Electromagnetic Compatibility Of Electronic Universal Testing Machine And Control System Design

Electronic universal testing machine is a kind of important scientific test equipment, which can detect the mechanical properties, technological properties, antivibration structure strength, and internal and external surface defect of material in the realistic and simulation states.Electronic universal testing machine control system is a set of automatic control system based on the programmable device--FPGA, which is used for the data-detecting and controlling motion. Hardware monitoring and control cards is a lower computer of the cintrol system. The hardware monitoring and control cards not only can collect and process the data of material mechanical properties, but also can control accurately the executing mechanism. The upper computer is based on the PC controlling and testing system. The application level software for the tesing and controlling system is compiled by LabVIEW8.2. The application level testing and controlling software has the friendly man-machine interface and convenient measuring and controlling method. Automatic measuring and accurate controlling in PC can be implemently.The measurement and control system developed previously in my lab was apt to be disturbed, and had the bad self-compatibility to the lower measuring precision and the weak testing and controlling stability, because of neglecting electromagnetic compatibility. The research contents of the paper are to improve the measuring stability and the measuring accuracy based on the study of electromagnetic compatibility. To improve the compatibility of electromagnetic, filtering and application of grounding technology are studied. Filtering can be divided into hardware and software filtering. Hardware filtering adopts the analog input channel signal filtering, power supply interface filtering, various IC circuit decoupling and bypass. Software filtering has the digital low-pass filter in the CPU FPGA, and median filtering in the LabVIEW of the upper computer. Groundings include the division and merger of the digital grounding and simulating grounding, the reasonable layout of the power plane and lower plane, and wire diagram layout of PCB and anti-disturbance. In addition, software redundancy technology is used in FPGA. The fault-tolerance performance of system and contingency performance is improved. Program fleet can be avoided by the addition of software watchdog. The testing and controlling program can retune to the normal operating orbit by means of the software watchdog when the mistakes occurred. In the base of the previous simple measuring and controlling interface in the upper computer, the force-shifts collection function, median filter function, measured data storage function, and printing function for the measured figure and data are added. The new measuring and controlling system has the advantage of collection and storage of the measured curve and data in the experiments. In addition, the system has more stronge points. For example, the measued curve and data can be analysied and printed, the motion can be controlled previously, the measured paraments can be prepared easily, and it have good data online processing.The results indicated the system has the stability, anti-disturbed and high testing accuracy. The system can meet the design requirements and achieved the desired results. Several points can be controlled by the use of the electromagnetic compatible, such as filter and grounding. The error of chip misoperation caused by the distortions from the outside can be monitored dynamic, and the error can be leaded to the normal operating orbit. The curve, measured by the testing of mental material sample, is compared with the previous curve form the previous system. The results showed that the system has the high stability, anti-disturbed, and testing precision.