An assembly is defined by a configuration of parts of known geometries subject to tolerances in the pose, dimensions, and mating relations among part features. Using a tolerance model based on matrix transforms and Ga...
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An assembly is defined by a configuration of parts of known geometries subject to tolerances in the pose, dimensions, and mating relations among part features. Using a tolerance model based on matrix transforms and Gaussian models of geometric variations, the pose and dimensional tolerance models are considered as a priori models of the assembly with nominal and variational components for both position and orientation. The mating relations are regarded as linear relational constraints, also with nominal and variational components. With this formulation, estimation of the configuration of parts may be posed as a maximum likelihood problem and solved by a Kalman filter algorithm. The resulting maximum likelihood configuration of the assembly may be used to evaluate the required deviation from nominal and the assemblability as defined by the maximum likelihood clearance from constraints. In addition, application of the technique to intermediate subassemblies may be used to evaluate assemblability of specific steps and discriminate among alternative assembly sequence plans.
We describe laboratory experiments, in which tactile data obtained from the finger-tips of a robot hand, while it is holding an object in front of a calibrated camera, is fused with the vision data from the camera, to...
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We describe laboratory experiments, in which tactile data obtained from the finger-tips of a robot hand, while it is holding an object in front of a calibrated camera, is fused with the vision data from the camera, to determine the object identity, pose, and the touch and vision data correspondences. The touch data is incomplete due to required hand configurations, while nearly half of the vision data are spurious due to the presence of the hand in the image. Using either sensor alone results in ambiguous or incorrect interpretations. A minimal representation size framework is used to formulate the multisensor fusion problem, and can automatically select the object class, correspondence (data subsamples), and pose parameters. The experiments demonstrate that it consistently finds the correct interpretation, and is a practical method for multisensor fusion and model selection.
For pt.I see ibid., p.3726-30. Our work has been focused on developing a methodology for process control of bulk deformation-specifically, extrusion. In Part I, we developed a dynamical system model which could be use...
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For pt.I see ibid., p.3726-30. Our work has been focused on developing a methodology for process control of bulk deformation-specifically, extrusion. In Part I, we developed a dynamical system model which could be used for real-time applications. In this paper, we use this model development plus output relationships from our previous model development work (1995, 1996) to develop parameter identification and open-loop control methodologies. An example with plant trial data is provided.
Our work has been focused on developing a methodology for process control of bulk deformation-specifically, extrusion. A process model is required for control. The difficulties with currently available models are stat...
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Our work has been focused on developing a methodology for process control of bulk deformation-specifically, extrusion. A process model is required for control. The difficulties with currently available models are stated. An appropriate decomposition and associated assumptions are introduced, permitting construction a real-time process model via spectral approximation to solve the axi-symmetric, 2D transient heat conduction equation with heat generation and loss. This solution, simulation results, and model execution times are provided.
This paper deals with the problem of finding a mobile robot path on an unknown world environment. It is desired that the robot navigates to a known goal-region without colliding with physical obstracles. A learning ap...
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This paper deals with the problem of finding a mobile robot path on an unknown world environment. It is desired that the robot navigates to a known goal-region without colliding with physical obstracles. A learning approach will be presented for this purpose. It is supposed that the root has no initial map of Its environment. The robot uses its own infrared distance-sensors to detect obstacles present on its path. Simulation results will be presented that validate the effectiveness of the approach, where, besides detecting obstacles, the only other initial robot's ability is to perform straight-line motions.
In this paper we describe the implementation of real-time binocular gaze control. This implementation is performance by using a complex binocular active vision system. In addition real-time vergence is also implemente...
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In this paper we describe the implementation of real-time binocular gaze control. This implementation is performance by using a complex binocular active vision system. In addition real-time vergence is also implemented. Vergence and gaze control are implemented based on binocular optical flow. Vergence control is implemented based on optical flow disparity, using the horopter as a reference. A Kalman filter is used to filter out the signals and compensate for the delays of the system.
This paper presents a novel time-based visual motion cue called the Hybrid Visual Threat Cue (HVTC) that provides some measure for a change in relative range as well as absolute clearances, between a 3D surface and a ...
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This paper presents a novel time-based visual motion cue called the Hybrid Visual Threat Cue (HVTC) that provides some measure for a change in relative range as well as absolute clearances, between a 3D surface and a moving observer. It is shown that the HVTC is a linear combination of Time-To-Contact (TTC), visual looming and the Visual Threat Cue (VTC). The visual field associated with the HVTC can be used to demarcate the regions around a moving observer into safe and danger zones of varying degree, which may be suitable for autonomous navigation tasks. The HVTC is independent of the 3D environment and needs almost no a-priori information about it. It is rotation independent, and is measured in ~time/sup -1/\ units Several approaches to extract the HVTC, are suggested. Also a practical method to extract it from a sequence of images of a 3D textured surface obtained by a visually fixating, fixed-focus monocular camera in motion is presented. This approach of extracting the HVTC is independent of the type of 3D surface texture and needs no optical flow information, 3D reconstruction, segmentation, feature tracking.
In many industrial applications such as autonomous vehicle guidance and robotic manipulations, reliable 3-D informations must be extracted from the scene in order to provide a robust description of the environment in ...
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In many industrial applications such as autonomous vehicle guidance and robotic manipulations, reliable 3-D informations must be extracted from the scene in order to provide a robust description of the environment in which the system evolves. This paper presents the TRID sensor, a simple, fast, robust and accurate 3-D sensing device based on the Biris technology. TRID is limited to a lateral resolution of one point. Experimental results show that an accuracy better than 0.15% can be obtained for the depth component (Z) of 3-D points at a distance of 1.3 meter from a wooden black painted beam surface with an acquisition rate of 8.5 points/s.
The passivity property of dissipative mechanical structures has long been exploited in designing passive controllers that provide robust stability even in the presence of unmodeled dynamics of the system. For an input...
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The passivity property of dissipative mechanical structures has long been exploited in designing passive controllers that provide robust stability even in the presence of unmodeled dynamics of the system. For an input/output map of a flexible structure to be passive, collocation of the actuators and sensors is required and also the sensors should measure the velocity of the system. The so-called smart structures frequently have more sensors than actuators. Therefore, the passive controller can at best utilize only a subset of the sensors. In this paper we consider the design of a squaring down matrix which would render a system passive subject to some additional performance considerations. The problem of obtaining the synthesized passive output is cast as a set of linear matrix inequalities (LMIs) which can be efficiently solved by the LMI Toolbox in Matlab. We apply this procedure with the assumption that the sensors provide both displacement and velocity information which is generally not true. We show that the passive controllers can be implemented without the use of velocity information. By using synthesized passive outputs in addition to naturally occurring passive outputs, we obtain better system performance. We present experimental results involving a single flexible beam with torque input and hub angular position and strain gage outputs.
This article presents two algorithems, that can be used for minimising the effects of mobile robot control-space quantisation errors. The first algorithem can be used to perform pure rotations (no translation) of the ...
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This article presents two algorithems, that can be used for minimising the effects of mobile robot control-space quantisation errors. The first algorithem can be used to perform pure rotations (no translation) of the mobile robot while minimising the effects of these errors. The second algorithem can be used to perform straight-line motions, between the mobile robot current position, and a predefined goal position in its working environment. Simulation results demonstrating the effectiveness of the algorithem will be presented.
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