A description is given of SPAR, a task planner that has been implemented on a PUMA 762. SPAR is capable of formulating manipulation plans to meet specified assembly goals; these manipulation plans include grasping and...
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A description is given of SPAR, a task planner that has been implemented on a PUMA 762. SPAR is capable of formulating manipulation plans to meet specified assembly goals; these manipulation plans include grasping and regrasping operations if they are deemed necessary for successful completion of assembly. SPAR goes beyond classical AI planners in the sense that SPAR is capable of solving geometric goals associated with high-level symbolic goals. Consequently, if a high-level symbolic goals. Consequently, if a high-level symbolic goal is on (A,B), SPAR can also entertain the geometric conditions associated with such a goal. Therefore, a simple goal such as on (A,B) may or may not be found to be feasible depending on the kinematic constraints implied by the associated geometric conditions. SPAR has available to it a user-defined repertoire of actions for solving goals and associated with each action is an uncertainty precondition that defines the maximum uncertainty in the world description that would guarantee the successful execution of that action. SPAR has been implemented as a nonlinear constraint posting planner.< >
Sparse tactile sensing can be used to determine the positions and orientations of objects if the objects are restricted to being of a particular class. Consideration is given to a simple example of exploiting class co...
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Sparse tactile sensing can be used to determine the positions and orientations of objects if the objects are restricted to being of a particular class. Consideration is given to a simple example of exploiting class constraints: finding the axis of an unknown surface of revolution. Three tactile curvature measurements on a surface of revolution with sweeping rule in C/sup 2/ are shown to be sufficient for determining the axis except for certain singular configurations. Position and orientation error bounds and preliminary experimental results are presented for a capacitive tactile sensor with two contacts. Optimal angular spacing was seen to be 90 degrees between contacts. Experiments showed that the method worked with a position error of 0.07 in. and an angle error of 7.3 degrees .< >
A methodology is developed for describing of hierarchical control of robot systems in a manner which is faithful to the underlying mechanics, structured enough to be used as an interpreted language, and sufficiently f...
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A methodology is developed for describing of hierarchical control of robot systems in a manner which is faithful to the underlying mechanics, structured enough to be used as an interpreted language, and sufficiently flexible to encompass a wide variety of systems. A consistent set of primitive operations which form the core of a robot system description and control language is presented. This language, motivated by the hierarchical organization of neuromuscular systems, is capable of describing a large class of robot systems under a variety of single-level and distributed control schemes.< >
An algorithm is described for planning the motions of several mobile robots which share the same workspace. Each robot is capable of independent translational motion in two dimensions, and the workspace contains polyg...
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An algorithm is described for planning the motions of several mobile robots which share the same workspace. Each robot is capable of independent translational motion in two dimensions, and the workspace contains polygonal obstacles. The algorithm computes a path for each robot which avoids all obstacles in the workspace as well as the other robots. It is guaranteed to find a solution if one exists. The algorithm takes a cell decomposition approach, where the decomposition used is based on the idea of a product operation defined on the cells in a decomposition of a two-dimensional free space. This algorithm is being implemented for the case of two robots as part of ongoing research into useful algorithms for task-level programming of the RobotWorld system.< >
An algorithm is presented for generating near-time-optimal trajectories for an open-kinematic-chain manipulator moving in a cluttered workspace. This is the first algorithm to guarantee bounds on the closeness of an a...
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An algorithm is presented for generating near-time-optimal trajectories for an open-kinematic-chain manipulator moving in a cluttered workspace. This is the first algorithm to guarantee bounds on the closeness of an approximation to a time-optimal trajectory. The running time and space required are polynomial in the desired accuracy of the approximation. The user may also specify tolerances by which the trajectories must clear obstacles in the workspace to allow modeling of control errors.< >
作者：
JOU, JYBOVIK, ACLaboratory for Vision Systems
Computer and Vision Research Center Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712-1084 USA
Techniques are described for improving the speed and accuracy of iterative visible-surface reconstruction algorithms. In particular, the importance of obtaining accurate early information is emphasized, both in the in...
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Techniques are described for improving the speed and accuracy of iterative visible-surface reconstruction algorithms. In particular, the importance of obtaining accurate early information is emphasized, both in the initial surface approximation and in the early localization of surface discontinuities. The first of these goals is attained using a simple technique known as constraint expansion , which yields a good initial approximation while accounting for detected discontinuities. The second goal is attained by using the locations of the image irradiance edges as a guide in locating potential discontinuities. Discontinuity detection in later stages of computation is augmented by a double-thresholding strategy and discontinuity backtracking.
作者：
CLARK, MBOVIK, ACLaboratory for Vision Systems
Computer and Vision Research Center Department of Electrical and Computer Engineering The University of Texas at Austin Austin TX 78712-1084 U.S.A
In this paper we apply a previously developed model of texture segmentation using multiple spatially and spectrally localized filters, known as Gabor filters, to the analysis of textures composed of elementary image f...
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In this paper we apply a previously developed model of texture segmentation using multiple spatially and spectrally localized filters, known as Gabor filters, to the analysis of textures composed of elementary image features known as textons. It is found that for regularly- or irregularly-spaced texton patterns, the segmentation approach works well, in the sense that it is in accordance with visual segmentation. Differences in texton spacing, size, orientation, and phase are all found to lead to successful segmentations.
The robust controller has very simple structures and can be divided into two separate parts: a servo controller and an auxiliary controller. The two controllers are designed independently. The function of the auxiliar...
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The robust controller has very simple structures and can be divided into two separate parts: a servo controller and an auxiliary controller. The two controllers are designed independently. The function of the auxiliary controller is to cancel out the plant uncertainties directly without the use of the high loop gain principle. Interpretation of robot controller as a signal-synthesis adaptive controller is given. Practical implementation issues of the auxiliary controller are discussed. Simulations of a design example with large parameter uncertainty, nonlinearity, and external disturbance are presented to demonstrate the effectiveness of the design technique. This technique is further tested with success in an experimental study of joint position control of a PUMA 560 robot arm.< >
Control of tool-workpiece interaction force is of vital importance in automated assembly. Using a simple linear continuous model of an edge-following system to predict the appropriate accomodation gains in a force con...
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Control of tool-workpiece interaction force is of vital importance in automated assembly. Using a simple linear continuous model of an edge-following system to predict the appropriate accomodation gains in a force control loop, previous work has shown that force control by accomodation is feasible. Following up this work, this paper describes the analysis, simulation and implementation of an adaptive force control in a two-dimensional edge-following task with a PUMA 560 robot and wrist force sensor. First, a discrete-time model of an edge-following system is developed and then used as the plant; second, a model reference adaptive control (MRAC) scheme is applied to achieve both tracking and regulation purposes. The reference (tracking) model can be determined by experimental reference input and desired model output information; the reference (regulation) model can be obtained by simulation to smooth out the plant output and improve the augmented filtered plant-model error. Study is done on the values of the adaptation gains in the adaptive mechanism, and hence can be adjusted to insure the best plant output performance.
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