Mathematical modeling of the electrohydraulic rotary motion servo drive

The article presents a mathematical model of the electrohydraulic rotary motion servo drive, which consists of two cylinders, running on a common crankshaft. The kinematic schematic diagram and the hydraulic circuit of this drive type are presented. The mathematical model takes into account a dry friction in the drive elements and nonlinear characteristics of the electrohydraulic servo valve. The results of mathematical modeling for different input levels are presented. The causes of uneven rotation of the output shaft both at the lower and the upper angular velocity limits are stated. The authors point out a significant expansion of the lower rotation speed limit as compared to the rotational drives based on a hydromotor.