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In this paper, an accurate model of an airbrake electro-hydraulic smart actuator is obtained by physical considerations, and then different control strategies (variable-gain proportional control, PT 1 control with switching integrator, and second order sub-optimal sliding mode control) are proposed and analyzed. This application is innovative in the avionic field, and is one of the first attempts to realize a fly-by-wire system for airbrakes, oriented to its immediate employment and installation on current aircraft. The project was carried on with the participation of the Italian Ministry of Defense, and was commissioned to MAG, a leading provider of integrated systems and aviation services for aerospace.

The protection of the electrical plant, equipment and components in aerospace applications represents a topic of advanced researches. In the last years, in particular, great efforts have been focused on the problem of the arc-fault detection. The impressive advancement of the electronic devices has been exploited. As well known, in many cases the arcs are not detected by the conventional overcurrent breakers, despite their effects can be as serious as those produced by a short-circuit, since they may cause fires on board the aircrafts. Arc-fault detection requires recognizing the arc signature contained in the current waveform. For this reason, an inescapable choice to face this problem is to adopt proper digital signal processing techniques. The detection reliability strongly depends on the criteria adopted in order to discriminate the arcing condition from other possible artefacts, due for example to normal electrical transients. In a previous work, the authors have proposed a technique based on the estimation of the energy which may be related to the arcing activity. It has been proven that it allows to establish a solid decision-making process for the parallel arc detection. In this paper the aspects related to the practical implementation of the proposed method are faced, with particular care to the impact of the unavoidable measurements uncertainties on the reliability of the method. This analysis has led to the development of an advanced prototype of a low-cost single-chip parallel arc fault detector, which can be employed to develop a very attractive AFCB (Arc Fault Circuit Breaker). A deep experimental activity has been hence carried out in laboratory. The well-recognized guillotine test has been used in order to assess the actual behaviour of the developed device

Arc faults are phenomena associated to unwanted electric discharge between two or more conductors. Since energy related to an arc may fuse the conducting material, very often an arc is responsible for a fire. This condition is very critical in aerospace environment, where a fire may produce catastrophic effects. For this reason, many efforts have been produced in order to develop a reliable method for arc detection. The main problem in facing this aim is represented by the intermittent and random nature of an arc in an aircraft, due to the effects of the in-flight vibrations. A continuous monitoring of the electric system is mandatory, and a smart measurement system is also required. In particular, different identification methods have been proposed, based on Kalman filter, neural network, fuzzy logic, etc., that usually require a complex learning activity which could be not exhaustive. In this paper a novel approach to the arc identification is presented, that is based on the evaluation of two physical parameters: rate of concurrency of current spikes and their specific energy. By combining these two parameters is possible to detect the arc and estimate its severity. The method has been tested using a standardized emulation system under different conditions and the experimental results clearly show its effectiveness