Design And Experimental Study Of Electro-hydraulic Servo Dynamic Testing Machine Control System

Electro hydraulic servo dynamic testing machine as the material testing machine is animportant branch of the field, more and more domestic and foreign testing machinemanufacturing enterprise. Electro hydraulic servo dynamic material testing machine is a kindof complicated nonlinear system, the application of servo valve controlled hydraulic cylindertest specimens for fatigue loading. Electro hydraulic servo dynamic testing machinemechanical structure, containing time delay, parameter changes, uncertainty, at the same timethe system vulnerable to load, hydraulic pressure, temperature adjustment, dynamic test, thedetected material specimen rigidity change, so that the signal accurate control forelectro-hydraulic servo control research a serious problem. Namely:" on the specimen isloaded on the response signal can accurately follow the excitation signal ".At present, our test machine manufacturers in the digital electro-hydraulic servo controllermade remarkable achievements, but cannot evasive is, our country in electro-hydraulic servoin the field of control strategy is used, still at a low level, also caused, in the field of nationaldefense and aerospace materials testing, has been the subject of foreign. Therefore, how in theelectro hydraulic servo dynamic testing machine, the application of modern control theory,has become an important criterion of judging controller. This paper mainly focuses on thefollowing three aspects of the work:(1) for electro-hydraulic servo testing machine control system hardwaredesign. Application of hierarchical control of grading design of electro-hydraulic servohardware part, control layer using high-end ARM9embedded microprocessor LPC3250as theelectro-hydraulic servo dynamic testing machine core controller; action layer selection ofintelligent type chip BTS7960servo valve driving circuit to drive Italy ATOS hydraulic servovalve, through the servo valve control, complete testing machine cycle and non-periodicsignals through experiments, high precision hydraulic pressure sensors to detect system ofmechanical properties, high resolution photoelectric coder displacement measuring system.(2) real-time operating system in μ C/OS-II as part of the development of programexecution. On the basis of hardware system hierarchical characteristics, as well as theelectro-hydraulic servo testing machine features, using the structure of modular framework,system software development platform. The software system is divided into three parts: theman-machine communication layer, testing machine control management and hardwareimplementation layer. Make full use of embedded real time operating multi-threadedmulti-task mechanism, in each layer generates a plurality of function module.(3) electro-hydraulic servo material testing machine control strategy research. On theanalysis of the electro-hydraulic servo fields related to, control strategy, this paper applied theinverse control theory, the mathematical model of the system identification. AIC (ADPTIVEINVERSE CONTROL) is a kind of compensation algorithm, through the use of anapproximate linear system model to improve the system instead, following performance. Thiscontrol method can improve the most testing machine control system to follow, but the mosteffective use is in a broadband random and periodic signal.