In this expository note, we prove the semiclassical propagation of singularities estimate in the presence of complex absorbtion, using the positive commutator method of Hörmander. As an application, we show a nontrapping estimate for one-dimensional semiclassical potential scattering using the method of complex scaling. We also explain how nontrapping estimates in certain other situations (such...

Within natural environments, animals must be able to respond to a wide range of obstacles in their path. Such responses require sensory information to facilitate appropriate and effective motor behaviors. The objective of this study was to characterize sensors involved in the complex control of obstacle negotiation behaviors in the cockroach Blaberus discoidalis. Previous studies suggest that a...

A substantial challenge in robotics is integration of complex software systems for realtime performance. This thesis integrates the robust and generic mapping framework Atlas, a feature-based local Simultaneous Localization and Mapping (SLAM) module, and obstacle avoidance using information from mapped features. The resulting system performs autonomous feature-relative Real-time Obstacle Avoida...

With the wide deployment of redundant manipulators in complex working environments, obstacle avoidance emerges as an important issue to be addressed in robot motion planning. In this paper, a new obstacle avoidance scheme is presented for redundant manipulators. In this scheme, obstacle avoidance is mathematically formulated as a time-varying linearly constrained quadratic programming problem. ...

The Rayleigh conjecture on the representation of the scattered field in the exterior of an obstacle D is widely used in applications. However this conjecture is false for some obstacles. AGR introduced the Modified Rayleigh Conjecture (MRC), and in this paper we present successful numerical algorithms based on the MRC for various 2D and 3D obstacle scattering problems. The 3D obstacles include ...

A large class of problems in robotics, e.g., trajectory tracking with obstacle avoidance, compliant motion control, and complex assembly, can be formulated as a least-squares tracking problem on the Euclidean group subject to constraints on the state and/or control. In this note we develop an optimal control framework for this general class of problems, and derive analytic solutions for the loc...

Density or gravity currents have been always one of the main causes for sedimentation along many of the dam reservoirs. So controlling this phenomenon is very important for increasing useful life of such reservoirs. In this research study the effect of a combination of rough bed and obstacle on the control of sedimentary density current has been investigated. Experiments were conducted in a til...

To understand the mechanics of a complex fluid such as a foam we propose a model experiment (a bidimensional flow around an obstacle) for which an external sollicitation is applied, and a local response is measured, simultaneously. We observe that an asymmetric obstacle (cambered airfoil profile) experiences a downwards lift, opposite to the lift usually known (in a different context) in aerody...

A path-planning method based on a combination of the static global and the dynamic local pathplanning methods is proposed for robot path planning under a complex environment. There are known static obstacles and unknown dynamic obstacles in any complex environment. The local-path planner dynamically generates a local path using obstacle-motion prediction and a rolling window for dynamic path pl...