Explore the vast range of titles available.

This study deals with the problem of finite-time reliable ℒ2 − ℒ∞/ℋ∞ control for non-linear systems with actuator faults through Takagi–Sugeno fuzzy model approach. The actuator failure model under consideration is assumed to be governed by a homogenous Markov chain. The focus is on the design of a fuzzy Markov switching fault-tolerant controller such that the resulting closed-loop system is stochastically finite-time bounded with a mixed ℒ2 − ℒ∞/ℋ∞ performance level over a finite-time interval. Some sufficient conditions for the solvability of the above problem are given in terms of linear matrix inequalities by introducing a new mixed ℒ2 − ℒ∞/ℋ∞ performance function. Finally, a quarter-vehicle suspension model is employed to demonstrate the effectiveness of our proposed approach.

This study optimizes vehicle suspension dynamics by introducing a controllable degree of nonlinearity, characterized by a parameter ε, into the spring element of Inerter-Spring-Damper (ISD) systems. Quarter-vehicle models for parallel and series ISD configurations are established, and a multi-objective genetic algorithm optimizes the parameters under random road excitation to minimize body acceleration (BA), suspension working space (SWS), and dynamic tire load (DTL). Results demonstrate that optimizing ε brings advantages: compared to a conventional passive suspension, the optimized parallel ISD suspension reduces BA, SWS, and DTL by 7.98%, 8.57%, and 1.69%, respectively, with the BA reduction notably improving from 5.94% (achieved by the linear ISD with ε = 0) to 7.98%. Similarly, the optimized series ISD achieves reductions of 2.53%, 7.62%, and 6.42% in BA, SWS, and DTL, showing a more balanced enhancement over its linear counterpart. The analysis reveals how ε distinctly influences the performance trade-offs, validating that strategically tuning the spring nonlinearity degree, in synergy with the inerter and damper, provides an effective method for superior suspension performance customization.

The dynamic characteristics of a vehicle are significantly influenced by the suspension mechanism. In this paper, the nonlinear kinestatic relations of a planar suspension mechanism are taken into account in the dynamic analysis of a vehicle. A planar suspension mechanism can be considered a 1-DOF parallel mechanism. The Jacobian is used for the kinestatic analysis of the suspension. The motions of the suspension can be represented by instantaneous screw. Based on these kinematic and static relations, the dynamic performances of a quarter-vehicle model with a planar suspension mechanism are described in terms of Lagrangian equations. Finally, as illustrated in the examples, two different kinds of road disturbances are inputted into the wheel. The dynamic responses of a quarter-vehicle model are simulated and compared with the simulation software Adams/View for the validity of the theoretical method.

The invariant points of the quarter vehicle model shape many properties concerned in vehicle suspension design. Although they have been studied for years, the invariant points are still confusing for their different traits. Hence, the existing invariant points are sorted and analysed. Meanwhile, the invariant points of the semi-active suspension were introduced. In this article, a further study on the invariant points of the semi-active suspension is conducted, which provides insight for suspension optimization. In detail, an equivalent linear approximation model, derived from the transformation of the semi-active suspension model, is utilized to analyse the invariant points of the semi-active suspension. With the equivalent linear approximation model, the invariant points of the sky-hook semi-active suspension are proved to be highly dependent on the adjustable damping range. In fact, the frequencies and magnitudes of the invariant points, as the limit of the semi-active suspension, are determined by the adjustable damping range. Consequently, the influence rule of the adjustable damping range on semi-active suspension performance is revealed, which provides insight for the optimization of the damping for different demands. Experimental study shows that the invariant points are real, not just exist in the theoretical analysis.

Inerter is a recent element in suspension systems with the property that the generated force is proportional to the relative acceleration between its two terminals, which is similar to the way a spring reacts to relative displacement and a damper to relative velocity. This paper presents the analysis of a non-linear inerter working in parallel to passive spring and damper of a vehicle suspension to evaluate its effect on vehicles ride. The non-linear inerter was theoretically capable of switching between on and off states depending on whether or not the suspension deflection was beyond a specified free play. In the study, this behavior was represented mathematically as control law which depended on the relative displacement between the sprung and unsprung masses. A mathematical quarter vehicle model incorporating the non-linear inerter was simulated in MATLAB/Simulink to determine the vehicle responses due to road input in the form of step profile for different combinations of free play and inerters on-state proportionality constant called the inertance. Results showed improvements in vehicle ride comfort, as demonstrated by the lower root-mean-squared sprung mass accelerations compared to the ordinary passive suspension with only spring and damper. Additionally, implementation of non-linear inerter gave lower percentage overshoot to step input, indicating better transient response than ordinary passive suspension.

Abstract A novel adaptive fuzzy logic controller (AFC) based on an interval type-2 fuzzy controller is proposed for vehicle non-linear active suspension systems. The adaptive strategy elicited from the least-mean-squares optimal algorithm is adopted to self-tune lower bounds and upper bounds of interval type-2 fuzzy membership functions (IMF2s). The IMF2s are utilized in the AFC design to deal with not only non-linearity and uncertainty caused by irregular road inputs and immeasurable disturbance, but also the potential uncertainty of experts knowledge and experience. A case study based on a quarter-vehicle active suspension model has demonstrated that the proposed type-2 controller significantly outperforms conventional fuzzy controllers of an active suspension and a passive suspension.