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The application of oxidation catalyst and particulate filter technology for the reduction of particulate matter (PM), hydrocarbons (HC) and carbon monoxide (CO) emissions from heavy duty diesel engines has become an established practice. The design and performance of such systems have been commercially proven to the point that the application of these technologies is cost effective and durable. The application of an effective NOx reduction technology in heavy duty diesel applications is more complicated since there are no passive NOx reduction technologies that can be fit onto HDD vehicles. However, Selective Catalytic Reduction (SCR) systems using Urea injection to achieve NOx reduction have become the technology of choice in Europe and have been applied to achieve Euro IV emissions levels on new HDD vehicles. In addition, retrofit SCR emission control systems have also been developed that can provide high NOx reduction when applied on existing HDD vehicles.

This paper describes recent progress in our program to develop an emissions technology allowing diesel engines to meet the upcoming stringent worldwide regulations for NOx. The Plasma Fuel Reformer (PFR) has the ability to rapidly convert diesel fuel (with air), to a hydrogen rich gas on-board a vehicle, which is then utilized to efficiently regenerate a NOx trap. We have made several advances on the PFR as well as on the NOx reducing system. The Plasma Fuel Reformer operating range has been extended by 120% up to 1.5 g/s fuel flow rate while retaining the high hydrogen and low soot characteristics. The plasma power consumption has been further reduced and the high voltage design has been made more robust. The T90 start-up time during regenerations has been reduced to less than 4 seconds. The NOx reducing system utilizes a novel algorithm for NOx trap regeneration that reduces the fuel penalty by 25% while increasing NOx conversion by 10%.

The cost of fuel for commercial trucks is second only to labor in the total vehicle operating costs. Therefore, technologies that reduce fuel consumption can have a significant impact on the bottom line for both trucking fleets and owner/operators. Quantifying the fuel savings associated with different technologies, however, is complicated by many factors, and short-term testing often cannot adequately quantify small changes in fuel consumption that, over time, can add up to substantial cost savings on a vehicle. For example, fuel economy gains of less than one percent may not be reliably measurable using fuel tests, and variable environmental and use factors can cast some doubt on the appropriateness of short-term testing.

The EPA is developing a new generation emissions inventory model, MOVES (Motor Vehicle Emissions Simulator). The first version of the model outputs fuel consumption based on available modal data. However, due to the limited heavy-duty vehicle data, MOVES pollutant (CO, HC, NOx) emission rates will need to be supplemented with rates determined with the Physical Emission Rate Estimator (PERE). PERE combines vehicle tractive power together with vehicle powertrain parameters specific to the class of vehicle; the vehicle weight, shape, engine type, and transmission. Analysis of in-use data for heavy-duty diesel tractor-trailer vehicles, city transit diesel buses, and dynamometer non-road diesel engines has enabled a determination of diesel engine friction and indicated efficiency and transmission shift schedules for these engines and vehicles. These model parameters and a comparison of the model results to measured fuel consumption and CO2 emissions are presented.

Automotive drive shafts, which transmit power from the transmission unit to the rear axle are in general straight round tubes. An attempt has been made to explore other possible cross-sectional shapes to improve NVH (Noise Vibration and Harshness) performance. The first natural frequency is a very good indicator of the NVH performance. First, finite element based topology optimization and later topography optimizations were tried out. A number of design solutions were obtained from the study and a comparison has been made. A round drive shaft with a bulge at the center has been proposed for stiffenening the drive shaft to improve the first natural frequency.

We hypothesize that components designed to improve fuel economy by reducing power requirements should also result in a decrease in emissions of oxides of nitrogen (NOx). Fuel economy and NOx emissions of a pair of class 8 tractor-trailers were measured on a test track to evaluate the effects of single wide tires and trailer aerodynamic devices. Fuel economy was measured using a modified version of SAE test procedure J1321. NOx emissions were measured using a portable emissions monitoring system (PEMS). Fuel consumption was estimated by a carbon balance on PEMS output and correlated to fuel meter measurements. Tests were conducted using drive cycles simulating highway operations at 55 mph and 65 mph and suburban stop-and-go traffic. The tests showed a negative correlation (significant at p < 0.05) between fuel economy and NOx emissions. Single wide tires and trailer aerodynamic devices resulted in increased fuel economy and decreased NOx emissions relative to the baseline tests.

Ground vehicle mobility models in U.S. Army entity-level force-on-force simulations have largely been tailored to the specific application (e.g., Janus, Close Combat Tactical Trainer [CCTT], Modular Semi-Automated Forces [MODSAF], OneSAF Testbed Baseline [OTB]). The NATO Reference Mobility Model (NRMM) is the Army standard model for single ground vehicle performance. However, it is much too complex and is not designed for use in entity-level simulations. Janus uses lookup tables based on NRMM speeds, and CCTT uses forces derived from algorithms internal to NRMM. The U.S. Army is developing two new entity-level simulations: CombatXXI and the One Semi-Automated Forces Objective System (OOS), which both have requirements to use NRMM as the basis for their ground vehicle mobility calculations. The U.S. Army Engineer Research and Development Center teamed with the U.S.

In automotive industry inserting cardboard liners or foam in the dirveshaft to prevent them from functioning as a path or amplifier to high frequency gear whine excitation is a common practice. Due to limited damping capability, these liners, however, have limited effectiveness and may not prevent or effectively reduce the shaft radiated noise. This paper addresses the feasibility and performance of polymers as an alternative lining material and technique. Through experimental investigations it has been shown that the polymer liners in reducing the driveshaft radiated noise are more effective than the cardboard liners.

The Future Combat System Operational Requirements Document requires that manned and unmanned ground vehicles be capable of negotiating gaps 1.5- to 4.0-meters wide. Gaps include both natural and manmade obstacles. Overcoming battlespace gaps requires the ability to effectively conduct four tasks: prediction, definition, avoidance, and defeat. The inability to overcome gaps within the theater of operations will significantly impair the Future Force's responsiveness, agility, and sustainability. Researchers at the US Army Engineer Research and Development Center (ERDC), working in the field of vehicle mobility have developed methods to predict the physical interactions of vehicles with terrain mechanics. This physics-based simulation method uses research conducted at the ERDC to combine historical empirical laboratory and field evaluations with lumped parameter and numerical analysis to develop a simulated environment of the terrain.

Three-dimensional models of real world terrain have application in a variety of tasks, but digitizing a large environment poses constraints on the design of a 3D scanning system. We have developed a Mobile Scanning System that works within these constraints to quickly digitize large-scale real world environments. We utilize a mobile platform to move our sensors past the scene to be digitized - fusing the data from cm-level accuracy laser range scanners, positioning and orientation instruments, and high-resolution video cameras - to provide the mobility and speed required to quickly and accurately model the target scene.

A methodology has been developed to generate military vehicle driving cycles for use in vehicle simulation models. This methodology is based upon the mission profile for a vehicle, which is typically given within a vehicle's specifications and lists the types of terrains that the vehicle is likely to encounter. A simplistic vehicle powertrain and road load model and the Bekker vehicle-soil interaction model are used to estimate the vehicle performance over each type of terrain. Two types of driving cycles are generated within a Graphical User Interface developed within MATLAB using the results of the vehicle models: Linear modes driving cycles, and Real-world driving cycles.

One fundamental difficulty in understanding the physics of the off-road traction and in predicting vehicle performance is the variability of the terrain profile and soil parameters. These operating conditions are uniquely defined at a given spatial location and a given time. It is not practically feasible, however, to measure them at a sufficiently large number of points to be able to accurately represent the terrain in models. This renders traditional analysis tools insufficient when dealing with rough deformable terrain. We employ stochastic analysis to capture the uncertain nature of this running support and the corresponding vehicle response. From a finite number of observations the terrain profile and soil properties can be modeled as random processes, with the actual operating conditions viewed as a particular realization of these processes. Soil parameters vary substantially from one type of soil to another.

The 1/8-scale Generic Conventional Model was studied experimentally in two wind tunnels at NASA Ames Research Center. The investigation was conducted at a Mach number of 0.15 over a Reynolds number range from 1 to 6 million. The experimental measurements included total and component forces and moments, surface pressures, and 3-D particle image velocimetry. Two configurations (trailer base flaps and skirts) were compared to a baseline representative of a modern tractor aero package. Details of each configuration provide insight into the complex flow field and the resulting drag reduction was found to be sensitive to Reynolds number.

Aerodynamic drag, lift, and side forces have a profound influence on fuel efficiency, vehicle speed, stability, acceleration and performance. All of these areas benefit from drag reduction and changing the lift force in favor of the operating conditions. The present study simulates the external flow field around a heavy truck with three prototype add-on drag reduction devices using a computational method. The model and the method are selected to be three dimensional and time-dependent. The Reynolds-averaged Navier Stokes equations are solved using a finite volume method. The Renormalization Group (RNG) k-ε model was elected for closure of the turbulent quantities. The run cases were chosen so that the influence of each drag reduction device could be established using a regression model from a Design of Experiments (DOEX) derived test matrix.

An investigation is made to the multiobjective suspension control problem for a heavy off-road vehicle based on mixed H2/H ∞ optimal control synthesis. A design procedure is explained based on a performance trade-off curve in order to solve this problem. In comparison with other control synthesis results we have obtained, it is shown that by combining both techniques into one mixed norm optimization framework, it is possible to exploit the strengths of each norm to provide better performance for the given hydropneumatic suspensions.

The National Highway Traffic Safety Administration (NHTSA) realizes that medium and heavy vehicles have different issues than passenger vehicles with respect to tire pressure monitoring. The NHTSA did not have time during the one year deadline imposed by the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act to address these complex concerns in its rulemaking.1 This paper explores the unique concerns that accompany commercial vehicle tire pressure monitoring and management that must be considered before a potential regulation for the commercial vehicle industry can be implemented successfully.

Understanding the parameters which influence the tendency for a heavy truck to exhibit rollover is of paramount importance to the trucking industry. Multiple parameters influence the vehicle’s motion, and the ability to determine how each affects the vehicle as a system would be an indispensable tool for the design of such vehicles. To be able to perform such predictions and analysis, models and a computer simulation were created to allow the examination of changes in design parameters in such vehicles. The vehicle model was originally developed by Law [1] and presented in Law and Janajreh [2]. The model was extended further by Lawson [3, 4] to include (a) the effects of the torsional compliance of both the tractor and trailer, and (b) tanker trailers with various levels of liquid fill. In the present paper, both the tractor and trailer compliances were studied independently to determine their influences on the rollover stability of the vehicle.

As a result of increased demand on the range of cargo types that U.S. military tactical trucks must transport, the effect of variations in the mass properties of the cargo on the roll stability of the trucks has become a serious issue. Vehicle dynamics experiments were conducted to obtain roll stability measurements for a tactical cargo truck hauling a broad range of rigid cargo loadings. A simple statics analysis for roll stability and the data obtained during the vehicle dynamics experiments were used to evaluate the relationship between the roll stability of the truck and the mass properties of the cargo. The results of the evaluation demonstrated that roll stability, quantified as the lateral acceleration at the wheel-liftoff threshold, can be accurately characterized as a function of: (1) the lateral center of gravity over the vertical center of gravity and (2) the longitudinal center of gravity over the wheelbase length.

This paper introduces a concept of predictive active safety by means of a full redundant architecture with the driver, from the perception of the environment to the vehicle controllers. The bottleneck of the current driver-vehicle association will be analyzed first. Then a virtual driver and the safety envelope of the different maneuvers will be described. A decision control will be presented that it matches the driver's command in this safety envelope. It is designed to give adequate feedback to the driver and can safely perform the command to the optimum of the chosen maneuver.

Several mechanical demining machines employ flails as the key mechanism for neutralizing landmines. Typically, flail systems consist of a rotating drum with a series of long chains with masses attached at the end. These masses strike and mill the ground that detonates and/or fragment buried landmines. Despite flail-based technology existing for several years in the demining field, minimal studies regarding the interaction with soil have been conducted. Three chain flail systems were evaluated in the soil bin at various rotational speeds. High speed videography of single pass operations indicated that a consistent and repeatable cleared path was not obtainable. This validated the need for multiple passes to effectively clear a minefield. The results were compared with the Mine Hammer mechanism that had consistent impacts on the surface. The load distribution at the various depths was recorded and the magnitude of the impulses calculated varied with depth and level of soil compaction.