Design methods for mobility

In fixed wind turbine installations, the optimal wind location is difficult to individuate, permissions are difficult to obtain and the production site is distant from the costumers. The large production scale of small wheeled wind turbines keep the cost at minimum and give the possibility to install the windmill close to the final costumers. CFD simulation makes it possible to optimize the matching of a small mobile wind turbine with an automotive commercial alternator. This paper proposes an innovative device to furl the wind turbine around the pole axis in such a way to optimize energy production and avoid over-speed. For this purpose a commercial shock-absorber and a cam mechanism are used. The CFD simulation, in this case with Flow Simulation of Solid Works, makes it possible to design the turbine, the tail vane and the mechanism to maximize energy production. The device includes a shock absorber and a cam mechanism. The system provides optimum matching of the turbine torque output to the generator shaft. The same mechanism also determines the cut-out speed. The automotive generator includes a system to charge a 24V standard battery. Then, a power inverter outputs the electric energy to the grid. The 4m-diameter three-blades-rotor is connected to the 3.6kW automotive alternator through a commercial 2.5:1 speed multiplier.

Keywords: Cam furling mechanism , Energy production , Generator matching , Low cost , Wind turbine

Many papers for the analytical solution of the lift distribution on a semi in semi-elliptical wing have been published. These works [1] usually approximate the solution by series expansion. This paper introduces an original method for the closed-form solution of this problem. The solution is possible through the use of symbolic manipulators. The wing of the WWII fighter "Reggiane Re 2005" has been solved analytically with the proposed method. The results are similar to the ones obtained by the panel-method and CFD. A CFD simulation of the Re 2005 at maximum speed demonstrates that these results are reasonable.

Keywords: Analytical closed solution , Elliptical wing , Lift , Load

Aircraft fuel consumption depends on engine, engine installation, propeller and aircraft efficiency. The matching of the installed propeller is optimized for a design point and it is a compromise for the other working points. The matching of aircraft optimum lift/drag, the minimum engine fuel consumption and the maximum propeller efficiency is rarely achieved. The hyper simplified model on books does not reach the result. Practically very few aircrafts truly match the three conditions The champion of matching are current airliners that, at least in cruise and with half the fuel, reach the optimum at least at the nominal density altitude. In addition, a few fighters and record aircrafts also achieve the maximum possible speed at the nominal conditions. The large majority of the general aviation aircrafts are far from the optimum matching. Even Unmanned Aerial Vehicles are not champions of propulsion efficiency. Ultralight and sport aircraft are the worst. Turbines are very difficult for matching since their optimum efficiency is reached in a very limited working area. Even spark ignition engines are not efficient in off-design conditions. In fact, the spark ignition engine works with an air to fuel ratio by mass that can ran from 16:1 (lean mixture) down to 12:1 (rich mixture). Even spark ignition direct injection engines the combustion takes place within this range. At the relatively high torque settings typical of aircraft engines, the air inside the combustion chamber is burnt entirely and the power output depends on the engine volumetric efficiency. In diesel engines, the air inside the combustion chamber is never burnt entirely. The minimum air to fuel ratio is around 17:1, but the engine works well with any air to fuel ratio below this value. This means that CRDID (Common Rail Direct Injection Diesel) efficiency or BSFC (Brake Specific Fuel Consumption) curve is flatter than the spark ignition engine one. This fact gives a decisive advantage in the propeller matching and in the fuel consumption. In fact, off-design performance is the strongest point in favour of CRDIDs in general aviation. Therefore, the fuel consumption of CRDID takes advantage not only from the extremely high efficiency of the engine, but also from the better matching. In fact, it is possible to map the CRDID FADEC (Full Authority Digital Electronic Control) to optimize SFC (Specific Fuel Consumption). In the example shown in this paper, a CRDID needs nearly half the fuel necessary to a very good spark ignition engine.

Keywords: Aircraft matching , Diesel engine , Power plant installation efficiency , Propeller , Propeller efficiency , Spark ignition engine

This paper shows that the sinkage of the tracked vehicle is the most important parameter in its mobility. Power and fuel consumption follow cubic power law with sinkage. So the usual strategy to increase power is not the more convenient way to improve vehicle off road performance. The Ground Pressure (GP) is the critical parameter. Power requirement goes with the cubic power of sinkage. GP above 0.9 daN/cm2 should be avoided at all costs. The best way to obtain this result on an existing design is to increase track length. However it is easier to work on track width. The easiest modification is to add "Duckbill extensions" in the outer part of the shoe. This system was used on the Sherman Tank when additional armor was added. With modern technology it is perfectly possible to perform experimental tests with new shoes. This can be done by manufacturing prototypes of high stress nitrided steel shoes, usually with 300M high strength steel. Comparative fuel consumption is a good index of vehicle performance. Also wheel diameter and width can be increased to improve off-road performance. Specialized tracks for different terrains should also be designed. The gravity center should be kept slightly rearward. This attitude should not be excessive to keep the pressure value more even possible along the track. In any case the vehicle naturally assumes the backward inclination due to terrain compression. Another important improvement is the addition of computer controlled directional control to improve the accuracy of trajectories. This is particularly important for tracked vehicles where turning involves extremely high energy consumption.

Keywords: Ground pressure , Mobility , Tracked vehicles

The primary task in DI (Direct Injection) diesel engines design is the fulfilment of the required emission limits. This result should be achieved while still providing optimum torque-to-rpm curves, acceptable fuel consumption, acceptable power density and affordable purchase and maintenance costs. One method to achieve these objectives is the downsizing. In this case a significant increase in the crankshaft speed and boost pressure is unavoidable. In this way an increase in air flow rate through the intake and exhaust ducts is obtained. Considering the impact of these changes, the duct design is extremely critical due to Mach number. Another physical limit is the CR (Common Rail) injector dynamic performance. This performance decreases with injector size and maximum fuel flow for inertia problems. Automotive engines in the range of 10 to 100 HP per cylinder are the most numerous. For this reason, these injectors are the most updated. Furthermore, their small inertia favors a better dynamic performance. The larger number of nozzles improves combustion performance. In fact, the better surface to volume ratio or the spray improves heat transfer. For this reason, it is convenient to use multiple injectors systems in modern HSDI (High Speed Direct Injection) CR large diesels, as it was common in the past. The primary purpose of this study is to examine the best duct geometry on a modern two-injectors-per-cylinder truck engine. For this purpose a new promising, patented concept is introduced. The study includes flow simulations during the intake phase. This new-patented design enables the formation of two extremely strong homogeneous swirls centered to the injectors, with excellent swirl and flow coefficients. The use of swirl generators on the manifolds avoids the necessity to design helical intake ducts. This approach simplifies head design. Moreover, using a VG (Variable Geometry) arrangement for the volutes (swirl generators) it is possible to tune the swirl index at the optimum for every crankshaft velocity and every load. In this way, the vehicle fuel consumption is reduced.

Keywords: Common Rail , Diesel , Direct injection , Multiple injectors , Swirl index

The large majority of current trainers are piston engine aircrafts. Their engine lasts 2,000 hours maximum. The idea is to substitute the engine with a green electric powerpack with the same performance of the original unit, but with no emission and basically with no maintenance. The powerpack should be easy to install, safe and should provide sufficient autonomy. This last part is particularly easy for trainers, since they fly in a very standard way. At morning, with the battery fully charged, the instructor and the student perform a flight that lasts typically from 20 minutes to 2 hours. On landing a de-briefing of the student takes place. This phase is followed by the briefing of the new student. These two steps take at minimum of 30 minutes. During this time the battery can be partially recharged. The process will continue for a full day, with a longer recharge during break times. Therefore, it is perfectly possible to have a one day autonomy (about 10 hours). This project is intended to develop an experimental green trainer to validate the best configuration for this power pack and to find-out critical issues on installation, safety, reliability and maintenance. Finally, a minimum number of 300 hours of flight will be performed to perform an accelerated test to individuate critical safety issues on the new proposal. This part should be considered as in integral part of the University Career for those aviation students who want to get involved in testing and engineering, rather than only flying. At the same time, converting powerplants from the combustion ones into the electric ones will contribute to reduce the polluting emissions in the air that produce micro-climate changes.

Keywords: aircraft trainers , Electric engines , emissions , maintenance

The main purpose of the investigation is to develop reliable methods to repair IN 792 superalloy components by Laser Beam Welding (LBW). The jet engine structural components made of nickel-base superalloys are subjected to high stresses and severe environmental, therefore crack may occurs during in-service life. Considering the high cost of this components they are often repaired by welding. Welds must be made: (i) by altering as little as possible the original microstructure; (ii) without introducing in the molten (MZ) and heat affected (HAZ) zones relevant residual stresses; (iii) without producing cracks in MZ and HAZ; (iv) without massive chemical segregation; (v) without elemental diffusion changing the composition of γ and γ' phases. LBW has been used to realize seams on 2mm-thick plates of directionally solidified (DS) IN792 superalloy. An Yb fiber laser has been employed in present experiments and the molten pool was shielded from oxidation through a patented equipment. A grid of samples has been prepared by varying the pass speed v from 1 to 2.0 m/min with pre-heating temperature of 200 °C. The microstructural changes occurring in the microstructure of molten zone (MZ) and heat affected zone (HAZ) have been investigated by optical and scanning electron microscopy (SEM) observations and energy dispersion spectroscopy (EDS).

Keywords: INS 792 , Laser Welding , Nickel superalloy

Simulation results are not representative of a real system behavior up to its model validation. Validation activity needs a model characterization to match real system and model parameters. This activity impacts more on mechatronics systems which are affected by both physical and control characterizations. This work deals with single bowden power window systems; it improves a system model, previously developed, by deepening window aspects and force system. Force types and modules have been obtained by several experimental tests, in different operating conditions. Experimental automated tests have been carried out by means of a new virtual instrument developed in LabVIEW® environment. Comparison of test results highlights three main components related to: sliding friction, window friction and gravity. These components are affected by window shape which induces module variations. We named these variations 'window shape effect and these results bring to a new procedure for system validation.

Keywords: experimental test , mechatronic system , single bowden power window system , system model validation , validation

Ergonomic design of automotive seat is a very challenging task whose results may directly influence driver's comfort and safety. Seat comfort can be improved by identifying car-packaging solutions that allow an optimal driver's posture. In order to reduce the time and cost for testing, ergonomic analysis is carried out in virtual reality (VR) environment with digital human models (DHM) that can be used to simulate the anthropometric variability of a target population of users and thus verify the robustness of design solutions with respect to the anthropometrical noise factor. In this paper we illustrate a case study concerning the comfort improvement of a minicar packaging set up via robust ergonomic design (RED) with digital human models. The aim is the identification of the optimum levels for the seat control parameters that minimize the driver's comfort loss with respect to a preferred posture. The approach adopted for the analysis of data obtained from the virtual experiments is based on the joint generalized linear modeling of mean and dispersion of the driver's postural comfort loss (i.e. the ergonomic response of interest).

Keywords: Generalized Linear Models , Postural Comfort Loss , Robust Ergonomic Virtual Design , Seat Comfort Improvement

The paper presents the design of an onshore Wave Energy Converter (WEC) named ALETTONE (At Least Energy Thanks To Neptune), which is characterized by a low cost mechanical architecture based on a four-bar linkage with mobility in a vertical plane. The lower link is a floating rocker arm moved by the hydrostatic and hydrodynamic forces exerted by the sea water, whereas the upper rocker arm is connected to a rotating electric generator via a transmission composed of either a single or a pair of one-way clutches coupled to a speed multiplier gearbox. Due to its simplicity, this WEC concept seems to be an interesting solution for energy generation in isolated locations. After a description of the overall design, the dynamic model of the system is presented, along with simulation results in case of monochromatic and panchromatic waves.

Keywords: Four-bar mechanism , Multibody simulation , Onshore generation , Wave energy converter

The i.Drive Lab has developed inter-disciplinary methodology for the analysis and modelling of behavioral and physiological responses related to the interaction between driver, vehicle, infrastructure, and virtual environment. The present research outlines the development of a validation study for the combination of virtual and real-life research methodologies. i.Drive driving simulator was set up to replicate the data acquisition of environmental and physiological information coming from an equipped i.Drive electric vehicle with same sensors. i.Drive tests are focused on the identification of driver's affective states that are able to define recurring situations and psychophysical conditions that are relevant for road-safety and drivers' comfort. Results show that it is possible to combine different research paradigms to collect low-level vehicle control behavior and higher-level cognitive measures, in order to develop data collection and elaboration for future mobility challenges.

Keywords: driving assessment , on-road tests , physiological measures , test vehicle , virtual reality simulator

The advancement of in-vehicle technology for driving safety has considerably improved. Current Advanced Driver- Assistance Systems (ADAS) make road safer by alerting the driver, through visual, auditory, and haptic signals about dangerous driving situations, and consequently, preventing possible collisions. However, in some circumstances the driver can fail to properly respond to the alert since human cognition systems can be influenced by the driving context. Driving simulation can help evaluating this aspect since it is possible to reproduce different ADAS in safe driving conditions. However, driving simulation alone does not provide information about how the change in driver's workload affects the interaction of the driver with ADAS. This paper presents a driving simulator system integrating physiological sensors that acquire heart's activity, blood volume pulse, respiration rate, and skin conductance parameters. Through a specific processing of these measurements, it is possible to measure different cognitive processes that contribute to the change of driver's workload while using ADAS, in different driving contexts. The preliminary studies conducted in this research show the effectiveness of this system and provide guidelines for the future acquisition and the treatment of the physiological data to assess ADAS workload.

More than one million people die per year on world's road. Researches have identified drivers' cognitive aspects as the major cause of human errors in 80% of crash events. Driver-Assistance Systems (DAS) have been developed to detect data about vehicle, environment and driver, and to communicate information usually through the senses of vision and hearing. But, the growth of in-vehicle devices increases the visual and auditory demand of the driver. This research aims at investigating whether olfactory stimuli can be used to elicit drivers' cognitive aspects. An experimental framework has been set up, and testing sessions have been organised. The analysis of the data collected from tests shows that olfactory stimuli are more effective in increasing some subjects' physiological parameters than the auditory ones. Therefore, smells may be used as a DAS, for increasing drivers' attention.

Keywords: Driver-assistance systems , Drivers' attention , Olfactory stimuli

This paper presents the determination of the vibration impact of the helicopter structural components and skin repairs in terms of frequency characteristics. To address this issue, a 3D Finite Element Method (FEM) model of 349 Gazelle helicopter has been developed in ABAQUS and the frequency analysis is conducted. The results on the natural frequencies of the full structure reasonably match with the literature giving confidence in the baseline model. The main advantage of this FEM model is that, it can be used to predict the natural frequencies of the full structure, precisely. In addition, the material properties and conditions of the components can be updated based on the applied conditions during the repair and maintenance period. Thus, the model gives a comprehensive design tool for analysing the frequencies of the helicopter with differing components. The effective variations in the frequency changes due to repair are predicted numerically. The discussion of these results helps in developing leads to improved selection of replacement materials and their properties.

This research focuses on the integrated simulation of helicopter-pilot system to predict pilot's physiological and psychological responses to the vibration. This paper describes the approach of integration of helicopter structural model to the aerodynamic forcing function and to the pilot-seat model. The physiological and psychological responses at 5 Hz are calculated based on vibration transmission ratio of the pilot's body segments. The pilot's Physiological responses including heart rate, highest blood pressure, lowest blood pressure, respiration rate and saliva secretion quantity are presented. Tired eyes, irritation, dizziness, yawning, sleepiness and headache as psychological reactions are provided. The integrated simulation approach of helicopter-pilot system can be used for pilot health and comfort assessments, helicopter structural and cockpit and seat design.

The associated risk for a patient taking advantage of Helicopter Emergency Medical Services (HEMS) mainly relates to vibrations. To this aim, especially in case of trauma and serious illness and long travels, aspects related to the vibrations effects on the patient needs to be properly investigated, taking into account the particular features of the helicopter used for HEMS. The purpose of this paper is the integrated simulation of vertical vibration at the supine patient's body, lying down on a rescue litter, in HEMS. Here, a 3D structural model of a reference helicopter, the Aerospatiale Gazelle, has been developed in ABAQUS and integrated with a dynamic model where aerodynamic forcing functions due to rotor are modelled. The accelerations at the litter location in the helicopter structural model are recorded and used as inputs to the supine patient's body model in MATLAB. The Multi-Body (MB) model of the patient's body consists of three interconnected masses of the head-neck, torso-arms and pelvis-legs. The simulation is carried out for single manoeuvre and the vibration information is extracted at the three body segments. This predictive approach of integrated simulation of the helicopter-patient is an effective tool in investigating of biodynamic response of the patient in HEMS. The benefits of this approach are reducing the risk and costs of running the experiments, providing suggestions on redesigning of litters and controlling the vibration on the litters in HEMS.

Keywords: Helicopter Emergency Medical Service , HEMS , Simulation , Structural model , Supine patient's body , Vertical vibration

Purpose - This paper aims to describe a methodology to optimize the trajectory of unconventional airship performing a high-altitude docking manoeuvre. Design/methodology/approach - The trajectories are based upon Bezier curves whose control points positions are optimized through particle swarm optimization algorithm. A minimum energy strategy is implemented by considering the airship physical properties. The paper describes the mathematical model of the airships, the trajectories modelling through Bezier's curves and the optimization framework. A series of test cases has been developed to evaluate the proposed methodology. Findings - Results obtained show that the implemented procedure is able to optimize the airship trajectories and to support their in-flight docking; a strong influence of the wind speed and course on the trajectories planning is highlighted. Research limitations/implications - The wind speed considered in these simulations depends only on altitude, and gusts effect has been neglected. Practical implications - The proposed model can support the study of unconventional airship trajectories and can be useful to evaluate best in-air docking strategies. Originality/value - The paper addresses the problem of trajectory optimization for a class of new air vehicles with an heuristic approach.

Keywords: Airship , Bezier curves , Green transportation , Heuristic algorithms , Trajectories optimization

Four-wheeled vehicles are often tested on indoor, four-poster road simulator rigs. Road loads are simulated with the use of servo-hydraulic systems for suspension set-up optimisation, NVH analysis, and fatigue life cycles. The use of a road simulator is not such a common practice for two-wheeled vehicles despite problems to be faced being extremely similar. The paper presents a device for testing motorcycles on a Servotest® four-poster. A dedicated restraint system had to be devised in order to support the motorcycle without altering its inertial characteristics. Additional pneumatic actuators with a purposely developed instrumentation have been designed to reproduce braking and power thrusts.

Keywords: Indoor testing , Motorcycles , Ride testing , Road simulator

Indoor testing should reproduce the real-world environment in order to be effective. In this article, an efficient methodology to reproduce road profiles on a four-poster rig is presented: such a method includes a complex rig control strategy based on an iterative process. Road profiles come from a purposely designed set of sensors fitted on the car which remains the same regardless of the vehicle or surface type. Particular stresses such as speed humps, potholes and manholes can be reproduced as well. Since there are no previous similar studies, a validation is provided by comparing road and rig data streams and using the maximum absolute error and root mean square error as performance indexes. Results show that the rig is able to reproduce road profiles and the related inputs to the vehicle successfully; hence, the method is reliable and effective.

Keywords: chassis and suspensions testing , durability tests , four-poster test rig , indoor testing , Road reproduction , vehicle ride testing

This paper introduces a Montecarlo Genetic Algorithm, hierarchical, multiobjective optimization of a Vertical Take Off landing Unmanned Aerial Vehicle having a tail sitter configuration. An optimization of the hierarchical type is introduced in place of the methods generally used multi-objective optimization, such as Pareto and “arbitrary” weighted sums. A Montecarlo method optimizes the weights of the final objective function used by the Genetic Algorithm. A very simple “spreadsheet based” algorithm defines the CAD model of the Genetic Algorithm individuals in order to evaluate the performance of the candidates. The optimization method described in this study appears to be very effective. Then experimental tests were conducted with scaled-down prototypes. Four flight tests were performed: Take Off, Cruise, Slow flight, Landing. A Taguchi matrix was defined for each experiment. The tests started from a prototype that comes directly from the Montecarlo Genetic Algorithm optimization and led to the final prototype shown along the paper (page 7, right figure). Unfortunately, the tail sitter approach proved poor control authority in the final phase of the vertical landing. Even the “final” prototype showed unsatisfactory behavior in case of erratic wind gusts. This unsolved problem is common to the tail sitter configuration that requires a power control by air jets or additional propeller to control the aircraft in the final phase of landing. Unfortunately, this necessity renders the tail sitter configuration inconvenient for small Unmanned Aerial Vehicles.

Keywords: Genetic algorithm , Montecarlo random optimization , Tail sitter , UAV