Many distributed manipulation systems are capable of generating planar force fields which act over the entire surface of an object to manipulate it to a stable equilibrium within the field. Passive air flow and other ...
详细信息
ISBN:
(纸本)3540404767
Many distributed manipulation systems are capable of generating planar force fields which act over the entire surface of an object to manipulate it to a stable equilibrium within the field. Passive air flow and other physical phenomena, naturally generate force fields through the linear superposition of logarithmically varying radial potential fields. The main advantage of these fields is that they are realizable through very simple actuation. However, they do not lend themselves to analytical prediction of net forces or equilibria. This paper presents an efficient means of numerically computing the net force and moment exerted by such fields on objects composed of multiple simple shapes, as well as efficient means of finding equilibrium points on these fields.
We examine the scalability of multi-robot algorithms. In particular, we attempt to capture the idea that the less coordination a multi-robot system requires, the better it should scale to large numbers of robots. To t...
详细信息
ISBN:
(纸本)3540404767
We examine the scalability of multi-robot algorithms. In particular, we attempt to capture the idea that the less coordination a multi-robot system requires, the better it should scale to large numbers of robots. To that end, we introduce a notion of communication complexity of multi-robot (or more generally, distributed control) systems as a surrogate for coordination. We describe a formalism, called CCL, for specifying multi-robot systems and algorithms for which the definition of communication complexity arises naturally. We then analyze the communication complexity of several, in some cases novel, multi-robot communication schemes each representative of one of several natural complexity classes.
The basic motion-planning problem is to plan a collision-free motion for an object moving among obstacles between free initial and goal positions, or to determine that no such motion exists. The basic problem as well ...
详细信息
ISBN:
(纸本)3540404767
The basic motion-planning problem is to plan a collision-free motion for an object moving among obstacles between free initial and goal positions, or to determine that no such motion exists. The basic problem as well as numerous variants of it have been intensively studied over the past two decades yielding a wealth of results and techniques, both theoretical and practical. In this paper, we propose a novel approach to motion planning, hybrid motion planning, in which we integrate complete solutions along with probabilistic roadmap (PRM) methods in order to combine their strengths and offset their weaknesses. We incorporate robust tools, that have not been available before, in order to implement the complete solutions. We exemplify our approach in the case of two discs moving among polygonal obstacles in the plane. The planner we present easily solves problems where a narrow passage in the workspace can be arbitrarily small. Our planner is also capable of providing correct nontrivial "no" answers, namely it can, for some queries, detect the situation where no solution exists. We envision our planner not as a total solution but rather as a new tool that cooperates with existing planners. We demonstrate the advantages and shortcomings of our planner with experimental results.
A metamorphic robotic system is an aggregate of identical robot units which can individually detach and reattach in such a way as to change the global shape of the system. We introduce a mathematical framework for def...
详细信息
ISBN:
(纸本)3540404767
A metamorphic robotic system is an aggregate of identical robot units which can individually detach and reattach in such a way as to change the global shape of the system. We introduce a mathematical framework for defining and analyzing general metamorphic systems. This formal structure combined with ideas from geometric group theory leads to a natural extension of a configuration space for metamorphic systems - the shape complex - which is especially adapted to parallelization. We present an algorithm for optimizing reconfiguration sequences with respect to elapsed time. A universal geometric property of shape complexes - non-positive curvature - is the key to proving convergence to the globally time-optimal solution.
This paper focuses on the collision-free coordination of multiple robots with kinodynamic constraints along specified paths. We present an approach to generate continuous velocity profiles for multiple robots that avo...
详细信息
ISBN:
(纸本)3540404767
This paper focuses on the collision-free coordination of multiple robots with kinodynamic constraints along specified paths. We present an approach to generate continuous velocity profiles for multiple robots that avoids collisions and minimizes the completion time. The approach, which combines techniques from optimal control and mathematical programming, consists of identifying collision segments along each robot's path, and then optimizing the robots velocities along the collision and collision-free segments. First, for each path segment for each robot, the minimum and maximum possible traversal times that satisfy the dynamics constraints are computed by solving the corresponding two-point boundary value problems. The collision avoidance constraints for pairs of robots can then be combined to formulate a mixed integer nonlinear programming (MINLP) problem. Since this nonconvex MINLP model is difficult to solve, we describe two related mixed integer linear programming (MILP) formulations that provide schedules that are lower and upper bounds on the optimum, the upper bound schedule is designed to be a continuous velocity schedule. The approach is illustrated with coordination of multiple robots, modeled as double integrators subject to velocity and acceleration constraints. Implementation results for coordination of 12 robots are described.
Self-reconfigurable robots are versatile systems consisting of large numbers of independent modules. Effective use of these systems requires parallel actuation and planning, both for efficiency and independence from a...
详细信息
ISBN:
(纸本)3540404767
Self-reconfigurable robots are versatile systems consisting of large numbers of independent modules. Effective use of these systems requires parallel actuation and planning, both for efficiency and independence from a central controller. This paper presents the PacMan algorithm, a technique for distributed actuation and planning. This algorithm works on systems with two- or three-dimensional unit-compressible modules. We give a simplified version of the algorithm along with extensions that handle a larger class of parallel actuation. For both algorithms, we present correctness analysis that show the classes of reconfigurations that can be guaranteed to be achieved. For the extensions, we give proofs of parallel actuation capability that describe how several modules can move simultaneously without synchronization while retaining correctness. We have successfully instantiated the basic algorithm onto the Crystal, a self-reconfigurable robot system, and present hardware experiments.
We describe an on-line sensor based algorithm for covering planar areas with a uniform scan pattern, where the covering is executed by a DxD square-shaped tool attached to a mobile robot. The algorithm, called Scan-ST...
详细信息
ISBN:
(纸本)3540404767
We describe an on-line sensor based algorithm for covering planar areas with a uniform scan pattern, where the covering is executed by a DxD square-shaped tool attached to a mobile robot. The algorithm, called Scan-STC, incrementally subdivides the planar area into a grid of D-size cells, while following a spanning tree of a graph whose nodes are 2D-size cells. The algorithm covers any planar grid with a scan path whose total length is at most (n+m)D, where n is the number of D-size cells and m less than or equal to n is the number of boundary cells, defined as cells that share at least one point with the grid boundary. Scan-STC additionally strives to minimize the total length of path segments orthogonal to the scan direction, and we report a preliminary bound on the length of these segments. We also demonstrate that any on-line coverage algorithm generates a covering path whose length is at least (2-epsilon)l(opt) in worst case, where l(opt) is the length of the optimal off-line covering path. Since (n+m)D less than or equal to 2l(opt), the bound is tight and Scan-STC is worst-case optimal. Moreover, in practical environments m much less than n, and Scan-STC generates close-to-optimal covering paths in such environments.
We introduce a new approach to design and fabrication of mechatronic systems called flexonics. Flexonics integrates structural, mechanical and electronic elements based on 3D printing techniques, in particular inkjet ...
详细信息
ISBN:
(纸本)3540404767
We introduce a new approach to design and fabrication of mechatronic systems called flexonics. Flexonics integrates structural, mechanical and electronic elements based on 3D printing techniques, in particular inkjet printing. This paper outlines some principles for flexonic design, which is based on flexion rather than sliding or rolling motion as in traditional mechanics. It describes our preliminary explorations of materials and processes. And it describes a kinematic approach to joint design that has so far led to one promising new design. Finally, we give a brief prospectus of future applications of flexonics.
暂无评论