Reduced Actuator Set for Pressure Control and Thrust Distribution for Multinozzle Propulsion Systems

This study investigated an approach to reduce the number of actuators used for internal pressure control and thruster allocation in a multinozzle solid propulsion system. In the proposed design, the throat areas of four divert nozzles are controlled by only three actuators, and chamber pressure maintenance and thrust distribution are achieved by controlling the throat areas. Using the proposed actuator set, thrust allocation can be accomplished in a more efficient way than when independent actuators are employed for each nozzle

In-Plane Formation Reconfiguration with Radial Maneuvers (vol 43, pg 1881, 2020): In-Plane Formation Reconfiguration with Radial Maneuvers

In the original article [https://doi.org/10.2514/1.G004933], the fifth element of the relative orbit elements (ROE) vector should be δiy, the y component of the relative inclination vector. Therefore: The correct notation for Eq. (1) is. (Formula presented).</p

In-plane formation reconfiguration with radial maneuvers

Formation reconfiguration with impulsive maneuvers has been continuously addressed in recent decades. The studies mostly focused on in-plane formation reconfiguration since the out-of-plane motion is independently controlled by a single burn. Most in-plane reconfiguration studies, meanwhile, rely on tangential maneuvers because of fuel efficiency and controllability of the orbital energy, compared to radial maneuvers. In this paper, the perspective differs that little influence of the radial maneuvers on the orbital energy is considered as a benefit rather than a drawback. By employing radial burns only, an effect of the thrust errors on the semimajor axis control error can be minimized. Both numerical simulations and sensitivity analysis demonstrate the robustness of the proposed radial impulsive burns compared to the conventional tangential impulsive control schemes.Space Systems Egineerin

Orbit deployment and drag control strategy for formation flight while minimizing collision probability and drift

The compact form factor of nanosatellites or even smaller satellites makes them predestined for distributed systems such as formations, constellations or large swarms. However, when it comes to orbit insertion of multiple satellites, these ride share payloads have constrains in the deployment parameters such as sequence, direction, velocity and time interval. Especially for formation flight missions without propulsion, where the satellites should minimize their relative distance drift either passively or by atmospheric drag control, the initial ejection parameters must find a proper trade-off between collision probability and relative drift. Hence, this article covers short-term (first orbit) collision analysis, long-term (30 days) drift analysis and atmospheric drag control strategy for long-term distance control of multiple satellites. The collision analysis considers various orbit deployment parameters such as insertion direction and tolerance, orbital elements of insertion and time span. To cover the parameter space, a Monte Carlo simulation was conducted to identify the impact of these parameters. It showed that for collision probability the major factor is the time span between two ejections and the precision of the deployment vector. For long-term drift analysis, orbit perturbation such as atmosphere and J 2 terms are considered. The result showed that for drift minimizing, minimizing the along-track variation is more substantial than reducing the time span between ejections. Additionally, a drag control strategy to reduce the relative drift of the satellites is described. The results have been applied on the S-NET mission, which consists of four nanosatellites with the task to keep their relative distance within 400 km to perform intersatellite communication experiments. The flight results for orbital drift show equal or better performance (0.1–0.7 km/day) compared to the worst-case simulation scenario, implying that orbit perturbation was chosen correctly and all orbit injection tolerances were within specified range. The drag control maneuver showed good matching to the flight results as well with a deviation for the maneuver time of approximately 10%.TU Berlin, Open-Access-Mittel – 202