Refine Your Search

Search Results

Technical Paper

Path Planning Algorithm of Intelligent Vehicle Based on Improved Visibility Graphs

2018-08-07
2018-01-1581
At present, the visibility graphs algorithm is mainly implemented in the field of mobile robot’s path planning on unstructured pavement. It only considers the common constraints such as travel time and move distance. The problems of road boundary and vehicle dynamics constraints are not involved. In this paper, a local path planning algorithm based on improved visibility graphs was proposed for intelligent vehicles traveling on structured road. The algorithm combined the geometric constraints of the road boundary with the vehicle dynamics constraints. By predicting the position of the obstacle vehicle in the preview time, the algorithm was used to generate the information of path network. Then, the performance index function was used to evaluate the trajectory which satisfying the maximum curvature constraint in the network. In this way a smooth path with minimum distances satisfying the constraints was obtained.
Technical Paper

A Novel Direct Yaw Moment Control System for Autonomous Vehicle

2018-08-07
2018-01-1594
Although autonomous driving technology has become an emerging research focus, safety is still the most crucial concern when autonomous vehicles leave research laboratory and enter public traffic. Direct yaw moment control (DYC), which differentially brakes the wheels to produce a yaw moment, is an important system to ensure the driving stability of vehicle under extreme conditions. The design of traditional DYC system must need to take into account driver’s intention and vehicle dynamics. However, for autonomous vehicle, no human is involved in driving process, and enforcing traditional DYC system may conflict with the demands of the desired path. Therefore, in this paper, a novel DYC system for autonomous vehicle is proposed using a hierarchical control architecture.
Technical Paper

Analysis of Vehicle Steering Stability of Nonlinear Four Wheel Steering Based on Sliding Mode Control

2018-08-07
2018-01-1593
Steering movement is the most basic movement of the vehicle, in the car driving process, the driver through the steering wheel has always been to control the direction of the car, in order to achieve their own driving intention. Four Wheel Steering (4WS) is an advanced vehicle control technique which can markedly improve vehicle steering characteristics. Compared with traditional front wheel steering vehicles,4WS vehicles can steer the front wheels and the rear wheels individually for cornering, according to the vehicle motion states such as the information of vehicle speed, yaw velocity and lateral acceleration. Therefore, 4WS can enhance the handling stability and improve the active safety for vehicles.
Paper

Advances in UAV Applications and Propulsion Technologies Drive the Development of UAV Propulsion Standards

2018-06-29
WP-0009
The number of small unmanned aerial vehicles (UAVs) used for private and commercial applications is growing exponentially, beyond the domain of hobby enthusiasts. However, standards development has not been keeping up with the applications and technologies now available. The advent of inexpensive battery-powered quadcopters as stable aerial photography and remote-viewing platforms has expanded the utility of these systems into commercial and private applications for inspection and surveillance. With drone-delivered packages on the horizon, the potential for expansion will be even higher. These developments need to be incorporated into standards being produced for UAVs and propulsion systems.
Technical Paper

Numerical Aeroacoustic Noise Prediction for Complex HVAC Systems

2018-06-13
2018-01-1515
Abstract Reliable tools for the prediction of aeroacoustic noise are of major interest for the car industry and also for the vendors of heating, ventilation and air conditioning (HVAC) systems whose aim is to reduce the negative impact of HVAC noise onto passengers. In this work a hybrid approach based on the acoustic perturbation equations is tested for this purpose. In a first step, the incompressible flow field is computed by means of a commercial finite volume solver. A large eddy simulation turbulence model is used to obtain time resolved flow data, which is required to accurately predict acoustic phenomena. Subsequently, the aeroacoustic sources are computed and conservatively interpolated to a finite element grid, which is used to calculate the sound radiation. This procedure is tested for an HVAC unit, a radial blower and finally for a complete system, which combines these two components.
Technical Paper

Direct Aeroacoustics Predictions of Automotive HVAC Systems based on Lattice Boltzmann Method

2018-06-13
2018-01-1520
Abstract The demand for low noise level in vehicle cabin continues to rise lately. In particular, noise generated by eco-friendly cars such as hybrid and electric ones tends to become lower and lower. In this market environment, the noise contributions caused by HVAC systems are also increasing. Therefore, it becomes increasingly important to accurately predict noise generated by HVAC systems and analyze the noise sources and resolve the noise issue. In this study, direct acoustics prediction approach based on Lattice Boltzmann Method is applied to predict the flow-induced noise from HVAC systems including blower and ducts and find noise sources. In order to validate the simulation result, acoustics measurements are performed on HVAC systems in an anechoic room and the results are compared to each other.
Technical Paper

Numerical Analysis of Aerodynamic Impact on Passenger Vehicles during Cornering

2018-05-30
2018-37-0014
Abstract Governmental regulations and increased consumer awareness of the negative effects of green-house gases has led the automotive industry to massive invest in the energy efficiency of its fleet. One way towards accomplishing reduced fuel consumption is minimizing the drag of vehicles by improving its aerodynamics. Fuel consumption is measured by standardized driving cycles which do not consider aerodynamic losses during cornering. It is uncertain whether cornering has a significant impact on the drag, and the present study intends to investigate this numerically, using a generic vehicle model called the DrivAer. The model is considered in two different configurations: the notchback and the squareback. Cornering in various radiuses is modelled using a Moving Reference Frame approach which provides the correct flow conditions when simulating a stationary vehicle where the wind and ground are moving instead.
Technical Paper

Effects on the Aerodynamic Characteristics of Vehicles in Longitudinal Proximity Due to Changes in Style

2018-05-30
2018-37-0018
Abstract The potential benefit for vehicles travelling in ‘platoon’ formations arises from a reduction in total aerodynamic drag which can result from the interaction of bluff bodies in close-proximity. During the 1980s this was considered as an opportunity to alleviate congestion and also for fuel-saving in response to the fuel crises of the 1970s. Early interest was limited partly due to the level of available control technology. But recent developments in vehicle-to-vehicle communication systems and autonomous driving technologies have provided the potential for platooning to be incorporated within future traffic management systems prompting renewed interest. For the investigation described in this paper, a new passenger car model was designed as the basis for determining the effectiveness of future low-drag styles in platoon formations. Small-scale models were tested in the Coventry University Wind Tunnel in platoons of up to 5 vehicles.
Technical Paper

Using Social Network Analysis to Quantify Interoperability and Versatility in the U.S. Air Force Network of Systems

2018-05-10
2018-01-6000
Abstract The Department of Defense (DoD) faces a similar challenge to the broader aerospace community in that they must integrate and operate a range of systems developed independently over a long period. It has proved difficult for the DoD to manage this network of systems and they must explore other options for analyzing and managing their systems. This paper explores the application of social network analysis tools and metrics to a network of aerospace systems within the U.S. Air Force. The structure of the network includes over one hundred U.S. Air Force systems including, aircraft, unmanned aerial vehicles, munitions, satellites, and command and control systems. The paper describes two separate networks based on direct connections and shared activities between these systems. For each of these networks measures of centrality, degree, closeness, betweenness, and eigenvector, quantify both the interoperability and versatility of the U.S. Air Force systems.
Technical Paper

Aviation Oxygen Safety Management System Analysis

2018-04-15
2018-01-6001
Abstract Oxygen has been a significant variable in flight operations for nearly 60 years. Today, the use of oxygen is almost synonymous with rocket, jet and turbo-prop operations affecting more than 45,000 aircraft worldwide. Today’s pilot flies farther, higher and longer than ever before, and does so at an ever increasing frequency. While the past 60 years have yielded tremendous advances in propulsion, avionics, materials and many other areas, oxygen and its role in aviation has remained largely stagnant. Although considered a major aircraft system and an essential component in high altitude operations, the orthodox mantra of ‘engineering it better’ has produced only limited results, most of them in the area of dispensation equipment (masks). In recent years Aeronautical Data Systems and collaborative entities have begun working to create a standardized and comprehensive aviation oxygen safety management system.
White Paper

The Use of Imaging for Powder Metal Characterization and Contamination Identification

2018-04-05
WP-0008
As AM technologies are being used with higher frequencywithin the automotive and aerospace industries, the interest in powder characterization and contaminant identification is growing—especially for suppliers looking to gain entry into these highly regulated industries. Standards for powder materials and methods used for aerospace applications are still be developed, and regulatory agencies such as the Federal Aviation Administration have been requesting that standards be developed as guidance for the industry. Methods such as CCSEM and HLS could be viable options for suppliers needing to adhere to a powder specification by demonstrating compliance. Solutions exist to integrate such methods into a production environment as exemplified by RJ Lee Group.
Technical Paper

Information Security Risk Management of Vehicles

2018-04-03
2018-01-0015
Abstract The results of this work is allowed to identify a number of cybersecurity threats of the automated security-critical automotive systems, which reduces the efficiency of operation, road safety and system safety. Wired or wireless access of the information networks of the modern vehicles allows to gain control over power unit, chassis, security system components and comfort systems. According to the evaluating criterion of board electronics, the presence of poorly-protected communication channels, the 75% of the researched modern vehicles do not meet the minimum requirements of cybersecurity due to the danger of external blocking of vital systems. The revealed vulnerabilities of the security-critical automotive systems lead to the necessity of developing methods for mechanical and electronic protection of the modern vehicle. The law of normal distribution of the mid-points of the expert evaluation of the cyber-security of a modern vehicle has been determined.
Technical Paper

Comparison of Duty-Cycle of a Lithium-Ion Battery for Electric Airplane and Electric Vehicle Applications

2018-04-03
2018-01-0666
Abstract In this study, the duty-cycle of a commercial lithium-ion battery (LIB) for a typical passenger airplane (Bombardier CRJ200) is obtained and compared to the duty- cycle of the same LIB for electric vehicles. For this purpose, the velocity and altitude of the airplane is monitored during a typical flight and the instantaneous mechanical power of the airplane is obtained by modeling. Based on the airplane required power and the characteristics of the LIB, a battery pack is designed for the airplane. Then, the duty-cycle of a LIB cell in the battery pack is yielded. The duty-cycle of the same LIB for a typical electric vehicle is also obtained from modeling based on the Highway Fuel Economy Test (HWFET), New York City Cycle (NYCC) and United States 2006 (US06) drive-cycles. Finally, the duty-cycle of the LIB for two different applications of electric airplane and electric vehicle is compared. The duty-cycles obtained in this study can be employed to study the lifespan of LIBs.
Technical Paper

Ground Landing Mechanisms in Vehicle-To-Pedestrian Impacts Based on Accident Video Records

2018-04-03
2018-01-1044
Abstract Accident data have shown that the pedestrian injuries resulting from contact with the ground are serious and may even be worse than the injuries resulting from the primary contact with the vehicle. The landing mechanisms, including the pedestrian trajectory and subsequent sequential body region contacts to the ground, are the basis for understanding the ground impact injuries of pedestrians. However, the landing mechanisms of pedestrian are too complicated to be categorized via investigation of the collision information after an accident has occurred. Nowadays, pedestrian kinematics after vehicle impacts can be observed from the accident videos that have been recorded by road monitoring and driver recorders. This study was aimed at investigating the pedestrian landing mechanisms and analyzing the influencing factors.
Technical Paper

Exergo-environmental Analysis of Basic and Intercooled-Recuperated Gas Turbine based Aviation Auxiliary Power Unit

2018-04-03
2018-01-1376
Abstract This paper deals with the exergo-environmental analysis of gas turbine with possible application as aviation auxiliary-power-unit (APU). The present work reports a comparison of thermodynamic performance, NOx and CO emission for basic gas turbine cycle (BGT) and intercooled-recuperated gas turbine (IcRcGT) cycle based engines for possible use by the aviation industry as auxiliary power unit (APU). In addition to this environmental sustainability index of these two cycles is also presented. Various cycle operating parameters such as compressor-pressure-ratio (rp,c), combustor-primary-zone-temperature, equivalence-ratio, and residence time have been chosen for analysis of the cycles. Mathematical modeling of the cycles has been done and the same have been coded in MATLAB. Results show that IcRcGT cycle exhibits higher gas turbine power output and gas turbine efficiency in comparison to BGT cycle for the same rp,c and turbine inlet temperature (TIT).
Technical Paper

Experimental Study on Diesel Spray Characteristics at Different Altitudes

2018-04-03
2018-01-0308
Abstract In this study, effects of altitude on free diesel spray morphology, macroscopic spray characteristics and air-fuel mixing process were investigated. The diesel spray visualization experiment using high-speed photography was performed in a constant volume chamber which reproduced the injection diesel-like thermodynamic conditions of a heavy-duty turbocharged diesel engine operating at sea level and 1000 m, 2000 m, 3000 m and 4500 m above sea level. The results showed that the spray morphology became narrower and longer at higher altitude, and small vortex-like structures were observed on the downstream spray periphery. Spray penetration increased and spray angle decreased with increasing altitude. At altitudes of 0 m, 1000 m, 2000 m, 3000 m and 4500 m, the spray penetration at 1.45 ms after start of injection (ASOI) were 79.54 mm, 80.51 mm, 81.49 mm, 83.29 mm and 88.92 mm respectively, and the spray angle were 10.9°, 10.8°, 10.7°, 10.4°and 9.8° respectively.
Technical Paper

Composite Springs for: Suspension Vehicles, Spacecraft Stage Separation, and Satellite Ejection on Orbit

2018-04-03
2018-01-0150
Abstract SARDOU SAS has developed highly stressed composites parts for 36 years. SARDOU SAS and QUALITY INDUSTRIAL PRODUCT jointly invented and patented composite “C” springs in 1993. We have designed and tested “C” springs, giving an energy density of 1350 Joules per kilogram (compared to 300 Joules for steel springs). This energy density means a potential 78% weight savings! But in the last century, weight savings was not a must and platform managers were reluctant to use anything else than coil springs. So in 2002, in order to comply with their wishes, we have invented and developed composite coils springs. Composite coils springs are the best choice for McPherson suspensions. We have identified that the weak point, in composite coils springs, is its epoxy matrix. During heavy loading, the matrix undergoes micro cracking. Then, during repeated loadings, micro cracks propagate and merge, transforming the matrix into a fine powder.
Technical Paper

Real-Time Path Correction of an Industrial Robot for Adhesive Application on Composite Structures

2018-04-03
2018-01-1390
Abstract Due to their unique and favorable properties as well as high strength to weight ratio, composite materials are finding increasing applications in automotive, aircraft and other vehicle manufacturing industries. High demand, production rates and increasing part complexity, together with design variations require fast, flexible and fully automated assembly techniques. In automotive and aircraft manufacturing, widely used bonding and sealing processes are automated using industrial robots due to their speed, flexibility and large working volume. However, there are limitations in achieving complete automation of these processes due to the inherent inaccuracies of the industrial robots, workpiece positioning and process tolerances. Currently, the robot programs are generated in CAD/CAM environment and are adjusted manually according to the actual workpiece.
Technical Paper

Comparison of 1-D Modelling Approaches for Wankel Engine Performance Simulation and Initial Study of the Direct Injection Limitations

2018-04-03
2018-01-1452
Abstract Recent interest in the possible use of Wankel engines as range extenders for electric vehicles has prompted renewed investigations into the concept. While not presently used in the automotive industry, the type is well established in the unmanned aerial vehicles industry, and several innovative approaches to sealing and cooling have recently been developed which may result in improved performance for ground vehicle applications. One such UAV engine is the 225CS, a 225 cc/chamber single-rotor engine manufactured by Advanced Innovative Engineering (UK) Ltd. To be able to analyse the parameters, opportunities and limitations of this type of engine a model was created in the new dedicated Wankel modelling environment of AVL BOOST. For comparison a second model was created using the established method of modelling Wankel engines by specifying an ‘equivalent’ 3-cylinder 4-stroke reciprocating engine.
Technical Paper

Determination of the Optimal Seat Profile Parameters for an Airplane Eco-class Passenger Seat

2018-04-03
2018-01-1324
Abstract An airplane passenger seat, like other seats in transportation, is used by thousands or millions of people. The seat should be designed to accommodate the maximum number of a target population by taking into account the variability of body size and also the environment’s constraints. Thanks to a fully adjustable experimental seat recently built at IFSTTAR, data of the preferred seat profile and compressed seat pan surface were collected in function of seat pan and backrest angle from a sample of 36 differently sized participants. Parametric models were obtained to predict optimal seat profile parameters in function of a sitter’s anthropometric characteristics, seat pan angle and seat back angle. Using a population simulation approach, a sample of 500 males and 500 females were generated randomly based on the distribution of relevant anthropometric dimensions.
X