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In this paper, we propose two methods based on quaternions to compute the angles of inclination and the angular velocity with 6 degrees of freedom using the measurements of a 3-axis accelerometer and a 3-axis magnetometer. Each method has singularities which occur during the computation of the orientation of the device in the 3-dimensional space. W...
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... default coefficients have been computed with MATLAB by synthesizing a low-pass filter with an experimentally determined cut-off frequency , where denotes the sampling frequency. They are given by . If a variation of the norm exceeds a threshold, the cut-off frequency of the Butterworth filter increases of and the coefficients are computed again. If the cut-off frequency reaches , the filter waits for the norm to stabilize. Then, decreases of until it reaches . Then, is kept, until the norm exceeds again the threshold. A threshold of has been experimentally determined. A sliding median filter is used in order to eliminate the highest frequencies sensor spurious noise, which creates variations of the norm of . Since this norm should be constant, we need to eliminate the samples that have an erroneous norm. As we will see in section 3.3, directly impacts the accuray of the entire computation process, hence the need to get with the least error. The sliding median filter uses a sliding window of norms. At the beginning, the window contains the first norms of the first samples. Then, the norms of the window are sorted. Finally, the median value of the window is extracted, and the sample whose norm is the median value is output from the filter, as shown in Fig. 5. Let be the input vector, the filtered vector and the index of the sample. The expression of the filter is given by: Then, the window slides to the right and the norms of are extracted. A sliding median filter creates a delay of ...
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... Microelectromechanical gyroscopes have found numerous applications such as in inertial navigations, automotive engineering, virtual reality, robotics, video camera stabilization and many other instances [1][2][3][4][5][6][7][8][9][10]. Among various categories of microgyroscopes, suspended vibratory gyroscopes are of special importance thanks to suitability for fabrication using micromachining processes. ...
The objective of this paper is to present a novel nonlocal strain gradient formulation for dynamic analysis of microgyroscopes. Taking into account the effect of nonlocal and gradient strains, the coupled equations of motion and the corresponding boundary conditions are derived using the Hamilton’s principle. Reduced order models for electrostatic and electrodynamic performance of the gyroscope are presented based on Galerkin projection technique. First, the influence of nonlocal and length-scale parameters on the electrostatic instability of the microgyroscope are investigated and it will be demonstrated that for electrostatic loading, the pull-in instability is delayed with decreasing the nonlocal and/or increasing the length-scale parameters. Then the equations governing the electrodynamic performance of the system are solved and the time responses and phase diagrams along to the drive and sense directions are presented. The stable amplitude and instability margin of the gyroscope under electrodynamic loading will be demonstrated to be subjected to nonlocal and length-scale parameters. Finally the frequency response of the gyroscope along the sense and drive directions are scrutinized. Accordingly, it will be shown that the nonlocal and length-scale values affect the near-resonance amplitude of vibration significantly. Furthermore, altering the values of nonlocal and length-scale parameters can change the distance between two peak frequencies as well as their absolute values.
... He first prepared the transpalladium bis(pyridine) complex 6 shown in Figure 4 (top), in which the 2 and 6 pyridine positions (adjacent to the nitrogen atom) feature alkene containing CH 2 CH 2 CHCH 2 substituents. This complex underwent 2-fold interligand ring closing olefin metathesis with Grubbs' first generation catalyst to yield what could be termed a pyridinophane adduct (7). Such ring closing metatheses commonly give cis/trans CC mixtures, but the cis,cis isomer crystallized, and an X-ray structure could be obtained. ...
Research directed toward the goal of molecular gyroscopes since the coverage of a previous review (2002) is described. Such species are a subclass of molecular rotors, which are comprised of rotators and stators. Major categories include (1) systems in which a rotator is embedded in a cage-like stator reminiscent of mechanical toy gyroscopes and (2) molecules that have been engineered to crystallize with parallel rotators and voids or other features that enable the rotator to rotate in the solid state (amphidynamic crystals). Particular attention is given to structural data and strategies for the minimization of rotational barriers. Synthetic routes are also described. Some allied types of molecules and supramolecular assemblies are also treated.
... While this work discusses the best detection and counter detection strategies for an abstract sensor, it does not implement a concrete sensor fusion algorithm, as we present in our work. Delporte et al. made use of positional sensor fusion in a constructive context in Delporte et al. [9]. In this work, a world frame approximation of the gyroscope was obtained while using a system equipped with only a magnetometer and an accelerometer. ...
... In fact, Delporte et al. Delporte et al. [9] were able to use only accelerometer and magnetometer readings to create a "virtual gyroscope". Another possible solution in the event of a sensor disagreement would be to tweak the sensor readings until they both agree, effectively halving the power of the attacker. ...
Position sensors, such as the gyroscope, the magnetometer and the accelerometer, are found in a staggering variety of devices, from smartphones and UAVs to autonomous robots. Several works have shown how adversaries can mount spoofing attacks to remotely corrupt or even completely control the outputs of these sensors. With more and more critical applications relying on sensor readings to make important decisions, defending sensors from these attacks is of prime importance. In this work we present practical software based defenses against attacks on two common types of position sensors, specifically the gyroscope and the magnetometer. We first characterize the sensitivity of these sensors to acoustic and magnetic adversaries. Next, we present two software-only defenses: a machine learning based single sensor defense, and a sensor fusion defense which makes use of the mathematical relationship between the two sensors. We performed a detailed theoretical analysis of our defenses, and implemented them on a variety of smartphones, as well as on a resource-constrained IoT sensor node. Our defenses do not require any hardware or OS-level modifications, making it possible to use them with existing hardware. Moreover, they provide a high detection accuracy, a short detection time and a reasonable power consumption.
... In this study, to reduce calculation burden for microcontroller fast complementary filter is used with Kalman filter. Related research work on IMU fusion have been successfully done in [7], [8], [9] and [10]. But if there is no angle feedback from observer frame, the performance of the comparison cannot be done distinctly. ...
... magnetometer). A method for sensors" data fusion in order to get device"s orientation is described in [14]. ...
Modern handheld devices, i.e. smartphones, have gone beyond their basic purpose for some time now. Beside powerful screens, which usually surpass those we use on our desktops, powerful cameras, and internet connectivity, these devices usually integrate many sensors. In this paper, we discuss how we can combine smart phone’s camera, connectivity, GPS receiver, accelerometer, and magnetometer in order to transform this kind of a device into geospatial video source. To validate and test suggested solution, we implemented a simple mobile app that fetches frames and sensors’ data, calculates georeference and streams geospatial video. In the paper, we also discussed limitations that are caused by the limited precision of used sensors.
... Para un correcto diseño de los filtros de fusión de datos es necesario conocer la exactitud de la medición y para esto disponer de un modelo del sensor resulta de utilidad. En este trabajo se adoptó el modelo propuesto por [1], [2], [3] y se buscó caracterizar los parámetros de dicho modelo. El objetivo es poder tener una mejor caracterización de estos dispositivos a la hora de decidir su utilización o no en un desarrollo. ...
... They can be turned off between measurements to save power, e.g. a magnetometer sampled at 100 Hz can be turned on for 1 ms to take a measurement and off for 9 ms, reducing power consumption to 10% at the expense of increased sensor noise. Moreover, these sensors are already implemented in many tags to estimate heading and are becoming available, integrated with accelerometers, as a low-power alternative to gyroscopes in consumer products (Delporte et al., 2012). A drawback of magnetometers is that, being a vector field sensor, they only measure two of the three rotational degrees of freedom, restricting the types of movements which they can track. ...
Studies of locomotion kinematics require high-resolution information about body movements and the specific acceleration (SA) that these generate. On-animal accelerometers measure both orientation and SA but an additional orientation sensor is needed to accurately separate these. Although gyroscopes can perform this function, their power consumption, drift and complex data processing make them unattractive for biologging. Lower power magnetometers can also be used with some limitations. Here, we present an integrated and simplified method for estimating body rotations and SA applicable to both gyroscopes and magnetometers, enabling a direct comparison of these two sensors. We use a tag with both sensors to demonstrate how caudal-oscillation rate and SA are adjusted by a diving whale in response to rapidly changing buoyancy forces as the lungs compress while descending. Both sensors gave similar estimates of the dynamic forces demonstrating that magnetometers may offer a simpler low-power alternative for miniature tags in some applications.
... Accelerometer [4], [14], [15], [13] Gyroscope [16]- [18] Magnetometer [16], [17] Physical health sensors Electrocardiogram (ECG) [19] Skin temperature [20] Heart rate (HR) [4], [21] Electroencephalograph (EEG) [22] Electromyogram (EMG),etc. [23] Environmental sensors ...
... Accelerometer [4], [14], [15], [13] Gyroscope [16]- [18] Magnetometer [16], [17] Physical health sensors Electrocardiogram (ECG) [19] Skin temperature [20] Heart rate (HR) [4], [21] Electroencephalograph (EEG) [22] Electromyogram (EMG),etc. [23] Environmental sensors ...
Data preprocessing, feature selection and classification algorithms usually occupy the bulk of surveys on human activity recognition (HAR). This paper instead gives a brief review on the data acquisition which is a critical stage of the wearable data-driven-based HAR. The review focuses on the determination of sensor types, modality of sensor devices, sensor deployment and data collection. The work aims to provide a comprehensive and detailed guidance for the fundamental part in HAR, also to highlight the challenges related to the topics reviewed.
... The device was dropped from several known heights, while an application known as "DataCollection" developed by Christopher Wozny recorded acceleration, gyroscopic and magnetometer data. A rotation about the Z axis, the Y axis or the X axis can be respectively described by a rotation matrix ( ), ( ), ( ), represented as following [11] The earth's magnetic field can be expressed as ...
... The others have focused on methods to improve these sensors' performance. These methods include fusion of the sensors and their filtering [3][4][5][6]. ...
This article aims at determining tilt angle of an object. For this reason, a fusion of gyro sensors and MEMS accelerometers have been utilized. At the first step, Levenberg-Marquardt optimization method was adopted to calibrate the accelerometer sensor. Next, after finding sensitivity coefficients of the gyro sensor, moving average filter has been used to reduce system's susceptibility to noise. Ultimately, by fusing the data from the gyro sensor with those of the accelerometer, it is attempted to find inclination angle. The results reveal that the proposed fusion algorithm has compensated time delay, susceptibility to noise, and accelerometer sensor motion sensitivity. In addition, it has corrected cumulative error of the gyro sensor in determining rotation angle.
