Kakuji Ogawara

Delayed Feedback Control for Flow around Wing using Plasma Synthetic Jet Actuator

Flow on an airfoil was investigated with plasma synthetic jet actuator. Plasma synthetic jet actuator is a flow control device which is composed of electrodes with A.C. signal, using electrohydrodynamic effect and induces a flow around the electrodes. From the characteristics of electrical device, plasma synthetic jet actuator has some important advantages; for example, miniaturization, maintenance free, and easy to control. From these characteristics, it is effective to apply flow control around an airfoil with plasma synthetic jet actuator. In this study, the behavior of the plasma synthetic jet actuator around an airfoil is observed by experiment. A NACA0012 airfoil with plasma synthetic jet actuator is set in the wind tunnel. The wake velocity behind air foil is measured with and without the actuator. Experimental result with the Delayed Feedback Control for the flow control system is shown in this paper. The results show good improvement for the plasma synthetic jet actuator to reduce drag in the high angle of attacks.

Investigation of Low-Cloud Characteristics Using Mesoscale Numerical Model Data for Improvement of Fog-Detection Performance by Satellite Remote Sensing

AbstractThe comprehensive relationship between meteorological conditions and whether low water cloud touches the surface, particularly at sea, is examined with the goal of improving low-cloud detection by satellite. Gridpoint-value data provided by an operational mesoscale model with integration of Multifunction Transport Satellite-2 data can provide sufficient data for statistical analyses to find general parameters that can discern whether low clouds touch the surface, compensating for uncertainty due to the scarcity of observation sites at sea and the infrequent incidence of fog. The analyses reveal that surface-touching low clouds tend to have lower cloud-top heights than those not touching the surface, although the frequency distribution of cloud-top height differs by season. The bottom of the Γ > Γm layer (where Γ and Γm are the vertical gradient and the moist-adiabatic lapse rate of the potential temperature, respectively) with surface-touching low-cloud layers tends to be very low or almost attach...

Delayed feedback altitude control for micro UAV without sensing pitch rate

In this paper we demonstrate characteristics of DFC in the situation that pitch rate and A.O.A. are unknown. This paper demonstrates characteristics of delayed feedback control in the case of pitch rate sensors absence.

Formation Control of Underactuated Satellite using Holonomy

Formation of satellites is difficult to control because of their unique system called the non-holonomic systems. One of the ways to control the non-holonomic system is to use the holonomy that appears when the periodic input is given to the non-holonomic systems. In this study, the formation of underactuated satellite is controlled using the holonomy. The satellite used in this study is simplified 2-dimensional model with only thrusters to change positions and to change its attitude angle. Various pattern of periodic input gives the different holonomy to the system. By combining the patterns of the holonomy, the satellite is able to move around to designated places and attitude. These combinations of the holonomy can be applied to the system to correct the attitude or position errors. This study also enables the satellite to move the satellite in rest-to-rest motion in the formation flight of multiple satellites

Study on Characteristics of Thermal Flow-Induced Vibration in Unlooped Heat Pipe

In this paper, presented is an experimental study of thermal flow-induced vibration in a both-ends-closed type self-induced oscillating heat pipe. This was made of winding glass tube to visualize the phenomenon. It was heated at the bottom to control temperature by heater, while was cooled at the top to keep temperature constant. Liquid column oscillation was excited with boiling and expansion of vapor plug. When liquid volume fraction was large, the magnitude of pressure oscillation was large and low frequency was relatively dominant. Furthermore, normalized temperature θt was proposed to investigate the threshold of excited conditions, taking account of initial condition, e.g. initial pressure. With respect to liquid volume fraction, θt was alternately varied up and down. This phenomenon was evaluated to be dependent on the liquid volume fraction.Copyright

Sliding Mode Heading Control for Autonomous Small UAV without Gyro Information

We have proposed a control algorism using holonomy for small UAVs. Because this control algorism is feedfoerward control, it has possibility that the heading angle overshoots the target yaw angle. This paper presents the sliding mode control for small UAV to reduce the overshoot. Sliding mode has feature of less overshoot. Holonomy control is used in the case that the target yaw angle is large. When the target angle becomes small, sliding mode control is used. In this way, poorly-convergence is inhibited by using sliding mode. Generally, plane is controlled using gyro rate. In this algorism, it is controlled using roll angle without gyro information. The altitude is controlled using delayed feedback control (DFC) at steady flight. DFC has characteristic to converge on unknown equilibrium position. We show that the heading control using sliding mode control and landing control. At landing operation, trajectory tracking is introduced as target angle determination. This algorism can guide UAV to runway. International standard atmosphere, steady wind and continuous gust wind are considered in the numerical simulation. In this paper, we demonstrate efficacy of sliding mode control by simulation.

Micro UAV Holonomy Control System Robust for Gust Wind

We consider autonomous control for micro UAV. The direction of movement is controlled using holonomy. The model airplane is difficult to be controlled due to nonholonomic system. It is effective to use the holonomy that is the response for the periodic input signal. Holonomy is displacement of state quantity by cycle input. At steady flight, short cycle block impulse is input to rudder. Yaw angle and roll angle change. However roll angle returns to 0 [deg] by attitude stabilizing apparatus and UAV’s stability, and yaw angle converges to a certain value. In this study, position, bank angle, and direction angle of the model airplane are controlled by the rudder only. Also, the altitude is controlled using delayed feedback control (DFC) at steady flight. The role of DFC is to make the state converge to unknown equilibrium position. During landing control, the thrust is fixed to 30% of the max thrust. We show that the direction control using holonony and landing control without gust wind are succeeded. International standard atmosphere, steady wind and continuous gust are considered in the numerical simulation.

CFD Analysis of Delayed Feedback Flow Control Around Wings Using PSJA

CFD analysis of the flow around the wing using closed-loop feedback control was investigated with plasma synthetic jet actuator. Plasma synthetic jet actuator is a flow control device which is composed of the electrodes with A.C. signal, using electro hydrodynamic (EHD) effect and induces a flow around the electrodes. From the characteristics of electrical device, plasma synthetic jet actuator has some important advantages; for example, miniaturization, maintenance free, and easy to control. From these characteristics, it is effective to apply flow control around wings. With this actuator, the flow around the wing controlled by the delayed feedback control (DFC) has shown high effect to reduce the drag and separation in the wind tunnel tests. In this study, the CFD analysis is held to see the effect of the DFC to the flow around the wing including precise flow stream, which is difficult to measure in actual wind tunnel testing. The conditions of CFD is set as equal to that of the low wind tunnel testing using a NACA 0012 aerofoil. The actuator actuates the flow according to the body force calculated computationally by the induced voltage between the isolated electrodes. The CFD analysis shows that the DFC reduces the drag and forces the position of the flow separation to down stream. These results show good agreement with that of the wind tunnel tests.

Effect of DFC parameter on flow control Around wings with PSJA

Flow around wings was investigated with plasma synthetic jet actuator. Plasma synthetic jet actuator is a flow control device which is composed of the electrodes with A.C. signal, using electro hydrodynamic (EHD) effect and induces a flow around the electrodes. From the characteristics of electrical device, plasma synthetic jet actuator has some important advantages; for example, miniaturization, maintenance free, and easy to control. From these characteristics, it is effective to apply flow control around wings. In this study, the experiment is held to see effect of the delayed feedback control (DFC) parameter of DFC on plasma synthetic jet actuator placed on the surface of the wing. A NACA0012 wing with plasma synthetic jet actuator is set in the wind tunnel. The parameter τ as the time delay parameter for delayed feedback control is varied to see the effect and change to the flow condition. From the experimental result, the flow velocity converged to certain stabilized periodic motion especially where the τ has shown the most actuating effect. As the characteristic of DFC, the controlled object converges to a limit cycle with the period of τ . In this paper, the flow has converged to the limit cycle with the period respectably linear to the time delay τ but different from its value of the time delay itself. Also, the change of the flow velocity effects the periodic cycle of the flow.

Using State-Space Database to Control Vehicles

Recent years, there are researches to operate vehicles by the voice instruction. It is important for these researches to recognize a peripheral environment. There are internal sensor and external sensor used to recognize a peripheral environment. Internal sensor is often used together with external sensor because the error with driving system is caused. Imaging sensor can especially measure the plane compared with other external sensors, the research combined with internal sensor is abundant. The delay is caused because it takes the processing time when imaging sensor is used. In this research, imaging sensor is installed on the vehicle, so the system is visual feedback control. The goal of this research is that using state-space database can control the vehicle. The vehicle can run on the straight corridor without the patterns like joint of the building. The vehicle cannot distinguish the patterns like joint of building on straight corridor and wall. Sobel operator that picks the edge causes this problem, because a similar feature appears to the objects. As result, the vehicle can be controlled regardless of the patterns like joint of the building on straight corridor. The state quantity of state-space database that solves this problem is found