METHOD FOR EVALUATING A SENSOR DEVICE

Description

[0001] The invention relates to a method for evaluating a sensor device. In particular, the invention relates to a method in which a sensor device is used that has at least one proximity sensor which detects the spatial approach of bodies. The sensor device further comprises a control and evaluation unit that is coupled to the proximity sensor and which in turn has a signal output.

[0002] Sensor devices of the aforementioned type are used in motor vehicles to detect operating gestures. For example, such sensor devices with capacitive or optical proximity sensors, and occasionally also with ultrasonic or radar sensors, are used in vehicles where a vehicle function is to be triggered by the execution of an operating gesture. Operating doors or hatches, especially tailgates, can thus be largely contactless. In this context, contactless means that the operator does not have to perform any unlocking manipulation of a door lock or door handle.

[0003] The measured values ​​from the proximity sensor are evaluated using established methods to determine whether the temporal signal profile of the data output by the proximity sensor corresponds to predefined criteria that characterize a valid user request. For this purpose, a complex pattern comparison can be performed, but simple temporal characteristics of the signal profile, as well as changes in values ​​within certain time periods, can also be compared. If, for example, the proximity sensor is a capacitive sensor located in the rear of a vehicle, it is typically intended that a user must first perform a pivoting movement of their leg or foot in one direction towards the vehicle and then back again to express a user request.Such a kick sensor will accordingly perform an evaluation to determine whether the proximity sensor detects a body approaching and subsequently moving away within a certain time period. Other gestures and movements can also be used for operation. Numerous implementations for the basic recognition of such operating patterns are known in the prior art. Likewise, numerous designs for sensor devices with proximity sensors and associated control and evaluation units are known.

[0004] For example, document DE 10 2012 100 960 discloses a corresponding sensor device and an associated evaluation algorithm. An alternative design, in which a temporal signal profile of a proximity sensor is subjected to pattern recognition, can be found in DE 10 2014 100 974.

[0005] Document DE102013110506(A1) describes a method for detecting the activation of a function in a motor vehicle using a sensor arrangement. This arrangement consists of at least two sensor devices that are spatially separated and serve to detect operations triggered by the approach of a user's body part. After the first sensor device detects a characteristic initial signal response, the user's identity is verified using a portable ID transmitter. As soon as an operation is detected by approaching the second sensor device, signals from both sensors are monitored for a defined period. If the signals indicate continued operation during this period, the end of this time period is indicated to the user. If the first sensor device subsequently signals the end of the operation, the desired function in the motor vehicle is activated.

[0006] Document WO2015113554A1 discloses an emblem for a motor vehicle that integrates an optical sensor system. This system is designed to monitor a specific detection area outside the vehicle. When a user is detected within this area, a signal is triggered, initiating an authentication check between a portable ID transmitter and the vehicle. Additionally, the sensor system monitors a second, distinct operating area. If a user is detected in this area as well, the system provides a working signal to the vehicle, which can be used for further functions.

[0007] All known systems share the common feature of evaluating signal patterns from proximity sensors and, based on this evaluation, determining whether or not the user actually intends to operate the vehicle. Simultaneously with or subsequently, an authorization check can also be performed, which involves a wireless query of a vehicle key or other authentication device that the operator must carry to actually activate the vehicle function.

[0008] While the basic function of such operating devices and the procedures for their operation are now widespread and well-established, user and operator acceptance is not always satisfactory. Operators are often unsure whether they are performing an operating gesture correctly or whether the vehicle is even in a state where it detects the executed operating gesture. Numerous improvements have already been proposed to facilitate operation, such as the optical marking of an area in which the operating gesture is to be performed (see, for example, DE 10 2014 106 939).

[0009] However, such systems occasionally bring new problems, as they may require, for example, impermissible light sources on the car or lose their usefulness under unfavorable environmental conditions.

[0010] The object of the invention is to provide an improved method which increases the ease of use of a sensor device and also enables improved operating safety.

[0011] This problem is solved by a method with the features of the patent claim. 1.

[0012] According to the invention, during the detection process of an operating event, several different signals are output at the signal output of the control and evaluation unit. This control and evaluation unit can typically be connected via its signal output to a vehicle bus system or other central control unit of a vehicle. This central control unit receives the signals from the control and evaluation unit of the sensor device and, optionally using additional signals and criteria, initiates subsequent actions, such as unlocking a door or performing other positioning procedures on the vehicle. Triggering wireless communication in response to the central control unit receiving a signal from the control and evaluation unit of the sensor device is also possible. However, these subsequent actions are not part of the invention.The response to the output signals can be individually selected by the vehicle manufacturer.

[0013] According to the invention, in addition to the second control signal, which, according to the invention, signals the recognition of a valid control gesture, a temporally prior first control signal is generated and output. If a user performs a control gesture on the vehicle within the detection range of the sensor device and its proximity sensor, the sensor values ​​of the proximity sensor are evaluated to determine whether these values ​​represent a validly executed control gesture. As described in the prior art, various types of pattern recognition or other evaluations can be used for this purpose. The evaluation of these signal sequences, which represent a control gesture, such as the pivoting movement of a foot or the approach of a hand, can be captured and evaluated by threshold comparisons, pattern recognition using neural networks, and other algorithms. The specific criterion also depends on the type of proximity sensor used, which may be...It can be designed as a capacitive sensor (however, the method can also be used with other types of proximity sensors). Since this detection of actual operator events is state of the art, it will not be discussed further here.

[0014] Before a valid operation is actually recognized, a first operating signal is generated and output by the control and evaluation device, according to the invention. Completely different criteria can be used for this first operating signal than for the evaluation of the valid, complete operating event. It can, for example, be a subset of the criteria also used for the evaluation of the operating signal, or significantly broader criteria that are met for the correct execution of an operating event, although this may also include some invalid operating events. To generate the first operating signal, a timer t1 is started when the control and evaluation device detects the beginning of an actuation of the sensor device.The detection of an initiating action can be triggered, in particular, by a change in the proximity sensor readings beyond a certain deviation from the resting position. This could include, for example, crossing a threshold value that is a predefined distance from the long-term average of the proximity sensor readings, or a predefined percentage deviation from a moving average. When such a change in the readings is detected, the first timer t1 is started, and the acquisition of readings from the proximity sensors continues. If the first timer t1 reaches a first target value tz1, and the readings continuously meet a first criterion from the timer's start until the target value is reached, the first operating signal is output at the signal output.The first criterion can be a complex one, or it can be a simple, continuous threshold comparison, such that if the measured values ​​fall back to the long-term average value in the unattended state, the criterion is not met. It can also be designed to check for a continuous monotonic decrease in the measured values ​​at the proximity sensor, whereby the measured values ​​can be subjected to smoothing or filtering beforehand. The first criterion can differ from the criteria used to detect valid operation in terms of data volume and type of criterion. Therefore, if the first criterion is designed to require minimal computational effort, early detection of the first criterion can be performed while simultaneously monitoring for completely correct operation.The runtime of the first timer t1 (i.e., the target value tz1) is selected within the scope of the invention such that this runtime is significantly shorter than the usual actuation duration. The target value tz1 is therefore reached in the usual actuation scenario before the actuation has been fully completed.

[0015] A downstream central control unit can further process the initial operating signal and use it as a trigger for a variety of processes, none of which yet include the final actuation. In particular, it is possible to provide information to the operator in response to the initial operating signal, informing them that an evaluation of the operating process is underway and that their current action is being assessed. Such feedback significantly improves user comfort, as the user does not have to wait until the final activation of the operating function to find out whether the vehicle or sensor device has entered an active and sensing state. Any signal perceptible to the user can be used for such notification, for example, activation of warning systems on the vehicle or other vehicle equipment (e.g., interior lighting).

[0016] The acquisition of measured values ​​continues even after the first operating signal is generated. This continuation of measurement data acquisition proceeds according to the criteria used for the standard recognition of the operating gesture. These recognition processes also typically have maximum durations after which they are aborted. If, during the continued acquisition of measured values, the second criterion—designed for recognizing a valid execution of an operating gesture—is met, and thus valid operation by the control and evaluation unit is established, then the second operating signal is output at the signal output of the control and evaluation unit.

[0017] However, if a fully successful actuation is not detected and consequently no second operating signal is issued because the measured values ​​do not meet the second criterion, a failure actuation signal is issued, which differs from the first operating signal and the second operating signal.

[0018] The incorrect operation signal is therefore issued when an evaluation has been initiated, but no successful operation has subsequently been detected. This ensures that a unit downstream of the control and evaluation system (e.g., a central control unit of the vehicle) can override any effect on the vehicle or, subsequently, on the operator that may have been triggered by the initial operating signal, thus maintaining a consistent operating sequence and user experience at all times. For example, if the initial operating signal was used to indicate to the operator that operator recognition was in progress, the incorrect operation signal can be used to inform the operator of a corresponding unsuccessful detection attempt. This increases operator acceptance, as they can always track whether an operation is being recorded, whether it was successful, or whether it was not successfully detected.

[0019] If, however, the initial operating signal is not issued, the incorrect operation signal provides all downstream units with evaluable indications of a possible error detection or a service requirement for the system. The incorrect operation signal indicates that while measurement data has been fully evaluated, it cannot be attributed to any specific operation. This information can be stored in the vehicle system and, for example, read out during servicing, or it can be communicated to the vehicle operator. This allows for a simpler differentiation of potential malfunctions, as it is recognized that an operation may have occurred when the detection process was initiated, but the measured values ​​could not be attributed to any specific operation. Finally, information or a signal can also be issued to the user in response to the incorrect operation signal.

[0020] According to the invention, the first and second operating signals and the incorrect operation signal are differentiated so that the downstream central control unit, which receives the signals from the control and evaluation device, can distinguish between the signals at any time. The distinction can be based on any difference in signal encoding, frequency, signal level, or similar characteristics.

[0021] It is a preferred embodiment of the method if the output of the incorrect operation signal depends on the output of the first operating signal.

[0022] According to the invention, a characteristic property of the incorrect operation signal is set by the control and evaluation device depending on whether the first operating signal has been issued.

[0023] The control and evaluation unit has information on whether an initial operating signal has already been issued for a specific usage process. If the initial operating signal has not been issued, the control and evaluation unit can suppress the output of the incorrect operation signal. An incorrect operation signal will then only be issued if it was preceded by an initial operating signal.

[0024] If the operator has already received a signal in response to the first operating signal, this signal can be canceled upon receiving the incorrect operation signal, or the incorrect operation can be signaled with a further signal. However, this is not necessary if the first operating signal was not issued at all. Furthermore, the timing of the incorrect operation signal can be dependent on the timing of the first operating signal, for example, with a predefined delay, to ensure a clear and perceptible separation of the signals at all times.

[0025] In a preferred design, a characteristic property of the incorrect operation signal is set by the control and evaluation device depending on whether the first operating signal has been issued.

[0026] While the preceding example allows for a decision on whether to issue a misoperation signal if the initial operating signal is absent, this design provides for selecting signal properties based on whether the initial operating signal was sent. Thus, a misoperation signal is always issued when an operating process is initiated but the operation is not recognized. However, the properties of the misoperation signal differ depending on whether an initial operating signal was previously sent. A downstream system can then differentiate between these signals. By encoding the information differently, it can be more easily fed into a downstream processing path.

[0027] It is particularly preferred if the first and second operating signals and the incorrect operation signal differ in their signal length.

[0028] Length encoding of the signals enables a particularly simple and reliable transmission in a vehicle's signaling system, for example via a bus system.

[0029] In a preferred embodiment of the invention, the first criterion includes a condition that the measured values ​​do not cross a predetermined first threshold.

[0030] This criterion checks whether a threshold value is crossed within the runtime of the first timer t1. For example, the initial rise or fall of the measured values ​​above or below a threshold value can be used as the criterion to start timer t1, thus triggering the detection of the initiating operating event. Afterward, until the first timer t1 expires, it is checked whether the signal falls or rises again toward the initial level. If this is not the case, meaning the signal has not crossed the threshold value again within the specified time period, the first operating signal is output, possibly after checking for the fulfillment of further conditions. The advantage of such a simple threshold check lies in the low computational requirements for the evaluations and calculations.To keep such a system as simple as possible, low computing power requirements are advantageous, especially since the actual subsequent detection of an operator event may require all available resources for rapid evaluation. Furthermore, it has been shown that a simple threshold comparison can correctly detect the vast majority of operator events, with the threshold being determined empirically and depending on the vehicle model.

[0031] In a preferred embodiment of the invention, the sensor device comprises at least two proximity sensors, each providing measured values, and both of which are used for evaluation to generate the first control signal. Thus, until the first timer t1 reaches the target value, the sensor values ​​of both proximity sensors are used, allowing for a more precise and reliable early evaluation to generate the first control signal. For example, both sets of measured values ​​can be subjected to a threshold comparison, with each proximity sensor being assigned a specific threshold for comparison. In conventional sensor devices, such as those used in the rear of a vehicle, several proximity sensors, usually in the form of capacitive proximity sensors, are located at various positions on the vehicle's exterior.For example, a first proximity sensor is located in the bumper, while a second proximity sensor is positioned below it and further towards the center of the vehicle. If a pivoting motion of the foot is performed in this area, both proximity sensors detect a change in the signal, albeit with a time delay due to their position. As a first criterion, simple value comparisons can then be used for the two proximity sensors. However, the temporal progression of the measured values ​​of the proximity sensors can also be examined, for example, whether both proximity sensors show an increasing or decreasing trend until the first target value is reached by timer t1.

[0032] In a preferred embodiment of the invention, timer t1 is not only used for generating the first operating signal, but is also continuously monitored thereafter. It can then be provided that the timer t1 reaching a second target value TZ2 serves as a time limit for recognizing a valid operating event. Thus, if the control and evaluation unit does not recognize that a valid operating event has occurred by the complete execution of a correct operating gesture before the second target value TZ2 is reached, the operating event is discarded. In this way, a consistent maximum duration for possible operation is defined, which is clear and comprehensible to the user.

[0033] It is advantageous if the control and evaluation unit is operated in such a way that the signals output at the signal output are transmitted with a minimum time interval TD. The control and evaluation unit then ensures that even when several signals are to be output simultaneously or in quick succession, a minimum delay is maintained to guarantee error-free signal transmission within the vehicle system at all times. This is particularly relevant when the first operating signal and the second operating signal or the incorrect operation signal are generated largely simultaneously. In any case, a delay in the operation of the control and evaluation unit ensures that the minimum time interval between the first operating signal and the second operating signal or the incorrect operation signal is maintained.

[0034] It is particularly advantageous if the initial operating signal is used to inform the operator of the ongoing evaluation process via acoustic or visual signals. The purpose of this procedure is to provide transparent operator guidance, as such visual or acoustic feedback keeps the user informed about the current status of the process at all times.

[0035] The incorrect operation signal can also be used to inform the operator of a failed evaluation procedure through acoustic or visual signals. The purpose of this process is also to provide transparent operator guidance, as the user is always informed about the current status of the procedure through such visual or acoustic feedback.

[0036] In a modified version of the procedure, in addition to or as an alternative to an optical or acoustic signaling signal, the first operating signal can be used as a trigger to initiate wireless radio communication for authorization querying of an ID transmitter carried by the operator.

[0037] Since the first control signal precedes the second control signal indicating successful opening, this time saving can be used to initiate a wireless query of an ID transmitter, which is necessary anyway before a vehicle function, especially a door opening, can be triggered. Using the first control signal for this purpose results in a more pleasant user experience and improved user acceptance.

[0038] In a further development of the invention, when the control and evaluation unit detects a valid operation, it is first checked whether a first operating signal has actually already been issued. This ensures that whenever a second operating signal is issued, it is always preceded by a first operating signal. This guarantees a consistent user experience, meaning that an operation is never triggered without the first operating signal having been issued. Such a check is necessary because, as mentioned above, the criteria for generating the first operating signal can differ from the criteria for recognizing a successful operation.The initial control signal is issued based on an early evaluation, so it's entirely possible that the subsequent evaluation will confirm a valid operation, while the initial evaluation failed to meet the first criterion for generating the control signal. For example, if the first criterion is a simple threshold comparison that checks whether the measured values ​​remain consistently above or below a predefined threshold during the first timer's runtime, a single deviation can cause this criterion to fail validation. If, for instance, a zero value is delivered for any reason during signal transmission, the first criterion might be considered unfulfilled.The more complex evaluation, potentially employing smoothing and filtering, used to generate the second control signal after a complete and correctly executed operation, could eliminate such errors and confirm that a valid operation has indeed occurred. Then, even though the first criterion was not met up to time tz1, the first control signal is subsequently generated and output, followed by the second. This ensures that a second control signal is only output after a first control signal has been issued. Therefore, if the central control unit triggers a technical response to the first control signal, it can always be relied upon that this action is executed before any actual operation.

[0039] The invention is explained in more detail below with reference to the accompanying drawing. Figure 1ashows the rear view of a vehicle for carrying out the method according to the invention; Figure 1b shows a schematic side view of the vehicle Figure 1a ; Figure 2 shows a flowchart of an embodiment of the method according to the invention.

[0040] In the Figures 1a and 1bFigure 1 shows a vehicle in which proximity sensor electrodes 2 and 3 are arranged in the rear area. These proximity sensor electrodes are connected to a control and evaluation unit 4, which controls the proximity sensor electrodes as capacitive electrodes and determines their respective capacitance. This control unit 4 is in turn coupled to a central control unit 5 of the vehicle. The control and evaluation unit 4 handles the control of the electrodes 2 and 3 and the signal evaluation, i.e., the determination of the signal responses and their assignment to a control signal. Any control signal generated is transmitted by the control and evaluation unit 4 to the central control unit 5, which can execute the closing function of the tailgate and the electric opening.

[0041] Electrode 2 is located in the lower rear area and its detection area 2a is directed downwards, as shown in Figure 1bshown. Electrode 3 is arranged such that its detection area 3a is directed to the rear.

[0042] In Figure 1bThe leg 6a, 6b of a user is shown in two different positions. In position 6a, the user is standing behind the rear of the vehicle, and the user's leg may be detected by sensor arrangement 3 with detection range 3a, but not by sensor arrangement 2 with its detection range 2a. However, if the user moves close to the tailgate and places their foot within detection range 2a, as shown in position 6b, detection in both range 3a and range 2a is possible. For successful user detection, both sensor 2 and sensor 3 must provide time-based signal sequences that conform to a criterion stored in the control and evaluation unit 4.This can take into account, for example, how long the user's leg must remain in position 6b to register a successful activation and how the measured values ​​of sensor 2 and sensor 3 change over time. How such detection works and how a corresponding second operating signal is output is described in detail in the prior art. The control and evaluation unit can, in particular, perform pattern or threshold comparisons or even include a neural network to distinguish the actual operation from interference signals caused by other objects or environmental conditions.

[0043] According to the invention, however, the second operating signal, which signals successful activation to the central control unit 5, is preceded by a first operating signal. To generate the first operating signal, a timer t1 is started upon detection of initiating operation. In the present example, this timer can be started as soon as the proximity sensor electrode 3 and the proximity sensor electrode 2 detect the approach of an object, which is manifested by the increase of the measured values ​​above their respective assigned threshold values.

[0044] While the Figures 1a and 1b To illustrate the system that can be used to carry out the method according to the invention, the following is shown. Figure 2 the flow diagram of the method according to the invention in a first embodiment.

[0045] In a first section of the inventive method, which is described in Figure 2As shown in block 10, the control and evaluation unit 4 monitors the signals S1 and S2, each assigned to one of the proximity sensor electrodes 2 and 3, respectively. This monitoring is performed in a loop until the measured values ​​of both proximity sensor electrodes 2 and 3 cross a threshold value THR1 or THR2, respectively. Such a crossing of the aforementioned threshold values ​​indicates that an operator event may be beginning or initiating. The capacitance detected by the proximity sensor electrodes 2 and 3 changes so significantly compared to the previous state (a resting state or moving average) that the proximity of a user can be assumed. If this condition is met, i.e., if the assigned threshold values ​​THR1 or THR2 have been crossed at both proximity sensor electrodes 2 and 3, then process block 30 is executed.

[0046] Procedure block 30 describes how the first control signal is output and which associated criteria apply in this embodiment of the invention. First, timer t1 is set to zero. Then, for a duration of timer t1, specifically as long as it is less than the target value tz1, it is checked whether the signals S1 and S2, i.e., the measured values ​​of the proximity sensor electrodes 2 and 3, have not crossed the assigned threshold values ​​again and have risen or fallen towards their initial level. The reference here to falling and rising sensor readings is only relevant to this specific embodiment. Whether an approach is expressed by falling or rising measured values ​​depends on the type of signal representation and the circuitry of the proximity sensor electrodes.In process block 30, it is checked whether the signal data S1 and S2 remain on the same side of the assigned threshold values ​​for the duration of timer t1 and do not cross them again. If this is the case, an initial operating signal is output at the signal output of the control and evaluation unit. If not, the initial operating signal is not output. In any case, after the timer t1 has elapsed, the process returns to block 20. There, regardless of the previously or concurrently performed check in block 30, the measured values ​​S1 and S2 from the proximity sensors are used to check whether a valid operating event has occurred. The time required for this check can be significantly longer than the duration tz1 and may also take additional measured values ​​into account compared to the process in block 30.The evaluation of such a valid operating event can be performed using complex criteria and with significantly higher computational effort. For example, stored measured values ​​for a specific time range can be subjected to pattern matching or fed into a neural network. A variety of threshold comparison criteria can also be used to recognize a valid operating event. If a valid operating event is detected in block 20, it is checked whether an initial operating signal has been sent. If no valid operating signal was output in the previously or concurrently executed block 30, the initial operating signal is output first. Subsequently, the second operating signal, which indicates the recognition of the valid operating event, is output. The control and evaluation unit inserts a predefined minimum time interval between the first and second operating signals.

[0047] In this process, it is therefore always ensured that a second operating signal is always preceded by the first operating signal, even if it was not sent as part of the recognition in block 30.

[0048] However, if block 20 determines that no valid operating signal has been detected, the system first checks whether the first operating signal was generated in block 30. If not, the process is terminated and the measured values ​​S1 and S2 are monitored again. If, however, the first operating signal was sent in block 30, a fault signal 1 is now output by the control and evaluation unit. The system then returns to monitoring the sensors.

[0049] However, if block 20 determines that no valid operating signal was detected and the first operating signal was not issued, a fault signal 2 is issued by the control and evaluation unit. The system then returns to monitoring the sensors.

[0050] Misactivation signal 1 and misactivation signal 2 differ in such a way that a subsequent differentiation is possible, particularly in their signal duration and / or their coded signal content. The distinction as to whether the misactivation was preceded by the output of a first control signal allows for differentiated further processing. For example, the various misactivation states can be signaled to the user in an appropriate manner. If the user has already been signaled that an evaluation is in progress in response to the first control signal, the misactivation can then be signaled using the same signaling means, because it can be assumed that the user will continue to pay attention to these signals. A misactivation without prior signaling can, for example,The process can be evaluated silently; however, it can be stored in the service memory or a corresponding error message can be sent to a user-carrying ID transmitter or mobile device. If a user attempts an action that triggers an evaluation process, they can use the message to determine whether an evaluation has actually been initiated.

[0051] The reactions of the central control unit 5 to the first operating signal, the second operating signal, and the incorrect operation signal depend on the intended use and the specific vehicle manufacturer that has installed the system. As described above, a first operating signal can be used, in particular, to indicate to the user that their operation is being continuously monitored. Alternatively, the first operating signal can be used to integrate a means of authentication carried by the user, such as a key fob, into a radio communication system. In such a radio communication system, the vehicle can, for example, monitor the distance to a legitimate vehicle key while the actual operation is still being monitored.Similarly, the incorrect activation signal can be used to send a corresponding message to the user or the accompanying means of authentication and, if necessary, to terminate a radio dialogue.

Claims

1. Method for evaluating a sensor device, wherein the sensor device comprises at least one proximity sensor (2, 3) which detects the spatial approach of bodies (6a, 6b), and wherein the sensor device comprises at least one control and evaluation unit (4) which is coupled to the proximity sensor and which has a signal output, comprising the steps of: - repeatedly detecting the sensor measurement values of the proximity sensor (2, 3) by means of the control and evaluation unit, - if the sensor measurement values characterize the beginning of an actuation of the sensor device, then - starting a first timer t1, - repeatedly detecting the sensor measurement values of the at least one proximity sensor (2, 3) by means of the control and evaluation unit, - wherein, when the first timer has reached a first target value tz1 and the sensor measurement values have continuously fulfilled a first criterion since the start of the first timer, a first operating signal is output at the signal output of the control and evaluation unit (4), - continuing to detect the sensor measurement values of the at least one proximity sensor by means of the control and evaluation unit (4), - wherein, if the sensor measurement values fulfil a second criterion that is configured to recognise a valid execution of an operating gesture, a second operating signal is output at the signal output, - wherein, otherwise, if the sensor measurement values do not fulfil the second criterion, an erroneous operation signal is output at the signal output, - wherein the first operating signal, the second operating signal, and the erroneous operation signal differ characteristically, characterised in that a characteristic property of the erroneous operation signal is adjusted by the control and evaluation unit depending on whether the first operating signal has been output.

2. Method according to claim 1, wherein the output of the erroneous operation signal depends on the output of the first operating signal.

3. Method according to one of the preceding claims, wherein the first and second operating signals and the erroneous operation signal differ in their signal duration.

4. Method according to one of the preceding claims, wherein the first and second operating signals differ in their signal content.

5. Method according to one of the preceding claims, wherein the first criterion comprises a condition according to which the sensor measurement values do not cross a predetermined first threshold value.

6. Method according to one of the preceding claims, wherein the sensor device comprises at least two proximity sensors (2, 3), each providing sensor measurement values, and wherein, when the first timer has reached the first target value and the sensor measurement values of all proximity sensors (2, 3) have continuously fulfilled a respective assigned first criterion since the start of the first timer, a first operating signal is output at the signal output.

7. Method according to claim 6, wherein the first criterion assigned to each proximity sensor is a specific threshold value which the sensor measurement values of the respective proximity sensor (2, 3) must not cross.

8. Method according to one of the preceding claims, wherein the second criterion comprises a condition according to which a valid execution of an operating gesture must be detected within the runtime of timer t1 and before the timer t1 reaches a second target value tz2.

9. Method according to one of the preceding claims, wherein the control and evaluation unit, if necessary, delays the output of signals that are output at the signal output in such a way that a minimum time interval td is maintained between the signals.

10. Method according to one of the preceding claims, wherein the first operating signal and / or the erroneous operation signal is / are received by a processing unit and used as a trigger for activating an optical or acoustic signalling device.

11. Method according to one of the preceding claims, wherein the first operating signal is received by a processing unit and used as a trigger for initiating wireless radio communication for authorisation verification of an ID transmitter carried by the operator.

12. Method according to one of the preceding claims, wherein - if a valid operation is detected by the control and evaluation unit (4), and - if no first operating signal has yet been output, the first operating signal is first output at the signal output of the control and evaluation unit (4), and subsequently the second operating signal is output at the signal output.