With the rapid development of military ground unmanned platform(GUP) technology, demands for better navigation systems for features such as high autonomy and intelligence are improved significantly. Apart from typical positioning and orientation determination, the ability of environmental sensation is especially needed. By equipping various sensors, the importance of INS based multi-sensor fusion technology is elevated. In this paper, the main INS-based navigation methods are studied and sorted out based on the requirement of GUPs. Basic principles and state of the art of INS/odometer, INS/visual, INS/lidar integrated navigation technologies are introduced respectively. The development trends of those navigation technologies that are suitable for GUPs are prospected.

In modern military applications, the main function of long-range missiles is to accurately strike pivotal military targets, which makes guidance precision a chiefly performance measure of missiles. Nowadays, the central inertial instruments used for long-range guidance weapons interiorly and overseas is inertial navigation platforms(INPs). The INP frame could rotate the inertial measurement unit(IMU) to realize self-alignment and self-calibration before missiles launching. During the flight of missiles, the INP stabilize the IMU in inertial space to improve the accuracy of inertial instruments by isolating the angular motion, which makes INPs become most preferred inertial instrument for long-range guidance system. Domestic INP technology has been developing since 1960s, and has experienced the development of ball bearing gyroscope platforms, air-floating gyroscope platforms, dynamically tuned gyroscope platforms, liquid-floating gyroscope platforms, and three-floating gyroscope platforms. At recent, the new types of long-range missile mainly adopt three-floating gyroscope INPs based on three-floating gyroscopes and gyroscope accelerometers. The key technologies of three-floating gyroscope INPs include sub-micron machining and assembly of special materials, high-reliability three-floating inertial instrument technology against high overload environments, inertial/astronomical integrated guidance, and INPs self-alignment and self-calibration technology. In recent years, the engineering application precision of novel inertial instruments, represented by optical gyroscopes and hemispherical resonator gyroscopes has gradually improved. Based on the INPs stability control technology, constructing novel structures of INPs using new types of solid-state gyroscopes will rapidly promote the development of domestic long-range weapons. By analyzing the technical advantages of fiber optical gyroscopes, hemispherical resonator gyroscopes and other novel inertial instruments, considering the performance requirements for miniaturization, digitalization, and intelligence of the future guidance systems, several suggestions are proposed to develop domestic INP technology.

The rapid development of image acquisition equipment has brought about a rapid increase in the number and type of images. Vision systems such as image stitching and fusion have increased the technical requirements for image registration. Image registration technology uses original image data or image feature information to transform and align the overlapping regions of the input images, which is the core technology for providing operational benchmarks for the follow-up image processing tasks such as image stitching and image fusion. It is a hot research topic in the current computer vision field. Firstly, the main application areas and major development prospects of image registration technology are introduced. Then, the basic framework and technical difficulties of image registration technology are explained. The implementation algorithms and key technologies of feature-based and region-based image registration technology are summarized. The advantages, disadvantages and applicability of different registration algorithms are analyzed. The development prospects of image registration technology are discussed and prospected.

In the future complex battlefield environment, the cooperative combat system composed of multiple unmanned aerial vehicles(UAVs) in flight space is the key to achieve the victory of intelligent air combat. Firstly, the definition of UAV is expounded, and its connotations and classifications are analyzed. It is pointed out that intelligentization is the future development direction of UAV, which is classified according to the capability of autonomous mission completion. Then, typical cooperative combat styles are introduced, and the development status of cooperative combat of both domestic and abroad is expounded. The key technologies restricting cooperative operations are analyzed from the aspects of cooperative situational awareness technology, interactive and information warfare cloud technology, intelligent decision-making technology, independent attack technology, cluster cooperation technology and learning and evolution technology

The research on artificial intelligence image classification methods based on deep learning is a hotspot in the computer vision field. Aiming at the Softmax image classification method in deep learning, the development of image classification technology is firstly reviewed in this paper. Then, the classifiers in image recognition technology are introduced and the classification principle of Softmax regression function is given. Furthermore, several image classification techniques based on the application of Softmax regression classifier are described in detail, including shallow neural network, deep belief network, deep autoencoder network and convolutional neural network. Simultaneously, the concrete structure, training method, practical application, classification effect, advantages and disadvantages of above four cascade models are introduced. Finally, the development and application prospects of the deep learning model based on Softmax classifier in image classification are prospected from three aspects: Softmax regression classifiers, deep learning network model and high-dimensional data classification.

Micro hemispherical resonator gyroscope(μHRG) is a new type of vibration gyroscope which is based on the technology of MEMS to achieve manufacturing of high precision resonator structure, and then angular rate or angular signal measurement is realized. This technology is expected to inherit the advantages of high precision and long lifetime of traditional hemispherical resonator gyroscopes(HRG), and has the technical advantages of miniaturization, so it has great potential for development. At present, the μHRG technology is in infancy. The research mainly focuses on the manufacturing technology of high precision resonator structure. In this paper, several manufacturing methods of μHRG are introduced, its technical characteristics are analyzed, and its future development trend is described based on the development status of μHRG technology at home and abroad.

Spin-exchange relaxation-free(SERF) magnetometer which utilizes SERF mechanism of the spin of alkali metal atoms to detect weak magnetic fields, has become a research hotspot in precision magnetic field measurement technology because of its ultra-high sensitivity, little volume, and low consumption. The basic principle of the SERF atomic magnetometer and its research status at domestic and oversea are introduced in this paper. The key technologies such as the manufacture of atomic vapor cell with long spin relaxation time, nonmagnetic heating of the vapor cell, and high precious compensation of the remaining magnetic field are analyzed in detail. At last, the tendency and application prospect of SERF atomic magnetometer are forecasted.

In recent years, the development of foreign navigation technology has shown a multi-system integration development trend. In combination with the development of foreign navigation technology in 2019, the current status of technology developments in satellite navigation, inertial navigation, astronomical navigation, visual navigation, database matching navigation, bionic navigation, quantum navigation, and all-source navigation in the United States, European Union, Russia, and India are summarized and analyzed, and the development of related technologies are prospected.

Few-shot learning refers to the method of deep learning training and prediction under the condition of insufficient or low-quality sample data. Aiming at the problem of insufficient sample data that may be faced in the application of deep learning object detection, the mathematical model and error source of few-shot object detection are analyzed firstly. The methods applicable to few-shot object detection are given in three categories: data, model and algorithm, and the shortcomings of each scheme are attached. Based on the practical exploration of few-shot object detection, the recent attempts along with their results are enumerated. The other applications of deep learning similar to few-shot learning are also briefly introduced. Then, after analyzing the existing problems in few-shot detection, the development direction and research trend of few-shot object detection in the future are discussed.

The alkali metal atomic vapor cell is the core component of quantum devices such as atomic gyroscope, atomic magnetometer and atomic clock. High performance micro-miniature atomic vapor cell is one of the important factors restricting the developments of the above quantum devices. In this paper, the research progress of the atomic vapor cell from the aspects of theoretical research, manufacturing technology and bulb material is summarized. The key technologies are analyzed and discussed, such as optical precision machining of glass micro cell, precise filling technology of alkali metal and gas mixture, high-temperature antirelaxation surface coating technology, cure technology with bake process. In view of micro-miniature, high-precision, integrated design for quantum devices, the development trend of alkali metal atomic vapor cell is also outlined.

Automatic guided vehicle (AGV) is one of the key equipment of the modern automation logistics system, it is powered by battery, and equipped with the electromagnetic or optical automatic navigation equipment. AGV can automatic address independently, complete the unpiloted travel and tasks by the control of computer. The paper introduced the evolutions of AGV at home and abroad, introduced the principles and applied fields of AGV system, discussed the key technologies and the new fruit of AGV, provided a foundation plat form for the future better application of AGV.

Due to the fact that satellite navigation systems can not penetrate physical obstructions and are susceptible to be interfered, and the accumulation of errors in inertial navigation systems are prone to diverge, traditional inertial/satellite integrated navigation systems are increasingly difficult to meet the needs of navigation accuracy, so multi-sensor integrated navigation system arises at the historic moment and develops continuously. In multi-source navigation system, how to fuse the data of different sensors efficiently and reliably is the core of the system. In engineering practice, the federated Kalman filtering is the most common method. However, it is not able to handle asynchronous heterogeneous aperiodic signals and nonlinear problems. Recently, a increasing more attention has been focused on the factor graph algorithm. Therefore, the application of factor graph in multi-source integrated navigation system and the future development direction are summarized.

As a typical representative of the integrated innovation of ring laser gyroscope technology, space triaxial ring laser gyroscope has fully demonstrated its superior comprehensive performance. For a comprehensive understanding and mastering space triaxial ring laser gyroscope technology development status, this article combs the space triaxial ring laser gyroscope principle and the composition, main features, key technology and research, and analyzes the major foreign typical product spectrum and application status, research institutions. It could be seen that the space triaxial ring laser gyroscope is already very mature and widely used abroad. Focusing on the gap between domestic development status, the following development suggestions are put forward, which could be a reference for the development and industrialization of ring laser gyroscope in China.

Gyroscope is the core device in inertial navigation system. This article firstly reviews the history of traditional gyroscopes, and introduces the basic principles as well as advantages and disadvantages of various types of gyroscopes. Then, the current development status of traditional gyroscopes in attractive attention, accuracy, cost and application is summarized and compared. Finally, the future development of the gyroscope is prospected. It is hoped that this paper will have a certain reference significance for the study of the gyroscope.

Accelerometers have been widely used in consumer electronics, industrial monitoring, inertial navigation and natural resource exploration fields. Compared with conventional accelerometers, the emerging optomechanical accelerometer has the advantages of high precision and miniaturization. It is combined optomechanical effects, microcavity photonics and MEMS technology, it is promising to be next-generation high-precision accelerometer. In this paper, different types of optomechanical accelerometers based on optical levitation and optical microcavity are introduced, the working principles, transduction mechanism, advantages and disadvantages are analyzed. In addition, the research status and development trend of optomechanical accelerometer abroad is summarized, which might provide reference information for relevant researches in China.

Hemispherical resonator gyroscope(HRG) is a new type of solid vibrating gyroscope with high precision, high reliability and long lifetime. It has a wide application prospect. As the core part of HRG, quartz hemispherical harmonic oscillator has thin wall, complicated shape, high precision requirement and difficult manufacturing. This is the key to restrict the development of HRG. Based on the technical development of HRG, the structure types and characteristics of HRG are analyzed. The machining methods and research progress of quartz hemispherical harmonic oscillator, such as rough grinding forming, precision grinding, grinding and polishing, chemical corrosion, mass adjusting and surface coating, are introduced. At last, the emphases and proposal of HRG future study are proposed.

The first part of this review summarizes various underwater navigation technologies developed in recent decades based on different requirements in other countries. Methods to transfer surface navigation information to underwater environment are described. Characteristics and problems of each correlation navigation method utilizing geophysical parameters as well as geographical positions are discussed respectively. Underwater SLAM navigation technology with regard to its unique underwater characteristics including interconnecting sensors and monitoring objectives during sea floor mapping, gravity and other geophysical parameter measuring is described. A general-purpose tool software, NavLab, which plays a unique role in underwater navigation system including precision analysis, pre-work navigation function planning and navigation information post-processing is discussed. In the second part of this review, the Norwegian HUGIN AUV series is introduced as an example for dual use in military and civil applications. Typical navigation modes and sensors selected from “navigation toolbox”, are described according to the task and navigation function requirements. In the end of the paper, future forecasting of underwater navigation technology is given based on AI technology.

Laser strapdown inertial navigation is widely used in missiles, ships, aircraft and rockets. At present, there is a lack of research on its performance in high dynamic environment such as large overload, large angle coning and linear angular vibration. Aiming at the problem of the accuracy decline of laser strapdown inertial navigation in high dynamic environment, the dynamic error mechanism of laser strapdown inertial navigation and the key technologies to improve the dynamic accuracy from inertial devices, vibration reduction and algorithm are summarized in this paper. The valuable research progress in recent years is introduced, and the ways to improve the dynamic accuracy in the future are briefly discussed.

Spacecraft is a vehicle fighting in extra-atmosphere, and also includes some earth reentry vehicles. During flight, inertial technology is critical important to assist the spacecraft to determine its attitude and velocity increment. As the missions become more complex, the application fields of inertial sensors expand rapidly and cover high precision attitude determination, inertial navigation, integrated navigation, et al. On this background, the development context of inertial technology for spacecraft is discussed in this paper, including the category of usage, present situation and future needs.

Microwave sensors are now widely used in commercial, military, surveying and other fields. However, traditional sensors are unable to meet the actual demands and a new type of microwave sensor is needed to realize the measurement of weak fields. Traditional microwave dipole sensor has some disadvantages such as low sensitivity, calibration required during measurement, the built-in antenna perturbation effect, and the narrow working frequency band, so a Rydberg atom-based microwave sensor is introduced in this paper. This kind of sensor can not only detect the weak fields better, but also transmit baseband signals to achieve the purpose of wireless communication. Rydberg atom-based microwave sensor is introduced in detail from the basic physical principle, which is of great significance for mastering the basic knowledge of microwave weak field detection principle and technology and for further promotion and application.

This essay focuses on the importance of inertial technology, which is proposed as one of the core technologies of autonomous navigation and guidance for air defense missiles. The development history of inertial technology for anti-aircraft missiles is reviewed, and the requirements of anti-aircraft missiles for inertial technology are summarized from the aspects of rapid response, working environment and measurement accuracy. In addition, the author also recommends three key technologies in inertial sensors, alignment technology of moving base, and high-precision autonomous navigation. Finally, the trend of inertial technology for anti-aircraft missiles is analyzed from the aspects of new inertial sensor technology, new materials and technologies, new application scenarios and new requirements. The development direction of air defense missile inertial technology is prospected from engineering application.

In recent years, marine unmanned small platforms have gradually become an indispensable tool for human activities such as marine research and exploration. With the implementation of the "maritime power" strategy, the navigation and positioning technology of underwater platform has become an important guarantee for maintaining territorial sea security, developing marine economy and performing a series of underwater tasks. At present, the navigation and positioning methods of these platforms mostly adopt the integrated navigation mode dominated by inertial navigation technology and supplemented by underwater acoustic positioning and geophysical navigation technology. The inertial/underwater acoustic integrated navigation is the main means of underwater target positioning and tracking. In this paper, the application status of inertial/underwater acoustic integrated navigation system at home and abroad is given firstly. Then, the research progress of underwater navigation and positioning key technologies is summarized. The application requirements and development trend of underwater unmanned small platform integrated navigation and positioning systems is analyzed finally.

Quartz vibrating beam accelerometer(QVBA) is a kind of novel solid-state inertial sensor based on quartz vibrating beam and force-frequency characteristics. QVBA has many outstanding advantages, such as high precision, wide range, low power consumption and direct frequency output without I/F converter, and has been widely used in tactical weapon system. In this paper, the working principle and technical characteristics of QVBA are briefly introduced, the research status and key technology for the separated structure and monolithic structure of QVBA are summarized. Based on the development trend abroad, it is pointed out that QVBA will be the most possible accelerometer scheme to achieve the precision and radiation resistance of pendulum integral gyroscope accelerometer and meet the needs of strategic level.

Scientific progress has promoted the development of new theories, new thinking, new mechanisms and new structures of inertial technology. The competition in equipment has prospered new methods and ways of inertial technology applications, new markets and new application models, and the accuracy of inertial instrument performance has been rapidly improved. Since the 20th century, two quantum technology revolutions are in the ascendant, which promotes the rapid development of inertial technology. Experts in the field of inertial around the world have taken demand as the traction, with the aim of improving accuracy, actively promoting the key technology research of basic inertial technology, actively exploring new mechanisms, innovating and expanding new functional applications. At present, based on the traditional mechanical rotor gyroscope, summarizing the accumulation and sublimation transition, innovation has promoted the birth of many new inertial technical instruments such as optical interference and quantum entanglement. Inertial technology has ushered in a new era of quantum+artificial intelligence based on quantum information and big data, and has obtained a new opportunity of rejuvenation and prosperity. The development process and current situation of inertial technology has been analyzed in this paper, some cognitions and thoughts for consultation and reference of technical workers in the field of inertial has been put forward.

The error sources of the inertial navigation test equipment, the exciting errors of the motion parameters and the error propagation method are reviewed in this paper. The method of precisely exciting of motion parameter represented in the inertial instrument coordinate system is introduced. Error automation compensation, error restrain method and error appraisal method of inertial instrument is also reviewed. Finally, the development trend of the calibration method of inertial instrument is expounded.

The developments and changes in inertial related foreign agencies are introduced in detail. Then the developments and applications of inertial instruments and systems of different research institutes in recent years are summarized from the aspects of ring laser gyro(RLG), fiber optic gyro(FOG), MEMS gyro, hemispherical resonant gyro(HRG) and atomic gyro, Northrop Grumman, Honeywell Aerospace, Safran Electronics & Defense and iXblue for instance. The development of GPS and the new progress of some projects under the environment of GPS denied are analyzed considering the severe situation of GPS. Finally, the developments and applications of different gyro technologies are compared, the trend of inertial technology is summarized.

For the complex marine environments, such as shallow water, contaminated sea area and polar region, the traditional marine survey methods have a high labor intensity and safety risk with low efficiency. The unmanned surface vehicle(USV) is suitable for the aforementioned complex marine environments for its advantages of unmanned and efficient. In recent years, it has been rapidly developed and widely used in marine survey field. Focusing on the advantages of USV in marine survey, worldwide typical USVs and application cases, this paper deeply analyses the current status of marine survey with USV in China, and forecasts the future directions of this technology. Practice shows that USV is basically mature for the hydrographic survey. Both the bathymetric data quality and the autonomous navigation accuracy could meet the requirements of the specifications. In the future, USV should be further extended to physical oceanography, marine biology, marine chemistry, etc. Meanwhile, the long voyage USV developing using renewable energy should be accelerated for the worldwide marine survey missions.

Bases on the development and evolution history of Aircraft Avionics System, the integration evolution process and the main features of the new Aircraft avionics system are summarized, the architectural trend of the new integrated avionics system are researched. Finally, the key technology of raised avionics system integration level is brought forward.

An alkali metal atomic vapor cell is the core component of atomic measuring instruments such as atomic gyroscope, atomic magnetometer and atomic clock. The atomic density is mainly affected by the heating temperature, the highly uniform and stable vapor cell heating structure is the key technology to ensure the stability of the alkali metal atom density, and it is essential to improve the sensitivity of the output signal of the atomic measuring instrument. In this paper, the heating methods for alkali metal vapor cell are reviewed. For the heating layer, heat transfer layer, insulation layer and other components, the development direction and process of alkali metal vapor cell heating structures are summarized, the future development trend of alkali metal vapor cell heating structure is also prospected.

Aiming at the strong confrontation, nonlinearity, diversification and other operational situation requirements of future underwater unmanned systems, the large displacement unmanned underwater vehicle(UUV) is taken as the carrier platform, which leads to the summaries on the internal logic relationship of overall performance, overall structure, energy supply, power propulsion and navigation control under the combat technical index of UUV. The overall work flow of UUV inertial multi-source autonomous navigation and the extended Kalman filter model are designed. The future technical development trend of large displacement UUV is put forward, which provides a basic idea for large UUV long endurance autonomous navigation.

The inertial technology is a measure to independently establish the attitude benchmark of a carrier in motion through an inertial sensor, which is sensitive to the moving information of the carrier. With the development of modern electro-optical(EO) detection technology, the application of EO weapons and equipment in reconnaissance, surveillance, positioning, navigation, and communication has become more and more extensive, and the role of inertial technology in EO technology and EO equipment is becoming more important. In this paper, the development of the EO detection technology, the typical airborne EO system and inertial technology are introduced. The application status of inertial technology in EO detection technology is introduced in detail, and the improvement it brings about to the operation mode and operation efficiency is analyzed. The potential application demand of inertial technology in EO detection technology in the future and its development trend are illustrated.

Because of the characteristics of irradiation and thermal insensitivity of photonic crystal fiber (PCF), it becomes an important technical approach to adapt the space environment for fiber-optic gyroscope (FOG) by applying photonic crystal fiber which is called photonic crystal fiber optical gyroscope (PC-FOG). This can be used to reduce volume and weight and power consumption of FOG. In this paper, the mechanisms photonic band gap PCF (PBG-PCF) and total internal reflection PCF(TIR-PCF) were discussed first and the theory of PC-FOG was also investigated. The pivotal technology of PC-FOG was researched and the development was expatiated too.

Marine/aviation gravity measurement is based on the dynamic relative gravity measurement of a mobile platform. It refers to the gravimetric measurement method for measuring the gravitational acceleration in the sea or near ground by using a gravimeter or an accelerometer on a manned ship or an aircraft. This paper introduces the application field of gravimeters, for mobile marine/aviation gravimeter, and the vehicle test of marine/aviation gravimeter, the current situation of the foreign and domestic development is elaborated comprehensively. It also points out that the problem that the unmanned gravity measurement technology and deep sea dynamic gravity measurement technology urgently to be solved, and analyzes the development direction of our country in the field of marine/aviation gravity measurement.

There is great amount of noise in the point cloud data acquired by single photon lidar, which brings challenges for data processing. Firstly, based on the local distance statistics, an improved point cloud de-noising algorithm is proposed to de-noise the original point cloud data of single photon lidar. Then, based on the statistical analysis method, an improved point cloud filtering algorithm is proposed to filter the de-noised point cloud data. The ground point cloud obtained after filtering algorithm is compared with digital terrain model(DTM) obtained from traditional lidar for quantitative evaluation of filter results. Calculation results show that the RMSE between MABEL ground point cloud and traditional lidar is 2.98m, and the correlation coefficient is 0.9938. Furthermore, linear digital elevation model(DEM) is obtained through interpolation of ground point cloud, the RMSE between linear DEM and traditional lidar is 2.85m and the correlation coefficient is 0.9931. Experiment results showed that single photon lidar point cloud processing results has a good correlation when compared with DTM data from traditional lidar. Thus, single photon lidar can provide accurate topographic information.

According to the operating speed and temperature range, aerospace bearings can be lubricated by solid, oil or grease lubricant. Aerospace bearings work under light load conditions, and the failure is generally due to the film breakdown caused by lubricant loss and degradation, and the increased wear lead to the loss of bearing accuracy. The expectancy during the bearing service period is the accuracy life, also called wear life. The failure factors, failure criteria, wear life model, accelerated life test and the residual life prediction based on performance degradation are summarized in different lubrication conditions. The shortcomings of the current study are summed up and the points need for attention and further research are put forward.

The quantum sensor based on the cold atom interferometer has a high theoretical accuracy and is widely used in various fields of natural science, especially in the field of gravity measurement and inertial sensor. In this paper, the basic principle of atom interferometer is firstly introduced. On this basis, the interference phase of a pulsed Mach-Zehnder interferometer based on two-photon stimulated Raman transition is given. Then, the application and development course of atom interferometer in gravimeter and gyroscope are described. The development course and trend of the most mature atom gravimeter are analyzed emphatically. At last, the development direction of the atom interferometer in application is pointed out.

The atomic antenna is constructed using the room temperature Cesium Rydberg atom. The response characteristics of the atomic antenna to radio frequency(RF) signals in 30MHz~40GHz are explored. In the experiment, the Rydberg atom is prepared by 852nm and 509nm two-photon excitation scheme. The electromagnetic induced transparent(EIT) spectroscopy is employed to sense the RF wave. The broadband RF wave response characteristics of 66S_1/2, 66D_5/2 and 76D_3/2 Rydberg states are investigated. It is found that the measurement signal in the region of near dipole resonant RF field is strong, but weak in the far from resonant region, where the measurement is mainly realized by AC Stark shift. The system achieves a sensitivity up to -110dBm/Hz±2dBm/Hz, and the linear dynamic is 40dB. Among them, 66S_1/2 and 66D_5/2 Rydberg states have a detection insensitive area at 30GHz. The dipole resonance transition of 76D_3/2 quantum state is evenly distributed in the range of 30MHz~40GHz, and no obvious insensitive area in the experiment.

Optically-pumped atomic magnetometer(OPAM) based on the light-atom interactions achieves high-sensitivity measurement of magnetic field. In this paper, the basic principle, scheme and development of OPAM are introduced. The concepts and influencing factors of the main technical indicators for OPAM, such as sensitivity, accuracy, dead zone, heading error, range of measurement, and bandwidth are discussed. The development of the core key technologies of optical sources and atomic cells, especially the high-stable atomic lamp and laser optical sources technology, anti-relaxation coating and multi-pass atomic cells technology, are introduced emphatically. Finally, the practical applications of OPAM technologies in airborne, ground, marine and space magnetometries are discussed.

In swimming posture measurement, due to the absorption and refraction of various signals by water, sensors relying on external information can not provide accurate information. Inertial technology is suitable for swimming posture measurement because it does not rely on external information. Inertial attitude measurement needs the initial value provided by the initial alignment technology to calculate the attitude in the process of swimming. However, the take-off time of swimmers is uncertain, and the traditional initial alignment algorithm takes a long time to get a high-precision result. In order to solve this problem, a fast alignment method based on Mahony algorithm is proposed, which uses MEMS nine-axis inertial measurement unit to collect information. The attitude angle is calculated through angular velocity information, the horizontal attitude angle is corrected by acceleration information, and the yaw angle is corrected by magnetic field strength information. The multi-source information is fused by complementary filtering method, so as to quickly obtain the initial value of inertial attitude measurement. Laboratory experiments show that the horizontal accuracy of attitude angle can reach the minute of arc level within 3s, which meets the requirements of swimming. The feasibility of the algorithm is verified by the test in the actual motion scene.

Solar arrays are always used by long-lived triaxial stabilized satellites for energy supply, and solar array drive assemblies have to be used to align the solar array for accurate tracking of the sun. Since 1960s, the international development of the new solar array drive mechanism and electronics to meet its special needs, such as high power, miniaturization and harsh environment adaptability, as well as other needs, has gone through 3 to 4 generations of development, with its great progress. Based on the relevant information and data collected, the paper tries to analyze the corresponding application, research focus and development direction in this field, by introducing the international typical product with their corresponding demand in this area.