Jean-Charles Maré

Estimation models for the preliminary design of electromechanical actuators

This article presents estimation models for the model-based preliminary design of electromechanical actuators. Models are developed to generate all the parameters required by a multi-objective design, from a limited number of input parameters. This is achieved using scaling laws in order to take advantage of their capability to reflect the physical constraints driving the actuator’s component sizing. The proposed approach is illustrated with the major components that are involved in aerospace electromechanical actuator design. The established scaling laws provide the designer with parameters needed for integration into the airframe, power sizing, thermal balance, dynamics, and reliability. The resulting estimation models are validated with industrial data.

A force equalization controller for active/active redundant actuation system involving servo-hydraulic and electro-mechanical technologies

The force equalization of a hybrid actuation system combining one servo-hydraulic actuator and one electro-mechanical actuator operated in position control and in active/active mode is addressed for safety critical applications such as primary flight controls. In a first step, an accurate virtual test bench is built to facilitate the analysis of force fighting and the assessment of the performance and robustness of the proposed force equalization strategies. It is validated from real experiments performed for the aileron actuator of a single-aisle commercial aircraft. Static force equalization is achieved first by adding equalization offsets in the position control loops as a function of the integral of the force difference between actuators. In order to keep a high level of segregation, the authority for this action is limited to 4% of the total actuator stroke. The dynamic force equalization is performed by forcing the two actuators to follow the same path. Thus, a trajectory generator is introduced to output the required position, velocity and acceleration from the position set point with realistic reproduction of the actuator power limits. Feedforward actions are used to compensate the major and invariant effects such as servo-hydraulic actuators functional flow and electro-mechanical actuator inertial torque. In this way, the pursuit errors are significantly reduced without decreasing robustness. Then, the accurate virtual test bench is used to assess the robustness of the force equalization strategy by analyzing the sensitivity of performance indicators to parameters and operating conditions. It is shown that the proposed force equalization scheme meets all the requirements, including segregation, robustness and simplicity.

Optimal preliminary design of electromechanical actuators

This paper presents a methodology for the optimal preliminary design of electro-mechanical actuators. The main design drivers, design parameters and degrees of freedom that can be used for preliminary design and optimization of electro mechanical actuator are described. The different types of models used for model-based design (estimation, simulation, evaluation and meta-model), and their associations are presented. The process preferred for its effectiveness in terms of flexibility, and computational time is then described and illustrated with the example of a spoiler electromechanical actuator. The proposed approach, based on meta-models obtained using the surfaces response methods and scaling laws models, is used to explore the influence of anchorage points and transmission ratio on the different design constraints and the overall mass of the actuator.

Modelling and simulation of mechanical transmission in roller‐screw electromechanical actuators

Purpose – The purpose of this paper is to develop accurate model and simulation of mechanical power transmission within roller‐screw electromechanical actuators with special attention to friction, compliance and inertia effects. Also, to propose non‐intrusive experiments for the identification of model parameters with an integrator or system‐oriented view.Design/methodology/approach – At system design level, the actuation models need to reproduce with confidence the energy losses and the main dynamic effects. The adopted modelling methodology is based on non‐intrusive measurements taken on a standard actuator test‐bench. The actuator model is first structured with respect to the bond‐graph formalism that allows a clear identification of the considered effects and associated causalities for model implementation. Various approaches are then combined, mixing blocked or moving load, position or torque control and time or frequency domains analysis. The friction representation model is suggested using a step‐b...

Friction modelling and simulation at system level: a practical view for the designer:

The modelling and simulation of friction at the system level is addressed using a practical approach that aims at providing the developer of system level virtual prototypes with realistic modelling and numerically robust simulation of friction. In this attempt, the paper provides key knowledge for the efficient use, development or extension of friction model libraries for electromechanical and fluid power actuators. The first part is dedicated to the factors that may influence friction at component or equipment level. Besides the well documented effect of speed, the work focuses also on the effects of position, load, direction of power, temperature and time. The second part deals with friction modelling and its numerical implementation for simulation. Particular attention is paid to the transition between the sticking and the sliding modes. Accordingly, the candidate models are sorted into three generic types (static mass-free, dynamic mass-free and dynamic mass-integrated) in order to point out numerical issues as well as constraints that apply to the development and use of a friction model library. The models and their implementation are discussed from a practical point of view. Summary tables recapitulate the properties of the candidate friction models considering the reproduced effects, the numerical constraints and their availability in the most common one-dimensional simulation tools.

Requirement-based system-level simulation of mechanical transmissions with special consideration of friction, backlash and preload

Abstract Mechanical transmissions are addressed with a system-level view for preliminary sizing and virtual prototyping. The simulation needs are transformed into requirements that drive the model development. Balanced models, incremental modeling, parameterization from datasheets, admittance to causal cases, fault injection or ageing, and reduction of discontinuities are considered with particular attention throughout. Examples of implementation are given for a nut-screw in the Dymola–Modelica simulation environment. The mechanical transmission is decomposed as a sequence of perfect power transmission, friction and compliance. In the compliance model, a single parameter allows a continuous transition between preload or backlash. The friction model structure enables irreversible transmissions to be simulated, if needed. Friction is decomposed into load-dependent and load-independent effects, for which parameters can be varied versus velocity and temperature. The influence of the preload force on friction is introduced as an additional load-dependent friction in the preload domain. Finally the mechanical transmission model is assembled and analyzed with respect to admittance of causal cases.

Enhanced Model of Four Way Valves Characteristics and its Validation at low Temperature

Abstract This paper deals with the modelling of sliding spool valves that are used in hydraulic actuation systems. A new model of continuity between opened and closed orifice configurations is proposed and validated from -40 to +32 degrees Celsius. It aims at reproducing accurately the experimental pressure gain, flow gain and leakage flow for a wide range of operating temperatures in the absence of detailed knowledge of the valve design. The proposed unified model of flow at valve orifices considers the mode of operation (opened or closed orifice) and the flow conditions (laminar or turbulent) with special attention to continuity around the hydraulic null. The leakage flow in closed orifice configuration is modelled with reference to a short orifice instead of a laminar gap between infinite planes. The parameter identification and model validation processes are presented in detail and the results are displayed for an aerospace flight control servovalve.

Simulation Based Design of Electromechanical Actuators With Modelica

This article deals with a methodology for the computer-aided design of electromechanical actuators. In the frame of the preliminary design, it focuses on the selection and sizing of various components used in the actuator architectures. The addressed design criteria are the mass and reliability for given effort and speed profiles. The developed library of components for the simulation takes advantage of the non-causal and object oriented characteristics of the Modelica language. Thus, the library models can carry out an inverse simulation of the energy flows going from the mechanical load to the power source. Additionally, the number of parameters to be entered by the user has been minimized by the use of scaling laws, which return all the parameters that are necessary for the simulation. At the end of the article, the proposed approach is illustrated with the sizing and comparison of actuator architectures for an aircraft landing gear steering system.© 2009 ASME

Modelling and Simulating the Pump of an Aerospace Electro-Hydrostatic Module for Fault Detection and Identification Purposes

This communication deals with the modelling and simulation of a fixed-displacement axial-piston pump used in aerospace electro-hydrostatic actuators. The pump model is developed in the LMS-AMESim simulation environment to support the development of fault detection and identification features. The model-based fault diagnosis method is introduced first and the modelling needs are addressed. Then, a system-level pump model is proposed with special considerations to model architecture. The different ways to improve the model’s realism are reviewed, in particular concerning energy losses (bearing friction, leakages in gaps), barrel force balance, piston back pumping, piston eccentricity and pump loading for tests. Finally, directions of research in system-level modelling of hydraulic effects are suggested.Copyright

Incremental Modeling and Simulation of Mechanical Power Transmission for More Electric Aircraft Flight Control Electromechanical Actuation System Application

In the field of more electric aircraft, electromechanical actuators (EMAs) are becoming more and more attractive because of their outstanding benefits of aircraft fuel reduction, maintenance costs saving, and system flexibility improvement. For aerospace electromechanical actuator applications, mechanical power transmission is critical for safety, in which reflected inertia to load, heat generated by energy losses and faults due to jamming, free-play and free-run are specific issues. According to the system-engineering process and simulation-aided design, this communication proposes an incremental approach for the virtual prototyping of EMA mechanical power transmission. Resorting to the Bond-graph formalism, the parasitic effects are progressively introduced and realism of models is increased step-by-step. Finally, the numerical implementations are presented and compared with basic, advanced and full models of mechanical power transmission in AMESim environment. Multi-level submodels are available and can be re-used for preliminary sizing, thermal balance verification and response to fault analysis. NOMENCLATURE Cb Cm Cj Cs Bearing translation support, motor electromagnetic, nut-screw inertial, rod output to surface torque [N/m] F0 Preload force [N] Fb Fc Fd Fe Bearing support translation, compliance contact, damping, elastic force [N] Fex, External aerodynamic force [N] Ff * f F f F Initial normal, faults injections and temperature sensitivity friction force [N] FL Load force [N] Fm Fs Motor shaft output, rod output to surface force [N] jam F Jamming stiction force [N] fv Viscous friction coefficient [N/(m/s)] Im Is Motor windings, DC supplied current [A] Pd Pf Damping, friction loss [W] S Heat power [J/sK] Um Us Motor wingdings, DC supplied voltage [V] vb ve vr vs vsr Bearing support, elastic, relative, rod output to surface, relative rod/support translational velocity [m/s] x0 * 0 x 0 x Initial normal, faults injections, temperature sensitivity backlash/preload parameter [m] xc Position command [m] xw Wear parameter of nut-screw [m] xr Relative elastic deformation [m] f f  Initial, temperature sensitivity friction factor[-] x   Temperature dependency backlash/preload parameter [-] d i Efficiency direct, indirect [-]  Temperature [°C] b mn sr Support rotational, motor rotor, relative nut/support, relative rod/support angular velocity [rad/s] i Current/torque loop angular frequency [rad/s] EHA Electro-hydrostatic actuator EMA Electro-mechanical actuator EM Electric motor HSA Hydraulic servo actuator MPT Mechanical power transmission PDE Power drive electronics INTRODUCTION Safer, cheaper and greener technologies are important initiatives for the next generation air transport in upcoming decades. In response to these needs, the aerospace industry is looking for an innovation (incremental or disruptive) in safetycritical actuation systems. In recent years, a significant interest is towards “more electric aircraft”. The trend is to increase the usage of power-by-Wire (PbW) electrical actuators: electrohydrostatic actuator (EHA) and electro-mechanical actuator (EMA). These are envisioned to take the place of conventional hydraulic servo actuators (HSA). Compared to EHAs, EMAs totally remove the central and local hydraulic circuits, resulting in increased economic, competitive and environmental Proceedings of the ASME 2016 International Mechanical Engineering Congress and Exposition IMECE2016 November 11-17, 2016, Phoenix, Arizona, USA