In applications such as carrier attitude control and mobile device navigation, a micro-electro-mechanical-system (MEMS) gyroscope will inevitably be affected by random vibration, which significantly affects the performance of the MEMS gyroscope. In order to solve the degradation of MEMS gyroscope performance in random vibration environments, in this paper, a combined method of a long short-term memory (LSTM) network and Kalman filter (KF) is proposed for error compensation, where Kalman filter parameters are iteratively optimized using the Kalman smoother and expectation-maximization (EM) algorithm. In order to verify the effectiveness of the proposed method, we performed a linear random vibration test to acquire MEMS gyroscope data. Subsequently, an analysis of the effects of input data step size and network topology on gyroscope error compensation performance is presented. Furthermore, the autoregressive moving average-Kalman filter (ARMA-KF) model, which is commonly used in gyroscope error compensation, was also combined with the LSTM network as a comparison method. The results show that, for the x-axis data, the proposed combined method reduces the standard deviation (STD) by 51.58% and 31.92% compared to the bidirectional LSTM (BiLSTM) network, and EM-KF method, respectively. For the z-axis data, the proposed combined method reduces the standard deviation by 29.19% and 12.75% compared to the BiLSTM network and EM-KF method, respectively. Furthermore, for x-axis data and z-axis data, the proposed combined method reduces the standard deviation by 46.54% and 22.30% compared to the BiLSTM-ARMA-KF method, respectively, and the output is smoother, proving the effectiveness of the proposed method.

A compact laser collimation system is presented for the simultaneous measurement of five-degree-of-freedom motion errors. The optical configuration of the proposed system is designed, and the principle of the measurement of five-degree-of-freedom errors is described in detail. The resolution of the roll and the horizontal straightness is doubled compared with other laser collimation methods. A common optical path compensation method is provided to detect light drift in real time and compensate for straightness and angle errors. An experimental setup is constructed, and a series of experiments are performed to verify the feasibility and stability of the system. Compared with commercial instruments, the pitch and yaw residuals are ${\pm 2.5}^{″}$ and ${\pm 3.5}^{″}$ without correction, and the residuals are ${\pm 1.9}^{″}$ and ${\pm 2.8}^{″}$ after correction, respectively. The comparison deviations of the horizontal straightness and vertical straightness changed from $\pm 4.8 \mathsf{\mu }$ m to $\pm 2.8$ μm and $\pm 5.9$ μm to $\pm 3.6$ μm, respectively. The comparison deviation of the roll is ${\pm 4.3}^{″}$ . The experimental results show that the data of the five-degree-of-freedom measurement system obtained are largely the same as the measurement data of commercial instruments. The common optical path compensation can effectively improve the measurement accuracy of the system.

With the continuous improvement of the power and miniaturization of high-energy laser weapons, the airborne laser may become the active defense weapon of the next-generation fighter. However, in order to achieve hard damage to the target, there has been a lack of comprehensive quantitative method as a reference in the parameter design of airborne laser. This paper establishes the high-altitude, slope-down, and short-range laser transmission process models based on the laser transmission simulation platform Easylaser to analyze the effect of multiple parameters of airborne laser weapon on the power distribution to the target spot. The simulation results show that the laser power, wavelength, laser emission aperture, tracking accuracy, and transmission distance have significant impact on the power distribution to the target spot, whereas the atmospheric mode, slanted angle, and adaptive optics almost no impact on that. On the basis of the simulation results, the response sensitivity of some parameters’ variations to the power distribution to the target spot are analyzed. The response sensitivity variations of the tracking accuracy and transmission distance to the target spot power density varies greatly, while the response sensitivity variations of the laser power and emission aperture to the target power density varies little. These quantifiable outcomes can provide a basis for parameter optimization of airborne laser in the future.

To improve laser anti-UAV technology and UAV laser protection capabilities, research on continuous laser damage to a UAV flight control system has been carried out. Combining waveform and function monitoring, the performance of the flight control system under laser irradiation was observed in real time, and the temperature and ablation process were recorded, which were used to analyze its damage characteristics and thresholds. Our experimental results show that the flight control system had two damage modes: temporary failure and permanent damage. Temporary failure had a temperature threshold, which was on average $450.85$ K. All temporarily failed flight control system functions could be restored after cooling and a manual restart, but permanently damaged flight control systems could not be manually restarted. This experiment showed that, within K. All temporarily failed flight control system functions could be restored after cooling and a manual restart, but permanently damaged flight control systems could not be manually restarted. This experiment showed that, within $10 \mathrm{s}$, the power density required for temporary failure and permanent damage to the flight control system was ${28.4 \mathrm{W}/\mathrm{c}\mathrm{m}}^2$ and ${42.6 \mathrm{W}/\mathrm{c}\mathrm{m}}^2$, respectively. The power density required for permanent damage was ${82.0 \mathrm{W}/\mathrm{c}\mathrm{m}}^2$ within $16 \mathrm{s}$ if the flight control system was encapsulated with aluminum alloy. Based on the circuit fault diagnosis of the flight control system samples that has been permanently damaged, the laser’s thermal effects damaged the diodes and linear regulators, ultimately rendering the flight control system unable to be manually restarted.