The dynamic characteristics is an important index to measure the performance of machine tools.However, there is no better method to evaluate the dynamic characteristics of whole NC (numerical control) machine tool. Through the excitation of real dynamic cutting force to the NC machine tool, the dynamic characteristics of the machine tool under the action of cutting force can be quickly obtained. In view of the fact that the cutting parameters would affect the amplitude of cutting force corresponding to each frequency component, a dynamic excitation force model was established based on the dynamic cutting forces under different sample materials and cutting parameters.The dynamic characteristics of the NC machine tool in different frequency bands could be tested by frequency band excitation. Through the finite element simulation analysis, the dynamic characteristics of NC machine tool in each frequency band was judged. The main frequency components in the vibration of machine tool were obtained by fast Fourier transform of vibration signal, which could provide guidance for optimizing the dynamic characteristics of machine tool. The dynamic stiffness of different machine tools under excitation of various dynamic cutting forces was compared to distinguish which machine tool had better dynamic characteristics. Finally, the simulation results were verified by the excitation test. The results indicate that the above method is simple and practical, and can quickly evaluate the dynamic characteristics of NC machine tool, which has certain practical value.

Aiming at the problem that the motor jitters at the acceleration inflexion point during the operation of high-precision ultra-high pressure liquid pump,an equal-area smoothing compensation control method is proposed. The running curve of liquid pump was treated smoothly to ensure the liquid phase pump smooth transition at the acceleration inflexion point with high initial speed and no jitter. The displacement reduced due to smoothing treatment was compensated to ensure that the displacement was same before the end of the single operation cycle of the liquid pump, so that the total amount of liquid suction and discharge of the liquid pump remained unchanged.Finally, the motor running test, flow accuracy detect test, response speed detect test and ultra-efficient separation test were carried out to prove the feasibility of the equal-area smoothing compensation control method. The tested result showed that the equal-area smoothing compensation control method could solve the problem of motor jitterd at the acceleration inflexion point with high initial speed, and the flow precision of the output liquid of liquid pump was improved from 0.081% to 0.055%. The eaqul area smoothing compensation control method effectively improves the flow precision of the output liquid of liqud pump, and has the characteristics of strong instantaneity and high calculation accuracy, which can provide a certain theoretical basis for improving the efficiency of sample detection.

Characterizing Braille on the smart touch screen mobile terminal is a practically significant but difficult task. In order to enable the visually impaired obtain the information by touching the Braille on the smart touch screen mobile terminal, three common Chinese Braille encoding methods based on mobile terminal with variable friction tactile were proposed, which were general Braille encoding method,tone embedding encoding method and four-lines two-columns encoding method.According to the principle that the ultrasonic vibration generated by piezoelectric sensor could produce variable friction tactile on the object surface, the Chinese Braille tactile code was realized on the smart mobile terminal. Through two systematic experiments on 12 blind users, the usability of encoding method was evaluated from the aspects of reading efficiency, reading accuracy and user satisfaction. Firstly, the usability of three encoding methods was evaluated (experiment 1). Based on the results of experiment 1, the four-lines two-columns encoding method was selected to compare with the vibration motor tactile feedback encoding method based on right-sliding touch reading mode for usability. The results of experiment 1 showed that the average reading efficiency of three encoding methods was 8.82, 4.91 and 4.12 s/Chinese character, and the average reading accuracy was 98.6%, 96.8%, and 98.6%, respectively. Among them, the score of four-lines two-columns encoding method was the highest. The results of experiment 2 showed that,compared with the vibration motor tactile feedback encoding method based on right-sliding touch reading mode, the four-lines two-columns encoding method had higher reading efficiency, reading accuracy and user satisfaction. In conclusion, using the four-lines two-columns encoding method is able to encode and read the common Chinese Braille on the mobile terminal, which can provide a new way for the visually impaired to read Braille on smart mobile terminal.

Aiming at the problem that the wall climbing robot is difficult to realize complete coverage detection on the outer wall of the oil tank, a priority heuristic path planning algorithm based on rolling window was proposed. The grid map was used to model the environment in the rolling visual window, and the priority heuristic algorithm was used to search coverage path in rolling planning window. For the existence of U-shaped obstacles in the environment, the recognition and direct filling of U-shaped obstacle were carried out. When the robot entered the dead zone, the dead zone escape algorithm was enabled to make the robot escape the dead zone smoothly. The simulation results showed that the path planning method could guide the wall climbing robot to achieve complete coverage efficiently under the condition that the outer wall environment of oil tank was unknown. The research results have certain theoretical and engineering significance for improving the coverage efficiency of the wall climbing robot on the outer wall of oil tank.

In order to meet the requirements of friction stir welding technology and solve the shortage of friction stir welding robots in withstanding upset forces and welding flexibility，a rigid-flexible 3CD/2RPU-SPR friction stir welding robot was designed by adding 3 ropes to the 3DOF 2RPU-SPR friction stir welding robot. The kinematics modeling was carried out，the closed vector method was used to obtain the inverse solutions of the positions of the rigid part and the rope part of the 3CD/2RPU-SPR friction stir welding robot，the derivative method was used to obtain the velocity Jacobian matrix of the rigid part and the rope part, and the characteristic length method was used to dimensionless the Jacobian matrix. According to the dimensionless velocity Jacobian matrix, the MATLAB software was used to program and solve the kinematic performance indicators of the friction stir welding robot before and after adding the rope. The performance indicators of 3CD/2RPU-SPR friction stir welding robot were optimized by genetic algorithm, the structural parameters satisfying the global stiffness and global dexterity of 3CD/2RPU-SPR friction stir welding robot were optimized by setting the optimal individual coefficient, population number and number of genetic evolution. Results showed that the performance indicators including the bearing capacity, dexterity, global dexterity, stiffness, global stiffness of 3CD/2RPU-SPR friction stir welding robot were all improved, and moving was continuous at the high-quality workspace considering dexterity and stiffness, illustrating 3CD/2RPU-SPR friction stir welding robot could withstand more upset forces compared with 2 RPU-SPR friction stir welding robot, the movement flexibility was improved.10 sets of structural parameters that met the global dexterity and global rigidity of the 3CD/2RPU-SPR friction stir welding robot were found by genetic algorithm. Under comprehensive consideration of the friction stir welding working conditions, the optimal set was selected as the structural parameter of friction stir welding robot. Working with this structure parameter, the robot performance indicators were improved, and it was more suitable for completing friction stir welding. The research provides a theoretical basis for improving the quality of robot friction stir welding.

In order to minimize the extent of injury caused by internal overpressure, storage tanks for flammable and explosive substances such as oil and natural gas must be designed as weak roof structures according to the relevant design standards and specifications at home and abroad. The common 5 000 m³ vertical dome storage tank was analyzed to obtain a suitable design method of weak roof structure. Firstly, the structural parameters of the storage tank were designed and its weak roof performance was preliminarily evaluated by the GB 50341—2014 Code for the Design of Vertical Cylindrical Steel Welded Oil Tanks. Secondly, the structure of the storage tank was analyzed by the finite element method to obtain the key parameters such as lifting height, lifting radius, maximum equivalent stress and film stress under the conditions of empty, half and full tank. The strength， structural stability, failure mode and weak roof performance of the storage tank were evaluated on these key parameters. Finally, it was conducted to analyze the influence of key parameters such as the roof-wall connection weld angle height, the tank roof curvature radius, the boundary plate thickness and the tank height-diameter ratio on the weak roof performance. The results showed that the 5 000 m³ vertical dome storage tank designed by the GB 50341—2014 did not meet the weak roof performance. However, some methods which could enable the tank to meet the weak roof structure were proposed: the roof-wall connection weld angle height was increased to 3.75 mm, the tank roof curvature radius was increased to 3.0D (D was the tank diameter), the boundary plate thickness was increased to 15 mm, or the tank height-diameter ratio was increased to 2.0. The research results can provide a reference for improving the weak roof structure of the storage tank.

It is difficult to effectively control roll of vehicle during steering because the ordinary magnetorheological damper (MRD) can not provide a larger damping force at low velocity. In order to solve this problem, a sheer MRD with large damping force at low velocity was designed to improve the anti-rolling performance of vehicle. The structure and magnetic field design of sheer MRD were carried out, the damping force model of sheer MRD was built. The output characteristic curve of the damper was obtained through the Simulink simulation, and the polynomial mathematical model of the MRD was established. In addition, a dynamics six-degree-of-freedom steering-roll model of vehicle was established, and the optimal control of limiting amplitude was used to design the roll and smoothness coordination controller. The dynamics simulation of MR semi-active suspension limiter optimal control under the condition of double lane change with the software of MATLAB was carried out, and the simulation results showed that compared with the conventional MRD, vehicle body roll angle and lateral load transfer rate (LLRT) had a significant reduction under anti-rolling mode during steering, at the same time, parameters includeing the body acceleration, tire dynamic load and suspension dynamic deflection had some improvement. The research showed that the shear MRD could effectively inhibit the vehicle body roll during steering, improve body posture, and keep the vehicle in good smoothness. Besides, it could effectively improve turning capacity of vehicle and prevent the vehicle from rollover. The research result provides some theoretical supports for the application of MR semi-active suspension in the vehicle roll control.

Passive exoskeleton can reduce walking energy consumption for human and doesn't require electric energy, it has a wide range of applying prospect in military and civilian fields. Aiming at the problem that existing passive exoskeleton saves less energy and cannot adapt to different walking configurations, the multi-level energy lock principle was proposed and a passive exoskeleton mechanical foot was designed according to this principle. Based on multi-level energy lock principle, human-machine coupling ADAMS (automatic dynamic analysis of mechanical systems) dynamics models during energy storing phase and energy releasing phase in support phase during human walking were established. Subsequently, the passive exoskeleton mechanical foot was optimized: based on the dynamics models, the effect of two structure parameters including the spring position and spring release angle on the assist performance of the mechanical foot was analyzed, and the optimal values of the parameters were obtained by combining the heel height. Based on walking experiment and finite element analysis, the strength, stiffness, smoothness and comfort of the passive exoskeleton mechanical foot were optimized. After the optimization, the mass of the mechanical foot was reduced 500 g, the safety factor reached 3.04, smoothness and comfort had a comprehensive improvement. The research showed that the energy releasing phase was the key phase for the exoskeleton mechanical foot to play a role; spring release angle had a significant effect on the assist performance of the mechanical foot during the energy releasing phase, and thus became a key parameter affecting the assist performance of the mechanical foot. This research will provide an important reference for exoskeleton design.

The dynamic characteristics of wind turbine gearbox as a key component directly affect the operation of the whole wind turbine. A megawatt wind turbine gearbox was taken as the research object. After considering the structural flexibility of the box and planet carrier, the coupling dynamic model of wind turbine gearbox was established and its dynamic response was analyzed. In order to solve the problem that the gear modification amount obtained under single working condition might not be suitable for other working conditions, the internal excitation of gear pairs in wind turbine gearbox under each working condition was weighted. Taking the minimum internal excitation sum as the optimization target, the optimal modification amount for multiple working conditions was found based on genetic algorithm, and the dynamic response of the wind turbine gearbox was improved by combining the optimization of the macro-parameters of the gears. The results showed that the vibration acceleration and structural noise of wind turbine gearbox were effectively improved under all working conditions after macro-parameter optimization and gear modification. The research results provide a basis for improving the dynamics characteristics of megawatt wind turbine gearbox.

To solve the problem that the key technology of thermal error compensation in vertical machining center is difficult to select the temperature measurement point, a new method based on improved sequential clustering method is proposed to optimize the temperature measurement points for feed system of the machine tools. First of all, basing on experimental data, the mutual information value reflecting the correlation between temperature variables and thermal errors was calculated to select temperature measurement points of each component preliminarily and reduce coupling between measurement points. Then, according to the selected temperature measurement points, the temperature variables were classified by establishing the class diameter matrix and calculating the minimum error function. After that, basing on multiple linear regression, a thermal error model containing several different measurement points was established and statistical comprehensive analysis was conducted on the models, so the optimal clustering number and optimal temperature measurement points were determined. Results showed that the root mean square error and average residual of the thermal error model established by improved sequential clustering method could be reduced to less than 1 μm and 1.05 μm respectively under different processing conditions. Compared with the thermal error model established by the unmodified sequential clustering method and the grey relational degree fuzzy clustering method, this thermal error prediction model had higher prediction accuracy and better robustness. This method has a broad application prospect in the research of temperature measurement point for medium and small machining center feed system.

UUV (unmanned underwater vehicle) has a wide application prospects in the marine civil and military fields. As an important part, UUV pressure structure affects the load capacity of UUV and can guarantee the UUV execute navigation tasks safely and efficiently, so it is of great significance to optimize the pressure structure. In order to reduce weight at the greatest extent, and balance the contradictory among the weight, structural strength and stability of pressure structure, a multi-objective optimization method based on the combined weighted response surface method was proposed to improve the comprehensive capacities of UUV. The initial sampling points were obtained through the design of experiment, and the response values were calculated and the agent model was constructed by using the finite element tool.Then, the sub-target was normalized by the compromise programming method, and the weight coefficients of sub-targets were set up by combined weighted method to achieve the multi-objective optimal design of pressure structure. Taking a certain type of UUV as an example, the multi-objective optimal design for its pressure structure with trapezoid rib was carried out based on the proposed method.The weight of the optimized pressure structure was reduced by 6.6%, the rib stress was reduced by 6.7%, and the stability requirement was met at the same time. On this basis, the pressure structures with different rib forms were optimized with weight as the optimization goal and with weight, structural strength and stability as the comprehensive optimization goals, respectively. The results showed that the comprehensive optimization effect of the pressure structure with trapezoid rib was the best. This method is suitable for the multi-objective optimization of UUV pressure structure, and the research results can provide a theoretical guidance for the optimal design of UUV pressure structure, which has the practical engineering significance.

Wind load is an important load in crane design and operation. In recent years, gantry cranes have shown a development trend of "large-scale" and "flexible". Large gantry crane is increasingly sensitive to wind load due to its structural characteristics. However, the current Design rules for cranes only defines the static wind load on the upwind surface by the wind force coefficient and wind shield reduction coefficient, so that the wind load distribution on each surface of the crane can not be obtained. To solve this problem, the wind flow characteristics of large gantry crane were simulated by the computational fluid dynamics (CFD) software. Then,by using the unidirectional fluid-solid coupling method,the wind load data was introduced into the computational structural mechanics modelof crane and analyzed. Finally, the wind load response of gantry crane in the natural wind fieldwas obtained and compared with the calculation results according to the Design rules for cranes. The results showed that the wind load of the crane by using the CFD simulation was similar to that calculated according to the Design rules for cranes. However, the structural stress and structuralstrain of the crane obtained based on the fluid-structure coupling method were 22.77% and 17.23% larger, respectively. This was because each surface of the crane was affected by the wind load in the natural wind field, but the Design rules for cranes only quantified the wind load on the upwind surface, while ignoring the negative pressure and viscous force effects on the non-windward surface. The main beam and outriggers of the gantry crane were in tandem structure, and the upstream structure had a shielding effect on the downstream structure, which led to negative pressure on the downstream structure surface, while the shielding effect weakened with the increase of spacing ratio between the upstream and downstream structures. Resecrch results can provide a reference for the design and verification of large gantry cranes.

With the continuous development of combustion engine in the direction of high efficiency, great power and intelligence, the turbocharger that is the core component of the combustion engine is gradually moving towards high pressure ratio, high rotational velocity and great flow. Due to the high rotational velocity of the turbocharger compressor impeller, the impeller burst, especially when non-containment debris is generated, will seriously endanger the operation safety of combustion engines, even causing the personal injury or death. Therefore, it is extremely important to research the containment of turbochargers. Based on the finite element method, the bursting rotational velocities of the turbocharger compressor impeller under the centrifugal load were simulated by using the linear elastic material model and bilinear isotropic strengthened elastoplastic material model for the containments of turbocharger (rotational velocity and weakened way of compressor impeller).Then, the containment experiments for the complete compressor impeller and two weakened compressor impellers were carried out. The results showed that the bursting rotational velocities of compressor impellers calculated by the bilinear isotropic strengthened elastoplastic material model had a difference of about 2% with the experimental values, while the difference between the bursting rotational velocities calculated by the linear elastic material model and experimental values was about 16%, which was conservative. At the same time, both weakened compressor impellers burst under the predetermined rotational velocity, which verified the rationality and accuracy of weakened mode. It could be realized that the compressor impeller burst under a predetermined rotational velocity by controlling the size of groove. The research results lay a foundation for the follow-up containment analysis of compressor impeller.

Rotor shaft with dynamic and static axis structure is a new type of rotor shaft configuration with anti-ballistic capability for the helicopter. It is planned to study the load separation characteristics of independently designed drum-shaped spline rotor shaft and flexible coupling rotor shaft with dynamic and static axis structure. Through the finite element software, the load separation coefficients of two kinds of rotor shafts with dynamic and static axis structures were simulated, and the verifiable multi-channel loading tests were carried out. The results showed that when the wall thickness of static shaft was 7 mm, the load separation coefficient of rotor shaft with dynamic and static axis structure was significantly higher than that when the wall thickness of static shaft was 4 mm.The comprehensive load separation coefficient of flexible coupling rotor shaft with dynamic and static axis structure was 77.37%, which was slightly higher than that of drum-shaped spline rotor shaft with dynamic and static axis structure. The research results provide guidance for the design of rotor shaft with dynamic and static axis structure in the helicopters.

In order to study the inflation characteristics of annular collar on the ground and underwater, the test study and simulation analysis of the inflation process of annular collar were carried out. During the inflation test of annular collar on the ground and under different depths of water, the image of inflation process was obtained by a high-speed camera and the inflation time was recorded. A mathematical model was established,which was used to simulate the inflation process of annular collar on the ground and underwater. Based on this model, the influence of the inflation depth on the inflation process was analyzed, which showed that there was a significant nonlinear relationship between the inflation time and inflation depth. According to the analysis result, an inflation strategy using gas containers with different volumes under different depths was put forward,which could balance the stability and flexibility of the inflation process. The results of the simulation and the test show a good agreement, which proves the correctness of mathematical model and provides reference for the engineering design and application of inflatable devics underwater.

Problems of dyskinesia and cognitive impairment for the elderly are very common. To solve these problems，an easy-to-use and feature-rich service robot for the elderly was designed. To Reduce the operation difficulty of the service robot for the elderly, and optimize the user’s experience, the human-like motion control for the manipulator was achieved by establishing the spatial joint mapping model between human arm and manipulator. Firstly, according to the structure and degree of freedom distribution of human arm and manipulator, the human-machine joint mapping model was initially established. The working space of human arm and manipulator was simulated and compared using the Monte Carlo method. Because of the obvious difference in the spatial structure and degree of freedom distribution between human arm and manipulator, the working space of manipulator was too little, and the manipulator couldn’t imitate the movement of human arm. So, a corresponding improved scheme was proposed, and the human-machine joint mapping model was reestablished. The spatial pose information of the human joints was collected using the Kinect visual sensor， and the human coordinate system with the human left shoulder joint as the origin was established. The spatial vector method and the inverse kinematics method of human arm based on elbow constraint were used to solve the pose changes of human joints. Finally, an experimental platform for service robot for the elderly was established, and the validity and rationality of the improved human-machine joint mapping model and related control algorithm were verified. The experimental results showed that the manipulator could highly revert to the human arm's motion after joint remapping. The research results can be used for reference to improve the robot's interactive ability, and have a significant effect on reducing the robot operation difficulty, which also lays a foundation for the follow-up research on more complex human-like motion robot.