Applied Mechatronics: Designing a Sliding Mode Controller for Active Suspension System

Abstract

The suspension system is referred to as the set of springs, shock absorbers, and linkages that connect the car to the wheel system. The main purpose of the suspension system is to provide comfort for the passengers, which is created by reducing the effects of road bumpiness. It is worth noting that reducing the effects of such vibrations also diminishes the noise and undesirable sound as well as the effects of fatigue on mechanical parts of the vehicle. Due to the importance of the abovementioned issues, the objective of this article is to reduce such vibrations on the car by implementing an active control method on the suspension system. For this purpose, a conventional first-order sliding mode controller has been designed for stochastic control of the quarter-car model. It is noteworthy that this controller has a significant ability to overcome the stochastic effects, uncertainty, and deal with nonlinear factors. To design a controller, the governing dynamical equation of the quarter-car system has been presented by considering the nonlinear terms in the springs and shock absorber, as well as taking into account the uncertainty factors in the system and the actuator. The design process of the sliding mode controller has been presented and its stability has been investigated in terms of the Lyapunov stability. In the current research, road surface variations are considered as Gaussian white noise. The dynamical system behavior for controlled and uncontrolled situations has been simulated and the extracted results have been presented. Besides, the effects of existing uncertainty in the suspension system and actuator have been evaluated and controller robustness has been checked. Also, the obtained quantitative and qualitative compressions have been presented. Moreover, the effect of controller parameters on the basin of attraction set and its extensiveness has been assessed. The achieved results have indicated the good performance and significant robustness of the designed controller to stabilize the suspension system and mitigate the effects of road bumpiness in the presence of uncertainty and noise factors.

A logarithmic sliding mode controller for stochastic active suspension systems

“…Although a car suspension system has a stochastic nature due to road bumps, except in some cases like Moghadam and Kebriaei (2019), Azizi and Mobki (2021), and Wang (2021), our survey interestingly showed that robust controller, rather than a robust stochastic controller, has been designed to activate a car suspension system. In other words, in the process of controller design, the disturbance due to surface roughness has been considered as an uncertainty, rather than a stochastic process, with known or unknown bound which might cause a conservative controller.…”

The Dynamic Model and Control Algorithm for the Active Suspension System

“…A drawback still exists when using the SMC algorithm, which is the phenomenon of "chattering." Tis phenomenon will cause the signal to vibrate continuously [53]. Terefore, it can afect the quality of the system.…”

A novel approach with a fuzzy sliding mode proportional integral control algorithm tuned by fuzzy method (FSMPIF)

“…According to Azizi and Mobki, the objects will slide over the surface. The object then advances toward the location of equilibrium 27 . According to Nguyen, a sliding surface is a complicated function dependent on the controller's error signal 28 .…”