A proper tire friction model is essential to model overall vehicle dynamics for simulation, analysis, or control purposes since a ground vehicle's motion is primarily determined by the friction forces transferred from roads via tires. Motivated by the developments of high-performance antilock brake systems (ABSs), traction control, and steering systems, significant research efforts had been put into tire/road friction modeling during the past 40 years. In this paper, a review of recent developments and trends in this area is presented, with attempts to provide a broad perspective of the initiatives and multidisciplinary techniques for related research. Different longitudinal, lateral, and integrated tire/road friction models are examined. The associated friction-situation monitoring and control synthesis are discussed with a special emphasis on ABS design

Integrated longitudinal and lateral tire/road friction modeling and monitoring for vehicle motion control

Intelligence in vehicles has developed through the years as self-driving expectations and capabilities have increased. To date, the majority of the literature has focused on longitudinal control topics (e.g. Adaptive Cruise Control (ACC), Cooperative ACC (CACC), etc.). To a lesser extent, there have been a variety of research articles specifically dealing with lateral control, e.g., maneuvers such as lane changes and merging. This paper provides a survey of this particular area of vehicle automation. The key topics addressed are control systems, positioning systems, communication systems, simulation modeling, field tests, surroundings vehicles, and human factors. Overall, there has been some successful research and field testing in lane change and merge maneuvers; however, there is a strong need for standardization and even more research to enable comprehensive field testing of these lateral maneuvers, so that commercial implementation of automated vehicles can be realized.

Lane Change and Merge Maneuvers for Connected and Automated Vehicles: A Survey

This paper presents a vehicle adaptive cruise control algorithm design with human factors considerations Adaptive cruise control (ACC) systems should be acceptable to drivers In order to be acceptable to drivers, the ACC systems need to be designed based on the analysis of human driver driving behaviour Manual driving characteristics are investigated using real-world driving test data The goal of the control algorithm is to achieve naturalistic behaviour of the controlled vehicle that would feel natural to the human driver in normal driving situations and to achieve safe vehicle behaviour in severe braking situations in which large decelerations are necessary A non-dimensional warning index and inverse time-to-collision are used to evaluate driving situations A confusion matrix method based on natural driving data sets was used to tune control parameters in the proposed ACC system Using a simulation and a validated vehicle simulator, vehicle following characteristics of the controlled vehicle are compared with real-world manual driving radar sensor data It is shown that the proposed control strategy can provide with natural following performance similar to human manual driving in both high speed driving and low speed stop-and-go situations and can prevent the vehicle-to-vehicle distance from dropping to an unsafe level in a variety of driving conditions

Human driving data-based design of a vehicle adaptive cruise control algorithm

This paper presents a novel real-time tire-road friction coefficient estimation method that is independent of vehicle longitudinal motion for ground vehicles with separable control of the front and rear wheels. The tire-road friction coefficient information is of critical importance for vehicle dynamic control systems and intelligent autonomous vehicle applications. In this paper, the vehicle longitudinal-motion-independent tire-road friction coefficient estimation method consists of three main components: 1) an observer to estimate the internal state of a dynamic LuGre tire model; 2) an adaptive control law with a parameter projection mechanism to track the desired vehicle longitudinal motion in the presence of tire-road friction coefficient uncertainties and actively injected braking excitation signals; and 3) a recursive least square estimator that is independent of the control law, to estimate the tire-road friction coefficient in real time. Simulation results based on a high-fidelity CarSim full-vehicle model show that the system can reliably estimate the tire-road friction coefficient independent of vehicle longitudinal motion.

Adaptive Vehicle Speed Control With Input Injections for Longitudinal Motion Independent Road Frictional Condition Estimation

Knowledge of tire force potential, i.e., tire-road frictional coefficient, is important for vehicle active safety systems because tire-road friction is an effective measure of the safety margin of vehicle dynamics. For vehicle handling dynamics, the frictional coefficient is highly coupled with tire slip angle, therefore, they need to be estimated simultaneously when the latter is not measured. This paper presents an estimation algorithm based on a robust adaptive observer methodology. Stability and robustness of this observer are analyzed numerically. The performance is analyzed using computer simulations and experiments under various road and steering conditions.

Robust Estimation of Road Frictional Coefficient

This paper presents a real-time maximum tire-road friction coefficient estimation method and field test results. The estimator is based on the relationship between the wheel slip ratio and the friction coefficient. An effective tire radius observer and a tire normal force observer have been designed for the computation of the slip ratio from wheel speed and vehicle speed measurements. The effective tire radius observer has been used so that the proposed method works for all driving situations. A tractive force estimator, a brake gain estimator, and a normal force observer have been used for the estimation of the friction coefficient. The proposed estimation method for the maximum tire-road friction coefficient has been implemented using a fifth wheel and typical vehicle sensors such as engine speed, carrier speed, throttle position, and brake pressure sensors.

Real-time slip-based estimation of maximum tire-road friction coefficient

This paper represents an investigation of the vehicle-to-vehicle distance control system using Hardware-in-the-Loop Simulation(HiLS). Control logic is primarily developed and tested with a specially equipped test vehicle. Establishment of an efficient and low cost development tool is a very important issue, and test vehicle approach is costly and time consuming. HiLS method is useful in the investigation of driver assistance and active safety systems. The HiLS system consists of a stepper motor for throttle control, a hydraulic brake system with an electronic vacuum booster, an electronic controller unit, a data logging computer which are used to save vehicle states and signals of actuator through a CAN and a simulation computer using mathematical vehicle model. Adaptation of a CAN instead of RS-232 Serial Interface for communication is a trend in the automotive industry. Since this environment is the same as a test vehicle, a control logic verified in laboratory can be easily transferred to a test vehicle.

An Investigation of Vehicle-to-Vehicle Distance Control Laws Using Hardware-in-the Loop Simulation

This paper describes the design and evaluation of an integrated control strategy for longitudinal safety and lateral stability. The objective of the integrated control strategy is to optimally coordinate independent brake inputs for longitudinal collision-safety and lateral stability in various driving situations such as lane change with braking and circular turning with braking, etc. The proposed integrated vehicle safety system is applied to the vehicle equipped with Smart Cruise Control (SCC)/Collision Avoidance (CA) and Vehicle Stability Control (VSC). The proposed control system consists of a supervisor, control algorithms, and a coordinator. The proposed system has three control modes which are normal driving, integrated safety I, and integrated safety II. According to the corresponding control mode, the longitudinal and lateral control algorithms calculate the desired motion of the subject vehicle. Based on the desired longitudinal force and the desired yaw moment, the coordinator determines the throttle angle and the brake pressures by using optimal distribution. Closed-loop simulations with the driver-vehicle-controller system are conducted to investigate the performance of the proposed integrated vehicle safety system. Finally, the proposed control system was also implemented in a sport utility vehicle and tested in several driving situations.

Design and Evaluation of an Integrated Vehicle Safety System for Longitudinal Safetyand Lateral Stability

This paper presents an impact assessment of enhanced safety by Advanced Cruise Control (ACC) systems The objective of the authors study is to assess the enhancement of the driving safety between with and without the ACC system For the impact assessment of the ACC system, the system performance test data as well as the usual driving data should be used to assess direct and indirect safety impacts Therefore the proposed methodologies were developed by using the collected data from the Field Operational Test (FOT) and the evaluation scenario based test for conducting the safety impact assessment of the ACC system First, five (5) vehicles equipped with ACC system will take part in the field operational test so that the authors can make the FOT database By using the collected database, changes of crash risk between with and without ACC system are used to quantify the impact of the ACC system Second, to make up for the missed the FOT data, test scenario based ACC performance test was conducted From the scenario based test, system’s physical performance in the specific driving situations can be evaluated Finally, impact assessment of the ACC system can be obtained by combining FOT based analysis and scenario based test results By using the proposed assessment methods, the impact assessment with respect to impacts on safety by the ACC system can be assessed scientifically

Impact Assessment of Enhanced Longitudinal Safety by Advanced Cruise Control System

A mathematical model and control laws for an Electronic-Vacuum Booster (EVB) For application to vehicle cruise control will be presented. Also this paper includes performance test result of EVB and vehicle cruise control experiments. The pressure difference between the vacuum chamber and the apply chamber is controlled by a PWM-solenoid-valve. Since the pressure at the vacuum chamber is identical to that of the engine intake manifold, the output of the electronic-vacuum booster is sensitive to engine speed. The performance characteristics of the electronic-vacuum booster have been investigated via computer simulations and vehicle tests. The mathematical model of the electronic-vacuum booster developed in this study and a two-state dynamic engine model have been used in the simulations. It has been shown by simulations and vehicle tests that the EVB-cruise control system can provide a vehicle with good distance control performance in both high speed and low speed stop and go driving situations.

Chankyu Lee

Papers

Real-time slip-based estimation of maximum tire-road friction coefficient

An Investigation of Vehicle-to-Vehicle Distance Control Laws Using Hardware-in-the Loop Simulation

Design and Evaluation of an Integrated Vehicle Safety System for Longitudinal Safetyand Lateral Stability

Impact Assessment of Enhanced Longitudinal Safety by Advanced Cruise Control System

Modeling and Control of an Electronic-Vacuum Booster for Vehicle Cruise Control