Visual servoing is a mode of navigation in which the motion of a robot vehicle is controlled through servoing on visual cues. Many visual servoing behaviors can be achieved using direct 2-D image cues, without requiri...
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To maximize productivity and safety, and to reduce maintenance costs, Space Station Freedom (SSF) must take advantage of advanced telerobotic technologies. The Robotic Systems Technology Branch a t the NASA Lyndon B. ...
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Postural control is of utmost importance for walking robots, particularly for those that traverse rugged terrain. A dynamic model for locomotion in rugged terrain is presented. The model has 18 actuated degrees of fre...
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Postural control is of utmost importance for walking robots, particularly for those that traverse rugged terrain. A dynamic model for locomotion in rugged terrain is presented. The model has 18 actuated degrees of freedom, plus six unactuated body translations and rotations to produce a total of 24 degrees of freedom. Nonlinear foot-terrain interaction models keep track of nonconservative soil deformations, and allow feet to make or break contact any number of times during a simulation. The utilization of this model for postural control studies is presented. A modification of the vertical hybrid control by allocation method is proposed as a viable postural control scheme. However, it is shown that positional control is sufficient in order to achieve stable response with the mechanism.< >
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.
Multilayer perceptrons (MLP) trained with backpropagation algorithm are popular because they offer certain desirable features. However, the training is time consuming which further limits its use in changing environme...
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Multilayer perceptrons (MLP) trained with backpropagation algorithm are popular because they offer certain desirable features. However, the training is time consuming which further limits its use in changing environment. We propose a methodology to partially designs MLP network using formal knowledge-rules and augmenting it with another neural network trained using labeled examples. The approach has the potential of reducing the training time and enables online changes in the user environment. The software developed is being used in a process control system.
The scenarios presented in this paper were selected by the AIAA Space Automation and robotics Committee on Standards to expose key technical issues which must be addressed in order to establish engineering guidelines ...
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A control system architecture is described for an autonomous flying vehicle. The vehicle, equipped with fourteen sensors, uses a model helicopter as an airframe. The control system utilizes these sensors to: remain al...
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A control system architecture is described for an autonomous flying vehicle. The vehicle, equipped with fourteen sensors, uses a model helicopter as an airframe. The control system utilizes these sensors to: remain aloft and in stable flight; navigate to a target; and manipulate a physical object. The overall approach to the problem is based on a behavioral paradigm. The key contribution of this paper is the demonstration of a situated agent under these severe circumstances; as the craft is airborne, it is in constant risk of crashing. Unlike terrestrial mobile robots, the craft must constantly make sound decisions to maintain its integrity.
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.< >
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