Because of the high cost of mechanical and optical gyroscopes, in recent years the low cost measurement systems based on Micro Electro Mechanical sensor (MEMS) are widely used. These systems often are integrated with radio navigation to achieve the required accuracy. MEMS gyroscopes suffer some problems like large drift and acoustic sensitivity, compare with MEMS Accelerometers. So the design of low cost inertial measurement system without using the gyroscope, and based on a suitable geometry configuration of Accelerometers is considered in literature in recent years. The goal of this research is to design and manufacture of such free gyroscope measurement unit. For this purpose, first an appropriate geometry configuration of accelerometer is proposed then the mathematical relationship between the output of linear Accelerometers and linear and revolving acceleration of the center of mass of the structure is derived and then the angular velocities are estimated. The proposed free gyroepocs IMU is constructed using the ADXL345 Accelerometers as sensors and the ARM-LPC1768 microcontroller as processing unit. The experimental results using a rotating table as reference are gathered in the Lab. The results show the suitable performance of the measurements unit.

Today, smartphones are well equipped with various sensors such as Accelerometers, magnetometers and GPS devices. The smartphones that are installed on the ground and may not experience a considerable slipping, may effectively be used as a large network of low to moderate seismometers. This smartphone-based seismic network can efficiently serve for producing shake maps, earthquake risk and hazard assessment and analysis, and earthquake crisis management. In this article, an Android application is developed by Java-programming in Android Studio IDLE to record and save three components of acceleration data that are sensed by smartphone Accelerometers, and send them to a local server. The feasibility of smartphone Accelerometers are then investigated for developing any future smartphone-based seismic networks especially for earthquake engineering applications. For this purpose, several important criteria such as recorded acceleration data (for the three components), peak ground accelerations (PGA), peak ground velocities (PGV), peak ground displacements (PGD), as well as Fourier and response spectra and Arias intensities are derived for two test smartphones and a reference professional Gü ralp accelerometer. The effect of smartphone slipping with respect to the ground during the earthquake data recording is also investigated. Harmonic oscillations with different frequencies and Bam earthquake movements are simulated by a shaking table that is designed and manufactured in the Earthquake Research Center (EQRC), Ferdowsi university of Mashhad. The above mentioned criteria derived from the recorded seismic data for the two test mobile sets are compared with those of reference Gü ralp accelerometer. The results show that the frequency range provided by the seismic data recorded by smartphone Accelerometers is efficiently enough for any earthquake engineering application (0. 1 to 10~20 Hz), especially for short to medium buildings. The accuracy of such devices are well enough to record seismic movements produced by nearly severe earthquakes with magnitudes > 5 at epicentral distances < 200 km. It is also shown in this article that small relative movements of mobile sets on their base may have little effect on seismic criteria and may not harmfully deviate the results. Sensitivity of the test mobiles to trigger earthquakes with magnitudes > 4. 5 at epicentral distance of 10 km is also investigated. As a whole, application of smartphone Accelerometers seems to be strongly justified for developing any seismic data aimed at earthquake engineering applications and earthquake crisis management. The EQRC team is now developing its smartphone– based seismic network on small to moderate scales and is testing different protocols for an efficient data transfer.

In the domain of damage detection, many notable methods have been introduced over the past years. Damage Load Vectors (DLV) is among the most powerful methods, which computes a set of load vectors from variations in flexibility matrices of a frame in undamaged and damaged conditions. These flexibility matrices are derived from acceleration responses of the frame that can be captured using Accelerometers. The DLV method then scrutinizes this shift among flexibility matrices, which ultimately enables locating the damaged member(s). This study holistically conducted seven experimental tests with seven damage scenarios of a test frame installed on a semi-harmonic shaking table. The DLV method was subsequently employed to locate the damaged members using recorded frame vibration data that were obtained from 'noisy' Accelerometers positioned on the frame at eight predefined locations. The Eigen Realization Algorithm (ERA) alongside Pandy's recommendations was adopted herein to facilitate the generation of accurate flexibility matrices derived from the noisy Accelerometers. The outcome is very encouraging with the accurate identification of damaged members in all seven damage scenarios without any 'positive-false' and 'negative-false'  findings. Additionally, there is a decrease (from 0. 045 to 0. 289) in the accuracy of Weighted Stress Indices (WSI) index when the number of damaged members is increased.

current inertial navigation systems usually use liner accelerometer and gyroscopes to sense linear accelerations and angular velocity, respectively. The gyroscopes have the disadvantage such as: complicated manufacture technique, high cost, and large volume and so on. Due to these factors the small Accelerometers with low cost to replace the gyroscopes in some inertial navigation systems.In this paper a ten-accelerometer configuration is proposed which can determine linear acceleration an angular velocity completely. The advantages of this method in comparison with previous works are the simplicity of the equations and elimination of direct integration of angular acceleration.Actual Accelerometers have errors such as bias and misalignment which have significant effect on precision of inertial navigation systems. So, these errors and their effect on navigation are considered in modelling and simulation. The obtained results of simulation show that this method has suitable precision in short time navigation systems.

The aim of this paper is to analyze the sensor errors in measurement while drilling (MWD) instrument used in directional drilling operations. The MWD consist of three orthogonal Accelerometers, three orthogonal magnetometers and one temperature sensor. The system formulation is achieved through the system analysis and functional consideration. The obtained formulation is validated and verified by comparing the results obtained from measurements and simulations. The Accelerometers calibration, to estimate bias factors, scale factors and non-orthogonal factors of sensors, is done using optimal non-linear Newton Raphson algorithm by considering the high temperature calibration coefficients. The accuracy of the experimental results, obtained from several measurement while drilling systems in Iranian national oil drilling company shows the effectiveness of the approach.