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Robotics and Automation, IEEE Transactions on

Issue 3 • Date June 1995

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Displaying Results 1 - 21 of 21
  • Comments on "A practical approach to job shop scheduling problems" [with reply]

    Page(s): 469 - 470
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    The author states that, in the original paper (D.L. Hoitomt and P.B. Luh ibid., vol. 9, no. 1, p. 1-13, 1993), the model formulation of the scheduling problem is highly irregular. If one were to consider the formulation by itself it would seem that since neither the precedence nor processing time constraints are linked to time, we could set all /spl delta//sub ijkh/=0 and obtain a feasible solution with jobs overlapping on machines. It is noted that in the subsequent relaxation of the capacity constraint, the binary variables have been set to 1 from start to finish time of the corresponding operation to account for capacity. The need for the model formulation to include such constraints explicitly is discussed, and the original authors discuss the relevance of the comments. The existence of related and similar results in previous works is also considered.<> View full abstract»

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  • Comments on "A sliding mode controller with bound estimation for robot manipulators"

    Page(s): 471 - 473
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB)  

    In the above paper by Su-Leung (IEEE Trans. Robot Automat., vol.9, no.2, p.208-14 (1993)), an adaptive sliding mode control scheme for the trajectory control of robot manipulators is developed. The proof of Theorem 1 in the paper is accomplished by resorting to the Lasalle theorem. It is well known that the Lasalle theorem can be applied to either autonomous systems or periodic nonautonomous systems, but it is not applicable to general nonautonomous systems. The Lasalle theorem is not applicable to the manipulator tracking control system given in the paper because the tracking control system considered in the paper is neither an autonomous system nor a periodic nonautonomous system but it can be classified into general nonautonomous systems. Therefore, the proof of Theorem 1 in the paper is not correct.<> View full abstract»

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  • A new adaptive control algorithm for robot manipulators in task space

    Page(s): 457 - 462
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    Adaptive control of robotic manipulators in task space coordinates is considered in this paper. A new composite adaptive control law, which uses the prediction error and tracking error to drive parameter estimation, is developed based on sliding mode and a general Lyapunov-like concept. It is shown that global stability and convergence can be achieved for the adaptive control algorithm. The algorithm has the advantage that inverse of Jacobian matrix and the bounded inverse of the estimated inertia matrix are not required. The algorithm is further modified so as to achieve robustness to bounded disturbances. A simulation example is provided to demonstrate the performance of the proposed algorithm View full abstract»

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  • A note on “On single-scanline camera calibration” [and reply]

    Page(s): 470 - 471
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    In this correspondence, the single-scanline camera model proposed in the original paper (R. Horaud, R. Mohr and B. Lorecki, ibid., vol. 8, no. 1, p. 71-5, 1993) is modified to include a lens distortion coefficient. The authors say that, by this modification, the calibration approach presented will become more practical. The original authors accept that the improvement is sensible but say that the argument is not rigorous and suggest better approaches to some aspects View full abstract»

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  • Learning control for robot tasks under geometric endpoint constraints

    Page(s): 432 - 441
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (812 KB)  

    A learning control scheme for a class of robot manipulators whose endpoint is moving under geometrical constraints on a surface is proposed. In this scheme, the input torque command is composed of two different signals updated separately at every trial by different ways. One is updated by the angular velocity error vector which is projected to the tangent plane of the constraint surface in joint space. The other is updated by the magnitude of contact force error at the manipulator endpoint. Not only the uniform boundedness of position and velocity trajectory errors but also the uniform convergence of position and velocity trajectories to their desired ones with repeating practices are proved theoretically. In addition, it is shown that the contact force itself converges to the desired one in the sense of L2-norm with repeating practices. Computer simulation results by using a 3 DOF manipulator are presented to demonstrate the effectiveness of the proposed method and to examine the speed of convergence of force trajectories besides position and velocity trajectories View full abstract»

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  • Synthesis using resource control nets for modeling shared-resource systems

    Page(s): 317 - 327
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (908 KB)  

    This paper proposes a general approach to synthesize a class of Petri nets that model shared-resource automated manufacturing systems. The approach imposes minimal restrictions on the interactions among subsystems initially so that the modeler is given significant freedom. To modularize the synthesis procedure, a shared-resource system is formulated from the processes. i.e., the subsystems, that control the system resources and the interactions among the processes. For modeling the processes. Resource control nets are defined as the basic generic modules. Then, the system model is built by merging these modules through their common transitions and common transition subnets, which denote the interactions among the processes. The merged net is proven to be conservative and thus bounded. An algorithm is also developed to check two sufficient conditions for structural liveness of the net. This algorithm examines only the net's structure, and appears to be more efficient than state enumeration techniques such as the reachability graph method View full abstract»

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  • Primitives for smoothing mobile robot trajectories

    Page(s): 441 - 448
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    Clothoids are very useful for smoothing the motion of a mobile robot moving along a trajectory. This paper addresses the problem of smoothing mobile robot motions when cusps, i.e., changes of motion direction along the trajectory, are imposed. We pinpoint some special curves (that we call “anticlothoids”) and we discuss how they can be used together with clothoids in order to smooth a predefined trajectory View full abstract»

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  • Parallel O(log N) algorithms for computation of manipulator forward dynamics

    Page(s): 389 - 400
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1060 KB)  

    These parallel algorithms described are based on a new O(N) solution to the problem. The underlying feature of this O(N) method is a different strategy for decomposition of interbody force which results in a new factorization of mass matrix (M). Specifically, a factorization of inverse of the mass matrix in the form of Schur complement is derived as M-1=C-DtA-1B wherein A, B, and C are block tridiagonal matrices. The new O(N) algorithm is then derived as a recursive implementation of this factorization of M-1. It is shown that the resulting algorithm is strictly parallel. Strategies for multilevel exploitation of parallelism in the computation are also discussed, resulting in more efficient parallel O(log N) algorithms. The parallel algorithms developed in this paper, in addition to their theoretical significance, are also important from a practical implementation standpoint due to their simple architectural requirements View full abstract»

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  • Hybrid adaptive/robust motion control of rigid-link electrically-driven robot manipulators

    Page(s): 426 - 432
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    In this paper a hybrid adaptive/robust control scheme is proposed for rigid-link electrically-driven robot manipulators in the presence of arbitrary uncertain inertia parameters of the manipulator and the electrical parameters of the actuators. In contrast to the known methods, the presented design requires at most the joint velocity feedback and does not rely on the knowledge of the bounds of complexity functions. Semi-global asymptotic stability of the adaptive/robust controller is established in the Lyapunov sense. Simulation results are included to demonstrate the tracking performance View full abstract»

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  • Minimal linear combinations of the inertia parameters of a manipulator

    Page(s): 360 - 373
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB)  

    This paper deals with the problem of identifying the inertia parameters of a manipulator. We begin by introducing the terminology of minimal linear combinations (MLC's) of the inertia parameters that are linearly independent of one another and determine the manipulator dynamics while keeping the number of linear combinations of the inertia parameters to a minimum. The problem is then to find an identification procedure for estimating the MLC's and to use the MLC's in the inverse dynamics for control. The recursive Newton-Euler formulation is rederived in terms of the MLC's. The resulting formulation is almost as efficient as the most efficient formulation in the literature. This formulation also provides a starting point from which to derive a recursive identification procedure. The identification procedure is simple and efficient, since it does not require symbolic closed-form equations and it has a recursive structure. The three themes concerning the dynamic modeling of a manipulator $the MLC's, the inverse dynamics in terms of the MLC's, and the identification procedure - are treated in sequence View full abstract»

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  • Inertial navigation systems for mobile robots

    Page(s): 328 - 342
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1164 KB)  

    A low-cost solid-state inertial navigation system (INS) for mobile robotics applications is described. Error models for the inertial sensors are generated and included in an extended Kalman filter (EKF) for estimating the position and orientation of a moving robot vehicle. Two different solid-state gyroscopes have been evaluated for estimating the orientation of the robot. Performance of the gyroscopes with error models is compared to the performance when the error models are excluded from the system. Similar error models have been developed for each axis of a solid-state triaxial accelerometer and for a conducting-bubble tilt sensor which may also be used as a low-cost accelerometer. An integrated inertial platform consisting of three gyroscopes, a triaxial accelerometer and two tilt sensors is described View full abstract»

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  • Computation of configuration-space obstacles using the fast Fourier transform

    Page(s): 408 - 413
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    This paper presents a new method for computing the configuration-space map of obstacles that is used in motion-planning algorithms. The method derives from the observation that, when the robot is a rigid object that can only translate, the configuration space is a convolution of the workspace and the robot. This convolution is computed with the use of the fast Fourier transform (FFT) algorithm. The method is particularly promising for workspaces with many and/or complicated obstacles, or when the shape of the robot is not simple. It is an inherently parallel method that can significantly benefit from existing experience and hardware on the FFT View full abstract»

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  • Generalized inverse kinematic functions for the Puma manipulators

    Page(s): 404 - 408
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    This paper presents a new approach for the computation of generalized positioning inverse kinematic functions for Puma manipulators. This new approach leads to real solutions of the joint variables for any set of Cartesian coordinates located inside or outside the robot's workspace. Therefore, the inverse kinematic functions derived are termed “generalized inverse kinematic functions”. These solutions, which produce the minimum distance between the end effector and a Cartesian point to be reached, are particularly useful in tracking operations. Because of the special architecture of the Puma, closed-form solutions are obtained. This leads to simple algorithms and allows for the computation of all solutions View full abstract»

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  • Gravitational stability of frictionless assemblies

    Page(s): 374 - 388
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1296 KB)  

    The stability of an assemblage of contacting rigid bodies without friction is investigated. A method is presented for finding an orientation of the assembly so that the assembly remains motionless under gravity. If no stable orientation exists for an assembly, the method finds the “least” unstable orientation. The metric used to measure stability is based on the second time-rate of change of the gravitational potential energy, and the desired orientation for an assembly is expressed in terms of an optimization problem involving changes in potential energy. The problem of finding stable or maximally-stable orientations is formulated as a constrained maximin problem. The maximin problem is shown to be a variant of standard zero-sum matrix games, and can be solved using linear programming. The method is the first general method for automatically determining stable orientations. Example assemblies are presented View full abstract»

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  • Closed-loop kinematic calibration of the RSI 6-DOF hand controller

    Page(s): 352 - 359
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    A method is presented for autonomous kinematic calibration of the RSI 6-DOF hand controller, a two-loop parallel mechanism comprised of three 6-DOF arms with potentiometers on the first three joints of each arm. This double closed-loop kinematic calibration method is an adaptation of a previously developed single closed-loop method. The kinematic parameters identified are the joint angle offsets and the joint angle gains. Experimental results are presented and compared to results using a special calibration fixture View full abstract»

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  • Time-minimum routes in time-dependent networks

    Page(s): 343 - 351
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    Route planning for mobile robots in time-dependent networks is investigated. The mobile robot is constrained to move in a prespecified network of roads. The environment contains a set of moving obstacles which are not necessarily constrained to move along arcs of the network and whose motions are assumed to be known. Due to dynamic objects in the environment, connectivity in the network changes over time, i.e., the network is time-dependent. Given such an environment, a method is presented to find a collision-free route in the network that takes the mobile robot from a given start node to a destination node in minimum time. Our method generates a time-minimum path for all time intervals during which the destination node is reachable. The problem is solved by a two-level graph search: (1) path search using a space-time spanning tree, and (2) path search in a time-dependent network. Algorithms for the two subproblems are presented and execution time of the algorithms is analyzed View full abstract»

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  • A normal form of singular kinematics of robot manipulators with smallest degeneracy

    Page(s): 401 - 404
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    We study singular kinematics of robot manipulators around internal configurations at which the manipulator Jacobian drops rank by 1. Conditions are presented under which such kinematics can be transformed to a simple quadratic normal form. The conditions are proved using standard methods of singularity theory, and illustrated with an example View full abstract»

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  • Real-time collision avoidance for redundant manipulators

    Page(s): 448 - 457
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    This paper presents a simple and robust approach to achieving collision avoidance for kinematically redundant manipulators at the control-loop level. The proposed scheme represents the obstacle avoidance requirement as inequality constraints in the manipulator workspace, and ensures that these inequalities are satisfied while the end-effector tracks the desired trajectory. The control scheme is the damped-least-squares formulation of the configuration control approach implemented as a kinematic controller. Computer simulation and experimental results are given for a Robotics Research 7 DOF redundant arm and demonstrate the collision avoidance capability for reaching inside a truss structure. These results confirm that the proposed approach provides a simple and effective method for real-time collision avoidance View full abstract»

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  • Robot manipulability

    Page(s): 462 - 468
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    This paper demonstrates fundamental problems with dexterity measures found throughout the robotics literature and offers a methodology for correcting those problems. Measures of robot dexterity derived from eigenvalues, eigenvectors, similarity transformations, singular-value decompositions and the Moore-Penrose inverse of the manipulator Jacobian do not have invariant physical meaning. The paper presents manipulability ellipsoids and manipulability screw-subspaces for both redundant and nonredundant manipulators View full abstract»

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  • Local optimization of weighted joint torques for redundant robotic manipulators

    Page(s): 422 - 425
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    In this article, stable local solutions with global characteristics are developed for the weighted joint torque optimization in redundant manipulator. Conditions for these symmetric weight matrices are found that can guarantee that the local optimization of joint torque weighted by these matrices will have the same stability and optimality as the local optimization for the inertia inverse weighted joint torque. The symbolic results of the weighted projection operator of Jacobian matrix are also derived. It is also proposed that the weight matrix plays an important role in avoiding instabilities by relating the null space of the Jacobian matrix to what the authors termed an effective null space of J View full abstract»

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  • Graph-theoretic deadlock detection and resolution for flexible manufacturing systems

    Page(s): 413 - 421
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    Flexible manufacturing systems are capable of producing a broad variety of products and changing their characteristics quickly and frequently. This flexibility provides for more efficient use of resources, but makes control of these systems more difficult. Control problems previously unstudied now require practical resolution, like system deadlock. A system deadlock is a situation that arises due to resource sharing in manufacturing systems, when the flow of parts is permanently inhibited and/or operations on parts cannot be performed. This problem has been ignored by most scheduling and control studies, which usually assume infinite machine queue capacity and unlimited tooling resources. FMS's, however, have little or no queue capacity and limited tooling resources. In this paper, graph-theoretic deadlock detection and resolution procedures are presented which are suitable for real-time control of manufacturing systems. These procedures determine whether part movement in the system causes system deadlock or not. To this end, a system status graph representing part routings is virtually updated for every part movement before parts move physically to the next destination. Two types of system deadlocks, part flow deadlock and impending part flow deadlock, are detected using the updated system status graph. If a deadlock detection and recovery method is used to recover from a deadlock using a storage buffer, only part flow deadlocks need to be detected. On the other hand, if no buffer is available, both types of existing as well as impending system deadlocks need to be detected to avoid a deadlock situation 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