Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Patent
1996-09-05
1999-03-02
Nguyen, Tan Q.
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
395898, G06F 706
Patent
active
058783580
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a data processor and, in particular, to an optical data processor.
The data processor according to the invention is suitable for use in a number of applications, for example, a star sensor for a satellite, vehicle control systems including a visual protection sensor for automobiles and other vehicles, and vehicle tracking/steering systems, at least the partial alignment of the antenna of at least two equipments, a telephone handset for a mobile radio system, and many other applications that will be directly evident to persons skilled in the art.
In all optical sensing systems the optical sensor generally produces significantly more data than is actually required for the purposes of evaluating the received data. For example, in a star sensor used on a satellite, the optical sensor is a charge coupled device (CCD) consisting of a two dimensional array of many thousands of individual elements or pixels, for example, an array of 250,000 to 1,000,000 sensor elements or pixels.
When such a sensor is exposed to the night sky it can see only a few stars but in order to evaluate the data relating to the stars it is necessary to access the data associated with all the pixels of the CCD array. Since the number of stars is small but the number of pixels is large the percentage of useful information is very small, i.e. approximately one in ten thousand has useful information.
In most optical sensing systems only a relatively small amount of the received data is likely to be of interest, in that the sensing system will only want to know where something is, not where it is not. In the case of a star sensor, the only information that will be required is the locations of the stars relative to each other.
In practice, the CCD array of a star sensor would produce approximately 40 million bits of data per second of which only 1080 will contain useful data.
In order to allow a star sensor to identify the star field it is viewing, only the brightest stars can be used, and in principle only three stars are required in any one field of view.
Thus, the number of pixels which need to be identified is therefore only 3, but due to the fact that a star image may be centered at the junction of 4 pixels or, due to errors in focusing, may illuminate more than one pixel, the number must be increased. To ensure that the three brightest stars' position can be identified the data processor of the star sensor must return the locations of the top 30 plus pixels. This number allows the brightest star to illuminate one pixel and also spill over into the 8 adjoining pixels such that they become the second brightest object. This is then repeated for the other 2 stars. This gives a minimum of 27 pixels. Additionally the CCD array may have some blemishes, therefore some additional pixels may be required in order to effect identification. With known methods of data processing, it is usual to evaluate all of the data by means of a computer which is adapted to sort through the data in accordance with given criteria to find the relevant bits. This is either slow, or requires the use of a very powerful data processor.
Known arrangements for automatically sorting and storing data words/samples, in rank order, are described in European patent applications, publication numbers 0 441 533 A2 and 0 413 951 A1.
In particular, EP A 0 441 533 describes apparatus for receiving and automatically storing data words, according to magnitude, in a self-sorting register stack, wherein the stored data words are maintained in sequential locations with data words of lesser magnitude preceding data words of greater magnitude, wherein incoming data is simultaneously compared with each of the stored data words, and wherein a new data word is automatically inserted into the correct register on the stack, the contents of that register, and subsequent registers, being moved down one location to accommodate the new data word. Thus, with this apparatus and other known automatic data sorting and storage arrangements, the computation overhead per incoming da
REFERENCES:
patent: 3493939 (1970-02-01), Dunn et al.
patent: 5179712 (1993-01-01), Abbound
patent: 5222243 (1993-06-01), Briggs et al.
Jolly Paul Harvey Ronald
Parsons Michael Colin
Frank Robert J.
MP Research Ltd.
Nguyen Tan Q.
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