Digital modeling, system simulation and optimization in the automotive production process are of great significance for improving the quality and efficiency of automotive production. In order to solve the common problem of low resource allocation efficiency caused by data link breakage in automobile manufacturing enterprises, a new type of digital pedestal system was proposed based on the painted body storage (PBS) of automobile, to achieve data chain integration and multi-source heterogeneous data fusion. At the same time, a vehicle sequencing strategy for PBS was designed, taking into account the constraints of the final assembly process on sequence optimization. The PBS outbound sequence was obtained by a genetic algorithm, and then the inverse ordinal pair was used as a reference index for PBS lane layout. The effectiveness of the proposed method and strategy was verified by applying the PBS system based on digital pedestal system to a certain automotive manufacturing enterprise. The research results provide a reference for enterprises to build internal integrated manufacturing platforms and design specific workshop units.

Digital twin is a concept that aims to establish a real-time mapping between physical space and virtual space. In order to expand the application of digital twin technology in laser machining, taking the processing of 7075 aluminum alloy by nanosecond laser marking machine as an example, the important role of finite element simulation in laser machining was expounded. However, due to the large computational amount of finite element simulation and the limited computing level of current computers, the simulation calculation time was long, which could not meet the real-time mapping required by digital twin technology. Therefore, a method of replacing finite element simulation with CGAN (conditional generative adversarial network) model was proposed. In this method, the CGAN model was trained by using the working condition images after image processing and the temperature cloud maps obtained by finite element simulation. Then, the trained CGAN model was packaged for building the surface temperature monitoring system for laser machining parts based on the digital twin. After completing the construction of the virtual end of the digital twin temperature monitoring system, the MQTT (message queuing telemetry transport) communication protocol was used to interact with the physical end to realize the remote monitoring and operation of the digital twin system. The surface temperature monitoring system for laser machining parts based on digital twin achieves the rapid simulation calculation of the surface temperature of parts, which solves the problems of long calculation time and inability to achieve real-time mapping by the finite element simulation. It can basically meet the monitoring and prediction of the surface temperature of laser machining parts, and has certain reference value in the field of laser machining temperature monitoring.

In order to solve the problem of difficulty in testing and performance verification of compliant mechanisms in the process of optimal design, the mechanical properties of thermoplastic polyurethane (TPU) material were studied by 3D printing technology. The effects of material hardness and print fill rate on the mechanical properties of TPU material were analyzed, and the better 3D printing parameters of TPU material were obtained. Using single factor and two factor tset combined with variance analysis, the primary and secondary factors that significantly affect the flexibility of TPU specimens were identified as TPU material hardness and print fill rate. Combined with the mechanical property test data of TPU material, the mapping relationships between the material parameters and material hardness, print fill rate of four commonly used hyperelastic material constitutive models, i.e. Mooney-Rivlin, Yeoh, Ogden and Valanis-Landel, were obtained. The results showed that with the increase of TPU material hardness and print fill rate, the flexibility of the specimens decreased; among the four hyperelastic models, Ogden model has a good prediction effect on the mechanical properties of TPU specimens under different printing parameters; there was no significant difference in the predictive effect of the four models under the same TPU material hardness and different print fill rates. The research results can provide reference for 3D printing and finite element simulation analysis of TPU material, and provide reliable technical support for the test, performance verification and sample production of compliant mechanisms in the design process.

Spray cooling technology is widely used in the efficient heat transfer of airborne equipment with high heat flux. In order to better carry out the experimental research on the heat transfer characteristics of spray cooling, an spray cooling experiment device with swing excitation was designed and built. Firstly, by monitoring the experimental data such as temperature, pressure and flow rate, and analyzing the uncertainty of the heat sink wall temperature, heat flux density and heat transfer coefficient of the simulated heat source, the spray heat transfer chamber system, swing control system and data acquisition and analysis system were designed. Then, the feasibility of the designed device and method was verified by conducting steady spray cooling heat transfer characteristics experiments under swing excitation with different amplitudes. The results showed that spray cooling could be divided into three stages: submerged spray, semi-submerged spray and normal spray; the abnormal discharge of heat transfer waste liquid caused by swing excitation changed the heat transfer behavior of spray cooling, and the heat sink wall temperature and heat flux density fluctuated violently during the swing process; after the swing stopped, the liquid accumulation began to decrease; with the decrease of liquid accumulation height, the heat transfer characteristics of spray cooling changed. In the process of spray cooling, the heat sink wall temperature increased by 26.47% under swing excitation with different amplitudes, about 10.915 ℃; the heat flux density of copper column decreased by 5.42%, about 4.126 W/cm². The designed experiment device is stable and reliable, and has certain value for the research and engineering application of the spray cooling heat transfer characteristics of airborne equipment.

Aiming at the key issues in the overall development of snakelike robots, including material selection, structure design and motion realization, a new multi-joint snakelike robot was developed. This snakelike robot was composed of 11 two-degree-of-freedom orthogonal joints, which could achieve three-dimensional high biomimetic motion while ensuring flexibility. The basic gaits of snakelike robot such as meandering, wriggling and tumbling were designed by using the serpentine curve, and an improved obstacle surmounting gait was further proposed. At the same time, the gaits of the snakelike robot were simulated in the V-REP software, and the motion trajectories and efficiency of different gaits were compared. Finally, through the gait experiment of the snakelike robot prototype, the influence of each control parameter in the gait model on the motion waveform and speed of the snakelike robot was analyzed, and the reliability of the body structure and control system of the snakelike robot was verified. The research results have important theoretical significance and practical guiding value for realizing the gait planning and motion control of snakelike robots.

In order to improve the stiffness and control accuracy of flexible manipulators, the variable stiffness control for flexible manipulators was studied based on the particle blocking mechanism. A variable stiffness rod was formed by filling plastic particles in the flexibility silicone tube, and its stiffness model was built through the theoretical analysis and experimental research. Three variable stiffness rods were symmetrically arranged in parallel to form a variable stiffness flexible manipulator. Based on the established experimental platform, the variable stiffness control and positioning accuracy analysis for the flexible manipulator were carried out. The results showed that particle blocking could not only achieve the stiffness adjustment of the flexible manipulator, but also improve its control accuracy; the shear stiffness of the flexible manipulator was proportional to the vacuum degree of the variable stiffness rod, and the positioning accuracy of the flexible manipulator was also proportional to the shear stiffness of the variable stiffness rod. The research results are of great significance in promoting the wide application of flexible manipulators in the fields of industrial robots and service robots, and improving the safety of human-machine interaction and human-machine collaboration.

In order to analyze the effect of thermal deformation of feed system on the motion repeatability errors of machine tool, a modeling method for thermal deformation of feed system based on a layered model-moving heat source was proposed. The feed system was divided into a screw layer and worktable layer, and the moving joint surface was equivalent to a spring. The finite element model was established by using solid element and contact element. The temperature field and thermal deformation of the feed system were obtained by applying moving heat source to the screw and guide rail. On this basis, the effect of worktable feed speed, bearing preload torque, and slider support distance on the motion repeatability errors of machine tool was analyzed and verified by experiments. The research showed that the worktable feed speed and bearing preload torque had a significant impact on the motion repeatability errors of machine tool, while the slider support distance had a relatively small impact on the motion repeatability errors of machine tool. The research results provide a basis for reducing the motion repeatability errors of machine tool in machine tool design and assembly.

In response to solve the current issue of requiring external rigid body pump and valve for flexible actuator, a flexible bending actuator driven by an embedded electrohydrodynamic pump was designed based on the motion characteristics of human finger bending and grasping. A electrohydrodynamic pump was designed, and the influence of electrode plate spacing and electrode hole diameter on the output flow and pressure of the electrohydrodynamic pump were analyzed through experiments. The dimensions of the needle electrode, hole electrode and other components of electrohydrodynamic pump were determined, and a prototype of the electrohydrodynamic pump was developed. Multiple electrohydrodynamic pumps were connected in series and parallel, and the relationships between input voltage and output pressure, output flow were obtained. Two electrohydrodynamic pumps in series were determined to drive the flexible actuator; a mechanical model of the flexible actuator was established, and bending simulation and experiments were conducted on the flexible actuator. The relationship between the driving pressure and the bending angle of the flexible actuator was obtained, proving the good bending performance of the flexible actuator. The experimental, simulation, and theoretical values of the bending angle were relatively consistent, and the theoretical and simulation models could accurately describe the bending deformation of the flexible bending actuator. The high integration of the electrohydrodynamic pump and the flexible actuator allows the electrohydrodynamic pump to directly drive the bending deformation of the flexible actuator, achieving the portability of the flexible bending actuator.

In order to improve the crushing efficiency and reduce energy consumption of the hammer mill, a new type of biomimetic hammer piece was designed with beaver incisors as biomimetic prototype. Firstly, the reverse reconstruction for beaver incisors was carried out to obtain an accurate three-dimensional model of beaver incisors. Then, the characteristic structure of beaver incisors was determined, extracted and characterized, and the obtained biomimetic coupling element was used for the tooth surface design of hammer pieces. Finally, through the hammer piece?material crushing simulation calculation, taking the fracture duration and maximum stress of material as the evaluation indicators of the biomimetic hammer piece performance, the response surface surrogate model of the structural parameters and performance indicators of the biomimetic hammer piece was constructed by the response surface method, and the optimal combination of structural parameters was solved by the Design-Expert software. The simulation results of material crushing showed that compared to ordinary hammer pieces, biomimetic hammer pieces caused larger material fractures, generated greater maximum stress when colliding with the material head-on, and required shorter time for material fracture. The experimental results of material crushing showed that after replacing the biomimetic hammer pieces, the production efficiency of the mill was higher and over crushing was improved, indicating that the service performance of the biomimetic hammer piece was better than that of the ordinary hammer piece. The research results can provide reference for the design of hammer pieces of mills for feed processing.

The performance of ultra-deep water pile hammer system directly affects the construction progress of large offshore oil and gas platforms. In order to conduct in-depth research on the failure mechanism of ultra-deep water pile hammer system, the reliability analysis and allocation research for the system was carried out. Firstly, the failure mode and effect analysis (FMEA) was conducted on the ultra-deep water pile hammer system, and an improved criticality analysis (CA) method was proposed based on the FMEA results. Then, using the improved AGREE (advisory group on reliability of electronic equipment) allocation method and reliability allocation method based on FMECA (failure mode, effect and criticality analysis), the reliability allocation research was carried out successively for subsystems and components of the ultra-deep water pile hammer system. Finally, the visual interface of the CA and reliability allocation process of ultra-deep water pile hammer system was designed in the MATLAB App Designer development environment. The results showed that there were a total of 27 failure modes in the ultra-deep water pile hammer system, and 9 components such as steel piles were weak links in the system; the system reliability after primary and secondary reliability allocation was 0.999 063 22 and 0.999 063 27, respectively. The reliability study of the ultra-deep water pile hammer system has identified the weak links of the system, which can provide certain theoretical guidance for its domestic design.

The co-simulation method can be used to analyze the kinematics, dynamics performance and hydraulic system characteristics of piston pump in real time, which can be widely used in the design and optimization of piston pump products. A distributed co-simulation of axial piston pump based on functional mock-up interface (FMI) was proposed to address the shortcomings of high discretization of analysis and optimization and low efficiency in traditional optimization processes. By developing automatic optimization components, the iterative optimization of key structural parameters of damping groove was achieved. Firstly, kinematics and dynamics analysis was carried on the piston pump shaft system, and the motion model and force model of the piston pump shaft system were established to determine the constraint relationship of shaft system components; secondly, a co-simulation model of the piston pump was established to study the motion, force, and deformation characteristics of the piston pump; then, a distributed co-simulation model of the piston pump was built based on cloud server, and heterogeneous scheduling of each simulation software was achieved through FMI technology; finally, based on cloud platform architecture, an optimization calculation template for the damping groove of piston pump was developed, achieving the solution of the optimal structural parameters of the damping groove and its automatic model creation. The simulation results showed that after optimizing the damping groove structure, the outlet flow pulsation rate of the piston pump was reduced by 35.78%. The proposed method can effectively improve the efficiency of simulation and optimization, and reduce the workload of research and development personnel.

Aiming at the problems of unstable operation and easy failure of transmission parts during acceleration and deceleration of carbon fiber winding machine with large moment of inertia, an optimization scheme of spindle operation curve based on improved Sigmoid acceleration and deceleration curve was proposed. Firstly, the quintic polynomial was used to compensate the mutation of the traditional Sigmoid acceleration and deceleration curve by constraining the velocity, acceleration and jerk of the starting point, connecting point and ending point of the curve. Then, the mathematical models of load torque, motor output power, strength and stiffness of spindle and number of winding coils were established based on the velocity and acceleration functions of the improved curve. The multi-objective optimization for the curve was carried out with the operating time of each stage as the design variables and the maximum motor output power and total operating time as the optimization objectives. Under the constraints of the number of winding coils, strength and stiffness of transmission parts and so on, the non-dominated solution set was solved by the multi-objective genetic algorithm NSGA-Ⅱ(non-dominated sorting genetic algorithm-Ⅱ), and the optimal solution was selected by the proportion selection function. Finally, through AMESim-ADAMS co-simulation, the operation effects of winding machine before and after acceleration and deceleration curve optimization were compared. The results showed that the total operating time, maximum acceleration, maximum load torque and maximum output power of the optimized winding machine were reduced by 41.7%, 75.8%, 75.5% and 72.8%, and the spindle operation curve was smoother, which verified the feasibility of the optimization scheme. The research results provide a new solution for the problem of unstable operation or transmission parts failure of rotating equipment with large moment of inertia.

In view of the adverse effects of dynamic modeling errors and uncertain perturbations on the high-precision trajectory tracking control of the end of manipulators, a novel sliding mode control strategy for manipulators based on the adaptive neural network was proposed. The control strategy could be divided into three parts: adaptive neural network compensation term, switching control term and equivalent control term. The introduction of adaptive neural network avoided the influence of modeling error and unknown external disturbance on the manipulator system, and improved the trajectory tracking accuracy. The switching control term could enable the manipulator system performance to quickly approach the sliding mode surface while approaching the equilibrium point at a very small rate, so as to ensure system stability while avoiding excessive chattering. The equivalent control term was used to compensate the gravity term and Coriolis force term of the manipulator dynamics model, which realized the linearization of the model and ensured the system control accuracy. Finally, the stability of the designed control system was proved by constructing the Lyapunov function, and the simulation experiment and comparison experiment were carried out in MATLAB/Simulink environment and robot system toolbox. The results showed that the proposed control algorithm could achieve high-precision trajectory tracking while maintaining the stability of the manipulator, which verified the correctness and superiority of this control algorithm. The adaptive neural network sliding mode control algorithm provides a solution for enhancing the trajectory tracking accuracy of the end of manipulators.

Laser mechanical drill bit is a new type of rock-breaking equipment, which is suitable for the development of ultra-deep oil and gas resources. In the process of drilling, the laser is first used to irradiate the rock, so that the mechanical drill bit can quickly break the rock, but at the same time, a large number of rock chip will be produced. If the chip removal performance of the laser mechanical drill bit is poor, it will lead to the secondary drilling and the bit wear will be aggravated, and frequent bit trips will seriously affect the drilling efficiency. Therefore, in order to improve the chip removal performance of the laser mechanical drill bit, a three-dimensional model of the laser mechanical drill bit was established, and the chip removal process was numerically simulated by using the EDEM-Fluent coupling method; at the same time, through the analysis of the downhole flow field of the laser mechanical drill bit, the chip removal performance indexes were put forward, and the flow channel inclination angle, flow channel diameter and laser channel width were optimized by the orthogonal test method, so as to improve the downhole flow field and chip removal performance. The results showed that after optimization, the laser mechanical drill bit had a flow channel inclination angle of 17°, a flow channel diameter of 10 mm, and a laser channel width of 5 mm; the downhole low-speed area accounted for 11.07%, which decreased by 26.19 percentage points; the downhole radial crossflow velocity was 27.93 m/s, which was increased by 61.54%; the annulus rock chip transport velocity was 8.97 m/s, which was increased by 46.57%; the average rock chip retention was reduced by 46.38%, and the average rock chip accumulation was reduced by 59.43%. In conclusion, the chip removal performance of the optimized laser mechanical drill bit has been effectively improved. The research results can provide a data reference for the hydraulic structure design of the laser mechanical drill bit.