An Extended HTN Language for Onboard Planning and Acting Applied to a Goal-Based Autonomous Satellite
Filipe Cividanes, Mauricio Goncalves Vieira Ferreira, Fabrlcio Kucinskis · IEEE Aerospace and Electronic Systems Magazine · 2021
Nowadays, there is an increasing demand to design space systems with a higher level of onboard autonomy. One way to achieve this is to equip the satellite flight software with an autonomous decision system, such as model-based planning techniques. This article addresses an extended Hierarchical Task Network (HTN) description language for satellite onboard mission planning and acting. Our proposal seeks a lightweight and practical approach to model the space system and at the same time meets the current demands (scalability, intelligibility, and performance) for an autonomous satellite. To promote a clear understanding of the proposed language, we provide a grammar for the hierarchical domain and onboard problem representation. A realistic case study focused on a Brazilian remote-sensing satellite illustrates the effectiveness and practicability of our language. An onboard HTN planning approach is also implemented to verify in practice the usability of the model. We carry out experimental scenarios on a typical setup of satellite onboard computer using a space-qualified processor. The results obtained show that our proposal could overcome the main setbacks of the temporal planning model, which is the prevailing approach in the space domain until today.