323,196 research outputs found
Direct and Inverse Kinematics for Coordinated Motion Tasks of a Two-Manipulator System
No full textA new formulation for direct kinematics of a system of two manipulators is presented. This allows a straightforward description of general coordinated motion tasks in terms of meaningful absolute and relative variables. An effective inverse kinematics algorithm is devised which exploits the above formulation where the task Jacobians are expressed in terms of the Jacobians of the single manipulators. The scheme is extended to handle the presence of redundant degrees of freedom in the system. Different types of grasp between the end effectors and a commonly held object are treated with minimum reformulation effort. Case studies are developed throughout the paper for a system of two PUMA 560 manipulators which illustrate the capabilities of the scheme
La motivaciónde l@s estudiantes de nivel secundario en las clases de educación física en relación a su intención futura de práctica de actividad física
No full textEl objetivo de nuestro trabajo de investigación es analizar la relación que existe entre la motivación intrínseca, la orientación motivacional y el estado de flow con la intención de práctica física futura de l@s estudiantes de la escuela secundaria. Se trata de un estudio descriptivo-correlacional, cuantitativo que forma parte una investigación macro simultánea en Argentina, España y Colombia, en la que l@s investigadores administramos el Cuestionario Q 1 -A –Motivación en educación validado en múltiples investigaciones previas. A nivel micro, lo realizamos en una escuela secundaria de la ciudad de Alta Gracia, provincia de Córdoba.Fil: Chiacchio, Gabriela Elsa. Universidad de Flores; Argentina
Task-space regulation of cooperative manipulators
No full textIn this paper a new task-space regulation scheme for a system of two cooperative manipulators tightly grasping a rigid object is proposed. The control architecture is based on individual task-space regulators for the two manipulators. In order to overcome problems arising from representation singularities, the unit quaternion is used to describe the orientation of relevant frames. To avoid steady-state internal stresses at the held object, kinetostatic filtering of the control action is introduced together with internal force feedback. Also, the performance of the control scheme is analyzed in the presence of a class of modeling uncertainties. The equilibria of the closed-loop system are then explicitly computed and asymptotic stability is proven via Lyapunov-like analysis
On low eigenvalues of the Laplacian with mixed boundary conditions
No full textAbstractBy means of the so-called α-symmetrization we study the eigenvalue problem for the Laplace operator with mixed boundary conditions. We obtain various bounds for combinations of the low eigenvalues and some sharp comparison results for the first eigenfunction in terms of Bessel functions
Multiple vortices for a self-dual Maxwell-Chern-Simons model
No full textIn this paper we study the multiple existence of multivortices for the self-dual CP(1) Maxwell-Chern-Simons model. The multivortices for this model correspond to solutions for an elliptic system of two unknown functions with exponential nonlinearity and Dirac measures of positive and negative signs as source terms, defined on a two-dimensional compact manifold such as a flat torus. The existence of at least one multivortex solution for this model was established by D. Chae and H.-S. Nam [Ann. Henri Poincar ́e, (2001)]; and in the case that all vortex points have a negative sign, the existence of the second multivortex solution was proved by the second author [Differential Integral Equations, (2004)]. This paper settles the question of multiple existence affirmatively in a more general case, that is, the case of mixed (but different numbers of positive and negative) vortices. It is proved first that the elliptic system arising from this model is equivalent to a fourth-order scalar elliptic equation with exponential nonlinearity. Then it is shown that this fourth-order equation has a nice variational structure enjoying the compactness property, and the desired solutions are obtained as local minima and critical points, via a mountain-pass theorem, of the associated energy functional. Construction of the local minimum solution is a key in the proof
Dexterous reconfiguration of a two-arm robot system
No full textAn inverse kinematics solution scheme has been devised for a two-arm redundant cooperative system with a force manipulability ellipsoid constraint. The developed case studies have demonstrated that the solution is very flexible as it can handle different types of redundancies. Nonetheless, it should be remarked that the inverse kinematics of more complex multi-arm systems can be solved with the proposed scheme if an effective description of the cooperative task is provided. Moreover, other kinds of constraints can be considered in the same framework as long as they can be functionally characterized in terms of the joint variables of the overall system
Task-oriented kinematic control of two cooperative 6-DOF manipulators
No full textThe kinematic control problem for a system of two cooperative 6-dof manipulators is addressed in this paper. First, a kinematic model of the system is obtained which allows a clear description of the task in terms of absolute and relative variables. Then, a suitable inverse kinematics scheme is designed to compute the joint variable trajectories corresponding to a given trajectory for the above cooperative task variables. The effectiveness of the technique is demonstrated by two case studies for two cooperative PUMA 560 robot manipulators; one regards a typical coordinated motion for the system, the other is aimed at illustrating the redundancy resolution features of the scheme
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