Search Results (234)

This paper proposes a method for solving mazes, with a special focus on navigation using image processing. The objective of this study is to demonstrate that a robot can successfully navigate a maze using only two-wheel encoders, enabled by appropriate control strategies. This method significantly simplifies the structure of mobile robots, which typically suffer from increased energy consumption due to the need to carry onboard sensors and power supplies. Through experimental analysis, it was observed that although the encoder-only solution requires more advanced control knowledge, it can be more efficient than the alternative approach that combines encoders with a gyroscope. In order to develop an efficient maze-solving system, control theory techniques were integrated with image processing and neural networks in order to analyze images in which various obstacles were transformed into maze walls. This approach led to the training of a neural network designed to detect key points within the maze. Full article

This study examined the design and optimization of low-speed external frame motors featuring Halbach-type and olive-shaped magnet structures to improve performance in spacecraft control moment gyroscopes (CMGs). Our research was driven by the urgent need for precise, high-torque, low-speed motors in CMGs, where conventional designs, including Halbach-type and traditional radial magnet configurations, are hindered by manufacturing complexity and excessive torque pulsation. This study focused on optimizing rotor pole configurations to enhance efficiency and torque stability. An olive-shaped magnet structure provides a more uniform magnetic field distribution in the air gap, substantially reducing magnetic field harmonics and minimizing cogging torque and torque pulsation—critical performance factors for low-speed applications. Comparative analysis reveals that the olive-shaped motor achieves a peak torque of 0.312 N·m with a torque pulsation of 0.9 mN·m, maintaining an amplitude below 0.3%. This demonstrates a 20% improvement compared to the Halbach-type motor’s torque pulsation of 1.15 mN·m. Moreover, the olive-shaped motor exhibits superior stability in air-gap magnetization under different loads, ensuring high efficiency and robust operation. By streamlining magnet assembly while enhancing electromagnetic performance, this study offers a cost-effective, high-precision solution for CMG systems. These findings underscore the olive-shaped magnet motor’s potential to advance motor technology for aerospace applications. Full article

This study introduces a flywheel rotor support structure for an active magnetic suspension flywheel energy storage system. In this structure, there is an axial offset between the axial-bearing position and the mass-center of the flywheel rotor, which affects the tilting rotation of the flywheel rotor and which causes the coupling between its tilting rotation and radial motion. Therefore, the influence of the bearing position on the vibration characteristics of the flywheel rotor is explored in this paper. The tilting rotation constraint of the flywheel rotor by axial active magnetic bearing (AAMB) is analyzed, and the radial active magnetic bearing (RAMB) is equivalently treated with dynamic stiffness and dynamic damping. Based on this, a dynamic model of the active magnetic suspension rigid flywheel rotor, considering the position parameter of the axial bearing, is established. To quantify the axial offset between the position of the AAMB and the mass-center of the flywheel rotor, the axial-bearing position offset ratio γ is defined. The variation trend of the vibration characteristics of flywheel rotor with γ is discussed, and its correctness is validated through experiments. It is indicated that, with the increase of γ, the second-order positive precession frequency of the flywheel rotor decreases obviously, and the influence of the gyroscope torque gradually weakens. Meanwhile, its second-order critical speed ω_2c decreases significantly (when γ is 0.5, ω_2c decreases by about 62%); ω_2c corresponds to the inclined mode, revealing that the offset ratio γ has a prominent influence on the critical speed under this mode. In addition, as γ increases, the mass unbalance response amplitude of the flywheel rotor under the speed of ω_2c decreases significantly. The reasonable design of the axial-bearing position parameter can effectively improve the operational stability of the active magnetic suspension flywheel energy storage system. Full article

Hemispherical resonator gyroscopes (HRGs) are critical components in high-precision inertial navigation systems, typically used in fields such as navigation, weaponry, and deep space exploration. Film thickness uniformity affects device performance through its impact on the resonator’s Q value. Due to the irregular structure of the resonator, there has been limited research on the uniformity of film thickness on the inner wall of the resonator. This study addresses the challenge of thickness non-uniformity in metallization coatings, particularly in the meridional direction of the resonator. By integrating COMSOL-based finite element simulations with reinforcement learning-driven optimization through the Proximal Policy Optimization (PPO) algorithm, a new paradigm for coating process optimization is established. Furthermore, a correction mask is designed to address the issue of low coating rate. Finally, a Zygo white-light interferometer is used to measure film thickness uniformity. The results show that the optimized coating process achieves a film thickness uniformity of 11.0% in the meridional direction across the resonator. This study provides useful information and guidelines for the design and optimization of the coating process for hemispherical resonators, and the presented optimization method constitutes a process flow framework that can also be used for precision coating engineering in semiconductor components and optical elements. Full article

Based on the relevant theories of structural dynamics, this study fully considers the coupling effects between subsystems resulting from the design of inward and outward vibration stiffness parameters in a two-stage vibration isolation system. A dynamic transmission characteristics model of the two-stage vibration isolation system in response to external vibration environments has been established. The theoretical derivation of the impact of the external vibration environment on the core IMU components of laser inertial systems has been completed. Utilizing a method for calculating the dynamic coupling coefficients of the two-stage vibration isolation system, this research provides a theoretical basis for the parameter design and improvement of the vibration isolation system used in laser inertial products. Guided by this theory, a two-stage vibration isolation system was designed, ensuring a rational distribution of output frequencies and the root mean square (RMS) acceleration responses of the IMU components across the entire frequency range. Finally, flight tests were conducted, and the results demonstrate that the two-stage vibration isolation system, designed based on this dynamic transmission characteristics model, can effectively mitigate the normal jitter of the laser gyroscope while achieving significant attenuation of the RMS acceleration response of the IMU components across all frequency ranges, thereby ensuring the output precision of the inertial products. Full article

This study proposes a novel parallel denoising and temperature compensation fusion algorithm for MEMS ring gyroscopes. First, the particle swarm optimization (PSO) algorithm is used to optimize the time-varying filter-based empirical mode decomposition (TVFEMD), obtaining optimal decomposition parameters. Then, TVFEMD decomposes the gyroscope output signal into a series of product function (PF) signals and a residual signal. Next, sample entropy (SE) is employed to classify the decomposed signals into three categories: noise segment, mixed segment, and feature segment. According to the parallel model structure, the noise segment is directly discarded. Meanwhile, time–frequency peak filtering (TFPF) is applied to denoise the mixed segment, while the feature segment undergoes compensation. For compensation, the football team training algorithm (FTTA) is used to optimize the parameters of the long short-term memory (LSTM) neural network, forming a novel FTTA-LSTM architecture. Both simulations and experimental results validate the effectiveness of the proposed algorithm. After processing the MEMS gyroscope output signal using the PSO-TVFEMD-SE-TFPF denoising algorithm and the FTTA-LSTM temperature drift compensation model, the angular random walk (ARW) of the MEMS gyroscope is reduced to 0.02°/√h, while the bias instability (BI) decreases to 2.23°/h. Compared to the original signal, ARW and BI are reduced by 99.43% and 97.69%, respectively. The proposed fusion-based temperature compensation method significantly enhances the temperature stability and noise performance of the gyroscope. Full article

The periodic rotation of the Ocean Color and Temperature Scanner (OCTS) introduces jitter errors in the HaiYang-3A (HY-3A) satellite, leading to internal geometric distortion in optical imagery and significant registration errors in multispectral images. These issues severely influence the application value of the optical data. To achieve near real-time compensation, a novel jitter error estimation and correction method based on multi-source attitude data fusion is proposed in this paper. By fusing the measurement data from star sensors and gyroscopes, satellite attitude parameters containing jitter errors are precisely resolved. The jitter component of the attitude parameter is extracted using the fitting method with the optimal sliding window. Then, the jitter error model is established using the least square solution and spectral characteristics. Subsequently, using the imaging geometric model and stable resampling, the optical remote sensing image with jitter distortion is corrected. Experimental results reveal a jitter frequency of 0.187 Hz, matching the OCTS rotation period, with yaw, roll, and pitch amplitudes quantified as 0.905”, 0.468”, and 1.668”, respectively. The registration accuracy of the multispectral images from the Coastal Zone Imager improved from 0.568 to 0.350 pixels. The time complexity is low with the single-layer linear traversal structure. The proposed method can achieve on-orbit near real-time processing and provide accurate attitude parameters for on-orbit geometric processing of optical satellite image data. Full article

In this work, we propose a two-phase approach for a fast topology optimization of multi-resonant MEMSs. The approach minimizes the computation effort required to achieve an optimal design. In the first step, we perform a pre-optimization using bi-directional evolutionary structural optimization (BESO). We found in previous research that BESO can achieve optimal MEMS designs in a significantly lower number of iterations when compared to classical density-based methods. However, we encountered convergence issues with BESO towards the end of the optimization. Therefore, we introduced a second, density-based optimization phase to circumvent this issue. Finally, we introduced model order reduction to reduce the optimization time further. The novel approach is benchmarked with the design task of two common multi-resonant MEMS devices: a linear gyroscope and a micromirror. We show that the two-phase approach can achieve an optimal design within 200 iterations. With the addition of MOR, the computation of the goal function can be further reduced by 50% in our examples. Full article

The hybrid laser inertial navigation system (INS) is increasingly vital for high precision under high-dynamic, long-duration conditions, especially in complex aircraft environments. Key components like the base, platform, and inner/outer frames significantly impact system accuracy and stability through thseir static and dynamic characteristics. This study focuses on minimizing deviations in the INS body coordinate system caused by elastic deformation under high overload by developing a mechanical simulation model of a rotational modulation structure and a structural model of the outer frame assembly. A reliability analysis model is established, considering both functional and structural strength failures. To address uncertainties from manufacturing, technical conditions, material selection, and assembly errors, a global sensitivity analysis based on Bayesian inference evaluates parameter contributions to functional failure probability, using a sample size of N1 = 5 × 10⁵. Additionally, uncertainty analysis via Sobol sequence sampling (N2 = 10,000) examines the impact of mean design parameter variations on failure probability for ZL107 and SiCp/Al aluminum matrix composite frames. Experimental verification concludes the study. The results indicate that the SiCp/Al composite material demonstrates superior mechanical performance compared to traditional materials such as the ZL107 aluminum alloy. The uncertainties in the inner frame thickness, inner frame material strength, and outer frame thickness have the most significant impact on the probability of functional failure in the hybrid INS, with sensitivity indices of ${\delta }_6^{P\left\{F\right\}}$ = 0.01657, ${\delta }_2^{P\left\{F\right\}}$ = 0.00873, and ${\delta }_4^{P\left\{F\right\}}$ = 0.00818, respectively. The mechanical properties of the outer frame structure made from SiCp/Al are significantly enhanced, with failure probabilities across three failure modes markedly lower than those of the ZL107 frame, indicating high reliability. In an impact test conducted on the product, the laser gyroscope worked normally, the hybrid laser system function was normal, and the platform angular velocity change corresponding to each impact direction was less than 12 ″/s. The maximum angle change of the inner and outer frames was 0.107°, indicating that the system structure can withstand large overloads and multiple levels of mechanical environments and has good environmental adaptability and reliability. This analytical approach provides a valuable method for reliability evaluation and design of new hybrid INS structures. More importantly, it provides insights into the influence of design parameter uncertainties on navigation accuracy, offering critical support for the advancement of inertial technology. Full article

Thermal stress is one of the most important factors damaging the temperature-dependent performance of MEMS gyroscopes. To reduce thermal stress and improve their performance, this paper deduced the production and effects of thermal stress on a high-precision MEMS butterfly gyroscope theoretically, which provided a basis for optimization and experiments. A novel cantilever plate structure was designed based on the working modes of the MEMS butterfly gyroscope and optimized based on our simulation to achieve stress isolation. The simulation results showed that after integrating the cantilever plate structure, the stress acting on the MEMS butterfly gyroscope was reduced by 346 times, while the average capacitance gap error was also reduced by 36 times within the same variable temperature range. In addition, the cantilever plate structure was fabricated and integrated with the MEMS butterfly gyroscope. Experiments were also conducted to demonstrate the effect of reducing the thermal stress, and the results showed that the frequency variation was reduced by 28.6% and the bias stability increased by about 2 times over the full temperature range after integrating the cantilever plate structure into the gyroscope. This demonstrated that the cantilever plate structure can effectively reduce thermal stress and improve the performance of the MEMS butterfly gyroscope. Full article

The hemispherical resonant gyroscope is the highest-precision solid-state vibration gyroscope, widely applied in aviation, aerospace, marine, and other navigation fields. As the core component of the hemispherical resonant gyroscope, the design of its structural parameters directly influences the key performance parameters of the resonator—specifically, the thermoelastic damping quality factor and the minimum frequency difference from interference modes—affecting the operational accuracy and lifespan of the gyroscope. However, existing research, both domestic and international, has not clarified the effect of structural parameters on performance laws. Thus, studying the mapping relationship between the resonator’s performance and structural parameters is essential for optimization. In this study, a hemispherical resonator with a midplane radius of 10 mm serves as the research object. Based on a high-precision finite element simulation model of an ideal hemispherical resonator, the mechanism of thermoelastic damping and the influence of structural parameters on performance are analyzed. A PSO-BP neural network mapping model is then developed to relate the resonator’s structural and performance parameters. Subsequently, the NSGA-II algorithm is applied to perform multi-objective mapping of these parameters, achieving an optimized resonator with a 4.61% increase in the minimum frequency difference from interference modes and a substantial improvement in thermoelastic damping of approximately 70.41%. The comprehensive, performance-oriented multi-objective optimization method for the structural parameters of hemispherical resonators proposed in this paper offers a cost-effective approach to high-performance design and optimization, and it can also be applied to other manufacturing processes under specific conditions. Full article

This paper describes a novel micro-electro-mechanical system (MEMS) tuning fork gyroscope (TFG) design that employs a chevron-shaped displacement mechanism to amplify the displacement generated by the Coriolis force, thereby increasing the TFG’s mechanical sensitivity. This approach was evaluated using both theoretical modeling and finite element analysis (FEA), and the results showed a high degree of agreement between the two methods. A conventional TFG having a comparable area was also designed and analyzed for comparison purposes. By introducing the displacement amplification mechanism, the proposed MEMS TFG design provides an output displacement about 2.5 times higher than the conventional design, according to the computation, without increasing the device footprint. Theoretical analysis and FEA on the TFG with amplification and a conventional TFG confirmed that the amplified displacement significantly improves the mechanical sensitivity of the gyroscope compared to conventional TFG designs. Full article

The cost of a wind turbine support structure is high and this support structure is difficult to repair, especially for offshore wind turbines. As such, the loads and stresses that occur during the actual operation of wind turbines must be monitored from the perspective of maintenance planning and lifetime prediction. Strain measurement methods are generally used to monitor the load on a structure and are highly accurate, but their widespread implementation across all wind turbines is impractical due to cost and labor constraints. In this study, a method for predicting the tower load was developed, using simple measurements applied during power generation, for onshore wind turbines. The method consists of a machine learning model, using the nacelle displacement and nacelle angle as inputs, which are highly correlated with loads at the bottom of the tower. Nacelle displacements can be derived from accelerations, which are already monitored in regard to most wind turbines; the nacelle angle can be calculated from the nacelle angle velocity, measured with a gyroscope. The low-frequency components that cannot be captured with these parameters were predicted using the operational condition data used for wind turbine control. Additionally, the prediction accuracy was increased by creating and integrating separate machine learning models for each typical vibration component. The method was evaluated through the aeroelastic simulation of a 2 MW wind turbine. The results showed that the fatigue and extreme loads of the fore–aft and side–side bending moments at the bottom of the tower can be predicted using operational conditions and nacelle accelerations, and the prediction accuracy in regard to the high-frequency components can be increased by adding the nacelle angle velocity into the model. Furthermore, the fatigue loads of the torsional torque can be evaluated using the nacelle angle velocity. The proposed method has the ability to predict the loads at the bottom of the tower without any, or with only a few, additional sensors. Full article

Defect detection and classification in super-high reflector mirrors and their substrates are crucial for manufacturing laser gyroscope systems. This paper presents a prototype designed to meet the requirements for the reflection and transmission of laser gyroscope mirror substrates. The prototype featured two measurement channels (bright field and dark field) and could detect defects on patterned and unpatterned surfaces. Key components were simulated using Ansys software, (Ansys Workbench 2022 R1)which showed a maximum static deformation of 4.65 μm, a resonant frequency of at least around 230 Hz, and a maximum stress of 9.86 MPa under transportation conditions (GJB150.16A-2009). These results confirm the prototype’s stability for optical performance testing and structural design. The experimental testing on laser gyroscope reflector substrates and USAF 1951 plates demonstrated that the prototype effectively detected defects on reflection and transmission surfaces, with a detection resolution that exceeded 170 nm, which met the design requirements. Full article

A MEMS gyroscope is a critical sensor in attitude control platforms and inertial navigation systems, which has the advantages of small size, light weight, low energy consumption, high reliability and strong anti-interference capability. This paper presents the design, simulation and fabrication of a Y-axis gyroscope with out-of-plane detection developed using CMOS-MEMS technology. The structural dimensions of the gyroscope were optimized through a multi-objective genetic algorithm, and modal, harmonic response and range simulation analyses were carried out to verify the reasonableness of the design. The chip measured 1.2 mm × 1.3 mm. The simulation results indicate that the driving and detecting frequencies of the gyroscope were 9215.5 Hz and 9243.5 Hz, respectively; the Q-factors were 83,790 and 46,085; the mechanical sensitivity was 4.87 × 10⁻¹¹ m/°/s; and the operational range was ±600°/s. Chip testing shows that the static capacitance was consistent with the preset value. The error between the measured frequency characteristics and the simulation results was 1.9%. This design establishes a foundation for the integration of the gyroscope’s structure and circuitry. Full article