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This paper describes a multi-degree-of-freedom model of a three-wheeled car implemented in Matlab®. The purpose was to investigate the dynamics of the car (assumed to be rigid on its suspension) during cornering. While the problems associated with three-wheeled cars are well known, much of the guidance in the literature and off-the-shelf software assumes a conventional four-wheeled car. Consequently, the authors were approached with a battery-electric concept car which was thought to offer better performance than the existing variants because the use of hub motors lowered the center of gravity and, hence, reduced rollover coefficient. However, simulation of the vehicle model in cornering shows that the concept is still prone to instability. Indeed, it suffers greater roll velocities than a comparable three-wheeled car with an internal combustion engine (ICE) because the ratio of sprung to unsprung mass is significantly altered.

A plug-in, charge-depleting, parallel hybrid powertrain has been developed for a high performance sport utility vehicle. Based on the Ford U152 Explorer platform, implementation of the hybrid powertrain has resulted in an efficient, high performance vehicle with a 0-60 mph acceleration time of 7.5 seconds. A dual drive system allows for four-wheel drive capability while optimizing regenerative braking and minimizing electric motor cogging losses. Design of the system focused on reducing petroleum use, lowering greenhouse gas emissions, and reducing criteria tailpipe emissions. Additionally, this vehicle has been designed as a partial zero emissions vehicle (PZEV), allowing the driver to travel up to 50 miles in a zero emission all-electric mode. High-energy traction battery packs can be charged from the grid, yielding higher efficiencies and lower critical emissions, or maintained through the internal combustion engine (ICE) as with a traditional hybrid vehicle.

Yosemite is an advanced hybrid electric vehicle built on the Ford U152 Explorer platform. The University of California, Davis, FutureTruck team designed Yosemite to meet the following objectives: 1 Maximize vehicle energy efficiency 2 Minimize petroleum consumption 3 Reduce fuel cycle greenhouse gas emissions 4 Achieve California Super Ultra Low Emission Vehicle (SULEV) target 5 Deliver class-leading performance The University of California, Davis FutureTruck team redesigned a 2002 Ford Explorer as a Hybrid Electric Vehicle to meet the following goals: reduce fuel cycle greenhouse gas emissions by 67%, double the fuel economy of a stock Explorer, meet California's Super Ultra Low Emissions Vehicle standard, and qualify for substantial Partial Zero Emissions Vehicle credits in California. Yosemite meets these goals with an efficient flexible fuel hybrid powertrain, improved component systems, and an advanced control system.

Fuel cell engines are expected to deliver greater efficiency and lower emissions than conventional transit bus powertrains in the near future. Although experimental vehicles have demonstrated the emission and efficiency benefits of fuel cell power, the next step toward implementation is widespread fleet demonstrations to prove the technology in the field. In order to aid in the start of new demonstrations and speed fuel cell technology towards the fleet vehicle marketplace, an assessment of the needs, risks, and advantages of using fuel cell power must be obtained from a consumer perspective. It has been assumed that the increased fuel efficiency that is inherent to fuel cell systems will lower operating costs as compared with conventional diesel powertrains. A comparison of two fuel cell buses and a diesel bus was completed in order to quantify the operational cost benefits and identify potential cost deterrents to fuel cell bus implementation.

The University of California, Davis FutureTruck team redesigned a 2000 Chevrolet Suburban as a Hybrid Electric Vehicle to meet the following goals: reduce fuel cycle greenhouse gas emissions by 66%, increase vehicle fuel economy to double that of the stock Suburban, meet California's Super Ultra Low Emissions Vehicle standard, and qualify for substantial Partial Zero Emissions Vehicle credits in California. Sequoia meets these goals with an efficient powertrain, improved component systems, and an advanced control system. Sequoia utilizes two independent powertrains to provide Four-Wheel Drive and achieve stock towing capacity. The primary powertrain combines a 1.9L gasoline engine inline with a 75 kW brushless DC motor driving the rear wheels. This powertrain configuration is simple, compact, reliable, and allows flexibility in control strategy. The secondary powertrain employs a 75 kW brushless DC motor to drive the front differential.

Near term (ca. 2005) Fuel Cell Vehicles (FCVs) will primarily utilize Direct-Hydrogen Fuel Cell (DHFC) systems. The primary goal of this study was to provide an analytical basis for including a realistic Compressed Hydrogen Gas (CHG) fuel supply simulation within an existing dynamic DHFC system and vehicle model. The purpose of this paper is to provide a tutorial describing the process of modeling a hydrogen storage system for a fuel cell vehicle. Three topics were investigated to address the delivery characteristics of H2: temperature change (ΔT), non-ideal gas characteristics at high pressures, and the maximum amount of hydrogen available due to the CHG storage tank effective “state-of-charge” (SOC) -- i.e. how much does the pressure drop between the tank and the fuel cell stack reduce the usable H2 in the tank. The Joule-Thomson coefficient provides an answer to the expected ΔT during expansion of the H2 from 5000 psi to 45 psi.

The problem of vehicle stability in emergency maneuvers has attracted a lot of research effort recently. Perhaps the most effective contributions made in this area were devoted to the control of vehicle yaw rate either by active steering or differential braking control systems. Each control technique has its own limitations that make it ineffective in some particular situations. This paper introduces a combined steering and braking control strategy using a fuzzy logic inference system. The proposed controller uses the estimated coefficient of friction (μ) to organize the combined control action. Computer simulation using a comprehensive vehicle model is used to illustrate the strengths and limitations of various control strategies.

An Automated Highway System (AHS) represents the next major enhancement to the Nation's highway system. Envisioned AHS configurations typically require a mixture of intelligence in both the vehicle and the infrastructure. Here, the infrastructure includes the roadway, roadside, check-in and check-out points, vehicle-to-roadside communications systems, and any other systems external to the vehicle that are required for the safe and efficient operation of an AHS. Due to the complexity of an AHS and the required level of safety and reliability, it will be necessary to develop innovative techniques to rapidly and accurately inspect, monitor, and maintain the health of the required infrastructure, particularly after construction and natural disasters, such as earthquakes or flooding.

Automated Highway Systems (AHS) will likely have numerous items including sensors and other electronics that are not present in conventional highways, and these pose both unique problems and opportunities from a maintenance and construction viewpoint. This paper reports on a new and unique concept for maintaining AHS which could also benefit traditional highway operations. The paper discusses a system of multiple wheeled mobile robots that are coordinated to accomplish complex tasks, and are tethered to a support vehicle for accurate relative positioning, power, and other necessary supplies. Multiple coordinated WMRs are proposed since many AHS maintenance and construction operations will involve several concurrent subtasks.

The objective of this research is to create a new brake system with fewer mechanical parts, higher performance, greater flexibility for adaptation to new functions, and lower cost. A simple/series electro-hydrostatic brake system is investigated as an inexpensive, reliable, and redundant integrated brake system that can include the functions; Boost, ABS, TCS, VDC, etc. Production issues are considered. The required motor power is the most critical and is estimated by simulation based on data from experiments. To reduce this power a flow boost self-energizing mechanism with computer control is explored, and it is found that the effect is significant. Robustness of the control for pad friction fluctuation is also analyzed, and the limitation is estimated. The result of analysis shows that a competitive commercial product can be developed.

Several lead-acid battery packs of different manufacture and voltage were evaluated on a performance and life-cycle basis. The battery packs ranged from a small 36 volt laboratory pack to a 320 volt full size U.S. Electricar S-10 truck pack. The influence of the charge algorithm, ambient temperature, and module connection methods for parallel strings on the performance and cycle-life of this laboratory pack was studied. Finally, a survey of presently employed battery management techniques, used in three “production” electric vehicles, was conducted. A standard set of testing procedures for electric vehicle batteries, based on industry accepted testing procedures, were used in the evaluations. The battery packs were evaluated by a combination of constant current capacity tests, cyclical loading to simulate typical EV driving cycles and actual EV driving experience.

The zinc bromine battery is a high energy density sealed battery that utilizes a flowing electrolyte and low cost materials (predominantly plastic) and operates at ambient temperatures. The typical full scale specific energy for this bipolar plate battery is more then twice that of lead acid batteries. The engineering research presented in this paper is the design and construction of a high-voltage, zinc bromine battery for use in an electric vehicle. Specifically, a 390 volt system is being integrated into a US Electricar S10 light-duty truck. The research goal is to show a reliable and practical electrochemical power system that is lighter and provides a longer range and shorter recharge times than lead acid batteries. Results of this study will help determine the applicability and practicality of zinc bromine technology for electric vehicles.

The last few years have been an exciting time for alternative vehicle development. New concerns about the environmental impact of personal transportation and about the United States' dependence on imported oil have pushed energy efficient, ultra-low, and zero emissions vehicles to the forefront of automotive design. California's own mandate for Zero Emissions Vehicles (ZEV) takes effect in 1998, creating a tremendous push towards the difficult goal of producing a commercially viable, practical electric vehicle for sale in 1998. Beyond California, most of the world's automakers are simultaneously committing tremendous research and development resources towards the technology necessary for a viable electric vehicle. The University of California at Davis is one of seven California universities participating in the 1993 Ford Hybrid Electric Vehicle Challenge.