摘要:

AbstractA major difficulty that has haunted most researchers in the process of optimal redundancy resolution of robotic manipulators is the instability observed in even very simple numerical simulations. This numerical instability is not related to the structurally singular configurations of the manipulators, and in the literature has been referred to as “algorithmic singularity,” “artificial singularity,” or “unavoidable singularity.” In this work, conditions on both structural and algorithmic singularities are studied based on the Singular Value Decomposition of the Jacobian matrix, and, hence, a singularity‐free control algorithm for redundant manipulators is developed and resolved as the Lagrange problem of optimal control. It is shown that many well‐known methods for optimal redundant manipulation in the literature, including the Extended Jacobian Technique, most of constraint function‐based methods, and most of the previously reported methods on global optimization techniques, are all special cases of the formulation provided here. Further, the necessary conditions of the global optimality for this general formulation are derived in explicit form and the source of “algorithmic singularity” is rigorously identified and resolved. © 299

ISSN:0741-2223    

DOI:10.1002/rob.4620120702

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThis article discusses the application of orthogonal neural networks to detect collisions between multiple robot manipulators that work in an overlapped space. By applying an expansion/shrinkage algorithm, the problem of collision detection between arms is transformed into that among cylinders (or rectangular solids) and line segments. This mapping simplifies the collision detection problem and thus neural networks can be applied to solve it. The property of parallel processing enables neural networks to detect collisions rapidly. A single‐layer orthogonal neural network is developed to avert the problems of conventional multilayer feedforward neural networks such as initial weights and the number of layers and processing elements. This orthogonal neural network can approximate various functions and is used to calculate forward solution and to detect collisions. An efficient neural network system for collision detection is also developed. © 1995 John Wiley&Sons, I

ISSN:0741-2223    

DOI:10.1002/rob.4620120703

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThis article introduces and draws a comparison on B‐splines and clothoids for generating fine‐grained, smooth path specifications as applied to mobile robot path planning. At one level, a sequence of objective points that the robot must attain to avoid obstacles and to progress toward its goal are supplied by a coarse path planner. Using B‐spline and clothoid curves, these objective points are converted into a path of finer detail, as requisite to a robot driving controller/tracker. Through experimental results with the Navlabll, a mobile robot vehicle at Carnegie Mellon University (CMU), we differentiate the advantages of this approach over conventional poly‐line fit/round corner used to date. © 2995 John Wiley&S

ISSN:0741-2223    

DOI:10.1002/rob.4620120704

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThis article deals with the subject of increasing the positioning accuracy of a manipulator beyond what is typically obtained via Denavit‐Hartenberg (D‐H) calibration. It is commonly accepted that one method for accomplishing this requires including “extra” terms (such as static deflection) in the D‐H model. Another technique, which is experimentally verified and quantified in this article, is that of local calibration. Rather than continually introducing more and more modeling terms, we restrict the workvolume of the manipulator. One contribution of this article is an experimental investigation of local calibration. Most data indicates that local calibration offers advantages and it quantifies that the approximate improvement on one particular PUMA 560 robot is as much as four times better than global calibration. Some data indicates that it is not always true that “localizing” the calibration is an improvement. The article also discusses the problem of recognizing bad calibration data. We demonstrate a technique for identifying and removing “bad” data. Finally, the article shows that the locality of workvolume must include a consideration of the joint motions as well. For example, it presents results when data is taken with the arm in a single configuration, and in multiple configurations. © 1995 Jo

ISSN:0741-2223    

DOI:10.1002/rob.4620120705

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0741-2223    

DOI:10.1002/rob.4620120701

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY