A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxationfree(SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. Howe...A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxationfree(SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. However, the fluctuation of probe light intensity is one of the main technical error sources that limits the bias stability of the gyroscope. Here we propose a novel method to suppress the bias error induced by probe light intensity fluctuations. This method is based on the inherent magnetic field response characteristics of the gyroscope. By the application of a bias magnetic field, the gyroscope can be tuned to a working point where the output signal is insensitive to probe light intensity variation, referred to herein as ‘zero point’, thus the bias error induced by intensity fluctuations can be completely suppressed. The superiority of the method was verified on a K–Rb–21 Ne co-magnetometer, and a bias stability of approximately 0.01°/h was obtained. In addition, the method proposed here can remove the requirement of the closed-loop control of probe light intensity, thereby facilitating miniaturization of the gyroscope volume and improvement of reliability.展开更多
Prony spectrum analysis is employed in this paper to analyze the harmonics of estimation of radial runout of axis in error separation. The result of analysis verifies the existence of harmonic suppression in multi-st...Prony spectrum analysis is employed in this paper to analyze the harmonics of estimation of radial runout of axis in error separation. The result of analysis verifies the existence of harmonic suppression in multi-step method, thereby advancing the study of harmonic suppression which stayed at the theoretical level for years.展开更多
A miniaturized atomic spin-exchange relaxation-free(SERF)co-magnetometer measures angular velocity using a balanced polarimetry technique which is easily affected by the laser power.A laser power closed-loop control s...A miniaturized atomic spin-exchange relaxation-free(SERF)co-magnetometer measures angular velocity using a balanced polarimetry technique which is easily affected by the laser power.A laser power closed-loop control system is usually used to suppress the fluctuation of the laser power.Although this method can greatly eliminate the fluctuation of the in-loop laser power(the feedback laser),it cannot fully eliminate the fluctuation of the out-of-loop laser power(the signal measurement laser).This leads to SERF gyroscope laser power error,which reduces the inertial measurement accuracy.In this paper,the influence mechanism of the split ratio(the ratio of the in-loop laser power to the out-of-loop laser power)on the out-of-loop laser power control accuracy is analyzed by establishing a laser power transmission model inside and outside the loop.Moreover,a method is developed to improve the out-of-loop laser power stability by optimizing the split ratio.Comparative experiments showed that the relative Allan standard deviation of the out-of-loop laser power decreased from 5.48×10^(-6)to 2.62×10^(-6)at 100 s,and decreased by an order of magnitude from 1.76×10^(-5)to 3.30×10^(-6)at1000 s.Correspondingly,the rate ramp coefficient in the Allan standard deviation curve of the SERF gyroscope test data decreased from 1.312[(°/h)/h]to 0.246[(°/h)/h].And the bias stability increased from 0.032°/h to 0.019°/h.Therefore,the proposed method can improve the long-term stability of the probe laser power and effectively suppress the laser power error of the SERF gyroscope.展开更多
针对城市峡谷及高动态应用场景下卫星伪距观测受大气建模残差、多径及观测噪声影响,易产生随机扰动与缓慢变化的偏差,从而导致伪距误差增大并呈现明显的非平稳特征的问题,提出了一种移动射频测距辅助的卫星伪距误差抑制方法.该方法在原...针对城市峡谷及高动态应用场景下卫星伪距观测受大气建模残差、多径及观测噪声影响,易产生随机扰动与缓慢变化的偏差,从而导致伪距误差增大并呈现明显的非平稳特征的问题,提出了一种移动射频测距辅助的卫星伪距误差抑制方法.该方法在原始北斗卫星伪距观测基础上,引入具有独立量测特性的移动射频测距信息,构建对卫星伪距的补充观测约束,利用两者在误差来源上的独立性,在联合解算过程中抑制伪距误差的传播.无人机动态实验结果表明,所提出的方法能够显著降低北斗卫星伪距残差的均方根(root mean square,RMS),相较于载波相位平滑伪距方法,伪距残差RMS降低82.3%.所提出的移动射频测距辅助卫星伪距误差抑制方法在复杂动态与遮挡环境下具有良好的伪距误差抑制能力,克服了载波相位平滑伪距对连续载波锁定的依赖及其对系统性偏差抑制能力不足的局限,具有鲁棒性强、适应性好的特点,为复杂环境下北斗卫星伪距误差抑制与观测质量提升提供了一种有效途径.展开更多
Global Positioning System data processing is affected by many non-tectonic factors, including the common-mode errors （CME） in station-position time series. The characteristics and origins of CME are still not clear,...Global Positioning System data processing is affected by many non-tectonic factors, including the common-mode errors （CME） in station-position time series. The characteristics and origins of CME are still not clear, due to uneven distribution of global GPS networks and the lack of reliable data of the position time series. In this work, data from 241 continuous GPS stations were reprocessed in a consistent way and the results were compared with those generated at Jet Propulsion Laboratory （JPL）. Improvements of residual positions were obtained for many low-quality stations, especially those located in Asia and Australia.展开更多
为实现高效率、低成本的镍磷合金光学元件全频段误差抑制,提出了小磨头抛光中基于宏观耕犁机制和微观化学键拔除机制的宏微观协同作用去除机理。基于赫兹接触理论,通过工件表面的弹塑性形变探讨耕犁机制产生的临界值,构建了磨粒作用机...为实现高效率、低成本的镍磷合金光学元件全频段误差抑制,提出了小磨头抛光中基于宏观耕犁机制和微观化学键拔除机制的宏微观协同作用去除机理。基于赫兹接触理论,通过工件表面的弹塑性形变探讨耕犁机制产生的临界值,构建了磨粒作用机制与工艺参数之间的关联模型——小磨头抛光磨头极限压力模型,实现了对宏微观去除机制的调控,从而达成全频段误差的有效抑制。随后通过第一性原理分子动力学仿真分析,探究了抛光过程中磨粒分子团簇与镍磷合金光学元件表层分子的相互作用,直观表征了镍磷合金抛光过程中的微观化学键拔除机制,该仿真分析对镍磷合金光学元件超光滑抛光具有指导意义。基于宏微观协同作用去除机理对φ50的铝基镀镍磷合金平面反射镜进行小磨头迭代抛光实验,在有效抑制中低频误差的同时,将表面粗糙度R a从2.252 n m提升到0.502 nm,提升了77.7%,实现了镍磷合金反射镜超光滑表面全频段误差的抑制。实验结果表明,宏微观协同作用去除机理适用于镍磷合金光学元件的全频段误差抑制,对于镍磷合金光学元件超精密加工提供了借鉴意义。展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFB0501600 and 2017YFB0503100)the National Natural Science Foundation of China(Grant Nos.61773043,61673041,and 61721091)
文摘A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxationfree(SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. However, the fluctuation of probe light intensity is one of the main technical error sources that limits the bias stability of the gyroscope. Here we propose a novel method to suppress the bias error induced by probe light intensity fluctuations. This method is based on the inherent magnetic field response characteristics of the gyroscope. By the application of a bias magnetic field, the gyroscope can be tuned to a working point where the output signal is insensitive to probe light intensity variation, referred to herein as ‘zero point’, thus the bias error induced by intensity fluctuations can be completely suppressed. The superiority of the method was verified on a K–Rb–21 Ne co-magnetometer, and a bias stability of approximately 0.01°/h was obtained. In addition, the method proposed here can remove the requirement of the closed-loop control of probe light intensity, thereby facilitating miniaturization of the gyroscope volume and improvement of reliability.
文摘Prony spectrum analysis is employed in this paper to analyze the harmonics of estimation of radial runout of axis in error separation. The result of analysis verifies the existence of harmonic suppression in multi-step method, thereby advancing the study of harmonic suppression which stayed at the theoretical level for years.
基金the National Natural Science Foundation of China(Grant Nos.61925301 and 62103026).
文摘A miniaturized atomic spin-exchange relaxation-free(SERF)co-magnetometer measures angular velocity using a balanced polarimetry technique which is easily affected by the laser power.A laser power closed-loop control system is usually used to suppress the fluctuation of the laser power.Although this method can greatly eliminate the fluctuation of the in-loop laser power(the feedback laser),it cannot fully eliminate the fluctuation of the out-of-loop laser power(the signal measurement laser).This leads to SERF gyroscope laser power error,which reduces the inertial measurement accuracy.In this paper,the influence mechanism of the split ratio(the ratio of the in-loop laser power to the out-of-loop laser power)on the out-of-loop laser power control accuracy is analyzed by establishing a laser power transmission model inside and outside the loop.Moreover,a method is developed to improve the out-of-loop laser power stability by optimizing the split ratio.Comparative experiments showed that the relative Allan standard deviation of the out-of-loop laser power decreased from 5.48×10^(-6)to 2.62×10^(-6)at 100 s,and decreased by an order of magnitude from 1.76×10^(-5)to 3.30×10^(-6)at1000 s.Correspondingly,the rate ramp coefficient in the Allan standard deviation curve of the SERF gyroscope test data decreased from 1.312[(°/h)/h]to 0.246[(°/h)/h].And the bias stability increased from 0.032°/h to 0.019°/h.Therefore,the proposed method can improve the long-term stability of the probe laser power and effectively suppress the laser power error of the SERF gyroscope.
文摘针对城市峡谷及高动态应用场景下卫星伪距观测受大气建模残差、多径及观测噪声影响,易产生随机扰动与缓慢变化的偏差,从而导致伪距误差增大并呈现明显的非平稳特征的问题,提出了一种移动射频测距辅助的卫星伪距误差抑制方法.该方法在原始北斗卫星伪距观测基础上,引入具有独立量测特性的移动射频测距信息,构建对卫星伪距的补充观测约束,利用两者在误差来源上的独立性,在联合解算过程中抑制伪距误差的传播.无人机动态实验结果表明,所提出的方法能够显著降低北斗卫星伪距残差的均方根(root mean square,RMS),相较于载波相位平滑伪距方法,伪距残差RMS降低82.3%.所提出的移动射频测距辅助卫星伪距误差抑制方法在复杂动态与遮挡环境下具有良好的伪距误差抑制能力,克服了载波相位平滑伪距对连续载波锁定的依赖及其对系统性偏差抑制能力不足的局限,具有鲁棒性强、适应性好的特点,为复杂环境下北斗卫星伪距误差抑制与观测质量提升提供了一种有效途径.
基金supported by the Institute of Crustal Dynamics Fund(ZDJ2009-01)National Natural Science Foundation of China(41104001)
文摘Global Positioning System data processing is affected by many non-tectonic factors, including the common-mode errors （CME） in station-position time series. The characteristics and origins of CME are still not clear, due to uneven distribution of global GPS networks and the lack of reliable data of the position time series. In this work, data from 241 continuous GPS stations were reprocessed in a consistent way and the results were compared with those generated at Jet Propulsion Laboratory （JPL）. Improvements of residual positions were obtained for many low-quality stations, especially those located in Asia and Australia.
文摘为实现高效率、低成本的镍磷合金光学元件全频段误差抑制,提出了小磨头抛光中基于宏观耕犁机制和微观化学键拔除机制的宏微观协同作用去除机理。基于赫兹接触理论,通过工件表面的弹塑性形变探讨耕犁机制产生的临界值,构建了磨粒作用机制与工艺参数之间的关联模型——小磨头抛光磨头极限压力模型,实现了对宏微观去除机制的调控,从而达成全频段误差的有效抑制。随后通过第一性原理分子动力学仿真分析,探究了抛光过程中磨粒分子团簇与镍磷合金光学元件表层分子的相互作用,直观表征了镍磷合金抛光过程中的微观化学键拔除机制,该仿真分析对镍磷合金光学元件超光滑抛光具有指导意义。基于宏微观协同作用去除机理对φ50的铝基镀镍磷合金平面反射镜进行小磨头迭代抛光实验,在有效抑制中低频误差的同时,将表面粗糙度R a从2.252 n m提升到0.502 nm,提升了77.7%,实现了镍磷合金反射镜超光滑表面全频段误差的抑制。实验结果表明,宏微观协同作用去除机理适用于镍磷合金光学元件的全频段误差抑制,对于镍磷合金光学元件超精密加工提供了借鉴意义。
