Roughness on the road is the main cause of the oscillation when the vehicle travels. The suspension system plays a role in maintaining the stability of the vehicle in fluctuating states. To improve comfort and smoothness, the active suspension system is used to replace the conventional passive suspension system. The performance of the active suspension system depends on the pre-designed controller. Linear control algorithms cannot guarantee oscillation requirements in all cases. Therefore, the use of a nonlinear control method is necessary. In this paper, the SMC control algorithm is proposed to control the operation of the active suspension system. To optimize this algorithm, five state variables were considered. Besides, the output signal of the model has been taken into account by the fifth derivative, and the error signal is also considered the fourth derivative. This is a completely novel and unique method. The simulation is done in the Matlab-Simulink environment. According to this result, the displacement and acceleration of the sprung mass was significantly reduced when the vehicle used the active suspension system controlled by the SMC algorithm. These values only reach 14.4% and 14.1% compared to the case of the vehicle using the mechanical suspension system. The effect of the SMC algorithm is extremely positive. This will be the basis for developing more complex control algorithms in the future.
The rollover phenomenon is a particularly dangerous problem. This phenomenon occurs when the driver travels at high speed and suddenly steers. Under the influence of centrifugal force, the body vehicle will be tilted and cause the wheels to lift off the road. To solve this problem, the method of using an active stabilizer bar has been proposed. The active stabilizer bar is controlled automatically by a previously designed controller. The performance of the active stabilizer bar depends on the selected control method. Previous research often only used a half-car dynamics model combined with a linear single-track dynamics model to simulate the vehicle’s oscillation. In addition, most of the research focuses only on the use of linear control methods for the active stabilizer bar. Therefore, the performance of the stabilizer bar is not guaranteed. This paper focuses on establishing the model of spatial dynamics combined with the nonlinear double-track dynamics model that fully describes the vehicle’s oscillation most accurately. Besides, the fuzzy control method is proposed to control the operation of the hydraulic stabilizer bar. This is a completely novel model, and it is suitable for the actual traveling conditions of the vehicle. Also, simulations are done based on different scenarios. The results of the paper showed that the values of the roll angle, the difference in the vertical force at the wheels, and the displacement of the unsprung mass were significantly reduced when the vehicle used the active stabilizer bar, which is controlled by an intelligent control method. Therefore, the stability and safety of the vehicle have been guaranteed. This result will be the basis for performing other more complex research in the future.
Vehicles are rollover when steering at high speed, this phenomenon is limited by increasing the anti-roll moment of the suspension system. This research focuses on analyzing and establishing the dynamic model of vehicle when steering and describes the dependence of the vehicle body's roll angle on other factors. Research has shown that when equipped a stabilizer bar it will significantly reduce the roll angle of the vehicle body. Besides, this research shows the outstanding advantages of active stabilizer bar with other stabilizer bars. Therefore, most of the vehicle should be equipped active stabilizer bar to ensure stability and safety when moving.
The phenomenon of the lateral instability of the vehicle when the steering is one of the extremely serious and dangerous problems. To improve safety and stability, vehicles often are equipped with stabilizer bars at the front and rear axles. However, the passive stabilizer bar cannot guarantee safe and stable performance in dangerous cases. Therefore, the active stabilizer bar is used to replace the passive stabilizer bar. The active stabilizer can automatically generate an anti-roll moment depending on the condition of the vehicle at each time. In dangerous cases, the anti-roll moment of the active stabilizer bar is much greater than the passive stabilizer bar. This research focused on the problem of establishing a spatial dynamics model in combination with a nonlinear double-track dynamic model to describe the state of oscillation of the vehicle when steering. The PID control method is used to control the hydraulic stabilizer bar. The results of the research indicated that when the vehicle was equipped with the hydraulic stabilizer bar, the values of the roll angle, the displacement of the un-sprung mass, the vertical force at the wheel, ... were significantly reduced.
When the vehicle is traveling at high speed and suddenly steers, a rollover phenomenon may occur. The main cause of this phenomenon is the appearance of a centrifugal force, which is proportional to the mass and the square of the velocity. In order to limit this situation, the method of using the hydraulic stabilizer bar (active stabilizer bar) has been proposed. The performance of the hydraulic stabilizer bar is highly dependent on the control method, which has been designed to ensure the stabilizer bar's operation. Previous research often only used simple dynamics models and conventional linear control methods. Therefore, the performance of the stabilizer bar is not guaranteed. At the same time, the factors affecting the movement of a vehicle are not mentioned. This will cause inaccuracies. This research used a spatial dynamics model combined with a non-linear double-track dynamics model, which fully describes the effects of vehicle oscillations. Besides, the two-input Fuzzy control method is also proposed. This is a completely novel model, and it is not like the previous models that have been used to study the stabilizer bar. The results of this research show that if the vehicle uses the hydraulic stabilizer bar controlled by a two-input Fuzzy controller, the values of the roll angle and roll index have been reduced. As a result, stability and safety have been significantly improved. The achievements of this research will be the basis for the development of other intelligent control methods in the future.
When the vehicle moves on the road, many external factors affect the vehicle. These effects can cause oscillation and instability for the vehicle. The oscillation of the vehicle directly affects the safety and comfort of passengers. The suspension system is used to control and extinguish these oscillations. However, the conventional passive suspension system is unable to fully meet the vehicle’s requirements for stability and comfort. To improve these problems, these are much modern suspension system models that have been used in the vehicle to replace the passive suspension system. The modern suspension systems are used as the air suspension system, semiactive suspension system, and active suspension system. These systems which are controlled automatically by the controller were established based on the control methods. There are a lot of control methods which are used to control the operation of the active suspension system. These methods have their advantages and disadvantages. Almost, conventional control methods such as PID, LQR, or SMC are commonly used. However, they do not provide optimal efficiency in improving a vehicle’s oscillation. Therefore, it is necessary to establish a novel solution for the active suspension system control to improve the vehicle’s oscillation. In this paper, the method of using the double-integrated controller is proposed to solve the above problem. The double-integrated controller consists of two hydraulic actuators which are controlled completely separately. This is a completely novel and original method that can provide positive effects. This research focuses on establishing, simulating, and evaluating the novel control method (the double-integrated control) for the active suspension system. The results of the research have shown that when the vehicle is equipped with the active suspension system which is controlled by the double-integrated controller, the maximum values of displacement and acceleration of the sprung mass are significantly reduced. They reach only 6.25% and 9.10% (case 1) and 6.00% and 6.12% (case 2) compared to the conventional passive suspension system. Besides, its average values which are calculated by RMS are only about 3.91% and 4.67% (case 1) and 4.48% and 4.77% (case 2) compared to the above case. Therefore, the comfort and stability of the vehicle have been improved. This paper provides new concepts and knowledge about the double-integrated control method which will become the trend to be used in the next time for the systems of the vehicle. In the future, experimental procedures also need to be conducted to be able to more accurately evaluate the results of this research.
The suspension system has the role of regulating and extinguishing oscillations in the vehicle. To improve stability and comfort, the active suspension system is proposed to replace the passive suspension system. There are many algorithms used for active suspension system control, such as PID, LQR, Fuzzy, etc. Among them, the nonlinear control method which uses the SMC algorithm gives a stable performance. This research proposes the use of the SMC algorithm to control the operation of the active suspension system equipped with a quarter dynamics model. The process of linearization of the hydraulic actuator is presented in the paper. As a result of the simulation, the values of displacement and acceleration of the sprung mass were significantly reduced when the vehicle used the active suspension system controlled by the SMC algorithm. The SMC controller established in this paper provides stability in many situations. Therefore, the vehicle's smoothness and comfort have been significantly improved. In the future, intelligent algorithms can be combined with SMC algorithms to improve the efficiency of the controller.
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