Article
Computer Science, Information Systems
Wei You, Xue Wang, Weihang Zhang, Zhenfeng Qiang
Summary: This paper proposes a multi-level kinematic constraints method to construct multiple skeleton features, which can effectively utilize valid information and enhance the performance of skeleton-based action recognition methods.
MULTIMEDIA TOOLS AND APPLICATIONS
(2022)
Article
Chemistry, Medicinal
Qinyang Li, Rongzhi Dong, Nihang Fu, Sadman Sadeed Omee, Lai Wei, Jianjun Hu
Summary: Understanding the relationship between composition, structure, and function in materials is crucial for discovering and designing new functional materials. In this study, we globally mapped all known materials in the Materials Project database to investigate their distribution in a set of seven descriptors. These maps provide a comprehensive overview of materials and space, revealing previously undescribed fundamental properties.
JOURNAL OF CHEMICAL INFORMATION AND MODELING
(2023)
Article
Robotics
Zijia Li, Mathias Brandstoetter, Michael Hofbaur
Summary: This article presents the kinematic analysis of redundant serial manipulators with 2n + 1 revolute joints, also known as circular manipulators. The special properties of the kinematic chain structure of circular manipulators are discussed, and a radical reparametrization method is proposed. The article also explores the inverse kinematics solution for redundant serial manipulators and conjectures numerical kinematic singularities for circular manipulators.
IEEE TRANSACTIONS ON ROBOTICS
(2023)
Article
Engineering, Aerospace
Xiaodong Shao, Qinglei Hu
Summary: This study introduces an I&I adaptive pose control scheme based on APFs to address the pose control issue of spacecraft proximity operations subject to various constraints and uncertainties, showing efficient control performance and asymptotic stability.
IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS
(2021)
Article
Computer Science, Information Systems
Ukasz Wolinski, Marek Wojtyra
Summary: Kinematically redundant manipulators have increased dexterity and the ability to fulfill secondary requirements. This paper presents a novel redundancy resolution method based on a quadratic programming approach, allowing joint constraints to be fulfilled at different levels.
Article
Mathematics
Jianguo Sun, Xiaoyan Jiang, Fenghui Ji
Summary: This paper focuses on some geometrical properties of the partially null slant helices in semi-Euclidean 4-space. By structuring suitable height functions, the singularity types of the pseudonull hypersurfaces generated by these helices are obtained, with an example provided to determine the main results.
Article
Computer Science, Information Systems
Junyong Wang, Thar Baker, Yingnan Zhou, Ali Ismail Awad, Bin Wang, Yongsheng Zhu
Summary: Configuration errors are a significant cause of software failures, and improper configuration options can pose a significant security risk to software. Existing techniques often require human intervention or additional inputs, but we propose a program and static analysis-based technique that can automatically map all configuration options just by reading the source code. Our evaluation shows high success rates in various modules and software, and also identifies undocumented configuration options.
JOURNAL OF KING SAUD UNIVERSITY-COMPUTER AND INFORMATION SCIENCES
(2022)
Article
Astronomy & Astrophysics
J. A. Melendez, C. Drischler, A. J. Garcia, R. J. Furnstahl, Xilin Zhang
Summary: The article presents a fast and accurate emulator for two-body scattering observables, which combines Newton's variational method with ideas from eigenvector continuation. The emulator is shown to accurately extrapolate far from the support of the training data, providing significant improvement in CPU time when used to emulate interactions with multiple free parameters.
Article
Materials Science, Multidisciplinary
Jia-Zheng Ma, Trinanjan Datta, Dao-Xin Yao
Summary: A new geometric effective theory based on curved space-time single valley Dirac theory with spin connection for twisted bilayer graphene is proposed. It can reproduce nearly flat bands with particle-hole symmetry and predict the properties of rotating bilayer graphene that cannot be accessed by previous theories, such as investigating the Bott index and relating it to the two-dimensional Thouless pump.
Article
Engineering, Industrial
Delphine Guillon, Rania Ayachi, Elise Vareilles, Michel Aldanondo, Eric Villeneuve, Christophe Merlo
Summary: Consumer attitudes and expectations are changing rapidly, leading to a demand for more customized products and services. Companies are responding by adding more services to products in order to differentiate themselves from competitors. To adapt to these market trends, companies now have to offer more sophisticated solutions to consumers.
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH
(2021)
Article
Mathematics, Applied
Jin-Guo Liu, Xun Gao, Madelyn Cain, Mikhail D. Lukin, Sheng-Tao Wang
Summary: This article introduces a unified framework for computing the solution space properties of a broad class of combinatorial optimization problems. Using the example of the independent set problem, the author demonstrates how these properties can be computed using the generic tensor network approach.
SIAM JOURNAL ON SCIENTIFIC COMPUTING
(2023)
Article
Astronomy & Astrophysics
Markus Q. Huber, Wolfgang J. Kern, Reinhard Alkofer
Summary: We use contour deformations to investigate the analytic structure of three-point functions, allowing calculations to continue analytically from the spacelike to the timelike regime. We demonstrate how to deform the integration contour and cuts in the integrand to obtain the known cut structure of two-point functions. This method is then applied to one-loop three-point integrals, revealing the relevance of singular points in determining physical thresholds.
Article
Automation & Control Systems
Jiangping Wang, Shirong Liu, Botao Zhang, Changbin Yu
Summary: This paper presents an efficient and probabilistic complete planning algorithm called Composite-space RRT for motion planning with soft constraints for spherical wrist manipulators. The algorithm generates collision-free paths in a novel configuration space called Composite Configuration Space, and maps them into joint-space paths using analytical inverse kinematics. The proposed algorithm is characterized by high efficiency and no numerical iteration, demonstrating effectiveness in improving the smoothness of end-effector orientation paths.
INTERNATIONAL JOURNAL OF CONTROL AUTOMATION AND SYSTEMS
(2021)
Article
Astronomy & Astrophysics
A. D. Cameron, M. Bailes, D. J. Champion, P. C. C. Freire, M. Kramer, M. A. McLaughlin, C. Ng, A. Possenti, A. Ridolfi, T. M. Tauris, H. M. Wahl, N. Wex
Summary: PSR J1757-1854 is a double neutron star binary system in our Galaxy, which exhibits relativistic properties and offers a potential for testing relativistic gravity. Through a 6-year observational campaign, we confirmed the presence of geodetic precession in PSR J1757-1854 and updated its timing and mass constraints. However, the precision of the radiative test of gravity is limited by the unknown distance to the pulsar. We also searched for pulsations from the companion neutron star but obtained negative results. Nevertheless, the system presents opportunities for future relativistic tests of gravity, with expected constraints on the change in the semimajor axis and the relativistic orbital deformation parameter.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Physics, Multidisciplinary
Maria Azhar, Volodymyr P. Kravchuk, Markus Garst
Summary: This paper investigates the micromagnetic structure of screw dislocation lines in cubic chiral magnets and finds that different strength dislocations can have a variety of core structures. In particular, the magnetization at the core can be either smooth or singular. Screw dislocations carry a noninteger but finite skyrmion charge and can be manipulated by spin currents, contributing to the topological Hall effect.
PHYSICAL REVIEW LETTERS
(2022)
Article
Mathematics, Applied
Andreas Mueller
Summary: The BH equations are crucial for the dynamics and control of nonholonomic systems, especially when quasi-velocities are involved. This paper presents a coordinate-free derivation of the Hamel coefficients and BH equations for rigid bodies, considering various choices of quasi-velocities and nonholonomic constraints. The connection between different equations is explored, providing insights into the structure and behavior of these systems.
JOURNAL OF NONLINEAR SCIENCE
(2021)
Article
Chemistry, Analytical
Hubert Gattringer, Andreas Mueller, Philip Hoermandinger
Summary: This paper presents two sensor concepts for measuring contact forces/torques of robotic manipulators, which are installed at the robot base instead of directly at the end-effector. These indirect measurement methods offer lower costs and easier implementation, but require a more elaborate dynamic model and calibration process for the robot.
Article
Robotics
A. Muller
Summary: This study introduces a control method using spatial representation for optimal control of robotic arms. Recursive O(n) algorithms and Lie group formulations were utilized to improve computational efficiency and compactness of expression, demonstrated on the Franka Emika Panda robot.
IEEE ROBOTICS AND AUTOMATION LETTERS
(2021)
Article
Engineering, Mechanical
Andreas Mueller
Summary: This paper presents a systematic modeling approach for PKM with complex limbs, utilizing local resolution of loop constraints to generalize the formulation for PKM with simple limbs, employing Lie group formulation for deriving the equations of motion, and exploiting the PKM topology in a parallel computation scheme for computationally efficient evaluation.
MECHANISM AND MACHINE THEORY
(2022)
Article
Automation & Control Systems
Hubert Gattringer, Andreas Mueller, Matthias Oberherber, Dominik Kaserer
Summary: This study presents a consistent method for solving the general waiter problem, which involves moving a tray with loosely placed objects as fast as possible without causing sliding. The optimal robot trajectory is determined using a multiple shooting method, taking into account the technical limitations and friction between objects and tray. Experimental results demonstrate the importance of a model-based control strategy and parameter identification in achieving optimal motion control.
Article
Engineering, Mechanical
Kun Xu, Hao Chen, Andreas Mueller, Xilun Ding
Summary: This paper presents the kinematics of the center of mass for robotic mechanisms based on Lie Group theory, which is important for the stability of mobile manipulating robots. The CoM kinematics is derived using the concept of homogeneous coordinates and the mass translation matrix. The results show that this method is useful for motion planning and ensuring stability.
MECHANISM AND MACHINE THEORY
(2022)
Article
Mechanics
Roberto Di Leva, Marco Carricato, Hubert Gattringer, Andreas Mueller
Summary: This paper validates a model for estimating the height of liquid sloshing during the movement of liquid-filled containers on a horizontal plane. The model is proven effective through experiments and extended to account for vertical acceleration.
MULTIBODY SYSTEM DYNAMICS
(2022)
Article
Engineering, Mechanical
Hubert Gattringer, Andreas Mueller, Simon Weitzhofer, Markus Schoergenhumer
Summary: This paper presents a multiple shooting method to solve the general point to point time-optimal motion planning problem for handling parts loosely placed at the end-effector of a robot. The method considers all relevant dynamic effects and ensures a C2-continuous trajectory to avoid bang-bang behavior of motor torques. Experimental results verify the feasibility of the proposed method for real robotic setup with rigid objects and address the handling of liquid-filled containers.
MECHANISM AND MACHINE THEORY
(2023)
Article
Multidisciplinary Sciences
Andreas Mueller
Summary: Modern geometric approaches in analytical mechanics utilize the bundle structure of the configuration space, which allows for an intrinsic splitting of the reduced Euler-Lagrange equations. In contrast, Hamel's equations offer a universal approach to non-holonomic mechanics in local coordinates. The connection between Hamel's formulation and geometric approaches in local coordinates has not been sufficiently discussed.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Robotics
Tobias Marauli, Hubert Gattringer, Andreas Mueller
Summary: The article introduces the time-optimal path following problem, which aims to find the shortest time duration for a given path in task space. Traditional algorithms use equidistant sampling of the path parameter, which does not consider the dynamics in joint space. To overcome this, the article proposes a sampling method based on the arc length in joint space, which guarantees bounded joint velocities and improves continuity compared to equidistant sampling. The problem is reformulated as a second-order cone programming and numerically solved, and the approach is demonstrated with a 6-DOF industrial robot following various paths in task space.
Article
Robotics
Christian Zauner, Hubert Gattringer, Andreas Mueller
Summary: This paper presents a method to derive a highly dynamic trajectory that complies with the system dynamics by solving an optimal control problem using multiple shooting. The trajectory is designed for a wheeled inverted pendulum robot to pass a height-restricting barrier. The nonconvex constraint functions and infeasible local minimum are overcome with a multistage approach, and the optimal trajectory obtained can be used as feedforward for the real system.
Article
Robotics
Andreas Mueller, Shivesh Kumar, Thomas Kordik
Summary: This letter introduces the trajectory control problem of series elastic actuators (SEA) in parallel kinematics manipulators (PKM). A computationally efficient method for evaluating the second time derivative of the inverse dynamics solution is proposed using recursive algorithms. The special topology of PKM is exploited by utilizing a Lie group formulation to derive all relations. Numerical results demonstrate the effectiveness of this approach in a 6-DOF Gough-Stewart platform (as part of an exoskeleton) and a planar PKM under a flatness-based control scheme.
IEEE ROBOTICS AND AUTOMATION LETTERS
(2023)
Proceedings Paper
Computer Science, Information Systems
Tobias Marauli, Hubert Gattringer, Andreas Mueller
Summary: This approach addresses the ill-posed nature of the inverse kinematics problem near kinematic singularities by parameterizing joint motion using arc length. By sampling the arc length, direct control over joint motion for prescribed end-effector motion is achieved, avoiding the issue of extremely large joint velocities.
ADVANCES IN SERVICE AND INDUSTRIAL ROBOTICS, RAAD 2022
(2022)
Article
Robotics
Hannes Gamper, Adrien Luthi, Hubert Gattringer, Andreas Mueller, Mario Di Castro
Summary: This paper presents a method of optimizing the design of robotic manipulators using a novel kinematic model pruning technique. The method allows simultaneous optimization of degree of freedom, link lengths, and other performance criteria, while ensuring desired end-effector position and collision avoidance.
Article
Robotics
Christoph Stoeger, Hubert Gattringer, Andreas Mueller
Summary: Pseudo-omnidirectional vehicles have high maneuverability and positioning accuracy, but their mathematical modeling is challenging due to artificial singularities in existing models. A novel singularity-free modeling concept that does not rely on switching strategies is introduced in this study, providing closed form solutions for traction forces and drive torques in practical situations with non-exactly aligned wheels. The new model serves as a basis for optimal path planning and model-based control, as demonstrated in robust simulations.
IEEE ROBOTICS AND AUTOMATION LETTERS
(2021)
