Sun angular coordinate indicator

FIELD: instrument engineering.

SUBSTANCE: device has optical spectrum filter, slit mask, multi-element photo-sensitive detector, threshold elements, photo-detector register, counter, output register, clock pulse generator. Multi-element photo-sensitive detector consists of elementary photo-detectors placed behind one another along quadratic curve. Normal lines to sensitive areas of each elementary photo-detector and quadratic curve lie in same plane.

EFFECT: higher effectiveness and efficiency.

1 dwg

 

The sensor is intended for determining the angular coordinates of the luminous reference point and, in particular, to determine the direction of the Sun in the coordinate system of the spacecraft.

The closest to the technical nature of the claimed sensor is the sensor [1], consisting of two identical channels that are used to measure angular coordinates in two mutually orthogonal planes. Each channel consists of a linear charge-coupled device, on which at a given distance in parallel planes are optical attenuation filter, the optical band-pass filter and a slit mask. In addition, each channel has: a generator of clock pulses, a signal amplifier of the charge-coupled device, a threshold device, a pulse counter, the output register and the device for storing the sign of the presence of the Sun. At the output of the sensor is formed by a digital code corresponding to the sequence number of the photosensitive element of the charge-coupled device, which is the average in the group of photosensitive elements, illuminated through the slit in the mask sunlight.

The disadvantage of this sensor is to run to find the angular coordinates of the formula

α=arctan[x(n-(N+1)/2)/d]

where α - angular coordinate; d is the distance from the surface of the device scaradavou connection to the plane which is slit mask; x - step arrangement of photosensitive elements, n is the sequence number of the photosensitive element, which is the average in the group of photosensitive elements, illuminated by the solar rays, N is the total number of photosensitive elements in the charge-coupled device.

Another disadvantage is the small size of the field of view 66°(33°), due to the discreteness of the charge-coupled device and the accuracy of calculation of functions of the form γ=arctan(x) for values larger than 1.

The aim of the invention is to obtain angular coordinates without performing computational operations and the expansion of the field of view.

This goal is achieved by the fact that the inventive sensor comprises a multi-element photosensitive receiver, and photosensitive elements are arranged not in a straight line in the plane and on the curve, in particular on the arc of a circle, resulting in the angular coordinate of the Sun is associated with the number of middle-lit elementary photodetector through the expression

α=[n-(N+1)/2]γ,

where α - angular coordinate; γ - angular spacing of photosensitive elements, n is the sequence number of the photosensitive element, which is the average in the group of photosensitive elements, illuminated by a ray of sunlight is mi, N is the total number of photosensitive elements in multi-element photodetector. That is, there is a linear relationship between the angular coordinate and the average number of the photosensitive element.

The device proposed sensor portion of a sensor and a slit mask illustrated drawings, in which 1 - multi-element photodetector; 2 - one of the elementary photodetectors; 3 - angular spacing of the elementary photosensitive elements; 4 - axis; 5 - a crack in the mask 6 is the angular coordinate of the Sun; 7 - Sun.

The sensor also includes a threshold device, the register sensor pulse counter output register clock.

Does the sensor in the following way. The sun's rays that have passed through the slit mask are transferred to the multi-element photosensitive receiver, where it is converted into an electrical signal. The electrical signal from each elementary sensor is fed to a threshold device for converting into a digital signal, which assumes the value of logical zero or one depending on whether illuminated photosensitive element or not. The output signals of the threshold devices are recorded in the register of the photodetector, which is read by the command sequentially and synchronously with the clock pulses. Simultaneously with the beginning of the output is ignal from the register of the photodetector, the counter begins to count clock pulses. As soon as the output register of a sensor a signal corresponding to the illuminated elementary photodetector, the counter starts counting pulses with a frequency of 2 times lower than the clock frequency. Then, as soon as the output register of the photodetector will receive a signal corresponding unlit elementary photodetector, the counter stops the account, and the received counter code is stored in the output register. Thus, the number of middle-lit elementary sensor and accordingly the angular coordinate of the Sun.

Multi-element photodetector can be fabricated by planar technology of the known semiconductor materials. Getting photosensitive elements that lie on a given curve, is due to the cut in the semiconductor wafer holes defined profile with a laser.

Comparative analysis with the prototype shows that the proposed sensor differs from the prototype there is no need to compute the value functions of the form arctan[x(n-(N+1)/2)/d].

No trigonometric calculations allows to extend the field of view of the sensor and when the sensor on Board the spacecraft to reduce the time required to determine the spatial orientation, which increases the reliability of the spacecraft which reduces its power consumption.

The source of information

1. Patent USA No. 4794245, NCI 250/203R, 1988.

The sensor of angular coordinates of the Sun contains the optical spectral filter, slit mask, multi-element photosensitive receiver, the threshold elements, the case of a sensor, a counter, an output register, a clock, wherein the multi-element photosensitive receiver consists of elementary photodetectors, which are located one behind the other on the curve of the second order in such a way that the normal to sensitive areas of each elementary sensor and a curve of the second order lie in the same plane.



 

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