There are numerous applications in which robots are needed to assist rather than replace human operators. These applications typically involve either work in a dangerous environment or performing tasks that are physic...
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There are numerous applications in which robots are needed to assist rather than replace human operators. These applications typically involve either work in a dangerous environment or performing tasks that are physically impossible for humans to accomplish by themselves. Robots used in this mode do not need to be autonomous because they can essentially be controlled by the operator. Nonetheless, it is difficult for an operator to flawlessly control a robot with a large number of degrees of freedom. Therefore, an intelligent control system is needed to correct and improve the operator's input to the robot. In this paper the authors discuss a central component in this control system known as the variably-autonomous trajectory generator (VATG). The VATG combines input from the operator with input from one or more autonomous control modules (CM) to generate the robot trajectory. The amount of impact the autonomous CMs will have on the overall trajectory will depend on a number of factors such as the task being performed and the sensing modalities available, hence the authors refer to this type of control as being variably-autonomous.< >
Nonholonomic vehicles are shown to be kinematically equivalent to unicycles. A dynamic model for mobile vehicles moving on planar surfaces under nonholonomic constraints is derived. The model is decomposed into a kine...
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Nonholonomic vehicles are shown to be kinematically equivalent to unicycles. A dynamic model for mobile vehicles moving on planar surfaces under nonholonomic constraints is derived. The model is decomposed into a kinematic and a dynamic subsystem. The kinematic subsystem is shown to be globally stabilizable by using continuous control laws on reference trajectories that are nonstationary and continuously differentiable with respect to time. The continuity of the kinematic control inputs allows the extension of the vehicle control at the dynamic level. Stability of the overall closed loop system is examined using singular perturbation theory. Simulations verify all theoretical derivations.
General-purpose CAD-based inspection of a manufactured workpiece often involves comparing a part model created using intensity or range images of the part to a toleranced reference model of the part. Before this compa...
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General-purpose CAD-based inspection of a manufactured workpiece often involves comparing a part model created using intensity or range images of the part to a toleranced reference model of the part. Before this comparison can be made, however, the sensed object model must be registered to the reference object model. Most registration approaches assume that it is possible to identify and match features in the models and that the object models represent very similar geometries. A registration approach that deals with featureless dissimilar models is presented, and experimental results are demonstrated. Although the need for such an approach was motivated by needs in inspection, the approach is very general and can be used in a variety of other applications.< >
A robust polynomial-time algorithm for model-based pose estimation from tactile grasp data is presented. A minimal representation criterion is used to formulate the matching problem as a global optimization. The hypot...
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A robust polynomial-time algorithm for model-based pose estimation from tactile grasp data is presented. A minimal representation criterion is used to formulate the matching problem as a global optimization. The hypothesize-and-test paradigm is invoked to search for the optimal solution. A three-on-three match of model features to data features is used to reduce the transform search space to polynomial size. A polynomial-time assignment algorithm is used to compute the optimal correspondence for each hypothesized pose. The strength of the algorithm lies in its ability to perform with noisy or incomplete data and with missing or spurious features. It is capable of rejecting outliers and finding partial matches, and it produces sensible results even in the presence of large noise. The algorithm has been implemented and tested on actual data.< >
A class of Newton-type algorithms is effective in solving the kinematic path planning problem for a system with nonholonomic equality constraints. A key result in this approach has been the generic full rank condition...
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A class of Newton-type algorithms is effective in solving the kinematic path planning problem for a system with nonholonomic equality constraints. A key result in this approach has been the generic full rank condition of a certain gradient operator. We have extended this method to path planning problems with inequality constraints and shown its efficacy in solving some challenging problems, but a similar genericity result is not currently available. In this paper, we present some extension of our algorithm for nonholonomic path planning with equality and inequality constraints and show the generic full rank condition for a special case. Simulation examples involving a steerable tractor-trailer vehicle and experiment results of a quarter-scale car with a trailer are presented.< >
When the uncertainty is large compared to clearances between objects, some form of compliance is required for a robot to manipulate these objects. Such situations include, but are not restricted to, assembly operation...
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When the uncertainty is large compared to clearances between objects, some form of compliance is required for a robot to manipulate these objects. Such situations include, but are not restricted to, assembly operations. Compliance can be thought of as a task-dependent mapping from sensed forces to corrective motions which bring the robot closer to its goal. A methodology for the automated synthesis of this mapping is described. The possible erroneous configurations of the robot together with their resulting contact forces are computed, and a corrective motion is identified for each configuration. The validity of the mapping is checked to ensure that the sensed forces will provide unambiguous information during the actual execution of the planned compliant motion.< >
A system for exhaustively inspecting a workpiece, not merely certain features, is presented. The system is based on comparing a volumetric representation of a reference object to a volumetric representation of an actu...
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Faat procedures for computing fuzzy prozimity meaaurea between a multifingered robot hand and an object to be grasped are presented in this paper. The computation useful in graap planning and in analyzing the local be...
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In this paper, we present a complete and exact algorithm for planning a geometrically feasible path for a polyhedral subassembly (robot) translating amongst polyhedral obstacles. Our algorithm can be used to determine...
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In traditional geometric modeling, it is common to assume that models of objects created are complete and correct. Unfortunately in real life robots and other autonomous machines may have only uncertain knowledge of o...
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