Patent Publication Number: US-2021164809-A1

Title: Sensor device, control system and method of communication between a sensor device and a control system

Description:
FIELD 
     This application relates generally to the communication between a sensor device and a control system, for example corresponding sensor devices, control systems and methods. 
     BACKGROUND 
     Sensor devices are generally used to detect one or more physical quantities. In some applications, signals from such control devices, which carry the measured physical quantity or quantities as information, are then transmitted to a control system. This control system can then control an associated device in accordance with the detected physical quantity or the detected physical quantities. 
     One example of these are electric motors, for example in vehicles. In such electric motors, in some systems, an angle sensing device can be used to detect an angular position and/or angular speed of the electric motor and transmit them to the control system. The control system then drives the electric motor depending on the angular position and/or angular speed detected, for example by supplying appropriate current to the windings of the electric motor. 
     Common interfaces used to transfer signals from a sensor device to a control system include an incremental interface (IIF), which is also known as an encoder interface or ABZ interface. With this interface, angle information is transmitted incrementally. 
     During a revolution no angular position is indicated, only a corresponding item of information in a predefined zero position is sent instead. Otherwise, the angular position is determined essentially by counting pulses or edges of the received signals, each of which indicates an incremental angular change. 
     Another interface used for such applications is the so-called UVW interface, also known as a “Hall Switch Mode” interface. This interface generally has a lower resolution than the IIF interface. 
     Both interfaces have in common that only angle information is transferred. Furthermore, the integrity of the transmission cannot be verified. 
     SUMMARY 
     A sensor device as claimed in claim  1 , a control system as claimed in claim  13  and a method as claimed in claim  29  are provided. The sub-claims define further embodiments. 
     According to one exemplary embodiment, a sensor device is provided, including: 
     a first interface, wherein the sensor device is configured to transmit sensor data via the first interface, and 
     a second interface, wherein the sensor device is configured to transmit redundant sensor data and/or additional data via the second interface. 
     According to another exemplary embodiment, a control system is provided, including: 
     a first interface for receiving sensor data from a sensor device, and 
     a second interface for receiving redundant sensor data and/or additional data from the sensor device. 
     According to another exemplary embodiment, a method of communication between a sensor device and a control system is provided, including: 
     transmitting sensor data from the sensor device to the control system via respective first interfaces of the sensor device and the control system, and 
     transmitting redundant sensor data and/or other data from the sensor device to the control system via a respective second interface of the sensor device and the control system. 
     The above brief summary is only intended as a short overview of some exemplary embodiments and is not to be interpreted as limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a block diagram of a system according to one exemplary embodiment. 
         FIG. 2  shows a flowchart illustrating a method in accordance with various exemplary embodiments. 
         FIG. 3  shows a block diagram of a system according to one exemplary embodiment. 
         FIG. 4  shows a data transmission via an IIF interface. 
         FIG. 5  shows a data transmission via a UVW interface. 
         FIG. 6A  shows a data transmission via an SPC-based interface. 
         FIG. 6B  shows examples of the data transmission of  FIG. 6A  for various master-trigger signals. 
         FIG. 7  shows a block diagram of a system according to one exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, various exemplary embodiments are explained in detail. These exemplary embodiments are intended for illustration purposes only and should not be construed as limiting. For example, in other exemplary embodiments, some of the features represented (e.g. elements or components) may be omitted or replaced by alternative features. In addition to the features explicitly described, other features can also be provided. For example, the following examples refer mainly to the communication between a sensor device and a control system. Other parts of sensor devices and control systems can be implemented in a conventional way and are therefore not explained in detail. 
     Connections or couplings between different components or elements refer to electrical connections or couplings, unless otherwise specified. Such connections or couplings can be modified, for example by adding elements or by omitting elements, provided the basic function of the connection or coupling, for example the transmission of a signal, the transmission of information, the provision of a voltage or a current and the like, is essentially preserved. 
     Features of different exemplary embodiments can be combined to form additional exemplary embodiments. Variations, additional features or details of features described for one of the exemplary embodiments can also be applied to other exemplary embodiments and are therefore not explained twice. 
       FIG. 1  shows a block diagram of a system according to one exemplary embodiment. The system of  FIG. 1  has a sensor device  10  and a control system  11 . A sensor device is generally understood to be a device which comprises one or more sensors in order to detect one or more physical quantities. For example, the sensor device  10  can be designed as an angle sensor device to detect a rotation angle or an angular speed of a rotary element, such as a shaft. For this purpose, the sensor device may have, for example, one or more magnetic field sensors such as Hall sensors, or sensors based on magnetoresistive effects (xMR sensors). A magnet device can then be attached to a rotating element, which under rotation generates a modulated magnetic field that is detected by the magnetic field sensor or the magnetic field sensors. In other embodiments, a linear motion can be detected in a similar way by attaching a magnet device to a linearly moving element. Additionally, or alternatively, the sensor device  10  may comprise other types of sensors such as voltage sensors, current sensors, temperature sensors, pressure sensors and the like. There may also be different types of sensors present in the sensor device  10 . In cases where the sensor device  10  acts as an angle sensor device, for example, a temperature sensor may also be provided. These sensors can be implemented in any conventional manner. 
     In addition, the sensor device  10  can comprise a processing circuit for processing signals from the sensor or sensors. Such processing circuits can be, for example, filters, analog-to-digital converters and the like. Such processing circuits can also be implemented in any conventional manner and therefore will not be explained in detail. 
     The sensor device  10  also has a first interface  12  and a second interface  13 . The sensor device  10  is configured to send sensor data via the first interface  12 . Sensor data here refers to data that is representative of the physical quantities detected by the sensor or the sensors, possibly processed by the processing circuit mentioned above. The first interface  12  can have a high resolution and/or data rate compared to the second interface  13  discussed below, in order to transmit the sensor data with high temporal resolution. In the case of angle sensors, for example, the first interface  12  can be an IIF interface or a UVW interface as mentioned above. Such interfaces are explained in more detail below. For example, the IIF interface typically has a resolution of 12 bits, corresponding to 4096 pulses per revolution. For other types of sensors, other relevant interfaces, which are conventionally used to transmit sensor data for corresponding sensors, can be used as the first interface  12 . 
     In some exemplary embodiments, the second interface  13  has a lower data rate than the first interface. In some exemplary embodiments, the second interface  13  is a single-wire interface that requires only a single conductor, in contrast to the IIF or UVW interfaces mentioned above, which usually work with three wires. The second interface  13  can be a digital interface. The second interface can be an interface which allows the integrity of the transmitted data to be verified, for example with a checksum such as a CRC (Cyclic Redundancy Check). Verifying the integrity of the data means that errors in the data caused by the transmission (e.g. due to noise) can be detected and, in some implementations, even corrected. Data items such as checksums, which enable the integrity of transmitted data to be verified, are referred to in the context of this application as integrity information. 
     In some exemplary embodiments, the sensor device  10  is configured to send redundant sensor data via the second interface  13 , in other words sensor data that provide redundant information about the sensor data sent via the first interface  12 . This can contribute to satisfying security requirements. In some exemplary embodiments, the second interface  13  can also be used to transmit diagnostic data or additional sensor data from other sensors, such as the above-mentioned temperature sensor in an angle sensor device. 
     In some exemplary embodiments, this transmission can be carried out at the request of the control system  11 . In this case, the sensor device  10  receives a request to send certain data via the second interface  13  and sends this data in response to the request. In such an approach, in the case of redundant sensor data the request can be used to specify the time of transmission of the redundant sensor data, which facilitates a comparison of the sensor data sent via the first interface  12  with the sensor data sent via the second interface  13 . 
     In some exemplary embodiments, the second interface  13  may comprise an edge-based pulse-width modulated protocol, in particular a bidirectional protocol. Such protocols use pulse-width modulated pulses, wherein edges of the pulses are detected and the pulse width of the pulses depends on the data to be sent. An example of such a protocol is the SPC protocol (Short PWM Code Protocol). The SPC protocol is based on the SENT protocol (Single Edge Nibble Transmission). 
     Examples of the variants for the second interface described above are explained in more detail below. 
     The sensor device  11  also has a first interface  14  and a second interface  15 . The first interface  14  is connected to the first interface  12  and designed identically to the first interface  12 . This means that the first interface  14  is configured to receive data from the first interface  12 , so that communication is enabled via the first interfaces  12  and  14 . The second interface  15  is connected to the second interface  13  and is designed identically to the second interface  13 , in order to enable a corresponding communication here also. The above descriptions of the first interface  12  and the second interface  13  of the sensor device  10  also apply correspondingly to the first interface  14  and the second interface  15  of the control system  11 . 
     Apart from providing the two interfaces  14 ,  15 , the control system can be implemented in a conventional manner, for example by means of a microcontroller, an electronic control unit (ECU), for example in a vehicle, by means of a multi-purpose processor (GPU; General Processing Unit), by means of an application-specific integrated circuit (ASIC), and the like. 
     The control system  11  receives sensor data from the  10  sensor device via the first interface  14  and receives redundant data and/or other data, such as diagnostic data or other sensor data, from the sensor device  10  via the second interface  15 . In addition, in some exemplary embodiments the control system  11  can send the above-mentioned requests to the sensor device  10 . In some exemplary embodiments, control and/or configuration information can also be sent from the control system  11  to the sensor device  10  via the second interface. 
     Depending on the sensor data received, the control system  11  can control another device (not shown in  FIG. 1 ) via a third interface  16 . For example, in the case of an angle sensor device  10 , an angle of rotation of an electric motor can be detected, and the control system  11  can then control the electric motor accordingly via the third interface  16 . 
       FIG. 2  shows a flow chart illustrating methods in accordance with several exemplary embodiments. The method of  FIG. 2 , for example, can be used in the system of  FIG. 1  or systems described in more detail hereafter. To avoid repetition, the method of  FIG. 2  will be explained by referring to the above explanations for  FIG. 1 . 
     At  20 , the method comprises transmitting sensor data between a sensor device and a control system via the respective first interfaces, for example the first interfaces  12  and  14  of  FIG. 1 . The different variants that were explained for this by referring to  FIG. 1  also apply in a corresponding way to the transmission in  20  of  FIG. 2 , for example, the possible implementations of the first interfaces. 
     At  21 , the method comprises transmitting redundant sensor data and/or additional data between the sensor device and the control system via second interfaces, for example the second interfaces  13  and  15  of  FIG. 1 . The different variants for this purpose discussed by referring to  FIG. 1  apply in a corresponding way to the transmission in  21  of  FIG. 2 . It should be noted that the transmission at  20  and the transmission at  21  can take place essentially simultaneously, that is, via the first and second interfaces in parallel, so that the sequence shown in  FIG. 2  is not to be interpreted as limiting. 
     In the following, various possible details for such a transmission by means of a first interface and a second interface will now be described in more detail, referring to  FIGS. 2-6 . These details and variants can be applied to the system of  FIG. 1  and the method of  FIG. 2  accordingly and also combined with each other. 
       FIG. 3  shows a system in accordance with another exemplary embodiment. The system of  FIG. 3  comprises a sensor device  30  and a control system  31 . The control system  31  is designed as a microcontroller. Unless otherwise specified in the following description of  FIG. 3 , the description of the sensor device  10  of  FIG. 1  and the control system  11  of  FIG. 1  is also applicable to the sensor device  30  of  FIG. 3  or the control system  31  of  FIG. 3 . For example, as described for the sensor device  10 , the sensor device  30  may comprise one or more sensors and, where appropriate, a processing circuit, and the control system  31  may be used to control a further device based on signals from the sensor device  32 . 
     The sensor device  30  in the exemplary embodiment of  FIG. 3  is supplied with a positive supply voltage, for example 5 V, which is coupled with a corresponding supply voltage terminal  32 . In addition, the sensor device  30  is connected to ground at a ground connection  35 . 
     Similarly, the control system  31  is also supplied with a positive supply voltage, such as 5 V, at a supply voltage terminal  36  and is connected to ground at a ground connection  39 . 
     The sensor device  30  in the exemplary embodiment of  FIG. 3  is an angle sensor device that measures an angle of rotation or angular speed of a rotary element, which as the first interface has an IIF interface with terminals labeled A, B, and Z, as is standard for IIF interfaces. Signals from the IIF interface  33  are received by the control system  31  at an interface  37 . This can be formed, for example, by a generic timer module (GTM), as is found in various conventional microcontrollers. 
     As the second interface, the sensor device  30  has an SPC-based interface  34 , which communicates with a corresponding SPC interface  38  of the control system  31  by means of a terminal, e.g. pins, labeled IFB via a single line. 
     Examples of the communication via the IIF interface  33  (or the corresponding interface  37  of the control system  31 ) and via the SPC-based interfaces  34 ,  38  will now be described with reference to  FIGS. 4 to 6 . 
       FIG. 4  shows an example of a communication via the IIF interface. Here, two signals phase-offset by 90° are output on the terminals labeled A and B, and the direction of the phase difference between these signals indicates the direction of rotation of the rotary element (+90° for a clockwise rotation and −90° for a counter-clockwise rotation). The frequency of the pulses is proportional to the angular speed of the rotating element. For example, the frequency of the pulses can correspond to a frequency of zero-crossings measured by a magnetic field sensor when a magnet device is used which is attached to a shaft or other rotating element, such as a pole wheel or a toothed wheel. A pulse is output at the terminal labeled Z when the rotary element is in a predefined 0° position. The drawing in  FIG. 4  corresponds to the conventional communication via an IIF interface of this kind and will therefore not be explained in more detail. This enables the transmission of the angle information with a high data rate, wherein between individual 0° pulses the angular position is determined by means of appropriate integration over the pulses, since each pulse corresponds to a certain incremental angle of rotation. 
     A UVW interface with three lines H1, H2 and H3 can also be used as an alternative to the IIF interface. In this case, three phase-shifted pulses are used, also in a conventional manner, to transmit the angle information acquired by the sensor device. The data rate is generally lower than with the IIF interface. 
     Next, an example of communication via the SPC interfaces  34 ,  38  of  FIG. 3  will be explained.  FIG. 6A  shows a general frame format of a communication, and  FIG. 6B  then shows examples of this. 
     In the case of an SPC interface, the communication is triggered by a master trigger pulse  60 , as is standard in SPC communication. In the case of  FIG. 3  this is sent from the control system  31  to the sensor device  30  and is a pulse of a specific length, wherein, as explained below, a plurality of different lengths are possible. The sensor device responds to this master trigger pulse  60  with a response, which in the example of  FIG. 6 a    consists of a total of seven 4-bit values. Each 4-bit value is encoded in a pulse (also called a “nibble”). A time between two edges of successive pulses determines the bit value, i.e. here there are 2 4 =16 different possible intervals. It should be noted that the number of seven values, each of which encodes 4 bits, may be chosen differently in other edge-based pulse-width modulation protocols. 
     In a first exemplary embodiment, the first 4 bits (reference sign  61 ) are diagnostic bits which can represent 16 different values that are sent to each data frame. These can comprise, for example, a sensor fault, a power-up fault, a sensor device reset, or the like. They can also comprise a counter, or they can also transmit additional values such as a temperature value, distributed across multiple data frames, for example, or with a resolution of 4 bits. 
     The next three 4-bit values, labeled with reference sign  62 , are used to transmit angle information, which is an example of redundant sensor data. The next two 4-bit values, labeled with reference sign  63 , can be used in variable ways, as will be explained by reference to  FIG. 6B . The last 4-bit value  64  contains a CRC checksum. This CRC checksum allows the control system  31  to verify the integrity of the received data. 
     The angle information, which is encoded in the 4-bit values  62 , can be in particular absolute angle information, in contrast to the incremental information in which a 0° position is indicated only once per revolution, as is used with the IIF interface (see  FIG. 3 ). 
     Such absolute angle information can be provided, for example, by integration directly in the sensor device. 
     The master trigger pulse  60  can be used to select different types of data for transmission in the variably used 4-bit values  63 . This will be explained by reference to  FIG. 6B . 
     Different lengths of trigger pulses are used to request different responses from the sensor device  30 . Conventionally, in the SPC protocol these different master trigger pulse lengths are used in the so-called bus mode in order to address different bus nodes, for example different sensor devices connected to a common bus. In this case, they represent an addressing of different bus nodes. In the exemplary embodiment of  FIG. 6 b   , different master trigger pulse lengths are used instead to request different responses from the sensor device. To illustrate this, three examples of responses to different master trigger pulses are shown, labeled as Mastertrigger #1, Mastertrigger #2, and Mastertrigger #3. The 4-bit values  61 ,  62  and  64  are the same in all cases, with the 4-bit values used for the angle information  62  in the example of  FIG. 6B  being used to transmit an absolute angle. 
     The variably usable 4-bit values  63  are used in response to the master trigger pulse Mastertrigger #1 to transmit an 8-bit temperature information item obtained from a temperature sensor of the sensor device. If a temperature is also transmitted with the diagnostic bits (4-bit value  61 ), then a temperature transmission with a higher resolution is possible. 
     In the case of the master trigger pulse Mastertrigger #2, the variable-use bits  63  are used for extended diagnostic information. Such extended diagnostic information can include, for example, plausibility data, data on various components of the sensor device, such as an analog-to-digital converter, EEPROM, UV/OV or EEPROM information. For example, the extended diagnostic information can indicate the component in which a fault has occurred, and/or a cause of the fault. 
     In the third master trigger pulse Mastertrigger #3, the variable 4-bit values  63  are omitted, and the CRC checksum is directly appended to the 4-bit values  62  used for the angle information. 
     Thus, a selection can be made between different information by a control system using different master trigger pulses. 
     In all of the options shown in  FIGS. 6A and 6B , redundant sensor data, in this case angle information, is sent in response to a trigger pulse. In this way, by way of the trigger pulse the control system can also define a time for the redundant sensor data, since in the case of the SPC protocol, for example, these data are essentially sent immediately after the trigger pulse. This makes it easier in some exemplary embodiments to compare the redundant sensor data with the sensor data received via the first interface in the control system (e.g. control system  31 ). In particular, sensor data and redundant sensor data can be compared for the same point in time. In particular, with digital interfaces such as the SPC interface, such a use of trigger pulses thus allows a temporal coordination with the first interface, in this case the IIF interface. 
     In other exemplary embodiments, a SENT interface (Single Edge Nibble Transmission) can also be used, wherein the above described trigger function is not provided here, but a transmission with a checksum, in particular a CRC checksum, of redundant data is nevertheless possible. 
     During transmission, for example, the redundant sensor data can also be used for a “calibration” of the sensor data received via the first interface, for example in some exemplary embodiments involving during a slow motion. Thus, using the absolute angle information from the redundant sensor data of  FIG. 6B  a new starting point for the integration can be set based on the pulses without having to wait for the next 0° pulse, for example, on the “Z” line of  FIG. 4 . 
     As mentioned above, control systems and sensor devices can be used, for example, to control electric motors as explained above. Such an application example is shown in  FIG. 7 . However, this should not be interpreted as limiting, and sensor devices as described here may also be used for other applications. 
     The system of  FIG. 7  comprises a control system  70 , a driver circuit  71 , a magnet-based synchronous motor  72 , a current sensor  73  and a sensor device  74 . The sensor device  74  is designed as an angle sensor device and can be implemented in the same way as the sensor device  30  of  FIG. 3 . In particular, it can transmit sensor data via an IIF interface and other data via an SPC interface. The control system  70  is implemented as a microcontroller and can communicate with the sensor device  74  by means of an interface  76 , which corresponds to the interface  37  of  FIG. 3 , and via an SPC interface  77 , which corresponds to the interface  38  of  FIG. 3 , as explained above. Furthermore, the control system  70  has an analog-to-digital converter input  75 , via which it receives a current measured by the current sensor  73 . 
     The sensor device  74  is used to measure a rotation angle of the motor  72 . The synchronous motor  72  is supplied with a current (for example, in three current phases) via the driver circuit  71 , which is detected via the current sensor  73 . Based on the detected current and the angle of rotation detected by the sensor device  74 , the control system  70  controls the driver circuit  71  with a pulse-width modulated signal PWM to control the motor  72 . This control can be carried out in any known manner. By providing, for example, redundant sensor data via the SPC interfaces, safety can be increased as described. 
     Some exemplary embodiments are defined by the following examples: 
     Example 1. Sensor device, comprising: 
     a first interface, wherein the sensor device is configured to transmit sensor data via the first interface, and 
     a second interface, wherein the sensor device is configured to transmit redundant sensor data and/or additional data via the second interface. 
     Example 2. The sensor device according to example 1, wherein the second interface is a single-wire interface. 
     Example 3. The sensor device according to example 1 or 2, wherein the sensor device is configured to communicate via the second interface on the basis of an edge-based pulse-width modulation protocol. 
     Example 4. The sensor device according to example 3, wherein the edge-based pulse-width modulation protocol is based on the short pulse width modulation code, SPC, protocol. 
     Example 5. The sensor device according to any one of examples 1 to 4, wherein the sensor device is configured to receive a request via the second interface and to send the redundant sensor data and/or the additional data in response to the request. 
     Example 6. The sensor device according to example 5, wherein the request specifies which data of the redundant sensor data and/or the additional data are sent. 
     Example 7. The sensor device according to example 6, wherein the redundant sensor data are always sent and wherein the request selects a type of the additional data. 
     Example 8. The sensor device according to any one of examples 1 to 7, wherein the sensor device comprises an angle sensor device, wherein the sensor data indicate an incremental angular position and the redundant sensor data indicate an absolute angular position. 
     Example 9. The sensor device according to any one of examples 1 to 8, wherein the first interface comprises an incremental interface, IIF, or a UVW interface. 
     Example 10. The sensor device according to any one of examples 1 to 9, wherein the sensor device is configured to transmit the redundant sensor data and/or the additional data together with integrity information via the second interface. 
     Example 11. The sensor device according to example 10, wherein the integrity information comprises a CRC checksum. 
     Example 12. The sensor device according to any one of examples 1 to 11, wherein the additional data comprise diagnostic data and/or additional sensor data from a different sensor than the sensor data. 
     Example 13. A control system, comprising: 
     a first interface for receiving sensor data from a sensor device, and 
     a second interface for receiving redundant sensor data and/or additional data from the sensor device. 
     Example 14. The control system according to example 13, wherein the second interface is a single-wire interface. 
     Example 15. The control system according to example 13 or 14, where the control system is configured to communicate via the second interface based on an edge-based pulse-width modulation protocol. 
     Example 16. The control system according to example 15, wherein the edge-based pulse-width modulation protocol is based on the short pulse width modulation code, SPC, protocol. 
     Example 17. The control system according to any one of examples 12 to 16, wherein the control system is configured to receive a request via the second interface and to send the redundant sensor data and/or the additional data in response to the request. 
     Example 18. The control system according to example 17, wherein the request specifies which data of the redundant sensor data and/or the additional data are to be sent by the sensor device. 
     Example 19. The control system according to example 18, wherein the redundant sensor data must always be sent, and the request selects a type of the additional data. 
     Example 20. The control system according to any one of examples 12 to 19, wherein the first interface comprises an interface for receiving data from an incremental interface, IIF, or a UVW interface. 
     Example 21. The control system according to any one of examples 12 to 20, wherein the control system is configured to receive the redundant sensor data and/or the additional data together with integrity information via the second interface and to check the integrity of the redundant sensor data and/or the additional data based on the integrity information. 
     Example 22. The control system according to example 21, wherein the integrity information comprises a CRC checksum. 
     Example 23. The control system according to any one of examples 12 to 22, wherein the additional data comprise diagnostic data and/or additional sensor data from a different sensor than the sensor data. 
     Example 24. The control system according to any one of examples 12 to 23, wherein the control system is configured to compare the sensor data and the redundant sensor data and/or to calibrate the sensor data based on the redundant sensor data. 
     Example 25. The control system according to any one of examples 12 to 24, wherein the control system is configured to control a further device based on the sensor data. 
     Example 26. A method for communicating between a sensor device and a control system, comprising: 
     transmitting sensor data from the sensor device to the control system via respective first interfaces of the sensor device and the control system, and 
     transmitting redundant sensor data and/or additional data from the sensor device to the control system via a respective second interface of the sensor device and the control system. 
     Example 27. The method according to example 26, wherein the second interface is a single-wire interface. 
     Example 28. The method according to example 26 or 27, wherein the transmission of the redundant sensor data and/or the additional data is based on an edge-based pulse-width modulation protocol. 
     Example 29. The method according to example 28, wherein the edge-based pulse-width modulation protocol is based on the short pulse width modulation code, SPC, protocol. 
     Example 30. The method according to any one of examples 26 to 29, further comprising sending a request from the control system to the sensor device, wherein the transmission of the redundant sensor data and/or of the additional data takes place in response to the request. 
     Example 31. The method according to example 30, wherein the request specifies which data of the redundant sensor data and/or the additional data are transmitted. 
     Example 32. The method according to example 31, wherein the redundant sensor data are always transmitted and wherein the request selects a type of the additional data. 
     Example 33. The method according to any one of examples 26 to 32, wherein the redundant sensor data and/or the additional data are transmitted together with integrity information. 
     Example 34. The method according to example 33, wherein the integrity information comprises a CRC checksum. 
     Example 35. The method according to any one of examples 26 to 34, further comprising using the control system to compare the sensor data and the redundant sensor data and/or to calibrate the sensor data based on the redundant sensor data. 
     Although specific exemplary embodiments have been illustrated and described in this description, persons with current knowledge of the art will recognize that a plurality of alternative and/or equivalent implementations can be chosen as a substitute for the specific exemplary embodiments shown and described in this description, without deviating from the scope of the invention disclosed. It is the intention that this application covers all adaptations or variations of the specific exemplary embodiments discussed here. It is therefore intended that this disclosure is limited only by the claims and their equivalents.