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Contact detection with multi-information fusion for quadruped robot locomotion under unstructured terrain

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0760-4

摘要： Reliable foot-to-ground contact state detection is crucial for the locomotion control of quadruped robots in unstructured environments. To improve the reliability and accuracy of contact detection for quadruped robots, a detection approach based on the probabilistic contact model with multi-information fusion is presented to detect the actual contact states of robotic feet with the ground. Moreover, a relevant control strategy to address unexpected early and delayed contacts is planned. The approach combines the internal state information of the robot with the measurements from external sensors mounted on the legs and feet of the prototype. The overall contact states are obtained by the classification of the model-based predicted probabilities. The control strategy for unexpected foot-to-ground contacts can correct the control actions of each leg of the robot to traverse cluttered environments by changing the contact state. The probabilistic model parameters are determined by testing on the single-leg experimental platform. The experiments are conducted on the experimental prototype, and results validate the contact detection and control strategy for unexpected contacts in unstructured terrains during walking and trotting. Compared with the body orientation under the time-based control method regardless of terrain, the root mean square errors of roll, pitch, and yaw respectively decreased by 60.07%, 54.73%, and 64.50% during walking and 73.40%, 61.49%, and 61.48% during trotting.

关键词： multi-information fusion contact detection quadruped robot probabilistic contact model unstructured terrain

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Transmission probability method based on triangle meshes for solving the unstructured geometry neutron

WU Hongchun, LIU Pingping, ZHOU Yongqiang, CAO Liangzhi

《能源前沿（英文）》 2007年第1卷第2期页码 158-166 doi: 10.1007/s11708-007-0020-z

摘要： The fuel assembly or core with unstructured geometry is frequently used in the advanced reactor. To calculate the fuel assembly, the transmission probability method (TPM) is widely used. However, the rectangular or hexagonal meshes are mainly used in the TPM codes for the normal core structure. The triangle meshes are most useful for expressing the complicated unstructured geometry. Even though the finite element method and Monte-Carlo method are well suited for solving the unstructured geometry problem, they are very time-consuming. Therefore, a TPM code based on the triangle meshes is developed here. This code was applied to the hybrid fuel geometry, and compared with the results of the MCNP code and other codes. The results of the comparison were consistent with each other. The TPM with triangle meshes can thus be applied to the two-dimensional arbitrary fuel assembly.

关键词： unstructured geometry assembly transmission probability TPM rectangular

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Discrete ordinates method for three-dimensional neutron transport equation based on unstructured-meshes

JU Haitao, WU Hongchun, YAO Dong, XIAN Chunyu

《能源前沿（英文）》 2008年第2卷第2期页码 179-182 doi: 10.1007/s11708-008-0024-3

摘要： A discrete ordinates method for a three-dimensional first-order neutron transport equation based on unstructured-meshes that avoids the singularity of the second-order neutron transport equation in void regions was derived. The finite element variation equation was obtained using the least-squares method. A three-dimensional transport calculation code was developed. Both the triangular-z and the tetrahedron elements were included. The numerical results of some benchmark problems demonstrated that this method can solve neutron transport problems in unstructured-meshes very well. For most problems, the error of the eigenvalue and the angular flux is less than 0.3% and 3.0% respectively.

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Numerical simulation of air flow field in high-pressure fan with splitter blades

LI Jianfeng, LU Junfu, ZHANG Hai, LIU Qing, YUE Guangxi

《能源前沿（英文）》 2008年第2卷第4期页码 438-442 doi: 10.1007/s11708-008-0085-3

摘要： For a deeper understanding of the flow characteristics in the high-pressure centrifugal blower of a fan of Model 9-26 with splitter blades, a three dimensional (3-D) numerical simulation of air flows in the fan was conducted with FLUENT software. The standard - turbulent model and unstructured grids were used. The computational fluid dynamics (CFD) results showed that the performance of a fan could be improved by adding the splitter blades in the channel among the leaf blades. Under operational conditions, with the presence of splitter blades, the air flow rate of the fan increased about 5% and the total pressure at the outlet of the fan increased about 10% on average. It was also found that the length of the splitter blades affected the air flow and pressure drop. There is an optimal value for the length. The simulation results provide helpful information for improving the fan performance.

关键词： splitter numerical simulation presence unstructured operational