507 research outputs found
A closed-loop jacobian transpose scheme for solving the inverse kinematics of nonredundant and redundant wrists
No full textDirect 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
Systematic procedure for the identification of dynamic parameters of robot manipulators
No full textIn this paper a complete and systematic procedure for the identification of the dynamic parameters of rigid robot manipulators is presented. Starting from the basic results on the subject present in the literature and on a new technique to find exciting trajectories for the estimation, the procedure is developed. A set of algorithms is provided for the implementation of the various steps of the procedure for a generic open-chain structure. The algorithms have been coded in the popular Matlab/Maple environment and the procedure has been tested in a practical case study to identify the dynamic parameters of a six-degree-of-freedom conventional industrial robot
Energy-based identification of dynamic parameters for a conventional industrial manipulator
No full textExperiments of feedforward control on a conventional industrial manipulator
No full textIn this paper, feedforward model-based control is experimented on a conventional industrial manipulator, the SMART-3 6.12R by COMAU. Despite of the fact that the conditions for the experiments are far from those provided by research set-ups, the obtained results confirm that it is worth using feedforward compensation control even on an industrial set-up
Identification of dynamic parameters and feedforward control for a conventional industrial manipulator
No full textDynamic compensation control algorithms can improve the performance of conventional industrial manipulators if an accurate dynamic model is available. Usually, the structure of the dynamic model is known but the actual values of the dynamic parameters are either unknown or not accurately known. It is thus required to perform an identification of these parameter using available algorithms. In this paper, feedforward model-based control is experimented on a conventional industrial robot, the SMART-3 6.12R by COMAU, based on a dynamic parameter identification. Despite the fact that the conditions for the experiments are far from those provided by research set-ups, the obtained results have confirmed that it is worth using feedforward compensation control, either in a complete or in a partial form, even on an industrial set-up
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
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
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