scholarly journals A Hybrid Approach for Autonomous Collision-Free UAV Navigation in 3D Partially Unknown Dynamic Environments

Drones ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 57
Author(s):  
Taha Elmokadem ◽  
Andrey V. Savkin
Keyword(s):  
Sliding Mode ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Dynamic Environments ◽  
Reactive Control ◽  
Suggested Approach ◽  
Safe Navigation ◽  
Wide Range ◽  
Planning Algorithm ◽  
Path Planning Algorithm

In the past decades, unmanned aerial vehicles (UAVs) have emerged in a wide range of applications. Owing to the advances in UAV technologies related to sensing, computing, power, etc., it has become possible to carry out missions autonomously. A key component to achieving this goal is the development of safe navigation methods, which is the main focus of this work. A hybrid navigation approach is proposed to allow safe autonomous operations in three-dimensional (3D) partially unknown and dynamic environments. This method combines a global path planning algorithm, namely RRT-Connect, with a reactive control law based on sliding mode control to provide quick reflex-like reactions to newly detected obstacles. The performance of the suggested approach is validated using simulations.

Kinematics of a Novel Single-Loop Under-Actuated Wrist

2012 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Path Planning ◽  
Closed Form ◽  
Nonholonomic Constraint ◽  
Three Dimensional ◽  
Single Loop ◽  
Closed Form Solutions ◽  
Position Analysis ◽  
Tracking Tasks ◽  
Planning Algorithm ◽  
Path Planning Algorithm

A novel type of parallel wrist (PW) is proposed which, differently from previously presented PWs, features a single-loop architecture and only one nonholonomic constraint. Due to the presence of a nonholonomic constraint, the proposed PW type is under-actuated, that is, it is able to control the platform orientation in a three-dimensional workspace by employing only two actuated pairs, one prismatic (P) and the other revolute (R); and it cannot perform tracking tasks. Position analysis and path planning of this novel PW are studied. In particular, all the relevant position analysis problems are solved in closed form, and, based on these closed-form solutions, a path-planning algorithm is built.

Research on Algorithm for Space Weld Reconstruction and Torch Pose Simulation

2014 ◽  
Vol 1049-1050 ◽  
pp. 833-837
Author(s):  
Peng Yang ◽  
Dong Xing Hui ◽  
Zheng Kai ◽  
Li Shu Tian
Keyword(s):  
Coordinate Transformation ◽  
Spline Interpolation ◽  
Three Dimensional ◽  
Automatic Welding ◽  
Control Points ◽  
B Spline ◽  
Spline Curve ◽  
Planning Algorithm ◽  
Control Terminal ◽  
Path Planning Algorithm

A path planning algorithm based on B-spline interpolation techniques was constructed for automatic welding system.The system used a B-spline curve to reconstruct the weld,it was achieved by reversing the control points of B-spline curve through the prescribed date points. The weld posture model was then obtained from the osculating plane and normal plane of B-spline curve. By taking a series coordinate transformation to the weld posture model, the torch posture model based on control terminal was provided.Experiments show that the new algorithm can readily be used for various three-dimensional welding tasks.

A family of skeletons for motion planning and geometric reasoning applications

2011 ◽  
Vol 25 (4) ◽  
pp. 375-392
Author(s):  
Ata A. Eftekharian ◽  
Horea T. Ilieş
Keyword(s):  
Motion Planning ◽  
Medial Axis ◽  
A Priori ◽  
Three Dimensional ◽  
Geometric Reasoning ◽  
Spatial Configurations ◽  
Planning Algorithm ◽  
Logic Operations ◽  
Path Planning Algorithm ◽  
Special Case

AbstractThe task of planning a path between two spatial configurations of an artifact moving among obstacles is an important problem in practically all geometrically intensive applications. Despite the ubiquity of the problem, the existing approaches make specific limiting assumptions about the geometry and mobility of the obstacles, or those of the environment in which the motion of the artifact takes place. We present a strategy to construct a family of paths, or roadmaps, for two- and three-dimensional solids moving in an evolving environment that can undergo drastic topological changes. Our approach is based on a potent paradigm for constructing geometric skeletons that relies on constructive representations of shapes with R-functions that operate on real-valued half-spaces as logic operations. We describe a family of skeletons that have the same homotopy as that of the environment and contains the medial axis as a special case. Of importance, our skeletons can be designed so that they are “attracted to” or “repulsed by” prescribed spatial sites of the environment. Moreover, the R-function formulation suggests the new concept of a medial zone, which can be thought of as a “thick” skeleton with significant applications for motion planning and other geometric reasoning applications. Our approach can handle problems in which the environment is not fully known a priori, and intrinsically supports local and parallel skeleton computations for domains with rigid or evolving boundaries. Furthermore, our path planning algorithm can be implemented in any commercial geometric kernel, and has attractive computational properties. The capability of the proposed technique are explored through several examples designed to simulate highly dynamic environments.

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