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Robotics and Automation, IEEE Transactions on

Issue 2 • Date April 2000

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Displaying Results 1 - 10 of 10
  • Part orientation with one or two stable equilibria using programmable force fields

    Page(s): 157 - 170
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    Programmable force fields are a representation of a class of devices for distributed, nonprehensile manipulation for applications in parts feeding, sorting, positioning, and assembly. They generate force vector fields in which the parts move until they reach a stable equilibrium pose. Research has yielded open-loop strategies to uniquely position, orient, and sort parts. These strategies typically consist of several fields employed in sequence to achieve a desired final pose. The length of the sequence depends on the complexity of the part. We show that unique part poses can be achieved with just one field. First, we exhibit a single field that positions and orients any part (except certain symmetric parts) into two stable equilibrium poses. Then, we show that for any part there exists a field in which the part reaches a unique stable equilibrium pose (again, except for symmetric parts). Besides giving an optimal upper bound for unique parts positioning and orientation, our work gives further evidence that programmable force fields are a powerful tool for parts manipulation. Our second result also leads to the design of "universal parts feeders", proving an earlier conjecture about their existence. We argue that universal parts feeders are relatively easy to build, and we report on extensive simulation results which indicate that these devices may work very well in practice. We believe that the results in this paper could be the basis for a new generation of efficient, open-loop, parallel parts feeders. View full abstract»

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  • Dynamics computation of structure-varying kinematic chains and its application to human figures

    Page(s): 124 - 134
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    This paper discusses the dynamics computation of structure-varying kinematic chains which imply mechanical link systems whose structure may change from open kinematic chain to closed one and vice versa. The proposed algorithm can handle and compute the dynamics and motions of any rigid link systems in a seamless manner without switching among algorithms. The computation is developed on the foundation of the dynamics computation algorithms established in robotics, which is superior in efficiency due to explicit use of the generalized coordinates to those used in the general-purpose motion analysis softwares. Although the structure-varying kinematic chains are commonly found in computing human and animal motions, the computation of their dynamics has not been discussed in literature. The developed computation will provide a general algorithm for the computation of motion and control of humanoid robots and computer graphics human figures View full abstract»

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  • Programming and control of robots by means of differential algebraic inequalities

    Page(s): 135 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    The method of programmed constraints has recently been proposed as an executable specification language for robot programming. The mathematical structures behind such problems are viability problems for control systems described by ordinary differential equations (ODE) subject to user-defined inequality constraints. This paper describes a method for the numerical solution of such problems, improving and extending some of our previous results. The algorithm presented is composed of three parts: delay-free discretization, local control, and local planning. Delay-free discretizations are consistent discretizations of control systems described by ODEs with discontinuous inputs. The local control is based on the minimization of an artificial, logarithmic barrier potential function. Local planning is a computationally inexpensive way to increase the robustness of the solution procedure, making it a refinement to a strategy based on viability alone. Simulations of a mobile robot are used to demonstrate the proposed strategy. Some complementarity is shown between the programmed-constraints approach to robot programming and optimal control. Moreover, we demonstrate the relative efficiency of our algorithm compared to optimal control: Typically, our method is able to find a solution on the order of 100 times faster than an optimal-control solver View full abstract»

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  • Design and implementation of an adaptive process planner for disassembly processes

    Page(s): 171 - 179
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    This paper presents a methodology for designing and implementing disassembly plans and processes using Petri nets (PN) for remanufacturing obsolete products. Process modeling and planning using PN are discussed. The proposed PN accommodate product topology and precedence relations during disassembly. Decision values are attached to PN to enable consideration of uncertainty during process execution. The resulting planner guarantees the plan's optimality when product remanufacturing parameters are known. In cases of uncertainty about product parameters, an adaptation scheme is designed and implemented to facilitate the goal of maximum benefit. Three planning and execution algorithms (globally fixed, limited adaptive, adaptive) are presented for disassembly processes. They are demonstrated comprehensively through a robotic disassembly system, and its use is demonstrated in disassembly of a car radio View full abstract»

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  • Intelligent organization for flexible manufacturing

    Page(s): 180 - 189
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    Intelligent production scheduling has been viewed as a problem-solving task that involves the generation of a suitable schedule among different ones using learning techniques. This work presents a unified model for a class of intelligent machines, suitable for flexible manufacturing systems, in which each alternative production plan comprises a fixed number of sequential steps, and the task is to select the optimal plan as more experience is obtained during the operation of the system. This model, based on the theory of hierarchically intelligent control systems developed by Saridis (1995), combines the powerful high-level decision making with advanced mathematical modeling and synthesis techniques of system theory and methods of dealing with imprecise or incomplete environment information View full abstract»

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  • Algebraic synthesis of efficient deadlock avoidance policies for sequential resource allocation systems

    Page(s): 190 - 195
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    Deadlock avoidance in sequential resource allocation systems is a well-defined problem in discrete event system literature, as it underlies the operation of many contemporary technological systems. In the past, the problem has been studied by means of a number of formal frameworks, including the finite-state automata (FSA) and Petri nets (PNs). In this paper, it is shown that a significant class of deadlock avoidance policies (DAPs), known as algebraic polynomial kernel (PK)-DAPs, originally developed in the FSA paradigm, can be analyzed using recent results from PN structural analysis. Furthermore, the approach to DAP analysis and design taken in this paper has led to the effective generalization of the currently available algebraic PK-DAPs, and to their enrichment with new and more flexible policy implementations View full abstract»

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  • The eigenscrew decomposition of spatial stiffness matrices

    Page(s): 146 - 156
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    A manipulator system is modeled as a kinematically unconstrained rigid body suspended by elastic devices. The structure of spatial stiffness is investigated by evaluating the stiffness matrix “primitives”-the rank-1 matrices that compose a spatial stiffness matrix. Although the decomposition of a rank-2 or higher stiffness matrix into the sum of rank-1 matrices is not unique, one property of the set of matrices is conserved. This property, defined as the stiffness-coupling index, identifies how the translational and rotational components of the stiffness are related. Here, we investigate the stiffness-coupling index of the rank-1 matrices that compose a spatial stiffness matrix. We develop a matrix decomposition that yields a set of rank-1 stiffness matrices that identifies the bounds on the stiffness-coupling index for any decomposition. This decomposition, referred to as the eigenscrew decomposition, is shown to be invariant in coordinate transformation. With this decomposition, we provide some physical insight into the behavior associated with a general spatial stiffness matrix View full abstract»

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  • Hyperbolic normal forms for manipulator kinematics

    Page(s): 196 - 201
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    We study the kinematics of robotic manipulators around singular configurations of Corank 1. Sufficient conditions are derived under which the kinematics become equivalent to a hyperbolic normal form. These conditions are illustrated with examples of nonredundant and redundant manipulator kinematics. New normal forms provide a better understanding of the singular behavior of robotic manipulators and are instrumental in solving the singular inverse kinematic problem within the normal form approach View full abstract»

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  • A brachiating robot controller

    Page(s): 109 - 123
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    We report on our empirical studies of a new controller for a two-link brachiating robot. Motivated by the pendulum-like motion of an ape's brachiation, we encode this task as the output of a “target dynamical system”. Numerical simulations indicate that the resulting controller solves a number of brachiation problems that we term the “ladder”, “swing-up”, and “rope” problems. Preliminary analysis provides some explanation for this success. The proposed controller is implemented on a physical system in our laboratory. The robot achieves behaviors including “swing locomotion” and “swing up” and is capable of continuous locomotion over several rungs of a ladder. We discuss a number of formal questions whose answers will be required to gain a full understanding of the strengths and weaknesses of this approach View full abstract»

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Aims & Scope

This Transactions ceased production in 2004. The current retitled publications areIEEE Transactions on Automation Science and Engineering and IEEE Transactions on Robotics.

Full Aims & Scope