Method for processing measured values ​​from a sun sensor of a motor vehicle and motor vehicle

Abstract

Method for processing measured values ​​from a sun sensor (1) of a motor vehicle (12) comprising at least one partial sensor, wherein the sun sensor (1) measures the intensity of incident light radiation as measured values, wherein a current geodetic position and orientation of the motor vehicle (12) is determined, and in conjunction with current time information, in particular a current date and time, sun position information (4) describing the position of the sun relative to the motor vehicle (12) is determined, characterized in that the sun sensor (1) has a sensor characteristic (2) which assigns a sensitivity of the sun sensor (1) to each pair of elevation angle and azimuth angle of the sun in relation to the sun sensor (1), in particular for each partial sensor.wherein a current elevation angle and azimuth angle of the sun relative to the sun sensor (1) are determined from the sun position information (4) and the corresponding current sensitivity is determined from the sensor characteristic (2) and used for the correction of the measured values ​​of the sun sensor (1), in particular for sub-sensors, wherein the correction as a correction step (5) comprises a multiplication of the inverse of the sensitivity with a measured value to determine a corrected value, wherein as part of the sun position information (4) a maximum measurable solar power value on Earth is also determined from the time information and / or the current geodetic information and / or the sun position and the corrected value is compared with the solar power value in a diffusivity check.

Description

[0001] The invention relates to a method for processing measured values ​​from a sun sensor of a motor vehicle comprising at least one partial sensor, wherein the sun sensor measures the intensity of incident light radiation as measured values, wherein a current geodetic position and orientation of the motor vehicle is determined, and, in conjunction with current time information, in particular a current date and time, sun position information describing the position of the sun relative to the motor vehicle is determined. The invention also relates to a motor vehicle.

[0002] Motor vehicles typically have climate control systems to adjust the interior temperature to the driver's preferences. Automatic climate control systems are also known, which regulate the climate based on sensor data from various sensors within the vehicle, such as temperature sensors measuring the actual temperature inside and / or outside the vehicle. In this context, it has also been proposed to use so-called solar sensors to measure the intensity of solar radiation, which can influence air volume, air distribution, and air temperature for specific climate zones within the vehicle.For example, if an occupant is located on the side of the vehicle facing the sun, he will feel a higher temperature due to the incident solar radiation, assuming the air conditioning settings are otherwise the same.

[0003] Sun sensors can be positioned, for example, on trim panels in a vehicle and / or in the base of a rearview mirror. However, such installation positions can lead to restrictions in the sun sensors' field of view.

[0004] Various designs of solar sensors have been proposed. A solar sensor typically comprises at least one sub-sensor, in particular a photodiode. With multiple sub-sensors, these are usually oriented differently to obtain information such as the direction of solar radiation. Examples of proposed solar sensors include those with one, two, or three photodiodes. A vehicle control unit, which might be implemented as climate control logic, processes the raw signals from the solar sensor—that is, its measured values—by filtering and / or evaluating the individual measurements. From this, it can determine zone-specific solar values ​​for different climate zones. These values ​​can then serve as input parameters for the climate control system and, for example, influence air volume, air distribution, and / or air temperature within the air conditioning system.

[0005] Besides the positioning and orientation of the sun sensors, a directional characteristic, particularly an optical unit, can also influence the measured values. The use of such a directional characteristic serves to deliberately reduce the sensor sensitivity under certain sun angles relative to the vehicle. This means that without the directional characteristic, the measured values ​​could be higher. As a consequence, the interior would become too cold, at least in some climate zones, which is the case, for example, at an elevation of 90°. In this case, the vehicle occupants would only be partially exposed to solar radiation.

[0006] In summary, the directional characteristics and positioning of the solar sensor limit its field of view and its sensitivity. Compared to the actual global solar load, each sub-sensor of the solar sensor measures a value that depends on the sun's azimuth and elevation. This value may be equal to or less than the global solar load. The relationship between the sun's azimuth and elevation relative to the solar sensor or sub-sensor and the resulting sensitivity is called the sensor characteristic. The sensor characteristic thus assigns a sensitivity value to each relative solar position, i.e., each pair of azimuth and elevation values, for the solar sensor or, more specifically, for each sub-sensor.

[0007] The disadvantage is that, at certain sun angles, the sensor's characteristics are less than necessary due to its design and positioning. This means the sun sensor delivers lower readings than required to maintain a comfortable temperature for the vehicle's occupants in every climate zone. For example, the interior may become too warm in such cases.

[0008] DE 10 2006 029 545 A1 relates to a method and a device for verifying the plausibility of a solar output signal. To ensure the most comfortable climate control in motor vehicles, the use of solar sensors that determine the intensity and direction of incidence of sunlight is proposed. Simultaneously, it is proposed to calculate a solar position signal based on the current vehicle position, the current vehicle direction of travel, and the current date and time. To verify the plausibility of the measured direction of incidence, it is proposed to compare this with the calculated solar position signal. This process can also take into account shading caused by topographical features, in particular buildings, mountains, or the like, which is stored in the vehicle's navigation system.

[0009] DE 101 55 410 C1 relates to a method for controlling the air conditioning system of a vehicle, in which solar radiation is determined indirectly via the outside temperature and the heating inside the vehicle. Furthermore, country-specific programs are set using data providing information about the current location. The proposed method is to determine the intensity of solar radiation entering a vehicle from the absolute position of the sun, the spatial orientation of the vehicle on site, and a measured solar intensity, taking into account the position on the globe as well as the time of day and year. In this way, the position of the sun relative to the vehicle is determined, and thus the intensity of solar radiation entering the vehicle's interior.

[0010] DE 103 32 205 A1 relates to an air conditioning system for a motor vehicle, wherein a device is provided with which, for the current position of the motor vehicle, the position of the sun relative to the motor vehicle can be determined in a first step and, from this, the direction of the solar radiation into the motor vehicle can be determined in a second step. This device is only activated when the ambient brightness detected by the light sensor exceeds a predetermined threshold.

[0011] The invention is based on the objective of providing an improved method for determining the solar radiation on a motor vehicle.

[0012] To solve this problem, a method of the type mentioned above is provided according to the invention in such a way that the sun sensor has a sensor characteristic which assigns a sensitivity of the sun sensor to each pair of elevation angle and azimuth angle of the sun in relation to the sun sensor, in particular for each sub-sensor, wherein a current elevation angle and azimuth angle of the sun to the sun sensor is determined from the sun position information and the corresponding current sensitivity is determined from the sensor characteristic and is used for the correction of the measured values ​​of the sun sensor, in particular for each sub-sensor.

[0013] The present invention is based on the possibility of determining the sun's position relative to the vehicle from its current geodetic position, its orientation, and time information that includes not only the time of day (i.e., the clock) but also the current date. The vehicle's current geodetic position can be determined, in particular, by means of a GNSS sensor (GNSS - Global Navigation Satellite System), especially a GPS sensor. Directional information can be obtained, for example, from a combination of information from the vehicle's compass and inertial sensor. For instance, current position information, including the vehicle's geodetic position and orientation, can already be determined by the vehicle's navigation system and retrieved accordingly.Since the relative movements of the sun and earth are very well known, the position of the sun at the current geodetic position of the vehicle can be determined using generally known methods, so that, together with the orientation information, the sun's position relative to the vehicle can also be determined. It should be noted that, within the scope of the present invention, it is conceivable to also consider the vehicle's elevation orientation and / or its current altitude when determining the sun's position information.

[0014] By combining the sensor characteristics and the sun's position according to the sun position information, it is also possible to determine the value that the sun sensor, or a specific sub-sensor under consideration, would have measured at 100% sensitivity, since, according to the invention, the process is preferably sub-sensor-specific. This can also be referred to as the "global solar load." In other words, within the scope of the present invention, it can be advantageously provided that the correction step comprises multiplying the inverse of the sensitivity by a measured value to determine a corrected value. This means that at certain sun positions, the measured values ​​can be increased to compensate for deficiencies of the sun sensor. The global solar load, and thus the corrected value, can be determined by multiplying the measured values ​​at the determined sun position by the inverse of the corresponding sensitivity from the sensor characteristics.In other words, by combining measured values, sensor characteristics and sun position calculation, improved measured values, at least subject to correction, can be calculated, especially as input variables for climate control, which compensate for the limited visibility of the sun sensors and thus lead to more comfortable indoor climate control.

[0015] It should be noted here that, depending on the specific implementation of the climate control system, the sensor characteristics can also be adjusted to obtain lower values ​​at certain sun positions, for example, because occupants may be shaded by the vehicle's roof. A directional characteristic can be taken into account as desired. However, it is preferable if the climate control system also has knowledge of the current sun position and can take into account corresponding shading of the occupants, for example, based on a vehicle model. In that case, the aforementioned "global solar loads" can generally be used as input variables for the climate control system.

[0016] In the context of the present invention, the partial sensors are in particular photodiodes, whereby, for example, a sun sensor with two or three photodiodes can be used.

[0017] In this context, it is important to note that the described correction step, which involves multiplying by the inverse of the sensitivity, is only correct in clear sunshine, i.e., with correspondingly directional solar radiation. During normal vehicle operation, diffuse lighting conditions can also occur, such as cloud cover, fog, and the like. In this case, there is no clearly directional solar radiation; this means that the calculated sun position, specifically described by the azimuth and elevation angles, does not correspond to the actual prevailing radiation distribution. In particular, correction calculations based on sensor characteristics, sun position, and measured values ​​can, at least partially, lead to corrected readings that are higher than necessary, potentially causing the climate control system to operate the vehicle too cold.Therefore, a further correction of the measured values ​​is appropriate in this case, for which it is necessary to recognize that diffuse lighting conditions are present.

[0018] Therefore, a particularly advantageous embodiment of the present invention proposes that, as part of the solar position information, a maximum measurable solar power value on Earth is also determined from the time information and / or the current geodetic information and / or the solar position, and that the corrected measured value is compared with the solar power value in a diffusion check, whereby, in particular, an exceedance of the solar power value by the corrected measured value is used as an indication of the presence of diffuse lighting conditions. It should first be noted that the first correction step already described is always particularly useful and therefore must be carried out in every case when the solar sensor, or specifically the sub-sensor, has low sensitivity. If diffuse light is present, more components from other directions are added, which could also be measured more accurately.According to the invention, it has now been recognized that multiplying by the sensitivity in such cases can lead to corrected measured values ​​that would be greater than the maximum measurable intensity value under these circumstances. A comparison between the solar power value and the corrected measured value can thus be seen as a kind of plausibility check, the failure of which, however, does not indicate a measurement error but rather the presence of diffuse measurement conditions if the corrected measured value is greater than the maximum possible solar power value. The diffuseness check can be carried out at least for one sub-sensor with a currently low sensitivity, but preferably for every sub-sensor. It may then be sufficient to detect diffuse light conditions if a sub-sensor, in particular, as will be discussed in more detail later, is used for a certain period of time or…Particularly often, the corrected measurement exceeds the solar power value, possibly with a predefined tolerance. It is especially important to note that, for example, with sub-sensors measuring with high sensitivity in the direction of the actual sun position, diffuse light conditions can lead to significantly lower measured or corrected values ​​than the solar power value.

[0019] In a specific embodiment of the present invention, it can be provided that for each time step, in particular each recorded measurement, a comparative result value is determined as a function of the deviation of the corrected measurement value from the solar power value, based on which the presence of diffuse light conditions is determined. It is preferred that if the corrected measurement value exceeds the solar power value, optionally taking into account a tolerance margin, a comparative result value of 1 is assigned; otherwise, a value of 0 is assigned.The trend of the comparison result value can be evaluated to determine the presence of diffuse light conditions, since it has been shown that, due to the extremely short time steps of modern sensors, for example, short-term shading by a tree or the like can already lead to extremely short-term, diffuse light conditions, which, however, are not relevant for climate control due to their short duration.

[0020] A particularly advantageous further development therefore involves calculating an average value for the comparative result over a moving time window spanning several time steps. The presence or absence of diffuse lighting conditions is then determined by comparing this average against a threshold value. For example, a moving time window encompassing 50 to 1000 time steps can be used. If, as mentioned above, the comparative result value in the individual decision (i.e., the individual comparison) is 1 for diffuse and 0 for non-diffused, a threshold value of, for example, 0.3 to 0.6 can be used to detect diffuse lighting conditions.

[0021] Furthermore, it is particularly advantageous that, in the case of diffuse light conditions identified by the diffusion test, a further correction step is applied to the corrected measurement to obtain a further corrected measurement. This further correction step can include an empirically determined correction. This means that typical deviation scenarios are measured and a corresponding correction formula is defined for the further correction step. It is particularly advantageous if the further correction step depends on a ratio of the corrected measurement to the solar power value. In other words, a further correction can be made depending on the ratio of diffuse and directional components, so that overall a proportional correction of the sensor raw values, i.e., the measured values, is carried out using solar position information and sensor characteristics.In other words, the further correction step, which can of course also be a combination of the first and subsequent correction steps, prevents the correction from yielding excessively high measured values. It has thus been recognized that, depending on the ratio between directional and diffuse radiation, it may be necessary to make no corrections to the measured solar intensities, or only partial corrections, to create a comfortable climate inside the vehicle.

[0022] In summary, it can be said that simply correcting for diffuse lighting conditions using sun position information and sensor characteristics has the disadvantage that it can lead to overly high measured values. Consequently, the indoor temperature would become too cold. An additional diffusion check, which anticipates diffuse lighting conditions, prevents this disadvantage by generating and using appropriately corrected measured values.

[0023] It should be noted here that the maximum possible solar power value can, of course, be determined in various ways, with the current altitude of the vehicle being a preferred method for determining it. In principle, the solar power value can be determined from a lookup table and / or a characteristic map, which can be derived, for example, through empirical measurements on the Earth's surface and / or corresponding physical models. It is also conceivable that the solar power value can be determined using a mathematical relationship, as scientific studies already exist that address the topic of solar irradiance at various locations on the Earth's surface.However, a simple approach is preferred according to the invention, since it has also been shown that the exceedances are usually sufficiently clear under diffuse lighting conditions, so that extremely high accuracy of the maximum possible solar power value is not required. In a specific embodiment, for example, it is conceivable to use only the sun's position and altitude to derive a maximum possible solar power value, particularly from a look-up table and / or a characteristic curve.

[0024] In general, it can be advantageous to determine the presence of diffuse lighting conditions, particularly as an additional step, by evaluating camera images and / or sensor data from a light sensor associated with the vehicle's lighting system. While, for example, clear, sunny weather is easily distinguishable from images of diffuse lighting conditions in camera images, using known evaluation algorithms, a light sensor typically provides an absolute illuminance value that accurately describes the overall brightness, which is usually reduced in diffuse lighting conditions. However, within the scope of the present invention, it is preferred to perform the plausibility check based on a comparison with the solar power value, with the additional checks described here optionally being performed as supplementary, and thus supporting and / or plausible.

[0025] As already explained, the corrected and / or further corrected measured values ​​can be particularly useful for adjusting the operation of a motor vehicle's air conditioning system. In particular, the corrected and / or further corrected measured values ​​can represent input variables for a climate control system of the motor vehicle, which is implemented, for example, by a control unit of the air conditioning system. This control unit may also incorporate a correction device designed to carry out the method according to the invention. A functional unit for climate control can also be referred to as a climate controller. In this case, the corrected and / or further corrected measured values ​​thus form input variables for the climate controller.

[0026] In addition to the method, the present invention also relates to a motor vehicle comprising at least one sun sensor, an air conditioning unit utilizing measured values ​​from the sun sensor, and a correction device designed to carry out a method according to the invention. All aspects relating to the method according to the invention can be applied analogously to the motor vehicle according to the invention, with which the aforementioned advantages can therefore also be obtained.

[0027] Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings. These show: Fig. 1 a block diagram illustrating the process of an exemplary embodiment of the method according to the invention, Fig. 2 an exemplary representation of a sensor characteristic, Fig. 3 a time course of a comparison result value, and Fig. 4 a schematic diagram of a motor vehicle according to the invention.

[0028] An embodiment of the method according to the invention is explained in more detail below. This relates to the corrective post-processing of measured values ​​from a sun sensor 1. The sun sensor 1 is installed inside a motor vehicle and, in this case, has two photodiodes as sub-sensors, which can be considered, for example, as a first and a second channel and each provide a measured value for each time step that describes the intensity of the solar radiation. The sub-sensors can, for example, measure in the infrared range. Due to its design and installation inside the motor vehicle, the sun sensor 1 has a sensor characteristic 2, meaning that under certain azimuth and elevation angles of the sun to the motor vehicle and thus to the sun sensor, the respective sub-sensors exhibit certain sensitivities that can differ significantly from 100%.An exemplary sensor characteristic for one of the photodiodes is shown in the 3D graph of the . Fig. 2, in which the sensitivity (S) in percent is plotted against the elevation angle E in degrees and the azimuth angle A in degrees. A comparable partial characteristic exists for the second sub-sensor, both of which are stored in sensor characteristic 2.

[0029] In order to make a meaningful correction to the measured values ​​of the sub-sensors of sun sensor 1, it is necessary to determine the current position of the sun relative to sun sensor 1. For this purpose, in step S3, sun position information 4 is determined, which includes at least a current azimuth angle and a current elevation angle of the sun to the vehicle and thus to sun sensor 1, i.e. the sun's position relative to sun sensor 1, but also a maximum possible solar power value.In step S3, the current geodetic position of the vehicle, its current orientation (which can be obtained as position information from the vehicle's navigation system and may be determined, for example, using a GPS sensor and a compass / inertial sensor), and time information, specifically the current date and time, are used to determine the current position of the sun relative to the vehicle. Simultaneously, the maximum possible solar power value is determined, taking into account all these input variables, including the vehicle's current altitude. Lookup tables, characteristic curves, and / or mathematical relationships can be used for both calculations.

[0030] The respective current measured values ​​of the sun sensor 1, the sensor characteristic 2, and the sun position information 4, specifically its position, are now used in a first correction step 5 to determine the first corrected measured values. For this purpose, the azimuth angle and elevation angle resulting from the sun position are first used to read the sensitivities for the two sub-sensors from the sensor characteristic 2. These sensitivities are then used in the first correction step 5 to determine the first corrected measured values ​​by multiplying the respective currently measured value by the reciprocal of the respective sensitivity.

[0031] However, since diffuse lighting conditions can also lead to significantly higher initial corrected measurements, a diffusion check is performed in step 6. To enable this, a size of a sliding time window, specifically a number of time steps, is defined. In each time step, it is checked whether the initial corrected measurement is greater than the maximum possible solar power value, possibly including a tolerance margin. If this is the case, a comparison result value of 1 is set for this time step and the corresponding sub-sensor; otherwise, a comparison result value of 0 is set. This is shown in the graph of the Fig. Figure 3 shows in more detail where the comparison result value is plotted against time. It is evident that initially, in the first time range 7, time steps in which the first corrected measurement is greater than the solar power value, and thus a comparison result value of 1, occur only rarely. However, this occurs more frequently in time range 8. Furthermore, the trend curve 9 shows the average of the comparison result value calculated over the moving time window ending at the current time step, which clearly assumes higher values ​​in the second time range.

[0032] A threshold value is now defined for this moving average, which can be in the range of 0.3 to 0.6, for example, and if this threshold is exceeded in step 6, it is determined that diffuse lighting conditions are present.

[0033] In diffuse lighting conditions, a second correction step (10) is performed, in which the measured values ​​are further corrected. This second correction step is empirically determined and may depend on the ratio of the first corrected measurement value to the solar power value. This results in further corrected measurements, known as the second corrected measurements. These are typically corrected downwards, as diffuse lighting conditions can lead to excessive light irradiance despite low sensitivity.

[0034] If no diffuse light conditions are detected in step 6, the process proceeds directly to step 11. In step 11, the first or second corrected measured values ​​are provided as input variables for a climate control system of the vehicle's air conditioning unit, so that, for example, in air conditioning zones of the vehicle where there is strong sunlight, corresponding adjustments to air conditioning parameters, such as air distribution and / or air temperature, can be made.

[0035] Fig.Figure 4 shows a schematic diagram of a motor vehicle 12 according to the invention. In addition to the sun sensor 1, this vehicle has an air conditioning unit 13 (air conditioning system), the operation of which is controlled by a control unit 14. The control unit 14 has, in addition to a climate controller 15, a correction device 16, which is configured to carry out the method according to the invention. Besides the measured values ​​from the sun sensor 1, the correction device 16 can, for example, receive time and position information from a navigation system 17 of the motor vehicle 12. The first and second corrected measured values ​​are provided as input variables to the climate controller 15, which operates the climate control system. The climate controller 15 can, of course, also receive other input variables, for example, from temperature sensors not shown in detail here.

Claims

[1] Method for processing measured values ​​of a sun sensor (1) comprising at least one partial sensor of a motor vehicle (12), wherein the sun sensor (1) measures an intensity of incident light radiation as measured values, wherein a current geodetic position and orientation of the motor vehicle (12) is determined and, in conjunction with current time information, in particular a current date and time, sun position information (4) describing the position of the sun relative to the motor vehicle (12) is determined, characterized by, that the sun sensor (1) has a sensor characteristic (2) which assigns a sensitivity of the sun sensor (1) to each pair of elevation angle and azimuth angle of the sun relative to the sun sensor (1), in particular for each sub-sensor, wherein a current elevation angle and azimuth angle of the sun relative to the sun sensor (1) is determined from the sun position information (4) and the corresponding current sensitivity is determined from the sensor characteristic (2) and is used for the correction of the measured values ​​of the sun sensor (1), in particular for the sub-sensor, wherein the correction as a correction step (5) comprises a multiplication of the inverse of the sensitivity with a measured value to determine a corrected value,wherein as part of the solar position information (4) a maximum measurable solar power value on Earth is also determined from the time information and / or the current geodetic information and / or the solar position and the corrected measured value is compared with the solar power value in a diffusion check. [2] Method according to claim 1, characterized by that the diffusivity check is performed at least for one sub-sensor with a currently low sensitivity, in particular for each sub-sensor. [3] Method according to claim 1 or 2, characterized by , that for each time step, in particular each recorded measurement, a comparison result value is determined depending on the deviation of the corrected measurement value from the solar power value, depending on which the presence of diffuse light conditions is determined. [4] Method according to claim 3, characterized by, that for the comparison result value an average value is determined over a moving time window encompassing several time steps, whereby the presence or absence of diffuse light conditions is determined by a threshold comparison of the average value. [5] Method according to any of the preceding claims, characterized by , that if diffuse light conditions are found to be present by the diffusivity check, a further correction step (10) is applied to the corrected measurement to obtain a further corrected measurement. [6] Method according to claim 5, characterized by , that the further correction step (10) includes an empirically determined correction and / or is dependent on a ratio of the corrected measurement value to the solar power value. [7] Method according to any of the preceding claims, characterized by, that the solar power value is determined taking into account a current altitude of the motor vehicle (12) and / or from a look-up table and / or a characteristic map and / or using a mathematical relationship. [8] Method according to any of the preceding claims, characterized by , that in order to determine whether diffuse light conditions exist, in particular additionally an evaluation of camera images from a camera and / or sensor data from a light sensor associated with a lighting system of the motor vehicle (12) is carried out. [9] Method according to any of the preceding claims, characterized by , that the corrected and / or further corrected measured values ​​are used to adjust the operation of an air conditioning unit (13) of the motor vehicle (12). [10] Motor vehicle (12) comprising at least one sun sensor (1), an air conditioning device (13) utilizing measured values ​​from the sun sensor (1) and a correction device (16) designed to carry out a method according to one of the preceding claims.

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