Dynamic segmentation is a method for improving the performance of cooperating tasks executed on loosely coupled multiprocessors. Four different data transfer techniques that can be used for intersegment data transfers...
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Dynamic segmentation is a method for improving the performance of cooperating tasks executed on loosely coupled multiprocessors. Four different data transfer techniques that can be used for intersegment data transfers in dynamically segmented buses are analyzed. Preemptive data transfers are considered for uniform message latencies and results are provided for message latency comparisons using various locality factors. These results indicate dynamic segmentation improves performance considerably, at a fraction of the cost of more complex interconnection networks such as multiple buses.< >
A description is given of research efforts directed towards the development of an active exploration system performing acquisition, processing, and integration of sensory inputs from vision, point laser range, tactile...
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A description is given of research efforts directed towards the development of an active exploration system performing acquisition, processing, and integration of sensory inputs from vision, point laser range, tactile, and force/torque sensors. An attempt is made to bring out the rationale that robotic workcell exploration can benefit by utilizing noncontact (e.g., vision, range, and proximity) as well as contact (e.g., tactile and force/torque) sensors while accomplishing tasks such as object identification, object localization, object grasping and object manipulation. The experimental results presented indicate that the rationale utilized in the design of the multisensory robotic active exploration scheme can work successfully.< >
A new approach to solving the collision detection problem for mobile robots in the presence of moving obstacles is proposed. Both the robot and obstacles in the two-dimensional space are assumed to be polygonal and ar...
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A new approach to solving the collision detection problem for mobile robots in the presence of moving obstacles is proposed. Both the robot and obstacles in the two-dimensional space are assumed to be polygonal and are composed of a set of convex polygons. The half-plane representation uses an algebraic method to describe the object motion including translation and rotation through time. Compared with previous methods, the proposed representation is more general in that obstacles are now allowed to move at nonconstant velocities. To detect collision between polygonal objects, a traversability vector method was developed. Traversability vectors are a simple mechanism used to analyze geometric constraints imposed by polygons. Using these vectors, a simple algorithm for predicting collision is derived. computer simulations were conducted to show the feasibility of the proposed method.< >
The authors present a knowledge-based image description system that uses fractal features. A knowledge-based recognition process is incorporated in this natural scene description system to enhance the capability of na...
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The authors present a knowledge-based image description system that uses fractal features. A knowledge-based recognition process is incorporated in this natural scene description system to enhance the capability of natural scene understanding. The scene description system is based on a fractal model. The fractal model provides useful information. A set of fractal features was developed from the fractal model which can effectively be used in image segmentation. After an image is divided into many regions based on fractal features, the scene information is derived with a knowledge-based scene recognition process. The structure of this system and its interaction strategy for the extraction of scene description are presented. The experimental results are also discussed.< >
A reference force-tracking impedance control system is proposed, consisting of a conventional impedance controller in the inner-loop and a trajectory modifying controller in the outer-loop for force-tracking. The desi...
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A reference force-tracking impedance control system is proposed, consisting of a conventional impedance controller in the inner-loop and a trajectory modifying controller in the outer-loop for force-tracking. The design of the outer-loop is presented and the stability of the two-loop control system is analyzed. A computationally efficient control algorithm for the inner-loop is suggested. Simulation results are presented. The controller is able to achieve excellent position and force-tracking with unknown environment stiffness and the presence of a burr on the tracking surface.< >
A novel method for solving the motion planning problem in the presence of moving obstacles is presented. Compared to previous approaches, the proposed method is more general in that obstacles are allowed to move with ...
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A novel method for solving the motion planning problem in the presence of moving obstacles is presented. Compared to previous approaches, the proposed method is more general in that obstacles are allowed to move with translation and rotation at nonlinear velocity. Using path/velocity decomposition, the method emphasizes the development of an efficient algorithm for collision detection between the robot and moving polygons. This algorithm is devised using transversability vector theory to determine the geometric relationships between any two convex polygons or convex components of concave polygons. The interference between the robot and the moving obstacles is detected and registered on the constraint map to represent time constraints on the robot's motion along the path. The constraint map is then used for velocity planning using a simple algorithm. The problem of a robot crossing the street is used as an example for computational analysis.< >
A hierarchical stereo system is described that uses structural descriptions up to the surface level. Surface descriptions are computed from monocular images, by using a perceptual grouping technique. Occlusion can be ...
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A hierarchical stereo system is described that uses structural descriptions up to the surface level. Surface descriptions are computed from monocular images, by using a perceptual grouping technique. Occlusion can be a major problem in stereo analysis and is often not treated explicitly. An analysis is presented of occlusion effects in stereo, and it is shown how structural descriptions can be used to deal with them. Experimental results are given for scenes with curved objects and significant occlusions.< >
The reduction of the state space of generalized stochastic Petri net (GSPN) models is discussed. For a certain class of GSPNs it is possible to analyze subnets in isolation by keeping the number of tokens in the net c...
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The reduction of the state space of generalized stochastic Petri net (GSPN) models is discussed. For a certain class of GSPNs it is possible to analyze subnets in isolation by keeping the number of tokens in the net constant. The authors construct a flow equivalent net (FEN), which has the same temporal and input/output properties of the original net, but with a strongly reduced state space. The FEN is substituted back into the complement of the original net.< >
A study is made of the servomechanism problem in unknown stable nonlinear systems. With a neural network as an identifier of the input-output characteristics of the plant, an error-feedback controller that achieves tr...
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A study is made of the servomechanism problem in unknown stable nonlinear systems. With a neural network as an identifier of the input-output characteristics of the plant, an error-feedback controller that achieves tracking with all states remaining bounded is designed. The controller is applicable to uncertain systems.< >
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