To address the need for automated anomaly detection in industrial robot factory inspections, a novel industrial robot automatic anomaly detection method based on the TCN-Transformer model is proposed. The method designs a TCN-Transformer-based dynamic modeling approach for industrial robots, where real-time joint angles, angular velocities, and angular accelerations are input into the TCN-Transformer model to perform inverse dynamics. This generates adaptive real-time standard joint current signals, which are compared with the actual real-time current signals to measure similarity and enable adaptive anomaly detection. A cloud-edge collaborative industrial robot automatic anomaly detection system is built, enabling automatic information acquisition, real-time data collection, and automated anomaly detection for robots in the production testing area. Through multiple experimental scenarios, including multi-condition robot tests, joint anomaly injection experiments, and system stress testing, the proposed dynamic modeling method is shown to generate adaptive standard data with high accuracy. The anomaly detection method is able to locate faulty joints and maintain a high consistency with the severity of the anomaly. This system provides stable, accurate, and efficient automated anomaly detection for large-scale industrial robot clusters.

The pump driving mode of artificial muscles represents a valveless driving approach, offering advantages such as straightforward driving equipment and high system efficiency. Among the existing length prediction methods for pump-driven artificial muscles, the impact of load force has not been taken into account, resulting in deviations between theoretical and actual lengths, thus urgently demanding improvement. Firstly, an experiment is carried out to explore the influence of load force on the length of artificial muscles. It is discovered that for artificial muscles of varying lengths, the relative length variations caused by the same load force were consistent, but the absolute variations were related to the original length of the muscle. Specifically, the longer the original length of the artificial muscle, the greater the absolute length variation induced by the load force. Hence, for longer artificial muscles, the influence of load force must be considered. Subsequently, the relationship between the external load force and the length of artificial muscles is obtained through experiments, and based on this, the original pure geometric length prediction model is revised. Finally, it is hypothesized that the state variables of artificial muscles, such as the length of unloaded muscles, the muscle elastic modulus, the pressure-load force correlation coefficient, etc., are all functions of the injected volume. Thus, a length prediction method for pump-driven artificial muscles is established with the injected volume as the core variable, and verified through single artificial muscle experiments and parallel mechanism application experiments. The experiments indicated that this method can achieve considerable accuracy even under open-loop control conditions without position feedback. This provides a new technical approach for the application of pump-driven artificial muscles in the field of robotics.

The SSRMS-type reconfigurable space manipulator, based on passive telescopic links, can alter its scale by adjusting the lengths of two telescopic links. While inheriting the advantages of traditional SSRMS-type space manipulators, it possesses the capability of scale reconfigurability and is expected to play a significant role in future on-orbit missions. However, the passive telescoping scheme employed in its telescopic links poses challenges for the design of the reconfiguration operation controller. To address this, a joint torque optimization control method with singularity robustness is proposed to achieve precise control over the manipulator's reconfiguration operations. Firstly, the dynamic equations of the manipulator in reconfiguration operation mode are derived by employing a mapping projection operator-based dynamics modeling approach. Based on this, a Lyapunov-based controller is designed using the concept of linear projection operators. By sending drive torque commands solely to the active rotational joints, the released passive telescopic links can achieve the desired motion, thereby enabling the reconfiguration operation of the manipulator. Meanwhile, the controller ensures the minimization of active joint drive torques and the absence of any driving force at the released passive telescopic links. Subsequently, the damping least-squares inverse of the submatrix of the projection matrix in the motion constraint equation is introduced into the controller, endowing it with singularity robustness. Finally, simulation verification of reconfigurable operation control is conducted, and the results demonstrate that the proposed method is suitable for precise reconfiguration control tasks of the SSRMS-type reconfigurable space manipulator.

The accuracy of five-axis hybrid robots is one of the primary challenges they face in the field of precision machining and manufacturing. Due to the complexity and diversity of error propagation paths within its structure, constructing an accurate overall error model is particularly challenging. To address this issue, this study proposes a kinematic calibration method for five-axis hybrid robots. First, decompose the five-axis hybrid robot into a tool motion chain and a workpiece motion chain to reduce interference and error propagation between them. Next, a closed-loop vector equation is constructed for the tool motion chain, which includes a parallel mechanism, and the error model is derived through differential perturbation. By introducing an auxiliary measurement device to perform full pose measurements on the end-effector of the parallel robot, it is noted that the anisotropy of the end-effector's position/orientation errors leads to inaccurate identification results. To resolve this issue, a weighted matrix is introduced to establish an identification equation with isotropic residuals, thereby improving identification accuracy. Subsequently, error analysis and modeling are performed for the workpiece motion chain, and the error sources are decomposed into motion errors and zero-point errors, which are compensated through the calibration and tool alignment processes, respectively. Finally, the effectiveness of the proposed calibration algorithm is validated through both calibration and test workpiece machining experiments. The results show that by calibrating the tool and workpiece motion chains, the proposed method can significantly improve the robot’s motion accuracy and stability, thus meeting the high-precision machining requirements in the manufacturing field.

With the increasing application of micromanipulation technology in high-precision applications, achieving real-time sensing of the gripping force is crucial for improving the performance of compliant grippers. This study modeled, analyzed, and experimentally investigated the integrated force sensing function of a piezoelectrically driven compliant gripper based on strain gauges. By attaching strain gauges to the flexure hinge to construct a force sensing unit, a theoretical model of the relationship between gripping force and strain was established, and the influence of the flexible beam’s structural parameters on the strain response is analyzed. The results showed that reducing the width and thickness of the flexible beam and increasing its length significantly increased the maximum surface strain. Finite element simulations validated the accuracy of the theoretical model, with a relative error of only 4.22%. Experimental calibration established a linear relationship between gripping force and strain. The input voltage, input displacement, and strain relationships of the piezoelectric actuator were further calibrated for gripping copper wires with diameters of 800 μm and 400 μm, respectively. A third-order polynomial fit was performed on the average values of the experimental data using the least squares method to obtain a functional relationship between the input voltage/displacement and gripping force, providing an effective method for accurate prediction and dynamic control of gripping force.

Aiming at the high-speed and high-precision operational needs in the fields of electronic packaging, precision machining, and high-performance 3D printing, the accurate dynamic modeling of a modular reconfigurable 3T1R parallel manipulator is investigated. Firstly, based on the screw theory, the degrees of freedom and constraint characteristics of the branch are analyzed, revealing that the end effector of the mechanism can achieve decoupled three-translations and one-rotation motion. Secondly, the inverse position analysis of the mechanism is obtained by the geometric projection method and the closed-loop vector method. The velocity and acceleration mapping models for each joint and the end effector are sequentially established by utilizing the superposition principle of twist screws and the properties of Lie screws. On this basis, the inertia wrench of each component are represented using screw theory, and the compact system dynamics model is established using the principle of virtual work. Finally, the correctness of the dynamic model is verified by comparing the results of the SolidWorks&Simscape collaborative simulation with the theoretical model calculations. Introducing evaluation metrics for error analysis reveals that the torque errors of the three branches are all less than 0.050 3 N·m, with an average relative error of less than 0.67%；the torque error of the RUPU branch chain is less than 7.62×10^-5 N·m, with an average relative error of less than 1.73%；and the decoupling characteristics of the manipulator’s translational/rotational motion are further demonstrated through simulation. It provides an important foundational for high-speed and high-precision control of the manipulator.

Origami cubes are spatially enclosed polyhedral structures designed with creases and slits to achieve functions of folding and deployment. The advantages of good interchangeability, high modularity, and flexible scalability render the cubes valuable in aerospace and civil applications such as on-orbit assembly, reconfigurable robotics, and emergency rescue equipment. To address the needs for limited transportation space, multi-task and multi-condition applications, a multi-state origami cube structure and design method that can reverse between two and three dimensions and transform between large plane, box, and small plane are proposed based on the metamorphic principle. Firstly, according to the metamorphic principle, the topological structure of the mechanism is changed by merging and separating components, enabling the box to have two motion stages: large plane deployment and small plane folding. Secondly, based on graph theory, the connections between single-loop mechanisms are analyzed, and the kinematic model of the mechanism is established using the D-H method and vector method. Thirdly, the vertex-splitting method is used to split the six-crease into a combination of two five-creases, thereby reducing the DOF of the mechanism's motion to optimize the motion process. Finally, the thick-panel metamorphic origami cube is designed by combining the offset panel method and the axis shifting method, and a parameterized thick-panel model is established. The research results show that the thick-panel metamorphic origami cube has two single-DOF motion stages, and the mechanism exhibits self-locking characteristics in the cube state. This study can provide reference and guidance for the basic and applied research of origami engineering.

To solve the dynamics and stiffness modeling difficulties caused by the multi-closed loop and multi-constraint characteristics of parallel mechanisms (PMs), an integrated method of elastodynamic and stiffness modeling for PMs that is applicable to both the pre-design and the prototype design stages is proposed. The model first establishes the element stiffness and mass matrices of each free body based on the matrix structure analysis method, and then extracts the global independent generalized displacement coordinates of the mechanism in the global coordinate system by combining multi-point constraint theory and kinematic constraint equations. The elastodynamic equation of the mechanism is established through Lagrange equation, and the elastostatic stiffness model corresponding to the exit node is established through static condensation technology. Based on the Lagrange equation and overall stiffness matrix, an ellipsoid index for the extreme stiffness and isotropy of the mechanism is established. A multi-objective genetic algorithm is used to establish the Pareto front of the multi-objective optimization problem. Further, the cooperative equilibrium point method is combined to determine a set of optimal solutions on the Pareto front. On this basis, the prototype of the 3PRRR PM is designed. The stiffness and mass matrices of components involving irregular cross-sections are extracted using finite element software to replace those of beam elements in the pre-design stage to achieve rapid performance evaluation of the three-dimensional model of the 3PRRR PM. The maximum error between the proposed theoretical model and the finite element model is within 1.48%. The performance comparison of the mechanism before and after optimization shows that the fundamental frequency, isotropic of the linear stiffness and angular stiffness have been improved by 2.3%, 19.05%, and 43.75%, respectively. The reasonable cross-section design of the links based on the screw theory further improves the performance indices of the mechanism, verifying the correctness and effectiveness of the model proposed in this work.

As the core components of fuel supply systems, fuel gear pumps have been widely applied in high-end equipment due to their compact structure, high efficiency, and low cost. However, vibration issues induced by gear meshing, flow pulsation, lubrication conditions, and housing resonance significantly degrade their operational performance, limiting the applications in high-pressure, high-speed, and large-displacement working conditions. Therefore, an in-depth investigation into the vibration generation mechanism and transmission characteristics of fuel gear pumps, along with effective vibration suppression, has become a critical challenge in this field. To promote the innovative development of vibration reduction technologies for fuel gear pumps, the recent progress on vibration dynamic mechanisms and suppression techniques is comprehensively reviewed. First, from the perspective of internal vibration excitation sources, the multi-physical dynamic modelling methods for rotor systems considering time-varying meshing stiffness of gears, fluid pressure pulsation, and lubrication of journal bearings are summarized. Second, from the viewpoint of vibration transmission paths, the current research status of experimental modal analysis with external excitation and operational modal analysis methods based on working data for fuel gear pumps is critically reviewed. Additionally, the advancements in vibration reduction technologies are systematically summarized, including housing structure optimization, gear tooth profile modification, relief groove design, and multi-stage gear pump configurations. Finally, the key challenges and future development opportunities in vibration reduction for fuel gear pumps are thoroughly discussed, providing theoretical guidance and research directions for improving fuel supply quality and service life.

In response to the demand for hypoid gears with obtuse crossed angles in helicopter transmissions, a geometric design and contact behavior control method is proposed. By establishing an obtuse crossed shaft angle hypoid gear pitch cone tangential contact model based on the three fundamental geometric relationships in space, different selection rules for gear tooth taper methods are proposed, forming a geometric design method for both inner and outer cones forms of obtuse crossed hypoid gears. Closed diagrams of boundary design parameter selections for both inner and outer cones are presented. Utilizing a local synthesis method that considers the avoidance of tooth surface defects, a comprehensive control method for the contact behavior of the obtuse crossed shaft angle hypoid gears is introduced. By employing digital tooth flank modeling techniques, an accurate meshing model of this type of gear transmission is obtained. Through tooth contact analysis and load tooth contact analysis to simulate the tooth contact behavior. Additionally, a testing machine is developed for the hypoid gear pair, allowing for adjustable shaft angles and offset distances to conduct rolling imprint tests, yielding consistent results that mutually validate each other.

Magnetically suspended permanent magnet synchronous motor(MSPMSM) has many hot parts, complex structure and the problem of heat transfer coupling between magnetic bearings and motor. In order to accurately analyze the multi-field coupling and heat transfer characteristics of the system, an air-cooled high-speed MSPMSM is taken as the research object. The electromagnetic and wind-friction loss models of magnetic bearings and motor are established, and the calculated results are mapped as heat sources into the thermal-flow field model for numerical solution, and then the obtained steady-state temperature is used as the boundary condition to compute the electromagnetic losses again. Based on this, a bidirectional magnetic-thermal-flow field coupling analysis model considering the heating of magnetic bearings is established. The flow characteristics of cooling air and the steady-state temperature distribution of the system are obtained. Besides, the effect of the temperature rise on the electromagnetic loss and the effects of different cooling air volume on steady-state temperature are explored. In order to verify the validity and accuracy of the proposed model, a prototype test platform is set up. The results show that the error of the inlet static pressure is 3.4%, and the error between the calculation and experiment of the steady-state temperature is less than 8.5 ℃. This research provides theoretical support for the cooling design and temperature rise prediction of MSPMSM.

Aiming at the problem of ambiguous mapping relationship between movable teeth transmission error and machining errors of transmission components. Taking swing roller movable teeth as the research object, and the geometric error vector representation model of the transmission components based on the equivalent mechanism of the swing roller movable teeth transmission is established. What’s more, the error transmission path is explored, and the transmission error model of multi-tooth parallel system is constructed considering the coordination relationship of multi-tooth parallel system. By means of time-frequency domain analysis, the time-frequency domain characteristics of the swing roller movable teeth transmission error under the effect of machining errors of wave generator, ring gear and separator are clear, as well as the combined effect of these errors. On this basis, the transmission error control schemes are developed. Then, a test platform for transmission error of swing roller movable teeth transmission is built to compare the error control effect of swing roller movable teeth prototype. The results show that transmission error peaks of the control schemes based on the influence degree of individual error factors and error interaction are controlled at the IT6 level of precision, which is 37.7% and 35.2% lower than IT7 level of precision, respectively. The transmission error peak value and fluctuation amplitude of the error control prototype based on the interaction influence degree of error are significantly lower than the same precision prototype based on IT7-level machining accuracy, which verifies the effectiveness of the transmission error model and error control method, and achieves an effective balance between transmission accuracy and machining cost.

To address the issue of significant impact occurring when the inertance device reverses at high speed or when the inertance coefficient is adjusted over a wide range, an electromagnetic variable inertance shock absorber for vehicle suspension is proposed. This shock absorber achieves real-time adjustment of the damping coefficient by varying the resistance of an external circuit, thereby indirectly controlling the system’s equivalent inertance. The inertial flywheel is flexibly coupled to the system through damping effects, effectively avoiding the mechanical shock associated with direct mechanical connections during adjustments. On this basis, the shock absorber is integrated into the quarter-vehicle suspension model. It was found that the damping and inertance of the suspension are coupled, and that changes in damping affect both the resonance peak value and resonance frequency of the suspension system. In order to achieve the desired control effect, a semi-active control strategy based on self-sensing estimation is proposed. This strategy can accurately estimate the motion state of the shock absorber and output positive power, thereby improving the desired control force tracking performance. Finally, the bench tests for characteristic verification and performance evaluation of variable inertance shock absorber were conducted. The experimental results show that the proposed variable inertance shock absorber can adjust the damping and inertia characteristics of suspension in real time, with its damping performance significantly outperforming that of passive suspension when using the proposed semi-active control strategy.

Since the mechanical fault diagnosis method based on federated learning lacks interpretability and is often regarded as a black box model, which reduces the trust of users to a certain extent. Based on this deficiency, a wavelet empowered federated learning (WEFL) model for mechanical fault diagnosis is prposed. In the proposed model, the wavelet coefficients are innovatively used to replace the local model parameters in traditional federated learning, and the wavelet coefficients are aggregated on the central server to reconstruct the global model. Due to the translation scale characteristics of wavelets, the constructed model greatly improves interpretability in federated learning. Simultaneously, local model parameters are replaced with wavelet coefficients, greatly reduce the computational cost of parameters and significantly accelerates the convergence. The experimenta test verify the effectiveness of the proposed model. Compared with the traditional federated learning model, the WEFL model has more transparency and interpretability in the decision-making process of mechanical fault diagnosis. Compared with the wavelet deep learning network (e.g. WaveletKernelNet), the WEFL model can effectively protect data privacy and solve the problem of data island.

Multi-object joint diagnosis often requires the establishment of multiple independent single task models, which leads to the omission of correlation information between multiple objects in the diagnostic model, resulting in inaccurate diagnostic models. Based on this, a mechanical fault diagnosis method based on multi-task twin kernel matrix machine (MTTKMM) is proposed. In MTTKMM, the synchronization processing of multi-task data is first achieved by designing kernel enhancement terms, which help to explore the correlation features between different tasks and improve the model's ability to utilize common information. Then, by utilizing the built-in nonlinear offset to capture the nonlinear relationships between data, the model becomes more flexible when dealing with complex data of multiple objects, further improving the stability of model classification. Finally, considering the significant differences in data between different tasks, a generalization loss is designed to optimize the model's fitting ability on multi-task data and reduce overfitting. To verify the effectiveness of MTTKMM in multi-task mechanical fault diagnosis, experimental verification is conducted using datasets such as rolling bearings and gears. The experimental results prove that MTTKMM has superior classification performance in multi-object diagnosis.

To enhance the load-carrying capacity of magnetic bearings and address a multivariable-coupled, time-varying system, a model predictive control strategy based on the asymmetric differential control approach is investigated. First, the operating principles of conventional differential control and the asymmetric differential control are comparatively analyzed. Subsequently, a model predictive controller is formulated based on the state-space model of the magnetic bearing-rotor system, and its parameters are optimized using the whale optimization algorithm to improve control performance. Thereafter, the developed control system is validated for correctness and effectiveness using Adams-Simulink electromechanical co-simulation. Finally, the designed controller is applied to a magnetic bearing flywheel rotor test rig to carry out static levitation, load-carrying capacity evaluation, and high-speed rotation experiments. Experimental results show that the asymmetric differential control approach increases the nominal load-carrying capacity of the magnetic bearing by 40.0% and the actual load-carrying capacity by 37.5%. The flywheel rotor operates stably at 12,000 r/min, with a peak current ripple below 1 A and a peak rotor vibration amplitude below 10 μm. The study demonstrates that the asymmetric differential control approach significantly enhances the load-carrying capacity of magnetic bearings without altering their mechanical dimensions, while the model predictive controller ensures satisfactory dynamic performance under the asymmetric differential control approach.

The fixed gantry machine tool, featuring vertical beam movement, is propelled by a dual ball screw system. A contact load analysis model for the dual ball screw drive system is developed, focusing on the issues of load distribution and fatigue life. This study elucidates the contact load distribution mechanism and analyzes the fatigue life of the system. Initially, a calculation model for the axial load of the dual ball screw drive system is proposed, taking into account the influence of guide rail tolerance and slide position. Subsequently, utilizing Euler-Bernoulli beam theory, the radial deformation of the ball screw pair under contact load is analyzed. Furthermore, a contact load distribution model for the dual ball screw drive system under operational conditions is established. The validity of the ball screw contact load distribution model is corroborated through comparison with a finite element model. Building upon these findings, the study reveals the influence mechanism of nut and slide positions on the contact load distribution and fatigue life of the ball screw pair. Additionally, the fatigue life of the dual ball screw drive system under gantry machine tool operational conditions is predicted. These results provide reliable data support and a theoretical foundation for the optimal design and long-term stable operation of the dual ball screw drive system.

The theoretical researches are carried out to predict the responses of the flywheel equipped with the dry friction damping ring and analyze the dynamic behaviors of the friction interfaces. A high-dimensional nonlinear dynamic model of the flywheel-damping ring system with multiple friction interfaces under the base random excitation is established. The number of DOF of the high-dimensional nonlinear system is reduced by using the modes of the linear system, and the vibration equations of the reduced-DOF system are solved by using the Duhamel integral, the detailed local dynamic behaviors of the friction interfaces are obtained. The dynamic responses of the flywheel under the base random excitation are predicted and compared with the experimental results, which show that the acceleration responses and acceleration response power spectral density (PSD) of the rim and bearing are basically consistent with the experimental results at the peaks, indicating that the established high-dimensional nonlinear dynamic model can accurately predict the vibration response of the flywheel. The ratio of the total time when the friction interface is in slip state to the total time of duration of the random excitation is defined as the overall slip ratio of the friction interface, which is shown to be in the range of 40%-100%. It is found that there is a corresponding relationship between the overall slip ratio and the normal load, i.e., the larger the normal load, the smaller the overall slip ratio; the smaller the normal load, the larger the overall slip ratio. The established nonlinear dynamic model can quickly and accurately predict the response of the flywheel-damping ring system, which can be used to guide the design of the flywheel damping ring.

In the milling process of critical aero-engine components such as blades and casings, the rapid tool wear caused by difficult-to-cut materials like titanium alloys and nickel-based superalloys significantly affects the geometric accuracy and surface quality of workpieces. To address the limitations of traditional end-to-end black-box models, including poor interpretability and weak cross-working condition generalization capability, a mechanism-data fusion tool wear prediction model is proposed. Firstly, a physically meaningful tool wear prediction mechanism model is established by developing a cutting force model considering tool wear and a power-based cutting force prediction model. Secondly, for the multi-dimensional information in machine tool processing, time-frequency domain processing and mutual information screening methods are employed to extract features highly correlated with tool wear and construct data feature vectors. Then, a mechanism-data fusion gated recurrent unit neural network model (MDF-GRU) is designed based on GRU model, and through the construction of a physically constrained loss function, the model optimization is achieved within the physical consistency space. Machining experiments demonstrate that the proposed model reduces the root mean square error and mean absolute error by 71.5% and 68.7% respectively compared to traditional methods, significantly improving prediction accuracy. This research provides a novel technical solution for tool wear prediction in difficult-to-cut material machining.

Artificial joint wear debris generate from the frictional motion of joint pairs, carrying mount of micro scale wear information. However, most of the artificial joint wear debris research is mainly by manual recognition, which lacks objective evaluation criteria. Classification and recognition of wear debris belongs to the image recognition field, intelligent classification such as convolutional neural network may solve the drawbacks of manual analysis. Therefore, radar graph fractal feature prior convolutional network is constructed to realize the intelligent recognition of artificial joint wear debris. Firstly, fractal dimension values of wear debris are calculated by the improved radar method, and the fractal dimension is used as the fixed characteristic of the wear debris to perform prior judgment. The judgement results are imported into the convolutional neural network models AlexNet and deep residual network (ResNet) to recognize the wear debris class. The models are trained in the wear debris picture dataset collected from literatures, and the generalization ability of the models is verified in the experimental dataset. The data augmentation method is also employed to expand the dataset and balance the uneven distribution among debris classes. Moreover, to compare the performance difference between the convolutional neural networks and ordinary machine learning models, a support vector machine (SVM) model is also used to classify the debris classes for the training data. The results showed that the radar graph fractal dimension had a good correlation with the shape distribution of the wear debris. The recognition accuracy and precision of convolutional neural network models are significantly higher than that of SVM. The fractal dimension prior judgment and data augmentation can obviously improve the recognition accuracy of the original model. The recognition accuracy of models based on AlexNet and ResNet networks reach 83.70% and 89.26%, respectively, which is higher than 80.74% and 82.59% of the AlexNet and ResNet original models of networks. The recognition accuracy models based on AlexNet and ResNet networks on the validation data are 86.60% and 88.66% respectively, which are close to the models on the training data, showing good generalization ability.

In response to the problem that the study of tribological properties of soft material surfaces lags far behind that of hard material surfaces, a friction counterpart surface consisting of the ceramic ball and the glass disk coated with a layer of polydimethylsiloxane (hereinafter referred to as PDMS) is constructed, and the correlation between the deformation of the soft surface and the tribological performance is investigated on the point-contact lubrication film measurement device based on optical interferometric technology. A high-speed camera is used to record the deformation behavior of the soft contact surface against the load, and the simultaneous measurement of contact diameter, indentation depth and surface contact contour line changes are realized. The results showed that the deformation of the PDMS surface is very fast after the load is applied, the deformation rises rapidly in 340 ms, then remains essentially unchanged and reaches a maximum value at the 300 s moment，and the deformation became smaller very fast after unloading, and basically recovered to the state before loading after 0.3 s. Under the dry contact condition, the friction force and real-time surface contact area were measured simultaneously with the change of speed and time, and it is found that the larger the real contact area was, the larger the corresponding friction force was. In the lubricated condition, the friction force was measured and the lubrication state of the soft contact surface is observed simultaneously. The results of the interferometric measurements show that it is always well lubricated and the surface deformation is reduced lubricated by calf serum, while the friction is very low and insensitive to changes in velocity. Under water lubrication, it is found that the surface is not adequately lubricated at low speeds, whereas the lubrication was improved and the friction is reduced when the speed is increased to 128 mm/s. This study would be like to provide a more comprehensive and objective knowledge of the tribological performance of soft contact surfaces, and be also of great significance for designing bionic lubrication materials with high-performance.

Under high-temperature and high-speed conditions, the air film floating ring seal experiences a significant change in clearance size. This change makes it difficult to meet low leakage requirements and seriously affects the seal’s performance and stability. Aiming to seal a bearing cavity in an engine, a design method for a“constant clearance”air film floating ring seal structure that is suitable for all working conditions is proposed. Furthermore, a high-precision method for calculating leakage, considering pressure loss with various film thicknesses under clearance eccentricity conditions, is also being explored. A numerical analysis model of fluid-solid-thermal coupling is established to discuss the comprehensive influence of the floating ring structure, mounted ring, and rotor material combination on the sealing clearance with changes in rotational speed and temperature. The model aims to analyze the leakage characteristics and utilize operational tests of the floating ring seal to verify the performance of the seal with a "constant clearance" and the accuracy of the numerical analysis model. The results indicate that the combination of the mounted ring and rotor material, along with the outer diameter and thickness of the mounted ring, are the most significant factors influencing the seal clearance under varying temperatures and speeds. The level of interference in the outer diameter of the graphite ring only impacts the initial seal clearance and the temperature at which failure occurs. After a thorough optimization of design and material selection, the constant-clearance air film floating ring seal can reduce clearance fluctuation by 90% compared to the ordinary floating ring under high-temperature and high-speed working conditions. The working clearance is the primary factor that affects the sealing performance. The leakage rate of a constant clearance air film floating ring seal is approximately proportional to the differential pressure and outlet pressure, and inversely proportional to the temperature. The rotational speed affects the eccentricity, which, in turn, causes fluctuations in the leakage rate. The conclusions of the study provide a dependable theoretical foundation for achieving high stability, long lifespan, and low leakage operation of air film floating ring seals under high-temperature and high-speed working conditions.

With the advancement of artificial intelligence technology and the increasing demand for emotional satisfaction, the unpredictability of the product's emotional intelligence design domain has become more evident, and its complexity has increased. This has led to a series of issues, including the misalignment between user emotional needs and product characteristics, the failure of final products, and the abandonment of products. In recent years, there has been a significant increase in research on the unpredictability of product emotional intelligence design. In the field of product emotional design, the presence of uncertainty has become increasingly evident, and the complexity of its interaction with human emotions has increased. This has led to a series of issues, including the misalignment between user emotions and the characteristics of products, the failure of final solutions, and the abandonment of products. In recent years, a significant number of studies have been conducted on the uncertainty in product emotional design. These studies have provided a comprehensive and systematic overview of the current research in this field. The study firstly introduces the research framework and content of product emotional design. It then systematically examines the uncertainty in the research framework, as well as the extraction of user emotions using intelligent methods, the relationship between user emotions and product characteristics, the generation of solutions using intelligent methods, and the evaluation of products using intelligent methods. The study firstly introduces the research framework and content of the product's emotional intelligent design, which is currently under investigation. It then systematically analyses the uncertainty issues in the research framework. The study then examines the intelligent extraction of user emotions, the establishment of user emotions and product features, and the intelligent generation, assessment and evaluation of product solutions. Finally, it synthesises the study's content and key technologies. The study then synthesises the current technological developments and research gaps to predict future trends. The aim is to achieve a comprehensive analysis of the uncertainty issues in the product's emotional intelligent design, which will inform future theoretical and practical research.

Suppression of low-frequency noise has always been a key focus and challenge in the field of noise control. Due to the limited effectiveness of traditional sound-absorbing materials in absorbing low-frequency noise, metastructure have emerged as a hot research topic. Among them, biomimetic structures, as an important branch, show great potential in the field of low-frequency noise absorption. In this study, a acoustic absorption metamaterial inspired by a conch is designed, where two spiral sound channels are coupled in a single unit cell, proposing a Conch-like bidirectional acoustic absorption metamaterial (CBAAM). CBAAM sampleswere produced by additive manufacturing (AM) technology, and their bidirectional acoustic absorption performance is validated through finite element simulations and acoustic impedance tube tests, showing a absorption performance of (168 Hz, 438 Hz) at face 1 and (166 Hz, 462 Hz) at face 2. The study revealed that the acoustic absorption performance mainly contributed from resonant effect, and some key geometric parameters had significant impact on the acoustic performance of CBAAM. Additionally, the study explored the composite of CBAAM with other different materials to analyze the influence of various material compositions on its compressive mechanical properties. The lightweight and bidirectional sound absorption performance of CBAAM may have broad application prospects in the field of acoustic control.

To control the dynamic characteristics of a rotor-bearing system and improve its stability, an actively controlled hybrid film bearings is designed based on a PD controller. By combining the hybrid bearing with electro-hydraulic servo valves, the bearing gains a specific active compensation ability to cope with changes in the dynamic response of the rotor-bearing system. The experimental setup for an actively controlled hybrid film bearing-rotor system is designed and constructed to validate the vibration control performance of the bearing. Various control parameters are adjusted to investigate the rotor's dynamic characteristics and vibration reduction capabilities. The results demonstrate that with an appropriately chosen differential coefficient, activating active control achieves significant vibration reduction, with the maximum horizontal vibration amplitude of the bearing decreasing from 41.4 μm to 19.6 μm, a reduction of 52.7%. The critical speed of the rotor system can be controlled by adjusting the bearing stiffness with only proportional component activated, reducing the critical speed from 2 508 r/min to 1 980 r/min, a decrease of 21.1%, thereby achieving control over the critical speed of the rotor system.

In order to improve the fatigue life of ultra-high strength steel under extreme load conditions, the composite strengthening method of deep rolling and two-angle pre-torsion was proposed. The formation of surface integrity and the strengthening mechanism of the microstructure of ultra-high strength steel under the coupling action are revealed by confocal microscopy, electron back scatter diffraction (EBSD), and transmission electron microscope (TEM). It is found that under the composite strengthening, the depth of the reinforced layer of residual compressive stress was improved, and the depth of the deep rolling and 13.7°/7.71° pre-torsion strengthening layer reached 1.2 mm, and an obvious "second reinforced layer" appeared, and the maximum circumferential residual compressive stress is -535 MPa, which appeared at 0.3mm from the surface. The grain refinement and dislocation multiplication in the surface layer are promoted. Compared with the single-angle pre-torsion, the combination of large and small angles pre-torsion after deep rolling reduced the grain size and increased the density of geometrically necessary dislocation. The surface layer microstructure is distributed in a gradient along the depth direction. The effectiveness of the two-angle pre-torsion after deep rolling method is proved, which is of great significance to the development of surface strengthening technology for hard-to-machine ultra-high strength steel parts.

The thermal error of machine tool during processing is an important factor of manufacturing error. Based on the existing concept of material thermal inertia, the concept of structural thermal inertia is proposed, its expression is established, its physical significance is clarified, and the technical approach of structural thermal inertia matching is discussed. Taking a five-axis direct drive vertical machining center as the research object, the thermodynamic coupling model of the whole machine is established. Based on the principle of structural thermal inertia matching and variable density method, a mathematical model of topological optimization design is established to improve the structural stiffness and reduce the temperature standard deviation. The results show that compared with the original beam structure, the mass of the optimized beam structure is reduced by 16.7%, the displacement of the tool tip is reduced by 14.8%, and the first-order frequency is increased by 8.3%. The proposed design method provides a new design idea for the design of various temperature-sensitive complex structural systems.

Traditional minimally invasive medical surgical forceps lack tactile feedback during tool-tissue interaction and cannot accurately position tissue. To enhance the perception of clamping force and tissue characteristics in minimally invasive surgery, as well as to improve the precision and stability of surgical operations, this study presents a novel design for minimally invasive surgical forceps featuring displacement-force bimodal feedback. In contrast to conventional instruments, the proposed forceps enable accurate measurement of both the clamping force and the jaw opening angle during operation. The system integrates two fiber Bragg grating (FBG) sensors: FBG1 attaches along the centerline on the back of the plier head under pre-tension to capture force-tactile data, while FBG2 mounts on the M-shaped elastic beam located at the bottom of the plier body to monitor angular displacement. The design undergoes structural optimization through hydrostatic analysis to enhance FBG sensitivity. A dedicated experimental platform supports static calibration, tissue block volume identification, and hardness recognition tests. Results demonstrate the device’s ability to distinguish tissue blocks with varying volumes and stiffness within biological samples. In terms of performance, FBG1 achieves an average sensitivity of 32.03 pm/N with a linearity of 0.998 across the 1-10 N load range. FBG2 delivers an average sensitivity of 5.66 pm/(°) and maintains the same linearity over the 0-60° jaw angle range.

Based on a comprehensive understanding of the mechanisms involved in laser direct processing of polystyrene (PS) microgrooves, the formation principles of PS microgrooves under photosensitive coating-assisted processing are further explored. The quantitative relationship model is established to correlate processing parameters with microgroove quality for both processing methods through mathematical modeling and fitting analysis. The results indicate that near-infrared picosecond laser processing of PS microgrooves primarily occurs via the photothermal effect, wherein the laser energy induces thermal degradation of PS. Laser direct processing is likely to result in uneven energy distribution, which can lead to defects such as energy-sparse areas, pits, filamentous or dot-shaped splashes, and protrusions along the edges of microgrooves. The width of the prepared microgrooves ranges from 128 μmm to 295 μmm. In contrast, the absorption rate of laser energy can be significantly enhanced with photosensitive coating on PS surface. This improvement allows for the processing of microgrooves with minimal defects at very low single pulse energy (3 μmJ), and it eliminates noticeable spray around the microgrooves. The photosensitive coating-assisted processing method is more suitable for creating microgrooves with narrower widths and shallower depths, with microgroove width is around 47 μmm. The established relationship model can effectively predict both the microgroove width and the quality of the microgroove using two methods.

3D printed water-soluble sacrificial molds are widely used in the fabrication of fine surface features and complex internal structures such as biological scaffolds and microfluidic channels due to their easy removal, low cost, ability to mold complex structures, and ability to protect fine features. However, existing 3D printing techniques such as direct ink writing or fused deposition molding have challenges in the fabrication of water-soluble sacrificial molds, such as low precision (>100 μm) and poor controllability of morphology. In this study, an electric field-driven thermal fusion micro-3D printing method for the fabrication of high-precision water-soluble sacrificial molds is proposed. First, the effects of the molecular weight of plasticizer PEO and the mixing ratio of PEG/PEO on the printability are investigated; then, the effects of the printing parameters on the linewidth and morphology are investigated and optimized, and a minimum linewidth of 30 μm with a pitch of 30 μm is achieved for wire grid printing. Finally, a PCL/Ecoflex dual-surface microstructured triboelectric nanogenerator (TENG) is designed and fabricated based on a high-resolution water-soluble sacrificial mold, which has an open-circuit voltage of 86 V for a 30 μm microgroove structure, which is 1.32 times higher compared with that of the 90 μm microgroove structure, and a peak power density of 156.8 mW/m² with excellent output performance. Therefore, the present method provides a new idea to realize the processing of high-resolution water-soluble sacrificial molds and microstructures.

Carbon fiber reinforced thermoplastic composites (CFRTP) are increasingly used in large aerospace components due to their advantages of light weight, high strength, easy fabrication and repairability. The assembly quality of large components of aerospace CFRTP directly affects the safety and performance of equipment, and it is often necessary to grind and modify the near-net formed CFRTP parts to meet the accuracy requirements of connection assembly. In the grinding process, the prediction accuracy of the material removal mathematical model directly affects the contour accuracy of the part. However, due to the anisotropy of CFRTP, the traditional mathematical model cannot guarantee the prediction accuracy when grinding in different directions. Therefore, the anisotropy of CFRTP removal thickness is characterized by the directivity coefficient combined with Preston equation, and the material removal depth and material removal rate mathematical model of CFRTP parts are established taking into account the fiber direction angle. Then, the robotic grinding system of CFRTP parts is used to carry out grinding tests, and the unknown coefficients in the model are fitted, the experiment verifies that the average relative error of the model is less than 12%, and the model has high prediction accuracy. Finally, the influence of grinding parameters on material removal was analyzed, and the influence of fiber orientation angle on material removal revealed by the removal model was explained and verified by combining the surface morphology and material removal mechanism.

Titanium alloy is a crucial metallic material indispensable for the main structure of aircraft and engine components. In the mechanical manufacturing process of titanium alloy parts, cutting is a typical processing method. However, insufficient effective infiltration of lubricant at the interface between the tool and the workpiece during continuous turning and excessive cutting force lead to severe tool wear, which are the main bottlenecks in its machining. The turning process of ultrasonic-energized bionic texture tools with minimum quantity lubrication is expected to solve the problem of tool wear during titanium alloy cutting. Nevertheless, the material removal mechanism and mechanical behavior of the new process are still unclear. Based on this, a mechanical model for material removal in the turning process of UVT-NMQL is established. The material removal characteristics of ultrasonic parameters such as instantaneous cutting thickness, instantaneous cutting speed, instantaneous shear angle, and instantaneous tool-chip contact state are clarified. A technical route for cutting force prediction under multiple working conditions is constructed, and the influence laws of input parameters and cutting speed on the cutting force are analysed. Under four experimental conditions of dry cutting, NMQL, T-NMQL, and UVT-NMQL, the cutting forces per unit area of material removal for the titanium alloy Ti-6Al-4V material are 2 504.18 N/mm², 2 255.85 N/mm², 2 074.71 N/mm², and 803.67 N/mm², respectively. Under the UVT-NMQL condition, the prediction model and the experimental results show that a consistent trend of change. When the cutting speed increased, the cutting force increased, and the average deviation of the model is 7.46%. The prediction model of turning force for UVT-NMQL established based on the material removal mechanism can provide theoretical guidance and technical support for both the industrial and academic fields.

The processing channels of integral components such as blisk, integral impeller, and closed impeller of aero-engine are twisted, narrow, and deep, and are prone to various machining interference, which are typical difficult-to-machine components. To improve their machined surface quality, the robotic belt grinding process that is widely used as the last finishing process of the integral component is taken as the research object, and a multi-objective planning method of interference-free machining postures for robotic belt grinding of integral components is presented. With this method, a definition of interference-free robot configuration space (IFRC-Space) is first proposed. Next, an exploration experiment on the evolution law of IFRC-Space along the toolpath when grinding integral components is carried out, which concluded that IFRC-Space varies continuously along the toolpath. Based on the conclusion, a rapid computation method of IFRC-Space is proposed by using the edge detection operator of images. Then, a multi-objective optimization algorithm of grinding postures is advanced based on IFRC-Space. With the algorithm, the indicators including interference avoidance, singularity avoidance, smoothness of grinding postures, and the kinematic performance of the robot can be comprehensively considered, which enables the automatic generation and multi-objective optimization of the interference-free machining postures for robotic belt grinding of integral components. The effectiveness and practicability of the proposed method are verified by toolpath planning experiments for robotic belt grinding of aero-engine blisk and closed impeller.

As the service temperature of turbine blades and other hot-end components in aero-engines is increasing, nickel-based alloys, which represent high-temperature resistant materials, are gradually being used for their manufacturing. At the same time, in order to further improve the service performance of these components, it is necessary to process film cooling holes on their surfaces. Due to its precision, low damage, and cold processing characteristics, femtosecond ultrafast laser is increasingly suitable for the processing of nickel-based micro-group holes. However, due to the large number of gas film holes, dense distribution, and high positioning accuracy, the inclined workpiece drilling process is difficult to meet the processing requirements of non-taper micro-group holes. In addition, the inclined laser drilling process has high requirements for the calculation and motion control precision of the optical path mathematical model. Therefore, in order to achieve the processing of non-taper micro-group holes in nickel-based alloy, a method of achieving non-taper group holes processing through multi-axis linkage of the machine tool is proposed. Firstly, the influence of machine tool motion parameters are explored, such as the feed speed and feed radius of the machine tool on the micro-group holes morphology. Then, the experimental study on the effective processing range of femtosecond laser processing of micro-group holes is carried out. Finally, based on the parameter exploration of the non-taper single hole experiment, the group hole processing experiment is carried out on a flat sample, and the experimental results are discussed and analyzed to form a complete flat group hole processing process. Ultimately, the 5×5 micro-group holes with an average taper of -0.03 ° was obtained on a nickel-based alloy with a thickness of 1 mm.

Aluminum alloy thin-walled parts have important applications in the aerospace field due to their light weight and high overall rigidity. Due to the thin thickness of the side wall and web of thin-walled parts, the milling force during machining is a key factor inducing machining errors. In order to further reveal the milling mechanism of thin-walled parts and optimize the cutting process, it is particularly important to accurately predict the cutting force. Aiming at the weak stiffness characteristics of thin-walled parts, a flexible milling force prediction model considering the force-deformation effect is proposed, and the coupling law between milling force and deflection deformation is revealed. According to the Kirchhoff theory and the change of cutter-workpiece contact area caused by workpiece deformation in the milling process, a model of flexible milling force prediction and a finite element calculation method of deflection bending deformation of thin-walled parts are established, which characterize the time-varying contact relationship between the force and the workpiece contact area. The dynamic deformation values generated during the cutting process are used to iteratively correct the instantaneous cutting thickness and improve the prediction accuracy of the milling force model. Comparing the prediction results with the experimental results, the maximum error of the predicted deformation value of the proposed method is within 0.012 mm, and the average error of the milling force prediction in the X and Y directions is less than 10 %, which verifies the accuracy and effectiveness of the model. The established cutting force model can provide a theoretical basis for the reasonable optimization of tool structure and the recommendation of process parameters.

The modulated target with sinusoidal micro-surface is an important impact carrier for inertial confinement fusion and other nuclear physics experiments. Its roughness fluctuation on the micro-surface seriously affect the nuclear physics and chemical reactions. For machining sinusoidal modulated target, the conventional slow tool servo (STS) cutting technology is difficult to control the roughness fluctuation owing to the sudden change of cutting state. Based on the requirement of surface consistency, the elliptical vibration slow tool servo (EVSTS) cutting method is presented for fabricating sinusoidal micro-surface. Based on the time-varying of the cutting process of EVSTS, the roughness distribution characteristics and its generation mechanism of the roughness fluctuation on the sinusoidal micro-surface are clarified, and the optimal matching strategy between the elliptical vibration trajectory and the target sinusoidal micro-surface is proposed to suppress the roughness fluctuation. The experimental results show, compared with the conventional STS cutting, the roughness on sinusoidal micro-surface machined by EVSTS decreases by 30%-60%, and its roughness fluctuation is reduced by more than 30% in a certain range of cutting parameters.

The through-feed superfinishing is the key process of tapered rollers in low friction rolling bearings. The spherical base surface scratches caused by the contact between the spherical base surface and the spiral push flange of the superfinishing guide roller often occur in production. A kind of numerical calculation method of the contact position of the base surface and the flange is proposed, and the influencing factors on the edge contact between the base surface and flange are analyzed. The analysis results show that the inclination angle of the spiral push flange, the radius reduction of the guide roller shape surface and the oblique angle of the tapered roller have significant effects on the contact position, while the contact angle between the roller and the guide rollers has little effect on the contact position. When the inclination angle of the spiral push flange is small, the outer edge of the flange is prone to contact; When the angle increases, the contact position moves rapidly to the inner edge of the flange, and the inner edge of the flange is prone to contact. The more the radius of guide roller shape surface decreases with the increase of the frequency of guide roller regrinding, the more likely it is to have the inner edge contact. The larger the oblique angle of the tapered roller, the more prone it is to have the inner edge contact. The contact position verification test is carried out, and the test results are in agreenment with the calculated results. The research results can provide theoretical and technical support for optimizing the through-feed superfinishing process of tapered rollers and avoiding scratches on the roller’s spherical base surface caused by the edge contact of the spiral push flange of the superfinishing guide roller.