Excavation Trajectory Planning Method Based on Path Coarse Interpolation

Ziwei Wang,Guangjun Liu,Bobo Helian,Yunfei Wang 제어로봇시스템학회 2024 제어로봇시스템학회 국제학술대회 논문집 Vol.2024 No.10

This paper analyzes the advantages and disadvantages of Cartesian space trajectory planning and joint space trajectory planning. To achieve the balance between efficiency and accuracy of trajectory planning, an excavation trajectory planning method based on path coarse interpolation is proposed. Firstly, a kinematic model of the excavator is established, and the excavation path is determined. Then, the excavation path is coarse interpolated in Cartesian space and divided into multiple excavation key points. Finally, the trajectory planning is carried out in the joint space. Taking space line and space arc as examples for simulation analysis, the simulation results show that the actual path under this method coincides with the planned path highly, and the maximum error and average error in X and Z direction are both less than 0.01mm, which ensures the accuracy of path execution and has small amount of calculation. This method achieves a balance between trajectory planning efficiency and accuracy.

Application of Biophysical Properties of Meridians in the Visualization of Pericardium Meridian

Xiong Feng,Xu Ruimin,Li Tongju,Wang Jinyu,Hu Qingchuan,Song Xiaojing,Wang Guangjun,Su Huanhuan,Jia Shuyong,Wang Shuyou,Zhu Zongxiang,Zhang Weibo 사단법인약침학회 2023 Journal of Acupuncture & Meridian Studies Vol.16 No.3

Background: The biophysical properties of the meridian system, an important concept of traditional Chinese medicine, include low impedance, resounding voice, and high acoustic conductance, all of which are helpful for elucidating the essence of meridians. Objectives: To visualize the human pericardium meridian (PC) based on the resounding voice property of meridians. Methods: Visualization of the PC was performed by injection of fluorescein sodium at the PC6 acupoint (Neiguan) on the PC. Before injection, percussion active points (PAPs) were identified by the virtue of their resounding voice properties. After injection, the trajectories of fluorescein migration throughout the body surface were recorded and analyzed. The distribution of fluorescein in the tissue was further studied using cross-sections of hind limbs of mini-pigs, in which fluorescein was injected into low impedance points. Results: The identified PAP lines were colocalized with PC. Following intradermal fluorescein injection, 1-3 fluorescent lines, which were unrelated to the arm veins, were observed in 7 of 10 participants; 85.4% of fluorescent signals were coincident with PAPs and their intensity had a negative correlation with the body mass index (r = –0.56, p = 0.045). Cross-sections showed a Y-shaped fluorescence pattern where the two migration lines on the surface were the two vertices of the “Y.” Conclusion: The trajectories of fluorescein in the body are suggestive of the anatomical structure of meridians. The PC is related to the deep horizontal interstitial channels that connect to the body surface through vertical interstitial spaces. These biophysical properties and techniques for meridian visualization are valuable for revealing the anatomical structure of meridians.

Homomorphic Subspace MAC Scheme for Secure Network Coding

Guangjun Liu,Xiao Wang 한국전자통신연구원 2013 ETRI Journal Vol.35 No.1

Existing symmetric cryptography-based solutions against pollution attacks for network coding systems suffer various drawbacks, such as highly complicated key distribution and vulnerable security against collusion. This letter presents a novel homomorphic subspace message authentication code (MAC) scheme that can thwart pollution attacks in an efficient way. The basic idea is to exploit the combination of the symmetric cryptography and linear subspace properties of network coding. The proposed scheme can tolerate the compromise of up to r–1 intermediate nodes when r source keys are used. Compared to previous MAC solutions, less secret keys are needed for the source and only one secret key is distributed to each intermediate node.

Optimization of the anti-snow performance of a high-speed train based on passive flow control

Guangjun Gao,Zhen Tian,Jiabin Wang,Yan Zhang,Xinchao Su,Jie Zhang 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.4

In this paper, the improvement of the anti-snow performance of a high-speed train (HST) is studied using the unsteady Reynolds-Averaged Navier-Stokes simulations (URANS) coupled with the Discrete Phase Model (DPM). The influences of the proposed flow control scheme on the velocity distribution of the airflow and snow particles, snow concentration level and accumulated mass in the bogie cavities are analyzed. The results show that the front anti-snow structures can effectively deflect downward the airflow and snow particles at the entrance of the cavities and alleviate the strong impact on the bogie bottom, thereby decrease the local accumulated snow. The rotational rear plates with the deflecting angle of 45° are found to present well deflecting effect on the particles’ trajectories and force more snow to flow out of the cavities, and thus significantly reduce the accretion distribution on the bogie top. Furthermore, running speeds of HST are shown to have a great effect on the snow-resistance capability of the flow control scheme. The proposed flow control scheme achieves more snow reduction for HST at higher train’s running speed in the cold regions.

Effect of bogie fairings on the snow reduction of a high-speed train bogie under crosswinds using a discrete phase method

Guangjun Gao,Yani Zhang,Jie Zhang,Fei Xie,Yan Zhang,Jiabin Wang 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.4

This paper investigated the wind-snow flow around the bogie region of a high-speed train under crosswinds using a coupled numerical method of the unsteady Realizable k-ε turbulence model and discrete phase model (DPM). The flow features around the bogie region were discussed and the influence of bogie fairing height on the snow accumulation on the bogie was also analyzed. Here the high-speed train was running at a speed of 200 km/h in a natural environment with the crosswind speed of 15 m/s. The mesh resolution and methodology for CFD analysis were validated against wind tunnel experiments. The results show that large negative pressure occurs locally on the bottom of wheels, electric motors, gear covers, while the positive pressure occurs locally on those windward surfaces. The airflow travels through the complex bogie and flows towards the rear bogie plate, causing a backflow in the upper space of the bogie region. The snow particles mainly accumulate on the wheels, electric motors, windward sides of gear covers, side fairings and back plate of the bogie. Longer side fairings increase the snow accumulation on the bogie, especially on the back plate, side fairings and brake clamps. However, the fairing height shows little impact on snow accumulation on the upper region of the bogie. Compared to short side fairings, a full length side fairing model contributes to more than two times of snow accumulation on the brake clamps, and more than 20% on the whole bogie.

Fibroblast Activation Protein-Responsive Peptide Nanocarrier Deliver BET Inhibitor to Reduce ECM in Pancreatic Cancer and Enhance the Efficacy of Chemotherapy

Yazhou Wang,Chong Du,Xiaodong Tian,Guangjun Nie,Yinmo Yang 대한외과학회 2018 대한외과학회 학술대회 초록집 Vol.2018 No.11

Effect of bogie fairings on the snow reduction of a high-speed train bogie under crosswinds using a discrete phase method

Gao, Guangjun,Zhang, Yani,Zhang, Jie,Xie, Fei,Zhang, Yan,Wang, Jiabin Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.27 No.4

This paper investigated the wind-snow flow around the bogie region of a high-speed train under crosswinds using a coupled numerical method of the unsteady Realizable $k-{\varepsilon}$ turbulence model and discrete phase model (DPM). The flow features around the bogie region were discussed and the influence of bogie fairing height on the snow accumulation on the bogie was also analyzed. Here the high-speed train was running at a speed of 200 km/h in a natural environment with the crosswind speed of 15 m/s. The mesh resolution and methodology for CFD analysis were validated against wind tunnel experiments. The results show that large negative pressure occurs locally on the bottom of wheels, electric motors, gear covers, while the positive pressure occurs locally on those windward surfaces. The airflow travels through the complex bogie and flows towards the rear bogie plate, causing a backflow in the upper space of the bogie region. The snow particles mainly accumulate on the wheels, electric motors, windward sides of gear covers, side fairings and back plate of the bogie. Longer side fairings increase the snow accumulation on the bogie, especially on the back plate, side fairings and brake clamps. However, the fairing height shows little impact on snow accumulation on the upper region of the bogie. Compared to short side fairings, a full length side fairing model contributes to more than two times of snow accumulation on the brake clamps, and more than 20% on the whole bogie.

The local time of the linear self-attracting diffusion driven by weighted fractional Brownian motion

Qin Chen,Guangjun Shen,Qingbo Wang 대한수학회 2020 대한수학회보 Vol.57 No.3

In this paper, we introduce the linear self-attracting diffusion driven by a weighted fractional Brownian motion with weighting exponent $a>-1$ and Hurst index $|b|<a+1,0<b<1$, which is analogous to the linear fractional self-attracting diffusion. For the 1-dimensional process we study its convergence and the corresponding weighted local time. As a related problem, we also obtain the renormalized intersection local time exists in $L^2$ if $\text{max}\{a_1+b_1,a_2+b_2\}<0$.

Stiffness Recognition Method Based on Modal Vibration for Serial Robotic Systems

Siyu Liang,Guangjun Liu,Bobo Helian,Yunfei Wang 제어로봇시스템학회 2024 제어로봇시스템학회 국제학술대회 논문집 Vol.2024 No.10

Automatic drilling systems based on 6-DOF robots are widely used in aviation manufacturing and other fields. However, as traditional serial robots with weak stiffness, the influence of stiffness on the machining system cannot be ignored in loading or working. Thus, it is significant to recognize the stiffness characteristic of robotic drilling systems precisely and rapidly. This paper presents a comprehensive study of the mechanical properties of serial manipulators, specifically focusing on stiffness and vibration theories. A novel model, the serial rigid links connected by elastic joints (SRLCEJ) with Spong’s joints, is introduced to describe the pose deformations under external forces, considering the links as rigid bodies for equivalent joint stiffness conversion. The paper further proposes a dynamic stiffness recognition method, integrating modal vibration theory. The efficacy and accuracy of the proposed theories and methods are validated through simulation results. The findings confirm that joint stiffness parameters can be obtained by vibration responses. In this method, the system stiffness properties can be estimated by neither setting any additional sensor on the end effector nor undertaking any other test when the robot reaches a new posture, which would be more convenient to operate. and may play an important role in robot dynamic stiffness control, online measurement, and real-time error compensation.

Real-time Semantic Segmentation and Grid-space Optimization for Sparse Point Cloud

Lunhui Zhang,Guangjun Liu,Changxin Wang,Bobo Helian,Yunfei Wang 제어로봇시스템학회 2024 제어로봇시스템학회 국제학술대회 논문집 Vol.2024 No.10

The identification of granular materials is a crucial ability for automating construction machinery. Current point clouds segmentation methods struggle to segment shapeless objects, such as sand piles, due to sparse features. A real-time semantic sparse point cloud segmentation framework based on multi-view method is developed using a multi-sensor fusion SLAM algorithm with visual odometry. This approach has inherent semantic mapping errors caused by external calibration, dynamic pose estimation, and image segmentation. To enhance segmentation accuracy, a grid-space optimization algorithm has been proposed. The first step involves finding the incorrect segmented points by checking the pixel-depth gradient in grid space. Secondly, depth density clustering are applied to these points for re-segmentation. Our algorithm was tested on gravel and sand piles in construction scenarios. The experimental results demonstrated that our segmentation strategy can effectively segment granular objects. Furthermore, our two-step scanning and re-segmentation methods can significantly improve the performance of point cloud semantic segmentation.