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Robotics and Automation, IEEE Transactions on

Issue 2 • Date Apr 1992

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Displaying Results 1 - 12 of 12
  • An analog neural network solution to the inverse problem of `early taction'

    Page(s): 196 - 212
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1580 KB)  

    The authors examine an application of analog neural networks to low-level processing of tactile sensory data. In analogy to the term early vision, the authors call the first level of processing required in tactile sensing early taction. The problem of deblurring or deconvolution of data provided by an array of tactile sensors that is also assumed to be corrupted by noise is addressed. It is noted that this inverse problem is ill posed and that the technique of regularization may be used to obtain solutions. The theory of nonlinear electrical networks is utilized to describe energy functions for a class of nonlinear networks and to show that the equilibrium states of the proposed network correspond to regularized solutions of the deblurring problem. An entropy regularizer is incorporated into the energy function of the network for the recovery of normal stress distributions. An integrated circuit prototype of the proposed network is discussed View full abstract»

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  • Extrinsic calibration of a vision sensor mounted on a robot

    Page(s): 161 - 175
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    A vision sensor mounted on a robot to detect surrounding objects is discussed. Its mounting position and orientation must be identified, resulting in an extrinsic calibration problem. The author presents three classes of extrinsic calibration procedures. All use closed-form solutions. The class A calibration procedure requires a reference object at a recalibrated location. The class B calibration procedure takes advantage of robot mobility. It requires a reference frame, but not precalibration. The class C procedure, by taking full advantage of both robot mobility and dexterity, requires no reference object but the simplest one-a visible point. In simulation studies, the class A, B, and C calibration procedures have produced estimates successfully converging to true extrinsic parameter values. Results of field experiments carried out for class B and C calibration procedures are presented. For comparison, two existing B-type calibration methods have also been tested with real data View full abstract»

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  • Force-reflection and shared compliant control in operating telemanipulators with time delay

    Page(s): 176 - 185
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1020 KB)  

    Shared compliant control has been incorporated into an advanced six-degree-of-freedom force-reflecting telemanipulation system. With this system the authors have investigated the effect of time delay on human telemanipulation task performance. Time delays of between 2 and 4096 ms were introduced between master and slave arms, and high-precision peg-in-hole tasks were performed by six test operators with two modes of control: kinesthetic force feedback (KFF) and shared compliant control (SCC). Task performance was quantified in terms of the completion time (CT) and the sum of square forces (SOSF). The experimental results demonstrate the superiority of SCC over KFF for time-delayed telemanipulation. SCC has significantly lower rates of increase than KFF in both CT and SOSF with time delay. Only SCC enabled task performance at delays above 1 s. Constant force maintenance tasks were also performed to investigate the effect of time delay on the stability of force reflection. SCC also has beneficial effects on telemanipulation without time delay View full abstract»

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  • Inferring feasible assemblies from spatial constraints

    Page(s): 228 - 239
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1004 KB)  

    The authors treat two different problems in the analysis of assemblies, and algorithms are described for each. The first problem is the selection of consistent sets of part feature relationships, and it corresponds to a search over possible configurations of parts that are consistent with feature set mappings. The second problem is the evaluation of the kinematic consistency of an assembly that has been defined by consistent feature sets. These two problems are linked together as two of the steps required in a search for all correct assembly configurations of a given set of parts. Several of the other necessary steps related to part interference, path feasibility, and workcell device kinematics are referred to but not analyzed. The proposed search algorithm is based on a constraint posting strategy, i.e. rather than generating and testing all specific alternatives, chunks of the search space are progressively removed from consideration by constraints that rule them out until one satisfactory alternative is found View full abstract»

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  • An ultrasonic visual sensor for three-dimensional object recognition using neural networks

    Page(s): 240 - 249
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (964 KB)  

    By combining ultrasonic imaging with neural networks, the authors have developed a 3-D object recognition system for use in robotic vision. Ultrasonic imaging is used to calculate the initial 3-D images of the objects. These images are then passed to neural networks that identify object categories, estimate object locations, and improve 3-D images. The authors explain the 3-D ultrasonic imaging method, propose three neural network structures for 3-D image analysis, and demonstrate the practicability of the system through experimental results, which show that quick and accurate recognition can be achieved using only a small set of transducers View full abstract»

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  • A new model-based tracking controller for robot manipulators using trajectory pattern inverse dynamics

    Page(s): 279 - 285
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    A novel inverse-dynamic model-based tracking controller is presented. The inverse dynamics models are derived using the trajectory pattern method. The path of motion is divided into a number of relatively large segments, along which the motion is described by a selected trajectory pattern. The resulting inverse dynamics models are in the form of a summation of a fundamental sinusoidal time function and a number of its harmonics with constant coefficients. The coefficients are computed offline using analytical expressions that are derived for the selected trajectory pattern. The controller permits ultra-high-speed generation of the desired trajectory and feedforward signals. The online computations are minimal and can all be performed in parallel. The inverse-dynamic model of a spatial 3R manipulator is derived for a specified trajectory pattern. The controller structure and simulation results indicating its effectiveness are presented View full abstract»

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  • Digital shaping filters for reducing machine vibration

    Page(s): 285 - 289
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    A digital shaping filter used to shape the input to digitally controlled flexible plants is derived from an input preshaping technique to reduce residual vibration in the plant output. Results from simulations show that these filters reduce plant residual vibration to zero. In addition, an arbitrary rate digital shaping filter is derived that allows the user to select any sampling rate for the digital system. The examination of these filters in the digital Z domain reveals them to be digital notch filters that are robust to vibration-mode parameter shifts View full abstract»

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  • A real-time robot arm collision avoidance system

    Page(s): 149 - 160
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    A data structure and update algorithm are presented for a prototype real-time collision avoidance safety system simulating a multirobot workspace. The data structure is a variant of the octree, which serves as a spatial index. The authors use the N-objects octree, which indexes a collection of 3D primitive solids. These primitives make up the two seven-degree-of-freedom robot arms and workspace modeled by the system. Octree nodes containing mor than a predetermined number N of primitives are decomposed. This rule keeps the octree small, as the entire world model for the application can be implemented using a few dozen primitives. As robot arms move, the octree is updated to reflect their changed positions. Modification to the octree is rarely required. Incidents in which one robot arm comes too close to another arm or an object are reported. Cycle time for interpreting current arm joint angles, updating the octree to reflect new positions, and detecting/reporting imminent collisions averages 30 ns on an Intel 80386 processor running at 20 MHz View full abstract»

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  • Robot sensing techniques based on high-dimensional moment invariants and tensors

    Page(s): 186 - 195
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    A generalization of the concepts of moments and moment invariants to n-dimensions is presented. These concepts are used to develop techniques for object identification and attitude determination. Experimental results for these techniques are presented, and theoretical error analyses are developed View full abstract»

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  • Admittance matrix design for force-guided assembly

    Page(s): 213 - 227
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1276 KB)  

    The authors address the design of manipulator admittance for reliable force-guided assembly. Their goal is to design the admittance of the manipulator so that, at all possible bounded part misalignments, the contact forces always lead to error-reducing motions. If this objective can be accomplished for a given pair of mating parts, the parts are called force-assemblable. As a testbed application of manipulator admittance design for force-guided assembly, the authors investigate the insertion of a workpiece into a fixture consisting of multiple rigid fixture to be one for which there exists an admittance matrix that ensures the unique positioning of a workpiece despite initial positional error. It is shown that, in the absence of friction, all deterministic fixtures are linearly force-assemblable. How to design an admittance matrix that guarantees that the workpiece will be guided into the deterministic fixture by the fixel contact forces alone is shown View full abstract»

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  • Automated precision measurement of surface profile in CAD-directed inspection

    Page(s): 268 - 278
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB)  

    The authors present an optimal match scheme that aligns the measurement data with the design data in CAD-directed dimensional inspection. The principle of this scheme is to determine the actual measured points on the nominal surface by minimizing the sum of the squared distances of the measurement data from the surface with respect to the parameters of a rigid body transformation. Its computational efficiency and robustness against singularity are discussed. Two applications are examined. The first is determining the design coordinate system with respect to a machine coordinate system. The second is comparative analysis for precision measurement. For determining the design coordinate system, a sensitivity measure is proposed and confirmed experimentally. For error comparative analysis, a statistical model is developed to determine the minimum number of required measurement points so that the sampled points can closely represent the entire population View full abstract»

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  • Adaptive control of flexible-joint robots

    Page(s): 250 - 267
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1404 KB)  

    The problem of designing robust adaptive control strategies for a flexible-joint robot manipulator is considered. By utilizing the concept of integral manifolds, a corrected reduced-order model of the flexible system is obtained. Adaptive control schemes for the corrected reduced-order model are then developed that otherwise would have been difficult to obtain for the full-order flexible system due to ill conditioning and the curse of dimensionality. Zeroth-order singular perturbation results are generalized to include corrected adaptive control schemes. The result is a robust adaptive control law that takes both parametric and dynamic uncertainties into account. Two common adaptive control strategies, the adaptive inverse dynamics scheme and the Slotine and Li (1987) scheme, are examined. Numerical simulations for a two-link flexible-joint manipulator are carried out to illustrate the potential and advantages of the adaptive control schemes as compared to these two techniques 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