In the context of an increasing worldwide and European effort to improve the affordability of space transportation, DEIMOS Space Romania is leading an activity to further develop and mature GNC technologies for future European reusable space applications.
Building on past experience, in the REVLANGNC project the design of innovative GNC solutions is consolidated for the terminal entry (TAEM) and descent and landing phases (D&L). The recovery strategy is based on parafoil systems, that will provide the control authority needed in the last phases of the descent to allowing the return vehicle to achieve a soft and precise landing. The consolidated GNC solutions are tested in application scenarios fully representative recovery of critical systems:
- A lifting body vehicle performing a pinpoint landing, where the GNC shall steer the parafoil toward a predefined, fixed, landing site.
- The recovery of a launcher fairing through mid-air retrieval, where the GNC shall steer the parafoil toward a predefined location and maintain a given heading in order to allow a recovery vehicle to approach and perform the recovery manoeuvre
The GNC technologies under development are based on innovative solutions to be able to cope with the challenges imposed by autonomous systems. End-to-end hybrid Navigation assures the continuous estimation of the vehicle state throughout of the phases of the flight, making use of measurements provided by the available sensors (IMU, GNSS, altimeter and FAD(S), if available). The Guidance function make uses of online optimisation techniques to successfully recompute the best path to target depending on the actual flight conditions. Robust control is assured by advanced techniques.
The REVLANGNC activity recently completed the first GNC design review, and the performance obtained for the proposed GNC confirmed its suitability for the targeted application. With this important step achieved, the project moves toward the consolidation of the solutions and its progressively migration to hardware, through SIL and PIL testing, targeting flight tests on small-scale parafoil system by the end of the year.
The 3D model of the parafoil and vehicle is illustrated in the following screenshots:
An example of the vehicle trajectory during part of the descent under parafoil is illustrated in the following screenshot (where the trajectory computed by the Parafoil-Guidance is presented with black and the simulated real trajectory of the vehicle is presented with blue):