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Develop an obstacle detection system for Unmanned Aerial Vehicle (UAV) especially for small UAV is challenging. A robust system should be able to not only detect obstacles but the free region for the avoidance path as well. Besides, the configuration of the obstacles in the operating environment should never be disregard. In this paper, expansion cues from the detected feature points with the help of convex hull will be used to categorize the regions in the image frame. A micro LIDAR sensor is used as the initial detector of obstacle and queue for image capturing by the camera. Next, ORB algorithm is applied to find the obstacle regions and free space regions. This is done through the principal of object size changes and distance relationship in an image perspective. The proposed system was evaluated through series of experiments in a real environment which consist of different configuration of obstacles. The experiments show the proposed system was able to find the safe avoidance region regardless of the configuration of the obstacles in the operating environment. Keywords: Expansion cue; ORB; Feature points; Safe avoidance region

This paper presents a simple, and effective CFD modelling of a permeable thin symmetric, NACA 0008, 3D wing and airfoil at a Reynolds number of 3.45 × 105using the StarCCM+ software. The results are validated against wind tunnel aerodynamic balance data. The aerodynamic performance of both permeable wing and airfoil is presented in terms of lift, drag, lift to drag ratio, and moment coefficients by varying permeability values and permeable sections. The lift slopes show good agreement with analytical and experimental data. The results show a decrease in drag at low values of permeability which results in an increase in the lift to drag ratio up to 72% for permeable airfoil and 65% for the permeable wing. A strong effect of permeability and its location on the pitching moment coefficient is observed, opening up avenues for the control of stability through permeability.

Geometric and volumetric quantities are usually used to define the reference area for the prediction of aerodynamic coefficients of various aquatic mammals, airships and unmanned vehicle. However, reference area does not have a unique definition, especially for a hybrid buoyant aerial vehicle having hybrid lifting hull which resembles a Steller sea lion. The term square cube root of volume is traditionally used as reference area to nondimensionalize the aerodynamic forces for conventional as well as unconventional airships. Published experimental data are usually available for complete configuration at low speed and in nondimensionalized form. So, a generic model of an aircraft’s fuselage was first tested in a wind tunnel as a test case to first determine the lift force and then the influence of different choices of reference area on the lift. A hybrid lifting hull was numerically simulated for the prediction of lift as well as drag coefficients and their ratio. It was found that the volumetric term has undefined correlation with aerodynamic forces in both cases. Changes in aerodynamic coefficients are not prominent when using the wetted area as the reference area. Based on the predicted trends of aerodynamic coefficients and a deep literature survey, the projected planform area is proposed as the best option for reference area of a Steller sea lion as well as for hybrid lifting hull of a hybrid buoyant vehicle.

It is well-known that air transportation of passengers and goods is a large market in the world of aviation. Hybrid buoyant aerial vehicles have the potential to be candidates for such applications. This paper addresses the preliminary static stability analysis for hybrid buoyant aerial vehicles in which a novel concept of ballonet arrangement is applied. A study was performed to assess the suitability of commercial off-the-shelf software for this task. A generic geometric model was created to obtain the lift and drag characteristics of the aircraft and provide geometric parameters. These parameters were input into DATCOM, which was used to model the aerodynamic characteristics and to determine the stability and control derivatives for static analysis and airship performance enhancement. This study demonstrates that the aerodynamic and stability trends for low-speed airships can be obtained and analyzed using DATCOM.

For economic and ‘green’ transportation, the concept of hybrid buoyant aircraft has recently become a research focus in the aerospace community. In the present work, a methodology is proposed to aid in the conceptual design of such aircraft, powered by internal combustion engines with either liquid hydrogen or gasoline as a fuel. Special emphasis is given to the sequence of procedures to be adopted at the conceptual design level highlighting a step by step methodology for the achievement of system design targets with the help of a design example. The proposed design synthesis methodology has given a base line for further design work on such aircraft at a conceptual level. Moreover, it will assist to provide qualitative as well as quantitative data for other design concepts of such hybrid configurations being considered in the conceptual design phase.

It is well known that hydrogen has less undesirable exhaust emissions as compared with other types of liquid fuels. It can be used as an alternative fuel for a hybrid buoyant aircraft in which half of the gross takeoff weight is balanced by the aerostatic lift. In the present study, weight advantage of liquid hydrogen as an ideal fuel has been explored for its further utilization in such aircraft. Existing relationships for the estimation of zero lift drag of airship is discussed with special focus on the utilization of such analytical relationships for the aircraft whose fuselage resembles with the hull of an airship. Taking the analytical relationship of aircraft and airship design as a reference, existing relationships for estimation of power budget are systematically re-derived for defined constraints of rate of climb, maximum velocity and takeoff ground roll. It is perceived that when the propulsion sizing for liquid hydrogen is required, then the presented framework for estimation of its power budget will provide a starting point for the analysis. An example for estimation of the power requirement is also presented as a test case.

This paper introduces a smartphone-based classification system for an indoor environment of a walking person. The system relies only on smartphone inertial data and it can be considered as a smartphone-based aiding system for an indoor navigation. In addition, it does not need pre-installing of wireless network in the environment or heavily tuning process before the navigation run. Therefore, this system can be used as an aiding block where the person wants to localize himself in an indoor environment starting from known navigations point. This system categorizes person navigation in indoor environment into three types of classes: walking straight, turning right, and turning left. There is an ELM (Extreme Learning Machine)-Based neural network for deciding the class of the current navigation action. The evaluation measure shows that the best performance is obtained with the Radial Basis Function (RBF) as the activation function of the neural network. Also, the obtained accuracy rates up to 95%.

Wind Tunnel Testing on a subscaled model of a winged hybrid airship requires a faithful reproduction of all geometric details of actual airship. Due to huge volume of hull, geometrical parameters of such airships are quite different from that of an aircraft. In this article, a scheme for designing such models is described alongwith a review of different strategies available for manufacturing of its prototype wind tunnel model in IIUM low speed wind tunnel. Similar to aircrafts, major contributing factors for scaling, design and manufacturing of a subscaled model of hybrid airships are discussed. It is concluded that the required aerodynamic data will be the dictating factor for selection of the manufacturing method.

In the field of aviation it is well known that a vehicle’s stability and takeoff flight segment are critical. This issue becomes more critical for a hybrid aircraft which is concealed as an airship with huge volume of hull as compared with fuselage of a conventional aircraft. In the present work, stability issues of a generic model of airship and of a conceptual model of hybrid aircraft are discussed. Special emphasis is given for future sizing of empennages of IWHA-14, a hybrid aircraft concept proposed for Malaysian inter island transportation. Effect of gondola position on rotation angle for takeoff ground roll was analyzed and it was found that such configurations can meet the requirement of minimum roll angle.

WiFi indoor localization is regarded as the most promising reliable technology for indoor localization. Its concept is based on building fingerprint and training a ma-chine learning model on it, then using it for predicting the location based on the measured received signal strength RSS. One aspect of its vulnerability is its time vari-ant change due to the dynamical conditions in the environment and the access points APs. This was the most focus of the researchers in the last decades. However, minori-ty of them have considered the limitations of the existing benchmarking fingerprint in terms of lacking of support to realistic navigations runs when they are used for eval-uating indoor localization models. This article proposes a simple yet novel add-on to existing benchmarking fingerprint that assists in converting it from static fingerprint to consecutive training data with supportability to incremental learning and awareness of various characteristics of indoor navigation runs. The model was evaluated based on two benchmarking fingerprint and the generated incremental data were plotted with two levels of granularity one is corresponding to location and the other to place for referring to high resolution level and low resolution level.

Spherical mobile robot is a ball-shaped mobile robot that capable to move from one place to another to perform the desired tasks. The challenge for spherical mobile robot falls within control algorithm aspects, where it is nonlinear and highly under-actuated increases the difficulties to control its motion. In this paper, the potentiality of intelligent controller is explored to control the motion spherical mobile robot. An error driven Fuzzy Logic controller (FLC) which consist of modular of two Proportional-Derivative (PD) type FLC and a Proportional-Integral (PI) type FLC were designed and tested to control the position of the spherical mobile robot, angle of the rotation of the pendulum and the angular velocity of the spherical mobile robot, respectively. The performance of the controller was then optimized by tuning the input and output gain of the controller with Particle Swarm optimization (PSO) method. The performance of the robot without the controller and with optimized controller were compared and analysed. As a result, the performance of the system in the form of rise time and settling time of the robot to control its position managed to be reduced by 86% and 89% respectively with optimized PD-type. For PD-type FLC to control the rotation of the pendulum, it was capable to eliminate the overshoot and reduce it settling time by 35.5%. While the optimized PI-type FLC has managed to eliminate the steady state error and achieved it desired velocity setpoint in 1.2s. Lastly, all the designed controllers were successfully tested on the prototype of the spherical mobile robot to study the performance of the spherical mobile robot. However, the overall performance of the implemented designed controller has shown a minimum effectiveness. The controller managed to achieve the setpoint value but with low stability which result from the less accuracy of the hardware sensors.

There has been considerable effort in the automotive industry to reduce and control the noise in the car cabin. Selecting or designing a better absorber will enhance the comfort of the passengers in the car. There are many techniques to reduce or control the noise in the car cabin. One of the techniques is to place specific material in order to reduce its acoustical noise. This paper presents a study on sound absorption of the felt, polyurethane foam and fabric which are commonly used as car interior material. Furthermore, the influence of surface discontinuity created between two joined material parts is also investigated. The sound absorption coefficient is measured using two-microphone impedance tube. This tube is used to provide noise source frequency ranging from 50 Hz to 10 kHz. Using the dBAlpha software that is connected to the microphone via Symphonie Analyzer, the sound absorption coefficient of the material for every frequency is presented in tabular as well as in graphical form. The test results show that material selection is significantly important for the absorption of noise. Besides, it is found that the surface discontinuity gives different effect depending on the material. For the felt material, the surface discontinuity has insignificant effect. However, the surface discontinuity may give a moderate effect for other materials such as polyurethane foam and fabric.

This paper presents aeroelastic tailoring optimization of a swept back supersonic wing with external stores using composite structure material for the wing skin. The analysis has been conducted to calculate the flutter speeds at several altitudes ranging from a negative altitude of-7,943 ft until 30000 ft. MSC Nastran software is used to determine the flutter speed. The objective is to get the lowest possible wing weight by varying the wing skin composite fly angle and thickness as the optimization variables and by considering flutter speed as the optimization constraint. The constraint is imposed such that the flutter speed should be similar or higher than flutter speed of a previously investigated supersonic wing having similar planform but using aluminum as wing skin. The use of composite suggested that each composite layer thickness and fiber angle can be manipulated to achieve the target. The present results indicate that the weight of the composite wing skin can be reduced by 70 % compared to the aluminum wing skin while retaining similar or better flutter speed boundary envelope.

To maintain flight safety, all transport aircraft designs should satisfy airworthiness standard regulation. One fundamental issue of the aircraft design that relates directly to flight safety as well as commercial aspect of the aircraft is on the evaluation of the maximum speed within the designated flight envelope. In the present work, a study is performed to evaluate the negative altitude requirement related to aeroelastic instability analysis as one requirement that should be fulfilled to design the maximum speed. An analytical derivation to obtain the negative altitude is performed based on the airworthiness requirement that a transport airplane must be designed to be free from aeroelastic instability within the flight envelope encompassed by the dive speed or dive Mach number versus altitude envelope enlarged at all points by an increase of 15% in equivalent airspeed at both constant Mach number and constant altitude. To take into account variation in atmospheric condition as function of altitude, the international standard regulation is used as referenced. The analysis result shows that a single negative altitude can be obtained using these criteria regardless of the dive speed or dive Mach number. A further discussion on the application of the negative altitude concept to UAV (Unmanned Aerial Vehicle), in relation to UAV Standard Airworthiness Requirement STANAG 4671, is presented.