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Technical Paper

A Vehicle-to-Vehicle Communication Database for Infrastructureless Routing

2008-04-14
2008-01-1254
Traffic engineers use time-of-day travel time databases to characterize normal travel times on roads. This information is used by traffic management centers together with information from sensors in the highway to identify problems and to make alternate route recommendations. In this paper, the travel time database concept is extended to a vehicle-to-vehicle communications network for traffic and safety information, wherein the travel time database is generated and stored by vehicles in the network, and used by the vehicles to identify abnormal traffic conditions. This infrastructure-free approach is attractive due to the potential to eliminate highway sensor and sensor maintenance costs, which are major factors that limit the growth of traffic information beyond major roadways in urban regions. Initial work indicates that database storage requirements in the vehicle should be manageable.
Technical Paper

A 6-Speed Automatic Transmission Plant Dynamics Model for HIL Test Bench

2008-04-14
2008-01-0630
During the production controller and software development process, one critical step is the controller and software verification. There are various ways to perform this verification. One of the commonly used methods is to utilize an HIL (hardware-in-the-loop) test bench to emulate powertrain hardware for development and validation of powertrain controllers and software. A key piece of an HIL bench is the plant dynamics model used to emulate the external environment of a modern controller, such as engine (ECM), transmission (TCM) or powertrain controller (PCM), so that the algorithms and their software implementation can be exercised to confirm the desired results. This paper presents a 6-speed automatic transmission plant dynamics model development for hardware-in-the-loop (HIL) test bench for the validation of production transmission controls software. The modeling method, model validation, and application in an HIL test environment are described in details.
Technical Paper

Closed Loop Pressure Control System Development for an Automatic Transmission

2009-04-20
2009-01-0951
This paper presents the development of a transmission closed loop pressure control system. The objective of this system is to improve transmission pressure control accuracy by employing closed-loop technology. The control system design includes both feed forward and feedback control. The feed forward control algorithm continuously learns solenoid P-I characteristics. The closed loop feedback control has a conventional PID control with multi-level gain selections for each control channel, as well as different operating points. To further improve the system performance, Robust Optimization is carried out to determine the optimal set of control parameters and controller hardware design factors. The optimized design is verified via an L18 experiment on spin dynamometer. The design is also tested on vehicle.
Technical Paper

Closed Loop Pressure Control System Requirements and Implementation

2011-04-12
2011-01-0391
Electro-hydraulic actuation has been used widely in automatic transmission designs. With greater demand for premium shift quality of automatic transmissions, higher pressure control accuracy of the transmission electro-hydraulic control system has become one of the main factors for meeting this growing demand. This demand has been the driving force for the development of closed loop pressure controls technology. This paper presents the further research done based upon a previously developed closed loop system. The focus for this research is on the system requirements, such as solenoid driver selection and system latency handling. Both spin-stand and test vehicle setups are discussed in detail. Test results for various configurations are given.
Technical Paper

A Strategy to Partition Crash Data to Define Active-Safety Sensors and Product Solutions

2008-10-20
2008-21-0032
Both Crash-Avoidance and Pre-Crash active safety technologies are being developed to help reduce the number of crashes and minimize the severity of crashes. The root basis in the development of new and improved active safety technologies always begins with gaining further knowledge about crash kinds and causes. The dynamics of crashes are quite complex. The evolving precursor crash situation initiated in the Crash-Avoidance time-period will vary from the imminent crash situation in the Pre-Crash time-period. As such, in order to develop the appropriate requirements for both crash-avoidance and pre-crash technologies, they must be analyzed from their respective crash data. A data-driven methodology process has been developed which partitions the field data with a perspective to crash-avoidance and pre-crash.
Technical Paper

A Systematic Experimental Investigation of Pd-Based Light-Off Catalysts

2005-10-24
2005-01-3848
Close-coupled or manifold catalysts have been extensively employed to reduce emissions during cold start by achieving quick catalyst light-off. These catalysts must have good thermal durability, high intrinsic light-off activity and high HC/CO/NOx conversions at high temperature and flow conditions. A number of studies have been dedicated to engine control, manifold design and converter optimization to reduce cold start emissions. The current paper focuses on the effect of catalyst design parameters and their performance response to different engine operating conditions. Key design parameters such as catalyst formulation (CeO2 vs. non CeO2), precious metal loading and composition (Pd vs. Pd/Rh), washcoat loading, catalyst thermal mass, substrate properties and key application (in use) parameters such as catalyst aging, exhaust A/F ratio, A/F ratio modulation, exhaust temperature, temperature rise rate and exhaust flow rate were studied on engine dynamometers in a systematic manner.
Technical Paper

SAE Standard Procedure J2747 for Measuring Hydraulic Pump Airborne Noise

2007-05-15
2007-01-2408
This work discusses the development of SAE procedure J2747, “Hydraulic Pump Airborne Noise Bench Test”. This is a test procedure describing a standard method for measuring radiated sound power levels from hydraulic pumps of the type typically used in automotive power steering systems, though it can be extended for use with other types of pumps. This standard was developed by a committee of industry representatives from OEM's, suppliers and NVH testing firms familiar with NVH measurement requirements for automotive hydraulic pumps. Details of the test standard are discussed. The hardware configuration of the test bench and the configuration of the test article are described. Test conditions, data acquisition and post-processing specifics are also included. Contextual information regarding the reasoning and priorities applied by the development committee is provided to further explain the strengths, limitations and intended usage of the test procedure.
Technical Paper

A Statistical Approach for Real-Time Prognosis of Safety-Critical Vehicle Systems

2007-04-16
2007-01-1497
The paper describes the development of a vehicle stability indicator based on the correlation between various current vehicle chassis sensors such as hand wheel angle, yaw rate and lateral acceleration. In general, there is a correlation between various pairs of sensor signals when the vehicle operation is linear and stable and a lack of correlation when the vehicle is becoming unstable or operating in a nonlinear region. The paper outlines one potential embodiment of the technology that makes use of the Mahalanobis distance metric to assess the degree of correlation among the sensor signals. With this approach a single scalar metric provides an accurate indication of vehicle stability.
Technical Paper

The Potential of Switched Reluctance Motor Technology for Electro-Mechanical Brake Applications

2006-04-03
2006-01-0296
Electro-mechanical brakes (EMBs) are emerging as a new approach to enhance brake system features as well as braking performance. This paper takes a fresh look at the switched reluctance (SR) drive as a possible prime mover technology for EMB applications. The switched reluctance motor has attractive potential, in view of its robustness, dynamic bandwidth and fault tolerance. An overall assessment of the approach is made based on bench performance of a prototype EMB caliper with an SR drive executing typical braking patterns. It is shown that the SR motor can provide the required overall brake actuator performance. Various implementation options are examined to lower cost, with particular focus on electronic design, control algorithms and motor position sensing.
Technical Paper

Control of Brake- and Steer-by-Wire Systems During Brake Actuator Failure

2006-04-03
2006-01-0923
In this paper a method of mitigating the consequences of potential brake actuator failure in vehicles with brake-by-wire (BBW) and possibly with steer-by-wire (SBW) systems is described. The proposed control algorithm is based on rules derived from general principles of vehicle dynamics. When a failure of one actuator is detected, the algorithm redistributes the braking forces among the remaining actuators in such a way that the desired deceleration of vehicle is followed as closely as possible, while the magnitude and the rate of change of the yaw moment caused by asymmetric braking are properly managed. When vehicle is equipped with BBW system only, or when the desired deceleration can be obtained by redistributing of braking forces, without generating an undesired yaw moment, no steering correction is used. Otherwise, a combination of brake force redistribution and steering correction (to counter the yaw moment generated by non-symmetric braking) is applied.
Technical Paper

Sensitivity of Contact Electronic Throttle Control Sensor to Control System Variation

2006-04-03
2006-01-0763
The purpose of this paper is to improve the understanding of the advantages of a non-contact electronic throttle control (ETC) air control valve position sensor over the potentiometer technology of contacting position sensors. The non-contact position sensing offers the industry an opportunity to take advantage of an improved ability to assess reliability of the product and utilize accelerated testing techniques with improved robustness to control system perturbations. Specifically; eliminating the contact wear failure mechanism reduces the complexity, and duration of ETC air control valve life testing and increases the robustness of the ETC system to noise factors from the control system variation.
Technical Paper

Application of Robust Engineering Methods to Improve ECU Software Testing

2006-04-03
2006-01-1600
Robust Engineering techniques developed by Taguchi have traditionally applied to the optimization of engineering designs. Robust Engineering methods also may be applied to software testing of ECU algorithms. The net result is an approach capable of improving the software algorithm in one of two ways. First the approach can identify the range of areas which prove problematic to the software such that a robust solution may be developed. Conversely, the approach can be used as a general strategy to verify that the software is robust over the range of inputs tested. The robust engineering methods applied to software testing utilize orthogonal array experiments to test software over a range of inputs. The actual software trials are best performed in the simulation environment and also via automated test hardware in the loop configurations in realtime. This paper outlines a process for applying Robust Engineering methods to software testing.
Technical Paper

Non-Intrusive Engine Speed Sensor

2007-04-16
2007-01-0960
In the field of vehicle diagnostics accurate instantaneous engine speed information enables the detection and diagnosis of many engine problems, even subtle ones. Currently, there is a limited choice in the ways of obtaining such information. For example, it is known that one can tap into the crank sensor wiring, or use a separate, intrusive method, such as mounting a sensor in the bell housing to sense the rotation of the ring gear. However, the shortcomings of these approaches are locating and gaining access to the crank sensor connector, the location of which varies from vehicle to vehicle. Thus, authors proposed a novel, robust and manufacturing friendly speed sensor. The concept is based on the Villari effect. The sensor, which is attached to the front end of the engine crankshaft, consists of a coil of magnetostrictive wire supplied with AC current. During engine rotation the magnetostrictive wire become stressed due to centrifugal force.
Technical Paper

Design of an Automotive Grade Controller for In-Cylinder Pressure Based Engine Control Development

2007-04-16
2007-01-0774
This paper describes a new tool to capture cylinder pressure information, calculate combustion parameters, and implement control algorithms. There are numerous instrumentation and prototyping systems which can provide some or all of this capability. The Cylinder Pressure Development Controller (CPDC) is unique in that it uses advanced high volume automotive grade circuitry, packaging, and software methodologies. This approach provides insight regarding the implementation of cylinder pressure based controls in a production engine management system. A high performance data acquisition system is described along with a data reduction technique to minimize data processing requirements. The CPDC software architecture is discussed along with model-based algorithm development and autocoding. Finally, CPDC calculated combustion parameters are compared with those from a well established combustion analysis system and thermodynamic simulations.
Technical Paper

A Hardware-in-the-loop Test Bench for Production Transmission Controls Software Quality Validation

2007-04-16
2007-01-0502
Production software validation is critical during software development, allowing potential quality issues that could occur in the field to be minimized. By developing automated and repeatable software test methods, test cases can be created to validate targeted areas of the control software for confirmation of the expected results from software release to release. This is especially important when algorithm/software development timing is aggressive and the management of development activities in a global work environment requires high quality, and timely test results. This paper presents a hardware-in-the-loop (HIL) test bench for the validation of production transmission controls software. The powertrain model used within the HIL consists of an engine model and a detailed automatic transmission dynamics model. The model runs in an OPAL-RT TestDrive based HIL system.
Technical Paper

Exploring the Trade-Off of Handling Stability and Responsiveness with Advanced Control Systems

2007-04-16
2007-01-0812
Advanced chassis control systems enable a vehicle to achieve new levels of performance in handling stability and responsiveness. In recent work by NHTSA and others, the performance of Electronic Stability Control (ESC) systems has been studied with focus on yaw stability and roll stability of vehicles on high friction surfaces. However, it is recognized that vehicle handling responsiveness is also an important aspect that should be maintained. This paper explores the trade-offs between yaw rate, side slip, and roll motions of a vehicle, and their relationships to handling stability and handling responsiveness. This paper further describes how various control systems are able to manage these motions. The paper also discusses methods to assess vehicle stability and responsiveness using specific maneuvers and measurements, and it includes data from vehicle tests on a slippery surface.
Technical Paper

Throttle Icing: Understanding the Icing Mechanism and Effects of Various Throttle Features

2008-04-14
2008-01-0439
Some Electronic Throttle Control (ETC) Air Control Valves (ACV) on automotive internal combustion engines are susceptible to icing of the throttle valve. Ice formation can result in an increase in torque required to open or close the valve. Laboratory studies were conducted to improve the understanding of throttle valve icing on electronic throttle control valves with both aluminum and composite (plastic) bodies over various bore sizes (4 cylinder to 8 cylinder engines). Study results indicated that ice compression at the bore and valve gap, not ice adhesion, is the major contributor to the ETC-ACV icing phenomenon. In addition, testing of parts with various bore sizes, orientations and surface cleanliness resulted in further understanding of the icing issue.
Technical Paper

A Comparative Study of the Production Applications of Hybrid Electric Powertrains

2003-06-23
2003-01-2307
In this paper, a comparative study of the production applications of hybrid electric powertrains is presented. Vehicles studied include the Toyota Prius, Honda Insight, Toyota Estima, Toyota Crown, Honda Civic Hybrid, and Nissan Tino. The upcoming Ford Escape Hybrid and General Motors Parallel Hybrid Truck (PHT) will also be included, although advance information is limited. The goal of this paper is to look at what hybrid drivetrain architectures have actually been selected for production and what are the underlying details of these drivetrains. Since hybridizing a powertrain involves significant changes, the powertrain architectures are presented in diagram form, with analysis as to the similarities and advantages represented in these architectures. The specific hybrid functions used to save fuel are discussed. Peak power-to-weight ratio and degree of hybridization are plotted for the vehicles. System voltage versus electric power level are also plotted and analyzed.
Technical Paper

“Clear Vision” Automatic Windshield Defogging System

2004-03-08
2004-01-1373
The present paper describes the system design for the Clear Vision auto defog system and the improvements made to the Integrated Dew Point and Glass Temperature (IDGT) sensor. The Clear Vision auto defog system has been implemented on a 2000 Cadillac DeVille. Preliminary validation tests demonstrate satisfactory performance.
Technical Paper

An Adaptable Software Safety Process for Automotive Safety-Critical Systems

2004-03-08
2004-01-1666
In this paper, we review existing software safety standards, guidelines, and other software safety documents. Common software safety elements from these documents are identified. We then describe an adaptable software safety process for automotive safety-critical systems based on these common elements. The process specifies high-level requirements and recommended methods for satisfying the requirements. In addition, we describe how the proposed process may be integrated into a proposed system safety process, and how it may be integrated with an existing software development process.
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