This paper applies model predictive control (MPC) to multi-input spacecraft attitude maneuver problems using reaction control systems (RCS) and reaction wheels (RW). For this purpose, we consider linear quadratic cost functions under the input constraints of nonlinear on-off control inputs for RCS and linear continuous inputs with saturation for RW. These are optimized as mixed integer quadratic programming (MIQP) problems. We further analyze the closed-loop stability in the input-to-state stability framework and derive a stability condition described by a linear matrix inequality (LMI). Some numerical studies are performed and the effectiveness of the proposed model predictive control is shown.
A single-stage launch vehicle with hybrid rocket engine has been conceptually designed by using design informatics, which has three points of view as problem definition, optimization, and data mining. The primary objective of the design in the present study is that the sufficient down range and duration time in the lower thermosphere are achieved for the aurora scientific observation whereas the initial gross weight is held down. The multidisciplinary design optimization and data mining were performed by using evolutionary hybrid computation under the conditions that polypropylene as solid fuel and liquid oxygen as liquid oxidizer were adopted and that single-time ignition is implemented in sequence. Consequently, the design information regarding tradeoffs and the behavior of the design variables was obtained.
The purpose of the present study is to develop a shock tube facility for nonequilibrium radiation studies in Mars entry flight conditions. For the purpose, characteristic investigations and radiation measurements are conducted using the newly developed shock tube facility. In the characteristic investigations, compression process is analyzed by compression tests and numerical analysis to decide the optimum operating condition. Shock velocity at the test section is measured and compared with actual flight data to examine the performance of the facility. In radiation measurements, shock front radiation is measured using the newly developed multipoint spectroscopic measurement system. As a result, the optimum operating condition to achieve soft landing operation is obtained. From the shock velocity measurements, it is found that the shock tube can simulate typical Mars entry flight conditions. The multipoint spectroscopic measurement system enables us to observe a spatial profile of emission spectrum with high accuracy. In conclusion, the newly developed shock tube facility can be used for nonequilibrium radiation studies in Mars entry flight conditions.
This paper proposes a relative position and attitude control method by using only magnetic force with multi-dipole for formation-flying spacecrafts. The control method can be widely applied to re-configurable space structures that architect large structure or reconstruct themselves by assembling basic structural units. One remarkable benefit of the method is that it does not require reaction wheels for relative attitude controls and then doesn't require any fuel for unloading. This paper focuses on current control of dipoles which produce strong nonlinear magnetic forces and suggests a way of linearization by using a corresponding linear reference system. A feasibility of this method and controllability of the strong nonlinear system is discussed, and then the series of position and attitude control simulation are shown, and the future works are suggested in the paper.
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