CHZ-Ⅱ海洋重力仪的电磁阻尼方案

An Electromagnetic Damper Scheme for CHZ-Ⅱ Gravimeter

海洋重力仪一般采用强阻尼方案抑制垂直扰动加速度引入的大幅度摆体运动。对CHZ-Ⅱ型海洋重力仪在液体阻尼和电磁阻尼方案下的阻尼系数进行了详细建模,分别得到了两种强阻尼方案下的闭环系统和误差传递模型,并结合设计参数进行了仿真建模分析。在恶劣海况下,外部扰动输入为周期10s、幅度200Gal(1Gal=1cm/s^(2))正弦加速度时,两种阻尼方案分别将摆体运动幅度抑制到5μm和4μm左右,均能保证仪器的正常工作。进一步研究表明,电磁阻尼方案引入的重力测量误差约0.15mGal,满足测量指标需求,其主要误差来源为阻尼执行器电压漂移;而且,电磁阻尼方案可通过参数切换适应各类重力测试环境,大大提高了重力仪的实用性,极具发展优势。

In general,marine gravimeters use a strong damping scheme to suppress the large motion of sampling mass caused by vertical perturbation acceleration.In this paper,the damping coefficients of CHZ-Ⅱmarine gravimeter under liquid damping and electromagnetic damping schemes are modeled in detail,and the model of closed-loop system and error transfer model under two strong damping schemes are obtained,respectively.In addition,based on the design parameters,the simulation model is analyzed.At the same time,under severe ocean conditions,when the external disturbance input is sinusoidal acceleration with a period of 10s and amplitude of 200Gal(1Gal=1cm/s^(2)),the motion amplitude of sampling mass can be suppressed to about 5μm and 4μm respectively by the two damping schemes,which all can ensure the normal operation of the instrument.Meanwhile,further investigations show that the gravity measurement error introduced by the electromagnetic damping scheme is about 0.15mGal to meet the requirement,and the main error comes from the voltage noise of damping actuator.Furthermore,the scheme of electromagnetic damping can adapt to various gravity testing environments by switching parameters,which greatly improves the practical performance of gravimeter and is full of development advantages.