<p>A unique combination of a tethered aerial drone, integrated</p>
<p>with a lightweight manipulator is proposed to overcome the challenges during the inspection of confined spaces at elevated heights, where a four degrees-of-freedom</p>
<p>cable-driven manipulator is presented, along with a continuous backbone design, inspired by the flexible ruler, which offers high bending stiffness in the vertical direction to minimize downward deflection of the manipulator, with low bending stiffness in the horizontal direction to maximize the flexibility of maneuvering in confined and complex spaces.</p>