This paper discusses on the actuator assignment of a variable geometry truss(VGT) as a space manipulator, which is required to capture space debris. The motion of VGT is simulated to synchronize trajectory of malfunctioned satellite, which is usually spinning or tumbling. The end of VGT is constrained to move periodically. The control law is also required to reduce energy consumption because of limited resources in space. The control law is derived from the locally optimal condition of minimum energy problem with periodic constraints. Two types of actuator assignments are compared through numerical simulation.

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This paper describes a structure design method of large deployable structures using similarity index value. Similarity index value is defined as the difference of the nominal deployment force between a module structure and the whole structure (which consists of some module structures). The differences are generated by the size of a module structure, the connection errors and the synchronization errors of the whole structure. By comparing the experimental and analysis results, we quantitatively evaluate the changes of the nominal deployment force in each factor. We introduce an index that indicates the number of modules in the structure design of large deployable structures. We design the antenna reflectors which are 10 or 20m in diameter using similarity index value.

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This paper studies a pointing control problem of mobile antenna mounted on a vehicles. Especially, we consider the problem to control the antenna precisely pointing a target under the influence of continuous disturbances acting to the vehicle. To the problem, we propose an optimal controller design method in a framework of the H_∞ gain-scheduled controller synthesis. By the synthesis, the optimal controller is obtained by using parameter varying filter in order to attenuate the influence of the various frequency disturbance. Finally, we apply the design method to the test prototype model.

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In this report, we describe the static structural behavior of the iso-truss structure. The iso-truss structure is modeled as a three-dimensional frame structure and is formulated by the finite element method. By the numerical calculation, the static behavior of the structure subjected to axial loading, concentrated loading and twisting loading is made clear. Analysis of cylindrical shell is carried out for the comparison. Especially, intruducing the equavalent bending rigidity, the numerial calculation results are analyzed. We show that the increase of number of bays has an effect of increasing of the equivarent bending rigidity.

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An analytical method of a three-dimensional cascade with supercavitation in spanwise shear flow between two parallel plane walls is presented. An equation of motion with respect to disturbance pressure is transformed into two problems by separation of variables. One of them is that of spanwise direction and the other is that of sectional plane of a hydrofoil. For the problem of the spanwise direction, an existing analytical solution is adopted. The problem of sectional plane of the hydrofoil is reduced to a simultaneous integral equation with respect to singularity distributions and is solved by using the analytical method previously proposed by the author for the three-dimensional cascade without cavitation. These two kinds of solutions corresponding to individual eigenvalues are combined linerly, and expressions of the cascade and cavity characteristics are obtained. Numerical calculations are carried out to clarify the characteristics.

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A new system for measuring ocean wave height, period and direction within ten centimeter accuracy is developed using a point-positioning commercial-based GPS receiver mounted on a buoy. The essential idea of the proposed system depends on the fact that the most of the spectrum of GPS point-positioning error lies in the frequency domain below 0.01Hz, but the frequency spectrum of ocean waves exists in a seperate band around 0.1Hz. Therefore, a simple high-pass filter can extract movements of a GPS equipped buoy excited by ocean waves without GPS long term period point-positioning error.

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The purpose of this paper is to show that the effective mass is a useful indication also in identifying dominant mode of unconstrained structures. Effective mass concept works well for structures with constraint, but it does not work for unconstrained structures with rigid-body modes. This is the reason all the effective masses for elastic modes are zero. A way to use the effective mass for dominant mode identification of unconstrained structures is to put zeros into elements in rigid-body modes. Although the effective mass takes different values by which element is replaced with zero and by zeroing rate, modes with large effective mass are dominant mode. However, we cannot necessarily judge that modes with small effective mass are not dominant for a zeroing rate. It is found that it is effective to select a zeroing node that modes are asymmetry with respect to the node in identifying dominant modes. A numerical example is given to show that the proposed method is effective for dominant mode identification of unconstrained structures.

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We experimentally investigated the dynamic characteristics of the lateral liquid sloshing in a concentric tank from the viewpoint of attitude stability and control. The experiment was conducted with a circular cylindrical tank with a 33.4-cm diameter outer rigid wall and a 23.4-cm diameter inner wall. Three materials were used for the inner wall, acrylic rigid wall, Kapton film, and polyethylene foam sheet. We found that when the inner wall is flexible, the amplitude of the resonant frequency is small, and it is difficult to find resonant phenomena, and that damping ratio increases with decreasing membrane wall rigidity.

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This article describes an overview of Deployable Radiator (DPR) with the Loop Heat Pipe(LHP) on Engineering Test Satellite type (ETS-VIII), which is Japan's first 3-ton-class geostationary satellite, developed by Japan Aerospace Exploration Agency (JAXA). DPR is one of key technologies concerned with thermal control for a high-powered satellite bus or internal equipments in communication, broadcasting and scientific satellites, since it can give larger heat rejection area for such satellites. DPR is the on-orbit experimental equipment on ETS-VIII for building up the high-heat-transport technologies in Japan. The LHP, which is a two-phase heat transport device using capillary evaporator, carries the heat of 300W from hot experimental heaters to a cold external radiator panel by latent heat of vaporization with a working fluid of Ammonia. In the LHP, the reservoir of working fluid is embedded in the capillary evaporator. On-orbit experiments on DPR are scheduled in FY2006.

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For the study of near-future robotic manipulations on satellites, we developed a 2-dimensional micro gravity experimental system dynamics of robotic manipulator mounted on a satellite. The robotic manipulator which is connected to the DISC (Dynamics and Intelligent control Simulator for satellite Cluster) is floated on the flat floor (glass plate, 3m by 5m) by air-bearings. We use a 3-DOF manipulator which is a RBR (Reconfigurable Brachiating space Robot) unit arm developed for EVA supports. We conducted the fundamental experiment for flexible beam carrying by a 3-DOF manipulator mounted on DISC which is assumed for the missions of on-orbit carrying service using the small satellite, and showed a vibration suppression of the beam applying input shaping theorem to RBR velocity profile.

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Solar sail system is considered to be one of solutions for planetary cruising, and it is researched by numbers of institutes. Our laboratory has been worked on this theme and presented deployment method using tether-formation control, membrane folding method, deployment mechanism, and ground experiment. However, more accurate and careful control is necessary to deploy solar sail membrane ideally. In this paper, we will present our new idea to control solar sail membrane under real-time control with using image processing and deployment mechanism.

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Deployment characteristics of spinning membrane are significant to realize the solar sail missions. This paper describes for the dynamic properties of deployable spinning membranes for solar sail experimentally. In this study, we use the rotationally skew fold membrane models, and consider the effects of radius, folding pitch and membrane thickness on the dynamic properties. The results indicate that the membrane with smaller folding pitch is deployed quickly and larger radius causes the rapid deployment at the first stage of deployment. The wrapping direction which is equal to the spinning direction indicates the quick deployment.

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