Design and Modeling of an Autonomous Parafoil for Rover Mars Landing

There are many ways to study space objects, such as using telescopes on Earth, satellites and orbiters near the study object or rovers on its surface. Some planets and moons of our Solar system have an atmosphere, and in the last decades new types of vehicles, like drones, conventional airplanes or lighter-than-atmosphere vehicles, were designed to explore these space objects in a new way. These types of vehicles, called aerobots, enable to have a greater range of exploration than rovers, and also a higher resolution of images and information than an orbiter, but for obvious reasons can be applied only in planets or moons with an atmosphere, like Mars, Venus and Titan. In this thesis two different types of aerobots are presented for a mission on Mars: a drone and a parafoil, which have very different characteristics and applications. The first one can be used to explore unreachable regions for a conventional rover, like caves or deep craters, and to identify appropriate future human landing sites. On the other hand the parafoil system can be used for autonomous precise landings: it is a good compromise between a conventional airplane, which is more controllable, and a parachute or a baloon, which are lighter and easier to transport inside a space vehicle. Even if both aerobots are considered, this thesis is focusing on the modeling and design of the parafoil system. For this reason in the first part an introduction to space drones and aerobots for space exploration is presented. Moreover, drone and parafoil dynamics and kinematics and mars enviroment model are also included. In the second part the design and modeling of the parafoil's dynamics simulator is discussed for studying the feasibility of the system and its behavior in the martian atmosphere. The thesis outlines the preliminary design of the parafoil to fly in the thin martian atmosphere. Then a 6 DoF (Degrees of Freedom) trajectory simulator is developed, without taking into account the apparent mass effect, due to the low density of the martian atmosphere. A lateral track proportional control law has been selected as guidance algorithm, which generates the reference command for the actuators using inertial velocities and position of the parafoil. This guidance algorithm was also tested with the implementation of a wind model to study the performance of the system.