Realistic Guidance Performance during Lunar Rendezvous with Third Body Perturbation

The paper describes the performance of a guidance law based on the Adjoint and SDRE methods in presence of reality representative models of sensors and actuators during the rendezvous phase of the proposed Heracles mission to the Moon. In recent years, the increased interest in returning to the Moon has motivated the necessity to develop accurate models for the analysis of missions that takes into account realistic system components. The paper reviews the mission’s details, the rendezvous/berthing guidance algorithm with third body perturbation, and sensor’s and actuators state of the art models. A Montecarlo analysis is used to validate the models in order to satisfy the safety of the trajectory. The results show that the proposed guidance and control are capable of maintaining safe relative motion between the vehicles

A Minimum-propellant Pontryagin-based Nonlinear MPC for Spacecraft Rendezvous in Lunar Orbit: the Extended Version

We propose a Nonlinear Model Predictive Control approach to spacecraft rendezvous in non-Keplerian Lunar orbits. The approach is based on the Pontryagin Minimum Principle and allows the accomplishment of minimum-propellant maneuvers. The relative motion between the chaser and the target is described by the nonlinear and unstable dynamics of the circular restricted three body-problem. In the proposed formulation, we design a minimum-propellant controller, which leads to a bang-bang behavior of the control signal. Under suitable assumptions, simplified dynamics is employed as prediction model, in order to reduce the complexity of the controller algorithm but, at the same time, without penalizing the controller tracking performance. The proposed approach's effectiveness is validated by a simulation example

LABCAM: Development for robotic simulation of space environment

This thesis has been done for ESA(European Space Agency) during an internship of 6 months in ESTEC, Noordwijk (Nl). It faces the challenges to reproduce Guidance, Navigation and Control's space conditions in a laboratory, passing trough all the phases of a laboratory's equipment design,testing and scenario-scaling. The author wants to underline the importance of the testing phase, especially in space mission design procedure: everything in space has to be reliable and robust. But not only, the testing phase is fundamental to design innovative algorithms and solutions. So the script is articulated in the phases described below. First of all the reader is introduced to the terminology of visual cameras and laboratories. After a general set-up's description, the third chapter explains in details all the requirements and constraints that had to be satisfied during the selection and design process.\\ Then the hardware and the software solutions are presented: everything has been done to be as much space-representative as possible without losing the ease in the use, the reliability and the versatility. During the design process was maximising the use of commercial and open-source components. Moreover, a lot of attention was given to the distortions' correction, the noise lowering and the error reduction. In fact they influence negatively the experiments' success.\\ In Chapter \ref{Scale_traj} is described the selected test-mission: Asteroid Impact Mission (AIM). In the same chapter is enunciate the procedure to scale space representative trajectories in a robot's work-space. Then all the implemented parts were tested and the results are reported in Chapter 7. For what that has not been possible to implement (e.g.vignetting correction and refocusing algorithm), some solutions were given. To conclude,it is possible to say that the set-up satisfy the most of the ESA's requirements with good and innovative solutions. Moreover the design's process has opened theoretical questions that it is interesting to deepen in the future: the dynamic camera calibration and correction, the dynamic vignetting correction, the refocusing problem etc

Guidance and Control for Phasing, Rendezvous and Docking in the Three Body Lunar Space

The renewed interest in Moon exploration motivates this thesis work, whose primary goal is the development of a fully safe, realistic, and automatic rendezvous strategy between a passive vehicle and an active one orbiting in trans-lunar. The first step of the research was to extend the 3-DOF translational model of the relative motion to a full 6-DOF described in the LVLH reference frame, which results in the most suitable for the design of the guidance. Nevertheless, it entails difficulties due to the need of expressing the various quantities within a non-inertial reference frame. Once the dynamics were defined under the CR3BP and the ER3BP is formulated the following step was to include the description of the sensors and the actuators in the model to ensure the reliability of the proposed GNC solution even in the presence of non-idealities. Therefore the selection and the design of proper Guidance and Control algorithm was fundamental at this point. In fact, later in this thesis the two techniques to control the attitude and the full model are discussed to accomplish the approaching maneuver in the exemplificative scenario of the ESA's HERACLES mission were presented. Afterward, the safety, in particular, the passive safety concept is introduced and different techniques to guarantee it is discussed. The main underlying idea is to exploit the concept, of stable and unstable manifolds to intrinsically guarantee some properties at each Hold-point. A study on the phasing part is also included in this elaborate, it is mostly a preliminary study based on the \gls{CR3BP} hypotheses but it provides significant results on the expected energy consumption Delta V boundaries to guide a spacecraft from a Moon LLO to the LOPG NRHO. In conclusion, the thesis compensates for another lack in the literature with the comparison between the Ephemeris model and CR3BP and ER3BP models, to validate all the proposed results and to identify the related limits. All the discussed work is currently implemented as a MATLAB simulator, called ROSSONERO, that allows the simulation of multiple rendezvous/phasing trajectories

A Minimum-propellant Pontryagin-based Nonlinear MPC for Spacecraft Rendezvous in Lunar Orbit

We propose a Nonlinear Model Predictive Control approach to spacecraft rendezvous in non-Keplerian Lunar orbits. The approach is based on the Pontryagin Minimum Principle and allows the accomplishment of minimum-propellant maneuvers. The relative motion between the chaser and the target is described by the nonlinear and unstable dynamics of the circular restricted three body-problem. In the proposed formulation, we design a minimum-propellant controller, which leads to a bang-bang behavior of the control signal. Under suitable assumptions, simplified dynamics is employed as prediction model, in order to reduce the complexity of the controller algorithm but, at the same time, without penalizing the controller tracking performance. The proposed approach's effectiveness is validated by a simulation example

Integrated Conceptual Design and Parametric Control Assessment for a Hybrid Mobility Lunar Hopper

The lunar lava tubes are envisioned as possible hosting structures for a human base in the Moon’s equatorial regions, providing shelter from radiations, micrometeoroids, and temperature excursion. A first robotic mission is set to scout the habitability of these underground architectures in the near future. The communication inside these underground tunnels is heavily constrained; hence, the scouting system should rely on a high degree of autonomy. At the same time, the exploration system may encounter different types of terrain, requiring an adaptable mobility subsystem able to travel fast on basaltic terrain while avoiding considerable obstacles. This paper presents a cave explorer’s mission study and preliminary sizing targeting the lunar lava tubes. The study proposes using a hybrid mobility system with wheels and thrusters to navigate smoothly inside the lava tubes. The peculiar mobility system of the cave explorer requires an accurate study of the adaptability of its control capabilities with the change of mass for a given set of sensors and actuators. The combination of conceptual design techniques and control assessment gives the engineer a clear indication of the feasible design box for the studied system during the initial formulation phases of a mission. This first part of the study focuses on framing the stakeholders’ needs and identifying the required capabilities of the cave explorer. Furthermore, the study focuses on assessing a design box in terms of mass and power consumption for the cave explorer. Following different mission-level assessments, a more detailed design of the cave explorer is discussed, providing an initial design in terms of mass and power consumption. Finally, the objective shifts toward studying the performances of the guidance, navigation, and control (GNC) algorithms varying the mass of the cave explorer. The GNC significantly impacts the design box of the surface planetary system. Hence, investigating its limitations can indicate the feasibility of mass growth to accommodate, for example, more payload

Optimal time-fixed impulsive non-Keplerian orbit to orbit transfer algorithm based on primer vector theory

The work applies a systematic method to compute an optimal transfer trajectory between two non-Keplerian halo orbits in the Circular Restricted Three-body formulation of the Earth–Moon dynamics. The paper exploits the knowledge of the natural non-linear dynamics and the primer vector theory applied to the Circular Restricted Three Body Problem to design optimal multi-impulsive Halo-to-Halo transfers with fixed and limited Time of flight, from every point of the departure orbit to every point of the arrival orbit with an optimal number of impulses. The used method is constituted by three systematic steps with the goal of facilitating the mission design process and the on-board autonomous guidance implementation of future missions in highly non-linear dynamics