inertial measurements
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2022 ◽  
Author(s):  
Laura Piho ◽  
Andreas Alexander ◽  
Maarja Kruusmaa

Abstract. Glacier hydrology describes water movement over, through and under glaciers and ice sheets. Water reaching the ice bed influences ice motion and ice dynamical models, therefore requiring a good understanding of glacier hydrology, particularly water pressures and pathways. However, as in situ observations are sparse and methods for direct observations of water pathways and internal pressures are lacking, our understanding of the aforementioned pathways and pressure remains limited. Here, we present a method that allows the reconstruction of planar subsurface water flow paths and spatially reference water pressures. We showcase this method by reconstructing the 2D topology and the water pressure distribution of an englacial channel in Austre Brøggerbreen (Svalbard). The approach uses inertial measurements from submersible sensing drifters and reconstructs the flow path between given start and end coordinates. Validation on a supraglacial channel shows an average length error of 3.9 m (5.3 %). At the englacial channel, the average length error is 107 m (11.6 %) and the average pressure error 3.4 hPa (0.3 %). Our method allows mapping sub- and englacial flow paths and the pressure distribution within, thereby facilitating hydrological model validation. Further, our method also allows the reconstruction of other, previously unexplored, subsurface fluid flow paths.


Author(s):  
Alexander A. Afonin ◽  
◽  
Andrey S. Sulakov ◽  
M.S. Maamo ◽  
◽  
...  

Nowadays, high-precision measurement of aircraft vibration parameters during its main operations modes, including in-flight operation mode, is still considered an important scientific and technical field of study and research. These kinds of measurements are usually conducted in order to analyze the airplane vibration properties and characteristics, which serves in diagnosing the state of its structure, predicting the appearance and development of defects and deformations, as well as to prevent or avoid the influence of dangerous phenomena such as flutter, buffeting, etc. In this article, the authors present the primary results of their work to build a system designed to measure such airplane vibration parameters. In comparison with the existing analogous systems, the new proposed system makes use of traditional vibrometric measurement methods in combination with approaches typical for solving orientation and navigation problems. So, the article discusses the principles of constructing a measurement system of vibration parameters of aircraft structural elements using the example of a system for measuring aircraft wing vibrations using MEMS IMU units and data fusion technology. A brief review of the main existing solutions in this research field is carried out, and the relevance and expediency of the proposed version of the system is substantiated. The basic components and structure of the proposed system are presented, including MEMS IMU units, a displacement sensor, and an onboard navigation system. The basic principles of the system operation are described based on the use of data from the displacement sensor, inertial measurements and optimal Kalman estimation. The main algorithms for the system operation are presented, including algorithms for inertial measurements, estimation and correction, as well as the actual algorithm for calculating vibration parameters. In addition, the mathematical errors models of the main measurements units of the system are presented. The article also presents simulation results, which are encouraging, and they demonstrate the performance of the system and its expected relatively high accuracy characteristics, which in turns confirms the expected efficiency of its application and the prospects of the chosen direction of research and development.


Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8457
Author(s):  
James D. Brouk ◽  
Kyle J. DeMars

This paper investigates the propagation of estimation errors through a common coning, sculling, and scrolling architecture used in modern-day inertial navigation systems. Coning, sculling, and scrolling corrections often have an unaccounted for effect on the error statistics of inertial measurements used to describe the state and uncertainty propagation for position, velocity, and attitude estimates. Through the development of an error analysis for a set of coning, sculling, and scrolling algorithms, mappings of the measurement and estimation errors through the correction term are adaptively generated. Using the developed mappings, an efficient and consistent propagation of the state and uncertainty, within the multiplicative extended Kalman filter architecture, is achieved. Monte Carlo analysis is performed, and results show that the developed system has favorable attributes when compared to the traditional mechanization.


2021 ◽  
Author(s):  
Alfredo Lobaina Delgado ◽  
Adson F. Da Rocha ◽  
Alexander Suarez Leon ◽  
Andres Ruiz-Olaya ◽  
Klaus Ribeiro Montero ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6222
Author(s):  
Xiang Tian ◽  
Wei Sheng ◽  
Zhanshe Guo ◽  
Weiwei Xing ◽  
Runze Tang

In this study, a comb-type capacitive accelerometer based on a silicon carbide (SiC) microstructure is presented and investigated by the finite element method (FEM). It has the advantages of low weight, small volume, and low cross-coupling. Compared with silicon(111) accelerometers with the same structure, it has a higher natural frequency. When the accelerometer vibrates, its resistive force consists of two main components: a viscous damping and an elastic damping force. It was found that viscous damping dominates at low frequency, and elastic damping dominates at high frequency. The second-order linear system of the accelerometer was analyzed in the time-frequency domain, and its dynamic characteristics were best when the gap between the capacitive plates was 1.23 μm. The range of this accelerometer was 0–100 g, which is 1.64 times that of a silicon(111) accelerometer with the same structure. In addition, the accelerometer could work normally at temperatures of up to 1200 °C, which is much higher than the working temperatures of silicon devices. Therefore, the proposed accelerometer showed superior performance compared to conventional silicon-based sensors for inertial measurements.


Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6626
Author(s):  
Diego Maceira ◽  
Alberto Luaces ◽  
Urbano Lugrís ◽  
Miguel Á. Naya ◽  
Emilio Sanjurjo

Currently, the interest in creating autonomous driving vehicles and progressively more sophisticated active safety systems is growing enormously, being a prevailing importance factor for the end user when choosing between either one or another commercial vehicle model. While four-wheelers are ahead in the adoption of these systems, the development for two-wheelers is beginning to gain importance within the sector. This makes sense, since the vulnerability for the driver is much higher in these vehicles compared to traditional four-wheelers. The particular dynamics and stability that govern the behavior of single-track vehicles (STVs) make the task of designing active control systems, such as Anti-lock Braking System (ABS) systems or active or semi-active suspension systems, particularly challenging. The roll angle can achieve high values, which greatly affects the general behavior of the vehicle. Therefore, it is a magnitude of the utmost importance; however, its accurate measurement or estimation is far from trivial. This work is based on a previous paper, in which a roll angle estimator based on the Kalman filter was presented and tested on an instrumented bicycle. In this work, a further refinement of the method is proposed, and it is tested in more challenging situations using the multibody model of a motorcycle. Moreover, an extension of the method is also presented to improve the way noise is modeled within this Kalman filter.


2021 ◽  
Author(s):  
Kanika Bansal ◽  
Javier Garcia ◽  
Cody Feltch ◽  
Christopher Earley ◽  
Ryan Robucci ◽  
...  

Leg movements during sleep occur in patients with sleep pathology and healthy individuals.  Some (but not all) leg movements during sleep are related to cortical arousals which occur without conscious awareness of the patient but have a significant effect of sleep fragmentation.  Detecting leg movements during sleep that are associated with cortical arousals can provide unique insight into the nature and quality of sleep in both health and disease.  In this study, a novel leg movement monitor is used in conjunction with polysomnography to better understand the relationship between leg movement and electroencephalogram (EEG) defined cortical arousals.  In an approach that we call neuro-extremity analysis, graph theoretic, directed connectivity metrics are used to interrogate the causal links between neural activity measured by EEG and leg movements measured by the sensors within the leg movement monitor.  The leg movement monitor in this study utilizes novel capacitive displacement sensors, and a 9-axis inertial measurement unit to characterize leg and foot movements.  First, the capacitive displacement measures more closely related to EEG-defined cortical arousals than inertial measurements.  Second, the neuro-extremity analysis reveals a temporally evolving connectivity pattern that is consistent with a model of cortical arousals in which brainstem dysfunction leads to near-instantaneous leg movements and a delayed, filtered signal to the cortex.  Neuro-extremity analysis reveals causal relationships between EEG and leg movement sensor time-series data that may aid researchers to better understand the pathophysiology of cortical arousals associated with leg movements during sleep.


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