network flow

In this paper, the problem of the Terrain Contour Matching systemrequirement effect in the constraint optimal trajectory planning of the unmanned aerial vehicles that are require to fly at low altitude over the terrain has been discussed. According to using this system in some of vehicles as a navigation aiding system,it is more efficient in rough terrain and given that the optimal path planning methods have generally attempted to cross the paved areas, with this contradiction, providing the requirements of this system is a complex task. In this paper, it's tried to meet the system requirementsin the constraint optimal trajectory design process. For this purpose, by developing an algorithm based on the layered network flow and applying dynamic equations of motion on digital terrain elevation data in the three-dimensional space with the discrete dynamical constraints and a cost function, a complete model of parameters affecting the system has been fulfilled. The resulting algorithm,by applying the initial conditions and in the least possible time,produces a constraint optimal trajectory in such a way that the requirements of the systemare satisfied. Numerical results of simulation show validity of this issue.

In this paper, the problem of the navigation error effect for the optimal and constraint Trajectory of the UAVs that are required to fly at low altitude over terrains has been discussed. Due to the increasing deviation problem of inertial navigation systems in terms of time, having a safe flight and collision avoidance with terrain at low altitude is the main point in the trajectory design of this type of the vehicles. On the other hand, some of these vehicles use Terrain Contour Matching (TERCOM) as a navigation aiding system. This system is more efficient in rough terrains, and providing the requirements of this system beside other constraints is a complex task. In this paper is tried to meet these constraints in the trajectory design process. For this purpose, an algorithm based on the layered network flow on the digital terrain maps used in a manner that has a high potential in adoption of various constraints and optimal trajectory is generated. Then, using equations of motion on a terrain digital data in 3D space with the dynamical constraints and different optimality criteria, a complete model of navigation error and also parameters affecting TERCOM has been developed to generate feasible path reducing terrain collision probability to zero.. Numerical results show validity of this issue.