Acta Armamentarii

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2019, 40(2): 0.

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Anti-jamming Method for Pulse Doppler Fuze Based on Joint Feature Extraction of Target Signal

DAI Jian, LI Ze, HAO Xinhong, LI Ping

2019, 40(2): 225-233. doi:10.3969/j.issn.1000-1093.2019.02.001

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An anti-jamming method based on the joint feature extraction of target signal for pulse Doppler (PD) fuze is proposed for the inadequate capacity of PD fuze against information type jamming. The output signal of fuze baseband filter is analyzed in consideration with the target function, and an expected target space is constructed using both two-class and one-class support vector machines (SVMs). The proposed method is verified through prototype test. The experimental results indicate that the prototype of PD fuze achieves more than 90 percent success rate in anti-jamming, which can significantly improve the anti-jamming ability of pulse Doppler fuze. Key

Optimization of Anti-vibration Performance of Naval Gun Barrel

FU Wei， WU Qiong， CUI Yunshan， LIU Qi, ZHOU Chao

2019, 40(2): 234-242. doi:10.3969/j.issn.1000-1093.2019.02.002

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The optimization of anti-vibration performance of barrel of naval gun is studied based on the firing accuracy of naval gun during continuous firing. According to the actual model of barrel, a simplified model of the three-section beam structure of barrel is put forward. And then a mathematical model of the barrel stiffness optimization is established, and the stiffness model of barrel is deduced. The sensitivity analysis method is used to obtain the sensitivity analysis map of barrel stiffness and mass, thus determining the optimized parameters. The ANSYS software is used for the multi-objective optimization of the anti-vibration performance of barrel. The optimal solution of barrel optimization was obtained and compared with the actual barrel model. The results show that the effective design variables of barrel could be changed to improve the dynamic performance of barrel. After the anti-vibration performance is optimized，the first order natural frequency is increased by 17.99%, and the mass of barrel is reduced by 6.12%. Key

Research on Robust Optimal Design of a Ramming Mechanism for Consistency of Ammunition Ramming

LIN Tong, QIAN Linfang, CHEN Guangsong, LIU Taisu

2019, 40(2): 243-250. doi:10.3969/j.issn.1000-1093.2019.02.003

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The fluctuation of projectile motion parameters before bayonet-chamber is reduced, i.e., improving the consistency of ammunition ramming, to improve the consistency of bayonet-chamber. The random parameters in the ramming system are summarized according to the operating principle of ramming mechanism and the experimental results. Based on MSC.ADAMS, a dynamic model for ramming process of a ramming mechanism, in which the parameter randomness are taken into account, is constructed. A robust optimal design model of ramming mechanism for consistency of ammunition ramming under the constraint of minimum 3 m/s bayonet-chamber velocity is established for minimizing the standard deviation of the motion parameters before bayonet-chamber. The optimization calculation efficiency is improved by using the global and local combinatorial optimization algorithms, and the descriptive sampling. Numerical examples show that the bayonet-chamber velocity meets the requirements, and the consistency of ammunition ramming is improved after optimization, which verifies the effectiveness of the method. Key

Double Triangle Array Model of Bullet Oblique Penetration Based on Shockwave Propagation Path

LIN Yixue, DI Changan, DI Changchun, GONG Xinyu, JI Han

2019, 40(2): 251-256. doi:10.3969/j.issn.1000-1093.2019.02.004

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In order to reduce the positioning error introduced by the traditional double triangle array positioning model due to that the projectile penetrating obliquely into a target plane, the propagation path of shockwave caused by projectile which obliquely penetrates into the target surface spreading to the sensor is analyzed, and an oblique penetration positioning model of double triangular array based on the shock wave propagation path is proposed. To verify the proposed model, the positioning error of oblique penetration and the traditional model were respectively simulated by MATLAB software. The simulated results show that the oblique penetration model effectively reduces the positioning error caused by the penetration angle. A small-angle firing experiment of 5.8 mm rifle in the absence of wind was designed. The experimental results show that,compared with the traditional double triangle array model, the average positioning error of projectile coordinates measured by the oblique penetration model is reduced by 43.46% and the positioning accuracy is improved to less than 1 cm under the same hardware conditions. Key

Improvement and Parameter Identification of Correction Force Model for Fixed-canard Guidance Kit

FENG Bin， YU Jiyan， WANG Yu， WANG Xiaoming， JU Tan

2019, 40(2): 257-264. doi:10.3969/j.issn.1000-1093.2019.02.005

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The attitude of fixed canard dual-spin trajectory correction projectile is changed by adjusting the phase angle of fixed canard to control the direction of correction force. An exact correction force model of precision guidance kit is the key to improve the correction accuracy of the correction projectile. The validity of the numerical calculation is verified on the basis of wind tunnel test. Based on the small disturbance theory, a modified correct force model of guidance kit is established for the correction projectile with four canards. Levenberg-Marquardt algorithm is used to identify the parameters of the modified correction force model based on the data of computational fluid dynamics（CFD）. The results show that y and z directions vary sinusoidally with phase angle in the correction force model based on four canards. The disturbance coefficient of warhead is insensitive to the angle of attack at a given Mach number. The change of disturbance coefficient with angle of attack is less than 4.9%. The residual sum of squares of correction forces in y and z directions in the proposed modified correction force model is smaller than that in the existing model. The calculated results of correction force model of guidance kit are in good agreement with CFD calculations. Key

Experimental and Numerical Research on Motion Characteristics of a Small Caliber Bullet in Muzzle Flows

CHEN Chuanlin， HUANG Chenlei， XU Hui， LI Zhongxin， WU Zhilin

2019, 40(2): 265-275. doi:10.3969/j.issn.1000-1093.2019.02.006

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The study on the motion characteristics of bullet in muzzle flow field is of great practical signi- ficance to the better understanding of the effect of muzzle flow on a bullet, and it also has a realistic meaning for improving the firing accuracy of weapon systems. The high-speed photography and shadowgraph method are used to study the motion characteristics of 5.8 mm bullet in the muzzle flow field. Based on chamber pressure data observed in experiment, the force and motion of bullet in muzzle flow field are studied by using coupled interior ballistic computational fluid dynamics method. The experimental result shows that the clear flow field and bullet motion can be captured by using the designed test scheme; the numerical calculation indicates that the motion of bullet in the muzzle flow field is not always accelerated. The effects of the coronal air mass and the core jet of propellant gas are the main cause to lead to the change in bullet velocity. At the moment of axial force conversion, there is still shock wave at the bottom of the bullet. Key

Comparative Study of Projectiles Penetrating into Two Kinds of Concrete Targets at High Velocity

ZHANG Xueyan, WU Haijun, LI Jinzhu, PI Aiguo, HUANG Fenglei

2019, 40(2): 276-283. doi:10.3969/j.issn.1000-1093.2019.02.007

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With the development of weapon systems, high strength concrete has been applied to the protection facilities. In order to study the phenomenon and law of projectile penetrating into high-strength concrete, the experiment of projectile penetrating into C60 high-strength concrete target is carried out, and the experimental results are compared with those of C35 normal strength concrete. The penetration depth and projectile erosion are analyzed by means of calculation method based on cavity expansion theory, empirical penetration formula method and nodes back-off method. The calculated and experimental results show that the overload of projectile penetrating into C60 concrete is 1.8 times of that of projectile penetrating into C35 concrete, and the penetration depth is 52%. The surface damage of C60 concrete target is greater, indicating that the brittleness of concrete gets larger with the increase of strength. The erosion of projectile penetrating into high strength concrete is more serious in the case of the same aggregate cutting conditions, indicating that the erosion effect of high-strength mortar gets larger. Key

J-integral Measurement of Mixed Mode Cracks of HTPB Propellant Based on Digital Image Correlation Method

WANG Yang, LI Gaochun, WU Peng, YANG Ming, HAN Yongheng

2019, 40(2): 284-291. doi:10.3969/j.issn.1000-1093.2019.02.008

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In order to realize the deformation field and J-integral measurement of mixed mode crack tip, the hydroxyl-terminated polybutadiene (HTPB) propellant specimens with center-through mixed mode cracks were prefabricated, and the stretching of propellant specimens was tested. The deformation picture sequences of specimens with different angle cracks were obtained. The digital image correlation method (DIC) is used to obtain the displacement and strain field of specimen surface. The J-integral of the mixed mode crack tip is calculated using the J-integral theory and the deformation field obtained by DIC. The results are compared with the finite element results. The results show that the distribution characteristics of deformation field obtained by DIC are consistent with the results obtained by the finite element method. The J-integrals under different integral paths are conserved, which verifies that the digital image correlation method can be used to effectively calculate J-integrals. For the same tensile displacement, the J-integral of mixed mode cracks decreases with the increase in angle. The J-integral value changes little when the crack angle changes from 0° to 45°, and the J-integral value decreases obviously when the crack angle changes from 45° to 67.5°.Key

Multi-stage Trajectory Optimization of Tactical Two-stage Booster Rocket Based on Gauss Pseudospectral Method

LIU Chaoyue， ZHANG Cheng

2019, 40(2): 292-302. doi:10.3969/j.issn.1000-1093.2019.02.009

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A multi-stage trajectory optimization method based on Gauss pseudospectral method (GPM) is proposed for optimizing the high-precision trajectory of tactical two-stage booster rockets under multiple constraints. According to the operating characteristic of the two-stage engine, the entire trajectory is divided into four flight phases, such as launching, climb, endurance and attack. In order to improve the accuracy of optimization trajectory near the no-fly zone and enemy fire coverage, the conception of quasi-contact point is introduced, and the trajectory is further subdivided. The connection points are used to ensure the smooth connection between adjacent phases. GPM is used to transform the trajectory optimization problem into a nonlinear programming problem. In order to further improve the computational efficiency and reduce the difficulty of setting the initial value, an iterative strategy based on the initial value generator is designed to achieve the optimization of multi-stage trajectory. Full consideration is given to the various flight characteristics and constraints of rocket in each phase, and the numerical examples are used to demonstrate the merits of the proposed algorithm. The simulated results show that the proposed algorithm has high effectiveness and can get the feasible optimal trajectory. Key

Hover Control Co-simulation of a Coaxial Dual-rotor Aircraft

CHEN Han， LI Kewei， DENG Hongbin， WEI Yiran， ZHAO Jin

2019, 40(2): 303-313. doi:10.3969/j.issn.1000-1093.2019.02.010

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The Adams/MATLAB co-simulation platform is used to study the hover control of a coaxial dual-rotor aircraft with a steering mechanism around which three steering gears are uniformly distributed. Since there is currently no accurate mathematical model for the aerodynamic interference between the upper and lower rotors, the aerodynamic interference and flapping motion of aircraft are approximately modeled using the blade element theory and the Pitt-Peters dynamic inflow model. The inaccurately modeled part is compensated using a control algorithm. The robust tactical sliding mode control algorithm and proportion integration differentiation (PID) algorithm are used to control the aircraft attitude. And the PID algorithm is used to establish the relationship between aircraft attitude and position so that the aircraft has the ability to hover according to the spatial coordinate point. The assembly model is imported into Adams to establish a dynamic model, and a controller is built in Simulink for co-simulation. The research result shows that the proposed control method is effective, and the maximum dynamic error of hovering position of aircraft is less than ±0.2 m. Key

Research on Optimal Control Allocation of Fixed-wing VTOL UAVs in Transition Maneuver

LIU Zhenchang, TANG Shengjing, LI Mengting, WANG Xiao, GUO Jie

2019, 40(2): 314-325. doi:10.3969/j.issn.1000-1093.2019.02.011

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A nonlinear optimal control allocation method is proposed to solve the 6-degrees-of-freedom transition maneuver control of a novel fixed-wing vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV). A global controller is designed using incremental nonlinear dynamic inversion (INDI) method. INDI method can be used to reduce the influence of uncertainty in control model on control system performance. On the basis of INDI method, a two-stage cascaded optimal control allocation method is proposed to allocate the increment of control variables in flight path and attitude control loops. The proposed method can be used to transform a nonlinear coupled control allocation problem into a linear optimization problem, which avoids iterative calculation and improves solution speed. A dynamic weight strategy is designed for the weight selection in objective function. The dynamic weight strategy can adjust weights according to flight states and mission requirement, ensuring the rationality of optimal allocation results. The simulated results indicate that UAV can track transition maneuver flight path successfully, and the control allocation method is feasible. Key

A Real-time Reliability Prediction Approach for Analog Circuits Based on Noise-assisted Technique and On-site Data Update

YAN Liyue, WANG Houjun, LIU Zhen

2019, 40(2): 326-333. doi:10.3969/j.issn.1000-1093.2019.02.012

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Signal processing and information fusion technologies are the key to real-time reliability prediction. The traditional real-time reliability analysis methods are based on specific random process and pro- bability distribution. A new real-time reliability prediction method is proposed. The proposed method uses a Kalman filter-based noise-assisted technique to calculate the fault indicators that characterize system performance degradation trend. On this basis, the particle filter technology is used to extrapolate the pseudo-failure performance of circuit system, and then the Bayesian inference as an information fusion method is introduced to update the time-varying parameters of performance distribution, thus predicting the real-time reliability of the circuit. The failure physical model of an embedded planar capacitor based on the real acceleration degradation experiment is introduced, and the effectiveness of this real-time prediction method combined with noise-assisted technology and on-site data is verified by using real data instead of ideal simulation hypothetical data. The result shows that the more the on-site data information is， the higher the prediction accuracy of circuit reliability is.Key

Computational Analysis of Cavity Flow Induced by High-speed Oblique Water-entry of Axisymmetric Body

CHEN Chen, WEI Yingjie, WANG Cong

2019, 40(2): 334-344. doi:10.3969/j.issn.1000-1093.2019.02.013

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The characteristics of cavity flow around a small moving body under the high-speed oblique water-entry are analyzed, and the Reynolds-averaged Navier-Stokes equations are solved for simulation. The computational method is validated by comparing the simulated results with the experimental results. The characteristics of multiphase flow during water-entry and the influence of entry angle on water-entry flow field are investigated based on the computational method. The results show that the moving body is subjected to large drag, lift, moment and impact in the impact phase; the hemisphere-like high pressure area moves from the lower part of nose tip to the center of nose tip as the moving body continues to penetrate; the direction of velocity of cavity wall points to water first and then the cavity; the small entry angle causes small drag coefficient and impact in the impact phase and trajectory deflection; and the cavity is subsequently pulled away and the maximum size of the cavity is large when the moving body enters the water at a small entry angle. Key

Drag Reduction Characteristics of a Film Boiling Sphere Moving Underwater

LI Jiachuan, WEI Yingjie, WANG Cong, XIA Weixue

2019, 40(2): 345-352. doi:10.3969/j.issn.1000-1093.2019.02.014

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In order to reveal the drag reduction mechanism of a film boiling sphere moving underwater, mixture multiphase flow model and evaporation-condensation model are used to simulate the flow around the film boiling sphere within the range of subcritical Reynolds number based on computational fluid dynamics method. The numerically simulated resistance coefficients results are in good agreement with the experimental results in Ref.［11］. The flow characteristics around the ordinary sphere and the film boiling sphere are compared. The effect of Reynolds number on the flow characteristics around the film boiling sphere is investigated, and the drag reduction mechanism of the flow around the film boiling sphere is analyzed. The numerical results show that the no-slip boundary condition of sphere surface can be changed into the slip boundary condition of vapor film due to the presence of vapor film of film boiling sphere. It reduces the viscous force exerted to the fluid by the wall, and makes the flow separation point move to the tail of sphere and reduces the resistance of the sphere. The steam accumulates in the tail of sphere. With the increase in Reynolds number, the accumulation position moves backward, the drag coefficient becomes smaller, and the flow around the tail tends to streamline.Key

Experimental Research on Blind Adaptive Multiuser Detection Algorithm with Different Carrier Frequencies and Severe OverlappingInterference of Spectra

GE Wei, YIN Jingwei， YANG Guang， ZHENG Maochun， LI Enyu

2019, 40(2): 353-360. doi:10.3969/j.issn.1000-1093.2019.02.015

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The carrier frequencies of the interfering users may be inconsistent with those of the expected users when mobile multiuser underwater acoustic communications occur. A blind adaptive multiuser detection（BAMUD）algorithm for carrier frequency inconsistency is proposed for the multiple access interference (MAI) problem produced by inconsistent carrier frequencies in mobile multiuser underwater acoustic communications. The multi-path interference (inter-symbol interference) can be viewed as MAI using virtual user technology, that is, the channel equalization link and the MAI suppression link are combined into one link in the multiuser underwater acoustic communication system, simplifying the communication system structure. The MAI suppression characteristic of Kalman filter-based BAMUD（KF-BAMUD）algorithm, that is, the optimal estimation characteristic of KF under the minimum mean square error criterion, is used to suppress the virtual MAI with different carrier frequencies, the transmission data of the expected user is effectively estimated, thus realizing multiuser communication. A series of multi-user communication experiments under inconsistent carrier frequencies were conducted in Bohai Sea and during its ice period, and the good experimental results have verified the effectiveness of the proposed algorithm. Key

State Adaptive Unscented Kalman Filter Algorithm and Its Application in Tracking of Underwater Maneuvering Target

MA Yan， LIU Xiaodong

2019, 40(2): 361-368. doi:10.3969/j.issn.1000-1093.2019.02.016

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In order to meet the needs for tracking the underwater maneuvering target in real-time and predicting its location in the underwater confrontation environment, the higher requirements are put forward for accurate and fast estimation of target’s sailing speed and course. The traditional unscented Kalman filter(UKF) tracking algorithm is improved for maneuvering target tracking with range and azimuth. The improved tracking algorithm can also be used to estimate the system status noise online in real-time without determining the state equation and the state noise variance in advance, thus tracking the maneuvering target adaptively. A novel adaptive UKF method is proposed，which adaptively adjusts the target state noise with residual probability distribution according to the residuals of predicted and observed values of UKF algorithm, so that the UKF tracking algorithm can adjust the state according to the target state the equation reduces the reliance on the predicted value when the target is maneuvering and increases the reliance on the prediction when the target is maneuvering. Primary numerical simulation results show that the algorithm not only has good tracking performance in target maneuvering but also has accurate estimation in non-maneuvering. At last, the tracking performance of state adaptive UKF algorithm is illustrated by sonar simulation system. Key

Circular Error Probable Estimation Method Based on Gaussian Mixture Model and Expectation Maximum Algorithm for Non-GaussianDistribution

JING Peiliang， DUAN Yu， HAN Chao， GUO Ronghua， NING Xiaolei， LIU Yu

2019, 40(2): 369-376. doi:10.3969/j.issn.1000-1093.2019.02.017

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For the situation when the ordnance attacking and/or observing points do not obey the Gaussian distribution, the traditional circular error probability (CEP) computation method could not effectively deal with the experimental data. In order to resolve this problem, one new CEP estimation method based on Gaussian mixture model (GMM) and expectation maximum (EM) algorithm is proposed. In the proposed method, GMM is used to depict the ordnance attacking and/or observing points probability density function（PDF）, the EM algorithm is used to solve the model parameters, and the bisection method is used to compute CEP. A lot of scenes are used to generate the ordnance attacking and/or observing points, and the traditional method and the proposed method are used to estimate the CEP. Experimental results show that the mean square error of CEP computed by the proposed method is about 1/10 of that computed by the traditional method. This illustrates that the performance of the proposed method is better than that of the traditional method. The proposed method could be used effectively to estimate CEP when the ordnance attacking and/or observing points do not obey the Gaussian distribution. Key

Judgement of Final-impacting Firepower Compatibility of Cross-platform Non-guided Projectiles Based on Firing Effectiveness

FU Bing, CAO Yuan, XIAO Yujie

2019, 40(2): 377-383. doi:10.3969/j.issn.1000-1093.2019.02.018

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The firepower compatibility judgment is one of the chief components of firepower compatibility technology of naval vessel. The judgment of the final-impacting firepower compatibility of cross-platform non-guided projectile is researched. The firepower compatibility criterion is proposed based on the characteristics of the jamming and the conflicts in the final-impacting area of non-guided projectile, and a solution method for estimating the final-impacting firepower compatibility of non-guided projectiles of ship formation is given based on firing effectiveness. The simulated results show that the proposed method can be used to describe the firepower compatibility of non-guided projectiles during impact terminal, and overcome the weakness of overestimation of weapons by exclusive judgment. Key

Kinematics and Working Space Analysis of a Humanoid Shoulder Joint

SUN Peng， LI Yanbiao, GUO Mingfei

2019, 40(2): 384-394. doi:10.3969/j.issn.1000-1093.2019.02.019

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A humanoid shoulder joint based on spherical 5R parallel mechanism is proposed according to the structural characteristics of human shoulder joint. The inverse position solution of parallel mechanism is derived through the idea of the Paden-Kahan sub-problem. A kinematics analysis method of the asymmetric parallel mechanism with few degrees of freedom is given based on the screw theory and the product of exponentials formula in combination with the direct method and the imaginary mechanism method, and the velocity jacobian matrix of parallel mechanism is obtained. The iterative sampling optimization method for multi-parameter is used to analyze the relationship between the evaluation index of working space and the structural parameter of the mechanism. A reasonable set of structural parameters is selected in consi- dering the processing assembly process. The research results show that the humanoid shoulder joint is compact, and has a large working space and conforms to the kinematical characteristics of human shoulder joint. Key

On Whole-body Contact Compliance Control for Spatial Multi-arm Robot Manipulating a Large Target

LIU Jiayu， LI Tongtong， YU Zhangguo， CHEN Xuechao， HUANG Qiang

2019, 40(2): 395-403. doi:10.3969/j.issn.1000-1093.2019.02.020

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A spatial multi-arm robot almost cannot perform effective manipulation constraint on the target due to the large drag force and motion from the multi-contact handles of target when it manipulates a large target on orbit. The unpredictable external drag may result in the damage to the arms or the failure of capture task. A contact compliance control strategy is proposed based on a combination control law of whole-body impedance control at the center of mass (CoM) level and the independent admittance control at every supporting arm level. The robot can effectively manage the external drag force by constructing the mechanical impedance at the CoM of multi-rigid body system of spatial robot and the admittance at every arm, respectively. A quadratic programming (QP) method is used to build a system controller for the contact compliance control, which can unify the robot's whole-body motion behavior. The effectiveness of the proposed method is verified by simulation and the dimensionality reduction experiment on air-bearing bed. Key

Experimental Investigation into the Effect of Fiber Tow on Low AltitudeSlow speed and Small Unmanned Aerial Vehicle

HOU Shengchao， MENG Lifan， LIU Chunmei

2019, 40(2): 404-411. doi:10.3969/j.issn.1000-1093.2019.02.021

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Focusing on the frequent occurrence of disruption events of low altitude, slow speed and small unmanned aerial vehicle (LSS-UAV) in the urban area, the effect of soft damage on power systems of LSS-UAV using fiber tow is studied. A motor power test system and a test scheme were designed. The intertwining-block effect of fiber tow on the motor is studied by using a certain type of motor as the test object. The test results show that the effective fall times of rotation speeds of five fiber tows, suck as 150D/3, 210D/3, 300D/3, 20S/3 and 200D, are between 0.9 s and 1.5 s, and the variable quantities of torque and tension within 1.0 s are between 0.021 N·m and 0.039 N·m, and 0.608 N and 1.3 N, respectively. The optimal material parameters of the soft damage on target dynamic system in the tested materials can be obtained through analysis.Key

Self-adaptive Control of Cutting Force Based on Wire Saw Velocity in Cutting Process of Hard and Brittle Materials

AN Bei, LI Shujuan, HAO Zheng, ZHAO Wen, WANG Jiabin, LIANG Lie

2019, 40(2): 412-419. doi:10.3969/j.issn.1000-1093.2019.02.022

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Hard and brittle materials, such as optical glass, engineering ceramics, and silicon-based materials, are widely used in high-tech fields, such as optical engineering and integrated circuits, because of their good physical and chemical properties. Their low plasticity and high brittleness lead to low efficiency and poor surface quality during cutting. A model of wire saw velocity and normal cutting force in the cutting process of diamond wire saw is established, and a minimum variance self-tuning controller is designed for controlling the cutting force on-line in real-time. The experimental results show that the minimum variance self-tuning controller can be used to reduce the fluctuation of cutting force on the slice in the wire saw cutting system, and make the cutting force tend to be stable. Compared with the slice cutted under the condition of the constant parameters, the surface of work-piece finished using the minimum variance self-tuning control strategy is relatively smooth, and the surface roughness is decreased by about 30%. Key

Influences of Cold Roll-beating Forming Parameters on Forming Force and Metal Deformation

LI Long， LI Yan， YANG Mingshun， CHEN Xin， LI Jiawei

2019, 40(2): 420-429. doi:10.3969/j.issn.1000-1093.2019.02.023

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Cold roll-beating forming is a metal bulk forming technology at room temperature, which is mainly used in the forming of external teeth. The influences of forming parameters on forming force and metal deformation in cold roll-beating forming are studied. The key processing parameters are selected according to the principle and processing characteristics of cold roll-beating forming. The forming force and metal deformation in the forming process are obtained by experiment and simulation of tooth groove forming of bulk metal. The changing characteristics of forming force under different roll-beating ways are explained, and the deformation characteristics of metal and the causes of forming defects in cold rolling forming are expounded. The influences of different process parameters on the forming force and forming quality of tooth groove are discussed. The results show that for up-beating the forming force is small but unstable, and the different roll-beating ways have little influence on the forming accuracy;the roll-beating density can be suitably increased to reduce the forming force and improve the forming accuracy; and the spindle speed is increased to enlarge the forming force and induce the occurrence of forming defects under the condition of same roll-beating density. Key

Analysis of Fuzzy PID Control Characteristics on Electromagnetic Actuator for Laser Optical Path Control

SUN Feng， ZHANG Qi， XU Fangchao， LI Qiang， JIN Junjie， TONG Ling， ZHANG Xiaoyou， LIU Weiwei

2019, 40(2): 430-441. doi:10.3969/j.issn.1000-1093.2019.02.024

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A three-degree-of-freedom electromagnetic actuator, which is driven by electromagnetic force and reset by permanent magnetic force, is proposed for the real-time control of the relative position of laser focus and auxiliary gas central axis in the laser cutting process. The actuator's structure is introduced, and a mathematical model is established. The control characteristics of fuzzy PID control algorithm are analyzed through simulation and experiment, and compared with those of the traditional PID control algorithms under the condition of same PID parameters. The simulated and experimental results indicate that，in x-axial direction, the position response time in simulation has little change, and the position response time in experiment is shortened by 1.50 s; in y-axial direction, the position response times in simulation and experiment are reduced by 0.28 s and 1.88 s, respectively. After optimizing the parameters of fuzzy PID controller, the response time in x-axial direction can be reduced to 0.10 s. Compared with the actuator with traditional PID controller, the actuator with the fuzzy PID controller has the advantages of shorter response time and faster response speed. Key

Interval Uncertainty Analysis of Soft-landing Dynamics of Lunar Lander

CHEN Zhaoyue, LIU Li, CHEN Shulin, CUI Ying

2019, 40(2): 442-448. doi:10.3969/j.issn.1000-1093.2019.02.025

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Dynamic analysis of soft-landing is very important for the design of lunar lander. At present, the determined landing attitude and speed are considered while not considering the uncertainty of these parameters in the analysis of soft-landing dynamics. Based on Chebyshev interval analysis method, an analysis process of landing dynamic interval based on nonlinear finite-element model is proposed for the dynamic characteristics of landing process. The upper and lower bounds of dynamic response are calculated using Chebyshev method and compared with the simulated results of Monte Carlo method. Comparative result shows that the analyzed results of Chebyshev interval analysis method can fully cover those of Monte Carlo method, and the dynamic interval is not enlarged. The influence of truncation order on the analytic error of dynamic interval was analyzed. The analyzed result shows that the truncation order has little influence on analysis error. Chebyshev method has the advantage of high accuracy and efficiency. Key

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