We introduce a novel proximity query, called connection collision query (CCQ), and use it for efficient and exact local planning in sampling-based motion planners. Given two collision-free configurations, CCQ checks w...
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ISBN:
(纸本)9783642174513
We introduce a novel proximity query, called connection collision query (CCQ), and use it for efficient and exact local planning in sampling-based motion planners. Given two collision-free configurations, CCQ checks whether these configurations can be connected by a given continuous path that either lies completely in the free space or penetrates any obstacle by at most E, a given threshold. Our approach is general, robust, and can handle different continuous path formulations. We have integrated the CCQ algorithm with sampling-based motion planners and can perform reliable local planning queries with little performance degradation, as compared to prior methods. Moreover, the CCQ-based exact local planner is about an order of magnitude faster than prior exact local planning algorithms.
This paper considers the problem of planning sensor observations for a network of overhead sensors which will resolve ambiguities in the output of a horizontal sensor network. Specifically, we address the problem of c...
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ISBN:
(纸本)9783642003110
This paper considers the problem of planning sensor observations for a network of overhead sensors which will resolve ambiguities in the output of a horizontal sensor network. Specifically, we address the problem of counting the number of objects detected by the horizontal sensor network, using the overhead network to aim at specific areas to improve the count. The main theme of our results is that, even though observation planning is intractable for such a network, a simple, greedy algorithm for controlling the overhead sensors guarantees performance with bounded and reasonable suboptimality. Our results are general and make few assumptions about the specific sensors used. The techniques described in this paper can be used to plan sensor aims for a wide variety of sensor types and counting problems.
Motion planning problems encountered in manipulation and legged locomotion have a distinctive multi-modal structure, where the space of feasible configurations consists of intersecting submanifolds, often of different...
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ISBN:
(纸本)9783642003110
Motion planning problems encountered in manipulation and legged locomotion have a distinctive multi-modal structure, where the space of feasible configurations consists of intersecting submanifolds, often of different dimensionalities. Such a feasible space does not possess expansiveness, a property that characterizes whether planning queries can be solved efficiently with traditional probabilistic roadmap (PRM) planners. In this paper we present a new PRM-based multi-modal planning algorithm for problems where the number of intersecting manifolds is finite. We also analyze the completeness properties of this algorithm. More specifically, we show that the algorithm converges quickly when each submanifold is individually expansive and establish a bound on the expected running time in that case. We also present an incremental variant of the algorithm that has the same convergence properties, but works better for problems with a large number of submanifolds by considering subsets of submanifolds likely to contain a solution path. These algorithms are demonstrated in geometric examples and in a legged locomotion planner.
We present a novel constraint-based motion interpolation algorithm to improve the performance of local planners in sample-based motion planning. Given two free-space configurations of a robot, our algorithm computes a...
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ISBN:
(纸本)9783642003110
We present a novel constraint-based motion interpolation algorithm to improve the performance of local planners in sample-based motion planning. Given two free-space configurations of a robot, our algorithm computes a one-dimensional trajectory subject to distance constraints between the closest features of the robot and the obstacles. We derive simple and closed form solutions to compute a path that guarantees no collisions between these closest features. The resulting local planner is fast and can improve the performance of sample-based planners with no changes to the underlying sampling strategy. In practice, we observe speedups on benchmarks for rigid robots with narrow passages.
We present fast methods for separating the direct and global illumination components of a. scene measured by a camera and illuminated by a light source. In theory, the separation can be done with just two images taken...
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ISBN:
(纸本)9783642147432
We present fast methods for separating the direct and global illumination components of a. scene measured by a camera and illuminated by a light source. In theory, the separation can be done with just two images taken with a high frequency binary illumination pattern and its complement. In practice, a larger number of images are used to overcome the optical and resolution limitations of the camera and the source. The approach does not require the material properties of objects and media in the scene to be known. However, we require that the illumination frequency is high enough to adequately sample the global components received by scene points. We present separation results for scenes that include complex interreflections, subsurface scattering and volumetric scattering. The computed direct and global images provide interesting insights into how real-world objects interact with light as well as optically interact with each other (hence the term "visual chatter"). All the measurement results reported here, as well as several others, can be viewed as high resolution images at hit]) / /***/CAVE/projects/separation/***
Replanning is a powerful mechanism for controlling robot motion under hard constraints and unpredictable disturbances, but it involves an inherent tradeoff between the planner's power (e.g., a planning horizon or ...
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ISBN:
(纸本)9783642174513
Replanning is a powerful mechanism for controlling robot motion under hard constraints and unpredictable disturbances, but it involves an inherent tradeoff between the planner's power (e.g., a planning horizon or time cutoff) and its responsiveness to disturbances. We present a real-time replanning technique that uses adaptive time stepping to learn the amount of time needed for a sample-based motion planner to make monotonic progress toward the goal. The technique is robust to the typically high variance exhibited by planning queries, and we prove that it is asymptotically complete for a deterministic environment and a static objective. For unpredictable environments, we present an adaptive time stepping contingency planning algorithm that achieves simultaneous safety-seeking and goal-seeking motion. These techniques generate responsive and safe motion in simulated scenarios across a range of difficulties, including applications to pursuit-evasion and aggressive collision-free teleoperation of an industrial robot arm in a cluttered environment.
A whole body tactile skin with a novel design is presented. It is installed on the entire surface of our adult-size humanoid robot. Experiments on various contact motion control, such as handling a 66kg human dummy, a...
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ISBN:
(纸本)9783642147432
A whole body tactile skin with a novel design is presented. It is installed on the entire surface of our adult-size humanoid robot. Experiments on various contact motion control, such as handling a 66kg human dummy, are realized.
This paper introduces a problem in which an agent (robot, human, or animal) travels among obstacles and binary detection beams. The task is to determine the possible agent path based only on the binary sensor data. Th...
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ISBN:
(纸本)9783642003110
This paper introduces a problem in which an agent (robot, human, or animal) travels among obstacles and binary detection beams. The task is to determine the possible agent path based only on the binary sensor data. This is a basic filtering problem encountered in many settings, which may arise from physical sensor beams or virtual beams that are derived from other sensing modalities. Methods are given for three alternative representations: 1) the possible sequences of regions visited, 2) path descriptions up to homotopy class, and 3) numbers of times winding around obstacles. The solutions are adapted to the minimal sensing setting;therefore, precise estimation, distances, and coordinates are replaced by topological expressions. Applications include sensor-based forensics, assisted living, security, and environmental monitoring.
Primary challenges in the building of untethered submillimeter sized robots include propulsion methods, power supply, and control. We present a novel type of microrobot called MagMite that utilizes a new class of wire...
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ISBN:
(纸本)9783642001956
Primary challenges in the building of untethered submillimeter sized robots include propulsion methods, power supply, and control. We present a novel type of microrobot called MagMite that utilizes a new class of wireless resonant magnetic micro-actuator that accomplishes all three tasks. The term MagMite is derived from Magnetic Mite-a tribute to the underlying magnetic propulsion principle and the micro-scale dimensions of the robot. The device harvests magnetic energy from the environment and effectively transforms it into inertia- and impact-driven mechanical force while being fully controllable. It can be powered and controlled with oscillating fields in the kilohertz range and strengths as low as 2 mT, which is only roughly 50 times the average Earth magnetic field. These microrobotic agents with dimensions less than 300 mu m x 300 mu m x 70 mu m and a total mass of 30-50 mu g are capable of moving forward, backward and turning in place while reaching controllable speeds in excess of 12.5 mm s(-1) or 42 times the robot's body length per second. The robots produce enough force to push micro-objects of similar sizes and can be visually servoed through a maze in a fully automated fashion. The prototype devices exhibit an overall degree of flexibility, controllability, and performance unmatched by other microrobots reported in the literature. The robustness of the MagMites leads to high experimental repeatability, which in turn enabled us to successfully compete in the RoboCup 2007 and 2009 Nanogram competitions. In this work it is demonstrated how the robots exhibit a plethora of driving behaviors, how they can operate on a host of unstructured surfaces under both dry and wet conditions, and how they can accomplish fully automated micromanipulation tasks. Various micro-objects ranging from beads to biological entities have been successfully manipulated. To the same end, multi-agent studies have shown great promise to be used in cooperative tasks.
This paper presents a method for determining the six degree-of-freedom transformation between a camera and a base frame of interest. A planar mirror is maneuvered so as to allow the camera to observe the environment f...
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ISBN:
(纸本)9783642003110
This paper presents a method for determining the six degree-of-freedom transformation between a camera and a base frame of interest. A planar mirror is maneuvered so as to allow the camera to observe the environment from several viewing angles. Points, whose coordinates in the base frame are known, are observed by the camera via their reflections in the mirror. Exploiting these measurements, we determine the camera-to-base transformation analytically, without assuming prior knowledge of the mirror motion or placement with respect to the camera. The computed solution is refined using a maximum-likelihood estimator, to obtain high-accuracy estimates of the camera-to-base transformation and the mirror configuration for each image. We validate the accuracy and correctness of our method with simulations and real-world experiments.
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