PID-controller-based hovering for a quadcopter

Abstract

Drones have seen a surge in popularity during the 2000s, being employed in an increasing number of different tasks considering both professional and recreative use cases. The purpose of this thesis was to implement a hovering feature for a small quadcopter. The feature was made using a proportional-integral-derivative controller that utilizes height data from a time-of-flight sensor attached to the bottom side of the quadcopter. The controller is run on a host PC and instructions are sent to the quadcopter wirelessly. The Ziegler-Nichols method was used to obtain initial PID gains, followed by iterative hand-tuning to obtain better results. Experiments done after the tuning process showcase that the control system is generally able to maintain the quadcopter’s altitude within 15% of the target. However, it is noted that occasionally the system suffers from instability and horizontal drift, the latter of which could not be explained. Future work proposed includes using a model-based tuning method and embedding the controller into the drone’s firmware to obtain better results and remove the effects of latency caused by wireless communication. Additionally, the possibility of expanding the implementa-tion into a complete flight controller capable of adjusting the quadcopter’s full position and attitude is proposed.