engleski

Quadcopter Altitude Control Methods for Communication Relay Systems

Background Owing to the rapid development of hardware components and reduction in prices, Unmanned Ariel Vehicles (UAVs) are becoming ubiquitous including application to airborne ad- hoc communication relay stations. Quadcopters are one class of UAVs which has particularity seen rapid growth due to its versatility. Since quadcopters are inherently unstable and hard to stabilize by a human operator, they need automated attitude stabilization. However, altitude stabilization around desired height is often overlooked, while it has an important role in an optimal location for airborne communication relay. Objective The paper addresses the issue by developing controllers for UAV hovering. The proposed approach can then be extended to arbitrary height (possibly with different sensor setup). Method For the development of control schemes, two approaches were used: PID and Neural network (NN) based one. For the development of NN (i.e. learning phase), Gazebo simulation environment was used essentially modeling the human driver. Developed approaches were tested both in simulation and in the real- world scenario on AR.Drone 1.0 and AR.Drone 2.0 UAVs. Results Obtained indoor results demonstrated PID accuracy of 1 cm with an overshoot of 2.7% and settling time of 3.75 s, while NN demonstrated 2.1 cm, 1%, and 8.4 s, respectively. Outdoor testing was also performed with similar result trends. Conclusion Both developed controllers demonstrated good results (indoor and outdoor) and could be used in the real-world scenario, but NN due to its favorable characteristics (i.e. human driver modeling) and straightforward development phase (as compared to PID which involves a lot of trial-and-error) is preferred.

altitude control, communication relay, neural network, PID, stabilization, UAV, simulation

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