The variable hyperbolic circular arc tooth trace (VH-CATT) cylindrical gear is a new gear suitable for heavy loads and high speed. The special structure of the gear provides excellent mechanical properties but also increases the processing difficulty. The special machine tool for VH-CATT gear provides a prerequisite for mass production, but the machining accuracy remains to be improved. Therefore, this paper proposes a Kriging model based on the glowworm swarm optimization algorithm of scene understanding (SGSO) to study the relationship between input parameters and output precision. Then, the SGSO algorithm is used to optimize the parameters of the Gaussian mutation function in the Kriging model to improve its fitting accuracy. When solving four groups of tooth profile and tooth direction errors, the key precision index, R², of SGSO-Kriging all exceed 0.95. Additionally, the feasibility of the model is verified by the residual diagram and the box diagram. The contour diagram and error results show that reducing the feeding velocity, v_f, can improve accuracy most efficiently, and the increase of rotational speed, n, is more conducive to the accuracy of the tooth surface than the acceleration of the coolant, v_Q. The above research provides an optimization strategy of gear machining accuracy and a theoretical basis for the promotion of the VH-CATT gear.

The kinematics of a robotic manipulator is critical to the real-time performance and robustness of the robot control system. This paper proposes a surrogate model of inverse kinematics for the serial six-degree of freedom (6-DOF) robotic manipulator, based on its kinematics symmetry. Herein, the inverse kinematics model is derived via the training of the Vector-Quantified Temporal Associative Memory (VQTAM) network, which originates from Self-Organized Mapping (SOM). During the processes of training, testing, and estimating of this neural network, a priority K-means tree search algorithm is utilized, thus improving the training efficacy. Furthermore, Local Linear Regression (LLR), Local Weighted Linear Regression (LWR), and Local Linear Embedding (LLE) algorithms are, respectively, combined with VQTAM to obtain three improvement algorithms, all of which aim to further optimize the prediction accuracy of the networks for subsequent comparison and selection. To speed up the solving of the least squared equation, which is common among the three algorithms, Singular Value Decomposition (SVD) is introduced. Finally, data from forward kinematics, in the form of the exponential product of a motion screw, are obtained, and are used for the construction and validation of the VQTAM neural network. Our results show that the prediction effect of the LLE algorithm is better than others, and that the LLE algorithm is a potential surrogate model to estimate the output of inverse kinematics.

An explicit analytical workflow for cylindrical hole stability analyses in general laminated materials that possess transversely isotropic (TI) anisotropy is presented. In this approach, the calculation of the distribution of the stresses around a cylindrical hole and the failure evaluation at the hole wall consider the effects of both material elasticity anisotropy and strength anisotropy caused by material laminated structures. Material strength anisotropy is assumed to be caused by the sliding of preexisting weakness planes oriented parallel to the isotropic plane of the material. The effect of anisotropy on strength is modeled by combining a shear failure criterion for the intact matrix and a weak plane failure criterion for the planes of weakness. We derive critical pressure solutions for the stability of the intact matrix around a hole filled with gas or fluid based on the Mohr–Coulomb failure criterion and Drucker–Prager failure criterion; either one of them can be combined with the weak plane failure criterion to give the solution for hole wall shear failure pressure. The solution for hole wall fracture initiation pressure is derived based on the tensile failure criterion. This approach can be applied to holes of arbitrary orientation in general laminated materials.