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Interactive physically based simulation of Roadheader Robot

ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2023年第2期48卷 2441-2454页

作者： Hou, Shengzhe Lu, Xinming Gao, Wenli Jiang, Shuai Zhang, Xingli Shandong Univ Sci & Technol Coll Comp Sci & Engn 579 Qianwangang Rd Qingdao 266590 Shandong Peoples R China Hiroshima Univ Grad Sch Adv Sci & Engn 1-3-2 Kagamiyama Higashihiroshima Hiroshima 7398527 Japan

Roadheader is an engineering robot widely used in underground engineering and mining industry. Interactive dynamics simulation of roadheader is a fundamental problem in unmanned excavation and virtual reality training. However, current research is only based on traditional animation techniques or commercial game engines. There are few studies that apply real-time physical simulation of computer graphics to the field of roadheader robot. This paper aims to present an interactive physically based simulation system of roadheader robot. To this end, an improved multibody simulation method based on generalized coordinates is proposed. First, our simulation method describes robot dynamics based on generalized coordinates. Compared to state-of-the-art methods, our method is more stable and accurate. Numerical simulation results showed that our method has significantly less error than the game engine in the same number of iterations. Second, we adopt the symplectic Euler integrator instead of the conventional fourth-order Runge-Kutta (RK4) method for dynamics iteration. Compared with other integrators, our method is more stable in energy drift during long-term simulation. The test results showed that our system achieved real-time interaction performance of 60 frames per second (fps). Furthermore, we propose a model format for geometric and robotics modeling of roadheaders to implement the system. Our interactive simulation system of roadheader meets the requirements of interactivity, accuracy and stability.

关键词： physically based simulation Robotics simulation Roadheader Interactive simulation Numerical integration

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physically based simulation of Fluid Movement

Physically Based Simulation of Fluid Movement

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International Conference on Computer Sciences and Applications (CSA)

作者： Yu, Qinpei Li, Guo Shan, Luobao Bo, Ku Fei, Xiao Fang, Yuheng Xi, Yuanxiao Bin, Zhangke Wuhan Vocat Coll Software & Engn Sch Comp & Software Wuhan Peoples R China

ISBN: (纸本)9780769551258

A physically based algorithm for fluid movement simulation is proposed. Compared with the traditional simulation technique, physically based simulation can represent realistic movement better. The Navier-Stokes equations are adopted as the model, and the operator splitting method is employed to split the model into external force term, advection term, diffusion term and projection term. Every step is stable, so the whole process is also stable. Thus, the large timestep can be taken to ensure the simulation speed in the fluid movement simulation.

关键词： physically based simulation fluid movement realistic simulation

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Understanding the stability of deep control policies for biped locomotion

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VISUAL COMPUTER 2023年第1期39卷 473-487页

作者： Park, Hwangpil Yu, Ri Lee, Yoonsang Lee, Kyungho Lee, Jehee Seoul Natl Univ Seoul South Korea Seoul Natl Univ Dept Comp Sci & Engn Seoul South Korea Samsung Elect Suwon South Korea Hanyang Univ Comp Sci Seoul South Korea NC Soft Sungnam South Korea

Achieving stability and robustness is the primary goal of biped locomotion control. Recently, deep reinforcement learning (DRL) has attracted great attention as a general methodology for constructing biped control policies and demonstrated significant improvements over the previous state-of-the-art control methods. Although deep control policies are more advantageous compared with previous controller design approaches, many questions remain: Are deep control policies as robust as human walking? Does simulated walking involve strategies similar to human walking for maintaining balance? Does a particular gait pattern affect human and simulated walking similarly? What do deep policies learn to achieve improved gait stability? The goal of this study is to address these questions by evaluating the push-recovery stability of deep policies compared with those of human subjects and a previous feedback controller. Furthermore, we conducted experiments to evaluate the effectiveness of variants of DRL algorithms.

关键词： Biped locomotion Deep reinforcement learning Gait analysis physically based simulation Push-recovery stability

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Efficient and Stable Generation of High-Resolution Hair and Fur With ConvNet Using Adaptive Strand Geometry Images

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IEEE ACCESS 2023年 11卷 81101-81112页

作者： Kim, Jong-Hyun Lee, Jung Inha Univ Coll Software & Convergence Dept Design Technol Incheon 22212 South Korea Hanbat Natl Univ Dept Comp Engn Daejeon 34158 South Korea

This paper proposes a technique for transforming low-resolution (LR) simulations of hair and fur into high-resolution (HR) representations without noise, using strand geometry images in the form of lines and Convolutional Neural Network (CNN or ConvNet). LR and HR data for training are obtained through physics-based simulations, and LR-HR data pairs are set up. The training data involves converting the positions of hair strands into geometry images for use in the learning process. The proposed strand network in this paper is used as an image synthesizer to upscale LR images to HR images. When the obtained HR geometry image is transformed back into HR hair through the nonlinear transform proposed in this paper, it effectively captures the elastic movement of hair that is challenging to represent with a single mapping function alone. Furthermore, we extended the solver to accommodate hair structured in a triangular mesh form. We also propose a method for adaptively refining the hair particles of strands using the Bezier curves algorithm. Additionally, we improve the algorithm to ensure that the proposed strand geometry image can work effectively even in adaptively sampled hair particle structures. As a result, the neural network enables the stable generation of strands not only for straight and curly hair but also in various environments where different external forces are applied. Furthermore, the proposed research generates results faster than previous physics-based simulations and can be easily executed without requiring a deep understanding of complex numerical analysis processes.

关键词： Hair Solid modeling Geometry Computational modeling Numerical models Training Adaptation models simulation Convolutional neural networks Hair simulation fur simulation convolutional neural network physically based simulation strand geometry image adaptive hairs curly hairs

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Nonlinear cloth simulation with isogeometric analysis

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COMPUTER ANIMATION AND VIRTUAL WORLDS 2023年第1期35卷 e2204-e2204页

作者： Ren, Jingwen Lin, Hongwei Zhejiang Univ Sch Math Sci Hangzhou Peoples R China Zhejiang Univ State Key Lab CAD&CG Hangzhou Peoples R China

physically based cloth simulation with nonlinear behaviors is studied in this article by employing isogeometric analysis (IGA) for the surface deformation in 3D space. State-of-the-art simulation techniques, which primarily rely on the triangular mesh to calculate physical points on the cloth directly, require a large number of degrees of freedom. An effective method for the cloth deformation that employs high-order continuous B-spline surfaces dependent on control points is proposed. This method leads to the merit of fewer degrees of freedom and superior smoothness. The deformation gradient on the high-order IGA element is then represented by the gradient of the B-spline function. An iterative method for solving the nonlinear optimization transferred from the implicit integration and a direct implicit-explicit method are derived on the basis of elastic force calculation to improve efficiency. The knots of the representation are effectively utilized in collision detection and response to reduce the computational burden. Experiments of nonlinear cloth simulation demonstrate the superiority of the proposed method considering performance and efficiency, achieving accurate, efficient, and stable deformation.

关键词： cloth simulation isogeometric analysis nonlinear elasticity physically based simulation

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Regularly striped preconditioner for implicit clothing simulation

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VISUAL COMPUTER 2022年第8期38卷 2827-2838页

作者： Lee, Sang-Bin Lee, Kyoung-Won Ko, Hyeong-Seok Seoul Natl Univ 1 Gwanak Ro Seoul South Korea

This paper investigates the question of whether the Jacobi preconditioner can be made to run faster by including a few additional outlying diagonals, for the case of mesh-based implicit clothing simulation. For the given N x N block system matrix A, we investigate two regularly striped (RS) preconditioners: (1) 3-RS which has two symmetric outlying diagonals with offset N/2 from the main diagonal and (2) 5-RS which has four symmetric outlying diagonals with offsets N/3 and 2N/3 from the main diagonal. This paper finds that both 3- and 5-RS preconditioners are consistently superior to the Jacobi preconditioner in the performance. based on the loop iteration count and time measurement, we finally recommend 5-RS rather than 3-RS.

关键词： Computer animation physically based simulation Clothing simulation Numerical integration

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Efficient Incremental Potential Contact for Actuated Face simulation 23

Efficient Incremental Potential Contact for Actuated Face Si...

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SIGGRAPH Asia Conference on Technical Communications (SA Technical Communications)

作者： Li, Bo Yang, Lingchen Solenthaler, Barbara Swiss Fed Inst Technol Zurich Switzerland

ISBN: (纸本)9798400703140

We present a quasi-static finite element simulator for human face animation. We model the face as an actuated soft body, which can be efficiently simulated using Projective Dynamics (PD). We adopt Incremental Potential Contact (IPC) to handle self-intersection. However, directly integrating IPC into the simulation would impede the high efficiency of the PD solver, since the stiffness matrix in the global step is no longer constant and cannot be pre-factorized. We notice that the actual number of vertices affected by the collision is only a small fraction of the whole model, and by utilizing this fact we effectively decrease the scale of the linear system to be solved. With the proposed optimization method for collision, we achieve high visual fidelity at a relatively low performance overhead.

关键词： physically based simulation Projective Dynamics Incremental Potential Contact Collision Handling

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Physics-preserving fluid reconstruction from monocular video coupling with SFS and SPH

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VISUAL COMPUTER 2020年第6期36卷 1247-1257页

作者： Nie, Xiaoying Hu, Yong Shen, Xukun Beihang Univ State Key Lab Virtual Real Technol & Syst Beijing 100191 Peoples R China Beihang Univ Sch New Media Art & Design Beijing 100191 Peoples R China

We propose a joint method to reconstruct dynamic fluid volume sequences from a monocular video. Compared with previous methods, sophisticated equipment or careful experimental setups are not required. In order to recover the surface detail and maintain its physical property, a joint reconstruction method coupled with shape from shading (SFS) and smoothed particle hydrodynamics (SPH) algorithms is proposed. SFS is the first used to recover the height field for each frame of the video, and then the height field of the first frame is further extended to a volume as the initial state of the SPH simulation. based on the above initial data, the key idea of our method is to optimize a SPH model to simulate the fluid volume sequences conforming to the laws of physical motion, and correct the fluid volumes to refine the surface details conforming to the recovered height field by SFS. Our experimental results compare favorably to the state of the art in terms of global motion features and fluid surface details and demonstrate the performance of our approach.

关键词： Fluid reconstruction SPH Shape from shading Video-based reconstruction physically based simulation

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Rockfall susceptibility and network-ranked susceptibility along the Italian railway

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ENGINEERING GEOLOGY 2021年 293卷

作者： Alvioli, Massimiliano Santangelo, Michele Fiorucci, Federica Cardinali, Mauro Marchesini, Ivan Reichenbach, Paola Rossi, Mauro Guzzetti, Fausto Peruccacci, Silvia CNR Ist Ric Protez Idrogeol Via Madonna Alta 126 I-06128 Perugia Italy

Rockfalls pose a substantial threat to ground transportation, due to their rapidity, destructive potential and high probability of occurrence on steep topographies, often found along roads and railway routes. Approaches for the assessment of rockfall susceptibility range from purely phenomenological methods and statistical methods, suitable for modeling large areas, to purely deterministic ones, usually easier to use in local analyses. A common requirement is the need to locate potential detachment points, often found uphill on cliffs, and the subsequent assessment of the runout areas of rockfalls stemming from such points. Here, we apply a physically based model for the calculation of rockfall trajectories along the whole Italian railway network, within a corridor of total length of about 17,000 km and varying width. We propose a data-driven method for the location of rockfall source points based on expert mapping of potential source areas on sample representative locations. Using empirical distributions of gridded slope angle values in source areas mapped by experts, we derived probabilistic maps of rockfall sources in the proximity of the railway network, regardless of a particular trigger. Source areas act as starting points of simulated trajectories within the three-dimensional model STONE. The program provides a pixel-by-pixel trajectory count, covering 24,500 km(2) and representing the largest homogeneous application of the model to date. We classified the raster map into a vector susceptibility map, analyzing the railway track as a collection of segments, for which we provide segment-wise rockfall susceptibility. Eventually, we considered an equivalent graph representation of the network, which helps classifying the segments both on the basis of rockfall susceptibility and the role of each segment in the network, resulting in a network-ranked susceptibility. Both maps are useful for subsequent hazard assessment, and to prioritize safety improvements along th

关键词： Rockfall Transportation Network physically based simulation Rockfall Susceptibility

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Real-Time 3D Position-based Dynamics simulation for Hydrographic Printing 33

Real-Time 3D Position-Based Dynamics Simulation for Hydrogra...

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33rd SIBGRAPI Conference on Graphics, Patterns and Images (SIBGRAPI)

作者： Thomas, Leonardo Aguero, Karl Apaza Apolinario Jr, Antonio Lopes Fed Univ Bahia UFBA Dept Comp Sci Salvador BA Brazil

ISBN: (纸本)9781728192741

Hydrographic Printing, also called Hydrographics, is a viable method for coloring objects created with 3D printers. However, executing the hydrographic technique leads to a complex interaction between a thin film and a 3D printed object, in which the image in the film must adhere to the object. To handle the difficulty of predicting the final result of hydrographic printing, we propose a 3D computational simulation that uses Position-based Dynamics, a popular technique for simulating deformable bodies and widely used in physics engines. We take advantage of this technique running in parallel a GPU-based simulation with suitable performance. We simulate the film behavior and its interaction with the printed object, as an interaction between a soft-body colliding with a rigid one. To evaluate the achieved performance consistency, we varied the number of vertices and voxels in the bodies involved and observed that the simulation kept running in real-time. We also execute the hydrographic technique in different printed models and compare these results with the simulated models.

关键词： 3D Printing Hydrographic Printing physically based simulation Real Time Rendering Soft Body simulation Texture Mapping

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