Waypoint

Abstract: The random waypoint model is a commonly used mobility model in the simulation of ad hoc networks It is known that the spatial distribution of network nodes moving according to this model is, in general, nonuniform However, a closed-form expression of this distribution and an in-depth investigation is still missing This fact impairs the accuracy of the current simulation methodology of ad hoc networks and makes it impossible to relate simulation-based performance results to corresponding analytical results To overcome these problems, we present a detailed analytical study of the spatial node distribution generated by random waypoint mobility More specifically, we consider a generalization of the model in which the pause time of the mobile nodes is chosen arbitrarily in each waypoint and a fraction of nodes may remain static for the entire simulation time We show that the structure of the resulting distribution is the weighted sum of three independent components: the static, pause, and mobility component This division enables us to understand how the model's parameters influence the distribution We derive an exact equation of the asymptotically stationary distribution for movement on a line segment and an accurate approximation for a square area The good quality of this approximation is validated through simulations using various settings of the mobility parameters In summary, this article gives a fundamental understanding of the behavior of the random waypoint model

Abstract: A six-degree-of-freedom model for the maneuvering of an underwater vehicle is used and a sliding-mode autopilot is designed for the combined steering, diving, and speed control functions. In flight control applications of this kind, difficulties arise because the system to be controlled is highly nonlinear and coupled, and there is a good deal of parameter uncertainty and variation with operational conditions. The development of variable-structure control in the form of sliding modes has been shown to provide robustness that is expected to be quite remarkable for AUV autopilot design. It is shown that a multivariable sliding-mode autopilot based on state feedback, designed assuming decoupled modeling, is quite satisfactory for the combined speed, steering, and diving response of a slow AUV. The influence of speed, modeling nonlinearity, uncertainty, and disturbances, can be effectively compensated, even for complex maneuvering. Waypoint acquisition based on line-of-sight guidance is used to achieve path tracking. >

Abstract: Describes a method for finding optimal trajectories for multiple aircraft avoiding collisions. Developments in spacecraft path-planning have shown that trajectory optimization including collision avoidance can be written as a linear program subject to mixed integer constraints, known as a mixed-integer linear program (MILP). This can be solved using commercial software written for the operations research community. In the paper, an approximate model of aircraft dynamics using only linear constraints is developed, enabling the MILP approach to be applied to aircraft collision avoidance. The formulation can also be extended to include multiple waypoint path-planning, in which each vehicle is required to visit a set of points in an order chosen within the optimization.