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.< >
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.< >
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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The authors develop a methodology for reasoning about the state of the environment based on evidence received from some source. It is assumed that the evidence is expressed as a probability mass function defined on a ...
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The authors develop a methodology for reasoning about the state of the environment based on evidence received from some source. It is assumed that the evidence is expressed as a probability mass function defined on a discrete set of mutually exclusive hypotheses about the state of the environment. Given that the quality of the evidence is variable, it follows that the precision of the reasoning process must also vary. That is, the level of specificity and the certainty associated with decisions made at that level depend directly on the quality of the evidence. An indistinguishability measure is used to generate a core set of aggregate focal elements, each of which may consist of logical disjunctions of the basic hypothesis set. The measure takes into account both the differences in support levels for the hypotheses and the degree to which they are similar. Partial dominance is then used to associate a basic probability assignment on the core set. This approach makes it possible to apply simple, quantitative methods to express the variations in the precision associated with decisions. The result is a set of aggregate hypotheses and their support levels which become input to the classification process. In most cases, multiple sets of aggregate hypotheses will be used in an evidential classification scheme to produce a composite characterization of the environment.< >
The intelligent coordination of multiple robots requires modularization of robots at some level higher than the joint, corresponding task representations, and a concept of time that allows the dynamic specification of...
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The intelligent coordination of multiple robots requires modularization of robots at some level higher than the joint, corresponding task representations, and a concept of time that allows the dynamic specification of task synchronization. The necessary representations of robots and tasks are developed, and the structural and operational semantics of the primitive task and reflex models are specified. A concept of time, called functional time-dependency, that allows the dynamic specification of the distributed semantics during task execution by multiple robots is developed. The utility of functional time-dependency is shown using two examples.< >
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