In view of the characteristics of high nonlinearity and high computational complexity in the optimization design of construction machinery, as well as the demand for high-fidelity and low-cost simulation models, an optimization design method for construction machinery structure based on an adaptive Kriging surrogate model was proposed. Firstly, the design variable sample space of the construction machinery structure was partitioned using the Voronoi diagram method. The global sparsity index (GSI) of the sample points was defined to identify subspaces requiring node-adding, and global points were generated within these subspaces using the max-min criterion. Next, local node-adding subspaces were identified based on the potential optimal parameters, and local points were generated accordingly. Finally, by integrating a local refinement strategy, the generated global points, local points and potential optimal solutions were filtered and incorporated into the sample set to update the surrogate model, thereby improving the fitting accuracy of the surrogate model. It was applied to the surrogate model construction phase in the construction machinery structure optimization design to significantly shorten the computational time for traditional high-fidelity model simulation and improve the efficiency of the optimization design. The numerical example verifications and engineering application results demonstrated that, compared with the existing methods, the proposed method achieved faster convergence within an acceptable error range under the same node-adding number. In the lightweight design of the upper structure of the arm-type bucket wheel reclaimer and the front boom structure of the tower crane, after only one iteration, the maximum relative errors of the optimal solution were reduced to 0.09% and 0.59% respectively. The proposed method is feasible and effective in the structural optimization design of construction machinery.

Aiming at the problems of insufficient accuracy and weak generalization ability of traditional neural networks in fatigue life prediction of bridge cranes, a fatigue life prediction method based on physical-informed neural network (PINN) was proposed. Based on the fatigue crack propagation mechanism of the crane structure, a data model was constructed using bi-directional long short-term memory network, which extracted features from time-series load data and performed equivalent transformation. Subsequently, a physical model was established in combination with fracture mechanics theory to depict the evolution law of fatigue damage. The data model and the physical model were deeply integrated, and the fused dynamic stress data served as the input to the physical neural network, while the fatigue life was set as the output. A penalty term that satisfied the differential equation of the Paris model was used as the physical loss, which was combined with the network data loss to construct a minimized loss function. Precise prediction of the fatigue life of bridge cranes was achieved by optimizing this loss function. Taking the DQ40 kg-1.8 m-1.3 m small general-purpose bridge crane as an example, by comparing the measured data and predicted data of the fatigue life of the crane during normal operation, the feasibility of the proposed method was verified. The results showed that, compared with the convolutional neural network model, support vector regression model, and K-nearest neighbor model, the fatigue life prediction fitting accuracy of the PINN model increased by 19%, 24.9%, and 26% respectively. The research results provide a new strategy for predicting the fatigue life of cranes.

In the primary support stage of tunnel construction. The wet spray trolley pumping system is prone to pipeline blockage, which can lead to unplanned downtimes, construction delays and other issues. Therefore, it is urgent to enhance the capabilities of equipment failure prediction and operation maintenance. To address challenges including strong noise interference and insufficient complex feature extraction from long-term sequential data in fault prediction method of pipeline blockage, a pumping system pipeline blockage fault prediction model based on the CNN-LSTM-Attention model was proposed. Pumping pressure data were took as the prediction target and processed using interquartile range for outlier removal and Kalman filtering for data smoothing, ensuring the stability of input data under high-noise conditions. The model employed CNN (convolutional neural network) to extract local spatiotemporal features from pumping pressure data, integrated LSTM (long short-term memory) network to capture the long-term dynamic characteristics of pumping processes, and incorporated the Attention mechanism to adaptively weight the critical nodes of the fluctuating pressure, achieving high-precision pressure trend prediction. The experimental results demonstrated that the prediction performance of the proposed model was significantly superior to that of traditional models such as CNN, LSTM, and CNN-LSTM. Based on the model prediction results, a health status evaluation system for wet spray trolley pumping system was established, and its health status prediction platform was developed, effectively supporting the decision-making at the construction site.

Aiming at the problem that traditional yarn cylinder loading operation depends on manual operation, the industry is committed to achieving automatic grasping by robotic arms. To this end, the focus is on two key links of object enveloping and collision detection in automatic grasping of robotic arms. In order to solve the problem of insufficient envelope accuracy of the traditional hybrid hierarchical bounding box algorithm in complex scenarios, an improved hybrid hierarchical bounding box model based on convex hull structure was designed, which significantly improved the spatial fitness of the bounding box by constructing the convex hull constraints in the leaf nodes. Aiming at the problem of low computational inefficiency of the classical separating axis theorem in dealing with collision detection of complex convex polygons, a gradient descent-based separating axis optimization strategy was proposed. By establishing the functional relationship between projection length variations and separating axis rotation angle, the search direction and rotation step of separating axes were dynamically adjusted. Experimental results showed that compared with the traditional hybrid hierarchical bounding box model, the improved hybrid hierarchical bounding box model had obvious improvement in the envelope accuracy. Compared with the classical separating axis algorithm, the gradient descent separating axis algorithm reduced the average iteration time and the iteration count by 90.67% and 98.48%, respectively. The proposed method is suitable for complex working conditions in industrial scenarios where objects are densely arranged and require high-precision collision detection.

To investigate the application of piezoelectric inkjet printing technology in vertical interconnect processes for multilayer circuits, a composite additive-subtractive forming process for vertical interconnection holes is proposed. This process employed mechanical drilling and laser drilling techniques to create blind holes in interconnection circuits, followed by precise filling of these holes using piezoelectric inkjet printing technology, successfully achieving the fabrication of double-layer and four-layer vertical interconnection circuits. The experimental results showed that the interconnection holes formed by the laser drilling technique exhibited inclined pore walls, with the cured nano-silver ink forming a conical distribution and voids appearing within the filled holes. In contrast, the interconnection holes fabricated by mechanical drilling technique maintained good perpendicularity of pore walls, enabling the cured nano-silver ink to form tight and uniform connections with each circuit layer, free of defects such as voids or pores. All fabricated interconnection samples successfully achieved electrical conductivity between each circuit layer, and the average resistance of each circuit layer was less than 1.70 Ω. The composite additive-subtractive forming process for vertical interconnection holes, which integrates mechanical drilling, laser drilling and piezoelectric inkjet printing technology, provides a viable solution for vertical interconnections between multilayer circuits.

The traditional path planning algorithms that combine ant colony optimization (ACO) and genetic algorithm (GA) commonly suffer from unsmooth paths, slow convergence speed and high energy consumption. To address these issues, a path planning method based on dynamic fusion of ACO and GA (DACO-GA) is proposed to improve the efficiency and accuracy of path planning. In the initial stage, ACO was used to generate the initial population, and GA was introduced for optimization and adjustment. In later stages, the leading role of the two algorithms was dynamically switched, enabling coordinated complementarity between global and local search. The algorithm integrated adaptive pheromone distribution, dynamic evaporation factors and adaptive crossover/mutation probability adjustment mechanisms, which effectively enhanced search capability and mitigate the tendency to fall into local optima. Finally, optimization experiments were conducted on the key control parameters of the DACO-GA to validate the effectiveness of each improvement mechanism. The DACO-GA was compared with traditional algorithms across multiple typical scenarios to further evaluate its adaptability in complex environments. The results showed that the proposed algorithm could generate smoother and shorter paths, demonstrating strong global optimization ability and faster convergence speed. The DACO-GA not only provides an effective solution for complex path planning problems, but also offers technical references for the optimization in areas such as multi-agent cooperation and robot navigation.

Aiming at the problem that the swimming pool cleaning robot deviates from the predetermined trajectory due to external interference and steering slip when performing tasks, a trajectory tracking control method based on improved sliding mode control (SMC) and iterative learning control (ILC) is proposed. It aims to improve the trajectory tracking accuracy of robots under slip interference. Firstly, the kinematics and dynamics models of the robot were established, and slip parameters were introduced to characterize the influence of slip interference. Then, the robustness of the robot control system was enhanced by combining SMC, and a nonlinear integral sliding mode surface adapted to slip interference was designed. Meanwhile, the ILC was used to further improve the trajectory tracking accuracy. Finally, by using the PD (proportional-derivative) type closed-loop ILC control law as the feedback, the stability and convergence of the designed nonlinear integral SMC-ILC controller in the presence of slip interference were proved through theoretical analysis. The simulation results showed that compared with the traditional PID (proportional-integral-derivative) control, the nonlinear integral SMC-ILC had significant advantages in trajectory tracking accuracy and robustness. The experimental results verified the effectiveness of the designed controller in practical swimming pool cleaning robot applications, which could achieve precise trajectory tracking under external interference and slip interference, thereby improving cleaning efficiency. The research results provide a new solution for the intelligent control of swimming pool cleaning robots and offer theoretical basis and practical support for trajectory tracking control in related fields.

Aiming at the problems of poor motion adaptability and low friction-driven efficiency of soft crawling robots in diverse surface environments, a triangular surface texture design scheme with anisotropic friction characteristics is proposed. Based on the principle of inchworm movement, the triangular surface texture design is applied to the friction foot of the soft crawling robot and integrated with the pneumatic corrugated actuator to achieve multiple movement modes of the robot on different surfaces. Firstly, based on the assumption of constant curvature, the relationship between the elastic deformation and the pressure of the corrugated actuator was analyzed, and its kinematics model was established. Then, a friction force testing experimental platform was built to measure the anisotropic friction performance of the friction foot on the contact surfaces of different roughness. Finally, experiments on the forward and turning movements of the robot were carried out to test its motion performance on substrate surfaces with different roughness. Through kinematics experiments, the correctness of the kinematics model of the corrugated actuator was verified. Through experiments, it was measured that on the wooden substrate surface, the forward speed of the robot could reach 1.11 cm/s; on the acrylic substrate surface, the forward speed of the robot could reach 0.95 cm/s. In the turning motion experiment, the turning speed of the robot on the wooden and acrylic substrate surfaces could reach 3.48 (°)/s and 3.08 (°)/s, respectively. The results showed that the triangular surface texture design could effectively achieve anisotropic friction performance, and this friction performance increased first and then decreased with the increase of texture height. The triangular surface texture design can significantly enhance the motion performance of soft crawling robots on different substrate surfaces and has certain practical value.

Aiming at the problem that parallel flexible mechanisms applied in micro/nano-positioning fields struggle to decouple rotational motion from other degrees of freedom to form independent actuation units, the rotational motion decoupling mechanism based on orthogonal arrangements of reed-beam parallelogram mechanisms is extended. By replacing reed beams with arc beams, a series of flexible rotational nano-motion decoupling mechanisms based on arc beams are designed, and their compliance modeling and performance testing are conducted. Firstly, the configurations of flexible decoupling mechanisms with different arc beam heights were introduced. Each mechanism was composed of two identical orthogonal upper and lower parts, which fully utilized the compliance characteristics of arc beams in various degrees of freedom, enabling decoupling among multiple coupled degrees of freedom, including translational motions. Then, theoretical modeling of the flexible decoupling mechanisms was performed based on the compliance matrix method to determine their dimensional parameters and derive their output compliance. Finally, the accuracy of the theoretical compliance models was validated by combining finite element analysis with experiments, and the decoupling capabilities of different mechanisms were compared. The results showed that the relative errors between the finite element analysis and experimental results and the theoretical calculation results of each flexible decoupling mechanism's compliance were within 10%, and its decoupling performance was positively correlated with the height of arc beams on both sides. This type of flexible decoupling mechanism can be applied to the flexible mechanism design for multi-degree-of-freedom parallel micro/nano-positioning platforms, which has certain practical value.

Aiming at the collaborative design challenge of stiffness, thermal stability and lightweight for the focal plane substrate structure in space telescopes, the topology optimization method is adopted to conduct optimization design. Taking the focal plane substrate structure of a large space telescope as the optimization object, a topological optimization mathematical model with dual objective functions of minimizing compliance and temperature gradient was established, and the analytic hierarchy process was employed to determine the weight coefficients of objectives. Subsequently, the COMSOL Multiphysics software was used for solution, and the topological optimization results of the substrate structure were obtained. Finally, the substrate structure was reconstructed based on the optimization results and validated through finite element simulation. The results demonstrated that compared with the original substrate, the optimized substrate achieved a 39.94% reduction in mass, a 4.92% decrease in maximum displacement, and a fundamental frequency of 801.2 Hz, thereby meeting design requirements and achieving the lightweight goal. The research results provide a reference for the lightweight design of other engineering structures.

Aiming at the alignment problem of the multi-stage turbine shafting of heavy duty gas turbines, an optimization alignment method integrating the reaction force of bearing and relative displacement between bearings was established, and a verification in hot-state was conducted. Firstly, the finite element software ANSYS Workbench was used to simulate the deformation in cold-state of the shafting, and the reaction forces and vertical displacements of the key bearings were obtained. Secondly, a multi-parameter optimization method integrating reaction force of bearing and the relative displacement between bearings was adopted, and the optimal solution was calculated by using the MATLAB software. Then, the Fluent software was used to simulate and analyze the airflow distribution between the intake volute and the shafting, the temperature influence under the actual working state of the shafting was taken into account to verify the validity of the optimal solution in hot-state. Finally, the bearing 5# was lowered by 0.057 mm in cold-state, the shafting was precisely adjusted, and an alignment experiment in hot-state was conducted. The results showed that the vibration of the shafting met the index requirements, verifying the effectiveness of the alignment scheme. The proposed shafting alignment optimization method takes into account the actual temperature and complex loads of the shafting, and has a good guiding significance for the precise adjustment of the shafting.

Aiming at the problem of low efficiency of manual binding of anchor nets in coal mine tunneling faces, a mine anchor net binding device is proposed. The handheld actuator is the terminal actuator of the mine anchor net binding device. In order to deeply understand its working mechanism and verify the design reliability, the wire feeding, wire cutting and wire twisting processes of the binding mechanism were simulated and analyzed by using SolidWorks software and ANSYS software, respectively. It was concluded that the peak torque of the wire feeding gear during operation was 0.19 N·m, the peak torque of the slicing sheet was 0.54 N·m, and the peak torque of the wire twisting shaft was 0.40 N·m. The multi-body dynamics simulation for the transmission system of the binding mechanism was carried out by using ADAMS software, and the speed characteristic curve of the transmission components during operation and the load characteristic curve of gear meshing transmission were obtained. Based on the ANSYS software, the finite element simulation analysis for the gear meshing motion of the binding mechanism was carried out, and the stress distribution cloud maps of the gear mating surface during the meshing process were obtained. The contact fatigue strength and bending fatigue strength of the gears were checked and verified according to the calculated allowable stress. Finally, an anchor net binding device prototype and a handheld actuator input test platform were built, and the binding performance verification experiments were carried out. The experimental results showed that the performance of the handheld actuator was basically consistent with the simulation analysis results. The binding action was continuous and efficient, and the time for a single binding operation cycle was 1.8 s. The binding effect met the design requirements and actual application needs. The research results provide a theoretical basis for the optimal design and engineering application of the mine anchor net binding device.

Aiming at the problems of high complexity, poor universality and insufficient precision in the models for the limiting vacuum degree and its pre-pumping time of Roots pumps, a high-precision, concise and universal prediction model was constructed, so as to provide theoretical support for the performance optimization and precise evaluation of Roots pumps. A fully parametric rotor profile model based on shape coefficients was established to achieve an accurate description of the rotor's geometric characteristics. The swept area method was used to analyze the theoretical flow, and the calculation formulas for instantaneous flow, average flow and flow pulsation coefficient were derived. Based on the laminar flow theory, combined with the geometric characteristics of radial, meshing and end face clearances, leakage models for the three clearances were established. Among them, an innovative equivalent parallel rectangular plate model with equal end-leakage area was adopted for end face leakage. Based on the principle of balance between pumping flow and leakage flow, as well as the isothermal conversion theory of pre-pumping baseline volume, models for the limiting vacuum degree and its pre-pumping time were established respectively. Moreover, CFD (computational fluid dynamics) simulation was used to conduct multi-dimensional verification on flow characteristics, leakage flow, limiting vacuum degree and its pre-pumping time. The results showed that the maximum error between the theoretical value and the simulation value of the flow characteristic parameters under the involute profile was 3.84%, the consistency error between the theoretical value and the simulation value of the leakage flow was within 4.72%, the error between the theoretical value and the simulation value of the limiting vacuum degree was 4.03%, the error of the pre-pumping time was 1.88%, and the rationality of each model and equivalent method had been verified. The analytical error is within the acceptable range for engineering. The fully parameterized design method improves the correlation between the rotor profile and performance parameters, and has good operability and repeatability. It can be directly applied to the performance optimization and rapid design of Roots pumps, thereby providing reliable theoretical support for the engineering application of Roots pumps in medium and high vacuum systems.

To investigate the influence of asymmetric grooves on cavitation evolution and sealing performance of mechanical seals, the flat-bottom symmetric grooves and left-tilted and right-tilted asymmetric grooves were designed and fabricated. Meanwhile, a combination method of experiments and numerical simulations was employed to analyze cavitation behavior, liquid film pressure and phase distribution, as well as the sealing performance of asymmetric textured sealing end faces under varying operating conditions. The results showed that the left-tilted asymmetric design increased the cavitation area of the groove by approximately 21.3% compared to the flat-bottom groove, whereas the right-tilted asymmetric design suppressed the cavitation behavior of the groove, with a reduction of cavitation area up to 44.9%. Regarding sealing performance, both the left-tilted and right-tilted asymmetric designs contributed to suppressing end face leakage, achieving leakage reductions of approximately 20.4% and 40.7%, respectively. However, their tribological behaviors differed markedly: the left-tilted groove increased the frictional torque of the sealing end face by approximately 30.8%, whereas the right-tilted groove led to a reduction of about 42.6%. It was concluded that the gradually expanding design of the right-tilted structure mitigated the abrupt cross-sectional expansion at the groove inlet, enabling the fluid to better adhere to the groove wall and reducing boundary layer separation. This mechanism effectively inhibitd the formation of low-pressure regions, thereby reducing cavitation area. Furthermore, the smaller cavitation area enhanced the hydrodynamic pressure effect within the groove unit and the liquid film bearing capacity, thereby improving interfacial tribological performance. Additionally, a stable high-pressure sealing dam was formed at the groove outlet, thereby reducing leakage pathways. The research results can provide significant references for the optimal design of mechanical seal end faces.