21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-5.5.3

COMPUTER VISUALISATION AND SIMULATION OF FAST CYCLIC HYDRAULIC ACTUATOR DYNAMICS

Jankovic J.
University of Belgrade, F. R. of Yugoslavia

Keywords: computer visualisation, simulation, fast cyclic, hydraulic actuator dynamics

In the paper is presented complete mathematical model of generalised fast cyclic hydraulic actuator dynamics, based on Rieman's equations in addition with corresponding external and internal boundary conditions. Fast cyclic hydraulic actuator can be assumed as two serially connected compressible fluid flows controlled by supply and return variable flow restrictors enclosed in control servovalve and separated by actuator piston. Exposed dynamic model includes several physical effects: fluid viscosity and compressibility, compression and expansion wave propagation in direct and reverse actuator modes, geometric and flow asymmetry, actuator equivalent inertia including remote mechanism of aircraft control surfaces, potential external load and arbitrary servo-valve control input. Solution of presented mathematical model is evaluated by using method of characteristics. Corresponding boundary conditions assumes actuator piston position as a movable boundary between direct and reverse part of actuator chamber. Main advantage of presented method is that corresponding computer package enables actuator simulation for its arbitrary states of function by using the same computational procedure.

view full paper