Scientific Ballooning by Toyoo Abe Takeshi Imamura Naoki Izutsu & Nobuyuki Yajima

Author:Toyoo Abe, Takeshi Imamura, Naoki Izutsu & Nobuyuki Yajima
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

(2)Generating a torque and rotating the gondola using a momentum exchange device within the gondola (this is similar to satellites).

The apparatus for method (1) is simple, but because it generates torque by twisting the long suspension line, it is difficult to obtain a rapid control response. The same reaction wheel as that employed in satellites is often used as the drive assembly for method (2). As described earlier, the angular disturbance imparted to the gondola is large compared with that imparted to a satellite. The size of the flywheel or the power of the drive motor is increased as the control accuracy required increases. From this point of view, a control moment gyro (CMG) is useful. A CMG is a drive assembly that generates a high torque through the gyro effect. Specifically, it is composed of a gyro that is mounted on a gimbal. The gyro generates a large angular momentum by rotating a large wheel at high rotation rate. The gimbal rotation axes are driven by a motor, and the direction of the large angular momentum vector changes quickly.

To achieve two-axis tracking of observation objects, the following methods have been adopted for rotating the entire body of the observation equipment: (1) The elevation angle of the observation equipment is controlled on the gondola that is azimuthally controlled by the above-mentioned methods, or (2) mounting a two-axis gimbal at the center of gravity of the gondola, in which the observation system is installed. The gondola is suspended from the balloon via the gimbal. The gondola can then freely rotate around the two axes, and a biaxial attitude control system that uses a momentum exchange device drives the gondola. Naturally, the latter method is applicable to large systems.

Figure 3.17 shows an astronomical infrared telescope. It is an example of a system in which the azimuthal angle of the gondola is controlled by a CMG [3], whereas the US Stratoscope II shown in Fig. 1.3 is an example of a system in which biaxial control is achieved using a two-axis gimbal.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.