Design and performance analysis of position-based impedance control for an electrohydrostatic actuation system

Electrohydrostatic actuator（EHA） is a type of power-by-wire actuator that is widely implemented in the aerospace industry for flight control, landing gears, thrust reversers, thrust vector control, and space robots. This paper presents the development and evaluation of positionbased impedance control（PBIC） for an EHA. Impedance control provides the actuator with compliance and facilitates the interaction with the environment. Most impedance control applications utilize electrical or valve-controlled hydraulic actuators, whereas this work realizes impedance control via a compact and efficient EHA. The structures of the EHA and PBIC are firstly introduced. A mathematical model of the actuation system is established, and values of its coefficients are identified by particle swarm optimization. This model facilitates the development of a position controller and the selection of target impedance parameters. A nonlinear proportional-integral position controller is developed for the EHA to achieve the accurate positioning requirement of PBIC. The controller compensates for the adverse effect of stiction, and a position accuracy of 0.08 mm is attained.Various experimental results are presented to verify the applicability of PBIC to the EHA. The compliance of the actuator is demonstrated in an impact test.

Review on signal-by-wire and power-by-wire actuation for more electric aircraft

The huge and rapid progress in electric drives offers new opportunities to improve the performances of aircraft at all levels：fuel burn,environmental footprint,safety,integration and production,serviceability,and maintainability.Actuation for safety-critical applications like flight-controls,landing gears,and even engines is one of the major consumers of non-propulsive power.Conventional actuation with centralized hydraulic power generation and distribution and control of power by throttling has been well established for decades,but offers a limited potential of evolution.In this context,electric drives become more and more attractive to remove the natural drawbacks of conventional actuation and to offer new opportunities for improving performance.This paper takes the stock,at both the signal and power levels,of the evolution of actuation for safety-critical applications in aerospace.It focuses on the recent advances and the remaining challenges to be taken toward full electrical actuation for commercial and military aircraft,helicopters,and launchers.It logically starts by emphasizing the specificity of safety-critical actuation for aerospace.The following section addresses in details the evolution of aerospace actuation from mechanically-signaled and hydraulically-supplied to all electric,with special emphasis on research and development programs and on solutions entered into service.Finally,the last section reviews the challenges to be taken to generalize the use of all-electric actuators for future aircraft programs.