This paper addresses the design problem of Gust Alleviation (GA) flight controllers for linearized longitudinal aircraft motions with some uncertainties using prior turbulence information via Model Predictive Control (MPC) scheme. Considering that the plant uncertainties are assumed to be modeled as time-invariant uncertain but bounded delays at the plant control input, we derive a plant set, the number of whose elements are finite, to represent the uncertainties without introducing any approximations. For this set, we derive a new formulation to obtain an optimal control input, which guarantees some robust performance with respect to GA performance against the delays, as a Second-Order Cone Programming (SOCP) problem. As the conditions in SOCP problems have the convexity with respect to the decision variables, the global optimal control input for our addressed problem is obtained using some effective software. Exploiting that our proposed method introduces no approximations when deriving the plant set and SOCP problems can give the global optima, we propose a method to identify whether or not the prior gust information improves GA performance. A numerical example which illustrates our conclusions is included.
The purpose of this paper is to introduce a velocity control system for a leader-following UAV. For the purpose of our work, we designed a whole guidance and control system; the guidance system using the pure pursuit navigation guidance law, the attitude control system using the dynamic inversion with the two-time scale approach, and the velocity control system considering aircraft and engine dynamics. This paper concentrates on the velocity controller including the stability analysis for the uncertainty of the aerodynamic parameters. Velocity controller gain determination technique adapted for the aircraft and/or engine dynamics are discussed in this paper. Simulation results show that the proposed guidance and control system provides a good performance.
The aerodynamic performance of an AGARD-B model, as an example of a winged model, was measured in a low-speed wind tunnel equipped with the JAXA 60cm Magnetic Suspension and Balance System (MSBS). The flow speed was in the range between 25m/s and 35m/s, and the angle of attack and the yaw angle were in the range of [− 8, 4] and [− 3, 3] degrees, respectively. Six components of the aerodynamic force were evaluated by using the control coil currents of the MSBS. In evaluating the drag, the effect of the lift on the drag must be evaluated at MSBS when the lift is much larger than drag. A new evaluation method for drag and lift was proposed and was examined successfully by subjecting the model to the same loads as in the wind tunnel test. The drag coefficient at zero lift and the derivatives of the lift and pitching moment coefficient with respect to the angle of attack were evaluated and compared with other source data sets. The obtained data agreed well with the corresponding values of the other sources. The side force, yawing moment and rolling moment coefficients were also evaluated on the basis of corresponding calibration test results, and reasonable results were obtained, although they could not be compared due to the lack of reliable data sets.
Effects of nozzle geometry, and total temperature on supersonic jet noise radiated from rectangular and axi-symmetric plug nozzles are investigated, experimentally. In JAXA (Japan Aerospace Exploration Agency), a pre-cooled turbojet engine for an HST (Hypersonic transport) is under development. In the present study, three kinds of subscale nozzle models are employed, namely two kinds of rectangular plug nozzles (RPN1 and RPN2) and an axi-symmetric plug nozzle (APN), and the jet noise data are acquired at aft angles of the jets by use of 1/4 inch high frequency microphones. The total pressure is set at 0.3MPa(a), which corresponds to the take-off condition of the vehicle, and the total temperature is varied from 290K to 860K. The jet noise spectra obtained are reduced to normalized spectra by use of a scaling law of heated jets (AUn law). It is shown that the normalized spectra collapse onto two lines according to each nozzle geometry, regardless of the total temperature. For APN, the peak SPL is smaller by about 8 to 14 dB when compared with that for RPN1 and RPN2, which implies that the axi-symmetric plug nozzle could be much quieter than rectangular plug nozzle.
The commercial success of a hypersonic airliner is discussed from a viewpoint of its operational convenience. In the hypersonic regime, a lift-to-drag ratio is generally small due to a large wave drag, which results not only in small cruising range but also in an operational inconvenience. To overcome this drawback, we propose a transportation network with multiple hypersonic airliners. The analysis of the operation diagram demonstrates that the travel time of passengers can be significantly reduced in the absence of the arrival and departure in late evening or early morning thanks to the combination of the high flight velocity and flexible network operation, even if the range of the hypersonic transport is limited to 7,330km. Consequently, the network operation will greatly enhance the potential of the hypersonic aircraft for future high-speed global transportation system.