Three diierent algorithms for qualitative obstacle detection are presented in this paper. Each one is based on diierent assumptions. The rst two algorithms are aimed at yes/no obstacle detection without indicating which points are obstacles. They have the advantage of fast determination of the existence of obstacles in a scene based on the solvability of a linear system. The rst algorithm uses ...

We recount some of Ralph Kleinman's scientiic achievements in obstacle scattering for time harmonic waves by reporting on two topics where R.K. and R.K. interacted mathematically. The rst topic is the problem of nonuniqueness for the classical boundary integral equations for the direct scattering problem and the second is the development of numerical methods for the inverse scattering problem.

In this paper, we extend the algorithm in Xue and Cheng [L. Xue, X.L. Cheng, An algorithm for solving the obstacle problems, Comput. Math. Appl. 48 (2004) 1651–1657] for solving the double obstacle problem. We try to find the approximated region of the contact in the double obstacle problem with less computation time by iteration. Numerical example is given for the double obstacle problem for t...

In this paper, we provide a dynamic graph theoretical framework for flocking in presence of multiple obstacles. In particular, we give formal definitions of nets and flocks as spatially induced graphs. We provide models of nets and flocks and discuss the realization/embedding issues related to structural nets and flocks. This allows task representation and execution for a network of agents call...

The obstacle number is a new graph parameter introduced by Alpert, Koch, and Laison (2010). Mukkamala et al. (2012) show that there exist graphs with n vertices having obstacle number in Ω(n/ log n). In this note, we up this lower bound to Ω(n/(log log n)2). Our proof makes use of an upper bound of Mukkamala et al. on the number of graphs having obstacle number at most h in such a way that any ...

The rst exact algorithm for the obstacle-avoiding Euclidean Steiner tree problem in the plane (in its most general form) is presented. The algorithm uses a two-phase framework | based on the generation and concatenation of full Steiner trees | previously shown to be very successful for the obstacle-free case. Computational results for moderate size problem instances are given; instances with up...

This paper describes a laser ranging sensor that is suitable for applications like small unmanned aerial vehicles. The hardware consists of a diode emitter array and line-scan charge coupled devices. A structured-light technique measures ranges up to 30 meters for 64 field angles in a 90 degree field of view. Operation is eye safe, and the laser wavelength is not visible to night vision goggles...

The Stanford AI Lab cart is a remotely controlled TV equipped mobile robot. A computer program has driven the cart through cluttered spaces, gaining its knowledge of the world entirely from images broadcast by the onboard TV system. The cart uses several kinds of stereo to locate objects around it in 3D and to deduce its own motion. It plans an obstacle avoiding path to a desired destination on...

The purpose of the current study was to understand how visual information about an ongoing change in obstacle size is used during obstacle avoidance for both lead and trail limbs. Participants were required to walk in a dark room and to step over an obstacle edged with a special tape visible in the dark. The obstacle's dimensions were manipulated one step before obstacle clearance by increasing...