ESA GNC Conference Papers Repository
Autonomous Guidance for Electrical Orbit Raising
We present the results of an ESA R&D study (ARTES funding) which looked into on-board guidance strategies for reducing ground workload over long electrical transfers, that would be similar to current ground-based approaches in terms of time/fuel optimal-ity, while being compatible with on-board resources. This move is encouraged by the prospect of autonomous GNSS-based navigation on-board telecom platforms. The study investigated two major approaches: - semi-autonomous solutions are an extension of the current strategy for Electrical Orbit Raising (EOR): adding on-board navigation data and smart compression allows to extend the validity of a ground-optimized guidance profile from weeks to months, reducing ground intervention five-fold. - fully autonomous solutions represent a significant step further, where the on-board system can autonomously compute an optimum guidance scenario (thrust profile and complete 3-axis attitude trajectory), based on the latest GNSS data, thus limiting ground intervention to health-checks and collision-risk monitoring. After comparing several alternatives, a best solution was selected for each approach. The candidate solution for the fully autonomous approach was then implemented in de-tail. Functional simulations over a complete transfer showed the performance was within 2% of the true optimum. The guidance software prototype then went through a formal code-generation process and tested on flight-representative hardware. The results of the Processor-In-the-Loop test campaign show that the CPU load amounts to less than 1%: this demonstrates that the fully autonomous guidance algorithms can indeed be implemented on board.