As the core of complex mechanical product, key parts play an important role in realizing product functions. However, it is very difficult to identify key parts because of the large number of parts and their coupling relationship. In order to realize the identification of key units of product, a method of key meta-action identification for complex mechanical product based on multi-criteria fuzzy association comprehensive evaluation was proposed from the perspective of meta-action. Firstly, the complex mechanical product was decomposed into the smallest motion unit?meta-action, by using the decomposition method of fuction-montion-action (FMA); secondly, a triangular fuzzy evaluation matrix was established based on the motion and structure relationship between different meta-actions. Combining evidence theory and fuzzy relationship, a fuzzy evidence theory algorithm was proposed to achieve the fusion of different associated information between meta-actions, solve the problem of information ambiguity or missing between meta-actions. On this basis, the ranking of the importance of meta-actions was realized by using the method of determining the index weight of the possible degree relationship of triangular fuzzy numbers; finally, taking the turntable of a domestic NC （numerical control） machining center as an example, the rationality and effectiveness of the method were verified. The research showed that FMA decomposition method could simplify the decomposition process of the whole machine from the perspective of motion, and effectively characterize the motion relationship of product parts; the coupling between meta-actions could be better studied by analyzing the association between meta-actions from the structure and motion relationship of meta-actions; the problem of information fuzziness could be solved by introducing evidence theory into fuzzy relations to fuse the related information between different meta-actions. By sorting the importance of meta-actions, key meta-actions were identified, which laid a foundation for the subsequent research on meta-action units.

Automobile clutch is an important starting element of automobile transmission system. The traditional design method does not integrate the performance requirements, product characteristics, process flow and process capabilities organically in the whole product development process, and does not consider the reasonable tolerance range of clutch product parameters and the size changes within the life cycle, so it is difficult to meet the requirements of clutch torque transmission capacity and pedal control characteristics in large-scale production. By establishing the IPPD (integrated product and process design) method of automobile clutch based on function-product characteristics-process-process capability, the influence of clutch product characteristics and process parameter tolerances on torque transmission capability and pedal control capability was analyzed, and the method of establishing accurate transmission system dynamics model was proposed. The mapping relationship between torque transmission capability, pedal control characteristics and product characteristics and process parameter tolerance was given; under the condition of meeting the design requirements of manufacturability and assemblability, a cycle mapping relationship of product characteristics and process flow and parameter changes was established, and a robust tolerance design method based on process capability was adopted to optimize the process scheme and process parameters. The proposed clutch IPPD method can better enable the product to meet the performance requirements, thus providing support for improving the design accuracy and reliability of the clutch, and establishing a foundation for the intelligent design of the clutch.

In order to improve the mixing uniformity of two-component composite coatings, the parameters of stirring screw were optimized. Taking the mixed pin type stirring screw as the object, its three-dimensional model was established and imported into the EDEM software. Then, based on the discrete element method, the stirring process of two-component composite coatings in the stirring screw was simulated and analyzed, in order to study the effects of rotation speed, pitch and aspect ratio of screw on the mixing uniformity. Finally, the uniaxial compression experiment was conducted to compare and verify the stirring effect after optimization of screw parameters.The results showed that the mixing uniformity of composite coatings was affected by the rotation speed, pitch and aspect ratio of screw through changing the particle dispersion, screw blade gap and screw length, respectively; after stable discharge, when the screw rotation speed was 200 r/min, the pitch was 80 mm, and the aspect ratio was 5.57∶1, the stirring effect was the best; the experiment verified that the mechanical properties of the composite coatings when stirred by the optimized stirring screw were better than those when stirred by hand. The research results can provide a theoretical basis for the structural design and parameter optimization of the automatic stirring screw.

Shale gas compressor is vulnerable to high temperature environment during operation. A large amount of waste heat generated during operation accumulates in the acoustic enclosure, resulting in overheating of motor, pipe, air cooler, etc., affecting the service life of key equipment and seriously threatening the safety of shale gas exploitation. Therefore, the DTY500 shale gas compressor was taken as the research object, a heat dissipation simulation model of the compressor skid mounted module system was established, the velocity field and temperature field characteristics were simulated, and the correctness of the simulation analysis method was verified by field experiments. Finally, the layout of the compressor skid mounted module was optimized. The results showed that most of the high-speed fluid did not cover the heat source areas such as the motor, compression cylinder and pipeline before the layout optimization of the air inlet and outlet, which was not conducive to the ventilation and heat dissipation of the equipment; after optimization, the relative heat dissipation of the system was increased by 46.34%, and the heat dissipation effect was significantly improved. The research results provide theoretical guidance for the optimization design of compressor skid mounted module system.

Metallurgical industrial robots play an increasingly irreplaceable role in modern industrial production. Due to the great improvement of industrial automation, people constantly put forward new requirements for the performance of metallurgical industrial robots, especially for the stability of them control system. In view of the problems of low trajectory tracking accuracy and lack of adaptive dynamic adjustment characteristics of metallurgical industrial robots, a fuzzy iterative Q-learning control algorithm was proposed. Taking 6-DOF (six-degree-of-freedom) dual-arm robot as the research object, the fuzzy control rules were compiled by using the Fuzzy toolbox and the position error and its change rate generated by the robot were taken as the input of the fuzzy controller, and then the quantization factor and scale factor in the fuzzy controller and the PD (proportional derivative) parameter in the iterative learning control was adjusted by introducing the Q-learning strategy, so as to complete the design of fuzzy iterative Q-learning controller. Then, combined with ADAMS (automatic dynamic analysis of mechanical systems) and MATLAB software, a 6-DOF dual-arm robot simulation platform was built to carry out the simulation of shaft hole assembly task with high-precision trajectory tracking. The simulation results showed that the 6-DOF dual-arm robot had high trajectory tracking accuracy in joint space, and could complete the coordinated assembly task of dual arm shaft holes, which verified the effectiveness and advancement of the proposed control algorithm. The research results can provide reference for the shaft hole assembly of dual-arm cooperative robot with high-precision trajectory tracking, and have certain practical application value.

In order to improve the printing accuracy of micro-flow extrusion 3D printer, aiming at the typical characteristics of its extrusion force control, such as time-varying and nonlinear, the extrusion process of printing materials was analyzed based on the extrusion force model, and a variable universe fuzzy PID (proportion integration differentiation) control strategy was proposed to realize rapid adjustment when the extrusion force changed irregularly in the extrusion process. At the same time, the MATLAB software was used to establish the simulation model of extrusion force control system to carry out the simulation analysis of different control strategies, and the self-built experimental platform was used to print the real object to verify the feasibility of the proposed control strategy. The simulation and experimental results showed that the variable universe fuzzy PID control strategy had a significant effect on improving the surface quality of formed body and the forming accuracy. The proposed variable universe fuzzy PID control strategy can provide some reference for the stable control of extrusion force of extrusion 3D printer, and also can provide some reference for similar time-varying and nonlinear control systems.

In order to study the influence of the series double circuit hydraulic brake valve on the braking performance of the wet spraying machine, according to the structure and working principle of the brake valve, taking into account the nonlinear factors such as the steady-state hydrodynamic force, the dynamic model of the hydraulic braking system was established using the bond graph theory. Based on the MATLAB platform, the static and dynamic characteristics of the brake valve were simulated and analyzed, and an experimental platform was built on the wet spraying machine to test its braking performance. The results showed that the output pressure of the brake valve had a proportional characteristic, the brake response of the rear axle was faster than that of the front axle, and the brake pressure of the rear axle was about 0.2 MPa higher than that of the front axle; the design of two-stage braking pressure gradient of the brake valve could meet the braking demand of the wet spraying machine with large kinetic energy difference at high and low speeds; the step response of the brake valve was rapid, the system could become stable within 0.3 s, without obvious pressure overshoot, and the braking performance was stable; in the reset phase of the brake valve, the brake cylinder quickly discharged the oil in the working chamber into the oil tank to release the brake. The test value of brake pressure was basically consistent with the simulation value, which verified the accuracy of the model. The research results can provide reference for parameter matching of braking system and optimization of brake valve structure.

Because of the low radial stiffness of the thin-walled casing, chatter is easy to occur during machining, which affects the machining quality and efficiency of the workpiece surface. Therefore, a rubber damping flexible fixture was designed, which could support the inner wall of the workpiece in a large area, thereby improving the processing stiffness of the workpiece. An equivalent dynamics model of workpiece-fixture system was established, and the accuracy of the model was verified by the milling experiment of the casing. The vibration reduction performances of rubber damping flexible fixture and traditional fixture were compared and analyzed. The influence of milling force loading frequency, pressure of platen, pressure of T-shaped platen and pressure of pushing block on the vibration of workpiece-fixture system was studied. The results showed that the acceleration effective value of the workpiece under the working condition with damping fixture was reduced by 43.33% compared with the traditional fixture; with rubber damping flexible fixture, the workpiece could avoid the frequency range of violent vibration in the range of 400-900 Hz, and the vibration amplitude was greatly reduced; with the increase of the pressure of platen, the acceleration effective value of the workpiece decreased first and then increased; for workpieces with different heights, different pressures of platen should be used to reduce the vibration of workpieces during processing; in actual processing, the pressure of T-shaped platen should exceed 3.56 MPa, and the pressure of pushing block should exceed 0.26 MPa, that was, the thrust of hydraulic cylinder should exceed 20 kN. The research result has important guiding significance for the field application of rubber damping flexible fixture.

In order to ensure the operation economy and stability of mechanical vapor recompression (MVR) system, the matching characteristics of centrifugal vapor compressor and evaporator in the MVR system were studied. In view of the change of heat transfer coefficient of evaporator under new operation, operation and scaling conditions, the concept of temperature resistance characteristic curve of evaporator operation was put forward, and it was superposed with the temperature rise characteristic curve of centrifugal vapor compressor, so as to carry out matching analysis of centrifugal vapor compressor and evaporator. Through analysis, it was found that the design flow of centrifugal vapor compressor was too large or the heat transfer area of evaporator was too small, which would lead to insufficient matching and easy surge, thus affecting the operation stability of MVR system. However, the design flow of centrifugal vapor compressor was too small or the heat transfer area of evaporator was too large, which led to excessive matching, resulting in poor operating economy of the MVR system, and may even cause the MVR system to be unable to establish thermal self cycle. The results showed that the centrifugal vapor compressor had unstable surge during the startup of MVR system, and the unstable area could be avoided by temporary adjustment of system parameters or by taking auxiliary measures. The surge margin of centrifugal vapor compressor should be more than 20% and the design margin of heat transfer area of evaporator should be 30% during design; the deviation between actual evaporation temperature and design temperature during MVR system operation should be controlled within ±5 ℃. The research results can provide reference for the design and debugging of MVR system.

Aiming at the problems of large amount of data collection, low collection efficiency and binding experimental objects existing in the current insect flight information collection methods, an automatic collection device based on visual inspection technology was designed. The device mainly included obstacle channel module, motion trigger acquisition module, flight path information module and automatic acquisition control system. Firstly, gap controller was designed according to the requirements of the control function, and closed-loop control was realized by using hardware such as laser ranging sensor and stepping motor; secondly, the STM32 microcontroller was used as control terminal, and the Blackfly S USB3 high-speed camera was triggered by using motion direction detection algorithm to realize the sequence image acquisition of insects in the specified motion direction; then, using the open-source computer vision library OpenCV to analyze the collected sequence images and obtain the flight path information of insects; finally, the embedded control system coordinated the communication between modules to achieve the design requirements of efficient and stable acquisition of insect flight information. In order to verify the applicability and accuracy of the device, Apis cerana was selected for the gap crossing experiment. The experimental results showed that in a static environment, the device could obtain complete and clear flight sequence images. The average accuracy rate reached 73.24%. The acquisition performance was stable, which effectively improved the acquisition efficiency. By analyzing the flight path information of honeybee, it is inferred that the mechanism of gap recognition is related to the amplitude and speed of its lateral movement, which provides support for in-depth research on the flight mechanism of Apis cerana.

The traditional dish-type solar thermal power generation system adopts slewing ring and spiral elevator to track the azimuth angle and altitude angle of solar, but it is unable to automatically adjust the posture of the condenser mirror element to cope with external disturbances. Using the parallel mechanism to realize solar tracking not only has the inherent advantages of high stiffness and small tracking error, but also can automatically adjust the posture of condenser mirror element. If the traditional spherical hinge is used, due to its physical limitations, the deflection ability of the tracking mechanism can not accurately meet the technical requirements of a wide range of solar tracking angles. Aiming at the above problems, a new dish-type solar tracking platform based on 3-RPS parallel mechanism was designed by using a new passive spherical hinge, and its tracking angle range was calculated; at the same time, the orientation workspace of the 3-RPS parallel tracking mechanism was calculated by establishing the inverse kinematics equation of the general 3-RPS parallel mechanism and combining with the spherical coordinate search method. According to the influence law of its structural parameters on the orientation workspace, the optimal values of structural parameters were determined. The results showed that: when the new passive spherical hinge was selected, the shape of moving and fixed platforms was isosceles triangle, the rotation pair axes were coplanar and triangular, the radius ratio of the moving and fixed platforms was two, and the branch chain length was twice the moving platform radius, the structure of new dish-type solar tracking platform met the design requirements, and the adjusted orientation workspace met the angle range required for solar tracking. The research results can provide reference for the subsequent structure design and parameter optimization of solar tracking platforms.

In order to improve the utilization of solar energy, a solar intelligent tracking system based on light intensity perception was designed according to the maximum power tracking principle. Firstly, based on the working principle of the solar intelligent tracking system, its overall structure was designed; then, based on the performance requirements of each module of the solar intelligent tracking system, the hardware equipment selection and the software design were carried out; finally, the corresponding experimental platform was built to assemble and debug the solar intelligent tracking system, and its performance was verified through functional test. The results showed that the designed solar intelligent tracking system could realize the intelligent tracking of solar panel to sunlight, and could complete remote control; in addition, the system had the advantages of simple structure and low cost, and it could not only save energy, but also provided good power supply, which met the needs of high-tech products, and conformed to the development trend of modern energy utilization.

The utilization of unmanned aerial vehicle (UAV) technology to realize the power line laying is gradually becoming the main trend of power industry development. Studying the UAV autonomous stringing technology can effectively improve operational efficiency, reduce construction cost and ensure security of workers. However, the problems of UAV stringing technology at this stage are mainly as follows: 1) Most UAVs rely on manual control or ground station to release waypoint control, which has a low level of intelligence, and long-term operation will bring strong load to electric workers; 2) The UAV lacks autonomous obstacle avoidance ability and has insufficient perception ability, and the obstacles such as wires and poles will cause safety hazards to it. In order to solve the above problems, fitstly, the hardware framework and the modular software framework based on ROS (robot operating system) of UAV autonomous stringing system were constructed, and on this basis, the stringing task planning algorithm and the stringing bow detection algorithm were implemented, so that the UAV had a stable autonomous stringing capability. Then, the collision model of UAV was constructed by using collision detection method, and the path planning algorithm of UAV was proposed. At the same time, the ground station-based obstacle avoidance strategy was introduced to effectively improve the safety of UAV. The experimental results showed that the software and hardware framework of the designed UAV autonomous stringing system was reasonable, and the stringing task planning algorithm could help the UAV complete the autonomous stringing task efficiently and stably. The ground station could monitor the status of the UAV in real-time, and assisted the UAV to avoid obstacles when necessary, so as to ensure the safety of UAV to the greatest extent. The designed system is safe and reliable, and can meet the actual electric stringing operation requirements.

Aiming at the difficulties of status monitoring and predictive maintenance of complex mining equipment under harsh working conditions, a predictive maintenance system based on digital twin was proposed by combining various comprehensive modeling, analysis and prediction techniques, such as status monitoring, fault warning and predictive maintenance. Firstly, the design flow and construction principle of digital twin of complex mining equipment were introduced, and the function of predictive maintenance system was realized in the process of building digital twin. Then, the status data acquisition method based on the LabVIEW, MySQL and Unity3D was studied, and the Unity3D development engine was used to build a three-dimensional visual status monitoring platform for complex mining equipment, and the current equipment status was visualized through virtual space. Finally, the applicability of optimized BP (back propagation) neural network in the fault warning of complex mining equipment was analyzed. At the same time, the predictive maintenance model of key parts of complex mining equipment was established by MATLAB software, and the warning results were transmitted to the Unity3D development engine through MySQL database to drive and deploy the preset maintenance process, so as to achieve the fault warning of key parts under the real-time monitoring of equipment status. According to the actual maintenance process of shearer hydraulic system, a mixed reality (MR) predictive maintenance strategy was formulated, and the effectiveness of the hydraulic plunger pump of shearer rocker arm was verified by taking it as the experimental object. The results showed that the fault prediction accuracy of the proposed predictive maintenance system was higher than 90%, and the fault warning results could drive HoloLens glasses to achieve the maintenance interaction of virtual guidance, which verified the effectiveness of the predictive maintenance function of the system. The research results can provide new ideas for predictive maintenance of complex mining equipment.

Aiming at the problems of low efficiency of manual preparation process of liquid culture medium and lack of automatic preparation system of liquid culture medium with complete process at home and abroad, an automatic preparation system of liquid culture medium based on programmable logic controller (PLC) was developed, which used the architecture that combined with action and perception layer, transmission layer and application layer, and consisted of feeding subsystem, discharging subsystem and control subsystem. The system realized the automatic selection and proportion of components based on the culture medium formula, online pH monitoring and dissolved oxygen (DO) monitoring, as well as the automatic cleaning, filtering, mixing and subpackaging of liquid culture medium through the combination of PLC, MCGS (monitor and control generated system) touch screen, sensors and execution equipment. At the same time, the monitoring data could be collected in real time and displayed graphically, and its whole process could be traced and stored. For the system error, the error model was obtained based on the test data, and the error correction was determined through prediction. Through actual test and correction, the relative error of the designed system for preparing liquid culture medium was below 0.336%, the repeatability error was below 0.274%, the maximum control error of pH was ±0.18, the maximum measurement error of pH and DO was ±0.04 and ±1%, which met the preparation requirements of liquid culture medium. The research results have certain reference significance for the development of the whole process automatic liquid medium preparation system.