Electromagnetic Vibration Table Control System Based On DDS

Electromagnetic vibration table is widely used in national defense, aviation, aerospace, communication, electronics, automobiles, home appliances, etc. It’s mainly used for the detection of early fault, simulation of the real working condition for the strength test. Compared to the other types of vibration table, electromagnetic vibration table has a wider frequency range, for example the small vibration table has a frequency range of0-10kHz and the big vibration table has a frequency range of0-2kHz.It has a wide dynamic range and a good acceleration waveform that can get a great value. It’s easily to achieve automatic and manual control,suitable to produce random wave.The core device of electromagnetic vibration table is frequency synthesis circuit that generate driving signals to the table.Along with the development of the actual demand,multiple degree of freedom and portable become the a great development direction of vibration table. This requires frequency synthesis circuit can generate multichannel synchronizing signal, and a small size with low power consumption. So the traditional frequency synthesis technology has not qualified for these requirements. In this paper, we propose a pure digital frequency synthesis technology, direct frequency synthesis technology (DDS). Compared with the traditional frequency synthesis technology, it has the advantages of low power consumption and high resolution,and is competent to the performance requirements of vibration table controller.At first the paper introduced the development of the frequency synthesis technology and the features of DDS technology. Then design a frequency synthesis systems used in vibration table controller with the STM32micro controller and multichannel synchronizing DDS chip AD9959, completed the corresponding hardware and software. The control program on PC writed in Delphi communicate with the STM32micro controller through RS232bus. Micro controller drive the AD9959chip according to the data from PC, then we can get up to4channel synchronous sine signals, achieve the linear sweep or modulation of frequency, phase or amplitude on all channel.In the end, the paper Introduce the test of the frequency synthesis systems, reveal the data of waveform on different operating mode, analysis the error and proposed the improvement plan.