The Experts below are selected from a list of 61416 Experts worldwide ranked by ideXlab platform
Gregory S. Chirikjian - One of the best experts on this subject based on the ideXlab platform.
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workspace generation of hyper redundant Manipulators as a diffusion process on se n
IEEE Transactions on Robotics and Automation, 2004Co-Authors: Yunfeng Wang, Gregory S. ChirikjianAbstract:Hyper-redundant Manipulators have a large number of redundant degrees of freedom. They have been recognized as a means to improve Manipulator performance in complex and unstructured environments. However, the high degree of redundancy also causes difficulty in the calculation of workspaces and inverse kinematics. This paper develops a diffusion-based algorithm for workspace generation of hyper-redundant Manipulators. This algorithm makes the workspace generation problem as simple as solving a diffusion equation which has an explicit solution. This diffusion equation is a partial differential equation defined on the motion group SE(N), and describes the evolution of the workspace density function, depending on Manipulator length and kinematic properties. This paper also solves the inverse kinematics problem in an elegant way by dividing the Manipulator into virtual segments and cascading the corresponding workspace densities generated by the diffusion equation.
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inverse kinematics of discretely actuated hyper redundant Manipulators using workspace densities
International Conference on Robotics and Automation, 1996Co-Authors: Imme Ebertuphoff, Gregory S. ChirikjianAbstract:Hyper-redundant Manipulators present an alternative to conventional 6 DOF Manipulators for inspection, space, and medical applications. The additional degrees of freedom facilitate obstacle avoidance and allow tasks to be performed even if some of the actuators fail. In this paper the authors consider hyper-redundant Manipulators that are actuated discretely, e.g. using two-state actuators or motors with finite resolution. The inverse kinematics problem for a discretely actuated Manipulator is intrinsically different from the one for its continuously actuated counterpart. The authors present a framework for the discussion of the discretely actuated case and propose an algorithm for the inverse kinematics. The algorithm generates solutions in linear time with respect to the number of Manipulator actuators, as opposed to the exponential time required by brute force search.
Jinsong Wang - One of the best experts on this subject based on the ideXlab platform.
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a new family of spatial 3 dof fully parallel Manipulators with high rotational capability
Mechanism and Machine Theory, 2005Co-Authors: Xinjun Liu, Jinsong Wang, Gunter PritschowAbstract:Most fully-parallel Manipulators encountered today have a common disadvantage, i.e., their low rotational capability. To overcome such a difficulty, this paper focuses its attention on the proposal of a new family of three-degree-of-freedom (3-DoF) fully-parallel Manipulators capable of high rotational capability. Parallelogram allows the output link to remain at a fixed orientation with respect to an input link, for which it has many unique roles, especially when creating a desirable DoF output in the design of parallel Manipulators. The role of a parallelogram herein described, is used completely for the design of a new parallel Manipulator family. In this family, the moving platform of a parallel Manipulator is connected to the base by three non-identical legs. The fact that all joints involved in the rotational DoF are with single DoF guarantees the high rotational capability performance of the Manipulators. The parallel Manipulators proposed here have wide applications in industrial robots, simulators, micro-motion Manipulators, parallel kinematics machines, and any other manipulation devices that a high rotational capability is needed. The research provides a new design methodology of novel parallel Manipulators.
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static analysis of cable driven Manipulators with non negligible cable mass
Robotics Automation and Mechatronics, 2004Co-Authors: Kristopher C Kozak, Qian Zhou, Jinsong WangAbstract:This paper addresses the static analysis of cable-driven Manipulators with non-negligible cable mass. An approach to computing the static displacement of a homogeneous cable is presented. The resulting cable displacement expression is used to help solve the inverse kinematics of general cable-driven Manipulators. In addition, the sag-induced stiffness of the cables is derived. Finally, a sample Manipulator, with dimensions and system parameters similar to a large scale cable-driven Manipulator currently under development, is analyzed. The results show that cable-sag can have a significant effect on the stiffness of such Manipulators.
Hong Liu - One of the best experts on this subject based on the ideXlab platform.
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an analytical solution for inverse kinematic of 7 dof redundant Manipulators with offset wrist
International Conference on Mechatronics and Automation, 2012Co-Authors: Minghe Jin, Hong LiuAbstract:A valid analytical inverse kinematics computation for seven-degree-of-freedom (7-DOF) redundant Manipulators with offset-wrist is proposed. The method uses a virtual joint to replace the join offset from the wrist, and forms a virtual Manipulator with a sphere-wrist. Assuming that the virtual Manipulator and the real Manipulator's joint angles keep the same all the time, the virtual Manipulator seems to be driven by the real Manipulator; meanwhile, the real Manipulator seems to be driven by the virtual Manipulator. There is an interesting relationship between these two Manipulators: the pose of the virtual Manipulator can be calculated if the pose and the 7th joint's angle of the real Manipulator are given. It means that the virtual Manipulator is driven to the calculated pose when the real Manipulator moves to the given pose with the given 7th joint angle, meanwhile, the real Manipulator will be driven to the to the given pose when the virtual Manipulator moves to the calculated pose with the given 7th joint angle. Then the inverse kinematic solutions of real Manipulator can be obtained through solving the inverse kinematic problems of virtual Manipulator with a known 7th joint angle. They share the same solutions. In this paper, the Manipulators' configuration is analyzed and the virtual joint method and its detailed solution processes were given. Lastly the method is verified by kinematic simulations. The results show that the virtual joint method behaves high precision in solving the inverse kinematic of 7-DOF redundant Manipulator with offset-wrist.
Lungwen Tsai - One of the best experts on this subject based on the ideXlab platform.
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Jacobian Analysis of Limited-DOF Parallel Manipulators
Journal of Mechanical Design, 2002Co-Authors: Sameer A Joshi, Lungwen TsaiAbstract:This paper presents a methodology for the Jacobian analysis of limited degrees-of-freedom (DOF) parallel Manipulators. A limited-DOF parallel Manipulator is a spatial parallel Manipulator which has less than six degrees-of-freedom. It is shown that a 6X6 Jacobian matrix, which provides information about both architecture and constraint singularities, can be derived by making use of the theory of reciprocal screws. The 3-UPU and 3-RPS parallel Manipulators are used as examples to demonstrate the methodology.
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jacobian analysis of limited dof parallel Manipulators
ASME 2002 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2002Co-Authors: Sameer A Joshi, Lungwen TsaiAbstract:This paper presents a methodology for the Jacobian analysis of limited degrees-of-freedom (DOF) parallel Manipulators. A limited-DOF parallel Manipulator is a spatial parallel Manipulator which has less than six degrees-of-freedom. It is shown that a 6 × 6 Jacobian matrix, which provides complete information about singularities, can be derived by making use of the theory of reciprocal screws. The 3-UPU and 3-RPS parallel Manipulators are used as examples to demonstrate the methodology.Copyright © 2002 by ASME
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kinematics and optimization of a spatial 3 upu parallel Manipulator
Journal of Mechanical Design, 2000Co-Authors: Lungwen Tsai, Sameer A JoshiAbstract:The structural characteristics associated with parallel Manipulators are investigated. Using these characteristics a class of 3 degree-of-freedom parallel Manipulators are enumerated. Several parallel Manipulators with only translational degrees of freedom are identified and the 3-UPU parallel Manipulator is chosen for design analysis and optimization. The kinematics of this 3-UPU parallel Manipulator is studied. Two geometric conditions that lead to pure translational motion of the moving platform are described. Due to the simple kinematic structure, the inverse kinematics yields two equal and opposite limb lengths whereas the direct kinematics produces two possible Manipulator postures with one being the mirror image of the other. The Jacobian matrix is derived and several singular conditions are discussed. Furthermore the conditions for existence of an isotropic point within the workspace are discussed and equations to compute the isotropic configurations of a 3-UPU Manipulator are derived. Finally, we undertake architecture optimization and show that certain values of design variables maximize the global condition index of the 3-UPU Manipulator.
Roger Boudreau - One of the best experts on this subject based on the ideXlab platform.
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force optimization of kinematically redundant planar parallel Manipulators following a desired trajectory
Mechanism and Machine Theory, 2012Co-Authors: Roger Boudreau, Scott B NoklebyAbstract:Abstract In this work, an optimization-based methodology for resolving the generalized forces for kinematically-redundant planar parallel Manipulators following a desired trajectory is presented. The proposed methodology assumes that the Manipulator is performing a task that is slow enough to allow kinetostatic analysis to be used. Two test trajectories were used to show the effectiveness of the proposed methodology. The results for a kinematically-redundant 3- P R P R Manipulator were compared against the results for a non-redundant 3-R P R Manipulator. The results show that the redundant Manipulator has improved force capabilities compared to the non-redundant Manipulator. In particular, the redundant Manipulator is able to pass through singular configurations with feasible generalized forces, something the non-redundant Manipulator cannot do.
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Kinematic analysis and path planning of a new kinematically redundant planar parallel Manipulator
Robotica, 2008Co-Authors: Iman Ebrahimi, Juan A. Carretero, Roger BoudreauAbstract:In this work, the 3- RP RR, a new kinematically redundant planar parallel Manipulator with six-degrees-of-freedom, is presented. First, the Manipulator is introduced and its inverse displacement problem discussed. Then, all types of singularities of the 3- RP RR Manipulator are analysed and demonstrated. Thereafter, the dexterous workspace is geometrically obtained and compared with the non-redundant 3- P RR planar parallel Manipulator. Finally, based on a geometrical measure of proximity to singular configurations and the condition number of the Manipulators' Jacobian matrices, actuation schemes for the Manipulators are obtained. Different actuation schemes for a given path are obtained and the quality of their actuation schemes are compared. It is shown that the proposed Manipulator is capable of following a path while avoiding the singularities.
