Methods and tools for space mission design and analysis, with applications

Research focus

The Peer review has evaluated this group as Average

The research interests in this theme are in the following focus areas: Astrodynamics, in particular non-Keplerian orbits and formation flight. Non-Keplerian orbits are trajectories generated by more than one gravitational attraction. Propellant mass saving occurs by exploiting the nonlinearities arising in the n-body models for the trajectory design. Such “Low Energy” trajectories are difficult to design due to the chaotic motion in nature, although the governing dynamics is Newton-based. These dynamical systems have interesting properties useful for new-concept space mission. Our activity focuses on computation of periodic orbits around the Lagrangian points, design of interplanetary transfers via the “invariant manifolds” technique, and design of Earth-Moon transfers combining low-thrust and lowenergy. The research on formation flight control focuses on the design and control of optimal reconfiguration manoeuvres, necessary for multi-objective missions, to deal with a satellite failure and to introduce new satellites in the formation. Manoeuvres have to be autonomous to reduce ground support and costs. Furthermore efficient algorithms for the station keeping of these complex missions have been developed. Autonomous planning /scheduling (P/S) and execution, failure detection, identification and recovery (FDIR). Researches on agents to enhance the spacecraft autonomy deal with both the deliberative and reactive levels, under the system robustness requirement. Studies are focused on developing an on-board agent prototype facing the real-time reasoning. The complete architecture includes software modules devoted to deliberation, P/S of activities, behaviour based reaction, execution, spacecraft health monitoring and failure detection, system reconfiguration, goal management. Multi-agents scenarios are dealt with too. The P/S problem in a distributed environment with no pre-fixed hierarchy among units has been solved focusing on solution robustness for execution changes. Solutions have been tested on team of collaborating exploration robots, group of mixed humans-robots and low thrust controlled spacecraft flotilla. Regarding FDI in space systems, several approaches and studies have been performed, among which a hybrid approach to the diagnosis task based on the combination of Model Based techniques for autonomous Failures Detection and Abductive Reasoning for their Identification. Hybrid diagnosis couples the main advantages of both approaches and exploits each of them only for the task which is most appropriate for it. Space robotics. Researches deal with vehicles and drilling tools for planetary soil exploration and analysis. Two vehicle prototypes have been realized, to test autonomous navigation algorithms: a six independent wheel configuration, and a six legged configuration, mimicking insects. Three different complementary objectives are of interest: obstacles identification, for short range navigation, 3D map reconstruction of the environment, for long range trajectory planning, and interesting targets recognition. To this end, artificial vision algorithm based on stereo cameras has been developed. Path planning is based on the Artificial Potential Field theory, in which obstacles are associated with repulsive fields and targets with attractive fields. The manoeuvres are generated step by step, considering the local value of the overall potential field. Studies on drilling tools focus on operations management of SD2, Sampler, Drill and Distribution Subsystem, one of the instruments on-board the lander Philae of the ESA Rosetta Mission, and on the drilling process modelling. A test facility has been realized to test the drill behaviour in different environmental scenarios. It is equipped with a sensor system to measure the drill kinematic behaviour, with a translation system to simulate all possible conditions of soil surface, and with specimens having the same structural characteristics of the space body soil. To model the drilling process, a numerical finite elements scheme capable of simulating the interaction between drill and planetary soil is available, to compute the power demand as a function of the drill and soil parameters. Design of micro-satellites. The most relevant activity is the development of the university satellite PALAMEDE, an educational and technological research project aimed at involving students in the complete flow of activities typical for satellite design. The mission objective is Earth observation with a CCD camera and a new type of triple junction solar cell testing. Palamede is built using both terrestrial and space-qualified components, preferring the first whenever possible. The possibility of using off-the-shelf components in lowcost space applications is the secondary purpose. In addition, this project is an important and exciting training experience for involved students. Attitude control. The most relevant activity addresses the design of the control system for very advanced in-orbit scientific and technological experiments that will require extremely accurate line-of-sight control. The Research topic 3.1 - Methods and tools for space mission design and analysis, with applications 2-36 pointing performances are achieved by the utilization of accurate sensors, low disturbance actuators and the development of control schemes which take advantage of state of the art technology.

Dipartimento di afferenza

Dipartimento di Ingegneria Aerospaziale

Docenti afferenti

Franco Bernelli-Zazzera (Full Professor)
Amalia Ercoli-Finzi (Full Professor)
Lorenzo Dozio (Assistant Professor)
Micelle Lavagna (Assistant Professor)