This paper deals with management problems of angular momentum distribution during the capture of a tumbling target by a free-floating space robot with constraints on the torque and angular momentum that the reaction wheels of the robot are able to output to suppress rotational motion of the robot base. A time-optimal control of the manipulator arm during the approaching phase of the capturing mission and an estimation method to minimize the base rotation after the manipulator captures the tumbling target are proposed in order to realize desirable angular momentum distribution of the entire system. The proposed strategy is verified by numerical simulation with a free-floating space robot model equipped with a 7-d.o.f. manipulator and a system of three reaction wheels.
We refine the earlier presentation method of the sunspot cycle variations of the neutral line on the source surface by introducing the view longitude. It is shown that the neutral line seen from the view longitude and the equivalent dipole (determined by Hoeksema, 1984) showed a trend of rotation throughout the sunspot cycle. However, the surface bounded by the neutral line is generally far from a circle. In fact, our combined presentation of both the equivalent dipole and the neutral line indicates graphically that such a simple description of the rotating (equivalent) dipole may be misleading. The concept of an inclined dipole with respect to the rotation axis may also be misleading.
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