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Robotics and Automation, IEEE Transactions on

Issue 5 • Date Oct 1989

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Displaying Results 1 - 13 of 13
  • Residue arithmetic VLSI array architecture for manipulator pseudo-inverse Jacobian computation

    Page(s): 569 - 582
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    The authors present the design of a two-level macro-pipelined VLSI array architecture for the real-time computation of the exact solution of the manipulator pseudo-inverse Jacobian using the Decell algorithm in the residue arithmetic system. The first-level arrays are asynchronous data-driven, wave-front-like arrays and perform matrix multiplication, matrix diagonal addition, and trace computations in the Decel algorithm. A pool of the first-level arrays is then configured into a second-level macro-pipeline with outputs of one array acting as inputs to another array in the pipe. The pipelined time of the proposed two-level pipelined array architecture has a computational order of 0(n+2 p-1), which is the same computational complexity order as that of the evaluation of a matrix product in an ordinary wavefront array. For a 12 degree-of-freedom redundant robot, a pipelined time of 6.975 μs is achievable with current VLSI custom design technology View full abstract»

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  • A restructurable VLSI robotics vector processor architecture for real-time control

    Page(s): 583 - 599
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    The authors propose a restructurable architecture based on a VLSI robotics vector processor (RVP) chip. It is specially tailored to exploit parallelism in the low-level matrix/vector operations characteristic of the kinematics and dynamics computations required for real-time control. The RVP is composed of three tightly synchronized 32-bit floating-point processors to provide adequate computational power. Besides adder and multiplier units in each processor, the RVP contains a triple register-file, dual shift network, and dual high-speed input/output (I/O) channels to satisfy the storage and data movement demands of the computations targeted. Efficiently synchronized multiple-RVP configurations, which may be viewed as variable very-long-instruction-word architectures, can be constructed and adapted to match the computational requirements of specific robotics computations. The use of the RVP is illustrated through a detailed example of the Jacobian computation, demonstrating good speedup over conventional microprocessors even with a single RVP. The RVP has been developed to be implementable on a single VLSI chip using 1.2-μm CMOS technology, so that a single-board multiple-RVP system can be targeted for use on a mobile robot View full abstract»

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  • Integration of multiple sensors into a robotic system and its performance evaluation

    Page(s): 658 - 669
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    The author proposes a systematic approach to integrating multiple sensors into a robotic system. It is shown that the robot motion control mechanism has a hierarchical structure consisting of multiple layers. The integration of multiple sensors should not disturb the structure, but it should enhance the intelligence of each activity. Therefore, multiple sensors can be hierarchically integrated into an existing system. To make the integration feasible, the author adopts the concept of logical sensors and treats logical sensors as object modules. By using object-oriented programming, integration becomes a modular procedure and interobject communication becomes an effective method of data flow required by the integration. The authors also proposes an objective method for evaluating the performance of integration. The benefit of the integration is measured by how the intelligence of the robotic system is enhanced. The cost of the integration is measured by a cost function and a loss function. The former is related to the sensor time; the latter is affected by sensor uncertainty View full abstract»

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  • A discrete trajectory planner for robotic arms with six degrees of freedom

    Page(s): 681 - 690
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    A discrete trajectory planner is described which has been shown to be capable of planning optimal trajectories for a six-degree-of-freedom robot with minimum time/energy objective functions and realistic constraints on the joint velocities, joint torques, joint jerks, and hand velocity. It is also flexible enough to handle other objective functions and constraints, provided they can be satisfactorily discretized. An alternative formulation of the discrete trajectory planner is also provided for the efficient generation of optimal trajectories when equal time intervals are required. Once an optimal trajectory is planned offline with the discrete trajectory planner, the open-loop solution can be fed to the online feedback controller for trajectory tracking. Computation time taken by the discrete trajectory planner is acceptable for offline planning purposes. Numerical examples are presented for the Stanford manipulator using all six degrees of freedom View full abstract»

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  • Vision-guided servoing with feature-based trajectory generation [for robots]

    Page(s): 691 - 700
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    The authors present a vision module which is able to guide an eye-in-hand robot through general servoing and tracking problems using off-the-shelf image-processing equipment. The vision module uses the location of binary image features from a camera on the robot's end-effector to control the position and one degree of orientation of the robot manipulator. A unique feature-based trajectory generator provides smooth motion between the actual image features and the desired image features even with asynchronous and discontinuous vision updates. By performing the trajectory generation in image feature space, image-processing constraints such as the feature extraction time can be accounted for when determining the appropriate segmentation and acceleration times of the trajectory. Experimental results of a PUMA robot tracking objects with vision feedback are discussed View full abstract»

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  • Special computer architectures for robotics: tutorial and survey

    Page(s): 543 - 554
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    The author provides an overview of recent research into specially designed computer architectures which can provide enhanced computational capabilities to meet the special needs of real-time control of robots and other automation systems. He reviews standard techniques for improving computational power through parallelism and special hardware and then considers how these approaches can be applied to problems in robot control, sensing, and coordination. It is noted that parallel and concurrent computing architectures offer several promising routes for achieving performance improvements, but they must meet the criteria of practical implementability, including connectability, performance, and cost. Some proposed architectures for performance improvements are surveyed, several of which have already achieved some degree of implementation. This survey is intended both to highlight significant progress to date and to provide an overview of the emerging trends for the development of specialized computer architectures in this field of application View full abstract»

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  • SPARTA: multiple signal processors for high-performance robot control

    Page(s): 628 - 640
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    The authors describe the SPARTA (signal processor architecture for real-time applications) system, which is a hybrid computer development system including: (1) a program development environment on an IBM VM/CMS mainframe computer: (2) user interface and runtime support on an IBM PC; and (3) real-time computation and input/output using multiple IBM Hermes signal processors situated on the IBM PC bus. The program development environment includes the PLH high-level language for generating efficient real-time Hermes code. The runtime supports symbolic debugging, dynamic loading and linking, and synchronous switching of control algorithms during real-time program execution. The real-time environment includes a distributed operating system which supports foreground and background task execution and real-time data collection and display. The task switching overhead is 0.1 μs, nonpreemptive, and 1.0-3.7 μs when the context is changed by an interrupt (i.e. preemptive) View full abstract»

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  • Prediction of the upper limit of feedrate for robot translational contouring

    Page(s): 670 - 680
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    The problem of how fast a robot can move without exceeding the limits of the joint motor capacities is addressed. For a robot translational contouring, it has been theoretically established that the joint velocities and the joint accelerations can be expressed as products of a feedrate-dependent term and a spatial function called the specific joint velocities and the specific joint accelerations, respectively. On the basis of this separation of variables, a simple efficient algorithms has been developed to determine the maximum feedrate under the constraints on the joint velocities and accelerations. A computer simulation of a typical task in robot translational contouring has been carried out to demonstrate the methodology and its applications in the design of joint motor capacities and selection process conditions View full abstract»

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  • CONDOR: an architecture for controlling the Utah-MIT dexterous hand

    Page(s): 616 - 627
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    The authors describe a fully implemented computational architecture (CONDOR) that controls the Utah-MIT dexterous hand and other complex robots. The architecture derives its power from the highly efficient real-time environment provided for its control processors, coupled with a development host that allows flexible program development. By mapping the memory of a dedicated group of processors into the address space of a host computer, efficient sharing of system resources between them is possible. The software is characterized by a few simple design concepts but provides the facilities out of which more powerful utilities such as a multiprocessor pseudo-terminal emulator, a transparent and fast file server, and a flexible symbolic debugger could be constructed View full abstract»

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  • Reconstruction of three-dimensional surfaces from two-dimensional binary images

    Page(s): 701 - 710
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    The authors describe a method for reconstruction of three-dimensional visible and invisible opaque surfaces using moving shadows. An object whose shape is to be determined is placed on a reference surface. A beam of substantially parallel rays of light is projected at the object at a set of different angles relative to the reference surface. Using a camera which is placed above the reference surface, the shadows cast by the object for each angle are transferred to a computer. A three-dimensional binary level shadow diagram (3DBL shadowgram) is formed and analyzed. The shadowgram has some features which make the reconstruction very simple: a section of the 3DBL shadowgram, referred to as a 2DBL shadowgram, can be used to determine the heights of points of the object to be reconstructed. Further analysis of some curves of the shadowgram can be used for the partial reconstruction of invisible surfaces. A set of experimental results to test the effects of the threshold, camera resolution, and the number of pictures demonstrates the robustness and usefulness of the method View full abstract»

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  • Neural network architectures for robotic applications

    Page(s): 641 - 657
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    The authors propose a ring VLSI systolic architecture for implementing artificial neural networks (ANNs) with applications to robotic processing. Key design issues concerning algorithms, applications, and architectures are examined. A variety of neural networks is considered, including single-layer feedback neural networks, competitive learning networks, and multilayer feed-forward networks. It is demonstrated that the ANNs are suitable to all three levels of robotic processing applications including task planning, path planning, and path control levels. For these applications, a programmable systolic array is developed than can exploit the strength of VLSI to provide intensive and pipelined computing. Both the retrieving and learning phases are integrated in the design. The proposed architecture, which is more versatile than other existing ANNs, can accommodate all the useful neural networks for robotic processing View full abstract»

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  • A modular architecture for inverse robot kinematics

    Page(s): 555 - 568
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    A modular architecture for general-purpose inverse robot kinematics is developed. The authors synthesize kinematic modules for the robot arm and wrist and develop computational blocks to describe their respective functions. They then present an analytical framework that defines the inverse kinematic problem in terms of the proper coordination of the kinematic modules to accomplish the desired robot task. In this general-purpose framework, the inverse kinematics problem is always solvable in the feasible regions of the robot workspace, irrespective of whether the solution is analytically tractable. The modular architecture is based upon a nonlinear equation solver for which the Banach fixed-point theorem provides the theoretical basis. The proposed framework allows for the mathematical definition of the region in the robot workspace where convergence to the correct solution is guaranteed. It is insensitive to the initial estimates and provides for the computation of multiple solutions View full abstract»

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  • A class of parallel algorithms for computation of the manipulator inertia matrix

    Page(s): 600 - 615
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    A class of parallel and parallel/pipeline algorithms for computation of the manipulator inertial matrix is presented. An algorithm based on the composite rigid-body spatial inertia method, which results in less data dependency and hence better parallelization efficiency, is used for computation of the inertia matrix. Two parallel algorithms are developed which achieve the time lower bound of O([log 2 n])+O(1) in the computation with O(n2) processors. The architectural features required for perfect mapping of these algorithms and their communication complexity are analyzed. The performance of the algorithms when mapped on two- and one-dimensional (linear) processor arrays with nearest-neighbor connection is investigated. Mapping on the linear array results in new algorithms with a computational complexity of k 1n[log2n]+k2 [log2n]+k3. A parallel/pipeline algorithm is also presented which achieves the computation time of k1n+k2 [log2 n]+k3 on the linear array. An architecture-oriented approach is used in the design of the algorithms 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