Sensor/Control Surface Fault Detection and Reconfiguration using Fuzzy Logic

In the aircraft flight control systems, a quick detection of the faults, that occur in actuators, control surfaces or sensors, is necessary. In this paper, sensor fault detection and reconfiguration is performed using Kalman filter by estimating the states of the plant and comparing them with respective measured values from the sensors. Sensor fault detection and reconfiguration is carried out using non-model-based fuzzy logic technique. Control surface fault detection and reconfiguration is carried out by identifying the elements of control distribution matrix using extended Kalman filter and fuzzy logic. In estimating the factor of effectiveness of the control surface using fuzzy logic, different implication methods such as Mamadani's minimum, Larsen's product, bounded product and drastic product have been used and a comparison is made.Defence Science Journal, 2010, 60(1), pp.76-86, DOI:http://dx.doi.org/10.14429/dsj.60.11

Analysis of effect of wake vortices on air data sensors

An essential part of operational clearance of a new aircraft is to certify that it is safe to fly even when wake vortices generated by another aircraft are encountered. For certification, it must be demonstrated that the aircraft can safely cross the wake at a certain separation distance. When the wake is encountered, air data sensors that measure the directional of airflow in terms of Angle of Attack (AOA / Alpha), Angle of Side Slip (AOSS / Beta / SSA) and pressures (Total and Static Pressure) show large fluctuations. The ADS measurements are used for feedback to the fly-by-wire control laws.These large and rapid fluctuations in the ADS signals affects the commands generated by the fly-by-wire control laws and in turn results in generating high loads on the aircraft. Therefore, before actual flight tests it is necessary to predict the behaviour of Air Data System (ADS) on encountering wake. Appropriate wake encounter protection features should be incorporated in the ADS algorithms. The behaviour of the ADS including the wake protection features during wake must be cleared in a simulation environment. The simulation environment for wake analysis, behaviour of the ADS measurements with and without wake protection features are presented in this paper for a generic high performance aircraft. Paper also briefly presents the wake protection features incorporated in the ADS algorithms

Functional level data acquisition requirement specification formulation for embedded systems: challenges, experiences and guidelines

94-105With the advancement in technology, many features of the large scale application systems are being embedded and miniaturized. This has led to investment of significant efforts on testing and verification of the developed embedded system. The data / signals acquired at intermediate stages of the system aids in analysis and debugging in accelerated manner. This article presents some guidelines for formulating the data acquisition / test points requirements of the core functional module (algorithms) and relevant aspects which are required to be considered during the development to cater for testing, evaluation and subsequent expansion or up-gradation of the system. The guidelines are proposed based on the experience gained over a period of time while working on safety critical embedded systems. The relevant experiences are also shared with the help of a few illustrative examples

Analytical Structures of Fuzzy PI Controllers with Multifuzzy Sets under Various T-norms, T-conorms, and Inference Methods (Invited Paper)

This paper deals with derivation of analytical structures of fuzzy PI controllers consisting of N>=3 number of triangular input fuzzy sets and 2N-1 number of trapezoidal output fuzzy sets on the universe of discourse of input and output variables, respectively, linear control rules, different T-norms, different T-conorms, different inference methods, and center of area defuzzification method. Properties of such fuzzy PI controllers are investigated. Simulation results are included to demonstrate the influence of the parameters of fuzzy PI controllers on the their performance. (c) Yang's Scientific Research Institute, LLC. All rights reserved

Simplest Fuzzy PI Controllers under Various Defuzzification Methods

This paper deals with the simplest fuzzy PI controllers under various defuzzification methods. The various simplest fuzzy PI controllers consist of two triangular input fuzzy sets and three triangular output fuzzy sets on the universe of discourse of input and output variables, respectively, linear control rules, intersection T-norm, Lukasiewicz and Zadeh OR T-conorms, and any valid inference methods and defuzzification methods. Properties of fuzzy PI controllers under various defuzzification methods are investigated through Simulation. Further, simulation results are included to demonstrate the influence defuzzification methods on the performance of the fuzzy PI controllers. Copyright c 20032005 Yang's Scientific Research Institute, LLC. All rights reserved. Index Terms--- Fuzzy control, PI control, defuzzifciation

The influence of the substrate and the substrate temperature on the crystallinity of tin films

Thin films of tin were prepared on various substrates (NaCl, KCl, KBr and KI) and at various substrate temperatures (28–90°C) and were studied using transmission electron microscopy and selected area electron diffraction techniques. To determine the dependence on cleanness, tin was deposited on single-crystal surfaces prepared by vacuum cleaving. Films were prepared on substrate surfaces to which a parallel d.c. electric field (0-1000 Vcm-1) was applied. It was observed that the crystallites of tin films deposited on KBr were more preferentially oriented than those deposited on NaCl, KCl or KI. The effects of vacuum cleaving and of d.c. electric fields are discussed

Whisker growth of di-substituted symmetric ureas

Experiments have been carried out at different temperatures and concentrations to grow whiskers of di-substituted symmetric ureas on mica and glass substrates using absolute alcohol as the solvent. It is conjectured that whisker growth takes place only if there is a slow rate of evaporation at constant temperature and as long as the effects of viscosity and surface tension are negligible

Whisker growth in natural graphite

This article does not have an abstract

Effect of temperature and pressure on the thermal oxidation behaviour of β-Sn films

Room temperature grown β-Sn films were thermally oxidised for 2 hours at various temperatures up to 200°C both in air and in vacuum. Only above about 130°C is α-SnO oxide formed; below 130°C amorphous oxide growth occurs. No higher oxide growth occurs in air. In vacuum, the growth morphology of α-SnO is different (whisker growth). A surprising result-the growth of a higher oxide at reduced oxygen partial pressure-was noted