Summary This paper addresses the control problem of adaptive backstepping control for a class of nonlinear active suspension systems considering the model uncertainties and actuator input delays and presents a novel adaptive backstepping‐based controller design method. Based on the established nonlinear active suspension model, a projector operator–based adaptive control law is first developed to estimate the uncertain sprung‐mass online, and then the desirable controller design and stability analysis are conducted by combining backstepping technique and Lyapunov stability theory, which can not only deal with the actuator input delay but also achieve better dynamics performances and safety constraints requirements of the closed‐loop control system. Furthermore, the relationship between the input delay and the state variables of this vehicle suspension system is derived to present a simple and effective method of calculating the critical input delay. Finally, a numerical simulation investigation is provided to illustrate the effectiveness of the proposed controller.
This paper presents a sliding mode observer-based fault tolerant controller for a class of active suspension with the parametric uncertainties and sensor faults. First, T-S fuzzy approach is employed to represent the inertial parameters uncertainties and sensor faults, and then an augmented vehicle dynamics model is established. To estimate both system state variables and sensor fault signal simultaneously, a sliding-mode observer is investigated, and the fault tolerant control law is further derived in terms of the estimation of state and state error within Lyapunov theory framework, moreover, the sufficient conditions for the existence of this controller is deduced and solved via a set of linear matrix inequalities. Finally, a complete comparative simulation case is provided to demonstrate the effectiveness and feasibility of the designed control method. INDEX TERMS active suspension system, sliding mode observer, fault tolerant control, T-S fuzzy approach. Nomenclature mc Vehicle body mass [kg] ϕ Pitch angle of vehicle body [rad] Iy Moment of inertia in vehicle body [kg• m² ] cf Damping coefficient of front suspension [N•s•m-1 ] muf Mass of the front suspension wheel [kg] cr Damping coefficient of rear suspension [N•s•m-1 ] mur Mass of the rear suspension wheel [kg] ktf Stiffness of the front tire [N•m-1 ] a Distance from COG to the front axle [m] ktr Stiffness of the rear tire [N•m-1 ] b Distance from COG to the rear axle [m] uf Front actuator force [F] zuf Vertical displacement of the front wheel [m] ur Rear actuator force [F] zur Vertical displacement of the rear wheel [m] ∆yf Front suspension dynamic travel [m] zrf Road excitations at the front wheel [m] ∆yr Rear suspension dynamic travel [m] zrr Road excitations at the rear wheel [m] kf Stiffness coefficient of the front suspension [N•m-1 ] zc Vertical displacement of vehicle body [m] kr Stiffness coefficient of the rear suspension [N•m-1 ]
This study proposes an improved adaptive sliding mode–based fault-tolerant control design for the improvement of dynamics performances of half-vehicle active suspensions with parametric uncertainties and actuator faults in the context of external road disturbances. To cope with the model establishment of the vehicle active suspensions, the T–S fuzzy approach and system augmentation technology are used to construct the T–S representation of the faulty augmented system, and a new adaptive law is, therefore, designed to achieve the accurate online estimation of the actuator gain and drift faults, which facilitates the desirable fault-tolerant controller design. Moreover, the proposed adaptive sliding mode–based fault-tolerant controller is synthesized, and the system stability analysis is further conducted in premise of the Lyapunov stability theory. Finally, a numerical simulation is provided to illustrate the effectiveness and robustness of the proposed controller.
This paper proposes a hybrid fault-tolerant control strategy for nonlinear active suspension subjected to actuator faults and road disturbances. First, an augmented closed-loop system model is established for the nonlinear active suspension system with the actuator faults and road disturbances. Then, based on this model, a hybrid fault-tolerant controller that consists of a nominal state-feedback controller and a robust H∞ observer is proposed to stabilize the control plant under fault-free condition and further compensate for the suspension performance loss under the actuator fault condition. Finally, a half-vehicle active suspension example is exploited to demonstrate the effectiveness of the proposed hybrid fault-tolerant controller under various running conditions.
This paper proposes an observer-based active fault-tolerant controller for a half-vehicle active suspension system subjected to the actuator fault as the nonzero offset fault. By constructing the augmented fault suspension system model, an H∞ weighted output feedback controller was developed to improve the vehicle dynamics performances under a fault-free condition. Moreover, a robust observer was designed to make an accurate estimation of the fault information with the auxiliary diagnosis system and further to develop an H∞ fault compensation controller, such that the closed-loop control system can eliminate the negative effects of the actuator faults on vehicle suspension performances. Finally, a numerical simulation investigation was provided to verify the effectiveness of the proposed controller under the random and bump road disturbances.
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