Types Of Gyroscopes Research Articles

Structural Solutions that Increase the Dynamic Accuracy of a Wave Solid-State Gyroscope

The development of wave solid-state gyroscopes (VTG) is one of the promising areas of development of gyroscopic angular velocity sensors. VTG from the standpoint of manufacturing technology, tuning and control systems, as well as accuracy characteristics, has a number of advantages compared to other types of gyroscopes. When developing VTG, they strive to reduce the gyroscope's own care, zero signal bias, and the non-linearity of the scale factor in the operating temperature range However, when creating the device, due attention is often not paid to the existing opportunities to improve the dynamic accuracy of the gyroscope by developing promising structural solutions for building control circuits and information processing. The solution to this problem was the goal of the work.Using the methods of the theory of automatic control, the dynamics of a wave solid-state gyroscope with a metal resonator and piezoelectric elements in the closed-loop mode of Сoriolis acceleration compensation are studied. Piezoelectric elements perform the functions of displacement and force sensors.Two promising structural solutions for constructing VTG control and information processing circuits are proposed and considered. Relations are established for selecting the parameters of the links of these contours, which provide an increase in the dynamic accuracy of the gyroscope. In the first case, the proposed structure for constructing the VTG allows us to significantly reduce the dynamic errors caused by the difference in the scale coefficient of the VTG at different frequencies of the measured angular velocity in the bandwidth. Such a structure for constructing a VTG can be recommended when solving a measurement problem in which it is necessary to accurately measure the angular velocity, and the phase lag of the output signal in relation to the measured angular velocity is of secondary importance. In the second case, the proposed structure of the VTG construction corresponds to the transfer function of the relative measurement error with secondorder astatism, and the absolute measurement error in the frequency band of 10 Hz does not exceed 0.1 %.

Balancing of metal resonators of wave solid-state gyroscopes of general use

Wave solid-state gyroscopes (WSG) are among the most modern navigation devices. Based on the phenomenon of precession of elastic waves in thin-walled axisymmetric bodies, WSGs have a simple design, including 2-3 fixed parts, and have a number of advantages over other types of gyroscopes: great resource of work; small random error; resistance to severe operating conditions (overload, vibration, gamma radiation); relatively small overall dimensions, weight and power consumption; preservation of inertial information during short-term power outages. From the point of view of practical application and technologies used, three main groups of WSG can be distinguished. Wave solid-state gyroscopes of high precision. In such devices, high-quality (with a Q-factor of over 1·107) quartz resonators, contactless sensors and actuators, as well as complex electronic control systems are used. The field of application today, for various reasons, is limited to space technology, which requires, along with high precision, a long working life. Micromechanical devices of low accuracy for mass use (laptop computers, toys, industrial equipment, etc.) Integration of micromechanical WSGs with satellite systems makes it possible to create small-sized inexpensive navigation systems for widespread use. This market segment is developing very quickly, but production of such devices requires a very high the level of development of the microelectronic industry. An intermediate group consists of sensors of general use with metal resonators. Although these devices are larger than micromechanical devices, their production technology is much simpler. Metal resonators with a quality factor of (3 ... 5)∙104 can be manufactured using universal metal-cutting equipment; such devices have a simple design, do not require the creation of a high vacuum in their housing, and widespread radioelements can be used in control units. As a result, devices of this group, possessing insignificant power consumption and long working life, have a low cost price. On the other hand, the comparatively large dimensions of the resonator allow their precise tuning, which makes it possible to sharply increase the accuracy of the gyro instruments. From these points of view, a general-purpose WSG with a metal resonator is the most promising device that should replace the rotary-type electromechanical gyroscopes used today, and the production of which can be quickly mastered by the domestic industry. The development of such sensors requires solving a number of scientific and technical problems. Since all the main characteristics of such a device are determined by the properties of the resonator, special attention should be paid to its design and production technology. One of the most difficult and expensive operations in the WSG technology is the balancing of the resonator, carried out to eliminate the mass imbalance that arises during its manufacture due to inevitable deviations from the ideal axisymmetric shape (inhomogeneity of the wall thickness, displacement of the centers of the outer and inner surfaces, etc.). At a nonzero value of the 4th harmonics of the mass imbalance, a splitting of the natural frequency of the resonator occurs, leading to random errors in the WSG. A number of technologies are described in the literature to eliminate this mass defect [3-5]. The resonator balancing according to the first three forms of mass defect is much more difficult. Here, oscillations of the center of mass of the resonator occur during operation of the gyroscope and additional dissipation of the energy of oscillations of the resonator in the nodes of its attachment. This leads to a dependence of the Q-factor of the resonator on the orientation of the standing wave and, consequently, to a systematic error of the device. Thus, the aim of this work is to develop a technique and equipment for balancing metal resonators according to the first three forms of mass defect, suitable for use in the production of general-purpose WSGs.

An Efficient Hybrid Technique for Noise Reduction in Optical Gyroscope Signals

Gyroscopes are sensors that are used for motion measurement. They are generally used to measure rotation rate of moving equipment. There are different types of gyroscopes including mechanical, micro-electro-mechanical (MEMS) and optical gyroscopes. Gyroscope signal suffers from internal noise due to internal device operation and external noise of the environment. This paper presents a proposed hybrid technique that includes both Kalman filter and wavelet denoising. Results show the superiority of this proposed technique to the other filters. Arranging the filters in cascaded hybrid structure has an effect on the performance of the hybrid technique. Using Kalman filter as a first stage is better than using the wavelet as a first stage. For the comparison, two evaluation metrics are used: Signal-to-Noise Ratio (SNR) improvement and correlation coefficient.

Optimizing Strap-down Inertial Navigation Systems Characteristics and External Correction Sensors for Autonomous Navigation of Different UAV Classes

Currently, unmanned aerial vehicles (UAVs) can be used in topographic works, condition monitoring and diagnostics of extended engineering structures, delivering goods to hard-to-reach places, etc. To provide the widespread UAVs applications and raise the number of tasks to be solved through their using, it is necessary to increase their autonomy degree in terms of navigation support, in particular. Unmanned aerial vehicles (UAV) control systems for autonomous navigation use the strap-down inertial navigation systems (SINS) based on various types of gyroscopes. SINS based on the laser gyroscopes, which have a large mass, have the best accuracy. UAVs with a payload mass that is commensurable with the mass of navigation equipment require optimization of SINS characteristics. An optimization method has been developed to enable obtaining a Pareto set for the mass and accuracy of SINS based on laser gyroscopes. A comprehensive assessment of the characteristics of SINS and UAV carrier with different payload mass has been performed. Various SINS correction methods are considered when satellite navigation is unavailable.For overland flights, the correlation-extreme navigation systems (CENS) and SLAM methods (for simultaneous localisation and mapping) can be used. CENS require a reference lay-of-the-land description and a sufficient density of landmarks. In navigation based on SLAM algorithms, there is no need in the reference lay-of-the-land description, and the initial data can be obtained through the optical sensors under appropriate condition of the atmospheric path.Regardless of the condition of the atmospheric path, type of the underlying surface and its information available in detail, the UAV coordinates can be determined by Doppler dead reckoning using a Doppler system (DISS). At low and medium altitudes SINS correction is possible, only heading sensor data are needed to calculate the path angle.In combining with DISS and 3D Flash Ladar sensors (for implementing SLAM algorithms), it is more optimal to use low-accuracy SINS based on fibre-optic gyroscopes rather than laser gyro-based systems.The results obtained can be used when developing navigation systems for medium, light and heavy-medium UAVs.

The Correcting Approach of Gyroscope-Free Inertial Navigation Based on the Applicable Topological Map

The accumulated error and noise sensitivity are the two common problems of ordinary inertial sensors. An accurate gyroscope is too expensive, which is not normally applicable in low-cost missions of mobile robots. Since the accelerometers are rather cheaper than similar types of gyroscopes, using redundant accelerometers could be considered as an alternative. This mechanism is called gyroscope-free navigation. The article deals with autonomous mobile robot (AMR) navigation based on gyroscope-free method. In this research, the navigation errors of the gyroscope-free method in long-time missions are demonstrated. To compensate the position error, the aid information of low-cost stereo cameras and a topological map of the workspace are employed in the navigation system. After precise sensor calibration, an amendment algorithm is presented to fuse the measurement of gyroscope-free inertial measurement unit (GFIMU) and stereo camera observations. The advantages and comparisons of vision aid navigation and gyroscope-free navigation of mobile robots will be also discussed. The experimental results show the increasing accuracy in vision-aid navigation of mobile robot.

Approaches to the Calculation of Technical Characteristics of a Solid-State Wave Gyroscope

В настоящее время к чувствительным элементам навигационных систем предъявляются жесткие требования, для выполнения которых необходимо постоянно совершенствовать датчики первичной информации (гироскопы, акселерометры) по таким параметрам, как массогабаритные характеристики, точность, надежность, длительный рабочий ресурс. Эти требования стимулируют разработку новых типов гироскопов. К одному из таких новых типов приборов относится твердотельный волновой гироскоп. Для повышения точностных параметров реального изделия и сокращения сроков подготовки производства необходимо разработать математическую модель. Рассматриваются два подхода. Первый - аналитический, второй - численный. При получении аналитического решения предлагаемая математическая модель для полусферического чувствительного элемента создается на основе метода масс. Реальная пространственная конструкция ЧЭ приводится к плоскому кольцу для упрощения задачи и сокращения времени расчета. Применены допущения о жесткой связи определенного числа одинаковых масс по окружному направлению и упругой связи в радиальном направлении. Рассматривается идеальный случай. Проводятся аналитические преобразования с определенными допущениями для упрощения конечной зависимости. Второй подход к созданию математической модели основан на применении теорий собственных колебаний и метода перемещений для объемных тел при условии их упругого деформирования. Рассматривается идеальное осесимметричное тело, жестко защемленное за ножку резонатора. Материал ЧЭ считается изотропным и не учитывает историю обработки заготовки. Исследована с помощью полнофакторного эксперимента основная характеристика ЧЭ - собственная частота в зависимости от конструктивных факторов, чему и посвящена данная статья. Сделано предположение о возможности применения результатов численного эксперимента в аналитической модели для приближенных расчетов.

Three-Axis Attitude Estimation Using Rate-Integrating Gyroscopes

Traditionally, attitude estimation has been performed using a combination of external attitude sensors and internal three-axis gyroscopes. There are many studies of three-axis attitude estimation using gyroscopes that read angular rates. Rate-integrating gyroscopes measure integrated rates or angular displacements, but three-axis attitude estimation using these types of gyroscopes has not been as fully investigated. This paper derives a Kalman filtering framework for attitude estimation using attitude sensors coupled with rate-integrating gyroscopes. To account for correlations introduced by using these gyroscopes, the state vector must be augmented, compared with filters using traditional gyroscopes that read angular rates. Two filters are derived in this paper. The first uses an augmented state-vector form that estimates attitude, gyroscope biases, and gyroscope angular displacements. The second ignores correlations, leading to a filter that estimates attitude and gyroscope biases only. Simulation comparisons are shown for both filters. The work presented in this paper focuses only on attitude estimation using rate-integrating gyroscopes, but it can easily be extended to other applications such as inertial navigation, which estimates attitude and position.

Scalarization method in problems of elastic surface-wave propagation in rotating transversely isotropic half-space

The work objectives are to generalize the scalarization method of dynamic elastic fields in the transversely isotropic media to the tasks for the environments rotating with a constant angular velocity, and to develop the methodological apparatus for describing the effect of rotation on the parameters of surface acoustic waves. On the basis of this method, the scientific-methodical device for the construction of new acoustic-wave gyroscopes is proposed. Parameter determination ratios for surface-acoustic waves (SAW) propagating on the boundary of the rotating half-space of the transversely isotropic material with arbitrarily spaced axis of material symmetry are obtained and validated. An example of the numerical simulation for the isotropic rotating half-space case is given. The proposed methodological apparatus and numerical simulation examples can be used to develop new types of gyroscopes on acoustic-wave systems for navigation, guidance and control of various mobile objects in aviation, robotics, etc

The estimation error of azimuth of self-orientation SINS in action by the random pitching

The estimation of self-orienting strapdown navigation system (SINS) azimuth error of laser gyro influenced by random pitching has been done. Results are obtained without imposing any limitations on the signals of laser gyros, are generic and can be extended to SINS built on other types of gyroscopes: optical, fiber optic, dynamically configurable, micromechanical etc.

An Innovative Multimedia Learning Method As Applied to Theoretical Mechanics and Theory of Gyroscopes

Presented is an innovative method for science studies, which applies multimedia training systems with dynamic visualization software. The paper considers methodical aspects and experience in creation and application of multimedia computer technologies to lectures, practical courses, and express-testing as applied to theoretical mechanics and theory of gyroscopes. The main principles and features of the innovative method are described. The contents of lectures and practical courses is presented in a form of MS PowerPoint presentations and embedded dynamic visualization software. Computer simulation and dynamic visualization is provided for equations and operating principles for main types of gyroscopes, for kinematics and dynamics of various systems and well as for the phenomena of mechanical motion.

Experimental analysis and characterization of electrostatic-drive tri-axis micro-gyroscope

A planar micro-machined tri-axis gyroscope in decoupled-mode mechanical structure is presented, verified for superior detection capability and analyzed by experiments in this paper. Initially, the natural frequencies of sense modes are successfully tuned to match the natural frequency of drive mode by polarization voltages onto the associated sensing electrodes so that the inherent bias frequency at each sense mode can be removed. Secondly, the undesired cross-axis coupling effects between drive mode and sense modes are substantially suppressed by the cooperation of mechanical design and an integrated Automatic Gain Control (AGC) loop for drive mode. For highly reliable tuning to ensure resonance, the AGC and PLL (Phase Lock Loop) are integrated with a PID (Proportional, Integral and Differential) feedback controller to eliminate steady-state errors and overshoots. The performance of the micro-gyroscope is analyzed and evaluated by experiments. The achieved scale factors (the reflected voltage to the detected angular rate) of the proposed tri-axis micro-gyroscope are 50.4 μV/°/ s, 60.3 μV/°/ s, and 71.2 μV/°/ s for X-, Y- and Z-axes (principal axis: Z-axis) respectively. The resulted resolutions are about 0.72 ° / s / Hz , 143 ° / s / Hz and 0.42 ° / s / Hz for X-, Y- and Z-axes respectively. The Cross-axis sensitivities are reduced down to 22%, 9% and 1.84% for X-, Y- and Z-axes respectively. S/N ratios reach 59.3, 13.8, and 140.1 for X-, Y- and Z-axes respectively. The experimental results illustrate that the gyroscope exhibits superior to detect exerted angular rate, in addition to successful suppression upon the cross-axis perturbation between drive mode and sense mode. Principle-axis sensitivity, resolution and floor noise are all numerically evaluated. Further more, cross-axis sensitivity, Signal-to-Noise Ratio (SNR) and measurement error are investigated. Finally, a few comparisons with the other typical types of gyroscopes are reported.

Coupled vibration and parameter sensitivity analysis of rocking-mass vibrating gyroscopes

Vibrating beam gyroscopes are widely used to measure the angle or the rate of rotation of many mechanical systems. The vibration and parameters sensitivity analyses of a specific type of vibrating beam gyroscope namely rocking-mass gyroscopes are presented in this paper. These types of gyroscopes by far have a better performance than the conventional single-beam gyroscopes. The system comprises of four slender beams attached to a rigid substrate, undergoing coupled flexural and torsional vibrations with a finite mass attached in the middle. Two of the beams carry piezoelectric patch actuators on top, while the other two possess piezoelectric patch sensors. Using extended Hamilton's principle, the resulting eight coupled partial differential equations of motion with their corresponding boundary conditions are derived. In spite of the need for a high computational power, the system is analysed in the frequency domain using an exact method and the closed-form characteristic equations for two cases of fixed and rotating base support are obtained. Furthermore, a detailed parameter sensitivity analysis is carried out to determine the effects of different parameters on the complex natural frequencies of the system. Results presented are valuable in the design of this type of gyroscope as the exact resonant conditions and the sensitivity of the system parameters play important roles in the dynamic performance of gyroscopes.

Construction and characterization of interferometric fiber optic gyroscope (IFOG) with erbium doped fiber amplifier (EDFA)

Gyroscopes, which sense changes on absolute angular rate and are classified into Interferometric Fiber Optic Gyroscopes (IFOG), Ring Laser Gyroscopes (RLG) and Micro- Electro-Mechanical Systems (MEMS) Gyroscopes, are critical components of the navigation systems together with accelerometers. Being dominant over other types of gyroscopes in terms of performance and cost, IFOGs have widely been used in metrology and in particular defense/aerospace industry. This paper covers the design details of both optical and electronic components of IFOG prototype, the sensing mechanism of which is based on Sagnac Phase Shift, constructed in Optics Laboratory of National Metrology Institute of TURKEY as absolute angular rate sensor. In the prototype IFOG, open-loop configuration was applied, a single mode telecommunication optical fiber and an EDFA pumped by DFB laser emitting at 1549.0 nm were used as sensing coil and broadband source, respectively. The voltage data carrying Sagnac Phase Shift was extracted by a phase tracking circuit consisting of an active RC band pass filter, an amplifier with adjustable gain and an AD630 balanced modulator chip which was operated as lock-in. For the prototype IFOG, peak to peak noise of 8 (°/h) and bias stability of 1.57 (°/h) were attained respectively. Moreover the scale factor of 13.83 (°/h)/mV was derived with deviation of 0.73%.