Study Of Digital Axial Piston Pump Control System

With rapid development of technology, information technology which mainly be composed of computer technology is taking a more and more important role in industry. The embedded system using embedded microprocessor as its main control chip, has advantages of faster speed, smaller volume, lower cost and with more functions, that makes it have broader and broader application in industry field. Hydraulic technology has obviously advantages in some industry field. There is a very important trend that using information technology to control conventional hydraulic equipments in hydraulic technology development. And how to improve the performance of digital hydraulic control and how to reduce their cost are the directions of digital hydraulic technology research, and are also the exigent needs of hydraulic industry.The paper is going to research on the control system of digital variable axial piston pump widely used in market at the present time. To improve the control performance of digital variable pump and satisfy the needs of industry application, the paper has designed an embedded control system using embedded ARM microprocessor as its main control chip and embedded Linux operation system as its kernel. In the process of research, the target of the research is to realize the constant flow control of the variable pump. And in aspect of human and machine interface, touch screen technology is used to improve the performance of human and machine communication in control system.The paper is going to introduce the research mainly in the following aspects, according to what I do in the research program.First of all, the structure of the CCY14-1B variable pump and its work principles were analysed. According to its working features, dynamic mathematic models of stroking mechanism of the variable pump and statics mathematic models of its other parts were set up, and then increment Laplace equations were also set up, at last the equations were consolidated to set up transfer function of the system which expressed the relationship of output and input. Secondly, the mathematic model was used to analyse and simulate the system, and the BODE graph and closed-loop step response graph were drew in the environment of MATLAB software. And then, performance of stability and dynamic of the system were analysed according to the graphs drew before. According to the results of analysis, a method of compensator was proposed that is proportional-derivative (PD) compensator to improve the performance of stability and dynamic of the system.Then, a development board with ARM microprocessor was chosen. According to features of the development board, U-Boot which is used to load the Linux kernel was designed. And according to the features of application, the Linux kernel was designed and transplanted to the board. After that, tool of Busybox was used to design a yaffs2file system. Finally, the embedded operation system running normally on the board was realized. At the same time when we established software platform of the control system, in aspect of hardware platform, stepper motor was used as control motor of the system, and sensor used to detect the value of output was chosen, that makes the system be a closed-loop control system.At last, in the platform of control system, driver process and main process of the digital variable pump were designed. Meanwhile, touch screen interface was designed by using Qt graphic develop software used in Linux environment to design Qt application process.In this way, the control system design of digital axial piston pump was achieved. In the final part of the paper, there are conclusions which summed up what have been done in the paper and proposed prospects which pointed out the directions of development of the project.