In the last two decades, through technological, experimental and theoretical advances, the situation in experimental fission studies has changed dramatically. With the use of advanced production and ...detection techniques both much more detailed and precise information can now be obtained for the traditional regions of fission research and, crucially, new regions of nuclei have become routinely accessible for fission studies. This work first of all reviews the recent developments in experimental fission techniques, in particular the resurgence of transfer-induced fission reactions with light and heavy ions, the emerging use of inverse-kinematic approaches, both at Coulomb and relativistic energies, and of fission studies with radioactive beams. The emphasis on the fission-fragment mass and charge distributions will be made in this work, though some of the other fission observables, such as prompt neutron and γ-ray emission will also be reviewed. A particular attention will be given to the low-energy fission in the so far scarcely explored nuclei in the very neutron-deficient lead region. They recently became the focus for several complementary experimental studies, such as β-delayed fission with radioactive beams at ISOLDE(CERN), Coulex-induced fission of relativistic secondary beams at FRS(GSI), and several prompt fusion-fission studies. The synergy of these approaches allows a unique insight in the new region of asymmetric fission around 180Hg, recently discovered at ISOLDE. Recent extensive theoretical efforts in this region will also be outlined. The unprecedented high-quality data for fission fragments, completely identified in Z and A, by means of reactions in inverse kinematics at FRS(GSI) and VAMOS(GANIL) will be also reviewed. These experiments explored an extended range of mercury-to-californium elements, spanning from the neutron-deficient to neutron-rich nuclides, and covering both asymmetric, symmetric and transitional fission regions. Some aspects of heavy-ion induced fusion-fission and quasifission reactions will be also discussed, which reveal their dynamical features, such as the fission time scale. The crucial role of the multi-chance fission, probed by means of multinucleon-transfer induced fission reactions, will be highlighted. The review will conclude with the discussion of the new experimental fission facilities which are presently being brought into operation, along with promising 'next-generation' fission approaches, which might become available within the next decade.
The paper presents a fast online predictive method to solve the task-priority differential inverse kinematics of redundant manipulators under kinematic constraints. It implements a task-scaling ...technique to preserve the desired geometrical task, when the trajectory is infeasible for the robot capabilities. Simulation results demonstrate the effectiveness of the methodology.
A kinematically complete quasifree (p, pn) experiment in inverse kinematics was performed to study the structure of the Borromean nucleus 17B, which had long been considered to have a neutron halo. ...By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 1s1/2 and 0d5/2 orbitals, and a surprisingly small percentage of 9(2)% was determined for 1s1/2. Our finding of such a small 1s1/2 component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in 17B. The present work gives the smallest s - or p -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of s or p orbitals is not a prerequisite for the occurrence of a neutron halo.
In this article, we propose a new method for multirobot systems to have reactive responses to various collision scenarios in real time. This method contains a novel Formula Omitted-norm ...approximation-based reactive approach, which allows multiple robots to avoid mutual collisions or to adapt to the collisions with intelligently regulated force. Compared with existing approaches, the implementation of the proposed method is simpler and more convenient since our reactive approach works as several linear quadratic programming constraints, allowing for flexible utilization by inverse kinematics solvers. In addition, it requires low computational complexity, achieves high accuracy, and does not need training. In the experiments, we employ a multirobot system to conduct comprehensive comparisons between the proposed method and state-of-the-art approaches, effectively showcasing the efficacy of our work.
A solving method for the inverse-kinematics （IK） problem of a kind of 6 degree of freedom （DOF） manipulator with the axes of the 3 adjacent rotational joints in the arm part，shoulder，elbow and wrist ...parallel is presented. The merit of this method is that，by utilizing the geometrical relation between the end-effector，hand and wrist of the manipulator determined by its structure，the position of the wrist corresponding to a desired end-effector orientation and position can be solved at the first step in the whole calculation process. And then，the solution of a 6-variable equations，which describes the relationship between the 6 joint positions of the manipulator and its end-effector orientation and position is reduced into two 3-variable equations，one of which describes the relationship between the wrist position and the positions of 3 joints distributed in the shoulder and elbow，and the other describes the relationship between the end-effector orientation and the positions of the rest 3 joint distributed in the
We describe our full body humanoid control approach developed for the simulation phase of the DARPA Robotics Challenge (DRC), as well as the modifications made for the DARPA Robotics Challenge ...Trials. We worked with the Boston Dynamics Atlas robot. Our approach was initially targeted at walking, and it consisted of two levels of optimization: a high‐level trajectory optimizer that reasons about center of mass and swing foot trajectories, and a low‐level controller that tracks those trajectories by solving floating base full body inverse dynamics using quadratic programming. This controller is capable of walking on rough terrain, and it also achieves long footsteps, fast walking speeds, and heel‐strike and toe‐off in simulation. During development of these and other whole body tasks on the physical robot, we introduced an additional optimization component in the low‐level controller, namely an inverse kinematics controller. Modeling and torque measurement errors and hardware features of the Atlas robot led us to this three‐part approach, which was applied to three tasks in the DRC Trials in December 2013.
Learning from demonstration (LfD) has been widely studied as a convenient method for robot learning. In the LfD paradigm for redundant manipulators, the reproduced trajectories ought to be similar to ...human demonstrations in both task and joint space. Despite many advancements achieved in the context of learning in task space, the solutions for generating similar reproductions in joint space are still largely open. In this paper, a novel non-parametric LfD framework for 7-DOF anthropomorphic manipulators with high computational efficiency is proposed. The proposed method leverages redundancy resolution and kernel-based approaches to formulate an efficient model characterized by a limited set of open parameters. Experiments were conducted to evaluate the performance of the proposed method and compare it with the commonly used ‘LfD+IK’ solution. The results indicated that the proposed method behaves much better in terms of the similarity between the demonstration and reproduction with high computing efficiency. As the proposed method can learn from human demonstrations effectively in both task and joint space, it has the potential to significantly enhance human–robot collaboration, streamline assembly line processes, or improving robot learning. An important future challenge will be extending the proposed method for general-purpose redundant manipulators and considering task constraints to perform complex tasks.
The structure of a neutron-rich 25F nucleus is investigated by a quasifree (p,2p) knockout reaction at 270 A MeV in inverse kinematics. The sum of spectroscopic factors of π0d5/2 orbital is found to ...be 1.0 ± 0.3 . However, the spectroscopic factor with residual 24O nucleus being in the ground state is found to be only 0.36 ± 0.13 , while those in the excited state is 0.65 ± 0.25 . The result shows that the 24O core of 25F nucleus significantly differs from a free 24O nucleus, and the core consists of ∼ 35 % 24Og.s. and ∼ 65 % excited 24O. The result may infer that the addition of the 0d5/2 proton considerably changes neutron structure in 25F from that in 24O, which could be a possible mechanism responsible for the oxygen dripline anomaly.
The manipulator workspace is an essential element in the field of manipulator research and is of great significance for manipulator motion planning. However, little research has been conducted on ...dividing the manipulator workspace into working subspaces. No precise division method has been proposed; the inverse kinematics of multiple solutions in manipulator trajectory planning may also cause abrupt joint changes, thus affecting the planned trajectory. The article proposes a working subspace division method for all ball‐wrist 6DOF(degree‐of‐freedom) manipulators that satisfy the Piper criterion to address the above problems. The kinematic model of the manipulator is established, and the Jacobi matrix of the manipulator is obtained. The space of joints of the manipulator is divided into unique domains containing only single inverse kinematic solutions by means of singular trajectory lines when the determinant of the Jacobi matrix is zero; The solution from the joint space to the workspace is achieved by a nonlinear mapping, which completes the partitioning of the work subspace, and each work subspace contains only unique inverse kinematic solutions. When trajectory planning is carried out from the independent area of a single workspace to the overlapping area of multiple workspaces, selecting the inverse kinematic solution in a single working subspace can effectively avoid abrupt changes in the joints of the manipulator and trajectory misalignment caused by numerous inverse solution selection problems and make the planned trajectory smooth and consistent with the operational requirements of each scene.
Abstract
In view of the complexity of the traditional inverse kinematics solution, it is solved by the mapping of the BP neural network, but the precision is low and the network performance is not ...good. By using FGA to optimize BP neural network, the shortcomings of the neural network itself can be overcome. Taking the pose matrix and joint angle of the manipulator as the input and output variables of the prediction network, the inverse solution prediction BP network of the manipulator is constructed, and then samples are selected for training. Finally, the network test and simulation results show that the optimized BP neural network has higher prediction precision and improved network performance.
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