1,721,039 research outputs found
Coordinate transformation - A solution algorithm for one class of robots
No full textOne of the most important features of an advanced control system for articulated robots is the capability of transforming the work space coordinates, which naturally characterize any robot task, into the corresponding joint coordinates, on which control actions are developed. For each task, the coordinate transformation problem consists in calculating one trajectory in the joint space which corresponds to the end effector trajectory, usually given in the Cartesian space. While simple kinematical structures allow for closed-form solutions, there is a class of robots for which this is not true. Typical articulated robot structures have three revolute joints at the end effector; the geometric parameters of these joints actually determine the spatial configuration of the last axes of motion. The large majority of today's nonredundant structures have three intersecting axes at the end effector, and closed form solutions do exist in this case. If the axes intersect two-by-two, as in some rather common arm design, an exact solution seems not to exist. A quite different solution algorithm is established, as compared to the trigonometric approach widely adopted so far, which yields solutions in case of two-by-two intersecting axes. The convergence of the algorithm along any trajectory is proved. Effectiveness of the proposed technique can be argued by the fact that it only makes use of direct kinematics, thus resulting in a contained computational burden. A robot prototype of the kind described above is taken as a reference in order to discuss digital implementation and develop numerical examples
Augmented task space approach for redundant manipulator control
No full textRedundant manipulators are currently receiving a considerable interest in the robotics research community. The extra (redundant) degree-of-freedom's (DOF's) in a structure which is redundant with respect to a given task can be used to obtain a more versatile configuration in terms of the interaction of the structure with the environment. Two approaches are commonly followed to control robotic manipulators. In this work it is shown how redundant manipulators, according to the above two approaches, are controlled
A computational technique for solving robot end-effector trajectories into joint trajectories
No full textA typical robot task is specified as a trajectory assigned to the end-effector. The solution must be a joint trajectory, which constitutes the reference input to the joint control servos. An approach is presented that is applicable to any robot structure with a kinematic equation and Jacobian that are known. The idea is to reformulate the inverse kinematic problem as a tracking problem for a simple dynamic system. As an example, the proposed inverse kinematic algorithm is applied to the first three degrees of freedom of a PUMA robot
Lagrange and Newton-Euler dynamic modeling of a gear-driven robot manipulator with inclusion of motor inertia effects
No full textThis paper is aimed at presenting the dynamic model of a gear-driven rigid robot manipulator. The dynamic effects of the motion of the motors driving the joints through gears are analyzed. A complete model is derived using the Lagrange formulation in which the contributions of rotor inertias and rotor-link interactions are evidenced. The resulting equations of motion are shown to be linear in terms of a suitable set of dynamic parameters for the augmented links (links with motors). These are utilized for model derivation using the recursive Newton-Euler formulation. The explicit dynamic model far an elbow manipulator is developed
Control of Robotic Systems Through Singularities
No full textThe goal of this work is to provide an overview of major control techniques that manage the occurrence of singularities for robotic systems. The common feature of these methods is a modification of the inverse differential kinematic mapping which is ill-conditioned in the neighbourhood of a singularity. The following solutions are discussed; namely, the Jacobian transpose, the Jacobian pseudoinverse, and the damped least-squares Jacobian inverse
Robotica – Modellistica, Pianificazione e Controllo
No full textQuesto libro si pone in continuità con le due precedenti edizioni del testo di Robotica Industriale, a firma dei primi due autori, di cui mantiene l'obiettivo didattico di coniugare gli aspetti fondamentali e tecnologici con quelli innovativi attraverso una presentazione formalmente rigorosa. I primi sei capitoli del testo riguardano la teoria delle strutture di manipolazione (con la trattazione della cinematica, della statica e della pianificazione di traiettorie) e la tecnologia degli attuatori, dei sensori e dell'unità di governo di un robot; gli altri sei capitoli approfondiscono la dinamica e il controllo del moto dei manipolatori, l'interazione con l'ambiente con l'uso di informazioni sensoriali esterocettive (forza e visione), i robot mobili e la pianificazione del moto. Completano il volume cinque appendici che forniscono una base di conoscenza omogenea a studenti di diversa estrazione. L'organizzazione degli argomenti, presentati con un crescente livello di difficoltà, consente l'adozione del libro come testo di riferimento sia per un corso al terzo anno delle lauree di primo livello in ingegneria automatica, elettronica, gestionale, informatica e meccanica, sia per un corso delle corrispondenti lauree di secondo livello, o anche per corsi monografici a livello dottorale
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