Purpose The combination of improved PSO (IPSO) algorithm and artificial neural network (ANN) model for intelligent monitoring of the bearing performance of the hydrostatic turntable. Design/methodology/approach This paper proposes an artificial neural network model based on IPSO algorithm for intelligent monitoring of hydrostatic turntables. Findings The theoretical model proposed in this paper improves the accuracy of the working performance of the static pressure turntable and provides a new direction for intelligent monitoring of the static pressure turntable. Therefore, the theoretical research in this paper is novel. Originality/value Theoretical novelties: an ANN model based on the IPSO algorithm is designed to monitor the load-bearing performance of a static pressure turntable intelligently; this study show that the convergence accuracy and convergence speed of the IPSO-NN model have been improved by 52.55% and 10%, respectively, compared to traditional training models; and the proposed model could be used to solve the multidimensional nonlinear problem in the intelligent monitoring of hydrostatic turntables. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0081/

Abstract This study presents a simulation model for the wave generator and flexspline assembly, examining the relationship between radial and main section deformations. Adjusting the wall thickness enables interference-free meshing of various sections. A response surface model for the effect of circular spline profile parameters on flexspline stress has been established. To assess how various parameters of the involute gear profile affect the meshing stress of flexspline. Thus providing a theoretical basis for optimizing gear profile modifications.

The internal feedback hydrostatic rotary table is a precision support device, and its performance relies heavily on the oil pad. However, uncertainties in the manufacturing process are often overlooked during the stiffness optimization, affecting the reliability of the optimized results. Accordingly, this paper aims to analyze the influence of structural parameters on the stiffness performance of the internal feedback hydrostatic rotary table and to perform reliability optimization considering the uncertainties. Initially, a theoretical computational model of internal feedback hydrostatic rotary table, accounting for the oil leakage effect, is proposed. The model's accuracy is validated through comparative simulation calculations, and based on this model, the load-bearing performance of the table is further analyzed. Subsequently, focusing on the structural characteristics of the oil pad, a reliability optimization model that considers manufacturing uncertainties is proposed. To improve the optimization efficiency, a Levenberg-Marquardt Backpropagation (LM-BP) neural network is introduced as a surrogate model for theoretical calculations. The oil pad is optimized through a particle swarm optimization algorithm. Ultimately, the optimal structural size parameters of the oil pad are obtained, achieving maximal stiffness under a high level of reliability. Both the stiffness performance and the reliability level of the rotary table are substantially enhanced. The results indicate that the proposed method can significantly improve performance and reliability in practical applications.

Contact stiffness and backlash in the harmonic drive significantly impact a robot's positioning accuracy and vibration characteristics. The height of the harmonic drive tooth pair is typically less than 1 mm, making the measurement and modeling of backlash and contact stiffness inherently complex. This paper proposes a contact stiffness and backlash model by establishing a correlation between fractal parameters and tooth contact load. To obtain the fractal roughness parameters of the real machined tooth surface, a combination of a noncontact optical profiler and the RMS method is employed. Subsequently, the study explores the influence of rough tooth surface and contact force fractal parameters on contact stiffness and gear backlash. The results demonstrate the substantial impact of surface topography parameters and contact force on contact stiffness and backlash. Specifically, an increase in the fractal dimension correlates with a reduction in gear backlash and contact stiffness. Conversely, the fractal roughness parameter exhibits the opposite effect. Notably, an increase in contact force enhances contact stiffness.

This paper proposes a parameter optimization method for hydrostatic turntable with internal feedback in machine tools, considering stiffness and energy consumption. For the first time, a power consumption calculation method for oil pads with built-in restrictor is presented, and a stiffness calculation model for the oil film is established based on the Reynolds equation. A multi-objective optimization function is constructed in the form of weighted coefficients. An experimental setup for performance testing of the oil pad with internal feedback is developed, and finite element simulation analysis is combined to verify the accuracy of the theoretical method. Finally, corresponding optimization schemes for different scenarios are provided. The results show that at a speed of 50 r/min, power consumption can be reduced by 50.1

This paper provides a comprehensive exploration of the operational mechanism of an internal feedback hydrostatic turntable. It employs a self-compensating gap restrictor mechanism, resulting in heightened load capacity and stiffness. In this paper, the concept of internal flow is innovatively introduced. Subsequently, the Reynolds equation is solved using the finite difference method. This methodology offers a more precise and efficient assessment of the load-bearing performance of the oil pad within the turntable. Then this paper further investigates the influence of the internal flow coefficient and pressure ratio on oil pad performance, encompassing aspects like load capacity, stiffness, and flow rate. Ultimately, optimal parameters are selected to improve the structure of the gap restrictor, considering various operational scenarios. In conclusion, the method adopted in this study not only improves the calculation accuracy and efficiency but also improves the structure and performance of the oil pad. The hydrostatic turntable is a critical component of numerous computerized numerical control machine tools. This paper provides a more comprehensive exploration of the operational mechanism of an internal feedback hydrostatic turntable. In addition, this study proposes a more accurate and efficient method to analyze the performance of the oil pad and optimize its structure.image

This study aims to analyze the impact of uniform and eccentric load conditions on the performance of internal feedback hydrostatic thrust and journal bearing. Two distinct models are established: a three-degrees-of-freedom uniform load model and a five-degrees-of-freedom eccentric load model. The support stiffness, overturning stiffness, and flow rate for both thrust and journal bearings are calculated. Additionally, numerical analysis is conducted to examine the influence of oil film thickness, inlet pressure, and restrictor size on the operational characteristics of the bearings, revealing the interplay between an eccentric load and journal bearing speed. The validity of the theoretical algorithm is verified through finite element simulation. The research outcomes hold significant guiding implications for the design and application of internal feedback hydrostatic bearings.

The internal feedback hydrostatic bearing features a distinctive structural design, playing a pivotal role in high-precision machine tools. Its performance significantly influences the improvement of machining accuracy and stiffness. In this study, the working principle of the internal feedback closed hydrostatic bearing is described, the equivalent liquid resistance model of oil circuit considering internal flow effect is established, an analysis method for evaluating the support performance of the internal feedback hydrostatic bearing is proposed, flow rate correction methods are proposed, and the influence of load-carrying capacity and flow rate due to inlet pressure, oil film thickness, and the size of the restrictor is discussed. The accuracy of the method is verified by simulation, and insights for the future development of hydrostatic bearings are provided.

Meshing backlash mainly determines the transmission accuracy of harmonic drive, which is an important index in design. In this paper, a design method for short tooth involute profile is proposed. By intercepting part of the tooth profile, meshing interference of the addendum can be effectively avoided. Based on the dimensions of over pins of circular spline and flexspline, a calculation method of tooth thickness deviation is proposed, and the positive and negative tooth thickness deviation are defined. Involute functions need not be calculated by this method, which simplifies the solution process. By discretizing the teeth profile points of circular spline and flexspline, a calculation method of time-varying backlash is proposed, the variation of backlash in meshing in and out is analyzed, and the influence law of tooth thickness deviation on backlash is studied. On this basis, an algorithm for adjusting the radial deformation to compensate for the backlash is proposed. The results show that the excessive backlash in the meshing area can be reduced by increasing the radial deformation. When meshing interference occurs, the interference-free meshing can be realized by decreasing the radial deformation.

Harmonic drive (HD) is one of the core components of the robot joint. Studies show that tooth shape design and meshing characteristics of the HD directly affect the motion control accuracy and vibration characteristics of the robot. In the present study, common coordinate systems are established for three tooth profiles to analyze the differences between them. To this end, expressions for the double circular arc common-tangent tooth profile (DCTP), cycloid common tangent tooth profile (CCTP), and the involute tooth profile (ITP) are established in the same coordinate system. By applying the envelope conjugate theory, the conjugate existent domain (CED) and conjugate tooth profile (CTP) of the HD transmission are solved independently for each profile. Furthermore, the influences of tooth profile parameters on both the CTP and CED are analyzed. Obtained results show that both the DCTP and CCTP have more robust envelope processes when compared with the ITP. Moreover, it is found that both profiles can achieve the second conjugate and two-point conjugate engagement through applying variations in the tooth shape design parameters. It is concluded that meshing performances of the DCTP and CCTP are better than that of the ITP, providing guidelines for the future development of the harmonic reducer tooth shape design.