Yuzo Shimada

Nonparametric Adaptive Attitude Control System Accommodating Nonlinearity and Uncertainty

The purpose of this study is to develop a nonparametric adaptive flight control system that can cope with uncertainty and nonlinearity for the automatic landing system of a spaceplane. The proposed adaptive flight control system is based on a dynamic inversion approach combined with time-scale separation. However, such an approach involves an interaction problem between the inner feedback loop and the outer feedback loop. Also, the nonlinear portions in the dynamics are not sufficiently cancelled by nonlinear state feedback without accurate prior knowledge of the parameters of the controlled system. To solve these problems, a new nonlinear state feedback control combined with observers is presented to estimate unknown signals due to nonlinearity and uncertainty. These techniques allow the control system to neatly avoid the estimation of unknown parameters, unlike in conventional adaptive control. Numerical simulations of the automatic landing of a spaceplane are performed to verify the effectiveness of the proposed method.

Adaptive attitude control with reduced number of estimated parameters for automatic landing system

The formulation of an adaptive attitude control law with reduced number of estimated parameters is introduced for the automatic landing system of a spaceplane. Adaptive attitude control systems have been designed to obtain the control law by estimating the parameters that describe the dynamics of the vehicle and actuator. Despite the fact that the vehicle was well controlled so as to track a reference trajectory, the estimated parameters did not agree with actual values because the number of estimated parameters was redundant for the controller. Therefore, the controller using the estimated parameters does not always show good performance during vehicle landing. In this study, we attempt to design an adaptive attitude controller by reducing number of estimated parameters for the automatic landing flight experiment (ALFLEX) vehicle. Assuming that the dynamics of the actuator is known, such model reduction is realized by decreasing the number of estimated parameters. The validity of the proposed method is verified and the effect of the dispersion of the actuators dynamics on the control system is also investigated by numerical simulation.

Automatic landing system for spaceplane based on model predictive control using state mapping

We describe the application of model predictive control (MPC) using state mapping to the automatic landing system of a spaceplane. The controller has to be designed to enable the vehicle to follow reference signals with respect to trajectory and velocity, which are expressed as functions of the downrange. To track the reference signals, a control input is generally designed so that one or more ideal transient responses are realized. We also have developed a flight control system based on this concept. However, it was not satisfactory for use as the controller of an actual vehicle due to the lack of consideration of the input and state constraints. A controller that considers these constraints can be designed by applying MPC. On the other hand, it is difficult to predefine the transient responses necessary to track the reference signals, which vary with the current downrange. In this paper, a new approach using state mapping and feedback linearization is proposed to improve the control performance of tracking the reference signals. State mapping is derived to describe a system in which the reference signals can be handled as a constant set point, and the described system is linearized using state feedback. The proposed system is applied to the Japanese automatic landing flight experiment (ALFLEX) vehicle. A numerical simulation is performed to verify the validity of the proposed method based on MPC.

Development of Flight Simulator for Human-Powered Aircraft - The Road towards a World Record

This is a preliminary report about our plan for a special-purpose flight simulator. The human-powered aircraft developed in Nihon University has achieved the Japanese flight distance record of 49.2 km in 2005. However, this Japanese record is still half the distance of the world record of 115.1 km that Massachusetts Institute of Technology achieved in 1988. Thus, the present goal for the development group of our university students is to break this world record. For this purpose, a research group for a human-powered flight support system was established to develop a special-purpose flight simulator for human-powered flight. The purpose of designing such a simulator is to provide the student pilot with a scientific and practical training facility and to feed the flight data and design factors back into an optimal design of the human-powered aircraft. That is, the simulator would be used to search for an optimal flight path planning, optimal power time-distribution program for the pilot, and the optimal configuration of the aircraft. To find the optimal flight path and optimal power distribution, an appropriate mathematical model for the pilot as a man-powered engine must also be analyzed and determined as well as a conventional pilot model in handling the control stick. The developed simulator would also be used to compare an ordinary student pilot with an athlete pilot. More details would be presented at the conference