FIELD

The present invention relates to a method and to a device for operating multiple sensors of a vehicle in at least partially spatially coinciding detection areas and in a shared frequency domain.

BACKGROUND INFORMATION

If a sensor is able to receive an external signal or its external echo sent by an external sensor, this external signal or external echo may superimpose or interfere with a signal or echo of the sensor. To avoid interferences, the frequency spectrum of the electromagnetic waves is divided into frequency bands and the frequency bands are divided into channels. Sensors of a vehicle may be operated in parallel on different channels. In order to operate multiple sensors of the vehicle on the same channel, the sensors may be oriented in such a way that their detection ranges are situated on different sides of the vehicle or are oriented in different directions. The sensors may also transmit in succession. In this case, one sensor starts to transmit when the preceding sensor is finished with its modulation.

SUMMARY

In accordance with the present invention, a method and a device for operating multiple sensors of a vehicle in at least partially spatially coinciding detection areas and in a shared frequency domain, as well as finally a corresponding computer program are provided. Advantageous refinements of and improvements on example embodiments of the present invention described herein result from the description herein and the figures.

Specific embodiments of the present invention may advantageously allow multiple sensors to operate in the same detection area or in overlapping detection areas in the same frequency band or in the same frequency domain, without only one of the sensors each being allowed to operate.

In this case, it is possible to operate multiple sensors having overlapping detection areas simultaneously without disruptive interferences. The sensor signals are transmitted and received in a nested manner. Thus, the potential frequency domain may be utilized and a cycle time including a modulation time required for processing the sensor signals may be filled.

In accordance with an example embodiment of the present invention, a method is provided for operating multiple sensors of a vehicle in at least partially spatially coinciding detection areas and in a shared frequency domain, which is characterized in that at one transmission point in time at least two of the sensors simultaneously transmit at instantaneous frequencies separated by a frequency gap, the frequency gap including at least one instantaneous receive bandwidth of the sensors, each instantaneous frequency being blocked for use by the sensors, after the transmission point in time, for the duration of a time gap, the time gap including at least one signal propagation time across a reception range of the sensors.

Specific embodiments of the present invention may be considered to be based, among other things, on the concepts and findings described below.

A sensor may be an active sensor, which emits a signal and receives reflected echoes of the signal. The signal may be an acoustic signal or an electromagnetic signal, such as a light signal or a radio signal. In particular, the signal may be a radar signal. A distance to a reflecting object may be determined over a propagation time between the emitting and the receiving. A relative speed of the object to the sensor may be determined via a frequency shift of the echo relative to the signal. A direction to the object may be determined via a propagation time difference. The sensors may be identical. The sensors are operated in a synchronized manner. The sensors may emit signals in a shared frequency domain. The frequency domain is a section of a potential operating area of the sensors. The frequency domain is determined by an upper limit frequency and a lower limit frequency. The frequency domain includes a bandwidth of frequencies provided for use. An instantaneous frequency is a frequency of the frequency domain emitted momentarily or occupied by the sensor. The instantaneous frequency is adjustable. A frequency gap is a frequency spacing between two instantaneous frequencies minimally required for separating two signals. The frequency gap to be minimally adhered to between two simultaneously emitted instantaneous frequencies is determined by reception properties of the two simultaneously emitting sensors. While one sensor is tuned to one instantaneous frequency, it is able to receive frequencies with one receive bandwidth. The present instantaneous frequency in a two-sided band receiver may be situated centrally in the receive bandwidth. As a result, the frequency gap includes at least the one half of the frequencies of the receive bandwidth of the one sensor and the other half of the frequencies of the receive bandwidth of the other sensor. In a one-sided bandwidth receiver, the present instantaneous frequency may alternatively be situated at the edge of the receive bandwidth. As a result, the frequency gap includes at least the entire receive bandwidth of one sensor. A time gap is a minimum time interval between two transmission points in time on the same frequency. The time gap is thus a time interval, which must be maintained at least until emission takes place again on one frequency. Echoes are received on the frequency during the time gap. The time gap is at least long enough for the signal to be able to reach an object in a reception range and the echo of the signal reflected on the object is able to reach the sensor again. Thus, the time gap is at least twice as long as the product of the reception range and a propagation speed of the signal. A maximum possible value of the reception range is determined by a maximum transmission power and a reception sensitivity of the sensor. A value used may be lower than the maximum value.

One of the sensors is able to modulate in one frequency sub-band of the frequency domain for a partial modulation time period. All frequencies of the frequency sub-band may be transmitted as an instantaneous frequency at least once within the partial modulation time period. The frequency domain may be subdivided into multiple frequency ranges, so-called frequency sub-bands. A frequency sub-band may be assigned to a sensor for a predetermined time period, the so-called partial modulation time period. For the partial modulation time period, the instantaneous frequency within the frequency sub-band may be adjusted or modulated.

The sensor may transmit sequentially in different frequency sub-bands over a total modulation time period that includes multiple partial modulation time periods. The frequency sub-bands of a total modulation time period may cover at least a majority of all frequencies contained in the frequency domain. The frequency sub-bands may, in particular, cover the entire frequency domain. The frequencies of the frequency domain may thus be processed piece by piece. In the process, other sensors may each use simultaneously the free frequency sub-bands.

The frequency sub-bands of the total modulation time period may at least partially overlap. The overlapping frequencies in this case are transmitted multiple times in one total modulation time period. These frequencies are therefore frequently scanned.

The sensors transmitting at one transmission point in time may transmit in different non-overlapping frequency sub-bands. Alternatively, at least two of the sensors transmitting at one transmission point in time may transmit in at least partially overlapping frequency sub-bands or in the same frequency sub-band. Thus, one sensor may transmit per frequency sub-band or multiple sensors may modulate within one frequency sub-band. Multiple sensors may be operated within a shared partial modulation time period. These sensors then transmit the same frequency offset by at least the time gap. By using multiple sensors in the same frequency sub-band, it is possible to achieve a particularly tight nesting. With the simultaneous use of different frequency sub-bands, it is possible to efficiently utilize the available frequency domain.

Two adjacent frequency sub-bands may be spaced apart from one another by a buffer frequency band. A buffer frequency band between two frequency sub-bands offers an additional frequency spacing. In this way, a reliable separation of the simultaneously transmitting signals and echoes may be achieved. The frequencies of the buffer frequency band may be contained in a frequency sub-band, which is used chronologically subsequently and which overlaps the two adjacent frequency sub-bands.

The sensor may transmit within one partial modulation time period at least one frequency ramp that sweeps the frequency sub-band. A frequency ramp may have a predetermined gradient. The frequency ramp may be transmitted in a rising or falling manner. Successive frequency ramps may have different gradients. The frequency range of the frequency sub-band results in a maximum possible transmission duration of an instantaneous frequency. The frequency ramp may be made up of a plurality of successive transmission points in time, each having a different instantaneous frequency.

The partial modulation time periods of the sensors transmitting at one transmission point in time may begin with a time delay. As a result of the offset, it is possible to achieve a nesting of the sensors.

The example method may, for example, be implemented in software or in hardware or in a mixed form made up of software and hardware, for example, in a control unit.

The approach presented herein further provides an example device, which is designed to carry out, activate or implement the steps of a variant of the method described herein in corresponding units.

The device may be an electrical device including at least one processing unit for processing signals or data, at least one memory unit for storing signals or data and/or at least one interface and/or a communication interface for reading in or outputting data, which are embedded in a communication protocol. The processing unit may, for example, be a signal processor, a so-called system ASIC or a microcontroller for processing sensor signals and for outputting data signals as a function of the sensor signals. The memory unit may, for example, be a flash memory, an EPROM or a magnetic memory unit. The interface may be designed as a sensor interface for reading in the sensor signals from a sensor and/or as an actuator interface for outputting data signals and/or control signals to an actuator. The communication interface may be designed to read in or output the data wirelessly and/or in a hardwired manner. The interfaces may also be software modules, which are present, for example, on a microcontroller alongside other software modules.

Also advantageous is a computer program product or computer program having program code, which may be stored on a machine-readable medium or memory medium, such as a semiconductor memory, a hard disk memory or an optical memory, and which is used for carrying out, implementing and/or activating steps of the method according to one of the previously described specific embodiments, in particular, when the program product or program is executed on a computer or a device.

It is noted that some of the possible features and advantages of the present invention herein are described with reference to different specific embodiments as method and device. Those skilled in the art recognize that the features may be combined, adapted or interchanged in a suitable manner in order to arrive at additional specific embodiments of the present invention.

