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The working modes of the improved accelerometer. (a) The working mode of the upper resonator; (b) The working mode of the lower resonator.
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The micromechanical silicon resonant accelerometer has attracted considerable attention in the research and development of high-precision MEMS accelerometers because of its output of quasi-digital signals, high sensitivity, high resolution, wide dynamic range, anti-interference capacity and good stability. Because of the mismatching thermal expansi...
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Citations
... In [19], a temperature gradient was induced to reduce the warpage of the bonded slices of a MEMS device. Other accelerometers were designed to be insensitive to temperature [12,20,30]. ...
Temperature is a major source of inaccuracy in high-sensitivity accelerometers and gravimeters. Active thermal control systems require power and may not be ideal in some contexts such as airborne or spaceborne applications.
We propose a solution that relies on multiple thermometers placed within the accelerometer to measure temperature and thermal gradient variations. Machine Learning algorithms are used to relate the temperatures to their effect on the accelerometer readings. However, obtaining labeled data for training these algorithms can be difficult. Therefore, we also developed a training platform capable of replicating temperature variations in a laboratory setting.
Our experiments revealed that thermal gradients had a significant effect on accelerometer readings, emphasizing the importance of multiple thermometers.
The proposed method was experimentally tested and revealed a great potential to be extended to other sources
of inaccuracy as well as to other types of measuring systems, such as magnetometers or gyroscopes.
... Then, by measuring the size of electrical signals, the changes and sizes measured can be judged [28]. ...
The problem that the fuze overload signal sticks and is not easily identified by the counting layer during the high-speed intrusion of the projectile is an important factor affecting the explosion of the projectile in the specified layer. A three-pole plate dual-capacitance acceleration sensor based on the capacitive sensor principle is constructed in this paper. The modal simulation of the sensor structure is carried out using COMSOL 6.1 simulation software, the structural parameters of the sensor are derived from the mechanical properties of the model, and finally the physical sensor is processed and fabricated using the derived structural parameters. The mechanical impact characteristics of the model under different overloads were investigated using ANSYS/LS-DYNA, and the numerical simulation of the projectile intrusion into the three-layer concrete slab was carried out using LS-DYNA. Under different overload conditions, the sensor was tested using the Machette’s hammer test and the output signal of the sensor was obtained. The output signal was analyzed. Finally, a sensor with self-powered output, high output voltage amplitude, and low spurious interference was obtained. The results show that the ceramic capacitive sensor has a reasonable structure, can reliably receive vibration signals, and has certain engineering applications in the intrusion meter layer.
... A MEMS resonant accelerometer is a force-sensitive sensor that detects external acceleration according to the force-frequency characteristics of the resonant beam. A schematic diagram of a MEMS resonant accelerometer is shown in Figure 1, consisting of doubleended turning forks (DETFs), a proof mass, micro-levers, combs, and anchors [21]. The DETFs work as force-sensitive resonant beams, one end of which is fixed to the anchors and the other end of which is connected to the proof mass, which converts external acceleration into inertial force. ...
Due to the working principle of MEMS resonant accelerometers, their thermally induced frequency drift is an inevitable practical issue for their extensive application. This paper is focused on reducing the thermally induced packaging effects on the frequency drift. A leadless ceramic chip carrier package with a stress-buffering layer was proposed for a MEMS resonant accelerometer, and the influences of packaging structure parameters on the frequency drift were investigated through finite element simulations and verified experimentally. Because of the thermal mismatch between dissimilar materials, the thermo-mechanical stress within the resonant beam leads to a change in the effective stiffness and causes the frequency drift to decrease linearly with increasing temperature. Furthermore, our investigations reveal that increasing the stress-buffering layer thickness and reducing the solder layer thickness can significantly minimize the thermo-mechanical stress within the resonant beam. As the neutral plane approaches the horizontal symmetry plane of the resonant beam when optimizing the packaging structure, the effects of the compressive and tensile stresses on the effective stiffness of the resonant beam will cancel each other out, which can dramatically reduce the frequency drift. These findings provide guidelines for packaging design through which to improve the temperature stability of MEMS resonant accelerometers.
... The magnitude of the input acceleration will be calculated from the difference between the resonant frequencies of the two resonators. According to [23], the resonant frequency of DETFs under inertial force are as follows: ...
... With the high-order terms omitted, the differential frequency output of the accelerometer is given as follows [23]: ...
... Based on the previous research on the resonant accelerometer and the ring gyroscope [23,26,27], combined with the current DDSOG technology level, the main structural parameters of the accelerometer gyroscope are set as shown in Table 1. ...
This paper presents the design and simulation of a single-chip integrated MEMS accelerometer gyroscope by integrating a Coriolis vibratory ring gyroscope and a differential resonant accelerometer into one single-chip structure, measuring both the acceleration and the angular velocity (or the angle). At the same time, it has the advantages of small volume, low cost, and high precision based on the characteristics of a ring gyroscope and resonant accelerometer. The proposed structure consists of a microring gyroscope and a MEMS resonant accelerometer. Tthe accelerometer is located inside the gyroscope and the two structures are concentric. The operating mechanisms of the ring gyroscope and the resonant accelerometer are first introduced. Then, the whole structure of the proposed single-chip integrated accelerometer gyroscope is presented, and the structural components are introduced in detail. Modal analysis shows the resonant frequencies of upper and lower DETFs in resonant accelerometer are 28,944.8 Hz and 28,948.0 Hz, and the resonant frequencies of the ring gyroscope (n=2) are 15,768.5 Hz and 15,770.3 Hz, respectively. The scale factor of the resonant accelerometer is calculated as 83.5 Hz/g by the analysis of the input–output characteristic. Finally, the thermal analysis fully demonstrates that the single-chip integrated accelerometer gyroscope has excellent immunity to temperature change.
... Micromachined silicon resonant accelerometers have the advantages of small size, low power consumption, mass production, and quasi-digitalization [1,2]. They have been widely used in aerospace and Earth exploration fields [3,4]. ...
The output of the micromachined silicon resonant accelerometer (MSRA) is prone to drift in a temperature-changing environment. Therefore, it is crucial to adopt an appropriate suppression method for temperature error to improve the performance of the accelerometer. In this study, an improved firefly algorithm-backpropagation (IFA-BP) neural network is proposed in order to realize temperature compensation. IFA can improve a BP neural network’s convergence accuracy and robustness in the training process by optimizing the initial weights and thresholds of the BP neural network. Additionally, zero-bias experiments at room temperature and full-temperature experiments were conducted on the MSRA, and the reproducible experimental data were used to train and evaluate the temperature compensation model. Compared with the firefly algorithm-backpropagation (FA-BP) neural network, it was proven that the IFA-BP neural network model has a better temperature compensation performance. The experimental results of the zero-bias experiment at room temperature indicated that the stability of the zero-bias was improved by more than an order of magnitude after compensation by the IFA-BP neural network temperature compensation model. The results of the full-temperature experiment indicated that in the temperature range of −40 °C~60 °C, the variation of the scale factor at full temperature improved by more than 70 times, and the variation of the bias at full temperature improved by around three orders of magnitude.
... In this structure, active damping driving and detecting combs are added to the existing accelerometer proof mass [16]. Fixed active damping driving combs 1, fixed active damping driving combs 2, fixed active damping detecting combs 1, and fixed active damping detecting combs 2, as shown in Figure 3, are connected with each other through the bottom wiring and, therefore, can be considered the same point in the logic of the electrical connection. ...
... During the subsequent simulation analysis of this structure, the comb structure is aggregated and equated to facilitate the simulation analysis. In this structure, active damping driving and detecting combs are added to the existing accelerometer proof mass [16]. Fixed active damping driving combs 1, fixed active damping driving combs 2, fixed active damping detecting combs 1, and fixed active damping detecting combs 2, as shown in Figure 3, are connected with each other through the bottom wiring and, therefore, can be considered the same point in the logic of the electrical connection. ...
This paper presents a micromachined silicon resonant accelerometer based on electrostatic active damping control, which can improve the shock response performance of the accelerometer. In the accelerometer, an electrostatic active damping structure and damping control circuit are designed to improve the equivalent damping coefficient of the system. System-level Simulink modeling and simulation of the accelerometer with an electrostatic active damping closed-loop control link were carried out. The simulation results indicate that the system can quickly return to normal output without an obvious vibration process after the shock. The fabricated and packaged accelerometer was connected to an external test circuit for shock performance testing. The stabilization time of the accelerometer after a 100 g, 3–5 ms half-sine shock was reduced from 19.8 to 5.6 s through use of the damping control. Furthermore, the change in deviation before and after the shock without damping control was 0.8197 mg, whereas it was 0.1715 mg with damping control. The experimental results demonstrate that the electrostatic active damping control can effectively improve the dynamic performance of the micromachined silicon resonant accelerometer.
... The second type of MOEMS accelerometer sensors measure acceleration based on frequency modulation. This type of sensor can measure acceleration by measuring the phase difference [15], [16], photoelectric effect [17], and interferometry [18], [19]. The second type of MOEMS accelerometer sensors is more accurate and has a higher frequency bandwidth than the first type. ...
This paper is a report on the design and fabrication of a dual-axis micro-opto-electro-mechanical system (MOEMS) accelerometer. The device consists of a proof mass (PM) suspended by four L-shaped springs. Two Fabry-Pérot (FP) cavities are formed between the cross-sections of the PM and the ends of two cleaved optical fibers in perpendicular directions (the X and Y axes). The acceleration causes the proof mass to move in the reverse direction relative to the applied acceleration. The sensor is fabricated by a silicon-on-insulator wafer. The fabricated sensor is characterized both by spectral monitoring and power measurements in the range of ±1 g. The results of spectral measurements show 3.23 nm/g (g = 9.81 m/s2: gravity constant) and 3.19 nm/g to the applied acceleration along the X and Y axes, respectively. Moreover, the obtained resolutions for the two directions of X and Y are
$309~\mu \text{g}$
and
$313~\mu \text{g}$
, respectively. Besides, the sensitivity of the sensor in power measurements is 550 mV/g and 528 mV/g in the X and Y directions, respectively. The sensor also possesses the resonant frequencies of 1382.5 Hz and 1398.6 Hz in the X and Y axes, respectively, in the range of ±1 g. The maximum cross-axis sensitivities obtained for this sensor are below 0.19% for each pair of X, Y, and Z axes. This value is fewer than the cross-axis sensitivity of most micro electro-mechanical systems without any post processing. This small value is a result of insensitivity of the FP spectrum to the lateral displacements of the PM.
... Most of the resonant MEMS accelerometers use resonant frequency shift, based on stiffness modulation, as an output metric for the measurement of input acceleration due to output signal being quasi-digital and high sensitivity [3,4]. However, the resonant frequency shift output metric for MEMS accelerometers is also strongly affected by the environmental variations including temperature and pressure [5,6]. This requires additional error compensation techniques for the stable operation of such resonant MEMS accelerometers [7,8]. ...
This paper presents a new design of microelectromechanical systems (MEMS) based low-g accelerometer utilizing mode-localization effect in the three degree-of-freedom (3-DoF) weakly coupled MEMS resonators. Two sets of the 3-DoF mechanically coupled resonators are used on either side of the single proof mass and difference in the amplitude ratio of two resonator sets is considered as an output metric for the input acceleration measurement. The proof mass is electrostatically coupled to the perturbation resonators and for the sensitivity and input dynamic range tuning of MEMS accelerometer, electrostatic electrodes are used with each resonator in two sets of 3-DoF coupled resonators. The MEMS accelerometer is designed considering the foundry process constraints of silicon-on-insulator multi-user MEMS processes (SOIMUMPs). The performance of the MEMS accelerometer is analyzed through finite-element-method (FEM) based simulations. The sensitivity of the MEMS accelerometer in terms of amplitude ratio difference is obtained as 10.61/g for an input acceleration range of ±2 g with thermomechanical noise based resolution of 0.22 and nonlinearity less than 0.5%.
... According to formula (1), the temperature sensitivity of the DETFs is only related to the temperature coefficient of Young's modulus. However, previous reports show that thermal stress caused by temperature changes can directly affect the frequency output of the resonant sensors, including accelerometers [33] and gyroscopes [34]. Thermal stress is generally induced by the mismatching thermal expansion coefficients of the sensor chip, the adhesive, and the chip carrier [8]. ...
Temperature compensation with high accuracy is crucial for improving the performance of MEMS resonant accelerometers. In this paper, we propose an effective temperature compensation method based on the backpropagation neural network (BP-NN). First, we analyzed the relationship among the input acceleration , the environmental temperature, the output frequencies, and the scale factor of a MEMS resonant accelerometer through the traditional polynomial fitting method. After that, we introduced the BP-NN improved by genetic algorithm (GA). Numerous experiments were performed to train the BP-NN model and establish the relationships between the input layer and the output layer. Comparison between single-beam working mode and symmetrical double-beam working mode of the MEMS resonant accelerometer proved that the latter had a better temperature compensation effect due to its minimized error caused by temperature measurement. Experimental results show that the maximum error of our approach is 0.017 % over the whole temperature range from-10 • C to 80 • C, which is 173-times better than the traditional polynomial fitting method.
... For some applications it is enough if the frequency output is interpreted as voltage or electrical current, which is easily achievable using well known frequency to voltage converters. Nevertheless, an accelerometer with a frequency output offers desirable characteristics such as quasi-digital signals, high sensitivity, high resolution, wide dynamic range, anti-interference capacity and good stability (Huang et al., 2013). For these reasons, from a metrological point of view, the use of the signal with ABSTRACT In most aerial vehicles, accurate information about critical parameters like position, velocity, and altitude is critical. ...
In most aerial vehicles, accurate information about critical parameters like position, velocity, and altitude is critical. In these systems, such information is acquired through an inertial measurement unit. Parameters like acceleration, velocity, and position are obtained after processing data from sensors; some of them are the accelerometers. In this case, the signal generated by the accelerometer has a frequency that depends from the acceleration experienced by the sensor. Since the time available for frequency estimation is critical in an aerial device, the frequency measurement algorithm is critical. This chapter proposes the principle of rational approximations for measuring the frequency from accelerometer-generated signals. In addition, the effect of different measurement parameters is shown, discussed, and evaluated.
