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.
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.< >
The authors discuss a system, called AMP-CAD, which develops assembly motion plans using CAD models of parts. They place an emphasis on the calculation of the potential fields used for motion planning. Potential field...
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The authors discuss a system, called AMP-CAD, which develops assembly motion plans using CAD models of parts. They place an emphasis on the calculation of the potential fields used for motion planning. Potential fields can be thought of as a mechanism to interface CAD representations with plan development. AMP-CAD is a complete system that combines an assembly representation, a two-phase motion planner, and a execution unit into a single integrated package. Implementation and experimental results are discussed.< >
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.< >
A formulation that makes possible the integration of collision prediction and avoidance stages for mobile robots moving in general terrains containing moving obstacles is presented. A dynamic model of the mobile robot...
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A formulation that makes possible the integration of collision prediction and avoidance stages for mobile robots moving in general terrains containing moving obstacles is presented. A dynamic model of the mobile robot and the dynamic constraints are derived. Collision avoidance is guaranteed if the distance between the robot and a moving obstacle 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. A feedback control is developed and local asymptotic stability is proved if the velocity of the moving obstacle is bounded. Simulation results verify the value of the proposed strategy.< >
A common problem in robotic assembly is that of mating tightly fitting parts when the locations and the dimensions of the parts are somewhat uncertain. Because the clearances allowed between mating features of parts a...
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