Perception-driven Formation Control of Airships

For tracking and motion capture (MoCap) of animals in their natural habitat, a formation of safe and silent aerial platforms, such as airships with on-board cameras, is well suited. However, unlike multi-rotors, airships are severely motion constrained and affected by ambient wind. Their orientation and flight direction are also tightly coupled. Therefore, state-of-the-art MPC-based formation control methods for perception tasks are not directly applicable for a team of airships. In this paper, we address this problem by first exploiting a periodic relationship between the airspeed of an airship and its distance to the subject. We use it to derive analytical and numeric solutions that satisfy the MoCap perception constraints. Based on this, we develop an MPC-based formation controller. We performed detailed analysis of our solution, including the effects of changing physical parameters (like angle of attack and pitch angle) on it. Extensive simulation experiments, comparing results for different formation sizes, different wind conditions and various subject speeds, are presented. A demonstration of our method on a real airship is also included. We have released all of our source code at https://github.com/robot-perception-group/Airship-MPC. A video describing our approach and results can be watched at https://youtu.be/ihS0_VRD_kk