An enlarged polygon method without binary variables for obstacle avoidance trajectory optimization

In this article,an Enlarged Polygon/Polyhedron(ELP)method without binary variables is proposed to represent the Convex Polygonal/Polyhedral Obstacle Avoidance(CPOA)constraints in trajectory optimization.First,the equivalent condition of a point outside the convex set is given and proved rigorously.Then,the ELP condition describing the CPOA constraints equivalently is given without introducing binary variables,and its geometric meaning is explained.Finally,the ELP method is used to transform the CPOA trajectory optimization problem into an optimal control problem without binary variables.The effectiveness and validity of ELP method are demonstrated through simulations with both simple linear dynamic model(unmanned aerial vehicle)and complex nonlinear dynamic model(hypersonic glide vehicle).Comparison indicates the computational time of ELP method is only 1%-20%of that of the traditional Mixed-Integer Programming(MIP)method.

Multi-Antenna UAV Data Harvesting:Joint Trajectory and Communication Optimization

Unmanned aerial vehicle(UAV)-enabled communication is a promising technology to extend coverage and enhance throughput for traditional terres-trial wireless communication systems.In this paper,we consider a UAV-enabled wireless sensor network,where a multi-antenna UAV is dispatched to collect data from a group of sensor nodes(SNs).The objective is to maximize the minimum data collection rate from all SNs via jointly optimizing their transmission scheduling and power allocations as well as the trajectory of the UAV,subject to the practical constraints on the maximum transmit power of the SNs and the maximum speed of the UAV.The formulated optimization problem is challenging to solve as it involves non-convex constraints and discrete-value variables.To draw useful insight,we first consider the special case of the formulated problem by ignoring the UAV speed constraint and optimally solve it based on the Lagrange duality method.It is shown that for this relaxed problem,the UAV should hover above a finite number of optimal locations with different durations in general.Next,we address the general case of the formulated problem where the UAV speed constraint is considered and propose a traveling salesman problem-based trajec-tory initialization,where the UAV sequentially visits the locations obtained in the relaxed problem with minimumflying time.Given this initial trajectory,we thenfind the corresponding transmission scheduling and power alloca-tions of the SNs and further optimize the UAV trajectory by applying the block coordinate descent and successive convex approximation techniques.Finally,numerical results are provided to illustrate the spectrum and energy efficiency gains of the proposed scheme for multi-antenna UAV data harvesting,as compared to benchmark schemes.