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The success of agricultural and construction machinery owes a great deal to the effective use of fluid power. Most fluid power systems are configured with a positive displacement fluid pump that is large enough to meet the flow requirements of many work circuits. Different work functions require a variety of fluid flow and pressure values to provide the desired operation. System branches, therefore, must include specialized flow and pressure regulating valves. The development of a mathematical model of a fluid flow control valve follows.

Multidimensional numerical simulations are performed to predict and optimize engine performance of a spark-ignited natural gas engine. The effects of swirl and combustion chamber geometry on in-cylinder turbulence intensity, burning rate and heat transfer are investigated using the KIVA multidimensional engine simulation computer code. The original combustion model in the KIVA code has been replaced by a model which was recently developed to predict natural gas turbulent combustion under engine-like conditions. Measurements from a constant volume combustion chamber and engine test data have been used to calibrate the combustion model. With the numerical results from KIVA code engine thermal efficiencies were predicted by the thermodynamics based WAVE code. The numerical results suggest alternative combustion chamber designs and an optimum swirl range for increasing engine thermal efficiency.

Presented in this paper is a nonlinear modeling and a controller design methodology for engine control. For illustrative purposes, the methodology is applied to the idle speed of a Ford 4.6L-2 valve V-8 fuel injected engine. The nonlinear model of the engine is based on a Hammerstein type model which is identified through input-output data without a priori knowledge of the engine dynamics. The nonlinear model is subsequently used in a frequency domain controller design methodology to achieve the performance goal of maintaining the engine idle speed within a prespecified asymmetric output tolerance despite external torque disturbances. An experimental verification of the proposed control law is included.

Automotive seat systems function primarily in a dynamic environment. Traditionally, seat manufacturers have focused on the safety and static comfort aspects of seating. The dynamic response of a seat and its influence on ride comfort was overlooked. However, recent trends in the industry clearly suggest an increased emphasis on such diverse issues as human response to vibration, seat ride quality and the influence of seat dynamic response on auto body dynamics. Seat cushion deflection is one of the objective parameters which can be effectively utilized for improving comfort and ride quality. In this study, an attempt was made to explain the role of seat cushion deflection for improving comfort and ride quality. Further, this study highlights how various static and dynamic comfort parameters are related to the cushion deflection characteristics of the seat system.

The architecture of a monolithic, dual axis, low cost surface micromachined [1] accelerometer is described, initial characterization results are presented, and issues surrounding the intended application are discussed. While the fabrication technology for the integrated mechanical sensor and electronics is essentially the same as that which supported earlier single axis products [2] [3] [4] [5] [6], a fundamentally different circuit architecture leads to much more compact and higher performance second generation devices. Compared to available bulk micromachined accelerometer sensors, surface micro-machined sensors are typically 20X smaller (0.58 mm x 0.66 mm) and have a natural axis of sensitivity (in the plane of the chip) that facilitates multi-axis sensing.

This study addresses the subjective assessment by the objective measures in order to develop the objective evaluation method of a vehicle seating comfort. Seventy-two male subjects subjectively evaluate six seats (driver seats in popular automotive in Korea) after a short-term seating session (non driving: the evaluation of seat characteristics) and after two-hour driving (two hour driving: the evaluation of body discomfort). The body pressure distribution, objective data for six seats, is investigated and compared with the subjective evaluation. The pattern of the pressure distribution is found and the pressure distribution is approximately correlate with the difference between comfortable and uncomfortable seats.

Deformations of soft tissues and seat cushion foam are significant factors in determining the interface contours between the seat and the back of the thigh. This paper describes the measurement of forces, deformations, and contours of people's thighs and seat cushion materials. The goal of this work is to represent the human interactions with seats. A two-dimensional, plane strain finite element method was used to develop a contact model between the cross section of the human mid-thigh and flat surfaces, which can be a flat, rigid surface or a flat, foam cushion of various thicknesses and densities. Results of human and seat interactions for various subjects were measured, modeled, and compared. The present work showed a good agreement between experiments and models for various subjects and foam densities. The important results showed that the stiffness of the foam does not depend on the foam thickness.

The human torso includes three major segments, the thoracic (rib cage) segment, lumbar segment, and pelvic segment to which the thighs are attached. The JOHN model was developed to represent the positions and movements of these torso segments along with the head, arms, and legs. Using the JOHN model, a new seat concept has been developed to support and move with the torso segments and thighs. This paper describes the background of the biomechanically articulated chair (BAC) and the development of BAC prototypes. These BAC prototypes have been designed to move with and support the thighs, pelvis, and rib cage through a wide variety of recline angles and spinal curvatures. These motions have been evaluated with computer modeling and with initial experience of human subjects. Results from computer modeling and human subjects show that the BAC will allow a broad range of torso postures.

A research effort was initiated to establish an empirical data base and to develop predictive models of normal human in-vehicle seated reaching motions while driving. A driving simulator was built, in which a variety of targets were positioned at typical locations a driver would possibly reach. Reaching motions towards these targets were performed by demographically representative subjects and measured by a state-of-the-art motion analysis system. This paper describes the experiment conducted to collect the movement data, and the new techniques that are being developed to process, analyze, and model the data. Some initial findings regarding the role of torso assistive motion, the effect of speed used in completing a motion on multi-segment dynamic postures, and illustrative results from kinematic modeling are presented.

Driver and passenger comfort, as related to automotive seats, is a growing issue in the automotive industry. As this trend continues, automotive seat designers and developers are generating a greater need for more anthropometrically accurate tools to aid them in their work. One tool being developed is the JOHN software program that utilizes three-dimensional solid objects to represent humans in seated postures. Contours have been developed to represent the outside skin surfaces of three different body types in a variety of postures in the sagittal plane. These body types include: the small female, the average male, and the large male.

Some aspects on the detection of critical roll over situations for car safety applications will be presented. The detection via acceleration sensitive devices will be discussed as well as the detection via roll rate sensing elements. A combination of both sensors, the inclination sensing element and the roll rate sensing element seems to be the most feasible way for realization of a safe roll over detection.

The development of a transducer for sensing the torque on the output shaft of a four speed rear wheel drive automatic transmission is described. Magnetoelastic polarized ring technology was selected based on its independence from shaft properties and its non-contact mode of sensing. The ring and several intermediate sleeves were attached by press fits onto an experimental shaft. The magnetic field arising from the ring with the application of torque was sensed by flux gate sensing elements. Ability to accurately measure the output torque of an engine driven transmission over its full range of torque and speed was demonstrated by dynamometer tests.

Magnetostrictive sensors offer many attractive features. Their strain sensitivity is significantly higher than that of strain gages. They are simple, rugged and inexpensive. Signal conditioning requirements for the magnetostrictive sensors are determined by the selection of a signal detection method. This article experimentally investigates different signal detection methods for single branch magnetostrictive sensors with conventional excitation and detection coils. Monitoring excitation voltage while holding excitation current constant, or monitoring excitation current while holding excitation voltage constant produces much better output signal compared to the detection voltage. Furthermore, this study suggest that the detection coil is not really needed, leading to a novel single branch magnetostrictive sensor without a detection coil.

Large changes in resistance with magnetic field exhibited by recently discovered thin-film multilayer structures offer new opportunities in the sensors field. Compatibility of these Giant Magnetoresistive (GMR) materials with conventional semiconductor processing technology and semiconductor underlayers allows the production of inexpensive, ultra-small, smart sensors with enhanced magnetic sensitivity. The action of GMR materials is described along with their application to sensor configurations for detecting magnetic fields, magnetic field gradients, and magnetic fields from currents. Characteristics of these sensors are discussed and compared to conventional magnetic field sensors. Finally, the exciting combination of GMR materials with semiconductor underlayers in smart sensors with linear or digital (switched) outputs is explored.

Most navigation systems today use some type of compass to determine heading direction. Using the earth's magnetic field, electronic compasses based on magnetoresistive (MR) sensors can electrically resolve better than 0.1 degree rotation. Discussion of a simple 8-point compass will be described using MR sensors. Methods for building a one degree compass using MR sensors will also be discussed. Compensation techniques are shown to correct for compass tilt angles and nearby ferrous material disturbances.

Recently there is demand for rotation sensors capable of high-accuracy detection and very low-speed detection of rotation at high temperature for automobile use. To meet this requirement, a rotation sensor using an InSb thin-film magneto-resistors with good thermal stability has been developed. This sensor transduces magnetic flux change due to gear rotation to resistance change. It is composed of InSb thin-film magneto-resistors fabricated by a newly developed process and signal shaping circuits where resistor signals are converted to digital signals using no amplifier. Accordingly, the signals are independent of the measured frequencies, making possible very low speed (0 to 20 Hz) detection. The sensor stably operates in the temperature range from -40 to 150 degree C for thousands hours. There is no need for a shielded harness due to the digital output signal.

The presentation and paper will include a basic description of the Giant Magnetoresistive Ratio (GMR) effect, and will describe the magnetic, electronic and thermal performance of GMR materials. A functional automotive grade magnetic rotational wheel speed sensor using GMR materials as a sensing element has been fabricated. Performance data and some design considerations will be discussed. GMR materials have been integrated with standard silicon semiconductor processing allowing sensor and signal processing circuitry to be combined on a single chip. This single chip solution allows for a high performance small sized device. The ABS sensor is a zero speed, two wire device with an output current that switches between two levels, producing a square wave that has a frequency equal to the frequency of the target wheel teeth or magnetic poles. The device has a 50% +/- 10 duty cycle over the operating temperature and frequency ranges.

The objective of this study was to use the driving-point impedance and transmissibility techniques to evaluate and compare the resonance behavior of two male humans, the Hybrid III aerospace manikin, and a rigid body mass using a rigid seat and a selected helicopter seat cushion. All occupants represented the 95th percentile or higher of the male population for weight. The results showed that the resonance frequencies associated with the peak impedance, chest, and head transmissibilities were significantly higher in the manikin regardless of the seating configuration or input acceleration level. While the magnitude of the peak impedance was higher in the manikin, differences in the chest and head transmissibilities depended on both the seating configuration and acceleration level. Neither the manikin nor the rigid body were effective in predicting the primary human resonance effects occurring in the sensitive region of 4 to 8 Hz.

Occupant protection in the event of interior head impact is a major issue in the development process of interior component countermeasures. As phase-in schedules for head impact protection regulations fast approach, auto safety engineers are presented with major challenges in regard to developing suitable design alternatives. This paper presents a variety of testing options which are available to evaluate interior design options. These test alternatives vary from simple component-level drop tests to in-vehicle compliance testing. Each type of test serves a specific purpose in the development of interior components from a head impact protection perspective. The basic parameters for each type of test, including mass, form shape, velocity, and motion will be discussed. Test data from component-level testing is presented, as well as the advantages and disadvantages for each alternative.

Two sled systems capable of producing structural intrusion in the footwell region of an automobile have been developed. The first, System A, provides translational toepan intrusion using actuator pistons to drive the footwell structure of the test buck. These actuator pistons are coupled to the hydraulic decelerator of the test sled and are powered by hydraulic energy from the impact event. Resulting footwell intrusion is characterized using a toepan pulse analogous to the acceleration pulse used to characterize sled and vehicle decelerations. Sled tests with System A indicate that it is capable of accurately and repeatably simulating toepan/floorpan intrusion into the occupant footwell. Test results, including a comparison of lower extremity response between intrusion sled tests and no intrusion sled tests, indicate that this system is capable of repeatable, controlled structural intrusion during a sled test impact.