Aiming at the problem of solution domain analysis of Watt-type planar six-bar linkage, a singularity identification method based on Euler formula and discriminate method for planar four-link chain and planar six-link chain was proposed. Combining the motion characteristics of planar four-link chain and planar six-link chain, the branch automatic identification for Watt planar six-link mechanism was studied. Firstly, based on the proposed recognition method and the MFC (microsoft foundation classes), a computer-aided identification software was designed to realize the automatic recognition of the branch, configuration position and singular point coordinates of Watt-type planar six-bar linkage. Secondly, according to the recognition results, the feasible region of Watt-type planar six-bar linkage was analyzed. According to the feasible region, the motion simulation video of the linkage was generated, and the kinematics characteristics were analyzed by the simulation video. Finally, the automatic identification process of Watt-type planar six-bar linkage was demonstrated by examples. The results showed that the computer aided identification software could automatically discriminate the branches of Watt-type planar six-bar linkage. The research results indicate that the proposed Watt-type planar six-bar linkage branch automatic identification method can realize the feasible domain analysis and kinematics analysis of the linkage easily and quickly，and has a strong engineering practicability.

Aiming at the problem that the shape memory alloy (SMA) temperature feedback control is difficult to achieve and the small SMA dependent variable leads to small drive displacement in practical applications, a new SMA actuator based on resistance feedback control was designed. A three-fingered dexterous hand with rope transmission was developed using this actuator. The new SMA actuator was consist of a pulley, a hollow stud, SMA wire and spring drawing device.The using length of the SMA wire was developed by using a pulley winding to increase the drive displacement output. A switch control system based on resistance feedback was designed based on the relationship between the change of SMA resistance and phase which was obtained by the resistance characteristics of SMA itself. The three-fingered dexterous hand was designed with modular idea, having 8 degrees of freedom for 3 fingers, and its ability to grab objects was verified through the experiment. The result showed that the new actuator did not need to judge the SMA wire phase change process by measuring temperature, and eliminated the external temperature sensor.The output of actuator could reach more than 8% of the total drive length. Monitoring the resistance change of the SMA wire could realize the control of the electric heating of the actuator and prevent the SMA wire from being overheated and burned.The results provide an idea for increasing the drive displacement and reducing the control difficulty of SMA actuator.

At present, protective equipment for the gateway of civil air defense engineering is in short supply. According to the characteristics and protective requirements of the horizontal electric blast door, a new design of horizontal electric blast door with both manual and electric forms which can be opened inside or outside is proposed. The layout was put forward which was compatible with manual as well as electric control modes to solve the problem of larger opening force when manual opening. Based on the established finite element model of the door leaf of new horizontal electric blast door, the section and skeleton layout of the door leaf were optimized, and the corresponding load loading and constraint setting methods and suggestions were put forward, the rationality and reliability of the design were verified by simulation analysis. Based on dynamics simulation technology, the simulation model and constraint setting method of electric actuator of blast door were established, and the theoretical peak of thrust required by electric components was determined. The prototype of new horizontal electric blast door was manufactured and tested. The result showed that the blast door ran stably and could meet the civil air defense requirement of level 6 protection resistance. The design and simulation analysis of the new horizontal electric blast door can provide reference for the development of other similar protective equipment.

In order to improve the operational reliability of the tripod universal joint in the power transmission system, according to the periodic variation of radial load and axial load on the slider assembly of the tripod universal joint, a rubber damping type tripod universal joint was designed and its life was predicted. Based on the nominal stress method, the S-N curve of the fluororubber material was obtained by the test, and the fatigue life of the damping structure was analyzed. It was found that the minimum number of fatigue cycles for the damping type tripod universal joint was 5.88×10⁶, which appeared at the position of the fluororubber damping element. According to the relationship between the mileage and the number of cycles, the life expectancy of the damping type tripod universal joint was about 1.47×10⁶ km. The study results can provide a theoretical basis for the regular maintenance and replacement of joints in the application.

In order to realize the recognition and matching of underground equipment by mining patrol robots, a coal mine equipment type of recognition model was established by deep learning algorithm based on convolution neural network. A large number of image samples of equipment to be identified were collected under the bright, dark and equipment overlapping conditions, and the recognition model was trained to realize the accurate recognition and classification of coal mine equipment by patrol robot. A coal mine equipment of matching model was established by using the SVM(support vector machine) based on particle swarm optimization. The three-axis position information, three-degree-of-freedom angle and the rotation angle of visual camera of the patrol robot relative to the coal mine coordinate system were taken as the input of the matching model, and the serial number of equipment in the camera field of vision was taken as the output to realize the correspondence between the equipment identified by the coal mine equipment type identification model and the known equipment serial number. The experimental results showed that the coal mine equipment type of recognition model based on deep learning algorithm was insensitive to external interference and had high recognition accuracy. The coal mine equipment of matching model based on support vector machine achieved 93.2% accuracy of equipment matching, and it was superior to the matching model based on the BP (back propagation) neural network in training and testing efficiency of equipment matching accuracy. The research results provide a reference for the development of patrol robot in coal mine.

To improve the bearing capacity of the integral slip in the soluble bridge plug, the structure of slip groove was optimized. Firstly, the failure reasons of the integral slip were analyzed through the bearing capacity test. Secondly, a one-sixth model and the generalized contact relation of integral slip and its contact parts were established by finite element method, and the influence of single tooth structure parameter on the anchoring effect of slip was analyzed. Then, an orthogonal experiment was designed to select the best groove structure parameters: the distance between the front groove axes and slip front was 25 mm, the distance between the front and back groove axes was 15 mm, the angle of groove axis was 20°, the inclination angle groove axis was 20° and the groove depth was 7 mm. Finally, the integral slip with optimized groove structure was processed and the bearing capacity experiment was carried out. The experiment results showed that the axial bearing capacity of slip reached 629 kN, which could bear the axial load of casing with inner diameter of 114.3 mm under the 70 MPa downhole pressure environment. The simulation and experimental results indicate that the integral slip groove parameters have significant influence on the bearing capacity of slip. The research results have important reference value for the design of integral slip structure with insert teeth.

In view of the research on the level of repair analysis (LORA) in the analysis of civil aircraft maintenance engineering, the economic and non-economic factors are comprehensively considered on the basis of the characteristics of the civil aircraft maintenance guarantee system, and the comprehensive analysis of various evaluation factors affecting the civil aircraft level of repair is carried out. A comprehensive evaluation model for civil aircraft level of repair was established by using the extension analytic hierarchy process (EAHP) and the fuzzy comprehensive evaluation (FCE), and the fuzzy evaluation results were verified by the grey correlation analysis. In the process of model solving, the model used interval number instead of point value to construct the judgment matrix and solved the weights of index at all levels, and the fuzzy comprehensive evaluation method was used to obtain the fuzzy relationship. The index weight and the fuzzy evaluation matrix were linearly combined to solve the complex multi-factor inclusion equation, and the optimal scheme was determined by normalization. The grey correlation analysis method was used to verify the correlation between the feasible scheme and the ideal scheme. The proposed model was validated by an example, and the results indicated that the best scheme was V₃, that was, the level of repair was base level, which was basically consistent with the guidance in engineering documents and showed that the validity of the model. The established model for determining civil aircraft level of repair analysis improves the theory of level of repair analysis, which can provide reference for aircraft manufacturers and airlines to determine the repair level of aircraft in the design and use phase.

In order to verify the rationality of overall layout design and manufacturing process of the smart manufacturing test bed under the operating environment, the production cycle time and OEE (over all equipment efficiency) were simulated through the Siemens Plant Simulation plant software. Firstly, one make-to-order manufacturing line 2D simulation model was established and the input parameters of the 2D simulation model were set up according to production requirements. The process layout, logistics layout and manufacturing strategy were also optimized according to the statistical results obtained from the 2D simulation model. Based on the 2D simulation model, the corresponding 3D model was built and the 3D model of each object was replaced or imported in the 3D simulation model based on the original 3D design map， and the precise 3D position coordinates and action paths were coded with Simtalk language to make the model more impressive and dynamic in the construction stage and operation stage. The results showed that the optimized 3D simulation model of smart manufacturing test bed could realize the business operation mode consistent with the actual production, which had more vivid and realistic dynamic running display effect. The simulation results have guidance for the construction and optimization of the smart manufacturing test bed, and the simulation model can also accept the operational data to optimize the continuous iteration of the test bed during the operation stage. The proposed simulation model design method can lay the foundation for the realization of the digital twins of the smart manufacturing test bed.

The dynamic error of feed system is a key factor in determining the machining accuracy of CNC (computer numerical control) machine tools. Clarifying the influence of mechanical system parameters and control system parameters as well as the coupling between them on the dynamic error of the feed system is an important subject currently facing. Taking the feed system of a five-axis linkage machining center as the research object, the dynamics model of the feed transmission system was established through fully considering the stiffness between the joint surface of the transmission parts of the feed system and the flexibility characteristics of the roller screw, and the model was verified by finite element software. Based on the typical three-loop PID (proportion integration differentiation) control structure, the electromechanical-rigid-flexible coupling dynamics model of the feed system was built. On this basis, the influence law of mechanical system parameters and control system parameters on the dynamic error of feed system was studied through the simulation analysis. The results showed that among the mechanical system parameters, the influence of ball screw lead and axial stiffness of nut pair on the dynamic error of feed system was significant, while the influence of axial stiffness of support bearing was not obvious. Among the control system parameters, the position loop proportional gain had a significant influence on the dynamic error of feed system, but the influence of the speed loop proportional gain was inconspicuous. The research results lay a theoretical foundation for realizing the predictability and controllability of dynamic errors of the feed system.

In solid-coupled ultrasonic test, ultrasonic coupled effect is imperfect on the contact interface formed by two rough surfaces. In order to promote the ultrasonic test coupled effect on the interface, coupled properties are necessary to study. Based on the spring contact model of rough surface and the contact theory of rough surface, the coupling interface theoretical model of surface solid-coupled ultrasonic test was deduced. According to the actual situation and material parameter analysis, the relationship between the average acoustic reflection coefficient, which represented the interface coupling effect, the contacting load and the equivalent roughness of the contact surface was obtained, and compared with the calculation results of T model. The average acoustic reflection coefficient of the contact interface under different equivalent surface roughness and different load was measured, the theoretical and experimental values of the contact load when the interface acoustic coupling effect reached the best under different equivalent surface roughness were compared, and the maximum relative error was 13.04%, showing that the experimental results agreed with the results of the proposed theoretical model. The proposed interface theoretical model of surface solid-coupled ultrasonic test was concise and practical and it can be referred to control relevant parameters to promote the ultrasonic test coupling effect.

Aiming at the low mechanization level of pineapple fruit picking industry as well as the low picking efficiency in China, and the problems that are prone to damage the hands of pickers, a continuously operation machine for picking and collecting pineapple is designed. Firstly, the overall structure of the pineapple automatic picking-collecting machine was designed, and the designs of the picking and cutting mechanism and belt transport mechanism were introduced in detail. Secondly, the three-dimensional model of the picking and cutting mechanism was designed by using SolidWorks three-dimensional software, and the analyses of stress, strain, displacement characteristics and dynamics were carried out through the SolidWorks soft and Motion modules. Thirdly, the electronics and control system of pineapple automatic picking-collecting machine was designed and analyzed, including the design of buck-boost scheme for power output and stepper motor drive control of the three degree-of-freedom manipulator. Finally, the pineapple fruit stalk cutting test and the pineapple fruit picking and collecting test were carried out. The test results showed that the cutting efficiency of the machine could reach 1 636 plants/h, which was more than twice the efficiency of artificial cutting, and the collection efficiency of pineapple fruit was 195 plants/h. The designed automatic picking-collecting machine can realize the continuous operation of the picking and collecting process of pineapple fruit, which can improve the picking efficiency of pineapple and reduce the labor intensity of pickers.

In order to absorb the wave energy from different directions, a direct-driven wave energy converter based on Stewart parallel mechanism was designed. The branch unit of the converter was connected with permanent magnet actuator by spring element, and the wave energy-electric energy was directly converted by relative motion of stator coil. The dynamics analysis of the wave energy converter was carried out under a wave environment in a specific sea area. The horizontal and vertical wave forces acting on the converter were calculated by the F-K hypothesis method. The dynamics modelling and energy conversion simulation analysis of the converter were carried out by using ADAMS dynamics simulation analysis software. The deformation law of the elastic branched chain under the wave force was studied, and the influence of the ratio of stiffness coefficient of branched spring to mass of moving platform on energy conversion rate was analyzed. The results showed that under wave excitation, the energy generated by vertical and transverse wave motions could be absorbed by the wave energy converter. By adjusting the ratio of the spring stiffness coefficient to the mass of the moving platform, the maximum energy conversion rate of the converter device reached about 35.2%. The research results provides an important theoretical foundation for the design of new type of high-efficiency wave power generation device.

In order to enrich the structure of planar ultrasonic motor, a planar ultrasonic motor driven by same type bending of dual-cross piezoelectric vibrator was proposed. With the in-plane and out-of-plane bending coupling of the longitudinal bars and crossbars of the dual-cross piezoelectric vibrator, two elliptical trajectories along xoz and yoz planes were synthesized on the two-rod driving feet to alternately push the mover along the x, y directions. The driving principle of the planar ultrasonic motor was analyzed, and the elliptial trajectory equation was derived. The electromechanical coupling model of the dual-cross piezoelectric vibrator was established, and the three-phase working modes were simulated. Based on structure optimization, the frequencies of three-phase working modes were consistent, which was 43 468, 43 552 and 43 569 Hz. The frequency nesponse characteristics of the dual-cross piezoelectric vibrator were simulated and the interference mode separation was realized. When the driving voltage was 250 V, the amplitude in x, y and z direction of the driving foot were 1.3, 0.8 and 0.9 μm, respectively, which met the motor drive requirements. The two elliptical trajectories of the dual-cross piezoelectric vibrator driving foot under the constant frequency excitation was simulated，which verified the effectiveness of the driving principle for the designed planar ultrasonic motor. This planar ultrasonic motor is expected to output greater speed and power, which has broad application prospects.

The hydro-viscous clutch has relatively serious nonlinearity and lower control accuracy, which is difficult to meet the requirement of high transmission characteristics in the industrial field. Based on these issues, sliding mode control strategy of piston displacement based on RBF (radial basis function) neural network was proposed. The local structure of the hydro-viscous clutch was improved. The displacement sensor and the conductive slip ring were added to acquire the displacement signal. The mathematical models of the electro-hydraulic proportional relief valve and the hydro-viscous clutch were derived. The sliding mode controller based on RBF neural network of piston displacement of hydro-viscous clutch was designed and analyzed. An AMESim-MATLAB co-simulation model of hydro-viscous clutch was built. The simulation results showed that the sliding mode control of piston displacement based on RBF neural network (RBFSMC) could effectively cope with the serious nonlinearity of hydro-viscous clutch, and solved the chattering phenomenon of sliding mode control. The piston displacement controller can improve the control precision, make the controller of hydro-viscous clutch have good robustness and meet the high industrial demand.

When using the method of double-disc straight groove grinding in the process of machining rollers, in order to improve the processing efficiency of rollers and meet the requirements of continuous feeding of rollers, a kind of propulsion device is designed which can convert electromagnetic energy into mechanical energy and apply to lapping processing of cylindrical roller. The structural design of the device, the magnetic field distribution and motion condition when the device was under the energized condition were analyzed. ANSYS Maxwell, one kind of electromagnetic field simulation software was used to simulate the 2D model of device. The distribution and motion of the magnetic field were observed, the force operated on each roller in the device and the whole force state under different excitation conditions were obtained. The simulation results showed that: when the device was under energized condition, it would produce travelling-wave magnetic field doing periodic motion along the axis direction, and provide electromagnetic thrust with certain direction and adjustable size, which could meet the requirement of continuous feeding in roller lapping. With the increase of voltage and frequency, the electromagnetic thrust would also increase, and it was convenient to adjust thrust. An experimental platform for measuring electromagnetic thrust was built. Electromagnetic thrust obtained under the same excitation condition through simulation and experiment was compared. The experiment results showed that, the whole electromagnetic thrust acting on rollers would increase with the increasing of voltage and frequency. Under the same excitation condition, the experiment results were close to the simulation results, which verified the accuracy of the simulation results. The device can realize the continuous feeding of rollers and has great practical value.

Aiming at the application requirements of heavy-duty robots for grinding and polishing, a new redundant drive 2SPR-2RPU parallel mechanism was proposed. The degree of freedom of the 2SPR-2RPU parallel mechanism was calculated by using the screw theory, and the inverse kinematics and Jacobian matrix of the parallel mechanism were solved. Considering the gravity factor of 2SPR-2RPU parallel mechanism, the statics analysis of the mechanism was carried out by the method of dismantling the bar, and its statics model was established. Aiming at the characteristics of drive redundancy, the Lagrangian multiplier method was used to construct the target function with the minimum driving force, and the driving force was distributed and solved. The driving force variation trend of the 2SPR-2RPU parallel mechanism with the given motion track was obtained. According to the velocity Jacobian matrix, the singularity of 2SPR-2RPU parallel mechanism was analyzed. It was concluded that the mechanism had no forward kinematics singularity and inverse kinematics singularity, but only two mixed kinematics singularities, and the two singularities could be avoided by reasonable design of the rod size. The research results can provide a theoretical basis for the study of redundant drive parallel mechanism in practical engineering applications.