Yali Yi

Aiming at the issue of coupled displacement in the parallel compliant mechanism of the two-degree-of-freedom (2-DOF) piezoelectric micro-positioning platform, this paper performs a rigid-body equivalence of the 2-PP type compliant mechanism and conducts kinematic analysis to reveal the mechanism of coupling generation. A ‘suitable constraint branch chain’ is introduced to eliminate the coupling between orthogonal chains, and a quasi-symmetric micro-positioning platform configuration with decoupling function is proposed. Based on the rigid-body replacement method, the compliant mechanism is designed to ensure that the output component undergoes pure translation without rotation, thereby achieving decoupling. A stiffness model of the compliant micro-positioning platform is established to clarify the dimensional design principles of the mechanism. A static model is developed using Castigliano’s theorem and the pseudo-rigid-body model to identify the factors influencing. Finite element simulation and experimental verification are conducted. The results show that the deformation difference between the constrained branched chains of the designed positioning platform is 4.3%, the deviation between the theoretical and simulated amplification ratios is 2.69%, the workspace is 63.5 μm × 54.0 μm, and the coupling rates are 0.47% and 0.74%, respectively, verifying the correctness of the decoupling method and the theoretical model. This research provides guidance for the decoupling design of 2-DOF positioning platforms.

Seventy-kilohertz ultrasonic transducers are essential in advanced manufacturing, especially in precision welding and micromachining. Key performance metrics, including resonant frequency, nodal deviation, and amplitude ratio, are strongly coupled through the structural parameters, which makes coordinated design difficult using conventional approaches. To address this issue, this paper presents a neural-network-based inverse design method. First, a theoretical performance–structure relationship is established using the Mason equivalent model. Subsequently, high-fidelity finite element analysis (FEA) is used to generate the training dataset, with resonant frequency further checked by comparison with three sets of impedance-based experiments. A seven-factor orthogonal design is then used to identify the structural parameters that most strongly influence the target performance. Finally, a Particle Swarm Optimization–Backpropagation (PSO-BP) inverse model is developed to predict key structural parameters directly from target performance inputs. FEA verification shows that the predicted design satisfies the preset specifications for resonant frequency, nodal deviation, and amplitude ratio, while direct experimental validation in the present study is provided only for resonant frequency. This study provides an efficient inverse-design framework for coordinated performance-oriented design of 70 kHz ultrasonic transducers.

To compensate for hysteresis, low damping vibration, and their coupling effects, this paper proposes a gated recurrent unit and convolutional neural network (GRU-CNN) model as a feedforward control model that maps desired displacement trajectories to driving voltages. The GRU-CNN integrates a gated recurrent unit (GRU) layer to capture long-term temporal dependencies, a multi-layer convolutional neural network (CNN) to extract local data features, and residual connections to mitigate information distortion. The GRU-CNN is then combined with transfer learning (TL) for feedforward control of cross-batch and cross-type piezoelectric actuators (PEAs), so as to reduce reliance on training datasets. The analysis focuses on the impacts of target PEA data volume and source-target similarity on transfer learning strategies. The GRU-CNN trained on PEA #1 achieves high control accuracy, with a mean absolute error (MAE) of 0.077, a root mean square error (RMSE) of 0.129, and a coefficient of determination (R²) of 0.997. When transferred to cross-batch PEA #2 and cross-type PEA #3, the GRU-CNN feedforward controller still delivers favorable performance; R² values all exceed 0.98, representing at least a 27% improvement compared to training from scratch. These results indicate that the proposed transfer learning-based feedforward control method can effectively reduce retraining effort, suggesting its potential applicability to batch production scenarios.

This study aimed to investigate the effect of different coating processes on interlayer coating using ProCAST software and identify the preferred coating process so as to prepare an EH40/2205 composite plate with a coating interlayer of Ni-5 Fe-15 Co (wt.%) displaying good performance. The preparation and characterization tests were conducted to analyze the interlayer coating, the diffusion of elements at the bonding interface and the mechanical properties of the hot-rolled composite plate. The results showed that the coating rate increased linearly with an increase in the initial coating temperature, pressure difference and the width ratio of the suction layer. The interlayer coating was complete under the guidance of optimized process parameters, and the test results and simulations confirmed each other. The coated interlayer successfully blocked the diffusion of elements between the bonding surfaces. The tensile strength of the rolled composite plate was 580 MPa, which met the needs of the project. The tensile shear fracture occurred at EH40, which proved that the plate was well bonded.

In order to improve the load state of the two-tooth difference swing-rod movable teeth transmission system, in this paper, a dynamic equivalent calculation model of the transmission system is established based on lumped parameter theory, and then a calculation method of system dynamic load is derived. The influence of external excitation on load inhomogeneity of the transmission system is analyzed from a dynamic point of view. The theoretical results are verified by Adams dynamic load simulation analysis and strain test based on a test bench. The results show that when errors of the transmission system are fixed, the system load inhomogeneity is improved effectively with the increase of load torque, while the system load inhomogeneity becomes worse as input speed increases. This study provides a theoretical reference for improving the load inhomogeneity of the two-tooth difference swing-rod movable teeth transmission system.

Using the two-tooth difference swing-rod movable teeth transmission system satisfying the drive function of large optical instruments as the study object, the influence of each component error on system transmission error is analysed. Each component error is presented by the vector method, and then it is transformed into equivalent error in the direction of the meshing action line based on the equivalent meshing error principle. The instantaneous transmission ratio of the system is obtained by the instantaneous velocity center method, and the system transmission error model is established. Using numerical analysis, the influence of each component error on the system transmission error is obtained. The transmission error test platform is used to test and analyze the transmission error of the two-tooth difference swing-rod movable teeth transmission system. The research results show that the swing-rod length error and the wave generator eccentric error have a great influence on the transmission error of the system among the six types of error factors, so they should be strictly controlled during design, processing and assembly. This study provides a theoretical basis for the rational allocation of machining errors and assembling errors of the two-tooth difference swing-rod movable teeth transmission system.