Screw-driven robot for locomotion into sand

The locomotion into sand is needed in various applications, but due to the complex mechanics of granular matter it causes special difficulties. High resistance forces on penetration systems and parameter dependent behavior, like stable or instable boreholes, complicate the design of mobile robots for the locomotion in sandy soil. The most effective state of the art devices deploy hammering mechanisms. Screw-driven systems arise more and more in the literature, as they promise to be a simple, robust and low-cost solution. In this paper, an autonomous drilling robot for the locomotion into sandy soils is presented. The design is based on theoretical modeling and experimental analyses of the screw drive aiming to minimize the needed torque and to maximize the locomotion speed. The presented prototype is able to reach a depth of 20 centimeters within a minute with a torque of 0.66 Nm