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2022 COMVEC™

COMVEC™ conference is the only North American event that addresses vehicles and equipment spanning on-highway, off-highway, agricultural, construction, industrial, military, and mining sectors.
Technical Paper

4-Sensor 2-Channel Anti-Lock System for FWD Cars

The possibility of 2 Channel anti-lock system, which controls each of two independent hydraulic circuits of diagonal split braking system of FWD car seperately, were studied. Theoretical investigation suggested two out of four possible control logics to be promising and they were proved to be practically satisfactory through vehicle test. This system is almost as effective as expensive 3-channel or 4-channel system, when the braking force distribution between front and rear axles is correct as required by EEC Braking regulation. Under extreme condition that rear wheels lock earlier than fronts, the compromise between stopping distance and stability is necessary.
Technical Paper

A Band Variable-Inertia Flywheel Integrated-Urban Transit Bus Performance

By means of computer simulation, the potential of a Band Variable-Inertia Flywheel (BVIF) as an energy storage device for a diesel engine city bus is evaluated. Replacing both a fixed-inertia flywheel (FIF) and a continuously variable transmission (CVT), the BVIF is capable of accelerating a vehicle from rest to a nearly-constant speed, while recovering part of the kinetic energy normally dissipated through braking of the vehicle. The results are compared with that of conventionally-powered bus. A fuel saving of up to 30 percent is shown with the BVIF-integrated system. The regenerative braking system reduces brake wear by a factor of five in comparison with the conventional vehicle.
Technical Paper

A Case Study: Improvements in Automotive Motion Simulators Using Six Sigma Methodologies

Newer automobiles have complex dynamic and stability controls due to regulations, competition, and safety concerns. More systems require testing at the subcomponent level to ensure proper operation in the final vehicle assembly. Many of the stability and navigation features originally designed for aircraft components are now being incorporated into automobiles. Certain types of motion test simulators were originally designed for testing aircraft sensors as: gyroscopes, inertial navigation systems (INS), inertial measurement units (IMU), and attitude heading and reference systems (AHARS) This same type of equipment is now used for automotive testing as: airbag fuse sensors, anti-skid sensors, rollover sensors, vehicle stabilization systems, active suspension sensors, and navigation systems.
Technical Paper

A Comparative Review of Fuel Cell Vehicles (FCVs) and Hybrid Electric Vehicles (HEVs) Part I: Performance and Parameter Characteristics, Emissions, Well-to-Wheels Efficiency and Fuel Economy, Alternative Fuels, Hybridization of FCV, and Batteries for Hybrid Vehicles

Currently, almost all the activities in the development of new generation of vehicles are focused on fuel cell powered vehicles (FCVs) and hybrid electric vehicles (HEVs). However, there are still uncertainties as to which provides the maximum benefits in terms of performance, energy savings and impact on the environment. This paper compares the performance and parameter characteristics of FCVs and HEVs with a view towards an objective assessment of the relative performance of these vehicles. In particular, this paper reviews major characteristics of FCVs as zero or ultra-low emission vehicles (ZEV/ULEVs), their presumed high efficiency and potential for using alternative fuels, while also considering their limited performance at high power demands.
Technical Paper

A Comparative Study of Rollover Crashes Involving Passenger Cars With and Without Electronic Stability Control (ESC)

The analysis presented here updates and expands previous research in which rollover critical events were classified based on a detailed review of about 500 police-reported single-vehicle rollover crashes of ESC-equipped vehicles. In order to compare the rollover performance of vehicles with and without ESC for the present study, an additional sample of 150 police reports on non-ESC passenger cars and 196 police reports on light vehicles with ESC in single-vehicle rollovers were obtained, and detailed coding of rollover scenarios was performed. The coding effort was undertaken by an engineering team and focused on critical events leading to rollovers (departure from road, loss of directional control, impact with an object, and departure from road with possible driver's input); driver factors (alcohol/drug involvement, speeding, inattention, distraction, fatigue, and overcorrection); and environmental factors.
Technical Paper

A Comparative Study on ESC Drive and Brake Control Based on Hierarchical Structure for Four-Wheel Hub-Motor-Driven Vehicle

Electronic Stability Control (ESC) is an important measure to proactively guarantee vehicle safety. In this paper, the method of four-wheel hub-motor torque control is compared with the traditional single-wheel hydraulic brake control in ESC system. The control strategy adopts the hierarchical structure. In upper controller, the stability of the vehicle is identified by threshold method, the additional yaw moment control uses a way to get the moment including feedforward and feedback parts based on the linear quadratic regulator (LQR). The medium controller is tire slip rate control, in order to get the optimal target slip rate from the upper additional yaw moment, a method of quadratic programming to optimize the longitudinal force is proposed for each wheel. The inputs of tire state for the magic tire model is introduced so as to calculate the target slip rate from the target longitudinal force.
Technical Paper

A Comparison Study on Control Strategies for Optimization of an Anti-Lock Brake System Algorithm Based on Tire Force Measurement in Pure and Combined Slip Conditions of an Automobile

The Anti-Lock Braking System (ABS) is a safety critical feature primarily used to control slipping of wheels, to maximize available traction and minimize stopping distance. Regulatory authorities of many countries have mandated implementation of an ABS as a compulsory safety feature to be present in all road legal automobiles. Hence, apart from avoiding wheel lock-up, an ABS must also ensure that the vehicle maintains its handling stability and steerability while braking. Thus, it is important that the ABS controller modulate and apply adequate amount of brake cylinder pressure. This paper suggests the use of a Tire Force based algorithm to analyze vehicle behavior and accordingly a control law is employed to modulate the wheel brake pressure.
Technical Paper

A Comparison of Braking Behavior between an IC Engine and Pure Electric Vehicle in Los Angeles City Driving Conditions

The Los Angeles City Traffic Brake Test Schedule has been an established procedure used almost universally for generations by vehicle manufacturers to evaluate and validate braking systems for the attributes of NVH and brake wear behavior. The Los Angeles driving route, commonly known as the Los Angeles City Traffic Test (LACT), has long been considered an effective and “quasi” extreme set of real world driving conditions representative of the US passenger vehicle market and have been covered in other analysis including SAE Technical Paper 2002-01-2600 [1] The performance of a vehicle, relative to braking, in LACT conditions is typically influenced by basic vehicle and brake system attributes including the ratios of vehicle mass to brake sizing attributes, friction material selection, and the acceleration, drag, and cooling behavior of the vehicle.
Technical Paper

A Comparison of Energy Use for a Direct-Hydrogen Hybrid Versus a Direct-Hydrogen Load-Following Fuel Cell Vehicle

Hybridizing a fuel cell vehicle has the potential to improve the vehicle efficiency largely due to the ability to recover braking energy. However, tradeoffs do exist, and the advantages (in terms of potential fuel savings) are largely dependent on the drive cycle. The tradeoffs include added energy losses associated with the DC/DC converter and the battery pack itself. Additional tradeoffs not explicitly addressed in this study include added overall complexity, additional packaging constraints, and potentially higher overall cost. This report will focus on a quantitative analysis of the performance of the direct-hydrogen (DH) hybrid and load-following fuel cell vehicles (FCVs) from the viewpoint of the energy use throughout the system. Specifically, the vehicle energy use and efficiency will be compared between the load following and hybrid vehicle platforms. Several hybrid component configurations were studied.
Technical Paper

A Comparison of Energy Use for a Indirect-Hydrocarbon Hybrid versus an Indirect-Hydrocarbon Load-Following Fuel Cell Vehicle

Hybrid vehicles have been in the news quite a bit of late given the commercial introduction of a number of hybrid vehicles that sport significant improvements in fuel economy. The improved fuel efficiency of these vehicles can be directly attributable to the hybridized power train on board these internal combustion engine vehicles. Similarly, hybridization of fuel cell vehicles not only helps improve fuel economy but can also help overcome other technical barriers (start up delays, transients). For fuel cell vehicles, hybridization of on-board fuel cell systems is expected to have the potential to improve the vehicle efficiency largely due to the ability to recover braking energy and via flexibility in designing the system controls. However, the advantages can be offset by the tradeoffs due to added energy losses associated with the DC/DC converter and the battery pack itself.
Technical Paper

A Comparison of Fuel-Cut Ageing during Retardation and Fuel-Cut during Acceleration

The effect of various fuel-cut agings, on a Volvo Cars 4-cylinder gasoline engine, with bimetallic three-way catalysts (TWCs) was examined. Deactivation during retardation fuel-cut (low load) and acceleration fuel-cut (high load, e.g. gearshift or traction control) was compared to aging at λ=1. Three-way catalysts were aged on an engine bench comparing two fuel-cut strategies and their impact on of the life and performance of the catalysts. In greater detail, the catalytic activity, stability and selectivity were studied. Furthermore, the catalysts were thoroughly analyzed using light-off and oxygen storage capacity measurements. The emission conversion as a function of various lambda values and loads was also determined. Fresh and 40-hour aged samples showed that the acceleration fuel-cut was the strategy that had the highest contribution towards the total deactivation of the catalyst system.
Technical Paper

A Comparison of Motorcycle Braking Performance with and without Anti-Lock Braking on Dry Surfaces

This paper analyzes motorcycle braking characteristics during stops at various speeds on a dry, asphalt surface with and without the use of the anti-lock brake system (ABS). To characterize the braking performance of the motorcycle, threshold brake stops were performed on a motorcycle of the superbike category at various speed increments. Motorcycle and brake system outputs consisting of brake pressures, wheel speeds, accelerations and yaw rates were measured and analyzed to highlight the different characteristics between a motorcycle with an integrated anti-lock brake system and multiple anti-lock brake system rider modes. Three different brake input strategies were used to brake the motorcycle; a front only brake application, a front and rear brake application, and a rear only brake application. The anti-lock brake system rider modes consist of a sport setting, a race setting and a setting that deactivates the anti-lock brake system.