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Unsettled Topics Concerning Sensors for Automated Road Vehicles

Stanford Univ.-Sven Beiker
  • Research Report
  • EPR2018001
Published 2018-10-18 by SAE International in United States
This SAE EDGE™ Research Report identifies key unsettled issues of interest to the automotive industry regarding the new generation of sensors designed for vehicles capable of automated driving. Four main issues are outlined that merit immediate interest: First, specifying a standardized terminology and taxonomy to be used for discussing the sensors required by automated vehicles. Second, generating standardized tests and procedures for verifying, simulating, and calibrating automated driving sensors. Third, creating a standardized set of tools and methods to ensure the security, robustness, and integrity of data collected by such sensors. The fourth issue, regarding the ownership and privacy of data collected by automated vehicle sensors, is considered only briefly here since its scope far exceeds the technical issues that are the primary focus of the present report. SAE EDGE™ Research Reports are preliminary investigations of new technologies. The three technical issues identified in this report need to be discussed in greater depth with the aims of, first, clarifying the scope of the industry-wide alignment needed, second, prioritizing the issues requiring resolution, and, third, creating…
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Overcoming Pressure Waves to Achieve High Load HCCI Combustion

Stanford Univ.-Julie Blumreiter, Chris Edwards
Published 2014-04-01 by SAE International in United States
There is significant motivation to extend the operating range of naturally aspirated HCCI combustion to high load (8-12 bar IMEP) to attain a combustion strategy with the efficiency benefits of HCCI but without the lost power density of a lean or highly diluted charge. Currently, the high-load limit of HCCI combustion is imposed by a phenomenon commonly known as ringing. Ringing results when the kinetically-driven autoignited combustion process proceeds in such a way as to form strong pressure waves which reverberate in the engine. Inhomogeneities and gradients in mixture reactivity lead certain regions to react ahead of others, and as a result, coupling can occur between a pressure wave and the reaction front. This paper seeks first to sort several related but distinct issues that impose the high load limit: ringing, engine damage, peak in-cylinder pressure, peak rate of pressure rise, and engine noise. The fundamental gasdynamics underlying the upper load limit for premixed, autoignited engines are explored and elucidated with a quasi-1D reacting compressible flow model. This model is then used to interpret published…
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Prospects for High-Temperature Combustion, Neat Alcohol-Fueled Diesel Engines

SAE International Journal of Engines

Stanford Univ.-Gregory Roberts, Bernard Johnson, Chris Edwards
  • Journal Article
  • 2014-01-1194
Published 2014-04-01 by SAE International in United States
The use of neat alcohols, namely methanol and ethanol, in direct-injection, compression-ignited engines is difficult, most notably due to their poor ignitability. By employing a high-temperature combustion strategy, this challenge may be overcome, thus creating the opportunity for using these oxygenated and inherently low-sooting fuels for heavy-load applications.Experimental data are provided from a single-cylinder research engine that shows particulate matter (PM) emissions for Diesel-style combustion of both methanol and ethanol that are below the current US Government regulation limit. The level of particulates remained low up to stoichiometric ratios of fuel and air. A complete emissions analysis indicates a high combustion efficiency of ∼ 96% at stoichiometric conditions.In order to achieve reliable combustion, some form of intake-air preheating was required. The issue of ignitability is addressed with modeling which indicates that highly turbocharged, non-intercooled air into a cylinder with low heat rejection (LHR) surfaces can achieve conditions that satisfy acceptable ignition delay requirements. With increased exhaust enthalpy, opportunities exist to use thermal or mechanical exhaust regeneration strategies. All of these features contribute to a clean,…
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Passive Pedestrian Protection Approach for Vehicle Hoods

Stanford Univ.-Matthew Pawlicki
General Motors Co.-Vesna Savic, Paul Krajewski, Mark Voss, Louis Hector, Keith Snavely
Published 2014-04-01 by SAE International in United States
Global regulations intended to enhance pedestrian protection in a vehicle collision, thereby reducing the severity of pedestrian injuries, are presenting significant challenges to vehicle designers. Vehicle hoods, for example, must absorb a significant amount of energy over a small area while precluding impact with a hard engine compartment component. In this paper, a simple passive approach for pedestrian protection is introduced in which thin metal alloy sheets are bent to follow a C-shaped cross-sectional profile thereby giving them energy absorbing capacity during impact when affixed to the underside of a hood. Materials considered were aluminum (6111-T4, 5182-O) and magnesium (AZ31-O, AZ61-O, ZEK100) alloys. To evaluate the material effect on the head injury criterion (HIC) score without a hood, each C-channel absorber was crushed in a drop tower test using a small dart. Two high speed cameras captured dart image data before and during impact from which HIC scores were computed with stereo digital image correlation (DIC). The only absorber material that fractured during impact, Mg AZ31-O, had the lowest and hence most favorable HIC score…
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Development of an Integrated Control Strategy Consisting of an Advanced Torque Vectoring Controller and a Genetic Fuzzy Active Steering Controller

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Stanford Univ.-Thomas Uchida
Univ. of Waterloo-Kiumars Jalali, John McPhee, Steve Lambert
  • Journal Article
  • 2013-01-0681
Published 2013-04-08 by SAE International in United States
The optimum driving dynamics can be achieved only when the tire forces on all four wheels and in all three coordinate directions are monitored and controlled precisely. This advanced level of control is possible only when a vehicle is equipped with several active chassis control systems that are networked together in an integrated fashion. To investigate such capabilities, an electric vehicle model has been developed with four direct-drive in-wheel motors and an active steering system. Using this vehicle model, an advanced slip control system, an advanced torque vectoring controller, and a genetic fuzzy active steering controller have been developed previously. This paper investigates whether the integration of these stability control systems enhances the performance of the vehicle in terms of handling, stability, path-following, and longitudinal dynamics. An integrated approach is introduced that distributes the required control effort between the in-wheel motors and the active steering system. Several test maneuvers are simulated to demonstrate the performance and effectiveness of the integrated control approach, and the results are compared to those obtained using each controller individually. Finally,…
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PLIF Measurements of Thermal Stratification in an HCCI Engine under Fired Operation

SAE International Journal of Engines

Stanford Univ.-Jordan Snyder, Ronald Hanson
Sandia National Laboratories-Nicolas Dronniou, John E. Dec
  • Journal Article
  • 2011-01-1291
Published 2011-04-12 by SAE International in United States
Tracer-based PLIF temperature diagnostics have been used to study the distribution and evolution of naturally occurring thermal stratification (TS) in an HCCI engine under fired and motored operation. PLIF measurements, performed with two excitation wavelengths (277, 308 nm) and 3-pentanone as a tracer, allowed investigation of TS development under relevant fired conditions. Two-line PLIF measurements of temperature and composition were first performed to track the mixing of the fresh charge and hot residuals during intake and early compression strokes. Results showed that mixing occurs rapidly with no measureable mixture stratification remaining by early compression (220°CA aTDC), confirming that the residual mixing is not a leading cause of thermal stratification for low-residual (4-6%) engines with conventional valve timing.In the second part of the study, single-line PLIF measurements performed later in the compression stroke showed that the distribution of TS and its development are very similar for both motored and fired operation. This finding indicates that the mechanism producing the temperature stratification is the same for both cases, although some differences in magnitude can occur. A subsequent…
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An In-cylinder Laser Absorption Sensor for Crank-angle-resolved Measurements of Gasoline Concentration and Temperature

SAE International Journal of Engines

Stanford Univ.-Jay B. Jeffries, Jason M. Porter, Sung Hung Pyun, Ronald K. Hanson
Nissan Motor Co Ltd-Kevin R. Sholes, Kiyotaka Shouji, Tomohiro Chaya
  • Journal Article
  • 2010-01-2251
Published 2010-10-25 by SAE International in United States
Simultaneous crank-angle-resolved measurements of gasoline concentration and gas temperature were made with two-color mid-infrared (mid-IR) laser absorption in a production spark-ignition engine (Nissan MR20DE, 2.0L, 4 cyl, MPI with premium gasoline). The mid-IR light was coupled into and out of the cylinder using fiber optics incorporated into a modified spark plug. The absorption line-of-sight was a 5.3 mm optical path located closely adjacent to the ignition spark providing spatially resolved absorption. Two sensor wavelengths were selected in the strong bands associated with the carbon-hydrogen (C-H) stretching vibration near 3.4 μm, which have an absorption ratio that is strongly temperature dependent. Fuel concentration and temperature were determined simultaneously from the absorption at these two wavelengths. The two mid-IR laser wavelengths were simultaneously produced by difference-frequency-generation in a periodically poled lithium niobate (PPLN) crystal using one signal and two pump lasers. The pump lasers were modulated at different frequencies allowing frequency demultiplexing of the laser light transmitted though the spark plug probe, providing simultaneous absorption signals at the two mid-IR wavelengths. A model of the absorption cross…
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Effect of Post Injections on In-Cylinder and Exhaust Soot for Low-Temperature Combustion in a Heavy-Duty Diesel Engine

SAE International Journal of Engines

Stanford Univ.-Wiley Neel
Sandia National Laboratories-Mohan Bobba, Mark Musculus
  • Journal Article
  • 2010-01-0612
Published 2010-04-12 by SAE International in United States
Multiple fuel-injections during a single engine cycle can reduce combustion noise and improve pollutant emissions tradeoffs. Various hypotheses have been proposed in the literature regarding the in-cylinder processes responsible for the pollutant emissions improvements. This paper provides a brief overview of these hypotheses along with an investigation exploring which of these mechanisms are important for post injections under low-temperature combustion (LTC) conditions in a heavy-duty diesel engine. In-cylinder soot and exhaust smoke are measured by 2-color soot thermometry and filter paper blackening, respectively. The evolution and interaction of soot regions from each of the injections is visualized using high-speed imaging of soot luminosity, both in the piston bowl and in the squish regions. Results for early main-injection (-18° after top dead center command start of injection) conditions show an abrupt reduction in exhaust soot as the post injection is delayed to timings where the post-injection jet starts to enter the squish volume. At these conditions, the post injection in the squish volume produces no soot of its own, and it does not interact with soot…
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Determination of Cycle Temperatures and Residual Gas Fraction for HCCI Negative Valve Overlap Operation

SAE International Journal of Engines

Stanford Univ.-Jordan Snyder, Ronald Hanson
Sandia National Laboratories-Russell P. Fitzgerald, Richard Steeper
  • Journal Article
  • 2010-01-0343
Published 2010-04-12 by SAE International in United States
Fuel injection during negative valve overlap offers a promising method of controlling HCCI combustion, but sorting out the thermal and chemical effects of NVO fueling requires knowledge of temperatures throughout the cycle. Computing bulk temperatures throughout closed portions of the cycle is relatively straightforward using an equation of state, once a temperature at one crank angle is established. Unfortunately, computing charge temperatures at intake valve closing for NVO operation is complicated by a large, unknown fraction of residual gases at unknown temperature. To address the problem, we model blowdown and recompression during exhaust valve opening and closing events, allowing us to estimate in-cylinder charge temperatures based on exhaust-port measurements. This algorithm permits subsequent calculation of crank-angle-resolved bulk temperatures and residual gas fraction over a wide range of NVO operation. Validation methods are employed to assess both accuracy and precision of the temperature calculations. Measured iso-octane ignition temperatures and combustion phasing sensitivity are compared with published experimental trends. Computed bulk temperatures throughout the main compression stroke are compared with core temperature measurements using tracer-based laser-induced fluorescence…
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Simultaneous Measurement of In-Cylinder Temperature and Residual Gas Concentration in the Vicinity of the Spark Plug by Wavelength Modulation Infrared Absorption

Stanford Univ.-Ronald K. Hanson, Jay B. Jeffries
Nissan Motor-Akihiko Kakuho, Kevin R. Sholes, Yutaka Hashizume, Tomonori Urushihara
  • Technical Paper
  • 2006-08-0435
Published 2006-09-27 by Society of Automotive Engineers of Japan in Japan
This paper presents a new measurement technique for in-cylinder gas temperature and residual gas concentration during the compression stroke of an internal combustion (IC) engine. This technique is based on the infrared absorption of water vapor by a wavelength-modulated laser. Wavelength modulation spectroscopy with second harmonic detection (WMS-2f) was adopted to enable the short-path measurements over a wide range of temperatures and pressures corresponding to the late compression stroke in a typical automotive engine. The WMS-2f signal is detected through a bandpass filter at a width of 7.5 kHz enabling crank angle-resolved measurements. The temperature is determined from the ratio of optical absorption for two overtone transitions of water vapor in the intake gas mixture and the H2O concentration is determined from this inferred temperature and the absorption for one of the transitions. The measurements sample a short-path region (5 mm) of the in-cylinder gases near the spark plug, which has been modified to provide optical access. Crank angle-resolved measurements are performed in a mass-production-type engine.