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Robotics and Automation, 1993. Proceedings., 1993 IEEE International Conference on

Date 2-6 May 1993

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  • Proceedings of 1993 IEEE International Conference on Robotics and Automation

    Publication Year: 1993
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    Freely Available from IEEE
  • Path-velocity decomposition revisited and applied to dynamic trajectory planning

    Publication Year: 1993 , Page(s): 40 - 45 vol.2
    Cited by:  Papers (14)
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    Dynamic trajectory planning is addressed. The case of a car-like robot, A, with bounded velocity and acceleration, moving in a dynamic workspace W=R2 is considered. The concept of adjacent paths is introduced, and used within a novel motion planning schema which operates in two complementary stages, paths-planning and trajectory-planning. In the paths-planning stage, a set of adjacent paths, one of which leads A to its goal, are computed. These paths are collision-free with the stationary obstacles and respect A's kinematic constraints. In the trajectory-planning stage, knowing that A is able to shift from one path to an adjacent one freely, the motion of A along and between these paths is determined so as to avoid any collision with the moving obstacles while respecting A's dynamic constraints View full abstract»

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  • Parallel search algorithms for robot motion planning

    Publication Year: 1993 , Page(s): 46 - 51 vol.2
    Cited by:  Papers (21)
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    The authors show that parallel search techniques derived from their sequential counterparts can enable the solution of instances of the robot motion planning problem which are computationally infeasible on sequential machines. A parallel version of a robot motion planning algorithm based on quasibest first search with randomized escape from local minima and random backtracking is presented. Its performance on a problem instance, which was computationally infeasible on a single processor of an nCUBE2 multicomputer, is discussed. The limitations of parallel robot motion planning systems are discussed, and a course for future work is suggested View full abstract»

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  • Efficient search and hierarchical motion planning using dynamic single-source shortest paths trees

    Publication Year: 1993 , Page(s): 566 - 571 vol.1
    Cited by:  Papers (1)
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    All previous robot motion planners based on approximate cell decomposition exhibit redundancy between successive searchers for a sequence of empty cells. A search method that eliminates this redundancy is presented. It is founded on the ability to efficiently maintain a single-source shortest paths tree embedded in the connectivity graph that is subject to the dynamic modifications that result from incremental subdivision of cells. The convergence of the algorithm is controlled by the vertex cost function, which relies on an estimate for the proportion of free space in a cell. The planner is fully implemented, and empirical results are given to illustrate the performance improvements of the dynamic algorithm compared to Dijkstra's algorithm View full abstract»

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  • Surface fitting from digitized data points

    Publication Year: 1993
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    Digitized data carry measurement errors. To assure the accuracy of the fitted surface, two fittings are made instead of one. The first fitting generates quadric surfaces from the digitized points by the least squares method in order to filter out the measurement errors. The second fitting generates bicubic splines as the final result from the patch nodes calculated from the quadric surfaces View full abstract»

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  • Obstacle avoidance for redundant manipulators using the compact QP method

    Publication Year: 1993 , Page(s): 262 - 269 vol.3
    Cited by:  Papers (17)
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    The compact QP (quadratic programming) method is proposed to resolve the obstacle avoidance problem for a redundant manipulator. The drift-free criterion is considered when a redundant manipulator performs a repeated motion. Due to the computational efficiency and versatility of the compact QP method, real-time implementation is able to be achieved, and physical limitations such as joint rate bounds and joint angle limits can be easily taken into account. An example is given to demonstrate that this method is able to avoid the throat of a cavity, and to remedy the drift problem while a primary goal of the manipulators is carried out. Simulation results show that multiple goals can easily be fulfilled by this method View full abstract»

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  • Modelling of assembly partitions for a distributed environment

    Publication Year: 1993 , Page(s): 52 - 57 vol.2
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    The problem of partitioning mechanical assembly processes to increase throughput and reduce costs is discussed. A partitioning model which takes into account constraints such as precedence relations while maximizing the efficiency or performance is described. A hierarchical portioning method, where several different criteria are used in the partitioning process, is also discussed View full abstract»

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  • Symbolical singular value decomposition for a 7-DOF manipulator and its application to robot control

    Publication Year: 1993 , Page(s): 895 - 900 vol.3
    Cited by:  Papers (3)  |  Patents (1)
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    The method for symbolical singular value decomposition (SVD) based on Jacobian decomposition is broadened to cover simple redundant manipulators. The redundant robot should be decomposed into its nonredundant part and an actually redundant subrobot. The Jacobians should be expressed in some intermediate coordinate frames in order to obtain the simplest symbolical expressions. The Jacobian for the nonredundant part should be decomposed into several submatrices of the order 1×1, 2×2 or 3×3. In the case of 3×3 matrices, it is not always possible to obtain the symbolical expressions for SVD. The redundant subrobot Jacobian should also be further decomposed into submatrices of the order ms× ns, with ms being less or equal to 2. By deriving the symbolical damped least-squares solution, the numerical complexity is reduced about 15 times as compared to the numerical SVD of the Jacobian submatrices of the same order. Simulations at the kinematic control level have shown very low position error and limited joint velocities View full abstract»

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  • Mechanical computation for passive force control

    Publication Year: 1993 , Page(s): 476 - 483 vol.1
    Cited by:  Papers (3)  |  Patents (1)
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    It is shown that a passive robotic wrist, of fixed mechanical design, can be programmed to execute a wide range of force control laws useful in automated assembly. A systematic characterization of the range of control laws (given by accommodation matrices) implementable by passive programmable hydraulic devices carried out. The authors use electrical network theory results to identify the accommodation matrices that are available in the joint-space of the wrist. These matrices are projected onto the task-space, and the range of task-space matrices is compared with a known class of matrices in an attempt to quantify the usefulness of passive devices. For simplicity, hydraulic networks consisting of tunable dampers are considered. It is shown that a broad range of accommodation matrices may be synthesized by passive devices with programmable parameters View full abstract»

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  • Exploration strategies for mobile robots

    Publication Year: 1993 , Page(s): 248 - 253 vol.2
    Cited by:  Papers (8)
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    The problem of programming a robot to carry out a systematic exploration of its environment using realistic sensors is considered. The robot is modeled as a single point moving in a two-dimensional configuration space populated with visually opaque and transparent obstacles. The robot is equipped with proximity sensors, a vision-based recognition system, and a method of odometry, all of which have some uncertainty associated with their measurements. By using visually distinctive configurations of features in the world as natural landmarks, a series of local maps is constructed. The geometrical relationships between mutually visible landmarks are used to build a relational map from this collection of local maps. This representation forms the basis for a systematic exploration algorithm. The approach is implemented in simulation, and results are presented View full abstract»

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  • Concurrent product/process design with multiple representations of parts

    Publication Year: 1993 , Page(s): 298 - 304 vol.3
    Cited by:  Papers (1)  |  Patents (19)
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    The need for concurrency in design and manufacturing is supported in a sheet metal design system by doing preliminary process design at the detail product design stage. This design with features approach represents the evolving part form to the designer in multiple process domains and at multiple stages of a sequential process. Each part of part form representations defines the conceptualized process which transforms it from one to the other. At this modeling level, processes are reversible so that design activity can take place in any of the domains and be transferred to the others. This concept is fully implemented in a sheet metal design/manufacturing system in which preliminary process design occurs concurrently with product design and the normal representation ambiguities of wireframe and flat panel models are eliminated View full abstract»

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  • Models for diagnosing robot error sources

    Publication Year: 1993 , Page(s): 155 - 159 vol.2
    Cited by:  Papers (1)
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    The idea of using error models to predict the sources of the error in a machine is discussed. It is shown that the somewhat ad-hoc modeling methods used for robot calibration, although satisfactory for improving accuracy, are not useful for detecting the true causes of error. It is shown that even if only independent parameters are used in a model, they still may not represent the real error sources. If dependent parameters are used in the model the problem can be aggravated and these parameters may not even improve accuracy. To alleviate this problem, the error function is being proposed to represent errors. By proper attachment of the error function in a parametrically general calibration model, a complete model for machine error identification can be obtained View full abstract»

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  • Shape matching from grasp using a minimal representation size criterion

    Publication Year: 1993 , Page(s): 442 - 449 vol.1
    Cited by:  Papers (9)
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    A robust polynomial-time algorithm for model-based pose estimation from tactile grasp data is presented. A minimal representation criterion is used to formulate the matching problem as a global optimization. The hypothesize-and-test paradigm is invoked to search for the optimal solution. A three-on-three match of model features to data features is used to reduce the transform search space to polynomial size. A polynomial-time assignment algorithm is used to compute the optimal correspondence for each hypothesized pose. The strength of the algorithm lies in its ability to perform with noisy or incomplete data and with missing or spurious features. It is capable of rejecting outliers and finding partial matches, and it produces sensible results even in the presence of large noise. The algorithm has been implemented and tested on actual data View full abstract»

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  • Learning control of underwater robotic vehicles

    Publication Year: 1993 , Page(s): 106 - 111 vol.2
    Cited by:  Patents (1)
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    A learning control approach to an underwater robotic vehicle system using neural networks is described. The objective is to have a robust control system with respect to changes in the vehicle dynamics and parameters. It has been observed that dominant vehicle dynamics vary with the vehicle velocity and that the effect of thruster dynamics becomes significant at low velocity in the vehicle control system. When it is necessary to operate the vehicle at low velocity (e.g., stationkeeping and hovering), the effect of thruster dynamics must be considered in the vehicle control system design. Results of computer simulation for pitch and altitude vehicle motion show the effectiveness of the proposed control system View full abstract»

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  • Fast functional decomposition of sine-cosine-polynomials

    Publication Year: 1993 , Page(s): 980 - 987 vol.1
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    To solve the inverse kinematics problem in symbolic form it is necessary to determine the roots of so-called sine-cosine-polynomials (SC-polynomials). A functional decomposition of an SC-polynomial reduces this task to the solution of two equations of degree less than or equal to half of the original degree. Thus, decompositions can significantly improve symbolic solutions of the inverse kinematics problem. An earlier algorithm only detects a special type of decomposition, is of exponential complexity, and fails for complicated kinematical problems. The algorithm presented here finds all decompositions and reduces the complexity by magnitudes, thus satisfying all needs in kinematics. The algorithm is applicable as well to symbolic solutions of the direct position problem of parallel manipulators. By combination with the so-called specialized analysis technique, it is possible to scan all different symbolic solutions of any manipulator and to determine the particular solution that allows a maximum decomposition. This is an important step toward finding optimal symbolic solutions for kinematic equation systems View full abstract»

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  • Further progress in robot juggling: the spatial two-juggle

    Publication Year: 1993 , Page(s): 919 - 924 vol.3
    Cited by:  Papers (29)
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    A spatial two-juggle is discussed. The device has the ability to bat two freely falling balls into stable periodic vertical trajectories with a single three degree-of-freedom robot arm using a real-time stereo camera system for sensory input. After a brief review of a previously-reported one-juggle, the author's initial approach to the two-juggle planning and control problem is described. A number of important refinements to their initial strategy are given. Data from typical two-juggle runs in the laboratory are given View full abstract»

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  • Parallel VLSI architectures for real-time kinematics of redundant robots

    Publication Year: 1993 , Page(s): 870 - 877 vol.1
    Cited by:  Papers (8)
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    Architectures for the efficient computation of redundant manipulator kinematics (direct and inverse) are described. By doing the core calculations in hardware, full use can be made of the redundancy by implementing more complex self-motion algorithms. A key component of the architecture is the calculation in VLSI hardware of the singular value decomposition of the manipulator Jacobian. CORDIC arithmetic is used in the design of the special-purpose VLSI array, which is used in computation of the direct kinematics solution (DKS), the manipulator Jacobian, and the Jacobian pseudoinverse. Application-specific (subtask-dependent) portions of the inverse kinematics are handled in parallel by a DSP processor that interfaces with the custom hardware and the host machine. The architecture and algorithm development are valid for general redundant manipulators and a wide range of processors currently available and under development commercially View full abstract»

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  • Edge-based placement of camera and light source for object recognition and location

    Publication Year: 1993 , Page(s): 586 - 591 vol.2
    Cited by:  Papers (9)
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    The selection and placement of cameras and light sources for a vision task is an essential step in both autonomous visual sensing and standard industrial applications. A technique is presented that determines the three-dimensional region of light-source locations such that one or more specified object edges will be detected with a given edge operator. The method uses a task description that includes a list of object edges and the edge operator to be used in order to derive constraints on image contrast, surface irradiance, and light-source location. The combination of this method with prior results on camera and light-source placement can be applied to object recognition and location tasks View full abstract»

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  • Laserradar and sonar based world modeling and motion control for fast obstacle avoidance of the autonomous mobile robot MOBOT-IV

    Publication Year: 1993 , Page(s): 534 - 540 vol.1
    Cited by:  Papers (14)  |  Patents (1)
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    The obstacle avoidance mechanism of MOBOT-IV, which serves as a test platform within the scope of a research project on autonomous mobile robots for indoor applications is described. The mechanism utilizes heterogeneous information obtained from a laser radar and a sonar sensor system in order to achieve a reliable and complete world model for real-time collision avoidance. This world model is transformed by a motion control component into a virtual position deviation to perform obstacle avoidance by using a track-control algorithm View full abstract»

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  • A global analysis of following trajectories by redundant manipulators in the presence of obstacles

    Publication Year: 1993 , Page(s): 901 - 906 vol.3
    Cited by:  Papers (5)
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    A global solution is given for the following problem: Given a continuous trajectory defined in a robotic site containing obstacles, and given a redundant manipulator in the site, is the manipulator's end-effector able to track the trajectory? If yes, find all possible solutions (i.e., all feasible motions of the robot's structure producing a continuous displacement of the end-effector along the trajectory) in order to further optimize the task. If not, find the feasible parts of the trajectory. Instead of considering the pre-image of the trajectory in the robot's jointspace (which would involve handling n-dimensional spaces, where n is the number of degrees-of-freedom of the manipulator), the problem is stated in a (r+1)-dimensional space, where r is the degree of redundancy of the manipulator. Application examples are shown using 3-R planar manipulators View full abstract»

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  • A smooth robust nonlinear controller for robot manipulators with joint stick-slip friction

    Publication Year: 1993 , Page(s): 449 - 454 vol.3
    Cited by:  Papers (20)
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    The design of a smooth robust nonlinear controller for the regulation of an n-degree-of-freedom rigid robot with internal joint stick-slip friction is presented. It is shown that not only positioning accuracy, but also smoothness of motion is improved through nonlinear feedback. The Lyapunov direct method is employed to prove the global stability of the closed-loop system. The desired accuracy can be achieved by adjusting the parameters of the controller. The nonlinear compensator is robust with respect to the character of the slipping torque. Only the maximum static friction torque of the internal joint is required for controller design. The numerical implementation of this controller on a two-link robot is presented View full abstract»

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  • Multi-transducer sonar interpretation

    Publication Year: 1993 , Page(s): 392 - 397 vol.2
    Cited by:  Papers (6)
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    In response to difficulties with interpretation of data from narrow beam time-of-flight sonar for robotics, an algorithm for sonar interpretation that uses the entire return signals from several transducers with broad, overlapping fields of view is presented. The result is an algorithm that reconstructs the geometry in front of the robot with only a moderate amount of robot motion. Preliminary results with a three transducer system are shown. The results demonstrate an unusual ability to recover the presence of obstacles even when they are partially masked by closer obstacles. The quality of the reconstruction is limited by the small amplitude of the robot translational motions, by the return signal peak width, and by orientation dead-reckoning error on the robot View full abstract»

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  • The theory and methodology for concurrent design and planning of reconfiguration fixture

    Publication Year: 1993 , Page(s): 305 - 311 vol.3
    Cited by:  Papers (1)
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    A methodology for concurrent design and planning of adaptable fixture configuration and computer aided design of fixturing systems is presented. Emphasis is put on the analytical considerations involved in the optimization for the design of the locators, clamps, and supports. The accessibility/detachability condition, determination condition, and force-assemblability condition of positioning by a set of locators are derived for workpieces with smooth analytical surfaces and for prismatic components. The relative form closure is defined on the basis of geometrical reasoning, and is achieved in terms of locators and clamps. Difference performance indices are proposed in order to select the optimum placement for the locators, clamps and supports. An approach to examining the relative form closure conditions for fixturing systems is adopted based on the J-junction concept, and the corresponding procedure for computer aided planning systems including analysis and synthesis functions of fixturing systems is developed. Details of the definition and properties of the J-functions are given, together with their applications to geometrical reasoning using simplified examples of fixturing system design and configurations planning View full abstract»

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  • Integration of path planning, sensing and control in mobile robotics

    Publication Year: 1993 , Page(s): 243 - 248 vol.3
    Cited by:  Papers (1)  |  Patents (1)
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    Mobile MODRO is a modular mobile robot developed as a test platform for indoor applications at the Institute of Robotics in Zurich. The benchmark task for the modulator mobile robot is the distribution of internal mail in the new building of the Institute of Robotics. Progress thus far with respect to hardware, sensors and the software system is reported. The stability of the platform is considered in the presence of floor discontinuities. It is shown that it is possible to achieve near optimal steering and speed control. By considering noise sources and their propagation through an optical sensor, a model is derived for an amplitude modulated continuous wave lidar which produces range uncertainty information with each range estimate. At the highest level, efficient global and local path planning can be achieved using traditional search methods in combination with artificial neural network and fuzzy logic-based controllers View full abstract»

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  • Force control of an industrial PUMA 560 robot under environmental constraints: implementation issues and experimental results

    Publication Year: 1993 , Page(s): 213 - 218 vol.1
    Cited by:  Papers (4)
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    The problems of deformations occurring in a robot working in contact with the environment can be solved by taking into account forces exerted at the end-effector level. A solution to compensate for these deformations by using a force control scheme is given. The results, which are illustrated in the form of graphs, are obtained from experiments on a real robotic setup built around a PUMA 560 robot View full abstract»

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