Launch Vehicle Attitude Research Articles

Operational Methodology for Large-Scale Deployment of Nanosatellites into Low Earth Orbit

The on-orbit deployment of large numbers of nanosatellites is cast in terms of the relative motion equations, augmented with differential drag. Using this framework, a methodology is developed for minimizing the likelihood of recontact or interference among the deployed nanosatellites. This approach is applied to a representative test case derived from the Operationally Responsive Space Office’s Launch Enabler Mission, which delivered 28 small payloads to orbit in 2013. By strategically varying the deployment order, timing, and launch vehicle attitude, the net separation among each of the nanosatellites is demonstrated for the first three weeks with minimal close approaches. These results are validated using high-fidelity simulations.

On the design of adaptive autopilots for a launch vehicle

Three efficient and practical approaches for the design of an adaptive autopilot for a launch vehicle (LV) attitude control system during atmospheric flight are presented. The proposed adaptive control schemes are developed on the basis of different combinations of gain scheduling, decoupling, and the model reference adaptive technique. A new adaptation mechanism based on hyperstability theory is developed. Every scheme contains some degree of adaptation, corresponding to its complexity and cost of realization. A six-degree-of-freedom non-linear simulation was used to compare the adaptation characteristics of the proposed schemes in the presence of different disturbances during atmospheric flight of the vehicle.

An Idea of Applying μ-Synthesis to Launcher Attitude and Vibration Control Design

This paper presents a methodology for applying μ-synthesis to a real high-order system: launch vehicle attitude and vibration control. The design involves robust characteristics against uncertainties of the system parameters as well as precise tracking performance under limited rigidity. As the plant dynamics has an extremely high order and unstable character, the standard μ-synthesis cannot be directly applied. Thus, the standard procedure is modified in a specialway in order tomake the approach more efficient. The methodology provided in the study will contribute to a better understanding of how to apply the robust control theory to complicated real problems.

Flexible Launch Vehicle Attitude Control Design Using Coevolutionary Algorithm

Launch vehicles in general are slender and flexible. The flexibility of the launch vehicle easily induces instability to the total launch vehicle system. There is also a high rate of change in mass and aerodynamic conditions. These conditions require an attitude controller which is robust to various system parameter changes and disturbances. In this paper, the launch vehicle's attitude controller is optimized by the coevolutionary algorithm. The attitude controller structure must be determined and the performance index is set according to the user needs. The coevolutionary algorithm can find the gains of the controller which gives the best performance. The controller is robust over a wide range of the system uncertainties. Also these uncertainties are controlled by the adaptive control using neural networks.