COMPUTER SIMULATION OF FAST HYDRAULIC ACTUATORS

Mathematical model of fast hydraulic actuator dynamics, based on Riemann’sequations, is presented in the paper. Fast hydraulic actuator can be assumed as two seriallyconnected compressible fluid flows controlled by supply and return variable flow restrictorsenclosed in control servo-valve and separated by actuator piston. Exhibited dynamic modelincludes several physical effects, such as: fluid viscosity and compressibility, compression andexpansion, wave propagation, actuator equivalent inertia, potential external load and arbitraryservo-valve control input. Solution of the presented mathematical model is evaluated by using themethod of characteristics. Corresponding boundary conditions assume the actuator piston positionas a movable boundary between the direct and the reverse part of the actuator chamber.