A framework for collaborative Quadrotor - ground robot missions

Abstract

The thesis proposes a real-time control algorithm for the cooperation of a joint team consisting of a Quadrotor and a Ground robot for coordinated ISR missions. The intended application focuses on indoor environments, where Global Positioning System signals are unreliable or simply unavailable so that the control algorithms must rely on local sensor information. The thesis describes the appropriate set up of the lab and includes simulations using a full dynamic model of the quadrotor and robot, demonstrating the suitability of the implemented and the proposed control scheme into a waypoint navigation scenario. The implemented controller uses the Linear Quadratic Regulator method imposed into five different channels; pitch, roll, yaw, x-y position and height, configured to the appropriate gains for smoother following of the trajectory. The proposed control scheme incorporates three key aspects of autonomy; trajectory planning, trajectory following and collaboration of the two vehicles. Using the differentially-flat dynamics property of the system, the trajectory optimization is posed as a non-linear constrained optimization within the output space in the virtual domain, not explicitly related to the time domain. A suitable parameterization using a virtual argument as opposed to time is applied, which ensures initial and terminal constraint satisfaction. The speed profile is optimized independently, followed by the mapping to the time domain achieved using a speed factor.