A hybrid pose / wrench control framework for quadrotor helicopters

This paper presents a hybrid pose / wrench control framework for quadrotor helicopters, allowing direct contact of the quadrotor with its environment and stable motion while in contact. The presented work explicitly takes into account the quadrotor's underactuation and utilizes a wrench estimator, able to estimate the wrench generated by the quadrotor using only quadrotor inputs and pose measurements. Experimental results of the quadrotor in pose and hybrid pose-wrench control mode are presented, showing stable behaviour while moving in contact. Whereas a lot of research nowadays is focused mainly on free-flight applications, stable and robust wrench control of quadrotors in direct contact with their environment, opens up new application areas for this class of flying robots.