Probability density functions (PDFs) are derived for many of the geometric measurements upon which stereo matching techniques are based, including orientation differences between matching line segments or curves, the ...
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Probability density functions (PDFs) are derived for many of the geometric measurements upon which stereo matching techniques are based, including orientation differences between matching line segments or curves, the gradient of disparity, the directional derivative of disparity, and disparity differences between matches. The PDFs resulting from the transformations are used to critically examine many existing stereo techniques. Several techniques based on these PDFs are proposed.< >
Fast procedures for computing fuzzy proximity measures between a multifingered robot hand and an object to be grasped are presented. T.N. Nguyen and H.E. Stephanou (1990) presented a fuzzy approach for prehension, ide...
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Fast procedures for computing fuzzy proximity measures between a multifingered robot hand and an object to be grasped are presented. T.N. Nguyen and H.E. Stephanou (1990) presented a fuzzy approach for prehension, identified sources of fuzziness, and proposed a fuzzy algorithm for multifingered prehension. These ideas are extended by assuming fuzziness in the object location and geometric hand configuration, computing information on proximity of the hand and object, analyzing the computational efficiencies, and indicating how geometric information can be used in the process of prehension. The implementation details are outlined. The computation is useful in grasp planning and in analyzing the local behavior of the robot hand in the vicinity of the object.< >
A system for exhaustively inspecting a workpiece, not merely certain features, is presented. The system is based on comparing a volumetric representation of a reference object to a volumetric representation of an actu...
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A system for exhaustively inspecting a workpiece, not merely certain features, is presented. The system is based on comparing a volumetric representation of a reference object to a volumetric representation of an actual object iteratively created from sensor data. The use of volumetric representations gives this approach a number of distinct advantages over the more traditional boundary-based inspection methods. The method is capable of handling arbitrarily complex geometries and does not rely on the identification of features. It lends itself naturally to a multisensor environment, and facilitates true 3-D inspection as opposed to methods that require dimensional reductions of data by projection onto a 2-D plane. The authors focus on an important aspect of volumetric inspection which is the automatic generation of a sequence of sensor operations that will acquire the complete geometry of the object being inspected.< >
The kinematic path planning problem of a nonholonomic system can be posed as a point-to-point control problem of a nonlinear system. This system has the property that it is not locally stabilizable but is globally con...
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The kinematic path planning problem of a nonholonomic system can be posed as a point-to-point control problem of a nonlinear system. This system has the property that it is not locally stabilizable but is globally controllable. In this paper, we present a new algorithm for constructing a feasible path between specified initial and final configurations. Polyhedral constraints in both configuration and non-configuration spaces (possibly non-convex) can also be incorporated in this framework. The algorithm is based on the assumption that the system is usually controllable about a non-trivial trajectory, which is true for many cases. An initial trajectory is iteratively warped until the desired final configuration is reached. Examples of a front-wheel driven car, and tractors with one, two, and three trailers are included to illustrate the efficacy of the proposed algorithm.
A complete dynamic model of mobile vehicles moving on nonplanar surfaces under nonholonomic and dynamic constraints is presented. The kinematic control of such systems is examined, and the invariant manifold technique...
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A complete dynamic model of mobile vehicles moving on nonplanar surfaces under nonholonomic and dynamic constraints is presented. The kinematic control of such systems is examined, and the invariant manifold technique is introduced for steering a nonholonomic mobile vehicle to an invariant manifold which is relatively locally-locally controllable. A closed-loop control strategy based on the invariant manifold technique is formulated and applied to the control of nonholonomic vehicles. Tracking control of such vehicles is demonstrated with both holonomic and nonholonomic reference trajectories.< >
An optimal control formulation of the problem of collision avoidance of mobile robots moving in general terrains containing moving obstscles is presented. A dynamic model of the mobile robot and the dynamic constraint...
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An optimal control formulation of the problem of collision avoidance of mobile robots moving in general terrains containing moving obstscles is presented. A dynamic model of the mobile robot and the dynamic constraints are derived. Collision avoidance is guaranteed if the minimum distance between the robot and the objects is nonzero. A nominal trajectory is assumed to be known from off-line planning. The main idea is to change the velocity along the nominal trajectory so that collisions are avoided. Furthermore, time consistency with the nominal plan is desirable. A numerical solution of the optimization problem is obtained. A perturbation control type of approach is used to update the optimal plan. Simulation results verify the value of the proposed strategy.
The authors utilize a class of Petri nets, called colored Petri nets (C/P-nets), to induce patterns of behavior in synchronization structures. These patterns of behavior locally specify the interactions between the di...
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The authors utilize a class of Petri nets, called colored Petri nets (C/P-nets), to induce patterns of behavior in synchronization structures. These patterns of behavior locally specify the interactions between the distributed system's processes. The induction of patterns of behavior in synchronization structures results in the specification of coordination structures. A coordination structure is a specification of the interaction behavior of a distributed system's processes in a particular context. C/P-nets are used for the differentiation of the system's context-sensitive variables and the representation of their instantiations. The three possible interactions between any two concurrent processes of the distributed system are specified.< >
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