EP3259746B1 - Method for operating a sensor device, and sensor device - Google Patents

Description

The invention relates to a method for operating a sensor device for detecting an object. The invention also relates to a sensor device for detecting an object. The invention also relates to a computer program.

State of the art

Determining the occupancy rate of multi-storey car parks and paid parking spaces is of great importance for their operation and for traffic control in cities. Therefore, sensors are used to monitor parking lots, which transmit the status of the parking lot to a control point. The condition is usually recorded either by magnetic field sensors, cameras or by emitting sensors such as ultrasonic or radar sensors.

Depending on the system, the sensors are either permanently connected to a power grid or a data network, which means a lot of effort during installation. Or they are battery-operated and communicate wirelessly with the control center. The particular challenge for wireless systems is to maximize the service life, which is limited by the battery capacity.

Disclosure of the invention

The font WO 2010/069002 A1 discloses a method for operating a sensor device for detecting an object, the sensor device having a first and a second environment sensor for detecting an environment of the sensor device.

The later published script EP2905765 A1 , which falls under Article 54 (3) EPC, concerns a hybrid magnetic radar detector for parking lot management. If the measurement of the magnetic field differs from a single standard measurement in an empty parking lot, a change in the magnetic field is detected, which indicates the presence of a vehicle and which is confirmed by the radar sensor.

The object on which the invention is based can therefore be seen in providing an efficient concept which makes it possible to reduce the electrical energy consumption of a sensor device.

This object is achieved by means of the respective subject matter of the independent claims. Advantageous refinements of the invention are the subject matter of the respective dependent subclaims.

• Messen eines Magnetfelds im Umfeld der Sensorvorrichtung mittels des Magnetfeldsensors, um einen dem gemessenen Magnetfeld entsprechenden Messwert zu ermitteln, wobei das Sensorgerät während der Messung des Magnetfelds deaktiviert ist,
• Berechnen einer ersten Distanz des Messwerts zu einem ersten Referenzmesswert, der einem Magnetfeld entspricht, wenn ein Messbereich des Magnetfeldsensors frei von einem Objekt ist,
• Berechnen einer zweiten Distanz des Messwerts zu einem zweiten Referenzmesswert, der einem Magnetfeld entspricht, wenn sich im Messbereich des Magnetfeldsensors ein Objekt befindet,
• Aktivieren des deaktivierten Sensorgerät abhängig von den berechneten Distanzen,
• Durchführen einer Laufzeitmessung im Umfeld der Sensorvorrichtung mittels des aktivierten Sensorgeräts, um der Laufzeitmessung entsprechende Sensordaten zu ermitteln,
• Ermitteln basierend auf den Sensordaten, ob sich in dem Umfeld der Sensorvorrichtung ein Objekt befindet.

According to one aspect, a method for operating a sensor device for detecting an object is provided, the sensor device comprising a magnetic field sensor and a sensor device which is designed for a transit time measurement, comprising the following steps:

• Measuring a magnetic field in the vicinity of the sensor device by means of the magnetic field sensor in order to determine a measured value corresponding to the measured magnetic field, the sensor device being deactivated during the measurement of the magnetic field,
• Calculating a first distance of the measured value to a first reference measured value, which corresponds to a magnetic field when a measuring area of the magnetic field sensor is free of an object,
• Calculating a second distance of the measured value to a second reference measured value, which corresponds to a magnetic field if there is an object in the measuring range of the magnetic field sensor,
• Activation of the deactivated sensor device depending on the calculated distances,
• Carrying out a transit time measurement in the vicinity of the sensor device by means of the activated sensor device in order to determine sensor data corresponding to the transit time measurement,
• Determine based on the sensor data whether there is an object in the vicinity of the sensor device.

• einen Magnetfeldsensor,
• ein Sensorgerät, das für eine Laufzeitmessung ausgebildet ist,
• eine Steuerungseinrichtung zum Steuern des Magnetfeldsensors und des Sensorgerät und
• einen Prozessor,
• wobei die Steuerungseinrichtung ausgebildet ist, den Magnetfeldsensor derart zu steuern, dass ein Magnetfeld im Umfeld der Sensorvorrichtung mittels des Magnetfeldsensors gemessen wird, um einen dem gemessenen Magnetfeld entsprechenden Messwert zu ermitteln, wobei das Sensorgerät während der Messung des Magnetfelds deaktiviert ist,
• wobei der Prozessor ausgebildet ist, eine erste Distanz des Messwerts zu einem ersten Referenzmesswert zu berechnen, der einem Magnetfeld entspricht, wenn ein Messbereich des Magnetfeldsensors frei von einem Objekt ist,
• wobei der Prozessor ausgebildet ist, eine zweite Distanz des Messwerts zu einem zweiten Referenzmesswert zu berechnen, der einem Magnetfeld entspricht, wenn sich im Messbereich des Magnetfeldsensors ein Objekt befindet,
• wobei die Steuerungseinrichtung ausgebildet ist, das deaktivierte Sensorgerät abhängig von den berechneten Distanzen zu aktivieren und derart zu steuern, dass eine Laufzeitmessung im Umfeld der Sensorvorrichtung mittels des aktivierten Sensorgeräts durchgeführt wird, um der Laufzeitmessung entsprechende Sensordaten zu ermitteln,
• wobei der Prozessor ausgebildet ist, basierend auf den Sensordaten zu ermitteln, ob sich in dem Umfeld der Sensorvorrichtung ein Objekt befindet.

According to a further aspect, a sensor device for detecting an object is provided, comprising:

• a magnetic field sensor,
• a sensor device which is designed for a transit time measurement,
• a control device for controlling the magnetic field sensor and the sensor device and
• a processor,
• wherein the control device is designed to control the magnetic field sensor in such a way that a magnetic field in the vicinity of the sensor device is measured by means of the magnetic field sensor in order to determine a measured value corresponding to the measured magnetic field, the sensor device being deactivated during the measurement of the magnetic field,
• wherein the processor is designed to calculate a first distance of the measured value to a first reference measured value, which corresponds to a magnetic field when a measuring area of the magnetic field sensor is free of an object,
• wherein the processor is designed to calculate a second distance of the measured value to a second reference measured value, which corresponds to a magnetic field when an object is located in the measuring range of the magnetic field sensor,
• wherein the control device is designed to activate the deactivated sensor device as a function of the calculated distances and to control it in such a way that a transit time measurement is carried out in the vicinity of the sensor device by means of the activated sensor device in order to determine sensor data corresponding to the transit time measurement,
• wherein the processor is designed to determine, based on the sensor data, whether there is an object in the vicinity of the sensor device.

According to a further aspect, a computer program is provided which comprises program code for carrying out the method according to the invention when the computer program is executed on a computer.

The invention thus includes in particular and among other things the idea of only activating the sensor device of the sensor device when the measurement of the magnetic field sensor is insufficient to be able to say with a predetermined probability whether or not there is an object in the vicinity of the sensor device. Because the sensor device is not activated continuously, that is to say permanently, in order to detect the surroundings of the sensor device, an electrical Energy consumption of the sensor device can be reduced. This is in comparison to a sensor device comprising a magnetic field sensor and a radar device or an ultrasound device, with both the radar device or the ultrasound device and the magnetic field sensor performing a field detection permanently or at least at predetermined intervals.

Furthermore, a service life limited by a battery capacity can thereby advantageously be maximized if the sensor device has such a battery, or generally an electrical energy supply, for the electrical energy supply. Thus, the sensor device can also be used in an advantageous manner in environments that do not have a wired power network for the purpose of energy supply. Thus, the effort involved in installing the sensor device can be reduced.

Calculating the corresponding distances between the measured value and the two reference measured values has the particular technical advantage that it can be determined whether a measured value is closer to the first or to the second reference measured value, i.e. whether the measured value is closer to the first or the second reference measured value resembles. The closer a measured value is to a certain reference measured value, the higher the probability, in particular, that there is no object in the measuring range of the magnetic field sensor if the measured value is closer to the first reference measured value, or that there is one in the measuring range of the magnetic field sensor Object is located when the measured value is closer to the second reference measured value.

The phrase “free of an object” means in particular that there is no object in the measuring range of the magnetic field sensor.

If, however, the determined distances are such that it cannot be reliably decided whether or not there is an object in the measuring range of the magnetic field sensor, based solely on the measured value, the deactivated sensor device is activated and a transit time measurement is carried out. So the sensor device can usually remain deactivated. The decision as to whether there is an object in the measuring range of the magnetic field sensor or not can be performed based on the magnetic field measurement alone. The sensor device is only activated in situations in which the magnetic field measurement is insufficient to reliably detect whether or not there is an object in the vicinity.

In one embodiment it is provided that the sensor device comprises a radar device and / or an ultrasound device.

A radar device within the meaning of the present invention comprises, in particular, a radar sensor for detecting radar radiation. The radar device is designed in particular to emit radar radiation, it being possible for reflected radar radiation to be detected by means of the radar sensor. The radar device therefore has, in particular, a radar emitter. In particular, according to one embodiment, the radar device is designed to measure a distance between the radar device and an object which is located in front of the radar device, that is to say in the measuring range of the radar device, that is to say in particular of the radar sensor. This is done by measuring the transit time of the emitted radar radiation. A transit time measurement in connection with the radar device can in particular be referred to as a radar measurement. The sensor data can then be referred to in particular as radar data.

An ultrasound device within the meaning of the present invention comprises in particular an ultrasound sensor for detecting ultrasound. The ultrasound is designed in particular to emit ultrasound, wherein reflected ultrasound can be detected by means of the ultrasound sensor. The ultrasound device therefore has, in particular, an ultrasound emitter. In particular, according to one embodiment, the ultrasound device is designed to measure a distance between the ultrasound device and an object which is located in front of the ultrasound device, that is, in the measuring range of the ultrasound device, that is in particular of the ultrasound sensor. This is done by measuring the transit time of the emitted ultrasound. A transit time measurement in connection with the ultrasound device can in particular be referred to as an ultrasound measurement. The sensor data can then be referred to in particular as ultrasound data.

According to one embodiment, the sensor device is designed to emit a signal, for example an ultrasonic signal and / or a radar signal, and to detect or measure a reflected signal, for example a reflected ultrasonic signal and / or a reflected radar signal, so that a transit time measurement of the signal can be performed. The sensor device thus includes, in particular, emitting sensors, which can generally also be referred to as active sensors, for example an active radar sensor and / or an active ultrasound sensor. An active sensor is thus understood to be a sensor that actively reflects a signal and can measure a reflected signal. The radar device thus comprises, for example, an active radar sensor, that is to say a radar sensor that emits radar. The ultrasound device thus comprises, for example, an active ultrasound sensor, that is to say an ultrasound sensor that emits ultrasound.

In contrast to this, a magnetic field sensor is a passive sensor because it does not emit a signal, but only passively measures the magnetic field in its surroundings or in its surroundings.

The sensor device is therefore designed in particular to measure a distance between itself and an object located in the measuring range of the sensor device. This in particular by means of a transit time measurement. Since a signal, for example radar and / or ultrasound, has to be emitted to measure the transit time, the sensor device can also be referred to as an emitting sensor device or as an active sensor device.

The fact that the sensor device is designed for a transit time measurement means in particular that the sensor device is designed to carry out a transit time measurement. This means that the sensor device carries out a transit time measurement. This, for example, to establish a distance between yourself and an object that is in the measuring range of the sensor device.

A transit time measurement includes in particular emitting or transmitting a signal and detecting or measuring a reflected signal. In particular, a transit time measurement includes a time measurement between the emitting or the transmission of the signal and the detection or the Measure the reflected signal. Based on the transit time measurement, it is provided according to one embodiment that a distance is determined or ascertained between the sensor device and an object which is located in the measuring range of the sensor device. Based on the transit time measurement, in particular based on the determined distance, according to one embodiment it is determined whether or not there is an object in the vicinity of the sensor device. Sensor data therefore include, in particular, data corresponding to the detected or measured reflected signal.

If, in the light of this description, a radar device and a radar measurement are specifically mentioned, this is not to be understood as restrictive. Rather, the sensor device and the transit time measurement should preferably also be read in general. Similarly, the ultrasound device should preferably also be read instead of or in addition to the radar device.

According to an example which is not part of the claimed invention, it is provided that the magnetic field sensor is deactivated after the measurement of the magnetic field. In particular, this has the technical advantage that the energy consumption of the sensor device can be reduced even further. This is because by deactivating the magnetic field sensor, electrical energy consumption of the magnetic field sensor is further reduced in an advantageous manner.

According to a further example, which is not part of the claimed invention, it is provided that the sensor device is deactivated after the transit time measurement has been carried out. This advantageously brings about the technical advantage that the energy consumption of the sensor device can be reduced even further. This is because the deactivation of the sensor device advantageously further reduces the electrical energy consumption of the sensor device.

That means in particular that after the detection of the surroundings by means of the magnetic field sensor, that is to say after the magnetic field measurement, the magnetic field sensor is deactivated.

That means in particular that after the detection of the surroundings by means of the sensor device, that is to say after the transit time measurement, the sensor device is deactivated.

Deactivation within the meaning of the present invention includes, in particular, that the magnetic field sensor or the sensor device is moved into a standby or standby mode. In particular, a deactivation in the sense of the present invention includes that a power supply or generally an electrical energy supply for the magnetic field sensor or the sensor device is interrupted. This means in particular that a deactivation can include that the magnetic field sensor or the sensor device is completely disconnected from an electrical energy supply.

Activation within the meaning of the present invention includes in particular that the magnetic field sensor or the sensor device is woken up from a sleep state or standby state or standby state. In particular, an activation includes that the magnetic field sensor or the sensor device is reconnected to an electrical energy supply if the magnetic field sensor or the sensor device has previously been disconnected from it.

The phrase “or” in the context of the present invention includes in particular the phrase “and / or”.

According to one embodiment, it is provided that a first magnetic field measurement is carried out by means of the magnetic field sensor, during which a measuring area of the magnetic field sensor is free of an object in order to determine the first reference measured value, a second magnetic field measurement being carried out by means of the magnetic field sensor, during which time the measuring area of the magnetic field sensor is located an object is located in order to determine the second reference measured value.

In particular, this has the technical advantage that, for example, the reference measured values can be determined during operation of the sensor device. In this way, specific environmental conditions can be taken into account in an advantageous manner. In this way, an adaptation to changing external influences can be effected in particular in an advantageous manner. Such external influences include, for example, weather or a placement of magnetic objects in the vicinity of the magnetic field sensor.

According to one embodiment it is provided that the calculated distances are normalized.

In another embodiment it is provided that the calculated distances are normalized, a difference between the two normalized distances being calculated, the difference between the two normalized distances being compared with a sensor device activation threshold value, the deactivated sensor device being activated depending on the comparison with the sensor device activation threshold value . In the case of a radar device, the sensor device activation threshold is a radar device activation threshold. In the case of an ultrasound device, the sensing device activation threshold is an ultrasound device activation threshold.

In particular, this has the technical advantage that it can be efficiently recognized when the deactivated sensor device has to be activated.

wobei der Normalisierungsfaktor insbesondere anwendungspezifisch gewählt ist. Anwendungsspezifisch heißt hier insbesondere, dass je nach vorgesehener Anwendung der Sensorvorrichtung, unterschiedliche Normalisierungsfaktoren gewählt werden. Wenn zum Beispiel die Sensorvorrichtung verwendet wird, um einen Belegtzustand einer Parkposition zu erfassen oder zu detektieren, so wird ein anderer Normalisierungsfaktor gewählt, als wenn die Sensorvorrichtung verwendet wird, um eine Verkehrsdichte zu messen.The normalization has the advantageous effect that the sensor device can behave in the same way in different environments. According to one embodiment, the calculation for the normalization is as follows: $$\mathrm{Normalized}\mathrm{distance}=\mathrm{distance}/\mathrm{Normalization\; factor},$$

wherein the normalization factor is selected in particular to be application-specific. Application-specific means here in particular that different normalization factors are selected depending on the intended application of the sensor device. For example, when the sensor device is used to detect or detect an occupied state of a parking position, a different normalization factor is selected than when the sensor device is used to measure a traffic density.

Another embodiment provides that the normalized distances are compared with a threshold value, depending on the Comparison with the threshold value is used to determine whether there is an object in the vicinity of the sensor device.

In particular, this has the technical advantage that it can be efficiently determined whether there is an object in the vicinity of the sensor device. So this in particular based on the magnetic field measurement.

Another embodiment provides that if it is determined based on the sensor data that an object is located in the vicinity of the sensor device, a magnetic field measurement is carried out by means of the magnetic field sensor in order to update the second reference measured value, wherein, if determined based on the sensor data If the surroundings of the sensor device are free of an object, a magnetic field measurement is carried out by means of the magnetic field sensor in order to update the first reference measured value.

In particular, this has the technical advantage that results of the transit time measurement can be used efficiently and effectively for updating the two reference measured values. This means in particular that after the transit time measurement, the magnetic field sensor carries out a magnetic field measurement in order to determine a corresponding measured value. Since it is known from the transit time measurement whether or not there is an object in the environment, this measured value can then be defined either as the first or as the second reference measurement value depending on whether the transit time measurement has shown whether an object is located in the environment or not.

This means in particular that if the transit time measurement has shown that there is an object in the vicinity of the sensor device, the measured value of the magnetic field measurement is defined as the second reference measured value. This means that the second reference measured value is then updated here. Correspondingly, the measured value of the magnetic field measurement is then defined as the first reference measured value if the transit time measurement has shown that there is no object in the vicinity of the sensor device. This means that the first reference measured value is then updated here. This is based on the runtime measurement.

According to a further embodiment, it is provided that a result of the determination of whether an object is located in the vicinity of the sensor device is sent via a communication network.

This brings about the technical advantage in particular that the result can also be made available remotely from the sensor device. For example, the result is sent over a communication network. A communication network includes, in particular, a WLAN and / or a cellular network.

In particular, according to an example that is not part of the claimed invention, it is provided that communication via the communication network is or is encrypted.

According to a further example, which is not part of the claimed invention, it is provided that a current result of the determination of whether an object is located in the environment is combined with an earlier result of an earlier determination of whether an object is located in the environment, is compared, the current result being sent via a communication network only if there is a difference between the current and the previous result.

In particular, this has the technical advantage that the electrical energy consumption of the sensor device can be reduced even further. This is because the current result is only sent via the communication network if a difference between the current and the previous result has been determined. In particular, this has the advantageous effect that an existing data bandwidth can be used efficiently. A result within the meaning of the present invention includes in particular that an object has been detected, that is to say that an object is present in the environment, that is to say is located in the environment. One result includes, in particular, that no object was detected, that is to say that there is no object in the vicinity.

The earlier result was determined analogously to the current result according to the method according to the invention or by means of the sensor device according to the invention. This means that the environment of the sensor device was detected at an earlier point in time in order to determine whether an object is located in the environment or not.

According to a further embodiment, it is provided that the sensor device is arranged in the vicinity of a parking position, so that, based on a result of the determination of whether an object is in the vicinity of the sensor device, it is determined whether the parking position is free or occupied.

In particular, this has the technical advantage that it can be determined efficiently and effectively whether the parking position is free or occupied. A free parking position particularly refers to a parking position in which no vehicle is parked. An occupied parking position particularly refers to a parking position in which a vehicle is parked.

In this embodiment, the sensor device can therefore be referred to as a sensor device for determining an occupied state of a parking position. The object which should or can be detected here is therefore in particular a vehicle. The sensor device can then, for example, also be referred to as a sensor device for detecting a vehicle.

In one embodiment it is provided that the control device is designed to control the magnetic field sensor in such a way that a first magnetic field measurement is carried out by means of the magnetic field sensor, during which a measuring area of the magnetic field sensor is free of an object in order to determine the first reference measured value, the control device being designed is to control the magnetic field sensor in such a way that a second magnetic field measurement is carried out by means of the magnetic field sensor, during which an object is located in the measuring range of the magnetic field sensor in order to determine the second reference measured value.

According to one embodiment it is provided that the processor is designed to normalize the calculated distances.

Another embodiment provides that the processor is designed to normalize the calculated distances, to calculate a difference between the two normalized distances and to compare the difference between the two normalized distances with a sensor device activation threshold value, the control device being designed to depend on the deactivated sensor device from the comparison with the sensing device activation threshold.

According to a further embodiment it is provided that the processor is designed to compare the normalized distances with a threshold value and, depending on the comparison with the threshold value, to determine whether there is an object in the vicinity of the sensor device.

According to yet another embodiment, it is provided that the control device is designed to control the magnetic field sensor in such a way that a magnetic field measurement is carried out by means of the magnetic field sensor in order to update the second reference measured value when it is determined based on the sensor data that an object is in the vicinity of the Sensor device is located, the control device being designed to control the magnetic field sensor in such a way that a magnetic field measurement is carried out by means of the magnetic field sensor in order to update the first reference measured value when it is determined based on the sensor data that an area around the sensor device is free of an object.

According to yet another embodiment it is provided that a communication interface is provided which is designed to send a result of determining whether an object is located in the vicinity of the sensor device via a communication network.

In another embodiment it is provided that an electrical energy supply is provided for an electrical energy supply of electronic elements of the sensor device. This will in particular the technical advantage has the effect that there is an independent energy supply for the sensor device. Electronic elements of the sensor device are in particular the sensor device, in particular the radar device and / or in particular the ultrasound device, the magnetic field sensor, the control device, the processor and possibly in particular the communication interface. According to one embodiment, the electrical energy supply comprises one or more batteries. In a further embodiment, the electrical energy supply comprises one or more accumulators.

Another embodiment provides that the processor is designed to determine, based on a result of the determination of whether an object is located in the vicinity of the sensor device, whether a parking position is free or occupied.

According to an example that is not part of the claimed invention, it is provided that the object is a vehicle traveling on a road or a container parked in a container storage area. This means in particular that the sensor device can be used to detect or monitor a traffic flow and / or a traffic density. In particular, an occupied state of a container space can thus advantageously be recorded or detected by means of the sensor device if the object is a container.

According to an example which is not part of the claimed invention, the processor and the control device are comprised by a microcontroller.

Device features result analogously from corresponding process features and vice versa. So that means in particular that Features, technical advantages and designs relating to the sensor device result analogously from corresponding designs, features and advantages of the method and vice versa. That means in particular that technical functionalities of the method result from the device and vice versa.

• Fig. 1 ein Ablaufdiagramm eines Verfahrens zum Betreiben einer Sensorvorrichtung,
• Fig. 2 ein Ablaufdiagramm eines weiteren Verfahrens zum Betreiben einer Sensorvorrichtung und
• Fig. 3 eine Sensorvorrichtung.

The invention is explained in more detail below on the basis of preferred exemplary embodiments, which each show

• Fig. 1 a flowchart of a method for operating a sensor device,
• Fig. 2 a flowchart of a further method for operating a sensor device and
• Fig. 3 a sensor device.

Fig. 1 shows a flowchart of a method for operating a sensor device for detecting an object.

• Messen 101 eines Magnetfelds im Umfeld der Sensorvorrichtung mittels des Magnetfeldsensors, um einen dem gemessenen Magnetfeld entsprechenden Messwert zu ermitteln, wobei das Radargerät während der Messung des Magnetfelds deaktiviert ist,
• Berechnen 103 einer ersten Distanz des Messwerts zu einem ersten Referenzmesswert, der einem Magnetfeld entspricht, wenn ein Messbereich des Magnetfeldsensors frei von einem Objekt ist,
• Berechnen 105 einer zweiten Distanz des Messwerts zu einem zweiten Referenzmesswert, der einem Magnetfeld entspricht, wenn sich im Messbereich des Magnetfeldsensors ein Objekt befindet,
• Aktivieren 107 des deaktivierten Radargeräts abhängig von den berechneten Distanzen,
• Durchführen 109 einer Radarmessung im Umfeld der Sensorvorrichtung mittels des aktivierten Radargeräts, um der Radarmessung entsprechende Radardaten zu ermitteln,
• Ermitteln 111 basierend auf den Radardaten, ob sich in dem Umfeld der Sensorvorrichtung ein Objekt befindet.

The sensor device comprises a magnetic field sensor and a radar device. In particular, the following steps are provided:

• Measuring 101 a magnetic field in the vicinity of the sensor device by means of the magnetic field sensor in order to determine a measured value corresponding to the measured magnetic field, the radar device being deactivated during the measurement of the magnetic field,
• Calculating 103 a first distance of the measured value to a first reference measured value, which corresponds to a magnetic field, if a measuring area of the magnetic field sensor is free of an object,
• Calculating 105 a second distance of the measured value to a second reference measured value, which corresponds to a magnetic field when an object is located in the measuring range of the magnetic field sensor,
• Activate 107 the deactivated radar device depending on the calculated distances,
• Carrying out 109 a radar measurement in the vicinity of the sensor device by means of the activated radar device in order to determine the radar data corresponding to the radar measurement,
• Determine 111 based on the radar data whether there is an object in the vicinity of the sensor device.

If it is determined on the basis of the calculated distances that the deactivated radar device does not have to be activated, a step 113 provides that the calculated distances are normalized, the normalized distances being compared with a threshold value, depending on the comparison with the Threshold value is determined whether there is an object in the vicinity of the sensor device. This means in particular that, according to step 113, it is determined on the basis of the magnetic field measurement alone whether there is an object in the vicinity of the sensor device. In this case, the radar device does not have to be activated. This brings about a reduced energy consumption of the sensor device in an advantageous manner.

Fig. 2 shows a flowchart of a further method for operating a sensor device for detecting an object.

The sensor device comprises a magnetic field sensor and a radar device. In particular, it is provided that the sensor device detects whether a parking position is occupied or free.

The method starts in a step 201, with a magnetic field sensor being activated for the purpose of a magnetic field measurement and a radar device being deactivated if it is not already deactivated.

In a step 203 it is provided that a first magnetic field measurement is carried out by means of the magnetic field sensor, during which a measurement area of the magnetic field sensor is free of an object in order to determine the first reference value. In particular, it is provided according to step 203 that a second magnetic field measurement is carried out by means of the magnetic field sensor, during which an object is located in the measuring range of the magnetic field sensor in order to determine the second reference measured value. So that means that according to it is provided in step 203 that the two reference measured values are initialized. This can be done, for example, during an initial assembly. In particular, this initialization of the reference measured values is carried out according to step 203 during operation of the sensor device.

In a step 205 it is provided that a magnetic field in the vicinity of the sensor device is measured by means of the magnetic field sensor in order to determine a measured value corresponding to the measured magnetic field, the radar device being deactivated during the measurement of the magnetic field.

In a step 207 it is provided that a first distance between the measured value and the first reference measured value is calculated. In particular, it is provided in step 207 that a second distance between the measured value and the second reference measured value is calculated. According to step 207 it is also provided that the calculated distances are normalized.

In a step 209 it is provided that the normalized distances are compared with a threshold value. In step 209 it is further provided that, depending on the comparison with the threshold value, it is determined whether there is an object in the vicinity of the sensor device. If there is no object in the vicinity of the sensor device, the method continues to block 211. If there is an object in the vicinity of the sensor device, a state is changed according to a step 213. This state therefore indicates whether the sensor device has detected an object or not, that is to say in particular whether a parking position is free or occupied. The states describe whether or not an object is present in the vicinity of the sensor device. The change affects the functioning of the sensor device, for example, in such a way that the fingerprint belonging to the state is updated in each case. Otherwise the change from one state to the other is binary, there is no transition phase. The state can be implemented, for example, by an internal status indicator, which can be referred to as a flag, for example, and can assume the values 0 (no object detected) and 1 (object detected).

The method then continues to block 211. Block 211 according to FIG Fig. 2 is not a separate function block, so it has no function of its own. The block 211 was only inserted into the flowchart in order to better illustrate the merging of the two decision branches (object present and no object present) for the sake of clarity.

From there, the method continues to step 215, in which a difference between the two normalized distances is calculated.

In a step 217 it is provided that the difference between the two normalized distances is compared with a radar activation threshold value.

Depending on the comparison with the radar activation threshold value, either the deactivated radar device is activated in accordance with a step 219 or it is not activated. If the radar device is activated according to step 219, a radar measurement is carried out by means of the activated radar device in the vicinity of the sensor device in order to determine the radar data corresponding to the radar measurement. According to step 219, provision is then made, in particular, for it to be determined based on the radar data whether there is an object in the vicinity of the sensor device.

The method then continues to step 221, in which, for example, provision can be made for a result of the determination to be sent out via a communication network. The method then ends in a step 223, according to which it can be provided that the sensor device is put into a sleep state. In particular, the magnetic field sensor is deactivated. In particular, the radar device is deactivated.

In particular, according to a further embodiment, it is provided that after a predetermined time or at predetermined intervals the method is continued in step 201 or 203 or 205 or started again.

Fig. 3 shows a sensor device 301 for detecting an object.

• einen Magnetfeldsensor 303,
• ein Radargerät 305,
• eine Steuerungseinrichtung 307 zum Steuern des Magnetfeldsensors 303 und des Radargeräts 305 und
• einen Prozessor 309,
• wobei die Steuerungseinrichtung 307 ausgebildet ist, den Magnetfeldsensor 303 derart zu steuern, dass ein Magnetfeld im Umfeld der Sensorvorrichtung 301 mittels des Magnetfeldsensors 303 gemessen wird, um einen dem gemessenen Magnetfeld entsprechenden Messwert zu ermitteln, wobei das Radargerät 305 während der Messung des Magnetfelds deaktiviert ist,
• wobei der Prozessor 309 ausgebildet ist, eine erste Distanz des Messwerts zu einem ersten Referenzmesswert zu berechnen, der einem Magnetfeld entspricht, wenn ein Messbereich des Magnetfeldsensors 303 frei von einem Objekt ist,
• wobei der Prozessor 309 ausgebildet ist, eine zweite Distanz des Messwerts zu einem zweiten Referenzmesswert zu berechnen, der einem Magnetfeld entspricht, wenn sich im Messbereich des Magnetfeldsensors 303 ein Objekt befindet,
• wobei die Steuerungseinrichtung 307 ausgebildet ist, das deaktivierte Radargerät 305 abhängig von den berechneten Distanzen zu aktivieren und derart zu steuern, dass eine Radarmessung im Umfeld der Sensorvorrichtung 301 mittels des aktivierten Radargeräts 305 durchgeführt wird, um der Radarmessung entsprechende Radardaten zu ermitteln,
• wobei der Prozessor 309 ausgebildet ist, basierend auf den Radardaten zu ermitteln, ob sich in dem Umfeld der Sensorvorrichtung 301 ein Objekt befindet.

The sensor device 301 comprises:

• a magnetic field sensor 303,
• a radar unit 305,
• a control device 307 for controlling the magnetic field sensor 303 and the radar device 305 and
• a processor 309,
• The control device 307 is designed to control the magnetic field sensor 303 in such a way that a magnetic field in the vicinity of the sensor device 301 is measured by means of the magnetic field sensor 303 in order to determine a measured value corresponding to the measured magnetic field, the radar device 305 being deactivated during the measurement of the magnetic field ,
• wherein the processor 309 is designed to calculate a first distance of the measured value to a first reference measured value, which corresponds to a magnetic field when a measurement area of the magnetic field sensor 303 is free of an object,
• the processor 309 being designed to calculate a second distance between the measured value and a second reference measured value, which corresponds to a magnetic field if an object is located in the measuring range of the magnetic field sensor 303,
• wherein the control device 307 is designed to activate the deactivated radar device 305 as a function of the calculated distances and to control it in such a way that a radar measurement is carried out in the vicinity of the sensor device 301 by means of the activated radar device 305 in order to determine the radar data corresponding to the radar measurement,
• the processor 309 being designed to determine, based on the radar data, whether there is an object in the vicinity of the sensor device 301.

The invention therefore includes in particular and among other things the idea of providing an efficient concept by means of which a lifetime of a sensor device, in particular a sensor device for detecting an occupied state of a parking position, comprising a radar device (and / or an ultrasound device, generally a sensor device, which is designed, to carry out a transit time measurement) and a magnetic field sensor can, in that the activation of the radar device (generally the sensor device) is in particular dependent on a signal from the magnetic field sensor. This advantageously reduces power consumption while maintaining the reliability of the detection, since the radar device (generally the sensor device) is only activated when it is needed. According to the invention, an efficient algorithm is therefore provided which decides from a small number of magnetic field measurement data whether activation of the sensor device, in particular the radar device and / or the ultrasound device, is necessary.

The core of the invention can be seen in particular in that, based on the distance from a measuring point of the magnetic field measurement to reference measurement data, for example the reference measurement values of an occupied and a free state of a parking position, it is decided whether the sensor device needs to be activated. The concept according to the invention, that is to say in particular the sensor device, has in particular the following advantages and technical features:
An increased service life of a battery through an intelligent reduction in the activation of the radar device, an extended maintenance interval and reduced operating costs.

Detection of the occupied status of the parking position from a current and at least one previous measured value with the magnetic field sensor when the radar device is not required.

A detection of the occupied state of the parking position from a current and at least one previous measured value, whether the activation of the radar device is necessary.

A continuous, in particular independent and / or automatic, calibration of the reference data, i.e. the reference measured values, in order to advantageously adapt to changing environments, for example different installation locations, changing external influences due to weather conditions, placement of magnetic objects in the vicinity of the sensor device.

A quick automatic adaptation to temporary changes, for example because a subway is moving below the parking position.

The sensor device, in particular the sensor device for monitoring parking spaces, that is to say for detecting an occupied status of a parking position, comprises in particular the following components:
A magnetic field sensor which, for example, periodically measures a magnetic field acting on it.

A radar device that can, for example, measure a distance to an object placed in front of the radar device. In general, a sensor device can be provided which can measure a distance to an object placed in front of the sensor device, in particular by means of a transit time measurement.

A microcontroller that runs software that controls the magnetic field sensor and the radar device. For this purpose, in particular, the magnetic field sensor and the radar device and any communication interface that may be present, which can also be referred to as a radio interface in the case of wireless communication, are activated. In particular, the software includes the inventive algorithm proposed here, which decides when the radar device should be activated.

A communication interface via which the detection is reported to a higher unit, for example an external server, i.e. a remote server.

An electrical energy supply, for example a battery, which supplies the electronic components, for example the magnetic field sensor, the radar device, the microcontroller, the radio interface, with electricity, i.e. generally with electrical energy.

According to an example that is not part of the claimed invention, it is provided that the magnetic field sensor is activated periodically in order to carry out a magnetic field measurement. As a result, changes in the ambient magnetic field can advantageously be used to determine whether a vehicle, generally an object, is located in the measuring range of the magnetic field sensor, that is, for example, above or next to the magnetic field sensor. However, it can now happen that this magnetic field measurement is disturbed by other external influences. It is therefore provided according to the invention that a radar device is also used. As a rule, however, this consumes significantly more electricity than the magnetic field sensor. This current usually has to be supplied or made available by the battery. This can make periodic activation of the radar device uneconomical, since either the battery life is greatly shortened or the response time of the sensor device is significantly lengthened.

These disadvantages are overcome in particular in that, according to the invention, the radar device is only activated when the radar device is actually needed. According to one embodiment, it is provided in particular that two images (fingerprints) are created and stored from the measured sensor values of the magnetic field sensor. So these are the two reference measured values.

A fingerprint (first reference measurement value) is created from the data from the empty parking position. The other fingerprint (second reference measurement value) is created from a parking position that is occupied.

According to an example that is not part of the claimed invention, it is provided that both fingerprints, i.e. both images, i.e. both reference measured values, are periodically updated during operation in order to advantageously adapt to changes in the measured magnetic field of the environment (e.g. drift by setting a temperature, placing magnetic objects nearby).

In order to determine or detect an occupied state of the parking position, the following is provided according to further embodiments:
A new measured value is preferably recorded periodically by means of the magnetic field sensor (compare step 205 according to FIG Fig. 2 ). From this measured value, the distances to the two fingerprints (that is to say to the two reference measured values) are calculated and then normalized (compare step 207 according to FIG Fig. 2 ). The normalized distances are compared with a threshold value (compare step 209 according to FIG Fig. 2 ). Depending on whether the normalized distances are above or below the threshold value, a decision is made as to whether the state has changed or whether the old state is retained. This means that, based on the comparison with the threshold value, a decision is made as to whether an occupied state of the parking position has changed (compare step 213 according to FIG Fig. 2 ) or not.

In order to decide whether the radar device has to be activated, one embodiment provides that the two normalized distances to the stored images are compared with one another (compare steps 215 and 217 according to FIG Fig. 2 ). If this difference between the two normalized distances is smaller than the radar activation threshold value, this means that no reliable decision can be made as to whether the occupied state has changed or not. This means that, according to one embodiment, it is then provided that the radar device is activated for a plausibility check for a distance measurement, in particular only for a short time. This means that after the distance measurement, the radar device is in particular deactivated again.

Then, according to an example that is not part of the claimed invention, it is provided that the result of the radar measurement is used to update the fingerprint in question, that is to say either the first or the second reference measured value. This is particularly due to the fact that the magnetic field sensor carries out a new magnetic field measurement.

The statements made above, in particular those in connection with the Fig. 1 , Fig. 2 and Fig. 3 The statements made apply analogously to sensor devices that generally include a sensor device, in particular an ultrasound device. That is, in the statements made above instead of or in addition to the radar device, an ultrasound device can be provided. This means that in the statements made above, a sensor device can generally be provided that is designed to carry out a transit time measurement, that is to say a sensor device that is designed for a transit time measurement.

Claims (18)

1. Method for operating a sensor apparatus (301) for detecting an object, wherein the sensor apparatus (301) comprises a magnetic field sensor (303) and a sensor device (305), which is embodied for a time-of-flight measurement, comprising the following step:

   - measuring (101) a magnetic field in the vicinity of the sensor apparatus (301) by means of the magnetic field sensor (303) in order to ascertain a measurement value corresponding to the measured magnetic field, wherein the sensor device (305) is deactivated during the measurement of the magnetic field,

   characterized in that the method furthermore comprises the following steps:

   - calculating (103) a first distance of the measurement value from a first reference measurement value that corresponds to a magnetic field if a measurement region of the magnetic field sensor (303) is free from an object,

   - calculating (105) a second distance of the measurement value from a second reference measurement value that corresponds to a magnetic field if an object is located in the measurement region of the magnetic field sensor (303),

   - activating (107) the deactivated sensor device (305) in dependence on the calculated distances,

   - performing (109) a time-of-flight measurement in the vicinity of the sensor apparatus (301) by means of the activated sensor device (305) in order to ascertain sensor data corresponding to the time-of-flight measurement,

   - ascertaining (111), based on the sensor data, whether an object is located in the vicinity of the sensor apparatus (301).
2. Method according to Claim 1, wherein a first magnetic field measurement is performed by means of the magnetic field sensor (303) while a measurement region of the magnetic field sensor (303) is free from an object in order to ascertain the first reference measurement value, wherein a second magnetic field measurement is performed by means of the magnetic field sensor (303) while an object is located in the measurement region of the magnetic field sensor (303) in order to ascertain the second reference measurement value.
3. Method according to Claim 1 or 2, wherein the calculated distances are normalized, wherein a difference between the two normalized distances is calculated (215), wherein the difference between the two normalized distances is compared (217) with a sensor device activation threshold value, wherein the deactivated sensor device (305) is activated (219) in dependence on the comparison with the sensor device activation threshold value.
4. Method according to Claim 3, wherein the normalized distances are compared (209) with a threshold value, wherein it is ascertained (113), in dependence on the comparison with the threshold value, whether an object is located in the vicinity of the sensor apparatus (301).
5. Method according to one of the preceding claims, wherein, if it is ascertained, based on the sensor data, that an object is located in the vicinity of the sensor apparatus (301), a magnetic field measurement is performed by means of the magnetic field sensor (303) in order to update the second reference measurement value, wherein, if it is ascertained, based on the sensor data, that a vicinity of the sensor apparatus (301) is free from an object, a magnetic field measurement is performed by means of the magnetic field sensor (303) in order to update the first reference measurement value.
6. Method according to one of the preceding claims, wherein a result of the ascertainment of whether an object is located in the vicinity of the sensor apparatus (301) is transmitted via a communication network.
7. Method according to one of Claims 1 to 5, wherein the sensor apparatus (301) is arranged in the vicinity of a parking position, with the result that it is ascertained, based on a result of the ascertainment of whether an object is located in the vicinity of the sensor apparatus (301), whether the parking position is free or occupied.
8. Method according to one of the preceding claims, wherein the sensor device (305) comprises a radar device (305) and/or an ultrasound device.
9. Sensor apparatus (301) for detecting an object, comprising:

   - a magnetic field sensor (303),

   - a sensor device (305), which is embodied for a time-of-flight measurement,

   - a control device (307) for controlling the magnetic field sensor (303) and the sensor device (305), and

   - a processor (309),

   - wherein the control device (307) is embodied to control the magnetic field sensor (303) in a manner such that a magnetic field in the vicinity of the sensor apparatus (301) is measured by means of the magnetic field sensor (303) in order to ascertain a measurement value corresponding to the measurement magnetic field, wherein the sensor device (305) is deactivated during the measurement of the magnetic field, characterized in that

   - the processor (309) is embodied to calculate a first distance of the measurement value from a first reference measurement value that corresponds to a magnetic field if a measurement region of the magnetic field sensor (303) is free from an object,

   - the processor (309) is embodied to calculate a second distance of the measurement value from a second reference measurement value that corresponds to a magnetic field if an object is located in the measurement region of the magnetic field sensor (303),

   - the control device (307) is embodied to activate the deactivated sensor device (305) in dependence on the calculated distances and to control it in a manner such that a time-of-flight measurement is performed in the vicinity of the sensor apparatus (301) by means of the activated sensor device (305) in order to ascertain sensor data corresponding to the time-of-flight measurement,

   - the processor (309) is embodied to ascertain, based on the sensor data, whether an object is located in the vicinity of the sensor apparatus (301).
10. Sensor apparatus (301) according to Claim 9, wherein the control device (307) is embodied to control the magnetic field sensor (303) in a manner such that a first magnetic field measurement is performed by means of the magnetic field sensor (303) while a measurement region of the magnetic field sensor (303) is free from an object in order to ascertain the first reference measurement value, wherein the control device (307) is embodied to control the magnetic field sensor (303) in a manner such that a second magnetic field measurement is performed by means of the magnetic field sensor (303) while an object is located in the measurement region of the magnetic field sensor (303) in order to ascertain the second reference measurement value.
11. Sensor apparatus (301) according to Claim 9 or 10, wherein the processor (309) is embodied to normalize the calculated distances, to calculate a difference between the two normalized distances, and to compare the difference between the two normalized distances with a sensor device activation threshold value, wherein the control device (307) is embodied to activate the deactivated sensor device (305) in dependence on the comparison with the sensor device activation threshold value.
12. Sensor apparatus (301) according to Claim 11, wherein the processor (309) is embodied to compare the normalized distances with a threshold value and to ascertain, in dependence on the comparison with the threshold value, whether an object is located in the vicinity of the sensor apparatus (301).
13. Sensor apparatus (301) according to one of Claims 9 to 12, wherein the control device (307) is embodied to control the magnetic field sensor (303) in a manner such that a magnetic field measurement is performed by means of the magnetic field sensor (303) in order to update the second reference measurement value if it is ascertained, based on the sensor data, that an object is located in the vicinity of the sensor apparatus (301), wherein the control device (307) is embodied to control the magnetic field sensor (303) in a manner such that a magnetic field measurement is performed by means of the magnetic field sensor (303) in order to update the first reference measurement value if it is ascertained, based on the sensor data, that a vicinity of the sensor apparatus (301) is free from an object.
14. Sensor apparatus (301) according to one of Claims 9 to 13, wherein a communication interface is provided, which is embodied to transmit, via a communication network, a result of the ascertainment of whether an object is located in the vicinity of the sensor apparatus (301) .
15. Sensor apparatus (301) according to one of Claims 9 to 14, wherein an electrical energy supply for supplying electronic elements of the sensor apparatus (301) with electrical energy is provided.
16. Sensor apparatus (301) according to one of Claims 9 to 15, wherein the processor (309) is embodied to ascertain, based on a result of the ascertainment of whether an object is located in the vicinity of the sensor apparatus (301), whether a parking position is free or occupied.
17. Sensor apparatus (301) according to one of Claims 9 to 16, wherein the sensor device (305) comprises a radar device (305) and/or an ultrasound device.
18. Computer program, comprising program code for performing the method according to one of Claims 1 to 8 if the computer program is executed on a computer.

Images