Vision-Based Hierarchical Impedance Control of an Aerial Manipulator

This article presents an image-based impedance control scheme for an under-actuated aerial manipulator. Unlike the existing Cartesian cascade control (admittance control) scheme, we design an image-space visual servoing controller at the dynamic level to achieve compliant interaction with unknown environments. Furthermore, compared with the state of the art in aerial interaction control, feedback of both the external wrench and the Cartesian position of the aerial manipulator are not required. To cope with the under-actuation property of the system, an attitude tracking control task is designed in such a way that it is dynamically decoupled with the visual impedance control task. Convergence of the task-space tracking error is proven based on the Lyapunov theory. The finite-gain${\mathcal{L}}_2$stability of the system regarding external force/disturbance is also proven. Indoor experiments are conducted to demonstrate the proposed method.