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The aim of this study is to create an integrated controller between the active suspension system and an anti-lock braking system using fuzzy logic control theories to improve braking performance. Also, the ride performance during braking is investigated. Braking and ride performances for active are evaluated using half vehicle model. The suspension system, tyre-road interface and anti-lock braking system model are included in the model. The anti-lock braking system and active suspension is compared with the anti-lock braking system combining passive suspension. The simulation result obtained show that the active and ABS system with integrated controller reduces the braking time and distance in the range from 3% to 5% compared with the same system without integrated controller. Furthermore, anti-lock braking system and active suspension improves ride comfort and safety in vehicles compared with passive system.

Suspensions are installed underneath the cab to reduce the transmitted vibration from the chassis and to improve ride comfort for truck and drivers. This paper addresses the cab suspension control and truck ride performance. A nine-degree of freedom model for the evaluation of ride performance for a truck and trailer moving on an irregular road surface is developed. The cab suspension for passive system is represented by a parallel arrangement of a spring and damper. A hybrid control strategy is proposed to improve ride performance. The effect of vehicle speed and road roughness on the ride performance is evaluated. The road roughness, speed, cab suspension and the proposed control strategy have significant effects on the truck ride performance.

The issue of ride comfort for vehicle operations has generated considerable interest in vehicle systems. The road condition has an important influence on ride quality; however, the road condition cannot be sufficiently controlled. The proper design of vehicle components is the only way to improve ride quality. This work is an investigation into the ride behavior of passive and active suspension systems using half vehicle model. The mathematical modeling approach is developed to enhance the ride characteristic and assist in the design of good ride properties of vehicle. The influence of spring stiffness, damping coefficient and tyre stiffness on ride comfort is studied. Also, the effect of anti-roll bar stiffness on the roll acceleration is discussed. Finally, the ride performance of active and passive suspension systems are evaluated. The results obtained give a solution to avoid load carrying capacity problem during vehicle motions.

One of the various active suspensions, which have been shown to have considerable practical potential, is a switchable damper suspension system. However, previous studies of this system have concentrated on the improvements obtainable for certain fixed road roughness, fixed forward speed and fixed vehicle parameters using a quarter vehicle model. This paper is concerned with an analytical study of a four-degrees of freedom vehicle incorporating a passive and a switchable damper suspension system. A half vehicle model of the switchable damper suspension system with adaptive control strategy is developed. The controller provides a set of gains over different operating conditions. The vibrations of the half vehicle are induced by random road inputs at the front and rear wheels. An investigation of the influence of switchable damper suspension system on vehicle ride quality control is performed on this model and compared with the conventional passive suspension.

Road roughness is a very important consideration in evaluating the condition of a given roadway, as it affects the ride comfort for the passenger and vehicle operating cost. This paper deals with an investigation of the influence of road roughness on the vehicle ride comfort and vehicular rolling resistance. The rolling resistance power losses is also investigated. A mathematical model of a quarter vehicle is developed to evaluate vehicle ride comfort in terms of suspension performance criteria. The performance of each suspension system can be assessed quantitatively in terms of discomfort (Acc), suspension working space (SWS) and dynamic tyre load (DTL). The effect of road roughness on the vehicular rolling resistance coefficient is also discussed. The ride performance, power consumed in rolling resistance and power dissipation in suspension for passive and switchable damper suspension systems are finally evaluated.

One of the various active suspensions, which have been shown to have considerable practical potential is the slow active scheme based on hydro-pneumatic components. However, previous studies of this system were restricted to using either a quarter or half vehicle model (two or four degrees of freedom). This paper is concerned with an analytical study of a multi-degree of freedom vehicle incorporating a passive and a slow active scheme based on hydro-pneumatic components. A full vehicle model of the hydro-pneumatic active suspension system is developed. This model includes the rigid body translation and rotational modes. This constitutes an extension of the state of the art, since previous investigations of hydro-pneumatic active suspension systems were restricted to bounce vibration control. The vibrations of the four-wheeled vehicle are induced by random road inputs at the left and right tracks.

Although active suspensions are well known to provide improved performance over passive systems, their two main drawbacks are the required energy input levels and the high component costs. A hybrid control system is proposed which addresses these two drawbacks. Its performance is examined theoretically in a simple application in which it is used as a seat suspension coupled to a quarter car model representing the general properties of vehicle ride dynamics. The hardware for the hybrid control system is based on DC motors and a condenser, and the strategy is to store the dissipative energy obtained in the dissipative cycles for later use in the active cycles when input power is required Practical issues are transfering the rotary motor motion to linear motion and electric components of the energy regenrative damper. These are chosen to give a practical damping coefficient value and to control the seat actuator.

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.

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.