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Although active suspension improved vehicle ride comfort, their two main drawbacks are the required high component costs and energy input levels for active suspension. The semi-active and twin accumulator suspensions are proposed which addresses these two drawbacks. Ride performances for passive, twin accumulator and semi-active are examined theoretically using half vehicle model. The power consumed in rolling resistance and power dissipation in suspension for passive, twin accumulator and semi-active suspension systems are evaluated. The effect of road disturbance on the vehicle ride performance for twin accumulator and semi-active suspension systems is studied. The rolling resistance power losses are also investigated. The results showed that the optimum twin accumulator suspension system over all road roughness/speed conditions would have adaptable spring stiffness and damping coefficients which could be changed depending on the road conditions.

An active suspension system has better performance than a passive suspension. However, it requires a significant amount of energy and is constructed from high cost components. To solve the problem of the power required, a switchable damper suspension system has been studied. In this paper, control strategies for the switchable damper suspension system and passive are compared in terms of their relative ride performance capabilities. Practical limitations involving switching time delay and threshold delay values are modeled and their effect on the ride performance are evaluated. The four setting switchable damper is compared with the two and three setting switchable dampers. The control strategies are used to maintain suspension working space level within design limit and to minimize body acceleration level. The results showed that the four setting switchable damper gives better ride improvements compared with the two and three setting switchable dampers.

In this paper, passive and various types of intelligent vehicle suspension systems are compared in terms of their relative ride performance capabilities and power requirements. These systems are active, two and three setting switchable dampers suspension systems. The control gains of the intelligent systems are obtained using optimal control theory and gain scheduling strategy (GS) is used for the system behaviour. In the first strategy (GS) used, gains are selected based on suspension working space. While, the other strategy (GS), gains are selected based on body acceleration. These strategies are used to maintain suspension working space and dynamic tyre deflection levels within design limits and to minimise body acceleration level. The mean power consumed in rolling resistance and the mean power dissipation within the suspensions is evaluated.

This paper presents experimental and theoretical investigations for ride comfort performance of compressed natural gas fuelled car. A compressed natural gas and gasoline fuel are used to run the engine car and its effect on the vehicle ride comfort is evaluated. The ride comfort performance in terms of experimental Root Mean Square (RMS) values of the vertical acceleration at near driver's feet on the floor, on the front and back seat for the same passenger car fuelled by gasoline and natural gas is evaluated. Furthermore, seven degrees of freedom vehicle mathematical model is developed, and validated through laboratory tests. The validation process is performed by comparing the predicted RMS values of the vertical accelerations with the measured RMS values. Furthermore, the optimum values of vehicle suspension parameters are obtained through the validated vehicle model.

The integrated control between the vehicle chassis subsystems (suspension, brake, and steering) became one of the most important aspects for current developments to improve the dynamics of the vehicles. Therefore, the aim of this study is to investigate the influence of the preview control of the active suspension on the vehicle ride and braking performance. The vehicle performance was examined theoretically using a longitudinal half vehicle model with four degrees of freedom considering the rotational motion of the tires. The active suspension system model, tire-road interface model and braking system model are included in the vehicle model. In order to study the influence of the preview control on the vehicle ride and braking performance, an active suspension system control algorithm employing the lock-ahead preview information and the wheel-base time delay based on the optimal control theory is derived.

The road condition has an important influence on ride quality; however, the road condition cannot be sufficiently controlled. The proper design of truck components is the only way to improve ride quality. This work is an investigation into the ride behaviour of passive and active suspension systems using full truck model. A mathematical model for the evaluation of ride comfort for a truck 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. The gain scheduling (GS) strategy is used to improve truck ride comfort. The influence of suspension elements, tyre stiffness, truck speed and road input on ride comfort is evaluated. The results showed that the active suspension system with gain scheduling strategy gives better ride improvements compared with active system .in terms of vertical cab acceleration.

The paper deals with a theoretical study to present a new sort of the buses suspension systems employs a hydraulic connection between the front and rear dampers together with active suspension actuator at the front axle. The theoretical investigation based on a half vehicle model of the bus suspension system includes the engine mounting system. The hydraulic connection between the front and rear dampers is created according to the capillary tubes theory. Furthermore, the active suspension system control algorithm based on the optimal control theory is derived. The Genetic Algorithm optimization routine is applied to generate the active suspension control algorithm parameters. A comparison between the connected dampers suspension system, active suspension system, active-connected dampers suspension system, and the passive suspension system in terms of ride comfort and road holding at constant suspension working space is performed.

The interest of the highway engineer and researchers are focused on road roughness and vehicle vibrations in the frequency range of interest, which corresponds to a wave number range appropriate for the prevailing traffic speed. Road profile is an important step for studying vehicle ride comfort. The aim of this work is to investigate the effect of road roughness on the ride comfort and rolling resistance for passenger cars. Mathematical models of a half vehicle for passive and semi-active suspension systems are developed to evaluate vehicle ride comfort in terms of suspension performance criteria. The ride performance, power consumed in rolling resistance and power dissipation in suspension for passive and semi-active suspension systems are finally evaluated

Nowadays, the anti-lock braking system, briefly ABS, is an important component in modern cars. Therefore, in this paper the one of the intelligent control theories “Fuzzy Logic Control” is suggested to create two different ABS controllers. The braking performance was examined theoretically using half vehicle model. The suspension system model, tire-road interface model and anti-lock braking system model are included in the model. The influence of vehicle initial speed and tire-road friction coefficient is investigated. The simulation results of the proposed controllers are compared with the conventional ABS controller and the Conventional Brake system. The results showed that, using Fuzzy Logic Control in ABS improved the braking performance than the conventional ABS. Furthermore, the improvement in the braking performance using fuzzy logic control is obtained without any additional sensors, which leads the controller to be more realizable for the industry application.

In this study, LQR control design is presented for the control of a vehicle active suspension system. Seven degrees of freedom, full vehicle model is used. LQR control system is prepared as well as adaptive LQR control system (gain scheduling strategy) to study the effect of each control system using the active suspension on ride performance. The acceleration and dynamic tyre load are evaluated. For the time domain analysis, different road conditions are considered in order to reveal the performance of the two controllers. The simulation results showed that adaptive LQR control system gives a better ride performance compared with LQR control system. Also, the comparison between these control strategies are discussed.

This paper deals with an investigation of the road roughness on the vehicle ride comfort using semi-active suspension system. A mathematical model of quarter vehicle for semi active suspension system is developed to evaluate vehicle ride comfort. The rolling resistance and power losses are also investigated. The power consumed in rolling resistance and power dissipation in suspension for passive and semi-active suspensions are evaluated. The obtained results showed that ride comfort increases as the road roughness is decreased. Comparisons between passive and semi-active suspensions systems in terms of ride performance and power dissipation are also discussed.

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.