Mithun Diddi’s PhD Dissertation Defense

“Multiple UAVs for Synchronous – Shared Tasks and Long-term Autonomy”

Abstract:

This thesis focuses on the use of multiple unmanned aerial vehicles(UAVs) in a distributed framework from a systems perspective to synchronously perform shared tasks such as aerial beamforming and coordinated mapping and to enhance the reliability of performing periodic (mapping) tasks at remote locations for long-term autonomous(LTA) missions. We present an autonomy stack for multiple, heterogeneous UAVs with a simulation framework. We implemented the end-to-end pipelines for perception and communication applications involving multiple UAVs.

Repeated deployments in harsh-weather, real-world locations are challenging and are limited by the need for human operators. These infrastructure-poor, remote locations pose unique challenges to long-term autonomous missions. In these locations, harvesting power onboard using solar panels may be a viable alternative for recharging batteries.
In the first part of the thesis, we focus on hardware architecture for UAVs to enable reliable LTA missions with minimal human intervention. We developed a Size, Weight, and Power(SWaP) constrained Smart charging stack to minimize hotel loads seen during the recharging process and enable efficient charging of batteries. This leads to the design of a standalone, solar rechargeable quadcopter.
Real-world applications such as reconstructing a dynamic scene from multiple viewpoints and distributed aerial beamforming require multiple robots(agents) to coordinate and synchronously act to accomplish shared tasks. These tasks require spatially distant, multiple UAVs to have time, phase, and frequency synchronization. We demonstrate a Synchronous UAV(S-UAV) architecture for wireless synchronization based on GPS disciplined oscillators and the associated software framework needed for temporal registration of data across multiple UAVs.
We have built four S-UAVs and demonstrate the ability to 3D reconstruct a dynamic scene from overlapping viewpoints. Dynamic baseline camera arrays formed using multiple S-UAVs are used to synchronously capture a dynamic environment with people moving around. A single-time instance of synchronously captured images of the scene is used to 3D reconstruct the dynamic environment while preserving static scene assumptions of Structure from Motion(SFM).

In the second part of the thesis, we focus on multi UAV autonomy framework for real-world applications of UAVs in perception, wireless communications, and reliable LTA missions. We present ‘Simplenav,’ a navigation stack for heterogeneous, multiple UAVs, and ‘OctoRosSim,’ a computationally lightweight multi-UAV simulation framework for validating the multi-UAV planning and autonomy pipeline. We demonstrate this framework with novel applications of end-to-end autonomy pipelines developed for a coordinated swarm of UAVs.

Committee:

Prof. Hanumant Singh (Advisor)

Prof. Kaushik Chowdhury

Prof. Taskin Padir