Accelerometer Parameters Research Articles

Correlation between kinematic parameters, ataxia and ground-to-lip distance in detomidine sedated horses.

An accurate evaluation of the degree of sedation is mandatory to adjust the dosage of sedative drugs. To determine the correlation between head height above the ground and ataxia degree in horses sedated with detomidine and the correlation existing between accelerometric variables and both parameters. Retrospective study. Twelve horses were given 0.01 mg/kg of detomidine hydrochloride iv. Measured accelerometric parameters, with one accelerometer positioned between both sacral tuberosities, included speed, stride frequency and length, regularity, dorsoventral, longitudinal, mediolateral and total accelerometric activities, relative force index and dorsoventral, longitudinal and mediolateral parts of the accelerometric activities. Head height above the ground (cm) and subjective ataxia degree were also measured. Baseline values (-15 min) and values measured 5 and 15 min after the injection and then every 15 min for a period of 2 h were obtained. There was a negative and strong correlation between head height above the ground and ataxia degree (Pearson r = -0.78, p < 0.001), particularly during the first 45 min. A significant correlation was found between head height above the ground and almost all accelerometric parameters. This correlation was very strong with stride frequency, regularity and dorsoventral and total accelerometric activities in both cases, but for ataxia, also with total accelerometric activity. Experimental conditions may not represent real clinical situations. Stride frequency and regularity are the most reliable parameters to determine degree of sedation and are related to the sedation produced. Ataxia should not be considered a separate property of sedation and does not need to be assessed separately to the depth of sedation.

Optical micro/nano fiber enabled accelerometer

Abstract Highly sensitive and miniaturized accelerometers play an important role in structural health, earthquakes, and body motion monitoring. Herein, an optical micro/nanofiber (MNF) enabled accelerometer is proposed. The structural parameters of the MNF accelerometer are optimized based on theoretical simulation. The accelerometer shows excellent linear relationship between displacement and force, and achieves a minimum detectable acceleration of 0.15 m/s2. For vibration sensing, the natural frequency of the sensor can be as high as 753 Hz.

Optical micro/nanofiber enabled wearable accelerometer

Highly sensitive and miniaturized accelerometers are of importance in many areas. Herein, an optical micro/nanofiber (MNF) enabled accelerometer is proposed. The structural parameters of the MNF accelerometer are optimized based on theoretical simulation. The accelerometer shows excellent linear relationship between displacement and force in a force range of 0–40 nN and achieves a minimum detectable acceleration of 0.15m/s2. For vibration sensing, the natural frequency of the sensor can be as high as 753 Hz; the vibrations of the tuning fork and human arm are recorded with high fidelity.

Designs of Optomechanical Acceleration Sensors with the Natural Frequency from 5 Hz to 50 kHz

In many applications, such as space navigation, metrology, testing, and geodesy, it is necessary to measure accelerations with frequencies ranging from fractions of a hertz to several kilohertz. For this purpose, optomechanical sensors are used. The natural frequency of such sensors should be approximately ten times greater than the frequency of the measured acceleration. In the case of triaxial acceleration measurements, a planar design with two sensors that measure accelerations in two perpendicular in-plane directions and a third sensor that measures out-of-plane acceleration is effective. The mechanical characteristics of the existing designs of both in-plane and out-of-plane types of sensors were analyzed, and the improved designs were elaborated. Using numerical simulation, the dependencies of the natural frequency level in the range from several hertz to tens of kilohertz on the designs and geometric parameters of opto-mechanical accelerometers were modeled. This allows one to select the accelerometer design and its parameters to measure the acceleration at the assigned frequency. It is shown that the opto-mechanical accelerometers of the proposed designs have reduced dissipation losses and crosstalk.

Accuracy Assessment of Charge-Mode Accelerometers Using Multivariate Regression of the Upper Bound of the Dynamic Error

This paper presents the mathematical basis and related procedures for the regression of the upper bound of the dynamic error produced by charge-mode accelerometers. The integral-square error obtained in response to simulation signals with one constraint appearing at the input of the accelerometer is considered. Physical models of accelerometers are presented with related equations and mathematical formulae that make it possible to obtain the error and the corresponding constrained signal. Examples of the regression for predefined values of the accelerometer parameters are also discussed. The solutions presented in this paper may contribute to increasing the accuracy of the charge-mode accelerometers commonly used in energy systems. Development of the functions approximating the integral-square error for the given ranges of accelerometer parameters constitutes the original contribution of this paper.

The Relevance of Intraoperative Clinical and Accelerometric Measurements for Thalamotomy Outcome.

Thalamotomy alleviates medication-refractory tremors in patients with movement disorders such as Parkinson's Disease (PD), Essential tremor (ET), and Holmes tremor (HT). However, limited data are available on tremor intensity during different thalamotomy stages. Also, the predictive value of the intraoperative tremor status for treatment outcomes remains unclear. Therefore, we aimed to quantify tremor status during thalamotomy and postoperatively. Data were gathered between January 2020 and June 2023 during consecutive unilateral thalamotomy procedures in patients with PD (n = 13), ET (n = 8), and HT (n = 3). MDS-UPDRS scores and tri-axial accelerometry data were obtained during rest, postural, and intention tremor tests. Measurements were performed intraoperatively (1) before lesioning-probe insertion, (2) directly after lesioning-probe insertion, (3) during coagulation, (4) directly after coagulation, and (5) 4-6 months post-surgery. Accelerometric data were recorded continuously during the coagulation process. Outcome measures included MDS-UPDRS tremor scores and accelerometric parameters (peak frequency, tremor amplitude, and area under the curve of power (AUCP)). Tremor intensity was assessed for the insertion effect (1-2), during coagulation (3), post-coagulation effect (1-4), and postoperative effect (1-5). Following insertion and coagulation, tremor intensity improved significantly compared to baseline (p < 0.001). The insertion effect clearly correlated with the postoperative effect (ρ = 0.863, p < 0.001). Both tremor amplitude and AUCP declined gradually during coagulation. Peak frequency did not change significantly intraoperatively. In conclusion, the study data show that both the intraoperative insertion effect and the post-coagulation effect are good predictors for thalamotomy outcomes.

Human Activity Detection Using Smart Wearable Sensing Devices with Feed Forward Neural Networks and PSO

Hospitals must continually monitor their patients’ actions to lower the chance of accidents, such as patient falls and slides. Human behavior is difficult to track due to the complexity of human activities and the unpredictable nature of their conduct. As a result, creating a static link that is used to influence human behavior is challenging, since it is hard to forecast how individuals will think or act in response to a certain event. Mobility tracking depends on intelligent monitoring systems that apply artificial intelligence (AI) applications referred to as “categories”. Because motion sensors, such as gyroscopes and accelerometers, output unconnected data that lack labels, event detection is a vital task. The fall feature parameters of tridimensional accelerometers and gyroscope sensors are presented and used, and the classification technique is based on distinguishing characteristics. This study focuses on the age-old problem of tracking turbulence in motion to improve detection precision. We trained the model, considering that detection accuracy is limited by factors such as the subject’s mass, velocity, and gait style. This is performed by employing an experimental dataset. When we used the sophisticated technique of particle swarm optimization (PSO) in combination with a four-stage forward neural network (4SFNN) to forecast four different types of turbulent motion, we observed that the total prediction accuracy was 98.615% accurate.

Failure Detection in Quadcopter UAVs Using K-Means Clustering.

We propose an unmanned aerial vehicle (UAV) failure detection system as the first step of a three-step autonomous emergency landing safety framework for UAVs. We showed the effectiveness and feasibility of using vibration data with the k-means clustering algorithm in detecting mid-flight UAV failures for that purpose. Specifically, we measured vibration signals for different faulty propeller cases during several test flights, utilizing a custom-made hardware system. After we made the vibration graphs and extracted the data, we investigated to determine the combination of acceleration and gyroscope parameters that results in the best accuracy of failure detection in quadcopter UAVs. Our investigations show that considering the gyroscope parameter in the vertical direction (gZ) along with the accelerometer parameter in the same direction (aZ) results in the highest accuracy of failure detection for the purpose of emergency landing of faulty UAVs, while ensuring a quick detection and timely engagement of the safety framework. Based on the parameter set (gZ-aZ), we then created scatter plots and confusion matrices, and applied the k-means clustering algorithm to the vibration dataset to classify the data into three health state clusters—normal, faulty, and failure. We confirm the effectiveness of the proposed system with flight experiments, in which we were able to detect faults and failures utilizing the aforementioned clusters in real time.

On Real-Time Detection of Line Sags in Overhead Power Grids Using an IoT-Based Monitoring System: Theoretical Basis, System Implementation, and Long-Term Field Verification

For overhead power grids, unexpected serious line sagging of extra-high voltage transmission lines would easily lead to major blackouts. Different direct and indirect sag measuring methods have been proposed, but they all have their own limitations. In this study, an Internet of Things (IoT)-based sag-monitoring system is proposed, which is able to perform real-time detection of line sags. The whole system has been deployed on two 161-kV lines for long-term field testing. The effectiveness of the proposed sag-monitoring system is verified through both theoretical calculation and field measurements. In this sag-monitoring system, a sag-sensing module is equipped with an embedded triaxial accelerometer to detect line sags at different spans of a single circuit. A catenary equation that takes temperature dependency into consideration is derived, so the measured accelerometer parameters can be converted to accurate line sag values. The long-term testing results show that the proposed sag-monitoring system yields an average error of 2.09%. The average differences between the sag values coming from the proposed system and a commercial sag measuring device are relatively small (between 0.57% and 4.14%), which proves that the sag values provided by the proposed system are reliable and accurate in the long-term testing. In addition, compared to the other existing sag measuring methods, the advantages of employing the proposed system are high measurement accuracy, and enabling wide field implementation, online monitoring, long-term field operation, and real-time transmission.

Validation of inertial measurement units for the assessment of trunk control in subjects with spinal cord injury

Background: Trunk control (TC) constitutes one of the main objectives in the rehabilitation of people with a spinal cord injury (SCI), but there are few clinically validated tests to assess it. Accelerometers have been proposed as sensitive and suitable procedures to assess TC. Objective: To evaluate test–retest reliability, construct and criterion validity of accelerometer parameters to assess TC in people with SCI. Methods: A cross-sectional study of simultaneous application of Clinical Trunk Control Test (CTCT) and accelerometer evaluation was conducted. Accelerometers were placed on the trunks of 27 people with SCI and 15 people without SCI. Reliability was assessed by three repeated measures in random order of selected static and dynamic TC tasks. Acceleration on three axes was analyzed using five metrics. Criterion validity was assessed by analyzing correlation of acceleration to CTCT scores. Construct validity was assessed by analyzing capacity of inertial measurement units (IMU) to differentiate individual’s characteristics, ASIA Impairment scale, gait capacity, level of TC, and neurological level of injury. Results: Reliable IMU data were obtained in people with SCI and without SCI, of all accelerometer axes, metrics, and tested items of the CTCT. Reliability of acceleration decreases with the increasing demand for TC tasks. Ten acceleration parameters showed construct and criterion validity. Conclusion: Accelerometer parameters are reliable, valid, and sensitive to evaluate TC in people with SCI. Significance: A set of IMU parameters were validated as reliable and valid measures to evaluate TC, which could be useful for the assessment of progression of people with SCI and clinical interventions.

ИСПОЛЬЗОВАНИЕ ОПТИМИЗАЦИОННОГО ПОДХОДА ДЛЯ АВТОМАТИЗИРОВАННОЙ КАЛИБРОВКИ МИКРОЭЛЕКТРОМЕХАНИЧЕСКОЙ ИНЕРЦИАЛЬНОЙ НАВИГАЦИОННОЙ СИСТЕМЫ

Technologies of autonomous wheeled robotic systems are becoming more and more in demandlately. A separate type of application of such technology is an autonomous unmannedground vehicle. Unlike other types of transport (air, water), ground vehicles need to periodicallyoperate in full autonomy - when external communication with the infrastructure and other agentsof the transport network is inaccessible. In such circumstances, the issue of autonomous navigationcomes out on top, and increased requirements are imposed on positioning accuracy, especiallyin an anthropogenic environment, for example, when driving in an urban environment, alongnarrow mountain roads, and tunnels. One of the components of autonomous navigation is often aninertial assembly consisting of several accelerometers, gyroscopes, and magnetometers. To obtaina high-precision navigation solution based on an inertial assembly, it is required to properly calibrateit. A separate issue is automation and its cost for further scaling necessary for mass production.The article presents the theory and methodology for automated calibration of an inertialnavigation system based on MEMS sensors by solving an optimization problem. The proposedtechnique does not require high-precision calibration equipment. The aim of the presented work isto develop methods and theory for the calibration of inertial navigation units. The article formulatesgeneral measurement models of sensors included in the inertial assembly, and proposesmethods for calibrating the parameters of accelerometers and gyroscopes fixed relative to eachother. The method of automation of the calibration process is presented, which does not requirehigh-precision equipment. The results of the application of the developed methods for the calibrationof a real inertial assembly are presented. A stand for automated calibration is presented.

Сomplex approach to certification and metrological estimation the state of digital seismometric registrators

The modern stage of the latest metrological achievements is being intensively deve-loped in our country in new methodological directions that are based on new scientific and technical achievements. The using of metrologically certified devices of different types and with different metrological parameters increases the level of confidence in the results of these works, because the relative comparison of the results of these works allows potential customers to choose the most useful and effective method for obtaining the desired results. This article presents the results of joint scientific and technical works for the methodology of certification of the calibration developed and patented device and the results of using an already certified calibration device for metrological determination of accelerometer parameters, measurers displacements and velocities. This article also shows that one of the important areas of such work on the metrology of measuring devices in the area of seismology is also to determine the amplitude-frequency characteristics or amplitude-frequency and phase characteristics of different devices for measurement velocity, acceleration or displacement for the using of these devices in modern automated complex systems for determination of various parameters of seismic events such as regi-onal, local and teleseismic.&#x0D; The article also presents comparative analyzes of experimental results of work on determining the frequency characteristics of the calibration device in different areas of measurements — displacement, velocity and acceleration. Obtaining these important results for assessing the state of various other seismological devices allowed experimentally do it for possible determination the presence of different types of physical differences in the regions of the same frequency range for displacement's and velocity's measurers. Compliance of the certificate with the requirements of the international metrological certification system ISO/IEC17025, obtained for the calibration device had been ensured by SE «Ukrmetrteststandart».

Studying the possibility of algorithmic compensation of temperature instrumental errors of string accelerometers as a composition of a strapdown inertial unit

The article is devoted to the study of temperature errors of the string accelerometer used as part of a strapdown inertial unit. One of the main tasks facing the development of string accelerometers is the problem of compensating temperature effects to eliminate the resulting errors. One of the methods to solve such problems is to provide compensation for changes in the parameters of the string accelerometer, to level the appearance of the instrumental error in measuring the acceleration in the output signal of the device. On the prepared bench base at Scientific and Production Association of Measuring Technology (AO NPO IT) for setting up and conducting experiments, a study of string accelerometers, which are part of the strapdown inertial unit, was carried out. The study consisted of collecting output information from the device during its temperature calibration. During the experiment, the strapdown inertial unit was oriented in space so that its measuring axes of the accelerometer channels were directed alternately vertically upward or vertically downward with a smooth temperature change. The data obtained were analyzed to determine the dependence of the change in the initial vibration frequency of the string accelerometer and the design parameter of the accelerometer on the temperature in the operating temperature range of the device. An assessment of the possible level of efficiency of algorithmic compensation for changes in the accelerometer parameters was also shown. The studies carried out have shown the possibility, due to the algorithmic compensation of the temperature instrumental errors of one-component string accelerometers, to provide the accuracy requirements for the linear acceleration sensor channel of the strapdown inertial unit device in the operating temperature range. In particular, the use of algorithmic compensation for the temperature error of the initial frequency of the accelerometer f 0 reduced the absolute value of the parameter change by more than two orders of magnitude, and the maximum value of the error in approximating the change in the design parameter k from temperature is an order of magnitude less than the value before algorithmic compensation.

A Ferrofluid-Based Tuning Strategy for Flexible Accelerometers

In this article, a novel methodology to tune parameters of a resonant accelerometer realized by a flexible structure is presented. A model describing the behavior of the tuning mechanism has been proposed and experimentally validated as well as a suitable design flow is presented through case studies. The device under test, whose dimensions are in the mesoscale, adopts a resistive sensing readout strategy implemented through strain gauges, directly inkjet printed on the flexures (springs) supporting the central membrane. The tuning mechanism, which exploits the interaction between an external magnetic field and a magnetic fluid (ferrofluid) embedded in the device’s springs, has been experimentally investigated by using a lab-scale prototype. The procedure for the optimal design of the sensor has also been addressed. The prototype shows a responsivity of 721.0 $\mu $ strain/m/s2 at the resonance frequency of 30.5 Hz and a noise floor of 7.5e $- 5 { \text {m/}}\text {s}^{{2}} {/}\sqrt {\text {Hz}} $ estimated in a bandwidth of 500 Hz. Responsivities of $657.0~\mu $ strain/m/s2 and $580.0~\mu $ strain/m/s2 as well as noise floor of 8.7e $- 5 { \text {m/}}\text {s}^{{2}} {/}\sqrt {\text {Hz}} $ and 10.9e $- 5 { \text {m/}}\text {s}^{{2}} {/}\sqrt {\text {Hz}} $ have been estimated in case of the tuning magnetic fields of $H =6.8\text{e}-3$ T and $H =11.4\text{e}-3$ T, respectively, showing resonance frequencies of 31.0 and 32.5 Hz. The main novelty of the proposed approach arises from the tuning strategy that is important for many real applications requiring a fine-tuning of the sensor parameters while the use of a cheap inkjet printing technology for the device realization represents a substantial advantage in terms of costs and to enable the rapid prototyping of customizable devices on flexible substrates.

Low-Cost and Efficient Thermal Calibration Scheme for MEMS Triaxial Accelerometer

In view of the large thermal drift of microelectromechanical system (MEMS) triaxial accelerometer and the high cost of traditional calibration schemes, this article proposes a low-cost and efficient thermal drift calibration scheme combining the parameter-correction method and the proposed least squares method based on the nine-parameter model. In this scheme, first, the parameter-correction method is applied to the data collected under the heating condition to obtain the thermal drift of calibrated parameters with constant error. The least squares method is then used to obtain the parameters at a temperature T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> . Then, the two sets of parameters are combined, and the constant offset error is removed. Finally, higher precision thermal drift curves of the parameters are obtained after smoothing and filtering. One thousand simulations show that the previously proposed parameter-correction method has consistent accuracy and can obtain accurate drift trends of the triaxial accelerometer parameters. The actual triaxial accelerometer thermal drift calibration experiment shows that when the temperature rises by 22 °C, the sensor data converted by the parameters obtained by the proposed scheme can effectively reduce the drift. The drifts of x- and y-axes are reduced from -19.2 and 11.6 mg to -0.7 and -0.6 mg, respectively. The Z-axis drift is reduced from -23.9 to 3.5 mg. This proves the feasibility of the method and scheme proposed in this article.

Exercise training improves sleep quality: A randomized controlled trial.

Exercise holds promise as a non-pharmacological intervention for the improvement of sleep quality. Therefore, this study investigates the effects of different training modalities on sleep quality parameters. A total of 69 (52.7% women) middle-aged sedentary adults were randomized to (a) control group, (b) physical activity recommendation from the World Health Organization, (c) high-intensity interval training (HIIT) and (d) high-intensity interval training group adding whole-body electromyostimulation training (HIITEMS). Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) scale and accelerometers. All intervention groups showed a lower PSQI global score (all P < .022). HIIT-EMS group improved all accelerometer parameters, with higher total sleep time and sleep efficiency, and lower wake after sleep onset (all P < .016). No differences were found between groups in any sleep quality parameter. In conclusion, exercise training induced an improvement in subjective sleep quality in sedentary middleaged adults. Moreover, HIIT-EMS training showed an improvement in objective sleep quality parameters (total sleep time, sleep efficiency and wake after sleep onset) after 12 weeks of exercise intervention. The changes observed in the HIIT-EMS group were not statistically different to the other exercise modalities.

Combined Effects of Water Depth and Velocity on the Accelerometric Parameters Measured in Horses Exercised on a Water Treadmill.

Simple SummaryAnecdotal comments of some trainers suggest that exercise on a water treadmill (WT), due to the greater difficulty of movement in water compared to air, increases muscularization and sports performance. Therefore, we studied accelerometric changes in six horses exercised for 40 min on a WT, comparing four situations: without water (DT) and with water at the depth of fetlock (FET), carpus (CAR), at 6 km/h and at the depth of the stifle (STF) at 5 km/h. Another five horses performed the same sessions, but all of them at 5 km/h. We observed that total power (TP) increased from depth DT to FET and CAR, without additional increases at STF depth when the velocity was the same at all depths. However, when the velocity was reduced to 5 km/h, TP decreased at the STF depth. Significant increases in dorsoventral power and dorsoventral displacement (movement of the center of gravity in up-down direction) increased with water depth and velocity. In conclusion, TP during an exercise session on a WT depends on both velocity and water depth, and this power is mainly directed towards the dorsoventral axis. These results should be taken into account when designing a training or rehabilitation plan.Horse trainers often claim that exercise on a water treadmill (WT) leads to a greater muscle power and development compared to terrestrial locomotion, because of the greater viscosity of water compared to air. This research assesses locomotor changes measured with accelerometers fixed in the pectoral region and in the sacrum midline in six horses subjected to exercise sessions of 40 min duration on a WT without water (DT), and with water at the depth of fetlock (FET) and carpus (CAR) with velocities of 6 km/h and at the depth of stifle (STF) at 5 km/h. Another five horses performed the same exercise sessions but always with a velocity of 5 km/h. Total power increased from DT to FET and CAR, without significant differences between CAR and STF depths when the velocity was the same. However, a significant decrease was found when the velocity was reduced. The greater total power with water was distributed mainly to the dorsoventral axis, with significant increases in dorsoventral displacement and dorsoventral power. Both parameters were significantly affected by velocity and water depth. In conclusion, total and dorsoventral powers increased with velocity and water depth, leading to reduction in longitudinal and mediolateral power, during exercise on a WT.

Improvement of the Vibratory Analysis by Enhancement of Accelerometer Characteristics

In this work, the mathematical model suitable for the operating principle of the piezoelectric accelerometer is extracted then this model which connects the accuracy and the measurement error according of the frequency ration and the damping rate is validated by simulation. The model developed makes it possible to improve the performances of the accelerometer such as precision, sensitivity and reliability as well as to propose a new conception of the latter. A comparative study is made to show the importance of our results compared to literature, these results have showed that a suitable and appropriate choice of damping ratio develops the accelerometer parameters and enhances the vibratory analysis technique.

Stabilization and Control of Single-Wheeled Vehicle with BLDC Motor

To stabilize a single-wheel vehicle is necessary to know the angle of gradient of the platform with respect to the horizontal axis and also the movement of the vehicle. This can be detected in several ways. Accelerometers and gyroscopes are small, accurate and energy-saving today. They provide analogue or digital output. In the introduction we will describe the basic parameters of accelerometer and gyroscope. We will describe the principle of digital signal processing from both sensors. In the next section we look at the effect of dynamic acceleration on the sensors and the elimination of this phenomenon with a complementary filter. We explain, what it is a complementary filter, benefits and internal structure. We will include a short code in the C language for data processing from the output.

A novel hybrid calibration method for FOG-based IMU

Fiber optic gyro inertial measurement unit (FOG-IMU) discrete calibration is a challenging task due to its dependence on non-linear filtering, complex computations, turntable accuracy and so on. In view of these problems, this paper proposes a high precision FOG hybrid grading calibration method using low-cost turntable. Combination method of coarse and accurate calibration is used to realize high precision calibration of FOG-IMU sensors. First of all, the system parameters sensors of IMU are calibrated using coarse calibration method. The parameters of accelerometer and gyro biases are calibrated by using low-cost turntable. In addition, the effect of the lever-arm is also considered. Then, system parameters are compensated. Afterwards, the residual components of IMU system parameter calibration are taken as estimated objects. According to the basic error equations of inertial navigation algorithm, 27-dimensions Kalman filter is formed based on velocity errors observations, and calibration path is arranged reasonably. Finally, the residual error of coarse calibration is estimated and modified, accordingly. The proposed method is validated through simulation and experiment with various rotation rates. The results verify the feasibility and effectiveness of the algorithm.