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A non-linear contact analysis of a leading-trailing shoe drum brake, using the finite element method, is presented. The FE model accurately captures both the static and pseudo-dynamic behaviour at the friction interface. Flexible-to-flexible contact surfaces with elastic friction capabilities are used to determine the pressure distribution. Static contact conditions are established by initially pressing the shoes against the drum. This first load step is followed by a gradual increase of applied rotation to the drum in order to define the maximum reacted braking torque and pseudo-dynamic pressure distribution at the transition point between sticking and sliding motion. The method clearly illustrates the changes in contact force that take place as a function of the applied pressure, coefficient of friction and initial gap between lining and rotor. These changes in contact area are shown to influence the overall stability and therefore squeal propensity of the brake assembly.

This paper proposes an advanced control strategy to improve vehicle handling and directional stability by integrating either Active Front Steering (AFS) or Active Rear Steering (ARS) with Variable Torque Distribution (VTD) control. Both AFS and ARS serve as the steerability controller and are designed to achieve the improved yaw rate tracking in low to mid-range lateral acceleration using Sliding Mode Control (SMC); while VTD is used as the stability controller and employs differential driving torque between left and right wheels on the same axle to produce a relatively large stabilizing yaw moment when the vehicle states (sideslip angle and its angular velocity) exceed the reference stable region defined in the phase plane. Based on these stand-alone subsystems, an integrated control scheme which coordinates the control actions of both AFS/ARS and VTD is proposed. The functional difference between AFS and ARS when integrated with VTD is explained physically.

A number of handling models of a small high performance formula type racing car have been produced. These have been used to optimise the performance of the vehicle whilst under going simple manoeuvres and around a complete race track. Recently the vehicle was fitted with a data acquisition system and objective data was taken of the vehicle's handling performance. The paper details an investigation into the accuracy of two (a simple and more sophisticated) vehicle handling models in predicting the actual vehicle's performance from the data collected by comparing measured and simulated results. The investigation studies the steady state and transient response of the vehicle up to the limit of the vehicle's handling performance. A description is also given of the use of the more sophisticated model in a virtual race track simulation where it is used as a development tool to tune the performance of future vehicles.

This paper presents a method of control for a 6×6 series-configured Hybrid Electric Off-road Vehicle (HEOV). The vehicle concerned is an eight-tonne logistics support vehicle which utilizes Hub Mounted Electric Drives (HMED) at each of its six wheel stations. This set-up allows Individual Wheel Control (IWC) to be implemented to improve vehicle handling and mobility. Direct Yaw-moment Control (DYC) is a method of regulating individual wheel torque to control vehicle yaw motion, providing greater stability in cornering. When combined with both a Traction Control System (TCS) and an Anti-lock Braking System (ABS) the tire/road interaction is fully controlled, leading to improved control over vehicle dynamics, whilst also improving vehicle safety.

The main objective of this research was to validate the friction prediction capability of Ricardo Software products PISDYN and RINGPAK by comparing predictions with measured piston assembly friction force. The measurements were made by the University of Leeds on a single cylinder Ricardo Hydra gasoline engine using an IMEP method developed by the University. This technique involves the use of advanced instrumentation to make accurate measurements of cylinder pressure, crankshaft angular velocity and connecting rod strain. These measured values are used to calculate the forces acting on the piston assembly including the friction force. PISDYN was used by Ricardo to calculate friction force at the interface between the piston skirt and cylinder liner. The model used includes the effects of secondary dynamics, partial lubrication and piston skirt profile. RINGPAK was used by Ricardo to calculate the friction force at each piston ring.

A non-linear example vehicle model including four degrees of freedom (yaw, sideslip, roll and steering), non-linear kinematics and the Magic Formula tyre model has been developed. With the assumption of small perturbations around any steady-state working condition, the linearised equations are derived. A novel approach is used for the linearisation of external forces and moments from the tyres. They are linearised in terms of the state variables rather than the slip angle, camber angle and vertical load which are themselves functions of the state variables. The results of this process are expressed in terms of stability derivatives. In order to use the method, the steady-state solution of the non-linear equations is first obtained for a particular value of lateral acceleration, then after the calculation of the stability derivatives, a linear analysis can be performed for the linear equations in terms of perturbed variables.

A non-contacting laser displacement meter has been used for dynamic measurements of the radial movement of a v-ribbed belt (type 3PK) around the arc of wrap running on a belt testing rig. Accurate and repeatable results are possible. Using this device, the belt radial movement and the beginning of rib bottom / groove tip contact around the arc of wrap have been determined experimentally for v-ribbed belts. Slip, torque loss, maximum torque capacity and efficiency have been measured during the tests.

Many active control systems are developed as safety systems for passenger vehicles. These control systems usually focus on improving vehicle stability and safety while ignoring the effects on the vehicle driveability. In the motorsport environment, increased stability is desirable but not if the driveability of the vehicle is heavily compromised. In this work, active suspension and active drivelines are examined to improve vehicle dynamics and enhance driveability while maintaining stability. The active control systems are developed as separate driveability and stability controls and tested individually then integrated to create a multi-objective control system to improve both driveability and stability. The controllers are tested with standard vehicle manoeuvres.

Most active control systems developed for passenger vehicles are developed as safety systems. These control systems usually focus on improving vehicle stability and safety while ignoring the effects on the vehicle driveability. While stability is the primary concern of these control systems the driveability of the vehicle is also an important consideration. An example of compromised driveability in a stability control system is brake based active yaw control. Brake based systems are very effective at stability control but can have a negative impact on the longitudinal dynamics of a vehicle. The objective of the vehicle control systems developed for the future will be to preserve vehicle driveability while ensuring the stability of the vehicle. In this work, active suspension and active drivelines are developed as stability control systems that have a minimal impact on the driveability of the vehicle.