Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244909
Y. Korkishko, V. Fedorov, S. Prilutskiy, D. Obuhovich, I. Fedorov, V. Prilutskiy, V. Ponomarev, A. Zuev, V. Varnakov, I. Morev, S. Kostritskii
At present time interferometric fiber-optic gyroscopes (IFOG, FOG) are widely used in inertial navigation systems (INS), and in wide range of applications have replaced its well-established main competitor ring laser gyroscopes (RLG). Recently, in order to cover the mass-market applications spectrum requiring low-cost and compact inertial sensor yet as much precise as it can be, RPC Optolink has launched new IFOG-based product: ultra-compact navigation-grade inertial measurement unit IMU400, its SWaP properties are: 80×95×62 mm, 0.7 kg, 0.5 l, ≤7 W. The aim of the current work was the production of IMU400 devices batches first, and then estimation of IMU 2019–2020 batches performance with direct approach and also with strapdown inertial navigation system (SINS) simulation methods, which is indirect way of performance observation, by its sense. Main IMU400 Gyro (FOG) and Accelerometer (ACC) parameters are: Angle Random Walk (ARW) = 0.007 °/√hour, Bias Instability (BI) = 0.01°/h; Velocity Random Walk (VRW) = 40μg/√Hz, BI = 6μg. SINS performance (best): heading 0.2°×sec(lat) (1σ, 10 min alignment time).
目前，干涉式光纤陀螺仪(IFOG, FOG)在惯性导航系统(INS)中得到了广泛的应用，并取代了其主要竞争对手环形激光陀螺仪(RLG)。最近，为了覆盖需要低成本和紧凑的惯性传感器的大众市场应用频谱，RPC Optolink推出了新的基于ifog的产品:超紧凑导航级惯性测量单元IMU400，其SWaP特性为:80×95×62 mm, 0.7 kg, 0.5 l，≤7 W。本研究的目的是先批量生产IMU400器件，然后采用直接方法和捷联惯导系统(SINS)仿真方法对imu2019 - 2020批次进行性能估计，这是一种间接的性能观测方法。IMU400陀螺仪(FOG)和加速度计(ACC)的主要参数为:角度随机游走(ARW) = 0.007°/√h，偏置不稳定性(BI) = 0.01°/h;速度随机游走(Velocity Random Walk, VRW) = 40μg/√Hz, BI = 6μg。捷联惯导系统性能(最佳):航向0.2°×sec(后期)(1σ，对准时间10分钟)。
{"title":"Compact near-navigation-grade IFOG inertial measurement unit IMU400","authors":"Y. Korkishko, V. Fedorov, S. Prilutskiy, D. Obuhovich, I. Fedorov, V. Prilutskiy, V. Ponomarev, A. Zuev, V. Varnakov, I. Morev, S. Kostritskii","doi":"10.1109/ISS50053.2020.9244909","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244909","url":null,"abstract":"At present time interferometric fiber-optic gyroscopes (IFOG, FOG) are widely used in inertial navigation systems (INS), and in wide range of applications have replaced its well-established main competitor ring laser gyroscopes (RLG). Recently, in order to cover the mass-market applications spectrum requiring low-cost and compact inertial sensor yet as much precise as it can be, RPC Optolink has launched new IFOG-based product: ultra-compact navigation-grade inertial measurement unit IMU400, its SWaP properties are: 80×95×62 mm, 0.7 kg, 0.5 l, ≤7 W. The aim of the current work was the production of IMU400 devices batches first, and then estimation of IMU 2019–2020 batches performance with direct approach and also with strapdown inertial navigation system (SINS) simulation methods, which is indirect way of performance observation, by its sense. Main IMU400 Gyro (FOG) and Accelerometer (ACC) parameters are: Angle Random Walk (ARW) = 0.007 °/√hour, Bias Instability (BI) = 0.01°/h; Velocity Random Walk (VRW) = 40μg/√Hz, BI = 6μg. SINS performance (best): heading 0.2°×sec(lat) (1σ, 10 min alignment time).","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124504239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244913
A. Taranta, A. Gillooly, V. Kopp, D. Neugroschl, M. Ibsen, C. Emslie, J. Sahu
The sensitivity of an interferometric fiber optic gyroscope (IFOG) scales with the length of the sensing optical path. Thus, IFOG development history has seen much work devoted to shrinking ever-increasing lengths of optical fiber into a fixed volume. Indeed, the success of the IFOG as a guidance and navigation technology is founded, to a large extent, on the many advancements in fiber-optics which were required to compact numerous state-of-the-art components – including a multi-kilometer length of optical fiber – to within the size of a teacup.An exciting technology which promises to continue this trend is multicore optical fiber, in which multiple, independent optical waveguides (cores) are placed within the same glass cladding which would ordinarily contain only one core. The dense arrangement of cores in such fibers can be exploited in an IFOG by connecting them in series, and thereby increasing the instrument sensitivity proportionally. As originally proposed by Bergh [1], these features present an opportunity to increase sensitivity while reducing the sensor footprint and simplifying the optical fiber coil - a key driver of cost and complexity in IFOGs.Here we detail performance characteristics of an all-fiber multicore IFOG employing a bend-insensitive, single-mode, 7-core fiber in the sensing coil. Like the recent, first-ever demonstration by Mitani et al. [2], [3], we employ an open-loop testbed architecture with a depolarized sensing loop, in which fiber cores are connected in series via a pair of multicore fan-in/fan-out devices. Here however, the fan-in/fan-out components are tapered fiber devices, packaged in conventional fiber-optic component sleeves, and with the core interconnections made via standard fusion splices [4]. Measurements of noise and long-term stability of the instrument show that its performance is commensurate with the 7X enhanced sensitivity afforded by the optical path length increase. For this 7-core, 154 m long, 10 cm diameter fiber coil, we show long-term gyro bias stability under 0.02 deg/hr and angle random walk of $2.4, text{mdeg} /sqrt {text{hr}}$. This compares favorably with both noise models and performance measurements in IFOGs of similar scale factor, thus confirming the sensitivity improvement conferred by use of 7-core fiber.The all-fiber configuration of the sensing loop makes this instrument highly practicable as a drop-in replacement for current IFOGs, with no change to existing front-end designs. Moreover, as multicore fiber technology continues to push the frontiers of optical fiber transmission capacity, future designs may benefit from even greater core multiplicity – an exciting prospect for the next generation of compact, low-cost, high-accuracy IFOGs.
{"title":"Performance Characteristics of a Multicore Interferometric Fiber Optic Gyroscope Using a 7-Core Fiber","authors":"A. Taranta, A. Gillooly, V. Kopp, D. Neugroschl, M. Ibsen, C. Emslie, J. Sahu","doi":"10.1109/ISS50053.2020.9244913","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244913","url":null,"abstract":"The sensitivity of an interferometric fiber optic gyroscope (IFOG) scales with the length of the sensing optical path. Thus, IFOG development history has seen much work devoted to shrinking ever-increasing lengths of optical fiber into a fixed volume. Indeed, the success of the IFOG as a guidance and navigation technology is founded, to a large extent, on the many advancements in fiber-optics which were required to compact numerous state-of-the-art components – including a multi-kilometer length of optical fiber – to within the size of a teacup.An exciting technology which promises to continue this trend is multicore optical fiber, in which multiple, independent optical waveguides (cores) are placed within the same glass cladding which would ordinarily contain only one core. The dense arrangement of cores in such fibers can be exploited in an IFOG by connecting them in series, and thereby increasing the instrument sensitivity proportionally. As originally proposed by Bergh [1], these features present an opportunity to increase sensitivity while reducing the sensor footprint and simplifying the optical fiber coil - a key driver of cost and complexity in IFOGs.Here we detail performance characteristics of an all-fiber multicore IFOG employing a bend-insensitive, single-mode, 7-core fiber in the sensing coil. Like the recent, first-ever demonstration by Mitani et al. [2], [3], we employ an open-loop testbed architecture with a depolarized sensing loop, in which fiber cores are connected in series via a pair of multicore fan-in/fan-out devices. Here however, the fan-in/fan-out components are tapered fiber devices, packaged in conventional fiber-optic component sleeves, and with the core interconnections made via standard fusion splices [4]. Measurements of noise and long-term stability of the instrument show that its performance is commensurate with the 7X enhanced sensitivity afforded by the optical path length increase. For this 7-core, 154 m long, 10 cm diameter fiber coil, we show long-term gyro bias stability under 0.02 deg/hr and angle random walk of $2.4, text{mdeg} /sqrt {text{hr}}$. This compares favorably with both noise models and performance measurements in IFOGs of similar scale factor, thus confirming the sensitivity improvement conferred by use of 7-core fiber.The all-fiber configuration of the sensing loop makes this instrument highly practicable as a drop-in replacement for current IFOGs, with no change to existing front-end designs. Moreover, as multicore fiber technology continues to push the frontiers of optical fiber transmission capacity, future designs may benefit from even greater core multiplicity – an exciting prospect for the next generation of compact, low-cost, high-accuracy IFOGs.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133175571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244889
W. Huang, Y. X. Liu, Y. He, L. Huo, X. Wang, W. Wang
Systematic errors resulting from differential alkali field, electric quadrupole interactions are the keys to the long-term stability of the nuclear magnetic resonance (NMR) gyros. In this paper, we review the basic theory governing spin-exchange pumped NMR gyros, and a simple model analyzing the influences of vapor cell’s temperature characteristics on the bias and noise is presented. We discuss how temperature characteristics (temperature drift and temperature gradient) limit the bias stability theoretically, and methods to minimize them. To validate the theoretical analysis, a NMR gyro with dual species operation is set up. The precession signals for the two isotopes are phase-closed to the drive waveforms for the nuclear magnetic resonance by adjusting the drive frequency. The result shows that temperature drift may introduce uncontrolled systematic errors, which are indistinguishable from actual rotations. Imperfect temperature stabilization set the ultimate limit of precision for the NMR gyro. The low frequency magnetic noise can be suppressed by static field stabilization control. However, the phase delay induced by Rb magnetometer and the differential alkali field are also the main source of the bias. Additionally, imperfect measurement of the NMR phase introduced by temperature gradient may be a significant contributor of noise.
{"title":"The influences of cell’s temperature characteristic on the performance of nuclear magnetic resonance gyroscope","authors":"W. Huang, Y. X. Liu, Y. He, L. Huo, X. Wang, W. Wang","doi":"10.1109/ISS50053.2020.9244889","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244889","url":null,"abstract":"Systematic errors resulting from differential alkali field, electric quadrupole interactions are the keys to the long-term stability of the nuclear magnetic resonance (NMR) gyros. In this paper, we review the basic theory governing spin-exchange pumped NMR gyros, and a simple model analyzing the influences of vapor cell’s temperature characteristics on the bias and noise is presented. We discuss how temperature characteristics (temperature drift and temperature gradient) limit the bias stability theoretically, and methods to minimize them. To validate the theoretical analysis, a NMR gyro with dual species operation is set up. The precession signals for the two isotopes are phase-closed to the drive waveforms for the nuclear magnetic resonance by adjusting the drive frequency. The result shows that temperature drift may introduce uncontrolled systematic errors, which are indistinguishable from actual rotations. Imperfect temperature stabilization set the ultimate limit of precision for the NMR gyro. The low frequency magnetic noise can be suppressed by static field stabilization control. However, the phase delay induced by Rb magnetometer and the differential alkali field are also the main source of the bias. Additionally, imperfect measurement of the NMR phase introduced by temperature gradient may be a significant contributor of noise.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126043725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244897
M. Zhu, Y. Wu, S. Luo
Foot-mounted inertial sensors become popular in many indoor or GPS-denied applications, including but not limited to medical monitoring, gait analysis, soldier and first responder positioning. However, the foot-mounted inertial navigation relies largely on the aid of Zero Velocity Update (ZUPT) and has encountered inherent problems such as heading drift. This paper implements a pedestrian navigation system based on dual foot-mounted low-cost inertial measurement units (IMU) and inter-foot ultrasonic ranging. The global observability analysis of the system is performed to investigate the roles of the foot-to-foot ranging measurement in improving the state estimability. A Kalman-based estimation algorithm is mechanized in the Earth frame, rather than in the common local-level frame, which is found to be effective in depressing the linearization error in Kalman filtering. An ellipsoid constraint in the Earth frame is also proposed to further restrict the height drift. Simulation and real field experiments show that the proposed method has better robustness and positioning accuracy (about 0.1–0.2% travelled distance) than the traditional pedestrian navigation schemes do.
{"title":"A Pedestrian Navigation System by Low-cost Dual Foot-Mounted IMUs and Inter-foot Ranging","authors":"M. Zhu, Y. Wu, S. Luo","doi":"10.1109/ISS50053.2020.9244897","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244897","url":null,"abstract":"Foot-mounted inertial sensors become popular in many indoor or GPS-denied applications, including but not limited to medical monitoring, gait analysis, soldier and first responder positioning. However, the foot-mounted inertial navigation relies largely on the aid of Zero Velocity Update (ZUPT) and has encountered inherent problems such as heading drift. This paper implements a pedestrian navigation system based on dual foot-mounted low-cost inertial measurement units (IMU) and inter-foot ultrasonic ranging. The global observability analysis of the system is performed to investigate the roles of the foot-to-foot ranging measurement in improving the state estimability. A Kalman-based estimation algorithm is mechanized in the Earth frame, rather than in the common local-level frame, which is found to be effective in depressing the linearization error in Kalman filtering. An ellipsoid constraint in the Earth frame is also proposed to further restrict the height drift. Simulation and real field experiments show that the proposed method has better robustness and positioning accuracy (about 0.1–0.2% travelled distance) than the traditional pedestrian navigation schemes do.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"165 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114647225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244890
M. Verola, R. Senatore, E. Quatraro, A. Piccinino, A. Moretti, A. Pizzarulli, M. Perlmutter
Operations in high dynamic environments, in presence of strong vibrations and extreme mechanical shocks, may represent a big challenge for a high-performance Inertial Measurement Unit to maintain its accuracy, availability and continuity at the required level. When designing the IMU, several aspects must be considered and corresponding actions must be taken to avoid IMU unavailability, aimed to mitigate undesirable effects during high dynamic transients, such as sensor’s bias drifts due to rectification errors or saturations due to input forces out of specified sensors’ measurement range.In case of vibrations, typically damping systems are adopted to decrease the energy reaching the IMU sensors, however, sometime the proper design or selection of components can be definitely complex, and furthermore actions taken to mitigate vibration effects can even produce amplifications in case of mechanical shock pulses, depending on the frequency response of the employed dampers. In general, high accuracy accelerometers have limited dynamic range, so undesirable out-of-range effects can be experienced in certain high dynamic transients, limiting their usability in harsh high-g demanding operational scenarios.More sophisticated design techniques, like the adoption of a sensors’ skewed redundant architecture, can be used to overcome some of these limitations, however, they have some drawbacks: increase of costs, mechanical complexity, increased system dimensions, together with the need to adopt a more complex IMU calibration process.This paper proposes a simple technique and system architecture to extend the measurement range of high accuracy IMUs, when its accelerometers have to deal with both high vibration and high-g shock environments, reducing the overall effort in designing tasks and the overall IMU bill of materials cost, avoiding complex mechanical architectures and damping systems, and guaranteeing the continuity and availability of the IMU acceleration measurements even in presence of over-range conditions for the most accurate sensor devices. This goal is achieved by adopting a cost effective IMU architecture that employs hybrid redundant sensors of different technologies, and a data fusion technique of high-accuracy, limited-range sensors, together with less expensive, lower-accuracy and broad-dynamic-range sensors.
{"title":"IMU Architecture based on Functional Redundancy to improve Safety Features and Measurements Availability during Highly Dynamic Transients","authors":"M. Verola, R. Senatore, E. Quatraro, A. Piccinino, A. Moretti, A. Pizzarulli, M. Perlmutter","doi":"10.1109/ISS50053.2020.9244890","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244890","url":null,"abstract":"Operations in high dynamic environments, in presence of strong vibrations and extreme mechanical shocks, may represent a big challenge for a high-performance Inertial Measurement Unit to maintain its accuracy, availability and continuity at the required level. When designing the IMU, several aspects must be considered and corresponding actions must be taken to avoid IMU unavailability, aimed to mitigate undesirable effects during high dynamic transients, such as sensor’s bias drifts due to rectification errors or saturations due to input forces out of specified sensors’ measurement range.In case of vibrations, typically damping systems are adopted to decrease the energy reaching the IMU sensors, however, sometime the proper design or selection of components can be definitely complex, and furthermore actions taken to mitigate vibration effects can even produce amplifications in case of mechanical shock pulses, depending on the frequency response of the employed dampers. In general, high accuracy accelerometers have limited dynamic range, so undesirable out-of-range effects can be experienced in certain high dynamic transients, limiting their usability in harsh high-g demanding operational scenarios.More sophisticated design techniques, like the adoption of a sensors’ skewed redundant architecture, can be used to overcome some of these limitations, however, they have some drawbacks: increase of costs, mechanical complexity, increased system dimensions, together with the need to adopt a more complex IMU calibration process.This paper proposes a simple technique and system architecture to extend the measurement range of high accuracy IMUs, when its accelerometers have to deal with both high vibration and high-g shock environments, reducing the overall effort in designing tasks and the overall IMU bill of materials cost, avoiding complex mechanical architectures and damping systems, and guaranteeing the continuity and availability of the IMU acceleration measurements even in presence of over-range conditions for the most accurate sensor devices. This goal is achieved by adopting a cost effective IMU architecture that employs hybrid redundant sensors of different technologies, and a data fusion technique of high-accuracy, limited-range sensors, together with less expensive, lower-accuracy and broad-dynamic-range sensors.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115176239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244916
Fabrício Saggin, A. Korniienko, G. Papin, E. Markiewicz, Y. David, A. E. Hajj, G. Scorletti
In this work, we propose a systematic and flexible method for designing the electronic filter of electro-mechanical ΣΔ (EM-ΣΔ) feedbacks, widely used for the closed-loop operation of high-performance MEMS gyroscopes. We formulate the filter design as an optimization problem based on the H∞ norm of weighted closed-loop transfer functions with an appropriate H∞ criterion. The desired closed-loop system specifications are then expressed through weighting filters, which can be chosen by the system designer. Practical implementations demonstrate the effectiveness of our method. When compared to the results of an established filter, we obtain performance improvements of 30% for the scale factor nonlinearity, 40% for the RMS noise, 35% for the angle-random walk, to cite a few.
{"title":"H∞ Design of an EM-ΣΔ Feedback for MEMS Gyroscopes","authors":"Fabrício Saggin, A. Korniienko, G. Papin, E. Markiewicz, Y. David, A. E. Hajj, G. Scorletti","doi":"10.1109/ISS50053.2020.9244916","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244916","url":null,"abstract":"In this work, we propose a systematic and flexible method for designing the electronic filter of electro-mechanical ΣΔ (EM-ΣΔ) feedbacks, widely used for the closed-loop operation of high-performance MEMS gyroscopes. We formulate the filter design as an optimization problem based on the H∞ norm of weighted closed-loop transfer functions with an appropriate H∞ criterion. The desired closed-loop system specifications are then expressed through weighting filters, which can be chosen by the system designer. Practical implementations demonstrate the effectiveness of our method. When compared to the results of an established filter, we obtain performance improvements of 30% for the scale factor nonlinearity, 40% for the RMS noise, 35% for the angle-random walk, to cite a few.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128220403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244822
T. Martin
This paper deals with the tight integration of Inertial Measurement Units (IMU), Global Navigation Satellite Systems (GNSS) and the concept of Advanced Receiver Autonomous Integrity Monitoring (ARAIM). While the integration of an IMU and GNSS to an integrated GNSS/Inertial system is well known and widespread, the use of the ARAIM concept in inertial systems is a new and promising approach. In safety critical applications such as aviation, GNSS receivers as well as integrated GNSS/Inertial systems have to be equipped with a Fault Detection and Exclusion (FDE) function. Single frequency L1 GPS receivers with Receiver Autonomous Integrity Monitoring (RAIM) were the answer for decades. The second generation of GNSS offers more satellite systems and more frequencies for navigation. The visibility and accuracy of Multi-Frequency and Multi- Constellation (MFMC) receivers are significantly improved. ARAIM transfers these improvements into aviation. MFMC receivers with ARAIM can provide protection levels for challenging Alert Limits, for instance VAL = 35 m, with reasonable availability. Therefore, ARAIM has the potential for LPV-200 (Localizer performance with vertical guidance, decision height 200 feet) approaches. By including an IMU, it is possible to increase this potential. The added value of using an IMU and the difficulties of integration are hardly mentioned in literature. ARAIM ensures integrity by comparing the GNSS position solution with all satellites in view to solutions of subsets (fault-tolerant solutions) that exclude certain satellites. A transfer of this concept into a tightly integrated GNSS/Inertial system seems straightforward – replace the GNSS position solutions and subsets by integrated GNSS/Inertial position and subsets. On the other hand, ARAIM needs to evaluate hundreds of subsets, which creates a considerable computational load, especially in the case of GNSS/Inertial integration. A challenge for GNSS/Inertial designs is the ARAIM specific ranging model, which includes ranging bias, accuracy and integrity. Carrier smoothed ranges are used in ARAIM. These smoothed signals contradict an optimal GNSS/Inertial integration. In addition, the integration design has to consider time correlations of ranging signals, neglectable for ARAIM. In this paper, we address the mentioned design issues of a tight GNSS/Inertial integration, which uses the concept of ARAIM. We also describe our simulation procedure to determine availability. The availability serves as performance measure for the integration designs. Benefits and effects of reducing the number of subsets, interpretation and implementation of ranging model, correlation time constants, as well as different IMU classes are investigated by means of simulation results.
{"title":"Advanced Receiver Autonomous Integrity Monitoring in Tightly Integrated GNSS/Inertial Systems","authors":"T. Martin","doi":"10.1109/ISS50053.2020.9244822","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244822","url":null,"abstract":"This paper deals with the tight integration of Inertial Measurement Units (IMU), Global Navigation Satellite Systems (GNSS) and the concept of Advanced Receiver Autonomous Integrity Monitoring (ARAIM). While the integration of an IMU and GNSS to an integrated GNSS/Inertial system is well known and widespread, the use of the ARAIM concept in inertial systems is a new and promising approach. In safety critical applications such as aviation, GNSS receivers as well as integrated GNSS/Inertial systems have to be equipped with a Fault Detection and Exclusion (FDE) function. Single frequency L1 GPS receivers with Receiver Autonomous Integrity Monitoring (RAIM) were the answer for decades. The second generation of GNSS offers more satellite systems and more frequencies for navigation. The visibility and accuracy of Multi-Frequency and Multi- Constellation (MFMC) receivers are significantly improved. ARAIM transfers these improvements into aviation. MFMC receivers with ARAIM can provide protection levels for challenging Alert Limits, for instance VAL = 35 m, with reasonable availability. Therefore, ARAIM has the potential for LPV-200 (Localizer performance with vertical guidance, decision height 200 feet) approaches. By including an IMU, it is possible to increase this potential. The added value of using an IMU and the difficulties of integration are hardly mentioned in literature. ARAIM ensures integrity by comparing the GNSS position solution with all satellites in view to solutions of subsets (fault-tolerant solutions) that exclude certain satellites. A transfer of this concept into a tightly integrated GNSS/Inertial system seems straightforward – replace the GNSS position solutions and subsets by integrated GNSS/Inertial position and subsets. On the other hand, ARAIM needs to evaluate hundreds of subsets, which creates a considerable computational load, especially in the case of GNSS/Inertial integration. A challenge for GNSS/Inertial designs is the ARAIM specific ranging model, which includes ranging bias, accuracy and integrity. Carrier smoothed ranges are used in ARAIM. These smoothed signals contradict an optimal GNSS/Inertial integration. In addition, the integration design has to consider time correlations of ranging signals, neglectable for ARAIM. In this paper, we address the mentioned design issues of a tight GNSS/Inertial integration, which uses the concept of ARAIM. We also describe our simulation procedure to determine availability. The availability serves as performance measure for the integration designs. Benefits and effects of reducing the number of subsets, interpretation and implementation of ranging model, correlation time constants, as well as different IMU classes are investigated by means of simulation results.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124337672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244915
R. Holm, H. Petersen, S. Normann, H. Schou, M. Horntvedt, M. Hage, S. Martinsen
Since 2009, more than 35,000 of Sensonor’s STIM gyro modules and IMUs have been shipped to customers across many applications in defense and commercial markets. The STIM gyro modules and IMUs are based on a proven gyro design that originally came from the automotive safety segment.There is a growing interest for using the same technology in high-g applications, mostly driven by artillery shells and artillery launched guided ammunitions, often referred to as smart munitions. A common requirement for this is 20,000g survival of the MEMS structure as well as measurement capability up to 10,000°/s. Additionally, the European defense industry has raised concerns regarding the lack of an all-European solution available in the market. Similar concerns have also been voiced by the European Defence Agency (EDA).In order to investigate whether Sensonor’s current gyro could be a candidate for these applications, finite-element modeling (FEM) has been performed with static load of 20,000g. Further, static high-g testing has been performed at 20,000, 25,000 and 30,000g exposing the gyro to high-g forces in all 6 directions. Finally, shock-tests up to 21,300g have been performed, again in all 6 directions. In total 168 gyro dies have been used in the various tests. This paper summarizes the analysis and tests performed and concludes that Sensonor’s gyro indeed is a candidate for high-g applications.
{"title":"High–g (20,000g+) testing of an existing tactical grade gyro design","authors":"R. Holm, H. Petersen, S. Normann, H. Schou, M. Horntvedt, M. Hage, S. Martinsen","doi":"10.1109/ISS50053.2020.9244915","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244915","url":null,"abstract":"Since 2009, more than 35,000 of Sensonor’s STIM gyro modules and IMUs have been shipped to customers across many applications in defense and commercial markets. The STIM gyro modules and IMUs are based on a proven gyro design that originally came from the automotive safety segment.There is a growing interest for using the same technology in high-g applications, mostly driven by artillery shells and artillery launched guided ammunitions, often referred to as smart munitions. A common requirement for this is 20,000g survival of the MEMS structure as well as measurement capability up to 10,000°/s. Additionally, the European defense industry has raised concerns regarding the lack of an all-European solution available in the market. Similar concerns have also been voiced by the European Defence Agency (EDA).In order to investigate whether Sensonor’s current gyro could be a candidate for these applications, finite-element modeling (FEM) has been performed with static load of 20,000g. Further, static high-g testing has been performed at 20,000, 25,000 and 30,000g exposing the gyro to high-g forces in all 6 directions. Finally, shock-tests up to 21,300g have been performed, again in all 6 directions. In total 168 gyro dies have been used in the various tests. This paper summarizes the analysis and tests performed and concludes that Sensonor’s gyro indeed is a candidate for high-g applications.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131401192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244885
W. Hong, S. Lou, B. Huang, P. Zhang, Y. Ma, Y. Li, X. Hu, M. Wang, C. Ding
With the maturity of slim diameter polarization-maintaining fiber and correlational optical devices, miniaturized interferometric fiber optic gyroscope (MIFOG) developed rapidly, MIFOG has strengthened its lead in tactical and navigation grade, while squeezed the market of ring laser gyroscope (RLG) and MEMS gyroscope. It has obvious advantages in the fields of navigation, attitude control and even civil autonomous driving in the future.Electrical crosstalk is regarded as the most significant factor influencing dead zone, bias error and noise in MIFOG. Studies have shown that circuit filter, isolation structure and multistate modulation can greatly reduce the crosstalk. However, there are many problems in the design and production of MIFOG: the circuit board is too small to use effective filtering measures; the existence of the spatial reflection paths makes the crosstalk control more difficult; the structure is limited by space and cannot be effectively isolated; the limitation of the fiber ring length makes it impossible to use complex multistate modulation.In this paper, an electrical crosstalk error suppression method based on multipoint reset modulation (MRM) is proposed. The mathematical model of the influence of electrical crosstalk on fiber optic gyroscope is established. The electrical crosstalk errors under single point reset (SRM) and MRM are analyzed through simulation and test. The results show that the electrical crosstalk errors under MRM reset can be reduced by more than 20% compared with SRM reset at a modulation depth of 2π/3. Furthermore, the crosstalk of MRM diminishes as the modulation depth increases, and it accords with the theory of signal-to-noise ratio (SNR) that needs modulation depth close to π to suppress the excess relative intensity noise (RIN) of the light source. The research in this paper is of great significance to the performance improvement of the MIFOG.
{"title":"Multipoint reset modulation for reduced crosstalk in a miniaturized fiber optic gyroscope","authors":"W. Hong, S. Lou, B. Huang, P. Zhang, Y. Ma, Y. Li, X. Hu, M. Wang, C. Ding","doi":"10.1109/ISS50053.2020.9244885","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244885","url":null,"abstract":"With the maturity of slim diameter polarization-maintaining fiber and correlational optical devices, miniaturized interferometric fiber optic gyroscope (MIFOG) developed rapidly, MIFOG has strengthened its lead in tactical and navigation grade, while squeezed the market of ring laser gyroscope (RLG) and MEMS gyroscope. It has obvious advantages in the fields of navigation, attitude control and even civil autonomous driving in the future.Electrical crosstalk is regarded as the most significant factor influencing dead zone, bias error and noise in MIFOG. Studies have shown that circuit filter, isolation structure and multistate modulation can greatly reduce the crosstalk. However, there are many problems in the design and production of MIFOG: the circuit board is too small to use effective filtering measures; the existence of the spatial reflection paths makes the crosstalk control more difficult; the structure is limited by space and cannot be effectively isolated; the limitation of the fiber ring length makes it impossible to use complex multistate modulation.In this paper, an electrical crosstalk error suppression method based on multipoint reset modulation (MRM) is proposed. The mathematical model of the influence of electrical crosstalk on fiber optic gyroscope is established. The electrical crosstalk errors under single point reset (SRM) and MRM are analyzed through simulation and test. The results show that the electrical crosstalk errors under MRM reset can be reduced by more than 20% compared with SRM reset at a modulation depth of 2π/3. Furthermore, the crosstalk of MRM diminishes as the modulation depth increases, and it accords with the theory of signal-to-noise ratio (SNR) that needs modulation depth close to π to suppress the excess relative intensity noise (RIN) of the light source. The research in this paper is of great significance to the performance improvement of the MIFOG.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129860199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-15DOI: 10.1109/ISS50053.2020.9244906
Ch.-Sh. Jao, K. Stewart, J. Conradt, E. Neftci, A. Shkel
In this paper, we proposed a novel zero velocity detector, the Dynamic-Vision-Sensor (DVS)-aided Stance Phase Optimal dEtection (SHOE) detector, for Zero-velocity-UPdaTe (ZUPT)-aided Inertial Navigation Systems (INS) augmented by a foot-mounted event-based camera DVS128. We observed that the firing rate of the DVS consistently increased during the swing phase and decreased during the stance phase in indoor walking experiments. We experimentally determined that the optimal placement configuration for zero-velocity detection is to mount the DVS next to an Inertial Measurement Unit (IMU) and face the sensor outward. The DVS-SHOE detector was derived in a General Likelihood Ratio Test (GLRT) framework, combining statistics of the conventional SHOE detector and the DVS firing rate. This paper used two methods to evaluate the proposed DVS-SHOE detector. First, we compared the detection performances of the SHOE detector and the DVS-SHOE detector. The experimental results showed that the DVS-SHOE detector achieved a lower false alarm rate than the SHOE detector. Second, we compared the navigation performance of the ZUPT-aided INS using the SHOE detector and the DVS detector. The experimental results showed that the Circular Error Probable (CEP) of the case using DVS-SHOE was reduced by around 25 % from 1.2 m to 0.9 m, as compared to the case of the SHOE detector.
{"title":"Zero Velocity Detector for Foot-mounted Inertial Navigation System Assisted by a Dynamic Vision Sensor","authors":"Ch.-Sh. Jao, K. Stewart, J. Conradt, E. Neftci, A. Shkel","doi":"10.1109/ISS50053.2020.9244906","DOIUrl":"https://doi.org/10.1109/ISS50053.2020.9244906","url":null,"abstract":"In this paper, we proposed a novel zero velocity detector, the Dynamic-Vision-Sensor (DVS)-aided Stance Phase Optimal dEtection (SHOE) detector, for Zero-velocity-UPdaTe (ZUPT)-aided Inertial Navigation Systems (INS) augmented by a foot-mounted event-based camera DVS128. We observed that the firing rate of the DVS consistently increased during the swing phase and decreased during the stance phase in indoor walking experiments. We experimentally determined that the optimal placement configuration for zero-velocity detection is to mount the DVS next to an Inertial Measurement Unit (IMU) and face the sensor outward. The DVS-SHOE detector was derived in a General Likelihood Ratio Test (GLRT) framework, combining statistics of the conventional SHOE detector and the DVS firing rate. This paper used two methods to evaluate the proposed DVS-SHOE detector. First, we compared the detection performances of the SHOE detector and the DVS-SHOE detector. The experimental results showed that the DVS-SHOE detector achieved a lower false alarm rate than the SHOE detector. Second, we compared the navigation performance of the ZUPT-aided INS using the SHOE detector and the DVS detector. The experimental results showed that the Circular Error Probable (CEP) of the case using DVS-SHOE was reduced by around 25 % from 1.2 m to 0.9 m, as compared to the case of the SHOE detector.","PeriodicalId":118518,"journal":{"name":"2020 DGON Inertial Sensors and Systems (ISS)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130459523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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