Seiya Ueno

Optimal feedback guidance for nonlinear missile model with impact time and angle constraints

This study addresses the optimal guidance for nonlinear missile model which enables missile to attack the target at the designated time and angle while integral square control efforts are minimized. This guidance is an optimal control problem and can be reduced to a two point boundary value problem (TPBVP). The optimal input is given by a function of state variables and parameters determined by solving the TPBVP. This TPBVP can be easily solved by using one of shooting methods. In the case where there is no impact angle constraint, optimal input can be obtained as in the case where both impact time and angle are designated. The validity of the proposed feedback guidance is verified by simulations.

Collision avoidance control law of a helicopter using information amount feedback

Utilization of helicopter in urban area is increasing because of its special flight performance. Collision avoidance guidance will play an important role in the future guidance of helicopters. All information of other aircraft is not always available for collision avoidance due to climate conditions or communication problems. Helicopter has to avoid other helicopter under such uncertain information conditions. This paper proposes that a controller uses the information amount as same as physical values. The helicopter changes the flight course to increase the information amount using dynamics of information. Collision avoidance law is adopted when approaching helicopters is recognized. Avoidance is to increase the minimum distance between two helicopters. Numerical simulations show that the helicopter using the information amount avoids the approaching one with safe distance.

Optimal risk management of human alveolar echinococcosis with vermifuge

In this study, we develop a bioeconomic model of human alveolar echinococcosis (HAE) and formulate the optimal strategies for managing the infection risks in humans by applying optimal control theory. The model has the following novel features: (i) the complex transmission cycle of HAE has been tractably incorporated into the framework of optimal control problems and (ii) the volume of vermifuge spreading to manage the risk is considered a control variable. With this model, we first obtain the stability conditions for the transmission dynamics under the condition of constant control. Second, we explicitly introduce a control variable of vermifuge spreading into the analysis by considering the associated control costs. In this optimal control problem, we have successfully derived a set of conditions for a bang-bang control and singular control, which are mainly characterized by the prevalence of infection in voles and foxes and the remaining time of control. The analytical results are demonstrated by numerical analysis and we discuss the effects of the parameter values on the optimal strategy and the transmission cycle. We find that when the prevalence of infection in foxes is low and the prevalence of infection in voles is sufficiently high, the optimal strategy is to expend no effort in vermifuge spreading.

Optimal reconfiguration of UAVs in formation flight

Reconfiguration of unmanned-aerial-vehicle (UAV) formation is one of most important step in field operation of UAV systems. Guidance law for reconfiguration of UAV is needed to satisfy requirements of optimality and constraints of short computational time. This paper describes rules of Dijkstra algorithm based on the optimal trajectories. Calculation results show that the proposed algorithm provides almost mean value of optimal trajectory. The algorithm is useful to generate reference trajectory for minimum time reconfiguration of UAV formation.

Dynamic Behavior of a Semi-Submersible Platform Coupled With Drilling Riser During Re-Entry Operation in Ultra-Deep Water

The present study deals with the dynamics of a semi-submersible platform coupled with a free-hanging vertical rigid riser during the re-entry operation in ultra-deep water. The reentry operation occurs after the drilling phases are accomplished which only use the bare drillstring. The re-entry operation entails positioning the subsurface Blow-Out-Preventer (BOP) above the wellhead and installing it to the wellhead. During this operation, the BOP is suspended by the drilling riser. The placement and installation is time consuming and requires a great amount of accuracy. One challenge is the effects of platform motions on the installation procedure. The present work was carried out with the aim to understand the influence of platform motions during the re-entry operation in ultra-deep waters. Another benefit of this study is the knowledge of the effect of platform motions on the drilling riser and BOP which leads to the possibility of drilling more than one well without the need to raise the BOP to the surface. This could greatly reduce the amount of time needed to drill subsurface wells which in turn, reduces overall operational costs. A numerical simulation in time domain has been carried out using a non-linear model for the platform dynamics. The dynamics of a free hanging drilling riser and a dynamic positioning system (DPS) of the semi-submersible platform are included in the numerical model. Simulation results in time domain of the platform displacements with DPS and riser displacement are shown. A discussion of riser displacement and DPS control is also included.Copyright

Near-Minimum Fuel Guidance Law of a Lunar Landing Module

Abstract This paper proposes a new guidance law for a lunar landing module. The guidance law is derived from the minimum fuel path solved by the optimal control theory. The attitude angle of a landing module is given to minimize the fuel consumption without iterative calculation. The information of thruster, thrust and specific impulse, is not necessary and only the data from an inertial measurement unit is used. The numerical results show that the guidance law has a high robustness of not only tenninal constraints but also optimality of fuel consumption.

Capturing simulation of space debris with super multi-link space manipulator

Space debris became one of the difficulties for mankind to utilize the space environment. Among the variable efforts to the debris problem, the development of technology for the active debris removal (ADR) is especially imperative. This paper is on the motion simulation of debris capture manipulator for ADR with large number of links. Light weight actuator using hydrogen storage alloy is developed for use in outer space as an actuator for the manipulator. The controllable time with the extended resolved motion rate control was examined past study. In this paper, to research the movement of the debris in the end-effector, the simple random collision model was established. Based on the results from this model, the aspects for the control of the end-effector to lower the relative velocity of debris in the controllable time is shown.

A Study on the receding horizon guidance with the sequence optimization for the terminal area

The airspace near the airport, namely the terminal area, has serious congestion. To resolve the congestion, there are demands for the trajectory optimization and the sequence optimization of the arrival aircraft. In this paper, the algorithm to optimize the trajectory and the sequence simultaneously is shown. The receding horizon guidance (RHG) is employed for the trajectory optimization, and the trajectory is defined in the space-time coordinate system (STCS) to introduce the sequence optimization to the trajectory optimization. The simulation is performed to demonstrate the optimization process and the ability of the RHG. The simulation result shows that the RHG with the sequence optimization is able to optimize the trajectory and the sequence simultaneously.

Collision Avoidance Law Using Information Amount

The collision avoidance control has been one of the key technology for future transportation. Recently, many unmanned systems are developed in shapes of robots, cars, ships, aircraft, etc. In these environments, proper navigation and control systems including collision avoidance is needed. This paper is on collision avoidance control law for air vehicles under uncertain information. The control law uses information amount as one of the physical parameter for control system. In the field of guidance, navigation, and control, collision avoidance of automated transportation system has been one of main interest of researchers. Many researches started from collision avoidance of ships (Ciletti et al., 1997) where collision avoidance has been one of the problems due to the increasing demand for the naval transportations. Wide varieties of studies on collision avoidance are treated in fields of robots (Fukuda & Kubota, 1999), cars (Hiaoka et al., 2009a, 2009b) and satellites. Some of these researches treat avoidance problems with the formation control which requires the cooperative information control (Slater et al., 2006; Stipanovic et al., 2007). In the field of aeronautics, the Traffic alert and Collision Avoidance System (TCAS) has been one of the references for the collision avoidance. TCAS exchanges the information of aircrafts and advises the aircraft to avoid in vertical direction. For the conflicts in collision avoidance control, Frazzoli et al. (2001) have shown feasible strategy to treat the conflict problem. Gates (2009) has proposed rule-based collision avoidance control strategies for real-time online collision avoidance. Miele et al. (2010) has proposed collision avoidance control for case of abort landing with low computational load which can be calculated by on-board computer. Conventional avoidance problems assume that all information about avoidance (intruders and environments) is certain. Therefore, control law is designed based on certain information. However in real cases, all information may not be correct and most of it is uncertain. These uncertainty of information differes by the relative position of the evader and intruder or the absolute position of intruder. There has been no research on control law to deal with uncertain information. This paper proposes control law that treats uncertain information. New parameters quantifying information amount are defined for this purpose. The proposed control law provides new performance by enabling the aircraft to obtain information and to check the certainty of the information. Two different cases of numerical simulations are used to investigate the usage of the information amount. The first case defines the problem as the uncertainty of the information changes by the relative position of the evader and the target. The problem treats the case

Robust polynomial guidance law for power descending phase of lunar lander

This paper is on polynomial guidance law for future lunar lander in power descending phase. To achieve pin-point landing, the guidance trajectory needs to be accurate. Boundary conditions are required to solve the polynomial guidance law, but the guidance law is designed in bases where the boundary conditions are nominal. This paper proposes the method to obtain boundary conditions from approximation when initial error occurs and give optimal trajectory even with the initial error. This paper shows the series of different initial errors and discusses the effect of the approximate error to the trajectory and fuel consumption. The results give some ideas for future navigation technology for lunar landing, which has error at the start of their power descending phase.