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Robotics and Automation, IEEE Transactions on

Issue 1 • Date Feb. 1993

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Displaying Results 1 - 13 of 13
  • Comments on "Adaptive PD controller for robot manipulators

    Publication Year: 1993 , Page(s): 117 - 119
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    An alternative analysis that does not invoke the LaSalle invariance principle of the PD proportional-differential controller with gravity compensation for robots, presented in the above-titled paper by P. Tomei (ibid., vol.7, no.4, p.565-70, Aug. 1991) is established. The result is used to develop straightforwardly a new PD controller with adaptive gravity compensation, and conditions to ensure closed-loop stability and global zero position error convergence are given.<> View full abstract»

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  • Visual tracking of a moving target by a camera mounted on a robot: a combination of control and vision

    Publication Year: 1993 , Page(s): 14 - 35
    Cited by:  Papers (185)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1452 KB)  

    The authors present algorithms for robotic (eye-in-hand configuration) real-time visual tracking of arbitrary 3D objects traveling at unknown velocities in a 2D space (depth is given as known). Visual tracking is formulated as a problem of combining control with computer vision. A mathematical formulation of the control problem that includes information from a novel feedback vision sensor and represents everything with respect to the camera frame is presented. The sum-of-squared differences (SSD) optical flow is used to compute the vector of discrete displacements each instant of time. These displacements can be fed either directly to a PI (proportional-integral) controller or to a pole assignment controller or discrete steady-state Kalman filter. In the latter case, the Kalman filter calculates the estimated values of the system's states and the exogenous disturbances, and a discrete LQG (linear-quadratic Gaussian) controller computes the desired motion of the robotic system. The outputs of the controllers are sent to the Cartesian robotic controller. Performance results are presented View full abstract»

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  • Dynamic control of a manipulator with passive joints in operational space

    Publication Year: 1993 , Page(s): 85 - 93
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    A method for controlling a manipulator with passive joints, which have no actuators, in operational space is presented. The equation of motion is described in terms of operational coordinates. The coordinates are separated into active and passive components. The acceleration of the active components can be arbitrarily adjusted by using the coupling characteristics of manipulator dynamics. This method is also extended to path tracking control of a manipulator with passive joints. A desired path is geometrically specified in operational space. The position of the manipulator is controlled to follow the path. In this method, a path coordinate system based on the path is defined in operational space. The path coordinates consist of a component parallel to the path and components normal to the path. The acceleration of the components normal to the path is controlled according to feedback based on tracking error by using the dynamic coupling among the components. This in turn keeps the manipulator on the path. The effectiveness of the method is verified by experiments using a two-degree-of-freedom manipulator with a passive joint View full abstract»

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  • A practical approach to job-shop scheduling problems

    Publication Year: 1993 , Page(s): 1 - 13
    Cited by:  Papers (54)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1124 KB)  

    The use of Lagrangian relaxation to schedule job shops, which include multiple machine types, generic precedence constraints, and simple routing considerations, is explored. Using an augmented Lagrangian formulation, the scheduling problem is decomposed into operation-level subproblems for the selection of operation beginning times and machine types, with given multipliers and penalty coefficients. The multipliers and penalty coefficients are then updated at the higher level. The solution forms the basis of a list-scheduling algorithm that generates a feasible schedule. A procedure is also developed to evaluate the quality of this feasible schedule by generating a lower bound on the optimal cost. Numerical examples are taken from a representative industrial job shop. High-quality schedules are efficiently generated every other day over a three-week period, with costs generally within 4% of their respective lower bounds. The methodology compares favorably with knowledge-based scheduling View full abstract»

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  • Two-dimensional robot navigation among unknown stationary polygonal obstacles

    Publication Year: 1993 , Page(s): 96 - 102
    Cited by:  Papers (23)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    The authors describe an algorithm for navigating a polygonal robot, capable of translational motion, in an unknown environment. The environment contains stationary polygonal obstacles and is bounded by polygonal walls, all of which are initially unknown to the robot. The environment is learned during the navigation process by use of a laser range-finding device, and new knowledge is integrated with previously acquired information. A partial map of the environment, containing parts of the obstacles that were seen by the robot and the free space between them, is obtained. The obstacles in the map are transformed into a new set of expanded polygonal obstacles, allowing the robot to be treated as a point, and the navigation problem is reduced to point navigation among unknown polygonal obstacles. A navigation graph is built from the transformed obstacles and used to search for a piecewise linear path to the destination. The algorithm is proved to converge to the desired destination in a finite number of steps provided a path to the destination exists View full abstract»

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  • High-speed trajectory control of a direct-drive manipulator

    Publication Year: 1993 , Page(s): 102 - 108
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    High-speed precision trimming of three-dimensional parts using laser-cutting industrial robots is addressed. A control system for direct-drive manipulators specially designed for high-speed trajectory control applications is developed. The concept of decoupled and invariant dynamics is discussed for a specific manipulator, and a simple procedure for system identification and control system design is presented. It is demonstrated that, through proper arm mechanism design, the control system can be greatly simplified and satisfactory control performance achieved. The arm mechanism design and control system are evaluated through simulations and experiments. Experimental tracking performance achieves a speed of 3 m/s and an acceleration of 3.8 g, with a joint mean tracking error of 0.0556° View full abstract»

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  • A torque sensing technique for robots with harmonic drives

    Publication Year: 1993 , Page(s): 108 - 116
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    The authors propose a joint torque sensing technique making use of the existing structural elasticity of robots. The technique provides joint torque sensing without reducing the stiffness of the robot or changing the mechanical structure of the joints. The elasticity of the flexsplines of the harmonic drives is utilized to measure the joint torque. The flexsplines are flexible thin cups, made from steel, in the harmonic drives that are driven by the wave generators. A finite-element analysis of the flexsplines shows that a special configuration of strain gauges, mounted on the flexspline, has to be employed to eliminate errors in sensor information due to rotation of the wave generator. Characteristics of the torque sensor are examined experimentally. The linearity and the dynamic response are almost the same as those of a conventional sensing technique. For a one-link robot arm, both theoretical and experimental investigations support the validity of the sensing technique View full abstract»

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  • Bounds on the largest singular value of the manipulator Jacobian

    Publication Year: 1993 , Page(s): 93 - 96
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    It is proved that if the manipulator Jacobian is properly scaled, the largest singular value is bounded within a small interval close to unity. In this case, the inverse of the smallest singular value is a good estimate of the condition number. This is useful in singularity analysis. Bounds are derived for a general six-joint manipulator and for the ABB IRb 2000 industrial robot in a case study View full abstract»

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  • Performance evaluation of a class of M-estimators for surface parameter estimation in noisy range data

    Publication Year: 1993 , Page(s): 75 - 85
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (872 KB)  

    Depth maps are frequently analyzed as if the errors are normally, identically, and independently distributed. This noise model does not consider at least two types of anomalies encountered in sampling: a few large deviations in the data (outliers) and a uniformly distributed error component arising from rounding and quantization. The theory of robust statistics, which formally addresses these problems, is used in a robust sequential estimator (RSE) of the authors' design. The RSE assigns different weights to each observation based on maximum-likelihood analysis, assuming that the errors follow a t distribution which represents the outliers more realistically. This concept is extended to several well-known maximum-likelihood estimators (M-estimators). Since most M-estimators do not have a target distribution, the weights are obtained by a simple linearization and then embedded in the same RSE algorithm. Experimental results over a variety of real and synthetic range imagery are presented, and the performance of these estimators is evaluated under different noise conditions View full abstract»

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  • A high-resolution sensor based on tri-aural perception

    Publication Year: 1993 , Page(s): 36 - 48
    Cited by:  Papers (90)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1048 KB)  

    The authors present a high-resolution sensor composed of three ultrasonic sensors, one transmitter/receiver and two extra receivers, which allows a significant improvement in the information-extraction process. With this sensor the position (distance and bearing) of all isolated objects in an approximately 25° field of view can be determined using information contained in one single snapshot of a moderately complex scene. Within limits, the sensor system can also discriminate between different types of reflectors, in particular, walls and edges, based on their radius of curvature. These results are all based on the determination of the arrival times of the echoes present at the three receivers. A noise model that accounts for the measured variations of the arrival times is used to derive limits on the resolution of the results provided by the sensor. Based on this model it is shown that, to a large extent, the sensor results are impervious to measurement variations common to all three receivers. Results obtained in a realistic environment are compared with those obtained from a conventional time-of-flight sensor View full abstract»

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  • On single-scanline camera calibration

    Publication Year: 1993 , Page(s): 71 - 75
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    A method for calibrating single scanline CCD cameras is described. It is shown that the more classical 2D camera calibration techniques are necessary but not sufficient for solving the 1D camera calibration problem. A model for single scanline cameras is proposed, and a two-step procedure for estimating its parameters is provided. It is also shown how the extrinsic camera parameters can be determined geometrically without making explicit the intrinsic camera parameters. The accuracy of the calibration method is analyzed through an application example View full abstract»

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  • SCARF: a color vision system that tracks roads and intersections

    Publication Year: 1993 , Page(s): 49 - 58
    Cited by:  Papers (71)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1044 KB)  

    SCARF, a color vision system that recognizes difficult roads and intersections, is presented. It has been integrated into several navigation systems that drive a robot vehicle, the Navlab, on a variety of roads in many different weather conditions. SCARF recognizes roads that have degraded surfaces and edges with no lane markings in difficult shadow conditions. It also recognizes intersections with or without predictions from the navigation system. This is the first system that detects intersections in images without a priori knowledge of the intersection shape and location. SCARF uses Bayesian classification to determine a road-surface likelihood for each pixel in a reduced color image. It then evaluates a number of road and intersection candidates by matching an ideal road-surface likelihood image with the results from the Bayesian classification. The best matching candidate is passed to a path-planning system that navigates the robot vehicle on the road or intersection. The SCARF system is described in detail, results on a variety of images are presented, and Navlab test runs using SCARF are discussed View full abstract»

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  • Comparative experiments with a new adaptive controller for robot arms

    Publication Year: 1993 , Page(s): 59 - 70
    Cited by:  Papers (64)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1060 KB)  

    A model-based adaptive controller and proof of its global asymptotic stability with respect to the standard rigid-body model of robot-arm dynamics are presented. Experimental data from a study of one new and several established globally asymptotically stable adaptive controllers on two very different robot arms: (1) demonstrate the superior tracking performance afforded by the model-based algorithms over conventional PD control; (2) demonstrate and compare the superior performance of adaptive model-based algorithms over their nonadaptive counterparts; (3) reconcile several previous contrasting empirical studies; and (4) examine contexts that compromise their advantage 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