Method and apparatus for signal analysis

Abstract

Method (400) for signal analysis, wherein the method (400) comprises the following steps: Reading (402) a signal (204); Comparing (404) the signal (204) with a noise signal characteristic (102) that characterizes a noise signal, in order to determine whether the signal (204) represents the noise signal; and Temporarily storing (406) the signal (204) at least for a predetermined time interval (107) in order to obtain a temporarily stored signal (222), characterized in that where the interference signal characteristic (102) is given by an initial part characteristic (108) and an end part characteristic (110).

Description

State of the art

[0001] The invention relates to a method or device according to the preamble of the independent claims. The present invention also relates to a computer program.

[0002] Modern vehicles contain a large number of inertial sensors. Due to increasing connectivity and to avoid redundant sensor installation, these are often integrated into one or a few electronic control units (ECUs), which then provide the sensor information to applications within or outside that ECU. Sensors can exhibit vulnerabilities that can lead to signal interference in specific usage situations. Disclosure of the invention

[0003] Against this background, the approach presented here comprises a method for signal analysis, a device that uses this method, and finally a corresponding computer program according to the main claims. Advantageous further developments and improvements of the method specified in the independent claim are possible through the measures listed in the dependent claims.

[0004] Comparing a read-in signal with a noise signal characteristic that characterizes a noise signal makes it possible to determine whether the read-in signal is a noise signal.

[0005] According to the approach proposed here, signal interference from a sensor can be detected and, in a further development of the proposed concept, corrected before the interference signals are sent to an application inside or outside the control unit performing the comparison. This is made possible by the fact that, due to the operating principle, the interferences have a reproducible pattern represented in the interference signal characteristics, so that the interferences can be distinguished from any useful signals after examining the further signal path.

[0006] Advantageously, in a further development of the proposed approach, the sensor signals can be retrospectively cleaned up after considering the further signal progression, without distorting the useful signals.

[0007] According to the concept proposed here, malfunctions in signal-taking applications can be avoided without having to design or implement the algorithms of the receiving functions so robustly that no malfunctions occur. Consequently, higher performance of the function in question can be achieved.

[0008] As just one example of a sensor, a gyroscope is given, which, depending on the sensing axis, is also called a yaw rate, roll rate, or pitch rate sensor. Due to their measurement principle, gyroscopes are susceptible to interference from linear accelerations and / or rotational movements in one or more specific narrowband frequency ranges. If the sensor experiences such an external disturbance, it will display distorted signals for a short period.

[0009] Signal receivers for these yaw rate signals include, for example, roll rate sensors (RoSe), rollover prevention logic, or damper control systems. For pitch rate, these would be headlight range control or a damper control system; for yaw rate, several other receivers besides ESP are conceivable.

[0010] A method for signal analysis is presented, the method comprising the following steps: Reading a signal; Comparing the signal with a noise signal characteristic to determine whether the signal represents the noise signal; and Temporarily storing the signal for at least a predetermined time interval in order to obtain a buffered signal.

[0011] In the comparison step, the signal can be compared with at least one initial and one final characteristic of the interference signal characteristic to determine whether the signal represents the interference signal. In this case, the length of the time interval can be determined by the time difference between the initial and final characteristic.

[0012] The signal can be an electrically transmitted pulse from a sensor, such as a vehicle's yaw rate or acceleration sensor. The interference signal can be a measurement error from the sensor providing the signal, resembling a useful signal. The interference signal characteristic can describe a defined signal waveform over a predetermined time interval. The initial waveform can represent the beginning of the signal waveform, and the final waveform can represent the end of the signal waveform.

[0013] According to one embodiment of the method, in the comparison step, the initial part of the interference signal characteristic can represent a first signal edge, and the final part of the interference signal characteristic can represent a second signal edge opposite the first. The first signal edge can be a rising signal edge and the second signal edge a falling signal edge, or vice versa. In this way, the interference signal can be readily identified by detecting the exceedance of a threshold value using the signal edges.

[0014] The procedure can still perform a step of providing the buffered signal to an application interface if, during the comparison step, it is determined that the signal does not represent the interference signal. This advantageously prevents malfunctions of signal processing equipment connected to the application interface.

[0015] According to one embodiment, the method can perform a step of modifying the buffered signal to obtain a modified signal if, during the comparison step, it is determined that the signal represents the interference signal. This allows the signal to be easily cleaned up.

[0016] The method can then perform a step of providing the modified signal to an application interface. This embodiment of the method ensures that signal processing devices connected to the application interface operate with an interference-free signal.

[0017] For example, in the modification step, an interpolation can be performed between a first noise-free section of the signal located before a section of the signal representing the noise signal and a second noise-free section located after the section of the signal representing the noise signal. Advantageously, this allows the noise signal to be eliminated quickly and reliably.

[0018] According to a particular embodiment, the method can perform a step of providing a suspected interference signal information to an application interface if, during the comparison step, it is determined that the initial part of the signal's characteristic curve matches that of the interference signal. In particular, the step of providing the suspected interference signal information can be performed before the time interval has elapsed. This advantageously ensures that a signal delay, and thus a delay in a signal processing device connected to the application interface, occurs only in a fraction of the events detected by the associated sensor.

[0019] The method can further include a step of suppressing a program response based on the signal or the buffered signal, responsive to the step of providing the interference signal suspicion information. This embodiment of the method ensures that a signal processing unit associated with the program response does not execute any steps based on an interference signal.

[0020] It is advantageous if the method includes a step of confirming the suppression of the signal-based program response when, during the comparison step, it is determined that the signal's end-stage characteristic matches the interference signal's characteristic. This embodiment ensures, in a simple manner, that the signal-based program response is definitively discarded.

[0021] Alternatively, the procedure can execute a step of initiating the program response if, during the comparison step, it is determined that the signal does not match the end-segment characteristic of the interference signal characteristic. In this way, the previously suppressed program response can now be executed with only a slight delay.

[0022] This process can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, for example in a control unit.

[0023] The approach presented here further provides a device designed to perform, control, and implement the steps of a variant of the signal analysis method presented here in appropriate facilities. This embodiment of the invention, in the form of a device, also allows the underlying problem to be solved quickly and efficiently.

[0024] In this context, a device can be understood as an electrical device that processes sensor signals and outputs control and / or data signals accordingly. The device may have an interface, which can be implemented in hardware and / or software. In the case of a hardware-based interface, the interfaces can, for example, be part of a so-called system ASIC, which incorporates various functions of the device. However, it is also possible that the interfaces are separate integrated circuits or consist at least partially of discrete components. In the case of a software-based interface, the interfaces can be software modules, which, for example, are located on a microcontroller alongside other software modules.

[0025] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular if the program product or program is executed on a computer or device.

[0026] Exemplary embodiments of the invention are shown in the drawings and explained in more detail in the following description. It shows: Fig. 1 a diagram for representing a useful signal and a noise signal according to exemplary embodiments; Fig. 2 a block diagram of a device for signal analysis according to an exemplary embodiment; Fig. 3 a block diagram of a device for signal analysis according to a further embodiment; and Fig. 4 a flowchart of a method for signal analysis according to an exemplary embodiment.

[0027] In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and acting similarly, without repeating these elements.

[0028] Fig. Figure 1 shows a diagram illustrating example signals from sensors. A Cartesian coordinate system is shown. The abscissa represents time t [s] at millisecond intervals. The ordinate represents the rotation rate or angular velocity Ω [° / s], which is generally also denoted by ω. The diagram in Fig. Figure 1 shows three graphs illustrating typical signal waveforms of different signal types. The signal shown is merely an example. For instance, voltage values, current values, resistance values, or other quantities could be plotted on the ordinate.

[0029] A first graph 100 runs linearly over time t at a rotation rate of 0. The first graph 100 represents a signal profile 100 that is typical for a signal detected by the associated sensor when no relevant event occurs.

[0030] One in the representation in Fig. Graph 102, shown in a dashed line, illustrates an example of an interference signal characteristic 102 from the associated sensor. The interference signal characteristic 102 initially runs parallel to the signal waveform 100 at a rotation rate of 0 and, from a point shortly after the 0.01-second mark, takes the form of a Gaussian curve. After a brief spike into the negative rotation rate range between approximately 0.021 and 0.026 seconds, it returns to a rotation rate of 0, running parallel to the signal waveform 100. A peak 104 of the signal waveform 102 represents a maximum rotation rate value of approximately 21.

[0031] One in the representation in Fig. Graph 106, represented by a dot-dash line, depicts a useful signal 106 from the associated sensor. The useful signal 106 initially runs parallel to the signal curve 100, then rises parallel to the noise signal characteristic 102 up to the maximum rotation rate value 104. The useful signal remains via a Fig. The signal remains at this high level for a time interval 107, indicated by a double arrow. Subsequently, the signal curve 106 also drops to a value of 0. Here, the time interval 107 exemplifies a period between 0.01 seconds and 0.027 seconds from signal acquisition.

[0032] The signal waveforms 100, 102, and 106 each exhibit an initial characteristic and an end characteristic, where the initial characteristic represents an initial segment and the end characteristic represents an end segment of the graphs 100, 102, and 106 plotted in the diagram. An initial characteristic of the interference signal 102 and an initial characteristic of the desired signal 106 form a common rising signal edge 108. An end characteristic 110 of the interference signal 102, representing a falling signal edge 110, follows directly after the rising signal edge 108. An end characteristic 112 of the desired signal 106, representing a falling signal edge 112, occurs at a later time t compared to the falling signal edge 110 of the interference signal 102.

[0033] The in Fig. The signal waveforms 100, 102, and 106 shown in Figure 1 are merely examples and are intended, in particular, to illustrate the difference between the interference signal 102 and the useful signal 106. The waveform of the interference signal 102 with a rising edge 108 and immediately following a falling edge 110 indicates a measurement error of the associated sensor, for example, in the form of an entry of linear acceleration and / or rotational motion in one or more specific narrowband frequency ranges of the associated sensor, if the associated sensor is an acceleration or angular rate sensor.

[0034] According to one embodiment, the rising signal edge 108 can indicate an exceedance of a certain threshold. Fig. 1. Not shown threshold value, where exceeding the threshold value indicates the presence of the disturbance signal 102.

[0035] The in Fig. The depicted course of the disturbance signal 102 in the form of a Gaussian curve is, for example, typical for a disturbance of a gyroscope due to linear accelerations in sensor-specific critical frequency ranges of the gyroscope, wherein the slope of the edges 108, 110 is determined by an internal filter characteristic of the sensor.

[0036] However, a fault in the sensor cannot be detected, or can only be detected to a limited extent, on the rising edge 108, since this can be identical to that of the useful signal 106, as is exemplified in Fig. Figure 1 shows the following event. However, the subsequent falling edge 110 is typical of a disturbance, whereas the useful signal 106 remains at a high signal level for a longer period – here beyond the time interval 107. After the disturbance has been detected on the falling edge 110, the signal 102 is cleaned in the signal memory before being passed on to applications, according to the signal analysis concept proposed here, e.g., by interpolating the signals before and after the disturbance around the disturbance peak 104. This will be discussed in more detail with reference to the following figures.

[0037] Fig. Figure 2 shows a block diagram of a device 200 for signal analysis according to an embodiment of the concept proposed here. The device 200 can be a control unit of a road-bound vehicle such as a passenger car or truck.

[0038] A signal 204 is read from a sensor 202 into the device 200. According to exemplary embodiments, the sensor 202 is an acceleration sensor or a yaw rate sensor of an inertial sensor installed in the road-bound vehicle. The device 200 processes the signal 204 and provides a further signal 206 or an alternative further signal 208 to an application interface 210 with an application 212 associated with the inertial sensor.

[0039] Application 212 can be a signal processing device of the vehicle, for example for rollover detection. Application 212 can be part of the control unit comprising device 200 or be located outside the control unit comprising device 200 and, for example, be part of another control unit of the vehicle coupled to the control unit comprising device 200.

[0040] The in Fig. 2 The exemplary device 200 shown for signal analysis has a signal storage device 214, a comparison device 216, a signal provision device 218 and a signal correction device 220.

[0041] The signal storage device 214 is designed to temporarily store the signal 204 for a predetermined time interval in order to obtain a temporarily stored signal 222 and to provide it to an interface 224 with the signal provisioning device 218 and the signal correction device 220.

[0042] The comparator 216 is designed to compare the signal 204 with an initial part characteristic and an end part characteristic of an interference signal characteristic – as exemplified in Fig. Figure 1 is shown – for comparison. The comparison device 216 thus determines whether the signal 204 represents the interference signal or a useful signal.

[0043] According to one embodiment, the comparator 216 is designed to compare the signal 204 by detecting the in Fig. To identify the maximum rotation rate value or peaks of the signal curve shown as an example of interference, for example by means of a threshold comparison.

[0044] The length of the time interval for the intermediate storage of signal 204 in the signal memory 214 is determined by a time interval between the initial and final phases of the interference signal characteristic. According to one embodiment, this is represented as in Fig. Figure 1 shows, by way of example, the initial part characteristic of the interference signal characteristic a rising signal edge and the final part characteristic of the interference signal characteristic a falling signal edge.

[0045] If the comparator 216 does not identify the signal 204 as an interference signal or as a useful signal, the buffered signal 222 is provided to the signal provisioning unit 218 via interface 224. The signal provisioning unit 218 is configured to forward the buffered signal 222 as the further signal 206 in its original or unmodified form to the application 212 via application interface 210.

[0046] If, on the other hand, the comparator 216 identifies signal 204 as an interference signal, the buffered signal 222 is provided to the signal correction device 220 via interface 224. The signal correction device 220 is configured to modify the buffered signal 222, for example, to clean it, and to provide a modified signal 208 as the alternative further signal 208 to the application 212 via application interface 210.

[0047] According to an embodiment of the device 200, the signal correction device 220 performs an interpolation in which a first interference-free section of the signal 222, located before a section of the signal 222 representing the interference signal, is interpolated with a second interference-free section of the signal 222 located after the section of the signal 222 representing the interference signal.

[0048] Device 200 is designed to filter out interference from signal 204 using a (nonlinear) filter. This (nonlinear) filter is based on detecting the signal waveform that is significant for the interference. Crucially, signal 204 is buffered so that not only can the current sensor value be modified for interference correction, but the interference can also be detected retrospectively.

[0049] The detection methods used in the device 200 depend on the specific disturbance characteristics. For example, a disturbance in a gyroscope due to linear accelerations in sensor-specific critical frequency ranges resembles a Gaussian curve, as exemplified in Fig. Figure 1 shows the slope of the disturbance characteristic. The slope of the disturbance characteristic is determined by the internal filter characteristic of sensor 202.

[0050] After the disturbance is detected on the falling edge, the signal 222 in the signal memory 214 is cleaned up in the signal correction unit 220 before being passed on to the application 212, e.g. by interpolating the signals before and after the disturbance to remove the disturbance peak, as described in Fig. Figure 2 is shown as an example. The signal correction performed in the signal correction device 220 can also be referred to as "signal washing" of the disturbed signal 204.

[0051] Fig. Figure 3 shows a block diagram of another embodiment of the device 200 for signal analysis. Here, the device 200 is extended by a device 300 for providing a suspected interference signal information 302 to the application 212. The suspected interference signal information 302 contains data about the existence of a suspicion that the signal 204 is an interference signal.

[0052] The device 300 is configured to provide the interference signal suspicion information 302 to a device 304 for response suppression of the application 212 when the comparator device 216 determines that the signal 204 corresponds to the initial part characteristic of the interference signal characteristic. The application 212 is configured to execute a program response when the signal 204 is a useful signal.

[0053] The advantage of the in Fig. In the embodiment of the device 200 shown in Figure 3, the interference signal suspicion information 302 is output to the device 304 for suppressing a response by the application 212 even before the time interval in which the comparator 216 performs the signal comparison has elapsed. This enables the application 212 to suppress or delay a program response based on the signal 204 in response to the availability of the interference signal suspicion information 302, until the suspicion of a signal disturbance has been confirmed or not.

[0054] If, after the time interval has elapsed, the comparator 216 determines that signal 204 also corresponds to the end-segment characteristic of the interference signal characteristic, the suspicion that signal 204 is an interference signal and not a useful signal is confirmed. Consequently, the suppression of the program response based on signal 204 is confirmed, and application 212 does not execute the program response.

[0055] According to the in Fig. In the embodiment shown in Figure 3, this is done by the application 212 retrospectively performing signal cleansing in response to the provision of the buffered signal 222 in an internal signal cleansing device 220.

[0056] If, on the other hand, the comparator 216 determines at the end of the time interval that the signal 204 does not correspond to the end-stage characteristic of the interference signal characteristic and that the signal 204 is therefore a useful signal, the application 212, responding to the provision of the buffered signal 222 in a suitable device 306 of the application 212, actively reverses the response suppression performed in the device 304 or retroactively initiates the previously suppressed program response.

[0057] The in Fig. The variant of the signal analysis concept proposed herein, described in section 3, is particularly suitable for applications 212 within the control unit where the sensor signal 204 is initially processed. Instead of a time-delayed signal, the additional information 302, indicating a suspected signal disturbance, is provided. This prevents the execution of critical application responses during this signal 204. After the subsequent course of the signal 204 has been examined, if a disturbance is detected, the signal error is calculated from the quantities derived from the signal 204 in application 212 and / or the suppression of the application response is confirmed. In the case of a false suspicion of a disturbance, the application response is initiated retrospectively.

[0058] This is in contrast to the one in Fig. The presented variant of signal analysis or signal washing is advantageous because signal delay and thus a delay in application responses only occur in the case of a suspected peak, and therefore only in a small fraction of all situations.

[0059] Fig. Figure 4 shows a flowchart of an embodiment of a method 400 for signal analysis. The method can be described in the Fig. 2 and Fig. The device shown in section 3 is executed in 200.

[0060] In step 402, a signal is read into the device via an interface. In step 404, the signal is compared with the start and end characteristics of a noise signal characteristic to determine whether the signal represents the noise signal. In step 406, the signal is temporarily stored for a predetermined time interval to obtain a buffered signal.

[0061] According to one embodiment, the method 400 includes a step 408 for the retrospective correction of a signal disturbance detected in the comparison step 404, so that the negative effects of the disturbance on declining applications are avoided.

[0062] The signal buffering in step 406 of procedure 400 ensures that signals are not made available to applications immediately after generation, but are transmitted only after a time delay – defined according to the sensor and application. This makes it possible to detect signal interference in the further course of the sensor signals and then transmit signals corrected for the interference with a time delay.

[0063] Due to the time lag and the exemplary interpolation of the corrected values, the implementation of the concept presented herein in a control unit that provides sensor signals to other consumers is possible simply by operating the control unit and examining the sensor signals transmitted via CAN or FlexRay. This would be the case, for example, with all AB+ systems where the roll rate is provided externally. According to the exemplary implementations, the proposed concept can also be extended to RoSe systems.

[0064] According to one embodiment, the device is designed as a control unit comprising means for performing steps 402, 404, 406, 408, and optionally at least one means for executing the application using the signal. The control unit has a housing that encloses these means.

[0065] If an embodiment includes an “and / or” connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

Claims

[1] Method (400) for signal analysis, wherein the method (400) comprises the following steps: Reading (402) a signal (204); Comparing (404) the signal (204) with a noise signal characteristic (102) that characterizes a noise signal, in order to determine whether the signal (204) represents the noise signal; and Temporarily storing (406) the signal (204) at least for a predetermined time interval (107) in order to obtain a temporarily stored signal (222), characterized by , that where the interference signal characteristic (102) is given by an initial part characteristic (108) and an end part characteristic (110). [2] Method (400) according to claim 1, wherein the length of the time interval is determined by a time interval between the initial part characteristic and the final part characteristic. [3] Method (400) according to one of the preceding claims, wherein in the step of comparison (404) the initial part characteristic (108) of the interference signal characteristic (102) represents a first signal edge and the final part characteristic (110) of the interference signal characteristic (102) represents a second signal edge opposite to the first signal edge. [4] Method (400) according to one of the preceding claims, comprising a step of providing the cached signal (222) to an application interface (210) when, in the step of comparing (404), it is determined that the signal (204) does not represent the interference signal. [5] Method (400) according to any of the preceding claims, comprising a step of modifying (408) the cached signal (222) to obtain a modified signal (208) when, in the step of comparing (404), it is determined that the signal (204) represents the interference signal. [6] Method (400) according to claim 5, comprising a step of providing the modified signal (208) to an application interface (210). [7] Method (400) according to claim 5 or 6, wherein in the modification step (408) an interpolation is performed between a first interference-free section of the signal (204) located before a section of the signal (204) representing the interference signal and a second interference-free section of the signal (204) located after the section of the signal (204) representing the interference signal. [8] Method (400) according to claim 1, comprising a step of providing a suspicion of interference signal information (302) to an application interface (210) when, in the comparison step (404), it is determined that the signal (204) corresponds to the initial part characteristic (108) of the interference signal characteristic (102), wherein the step of providing the suspicion of interference signal information (302) is performed before the expiry of the time interval (107). [9] Method (400) according to claim 8, comprising a step of suppressing a program response based on the signal (204) in response to the step of providing the interfering signal suspicion information (302). [10] Method (400) according to claim 9, comprising a step of confirming the suppression of the program response based on the signal (204) when, in the step of comparing (404), it is determined that the signal (204) corresponds to the end-part characteristic (110) of the interference signal characteristic (102). [11] Method (400) according to claim 9, comprising a step of initiating the program response when, in the step of comparing (404), it is determined that the signal (204) does not correspond to the end-part characteristic (110) of the interference signal characteristic (102). [12] Device (200) configured to carry out the method (400) according to any one of the preceding claims. [13] Computer program configured to perform the method (400) according to any one of the preceding claims 1 to 11. [14] Machine-readable storage medium on which the computer program according to claim 13 is stored.

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