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In this paper, the performance tradeoffs in the design of electronically controlled suspension systems are theoretically studied. Using quarter car model, a new treatment procedure for the control laws is introduced using fully active suspension system with two control strategies. The first strategy is considered for vehicle vibration isolation due to random road excitation only. The second strategy is considered to perform a zero steady-state suspension deflection due to body vehicle attitude variation during maneuvering, braking and aerodynamics as well as vibration isolation due to random road excitation. The two strategies are achieved by using two different optimization techniques combined with PID (Proportional-Integral-Derivative) compensator. The first technique is based on Linear Quadratic Regulation (LQR) technique and the second technique is based on Genetic Algorithm (GA).

Road humps are considered as one of the best design propositions to control running vehicle speeds, in many roads they are randomly installed depending on the resident's requirements. In this paper, Genetic Algorithm (GA) optimization technique is used to design an active suspension based on force cancellation concept when the vehicles crossing road humps. A longitudinal half vehicle model is used to represent passenger's car and truck models. These models are used to evaluate the performance of active suspension over the road speed humps. The force cancellation concept is employed to isolate the force between the sprung and unsprung mass. Virtual damper and skyhook damper concepts are also used for reducing the sprung mass acceleration and tire dynamic loads. GA is adopted to obtain the better coefficients of a virtual damper and a skyhook damper for its effective searching ability.

Vibration ride comfort of combat vehicles is essential subject because these vehicles operate at different environments. Improving the comfortability enables the solders to drive for a long time at critical situations with full activity. This paper looks at the ride performance of multi-axles combat vehicles driven at varies speeds over terrain profile. Three configurations of these vehicles, two axles, three axles and four-axles-vehicles, have been studied and compared. The results showed that at a wide range of speeds there is a significant improvement to be gained by using four axles over the three axles and two axles when emphasis is placed on the vehicle body vertical acceleration and dynamic tyre loads.

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.

One of the main causes of the torsional and bending fluctuations of the driveline is the angularity of the driveshaft and its universal joints. Most of the previous studies of the driveline vibrations have considered constant and equal angularities of these joints. However, the exact equality of the angularity is very difficult to maintain for ground vehicles under different ride vibration modes. This paper is concerned with the coupling between the driveline fluctuations and the ride vibrations of the rear drive vehicles. The coupled motions, which are; drive axle suspension deformation and vehicle body pitch angle and their derivatives, have been used to study the driveshaft and output shaft bending and torsional fluctuations. The results have showed that the fluctuations of the driveshaft due to the base angularity of the joints are superimposed by another fluctuation due to the bounce and pitch of the vehicle body.

In this paper, a continuously controlled semi-active suspension system is designed for trucks main suspension. Using a linearized seven degrees of freedom mathematical model equipped with hydraulic and hydro-pneumatic components, the optimal damping forces for truck front and rear suspensions are designed based on optimal control theory using Linear Quadratic Regulation (LQR) to improve the ride comfort and dynamic tyre loads. The practical limitation for the damping forces and the time lag for system controllable elements are taken into account. The results are generated considering the suspension components non-linearity and the model is excited by statistically random road. The frequency domain results as power spectral density and the root mean square values are compared with those obtained from conventional passive suspension system.

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.

In this paper, the performance of hydro-pneumatic limited bandwidth active suspension system is studied theoretically using a half car model. The bounce and pitch motions for the sprung mass and two vertical degrees of freedom for the unsprung mass's are considered (to permit for good suspension design). The linear optimal control theory is used to derive the full state feedback and feedforward control laws taking into account the correlation between the front and rear wheel excitation. The results are generated when the vehicle running on a statistically random road using a 6 Hz bandwidth analogue controller. A comparison between the conventional passive, limited bandwidth active suspensions with and without wheelbase correlation are presented and discussed. The results showed that there is a worthwhile improvement for the proposed active system over the passive, while incorporating wheelbase correlation added more benefits for the rear axle dynamics and pitch motion.