Advances in the Development of a Spherical Rover for Planetary Exploration – Part 1: Design

The thesis focuses on the advances in the design, performance analysis and control strategy of a spherical rover actuated by a 2-dof pendulum. Designed for space exploration, the choice of rover's spherical shape offers several advantages. The presence of a continuous solid shell provides effective protection for the internal mechanism and makes the rover suitable for harsh environments, as it is immune to overturning and efficient in absorbing impacts. The design goals include the ability to move at a constant speed over 15º slope surfaces incline and to overcome 10-cm-height steps. To address the inherent limitations of the design, a gyroscope system is included. The gyroscope system provides auxiliary propulsion to the main system, allowing enhanced performances. This feature is based on the physical principle of angular momentum conservation. The work has been divided in two theses. In the following, developments concerning the revision and the re-configuration of both the mechanical and electronic design are presented. The work starts from the previous design of a spherical rover, and considering the analysis of the state of the art. The inherited project reached a functional state. This thesis examinates and redefines the critical construction elements. Choices were made as compromise between structural reliability, transmission efficiency, and internal disposition. Positioning of system center of gravity played a fundamental role to achieve optimal performances. Subsequently, sensors and control devices were selected for the imposition of the primary and gyroscopic actuation. Signal transmission, processing efficiency, and energy consumption were considered to choose the components. Market availability and costs were deemed when selecting both mechanical and electrical components. The structural parts have been redesigned. The final barycenter position allows optimal motion management. FEM analyses were made for the sizing of the elements in various load conditions, satisfying design requirements have been met. The results of this part of the work culminate in a rover design suitable for prototyping.