Control strategies comparison and performance evaluation for a reusable VTVL platform based on a rocket engine
Creators: name:  T. AFILIPOAE 
name:   A. NECULAESCU 
name:   P. SIMPLICIO 
name:   S. BENNANI 
name:   H. STRAUCH 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: REUSABLE SYSTEMS
FLIGHT PHYSICS
DYNAMICS

description: The international trend in space business is proving the ability to reuse space technology and this can be easily seen in the space exploration and transportation scene with all major players putting a lot of effort to demonstrate all these technologies which will lead to profitability on the long run. In this context, the Ascent and Descent Autonomous Manoeuvrable Platform (ADAMP) initiative is undertaken as a development by the National Institute for Aerospace Research Elie Carafoli INCAS Romania with the support of the European Space Agency (ESA), through the General Support Technologies Program (GSTP) and the Romanian Space Agency (ROSA). ADAMP initiative addresses one key element for space technology innovation, which is rapid turnaround and low-cost system testing. ADAMP will serve as an in-flight testing platform for several control strategies, for real time autonomous and fuel optimal guidance strategies, for safe precision landing innovative techniques, as well as hardware components such as sensors, computers and on-board cameras. ADAMP activity consists of the development of a reusable test platform through building an experimental Vertical Take-Off and Landing (VTVL) platform accompanied by the corresponding facilities, personnel and procedures. This will allow to host testing and verification and validation campaigns for other companies and institutes in a fast and reliable manner, as well as to readily tailor experiments for bigger space programs. ADAMP builds up on the heritage of the previous vehicle developed by INCAS, Demonstrator for Technologies Validation (DTV) [R1]. ADAMP platform 1st fully integration testing flight is planned for early 2022. In the frame of the ADAMP project, a Flight Simulator consisting of guidance and control algorithms as well as a moderate fidelity plant model within Matlab-Simulink environment has been developed at INCAS. This type of platform poses several challenges that must be adequately tackled through control design: time-varying propellant sloshing, low control effectiveness, strong interactions between control loops, Thrust Vector Control (TVC) and guidance frequencies, as well as dynamical perturbations such as model uncertainties and atmospheric turbulence, which are critical for any launch vehicle [R2]. The Flight Simulator is used for the implementation and testing of different control strategies for the ADAMP platform and, in this article, two control strategies for the reusable VTVL platform are developed, discussed and compared. The first control strategy considers nonlinear sliding mode controllers for translational, pitch and roll motions. The second control strategy is based on robust control theory and relies on self-scheduled structured H-infinity optimisation [R3]. As a conclusion, this article will present the synthesis and analysis of two different control strategies for ADAMP VTVL testing platform, clearly highlighting their strengths and challenges in terms of robustness, stability and practical implementation. [R1] Ana-Maria Neculaescu, Alexandru Marin, Adrian Toader, et al., System Identification and Testing for a VTVL vehicle, EUCASS Conference 2019 [R2] Pedro Simplicio, Andres Marcos, Samir Bennani, New Control Functionalities for Launcher Load Relief in Ascent and Descent Flight, EUCASS Conference 2019 [R3] Diego Navarro-Tapia, Andres Marcos, Samir Bennani and Christophe Roux, Structured H-infinity and Linear Parameter Varying Control Design for the VEGA Launch Vehicle, EUCASS Conference 2017.