Repeated positioning accuracy is an important performance index of machine tools，which directly affects the quality consistency of processed products. The existing one-dimensional evaluation method, which takes the position deviation of linear axis motion direction as the evaluation parameter, is no longer suitable for evaluating the repeated positioning accuracy of precision machine tools. To make the evaluation more comprehensive, a three-dimensional method for evaluating the repeated positioning accuracy of machine tool linear axis is proposed. The one-dimensional positioning evaluation is extended to three-dimensional spatial evaluation by taking the spherical probability error radius as the evaluation index. Firstly, the mathematical model of the repeated positioning accuracy of the uniaxial motion parts and machine tool was established by homogeneous coordinate transformation, and the limitation of the existing one-dimensional evaluation method was analyzed. Secondly, the calculation process of the spherical probability error radius was simplified based on the properties of Chi-square distribution. Finally, the repeated positioning accuracy of machine tool linear axis was evaluated by the simplified spherical probability error radius calculation method. Taking the worktable of precision horizontal machine tool as the research object, the comparison between one-dimensional evaluation method and three-dimensional evaluation method was carried out through experiments. The results showed that the three-dimensional evaluation results based on the spherical probability error radius were basically consistent with the dispersion degree of spatial distribution of location points. Using the three-dimensional evaluation method can make the evaluation for repeated positioning accuracy of machine tools more comprehensive, and provide more reliable theoretical guidance for improving the overall performance of machine tools.

To find out the average transmission efficiency of the tripod universal joint, the motion law of the slider on the input shaft of the tripod universal joint was analyzed. Firstly, an auxiliary coordinate system was established at the center of the slider, and the sliding velocity of the slider at the center of the contact surface between the slider and the guide groove relative to the guide groove and the sliding velocity of the slider center relative to the guide groove were calculated. Secondly, the instantaneous transmission efficiency of the tripod universal joint was deduced by the relationship between the friction power loss and velocity. Finally, the expression of the average transmission efficiency of the tripod universal joint was obtained by integration. Through analysis， it was found that the average transmission efficiency of the tripod universal joint was related to the friction coefficient, the deflection angle between the input shaft and the output shaft, the trigeminal arm radius and the rotation radius. The average transmission efficiency of the tripod universal joint decreased with the increase of the friction coefficient, the deflection angle and the trigeminal arm radius, and increased with the increase of the rotation radius. This result provides an important theoretical basis for the design and application of the tripod universal joint.

At present, the planning and controlling problems of grasping in robotic multi-fingered hand system have not been solved perfectly for the objects with different sizes and shapes. Therefore, it is proposed to improve the dexterity of the robotic multi-fingered hand and expand its working space by using humanoid palm to reduce the difficulty of grasping planning and controlling. Firstly, the characteristics of human palm movement were analyzed and a robotic alterable palm mechanism of a humanoid hand was developed based on the skeletal structure of the human palm. The alterable palm mechanism had six degrees of freedom, and the fingers on the alterable palm mechanism were able to change the working space and the grabbing point position by the configuration transformation. Then, the mathematical model of the alterable palm mechanism was established, and its six degrees of freedom were analyzed when the number and position of grasping point were known. Then, the model of alterable palm mechanism was established by three-dimensional software to simulate the grabbing action. Lastly, the grasping experiment was carried out through the experimental platform and the physical prototypes to verify the grasping ability and adaptability of the alterable palm mechanism by grasping 13 kinds of objects with rigid and flexible fingers. It could be seen that the robotic alterable palm mechanism of a humanoid hand was able to realize the adaptive configuration simply and quickly, and it could complete the grasping of objects with large differences in size， weight and shape. It was suitable for grasping by two, three or four fingers and able to be connected with rigid or flexible fingers, which not only improved the grasping quality and adaptability of the robotic multi-fingered hand, but also reduced the difficulty of grasping planning and controlling. The research results provide reference for the universal application of robotic multi-finger hand.

With the rapid development of aviation manufacturing industry, higher requirements have been put forward for spherical grinding process. At present, grinding parameters are widely determined based on the processors’ experience, and the spherical contour can only be up to 2.2 μm. In order to achieve higher precision spherical machining, aiming at the generating method spherical grinding of GCr15 plunger parts, a feasible optimizing method for grinding parameters is provided. The orthogonal tests were designed and implemented by taking the grinding wheel speed, workpiece speed and feed speed as the influencing factors, and the spherical contour and consumed time as the objective function. The effects of different grinding parameters on the spherical contours were analyzed. Considering the complex relation between the grinding parameters and spherical contour, the back propagation (BP) artificial neural network (ANN) optimized by genetic algorithm (GA) was established to map the nonlinear relation between the spherical contour and grinding parameters based on the orthogonal experimental. Furthermore, the GA was used to optimize the extremum and locate the best grinding parameters combination. Finally, according to the optimal combination of grinding parameters, a number of validation experiments were carried out. According to the results, the spherical contour could be improved to 1.4 μm by using the optimized grinding parameters while remaining the machining efficient, which was 36% higher than that of traditional empirical method. The proposed optimization method of grinding parameters is reliable and effective, and can be directly applied to engineering, which is of great significance for realizing spherical precision machining.

In order to improve the life of air filter element which mounts the air intake system of the commercial vehicle and avoid frequent replacement of filter element in the harsh working condition, a high inlet pipe scheme designed for increasing the swirling fan is proposed, and the efficiency of pre-filtering dust and liquid mist of the air intake system is improved through the optimizing the swirling fan angle to achieve the goal of reducing costs. Firstly, the computational fluid dynamics (CFD) method was used to simulate the internal flow field of the high inlet pipe during the air intake process. The velocity streamline diagram and the velocity gradient cloud chart of three types of high inlet pipes were analyzed，and the mechanism of dust and liquid mist pre-filtered by high inlet pipe was obtained. Based on the variation law of velocity flow field of high inlet pipe, the optimum direction of vortex fan angle was proposed. Secondly, by using the rack test, the test of dust and liquid mist pre-filtered by optimized high inlet pipe was carried out, and the pre-filtration efficiency of dust and liquid mist was calculated. Finally, comparing the different dust and liquid mist pre-filtration efficiencies of high inlet pipes, the optimal angle of swirling fan was set as 75° according to the intersection of the two pre-filtration efficiency trends. The simulation and experimental results showed that the angle of the swirling fan had an important influence on the flow field and pre-filtration efficiency of the high inlet pipe during the working process of the intake system. The optimal angle of the swirling fan can help to improve the filtration performance of intake system, which reduces the dust and liquid mist entering the air filter and extends the life of the air filter element.

Pilots need to acquire and process a lot of visual information from the cockpit display interface during flight. A lot of visual information could make the pilot overload the brain, which is easy to cause flight accidents. The influence of the general aviation aircraft display interface on pilots' mental workload was estimated, which provided a basis for the optimization of the design of the general aviation aircraft display interface, reducing the mental load of pilots in the process of flying missions and improving the flight safety. Taking Cessna 172SP as an example, the mental workload of pilots during airfield traffic pattern was evaluated by subjective evaluation, performance evaluation and physiological measurement. Based on the analysis results of subjective scores, flight performance, EEG (Electroencephalogram) indicators and eye movement indicators, the order of mental workload for different flight stages of airfield traffic pattern was obtained. Eye tracking technology was used to locate the interface information that pilots paid attention to in different flight stages. The gaze hot zone that had a greater impact on mental workload in cockpit display interface were determined. It was showed that the pilots' mental workload during the horizontal flight was smaller, and it was larger during the landing flight. The interface side-slip indicator showed the greatest impact on the mental workload. In summary, mental workload measurement combined with eye movement indicators can effectively evaluate the performance of general aviation aircraft display interface.

In order to accurately select small target in the process of human-computer interaction in virtual reality and avoid the poor user selection accuracy due to the hand and controller jitter, a method was proposed based on Fitts' law to effectively measure the interaction time of small target in virtual situation. Firstly, the applicability of Fitts' law in virtual environment was clarified by analogy of moving distance and target width in graphical user interface. Secondly, the experiment was designed and the regression analysis of Fitts's formula in virtual situation was carried out. The correlation coefficient R²=0.896 3 indicated that the prediction time deviated from the real time. Then, MATLAB cftool was used to perform linear regression for different target sizes. Combined with the analysis of variance, the intercept of the fitted line was significantly correlated with the target size, and then combined with the Fitts's formula in virtual situation, the small target selection model was established in virtual reality. The new model was subjected to multiple regression analysis to determine the correlation coefficient R²=0.976 7, which indicated that the new model could effectively predict the time of capturing small target. Then the influence of the motion direction on the interaction time was analyzed. The new model had good applicability to different motion directions and it could effectively guide to calculate the good selection size in the virtual context interaction task. Finally, a virtual reality tunnel rescue experience system was taken as an example for experimental evaluation. The results indicated that using this model could effectively reduce the user interaction time and provide a better user experience when acquiring small target in virtual reality. The research results can provide effective guidance for the design developer to determine the interface layout in virtual situation and optimize the user interaction experience to some extent.

Processing capacity of traditional shale shaker can t meet the existing engineering requirements with the rapid development of petroleum drilling technology. Therefore, a new type of negative pressure drilling fiuid shale shaker is proposed. The gas-liquid ejector is the core equipment for the negative pressure shale shaker. The negative pressure area is formed under the screen by using the gas-liquid ejector, which makes the drilling fluid be subjected to a combination of vibration and negative pressure, and enhances the ability of the drilling fluid passing through the screen. The performance of the gas-liquid ejector directly affects the processing efficiency of the negative pressure shale shaker. In order to obtain a considerable working efficiency of the negative pressure shale shaker, it is necessary to design a structure and the working condition for ejector reasonably. The fluid momentum conservation equation was applied to the gas-liquid ejector in the negative pressure shale shaker, and the momentum equations of the gas-liquid mixing chamber under constant flow conditions were deduced as well as the computational performance equation of the gas-liquid ejector.The complex two phase flow in the gas-liquid ejector was simulated by computational fluid dynamics method (CFDM). The rationality of the numerical model was verified through comparison of the numerical simulation results and theoretical calculation results. Jet performances of gas-liquid ejector under different liquid volume fractions of ejected fluid, working gas pressures, nozzle distances and nozzle area ratios were simulated.It was found that the working parameters and structural parameters of the gas-liquid ejector had a great influence on its injection coefficient and vacuum degree. According to the simulation results, the ejector performance was optimal when the liquid volume fraction of ejected fluid was 30%, the working gas pressure was 300 kPa, the nozzle distance was 60 mm, and the nozzle area ratio was 3.484. The research results provide a theoretical basis for the design and field application of gas-liquid injection devices in negative pressure shale shaker.

In view of the complexity of the reliability analysis for the gas turbine pull rod combined rotor, the strength reliability analysis method based on Kriging surrogate model is researched. The proxy response surface was sampled by Latin hypercube sampling, and the stress distribution characteristics of parts at the turbine end of the pull rod combined rotor were obtained. The strength reliability mathematical model of pull rod combined rotor system was established, which was used to study the strength reliability of pull rod combined rotor from the perspective of parts and system. The strength reliability of pull rod combined rotor under the joint influence of uncertainty factors and strength degradation was studied, and the variation rule of strength reliability of pull rod combined rotor was revealed. The study results provide a certain reference for the reliability design, safe and stable operation and shutdown maintenance of the gas turbine unit.

Under the boundary ideal constraint condition, the body-in-white (BIW) static stiffness test system is complex and the cost is high. However, the error of using the boundary full constraint condition test is large, which cannot meet the accuracy requirement. To solve the problem above, a static stiffness simulation model of an automotive BIW under a certain boundary constraint condition was established, and the static stiffness of the BIW was numerically analyzed. Then, the effectiveness of the simulation model was verified by using the physical test. Based on the verified simulation model, the static stiffness simulation models of the BIW under 12 different boundary constraint conditions were established, and the contrast of the BIW static stiffness under different boundary constraint conditions was carried out. The results showed that there were 1 or 2 kinds of boundary over-constraint conditions which could replace the boundary ideal constraint condition in the static stiffness simulation analysis and test for the automotive BIW, and the error was within the range of -2%-2%. This method can not only reduce the test cost, but also meet the accuracy requirement. The research results have good promotion value and can provide references for automotive developers.

Machine vision is widely used in assembly, manufacturing，processing and other industrial fields to guarantee the product quality and control production procedure. Image processing technology is applied to automatic assembly production line, and the quality of TV backboard is detected online. In order to realize the capture of TV backboards with different models and sizes, the image template matching method was used to determine the current backboard model and detect the quality of the current backboard, and adaptive control system based on the visual servo was developed based on the collected images. The control system with Siemens PLC (programmable logic controller) as the control core, achieved PLC and Halcon software data docking through serial communication. The Halcon tool box was used to calculate the collected image of the TV backboard and extract the features of the target. The coordinate value of the capute process was analyzed, and the stepper motor adjustment offset was controlled to realize the adaptive capture process according to the result of position coordinate error. Aiming at the accumulative errors of position and posture of TV backboard obtained from image processing, a method was proposed to compensate the errors of visual positioning of position and posture of backboard by calculating the difference between the center parameter values of standard template and the incremental errors. The capture experiment proved that the adaptive control system based on the visual servo had high reliability and met the industrial production requirements of automated assembly. In the production practice, the application of the TV backboard automatic detection and capture platform can greatly improve the production efficiency of TV set, save labor cost, reduce labor intensity and improve production accuracy，and the platform has a good application prospect.

Aiming at the shortcomings of low working efficiency, high cost and unstable product quality in the process of flap discs production with traditional manual operation and the demand of high automation and high processing precision, a kind of control system of fixed length cutting and automatic layout for flap discs was developed. Firstly, according to the working principle and functional requirements of fixed length cutting and automatic layout system for flap discs, the modular design of its hardware and software was carried out taking ARM+DSP as the core. Secondly, in order to improve the control accuracy of the feeding mechanism, the position deviation and deviation change rate of the feeding mechanism were taken as the fuzzy input, and the correction of the PID parameters as the fuzzy output, The fuzzy gain self-adjusting PID controller was designed, which realized the high precision control of fixed length cutting. Finally, the effectiveness of the system was verified by experiment. The system had been put into practical production and application. The operation results showed that the fixed length cutting and automatic layout system for flap discs had stable performance, running period was 4 s, slicing precision was less than 0.2 mm. Using the fuzzy gain self-adjusting PID controller could obviously improve the dynamic response performance of feeding system and the precision of fixed length cutting, improve the processing quality and production efficiency of flap discs, meet the production requirements of enterprises. It has guiding significance for the development of control system of flap discs machine.

The pointing driving mechanism of navigation satellite antenna is the key component to realize high precision, long-life and reliable pointing of satellite inter-satellite link antenna. To meet the requirement of mechanical environment in launching stage, satisfy the constraint condition of vacuum, high and low temperature and satisfy the special high precision and long-life requirement of inter-satellite linkage antenna, a design method for improving accuracy and life of the driving mechanism was proposed based on the tandem assembly structure of stepper motor, harmonic reducer and encoder series and integrated shafting. The stress state and influencing factors of the pre-tightening shafting of the driving mechanism were analyzed in theory. The pre-tightening force, starting torque equivalent test and service life test for driving mechanism shafting were carried out, and the load characteristics of the designed driving mechanism were analyzed. The lock nut of the driving mechanism shafting was improved to optimize the force of driving mechanism shafting. To verify the correctness of the designed driving mechanism and its improved method, the precision test and life test under different thermal environments were carried out on the ground. Finally, it was verified that the driving mechanism for navigation satellite antenna could meet the requirements of on-orbit stable operation with high precision and long-life under special conditions. The analysis and the test of the pre-tightening force for mechanism shafting has significant engineering guiding significance.

In order to improve the temperature uniformity of phased array antenna with multiple sources, based on the excellent mass transfer characteristic of the plant leaf veins, a leaf vein-shaped microchannel heat sink for phased array antenna with multiple sources was proposed. Firstly, the temperature distribution of heat sources in heat sink was displayed through the simulation analysis of flow and heat transfer performance of the leaf vein-shaped microchannel heat sink. Then, the structure of leaf vein-shaped microchannel was optimized by minimizing the standard deviation of heat source temperature, and an asymmetry leaf vein-shaped microchannel topology structure was achieved. Lastly, the test piece of aluminum-based microchannel heat sink was made by metal 3D printing and its heat transfer performance was tested. The numerical simulation results indicated that compared with the traditional parallel microchannel heat sink, the leaf vein-shaped microchannel heat sink not only enhanced heat transfer, but also made the heat source temperature more uniform and pressure loss smaller. The experimental results verified the excellent heat transfer performance of leaf vein-shaped microchannel heat sink. The research conclusion can provide basis for the heat sink design of phased array antenna with multiple sources.

In order to reduce the amplitude of resonant frequency drift when the ultrasonic oscillator was connected to the external load, the electromechanical equivalent circuit method and COMSOL Multiphysics 5.3 finite element simulation software were used to fabricate an ultrasonic oscillator based on performance-adjustable stepped horn. Finite element simulation and field test of the resonant frequency of the ultrasonic oscillator were carried out. Taking the washing machine as an example, the test platform similar to its principle was built, and the water with different liquid level was used as the external load of the horn. The effectiveness of adjusting the tuning inductance of the piezoelectric stack connected to the horn to solve the problem of resonant frequency drift of ultrasonic oscillator under different loads was studied. The test results showed that the resonance frequency of the ultrasonic oscillator increased as the liquid height of the water cup increased. By externally connecting the tuning inductance at the piezoelectric crystal pile of the horn, the resonant frequency of the ultrasonic oscillator would be compensated and return to the original resonant frequency value. The research had shown that when using ultrasonic oscillator for ultrasonic assisted machining, the ultrasonic oscillator had a certain effect on reducing the amplitude of resonant frequency drift caused by external loads. The research results can provide a new idea and new method for the tuning of ultrasonic oscillator.

The sand-collecting shovel is an important part of a small track sand removing vehicle. In practical working, a large impact force occurred on the shovel which developed a large deformation on the edge of the shovel. In order to improve the force condition of the shovel, the stress state of sand-collecting shovel during the sand-collecting process was studied. By the discrete element method (DEM) and multi-body dynamics, the total force and the force in X, Y and Z directions of sand-collecting shovel with straight board, 15° board and 30° board under the same working conditions were compared, respectively. At the same time, the velocity distribution of sand particles in the instant of cutting sand by shovel at different time was analyzed by using the DEM. Finally, a sand-collecting shovel test bench was designed and manufactured to simulate the sand-collecting process，and the working torques of the sand-collecting shovel with straight board and 30° board were measured. The research results showed that increasing the edge inclination angle of the sand-collecting shovel board can reduce the force of the sand-collecting shovel. Meanwhile, with the changing of the edge inclination angle of the sand-collecting shovel board, the velocity distribution of the sand particles obviously changed when the sand-collecting shovel touched the sand. The research results have guiding significance for improving the impact force of sand shovel and studying shovel-sand interaction process by using DEM.