Adaptive Control of an Aerospace Electrohydrostatic Actuator with a Constant-Torque Variable-Displacement Pump

Abstract

An electrohydrostatic actuator (EHA) system is one of the key components of electric aircraft flight controls. The EHA system with fixed pump displacement and variable motor (EHA-FPVM) is widely used because of its simple structure, but the power weight ratio of EHA-FPVM is small, although it is very important to an aircraft. A novel EHA with a constant-torque variable-displacement pump (CTVDP) is proposed and simulated; it can substantially decrease the maximum motor-rated torque while reducing the servo-motor volume and weight. First, the CTVDP structure of the EHA system is proposed and a constant-torque variable-displacement pump is designed. Second, mathematical models of the EHA system structure are developed and simplified according to the constant-torque displacement–pressure law. Third, an adaptive backstepping control algorithm is proposed to improve position-tracking performance in the presence of the uncertain viscous damping coefficient. Finally, numerical simulations prove that the EHA system with CTVDP structure can further decrease motor maximum torque by approximately 37.5% and is robust against load impact, pump displacement variation, and parameters uncertainty. The results of this study can serve as the foundation for future application.