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Robotics and Automation, IEEE Transactions on

Issue 4 • Date Aug 1993

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Displaying Results 1 - 17 of 17
  • Viewpoint independent representation and recognition of polygonal faces in 3-D

    Publication Year: 1993 , Page(s): 457 - 463
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    The recognition of polygons in 3-D space is an important task in robot vision. Two particular problems are addressed in the paper. First a new set of local shape descriptors for polygons are proposed that are invariant under affine transformation. Furthermore, they are complete in the sense that they allow the reconstruction of any polygon in 3-D space from three consecutive vertices. The second problem discussed in this paper is the recognition of 2-D polygonal objects under affine transformation and the presence of partial occlusion. A recognition procedure that is based on the matching of edge length ratios is introduced using a simplified version of the standard dynamic programming procedure commonly employed for string matching. The algorithm is conceptually very simple, easy to implement and has a low computational complexity. It is in a set of experiments that the method is reliable and robust View full abstract»

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  • Regulation of flexible arms under gravity

    Publication Year: 1993 , Page(s): 463 - 467
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    A simple controller is presented for the regulation problem of robot arms with flexible links under gravity. It consists of a joint PD feedback plus a constant feedforward. Global asymptotic stability of the reference equilibrium state is shown under a structural assumption about link elasticity and a mild condition on the proportional gain. The result holds also in the absence of internal damping of the flexible arm. A numerical case study is presented View full abstract»

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  • Control of flexible arms with friction in the joints

    Publication Year: 1993 , Page(s): 467 - 475
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (804 KB)  

    The control of flexible arms with friction in the joints is studied. A method to identify the dynamics of a flexible arm from its frequency response (which is strongly distorted by Coulomb's friction) is proposed. A robust control scheme that minimizes the effects of this friction is presented. The scheme consists of two nested feedback loops: an inner loop to control the motor position and an outer loop to control the tip position. It is shown that a proper design of the inner loop eliminates the effects of friction while controlling the tip position and significantly simplifies the design of the outer loop. The proposed scheme is applied to a class of lightweight flexible arms, and the experiments show that the control scheme results in a simple controller. As a result, the computations are minimized and, thus, high sampling rates may be used View full abstract»

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  • Coordinated control of multiple manipulator systems

    Publication Year: 1993 , Page(s): 400 - 410
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    A scheme for controlling multimanipulator systems is presented. The control objective is to coordinate the manipulators to perform parts-matching tasks such as screwing a nut onto a bolt. The task of moving a rigid object can be treated as a special case. Two secondary control objectives, internal force control and load distribution, can be accomplished within the structure of the control law. The internal force control mechanism keeps the internal forces on the object being manipulated at a desirable level. The load distribution mechanism distributes control effort to each manipulator according to a weighting factor. It is also shown that the control algorithm has a modular structure which facilitates its implementation on a multiprocessor computer. The scheme was tested on a planar scara type dual-manipulator system. A series of experimental results is included to demonstrate the system performance under various conditions View full abstract»

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  • Toward automatic robot instruction from perception-recognizing a grasp from observation

    Publication Year: 1993 , Page(s): 432 - 443
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1120 KB)  

    Deals with the programming of robots to perform grasping tasks. To do this, the assembly plan from observation (APO) paradigm is adopted, where the key idea is to enable a system to observe a human performing a grasping task, understand it, and perform the task with minimal human intervention. A grasping task is composed of three phases: pregrasp phase, static grasp phase, and manipulation phase. The first step in recognizing a grasping task is identifying the grasp itself. The proposed strategy of identifying the grasp is to map the low-level hand configuration to increasingly more abstract grasp descriptions. To achieve the mapping, a grasp representation is introduced, called the contact web, which is composed of a pattern of effective contact points between the hand and the object. A grasp taxonomy based on the contact web is also proposed as a tool to systematically identify a grasp. The grasp can be described at higher conceptual levels using a certain mapping function that results in an index called the grasp cohesive index. This index can be used to identify the grasp. Results from grasping experiments show that it is possible to distinguish between various types of grasps using the proposed contact web, grasp taxonomy and grasp cohesive index View full abstract»

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  • An analysis of the kinematics and dynamics of underactuated manipulators

    Publication Year: 1993 , Page(s): 411 - 422
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1012 KB)  

    The dynamics and kinematics of manipulators that have fewer actuators than degrees of freedom are studied. These underactuated manipulators arise in a number of important applications such as free-flying space robots, hyperredundant manipulators, manipulators with structural flexibility, etc. In the analysis such underactuated manipulators are decomposed into component active and passive arms. This decomposition allows techniques previously developed for regular (fully actuated) manipulators to be applied to underactuated systems. Spatial operator identities are used to develop closed-form expressions for the generalized accelerations for the system. These expressions form the basis for a recursive O(N) dynamics algorithm. The structure of this algorithm is a hybrid of known forward and inverse dynamics algorithms for regular manipulators. Expressions and computational algorithms are also developed for the generalized and disturbance Jacobians for underactuated manipulators. The application of the results in the paper to space manipulators is also described View full abstract»

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  • Segmentation of range images: an orthogonal moment-based integrated approach

    Publication Year: 1993 , Page(s): 385 - 399
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1656 KB)  

    A new approach to range image segmentation is presented. The proposed approach involves two phases in which the region and edge information detected using a set of orthogonal Zernike moment-based operators are combined to provide robust segmentation of range images. In the first phase, each range image point is characterized by the surface normal vector and the depth value at that point. A surface feature-based clustering of range image points yields its initial region-based segmentation. This initial segmentation phase often produces oversegmented images. In the second phase of the proposed technique, the oversegmented image is resegmented by appropriately merging adjacent regions using the edge information to produce final segmentation. One attractive characteristic of the proposed technique is that the same set of three moment-based operators is used to extract both surface and edge features. Thus only three convolution operations are needed at an image point to compute all the desired surface and edge features associated with that point. The performances of the proposed Zernike moment-based operators in surface and edge feature detection are theoretically analyzed View full abstract»

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  • Steering a robot with vanishing points

    Publication Year: 1993 , Page(s): 491 - 498
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    The paper analyzes the use of vanishing points for steering a robot. Parallel lines in the environment of the robot are used to compute vanishing points which serve as a reference for guiding the robot. To accomplish the steering task, three subtasks are performed: detection of straight lines, computation of vanishing points, and robot steering using vanishing points. Straight lines are detected by employing a high precision edge detector and a line-fitting algorithm. The cross product method introduced by Magee and Aggarwal (1984) is modified to make the detection of vanishing points appropriate for an indoor environment. Properties of vanishing points under camera rotation and translation are derived. Using these properties, the location of the vanishing points can serve as a reference for steering the robot. A model of the robot environment is defined, summarizing the minimum number of constraints necessary for the method to work. Finally, the limitations as well as the advantages of using vanishing points in robot navigation are discussed View full abstract»

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  • Iterative inverse kinematics with manipulator configuration control

    Publication Year: 1993 , Page(s): 476 - 483
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    A new method, termed the offset modification method (OM method), for solving the manipulator inverse kinematics problem is presented. The OM method works by modifying the link offset values of a manipulator until it is possible to derive closed-form inverse kinematics equations for the resulting manipulator (termed the model manipulator). This procedure allows one to derive a set of three nonlinear equations in three unknowns that, when numerically solved, give an inverse kinematics solution for the original manipulator. The OM method can be applied to manipulators with any number of degrees of freedom, as long as the manipulator satisfies a given set of conditions (Theorem 1). The OM method is tested on a 6-degree-of-freedom manipulator that has no known closed-form inverse kinematics equations. It is shown that the OM method is applicable to real-time manipulator control, can be used to guarantee convergence to a desired endpoint position and orientation (if it exists), and allows one to directly choose which inverse kinematics solution the algorithm will converge to (as specified in the model manipulator closed-form inverse kinematics equations). Applications of the method to other 6-DOF manipulator geometries and to redundant manipulators (i.e. greater than 6 DOF geometries) are discussed View full abstract»

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  • Robust impedance shaping telemanipulation

    Publication Year: 1993 , Page(s): 374 - 384
    Cited by:  Papers (98)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (920 KB)  

    When a human operator performs a task via a bilateral manipulator, the “feel” of the task is embodied in the mechanical impedance of the manipulator. Traditionally, a bilateral manipulator is designed for transparency; i.e. so that the impedance reflected through the manipulator closely approximates that of the task. “Impedance shaping bilateral control”, introduced here, differs in that it treats the bilateral manipulator as a means of constructively altering the impedance of a task. This concept is particularly valuable if the characteristic dimensions (e.g. force, length, time) of the task impedance are very different from those of the human limb. It is shown that a general form of impedance shaping control consists of a conventional power-scaling bilateral controller augmented with a real-time interactive task simulation (i.e. a virtual environment). An approach to impedance shaping based on kinematic similarity between tasks of different scale is introduced and illustrated with an example. It is shown that an important consideration in impedance shaping controller design is robustness; i.e. guaranteeing the stability of the operator/manipulator/task system. A general condition for the robustness of a bilateral manipulator is derived. This condition is based on the structured singular value (μ). An example of robust impedance shaping bilateral control is presented and discussed View full abstract»

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  • Learning hybrid force and position control of robot manipulators

    Publication Year: 1993 , Page(s): 423 - 431
    Cited by:  Papers (35)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    The learning control is applied to hybrid force and position control of robot manipulators. When the geometry and position of a constraint surface is known, the hybrid force and position controller and the feedforward compensator can be designed in the constraint coordinates. When the operation is periodic, the learning hybrid force and position control enhance the control performance as the feedforward compensator is updated in each cycle by the force and position error in the preceding trials. This scheme is proved to be asymptotically stable. A two degree of freedom SCARA-type direct-drive robot manipulator is used to test the learning hybrid force and position control. The deburring tool mounted on the upper link of the robot could follow a flat, tilted flat, and curved ¼" aluminum plate with a desired contact force of 10 N (within the root-mean-square force error of 1.95 N) and with a desired tangential velocity. The experiments confirmed the effectiveness of the learning hybrid force and position controller View full abstract»

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  • Finding antipodal point grasps on irregularly shaped objects

    Publication Year: 1993 , Page(s): 507 - 512
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    Two-finger antipodal point grasping of arbitrarily shaped smooth 2-D and 3-D objects is considered. An object function is introduced that maps a finger contact space to the object surface. Conditions are developed to identify the feasible grasping region, F, in the finger contact space. A “grasping energy function”, E , is introduced which is proportional to the distance between two grasping points. The antipodal points correspond to critical points of E in F. Optimization and/or continuation techniques are used to find these critical points. In particular, global optimization techniques are applied to find the “maximal” or “minimal” grasp. Further, modeling techniques are introduced for representing 2-D and 3-D objects using B-spline curves and spherical product surfaces View full abstract»

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  • The parallel approach to force/position control of robotic manipulators

    Publication Year: 1993 , Page(s): 361 - 373
    Cited by:  Papers (67)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1232 KB)  

    Force/position control strategies provide an effective framework to deal with tasks involving interaction with the environment. In this paper the parallel approach to force/position control of robotic manipulators is presented. It shows a complete use of the available sensor measurements by operating the control action in a full-dimensional space without using selection matrices. Conflicting situations between the position and force tasks are managed using a priority strategy: the force control loop is designed to prevail over the position control loop. This choice ensures limited deviations from the prescribed force trajectory in every situation, guaranteeing automatic recovery from unplanned collisions. A dynamic force/position parallel control law is presented and its performance in presence of an elastic environment is analyzed; simplification of the dynamic control law is also discussed leading to a PID-type parallel controller. Two case studies are worked out that show the effectiveness of the approach in application to an industrial robot View full abstract»

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  • A tactile sensor system for universal joint sections of manipulators

    Publication Year: 1993 , Page(s): 512 - 517
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    It is very difficult to place tactile sensors around revolute joints of manipulators, since those joints and surrounding surfaces are not stationary and thus they remain insensitive to contact with obstacles. This interferes with the introduction of sensors for collision avoidance control in manipulators. This paper deals with a tactile sensor system for universal joint sections of manipulators in order to detect collisions with obstacles. Its unique characteristic is the ability to detect, in one sampling period, the positions of more than one collision despite having only one signal line. It is achieved by making use of the resonance phenomenon of the sensor circuit, and all sensor elements can be distinguished from one another by frequency division. The structure of the sensor and the method to detect the label number and position of the sensor elements that are in contact with obstacles are described, followed by analysis of the circuits and experimental results of the sensor system View full abstract»

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  • Exploiting nonholonomic redundancy of free-flying space robots

    Publication Year: 1993 , Page(s): 499 - 506
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Nonholonomic redundancy is an intrinsic property of nonholonomic mechanical systems. A free-flying space robot is a nonholonomic mechanical system, and exhibits the presence of nonholonomic redundancy even in the absence of ordinary kinematic redundancy. Like ordinary kinematic redundancy, nonholonomic redundancy can also be utilized while planning trajectories for the system. In the paper, a trajectory planning scheme for a 6-DOF space robot is developed in which nonholonomic redundancy for avoiding joint limits and obstacles is utilized View full abstract»

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  • Range-image-based calculation of three-dimensional convex object moments

    Publication Year: 1993 , Page(s): 484 - 490
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    In the paper, a novel method is proposed to calculate three-dimensional (3-D) moments. First, a discrete Gaussian theorem is proposed to convert the summation in a 3-D volume domain to that on a 2-D plane region, which decreases computational complexity from O(N3) to O(N2). Second, a Pascal triangle transform, a Pascal triangle matrix, and a systolic structure are proposed to calculate the monomials on a 3-D object boundary surface, which simplifies the monomial calculation. Third, a range-image measurement system is used to implement the new method. Finally, a comparison of the authors' method with the known ones is provided, showing that the authors' method is much simpler View full abstract»

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  • Path planning and the topology of configuration space

    Publication Year: 1993 , Page(s): 444 - 456
    Cited by:  Papers (21)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1136 KB)  

    This work considers the path planning problem for planar revolute manipulators operating in a workspace of polygonal obstacles. This problem is solved by determining the topological characteristics of obstacles in configuration space, thereby determining where feasible paths can be found. A collision-free path is then calculated by using the mathematical description of the boundaries of only those configuration space obstacles with which collisions are possible. The key to this technique is a simple test for determining whether two disjoint obstacles are connected in configuration space. This test allows the path planner to restrict its calculations to regions in which collision-free paths are guaranteed a priori, thus avoiding unnecessary computations and resulting in an efficient implementation. Typical timing results for environments consisting of four polyhedral obstacles comprising a total of 27 vertices are of the order of 22 ms on a SPARC-IPC workstation 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