1 November 1990 Time-domain computer simulation program as first step of a full digital high-precision pointing system for platform in balloon-borne remote sensing
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Abstract
The first and the most important step on the way to the absolute high accuracy pointing in balloon-borne remote sensing is a good azimuth stabilization. For this goal it is absolutely necessary to control the non linear friction of the suspension bearings in order to isolate the instrumentation, as much as possible, from the random rotation of the cruise balloon. The paper describes a program simulation of a servo-system that is theoretically capable of 2.6 arc mm of accuracy with a magnetometer sensor in the feedback path only. This pointing accuracy strongly depends on the signal to noise ratio of the sensor employed, but it is possible to approach the theoretical value by means of a particular mechanical arrangement, powered by a torque motor. This active mechanical arrangement (named Pivot and strategically placed at the interconnecting point balloon-payload) houses the necessary suspension bearings. The leakage torque, transmitted from the balloon to the gondola through the load stress of this interconnecting point, is controlled and attenuated simply by putting the bearings of the Pivot in rotation. The parameters of this Pivot and the features of two DC torque motors are the starting points of our simulation design. The second motor, according to the inertia moment of a reaction wheel, provides the torque necessary for any platform motion around the vertical axis. However some mechanical non-linearities, localized exactly at the Pivot level, impose a time domain design either for any settling time control whenever the gondola experiences a new change in azimuth coordinate or during the tracking action of an astrophysical target. The program simulation in the time domain, that is the first step towards a full digital pointing design, has the same utility, for the servo-system analysis, of the unity step response in the Laplace transform field.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Andrea Boscaleri, Andrea Boscaleri, V. Venturi, V. Venturi, R. Colzi, R. Colzi, "Time-domain computer simulation program as first step of a full digital high-precision pointing system for platform in balloon-borne remote sensing", Proc. SPIE 1341, Infrared Technology XVI, (1 November 1990); doi: 10.1117/12.23076; https://doi.org/10.1117/12.23076
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