The only really efficient way of evading the above dilemma is, to build in AIT support functionality into the autonomous unit. This paper discusses the AIT support functions of a highly autonomous instrument, the Advanced Stellar Compass (ASC), developed by the department of Automation at DTU. It is a fully autonomous star tracker intended as a high accuracy attitude reference onboard spacecrafts. The ASC consists of a miniaturized but powerful microcomputer driving from one to four CCD-based camera heads. The use of multiple camera heads may relieve several constraints on the AOCS, such as increased maximum attitude rate of change, and a "don't-care" inertial pointing, because multiple cameras may be arranged such that simultaneous blinding by the Sun and Earth are highly unlikely.On the other hand, to stimulate an old-fashioned star tracker, it only took a single moving light source, whereas not even a high quality star pattern generator may be able to pass the outlier rejection filtering of the ASC thus efficiently precluding artificial stimuli during AIT tests. In order to circumvent this impasse, the ASC has a series of build-in features enabling simple, yet comprehensive, closed loop testing. These features encompass a suite of support functions including an in-line attitude simulator, image up and download features, and failure and surveillance monitors. The paper describes the operation of these modes and how they have been used during the AIT of several spacecrafts.
|Title of host publication||ESA 4th Symposion on Spacecraft Guidance Navigation and Control|
|Publication status||Published - 1999|
|Event||4th ESA International Conference on Spacecraft Guidance, Navigation and Control - Noordwijk, Netherlands|
Duration: 18 Oct 1999 → 21 Oct 1999
|Conference||4th ESA International Conference on Spacecraft Guidance, Navigation and Control|
|Period||18/10/1999 → 21/10/1999|