scholarly journals Enhanced Potential Field-Based Collision Avoidance in Cluttered Three-Dimensional Urban Environments

2021 ◽  
Vol 11 (22) ◽  
pp. 11003
Author(s):  
Daegyun Choi ◽  
Donghoon Kim ◽  
Kyuman Lee

With the various applications of unmanned aerial vehicles (UAVs), the number of UAVs will increase in limited airspace, leading to an increased risk collision. To reduce such potential risk, this work proposes a collision avoidance strategy for UAVs using an enhanced potential field (EPF) approach in cluttered three-dimensional urban environments. Using the EPF formulated in a two-dimensional environment, the avoidance maneuvers for both horizontal and vertical planes are generated by introducing rotation matrices, and these maneuvers are combined by applying a weighting factor. The numerical simulations with various meaningful scenarios are conducted to validate the performance of the proposed approach. To mimic practical situations, UAV dynamics and sensor limitations were considered. The simulation results show that the proposed approach provides an efficient, reliable, and collision-free path without local minima and unreachable goal issues.

Robotica ◽  
2021 ◽  
pp. 1-20
Author(s):  
Daegyun Choi ◽  
Anirudh Chhabra ◽  
Donghoon Kim

Summary This paper proposes an intelligent cooperative collision avoidance approach combining the enhanced potential field (EPF) with a fuzzy inference system (FIS) to resolve local minima and goal non-reachable with obstacles nearby issues and provide a near-optimal collision-free trajectory. A genetic algorithm is utilized to optimize parameters of membership function and rule base of the FISs. This work uses a single scenario containing all issues and interactions among unmanned aerial vehicles (UAVs) for training. For validating the performance, two scenarios containing obstacles with different shapes and several UAVs in small airspace are considered. Multiple simulation results show that the proposed approach outperforms the conventional EPF approach statistically.


Author(s):  
Jun Tang ◽  
Jiayi Sun ◽  
Cong Lu ◽  
Songyang Lao

Multi-unmanned aerial vehicle trajectory planning is one of the most complex global optimum problems in multi-unmanned aerial vehicle coordinated control. Results of recent research works on trajectory planning reveal persisting theoretical and practical problems. To mitigate them, this paper proposes a novel optimized artificial potential field algorithm for multi-unmanned aerial vehicle operations in a three-dimensional dynamic space. For all purposes, this study considers the unmanned aerial vehicles and obstacles as spheres and cylinders with negative electricity, respectively, while the targets are considered spheres with positive electricity. However, the conventional artificial potential field algorithm is restricted to a single unmanned aerial vehicle trajectory planning in two-dimensional space and usually fails to ensure collision avoidance. To deal with this challenge, we propose a method with a distance factor and jump strategy to resolve common problems such as unreachable targets and ensure that the unmanned aerial vehicle does not collide into the obstacles. The method takes companion unmanned aerial vehicles as the dynamic obstacles to realize collaborative trajectory planning. Besides, the method solves jitter problems using the dynamic step adjustment method and climb strategy. It is validated in quantitative test simulation models and reasonable results are generated for a three-dimensional simulated urban environment.


2018 ◽  
Vol 15 (4) ◽  
pp. 172988141878707 ◽  
Author(s):  
X Xu ◽  
Y Hu ◽  
JM Zhai ◽  
LZ Li ◽  
PS Guo

This article presents a non-collision trajectory planning algorithm in three-dimensional space based on velocity potential field for robotic manipulators, which can be applied to collision avoidance among serial industrial robots and obstacles, and path optimization in multi-robot collaborative operation. The algorithm is achieved by planning joint velocities of manipulators based on attractive, repulsive, and tangential velocity of velocity potential field. To avoid oscillating at goal point, a saturated function is suggested to the attractive velocity potential field that slows down to the goal progressively. In repulsive velocity potential field, a spring damping system is designed to eliminate the chattering phenomenon near obstacles. Moreover, a fuzzy logic approach is used to optimize the spring damping coefficients for different velocities of manipulators. Different from the usual tangential velocity perpendicular to the repulsive velocity vector for avoiding the local minima problem, an innovative tangential velocity potential field is introduced that is considering the relative position and moving direction of obstacles for minimum avoidance path in three-dimensional space. In addition, a path priority strategy of collision avoidance is taken into account for better performance and higher efficiency when multi-robots cooperation is scheduled. The improvements for local minima and oscillation are verified by simulations in MATLAB. The adaptabilities of the algorithm in different velocities and priority strategies are demonstrated by simulations of two ABB robots in Robot Studio. The method is further implemented in an experimental platform with a SCARA and an ABB robot cooperation around a stationary obstacle and a moving object, and the result shows real time and effectiveness of the algorithms.


Fluids ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 137 ◽  
Author(s):  
Mingrui Liu ◽  
Xiuling Wang

Three-dimensional urban wind field construction plays an important role not only in the analysis of pedestrian levels of comfort but also in the effectiveness of harnessing wind energy in an urban environment. However, it is challenging to accurately simulate urban wind flow due to the complex land use in urban environments. In this study, a three-dimensional numerical model was developed for urban wind flow construction. To obtain an accurate urban wind field, various turbulence models, including the Reynolds stress model (RSM), k-ω shear stress transport (SST), realizable k-ε, and (Re-Normalisation Group (RNG) k-ε models were tested. Simulation results were compared with experimental data in the literature. The RSM model showed promising potential in simulating urban wind flow. The model was then adopted to simulate urban wind flow for Purdue University Northwest, which is located in the Northwest Indiana urban region. Based on the simulation results, the optimal location was identified for urban wind turbine siting.


2016 ◽  
Vol 36 (3) ◽  
pp. 318-332 ◽  
Author(s):  
Zhenyu Wu ◽  
Guang Hu ◽  
Lin Feng ◽  
Jiping Wu ◽  
Shenglan Liu

Purpose This paper aims to investigate the collision avoidance problem for a mobile robot by constructing an artificial potential field (APF) based on geometrically modelling the obstacles with a new method named the obstacle envelope modelling (OEM). Design/methodology/approach The obstacles of arbitrary shapes are enveloped in OEM using the primitive, which is an ellipse in a two-dimensional plane or an ellipsoid in a three-dimensional space. As the surface details of obstacles are neglected elegantly in OEM, the workspace of a mobile robot is made simpler so as to increase the capability of APF in a clustered environment. Findings Further, a dipole is applied to the construction of APF produced by each obstacle, among which the positive pole pushes the robot away and the negative pole pulls the robot close. Originality/value As a whole, the dipole leads the robot to make a derivation around the obstacle smoothly, which greatly reduces the local minima and trajectory oscillations. Computer simulations are conducted to demonstrate the effectiveness of the proposed approach.


Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2404 ◽  
Author(s):  
Francisco Fabra ◽  
Willian Zamora ◽  
Julio Sangüesa ◽  
Carlos T. Calafate ◽  
Juan-Carlos Cano ◽  
...  

As the number of potential applications for Unmanned Aerial Vehicles (UAVs) keeps rising steadily, the chances that these devices get close to each other during their flights also increases, causing concerns regarding potential collisions. This paper proposed the Mission Based Collision Avoidance Protocol (MBCAP), a novel UAV collision avoidance protocol applicable to all types of multicopters flying autonomously. It relies on wireless communications in order to detect nearby UAVs, and to negotiate the procedure to avoid any potential collision. Experimental and simulation results demonstrated the validity and effectiveness of the proposed solution, which typically introduces a small overhead in the range of 15 to 42 s for each risky situation successfully handled.


Author(s):  
Nikhil Kumar Singh ◽  
Sikha Hota

The paper computes optimal paths for fixed-wing unmanned aerial vehicles with bounded turn radii to follow a series of waypoints with specified directions in a three-dimensional obstacle-filled environment. In the existing literature, it was proved that the optimal path is of circular turn–straight line–circular turn (CSC) type for two consecutive waypoint configurations, when the points are sufficiently far apart and there is no obstacle in the field. The maximum of all minimum turn radii corresponding to all possible two-dimensional circular maneuvers was used for both the initial and final turns to develop the CSC-type paths. But, this paper considers the minimum turn radii for initial and final turns, corresponding to the maneuvering planes and which produces shorter CSC-type paths. In an obstacle-filled environment the shortest path may collide with obstacles, so a strategy is proposed to switch to the next best path that does not collide with obstacles. Using this technique, a series of waypoints is followed in the presence of obstacles of different types, for example, cylindrical, hemispherical, and spherical in shapes with different sizes. Finally, simulation results are presented to show the efficiency of the algorithm for obstacle avoidance. The computation time listed here indicates the potentiality of this algorithm for implementation in real time.


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