A Dynamic Artificial Potential Field (D-APF) UAV Path Planning Technique for Following Ground Moving Targets

Abstract

Path planning is a vital and challenging component in the support of Unmanned Aerial Vehicles (UAVs) and their deployment in autonomous missions, such as following ground moving target. Few attempts are reported in the literature on multirotor UAV path planning techniques for following ground moving targets despite the great improvement in their control dynamics, flying behaviors and hardware specifications. These attempts suffer several drawbacks including their hardware dependency, high computational requirements, inability to handle obstacles and dynamic environments in addition to their low performance regarding the moving target speed variations. In this paper, a novel dynamic Artificial Potential Field (D-APF) path planning technique is developed for multirotor UAVs for following ground moving targets. The UAV produced path is a smooth and flyable path suitable to dynamic environments with obstacles and can handle different motion profiles for the ground moving target including change in speed and direction. Additionally, the proposed path planning technique effectively supports UAVs following ground moving targets while maneuvering ahead and at a standoff distance from the target. It is hardware-independent where it can be used on most types of multirotor UAVs with an autopilot flight controller and basic sensors for distance measurements. The developed path planning technique is tested and validated against existing general potential field techniques for different simulation scenarios in ROS and gazebo-supported PX4-SITL. Simulation results show that the proposed D-APF is better suited for UAV path planning for following moving ground targets compared to existing general APFs. In addition, it outperforms the general APFs as it is more suitable for UAVs flying in environments with dynamic and unknown obstacles. INDEX TERMS Unmanned Aerial Vehicles, path planning, Artificial Potential Field, ground moving targets.

UAV Path Planning for Reconnaissance and Look-Ahead Coverage Support for Mobile Ground Vehicles

“…Although this method provides waypoints that can easily be implemented in an existing autopilot such as PX4-autopilot [ 38 ] or ArduPilot [ 39 ], symmetric obstacles have proven to be challenging to handle. An enhanced version of the general APFs, the dynamic-APF (D-APF) [ 40 ], accommodates an approach to change the UAV’s altitude in the presence of obstacles to ensure collision avoidance when the UAV is following the MGV. The D-APF repulsive force that controls and changes the UAV’s altitude when obstacles are in the planned path of the UAV is active along the vertical direction.…”

“…The proposed ED-APF was inspired by and extends and enhances the techniques presented in [ 36 , 37 , 40 ]. The proposed ED-APF generates velocity waypoints by simultaneously considering the constraints of following the MGV and the visual coverage quality of the reconnaissance routes and areas.…”

“…The proposed ED-APF generates velocity waypoints by simultaneously considering the constraints of following the MGV and the visual coverage quality of the reconnaissance routes and areas. This is achieved by adopting the concept of the D-APF [ 40 ] for path planning and enhancing the attractive force for following the MGV along a vertical sinusoidal path. The ED-APF’s attractive force controls and adapts to the frequency of the vertical sinusoidal path based on the MGV’s velocity, the camera’s field-of-view (FoV), the average altitude, and the camera fixed gimbal angle.…”

“…The resultant force of the two attractive forces along the horizontal plane and vertical axis is adopted to generate the required velocity waypoints for following the MGV with a variable velocity in a dynamic environment. The attractive force in the horizontal direction is a modified version based on the D-APF attractive force [ 40 ], while was proposed and defined to control the vertical sinusoidal path based on the MGV’s velocity , the onboard camera’s FoV on the horizontal plane and the vertical plane , the minimum relative altitude of the UAV , and the camera-fixed gimbal angle , as follows: where and are the gain factors of the attractive force and the summation gives the maximum magnitude of the attractive force. The constants and control the minimum required displacement and velocity, respectively, to achieve the maximum magnitude of the force.…”

“…They also suffer from local minima and create unnecessarily long paths when obstacles are nearby. Other technique such as the D-APF [ 40 ] plans collision-free paths by changing the UAV’s altitude in the vertical direction; however, it does not compensate and unable to handle dynamic obstacles moving towards the UAV. The ED-APF’s resultant repulsive force is proposed to overcome these drawbacks as it consists of two subrepulsive forces to produce a collision-free path while continuously following the MGV.…”