Image-Based Time-Varying Contact Force Control of Aerial Manipulator Using Robust Impedance Filter

The use of aerial manipulators for safe and efficient physical interaction with their surrounding environments has been gaining attention within the aerial robotics research community. In this letter, we present an image-based time-varying force tracking controller for an aerial manipulator conducting forceful interaction with a static surface. To this end, we first extract visual features from the surface using a monocular camera and calculate image feature vectors for the rotational and translational movements of the camera. Then, the RISATE (Robust Integral of SATuration Error)-based impedance filter continuously updates the desired values of the image features based on the previously designated force profile. Our stability analysis verifies that the error between the desired and actual contact force is uniformly ultimately bounded in an arbitrarily small bound with the proposed strategy even with the switching between free-flight and contact modes. Moreover, through time-varying force-tracking experiments with a quadrotor-based aerial manipulator, we validate the reproducibility and improved force-tracking performance of the proposed method.