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A new realistic motion control algorithm for digital human models is presented in this paper based on the principle of effort minimization. The proposed algorithm is developed through an innovative mathematical model to make the applications more flexible and more global, especially for the visualization of human motions in automotive assembly operations. The central idea of this unique model is to interpret the solution of the homogeneous Lagrange equation for a mannequin as the origin of dynamic motion. Furthermore, a digital human possesses about 42 joints over the main body except the head, fingers and toes, and offers a large room of kinematic redundancy. We have found 14 new 3-D independent motion markers assigned over the human body to constitute a Cartesian coordinate system, under which a minimum-effort based dynamic control scheme is developed using a state-feedback linearization procedure.

With the increasing emphasis on Systems Engineering, there is a need to ensure that Electrical/Electronic (E/E) Systems Endurance Testing of vehicles, in a real world environment, prior to Production Launch, is performed in a manner and at a technological level that is commensurate with the high level of electronics and computers in contemporary vehicles. Additionally, validating the design and performance of individual standalone electronic systems and modules “on the bench” does not guarantee that all the permutations and combinations of real-world hardware, software, and driving conditions are taken into account. Traditional Proving Ground (PG) vehicle testing focuses mainly on powertrain durability testing, with only a simple checklist being used by the PG drivers as a reminder to cycle some of the electrical components such as the power window switches, turn signals, etc.

The Hybrid III family of dummies is used to estimate the response of an occupant during a crash. One recent area of interest is the response of the neck during air bag loading. The biomechanical response of the Hybrid III dummy's neck was based on inertial loading during crash events, when the dummy is restrained by a seat belt and/or seat back. Contact loading resulting from an air bag was not considered when the Hybrid III dummy was designed. This paper considers the effect of air bag loading on the 5th percentile female Hybrid III dummies. The response of the neck is presented in comparison to currently accepted biomechanical corridors. The Hybrid III dummy neck was designed with primary emphasis on appropriate flexion and extension responses using the corridors proposed by Mertz and Patrick. They formulated the mechanical performance requirements of the neck as the relationship between the moment at the occipital condyles and the rotation of the head relative to the torso.

This paper contains a review of methods for deriving risk curves from biomechanical data obtained from impact experiments on human surrogates. It covers many of the problems and pitfalls of obtaining realistic human risk curves from impact experiments. The strength and weakness of both parametric and non-parametric methods are evaluated. The limitations of standard analysis of censored impact test data are presented. Methods are given for determining risk curves from both doubly censored data and data obtained from impacts to body regions in which there are more than one mechanism of injury. A detailed set of examples is presented in which different experimental data are analyzed using the Consistent Threshold method and the logistic approach. Finally risk curves for published data are presented for the femur, head, thorax, and neck.

The Portable Life Support System (PLSS) emergency oxygen system is being reexamined for the next generation of suits. These suits will be used for transit to Low Earth Orbit, the Moon and to Mars as well as on the surface of the Moon and Mars. Currently, the plan is that there will be two different sets of suits, but there is a strong desire for commonality between them for construction purposes. The main purpose of this paper is to evaluate what the emergency PLSS requirements are and how they might best be implemented. Options under consideration are enlarging the tanks on the PLSS, finding an alternate method of storage/delivery, or providing additional O2 from an external source. The system that shows the most promise is the cryogenic oxygen system with a composite dewar which uses a buddy system to split the necessary oxygen between two astronauts.

The damping loss factor of a structural panel plays a significant role in its vibro-acoustic performance. The objective of this paper is to present a new procedure for evaluating the damping loss factors of these panels. Traditionally, the damping loss factors are determined by using the decay rate of the decay curves which are experimentally obtained from the structure. However, this is time consuming and the accuracy is limited by fluctuations in the decay curve. In this paper, the envelope signal of each decay curve is determined through its Hilbert transform, and the remaining small fluctuations in the envelope signal are further smoothed out by the exponential average method. Finally, the damping loss factor is estimated based on the smoothed envelope signal of each decay curve. A computer program has been developed to implement this procedure. It is shown that this procedure improves both accuracy and efficiency of the decay rate method for estimating damping loss factor.

The pulse severities from various vehicle impact tests need to be assessed during the impact structure development and targeting stage to assure that the occupants can meet the injury criteria as required. The conventional method using TTZV (time to zero velocity), TDC (total dynamic crush), and G1/G2 (two stage averaged pulse) is often unable to give a quick and clear answer to the question being raised. A simple numerical tool is developed here to assess the pulse severity with a single parameter in which the severity is expressed as the amount of chest travel under a certain target restraint curve or chest A-D curve. The tool is applied to several front impact vehicle pulses to show the effectiveness. The new method developed here can be used to assess the pulse severity in an easy and objective way along with conventional parameters.

The problem of predicting the quality of weld is critical to manufacturing. A great deal of data is collected under multiple conditions to predict the quality. The data generated at Daimler Chrysler has been used to develop a model based on grammatical evolution. Grammatical Evolution Technique is based on Genetic Algorithms and generates rules from the data which fit the data. This paper describes the development of a software tool that enables the user to choose input variables such as the metal types of top and bottom layers and their thickness, intensity and speed of laser beam, to generate a three dimensional map showing weld quality. A 3D weld quality surface can be generated in response to any of the two input variables picked from the set of defining input parameters. This tool will enable the user to pick the right set of input conditions to get an optimal weld quality. The tool is developed in Matlab with Graphical User Interface for the ease of operation.

Integration of the water and air treatment systems in confined habitats for extended duration space missions will require characterization of the constituents in the gases produced by biological water processors. A membrane bioreactor was constructed to accomplish nitrification as part of a denitrification-nitrification biological water processor to treat a simulated early planetary base wastewater. A gas chromatograph was installed inline to the influent and effluent gas lines of the membrane bioreactor to monitor nitrogen, oxygen, carbon dioxide and nitrous oxide. The inline monitoring system enabled sampling of gas effluent from the lumen of the membranes and from a gas-liquid separator. Mass flow of the gas streams was also measured to enable calculation of the mass flow rates of the four inorganic gases.

Automotive electronics and software is getting complex day by day. More and more features and functions are offered and supported by software in place of hardware. Communication is carried out on the CAN bus instead of hard wired circuits. This architectural transition facilitates lots of flexibility, agility and economy in development. However, it introduces risk of unexpected failures due to insufficient testing and million of possible combinations, which can be created by users during the life time of a product. Model based development supports an effective way of handling these complexities during simulation and also provide oracle for its validation. Based on priorities and type of applications, test vectors can be auto generated and can be used for formal verification of the models. These auto-generated test vectors are valuable assets in testing and can be effectively reused for target hardware (ECU) verification.

In embedded software world, development and testing are becoming far more complex with growing functionality and fail safe strategies. As a result of that, model-based software development is getting increasingly popular in capturing the functional requirements and auto generating the code from these validated models to avoid any functional deficiency. However, the complexity in the model may not be correctly interpreted by the code generation tool and may result to an incorrect code behavior. In this paper, a methodology has been proposed and implemented to validate the generated code against the models. Simulation test scripts are recorded in the modeling environment to generate the desired set of test inputs. These input scripts are designed to get complete transition and state exposure to maximize the functional coverage. With these test scripts, expected outputs are recorded for downstream validation in the simulation environment with mature models.

It is commonly known that in an automotive manufacturing assembly line several workers perform either a common task or a number of different tasks simultaneously, and there is a need to represent such a multi-worker operation realistically in a digital environment. In the past years, most digital human modeling applications were limited only in a single worker case. This paper presents how to simulate multi-worker operations in a digital workcell. To establish an effective communication and interaction between the mannequins, some existing commercial software package has provided a digital input/output mechanism. The motion for each mannequin is often programmed independently, but can be interrupted anytime by the other digital human models or devices via a communication channel.

To mitigate head impact injuries of vehicle occupants in impact accidents, the FMVSS 201 requires padding of vehicle interior so that under the free-moving-head-form impact, the head injury criterion (HIC) is below the limit. More recently, pedestrian head impact on the vehicle bonnet has been a subject being studied and regulated as requirements to the automobile manufacturers. Over the years, the square wave has been considered as the best waveform for head impacts, although it is impractical to achieve. This paper revisits the head impact topic and challenges the optimality of aiming at the square waveform. It studies several different simple waveforms, with the objective to achieve minimal HIC or minimal crush space required in head-form impacts. With that it is found that many other waveforms can be more efficient and more practical than the square wave, especially for the pedestrian impact.

In this paper, we study the sensitivity of a vehicle impact harshness (IH) performance to the suspension bushing rates. A mid-sized uni-body SUV is selected for this study, with the acceleration responses at the driver seat track and the steering wheel as objective functions. A sensitivity study is conducted using an ADAMS full vehicle model including a tire model and flexible body structure representation over an IH event. The study resulted in the identification of key bushings that affect the IH performance and its sensitivity to the bushing rates. Based on the results, we came-up with an “optimal” bushing set that minimizes impact harshness, which was subjectively verified to result in significant improvement in IH.

Buffeting is a wind noise of high intensity and low frequency in a moving vehicle when a window or sunroof is open and this noise makes people in the passenger compartment very uncomfortable. In this paper, side window buffeting was simulated for a typical SUV using the commercial CFD software Fluent 6.0. Buffeting frequency and intensity were predicted in the simulations and compared with the corresponding experimental wind tunnel measurement. Furthermore, the effects of several parameters on buffeting frequency and intensity were also studied. These parameters include vehicle speed, yaw angle, sensor location and volume of the passenger compartment. Various configurations of side window opening were considered. The effects of mesh size and air compressibility on buffeting were also evaluated. The simulation results for some baseline configurations match the corresponding experimental data fairly well.

This paper describes the performance improvement and cost savings achieved by the Stamping Technology Department at DaimlerChrysler Corporation (Chrysler group), in migrating from Unix workstations with RISC technology to Linux PCs with Intel Pentium technology. Performance comparisons of various engineering applications running on these two system configurations are analyzed. The major aspects such as hardware configuration, operating system, software availability, compatibility, reliability, accuracy and consistency of simulation results are discussed. The improvement in computing speed and deviations in simulation results between MPP LS-Dyna and SMP LS-Dyna are presented.

In September 2003, the Mercedes Car Group set another milestone by introducing the fifth generation of automatic transmissions developed and manufactured in-house since 1960. The world's first 7-speed automatic transmission 7G-TRONIC is featured in the Mercedes-Benz S, SL, CL and E-Classes with V8 gasoline engines. Deduced from the demands of the requirement specifications, the 5-speed automatic transmission was decisively improved; the result is a clear increase in spontaneity, agility, fuel economy, and driving comfort for the customer. And because of the harmony between the vehicle and its powertrain, excellent results in the areas of performance, reduced emissions, comfort, and acoustics are obtained.

A traction test machine, developed for evaluation of traction-CVT fluids for the automotive consortium, USCAR, provides precision traction measurements to stresses up to 4 GPa. The high stress machine, WAMhs, provides an elliptical contact between AISI 52100 steel roller and disc specimens. Machine stiffness and positioning technology offer precision control of linear slip, sideslip and spin. A USCAR traction test methodology includes entrainment velocities from 2 to 10 m/sec and temperatures from -20°C to 140°C. The purpose of the USCAR machine and test methodology is to encourage traction fluid development and to establish a common testing approach for fluid qualification. The machine utilizes custom software, which provides flexibility to conduct comprehensive traction fluid evaluations.

NVH targets for future vehicles are often defined by utilizing a competitive benchmarking vehicle in conjunction with an existing production and/or reference vehicle. Mode management of full vehicle modes is one of the most effective and significant NVH strategies to achieve such targets. NVH dynamic characteristics of a full vehicle can be assessed and quantified through experimental modal testing for determination of global body mode resonance frequency, damping property, and mode shape. Major body modes identified from full vehicle modal testing are primarily dominated by the vehicle's body-in-white structure. Therefore, an estimate of BIW modes from full vehicle modes becomes essential, when only full vehicle modes from experimental modal testing exist. Establishing BIW targets for future vehicles confines the fundamental NVH behavior of the full vehicle.

This paper presents a new approach to improve occupant response in a front impact event. Instead of designing a vehicle structure for maximum structural efficiency and safety and then engineer a restraint system for the vehicle, this paper proposes to use a systems approach. In this approach, the vehicle structural response during impact (i.e., pulse) and the restraint system are considered together in the optimization process. In this paper, the 35 mph front impact into a rigid barrier with belted occupants, which is the NHTSA NCAP test, will be used to demonstrate the proposed new approach.