Showing papers in "SAE technical paper series in 2022"

Mobility Energy Productivity Evaluation of Prediction-Based Vehicle Powertrain Control Combined with Optimal Traffic Management

Abstract: T ransportation vehicle and network system efficiency can be defined in two ways: 1) reduction of travel times across all the vehicles in the system, and 2) reduction in total energy consumed by all the vehicles in the system. The mechanisms to realize these efficiencies are treated as independent (i.e., vehicle and network domains) and, when combined, they have not been adequately studied to date. This research aims to integrate previously developed and published research on Predictive Optimal Energy Management Strategies (POEMS) and Intelligent Traffic Systems (ITS), to address the need for quantifying improvement in system efficiency resulting from simultaneous vehicle and network optimization. POEMS and ITS are partially independent methods which do not require each other to function but whose individual effectiveness may be affected by the presence of the other. In order to evaluate the system level efficiency improvements, the Mobility Energy Productivity (MEP) metric is used. MEP specifically measures the connectedness of a system while accounting for time and energy externalities of modes that provide mobility in a given location. A SUMO model is developed to reflect real traffic patterns in Fort Collins, Colorado and data is collected by a probe SUMO vehicle which is validated against data collected on a real vehicle driving the same routes through the city. Individual vehicle and system level efficiencies are calculated using SUMO outputs for scenarios which integrate POEMS and ITS independently as well as jointly. Results from application of

Testing of a Modern Wankel Rotary Engine - Part III: Firing Condition Analysis

Abstract: This work represents a further contribution to reporting experimental activities carried out on a modern Wankel rotary engine. Specifically, in this study, the firing performance of the Advanced Innovative Engineering 225CS engine is analysed. Preliminary presentations of the experimental and measurement setup and a motoring analysis were extensively covered in Part I and II of this suite of papers while the current work presents the combustion analysis of the firing indicated pressure cycles collected through the bespoke combustion analyser software developed within the project. With the Wankel rotary engine gaining popularity again due to its potential as a range extender for battery electric vehicles, the aim of this work was mainly to analyse the fuel consumption together with the overall efficiency and the emissions at different engine speeds and loads as per classic steady-state engine testing. The characteristic curves of power and torque thus derived from the experimental measurements are reported while further deductions on combustion phenomena are then drawn from an analysis of the indicated pressure cycles. Specifically, parameters such as the rate of heat release, the net heat release, the IMEP and the indicated instantaneous torque are assessed. Further considerations are drawn on the overall mechanical efficiency relying on the IMEP computed from the indicated pressure cycles and the BMEP inferred from the torqued measured experimentally under steady-state conditions. Furthermore, the effects of the combustion on the internal pressure of the Self-Pressurizing Air-Rotor-Cooling System employed are evaluated in addition to parameters such as the Coefficient of Variation of the IMEP for the evaluation of the cycleto-cycle combustion quality and engine regularity. Finally, the postprocessed data represent an update to the historical literature on Wankel rotary engines. In addition, it can be used for the development and validation of numerical models for such engines hence allowing investigation by means of simulations of the effect on efficiency and performance of the rotary engine when employing alternative fuels such as hydrogen in the future.

The Missing Link: Developing a Safety Case for Perception Components in Automated Driving

Abstract: Safety assurance is a central concern for the development and societal acceptance of automated driving (AD) systems. Perception is a key aspect of AD that relies heavily on Machine Learning (ML). Despite the known challenges with the safety assurance of ML-based components, proposals have recently emerged for unit-level safety cases addressing these components. Unfortunately, AD safety cases express safety requirements at the system-level and these efforts are missing the critical linking argument connecting safety requirements at the system-level to component performance requirements at the unit-level. In this paper, we propose a generic template for such a linking argument specifically tailored for perception components. The template takes a deductive and formal approach to define strong traceability between levels. We demonstrate the applicability of the template with a detailed case study and discuss its use as a tool to support incremental development of perception components.

Testing of a Modern Wankel Rotary Engine - Part II: Motoring Analysis

Abstract: The present work represents the continuation of the introductory study presented in part I [11] where the experimental plan, the measurement system and the tools developed for the testing of a modern Wankel engine were illustrated. In this paper the motored data coming from the subsequent stage of the testing are presented. The AIE 225CS Wankel rotary engine produced by Advanced Innovative Engineering UK, installed in the test cell of the University of Bath and equipped with pressure transducers selected for the particular application, has been preliminarily tested under motored conditions in order to validate the data acquisition software on the real application and the correct determination of the Top Dead Centre (TDC) location which is of foremost importance in the computation of parameters such as the indicated work and the combustion heat release when the engine is tested later under fired conditions. In this testing phase much importance has been given also to the measurement of the frictions at the different operating rotational speeds. Interestingly, the data have been collected at three different coolant temperatures, 30°C, 60°C and 90°C respectively, in order to investigate and quantify any possible effect and interaction of the heat transfer on the mechanical and thermodynamics engine parameters for the usual operating temperature range. The collected data are subsequently used for the determination of the Friction Mean Effective Pressure (FMEP) to be employed in the computation of the Brake Mean Effective Pressure (BMEP) from the indicated pressure cycle or in the numerical models created for simulation purposes. Finally, still by means of the analysis of the indicated pressure cycle, further considerations are drawn on the thermo-fluid dynamics interactions of the three moving chambers with the self-pressurizing air-cooled rotor system (SPARCS) with its details already described in the first part of this suite of papers.