We propose a new space system enabling orbital reconfiguration and recycling. We designed and fabricated a prototype of Cellular Satellite (CellSat) which is reconfigurable by autonomous space robots. The robotic precise assembly technology is developed. We demonstrated the CellSat feasibility in assembly experiment.
This paper describes the development of a fixed-wing small-size UAV and the design of its flight controllers. The developed UAV’s wing span is 0.6m, and gross weight is 0.27kg. In order to ensure robust performances of the longitudinal and lateral-directional motions of the UAV, flight controllers are designed for these motions with μ-synthesis. Numerical simulations show that the designed controllers attain good robust stabilities and performances, and have good tracking performance for command. After an order-reduction and discretization, the designed flight controllers were implemented in the UAV. A flight test was performed, and the ability of the UAV to fly autonomously, passing over waypoints, was demonstrated.
The attitude motion estimation of objects in orbit, especially uncontrolled satellites owing to failures, is an elemental technology in space environmental preservation missions, such as debris removal and on-orbit servicing. This paper proposes a marker-based attitude estimation approach that enables the accurate estimation even when there exists uncertainty in observation and a lack of prior information such as inertial parameters. For estimating states in nonlinear systems such as attitude motion, the Unscented Kalman Filter is used because of high-accurate performance. Simulation results indicate that this method is able to achieve simultaneous estimation of states and parameters successfully in nonlinear systems, and is robust against misreading by an observer.
This study concerns a shape optimum design to minimize wrinkle intensity of a membrane under an area constraint. The membrane shape is modeled by non-uniform rational B-spline (NURBS) curves and the curve-passing points are adopted as design variables. The membrane wrinkle intensity is evaluated through the wrinkle-mode deformation energy proposed by one of the authors. Where, the total strain energy in a wrinkled membrane evaluated by the tension field theory is effectively decomposed into elastic strain energy and apparent wrinkle-mode deformation energy by applying a projection matrix. The latter only depends on the deformation caused by wrinkling, and is utilized as an objective function. As a numerical example, the optimization is applied to a typical square membrane design problem to demonstrate the effect of the shape optimization on the wrinkle reduction. The wrinkle-mode deformation energy decreases to 10% of the original design for only 5% reduction of the membrane area. Additionally, a high convergence property is achieved regardless of direct implementation of the nonlinear finite element analysis during the optimization.
A flyable FADEC system engineering model incorporating Integrated Flight and Propulsion Control (IFPC) concept is developed for a highly maneuverable aircraft and a fighter-class engine. An overview of the FADEC system and functional assignments for its components such as the Engine Control Unit (ECU) and the Integrated Control Unit (ICU) are described. Overall system reliability analysis, convex analysis and multivariable controller design for the engine, fault detection/redundancy management, and response characteristics of a fuel system are addressed. The engine control performance of the FADEC is demonstrated by hardware-in-the-loop simulation for fast acceleration and thrust transient characteristics.
The aerodynamic design procedure of a large-scale aircraft noise suppression facility has been developed. Flow quality required for the engine inlet flow has been determined through basic experiment. Aerodynamic design of the facility has been performed by using wind tunnel experiment and CFD. Important relationship between the length of the facility and the inlet flow quality has been found. The operational envelope of the designed facility has been estimated. Then, the aerodynamic characteristics of an actual large-scale aircraft noise suppression facility, constructed based on the new design procedure, have been measured. Obtained flow field showed good agreement with CFD results, and the effectiveness of the design procedure based on CFD and wind tunnel experiment has been confirmed. The engine operations were satisfactory under various wind conditions. Furthermore, the data under commercial operations thereafter have been collected and analyzed. As the result, the aerodynamic design procedure has been validated.