EA040950B1 - LIGHT POSITION SENSOR - Google Patents

Description

The field of technology to which the invention belongs

The present invention relates to a sensor for determining the position of a light source and to methods for determining the position of a light source using the sensor. In particular, the invention relates to a solar sensor for a satellite.

State of the art

Sensors for determining the position of the Sun are well known and range from very simple to extremely high-tech solutions. When such sensors are intended for use in space satellites or rockets, their robustness and reliability are important. In addition, weight and volume are very important for space microprobes.

A known sensor for space microprobes from Farian et al. (A Miniturized Two-Axis Ultra Low Latency and Low-Power Sun Sensor for Attitude Determination of Micro Space Probes, IEEE Transactions on Circuits and Systems (Transactions on circuits and systems), 2017). Disclosed here are sensor units comprising two linear sensors orthogonally oriented with respect to each other. In FIG. 1 shows a sensor (sensor) according to Farian. The sensor 10 includes a sensor unit 12 on a chip 13. The mask 14 includes a transparent portion 15 which allows light 16 to reach the sensor unit 12. The position of the light source can be determined by which part of the sensor unit 12 is illuminated.

However, Farian does not consider how to place the sensor in the detector module. As a rule, to provide a field of view (FOV, field of view) over a full hemisphere, five sensors are attached to the corresponding surfaces of the cubic support structure. US 2016/0123801 A1 discloses a sensor design comprising a pyramid structure with photosensitive areas and electrical contacts on each outward facing surface of the pyramid. The position of the light source is determined by comparing the signals from different photosensitive areas.

However, the need remains for a rugged, reliable, lightweight and small sensor with a full hemispherical field of view.

The essence of the invention

According to a first aspect of the present invention, there is provided a sensor device for determining the position of a light source, the sensor device comprising: a plurality of sensor units, each sensor unit having a corresponding sensor area; and a mask positioned above the plurality of sensor units and configured such that incident light from the light source illuminates different areas of the sensor area of each of the sensor units depending on the position of the light source relative to the sensor device, so that the position of the light source can be determined based on which the areas of the sensory zone of the sensor blocks are illuminated; wherein each sensor unit is controlled by a respective unit controller to determine the position of the light source.

Each of the plurality of sensor units may be used to determine the position of the light source, and therefore, a plurality of measurements of the position of the light source by the sensor device may be made, one for each of the plurality of sensor units. The sensor unit may include any suitable mechanism for detecting light falling on it, and may include a plurality of light sensitive pixels in any suitable arrangement. Thus, the light sensitive pixels of the sensor unit constitute the sensor area.

The mask contains a transparent portion that allows light from a light source to pass through to illuminate different areas of the sensory area of each of the sensor units, and contains an opaque portion that prevents light from entering other areas of the sensory area of each of the sensor units. The mask is offset from the sensor blocks by a predetermined distance, so that for each position of the light source relative to the sensor device, different areas of the sensory zones of each sensory block will be illuminated (i.e., the shading from the mask will be different for different positions of the light source, illuminating different areas of the sensory zones) . Thus, by measuring which parts of the touch area are illuminated, the position of the light source relative to the touch device can be determined.

The touch device may be substantially flat and therefore may define a normal vector normal to the plane of the touch device.

The sensor device may be a sensor circuit and may be implemented on a single printed circuit board or the like. Thus, a touch device may have a field of view (FOV) defined by the maximum angle at which a light source can be positioned from the normal vector while still illuminating the area of the sensor block and therefore remaining detectable. The touch device may determine the direction in which the light source is located relative to the touch device.

Each sensor unit may comprise a first strip and a second strip substantially orthogonal to the first strip, wherein the mask may be configured such that a light source illuminates areas of both strips of each sensor unit simultaneously. Those. each sensor unit (and corresponding sensor area) may be substantially L-shaped, and the mask may be configured to simultaneously illuminate areas of each line of that L-shaped. The sensor strips of the sensor units may be directly adjacent to each other (eg in an L-shaped corner) or may be slightly spaced apart. Although the first and second strips are preferably oriented substantially orthogonally, they may be at any angle to each other, for example, as long as they extend at least some distance in two dimensions.

Since each sensor unit defines a touch area that extends in two dimensions of the plane, each sensor unit can operate to determine the orientation of the light source relative to the sensor device and therefore can determine its direction relative to the normal to the sensor device (i.e., polar coordinates of the light source in a spherical cap visible to the sensor units).

The first and second strips may preferably be substantially the same length, although they may be of different lengths if desired. Orthogonal strips of the same length can provide the same field of view in two dimensions.

Each sensor block strip may be a single row of pixels or any other suitable photosensitive mechanism. Thus, by measuring which pixel(s) are lit on each stripe and determining their location relative to the mask, the direction (i.e., relative position) of the light source can be determined.

The sensor units may be configured such that their pixels generate a signal when their accumulated charge (from incident light) exceeds a threshold value. Thus, the sensor units can be event-driven so that their readings are provided only when there is significant illumination. Thus, it is possible to reduce the processing required to operate the sensor units.

The sensor units may be adjacent to each other. The sensor blocks may be arranged such that the first strips of each sensor block are substantially parallel and the second strips of each block are substantially parallel. The first strips of the sensor units may be adjacent to each other, and the second strips may be adjacent to each other. Thus, L-shaped sensor units can be nested together in a compact design. As such, the strips of the sensor blocks may extend along two sides of the square, thus delimiting half of that square. If the touch device is made on a printed circuit board, then the square which is half bound by the strips can be filled with other appropriate blocks to make the touch device relatively compact.

The mask may include a first transparent slit and a second transparent slit substantially orthogonal to the first transparent slit. Those. the transparent part of the mask may be L-shaped. The first transparent slit may be positioned perpendicular to the first strips of the sensor blocks, and its middle may be located directly above the centers of each first strip. The second slit may be located perpendicular to the second strips of the sensor blocks, and its middle may be located directly above the centers of each second strip. Thus, the mask can be L-shaped, like the sensor blocks, but rotated by 180° relative to them (in the plane of the sensor device).

Each stripe of each sensor unit may contain a plurality of pixels, wherein the pixels of each stripe may be offset relative to the pixels of each adjacent stripe by a distance less than the width of each pixel in the offset direction. The pixels may be shifted by a fraction of the pixel width equal to the reciprocal of the number of sensor units in the sensor device. For example, if there are three sensor units, the pixels may be offset by one third of the pixel width. By such an offset, the resolution of the sensor device can be improved because each sensor unit will detect the light source at a slightly different position.

The sensor device may have gradient shielding to reduce the intensity of light incident on the sensor units to counteract the relative decrease in intensity of light incident on the sensor unit at an angle. The decrease in the intensity of light incident at an angle may refer to a decrease in the intensity of light incident directly on the sensor unit. The mask may be graduated to counteract the relative decrease in the intensity of light hitting the sensor unit at an angle. Light falling on the sensor device directly (ie from the light source along the normal vector) will be transmitted through the mask to the corresponding areas of the touch zones of the sensor blocks (for example, to the middle of each strip). Light incident on the touch device at an angle to the normal will pass through the mask at an angle and fall on the touch zone area at that angle. Thus, its intensity will be reduced (in proportion to the cosine of the angle to the normal). For example, light incident at an angle of 60° to the normal will have 50% of the intensity of the normal incident light, since the cosine of 60° is 0.5. Thus, the transparency of the transparent part of the mask can be graduated or gradient, so that it transmits a greater proportion of light falling at an angle than light falling directly from above. Therefore, the sensor units can receive approximately the same light intensity regardless of the position of the light source.

The gradation can be smoothed so that the mask allows more light to pass through areas further from its center and less light to pass through the transparent area of the mask directly above the sensor blocks. The graduation can be inversely proportional to the cosine of the angle of incidence of the normal vector on the touch device.

The sensor device may be configured such that each sensor unit is part of a respective power domain. Those. the sensor device may be configured such that, in operation, each sensor unit is powered by a separate power source, so that failure of any one power source will not affect the operation of sensor units in other power domains.

The sensor device may be a microsensor for a satellite or the like. It may be less than 1 cm by 1 cm, may be less than 5 mm by 5 mm, and may be less than 2.5 mm by 2.5 mm. The sensor device may be substantially flat, albeit with sufficient depth to allow the mask to stand apart from the sensor units.

According to a second aspect of the present invention, a sensor module is provided for determining the position of a light source, the sensor module comprising: a plurality of sensor devices disclosed in connection with the first aspect of the invention; and a plurality of block controllers configured to control one sensor block in each of the plurality of sensor devices, each sensor device comprising one of the plurality of block controllers.

Each of the block controllers can be functionally different from the others and thus can function completely independently of the others. Therefore, the number of block controllers can be the same as the number of sensor devices, with each block controller controlling a sensor block in each of the sensor devices. Therefore, each sensor device may have the same number of sensor units as the number of sensor devices in the sensor module. Each block controller may be configured to control only one sensor block in each sensor device.

Each sensor device may contain a corresponding one of the block controllers. Thus, the block controller of each sensor device may be configured to control a sensor block located in the same sensor device as the block controller and one sensor block located in each of the other sensor devices. As such, each unit controller may be configured to control sensor units having respective fields of view determined by the orientation of each sensor device. The sensor devices may be oriented in different directions to provide overlapping and/or complementary fields of view. Thus, each block controller may have a field of view that includes the field of view of all sensor devices.

The sensor module may have a field of view spanning at least a full hemisphere and therefore be able to determine the position of the light source anywhere in that hemisphere (ie, in any direction within that hemisphere). Thus, each controller unit of each sensor unit of the sensor module is able to determine the position of the light source in any direction of the full hemisphere. Therefore, a plurality of block controllers can provide a redundant means of determining the position of the light source in the event of, for example, one or more block controllers fail.

The sensor module may be configured such that each block controller belongs to a respective power domain. Power domains can be separate and distinct so that a failure in one domain will not affect the operation of the others. Each power domain may include a block controller as well as one sensor block of the same sensor device as the block controller. The power domain may include all sensor units controlled by the unit controller.

The sensor module may include a plurality of module controllers, wherein each module controller may be configured to control each of the plurality of block controllers. Those. each module controller can control all block controllers, and the number of module controllers can be the same as the number of block controllers and sensor devices. Each module controller may be functionally different from the other module controllers and therefore can function completely independently of them. The sensor module may be configured such that only one of the module's controllers controls the block controllers at any given time.

Each sensor device may comprise a corresponding module controller, which module controller is configured to control the block controller of that same sensor device, as well as the block controllers of all other sensor devices in the sensor module.

Each module controller may be configured to interact with a system controller such as a satellite control system or the like. The module may be configured such that only one module controller can interact with the system controller at any given time.

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The sensor module may be configured so that the module's backup controller takes over communication with the system controller in the event of failure of the module controller that previously interacted with the system controller.

The arrangement disclosed herein allows each sensor device to be identical, each containing a plurality of sensor units, a unit controller, and a module controller. Thus, it is possible to simplify the manufacture and construction of the sensor module.

In one embodiment of the sensor device, each of the sensor units is substantially L-shaped and abuts each other such that they define two sides of a square or rectangle. The sensor unit controller and/or the sensor unit module controller may each be located at least partially (and may be mostly or entirely) within a square or rectangle delimited by the sensor units. The unit controller and/or the module controller may be adjacent to the first and/or second sensor unit strips and may be adjacent to each other. Thus, the touch device can be compact and the space occupied by it can be made as small as possible.

The sensor module may include a base and three sensor devices located on respective faces of the base, the base having the shape of at least part of a tetrahedron. The base may be in the form of a tetrahedron without a top. The tetrahedral base may be in the shape of a regular tetrahedron and may support the sensor devices in position. On the fourth side, the tetrahedral base may be mounted on a surface (eg, a satellite or any other suitable device) and may thus provide sensor device coverage hemispherically above the surface by positioning the sensor devices. The sensor devices may be evenly spaced along the tetrahedral base to provide the sensor module with a field of view that includes at least the entire hemisphere above the module (ie, 180° in module azimuth and 90° in module height). The module can provide a field of view greater than a hemisphere. Accordingly, in one embodiment of the sensor module, each of the three sensor devices is parallel to the surface plane of the tetrahedron, with one sensor device on each plane facing outward if the sensor module is mounted on the surface. In another embodiment of the sensor module, each of the three sensor devices is located parallel to the plane of the surface of a regular tetrahedron, while if the sensor module is installed on the surface, then one sensor device on each plane faces outward.

Alternatively, for the desired positioning of the sensor devices, the sensor module may have a base of any suitable shape. For example, the base may be a square pyramid, a pentagonal pyramid, and so on.

By this arrangement, each block controller can function to detect (at least one sensor block in the corresponding sensor device) a light source at any position within a hemisphere above the sensor module. Each module controller can compare measurements from each of the block controllers. Each module controller may be configured to determine the average value of the measurements of the position of the light source, and may also be configured to transmit this average value to the system controller. Each module controller may be configured to determine the position of the light source as the middle position or as the median position. By choosing a median position, erroneous or outlier measurements can be ignored, and the reliability of the sensor module can be improved.

The sensor module may be a space microprobe and may be less than 100 mm, less than 50 mm, and preferably less than 25 mm. The sensor module may be a solar sensor for a satellite, a rocket probe, or the like.

According to a third aspect of the present invention, a sensor system is provided for detecting the position of a light source, the sensor system comprising a plurality of sensor modules as disclosed herein in connection with the second aspect, each sensor module configured to have a different field of view for detecting a light source.

The sensor system may be configured to detect a light source over a wider field of view than would be available using the sensor module alone. The sensor modules of the sensor system may be configured to detect a light source in opposite directions. The sensor system may contain two sensor modules and may contain only two sensor modules. The two sensor modules can be positioned so that each detects a light source in opposite hemispheres, and so the sensor system can provide a field of view over the entire sphere (i.e., a field of view in all directions) so that the position of the light source can be detected in either direction using at least one of the sensor modules.

The sensor system may include a system controller configured to interact with and/or control each of the plurality of module controllers. Each of the plurality of module controllers may be configured to send a signal to the system controller.

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According to a fourth aspect of the present invention, there is provided a satellite comprising a sensor system as disclosed herein in connection with the third aspect of the invention and/or comprising a sensor module as disclosed herein in connection with the second aspect of the present invention and/or comprising a sensor device as disclosed herein. document when considering the first aspect of the present invention.

According to a fifth aspect of the present invention, there is provided a method for determining the position of a light source using a sensor device disclosed in the first aspect, or using a sensor module disclosed in the second aspect, including: determining the position of the light source as the average of the positions determined by the sensor units .

The method may include determining the average as the average of the positions, or may include determining the average as the median of the positions. Using the median value, you can reduce the errors that distort the measurement results.

The method may include: (i) reading digital output pixel values from one of the sensor units; (ii) setting to 1 any pixel values adjacent to the pixel values constituting 1; (iii) setting to 0 any pixel values adjacent to the value 0; (iv) repeating step (iii) until performing step (iii) one more time results in all sensor block pixel values being set to 0; and (v) determining the position of the light source using the remaining non-zero pixel or pixels. The method may comprise, in step (ii), setting to 1 any pixel values surrounded by (i.e., adjacent on both sides of) pixel values that are 1.

The remaining non-zero pixel or pixels will be treated as the illuminated area of the sensor block. If the remaining non-zero pixel is a single pixel, then that pixel can be taken as the measured illumination position from the light source. If a plurality of pixels remain non-zero, then the measured illumination position from the light source can be taken as the average position of these pixels.

The method may include using a sensor system as disclosed herein in connection with a third aspect, or a satellite as disclosed herein in connection with a fourth aspect.

According to a sixth aspect of the present invention, there is provided a method for determining the position of a light source using a sensor device disclosed in the first aspect or using a sensor module disclosed in the second aspect, comprising: (i) reading digital output pixel values from one of the sensor blocks; (ii) setting to 1 any pixel values of pixels adjacent to the pixel values constituting 1; (iii) setting to 0 any pixel values adjacent to the value 0; (iv) repeating step (iii) until performing step (iii) one more time results in all sensor block pixel values being set to 0; and (v) determining the position of the light source using the remaining non-zero pixel or pixels.

The method may include repeating step (ii) a plurality of times. Step (ii) may be an OR function that eliminates pixels of type constant 0, and may be performed in one or two steps. Step (iii) can be an AND function and can exclude pixels of type constant 1, and can also find the light center of gravity (similar to, for example, the object's center of mass). The method may comprise, in step (ii), setting to 1 any pixel values surrounded by (i.e., adjacent on both sides of) pixel values that are 1.

Such a method can be used to determine the center of the illuminated area with the sensor unit, thereby making it easier to measure the position of the light source. Thus, the method can simplify the logic required to determine the position of the light source and can reduce the dynamic power consumption of the sensor module.

The method may include using a sensor system as disclosed herein in connection with a third aspect, or a satellite as disclosed herein in connection with a fourth aspect. The method may include determining the position of the light source, as disclosed herein in connection with the fifth aspect.

List of drawings

Certain preferred embodiments of the invention will be described below by way of example only and with reference to the accompanying drawings, in which:

in fig. 1 shows an example of a touch device containing a single touch unit;

in fig. 2 shows an example of a sensor device containing a plurality of sensor units;

in fig. 3A shows how the position of the light source can be measured by the sensor unit;

in fig. 3B shows an example of a light source illuminating the sensor unit at an angle α;

in fig. 4 shows a sensor module containing a plurality of sensor devices;

in fig. 5 shows an exemplary arrangement of a touch device;

in fig. 6 shows a diagram of the signal and power domains for the three sensor devices of the sensor module;

- 5 040950 in FIG. 7 is a signal and power domain hierarchy diagram for a sensor module containing block controllers and module controllers;

in fig. 8 shows an example of the arrangement of pixels in the touch blocks of a touch device.

in fig. 9 shows the change in the intensity of light falling on the sensor block at different angles;

in fig. 10 shows pixel values according to the steps of the digital signal processing method;

in fig. 11 shows data on a module bus between sensor module domains;

in fig. 12 shows an example of light intensity on the sensor unit;

in fig. 13 shows pixel values according to a distributed digital signal processing method;

in fig. 14 shows pixel values according to a modified distributed digital signal processing method;

in fig. 15 is a diagram of a sensor module including the signal and power domains for the three sensor devices it contains;

in fig. 16 shows a schematic control hierarchy for a sensor module containing three sensor devices; and in FIG. 17 shows a schematic control hierarchy for a sensor system containing a plurality of sensor modules.

Detailed disclosure of the invention

In FIG. 2 shows a sensor circuit 100 (also referred to as a sensor device or sensor element) according to the present disclosure, comprising a plurality of sensor units 110 that are configured to operate independently. The sensor circuit 100 includes a mask 120 comprising a transparent region 122 and an opaque region 124. The transparent region 122 and the opaque region 124 allow light to illuminate specific different areas of the sensor blocks 110 depending on the orientation of the light source with respect to the sensor circuit 100. Thus, the position of the source of light (or its direction relative to the sensor device 100) can be determined by measuring which areas of the sensor units 110 are illuminated.

Any failure of one L-shaped sensor 110 will not affect the others, since each of them can function independently and can belong to their respective separate signal and power domains. Accordingly, the reliability of the sensor circuit 100 can be improved without increasing the surface area required for the sensor circuit 100 (and therefore without increasing its size). When multiple sensor units 110 work together, they can also increase the resolution of the sensor device 100.

Each sensor unit 110 includes a first strip 112 and a second strip 114 perpendicular to the first strip 112. Thus, the first and second strips 112, 114 extend in two dimensions in the plane of the sensor device 100, providing a two-dimensional measurement of the position of the light source. The transparent portion 122 of the mask 120 includes a first transparent slot 126 and a second transparent slot 128. The first transparent slot 126 is positioned perpendicular to the first strips 126 of each of the sensor units 110, and the second transparent slot 128 is positioned perpendicular to the second strips 114 of each of the sensor units 110. Thus, the transparent portion 122 of the mask 120 has an L-shape similar to the shape of the sensor units 110, although rotated 180° in the plane of the sensor device relative to the sensor units 110.

The first transparent slot 126 is located above (for example, directly above) the centers of the first strips 112 of the sensor units 110. Therefore, moving the light source in the direction determined by the first strips 112 will cause the shadow from the mask 120, and hence the light passing through the first slot, to move. 126. Thus, light falling on the first strips 112 through the first slot 126 will travel in the opposite direction along the first strips 112. Similarly, moving the light source in the direction defined by the second strips 114 will cause the light passing through the second slot 128 to move, in the opposite direction along the second strips 114.

In FIG. 3A shows the locations of the illuminated areas on the sensor unit 110 depending on the position of the light source relative to the sensor device 100. The coordinates are given in arbitrary units along the X and Y axes, and only one sensor unit 110 is shown for simplicity. When the light source is directly above the sensor device 100 (i.e., in the direction of the normal vector from the surface of the sensor device), the first transparent slot 126 of the transparent section 122 of the mask 120 will create the first illuminated area 127 on the first strip 112 of the sensor unit 110 just below the first slot 126. The second slot 128 of the mask 120 will create the second illuminated area area 129 on the second strip 114 of the sensor unit 110 just below the second slot 128. This situation is shown in the center of FIG. 3 for coordinate (0,0).

If the light source moves from the normal only in the X direction, towards the (1,0) coordinate, then the second illuminated area 129 will move in the opposite X direction, while the first

- 6 040950 the illuminated area 127 will remain in the same place on the first strip 112 of the sensor block 110. If instead the light source moves to the coordinate (-1, -1), then both the first and second illuminated areas 127, 129 will move on the touch block 110 as shown. Different positions of the light source will cause different areas of the sensor unit 110 to be illuminated. Thus, the position of the light source relative to the sensor device 100 can be determined based on which areas of the sensor unit 110 are illuminated.

In FIG. 3B shows a light source at an angle α from the normal to the planar sensor device 100. The angle α of the light and the distance d between the mask 120 and the sensor element 110 determine where the light hits the sensor unit 110. The field of view of the sensor device depends on the ratio L/d , where L is the length of the sensor block in the corresponding direction. The high L/d ratio gives a large field of view. In the one shown in FIG. 3B, the width (W) of the transparent slit is 50 µm, the thickness (h) of the mask 120 is 100 nm, the distance (d) between the mask 120 and the sensor unit 110 is 356 µm, the length (L) of the sensor unit is 2256 µm, and the pixel pitch - 11.75 microns. The strip of the sensor unit 100 contains 192 pixels evenly distributed along its length, which is 2256 microns.

The sensor units 110 are arranged next to each other such that the first strips 112 are parallel and adjacent and the second strips 114 are parallel and adjacent. By arranging multiple sensor units 110 on the sensor device, it is possible to obtain multiple light source position measurements using a single mask 120 and without significantly increasing the size of sensor device 100. Therefore, sensor device 100 provides redundancy with respect to light source position measurements.

In FIG. 4 shows a sensor module 200 containing three sensor elements 100 (ie, sensor devices 100 or sensor circuits 100); wherein each of the sensor elements 100 is parallel to the respective surface planes of the tetrahedron 210, one on each plane facing outward if the sensor module 200 is mounted on the surface. This provides a full field of view (FOV) of the hemisphere with just three 100 sensor elements while taking up minimal volume. This arrangement also provides FOV overlap, contributing to increased resolution.

The present invention also provides a sensor module 200 that is improved in several other technical aspects. For example, pixel reading may be event-driven. After a master reset, pixels generate an event signal when their accumulated charge (from light) exceeds a threshold. It requires little computing power. Thus, depending on the number of sensor units 110, each sensor element 100 may include processing units 130. FIG. 5 shows a sensor element 100 comprising a processing unit 130 configured to control sensor units 110 (ie, unit controller 130). Block controller 130 is configured to control one sensor block 110 of the same sensor element 100. Block controller 130 is further configured to control sensor blocks 110 from other sensor elements 100 of sensor module 200.

In FIG. 6 shows an example of the arrangement of sensor elements 100a, 100b, 100c. Block controllers 130a-c on each sensor element 100a-c belong to different power and signal domains and are designed to control the respective sensor blocks 110a-c, one sensor block 110a-c on each sensor element 100a-c. Thus, each unit controller 130 may determine the position of the light source using any of the sensor elements 100. Each sensor element 100a, 100b, 100c may comprise a respective module controller (140a, 140b, 140c) as shown in FIG. 5.

As shown in FIG. 6, by positioning the unit controller 130 and/or module controller 140 within the square defined by the L-shaped sensor units 110, each sensor device 100 (i.e., sensor element 100) can be compactly configured to take up as little space as possible, and hence each sensor device and hence the sensor module and sensor system can be as small as possible.

The present invention may include a hierarchical organization of sensor elements 100 and sensor units 110 that provides stable and reliable operation of sensor module 200. FIG. 7 shows a hierarchical layout diagram of the signal and power domains of the sensor module 200. The sensor module contains three separate domains, one for each of the block controllers 130. Each touch element 100 contains a module controller 140 (eg, module master 140) operative to control the entire touch module 200 (see, for example, FIG. 5). Each module controller 140 is configured to control all block controllers 130 (eg, domain masters 130) and can be connected to each of the power domains. Each unit controller 130 is configured to control one (and only one) sensor unit 110 in each of the sensor elements 100.

Therefore, each unit controller 130 independently controls a plurality of touch units.

- 7 040950 kov 110 to determine the position of the light source. The respective domains of the block controllers 130 are also powered independently. Each module controller 140 controls all of the block controllers 130 and therefore can be configured to compare measured positions from all of them and perform a final determination of the position of the light source. Each module controller may be further configured to send a signal indicating the position of the light source to the system controller. The sensor module 200 may be configured such that at any given time, only one module controller 140 controls the block controllers 130.

In addition to operating in different signal domains, unit controllers 130 (together with their respective arrays of sensor units 110) each have separate power domains. Those. each block controller 130 functions completely independently of the others, and if any of them suffer the failure of their respective power supply, the others will still continue to function. As such, the sensor module 200 provides redundancy in case any of the power domains is affected by a power failure. Each module controller 140 may belong to one power domain (eg, the same as the block controller 130 of the same sensor device 100) or may belong to each of the power domains. This arrangement means that the sensor module 200 provides redundancy not only in terms of measuring the position of the light source, but also in terms of power failure in any of the domains and/or sensor devices 100.

In FIG. 8 shows on an enlarged scale the first strips 112 of the sensor units 110 of each sensor device. Each strip contains a plurality of pixels 115 arranged in a line. The pixels 115 of each stripe 112 are offset from the pixels of adjacent stripes 112. Such an arrangement can provide increased resolution of the touch device 100. Each of the depicted lines of pixels 115 shows a portion of the stripes 112 of the sensor unit 110. The pixels 115 of each stripe 112 are shifted by 1/3 pixel pitch relative to each other. friend. By combining information from all domains, the resolution of the sensor device 110 can be increased by 1/3 of what each domain can provide individually.

Touch elements 100 may include gradient screening of pixels. Such shielding can counteract the reduction in intensity caused by light striking the sensor units at an angle to the normal vector. In FIG. 9A shows an example of how the intensity of the first illuminated region 127 changes with the angle. Pixels 115 of the sensor unit 110 are illuminated in the first illuminated region. The number of illuminated pixels 115 will be the same for the light entering the center and the periphery. However, at the periphery, the light intensity will be less (maximum times cos(a)). The resolution (degrees/pixels) is higher at the periphery than at the center.

In FIG. 9B shows the signal level distribution as a function of the angle of the light source relative to the normal. Also shown for reference is the maximum albedo of the Earth and the maximum albedo of the Moon. In FIG. 9B also shows that when the light source is at 60°, the signal level is 50% of the signal level when the light source is at 0°.

Thus, gradient screening of pixels can be used to reduce the intensity of the incident light as required to equalize the signal level across the angles of incidence. For example, 50% of the surface of the center pixels may be plated in a certain order. As the angle increases, a reduction in coverage can be used so that no shielding is required at the edges of the sensor block. The shielding may be positioned as desired within the touch device to prevent light from reaching the pixels as desired. For example, shielding may be included in the mask 120.

The sensor module can use distributed digital signal processing to improve performance and reduce power consumption. In FIG. 10 shows signals from a sensor strip according to successive steps of an exemplary distributed signal processing method. At time t0, each pixel 115 has either registered (1) an event or not (0). In the first step, any pixels 115 set to 0 that are surrounded by pixels set to 1 are set to 1. This removes the mismatched pixels from the signal. The result is shown at time t1 in FIG. 10. In the next step, any pixels with value 1 adjacent to pixels with value 0 are set to 0 (see t2). This is repeated until repeating this one more time results in all pixels being set to 0 (see steps t3, t4 and t5).

This process requires minimal processing power and determines the center of the illuminated area (similar to the center of gravity of a mass), which can be used to locate the light source.

In FIG. 15 is a diagram of a sensor module 200 including three sensor devices 100a, 100b, 100c. The arrangement is similar to that of Fig. 6, with unit controllers 130a, 130b, 130c and module controllers 140a, 140b, 140c respectively shown for each sensor device 100a, 100b, 100c. The layout and control hierarchy are the same as those of the touch module of FIG. 6.

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Signal domains and power domains for sensor module 200 in FIG. 15 are indicated by color or shading. The unit controller 130a of the first sensor device 100a is in the same signal domain as the sensor unit 110a on the same sensor device 100a. The signal domain contains one sensor block 110a of each of the three sensor devices 100a, 100b, 100c. Thus, each sensor unit 110a is configured to send signals to the unit controller 130a. Each module controller 140 can detect a light source via any of the three signal domains controlled by block controllers (ie, domain masters) 130a, 130b, and 130c. If one signal domain fails, the other two will be available as redundant so that the sensor module 200 can continue to operate. Only one module controller (eg, module controller 140a) will act as a master controlling sensor module 200 at any given time. The other two module controllers (eg, module controllers 140b and 140c) may be in sleep mode (eg, ready to take control from the first module controller 140a in the event of a fault) or may operate in parallel, testing the module controller (eg, module controller 140a), playing the role of a master. If both other module controllers (eg, controllers 40b and 140c) do not agree on the module master role (eg, module controller 140a), then they can transfer the master role to one of the others.

The controller 140a of the module of the first touch device 100a is in the same power domain as the block controller 130a of the first (same) touch device 100a, and the sensor units 110a (i.e., sensor elements 110a) of the same touch device 100a and two other touch devices 100b and 100c. Module controller 140b, unit controller 130b, and sensor units 110b are likewise in the same power domain as each other. The same applies to module controller 140c, unit controller 130c, and sensor units 110c. Each food domain is separate and independent from the others.

In the arrangement shown in FIG. 15, each power domain contains the same components as the signal domain plus a module controller on the same sensor device as the block controller from the signal domain. Each power domain is powered by a separate, independent power source so that if any one power domain fails in operation (eg, power supply failure), the sensor module 200 has additional power domains available and can continue operation. Thus, the sensor module 200 is triple redundant in this respect.

In FIG. 16 schematically shows the signal and power hierarchy for sensor unit 200. The layout in FIG. 16 is the same as in Fig. 7, and each touch device 100a, 100b, 100c is further shown. Each sensor device 100 is a physical unit (eg, a circuit device, etc.) and is associated (eg, logically and/or functionally) with other sensor devices 100 in the sensor module 200 in the signal and power hierarchy shown. The power domain 150 of the controller 130a of the unit of the first touch device 100a is shown in dotted outline. In this case, the power domain 150 includes one sensor unit 110a on each sensor device 100a-c, as well as a unit controller 130a and a module controller 140a. Thus, each power and signal domain includes sensor units 110 from each sensor device 100. While sensor devices 100 are tangible components, domains are logical (e.g., functional and/or electrical) groupings of subcomponents of sensor devices 100.

In the sensor module 200 shown in FIG. 16, the module controller 140a of the first sensor device 100a controls the entire sensor module 200, so that each of the block controllers 130a, 130b, 130c is controlled by it and sends signals to it. In addition, through each of the unit controllers 130a-c, all sensor units 110a-c on each of the sensor devices 100a-c are controlled by and send signals to the first unit controller 140a.

The sensor module 200 contains three power domains, shown in color or shading of the respective components or their outlines. Components with the same color or with the same shading belong to the same power domain and are therefore powered by the same power source. The three power domains of the sensor module 200 are separate and independent. The sensor units 110a of each sensor device 100a-c are in the same power domain 150 (ie, have the same power source) as the first module controller 140a and the first unit controller 130a. Other sensor units 110, unit controllers 130, and module controllers 140 of other sensor devices 100 have the same layout.

In case the first module controller 140a fails, the second module controller 140b is configured to take over control of the sensor module 200. If the second module controller 140b fails, the third module controller 140c is able to take control of the sensor module 200. Thus, the sensor module 200 is triple redundant in this respect.

It should be understood that the term sensor device is used here interchangeably with the terms sensor element and sensor circuit. The term block controller is used interchangeably with the term domain master, and the term module controller is used interchangeably with the term module master.

In FIG. 17 shows a sensor system 300 with only two sensor modules 200a, 200b. Each of the sensor modules 200a, 200b is similar to the sensor module 200 in FIG. 16. However, in the first touch device 100a of the second touch module 200b, the signal domain 160 does not include the first module controller 140a. The power domains of each sensor module 200a, 200b are indicated by component color or shading, such that components of the same color or shading belong to the same power domain and are therefore powered by separate, independent power supplies.

The first sensor module 200a in this example is controlled by the first module controller 140a, which is the far right in FIG. 17. The second sensor module 200b is controlled by the first module controller 140a, which is the central one in FIG. 17. The other module controllers 140b, 140c of each sensor module 200a, 200b may control their respective sensor modules 200a, 200b in the event of a malfunction or failure of the first module controller 140a.

In FIG. 17 shows a signal domain 160 for the controller 130a of the sensor module unit 200b. All other block controllers 130 have the same signal domain. All module controllers 140 in one module 200 have access to all signal domains 160 via block controllers 130.

The sensor system 300 includes two sensor modules 200, each with a field of view covering a hemisphere or more. The sensor modules 200 can be configured to see opposite hemispheres so that the sensor system 300 can be used to detect the position of a light source across the entire sphere (ie, in any direction). Therefore, a total of six sensor devices 100 can be used to enable detection of a light source in all directions while ensuring detection accuracy and functional redundancy. Each sensor module 200 has plenty of redundancy for signal acquisition and power delivery in a very compact package. In addition, the presence of multiple sensor units 110 in one sensor unit 100 not only provides redundancy, but can also be used, for example, to increase resolution (for example, by offsetting the pixels 115 of adjacent strips 112 of sensor units 110, as disclosed by considering Fig. 8) .

Examples

The following is a list of terms used here.

Sensor Line/Strip: A one-dimensional line of photosensitive pixel sensors implemented on a CMOS (complementary metal-oxide-semiconductor) integrated circuit.

Sensor unit (or L-shaped sensor): two sensor lines orthogonally oriented in an L-shape. The sensor unit can detect the position of an illuminating object in two dimensions.

Mask/Slotted screen: Above the sensor block is a screen with an L-shaped transparent hole oriented 180° relative to the sensor block.

Domain: A domain is a functional area that separates signal and power. The different domains are completely independent, and even fatal short circuits in the power supply in one domain will not affect the others. A domain can span multiple physical devices, and a single physical device can have multiple domains.

Sensor/sensor/sensor device/element/circuit/ASIC (Application Specific Integrated Circuit): A physical integrated circuit that houses one or more sensor units from one or more domains.

Detector/Sensor Module: A module containing sensor circuits, other components, base, chassis, housing, etc. for hemisphere measurement.

Detector System: Depending on the application, the detector system may comprise one or more detector modules. In the case of a satellite, these may be two detector modules oriented in opposite directions.

X, Y, and Z axes: The X, Y, and Z axes are local references for each sensor map.

φ (phi) and θ (theta): polar coordinates in the detector module, φ ranges from 0 to 360° and in the X direction (offset by 120°), and θ ranges from 0 to 90° and in the Y direction .

Event Handling: Each device triggers a flag signal (signal) on a shared line when a certain situation occurs. This is different from polling, where the central unit requests all elements one by one in turn.

The known sensor consists of one sensor circuit with one sensor unit. It has been developed for rocket probes and its function and performance has been verified in the laboratory. The known version has no redundancy. There are no radiation requirements, and therefore it was not designed for this. It has a 144° field of view in both the X and Y directions. Some external electronics are required to generate control signals, etc. A known version is disclosed by Farian et al.

The sensor according to the present invention may contain three identical sensor circuits in

- 10 040950 designs of a quadrangular pyramid. It can be designed for a wider range of applications, from satellites in geostationary orbit to solar panels and window blinds used on Earth. Such embodiments of the present invention can provide triple redundancy and thus can be designed with high radiation hardness in mind. It may have a field of view well in excess of 180° (i.e. a hemisphere). A minimum of external components may be required.

The L-shaped sensor is shown in Fig. 1 and consists of two orthogonally oriented rows of sensors located along the two edges of a 2.5x2.5 mm ASIC chip implemented in the 0.35 µm CMOS Opto process from AMS. The pixel reading may be event-driven. After a master reset, pixels generate an event signal when their accumulated charge (from light) exceeds a threshold. Thus, the time from reset to event represents the light intensity. The number of events that can be read is programmable.

Since the only analog element is the comparison of the pixel signal with a common threshold value within each pixel, the analog part is kept at an absolute minimum. Thus, there is no need for analog-to-digital converters or analog units, which can be sensitive to radiation or noise. This simplifies the design and improves reliability. The device supports a fairly high measurement speed. If better resolution is required and the speed is not high enough, then the overall threshold level can be reduced. This gives more events per time period and more data to reduce the standard deviation.

As shown in FIG. 1, the sensor circuit (largest red square) contains two orthogonally oriented lines of sensors (solid red). This is covered by an opaque slit screen with two transparent slits (solid yellow) in an L-shape, oriented 180° with respect to the sensors.

The sensor and slit are positioned so that the intersection points of each are at the center of the other when the Sun is perpendicular to the plane of the sensor.

The integrated circuit (sensor) has a size of 2.5x2.5 mm. The package size is 9.5x9.5 mm.

As shown in FIG. 3B, the angle of incidence of sunlight and the distance between the slotted screen and the touch element (d) determine where the light hits the sensor. The field of view depends on the ratio L/d, where a high value of L/d gives a large field of view. In the present embodiment, W=50 µm, h=100 nm, d=356 µm, L=2256 µm, pixel pitch=11.75 µm, with 192 pixels uniformly distributed over 2256 µm.

As shown in FIG. 9A, the number of illuminated pixels will be the same for light incident at the center and at the periphery. However, at the periphery, the light intensity will be less (maximum value multiplied by cos(a)). The resolution (degrees/pixels) is much higher at the periphery than at the center.

In FIG. 3A shows how the sun will fall on the sensor element depending on the position of the sun. Note that the maximum angle α to the normal vector is in both the X and Y directions. Therefore, the angles covered are α\2 to the normal vector. The X and Y axes have a field of view (FOV) of 2α, and the diagonal FOV is α2^2.

The following table compares the requirements of the AO8884 with an L-shaped sensor. The field of view (FOV) depends on the distance between the sensor and the slit. With the available distance (d=356 µm), the FOV is 144°, but the accuracy does not meet the 1° accuracy requirement. However, in a 3D design with three sensors, each sensor only needs to cover 120°. If the distance is adapted to this (d=651 µm), then the hardware accuracy of the circuit is 1.03°. The number of pixels can be increased from 192 to 256, and the pixel pixel precision will be 1.0°. Accuracy will be further improved by interpolating and shifting duplicate sensor lines.__________

Technical data AO8884 L-shaped sensor Areas Requirements Technical data L-shaped sensor Version available (s1=356µm) L-shaped sensor adapted to FOV=120° (c1=651µm) Price 400,000 euros TRL 5 Functional Issued data The direction of the Sun in the SC frame Direction of the Sun as pixel coordinates ΧΥ of the brightest cells Productivity (in full Angular accuracy (including resistance to -Full FOV (180°): 5° (3σ) Stock 0.9% (=30.9%-30.0%) Stock 20% (=50.0%30.0%)

- 11 040950

thermal and dynamic environment) solar flares, SEU, albedo and scattered light) - Accurate FOV (60°): 1° (3σ) (target 0.5°) >60°:0.17°-1.38° <60°:1.38°-1.89° >60°: 0.26°0.76° <60°:0.76°- 1.03° -Full FOV: Hemisphere (180°) 120° full angle - Accurate FOV: +/- 30° field of view (60°) 144° Weight of the whole systems 400g 0,Zgr* Sensor dimensions (without electronics) 120 x 120 x 60 mm 2.5x2.5mm2* Electronics dimensions (if referenced) Average energy 100 x 100 x 50 mm Interfaces consumption 2 W 6,3mkW* Thermal accommodation 2 W 6,3mkW* 5V regulated OR Served (12V OR 28V OR voltage 50V) unregulated 3.3V adjustable Digital: TBD type Interface (subject to data clarification) Digital Reservation Internal None (great potential) Preliminary tests + Life time 15 years at GEO 1 hour in rocket flight Thermal cycles 7000 unknown Reliability 100FIT @30°С unknown Construction and Radiation Electronic Possibly at least RA components: 100 krd standard COTS (50-70krd) Optics: ZOOkrd Detector (if equipped): 1Mrd SEU resistant No ITAR - components Without ITAR Without ITAR Angular velocity: 113005/sec (rotating Dynamics +/-100% i.e. 1005/sec rocket) Storage and working_ from -40 to +75°C Connection Extension solar panels: Unknown but possible Temperature from -80 to +100°С (FA) minimum from -40° up to +125° terms of Use Sinusoidal:at 20g peak Random: RMS 27g vibration and Stroke: 3000g 2 to No problem for myself blows 10 kHz sensor, depending on the packaging

* this only applies to the touch element itself. However, the need for additional electronics is quite limited, so power consumption will still be low compared to alternatives. To increase size, weight, etc. only packaging, printed circuit board, etc. is required.

- 12 040950

An L-shaped sensor can be generally characterized as follows.

Two orthogonal touch lines.

Reduced footprint and reduced power compared to standard pixel array solutions. Same performance. Better positioning and better elimination of false sunlight sources (reflection, ghost, etc.) than analog systems.

Event driven.

Reduced power consumption and increased speed.

The analog part is reduced to a simple comparator in each pixel cell.

This improves radiation resistance and reduces sensitivity to noise.

In one embodiment, the implementation of the sensor module can be characterized as follows.

The modules are arranged on a tetrahedron with sensory circuitry on three sides (not the bottom).

Gives a total field of view of over 180° (hemisphere).

Each sensor circuit contains three sensor blocks, each belonging to three different power and signal domains. Domains are fully redundant and each domain provides a complete field of view.

Increased reliability, flexibility, correctness and accuracy.

A short-term failure in one domain (particle hit, etc.) will be smoothed out by the other two, which make up the majority. For a longer outage, it is possible to shut down one domain and restart it while the other two remain up. A permanent fatal failure in one domain will not affect the other two, which are fully serviced. If one domain provides sufficient performance, then the other two can be disabled to save power.

All sensor circuits are the same. All schemes contain three touch elements, a domain master, a module master and a complete interface scheme. However, only one module master is active at any given time.

Simplifies logistics and development. It is necessary to develop only one device containing everything necessary to create a compact complete system with three circuits.

Distributed digital signal processing for each sensor line.

Filters single and double pixels constant 0. Filters up to triple pixels constant 1. Finds the center of gravity of the light.

Can be bypassed and turned off to save power.

Gradient pixel shielding to compensate for reduced sensitivity at the edges.

Provides more uniform sensitivity across the entire sensor line. Useful for a number of other uses.

Relative offset in 1/3 pixel increments between three sensor units on each chip.

Resolution increased by 1/3.

The sensor measurement system may comprise two sensor modules physically separated and located in opposite directions on the spacecraft. Each module has a field of view (FOV) of 180° plus some overlap.

In FIG. 4 shows a tetrahedral sensor module. The sensor module is based on three sensor circuits placed on three sides of a tetrahedral pyramid, the common angle (D) being orthogonal. The pyramid may or may not include the top. A sensor circuit is an integrated circuit containing pixel cells, some control circuit, and some power management device. This design ensures that we can provide a viewing angle of more than 180° based on sensor elements with a field of view of just over 120°. The design covers all corners above the base of the tetrahedron and some below.

As shown in FIG. 2, the shape of the L-shaped sensor block leaves a significant portion of the area unused. In the sensor circuit, the L-shaped sensor is tripled, with each block associated with different independent signal and power domains. With this solution, we will have three sensory domains, all of which are represented in all directions. Each domain has a field of view of over 180°. Signal and power supply (including the connection of pad contacts) are completely independent. The only common terminal is ground.

In FIG. 6 shows the domain map for each sensor map. In the known version, the shape of the L-shaped sensor block leaves a significant portion of the area unused. In the disclosed sensor circuit, the L-shaped sensor block is tripled, with each block associated with different independent signal and power domains. With this solution, there are three sensory domains, all of which are presented in all directions. Each domain has a field of view of more than 180°. Signal and power supply (including the connection of pad contacts) are completely independent. The only common terminal is ground.

As shown in FIG. 2, each touch element contains three L-shaped touch structures, some digital signal processing, power management, and a bus interface. With a 13 040950 indoor L-shaped sensor, you can get three completely independent (including power) L-shaped sensors on one device. Thus, any failure of one L-shaped sensor will not affect the others. When they work properly, all data can be combined to improve resolution and so on.

The 3D sensor structure may have three independent and identical digital signal processing modules (shown flat in FIG. 6). Three different and completely independent food domains are shown with different shading/color. A short circuit in one of them will not affect the others (except for the absence of data from this domain). The two sensors on each device belong to an adjacent power domain. Thus, for example (red) DSP1, S11, S21 (on device 2) and S31 (on device 3) belong together. This also applies to interfaces, i.e. to power input-output pads, etc. If both devices 2 and 3 fail, then device 1 will still have sensors in all directions and be able to provide a full hemisphere (>180°) FOV. If all devices are working properly, then each DSP (digital signal processor) has access to all nine sensors and can use this to increase resolution.

The L-shaped sensor was developed using a standard 350 µm CMOS process from AMS (Austria Micro Systems). It was designed for rocket probes and therefore did not need the long term radiation hardness required for this application. However, IDEAS has developed a radiation tolerant library for the same characterized process according to the required radiation levels. This is a library that has been developed and proven to be stable over time.

In one embodiment, the disclosed L-shaped sensor comprises two lines of sensors one pixel wide and 256 pixels long, orthogonally oriented in an L-shape. The three L-shaped sensors on an element can be internally shifted in 1/3 pixel increments. This improves reliability and resolution. The L-shaped sensor can be event-based. The pixels contain a semiconductor (PN) diode in which the charge generated by the incident light increases the voltage over the capacitance. When the threshold value is exceeded, the pixel generates an event signal. This reduces the analog part to an absolute minimum. There is no need for analog signaling, shared analog blocks, analog-to-digital converters, etc., with the advantages that this brings in terms of reliability, immunity to radiation, immunity to noise, processing speed and power consumption. The allowable time window for events can be set to a fixed number (default) of master clock cycles, a programmable number of cycles, or a programmable number of events.

The following table provides an overview of the features from the technical part of the European Space Agency (ESA) tender documentation for AO8884 compared to the L-shaped sensor and the disclosed sensor module.

Technical part of the ESA tender documentation for AO8884 L-shaped element Sensor module Areas Requirements Technical data L-shaped sensor adapted to FOV=120° (c1=651µm) Three new elements in a tetrahedron Price 400,000 euros TRL 5 Functional Issued data Direction Sun in SC frame Direction of the Sun as XY pixel coordinates of the brightest cells The direction of the Sun in the SC frame Productivity (for full thermal and dynamic environment Angular Accuracy (including solar flare, SEU, albedo and ambient light resistance) -Full FOV (180°): 5° (per) -Precise FOV (60°): H (Over) (target 0.5°) Stock 20% (=50.0%-30.0%) Stock: 70% (=100%-30%) >60°: 0.26°-0.76° <60°:0.76°-1.03° 0.16-0.5° Full field of view angle -Full FOV: Hemisphere (180°) 120° >180°

- 14 040950

- Accurate FOV: +/-30° (60°) Interfaces Mass of the whole system 400g 0,Zgr* bulk + packing Sensor dimensions (without electronics) 120x120x60 mm 2.5x2.5mm2* 25mm + packing Electronics dimensions (if there is a link) 100 x 100 x 50 mm 25mm + packing Average Energy consumption 2 W 6,3mkW* <10mW Thermal accommodation 2 W 6,3mkW* <10mW Supply voltage 5V adjustable OR (12V OR 28V OR 50V) non-adjustable 3.3V adjustable 5V Data interface Digital: Type TBD (TBC) Digital Digital Construction and RA Reservation Double None (great potential) Almost 100% triple Life time 15 years at GEO Preliminary tests + 1 hour in flight 15 years at GEO Thermal cycles 7000 unknown 7000 Reliability 100FIT @30°C unknown 100FIT @30°C Radiation Electronics: 100 cd Optics: 30 cd Detector (if equipped): 1 md SEU resistant Possibly at least standard COTS (50-70krd) According to requirements No ITAR Components Without ITAR Without ITAR Without ITAR terms of Use Dynamics Temperature Vibration and shock Angular rate: +/-100% i.e. 100S/s Storage and operating_ 40 to +75°C Solar extension: 80 to +100°C (TVS) Sinusoidal: 20 g peak Random: 27 g RMS Stroke: 3000g 2 to 10 kHz 11300S/S (spinning rocket) Unknown, but possibly at least -40° to +125° No problem for the sensor itself, depending on the packaging 11300S/S According to requirements According to requirements

In FIG. 7 shows a diagram of the logical hierarchy of modules. All domains have a domain master. Below the domain master are three sensor blocks located on three different sensor circuits. All sensor circuits also have a module master, but only one is active at any given time. The module master aggregates the information from the domain masters and forwards the final data to the external user. The module master handles all contact with the outside world. He accepts

- 15 040950 setup data and forwards it to the three domain masters. If the module master fails, one of the other module masters will be ready to go in no time.

In FIG. 5 shows an example of what a sensor circuit might look like. The top and right edges show the interface facing the sensor blocks on the other two sensor circuits. On the left side there is a bus for communication between the masters of the module. At the bottom left there is a bus for external communication. The circuit contains three L-shaped sensor blocks, a domain master and a module master, as already mentioned. It also contains a block with protocols, etc. for external communications (eg SpaceWire, SPI, etc.). The last block is the power control, measurement and control block. This block measures the current drawn by this domain and turns off the power if the current exceeds a certain limit.

In FIG. 8 shows the shifted pixel lines. Three pixel lines are shifted by 1/3 pixel relative to each other. By combining information from all domains, this will increase the resolution by 1/3 of what each domain can support separately.

The communication and states of the sensor unit will now be described. In addition to power (and ground), there are five wires between each sensor unit and the domain master: CLK, R/W, EN, X, and Y. The first three are one-way directions from the domain master to the sensor unit. The last two are bidirectional where the R/W signal controls the direction.

The sensor unit has four main modes:

Sidle is an inactive mode. This mode can be entered by setting EN high and setting R/W to record;

Smeasure is a measurement mode in which pixels accumulate light. Pixels are reset the first time EN goes low after entering this mode. When EN goes high, pixel events are stored in the SR latches and pulses are sent on the X and Y wires. When EN goes low again, further event pulses are blocked from the event bus and from setting the SR latches;

Sshift is a mode in which data is shifted to upper case from the sensor unit or register settings are shifted to lower case. Whether data is read or register settings are lowered depends on the R/W signal;

Soptimize is the mode in which the distributed digital filter is activated. The filter will try to exclude single and double constant 0 and single and double constant 1 (depending on the setting) and find the light center of gravity.

Distributed digital signal processing will be disclosed with reference to FIG. 10. After the end of the measurement (Smeasure period), a simple and distributed signal processing takes place on the sensor. First, any single zeros (surrounded by ones) are replaced by a one (see FIG. 10, steps t0 through t1). This is necessary for filtering pixels set to constant 0, low gain filters, and the like. Inverse filtering then occurs when pixels that have a neighbor with a value of zero (or zero itself) are set to zero (see FIG. 10, step t1 to t2 to t3 to t4). This will find the weight point for the light (pixel 5 at t4) and remove the individual ones (surrounded by zeros) (pixel 12 at t1). This process will be repeated until at the next step (t5) all pixels are zeroed. Then the pixel from 1 closest to the control end (pixel 5 at t4) will give out its position on the common bus. If the next pixel along the line is equal to one, then this will signal that the weight point is between two pixels. This filtering is done with simple distributed logic requiring multiple gates per pixel. Dynamic power consumption will be low as most of the pixels will remain at zero.

DSP can be distributed over pixel lines with multiple logic gates per pixel. This can provide faster and better processing and possibly less power consumption as well. Most of these blocks will remain 0 and only some of these valves will switch during operation. This solution can reduce power consumption, for example, if the static leakage current is much lower than the dynamic power consumption of switched gates, as in many CMOS technologies.

Each pixel can set a private latch if the signal passes the threshold level within the time window of the event. If the threshold is outside the time window of the event, the latch cannot be affected. The event window can be triggered by a reset pulse. Depending on the setting, the event window can be closed, for example, when: a specified time has elapsed, several events (one or more) have been generated, and/or a certain time has elapsed since the last event signal. Given the preferred settings for a touch device, an average of 4.5 pixels will be illuminated by a light source (eg the Sun). The light intensity is shown as line 1201 in FIG. 12.

There may be slight differences in offset and gain between pixels. This is illustrated by stepped line 1202 in FIG. 12. If the event window only closes after one or two events, the final determined position (for example, light center of gravity) will be slightly to the left, which will reduce resolution and accuracy. Therefore, it is important to stay open for enough events (or for enough time) to get a more accurate center of gravity. This is complicated by erroneous pixels, consistently dark or bright, or with very low or high gain. To improve this, the described distributed digital signal processing can be used.

The table in FIG. 13 shows an example of digital processing. The top row shows the pixel values (0 or 1) sampled during the time window of the event. The signal processing for each pixel goes vertically down. Each new value (example: orange pixel 1301) is determined based on the three values above (example: blue pixels 1302) and the filter parameter (blue AND 1303). Each pixel has a six-step signal line. There can be three possibilities in a rung: logical OR for a pixel and its neighbors, logical AND for a pixel and its neighbors, and SKIP, which passes the signal without being affected by the neighbors. The logical OR will eliminate the pixels constant zero. Logical AND will eliminate the constant unit and find the center of gravity of events. The first two steps in Fig. 13 have only the AND or OR option, while the last four steps only have the AND or SKIP option. In FIG. 13 shows the initial filter setting to eliminate one erroneous zero (as shown for pixel 6). With one OR, two ANDs are needed to cancel the erroneous units (pixels 16, 23, and 27).

After the above initial setting, there is no 1 in the bottom row. The filter parameters must then be changed (see Fig. 14) until row 6 is completely zero. To do this, line 6 is first changed to SKIP. Since that doesn't help, line 5 is also changed to SKIP. Now row 6 is not all zero, and the center of gravity pixel is in row 6.

A pixel gradient shading can be applied to a touch element. An L-shaped sensor will be rated for a viewing angle of just over 120°. The problem is that the accumulated light energy decreases with the cosine of the incident light from 100% in the middle to 50% at 60°. At 60°, the Sun will have 50% efficiency, but still a higher signal than any other light source, including reflections from the Earth, spacecraft, etc. A possible option would be to compensate for this deviation by covering with metal a part of the corresponding area of the sensitive pixel corresponding to l/(2cos(oc)) of the angle a (to the normal vector of the sensor). If this is done, then the central pixels will be covered by 50% metal, and at ±60° this figure decreases to 0%. In addition to screening, pixels are aligned to provide the most similar dynamic performance.

Such a situation is shown in Fig. 9B. The signal level will decrease towards the ends in accordance with the cosine characteristic. At 60° this is 50%, but still above the maximum reflection from the earth and other natural or artificial light sources. The top line shows sensitivity from different angles. The bottom lines show the maximum albedo strength from the Earth and the Moon at 0° (relative to the Sun at 0°).

As shown in FIG. 9C, at a fixed pixel pitch, resolution will be worst in the middle and improve towards the ends. The provided filtering and combination of location data from three domains will further improve the resolution.

With respect to the functionality of the domain master (ie, block controller), each of the domain masters receives position data from three different sensor elements, which together cover the entire hemisphere. It first decides which one has the strongest signal and chooses that as the probable position of the Sun. It then has to convert the element's local x position to the touch module's global x position. First, the angle is calculated based on the position from the position according to oc=90-arctan((d+Ad)/(L+AL)), where L is the position of the pixel, d is the estimated distance between the sensor and the slotted screen, a (Ad and AL) - received variables. Addition and division must be done in place, while arctan will probably need a lookup table. The angle in the local Y direction is global 0. To do this, each element must know its position in the module. This is provided by a wired input on two contacts. Based on the hardware-derived location information, the angle (X position) is added by default at 0, 120, or 240°. Alternatively, programmable values can be selected to compensate for deviations due to inaccurate mechanical position of the sensor elements, etc. The change in the angle of the substrate can be reasonably (and/or significantly) less than the measurement resolution and, therefore, it can be neglected. ______

Element code Left sensor This sensor Right sensor 00 0° 0° 0° 01 240° 0° 120° 10 0° 120° 240° eleven 120° 240° 0°

All of the above processing takes place in parallel in three completely independent signal and power domains (shown in shading/color in the drawings). This generates three pairs of positions, which may differ due to measurement variations or more severe permanent or timing errors.

The functionality of the module wizard will now be disclosed in connection with FIG. 11. Of the three on- 17-

Claims (15)

of the positions generated by the domain masters, the module master selects the φ average position and the θ average position and sends them to the spacecraft main system. This procedure will filter out wrong position in φ and wrong position in θ. If all of them are correct, then the most accurate position with improved resolution will be generated. The only process the satellite host needs is to know which of the two sensor modules it is receiving data from and compensate for this in the θ direction. This module master plays an important role when it comes to redundancy. Although all three elements (i.e., touch devices) contain this module, only one can send data to the host computer. The module master will be selected from a sequence based on hardware-derived position information. If the module is not powered, then the task will be passed to the next one in the sequence. CLAIM 1. A sensor device for determining the position of a light source, comprising: a plurality of sensory blocks, each sensory block having a corresponding sensory area; and a mask positioned above the plurality of sensor units and configured such that incident light from the light source illuminates different areas of the sensor area of each of the sensor units depending on the position of the light source relative to the sensor device, such that the position of the light source can be determined based on which areas of the sensory area of the sensor blocks are illuminated; wherein each sensor unit is controlled by a respective unit controller to determine the position of the light source, and each sensor unit comprises a first strip and a second strip substantially orthogonal to the first strip, wherein the mask is configured so that the light source illuminates areas of both strips of each sensor unit simultaneously. 2. The sensor device according to claim 1, wherein the sensor units are adjacent to each other. 3. The sensor device of claim 1 or 2, wherein the mask comprises a first transparent slit and a second transparent slit substantially orthogonal to the first transparent slit. 4. The sensor device of claim 3, wherein the first transparent slit is substantially perpendicular to the first sensor block strips and the second transparent slit is substantially perpendicular to the second sensor block strips. 5. A touch device according to any one of the preceding claims, wherein each strip of each sensor unit comprises a plurality of pixels, the pixels of each strip being offset from the pixels of each adjacent strip by a distance less than the width of each pixel in the offset direction. 6. A sensor device according to any one of the preceding claims, comprising gradient shielding to reduce the intensity of light incident on the sensor units to counteract the relative decrease in intensity of light incident on the sensor unit at an angle. 7. A sensor device according to any one of the preceding claims, wherein each sensor unit is configured to be part of a respective power domain. 8. A sensor device according to any one of the preceding claims, wherein each sensor unit is associated with an independent signal domain and associated with an independent power domain. 9. Sensor module for determining the position of the light source, containing: a plurality of touch devices according to any one of claims 1 to 8; and a plurality of block controllers configured to control one sensor block in each of the plurality of sensor devices, each sensor device comprising one of the plurality of block controllers. 10. The sensor module of claim 9, wherein each block controller belongs to a respective power domain. 11. The sensor module according to claim 9 or 10, comprising a plurality of module controllers, each module controller being configured to control each of the plurality of block controllers. 12. A sensor module according to any one of claims 9 to 11, comprising a base and three sensor devices located on respective faces of the base, the base having the shape of at least part of a tetrahedron. 13. A sensor module according to any one of claims 9-12, comprising three sensor devices, each of which is located parallel to the surface plane of the tetrahedron, with one sensor device on each plane facing outward. 14. A sensor module according to any one of claims 9 to 13, wherein the sensor module is a solar sensor for a satellite. 15. A sensor module according to any one of claims 9 to 14, configured to have a field of view for detecting a light source that is at least a hemisphere. -