WO2020058396A1

WO2020058396A1 - Method for operating an optoelectronic sensor for a motor vehicle, computer program product, optoelectronic sensor and motor vehicle

Info

Publication number: WO2020058396A1
Application number: PCT/EP2019/075158
Authority: WO
Inventors: Jochen Schenk; Frank SELBMANN; Frank Ehmann; Olga KASPEREK
Original assignee: Valeo Schalter Und Sensoren Gmbh
Priority date: 2018-09-21
Filing date: 2019-09-19
Publication date: 2020-03-26
Also published as: EP3853630A1; DE102018123298A1

Abstract

The invention relates to a method for operating an optoelectronic sensor (5) of a motor vehicle (1), in which method, during a measuring cycle for detecting an object (3), light pulses are emitted by means of a transmitting device (6) of the optoelectronic sensor (5) and the light pulses reflected by the object (3) are received by means of a receiving device (7) of the optoelectronic sensor (5). In order to emit the light pulses, a light source (12) of the transmitting device (6) is activated at certain transmission time points, and the light pulses are deflected by means of a deflecting unit (13) of the transmitting device (6). Successive movements along a predefined deflection angle range (15) are performed by means of the deflecting unit (13) in order to deflect the light pulses. The predefined deflection angle range (15) is divided into a plurality of deflection angle range segments (16a to 16r). During each movement of the deflecting unit (13) along the deflection angle range (15), a light pulse is emitted in each of predefined ones of the angle range segments (16a to 16r).

Description

Method for operating an optoelectronic sensor for a motor vehicle, computer program product, optoelectronic sensor and motor vehicle

The present invention relates to a method for operating an optoelectronic sensor for a motor vehicle. By means of the optoelectronic sensor, light pulses are emitted into a surrounding area of the motor vehicle during a measurement cycle with a transmitting device of the optoelectronic sensor for detecting objects, and the light pulses reflected on an object are emitted with a

Receiving device of the optoelectronic sensor received. To emit the light pulses, a light source of the transmission device is activated at certain transmission times and the light pulses are deflected with a deflection unit of the transmission device. The deflection unit has a periodically oscillating deflection element which is deflected within a predetermined angular range. The invention further relates to a computer program code, an optoelectronic sensor and a motor vehicle.

In the present case, the focus is particularly on optoelectronic sensors for motor vehicles. Such optoelectronic sensors can be designed, for example, as lidar sensors (lidar is the abbreviation for light detection and ranging), in particular as a laser scanner. Such optoelectronic sensors are installed, for example, in motor vehicles in order to detect the surroundings of the motor vehicle while driving or while the motor vehicle is in operation. The optoelectronic sensor is in particular a scanning optical measuring device by means of which objects in the surroundings of the motor vehicle can be detected. For example, the optoelectronic sensor can be used to determine a distance between the motor vehicle and the object on the basis of the transit time of a light pulse (also known as the time-of-flight principle). The

Optoelectronic sensor usually comprises a transmission device that

for example, has a laser diode by means of which an optical transmission signal in the form of a light pulse can be emitted. In addition, the optoelectronic sensor comprises a corresponding receiving device, which

for example, has at least one photodiode, by means of which the light pulse reflected by the object can be received as a received signal. With the optoelectronic sensor, the light pulses are emitted in a predetermined angular range in the vicinity of the motor vehicle. To deflect the light pulses or the laser light within the angular range, the transmitting device has a deflection unit that includes a periodically oscillating deflection element that is deflected in a predetermined angular range, for example a micromirror or MEMS mirror. The light pulses can be emitted at predetermined transmission times. Thus, with the

Transmitting device can be scanned a predetermined angular range in the vicinity of the motor vehicle. The predetermined angular range can be defined in the horizontal and / or in the vertical direction, depending on the selection of the deflecting element

Deflection unit. By dividing the predetermined angular range into a plurality of deflection angles, a resolution can be defined with which the surroundings can be scanned. The transmission device or a light source of the

Transmitting device is usually controlled at constant time intervals. Within half a period of an oscillation of a periodically oscillating deflecting element such as a micro or. MEMS (abbreviation for Micro-Electro-Mechanical - Systemj mirroring, ie the deflection of the deflection unit from a first maximum deflection angle to a second maximum deflection angle, however, is generally not possible to completely scan the entire surrounding area. This is particularly due to a waiting time between two

Light pulses that are needed to receive the reflected light pulses. The

Deflection element continues to oscillate during this period. This means that a large number of vibrations of the deflecting element are required so that the surroundings can be scanned.

The object of the present invention is to provide a method for operating a

to provide an optoelectronic sensor, a computer program product, an optoelectronic sensor and a motor vehicle in order to increase the detection rate of an optoelectronic sensor for a motor vehicle or to reduce the duration of a measurement cycle.

This object is achieved by a method, a computer program product, an optoelectronic sensor and a motor vehicle according to the independent

Claims solved.

One aspect of the invention relates to a method for operating an optoelectronic sensor for a motor vehicle. Within a measuring cycle, a Transmitting device of the optoelectronic sensor for detecting at least one object emits light pulses into a surrounding area of the motor vehicle. The light pulses reflected on an object are received by a receiving device of the optoelectronic sensor. The emitted light pulses are deflected into a plurality of deflection angles by a deflection unit of the transmission device

Distracted surrounding area. To deflect the light pulses, the deflection unit has a periodically oscillating deflection element which is deflected within a predetermined angular range.

According to the invention, the predetermined angular range is divided into a plurality of segments. Within a measuring cycle, the deflection element is deflected at least once in a first deflection direction and at least once in a deflection direction opposite to the first deflection direction. A first deflection angle is assigned to each segment when deflecting in the first deflection direction and a second deflection angle is deflected when deflecting in the second deflection direction. With each deflection in a deflection direction, a light pulse is emitted in at least one segment.

The method according to the invention is intended for operating an optoelectronic sensor for a motor vehicle, in particular for a passenger car. The optoelectronic sensor can be designed as a lidar sensor, in particular as a laser scanner. Objects in the surroundings of the motor vehicle are detected with the optoelectronic sensor. To capture the object, use the

optoelectronic sensor performed consecutive measurement cycles. In each measuring cycle, a certain number of

Transmitted signals in the form of light pulses. The light pulses are emitted into the surrounding area at a variety of deflection angles. The deflection angles can include horizontal and / or vertical deflection angles. The maximum

Deflection angles in this case span a deflection angle range which, for example, can have a horizontal deflection angle range of 100 ° to 180 ° or 120 ° to 160 °, in particular 140 ° to 150 °. In addition, a vertical deflection angle range of, for example, 5 ° to 45 ° or 15 ° to 35 °, in particular 25 °, can be spanned. The emitted light pulses, which were reflected on the object, are received with the receiving device of the optoelectronic sensor. The

For this purpose, the receiving device can have, for example, a photodiode, in particular an APD (abbreviation for avalanche photodiode), an array of photodiodes or a matrix of photodiodes in order to receive the light pulses reflected on objects and generate corresponding electrical signals. Alternatively, for example, a CCD (abbreviation for charge-coupled device) sensor can be provided for this

to receive reflected light pulses. Based on the measurements of the

optoelectronic sensor can in particular be a distance between the

Motor vehicle and the object and / or a position of the object relative to the vehicle can be determined.

The transmission device has the light source and a deflection unit. For example, one or more laser diodes can be used as the light source. The light source generates light pulses which are then deflected into a predetermined deflection angle range by means of the deflection unit. For this purpose, the deflection unit has a periodically oscillating deflection element. Micro-mirrors or MEMS mirrors in particular can be used as the periodically oscillating deflection element. Micromirrors or MEMS mirrors offer the advantage that they require very little installation space and can be easily applied to a printed circuit board, which allows simple integration into an optoelectronic sensor and enables a reduction in the size of the sensor. The oscillation frequency of the deflection element can be, for example, a frequency in the range from 1 kHz to 5 kHz or 2 kHz to 4 kHz, in particular 3.5 kHz. The maximum deflection angle of the deflection area can be, for example, ± 5 ° to ± 45 ° or ± 15 ° to ± 35 °, in particular ± 25 °.

Depending on the emission of two light pulses, one can

Range request to the optoelectronic sensor, a waiting time can be specified. If, for example, the optoelectronic sensor is to be able to detect objects within a range of 200 m, the waiting time must correspond to at least the time it takes a light pulse to cover 400 m, namely 200 m from the sensor to the object and 200 m from the object back to the sensor. In addition, a

Processing time can be specified by an evaluation device, which is required to process a received signal. Thus, the waiting time can be at least

Time period from sending to receiving a signal at maximum

Coverage range and processing time include. The time interval that is required to build up the energy for the next light pulse can mostly be neglected, since this time interval for most light sources for

optoelectronic sensors for motor vehicles is significantly less than the waiting time.

The periodically oscillating deflection element continues to oscillate during the waiting time. It is thus from a certain predetermined angular resolution with which the To be scanned, not possible within a range

Half oscillation of the deflection element at each deflection angle at which a light pulse is to be emitted, to emit a light pulse since the waiting time is longer than a time in which the deflection element moves from one deflection angle to the next

Deflection angle is deflected. Thus, from a certain resolution, at least one complete oscillation period is required to scan the surrounding area in order to scan the surrounding area with the corresponding resolution.

A deflection angle in the sense of the invention is a defined angular position of the

Deflection unit in which a light pulse is emitted into the surrounding area by means of the deflection unit in order to emit a light pulse into the surrounding area at a deflection angle corresponding to the angular position. In other words, with each deflection angle, a deflection angle is specified with which the surrounding area is scanned. Depending on the design of the optoelectronic sensor and the orientation of the transmitting device to the deflection device, a light pulse at a deflection angle of 0 ° can be emitted at a maximum deflection angle of ± 35 ° at a deflection angle of 0 °, and at a deflection angle of ± 10 ° Light pulse with a deflection angle of ± 20 °, with a deflection angle of ± 20 ° a light pulse with a deflection angle ± 40 ° etc.

The time required for a measuring cycle of the optoelectronic sensor can be reduced by dividing the angular range by deflecting the deflecting element into a plurality of segments and giving each segment a first deflecting angle when deflecting in the first deflecting direction and when deflecting in the first

Direction of deflection opposite the second deflection direction is assigned a second deflection angle. By emitting a light pulse in at least one segment each time the deflection element is deflected in a deflection direction, the detection rate is maximized or the duration of a measurement cycle is reduced, although one or more segments can still be omitted, for example if already in all

A light pulse was emitted. In addition, it is possible that if a measurement cycle has been completed within a deflection of the deflection element, the next measurement cycle can be started during the same deflection.

In a preferred embodiment, a deflection angle for emitting the light pulse is determined for each deflection of the deflection element for the respective segments, the deflection angle for emitting the light pulse for the respective segments Differentiate segments of the successive deflections within a measurement cycle.

By sending out the light pulses in a segment within successive deflections at different deflection angles, the time required for a measurement cycle can be further reduced. In the simplest application, depending on the specified resolution, range requirement and repetition rate, the

Light source the entire surrounding area can be scanned in a period of the deflection element. When deflecting in the first deflection direction, a first part of the surrounding area can be scanned, when deflected into the second

Deflection direction a second part of the surrounding area. In this case, however, the entire surrounding area cannot be scanned sequentially within a deflection of the deflection element, but only by superimposing the

Partial scan images can result in the entire image of the surrounding area. In particular, it can also be provided here that a light pulse does not have to be emitted in each segment with every deflection. This has the advantage that, for example, when the optoelectronic sensor is switched on and the required deflection of the deflection unit, at least a portion of the

Surrounding area can be detected. In addition, it can be an advantage under certain conditions not to have a light pulse in individual segments

To send out deflection of the deflection unit, for example to ensure eye safety when a person has been detected in the vicinity of the optoelectronic sensor.

In a further embodiment, a plurality of

Deflection angle determined for emitting the light pulse and within one

A light pulse is emitted only once for each measuring cycle at each of the deflection angles. The fact that only one light pulse is emitted at each deflection angle of a segment prevents double or multiple scanning of individual scanning angles. A double or multiple scan increases the duration of a measurement cycle, since each double or multiple scan receives information that has already been obtained in a previous scan. Both the detection rate and the eye safety can thus be increased, since a double or multiple scanning of individual scanning angles could lead to a potential hazard within a very short time window. According to one embodiment, the deflection element is periodically between a first reversal angle of the angular range and a second reversal angle of the

Deflected angular range and divided the angular range into at least one middle segment, a first outer segment and a second outer segment, the first outer segment comprising the first reversal angle and the second outer segment comprising the second reversal angle.

In particular, it is provided in a further embodiment that the first outer segment and the second outer segment comprise fewer deflection angles than the at least one middle segment. In other words, the middle segment is arranged between the first and the second outer segment. In this way, for example, depending on the operating parameters of the deflecting mirror, for. B.

Resonance frequency or vibration amplitude, the number of deflection angles in the outer segments can be adjusted. This can be particularly relevant for the outer segments, since these contain the reversal angles of the periodically oscillating deflection element. Since the angular velocity, that is, the change in the deflection of the deflection element per time, initially decreases at the reversal angle and then increases again to a constant value in the opposite direction of deflection. Thus, by reducing the deflection angle in the outer

Segments the duration of a measurement cycle can be reduced. In addition, by reducing the deflection angles in the outer segments, the resolution with which a sub-area of the surrounding area is scanned with the light pulses emitted at the respective deflection angles of the outer segments can be reduced, since, depending on the application, a lower resolution may be sufficient for some sub-areas.

In a further embodiment, the light pulses are first emitted in the middle segment and then in the first outer segment and / or the second outer segment. At the beginning of a measurement cycle, light pulses can thus first be emitted into the middle segment, since objects in the direction of travel of the motor vehicle are more relevant than objects that are arranged on the side, especially in ferry operation. Thus, in particular during the first deflections of the deflection unit within a measurement cycle, light pulses can initially only be emitted at deflection angles of the middle area. Light pulses are only emitted at the deflection angles of the outer segments after light pulses have been emitted at a predetermined or predeterminable number of deflection angles of the middle segment. Thus, in addition to reducing the amount of time the security of a measurement can be increased since it ensures that objects with a probably higher priority can be recognized more quickly.

In a further embodiment, a current deflection angle of the deflection element is determined and the light source is controlled as a function of the determined deflection angle and / or the activation of the light source with the deflection of the

Deflection element synchronized. In this way it can be ensured that the light pulses are emitted at the correct times, so that the light pulse is deflected accordingly by the deflection element when a certain deflection angle is reached.

In addition, in one embodiment, a period of time is determined on the basis of the current deflection angle and the closest deflection angle for emitting a light pulse, after which the deflection unit will reach the closest deflection angle for emitting a light pulse, and the light pulse is emitted after the expiry of the time period. By determining the closest deflection angle for emitting a light pulse and determining a time period associated therewith, the next measurement, that is to say the emitting of a light pulse, as well as the

Receiving the reflected light pulse, be delayed. It can thus be ensured that the light pulse is emitted only at predetermined deflection angles. In particular, this can prevent multiple light pulses from being emitted at deflection angles.

In a further embodiment, a first and a second outer deflection angle are assigned to each segment. During the first deflection in the first or the second deflection direction, a light pulse is emitted within a measuring cycle at the first or second outer deflection angle and during the subsequent deflections in the first or second deflection direction, a light pulse is emitted at the adjacent deflection angle, in the inside no light pulse has been emitted in the respective measuring cycle. In other words, within a measurement cycle, light pulses are first emitted in the individual segments at the outer deflection angles and, in the subsequent deflections of the deflection element, the deflection angles in the direction of the center of the

Segment. The measurement duration of a measurement cycle can be further reduced with such a scanning pattern. Another aspect of the invention relates to a computer program product

Program code means, which are stored on a computer-readable medium, for the method according to the preceding aspect or an advantageous

Embodiment to perform when the computer program product is processed on a processor of an electronic computing device.

Another aspect of the invention relates to an optoelectronic sensor for a

Motor vehicle which is used to carry out a method according to one of the

previous claims is designed.

Another aspect of the invention relates to a motor vehicle with an optoelectronic sensor. In particular, the motor vehicle is designed as a passenger car.

Advantageous embodiments of the method are to be regarded as advantageous embodiments of the optoelectronic sensor and of the motor vehicle. The

The optoelectronic sensor and the motor vehicle have objective ones

Features that enable the implementation of the method or an advantageous embodiment thereof.

Further features of the invention result from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures are not only in the respectively specified combination but also in others

Combinations that can be used alone without leaving the scope of the invention. Embodiments of the invention are thus also to be regarded as encompassed and disclosed, which are not explicitly shown and explained in the figures, but which can be derived from and can be generated from separate combinations of features from the embodiments explained. Versions and combinations of features are also to be regarded as disclosed, which therefore do not have all the features of an originally formulated claim. In addition, designs and combinations of features, in particular by the embodiments set out above, are to be regarded as disclosed, which go beyond or differ from the combinations of features set out in the claims.

Exemplary embodiments are explained below using schematic drawings. Show:

Fig. 1 shows a motor vehicle according to an embodiment of the present invention

Invention, which a driver assistance system with a

has optoelectronic sensor;

2 shows a schematic illustration of the optoelectronic sensor;

Fig. 3 shows a time sequence of with a transmitter of the

optoelectronic sensor emitted light pulses according to a first embodiment of the prior art;

FIG. 4 shows a frequency distribution of the emitted light pulses according to FIG. 3 in

Dependence on a deflection angle of a deflection element of the optoelectronic sensor;

5 shows a schematic flow diagram of a method for operating the optoelectronic sensor;

Fig. 6 shows a time sequence of with a transmitter of the

optoelectronic sensor emitted light pulses according to a first embodiment of the invention;

7 shows a further illustration of the chronological sequence of emitted signals

Light pulses according to FIG. 6;

8 shows a chronological sequence of with a transmitting device of the

optoelectronic sensor emitted light pulses according to a second embodiment of the prior art;

FIG. 9 shows a frequency distribution of the transmission times according to FIG. 8 in

Dependence on the angle of the deflection unit of the optoelectronic sensor; 10 shows a chronological sequence of light pulses emitted by a transmission device of the optoelectronic sensor according to a second embodiment of the invention;

Fig. 1 1 is an enlarged view of the time sequence of emitted

Light pulses according to FIG. 10;

12 shows a further illustration of the time sequence of transmitted signals

Light pulses according to FIG. 10;

13 shows a time sequence of with a transmitting device of the

optoelectronic sensor emitted light pulses according to a third embodiment of the invention;

14 shows a further illustration of the time sequence of transmitted signals

Light pulses according to FIG. 13; and

15 is an enlarged representation of the time sequence of transmitted

Light pulses according to FIG. 14.

In the figures, the same and functionally identical elements are the same

Provide reference numerals.

1 shows a top view of a motor vehicle 1 according to an embodiment of the present invention. In the present case, motor vehicle 1 is designed as a passenger car. The motor vehicle 1 comprises a driver assistance system 2, which serves to support a driver of the motor vehicle 1 when driving the motor vehicle 1. With the driver assistance system 2, for example, an object 3, which is located in an environment 4 of the motor vehicle 1, can be detected. If the object 3 is detected, which is located in a route of the motor vehicle, the driver assistance system 2 can issue a warning to the driver. Furthermore, the driver assistance system 2 can be used to intervene in the steering, the brake system and / or the drive motor in order to avoid a collision with the object 3. The driver assistance system 2 includes a for detecting the object 3

optoelectronic sensor 5. The optoelectronic sensor 5 can be designed as a lidar sensor. The optoelectronic sensor 5 is preferably designed as a laser scanner. The optoelectronic sensor 5 comprises a transmission device 6, by means of which light pulses can be transmitted as a transmission signal. This is illustrated here by arrow 8. With the transmitter 6, the light pulses can be emitted in a predetermined surrounding area W. For example, the light pulses can be emitted in a predetermined horizontal surrounding area. The optoelectronic sensor 5 further comprises one

Receiving device 7, by means of which the light pulses reflected by the object 3 can be received again. This is illustrated in the present case by arrow 9.

In addition, the optoelectronic sensor 5 comprises a computing device 10, which can be formed, for example, by a microcontroller, a digital signal processor or an FPGA. The computing device 10 can be used to control the transmitting device 6 for emitting the light pulses. In addition, the

Computing device 10 evaluate signals of the receiving device 7, which with the

Receiving device 7 are generated on the basis of the received light pulses. Finally, the driver assistance system 2 comprises an electronic control unit 11, with which corresponding control signals can be output as a function of the object 3 detected with the optoelectronic sensor 5.

FIG. 2 shows a schematic illustration of the optoelectronic sensor 5. The transmitting device 6 of the optoelectronic sensor 5 has a light source 12. The light source 12 can be formed, for example, by one or more laser diodes. In addition, the transmitting device 6 has a deflection unit 13, by means of which the light pulses emitted by the light source 12 can be deflected. The deflection unit 13 has a deflection element, which with an actuator in a

periodic vibration is offset. Here, the deflection element is deflected periodically in succession in a first and a second deflection direction. The deflection element can be controlled with the actuator so that it performs a periodic oscillation with a frequency of several kHz, in particular 3.5 kHz. With the aid of the computing device 10, the light source 12 can be controlled to emit the light pulses. For this purpose, the control device 10 can transmit a control signal to the light source 12, by means of which the light source 12 is activated for a predetermined period of time. The light source 12 also transmits a signal to the receiving device 7 which describes the time at which the light pulse was emitted. If the light pulse reflected by the object 3 is then received with the receiving device 7, a corresponding signal can be transmitted to the computing device 10, which describes the time of reception of the light pulse. Thus, the

Computing device 10 determines the distance between the optoelectronic sensor 5 and the object 3 on the basis of the transit time between the emission of the light pulse and the reception of the light pulse reflected by the object 3.

In addition, the deflection unit 13 can be used to transmit a signal to the computing device 10, which describes the current position of the mirror element or a current deflection angle α of the mirror element at the time the light pulse is emitted.

In the case of the optoelectronic sensors 5 known from the prior art according to FIG. 3, the light source 12 is activated at fixed intervals. The deflection element of the deflection unit 13 oscillates periodically. The fact that the deflection element has a lower angular velocity when it is deflected in the areas with maximum deflection or at the reversal points, results in

Sending light pulses at fixed intervals at the edge areas a higher density of measuring points. 3 shows a diagram which shows a chronological sequence of light pulses emitted by the transmitting device 6. The time t is plotted on the abscissa and the deflection angle a of the deflection element is plotted on the ordinate. In the present case, the deflection element swings in an angular range between a deflection angle α of -14 ° and a deflection angle α of + 14 °. The

Deflection element can vibrate at a frequency of 3.5 kHz. Within the predetermined surrounding area W, which is to be scanned in the area 4 of the motor vehicle 1, a scanning resolution of 0.1 ^{0 is to be} achieved. For this purpose, the light source 12 is driven at a frequency of 34 kHz. In the present case, a time period of approximately 24 ms is required to complete all discrete scanning angles in the

Area W to be measured.

FIG. 4 shows a frequency distribution of the light pulses, which were emitted within a measurement cycle within a measurement cycle, over the deflection angle of the

Deflection element, in which light pulses are emitted in one measurement cycle, according to FIG. 3. The deflection angle α is plotted on the abscissa and the number A of light pulses is plotted on the ordinate. It can be seen here that at the edge regions or at the reversal points of the oscillating mirror element, which in the Range of -14 ° and + 14 °, multiple light pulses are emitted. In the present case, up to 23 light pulses are emitted in the range of -14 ° and in the range of + 14 °. This leads, for example, to scanning angles in the surrounding area W, which are assigned to these deflection angles a, being illuminated with a higher intensity. This can be particularly critical with regard to eye safety.

FIG. 5 shows a schematic flow diagram of a method for operating an optoelectronic sensor 5 according to an embodiment of the present invention. The method is started in a step S1. In a step S2, a plurality of segments 16a to 16r are determined in a predetermined angular range 15 in which the deflection element is deflected (see FIG. 6). These segments 16a to 16r can be determined dynamically. It can also be provided that previously determined segments 16a to 16r are used. In a step S3, the discrete scanning angles within the surrounding area W in the surrounding area 4 are determined, which are to be scanned or into which the light pulses are to be emitted. Each of these discrete scanning angles then becomes one

Deflection angle assigned to the deflection element. The deflection angles describe those deflection angles α of the deflection element at which a light pulse is to be emitted. Furthermore, an array can be determined in which a first value is entered for each of the determined deflection angles. The first value can be, for example, the value zero or the value "False".

The current deflection angle α of the deflection element is determined in a step S4.

A corresponding signal can be received here by the deflection unit 13. The current deflection angle α can also be determined on the basis of a control signal with which the actuator of the deflection unit 13 is controlled. In a step S5, depending on the current segment 16a to 16r and depending on the

determined deflection angle determines the closest deflection angle at which a light pulse is emitted. The deflection angle can be determined on the basis of the array. In a step S6, a waiting time td is determined, after which the deflection element will reach the closest deflection angle. In a step S7, a loop is run through until the waiting time td has elapsed.

As soon as the waiting time td has elapsed, the light source 12 is activated in a step S8 to emit the light pulse. The light pulse reflected by the object 3 is then received and, based on the transit time, the distance between the optoelectronic sensor 5 and the object 3 are determined. In a step S9, the deflection angle at which the light pulse was emitted is assigned a second value in the array. The second value can be, for example, the value one or "True". In a step S10 it is then checked whether a light pulse has been emitted for all determined transmission deflection angles. If this is not the case, the method is continued again with step S4. If this is the case, the measuring cycle is ended in a step S1 1. In a further step S12, the transmission deflection angles can already be determined for a further measurement cycle, which can be started with step S13.

Fig. 6 shows the chronological sequence of the transmission times 14, at which with the

Transmitting device 6 of the optoelectronic sensor 5, the light pulses are emitted. The optoelectronic sensor 5 is operated according to a method according to the invention. It can be seen here that the angular range 15 is divided into the plurality of segments 16a to 16f. In the present case, the angular range 15 is divided into six segments 16a, 16b, 16c, 16d, 16e and 16f. In addition, reversal angles 17a, 17b are shown, at which the deflection element reverses their movement. The first reversal angle 17a is approximately + 14 ° and the second reversal angle is approximately -14 °. The angular range 15, in which segments 16a to 16f are defined, is predetermined by the reversal angles 17a, 17b. In the present case, all segments 16a to 16f are selected to be of the same size.

It can be seen in FIG. 6 that only one light pulse was emitted at each discrete deflection angle of the deflection element. In particular, it can be seen that the

Distinguish time intervals between the transmission times 14. The light source 12 is therefore not controlled periodically. In particular, this enables a measurement cycle to be carried out over a period of approximately 13.5 ms. It takes into account that between sending two

successive light pulses a pause of 29.4 ms is observed. This corresponds to the frequency of 34 kHz according to the example in FIG. 3. It shows that compared to the operation according to the prior art of the optoelectronic sensor 5, which is shown in FIG. 3, the duration for a measurement cycle is almost halved can.

7 shows in the upper part the waiting times td between the emission of the respective light pulses. The time t is plotted on the abscissa and the waiting time td on the ordinate. The lower part of FIG. 7 shows how the segments 16a to 16f are processed in sequence over time. Here are the ordinates Segments 16a to 16f are plotted, segment 16a in the lower part of FIG. 7 being designated 1, segment 16b being 2, etc. In particular, it can be seen there that, for example, there is initially a long waiting time td between the first two light pulses in segment 16f, since segment 16f contains the reversal angle 17b. in the

Reversal angle 17b the direction of deflection is reversed. For this purpose, the actuator is excited with an excitation signal that is opposite to the current deflection direction. As a result, the angular velocity of the deflecting element is first reduced until that

Deflection element is deflected in the opposite direction, the maximum angular velocity of the deflection element being reached only after a certain excitation time. Consequently, the deflection of the deflection element is in segment 16f for a relatively long time, so that a long waiting time between the two laser pulses is necessary. This is the reverse of segment 16a, here the pairs of light pulses occur in succession with almost no waiting time td, since in particular the first light pulse is emitted at the reversing angle 17a. At the end of the measuring cycle, the situation is exactly the opposite. Here, the waiting times td between the light pulses in segment 16f become shorter, while the waiting times td between the light pulses in segment 16a increase.

8 shows a further chronological sequence of light pulses, in which the light pulses are emitted at fixed intervals according to a method from the prior art. In this example, the light pulses are emitted at a frequency of 100 kHz. The deflection element oscillates at a frequency of 3.485 kHz between a deflection angle α of -41 ° and a deflection angle α of +41 °. It takes about 46.5 ms until all angular positions have been measured at least once. 9 shows the associated frequency distribution. It can be seen here that at the

Edge areas or at the reversal points at -41 ° and +41 ° for the deflection angles, angular positions, multiple light pulses were emitted. In this case, up to 52 light pulses are emitted at these deflection angles a.

In comparison to this, FIG. 10 shows the chronological sequence of the light pulses, the optoelectronic sensor 5 being operated according to a method according to the invention. Here the angular range 15 extends from -37.5 ° to +37.5 °. Here too

takes into account that between sending two consecutive

Light pulses a duration of about 10 ps is maintained. This corresponds approximately to the frequency of 100 kHz according to the example in FIG. 8. It can be seen here that the measuring cycle can be carried out within a time period of only 26.1 ms. In the example of FIG. 10, the angular range 15 is divided into 18 segments 16a, 16b, 16c, 16d, 16e, 16f, 16g, 16h, 16i, 16j, 16k, 16I, 16m, 16n, 16o, 16p, 16q and 16r . In this case, not all segments 16a to 16r have an equal number of deflection angles for emitting light pulses. In the present case, the first outer segment 16a and the second outer segment 16r have fewer deflection angles for emitting light pulses than the middle segments 16b to 16q of the angular range 15. The outer ones

Segments 16a and 16r each encompass a partial angle range of 1.5 °. The middle segments 16b to 16q each encompass a partial angle range of 4.5 °. For example, 30 deflection angles can then be assigned in the outer segments 16a and 16r and 90 transmission deflection angles in the middle segments 16b to 16q. Furthermore, the size of the segments 16a to 16r is dependent on the maximum possible scanning resolution or the maximum possible number of light pulses per segment 16a to 16r. In addition, this in turn depends on the maximum possible in time

Transmission of the light pulses and the maximum possible laser repetition frequency. It can be seen in FIG. 10 that exactly one light pulse was emitted at all required deflection angles. This means that a significantly shorter total time is required, which is now around 26.1 ms. A scanning resolution of 0.05 ° is realized. FIG. 11 shows a detailed view from FIG. 10 for a partial angle range 15 from -18 ° to approximately -19 °.

12 shows in the upper part the waiting time td on the ordinate between the light pulses over the time t. The lower part of FIG. 12 shows how light pulses are sequentially emitted in the deflection angles of the segments 16a to 16r. The segments 16a to 16r are plotted on the ordinate. It can be seen in particular that light pulses are emitted first at deflection angles of the second outer segment 16r before light beams are emitted at deflection angles of the first outer segment 16a. It can be seen in particular in a last temporal part of the measurement cycle that light beams are emitted only at deflection angles of the middle segments 16b to 16q, since the two outer segments 16a, 16r have a smaller number of deflection angles and all of them at all deflection angles of the two outer segments 16a, 16r light pulses were emitted.

13 shows a further possibility of how the light pulses can be emitted in time. In particular, the light pulses can first be emitted in one of the middle segments 16b to 16q and then emitted in the first outer segment 16a and / or the second outer segment 16r.

In particular, it can be seen that in each of the middle segments 16b to 16q

Light rays starting at a first and a second outer deflection angle in Towards the center of the segment and that at the beginning of the

Measurement cycle no light pulses are emitted at the deflection angle of the two outer segments 16a and 16r. As a result, a constantly successive sequence of light pulses can be implemented for the middle segments 16b to 16q.

14 shows in the upper part the waiting times td between the light pulses over the time t and in the lower part as in the deflection angles of the segments 16a to 16r sequentially over the time light pulses are emitted according to the example from FIG. 13. that at deflection angles of the two outer segments 16a, 16r, light pulses are only emitted in a second third of the duration of the measuring cycle. 15 shows a detailed view of FIG. 14.

Claims

1. Method for operating an optoelectronic sensor (5) for a

Motor vehicle (1), in which during a measurement cycle with a

Transmitting device (6) of the optoelectronic sensor (5) for detecting at least one object (3) light pulses in a surrounding area of the

Motor vehicle are emitted and light pulses reflected on an object (3) are received with a receiving device (7) of the optoelectronic sensor (5), the emitted light pulses being deflected into a plurality of deflection angles of the surrounding area with a deflection unit (13) of the transmission device (6) are, the deflection unit (13) for deflecting the light pulses having a periodically oscillating deflection element, which within a

predetermined angular range (15) is deflected,

characterized in that

the predetermined angular range (15) is divided into a plurality of segments (16a to 16r),

that the deflection element is deflected at least once in a first deflection direction and at least once in a deflection direction opposite to the first deflection direction within a measurement cycle,

that a first deflection angle is assigned to each segment (16a to 16r) when deflecting in the first deflection direction and a second deflection angle when deflecting in the second deflection direction and

that a light pulse is emitted in each deflection in a deflection direction in at least one segment (16a to 16r).

2. The method according to claim 1,

characterized in that

For each deflection of the deflection element for the respective segments (16a to 16r), a deflection angle for emitting the light pulse is determined, the deflection angle for emitting the light pulse for the respective segments (16a to 16r) of the successive deflections within one Differentiate measurement cycle from each other.

3. The method according to claim 2,

characterized in that

for each segment (16a to 16r) a plurality of deflection angles for the

Emission of the light pulse is determined and only one light pulse is emitted within a measurement cycle at each of the deflection angles.

4. The method according to any one of the preceding claims,

characterized in that

the deflection element is deflected periodically between a first reversal angle (17a) of the angular range (15) and a second reversal angle (17b) of the angular range (15) and the angular range (15) into at least one central segment (16b to 16q), a first outer segment ( 16a) and a second outer segment (16q) is divided, the first outer segment (16a) being the first

Reversal angle (17a) and the second outer segment (16r) comprises the second reversal angle (17b).

5. The method according to claim 4,

characterized in that

the first outer segment (16a) and the second outer segment (16r) comprise fewer deflection angles than the at least one middle segment (16b to 16q).

6. The method according to claim 4 or 5,

characterized in that

the light pulses are first emitted in the middle segment (16b to 16q) and then in the first outer segment (16a) and / or the second outer segment (16r).

7. The method according to any one of the preceding claims,

characterized in that

a current deflection angle (a) of the deflection element is determined and the

Light source (12) is controlled as a function of the specific deflection angle (a) and / or the control of the light source (12) with the deflection of the

Deflection element is synchronized.

8. The method according to claim 7,

characterized in that

based on the current deflection angle (a) and the closest deflection angle for emitting a light pulse, a time period (td) is determined, after which the deflection unit (13) will reach the closest deflection angle for emitting a light pulse, and the light pulse is emitted after the expiry of the time period becomes.

9. The method according to any one of the preceding claims,

characterized in that

a first and a second outer deflection angle are assigned to each segment, a light pulse is emitted during the first deflection in the first or the second deflection direction within a measurement cycle at the first or second outer deflection angle and during the subsequent deflections in the first or second deflection direction a light pulse is emitted at the adjacent deflection angle, in which no light pulse has yet been emitted within the respective measurement cycle.

10. Computer program product with program code means, which on a

computer-readable medium are stored to carry out the method according to any one of claims 1 to 1 1 when the computer program product is processed on a processor of an electronic computing device.

1 1. Optoelectronic sensor (5) for a motor vehicle (1) which is designed to carry out a method according to one of the preceding claims.

12. Motor vehicle (1) with at least one optoelectronic sensor (5)

Claim 1 1.