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This paper presents an optimization-driven controller design for smooth and accurate position control of a single-rod electrohydrostatic actuator. The design approach uses logically guided iterative runs of the electrohydrostatic actuator to determine the optimal gain and poles' locations of a low-bandwidth controller. The optimization algorithm used in the paper is the globalized bounded Nelder-Mead algorithm with deterministic restarts for improved globalization and lower numerical cost. The design also incorporates a prefilter to ensure minimum jerk in the system's step input response in the beginning and while approaching steady-state. The step response of the filter is a seventh-deg polynomial curve that ensures the minimum change in acceleration in both states. Experimental results reveal that the addition of the proposed prefilter reduces jerk in the system by up to 90%. Results also indicate that the controller performs very well in all quadrants with external load uncertainty of up to 367 kg and thus proves the effectiveness of the design approach. [ABSTRACT FROM AUTHOR]

Summary: A mode decoupling control strategy is proposed for the active Kinetic Dynamic Suspension Systems (KDSS) with electrohydrostatic actuator (EHA) to improve the roll and warp mode performances. A matrix transfer method is employed to derive the modes of body and wheel station motions for full vehicle with active KDSS. The additional mode stiffness produced by the active KDSS is obtained and quantitatively described with the typical physical parameters. A new hierarchical feedback control strategy is proposed for the active KDSS to improve the roll and warp motion performances and simultaneously accounting for nonlinear dynamics of the actuators with hydraulic uncertainties. H∞ static output‐feedback control is employed to obtain the desirable mode forces, and a new projection‐based adaptive backstepping sliding mode tracking controller is designed for EHA to deal with address the nonlinearity and parameters uncertainty. This controller is used to realize the desirable pressure difference of EHA required from the target mode forces. Numerical simulations are presented to compare the roll and warp performances between the active KDSS, conventional spring‐damper suspension, and suspension with antiroll bar under typical excitation conditions. The evaluation indices are normalized and compared with radar chart. The obtained results illustrate that the proposed active KDSS with proposed controller does not produce additional warp motion for vehicle body, and has achieved more reasonable tire force distribution among wheel stations, the roll stability, road holding, and significantly improved ride comfort simultaneously. [ABSTRACT FROM AUTHOR]

Highlights • Robust estimation strategies are critical for the safe and reliable control of mechanical and electrical systems. • Presents a novel robust estimation method based on sliding mode concepts and the smooth variable structure filter (SVSF). • A mathematical proof of stability is provided based on Lyapunov theory. • The proposed nonlinear second‐order (NSO) filtering strategy is applied on an aerospace actuator. • The results are compared with the popular Kalman and extended Kalman filter, as well as the SVSF. Abstract In this paper, a new strategy referred to as the nonlinear second-order (NSO) filter is presented and used for estimation of linear and nonlinear systems in the presence of uncertainties. Similar to the popular Kalman filter estimation strategy, the proposed strategy is model-based and formulated as a predictor-corrector. The NSO filter is based on variable structure theory that utilizes a switching term and gain that ensures some level of estimation stability. It offers improvements in terms of robustness to modeling uncertainties and errors. The proof of stability is derived based on Lyapunov that demonstrates convergence of estimates towards the true state values. The proposed filtering strategy is based on a second-order Markov process that utilizes information from the current and past two time steps. An experimental system was setup and characterized in order to demonstrate the proposed filtering strategy's performance. The strategy was compared with the popular Kalman filter (and its nonlinear form) and the smooth variable structure filter (SVSF). Experimental results demonstrate that the proposed nonlinear second-order filter provides improvements in terms of state estimation accuracy and robustness to modeling uncertainties and external disturbances. [ABSTRACT FROM AUTHOR]

This paper deals with thermal-fluid-structure coupling analysis for valve plate friction pair of axial piston pump in electrohydrostatic actuator (EHA) of aircraft. The axial piston pump with high pressure and high rotational speed to be widely applied in EHA of more electric aircraft can increase the power density, but it also deteriorates thermal-fluid-structure coupling of the friction pairs. In order to reveal its interior multiphysics field coupling mechanism, taking the valve plate friction pair in three key friction pairs for example, this study carries out the research on multiphysics field coupling. Firstly, Navier–Stokes equations and energy equation of the incompressible fluid considering the influence of temperature and pressure on the oil properties, heat conduction governing equation with many boundary conditions including heat flux, heat convection, heat radiation and considering the influence of the structure deformation on the temperature and the influence of the temperature on the material properties, the elastic mechanics model of the structure exerted together by temperature, fluid pressure and mechanical load, are established. On this basis, a complete set of fast and effective thermal-fluid-structure coupling method is originally presented, and the numerical analysis is conducted using it for the valve plate friction pair. By the calculation results, the evolution laws with time and space are revealed regarding to the pressure and temperature of the fluid in the chambers, and the temperature, stress and deformation of the valve plate friction pair, the wedge-shaped clearance forms between them, even mixed friction occurs, and the corresponding improving measures aimed at the discovered problems are discussed. These results can provide the theoretical evidence for the design and development of the pump of EHA. [ABSTRACT FROM AUTHOR]

During the last few years, the concept of more-electric aircraft has been pushed ahead by industry and academics. For a more-electric actuation system, the electrohydrostatic actuator (EHA) has shown its potential for better reliability, low maintenance cost and reducing aircraft weight. Designing an EHA for aviation applications is a hard task, which should balance several inconsistent objectives simultaneously, such as weight, stiffness and power consumption. This work presents a method to obtain the optimal EHA, which combines multi-objective optimization with a synthetic decision method, that is, a multi-objective optimization design method, that can combine designers' preferences and experiences. The evaluation model of an EHA in terms of weight, stiffness and power consumption is studied in the first section. Then, a multi-objective particle swarm optimization (MOPSO) algorithm is introduced to obtain the Pareto front, and an analytic hierarchy process (AHP) is applied to help find the optimal design in the Pareto front. A demo of an EHA design illustrates the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]