Abstract
The use of pump controlled hydraulic servosystem has been increasing in recent years because its superior energy efficiency in comparison with a valve controlled hydraulic servomechanism, though the pump controlled system is inferior in dynamic response. The dynamic characteristics of servo-pump (a pump used in the pump controlled system) must be made clear in order to design the pump controlled servo-system and/or to simulate the response of such a system.
Purpose of this paper is to establish a dynamic model, including unknown parameter identification, of the servo pump.
Firstly, a mathematical model of the servopump was made referring the structure of the servo-pump. Secondly, error response of an actual servo-pump was measured and input signal to servovalve in the servo-pump was calculated. Finally, unknown parameters such as damping coefficient and equivalent compressibility of oil were identified by minimizing sum of squares of difference between theoretical and experimental values of frequency characteristics of servo-pump.
In most cases the identified parameters were found in reasonable range, and scatters were small. However, they became uncertain when input current to the servovalve was smaller than about 10% of the nominal current.
