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Robotics and Automation, IEEE Transactions on

Issue 2 • Date April 1997

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Displaying Results 1 - 17 of 17
  • Modeling and Control of Robot Manipulators [Book Reviews]

    Publication Year: 1997 , Page(s): 315 - 316
    Cited by:  Papers (1)
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    Freely Available from IEEE
  • Hitting from any direction in 3-D space by a robot with a flexible link hammer

    Publication Year: 1997 , Page(s): 296 - 301
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    This paper describes a hammering robot with a flexible link which can hit an object from an arbitrary direction in a 3-D space. A dynamical equation of a flexible link hammer is presented by taking gravity into consideration. The conditions that the hammer can strike an object flatwise with only a normal velocity to its face are investigated, and a manipulating method to satisfy the hitting conditions is obtained View full abstract»

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  • Liquid crystal polarization camera

    Publication Year: 1997 , Page(s): 195 - 203
    Cited by:  Papers (26)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB)  

    We present a fully automated system which unites CCD camera technology with liquid crystal technology to create a polarization camera capable of sensing the partial linear polarization of reflected light from objects at pixel resolution. As polarization sensing not only measures intensity but also additional physical parameters of light, it can therefore provide a richer set of descriptive physical constraints for the understanding of images. Previously it has been shown that polarization cues can be used to perform dielectric/metal material identification, specular and diffuse reflection component analysis, as well as complex image segmentations that would be significantly more complicated or even infeasible using intensity and color alone. Such analysis has so far been done with a linear polarizer mechanically rotated in front of a CCD camera. The full automation of resolving polarization components using liquid crystals not only affords an elegant application, but significantly speeds up the sensing of polarization components and reduces the amount of optical distortion present in the wobbling of a mechanically rotating polarizer. In our system two twisted nematic liquid crystals are placed in front of a fixed linear polarizer placed in front of a CCD camera. The application of a series of electrical pulses to the liquid crystals in synchronization with the CCD camera video frame rate produces a controlled sequence of polarization component images that are stored and processed on Datacube boards. We present a scheme for mapping a partial linear polarization state measured at a pixel into hue, saturation and intensity producing a representation for a partial linear polarization image. Our polarization camera currently senses partial linear polarization and outputs such a color representation image at 5 Hz. The unique vision understanding capabilities of our polarization camera system are demonstrated with experimental results showing polarization-based dielectric/metal material classification, specular reflection and occluding contour segmentations in a fairly complex scene, and surface orientation constraints View full abstract»

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  • A decomposition of the manipulator inertia matrix

    Publication Year: 1997 , Page(s): 301 - 304
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A decomposition of the manipulator inertia matrix is essential, for example, in forward dynamics, where the joint accelerations are solved from the dynamical equations of motion. To do this, unlike a numerical algorithm, an analytical approach is suggested in this paper. The approach is based on the symbolic Gaussian elimination of the inertia matrix that reveal recursive relations among the elements of the resulting matrices. As a result, the decomposition can be done with the complexity of order n, O(n), where n being the degrees of freedom of the manipulator, as opposed to an O(n3) scheme, required in the numerical approach. In turn, O(n) inverse and forward dynamics algorithms can be developed. As an illustration, an O(n) forward dynamics algorithm is presented View full abstract»

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  • Repetitive and adaptive control of robot manipulators with velocity estimation

    Publication Year: 1997 , Page(s): 204 - 217
    Cited by:  Papers (65)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    This paper presents repetitive and adaptive motion control schemes for rigid-link robot manipulators, when the manipulator's joint velocities cannot be measured by the control system. The control objective consists in tracking a prescribed desired trajectory. In the case of repetitive control, the desired trajectory is periodic and it is required that the robot achieve the control objective through repeated learning trials. We assume that the robot inverse dynamics are totally unknown, except that they can be represented by an integral of the product of known differentiable kernel and an unknown influence function. In the case of adaptive control, it is assumed that only the manipulator inertia parameters are unknown and that the desired trajectory jerks are available to the control system. In both control schemes, a velocity observer, which is formulated based on the desired input/output relation of the manipulator, is used to estimate the manipulator joint velocities. A stability analysis of the repetitive and adaptive control schemes with velocity estimation is presented. Simulation and experimental results show that the proposed repetitive control algorithm is successful in achieving the control objective without direct measurement of the joint velocities View full abstract»

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  • Stability of frictional contact in constrained rigid-body dynamics

    Publication Year: 1997 , Page(s): 230 - 236
    Cited by:  Papers (14)
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    The use of rigid-body models during frictional contact is often justified by proving the existence of a unique solution to the forward dynamic equations. The implicit assumption here is that the contact forces so obtained are stable. In this paper, the rigid-body assumption is relaxed and body-to-body contacts are modeled using springs and dampers. A singular perturbation analysis reveals additional necessary conditions to ensure contact force stability in the reduced rigid-body model. Furthermore, the analysis indicates that stability depends on a damping ratio associated with the rigid contacts View full abstract»

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  • Modeling manufacturing dependability

    Publication Year: 1997 , Page(s): 161 - 168
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    In this paper, an analytical approach for the availability evaluation of cellular manufacturing systems is presented, where a manufacturing system is considered operational as long as its production capacity requirements are satisfied. The advantage of the approach is that constructing a system level Markov chain (a complex task) is not required. A manufacturing system is decomposed into two subsystems, i.e. machining system and material handling system. The machining subsystem is in turn decomposed into machine cells. For each machine cell and material handling subsystem, a Markovian model is derived and solved to find the probability of a subset of working machines in each cell, and a subset of the operating material handling carriers that satisfies the manufacturing capacity requirements. The overall manufacturing system availability is obtained using a procedure presented in the paper. The novelty of the approach is that it incorporates imperfect coverage and imperfect repair factors in the Markovian models. The approach is used to evaluate transient and steady-state performance of three alternative designs based on an industrial example. Detailed discussion of the results and the impact of imperfect coverage and imperfect repair on the availability of the manufacturing system is presented. Possible extensions of the work and software tools available for model analysis are also discussed View full abstract»

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  • Modeling closed-loop mechanisms in robots for purposes of calibration

    Publication Year: 1997 , Page(s): 218 - 229
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    A method for modeling the significant parameters of closed-loop mechanisms in robots for purposes of calibration is presented. Nonlinear kinematic and mechanical characteristics of the closed-loop mechanisms are modeled in such a way that they can be integrated into an open-loop manipulator model and identified. This integration is accomplished through a separation of the spatial open-loop manipulator (defining the kinematic model) and its joint-actuating mechanisms or actuator models which can be nonlinear in the case of closed-loop mechanisms. Identifiability of model parameters (including elasticity) is analyzed and calibration results are presented View full abstract»

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  • Scheduling messages on controller area network for real-time CIM applications

    Publication Year: 1997 , Page(s): 310 - 316
    Cited by:  Papers (49)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    Scheduling messages on the controller area network (CAN) corresponds to assigning identifiers (ID's) to messages according to their priorities. In this paper we present the mixed traffic scheduler (MTS) which provides higher schedulability than fixed-priority schemes, like deadline-monotonic (DM), while incurring less overhead than dynamic earliest-deadline (ED) scheduling. Through simulations, we compare the performance of MTS with that of DM and ED* (an imaginary scheduler which works like ED, except it incurs less overhead). Our simulations show that MTS performs much better than DM and at the same level as ED*, except under high loads and tight deadlines, when ED* is superior View full abstract»

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  • Performance measures for constrained systems

    Publication Year: 1997 , Page(s): 278 - 289
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    We present a geometric theory of the performance of robot manipulators, applicable to systems with constraints, which may be nonholonomic. The performance is quantified by a geometrical object, the induced metric tensor, from which scalars may be constructed by invariant tensor operations to give performance measures. The measures thus defined depend on the metric structure of configuration and workspace, which should be chosen appropriately for the problem at hand. The generality of this approach allows us to specify a system of joint connected rigid bodies with a large class of metrics. We describe how the induced metric can be computed for such a system of joint connected rigid bodies and describe a MATLAB program that allows the automatic computation of the performance measures for such systems. We illustrate these ideas with some computations of measures for the SARCOS dextrous arm, and the Platonic Beast, a multilegged walking machine View full abstract»

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  • Optimal obstacle avoidance based on the Hamilton-Jacobi-Bellman equation

    Publication Year: 1997 , Page(s): 305 - 310
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    This paper solves the online obstacle avoidance problem using the Hamilton-Jacobi-Bellman (HJB) theory. Formulating the shortest path problem as a time optimal control problem, the shortest paths are generated by following the negative gradient of the return function, which is the solution of the HJB equation. To account for multiple obstacles, we avoid obstacles optimally one at a time. This is equivalent to following the pseudo-return function, which is an approximation of the true return function for the multi-obstacle problem. Paths generated by this method are near-optimal and guaranteed to reach the goal, at which the pseudo-return function is shown to have a unique minimum. The proposed method is computationally very efficient, and applicable for online applications. Examples for circular obstacles demonstrate the advantages of the proposed approach over traditional path planning methods View full abstract»

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  • An articulated-body model for a free-flying robot and its use for adaptive motion control

    Publication Year: 1997 , Page(s): 264 - 277
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    We synthesize an adaptive motion control law for a free-flying robot with no external forces or moments. The basic idea is to make use of the articulated part of the space robot to control the position and orientation of the end-effector in an inertial frame. The inertia parameters for the robot end-effector and load are assumed to be a priori unknown. The articulated-body model is linear in the unknown parameters, so that an adaptive control law is developed. A novel feature of our approach is that the parameter estimates are obtained using momentum integrals only. In addition, we use unit quaternions to represent orientation errors. The stability properties of the adaptive control law is shown using Lyapunov stability theory. Computer simulations of an example 12 degrees of freedom space robot system are presented View full abstract»

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  • Deterministic timed event graphs for performance optimization of cyclic manufacturing processes

    Publication Year: 1997 , Page(s): 169 - 181
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    A model of a cyclic manufacturing system representable as a deterministic timed event graph is considered in this paper. It is possible to apply analytical techniques for performance evaluation of such systems. On this basis, a two-level optimization problem is considered. The higher level refers to the maximization of the system productivity with respect to the assignment of operations to machines, the lot sizes, and the service sequences at the various machines, assuming that unlimited work-in-progress and buffers of finite dimension are available. The lower level deals with the minimization of an aggregate cost taking into account the work-in-progress and the buffer dimensions View full abstract»

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  • Model-based planning of optimal sensor placements for inspection

    Publication Year: 1997 , Page(s): 182 - 194
    Cited by:  Papers (41)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    We report a system for sensor planning, GASP, which is used to compute the optimal positions for inspection tasks using known imaging sensors and feature-based object models. GASP (general automatic sensor planning) uses a feature inspection representation (the FIR), which contains the explicit solution for the simplest sensor positioning problem. The FIR is generated off-line, and is exploited by GASP to compute on-line plans for more complex tasks, called inspection scripts. Viewpoint optimality is defined as a function of feature visibility and measurement reliability. Visibility is computed using an approximate model. Reliability of inspection depends on both the physical sensors acquiring the images and on the processing software; therefore we include both these components in a generalized sensor model. These predictions are based on experimental, quantitative assessment. We show how these are computed for a real generalized sensor, which includes a 3-D range imaging system, and software performing robust outlier removal, surface segmentation, object location and surface fitting. Finally, we demonstrate a complete inspection session involving 3-D object positioning, planning optimal position inspection, and feature measurement from the optimal viewpoint View full abstract»

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  • 3-D polyhedral face computation from two perspective views with the aid of a calibration plate

    Publication Year: 1997 , Page(s): 290 - 295
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    The 3-D reconstruction of visible polyhedral faces from a pair of general perspective views with the aid of a calibration plate is addressed. A polyhedron is placed on a planar calibration plate and two side views of both the polyhedron and the calibration plate are taken. Through proper arrangements we may assume that in the two views a number of polyhedral edges lying on the calibration plate and the whole calibration plate boundary are visible. We present an online camera calibration technique with the aid of the calibration plate and a two-stage process to find the vertex/edge correspondences without encountering the ambiguity problem of the conventional epipolar line technique. We then give a closed form solution to the 3-D polyhedral vertices visible in both images. We also describe other advantages of using our method for the 3-D polyhedron reconstruction. Experimental results show that the obtained 3-D polyhedral vertex coordinates are rather accurate View full abstract»

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  • Mobile robot localization using landmarks

    Publication Year: 1997 , Page(s): 251 - 263
    Cited by:  Papers (134)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    We describe an efficient method for localizing a mobile robot in an environment with landmarks. We assume that the robot can identify these landmarks and measure their bearings relative to each other. Given such noisy input, the algorithm estimates the robot's position and orientation with respect to the map of the environment. The algorithm makes efficient use of our representation of the landmarks by complex numbers. The algorithm runs in time linear in the number of landmarks. We present results of simulations and propose how to use our method for robot navigation View full abstract»

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  • Collision-free path planning for a diamond-shaped robot using two-dimensional cellular automata

    Publication Year: 1997 , Page(s): 237 - 250
    Cited by:  Papers (30)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1332 KB)  

    This paper presents a new parallel algorithm for collision-free path planning of a diamond-shaped robot among arbitrarily shaped obstacles, which are represented as a discrete image, and its implementation in VLSI. The proposed algorithm is based on a retraction of free space onto the Voronoi diagram, which is constructed through the time evolution of cellular automata, after an initial phase during which the boundaries of obstacles are identified and coded with respect to their orientation. The proposed algorithm is both space and time efficient, since it does not require the modeling of objects or distance and intersection calculations. Additionally, the proposed twodimensional multistate cellular automaton architecture achieves high frequency of operation and it is particularly suited for VLSI implementation due to its inherent parallelism, structural locality, regularity, and modularity 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