In the cloud manufacturing environment, aiming at the problem of huge waste of resources caused by the surplus sheet materials after processing by small and medium-sized enterprises, a hierarchical resource description model based on the semantic similarity algorithm and integrating the QoS (quality of service) information is proposed. Firstly, the ontology models of surplus sheet material and sheet processing equipment resources were established; then, based on the semantic similarity algorithm, the attribute parameters of surplus sheet material and sheet processing equipment were matched to obtain the primary selection service set; finally, the natural language describing the user’s requirements was transformed into triangular fuzzy numbers through the fuzzy QoS matching algorithm, and the optimal set of service equipment was obtained. The simulation results showed that the proposed method took the surplus sheet materials as manufacturing resources to access the cloud manufacturing platform, and shared them in the form of services, which enhanced the accuracy and reliability of the service matching process and realized the reasonable scheduling and use of surplus sheet material and idle sheet processing equipment resources. The research results can provide a new idea for the matching and optimization of surplus sheet material and processing equipment resources in the cloud manufacturing environment.

In view of the disadvantages of the current active heave compensation method of marine winches driven by AC (alternating current) variable frequency motors, such as large starting current, low efficiency and large energy consumption, an active heave compensation control method driven by switched reluctance motor (SRM) is proposed. Firstly, a mathematical model of SRM was established. Then, combined with the synchronous control requirements of the active heave compensation of the marine winch, a speed control method of SRM based on gradual steady state control signal-error control (GSSEC) was proposed, and its basic principle, specific design method and control parameter optimization method were analyzed. Finally, the effect of the speed control method of SRM was simulated and verified by experiment. The results showed that the speed control method of SRM based on GSSEC not only had high tracking accuracy for the time-varying given speed, but also had strong robustness to the load disturbance, which effectively improved the accuracy of the active heave compensation control of the marine winch. The research result is of great significance to promote the application of the active heave compensation control function of marine winches.

There are many dimension marking modes of mechanical parts, which affect the precision and manufacturing cost of mechanical products. In order to obtain a reasonable part dimension marking mode, a assembly dimension connection path diagram containing all possible dimension marking modes was established. In order to obtain the shortest formation path of assembly functional dimension, based on the shortest path principle of assembly dimension chain and the solution of shortest path problem, two methods were used to establish the shortest path spanning tree of assembly functional dimension. The shortest path spanning tree determined only one reasonable dimension marking mode for all parts of the assembly. The research results provide a new path for the rational design of part dimension marking, which is easy to realize with computer aid.

In view of the existing automatic extraction method for drawing text information that can only extract the contents of title bars and detail lists in a single drawing, a text information automatic extraction method for multiple CAD (computer aided design) drawings is proposed, and the supporting automatic extraction and verification system is developed. The block table record iterator was used to traverse all attribute blocks in the multiple CAD drawings, and the drawing block and its insertion point coordinates and format were filtered based on the block name, so as to determine the position of each drawing; the text information of multiple CAD drawings was classified according to the multi segment lines and attribute blocks, and the text information in the drawings was obtained and extracted by constructing the window selection set; the extracted text information was output in the form of array and compared with the original file. Finally, an automatic text information extraction and verification system for multiple CAD drawings was developed, and the feasibility of the proposed method and system was verified by extracting and verifying the text information of connector circuit diagrams. The results show that the proposed method provides a new idea for the extraction of CAD drawing text information, and the developed system provides a new tool for operators to extract text information of CAD drawings, which can significantly improve the working efficiency.

Point cloud hole repair is a key technology in the point cloud data processing, which directly affects the quality and integrity of the point cloud. The BP (back propagation) neural network optimized by genetic algorithm (GA)(GA-BP neural network) is a good repair method for scattered point cloud holes. However, multiple steps in the traditional repair method of scattered point cloud holes based on GA-BP neural network need to be completed through the human-computer interaction with the help of reverse software, which leads to a tedious and time-consuming process. Therefore, an automatic repair method of scattered point cloud holes based on GA-BP neural network was proposed. Through the computer programming, the hole identification, hole region interpolation and hole repair were combined to realize the automatic repair from the incomplete point cloud model to complete point cloud model without complicated human-computer interaction and data conversion. The experimental results show that the proposed method can effectively avoid the data distortion caused by the data conversion, reduce the workload of human-computer interaction and repair point cloud holes conveniently and efficiently. The density of the repaired point cloud is uniform, which is of great significance for improving the repair efficiency and quality of point cloud holes.

Due to the complex structure and bad operating environment, the wind turbine gearbox is a component with the highest failure rate in the wind turbine. Its performance directly affects the stability and safety of the wind turbine, and it may cause property loss or even casualties in serious cases. Therefore, based on the principle of electrostatic monitoring, a number of electrostatic sensors were used to simultaneously monitor the secondary effect of the friction and wear of the wind turbine gearbox; based on the extracted time-domain characteristic parameters and complexity measurement parameters, the MWLOF (moving window local outlier factor) algorithm was used to analyze the variation trend of electrostatic signals of the wear state of the wind turbine gearbox in the load test and damage test. The results showed that in the load test, the electrostatic monitoring method had detected the early performance degradation of the wind turbine gearbox before some faults occurred; in the damage test, the electrostatic monitoring method detected the faults of wind turbine gearbox by 200-1 000 sample points earlier than the vibration monitoring method. The research shows that as a new condition monitoring technology, the electrostatic monitoring method can effectively improve the ability to monitor the wear state of wind turbine gearboxes and make a relatively accurate early the occurrence of early faults, which can provide a reference for the state monitoring of key parts of large equipment.

In deepwater test operations, the riser and the test string formed a coupling structure of double-layered string, which caused coupling vibration under the action of ocean current, bringing about safety risks. To study the influence of ocean velocity on the vibration of the riser-test string system, a similar experimental device for the vortex-induced vibration of riser-test string system was established, and the vortex-induced vibration experiment of riser-test string system was carried out at different ocean current velocities. In the experiment, strain gauges were used to collect data, and the experimental data was processed by modal analysis method to analyze the strain, frequency, displacement standard deviation and modal characteristics of the riser and the test string in lateral and flow directions. The results showed that under the load of the marine environment, the riser and the test string contacted and collided. Consequently, the test string produced vortex-induced vibration similar to that of the riser. However, the vibration amplitude of the riser was significantly larger than that of the test string; when the ocean current velocity was 0.5 m/s, the vibration amplitude of the riser and the test string increased significantly, and the riser-test string system showed a "locks up" phenomenon; as the ocean current velocity increased, the flow direction vibration of the riser was gradually dominated by a higher frequency, but the flow direction vibration of the test string was still dominated by a lower frequency. The research results can provide a reference for the suppression of riser vibration during deepwater test operation.

In order to solve key technical problems in the implementation of double-disc straight groove grinding method, relevant studies on the rotating motion of cylindrical rollers under the grinding state were conducted. Firstly, the theoretical analysis of the rotating motion of cylindrical roller under the grinding state was carried out to conclude the its stable rotation conditions. Secondly, based on ADAMS (automatic dynamic analysis of mechanical systems) software, a dynamics simulation model of the rotating motion of cylindrical roller was established. Taking the friction coefficient between the cylindrical roller and the upper and lower grinding discs, the half-angle of lower grinding disc V-type groove, the grinding pressure on single cylindrical roller and the relative linear velocity of the upper and lower grinding discs as main influencing factors, and the relative sliding rate of cylindrical roller as the evaluation index, an orthogonal experiment considering the interaction between factors was carried out. Furthermore, through the response mean analysis and variance analysis, the optimal parameter combination which could realize the stable and continuous rotation of cylindrical rollers was obtained. Finally, the correctness of the optimal parameter combination was verified on a self-designed experimental platform of cylindrical roller rotating motion test platform. The experimental results showed that the average relative sliding rate of cylindrical rollers during rotation under the optimal parameter combination was only 0.3%, and the stable and continuous rotation could be achieved, which verified the correctness of optimal parameter combination obtained by the theoretical analysis and orthogonal experiment. The research results confirm the reasonable and feasible range of the cylindrical roller rotating motion based on the double-disc straight groove grinding, which has guiding significance for the engineering practice of the double-disc straight groove grinding method, and lays the foundation for improving the consistency of the batch diameter size of cylindrical rollers.

To reduce flow unevenness caused by inappropriate structural parameters of single-acting reciprocating pump and improve the vulnerability of piston, by deriving the analytical formula of flow unevenness and piston inertia force of single-acting reciprocating pump, the changing curve of flow unevenness with cylinder number of reciprocating pump and crank-link ratio and the changing curve of piston inertia force with crank angle and crank-link ratio were obtained. Therefore, an optimization suggestion on crank-link ratio was proposed. The research results showed that flow unevenness decreased with crank-link ratio, and the maximum effect of the change of crank-link ratio on the fluctuation of flow unevenness of single-cylinder single-acting reciprocating pump was up to 60%; the effect of crank-link ratio on flow unevenness decreased with the increase of the cylinders number of reciprocating pump; the piston inertia force also decreased with the decrease of crank-link ratio, and the two peaks of its changing curve gradually converged to the middle until they merged; when the crank-link ratio dropped below 0.3, the peak of the changing curve of piston inertia force decreased to one in one cycle. The research results can provide a theoretical basis for structural parameter design and piston fatigue analysis of single-acting reciprocating pump.

To improve the mechanical performance of the all-terrain mobile robot body structure, an optimization method combining multi-body dynamics, finite element analysis and orthogonal test is proposed. Aiming at the full-load bending and torsion conditions of the all-terrain mobile robot, the external load of this mobile robot during motion was obtained by the multi-body dynamics analysis, and the dynamic mechanical performance parameters of the body structure were obtained by combining the finite element analysis, so as to verify the mechanical performance of the body structure under extreme conditions. Based on the orthogonal test of four factors and three levels, the influence of the thickness of bottom plate, the thickness of the suspension support, the length of the suspension support stiffener and the thickness of the raised support stiffener on the maximum stress, maximum deformation and mass of the all-terrain mobile robot was studied. The results of orthogonal test were analyzed by the grey correlation analysis method. Through the comparison of grey correlation degree of all factors, the best optimization scheme for the all-terrain mobile robot body structure was obtained as follows: the thickness of bottom plate was 5 mm, the thickness of the suspension support was 2 mm, the length of suspension support stiffener was 65 mm and the raised support was added stiffener with thickness of 2 mm. The analysis results showed that compared with the original scheme, the optimized all-terrain mobile robot body reduced the mass by 6.93%, while the maximum stress was reduced by 12.47%, and the maximum deformation was reduced by 41.69%. It indicated that this optimization scheme could improve the performance of body structure and reduce the body mass and the power consumption, which verified that the effectiveness of the proposed optimization method. The research results can provide a reference for the dynamic mechanical performance analysis and optimization of mechanical structures.

In order to study the failure of the axial cooling fan of the auxiliary converter in a maglev train, a failure analysis and optimization design method based on the field test, finite element simulation and surrogate model was proposed. Firstly, the failure mechanism of the axial cooling fan was analyzed through the vibration spectrum test and modal simulation analysis, and the local resonance caused by the insufficient rigidity of the installation structure and the decrease of the rotating speed was determined as the root cause of the fan failure. Then, based on the modal analysis results, a retrofit scheme for local strengthening of diagonal reinforcements in the installation network of axial cooling fan was designed, and the performance of the retrofit fan was evaluated by the acceleration spectrum response analysis. Then, the surrogate model was used to fit the mapping relationship between the characteristic parameters of the installation network strengthening structure and the vibration response characteristics of the axial cooling fan. The optimal retrofit scheme was obtained by the intelligent algorithm with the optimization objectives of avoiding resonance, reducing vibration intensity and minimizing retrofit cost. Finally, the feasibility of the optimal retrofit scheme was verified by the vibration performance evaluation test and the long-life vibration test. The results showed that the optimal retrofit scheme could effectively solve the local resonance problem of the axial cooling fan and prolong its service life. The research results can provide a reference for the resonance failure analysis and optimal design of the axial cooling fan, which has important engineering practical value.

Functionally graded material (FGM) has good application prospects in the design of thermal protection system of hypersonic aircraft because of the continuous variation of internal components along the space position, which can effectively alleviate thermal stress concentration and other phenomena. Taking the metal-ceramic functionally graded plate as the research object, the changing rules of heat conduction, thermal deformation and thermal stress of the functionally graded plate under different thermal environments were discussed. Firstly, based on the power-law distribution model of FGM, the effects of four kinds of thermal environments, including linear temperature field, sinusoidal temperature field, heat flux temperature field and nonlinear temperature field, on the physical properties of FGM were analyzed. Secondly, based on the idea of finite element layered modeling, the finite element model of functionally graded plate was established by Python programming. The changing rules of heat conduction, thermal deformation and thermal stress of functionally graded plate in heat flux temperature field under different plate thickness, ceramic volume fraction index and heat flux density and other parameters were simulated and analyzed. Finally, the method of improving the thermal protection performance of functionally graded plate based on parameter control was discussed. The results showed that when using FGM to design aircraft thermal protection panel, the ceramic volume fraction index should be less than 5.0; under heat flux temperature field, the thickness of the functionally graded plate was 7.2-9.0 mm, and the ceramic volume fraction index was 1.0-2.5, which could realize the light weight and efficient heat insulation of functionally graded plate; when the heat flux density was constant, it was of vital importance to adjust the flight time to guarantee the safety of aircraft; the heat flux density should be limited to 5-10 mW/mm² to control the deformation of functionally graded plate. The research conclusions have reference value for the thermal protection design of metal-ceramic functionally graded plate under heat flux temperature field.

The structure of offshore wind power foundation bearing equipment becomes more and more complex and heavier. Different construction processes and construction paths will lead to different residual stresses of the bearing equipment, which will affect its safety and reliability. Therefore, based on the finite element analysis method, different calculation models of offshore wind power jacket were established by using the beam element and the shell element, respectively. Then, the vertical and horizontal on-land construction processes of the offshore wind power jacket were simulated by using the element life-and-death technology. The simulation results showed that the shell element could simulate the stress state at the connections of offshore wind power jacket pipes more accurately; vertical construction process could reduce the residual stress on the key parts of the offshore wind power jacket and keep it stable during the construction, and the residual stress of the offshore wind power jacket was smaller after the construction was completed. The research results show that the key parts of large offshore structures should be simulated by shell elements which can reflect the actual structural characteristics, and the vertical construction process is safer during the on-land construction, which can provide a reference for the selection of on-land construction process for the offshore wind power foundation bearing equipment.

In order to solve the problems of low rehabilitation efficiency and easy to cause secondary injury to human body when traditional rigid robots assist human rehabilitation training, a three-joint soft actuator made of silicone material was proposed according to the structure of human fingers and the range of motion of their joints. Firstly, according to the Yeoh hyperelastic material constitutive model and virtual work principle, the nonlinear mathematical relation between the bending angle of the airbag of soft actuator and the input air pressure was established under ideal conditions, and then the influences of different structural parameters of the actuator on its bending performance under certain air pressure were studied; after that, the influences of actuator ‘s wall thickness, bottom layer thickness and chamber external diameter on the bending performance of the actuator were ranked in terms of significance by finite element model simulation; finally, the three-joint soft actuator was fabricated by 3D printing and molding process, and the test platform of bending performance of soft actuator was established to test its bending performance. The results showed that as the input air pressure increased, the relative deviation between theoretical calculation results and experimental results of the bending angle of soft actuator decreased gradually; when the air pressure was higher than 20 kPa, the minimum relative deviation was 1.48%; when the air pressure in the chamber was 50 kPa, the output force of soft actuator was 0.45 N. The software actuator can be applied to human-computer interaction assisted rehabilitation, and is expected to be applied to agriculture and biomedicine in the future.

The synchronous visual display of animal behavior signals provides an effective means to analyze and understand the characteristics of animal movement behaviors. In order to intuitively analyze the relationship between human motion posture and plantar contact force, a "behavior-force" synchronous visual display system was established. Firstly, LabVIEW software was used to realize the signal acquisition of multi-channel 3D force sensor based on UDP (user datagram protocol) and Kinect camera; secondly, a data synchronous processing method based on interpolation was proposed to realize the synchronous processing of motion posture signal and plantar force signal; then, a synchronous real-time visual virtual display system was constructed by using multi-threading technology to realize the synchronous real-time display of motion trajectory, motion posture and plantar contact force; finally, the experimental results verified that the display system had good real-time performance. The research result show that the "behavior-force" synchronous visual display system is an effective device to study the characteristics of animal movement behaviors.

In order to shorten the development cycle of omni-directional mobile navigation system of robots and improve the reusability and portability of codes, the ROS (robot operating system) with open source and distributed architecture was used as the research platform. In view of the inconsistency of protocol, poor real-time performance and complex application of traditional bus, the IgH master station under Linux was proposed to conduct EtherCAT (ether control for automation technology) communication between the control system and drivers. Firstly, an appropriate task period was selected, and the IgH master station was integrated with ROS platform. Then, kinematics modeling of omni-directional mobile platform was establish. By establishing URDF (unified robot description format) model and odometry model and combining the Navigation function package provided by ROS, an omni-directional mobile navigation system with good openness, high code reusability and stable performance was developed. The research showed that the navigation system could effectively realize autonomous navigation, with the advantage of simple structure, excellent synchronization and low cost. The research result provides a new method for the precision control of omni-directional mobile robot.

In order to explore and enrich the structure of rotary ultrasonic motor to meet the requirements of accurate and fast response and simple control, a Y-shaped rotary ultrasonic motor was designed, and its structure and dynamic characteristics were analyzed. The Y-shaped rotary ultrasonic motor combined the transverse vibration of three groups of piezoelectric ceramic plates into a small amplitude drive by the driving foot face to the rotor, and the rotor was driven to rotate clockwise or counterclockwise under the inertia action through friction coupling. The Design Exporation module of Workbench software was used to optimize the structural dimension of the Y-shaped rotary ultrasonic motor stator assembly, so as to improve its performance. The finite element simulation model of the stator assembly of the optimized Y-shaped rotary ultrasonic motor was established. The natural vibration shape required by the stator assembly was obtained through the modal analysis. The amplitude-frequency characteristic curve of the stator assembly was obtained through the harmonic response analysis. The vibration mode of the stator assembly in one excitation cycle was obtained through the transient analysis, which verified the driving mechanism of the Y-shaped rotary ultrasonic motor. The results showed that the optimal frequency of the voltage applied on the surface of piezoelectric ceramic plate of Y-shaped rotary ultrasonic motor was 20 739 Hz, the corresponding amplitude of the driving foot face was 6.95 μm. The Y-shaped rotary ultrasonic motor has a simple and symmetrical structure, and high energy efficiency utilization, which has important reference value for broadening the application field of ultrasonic motors.