This thesis deals with composite joints. Designing such joints is more difficult than metallic joints due to the mechanical properties of composite materials. Composites are anisotropic and have a limited ability of yielding. The low degree of yielding means that stress concentrations are not relieved by plastic deformation, which is important in multi-fastener single-lap joints. The distribution of load between the fasteners may be more uneven than in metallic joints due to that the stress concentrations around the holes are not relieved. Single-lap joints have an eccentric load path which generates a nonuniform bolt-hole contact pressure through the plate thickness. This generates out-of-plane deflection of the joint, termed secondary bending. Such nonuniform contact stress severely limits the strength of the joint. The nonuniform contact stress distribution is affected by several factors, e.g. bolthole clearance and secondary bending. The first part of the work is devoted to investigating secondary bending, and its effect on stresses in the joint. A novel technique to study secondary bending has been developed and used in a parametric study. It is based on the calculation of specimen curvature from out-of-plane deflections measured with an optical technique. It is shown that the specimen curvature is correlated to the conventional definition of secondary bending, which involves strain measurements on both sides of the plate. The two most important parameters affecting specimen curvature was found to be the overlap length and the thickness of the plates. The finite element method was used to study the influence of secondary bending on joint strength. Secondary bending was changed in magnitude by altering the length of the overlap region in a two-fastener specimen. It was found that secondary bending affects the local stress field around the fasteners and that it may change the strength and the mode of failure. The second part is concerned with the load distribution and prediction of joint strength. A detailed finite element model was developed to calculate the load distribution while accounting for bolt-hole clearances, bolt clamp-up, secondary bending and friction. An experimental programme was conducted in order to validate the finite element model by means of instrumented fasteners. Good agreement between simulations and experiments was achieved and it was found that bolt-hole clearance is the most important factor in terms of load distribution between the fasteners. Sensitivity to this parameter was found to be large, implying that temperature changes could affect the load distribution if member plates with different thermal expansion properties are used. Calculating the load distribution in structures with a large number of fasteners is in general not feasible with detailed finite element models based on continuum elements. A simplified, computationally effective model of a multi-fastener, singlelap joint has been developed by means of structural finite elements. The model accounts for bolt-hole clearances, bolt clamp-up, secondary bending and friction. Comparisons with the detailed finite element model and experiments validated the accuracy of the simplified model. A parametric study was conducted where it was found that an increased stiffness mismatch between the plates generates a more uneven load distribution, while reducing the length of the overlap region has the opposite effect. Increasing the stiffness of a fastener shifts some of the load from the nearest fasteners to that particular fastener. An idealized optimization study was conducted in order to minimize bearing stresses in the joint with restrictions on the increase of joint weight and net-section stresses. Maximum bearing stress was reduced from 220 MPa to 120 MPa while both weight and net-section stresses decreased. A procedure to predict bearing strength based on the results from the simplified model was developed. It was established by an experimental programme that fiber micro-buckling is the initial failure mode. The stress state in the laminate was determined through force and moment equilibrium, based on output from the finite element model. An existing criterion was used to predict the fiber microbuckling, and thus the initial failure. Predictions were compared with experiments which validated the method. The small computational cost required by the procedure suggests that the method is applicable on large scale structures and suitable to use in conjunction with iterative schemes such as optimization and statistical investigations. / QC 20110121

The car has become bigger, faster and more advanced for each passing year since its first appearance, and the safety requirements have also become stricter. Computer vision based support is a growing area of safety features where the car is equipped with a mono- or stereo camera. It can be used for detecting pedestrians walking out in the street, give a warning for wild-life during a cold January night using night-vision cameras and much more. This master thesis investigates the problem of detecting and tracking overtaking vehicles. Vehicles that overtake are only partly visible in the beginning, rendering it hard for standard detection/classification algorithms to get a positive detection. The need to quickly detect an incoming vehicle is crucial to be able to take fast counter-measure, such as braking, if needed. A novel approach referred to as the \textit{Wall detector} is suggested, detecting incoming vehicles using one-dimensional optical flow. Under the assumption that an overtaking car is moving in parallel to the ego-vehicle, both cars are moving towards the vanishing point in the image. A detection wall, consisting of several detection lines moving towards the vanishing point, is created, making all objects that are moving parallel to the ego-vehicle move along these lines. The result is a light-weight and fast detector with good detection performance in real-time. Several approaches for the Wall detector are implemented and evaluated, revealing that a feature based approach is the best choice. The information from the system can be used as input to heavier algorithms, boosting the confidence or to initialize a track.

This research builds on three projects that aim to investigate how knowledge transfer takes place in new product development in the automotive industry. The study seeks to picture how product development teams frame and shape new product knowledge, how they interpret such knowledge, and how they apply knowledge to the product development process. From that perspective, product development activities can be seen as transactions that are integrated into an overall system of identifying, assessing, collecting and combining knowledge. Results of my research so far reveal that there are many factors that affect the successful management of knowledge transfer in new product development projects. Based on my first two projects, using the case study approach, it is evident that for successful knowledge transfer to occur, there is a need to distinguish between design knowledge that is embedded in the tacit knowledge domain and that embedded in the or explicit design knowledge domain. The results of project three, using a survey questionnaire approach, provide a powerful demonstration, that knowledge integration, combination and creation in product development need intensive interaction and collaboration. The enormous importance of interaction and collaboration to integrate and combine knowledge has its origin in the nature of design knowledge. For example engineers produced in the survey a 82 % rate of agreement with the statement that they use mainly knowledge that comes from their past work experience as product developers, in order to solve complex design tasks. The underlying assumption of this finding is, that engineers are therefore mostly forced to transfer tacit design knowledge to solve complex design tasks. The research showed that a remarkable under-performance exists in knowledge identification and knowledge articulation in new product development in the automotive industry. In vehicle development, non-routine tasks are highly complex. This requires team members to have an understanding of the complete product system architecture. To create such an understanding, engineers need to identify and articulate knowledge. These activities can be seen as a pre-knowledge creation. The result is a shared product knowledge base, which makes it possible for people engaged in the vehicle development process to use different kinds of knowledge to capture and link new technologies into innovative products. This may require a cultural shift by vehicle manufacturers in terms of how they steer and allocate resources to future vehicle development programmes. Building on four years engagement with knowledge transfer research, I conclude that organisations in the automotive sector still rely on methods and processes that were successful in the past and strictly directed at exploiting tangible assets. To integrate preknowledge creation, as a new found discipline in product development projects creates an enormous potential to integrate and combine knowledge in an efficient way for future product development projects.

The robust loop-shaping control methodology is applied in the flight control system design of the Cranfield A3 Observer unmanned, unstable, catapult launched air vehicle. Detailed linear models for the full operational flight envelope of the air vehicle are developed. The nominal and worst-case models are determined using the v-gap metric. The effect of neglecting subsystems such as actuators and/or computation delays on modelling uncertainty is determined using the v-gap metric and shown to be significant. Detailed designs for the longitudinal, lateral, and the combined full dynamics TDF controllers were carried out. The Hanus command signal conditioning technique is also implemented to overcome actuator saturation and windup. The robust control system is then successfully evaluated in the high fidelity 6DOF non-linear simulation to assess its capability of launch stabilization in extreme cross-wind conditions, control effectiveness in climb, and navigation precision through the prescribed 3D flight path in level cruise. Robust performance and stability of the single-point non-scheduled control law is also demonstrated throughout the full operational flight envelope the air vehicle is capable of and for all flight phases and beyond, to severe launch conditions, such as 33knots crosswind and exaggerated CG shifts. The robust TDF control law is finally compared with the classical PMC law where the actual number of variables to be manipulated manually in the design process are shown to be much less, due to the scheduling process elimination, although the size of the final controller was much higher. The robust control law performance superiority is demonstrated in the non-linear simulation for the full flight envelope and in extreme flight conditions.

This thesis work was executed at Swift Engineering Incorporated located in San Clemente, California during spring in 2009. Placement supervisor from Swift was Mark Page and advisor and examiner from the Division of future products at Mälardalen University, Sweden was Gustaf Enebog. The objective with this thesis work was to examine the effects of fitness ratio, lift over drag, lift coefficient at cruise, winglet span, wing sweep angle, wing aspect ratio, wing area and weights with respect to Mach number for a conventional business jet capable of 18 passengers. The cruise speed study range from Mach 0.88 to 0.99. The Excel based conceptual design tool Jetsizer 2008c was used to make four models with similar configuration and mission but with different cruise Mach numbers. A new Jetsizer module was then created to handle a modification process where the models are optimized for their speed and configuration. The result in this report gives guidelines for the needed values when creating an initial CFD model for this type of airplane.

SAMMANFATTNING Detta arbete har gått ut på att i CAD implementera en UAV-design av Enebog, Designen har förmedlats av handledaren via möten och mail. Ett ”levande” dokument skapades och har sedan uppdaterats från båda sidor genom projektets fortlöpande. Dimensioner och mått har diskuterats samt hur det ska implementeras i CAD. UAV’n är uppbyggd som en ”assembly” i CAD, med tillhörande modeller och ”sub-assemblies”. Modellerna är designade i Solid Works standard-arbetsbänk och ihopsatta i assemblyn med så kallade ”mates”. Tyngdpunkt och massa har beräknats i Solid Works för flygplanets olika delar. Datat har exporterats till Excel för att kunna presenteras. Resultatet är 7 stycken 2D ritningar kopplade till en 3D modell. Flygplanet har en spännvidd på 2,7 meter och en vingarea på 0,91m2. Den totala längden dimensionerades till 1,87 meter och den totala massan kalkylerades till 8,68 kg, som också är flygplanets ”take off weight”. Flygplanet är designat för att byggas med två olika komposit material: kolfiber/epoxy och glasfiber/epoxy. I ritningsunderlaget genererares tre-plans vyer med måttsättning, detaljvyer på till exempel nos-poden i den främre delen av flygplanet samt en sprängskiss med innehållsförteckning. / ABSTRACT This work has been focused on implementing, into CAD (Solid Works), a UAV-design by Enebog. The design has been given to the author on meetings and mail. A “living” document with design parameters was updated from both sides continuously throughout the project. The measurements/dimensions of the aircraft were discussed as well as how to implement in CAD. All updates were also continuously updated in the document. The UAV is built up as an assembly in CAD, with sub-assemblies and parts. The parts are designed with the standard work bench in Solid Works and mated together to form an aircraft. Center of gravity and mass properties of the parts were calculated in Solid Works and exported to Excel for the purpose of presenting the data. The result is 7 2D drawings attached to a 3D model. The aircraft has a wing span of 2,7 meters (8,68 ft), with a corresponding wing area of 0,91 m2 (9,8 ft2). The total length is dimensioned to 1,87 m (6,14 ft) and the total mass is calculated to 8,68 kg (19,14 lbs), which is also the aircrafts takeoff weight. The aircraft is designed to be built with two composite materials; carbon fiber/epoxy and glass fiber/epoxy. In the drawing material plan views with dimensions of the aircraft, detail views of e.g. the nose pod in the front part of the aircraft, an exploded view with a corresponding build of material-table was generated.

Unmanned Vehicles (UVs) are developed for several civil and military applications. For these applications, there is a need for multiple vehicles with different capabilities to visit and monitor a set of given targets. In such scenarios, routing problems arise naturally where there is a need to plan paths in order to optimally use resources and time. The focus of this thesis is to address a basic optimization problem that arises in this setting. We consider a routing problem where some targets have to be visited by specific vehicles. We approach this problem by dividing the routing into two sub problems: partitioning the targets while satisfying vehicle target constraints and sequencing. We solve the partitioning problem with the help of a minimum spanning tree algorithm. We use 3 different approaches to solve the sequencing problem; namely, the 2 approximation algorithm, Christofide's algorithm and the Lin - Kernighan Heuristic (LKH). The approximation algorithms were implemented in MATLAB. We also developed an integer programming (IP) model and a relaxed linear programming (LP) model in C with the help of Concert Technology for CPLEX, to obtain lower bounds. We compare the performance of the developed approximation algorithms with both the IP and the LP model and found that the heuristic performed very well and provided the better quality solutions as compared to the approximation algorithms. It was also found that the approximation algorithms gave better solutions than the apriori guarantees.

This paper presented Symmetric and Asymmetric Regular Sampling techniques apply successfully to a Digital Signal Processor (DSP) together with an inverter. Experimental results are shown that taking advantage of SPWM control techniques can reduce the waste of energy. Further, the Soft Start techniques of DSP scripts can boost security for driver. Moreover motor driver safely can be increased by designing circuit to prevent over voltage. The function of motor driver will be better due to the decreased hardware size and increased accuracy which are the advantage of writing DSP scripts to analysis rotor speed.

When carrying out sampling tasks close to the ocean bottom, a ROV keeps station at a fixed position and compensates the tether effects and currents. However, the operation of ROV thrust propellers for station keeping might stir up sediment and cause poor visibility, which forces ROV operators to stop work until the sediment clears. The purpose of this thesis, therefore, is to design and fabricate a seafloor moving platform able to approach steadily to sampling objects without stirring up much sediment. This moving platform must be combined with the second generation NCKU-NSYSU ROV, a sampling manipulator, and a sample storage apparatus. Also, the moving platform requires some capabilities for travel over relatively smooth seafloor. A wheel-driven mobile platform, as a result, is developed, in which the front wheels and rear wheels are respectively driven by two separately provided DC motors. The required power and serial command signals are transmitted to the platform via the second generation NCKU-NSYSU ROV. A four-bar linkage for steering font wheels is designed to work close to the Ackerman condition, and a chain-and-sprocket drive train is used to transfer power to the rear wheels. The motor controllers used for controlling DC motors are constructed based on MSP430 MCU (Micro Controller Unit). The preliminary driving performance of the platform is tested. The testing results indicate that the moving platform can drive steadily and behave as expected.

<p>This thesis deals with composite joints. Designing such joints is more difficult than metallic joints due to the mechanical properties of composite materials. Composites are anisotropic and have a limited ability of yielding. The low degree of yielding means that stress concentrations are not relieved by plastic deformation, which is important in multi-fastener single-lap joints. The distribution of load between the fasteners may be more uneven than in metallic joints due to that the stress concentrations around the holes are not relieved. Single-lap joints have an eccentric load path which generates a nonuniform bolt-hole contact pressure through the plate thickness. This generates out-of-plane deflection of the joint, termed secondary bending.</p><p>Such nonuniform contact stress severely limits the strength of the joint. The nonuniform contact stress distribution is affected by several factors, e.g. bolthole clearance and secondary bending. The first part of the work is devoted to investigating secondary bending, and its effect on stresses in the joint. A novel technique to study secondary bending has been developed and used in a parametric study. It is based on the calculation of specimen curvature from out-of-plane deflections measured with an optical technique. It is shown that the specimen curvature is correlated to the conventional definition of secondary bending, which involves strain measurements on both sides of the plate. The two most important parameters affecting specimen curvature was found to be the overlap length and the thickness of the plates. The finite element method was used to study the influence of secondary bending on joint strength. Secondary bending was changed in magnitude by altering the length of the overlap region in a two-fastener specimen. It was found that secondary bending affects the local stress field around the fasteners and that it may change the strength and the mode of failure.</p><p>The second part is concerned with the load distribution and prediction of joint strength. A detailed finite element model was developed to calculate the load distribution while accounting for bolt-hole clearances, bolt clamp-up, secondary bending and friction. An experimental programme was conducted in order to validate the finite element model by means of instrumented fasteners. Good agreement between simulations and experiments was achieved and it was found that bolt-hole clearance is the most important factor in terms of load distribution between the fasteners. Sensitivity to this parameter was found to be large, implying that temperature changes could affect the load distribution if member plates with different thermal expansion properties are used.</p><p>Calculating the load distribution in structures with a large number of fasteners is in general not feasible with detailed finite element models based on continuum elements. A simplified, computationally effective model of a multi-fastener, singlelap joint has been developed by means of structural finite elements. The model accounts for bolt-hole clearances, bolt clamp-up, secondary bending and friction. Comparisons with the detailed finite element model and experiments validated the accuracy of the simplified model. A parametric study was conducted where it was found that an increased stiffness mismatch between the plates generates a more uneven load distribution, while reducing the length of the overlap region has the opposite effect. Increasing the stiffness of a fastener shifts some of the load from the nearest fasteners to that particular fastener. An idealized optimization study was conducted in order to minimize bearing stresses in the joint with restrictions on the increase of joint weight and net-section stresses. Maximum bearing stress was reduced from 220 MPa to 120 MPa while both weight and net-section stresses decreased.</p><p>A procedure to predict bearing strength based on the results from the simplified model was developed. It was established by an experimental programme that fiber micro-buckling is the initial failure mode. The stress state in the laminate was determined through force and moment equilibrium, based on output from the finite element model. An existing criterion was used to predict the fiber microbuckling, and thus the initial failure. Predictions were compared with experiments which validated the method. The small computational cost required by the procedure suggests that the method is applicable on large scale structures and suitable to use in conjunction with iterative schemes such as optimization and statistical investigations.</p>