (mediante tubo di impedenza) e diffusa (in camera riverberante). Si è osservato un buon accordo tra il modello teorico e i dati sperimentali, che ha consentito un’ottimizzazione dei principali parametri geometrici che governano le prestazioni acustiche del pannello

Electromechanical Actuation for Morphing Winglets

As a key enabler for future aviation technology, the use of servo electromechanical actuation offers new opportunities to transition innovative structural concepts, such as biomimicry morphing structures, from basic research to new commercial aircraft applications. In this paper, the authors address actuator integration aspects of a wing shape-changing flight surface capable of adaptively enhancing aircraft aerodynamic performance and reducing critical wing structural loads. The research was collocated within the Clean Sky 2 Regional Aircraft Demonstration Platform (IADP) and aimed at developing an adaptive winglet concept for green regional aircraft. Finite Element-based tools were employed for the structural design of the adaptive device characterized by two independent movable tabs completely integrated with a linear direct-drive actuation. The structural design process was addressed in compliance with the airworthiness needs posed by the implementation of regional airplanes. Such a load control system requires very demanding actuation performance and sufficient operational reliability to operate on the applicable flight load envelope. These requirements were met by a very compact direct-drive actuator design in which the ball recirculation device was integrated within the screw shaft. Focus was also given to the power-off electric brake necessary to block the structure in a certain position and dynamically brake the moveable surface to follow a certain command position during operation. Both the winglet layout static and dynamic robustness were verified by means of linear stress computations at the most critical conditions and normal mode analyses, respectively, with and without including the integrated actuator system

Power absorption optimisation in electromechanical primary flight actuators via control laws design

This paper deals with the design of optimal control laws for an electromechanical actuator used for primary flight controls. The reference actuator, essentially composed of a brushless DC motor coupled with a low-pitch ball-screw, is controlled is by two nested loops, on motor current and output position respectively. A basic structure of the actuator regulators is preliminarily defined by using a detailed model of the actuator, and then verified through experiments. Starting from this basic design, an optimisation of the regulators is performed by applying the LQR technique. Once linearized the detailed model of the actuator, different versions of optimal control laws are obtained by varying the structure of the optimisation cost function. The actuator responses with “tracking-oriented” optimisations (more focused on the tracking error minimisation) and “power-oriented” optimisations (more driven towards the current absorption reduction) are finally compared, highlighting and discussing advantages and drawbacks of the two approache

Development and Experimental Testing of a Health Monitoring System of Electro-Mechanical Actuators for Small Airplanes

This paper reports the preliminary results of the REPRISE (Reliable Electromechanical actuator for PRImary SurfacE with health monitoring) project, which aims to design a novel Electro-Mechanical Actuator (EMA) to be used on primary flight surfaces of small aircrafts. An important element of the actuator control system is a Health Monitoring (HM) module. This component is an algorithm able to detect anomalies in the device even if there is no evident loss of ability in pursuing its main function (position tracking). In particular, the project aim is to identify any degradation in the mechanical transmission elements, the ballscrew and other components such as bearings. Moreover, it is strongly advisable that the HM algorithm is based on a feature whose value can be easily computed and monitored during the actuator life. In this work, a large experimental activity has been carried out with the purpose of bringing the actuator close to failure, by progressive fault injection in overload operating conditions. A feature named Σ, that is, the mean of the RMS of the three phase currents (the input to the electric motor), is proposed as a parameter for HM. The effectiveness of this parameter in detecting the mechanical transmission degradation is experimentally tested. The degradation has been confirmed by visual inspection and screw thread profile measurements. In spite of this, the actuator is still able to perform position tracking in an effective way

Condition Monitoring of Electro-Mechanical Actuators for Aerospace Using Batch Change Detection Algorithms

This paper proposes the use of a change detection algorithm to monitor the degradation of mechanical components of Electro-Mechanical Actuators (EMA) employed in the aerospace industry. Contrary to the standard on-line application of change detection methods, the presented approach can be applied in a batch mode, leveraging on the knowledge of when the data were collected. The methodology is applied to data measured during an endurance test campaign on a real EMA employed in aerospace, by means of a developed test bench, progressively bringing the EMA to failure. Three rationales for building an indicator of degradation are tested. Results show how the method is able to assess the degradation of the actuator over time, constituting a first step towards a condition monitoring solution for the more-electric-aircraft of the future