In recent years, the use of multi-rotors has been drastically increased both in military and civil applications. Specifically, load transportation using a flock of rotary unmanned aerial vehicles (UAVs) has been widely studied and developed in the last decade. Carrying a load using multiple UAVs allows to significantly increase the maximum weight that can be carried.
Beyond the challenge of controlling the multi-UAV connected to a load system, the ability to keep the load at constant altitude above the terrain exposes us to a field of autonomous complex maneuvers which is attractive for a wide range of applications. In this study we incorporate the terrain following capability into a multi-UAV connected to a load system, which was not addressed in the open literature.
This research revolves around the development of a control algorithm that will allow the safe transportation of a load using a team of three or more octorotors as actuators. The algorithm accounts for different constraints such as safety distance between the octorotors, maximum allowed force each octorotor can provide, and more. The system incorporates a terrain following capability that relies on measurements received from body-fixed Laser Range Finder (LRF) sensors installed on the octorotors.
The algorithm was validated and tested for different scenarios using a realistic 6DOF simulation that incorporates disturbances, measurement noises and model inaccuracies. A parametric study was conducted in order to determine the optimal configuration of the LRF sensors and to examine parameter sensitivity of the setup. The system has demonstrated impressive performance characteristics for a variety of flight conditions.
