The Study Of Hydraulic Servo Control System Based On Modular Design

Hydraulic servo computer control system can be divided into upper and lower computer. Upper computer is to achieve the friendly interface between computer and operator, and signal acquisition, implementation algorithm and driving the acutator are achieved by the lower computer. According to the software category, the control system can be divided into five parts: A/D module, Filter module, Control algorithm module, D/A module and Communication module.In the actual system, many manufacturers provide completely functional data acquisition card, such as ADVANTEC Family card, which supply complete A/D module, D/A module, I/O Interface module, counter module and relevant drive software. However, the driver software is usually applied to DOS or Windows operation system. So it is hard to provide perfect interface for the composition of each module. Also for the need of control system, the multi-task and real-time operation system is always chosen. So for the disadvantages listed above, based on algorithm characteristics of each module, it is highly necessary to choose a design method which can encapsulate algorithm effectively and protect instantiation of class well. So according to the characteristics of ADVANTECH family data acquisition control card and the need of research, works accomplished are shown below:1) Based on Strategy strategy of Behavioral Pattern, the properties and service function of common used hardware module, data pretreatment module, and common used control algorithm are encapsulated.2) IIR filter design method is used in the Pretreatment module to implement the algorithm of low pass ButterWorth Filter. The low pass ButterWorth Filter can effectively filter the high frequency signal, and retain low pass signal.3) Classical control algorithm PID is used in the control module, and Notch Filter algorithm is added to reduce the resonance frequency of system.4) Based on Singleton of Creation Pattern, both network communication and CAN communication are used in upper and lower communication software module to implement the data exchange between them.5) AMESim software is used to simulate the input signal of following feature of single hydraulic cylinder, and then experiment is carried out to prove the fine control feature.