Actuator Parameter Uncertainties Research Articles

Synthetic Jet Actuator-Based Aircraft Tracking Using a Continuous Robust Nonlinear Control Strategy

A robust nonlinear control law that achieves trajectory tracking control for unmanned aerial vehicles (UAVs) equipped with synthetic jet actuators (SJAs) is presented in this paper. A key challenge in the control design is that the dynamic characteristics of SJAs are nonlinear and contain parametric uncertainty. The challenge resulting from the uncertain SJA actuator parameters is mitigated via innovative algebraic manipulation in the tracking error system derivation along with a robust nonlinear control law employing constant SJA parameter estimates. A key contribution of the paper is a rigorous analysis of the range of SJA actuator parameter uncertainty within which asymptotic UAV trajectory tracking can be achieved. A rigorous stability analysis is carried out to prove semiglobal asymptotic trajectory tracking. Detailed simulation results are included to illustrate the effectiveness of the proposed control law in the presence of wind gusts and varying levels of SJA actuator parameter uncertainty.

Adaptive Robust Vibration Control of Full-Car Active Suspensions With Electrohydraulic Actuators

This paper investigates the problem of vibration suppression in vehicular active suspension systems, whose aim is to stabilize the attitude of the vehicle and improve the riding comfort. A full-car model is adopted, and electrohydraulic actuators with highly nonlinear characteristics are considered to form the basis of accurate control. In this paper, the H∞ performance is introduced to realize the disturbance suppression by selecting the actuator forces as virtual inputs, and an adaptive robust control technology is further used to design controllers which help real force inputs track virtual ones. The resulting controllers are robust against both actuator parametric uncertainties and uncertain actuator nonlinearities. The stability analysis for the closed-loop system is given within the Lyapunov framework. Finally, a numerical example is given to illustrate the effectiveness of the proposed control law, where different road conditions are considered in order to reveal the closed-loop system performance in detail.

Robust control of vehicle suspension with electrohydraulic actuator

This paper presents a study on robust control of vehicle electrohydraulic suspension with parameter uncertainties. The change of sprung mass and the variation of spring stiffness, damping coefficient, and actuator parameters are considered as parameter uncertainties and described by different methods. A robust controller is then designed for the uncertain vehicle suspension model to optimise its performances on ride comfort, suspension deflection, and road holding ability considering suspension and actuator parameter uncertainties and actuator saturation. The sufficient conditions for designing such a controller are derived as linear matrix inequalities (LMIs) which can be solved using standard software. Numerical simulations are used to validate the effectiveness of the proposed approach. It is confirmed by the simulation results that the applied control strategy performs better than the passive suspension regardless of the parameter uncertainties.