Lightweight compliant arm for aerial manipulation

This paper presents the design and experimental validation of a low weight compliant arm for aerial manipulation, which uses a linear actuator to move the elbow joint. The proposed arm design allows for estimating payload mass, as well as detecting collisions against obstacles in the forearm. The compliant arm design is intended to be applied in aerial manipulation and transportation, being mounted on the base of an Unmanned Aerial Vehicle (UAV) like a multirotor or a small autonomous helicopter. The payload mass estimation can be useful in the adaptation and stabilization of UAV altitude and attitude controllers when objects of unknown weight are grasped by the arm, while compliance reduces the effect of physical interaction when lifting an object on UAV stability. The paper addresses the mechanical design and construction of a three DoF arm prototype (elbow, wrist roll and pitch), deriving the equations for estimating the payload mass. A set of experiments for payload mass estimation and collision detection and reaction have been performed to test the validity of the approach.