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16
RapidlyExploring Random Trees: Progress and Prospects
 Algorithmic and Computational Robotics: New Directions
, 2000
"... this paper, which presents randomized, algorithmic techniques for path planning that are particular suited for problems that involve dierential constraints. ..."
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Cited by 228 (25 self)
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this paper, which presents randomized, algorithmic techniques for path planning that are particular suited for problems that involve dierential constraints.
Combining SpeedUp Techniques for ShortestPath Computations
 In Proc. 3rd Workshop on Experimental and Efficient Algorithms. LNCS
, 2004
"... Computing a shortest path from one node to another in a directed graph is a very common task in practice. This problem is classically solved by Dijkstra's algorithm. Many techniques are known to speed up this algorithm heuristically, while optimality of the solution can still be guaranteed. In m ..."
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Cited by 20 (6 self)
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Computing a shortest path from one node to another in a directed graph is a very common task in practice. This problem is classically solved by Dijkstra's algorithm. Many techniques are known to speed up this algorithm heuristically, while optimality of the solution can still be guaranteed. In most studies, such techniques are considered individually.
From dynamic programming to RRTs: Algorithmic design of feasible trajectories
 Control Problems in Robotics
, 2002
"... Abstract. This paper summarizes our recent development of algorithms that construct feasible trajectories for problems that involve both differential constraints (typically in the form of an underactuated nonlinear system), and global constraints (typically arising from robot collisions). Dynamic pr ..."
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Cited by 13 (0 self)
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Abstract. This paper summarizes our recent development of algorithms that construct feasible trajectories for problems that involve both differential constraints (typically in the form of an underactuated nonlinear system), and global constraints (typically arising from robot collisions). Dynamic programming approaches are described that produce approximatelyoptimal solutions for lowdimensional problems. Rapidlyexploring Random Tree (RRT) approaches are described that can find feasible, nonoptimal solutions for higherdimensional problems. Several key issues for future research are discussed. 1
SpeedUp Techniques for ShortestPath Computations
 IN PROCEEDINGS OF THE 24TH INTERNATIONAL SYMPOSIUM ON THEORETICAL ASPECTS OF COMPUTER SCIENCE (STACS’07
, 2007
"... During the last years, several speedup techniques for Dijkstra’s algorithm have been published that maintain the correctness of the algorithm but reduce its running time for typical instances. They are usually based on a preprocessing that annotates the graph with additional information which can ..."
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Cited by 13 (7 self)
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During the last years, several speedup techniques for Dijkstra’s algorithm have been published that maintain the correctness of the algorithm but reduce its running time for typical instances. They are usually based on a preprocessing that annotates the graph with additional information which can be used to prune or guide the search. Timetable information in public transport is a traditional application domain for such techniques. In this paper, we provide a condensed overview of new developments and extensions of classic results. Furthermore, we discuss how combinations of speedup techniques can be realized to take advantage from different strategies.
Using Randomization to Find and Optimize Feasible Trajectories for Nonlinear Systems
 Proc. Annual Allerton Conference on Communications, Control, Computing
, 2000
"... Abstract We present our current progress on the design and experimentation with trajectory planning and optimization algorithms for nonlinear systems that have significant statespace constraints. An overview of our planning method based on Rapidlyexploring Random Trees (RRTs) is given. We show our ..."
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Cited by 6 (0 self)
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Abstract We present our current progress on the design and experimentation with trajectory planning and optimization algorithms for nonlinear systems that have significant statespace constraints. An overview of our planning method based on Rapidlyexploring Random Trees (RRTs) is given. We show our current planning results for two challenging sets of nonlinear systems: 1) the determination of automobile trajectories through obstacle courses; 2) the design of reentry trajectories for a reusable launch vehicle model based on the NASA X33 prototype. We also briefly describe some early results on using randomization to optimize trajectories in the presence of state space constraints. 1
General Gate Array Routing using a kTerminal Net Routing Algorithm with Failure Prediction
, 1993
"... In this paper a general approach to gate array routing is presented, based on an abstract routing space model. An efficient kterminal net maze runner is described. It does not partition nets into 2terminal net routing problems, but solves the problem by simultaneously growing k search waves. It ..."
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Cited by 3 (3 self)
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In this paper a general approach to gate array routing is presented, based on an abstract routing space model. An efficient kterminal net maze runner is described. It does not partition nets into 2terminal net routing problems, but solves the problem by simultaneously growing k search waves. It is shown that the explored routing space diminishes when compared to bidirectional routing schemes. Additional routing space restriction is attained by use of variable search space restriction and due to the introduction of a dynamic routing space partitioning method based on the concept of regions. This concept allows us to determine non routable nets or parts of nets in an efficient way. Is is shown that this new partitioning method may be implemented in any maze runner without increasing the complexity of the maze runner algorithm. Result show a decreas of cputime up to 35%. Especially in congested routing space the cputime decreases significantly. 1 Introduction We are developing ...
Experiments in HighLevel Robot Control Using ConGolog  Reactivity, Failure Handling, and KnowledgeBased Search
, 1998
"... Getting robots to do complex tasks is very difficult. The robot must not only be able to navigate through the world and execute various primitive tasks such as "go forwards by 5 cm" and "take a picture", but also support the specification and execution of complex behaviors, which requires reasoning ..."
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Cited by 3 (1 self)
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Getting robots to do complex tasks is very difficult. The robot must not only be able to navigate through the world and execute various primitive tasks such as "go forwards by 5 cm" and "take a picture", but also support the specification and execution of complex behaviors, which requires reasoning about goals and actions. The occurrence of exogenous events and runtime failures, and having incomplete information of the environment have long been two major problems encountered by most robots operating in the real world. In this thesis, we develop an approach to building robust highlevel control modules using the ConGolog language and prioritized interrupts to handle exogenous events and runtime failures. Such a module is implemented and tested on a mobile robot in a real environment for a mail delivery task. We also develop a knowledgebased approach to guide search for people in the presence of incomplete knowledge.
Counting paths and packings in halves
 in ESA
, 1007
"... Abstract. It is shown that one can count kedge paths in an nvertex graph and mset kpackings on an nelement universe, respectively, in n and, up to a factor polynomial in n, k, and m; in time ` n k/2 mk/2 polynomial space, the bounds hold if multiplied by 3 k/2 or 5 mk/2, respectively. These are ..."
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Cited by 3 (0 self)
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Abstract. It is shown that one can count kedge paths in an nvertex graph and mset kpackings on an nelement universe, respectively, in n and, up to a factor polynomial in n, k, and m; in time ` n k/2 mk/2 polynomial space, the bounds hold if multiplied by 3 k/2 or 5 mk/2, respectively. These are implications of a more general result: given two set families on an nelement universe, one can count the disjoint pairs of sets in the Cartesian product of the two families with O(nℓ) basic operations, where ℓ is the number of members in the two families and their subsets. 1
Common Misconceptions Concerning Heuristic Search
"... This paper examines the following statements about heuristic search, which are commonly held to be true: More accurate heuristics result in fewer states being expanded by A * and IDA*. A * expands fewer states than any other equally informed algorithm that finds optimal solutions. Any admissible heu ..."
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Cited by 2 (2 self)
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This paper examines the following statements about heuristic search, which are commonly held to be true: More accurate heuristics result in fewer states being expanded by A * and IDA*. A * expands fewer states than any other equally informed algorithm that finds optimal solutions. Any admissible heuristic can be turned into a consistent heuristic by a simple technique called. In search spaces whose operators all have the same cost A * with the heuristic function for all states, , is the same as breadthfirst search. Bidirectional A * stops when the forward and backward search frontiers meet. The paper demonstrates that all these statements are false and provides alternative statements that are true.
A Multiple Terminal Net Routing Algorithm using Failure Prediction
 Proc. Int. Conf. on VLSI Design
, 1993
"... A new multiple terminal net maze runner is described that is used in a generic placement and routing system targeted towards prefabricated devices such as gate arrays and SeaofGates gate arrays. Instead of partitioning an nterminal net into several 2terminal nets to be routed sequentially, w ..."
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Cited by 1 (1 self)
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A new multiple terminal net maze runner is described that is used in a generic placement and routing system targeted towards prefabricated devices such as gate arrays and SeaofGates gate arrays. Instead of partitioning an nterminal net into several 2terminal nets to be routed sequentially, we tackle the routing problem by routing all terminals at once. We show that the explored routing space diminishes and thus the cputime is reduced by doing so. A new mechanism is introduced that partitions the routing space into socalled 'unconnected regions'. The benefit of this is twofold. Firstly, it enables us to identify nonroutable nets or nonroutable parts of nets without actually trying to route them. Secondly, additional routing space restriction is possible. It is shown that this failure prediction mechanism can be implemented in any maze runner scheme without increasing the complexity of the algorithm. Experimental results show an extra reduction of cputime up to 35% by u...