Adaptive impedance control of UAVs interacting with environment using a robot manipulator

In this paper, a nonlinear adaptive impedance controller is proposed for UAVs equipped with a robot manipulator that interacts with environment. In this adaptive controller, by considering the nonlinear dynamics model of the UAV plus the robot manipulator in Cartesian coordinates, all of model parameters are considered to be completely uncertain and their estimation is updated using an adaptation law. The objective of the proposed adaptive controller is the control of manipulator´s end-effector impedance in Cartesian coordinates to have a stable physical interaction. The adjustable Cartesian impedance is a desired dynamical relationship between the end-effector motion in Cartesian coordinates and generalized external forces and moments acting on the system. The asymptotic tracking performance and global stability of the system are proved using Lyapunov stability theorem. Using simulations on a quadrotor UAV connected to a multi-DOF robot manipulator, the effectiveness of the proposed controller is investigated.