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13 pages, 2989 KiB

Open AccessArticle

Torsion Pendulum Apparatus for Ground Testing of Space Inertial Sensor

by Shaoxin Wang, Zuolei Wang, Dongxu Liu, Peng Dong, Jian Min, Ziren Luo, Keqi Qi and Jungang Lei

Sensors 2024, 24(23), 7816; https://doi.org/10.3390/s24237816 - 6 Dec 2024

Viewed by 534

Abstract

The precise movement of the test mass along a geodesic is crucial for gravitational wave detection in space. To maintain this motion, the core payload-inertial sensor incorporates multiple functional units designed to mitigate various sources of stray force noise affecting the test mass. [...] Read more.

The precise movement of the test mass along a geodesic is crucial for gravitational wave detection in space. To maintain this motion, the core payload-inertial sensor incorporates multiple functional units designed to mitigate various sources of stray force noise affecting the test mass. Understanding the limits of these noise sources is essential for enhancing the inertial sensor system design. Additionally, thorough ground-based verification of these functional units is necessary to ensure their reliability for space missions. To address these challenges, we developed a low-frequency torsion pendulum apparatus that utilizes a commercial autocollimator as the optical readout element for testing this type of space inertial sensor. This paper provides a comprehensive overview of the apparatus’s operating principle, structural characteristics, and the results of laboratory tests of its background noise. Experimental data demonstrate that the torsion pendulum achieves a sensitivity of 1 × 10⁻¹¹ Nm/Hz^1/2 within the measurement band from 1 mHz to 0.1 Hz, confirming its suitability for various inertial sensor tests. Furthermore, the insights gained from constructing the torsion pendulum will inform future system upgrades. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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Figure 1
Measurement method of the TM angle using optical readout and its transfer function. (A) The TM suspended by a fiber is twisted under the action of external stray torque. This angle is precisely measured by an optical readout device through the auxiliary mirror. (B) The transfer function illustrates the relationship between torque and angle of the TM within the measurement frequency band. The resonance frequency of the pendulum is approximately 5 mHz. Full article ">Figure 2
Design form of the TM and EH, along with the electrode distribution used in the torsion pendulum. (A) All surfaces of the TM were ultra-precision machined, with a threaded connection provided in the Z direction. (B) Electrode distribution in different directions: two pairs of electrodes in the same direction controlled one translational and one rotational degree of freedom, respectively. (C) The assembled EH, featuring electrode leads for signal transmission. Full article ">Figure 3
The suspension structure of the TM. The TM was suspended by two fibers separated by a magnetic damper and placed in the EH, which was mounted on the base plate. The suspension path was also provided with two sets of adjusting devices for the position adjustment of the TM. Full article ">Figure 4
The vacuum maintenance system of the torsion pendulum. This mainly consisted of a chamber and a multistage pump group. The autocollimator was fixed on the chamber by a specially designed mounting frame to achieve the angle surveying of the TM inside. Full article ">Figure 5
Main noise curves associated with the designed torsion pendulum. The red curve represents the thermal noise of the torsion pendulum, while the blue curve illustrates the autocollimator background noise measured during the experiment. The carmine curve represents the estimated background noise of the torsion pendulum, obtained by integrating the thermal noise and autocollimator readout noise; it nearly coincided with the blue curve. Full article ">Figure 6
Integrated torsion pendulum as well as the internal TM and EH units. (A) The whole apparatus under experimentation. (B) The TM before integration. (C) The electrode housing under electronics testing. Full article ">Figure 7
The background noise curves of the torsion pendulum system. The blue line represents the estimated background noise as detailed in <a href="#sec3dot4-sensors-24-07816" class="html-sec">Section 3.4</a>. The cyan line depicts the actual measured background noise recorded from the apparatus during experiments. The red line illustrates a smoothed version of the background noise data from the torsion pendulum. Full article ">

26 pages, 8079 KiB

Open AccessArticle

Identification and Compensation Method of Unbalanced Error in Driving Chain for Rate-Integrating Hemispherical Resonator Gyro

by Yiwei Sun, Zhennan Wei, Guoxing Yi and Ning Wang

Sensors 2024, 24(13), 4328; https://doi.org/10.3390/s24134328 - 3 Jul 2024

Cited by 2 | Viewed by 1135

Abstract

The accuracy of the signal within a driving chain for the rate-integrating hemispherical resonator gyro (RI-HRG) plays a crucial role in the overall performance of the gyro. In this paper, a notable and effective method is proposed to realize the identification and compensation [...] Read more.

The accuracy of the signal within a driving chain for the rate-integrating hemispherical resonator gyro (RI-HRG) plays a crucial role in the overall performance of the gyro. In this paper, a notable and effective method is proposed to realize the identification and compensation of the unbalanced error in the driving chain for the RI-HRG that improved the performance of the multi-loop control applied in the RI-HRG. Firstly, the assembly inclination and eccentricity error of the hemispherical resonator, the inconsistent metal conductive film layer resistance error of the resonator, the coupling error of the driving chain, and the parameter inconsistency error of the circuit components were considered, and the impact of these errors on the multi-loop control applied in the RI-HRG were analyzed. On this basis, the impact was further summarized as the unbalanced error in the driving chain, which included the unbalanced gain error, equivalent misalignment angle, and unbalanced equivalent misalignment angle error. Then, a model between the unbalanced error in the driving chain and a non-ideal precession angular rate was established, which was applicable to both single channel asynchronous control and dual channel synchronous control of the RI-HRG. Further, an unbalanced error identification and compensation method is proposed by utilizing the RI-HRG output with the virtual precession control. Finally, the effectiveness of the proposed method was verified through simulation and experiments in kind. After error compensation, the zero-bias instability of the RI-HRG was improved from 3.0950°/h to 0.0511°/h. The results of experiments in kind demonstrated that the proposed method can effectively suppress the non-ideal angular rate output caused by the unbalanced error in the driving chain for the RI-HRG, thereby further improving the overall performance of the RI-HRG. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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12 pages, 2934 KiB

Open AccessArticle

Data Quality Assessment of Gravity Recovery and Climate Experiment Follow-On Accelerometer

by Zongpeng Pan and Yun Xiao

Sensors 2024, 24(13), 4286; https://doi.org/10.3390/s24134286 - 1 Jul 2024

Cited by 1 | Viewed by 834

Abstract

Accelerometers are mainly used to measure the non-conservative forces at the center of mass of gravity satellites and are the core payloads of gravity satellites. All kinds of disturbances in the satellite platform and the environment will affect the quality of the accelerometer [...] Read more.

Accelerometers are mainly used to measure the non-conservative forces at the center of mass of gravity satellites and are the core payloads of gravity satellites. All kinds of disturbances in the satellite platform and the environment will affect the quality of the accelerometer data. This paper focuses on the quality assessment of accelerometer data from the GRACE-FO satellites. Based on the ACC1A data, we focus on the analysis of accelerometer data anomalies caused by various types of disturbances in the satellite platform and environment, including thruster spikes, peaks, twangs, and magnetic torque disturbances. The data characteristics and data accuracy of the accelerometer in different operational states and satellite observation modes are analyzed using accelerometer observation data from different time periods. Finally, the data consistency of the accelerometer is analyzed using the accelerometer transplantation method. The results show that the amplitude spectral density of three-axis linear acceleration is better than the specified accuracy (above 10⁻¹ Hz) in the accelerometer’s nominal status. The results are helpful for understanding the characteristics and data accuracy of GRACE-FO accelerometer observations. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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15 pages, 6042 KiB

Open AccessArticle

A Ground-Based Electrostatically Suspended Accelerometer

by Hanxiao Liu, Xiaoxia He, Chenhui Wu and Rong Zhang

Sensors 2024, 24(12), 4029; https://doi.org/10.3390/s24124029 - 20 Jun 2024

Cited by 1 | Viewed by 802

Abstract

In this study, we have developed an electrostatically suspended accelerometer (ESA) specifically designed for ground use. To ensure sufficient overload capacity and minimize noise resulting from high suspension voltage, we introduced a proof mass design featuring a hollow, thin-walled cylinder with a thin [...] Read more.

In this study, we have developed an electrostatically suspended accelerometer (ESA) specifically designed for ground use. To ensure sufficient overload capacity and minimize noise resulting from high suspension voltage, we introduced a proof mass design featuring a hollow, thin-walled cylinder with a thin flange fixed at the center, offering the highest surface-area-to-mass ratio compared to various typical proof mass structures. Preload voltage is directly applied to the proof mass via a golden wire, effectively reducing the maximum supply voltage for suspension. The arrangement of suspension electrodes, offering five degrees of freedom and minimizing cross-talk, was designed to prioritize simplicity and maximize the utilization of electrode area for suspension purposes. The displacement detection and electrostatic suspension force were accurately modeled based on the structure. A controller incorporating an inverse winding mechanism was developed and simulated using Simulink. The simulation results unequivocally demonstrate the successful completion of the stable initial levitation process and suspension under

\pm 1 g

overload. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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26 pages, 8525 KiB

Open AccessArticle

Sensor Head Temperature Distribution Reconstruction of High-Precision Gravitational Reference Sensors with Machine Learning

by Zongchao Duan, Feilong Ren, Li-E Qiang, Keqi Qi and Haoyue Zhang

Sensors 2024, 24(8), 2529; https://doi.org/10.3390/s24082529 - 15 Apr 2024

Viewed by 1240

Abstract

Temperature fluctuations affect the performance of high-precision gravitational reference sensors. Due to the limited space and the complex interrelations among sensors, it is not feasible to directly measure the temperatures of sensor heads using temperature sensors. Hence, a high-accuracy interpolation method is essential [...] Read more.

Temperature fluctuations affect the performance of high-precision gravitational reference sensors. Due to the limited space and the complex interrelations among sensors, it is not feasible to directly measure the temperatures of sensor heads using temperature sensors. Hence, a high-accuracy interpolation method is essential for reconstructing the surface temperature of sensor heads. In this study, we utilized XGBoost-LSTM for sensor head temperature reconstruction, and we analyzed the performance of this method under two simulation scenarios: ground-based and on-orbit. The findings demonstrate that our method achieves a precision that is two orders of magnitude higher than that of conventional interpolation methods and one order of magnitude higher than that of a BP neural network. Additionally, it exhibits remarkable stability and robustness. The reconstruction accuracy of this method meets the requirements for the key payload temperature control precision specified by the Taiji Program, providing data support for subsequent tasks in thermal noise modeling and subtraction. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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11 pages, 3059 KiB

Open AccessCommunication

A Transportable Atomic Gravimeter with Constraint-Structured Active Vibration Isolation

by Chuanjing Ruan, Wei Zhuang, Jiamin Yao, Yang Zhao, Zenghan Ma, Cong Yi, Qin Tian, Shuqing Wu, Fang Fang and Yinghong Wen

Sensors 2024, 24(8), 2395; https://doi.org/10.3390/s24082395 - 9 Apr 2024

Cited by 2 | Viewed by 1218

Abstract

Many efforts have been taken in recent years to push atomic gravimeters toward practical applications. We demonstrate an atomic gravimeter named NIM-AGRb2 that is transportable and suitable for high-precision gravity measurements. Constraint-structured active vibration isolation (CS-AVI) is used to reduce the ground vibration [...] Read more.

Many efforts have been taken in recent years to push atomic gravimeters toward practical applications. We demonstrate an atomic gravimeter named NIM-AGRb2 that is transportable and suitable for high-precision gravity measurements. Constraint-structured active vibration isolation (CS-AVI) is used to reduce the ground vibration noise. The constraint structure in CS-AVI ensures that the isolation platform only has vertical translation, with all other degrees of freedom (DoFs) being constrained. Therefore, the stability of active vibration isolation is enhanced. With the implementation of CS-AVI, the sensitivity of NIM-AGRb2 reached as low as 20.5 μGal/Hz^1/2. The short-term sensitivity could be further reduced to 10.8 μGal/Hz^1/2 in a seismologic observation station. Moreover, we evaluated the system noise of the gravimeter, and the results were consistent with our observations. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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Figure 1
Schematic experimental setup of the atomic gravimeter. The top yellow sphere represents the 87Rb atoms that are trapped and cooled to 2 μK in the ground state <math display="inline"><semantics> <mrow> <mrow> <mo>|</mo> <mrow> <mi>F</mi> <mo>=</mo> <mn>2</mn> </mrow> <mo>〉</mo> </mrow> </mrow> </semantics></math> using a three-dimensional magneto-optical trap. Then, the atoms fall freely and are sequentially subjected to state preparation and atomic interference operations. Fluorescence detection is used to detect the final state atoms of <math display="inline"><semantics> <mrow> <mrow> <mo>|</mo> <mrow> <mi>F</mi> <mo>=</mo> <mn>1</mn> </mrow> <mo>〉</mo> </mrow> </mrow> </semantics></math> (blue sphere) and <math display="inline"><semantics> <mrow> <mrow> <mo>|</mo> <mrow> <mi>F</mi> <mo>=</mo> <mn>2</mn> </mrow> <mo>〉</mo> </mrow> </mrow> </semantics></math>. Full article ">Figure 2
Structure of the CS-AVI process. The solid framework is the top view of the passive vibration isolator and rods. The dashed framework represents the scheme to monitor the tilt of the vibration isolator. Full article ">Figure 3
Tilt drift of the passive isolation platform. Full article ">Figure 4
Gravity measurement results from the laboratory. (a) The measured gravity data and the residuals of gravity subtracted from the tide model. (b) The Allan standard deviation of the residuals in (a). The filled region indicates the confidence intervals of the points. The red dashed line corresponds to a sensitivity of 20.5 μGal/Hz1/2. Full article ">Figure 5
Allan standard deviation of gravity data in the seismic station. The filled region indicates the confidence intervals of the points. The blue and red dashed lines indicate short-term sensitivities of 33.1 μGal/Hz1/2 and 10.8 μGal/Hz1/2 under the two conditions in the legend, respectively. Full article ">Figure 6
Interference fringe of the atomic gravimeter for T = 105 ms. Each black dot corresponds to the transition probability obtained from a single measurement with a 1 s interval. The red curve represents the sinusoidal fitting of the fringe. The inset graph shows the results of sampling at the peak of the fringe for 600 s. Full article ">Figure 7
PSD of the phase noise of the Raman laser and reference signal. Full article ">Figure 8
PSD of the vibration noise. (a) The vibration noise sampled in the laboratory. (b) The vibration noise sampled in the seismic station. Full article ">

15 pages, 6268 KiB

Open AccessArticle

Research and Optimization of High-Performance Front-End Circuit Noise for Inertial Sensors

by Yuzhu Chen, Xin Liu, Longqi Wang, Tao Yu, Zhi Wang, Ke Xue, Yanlin Sui and Yongkun Chen

Sensors 2024, 24(3), 805; https://doi.org/10.3390/s24030805 - 26 Jan 2024

Cited by 2 | Viewed by 1370

Abstract

An inertial sensor is a crucial payload in China’s Taiji program for space gravitational wave detection. The performance of the capacitive displacement sensing circuit in the low-frequency band (0.1 mHz to 1 Hz) is extremely important because it directly determines the sensitivity of [...] Read more.

An inertial sensor is a crucial payload in China’s Taiji program for space gravitational wave detection. The performance of the capacitive displacement sensing circuit in the low-frequency band (0.1 mHz to 1 Hz) is extremely important because it directly determines the sensitivity of the space gravitational wave detection missions. Therefore, significant, yet challenging, tasks include decreasing the low-frequency noise in capacitive displacement sensing circuits and improving the capacitive sensing resolution. This study analyzes the noise characteristics of the pre-amplifier circuit within the capacitive sensing circuit, achieves precise tuning of the transformer bridge, and examines how transformer parameters affect noise. In addition, this study introduces a method using a discrete JFET to reduce the operational amplifier current noise and analyzes how feedback resistance and capacitance in TIA circuits affect the overall circuit noise. The proportional relationship between different transformer noises and TIA noise before and after optimization was analyzed and experimentally verified. Finally, an optimized TIA circuit and a superior transformer were utilized to achieve an increase in the capacitive sensing resolution from 1.095 aF/rtHz @ 10 mHz to 0.84 aF/rtHz @ 10 mHz, while improving the performance by 23%. These findings provide valuable insights into further decreasing circuit noise and increasing the capacitive sensing resolution. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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Review

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27 pages, 6483 KiB

Open AccessReview

Core Payload of the Space Gravitational Wave Observatory: Inertial Sensor and Its Critical Technologies

by Shaoxin Wang, Dongxu Liu, Xuan Zhan, Peng Dong, Jia Shen, Juan Wang, Ruihong Gao, Weichuan Guo, Peng Xu, Keqi Qi and Ziren Luo

Sensors 2024, 24(23), 7685; https://doi.org/10.3390/s24237685 - 30 Nov 2024

Viewed by 720

Abstract

Since Einstein’s prediction regarding the existence of gravitational waves was directly verified by the ground-based detector Advanced LIGO, research on gravitational wave detection has garnered increasing attention. To overcome limitations imposed by ground vibrations and interference at arm’s length, a space-based gravitational wave [...] Read more.

Since Einstein’s prediction regarding the existence of gravitational waves was directly verified by the ground-based detector Advanced LIGO, research on gravitational wave detection has garnered increasing attention. To overcome limitations imposed by ground vibrations and interference at arm’s length, a space-based gravitational wave detection initiative was proposed, which focuses on analyzing a large number of waves within the frequency range below 1 Hz. Due to the weak signal intensity, the TMs must move along their geodesic orbit with a residual acceleration less than 10⁻¹⁵ m/s²/Hz^1/2. Consequently, the core payload-inertial sensor was designed to shield against stray force noise while maintaining the high-precision motion of the test mass through a drag-free control system, providing an ultra-stable inertial reference for laser interferometry. To meet these requirements, the inertial sensor integrates a series of unit settings and innovative designs, involving numerous subsystems and technologies. This article provides a comprehensive overview of these critical technologies used in the development of inertial sensors for space gravitational wave detection and discusses future trends and potential applications for these sensors. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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21 pages, 2221 KiB

Open AccessReview

High-Precision Inertial Sensor Charge Management Based on Ultraviolet Discharge: A Comprehensive Review

by Tao Yu, Yuhua Wang, Yang Liu and Zhi Wang

Sensors 2023, 23(18), 7794; https://doi.org/10.3390/s23187794 - 11 Sep 2023

Cited by 4 | Viewed by 1835

Abstract

The charge accumulation caused by cosmic rays and solar energetic particles poses a significant challenge as a source of noise for inertial sensors used in space gravitational wave detection. To address this issue, the implementation of charge management systems based on ultraviolet discharge [...] Read more.

The charge accumulation caused by cosmic rays and solar energetic particles poses a significant challenge as a source of noise for inertial sensors used in space gravitational wave detection. To address this issue, the implementation of charge management systems based on ultraviolet discharge becomes crucial. This paper focuses on elucidating the principles and methods of using ultraviolet discharge for charge management in high-precision inertial sensors. Furthermore, it presents the design and implementation of relevant payloads. Through an analysis of the charge accumulation effect and its impact on noise, key considerations regarding coatings, light sources, and optical paths are explored, and some current and valuable insights into the future development of charge management systems are also summarized. The conclusions drawn from this research also provide guidance for the advancement of higher precision ultraviolet discharge technology and the design of charge management systems. Full article

(This article belongs to the Special Issue Advanced Inertial Sensors: Advances, Challenges and Applications)

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