Numerical Simulation for Redundant Electro-Hydrostatic Servo-Actuators under Certain Special Conditions

Abstract

This work presents some numerical simulations, performed using AMESim software, for a system composed by two redundant servo-actuators. Certain operating conditions are taken into account for these two electro-hydrostatic servo-actuators, which are coupled to the command surface (aileron) of a transport aircraft. We first considered the situation of slight asymmetries in the construction of the servo-actuators, then a situation in which one servo-actuator fails at maximum flight speed, and then at a medium flight speed, and finally we considered the effect of gusts upon the system. Small differences in the construction of the servo-actuators were taken into consideration by modifying each of the pump displacements, one by +2% and one by −2%, from the nominal value. It is possible that many other asymmetries exist in the construction of servo-actuators, such as different liquid leakages in the cylinders or pumps, small differences in the controller coefficients, and so on. These differences should be taken into account in future works. Our results provide evidence that, under some operation situations of redundant servo-actuators, significant overstresses can appear in one servo-actuator, leading to a decrease in the time for which the system operates correctly.

Keywords

• electro-hydrostatic
• servo-actuators
• numerical simulation
• AMESim software