Seismometer Feedback Control System Based On Voice Coil Motor

The basis of earthquake prediction is accurate and effective earthquake observation data. At the same time, Seismic exploration method is one of the most efficient method among the underground structure exploration methods. It has the characteristics of great detective depth and high accuracy. And all these depend on high performance earthquake observation instruments. Seismometer is widely used in the field of seismic exploration.It’s a kind of sensor which can transform earth mechanical vibrations into detectable physical quantities. It plays an very important roll in the research areas of earthquake prediction and underground resources exploration.The practical application demand of earthquake observation determined the direction of seismometer research is characterized in broadband,large dynamic range and high resolution. Due to the limitation of the key components materials and machining technology, simply changing the mechanical structure of the seismometer cannot improve the technical specifications effectively.Therefore, It’s necessary to add a feedback element to the original mechanical framework. A set of seismometer feedback control system with the advantage of quick response, precise control becomes particularly important. The voice coil motor with many advantages,especially suit for high-response, high-precision, high-frequency reciprocating motion occasions.The outstanding advantages apply to seismometer feedback control system,it’s helpful to improve the shortcomings of the traditional mechanical structure of the seismometer, such as reduce mechanical resonance, eliminate mechanical impact,improve the pendulum large amplitude bearing capacity, and so on. To achieve the purpose of expansion of the frequency bandwidth and dynamic range, and improve the resolution.The paper is based on CMG-3T mechanical pendulum seismometer. Firstly,introduce and analysis the seismometer mechanical structure and the working principle of its force-balance feedback state.Based on this, establish seismometer and voice coil motor electromechanical coupling mathematical model.And determining the seismometer feedback control system parameters.Derive the transfer function relationship of the system.Secondly, on the basis of the transfer function of the system.According to the design requirements,the paper makes a study on seismometer feedback control system control strategies.Create simulation model in the Matlab software environment.And the algorithm is optimized.The position loop feed back control is completed by DSP28335.Based on the done above,the hardware and software program of the seismometer feedback control system are designed.Finally, the whole system is built.And carry out experiment on low-frequency standard vibration platform.The performance of the seismometer feedback control system is tested and calibrated.The test result shows that: the seismometer has a frequency band of 0.05 Hz to 36 Hz, and the sensitivity is about700 m V/mm/s.Complete the seismometer force-balance feedback control and feedback network digitization.