Lyapunov-based coordinated control of an underactuated unmanned aerial vehicle and robot manipulator

This Ph.D. dissertation describes nonlinear tracking control results for a quadrotor helicopter unmanned aerial vehicle (UAV) towards the ultimate goal of controlling a combined UAV plus robot manipulator system (UAVRM). The quadrotor UAV is a helicopter that has four independent rotors that provide vertical lift: these four independent forces are managed in order to directly provide lift, pitch, roll, and yaw of the vehicle. Horizontal translations result from pitch and roll actions, the system is underactuated in the sense that there are only four control inputs to move the six degree-of-freedom aircraft. There are existing dynamic models of the quadrotor UAV that relate the input forces and torques to position, velocity, and acceleration. Use of these dynamic models for model-based UAV control design is explored. First, a parametric uncertain model of the UAV system was considered. A robust control approach is proposed to account for the fact that the model parameters are difficult to measure exactly in a physical system. The controller uses full state feedback signals and a robust control scheme is designed to compensate for the unknown parameters in each dynamic subsystem model using a Lyapunov-based approach. Lyapunov-type stability analysis suggests a global uniform ultimately bounded (GUUB) tracking result. Next, the difficulties of UAV state measurement is considered; specifically, where only the output position signals are available but no velocities or acceleration signals are measurable. The output feedback control proposes a new control approach for trajectory-tracking by the quadrotor family of small-scale unmanned aerial vehicles (UAV), in which only the positions and yaw angle are measured. The tracking control result is achieved using an observer, which estimates velocity signal based on exact knowledge of the dynamic modeling of equation. An integrator backstepping approach is applied to this cascaded and coupled nonlinear dynamic system to perform an observer and closed-loop controller design via a Lyapunov-type analysis. A semiglobal, uniformly ultimate bounded (SGUUB) tracking result is achieved. The application of remote robots equipped with a robotic hands or arms, has been growing in applications where it is dangerous or inconvenient to use direct human intervention. Recently, the area of unmanned aerial robot system has seen an amazing growth in both military and civilian applications. UAVs have the distinct advantage of being able to move rapidly, free of ground obstacles. Most current applications of the aerial robot system use the UAV as “eye-in-the-sky” for surveillance and monitoring applications. Projecting the intersection of these two trends, if the integration of robot manipulator and aerial robot system is possible, the system could be fast moving and avoid obstacles, but also useful for manipulating physical systems once in place, e.g., changing a lightbulb on a radio tower. This is the ultimate purpose of the work contained in this dissertation - the development of the unmanned aerial-robotic system. A model of the combined UAV and robot manipulator is proposed from which a coordinated controller of the integrated nonlinear system is developed using a Lyapunov-type method. The design goal for this controller is to simultaneously control the two degree-of-freedom robot manipulator (RM) and the quadrotor Unmanned Aerial Vehicle (UAV) to create a six degree-of-freedom UAV-Robot Manipulator (UAVRM). The UAVRM end-effector can track three desired positions and three angles using feedback signals.