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Homogeneous charge compression ignition (HCCI) engines lack direct in-cylinder mechanisms, such as spark plugs or direct fuel injection, for controlling the combustion timing. Many indirect methods have been used to control the combustion timing in an HCCI engine. With any indirect method, it is important to have a measure of the combustion timing so the control inputs can be adjusted for the next cycle. In this paper, it is shown that microphones and knock sensors can be used to detect combustion in HCCI engines. The output from various microphones and a knock sensor on an HCCI engine are measured at light and high loads. The combustion timing data obtained from the sensors are compared to the combustion timing data obtained from a piezoelectric cylinder pressure transducer. One of these sensors is selected and used for closed-loop control of the combustion timing in a single cylinder HCCI engine.

The number and quality of sensors available for both on-board vehicle and infrastructure-based sensing is increasing while the cost of these sensors is rapidly decreasing. On-board vehicle sensors can be utilized for both individual vehicle safety as well as automated vehicle control. It is becoming imperative that "fusion" techniques be developed, i.e., methods to combine the wide variety of sensors available so that reliable and accurate information can be obtained even though individual sensors may fail or become extremely noisy. The process of sensor fusion combines multiple sensor measurements in order to provide an accurate and coherent view of the vehicle and its environment.

This report will present the results of the initial study to develop an accurate working model of the 40 foot New Flyer Bus powered by the Cummins C8.3+ 280G CNG engine (Figure 1.1). The main focus of the study is the modeling of the vehicle dynamics using step input acceleration data. Other parts of the research include gear shifting and torque production from the CNG engine, all of which are required to produce a completely simulationcapable bus model.

The dielectric properties are reported for nanoporous thin films of poly(methyl silsesquioxane) (MSSQ) for use as an ultralow, dielectric intermetal insulator. Direct experimental conformation is provided that the films have low dielectric constants with low loss up to 10 GHz. Low-frequency measurements are also reported.

The Xenopus laevis egg vitelline envelope is composed of five glycoproteins (ZPA, ZPB, ZPC, ZPD, and ZPX). As shown previously, ZPC is the primary ligand for sperm binding to the egg envelope, and this binding involves the oligosaccharide moieties of the glycoprotein (Biol. Reprod., 62:766-774, 2000). To understand the molecular mechanism of sperm-egg envelope binding, we characterized the N-linked glycans of the vitelline envelope (VE) glycoproteins. The N-linked glycans of the VE were composed predominantly of a heterogeneous mixture of high-mannose (5-9) and neutral, complex oligosaccharides primarily derived from ZPC (the dominant glycoprotein). However, the ZPA N-linked glycans were composed of acidic-complex and high-mannose oligosaccharides, ZPX had only high-mannose oligosaccharides, and ZPB lacked N-linked oligosaccharides. The consensus sequence for N-linked glycosylation at the evolutionarily conserved residue N-113 of the ZPC protein sequence was glycosylated solely with high-mannose oligosaccharides. This conserved glycosylation site may be of importance to the three-dimensional structure of the ZPC glycoproteins. One of the complex oligosaccharides of ZPC possessed terminal beta-N-acetyl-glucosamine residues. The same ZPC oligosaccharide species isolated from the activated egg envelopes lacked terminal beta-N-acetyl-glucosamine residues. We previously showed that the cortical granules contain beta-N-acetyl-glucosaminidase (J. Exp. Zool., 235:335-340, 1985). We propose that an alteration in the oligosaccharide structure of ZPC by glucosaminidase released from the cortical granule reaction is responsible for the loss of sperm binding ligand activity at fertilization.

We comparatively assess the influence of adaptive cruise control (ACC) and cooperative adaptive cruise control (CACC) systems on highway traffic behaviors. The primary goal is to study the design and implementation of vehicle-vehicle/roadside-vehicle communication, which enhances an ACC system to a CACC one. In addition, the impact of market penetration of ACC/CACC vehicles and controller aggression are also evaluated. Two simulation works are presented. The microscopic work simulates a single ACC/CACC vehicle using MATLAB/SIMULINK. A cut-in scenario and a braking scenario are tested. Vehicle-vehicle communication saves control effort in the former scenario, while shows little effect in the latter. In the macroscopic work we simulate ACC/CACC controlled highway merging with SHIFT language. The results show beneficial effects of communication in terms of braking effort, average velocity, waiting-to-merge queue length, and main lane traffic shock wave caused by merging. The higher the market penetration of controlled vehicles the better the system performs. The aggressiveness of controller has mixed influence, which provides a tradeoff between efficiency and safety. We study the wireless communication among highway vehicles. A vehicle- vehicle Location-Based Broadcast (LBB) communication protocol is designed to meet highway safety applications' communication requirements. The analytical expressions of the performance of the protocol in terms of probability of transmission failure and channel occupancy are derived with commonly satisfied assumptions. The optimal relation between the performance and design parameters is obtained from the expressions. The sensitivity of the protocol performance is tested for various communication conditions as well as highway traffic conditions. Feasible combinations of the communication and highway traffic parameters are found for certain requirements on protocol performance. The analysis is conducted in accordance to the communication condition in the newly-assigned 5.9 GHz Dedicated Short Range Communication (DSRC) spectrum. More experiments are done to find out the factors that influence the slip measurements in order to refine our results of friction coefficient estimation. To obtain the circumferential velocity of the wheel, the exact tire radius is needed. The change in the spring constant based on tire air pressure is obtained, and also the increase in tire radius due to the faster velocity is considered. The normal force applied on each wheel due to the vehicle pitch motion resulting from acceleration and deceleration is also estimated using static vehicle model. Brake torque sensor and accelerometer are used to find the normal force. Using the estimated normal force and road force, the tire-road friction coefficient is obtained. The characteristics of the friction coefficient and slip curve are studied on different road conditions with the refined slip measurements. An originally proposed slip-based controller does not seem to work very well in an practical situation due to actuator time delay. However, experimental results show that the existing nonlinear controller with the limited slip assumption shows good performance even in an emergency braking situation. Therefore, instead of using different control algorithm, this research focuses on the control strategies dedicated to emergency situation for the platoon. In order to integrate the benefits from the communication and friction coefficient estimation technique, a safe control strategy is considered in the situation when the platoon of vehicles needs to decelerate rapidly. It is assumed that we have the knowledge of friction coefficients between road and tire and our vehicles are equipped with proper communication methods. Then, the theoretical bounds for the reference trajectory accelerations are calculated that do not cause the actuator saturation using linear vehicle and controller model.

One of the main goals of an Automated Highway System environment is to increase the throughput of vehicles traveling on the highway. By moving vehicles in a platoon (a group of tightly spaced vehicles), the traffic flow capacity can be greatly increased. The control law developed for vehicles to safely travel in a platoon is dependent on the lead and preceding vehicle's velocity and acceleration profiles. This information guarantees string stability (i.e. spacing errors between vehicles do not increase down the chain of vehicles). These profiles are transmitted to the vehicle via wireless communication. Unfortunately, a perfect wireless communication does not exist. In this paper, the effects of various communication delays on string stability will be analyzed. The concept of platooning in an Automated Highway System (AHS) allows a group of vehicles to share information across a wireless local area network (LAN). This sharing of information allows vehicles belonging to the same platoon to maintain a smaller inter-vehicular spacing that would otherwise be possible. Of course, once these platoon/LANs exist on the AHS, a method must exist to add vehicles to a platoon and also to remove vehicles from a platoon. This report also develops handshaking protocols that allow the LANs associated with each platoon to reconfigure themselves in response to any physical changes to the composition of the platoon. Since the LANs operate over a wireless communication system, these protocols are designed to be robust towards packet losses, as well as satisfying certain safety and liveness conditions.

A new architecture for a mobile ad-hoc communication network is developed, and simulation results show that the proposed MAC protocol can enhance transmission success probability from 0 to 97%. Two novel applications of vehicle-to-vehicle networks are then developed and simulated. The first application is a \Cooperative Adaptive Cruise Con- trol" which uses communicated information to improve on ordinary cruise control systems. Communicating a \virtual brake light" between vehicles is shown to decrease the accelerations required to maintain safe following distances in cut-in and hard braking situations. The second application is a \Cooperative Estimation" algorithm. The idea behind this algorithm is that each vehicle on the road is potentially a driving condition \sensor." By combining data communicated from many vehicles on the roadway, the cooperative estimation algorithm is able to produce estimates of driving time and road condition that are significantly better than those that any one vehicle could produce on its own. While developing the cooperative road condition estimation algorithm, it is found that the problem's crux is at the vehicle level, so the friction estimation problem is then investigated at a vehicle/tire level through exten- sive experimentation. An exciting new type of \slip-based" road condition estimator is developed and experimentally shown to be able to distinguish between wet and dry roads using no dedicated road condition sensors sen- sors. In-depth literature review complements our own results and shows that \slip-based" estimators of the type developed may be very useful to help solve the AHS road condition estimation problem.

MOU308 provides solutions to two common brake control problems: variable brake torque gain and brake rotor-induced brake torque oscillations. The adaptive control solution for the variable brake torque gain problem is shown to work experimentally, and the algorithm to eliminate brake torque oscillations is demonstrated in simulation. In addition, documentation is provided for differential braking hardware, wheel speed measurement hardware, and a strain-based brake torque sensor that were constructed to test these algorithms.

The transient aerodynamic effects in a four-vehicle platoon during passing maneuvers and in-line oscillations are investigated. A vehicle model is moved longitudinally parallel to a four-car platoon to simulate passing maneuvers. The drag and side forces experienced by each platoon member are measure using strain gauge balances. The resulting data are presented as dimensionless coefficients.  It is show that each car in the platoon experiences a repulsive side force when the passing vehicle is in the neighborhood of its rear half. The side force reverses its direction and becomes an attractive force when the passing vehicle moves to the neighborhood of it front half.

Keywords longitudinal control, car platooning, back-stepping control, multi-surface dynamic sliding mode control, integral filters, realtime control code This report presents the development of nonlinear longitudinal controllers and their realtime implementation for Automated Highway Systems (AHS) at PATH, U. C. Berkeley supported by the project MOU 331. The demo'97 realtime code was first reconstructed for further development. Based on the new framework, the implementation and comparison of nonlinear controllers in the longitudinal control for cars platooning and other maneuvers have been carried out. Specifically, a dynamic sliding mode controller and a dynamic back-stepping multiple surface controller have been implemented, which are then compared to the previously implemented adaptive sliding mode controller. In the dynamic back-stepping control, a new type of integral filters have been developed, which were used for filtering measured signals and to estimate the derivative of these signals in realtime. These controllers have been implemented in realtime code and tested at low and high speed. Realtime run shows that each controller has its own characteristics. In general, the optimal dynamic back-stepping sliding surface controller has better performance by using the same set of measured data compared to previously implemented adaptive sliding mode controller. Emphasis has been put on the dynamic back-stepping multiple surface controller development.

This report presents the work on the development of the regulation layer for automated merging. It includes system modeling, control system synthesis, theoretical analysis and real-rime implementation and field test. The essential part is a rather general adaptive merging algorithm. Key words: automated highway systems, advanced vehicle merging maneuvers, automated vehicle merging maneuvers, longitudinal control, speed control, distance control, vehicle platooning, virtual platooning, adaptive realtime merging algorithm, back-stepping control, magnet distance measurement

In order to provide reliable control algorithms on PATH automated highway system, knowledge of the transient aerodynamic forces is important from the point of the controlla- bility of the platoon and individual vehicles. In a passing maneuver, the platoon members may experience severe aerodynamic forces and yaw moment when another vehicle overtakes. Similar phenomenon can be seen in our daily life as one car passes the other but much more complicated flow field is expected when the interaction involves in a multi-vehicle platoon. It is the purpose of this study to quantify the unsteady aerodynamic forces and moment so as to assure the safety of the system.

This report focuses on longitudinal issues regarding modeling and control of vehicles in an Intelligent Transportation Systems (ITS) setting. Specifically, the report addresses the issue of vehicle control in an automated highway system, brake actuation and brake control. Recent research findings in the area of automated vehicle platooning on isolated lanes of an automated highway are included. Performance specifications, control system architecture, vehicle control algorithms, actuator and sensor specifications and communication requirements are also discussed. The report also addresses the issue of switching from throttle to brake actuation.

In this report, a Cooperative Intelligent Cruise Control (CICC) System is proposed to increase highway capacity and provide safety and comfort to drivers. The method requires an automatic throttle and brake control and simple infrastructure-vehicle communication. The system is designed to let a vehicle operate under a conventional cruise control system as well as a distancing control system. The performance of the CICC is evaluated through simulations with a non-linear vehicle model.

This report investigates the problem of regulation-level vehicle control for combined lateral and longitudinal maneuvers in an automated highway system (AHS) setting. Intelligent vehicles are assigned to dedicated lanes by a decentralized roadside coordinator which suggests a desired velocity. Magnetic markers embedded in the road, are used to provide geometry, and lateral and longitudinal position reference. Relative vehicle spacing information is obtained via a radar or vision referencing system. Onboard inertial sensors are utilized to provide a measure of the vehicle's absolute motion.

This report begins with an examination of autonomous lateral vehicle control. This is followed by a section on Cooperative Intelligent Cruise Control (CICC). The effect of communication delays on the control performance of vehicle platoons is then examined. The report concludes with a study of the three basic transition maneuvers in an Automated Highway System: join, split, and lane change.

This report studies performance issues in Automated Vehicle Control Systems (AVCS). Specifically, it addresses the automatic braking controller design issues, effects of braking on Intelligent Vehicle Highway Systems (IVHS) lane capacity, performance of platoons with various information structures, and fault detection filter design for AVCS.

In this report, a combined longitudinal and lateral eighteen-state vehicle chassis, engine, and drive train model is developed and validated against existing longitudinal-only and lateral-only vehicle models. The full-size model is simplified to a three-state model to facilitate controller design. The control task in a combined maneuver is defined as the simultaneous regulation of the vehicle's longitudinal and lateral spacings through the application of throttle and steering. Two forms of a Sliding control law are derived based on the reduced order model. One version is decoupled in the longitudinal and lateral dynamics and forces, while the other retains the coupling terms. Nominal stability of the controllers is shown.

The first section of this report addresses the issues of vehicle control during transition maneuvers in Intelligent Vehicle Highway Systems. Transition maneuvers include automatic lane change of vehicles and merging and splitting of platoons of vehicles in the automated highway system. The second part of the report addresses the issues involved in implementation of the longitudinal control laws for vehicle control in Automated Highway Systems.

This report addresses some of the important longitudinal vehicle modeling and control issues of Advanced Vehicle Control Systems (AVCS) such as brake dynamic model development and validation, decentralized longitudinal control algorithms which guarantee the stability of the entire platoon and fault detection and isolation in the longitudinal vehicle dynamics of controlled vehicles.

The aim of this report is to study issues concerning fault detection and identification in vehicle follower control. The report discusses various potential fault modes among sensors, and actuators used in the vehicle following experiments in cars. It deals with issues of fault detection of sensors and actuators for vehicle following applications.

This report summarizes recent work done in the area of longitudinal control of a platoon of autonomous vehicles. As a prerequisite to controller design, a twelve state nonlinear model including an internal combustion engine, engine transmission dynamics, and tire friction characteristics has been developed. Two simplified models for simulation and controller design are presented. After outlining the control problem, two platooning strategies, based on spacing or headway criterion, are proposed. To solve the control requirements, decentralized nonlinear control strategies using throttle angle and brake torque control for a platoon were developed using a modification of the technique of Sliding Control and Input-Output Linearization. The quantities of primary concern are position and velocity tracking errors. Simulation results on multiple vehicle platoons demonstrate excellent tracking using the spacing-based controllers. The control strategies were implemented experimentally on the Integrated Platoon Control System (IPCS) during two and four car platoon testing.

Our roads are crumbling under the weight of buses and heavy truck loads. Although early researchers attributed the pavement damage to a fixed, "static" factor - the vehicle's weight and design - we now know that much of the blame is owed to "dynamic" variables - the interaction between the vehicle's suspension and the road surface. Recent studies show that dynamic force can double, even quadruple, pavement damage. But by equipping trucks and buses with advanced, "semi-active" suspensions, the problem of road wear can be effectively addressed. We are anticipating an up to 20 percent reduction in tire force on pavement surfaces.

With this first issue of Access, we at the University of California Transportation Center seek to introduce our research to a diverse community of readers. By presenting our findings in a nontechnical format, we hope to make them accessible to professionals in various fields and to citizens who might find them useful or perhaps merely interesting.

This report deals with an introduction to the control aspect of platoon maneuvers in Automated Highway Systems. The different platoon maneuvers include lane changes, merge procedures and split procedures. The first part of the report consists of a review of the existing literature in this area. The survey is split up into the quasi-synchronous and vehicle follower controller methods of approach to the problem. The subsequent sections deal with the mathematical description of the problem with two representations of the system under study, varying only in level of model complexity. The simplified model has been studied with a linear based control as well as the nonlinear sliding mode approach. The results only reinforce the need for nonlinear systems analysis and control. The sliding control technique has also been applied to study the detailed version of the plant.