The convergence speed and the filtering precision are poor when the interactive multiple model (IMM) filtering algorithm is applied to track the anti-ship missile in S maneuver. Thus a fuzzy logic interactive multiple model (FLIMM) filtering algorithm is proposed by improving the model probability updating module of IMM filtering algorithm in three-dimensional space. Taking relative distance and angle of sight as observation information, the algorithm assumes that the target moves in two modes:uniform motion in a straight line and S maneuver. The simulation shows that the proposed algorithm can improve the convergence speed effectively and achieve higher tracking accuracy.

Based on the objective reality of gradient potential existence in spacecraft surface caused by charged particles in space plasma environment in the orbiting spacecraft, discharge of spacecraft with surface charging or deep dielectric charging would be induced by debris or meteoroids impacting. In order to simulate the existence of the spacecraft surface potential in the laboratory, method of spacecraft surface segmentation was used, different spacing is reserved between two adjacent surfaces, and resistance is added to create high-potential surface and high-potential gradient as a target in the segmentation of the surface for 2A12 aluminum plate. Potential gradient power supply circuit system, discharge test system and ultra-high speed camera photo acquisition system were built by ourselves, and combining with two-stage light gas gun loading system, we have carried out experiments on high-velocity impact on 2A12 aluminum target with gradient potential. In the experiments, high-potential 2A12 aluminum was used as the target with gaps of 2 mm, 3 mm, 4 mm and 5 mm between high-potential and low-potential 2A12 aluminum, the incidence angle (between projectile flying trajectory and target plane) of 60°, and the impact velocity of about 3 km/s. Voltage probe and current probes were used to acquire discharge voltage and current. The experimental results show that the plasma discharge is generated by forming a discharge channel between high-potential and low-potential target, the gaps with 2 mm and 3 mm evoke primary discharge, and the discharge current increases when the level of spacing decreases; the gaps with 4 mm and 5 mm induce the second discharge, and the discharge current does not change significantly when the spacing between high-potential and low-potential target increases.

For the compliant micro-motion mechanism with one input force, compliance describes the relation between output displacement and input force, and is an important performance index for the dynamic performance and positioning precision. For the one with many input forces, the relation equation between output displacement and input forces has the same role with the compliance. For obtaining this equation, the method which combined the compliance matrix method and the motion raw of rigid body was proposed. Firstly, the whole structure is divided to elements, and the relation equation between displacement and force of element end is established. Secondly, the superposition or coordinate relation equation about displacements or forces of different element ends was solved according to their structural relation. Finally, the equation of relation between the output displacement and the input forces was worked out by synthesizing all the solved equations. The output displacement of a micro-motion gripper was worked out by this method and contrasted with the one from finite element analysis method. The results show that this method has the enough precision and a good adaptability for micro-motion mechanism performance analysis and optimization. The theory suggestion about dimension optimization was obtained by analyzing the equation by using MATLAB software.

This paper proposed a failure-behavior-model based accelerated degradation test designing method for assessing the storage life of accelerometer for inertial navigation products, which determines test stress levels while lacking of the preliminary experimental data. On the basis of analyzing the product characteristics and main mechanisms, the storage life characteristic parameters and test stress types are determined. An accelerometer failure behavior model which takes the material dispersion into consideration is established to describe the time-varying law. Given the highest stress level, based on the given confidence level and failure behavior model, a simulation accelerated degradation test design method is proposed to determine the lowest and intermediate stress levels with the constraint that the upper bound of degradation under lower stress level is lower than the lower bound of degradation under high stress level. Following the proposed framework, the experimental profile is designed, and then a best test plan is finally obtained. The validity of the proposed method is verified by a case study.

For dust impact on machine vision of the probe landing in Mars, a method was brought forward to remove the effect of dust on optical image and provide clear input image for the visual system. First, a model was built for the dust image. Then, the values of the atmospheric light and the transmission coefficient of the model were obtained by calculation. Among them, a quadtree subdivision approach was employed to calculate the value of the atmospheric light. The computing method was to search the maximal average region of the specified threshold area on the minimum image. Then the mean values of each channel on the same position of the original image were calculated as the estimation value of atmosphere light. And on this basis, the calculation of transmission coefficient was performed. At last, the recovery of the clear picture was finished. Test on dust images indicates that the dust image can be restored to clear image by the proposed method. Even in the complex environment, this method has high robustness to illumination variations, dust intensity change and scene change. Compared to other methods, this method has better effect in removing dust impact on optical images and is superior to other methods in terms of the restoring image evaluation index. It can further improve the clearness of dust images and provide more abundant information for post-processing.

In the field of precision measurement and aerospace, atomic gyroscope and atomic magnetometer have high requirements on the uniformity of magnetic field, while the uniformity of magnetic field generated by the traditional Helmholtz coil is not good enough for these applications. To obtain better field uniformity, a method to calculate the parameters of cylindrical coil systems is proposed based on the Taylor expansion of the axial magnetic field. The parameters of two-coil to nine-coil systems are computed, and the variation trends of magnetic field uniformity, coils' size, and coils' maximum ampere-turn ratio with coil number are analyzed. Numerical results demonstrate that the uniform region area of magnetic field increases almost linearly with the increasing of coil number, and the region area where the field uniformity is better than 0.01% in nine-coil system is about 30 times as large as that in Helmholtz coil. A method of rounding coil ampere-turn ratio is presented when integer coil turns and the same current in each coil turn are required, and the integer ampere-turn ratios of two-coil to nine-coil systems are given. Numerical results show that the uniformity of our coil systems is better than those in other papers. Finally, simulation analysis for the error caused by fabrication technique in practical five-coil system is conducted. Simulation results demonstrate that both the designed size and magnetic field of the coil meet the practical demand of atomic gyroscope and atomic magnetometer when error is taken into consideration.

A distributed spherical simplex-radial cubature quadrature Kalman filter (DSSRCQKF) was proposed aiming at the coordinated navigation problem for cooperative target by multi-satellite on orbit. The spherical simplex rule and second-order Gauss-Laguerre quadrature rule were adopted to calculate the spherical integral and radial integral, respectively, in order to calculate the Gaussian weighted integral in nonlinear Kalman filter, and a novel spherical simplex-radial cubature quadrature rule was put forward. Combined with the nonlinear cooperative navigation mathematical model, the above rule is embedded into the distributed Kalman filter framework to achieve the DSSRCQKF, in which the satellite only needs to communicate with its neighbors. The consensus estimation of the orbital state of the target satellite is achieved using the distributed data fusion method, thus avoiding the higher communication and computational burden in centralized filter. The simulation results show that, compared with the distributed extended Kalman filter, DSSRCQKF improves the real-time positioning accuracy by 11 m and the velocity accuracy by 0.02 m/s, which verifies the validity of the proposed algorithm.

The implicit solving approach of steady transonic flow field equals a Newton iteration for a nonlinear equation system. Globalization of Newton iteration is usually necessary in practice in order to fulfill the convergence requirement. In the framework of homogenous continuation, a Laplace operator based function continuation method which accelerates convergence of implicit solving of steady flow field is proposed. Considering that the steady flow field is usually initialized as uniform freestream condition, the Laplace operator is employed to speed up information propagation from wall boundary to internal flow field due to its ellipticity and to improve regularity of the problem due to its linearity and symmetric positive definite property. Thus the stability of Newton's method is improved then larger CFL number could be employed and finally the flow field solving efficiency is improved. Due to the complexity and nonlinearity of the flow field problem, a priori optimal nonlinear solving strategy is impossible to be obtained through theoretical analysis. Thus, the effect of Laplacian coefficient on convergence efficiency is investigated through numerical experiments on inviscid NACA0012 airfoil, turbulent RAE2822 airfoil and ONERA M6 3D wing test cases. Generally pragmatic combination of iteration parameters are also given and the proposed method is proved to gain over 20% saving in CPU computing time compared with the classic pseudo time marching method under transonic condition.

Magnetically suspended control and sensing gyroscope takes Lorentz force magnetic bearing (LFMB) as torquer to drive the rotor to tilt. As there is coupling between the two radial rotation degrees of freedom and it requires that rotor tilts with high precision and fast response, feedforward decoupling and internal model controller is proposed. Dynamic model for rotor tilting is established based on basic structure of LFMB. Feedforward decoupling matrix is designed to perform tilting decoupling in radial direction, and then on this basis, two-degree-of-freedom internal model controller (2-DOF IMC) is adopted to perform rotor tilting control with high precision and fast response. Simulation results by MATLAB indicate that the proposed method can realize full decoupling for rotor tilting, response time is reduced by 57.1% than that of cross PID controller, and tilting fluctuation amplitude produced by 0.1sin(2πt)° disturbance signal is reduced by 76% than that of cross PID controller.

Path following control is one of the key technologies for unmanned surface vehicle (USV) to complete its mission, which is widely concerned by the field of motion control at home and abroad. In order to improve the accuracy and robustness of USV's path following control under the disturbance of the external environment such as wind, wave and flow, path following control problem of the asymmetry underactuated USV under external disturbances such as current is discussed, and two modified integral line-of-sight(ILOS) guidance strategies are proposed. Based on the modified guidance strategies and feedback control theory, path following of the USV at horizontal level is realized. Compared to the conventional ILOS guidance strategy, the first modified strategy with time-varying integral gain can avoid integral windup and overshoot phenomenon; on the basis of the first modified strategy, the lookahead distance is designed as a time-varying element in the second modified strategy, making the USV control more flexible. In the modified strategies, integral gain and lookahead distance are all computed as different functions of cross-track error, which can conduce the USV to converge to desired path in an elegant and fast manner. Based on the cascaded system theory, the control system proposed is proved to be global k-exponential stable (GKES) when the target tasks are all achieved. The theoretical analysis and simulations show effectiveness and advancement of the proposed method.

Based on Timoshenko beam theory, this paper has analyzed the dynamic properties when a clamped beam subjected to step load and moving load respectively. In addition, K-V damping model is considered to study the influence of damping on dynamic performance of the system. To acquire the theoretical solution, proportional damping utilization condition is derived, the real modal superposition method is applied, and eventually obtain the analytical responses when beam subjected to external loads. The numerical analysis results indicate that the solving process is accurate and reliable, providing a measurement reference to other methods, like Laplace transformation. The results of damping cases demonstrate that the high modes inherit over damping property, while in low modes present oscillation convergent characteristic. Sometimes, the damping can have significantly impact on the whole system, and for large slender ratios, the amplitude under moving load is even enlarged. Furthermore, the dynamic response subjected to step load is dominated by the low modes.

Aimed at the deterioration issue of gyroscope angular velocity measurement precision, which is caused by phase fluctuation noise of superfluid gyroscope, a gyroscope noise cancellation system based on recursive least square (RLS) algorithm was proposed. First, the phase detection model of superfluid gyroscope was established, and the relationship between thin film displacement and phase of gyroscope was obtained. Second, considering the influence of thermal motion, the noise equivalent input angular velocity model of gyroscope was established, the influence of gyroscope parameter on angular velocity noise was explored, and the amplitude range of angular velocity noise was obtained. Furthermore, considering the irrelevance between angular velocity noise and input angular velocity, the mixed angular velocity information which is calculated from the thin film amplitude of the gyroscope was taken as original input of the noise cancellation system, and angular velocity noise which is caused by phase noise as the reference input of RLS adaptive filter. The noise portion of the mixed angular velocity is offset by the output of RLS filter through adjusting the parameters. Finally, the comparison results between this method and least mean square (LMS) algorithm show that the noise portion in mixed angular velocity information can be effectively suppressed by this cancellation system with fast convergence speed and good stability in the case of large angular velocity and large noise.

Based on airworthiness requirements of civil airplane, a method for evaluating ground stability and control of crosswind landing based on digital virtual flight is established. With maximum bank angle of airframe and maximum lateral deviation during the landing roll-out as key parameters, and in accordance with the results of pilot-in-loop digital flight simulation, ground stability and control as well as airworthiness compliance of crosswind landing task of a certain large amphibious aircraft were evaluated. Simulation result shows that, for a 20 kts crosswind component, the aircraft conducted a safe and well-behaving landing roll with a 3.44° maximum bank angle and 2.51 m maximum lateral deviation on dry runway, which was of airworthiness compliance. Further research indicates that crosswind component value and the extent of runway contamination significantly affect the safety of crosswind landing roll-out. A 30 kts crosswind component might result in uncontrollable ground-looping tendency on dry runway, while contaminated runway increases landing roll-out distance and brings difficulty to direction control of taxiing. The method delivered in this paper can be applied to the preliminary design phase of civil airplane and offer theoretical references for subsequent flight tests.

The inflatable self-supporting boom, which is made of laminated aluminum film and local discrete self-supporting thin shell, has the ability to support the effective load at zero inner pressure. In order to improve the accuracy predicting the vibration characteristics of the inflatable self-supporting boom, the vibration differential equation of the self-supporting boom was first deduced based on the Timoshenko beam theory and Hamiltonian principle, and a new beam element model considering the prestress and configuration change for inflation pressure was proposed. Moreover, this beam element model also considers the discrete characteristics of the self-supporting shell in self-supporting boom, and the mass matrix established by this model is closer to true value. Then, this beam element model is verified by the vibration test results, and the verified results show that this model has better accuracy than the traditional beam element model. Finally, the influence of the inflatable pressure and the width of self-supporting shell on the vibration characteristics of the self-supporting booms is analyzed. This study would provide a theoretical reference for the design of the inflatable self-supporting boom.

In order to improve the dynamic adaptability of reservoir, overcome the ill-posed problems of output weights in echo state network (ESN), and balance the fitting and generalization ability, a fault diagnosis model of plasticity echo state network based on L_1/2-norm regularization is presented. BCM rule was introduced into the reservoir construction to train the connection weight matrix. Meanwhile, the L_1/2-norm penalty term was added to the objective function in order to improve the sparsification efficiency. An iterative numerical oscillation problem was solved by using a smoothing L_1/2 regularizer, and finally the model was solved by using the half threshold iteration method. The model is applied to the fault diagnosis of airborne radio station, and the simulation results prove the validity and superiority of the model.

Considering the entire skin coating of aerostat envelop materials as one material, the effect of absorption and emission rate of aerostat envelop materials on helium temperature differences between day and night is investigated. In order to further reduce helium temperature differences between day and night, in this paper, aerostat envelop materials are divided into illuminated side with materials of low absorption rate and backlight side with materials of high emission rate. Under the established thermal analysis model, material properties in different parts of aerostat envelop materials are optimized with the method of Kriging model. It holds the thoughts that aerostat envelop materials can be divided into 48 parts, Latin hyper-cube method is used to do sampling, and sample response can be obtained through thermal analysis so as to build a Kriging approximate model. As the result, it shows that the helium temperature difference between day and night is reduced to 28.6 K, which is 7.7% less than the traditional ways of analysis.

In order to improve the anti-amplitude-modulation (AM)-jamming, anti-frequency-modulation (FM)-jamming and anti-sweep-jamming performance of FM fuze, a harmonic timing sequence detection anti-jamming method is proposed using the timing sequence characteristics of harmonics during the projectile-target encounter. A harmonic extraction method based on fast Fourier transform (FFT) is designed, and the harmonic amplitude is obtained by FFT on the difference frequency signal. Compared with the harmonic extraction method through the band-pass filter (BPF) of the existing FM harmonic fuze, the harmonic number and harmonic channel can be flexibly selected, under the condition of the same ranging precision. The better anti-jamming performance and flexible ignition height are achieved using the harmonic timing sequence detection. Simulation and experimental results verify the feasibility of the program and the anti-jamming success rate of FM fuze is improved from 16.7% to more than 90%.

Aimed at the maneuvering penetration and precision strike problem of hypersonic vehicle terminal trajectory, an optimal maneuvering trajectory optimization method considering the dynamic characteristics of intercepting was proposed from the viewpoint of optimal control, so as to obtain the maximum maneuverability of hypersonic vehicles. In this paper, the intercepting missile model was introduced into the model of penetration trajectory optimization, and a constraint was imposed to restrict the intercepting missile to fly according to the proportional guidance law. The trajectories were divided into phases according to the different missions and trajectory characteristics of the belligerents. The penetration performance index and the precision strike performance index are put forward according to the task and characteristics of each phase, and by the weighting function the independent and contradictory performance indicators are unified. Thus a multi-object, multi-phase and multi-constrained maneuvering penetration trajectory optimization model was established. And multiphase Radau pseudospectral method (MRPM) was used to solve the problem. Due to the initial sensitivity and narrow feasible region of the problem, a series of trajectory optimization strategies were proposed to improve the convergence rate and the precision of the solution. Finally, the optimal maneuvering trajectory was obtained, and the optimality of the solution was verified based on the principle of costate mapping. The results show that the method can give full play to the maneuverability of the hypersonic vehicle, and obtain the penetration trajectory which satisfies the terminal accuracy. Compared with the existing method, the miss distance is increased by 1-2 orders of magnitude. Sensitivity analysis shows that the trajectory is insensitive to the launch time of the interceptor.

In order to meet the demand of honeycomb structure perfusion of large spacecraft, a novel hybrid perfusion robot is proposed. This article mainly focuses on the analysis of the parallel mechanism. First, the kinematics analysis of 3PSS-PU parallel mechanism is conducted, and the inverse kinematic model and Jacobian matrix of 3PSS-PU mechanism are established. Then, the constraints of the main factors influencing workspace of the mechanism are given, and the reachable workspace is obtained. Next, stiffness model of the mechanism is established, and stiffness distribution of the mechanism in the process of movement is displayed. Finally, aimed at workspace volume and global stiffness, multi-objective optimization analysis of structure parameters is performed based on genetic algorithm, and final dimension parameters of the mechanism are obtained. This work would lay the foundation for the application of the honeycomb perfusion robot.

With the continuous increasing of flight density, the aviation safety in low altitude has caused extensive concern. Low-altitude environment is complex, and ground obstacles and weather have more significant impact on low-altitude flight than commercial aviation. Traditional traffic alert and collision avoidance system (TCAS) and other methods may not be applicable to low-altitude intensive flight environment. In view of the computational complexity and lack of applicability of traditional detection methods, a binary classification method of support vector machine (SVM) was introduced. By normalizing the trajectories of own and surrounding aircraft, optimizing the key parameters by intelligent optimization algorithm, and pre-training the classifier through simulation data, efficient conflict detection for low-altitude flight was carried out. Various sets of artificial data were utilized to verify the effectiveness of the algorithm. The results show that the missed alarm rate and false alarm rate are controlled at about 0.1% and 6% respectively, which proves that the proposed algorithm can overcome the shortcomings of traditional deterministic and probabilistic methods which are difficult to take both the efficiency and applicability into account.

Regarding the deficiencies of bispectrum with big data and high dimension in signal feature extraction and recognition, a method combining bispectra diagonal slice (BDS) with generalized dimension (GD) was proposed. First, BDS was used to reduce data volume and GD in the multi-fractal theory was taken to reduce dimension in order to make subtle description for slice. Second, generalized dimension corresponding to three ranks is treated as feature vectors by feature evaluation index based on distance measure. Finally, the feature vectors will be input into least squares support vector machine for recognition. Four sorts of low probability of intercept (LPI) signal are used to be recognized, and the simulation results show that the signal features in feature space have good aggregation and discreteness, and the accuracy rate of recognition can reach 92.2% when the SNR is 0 dB, which shows that it has good performance in recognition compared with other algorithms.

Through the analysis on structure characteristics and work principle of bus-based embryonic electronic array (BBEEA), the multi-state system theory is introduced to the reliability analysis of BBEEA, and the universal generating function (UGF) was used to model and analyze BBEEA reliability. Compared with BBEEA reliability model based on n/k system, correctness and validity of BBEEA reliability model based on multi-state system are verified. BBEEA reliability is analyzed based on the proposed multi-state system reliability model so as to guide the structure design of BBEEA according to reliability requirement. At the same time, in order to analyze the performance of BBEEA, comparative analysis of reliability between typical embryonic electronic array (EEA) and BBEEA is completed. The results of analysis show that reliability model based on multi-state system can analyze BBEEA reliability in nature, and it can associate working states and reliability of BBEEA, which has great guiding significance on structure design and preventive maintenance decision of BBEEA.

In order to achieve salvo attack for large heading errors with integrated time, an impact time control guidance (ITCG) law for large heading errors is proposed based on equivalent sliding mode control theory and Lyapunov stability theorem by adopting the nonlinear guidance equation and the time-to-go approximation algorithm according to predicting interception point (PIP). For stationary and non-maneuvering constant velocity targets, the proposed guidance law achieves impact time successfully with any designated initial heading error even when the closing speed is negative. Initial conditions of the missile guidance are widely broadened. Rigorous theoretical proof demonstrates the validity of the guidance law. The simulation results under different initial conditions verify the effectiveness of the proposed guidance law.

The soft landing stability will be greatly reduced if the main engine of planetary explorer fails to shut down timely. In order to avoid this reduction, a new shutdown mode is introduced to serve as a remedy where engine is shut down at touchdown. The dynamic model of the explorer equiped with novel landing gear system was established, and the model of variable thrust rocket engine and attitude control thrusters were attached to it for the analysis of the remedy. The Monte Carlo simulation is used to analyze the soft landing stability of the explorer under three shutdown modes, which include the mode that main engine fails to be shut down, the mode of shutdown at touchdown mode and the mode of shutdown at touchdown with attitude controlling, considering the uncertainty of the landing site and the explorer state at touchdown. By adopting the descriptive sampling method and a termination criterion based on the relative error of the mean estimation, the efficiency of Monte Carlo simulation is improved on the premise of ensuring the accuracy. By comparing the landing reliability among three modes, the pad contact engine shutdown technique efficiently improves the landing stability by 11.6% after failure of main engine shutdown occurs, and the introduction of the attitude control system increases the reliability of successful landing by 9.7%.

Through the fault diagnosis of aero-engine, the working status of each component can be correctly judged, and the maintenance program can be determined quickly to ensure the safety of flight. Based on the combination of deep belief network and decision fusion theory, the fault fusion diagnosis model of aero-engine based on deep learning was proposed. This model, through analyzing a large number of engine performance parameters, starts with getting fault classification confidence via hidden features in engine performance parameters extracted by deep learning algorithm, and then the multiple fault classification results were fused by decision fusion method to get more accurate results. The JT9D engine failure coefficient was simulated as data to prove the validity of the method. The results of an example show that the reliability of the data has been improved by fault fusion diagnosis of several experimental results, and the model has high fault classification and diagnosis accuracy and anti-interference ability.

In this paper, the effect of variant transshipment strategies on expected backorders (EBO) of a three-site inventory system is researched. Based on the predefined assumptions and inventory control strategy, as well as the consumption and replenishment process of the spares, the state equations of spares on hand, spares due in from repair and resupply, and backorders are presented with the consideration of the supply priority among sites. By defining the ratio between EBO and the number of spares due in, the original nonlinear equations can be transformed into linear equations. Since the coefficient matrix of the linear equations is invertible, it can be said that the linear equations has only one solution. As indicated above, a Cauchy sequence of the number of spares due in is constructed to approach the sole solution. Finally, the numerical values of the EBO under two transshipment strategies (fixed probability transshipment and priority preferred transshipment) are compared. The results show that the strategy of priority preferred transshipment can not only increase the utilization rate of spares but also reduce EBO of the system in most cases. In addition, it can be found that the effect of different transshipment strategies on the EBO mainly depends on the feasible space of transshipment strategies, which is mainly determined by the rate of demands filled by local site, the inventory allocation scheme, and the repairing and demanding rate of each site.

Zero-velocity update (ZUPT) algorithm is imported to calibrate device's cumulative error in traditional inertial navigation system (INS) which is based on micro-electro-mechanical system inertial mea-surement unit (MEMS-IMU). The positioning accuracy will be reduced when the movement trajectory of indoor pedestrian contains multi-movement patterns, because the zero-velocity determination threshold is fixed and only suitable for a single movement pattern. An adaptive threshold ZUPT algorithm under multi-movement patterns was proposed. The selection of zero-velocity determination threshold of indoor pedestrian's five movement patterns including Still, Walk, Run, Upstairs and Downstairs was analyzed. Classification and recognition of five movement patterns using random forest (RF) algorithm were realized. And the zero-velocity determination threshold of ZUPT was adaptively adjusted according to the recognition results. In order to verify the feasibility and validity of the algorithm, the test data was disposed and was compared with traditional position-ing algorithm through MATLAB software platform. The three groups of test results show that, when there are multiple movement patterns in an indoor pedestrian trajectory, the positioning accuracy of positioning algorithm can be improved by 73.83% when ZUPT algorithm with adaptively adjusted threshold is imported, compared with traditional positioning algorithm with fixed threshold.

The identification of branch, motion defect and range of motion of the planar six-bar linkages with sliding pairs is an important indicator for motion characteristics of linkages. Firstly, this paper divides the planar six-bar linkages with two sliding pairs or three sliding pairs into four-bar chain or five-bar chain. B-ring in Euler's formula and trigonometric substitution method, the specific configurations (including branch points and dead points) of the planar linkages with sliding pairs in their limit positions, input and output relationship and joint rotation space are obtained. Secondly, this paper combines two chains and proposes a method for the branch identification of planar six-bar linkages with two or three sliding pairs. Finally, this paper verifies the proposed method with examples of planar six-bar linkages with two and three sliding pairs. The branches, dead points and the specific angles of joints in limit positions of the two mechanisms are calculated. The proposed method gives a convenient and effective way for the automatic branch identification of planar linkages with sliding pairs.