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Robotics and Automation, IEEE Transactions on

Issue 6 • Date Dec. 2003

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Displaying Results 1 - 14 of 14
  • Workspace analysis and optimal design of a 3-leg 6-DOF parallel platform mechanism

    Page(s): 954 - 966
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (988 KB)  

    A new class of six-degree-of-freedom (DOFs) spatial parallel platform mechanism is considered in this paper. The architecture consists of a mobile platform connected to the base by three identical kinematic chains using five-bar linkages. Recent investigations showed that parallel mechanisms with such a topology for the legs can be efficiently statically balanced using only light elastic elements. This paper follows up with a workspace analysis and optimization of the design of that parallel mechanism. More specifically, considering a possible industrial application of the architecture as a positioning and orienting device of heavy loads, an optimization procedure for the maximization of the volume of the three-dimensional (3-D) constant-orientation workspace of the mechanism is first presented. As the mechanism could also have great potential as a motion base for flight simulators, we develop here a discretization method for the computation and graphical representation of a new workspace with coupled translational and rotational DOFs. This workspace can be defined as the 3-D space which can be obtained when generalized coordinates x,y and torsion angle ψ in the tilt-and-torsion angles parametrization are constant. A second procedure is then presented for the maximization of the volume of this second subset of the complete workspace. For both approaches, our purpose is to attempt an optimal design of the mechanism by maximizing the volume of the associated 3-D Cartesian region that is free of critical singularity loci. View full abstract»

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  • Inverse dynamics based control system for a three-degree-of-freedom flexible arm

    Page(s): 1007 - 1014
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (567 KB) |  | HTML iconHTML  

    This article describes a new control scheme designed for a three-degree-of-freedom flexible arm. This arm has been built with light links, has most of its mass concentrated at the tip, and uses a special mechanical configuration to approximately decouple tip motions in spherical coordinates. This configuration facilitates the dynamic modeling and control of the arm. A compliance matrix can be used to model the oscillations of the structure. A consequence of this simple dynamic is that minimum sensing effort is required (only direct motor and tip measurements), and the use of complex observers is avoided because the state of the system can be very easily obtained from these measurements. A two-nested control-loop scheme is used to control the tip position by using joint position and tip acceleration feedbacks. The stability of the controlled system is analytically proven in the case of perfect dynamic modeling. Then, an analysis of stability in the case of modeling errors is carried out, and conditions for local stability are derived. Experimental results are presented for the cases of perturbation control and trajectory tracking. Comparative results between controlled and noncontrolled tip responses are also shown. View full abstract»

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  • Distributed performance evaluation of a controlled IC fab

    Page(s): 1027 - 1033
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (525 KB) |  | HTML iconHTML  

    Integrated circuit (IC) foundry fabs are difficult to model due to the increasing product mixes and flexible routes. An imprecise fab model cannot be used to evaluate fab performance or estimate product cycle time. The distributed colored timed Petri net (DCTPN) is a type of high-level Petri net with embedded entity attribute, time, communication, and remote object invocation properties that contribute to realistic descriptions, distributed modeling, and manufacturing execution system integration. Furthermore, the resource-oriented DCTPN modeling extends product mix and flexible route modeling capabilities. The DCTPN conflict resolution and token competition rules are used to construct the dispatching system for a controlled IC fab. A simplified 200 mm IC fab with six functional areas is discussed and demonstrated based on different control policies. View full abstract»

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  • Dynamic sliding PID control for tracking of robot manipulators: theory and experiments

    Page(s): 967 - 976
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (756 KB)  

    For a class of robot arms, a proportional-derivative (PD) controller plus gravity compensation yields the global asymptotic stability for regulation tasks, and some proportional-integral-derivative (PID) controllers guarantee local regulation without gravity cancellation. However, these controllers cannot render asymptotic stability for tracking tasks. In this paper, a simple decentralized continuous sliding PID controller for tracking tasks that yields semiglobal stability of all closed-loop signals with exponential convergence of tracking errors is proposed. A dynamic sliding mode without reaching phase is enforced, and terminal attractors, as well as saturated ones, are considered. A comparative experimental study versus PD control, PID control, and adaptive control for a rigid robot arm validates our design. View full abstract»

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  • Continuous-time restless bandit and dynamic scheduling for make-to-stock production

    Page(s): 977 - 990
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (957 KB)  

    We study the "Whittle relaxation" version of the continuous time, discrete, and continuous state space Restless Bandit problem under the discounted cost criterion. Explicit expressions of Whittle's priority indexes, which generalize the Gittins indexes, are derived. This formalism is then used in the context of flexible make-to-stock production to construct dynamic scheduling rules. These analytical results are finally compared with the optimal numerically derived policy, obtained for a server delivering two product types. It is observed that the Whittle relaxation version of the Restless Bandit model nearly yields optimal dynamic scheduling rules. View full abstract»

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  • Output regulation of robot manipulators with a constantly revolving arm

    Page(s): 1002 - 1006
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    This paper presents analysis and experiment results on regulation of a two-link robot with a constantly revolving arm. The rotating member imposes a harmonic excitation on the system. A control algorithm inspired by passive dynamic vibration absorber is devised to turn the base link to a target position asymptotically. The displacement of the base link is the only state variable required in the feedback loop. Asymptotic stability is proved using a tool based on the center manifold theory. Real-time experiments are conducted to verify the performance of the proposed method. View full abstract»

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  • Using manipulability to bias sampling during the construction of probabilistic roadmaps

    Page(s): 1020 - 1026
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (687 KB) |  | HTML iconHTML  

    Probabilistic roadmaps (PRMs) are a popular representation used by many current path planners. Construction of a PRM requires the ability to generate a set of random samples from the robot's configuration space, and much recent research has concentrated on new methods to do this. In this paper, we present a sampling scheme that is based on the manipulability measure associated with a robot arm. Intuitively, manipulability characterizes the arm's freedom of motion for a given configuration. Thus, our approach is to densely sample those regions of the configuration space in which manipulability is low (and therefore, the robot has less dexterity), while sampling more sparsely those regions in which the manipulability is high. We have implemented our approach, and performed extensive evaluations using prototypical problems from the path planning literature. Our results show this new sampling scheme to be effective in generating PRMs that can solve a large range of path planning problems. View full abstract»

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  • Exact solution and infinite-dimensional stability analysis of a single flexible link in collision

    Page(s): 1015 - 1020
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    There is an increasing interest in examining the use of flexible link manipulators in tasks where there is contact with the environment. Presently, there has been limited work examining the stability of force control strategies for such manipulators, especially in the case where there is a switching transition between the unconstrained and constrained environments. In this paper, the modeling and stability of a single flexible link under proportional derivative control contacting an environment is studied. Intuitively, since the system only has passive elements, one would expect the system to be stable. With a few very reasonable assumptions, the problems associated with finite-dimensional approximations are solved by using a novel infinite-dimensional approach. The resultant infinite-dimensional switching system is shown to be asymptotically stable using an energy-based method. View full abstract»

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  • A hybrid scheduling and control system architecture for warehouse management

    Page(s): 991 - 1001
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (983 KB) |  | HTML iconHTML  

    In recent years, the hybrid control framework has received attention from the research community. Variations of this control framework are available in the literature. In this paper, a hybrid intelligent agent-based scheduling and control system architecture is presented for an actual industrial warehouse order-picking problem, where goods are stored at multiple locations and the pick location of goods can be selected dynamically in near-real time. The presented architecture includes a higher level optimizer, a middle-level guide agent, and lower level agents. The need for a higher level optimizer and communication between higher and lower level controllers is demonstrated. A mathematical model and a genetic algorithm for the resource assignment problem are presented. Simulation results demonstrating efficiency of the new approach are also presented. View full abstract»

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  • Grasp analysis and synthesis based on a new quantitative measure

    Page(s): 942 - 953
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1226 KB) |  | HTML iconHTML  

    In this paper, we present a quantitative measure of multifingered grasps. The measure quantifies the capability of a grasp in firmly holding an object while resisting external loads and/or disturbances. It can also be used for qualitative test of closure properties (form closure and force closure). For planar grasps and frictionless three-dimensional (3-D) grasps, the quantitative measure can be computed efficiently by solving a set of linear programs, while for frictional 3-D grasps, it can be computed by solving nonlinear programs without linearization of the friction cone. By using the proposed quantitative measure, an algorithm for grasp synthesis on polygonal objects is developed. Rather than producing a single grasp configuration, the algorithm computes all grasps on a polygon that satisfy quantitative constraints, i.e., the value of the quantitative measure is greater than a predetermined positive constant. The approach has potential application in grasp planning with multiple optimality criteria. View full abstract»

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  • A decentralized approach to formation maneuvers

    Page(s): 933 - 941
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (645 KB) |  | HTML iconHTML  

    This paper presents a behavior-based approach to formation maneuvers for groups of mobile robots. Complex formation maneuvers are decomposed into a sequence of maneuvers between formation patterns. The paper presents three formation control strategies. The first strategy uses relative position information configured in a bidirectional ring topology to maintain the formation. The second strategy injects interrobot damping via passivity techniques. The third strategy accounts for actuator saturation. Hardware results demonstrate the effectiveness of the proposed control strategies. View full abstract»

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  • List of reviewers

    Page(s): 1034 - 1037
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    Freely Available from IEEE
  • Author index

    Page(s): 1038 - 1042
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    Freely Available from IEEE
  • Subject index

    Page(s): 1042 - 1050
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    Freely Available from IEEE

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