The aim of the paper is to investigate the design of active suspensions aimed at improving of the ride vibration behaviour of trucks and incorporating the effects of the flexible frame in the dynamic behaviour. The work is a theoretical study and deals with improvements of the ride comfort, structural acceleration, suspension working spaces and dynamic tyre loads. The road surface profile is considered to be a continuous, random process and is modelled as a filtered white noise excitation. The time delay between the excitation inputs of the vehicle axles is included and modelled using the Pade approximation technique. The FEM (finite element method) and the modal superposition theory have been used to calculate the modal properties of the frame structure. The Lagrangian approach has been applied to obtain the energy equations of the vehicle system motions which result from the well known rigid body modes and from the modal parameters of the frame structure flexibility. Linear stochastic optimal control theory has been used to obtain the optimal active suspension for the truck system based on the full state controller strategy. The performance of the passive system is compared with the performance of the optimal actively controlled systems for two cases, one in which control law accounts for the preview effect that the input at the rear is a delayed version of that at the front (referred to as correlated) and one in which the control law does not (uncorrelated). The results show that the modelling technique is a useful design aid for studying the dynamics and control of complex vehicle structures. It is shown that active suspension controllers offer significant improvements over passive systems in acceleration levels, suspension workspace and dynamic tyre load.

The background to the development of so-called green or low-carbon vehicles continues to be relentlessly reviewed throughout the literature. Research and development (R&D) on novel powertrains – often based on electric or hybrid technology – has been dominating automotive engineering around the world for the first two decades of the twenty-first century. Inevitably, most of the R&D has focused on powertrain technology and energy management challenges. However, as new powertrains have started to become commercially available, their effects on other aspects of vehicle performance have become increasingly important. This article focuses on the review of the integration of new electrified powertrains with the vehicle dynamics and control systems. The integration effects can be discussed in terms of three generic aspects of vehicle motions, namely roll-plane, pitch-plane and yaw-plane, which however are strongly coupled. The topic on regenerative suspension is further discussed. It quickly becomes clear that this integration poses some interesting future engineering challenges to maintain currently accepted levels of ride, handling and stability performance.

The article 'Performance of multicone synchronizers for manual transmissions' by N. A. Abdel-Halim, D. C. Barton, D. A. Crolla, and A. M. Selim published in Proc. IMechE, Part D: J. Automobile Engineering, 2000, 214(1), 55-65, DOI: 10.1243/0954407001527213 is incorrect. The following corrections apply:.

The paper describes some simple modelling to investigate whether there are potential benefits to incorporating a geared transmission in electric vehicle driveline.The overall conclusion is that considerable benefits in energy consumption are available if a continuously variable gearbox system is incorporated; performance improvements of 6 to 19 2 % are predicted over a range of European, USA and Japanese driving cyclesFurthermore, the use of a much simpler, two speed gearbox an improve performance significantly - by for example 9.2% over the NEDC cycle - although similar improvements are not predicted over other driving cyclesOverall, the results suggest not only that direct benefits in terms of energy reductions are obtainable, but also that significant reductions in motor and driveline sizing may be an alternative approach to exploiting the introduction of a transmission system.

The current level of interest in electric vehicles (EVs) could hardly be overstated as manufacturers and governments around the world appear to have increased interest at a staggering rate. The resurgence of current interest in the early part of the 21st century has been driven by both political and technological developments, namely a requirement to control global emissions and the emergence of new battery designs with improved specific energy, energy density and rechargability properties. One of the great advantages of the electric motor is its torque characteristic which provides maximum torque from zero up to low speeds, and then it is governed by the maximum power available as motor speed increase. This has two significant advantages over the typical torque-speed properties of the competing IC engine: (1) It is fundamentally a more desirable characteristic spread of torque over the speed range in contrast to the peakiness of an IC engine. (2) It removes the need for any additional transmission clutch or gears. However, one of the main conclusions to emerge from the plethora of research work into energy efficient vehicles is that it is necessary to pursue every possible avenue for minor efficiency gains. It is therefore of interest to investigate whether it is possible to manage the efficiency of the electric motor, so that by using an intermediate gearbox the motor is operated more often in its higher efficiency region. The aim of this paper is to develop a simple EV model and predict its energy consumption with a variable and fixed ratio gearbox over a standard driving cycle in order to understand whether this could offer significant efficiency gains. The emerging conclusions are that it is possible to improve overall energy consumption levels by around 5 to 12% with a variable ratio gearbox depending on the driving cycle used. However, there are many other practical considerations which must be weighed against this positive result and the paper discusses the impact of several of these such as, gearbox efficiency, additional weight, cost and complexity, effect on drivability and potential for motor downsizing.

The control problem for a hybrid vehicle powertrain is commonly tackled as an optimal control problem, although this is often used in a general sense as opposed to a strict mathematical definition. The problem may be characterised in many ways depending on the performance objective, the hybrid vehicle model considered, the constraints imposed and the available control actions. However, as a general dynamics and control problem it is clearly not straightforward, and is likely to involve combinations of linear and non-linear elements, discrete and continuous systems, algebraic and dynamical systems.

The development of chassis control schemes has been a major area of study for automotive control engineers over the past 30 years. The volume of published literature is large, exceeding 1000 papers. Of this literature, there are 250 examining yaw and sideslip control. Here is a comprehensive review of this field of study to identify the current state of the art and research in yaw rate and sideslip control. The survey shows that there is still a significant research effort needed to address the subjective performance of handling systems, and more research is needed to develop schemes that integrate systems to achieve high-level performance objectives.

This paper describes the development and use of a multi-body co-simulation approach for predicting the dynamic response of a vehicle containing magnetorheological (MR) semi-active dampers. The approach is used to investigate the effects of various local and global control strategies on the load histories of suspension components for the purpose of assessing their likely impact on fatigue life. The approach adopted aims to exploit the capability of a multi-body system (MBS) code and a mathematical simulation code, by integrating the MBS vehicle models with selected semi-active damper/controller models. Various MBS vehicle models are developed of increasing complexity using MSC.visualNastran, which are linked to three local, two-state switchable, control algorithms and also two global controllers, each developed in MATLAB/Simulink. The control strategies are implemented within the vehicle model using an MR damper model derived from experimental test data. Road inputs, including both bump/pothole and random road excitation, and the tyre model are also implemented within MATLAB/Simulink. Ultimately, the aim is to develop an approach which would allow concurrent structural optimization and controller optimization to enable lighter and more durable suspension components to be produced.

The design of hybrid vehicles inevitably involves two, or sometimes more, power sources. Although successful designs have required a whole range of technological developments, two particular aspects are highlighted here (a) the power splitting or power combining transmission often based on a combination of mechanical and electrical components and (b) the supervisory control strategy for managing the power flows to obtain both high efficiency and good driveability.

Control systems designed to optimize vehicle performance, such as antilock braking systems or traction control systems, depend upon a knowledge of the amount of available grip at the tyre-road contact point. There have been both qualitative and quantitative approaches to identify the road surface coefficient of friction, mu. This work proposes a method of estimating the longitudinal and lateral grips for use within a control system. The estimation method is explained and the vehicle model equations used are stated. The estimator is then tested using logged data from a test vehicle, and the force estimates are validated against results from strain-gauged wheel rims. Finally, the direction of future work is described.

An integrated vehicle dynamics control system which aims to improve vehicle handling and stability by coordinating active front steering (AFS) and dynamic stability control (DSC) subsystems is developed in this paper. The DSC subsystem includes driveline-based, brake-based, and driveline plus brake-based DSC subsystems. The influence of varying forward speed and lateral acceleration on the lateral vehicle dynamics is investigated first. The AFS controller, which is used to improve vehicle steerability in the low to mid-range lateral acceleration, and the DSC controller, which manages to maintain vehicle stability during extreme driving situations, are then designed by using the sliding mode control (SMC) technique and phase plane method respectively. Based on the two independently developed controllers, a rule-based integration scheme is proposed to optimize the overall vehicle performance by minimizing interactions between the two subsystems and extending functionalities of individual subsystems. Computer simulation results confirm the effectiveness of the proposed control system and the overall improvements in vehicle handling and stability.

In this paper, the effect of the dynamic interaction between tractor and semitrailer on the ride behaviour of heavy good vehicles is investigated. A multi-body model is constructed for a 4-axle tractor-semitrailer vehicle with flexible frames and excited by random road irregularities. The modal parameters of the connected frames are calculated using the FEM (Finite Element Method), as an integrated free vibrating structure, and incorporated with the equations of motion of the whole vehicle which are generated using the Lagrange energy approach. Frequency response analysis is carried out for random road excitations to evaluate the vehicle ride dynamics. In order to give a broad overview of the vehicle ride quality, different loading conditions are considered in the computer simulation. The results showed that the acceleration levels of vehicle components are significantly increased when the effect of an empty semitrailer is considered within the vehicle model. This effect is suppressed by reducing the stiffness and damping coefficients of the suspension systems of the tractor and semitrailer. Practically, a change in the suspension stiffness can be achieved using conventional multi-stage leaf springs or adjustable air suspension systems in such a way so as to keep the static suspension deflections similar to those of the laden condition. At the same time, switchable dampers can be used to alter the damping coefficients. The results (root mean square values and power spectral density functions) showed that excellent improvements in ride behaviour of unladen vehicle can be achieved by using specific suspension parameters.

In this thesis an integrated powertrain control for gearshifts on twin clutch transmissions is developed. First, a detailed model of an automotive powertrain featuring a twin clutch transmission is developed in Matlab/Simulink®. This model includes detailed friction models for the twin clutch that enable an investigation into the effects of different friction materials on the performance of the gearshift controller. The transmission model also includes detailed models of the synchronisers and thus allows a simulation of synchroniser-to-synchroniser shifts. A simplified phenomenological model, derived from a more complex non-linear model, is employed to model the hydraulic actuation of clutches and synchroniser. The thesis finds that the dependency of the friction coefficient on the sliding speed has an important influence on the gearshift quality and the performance of gearshift controller, while the absolute level of the friction coefficient is less important. Based on this powertrain model the key problems of gearshifts on twin clutch transmissions were identified and a control that overcomes these problems was developed. The first stage was to devise a gearshift control algorithm that handles single clutch-to-clutch shifts without a oneway (freewheeler-, overrunning-) clutch. This basic gearshift control algorithm featured a control of clutch slip for the engine torque transfer and a control of engine speed through engine torque manipulation (plus clutch pressure manipulation for downshifts). In a second stage, an optional transmission output torque control was developed that could be integrated in the basic control. The thesis shows that these control strategies are superior, in terms of shift quality, to conventional gearshift controls as used on planetary-type transmissions and are also robust against variations in the powertrain parameters (including friction coefficient) and sensor noise. The control strategies developed for single clutch-to-clutch shifts were extended to handle double and other multiple gearshifts that take place in the same transmission half. The thesis also investigates the other main part of gearshifts on twin clutch transmissions, the gear pre-selection. The thesis shows that, on power-on gearshifts, the torque reactions at the transmission output due to the gear pre-selection with conventional hydraulically actuated synchronisers can be effectively compensated for by a simple manipulation of engine torque.