Optimization-based trajectory planning with adaptive SMC for space applications

In the history of the space exploration, the ability to navigate, rendezvous and interact with a target in orbit always had profound importance. As our understanding of the cosmos deepens, the demand for advanced satellite systems capable of undertaking more complex missions has grown exponentially with newer challenges upfront. The number of unmanned missions and satellite has recently risen more than ever, driving a potential revolution in satellite operations thanks to topics like space debris removal, on-orbit servicing and formation flying. These activities have recently taken some spare of the space market as they are now supported and adopted inside the space companies. ESA is developing the “Clean Space” program and has already expressed interest in starting on-orbit servicing missions to extend the life of the already orbiting satellites instead of having them replaced (with every kind of waste inferred) or having to lunch more. Mission planning is a key topic of interest, including the selection and sequencing of targets, along with the optimization of transfer trajectories. The objective of this thesis is the design of a guidance algorithm, able to generate an onboard trajectory, and of an adaptive control system. This thesis is a comprehensive exploration of a 3DOF orbital simulator developed in MATLAB Simulink which aims to replicate the dynamics of a satellite engaged in a complex multi-target rendezvous mission. It consists of several key components: a system, which models the satellite's behaviour in orbit, a guidance model for path determination, a controller model for decision-making, an actuator model, and a disturbance model for orbital perturbations. The specific scenario considered involves a satellite in Low Earth Orbit (LEO) pursuing a target within the valid range of the Hills Equation. The control system's primary objective is to navigate the satellite into proximity with the target and execute rendezvous manoeuvres while accounting for uncertainties and variations common in complex missions. The results obtained show the system successfully completing the rendezvous with different mass properties and in different starting positions. An investigation was conducted to determine the influence of the guidance parameters on the resulting trajectories and some correlations were found with the time needed and propellant consumed in the mission.