Search Results

In today’s rapidly evolving automotive world, reduction of time to market has prime importance for a new product development. It is critical to have significant front-loading of the development activities to reduce development time while achieving best in class performance targets. Driver-in-the-loop (DIL) simulators have shown significant potential for achieving it, through real time subjective feedback at preliminary stages of the vehicle development. Recent advances in technology of driving simulators have enabled quite accurate representation steering and handling performance, also good prediction on primary ride and low frequency vibrations. In conventional damper development, the definition of the initial dampers tuning specifications typically requires a mule vehicle, or atleast, a comparable vehicle. However, this approach is associated with protracted iterations that consume substantial time and cost.

In order to realize the series-parallel switching control of hybrid electric vehicle (HEV) with dual-motor hybrid configuration, a method of unpowered interrupt switching based on the coordinated control of three power sources was proposed by analyzing the series-parallel driving mode of the dual-motor hybrid configuration. The series to parallel switching process is divided into three stages: speed regulation stage, clutch combination and power source switching. The distribution control of speed regulating torque is carried out in the speed regulating stage. The speed adjustment torque is preferentially allocated to the power source of the input shaft (engine and P1) to carry out the lifting torque. Due to the high speed adjustment accuracy and fast response of the P1 motor, the input shaft is preferentially allocated to P1 for speed adjustment, that is, the torque intervention of P1.

In order to solve the problems of the shuffle caused by internal and external excitation and the difficulty in obtaining the real-time accurate engine torque during the parallel mode operation of hybrid electric vehicles, a dynamic coordination control strategy for suppressing the jitter of hybrid electric vehicles based on the closed-loop control of engine speed was proposed. The engine torque filtering control method based on the slope limit was adopted to limit the rate of change of the engine torque and reduce the impact caused by the sudden change of the engine torque; the engine speed closed-loop control method was used to take the motor speed which is easy to be measured accurately in real time as the feedback control variable, which solved the problem of the real-time accurate estimation of the engine torque online. In parallel mode, the motor torque accounts for a small proportion because the torque distribution method gives priority to the engine.

Abstract : In any human space flight program, safety of the crew is of utmost priority. In case of exigency during atmospheric flight, the crew is safely and quickly rescued from the launch vehicle using Crew escape system. Crew escape system is a crucial part of the Human Space flight vehicle which carries the crew module away from the ascending launch vehicle by firing its rocket motors (Pitch Motor (PM), Low altitude Escape Motor (LEM) and High altitude Escape Motor (HEM)). The structural loads experienced by the crew escape system during the mission abort are severe as the propulsive forces, aerodynamic forces and inertial forces on the vehicle are significantly high. Since the mission abort can occur at anytime during the ascent phase of the launch vehicle, trajectory profiles are generated for abort at every one second interval of ascent flight time considering several combinations of dispersions on various propulsive parameters of abort motors and aero parameters.

Thermo-mechanical fatigue and natural aging due to environmental conditions are difficult to simulate in an actual test with the advanced fiber-reinforced composites, where their fatigue and aging behavior is little understood. Predictive modeling of these processes is challenging. Thermal cyclic tests take a prohibitively long time, although the strain rate effect can be scaled well for accelerating the mechanical stress cycles. Glass fabric composites have important applications in aircraft and spacecraft structures including microwave transparent structures, impact-resistant parts of wing, fuselage deck and many other load bearing structures. Often additional additively manufactured features and coating on glass fabric composites are employed for thermal and anti-corrosion insulations. In this paper we employ a thermo-mechanical fatigue model based accelerated fatigue test and life prediction under hot to cold cycles.

At the dawn of battery electric vehicles (BEVs), protection of automotive battery systems as well as passengers, especially from severe side impact, has become one of the latest and most challenging topics in the BEV crashworthiness designs. Accordingly, two material-selection concepts are being justified by the automotive industry: either heavy-gauge extruded aluminum alloys or light-gauge advanced high-strength steels (AHSSs) shall be the optimal materials to fabricate the reinforcement structures to satisfy both the safety and lightweight requirements. In the meantime, such a justification also motivated an ongoing C-STARTM (Cliffs Steel Tube as Reinforcement) Protection project, in which a series of modularized steel tube assemblies, were demonstrated to be more cost-efficient, sustainable, design-flexible, and manufacturable than the equivalent extruded aluminum alloy beams as BEV reinforcement structures.

In today's industrial sphere, machines are the key supporting various sectors and their operations. Over time, due to extensive usage, these machines undergo wear and tear, introducing subtle yet consequential faults that may go unnoticed. Given the pervasive dependence on machinery, the early and precise detection of these faults becomes a critical necessity. Detecting faults at an early stage not only prevents expensive downtimes but also significantly improves operational efficiency and safety standards. This research focuses on addressing this crucial need by proposing an effective system for condition monitoring and fault detection, leveraging the capabilities of advanced deep learning techniques. The study delves into the application of five diverse deep learning models—LSTM, Deep LSTM, Bi LSTM, GRU, and 1DCNN—in the context of fault detection in bearings using accelerometer data. Accelerometer data is instrumental in capturing vital vibrations within the machinery.

A and B stiffness coefficients to model the frontal stiffness of vehicles is a commonly used and accepted technique within the field of collision reconstruction. Methods for calculating stiffness coefficients rely upon examining the residual crush of a vehicle involved in a crash test. When vehicles are involved in a collision, portions of the crushed vehicle structures rebound from their maximum dynamic crush position. Once the vehicle structures have finished rebounding, the remaining damage is called the residual crush. A problem can arise when the plastic bumper cover rebounds more than the vehicle's structural components, resulting in an air gap between the structural components and the plastic bumper cover. Most modern New Car Assessment Program (NCAP) tests quantify crush in the test reports based on the deformed location of the plastic bumper cover and not the structural components behind the plastic bumper cover. This results in an underreporting of the actual residual crush.

Analytical computer simulations were used to optimize and fabricate an Advanced Integrated Safety Seat (AISS) for frontal, rear, side, and rollover crash protection. The AISS restraint features included: dual linear recliners, pyrotechnic lap belt pretensioner, 4 kN load-limiter, extended head restraint system, rear impact energy absorber, seat-integrated belt system, and side impact air bag system. The evaluation and optimization of the AISS design was achieved through analytical simulations using MADYMO multi-body analysis software, LS-DYNA3D finite element software, and through LS-DYNA3D/MADYMO coupling. Frontal and rear impact sled tests were also conducted with physical AISS prototypes and baseline integrated seats to verify performance. Both the analytical modeling and the experimental sled testing demonstrated safety improvements over the baseline integrated seat.

The NHTSA notices of proposed rulemaking on side impact protection have focused worldwide attention on one of the most difficult and frustrating efforts in automobile crash safety. Traditional vehicle design has evolved obvious structural contrasts between the side of the struck vehicle and the front of the striking vehicle. Protection of near-side occupants from intruding door structure is a most perplexing engineering challenge. Much useful and insightful engineering work has been done in conjunction with NHTSA's proposed rulemaking. However, there are many major engineering issues which demand further definition before reasonable side impact rulemaking test criteria can be finalized. This paper reviews recent findings which characterize the human factors, biomechanics, and occupant position envelope of the typical side impact crash victim.

Immediate collision hazards pose obvious threats to approaching drivers and therefore provoke emergency evasive responses. When the hazard is a vehicle intruding into the lane ahead, how its movement characteristics influence an approaching driver’s response is not well understood. This study examined the relationship between intruding vehicle motion and hazard perception. Seventeen subjects viewed first-person perspective recordings of a simulated vehicle travelling down a two-lane roadway containing several intersections with stop-controlled minor roads. Stopped vehicles were located at approximately half of the minor road intersections. Throughout the study, some vehicles (termed ‘intruders’) accelerated into the subject’s lane of travel at 1 of 6 pre-determined acceleration rates. Subjects were instructed to ‘brake’ their vehicle by pressing the space bar on a keyboard as soon as they perceived that a collision was imminent.

Leveraging the power of math models in driveline development requires a deeper appreciation for the multi-disciplinary and wide ranging physical system dynamic behaviors involved. The models have to handle operational demands of multi-configurable systems brought on by hybrid powertrains in general and automatic/manual transmissions, specifically. As a first requirement, system models have to be broken down into physically compatible subsystems, not as the hardware looks but, as the interface dynamics suggest. Transient dynamics, brought on by subsystem power flow disturbances and attendant noise generation and controls challenges must be addressed up front. This paper delves into the levels of detail automotive propulsion system models must possess not only to offer insight to the inner dynamics of a product but, also, make such formulation compatible with modern control system techniques.

Five years ago, a new experiment in passenger air transportation for Atlantic Ocean crossings was introduced. It was given the acronym known as ETOPS and involves the development of passenger aircraft having only two-engines utilized for flights over such critical routes. The essence of the concern generated in this study is summarized by the safety analysis of Dr. Robert Besco, who states, “ETOPS is troublesome because the failure of only one system on an aircraft [In this case an engine] should not cause that aircraft to have to operate under emergency conditions.” Previously, a major cornerstone of civil aviation safety was the concept of providing multiple engine redundancy with a minimum of three-engines required for such critical flights.

This paper is the first in a series of documents designed to record the progress of the SAE J2293 Task Force as it continues to develop and refine the communication requirements between Plug-In Electric Vehicles (PEV) and the Electric Utility Grid. In February, 2008 the SAE Task Force was formed and it started by reviewing the existing SAE J2293 standard, which was originally developed by the Electric Vehicle (EV) Charging Controls Task Force in the 1990s. This legacy standard identified the communication requirements between the Electric Vehicle (EV) and the EV Supply Equipment (EVSE), including off-board charging systems necessary to transfer DC energy to the vehicle. It was apparent at the first Task Force meeting that the communications requirements between the PEV and utility grid being proposed by industry stakeholders were vastly different in the type of communications and messaging documented in the original standard.

Executive Order No. 12291 requires that the federal regulatory agencies undertake a cost-benefit analysis of any proposed social regulation to show that its benefits exceed its costs. This paper outlines the essential elements of a cost-benefit analysis; describes the key regulatory actors, namely Congress, the Office of Management and Budget, and the regulatory agencies; assesses the quality of the regulatory analyses performed under the Order; and concludes by offering ten recommendations to improve social regulation. On February 17, 1981, within a month of entering office, President Reagan issued Executive Order No. 12291 as part of his program for regulatory reform.

A supervisory Model Predictive Control (MPC) approach is developed for an air path system for multi-mode operation in a diesel engine. MPC is a control method based on a predictive dynamic model of system and determines actuator control positions through the optimization of various factors such as tracking performances of target setpoints, moving speed of actuators, limits, etc. Previously, linear MPC has been successfully applied on the air path control problem of a diesel engine, however, most of these applications were developed for a single operation mode which has only one set of control target setpoint values. In reality, a single operation mode cannot cover all requirements of current diesel engines and this complicates practical implementations of linear MPC. The high priority targets for the development of diesel engines are low emissions, high thermal efficiency and robustness.

Advanced Traffic Management Systems (ATMS) provide the means for local transportation officials to monitor traffic conditions, adjust traffic operations, and respond to accidents. By providing early traffic incident detection and management, and by redistributing traffic to less congested portions of the highway network, ATMS can influence vehicle operators' route choices. COMPASS, a state-of-the-art advancedtraffic managementsystemimplemented in the Metropolitan Toronto area, has adopted most of the Intelligent Vehicle-Highway Systems (IVHS) technologies. This paper describes the logic and implementation of the automatic incident detection for COMPASS. The purpose of incident detection is to identify the potential occurrence of incidents in a traffic stream by analyzing the flow characteristicsof the traffic stream. The output of the incident detection function will form the basis for incident verification by the operator and implementation of traffic response plans.

The Marshall Space Flight Center (MSFC) has been given the responsibility for conceptual development of the Geostationary Earth Observatory (GEO) element of NASA's Mission to Planet Earth program. Because these multi-instrument geostationary satellites will orbit over given points on the ground, they will each provide continuous observation of large regions of the Earth and will complement other data gathering facilities in low Earth orbit (LEO) such as the polar platforms of the Earth Observing System (EOS) and the Earth Probe satellites which operate in a variety of specialized LEO's. These various systems will operate over a 15-year period to obtain data with unprecedented global and temporal coverage. Because of their Earth-fixed position, the GEO instruments will provide high temporal resolution while the LEO instruments will provide data having higher spatial and spectral resolution.

The “new generation” of large satellites like ERS-1 requires modular thermal balance testing due to the physical size. The purpose of this paper is to outline the experience gained from the ERS-1 Payload Thermal Balance Test. The first part of the paper highlights the test set-up, the earthshine compensation and the selected test phases. The second part describes the temperature uncertainty approach and test correlation criteria defined for the thermal analyses and tests. The third part concentrates on the test correlation with emphasis on the thermo-optical properties of the Optical Solar Reflectors (OSRs) in the Xenon light of the simulated sun and the temperature dependent linear conductance of the honeycomb core material which played a crucial role in explaining a temperature level offset. The paper is understood as complement to the paper presented in 1987 - Thermal Control and Design of the ERS-1 Payload -.

Tyres play a crucial role in determining the ride and handling properties of a vehicle. Multi-body simulation softwares are being used extensively to understand vehicle ride and handling properties using detailed vehicle models. Models need a set of characteristics and parameters to represent the tyre as close as possible to the actual tyre. Tyre properties are generally grouped into vertical, lateral and longitudinal stiffness characteristics. Various test facilities are currently present in educational institutions and commercial organizations. They are prohibitively expensive to use during product development stage where a number of design iterations are carried out before finalizing for mass production. This paper highlights the work done in creating innovative and simplified test facilities for measuring lateral force characteristics, static vertical, lateral and longitudinal stiffness and dynamic vertical stiffness and damping.