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This paper covers briefly the theory of tire-road friction, coefficient of friction measurement techniques, and the vagaries of tire-road friction as they relate to critical speed estimation. A literature review of tire-road friction studies was conducted to identify the primary factors effecting the tire-road coefficient of friction. Background information is presented covering general definitions and the connection between the basic critical speed formulas and the coefficient of friction. The primary components of tire-road friction, adhesion and hysteresis, are discussed along with minor effects such as tearing, wear, waves, and roll formation. Common coefficient of friction field measuring techniques are described, including the skid-to-stop test and drag sled. Influential factors such as tire characteristics, tire inflation pressure, road conditions, and dynamic factors are reviewed.

This paper presents the results of original research conducted to evaluate the braking characteristics of passenger vehicles equipped with anti-lock braking systems (ABS) as a function of vehicle speed at the beginning of a braking maneuver. The conditions studied in this paper are for braking on a dry, level roadway without any steering input. The objective of the paper is to study the effect of vehicle speed on the braking systems of common vehicles currently in-use. Comparisons are made between ABS and locked-wheel braking for each vehicle. The subject of this paper is part of the general topic of passenger vehicle dynamics and stability. Knowledge of how a vehicle performs under a variety of braking conditions is important for a variety of applications such as 1) intelligent vehicle highway systems, 2) vehicle stability and control, 3) vehicle dynamics, and 4) accident reconstruction.

This paper presents the results of original research conducted to evaluate the braking characteristics of passenger vehicles equipped with anti-lock braking systems (ABS) as a function of brake-pedal application force. The conditions studied in this paper are for braking on a dry, level roadway without any steering input. The objective of the paper is to study the effect of brake-pedal application force on the braking systems of common vehicles currently in-use. Comparisons are made between ABS and locked-wheel braking for each vehicle. The subject of this paper is part of the general topic of passenger vehicle dynamics and stability. Knowledge of how a vehicle performs under a variety of braking conditions is important for a variety of applications such as 1) intelligent vehicle highway systems, 2) vehicle stability and control, 3) vehicle dynamics, and 4) accident reconstruction.

This paper provides an exposition of the basic and some refined inertial critical speed estimation formulas. A literature review of existing inertial formulas for estimating critical cornering speed were identified for the ultimate purpose of developing a useful, compact, and more accurate speed estimation formula. Background information is presented covering the general definitions and utility of critical speed formulas. First, as a point of reference, the basic critical speed formulas are derived. Included is a list of the key assumptions on which the basic formulas are based. It is shown that the basic formulas are founded on the fundamental principles of physics and engineering mechanics; namely, Newton's Second Law and centrifugal force.

Cylinder liner rotation (Rotating Liner Engine, RLE) is a new concept for reducing piston assembly friction in the internal combustion engine. The purpose of the RLE is to reduce or eliminate the occurrence of boundary and mixed lubrication friction in the piston assembly (specifically, the rings and skirt). This paper reports the results of experiments to quantify the potential of the RLE. A 2.3 L GM Quad 4 SI engine was converted to single cylinder operation and modified for cylinder liner rotation. To allow examination of the effects of liner rotational speed, the rotating liner is driven by an electric motor. A torque cell in the motor output shaft is used to measure the torque required to rotate the liner. The hot motoring method was used to compare the friction loss between the baseline engine and the rotating liner engine. Additionally, hot motoring tear-down tests were used to measure the contribution of each engine component to the total friction torque.

This paper investigates the effect of real-time control system computational delay on the performance of a hybrid adaptive cruise control (ACC) system during braking/coasting scenarios. A hierarchical hybrid ACC system with a finite state machine (FSM) at the high-rank and a nonlinear sliding mode controller (SMC) at the low-rank is designed based on a vehicle dynamics model with a brake-by-wire platform. From simulations, parametric studies are used to evaluate the effect of the bounded random computational delay on the system performance in terms of tracking errors and control effort. The effect of the computational delay location within the control system hierarchy is also evaluated. The system performance generally becomes worse as the upper boundary of the computational delay increases while the effect of the computational delay located at the high-rank controller is more pronounced.

In this paper, functional analysis is employed to develop an ideal path of a vehicle undergoing a limit lane-change maneuver. Inputs to the problem are the lane width, tire-road coefficient of friction and either vehicle velocity or total longitudinal lane-change distance. Vehicle velocity is assumed to be constant. The problem is formulated using the calculus of variations. The solution technique relies on elliptic functions to achieve a closed-form solution. The synthesis of an ideal lane-change trajectory is treated as a minimal-energy-curve optimization problem with prescribed continuity and boundary conditions. The concept of critical speed is employed to limit the maximum curvature of any specified lane-change, thereby ensuring that the synthesized trajectory function describes a path that can be traversed under realistic road conditions. The analytical solution is confirmed by comparison to a numerical solution and a validated 8 degree-of-freedom vehicle model simulation.