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This research paper is focused on a novel transmission which provides a continuously variable gearbox based on two epicyclic gear sets plus two electric motor/generator units. This design scheme offers potential efficiency benefits over its competitors. It is referred to as a four branch transmission [1], because it has four independent power input and output, namely the engine, two motor/generators and the output shaft of the transmission. A key advantage of the design, when it is used on a hybrid electric vehicle, is that the electrical machines, namely the two motor/generators, and can be downsized compared with the more common, single epicyclic, 3 branch arrangement. A matrix method for the analysis of planetary transmissions [2] is used; the performance and control strategy of the new system is presented.

Motorcycle models in the literature are derived using the Lagrangian formulation approach and are generally complex in order to satisfy the requirement for accuracy of the response. The objective of this paper is to develop a simplified motorcycle model, which although reduced in complexity, captures fundamental dynamic behavior. The resulting model will have two main uses. The first use will be as an explanatory aid to introduce engineers to the dynamics of motorcycles. The second application for the motorcycle model developed in this paper is for incorporation in active bike control stability systems. This is a subtly different objective to models required for simulation only where accuracy of the response is of paramount importance. The same motorcycle model concepts will be used in the paper to develop both a transient non-linear and linearised steady state model.

In this work, the active front steering control is studied using linear three degrees of freedom handling model incorporating the driver’s operation model and vehicle suspension derivatives. The active steering control strategy is based on the optimal control theory. In this design, the active front steering angle is determined based on minimizing all model state variables and full state feedback gains. The results are generated when the model is excited by random wind excitation, which was modeled as quasi-static approach with statistical properties taken from previous work, and presented in frequency domain as power spectral density as well as root mean square values in tables. Significant improvements are achieved for the vehicle handling characteristics using active front steering control in comparison with active four wheel steering and conventional two wheel steering.

In this paper, a hybrid roll control system, including passive and active roll control units, is designed to improve the roll dynamics of tanker vehicles and to reduce the lateral shifts of the liquid cargo due to lateral accelerations. The passive control system consists of radial partitions installed inside the vehicle container. These partitions rotate in phase with the liquid cargo as one unit about the longitudinal axis of the container in response to the induced momentum forces due to the lateral acceleration excitation. Torsion dampers are fixed between the partitions and the container's front and rear walls to reduce the oscillating motion of the liquid cargo. While the passive partition dampers control the dynamics of the liquid cargo inside the container, the dampers of the vehicle suspension are switchable, generating anti-roll damping moments based on the lateral acceleration level and the container filling ratio.

In this paper, a direct technique to estimate the rollover threshold limits of partially filled tank trucks is applied for banked roadways. Overturning and restoring moments are calculated as functions of tank shape, fill level, gradient of both liquid cargo free surface and the lateral inclination of banked road surfaces. The static rollover threshold of tanker trucks traveling on laterally banked roadways is estimated by balancing the net value of the total overturning moment against the net value of the restoring moment. Different filling ratios are considered for circular, elliptical and modified tank vehicles. The rollover threshold limits are calculated considering a superelevation range of (0.0-0.1) for the lateral road banking as defined by Blue and Kulakowski (1991). It is shown that the vehicle rollover threshold limit increases with an increase of the angle of the lateral road banking.

The development of Integrated Chassis controllers has followed two main approaches. The pragmatic approach is to integrate existing chassis subsystems (e.g. DYC, ABS, TCS, ARC) with heuristic control laws. The more theoretical approach is to calculate control actions by solving a model of the vehicle dynamics. There is a dearth of literature that investigates the interface between these two strategies. This interface can give vehicle manufacturers ownership of the core vehicle motion control algorithm and allow them to select chassis controllers from a range of component suppliers. IVMC aims to give a global design methodology for Intelligent Vehicle Motion Control that interfaces a theoretical, generic controller with existing chassis subsystems. The interface takes the generic actuation forces and distributes them to the braking and steering chassis subsystems, DYC and active steering.

The paper describes the application of neural networks to understand the links between test drivers' subjective ratings of vehicle handling and measurable vehicle performance metrics as part of the Foresight Vehicle initiative. The shortcomings of classical linear methods used in previous studies (Crolla et al [1, 2 and 3]) are described along with the processes and developments made in a genetic algorithm based methodology used to find the predominantly non-linear links between subjective and objective handling. The techniques used were designed to make allowances for noise and other distractions inherent within drivers' subjective ratings. Further insights into the preferred ranges of the values of important vehicle handling metrics are presented.

There have been numerous studies of various forms of active suspensions over the past three decades. Most of published literature has reported theoretical studies and outlined the potential advantages in both vehicle ride and handling of such systems over their passive equivalents. One of the systems, which have been shown to have considerable practical potential is a limited bandwidth active scheme based on hydro-pneumatic components. However, in order to exploit the full potential of this arrangement, the control law should include two features; (a) the ability to exploit the wheel-base preview effect in which information at the front suspension of the vehicle is used to improve performance at the rear and (b) the ability to adapt on gain scheduling approach to a variety of different operating conditions. Both features are investigated in the paper using a four degree of freedom model and practical performance benefits are quantified.

In this paper, the vehicle body attitude in response to low frequency dynamic loads experienced during braking, accelerating, cornering, aerodynamics or payload variations can be controlled using an electronically controlled active suspension. Using a four degree of freedom half vehicle model, a composite controller which consists of Linear Quadratic Regulator vibration controller (LQR) plus Proportional-Integral-Derivative controller (PID) has been designed to isolate the body vibration from the road surface irregularities and maintain the body static height constant as well as control the body pitch motion. Vertical step inputs and different longitudinal step braking forces were applied to the body C.G. to simulate the payload variations and emergency braking effects.

One of the long-running themes throughout vehicle dynamics research has been a desire for a better understanding of the correlation between subjective and objective measures of vehicle handling. This theme can be traced back to the earliest contributions of that great automobile engineer Maurice Olley, who provided an analytical insight into qualitative expressions of vehicle behaviour. Results from a set of experiments using two vehicles, eight drivers and forty-six response metrics have been analysed to identify links between objective data and driver ratings of passenger car handling. The procedures involved matching objective metrics to ratings using ridge regression plots followed by least squares regression. Results showed that 70 to 90% of the variability of drivers' ratings could be accounted for by regression equations with greater than 95% significance.

This paper presents the algorithm for a Kalman filter active vehicle suspension design. Based on simulations, two main issues have been investigated, (a) the effects of disturbances from the changes in road input and the variations of vehicle parameters on state observer estimation, (b) the benefits of adaptation of an active suspension to the changes of road input and the variations of vehicle parameters. Simulations showed the significant vehicle performance improvement from adaptation to road input; however, an adaptive Kalman filter is not very necessary.

Persisting concerns regarding ride comfort, directional stability and more recently road damage have caused the manufacturers of commercial vehicles to consider controllable suspension systems. An electronically controllable adaptive suspension that comprises a variable spring rate system, switchable damping and load levelling is proposed as a cost-effective solution. This paper describes the aforementioned system and provides an outline of the design scheme for a prototype system; practical issues such as system configuration/detail, control system requirements, etc., are discussed. The system is evaluated analytically and both ride and handling modes are examined. In conclusion, performance capabilities are defined and cost-benefit issues addressed.

Torsional motion of a truck driveline system is coupled with other motions of its components. In this paper, a comprehensive model of the truck driveline and body for vibration analysis was developed. Coupling of the torsional vibration of the truck driveline system with the body fore-aft and vertical vibrations was investigated. A mathematical model, including the torsional vibration of the driveline system and the whole body vibrations of the truck, was constructed. The driveline system was modelled as a set of inertia discs linked together by massless springs and the tyre was represented as having massless circumferential band which is elastically connected to the carcass with the bands being subject to longitudinal forces at the road surface. System behaviour at steady and transient runs was developed.

Previous work to examine the performance of a variety of control strategies for a switchable damper suspension system is extended to include an adaptive suspension. The aim of this adaptation algorithm is to maintain optimal performance over the wide range of input conditions typically encountered by a vehicle. The adaptive control loop is based on a gain scheduling approach and two strategies are examined both theoretically and experimentally using a quarter vehicle test rig. For the first strategy, the gains are selected on the basis of root mean square (r.m.s.) wheel acceleration measurements whereas in the second approach the r.m.s. value of suspension working space is used. A composite input is used consisting of sections of a road input disturbance of differing levels of magnitude in order to test the control systems' abilities to identify and adapt efficiently as the severity of the road input changes.

The paper reviews the contributions of vehicle dynamics theory to practical vehicle design. Although much of the early work on the subject focused on passenger cars, its subsequent impact on commercial vehicle design has been equally dramatic. Recent advances in actively controlled components e.g. active suspension, multi wheel steering are reviewed and their potential impact on future truck design is assessed.

A comprehensive and systematic approach to vehicle dynamics analysis is described. All the commonly required calculations for vehicle dynamics studies have been embodied in a computer package called VDAS (Vehicle Dynamics Analysis Software). Examples taken from off-road vehicle applications are chosen to show how this particular class of dynamics problem can be tackled efficiently using this package. In addition to the standard range of calculations for vehicle ride and handling behaviour, e.g. natural frequencies, mode shapes, frequency responses, power spectral densities, steady state handling diagrams etc., the package incorporates more advanced features including derivation of control laws for active/semi-active suspension applications and sensitivity analysis to assist design studies. The VDAS package currently contains a range of ride and handling models of varying degrees of complexity, suitable for vehicle analysis.