DE102017221529B4 - Photoelectric sensor - Google Patents

Abstract

Optoelectronic sensor (100), in particular LiDAR macro scanner, comprising
- A plurality of transmission boards (132), each transmission board (132) having at least one optical transmission unit,
- At least one holding device (120, 130) into which the transmitter boards (132) are inserted,
wherein a measuring range (200) of the sensor (100) is determined by the alignment of the transmitter boards (132) to one another,
in which
the holding device (120, 130) is adaptable in such a way that the relative alignment of the transmitter boards (132) to one another can be changed, whereby a measuring range (200) and / or a resolution of the sensor (100) can be adapted, characterized in that a curvature, in particular a vertical and / or a horizontal curvature to which the holding device (120, 130) can be adapted.

Description

The invention relates to an optoelectronic sensor, in particular a LiDAR macro scanner with a plurality of transmission boards. The optoelectronic sensor is designed in such a way that a measuring range (field-of-view) can be set adaptively.

State of the art

The US 2011 216 304 A1 shows a generic optoelectronic sensor which is designed as a biaxial LiDAR macro scanner. The sensor comprises several circuit boards that are plugged into a motherboard and thus fixed. Individual lasers or detectors are arranged on each of the boards. Each of the boards defines a measuring plane of the sensor.

Different driving environments, especially in the context of highly automated or autonomous driving, place different demands on the system of sensors that constantly monitor the vehicle environment. A type of sensor typically used to detect the surroundings is a laser scanner, in particular a LiDAR macro scanner. Ideally, only a single type of macro scanner is built into the system, for reasons of profitability, for example during installation, reading and production.

The sensors known from the prior art are, with regard to the measurement range, also referred to as field-of-view (FoV for short), and the measurement resolution is usually designed in such a way as to address a certain type of driving scenario.

For example, sensor types are known that are designed to detect high-resolution images over short distances (e.g. 5-10 m). However, with such sensors it is almost impossible to detect an object more than 60 m away. According to the state of the art, a higher resolution is achieved by installing several transmitting and receiving boards. The more transmitter and receiver boards that are installed, the larger, heavier and usually more expensive the system becomes. Another problem arises, e.g. when a vehicle with a LiDAR sensor (macro scanner) moves on a road with an incline. In this case, many measuring levels of the sensor will hit the ground and thus not provide any usable measurement data.

In order to meet the various requirements with just one sensor, it should be possible to adapt the vertical Field of Views (FoV) or the resolution of the vertical FoV to the driving scenario. The object of the present invention is accordingly the optimal use of an existing sensor structure, in particular the existing transmitter boards, in order to achieve different vertical fields of views and resolution.

The US 2011/0216304 A1 discloses a lidar-based 3D point cloud measurement system that includes a base, a housing, a plurality of photon transmitters and photon detectors contained in the housing, a rotary motor that rotates the housing about the base. In certain variants, the system comprises a vertically aligned motherboard, thin circuit boards and ceramic hybrids for the selective mounting of emitters and detectors and a common D-shaped lens arrangement.

The WO 96/034434 A1 describes a laser diode assembly with a laser diode unit mounted directly on a compact thermoelectric cooler that is mounted on a heat sink.

The US 8761594 B1 shows methods for providing spatially dynamic lighting for camera systems. A spatially dynamic lighting source makes it possible to illuminate only the desired objects in the field of view of the camera and thereby to reduce the total amount of light required by the illumination source. The spatially dynamic lighting source can consist of an arrangement of lighting elements and a control component. Each lighting element in the lighting arrangement can contain a light-emitting element in combination with an optical element.

The DE 102016108422 A1 shows a lidar field system with a controllable field of view. This is achieved by dynamically changing a relative position between a laser array and a lens that fans out the laser beams.

The WO 2017/101988 A1 discloses a surveying instrument that includes a housing, an optical system having an optical axis, a table attached to the housing, and an optical component. The optical system can be adapted to receive and / or send light. The optical component is at or near the optical axis. The received and / or transmitted light passes through the optical component. The table includes an actuator which is arranged to act on the optical component to move it. The actuating element can be designed such that, in response to a change in temperature, a displacement of the optical Component is caused relative to the chassis along the optical axis.

Disclosure of the invention

• - eine Mehrzahl von Sendeplatinen, wobei jede Sendeplatine zumindest eine optische Sendeeinheit aufweist,
• - mindestens eine Halteeinrichtung, in die die Sendeplatinen eingesteckt sind, wobei ein Messbereich des Sensors durch die Ausrichtung der Sendeplatinen zueinander bestimmt wird.

According to a first aspect of the invention, an optoelectronic sensor, in particular a LiDAR macro scanner, is proposed. The optoelectronic sensor includes

• - A plurality of transmitter boards, each transmitter board having at least one optical transmitter unit,
• - At least one holding device into which the transmitter boards are inserted, a measuring range of the sensor being determined by the alignment of the transmitter boards with respect to one another.

According to the invention, the holding device can be adapted, for example by applying a control signal, in such a way that the relative alignment of the transmitter boards to one another can be changed, as a result of which a measuring range and / or a resolution of the sensor can be adapted.

Due to the adaptability of the relative alignment of the sending boards, a measuring range and / or a resolution of the sensor can be changed in a targeted manner and optimally adapted to the current requirements and conditions. The adaptability of the relative alignment of the sending boards is achieved according to the invention in that a holding device into which the sending boards are inserted is adapted, in particular by changing a curvature, in particular a vertical and / or horizontal curvature, of the holding device.

The inventive design of an optoelectronic sensor results in the advantages that the measurement area (field of view), in particular the discrete, vertical field of view, can be adapted to the current driving scenario. Furthermore, the resolution within the vertical field of views can be adapted to the current driving scenario. This results in an optimal use of the existing components of an existing sensor and, for example, no different sensors or sensor components have to be provided for different driving scenarios. Because fewer components have to be installed overall, the sensor can be made more cost-effective, lighter and smaller.

In a particularly advantageous embodiment, the holding device is preset in such a way that under normal conditions (i.e. without additional heating or cooling, for example) the transmitter boards are aligned with one another, which results in a measurement range (field of view) and / or a resolution that most driving situations is appropriate, e.g. for urban driving. In particular, a certain curvature or bending of the holding device can be preset.

The holding device is preferably a plate or circuit board which is essentially rectangular and has a plurality of slots or openings into which the transmission circuit boards are inserted. The holding device is preferably arranged in such a way that it is essentially parallel to a main axis or

The axis of rotation of the sensor is arranged. In this context, essentially means that there is no exact parallelism, since the holding device preferably has an in particular changeable curvature or bend by means of which the alignment of the inserted transmitter boards is adapted to one another.

The sensor preferably has a housing, the holding device and the transmitter boards being arranged within the housing.

In a preferred embodiment of the invention, the holding device has at least one bimetal element or is designed as a bimetal element. A bimetal element (also referred to as a thermal bimetal) usually comprises two layers of different metals that are connected to one another in a materially or form-fitting manner. The change in shape with a change in temperature is characteristic. This manifests itself as a bending. The cause is the different coefficient of thermal expansion of the metals used. For example, the holding device can be designed as a bimetallic plate. Furthermore, the holding device has at least one heating device and / or at least one cooling device. The bimetal element is heated or cooled by means of the heating device or the cooling device. Due to the effect that different metals (bimetal) experience volume changes of different magnitude when the temperature changes, a curvature of the holding device changes when the temperature changes. The transmission boards inserted into the holding device move towards or away from one another due to the change in curvature, so that the measuring range of the sensor is narrowed or widened.

In a further preferred embodiment of the invention, several holding devices are provided, at least one holding device having two or more thermally insulated part areas. Each sub-area in turn has a bimetal element. The sub-areas can be cooled and / or heated independently of one another educated. This embodiment has the advantage that, through different heating or cooling of the sub-areas, a tilt angle of the sensor measurement area can also be changed and can be adapted in a defined manner by appropriate adaptation of the temperatures of the sub-areas.

According to a second aspect of the invention, a method for adapting a measuring range of an optoelectronic sensor is proposed, the optoelectronic sensor being designed as described above. According to the invention, the alignment of the transmitter boards with respect to one another is adapted by adjusting a curvature of the holding device.

By changing a radius of curvature of the holding device, a resolution and / or a range of the sensor is preferably changed or set.

If the optoelectronic sensor is designed in such a way that at least one holding device has two or more thermally insulated partial areas, each partial area in turn having a bimetal element, a preferred embodiment of the method provides that the partial areas are cooled and / or heated independently of one another , whereby a tilt angle of the measuring range of the sensor is set by the selective heating and / or cooling of at least two different partial areas of the holding device.

A control signal for setting a curvature of the holding device, that is to say for setting a specific relative orientation of the transmission boards, is preferably generated as a function of a current vehicle speed and / or a road gradient and / or location information. The measuring range and / or the resolution of the optoelectronic sensor are therefore adapted depending on the current driving situation by aligning the transmitter boards accordingly.

It can happen that, during the operation of the sensor, the temperature inside the housing of the sensor is not the operating temperature required to set a desired curvature or bend of the holding device, in particular comprising a bimetal element or designed as a bimetal element. This can occur, for example, when starting the vehicle after standing for a long time. In this case, various compensation mechanisms can be used. For example, more energy can be supplied to the bimetal until the necessary expansion is achieved. Alternatively, a mechanically opposite compensation (opposite behavior to the bimetal used) can be installed as a temperature compensator at the pivot points in order to compensate for the global temperature fluctuations. Pivot points are the points at which the holding device is positively / cohesively connected to a sensor chassis. A combination of both methods is also conceivable. For this purpose, a temperature sensor is preferably arranged in the interior of the housing of the sensor, which is connected to a corresponding control circuit.

Figure list

• 1 shows a lidar macro scanner according to the prior art in side view.
• 2 shows a schematic diagram of a holding device which has two different metals.
• 3 shows various driving scenarios schematically. On the right-hand side, the required measuring ranges for the various driving scenarios are shown schematically.
• 4th shows a representation of a second possibility of aligning the blanks with a second holding device according to a possible embodiment of the invention.
• 5 shows a schematic diagram of the effect of the adaptive field of view adaptation by aligning the transmission boards according to a possible embodiment of the invention.
• 6th represents an exemplary embodiment of a method according to the invention for adapting a measuring range of an optoelectronic sensor according to the invention as a flow chart.

In the following description of the exemplary embodiments of the invention, the same elements are denoted by the same reference numerals, and a repeated description of these elements may be dispensed with. The figures represent the subject matter of the invention only schematically.

1 shows a sensor 10 according to the prior art, for example in the US 2011 216 304 A1 is described. The sensor 10 includes a motherboard 20th into which a plurality of transmit / receive boards 32 are plugged in. The transmitter boards have emitters that emit light in a rear area of the sensor. There the light pulses are reflected by a mirror (not shown) and through a lens 50 directed to the outside. Pulses reflected from objects in the vicinity are passed through another lens over the mirror 40 on detectors on the transmitter / receiver boards 32 directed. The motherboard 20th and the mirror 40 are in one common framework 22nd arranged of the motherboard 20th and the mirror 40 holds and provides alignment. The frame 22nd is on a platform 14th attached. The platform 14th can be designed to be rotatable.

The main board is designed as a flat plate that is parallel to an axis of rotation of the sensor 10 is aligned. The send / receive boards 32 are in openings on the motherboard 20th inserted and arranged in a fan-like manner to one another. In the variant shown here, the send / receive boards generate 32 a measurement area (field of view) that extends 10 degrees above and 30 degrees below a horizontal line. The central, horizontal plane of the measurement area (field of view) thus extends approximately at the level of the ninth transmitter / receiver board 38 from above. Each transmit / receive board 32 is opposite the next below or above transmitter / receiver board 32 inclined by approx. 11/3 degrees. This relative orientation of the send / receive boards 32 can be varied depending on the desired training of the field of view. Are the send / receive boards 32 however, once aligned with each other, so will the transmit / receive boards 32 fixed according to the state of the art and the measuring range (field of view) and the resolution are fixed. The sensor 10 usually has a sensor housing, which, however, is not shown here.

In 2 a) is a holding device 120 an optoelectronic sensor 100 shown schematically according to the invention. The holding device 120 is designed as a convex bimetal plate and has a certain preset curvature. A combination of two metals with as different thermal expansion coefficients as possible can be used as the bimetal, for example zinc and steel or brass and iron. Alternatively, the holding device can also have a concave design. The holding device 120 has a plurality of openings 124 on. In each of the openings 124 is a transmitter board 132 plugged in. The holding device 120 has a heating and / or cooling device 150 on, through which a defined temperature of the holding device can be set. Heating can take place, for example, by means of a heating resistor, and cooling by means of a Peltier element. A change in temperature and thus a change in the curvature of the holding device 120 is triggered, for example, when a certain speed of the vehicle, which has the sensor, is over or undercut. Alternatively or additionally, the curvature of the holding device can be changed 120 depending on a global position, determinable for example by satellite navigation such as GPS or the like, or depending on a current road incline. The heating and / or cooling device 150
Can be attached directly to the holding device, as in the example shown 120 be arranged. Alternatively, the heating and / or cooling device 150 separate from the holding device 120 be provided within a sensor housing (not shown).

If a vehicle that is equipped with an optoelectronic sensor designed according to the invention moves in an urban environment, the preset curvature (“zero” position) of the transmission boards can 132 be used. This corresponds to no change in temperature on the holding device 120 . If the vehicle registers, for example by means of a GPS receiver, that it is moving from an urban environment to a motorway / country road, the vertical field of view (vFoV) is set to a specific temperature assigned to the new driving situation by means of defined heating or cooling of the holding device and the resulting change in the relative orientations of the transmitter boards is aligned according to a further predefined orientation. This change can also be triggered, for example, by a change in speed or by map information. By heating or cooling the holding device 120 its curvature can be changed in such a way that the vertical field of view is optimally adapted to the current driving situation.

2 B) shows an enlarged section A of the holding device 120 out 2 a) . The holding device 120 includes two metal plates 121 and 122 , which are formed from different metals and therefore when the holding device is heated or cooled 120 expand or contract differently. The arrows 222 , 212 illustrate the effect of a heat input on the curvature of the holding device 120 . The metal plate 121 expands more than the metal plate due to the heat input 122 . The initially convexly curved holding device 120 thus loses its convexity (curvature) when heated - the radius of curvature increases with increasing temperature. This creates the individual, evenly formed transmission boards 132 moved towards each other. This increases the resolution of the sensor.

3 shows various driving scenarios schematically. 3 a) shows a vehicle 50 that with an optoelectronic sensor 100 Is provided. The sensor 100 has a measurement area (Field of View) 200 on. The measuring range 200 has a plurality of measuring planes 201-205 , of which only five are shown here as examples. The vehicle 50 moves in an urban driving scenario, for example in city traffic. A vehicle in front 60 such a driving scenario is typically at a short distance from the vehicle 50 . Of the Measuring range 200 is designed such that the vehicle 60 is optimally recorded. The design of the measuring range 200 is decisive here on the relative alignment of the transmission boards 132 determines who the measuring planes 201-205 establish.

In 3 b) a driving scenario is shown which corresponds to driving on the motorway. The vehicle in front points here 60 typically a greater distance from the vehicle 50 so in an urban driving situation like in 3 a) shown. The resolution of the optoelectronic sensor is at this greater distance 100 when compared to the situation 3 a) unchanged field of view, which is due to the greater vertical distance between the measuring planes 201 - 205 is conditional. The greater distance can also cause bumps 75 or slopes of the road 70 lead to some measurement levels 202-204 the vehicle 60 no longer capture at all, but the road 70 to meet.

In 3 c) are exemplary three different configurations 200 , 200 ' , 200 " for the measuring range (field of view) of the sensor 100 shown, for different driving situations, for example those in the 3 a) and 3 b) the driving scenarios shown are adapted and optimized. The respective measuring ranges 200 , 200 ' , 200 " are through exemplary five measuring levels 201-205 shown. The example i) represents a measuring range 200 that is optimized for urban driving situations, and that in connection with 3 a) described measuring range 200 corresponds to. Example ii) represents a measurement range optimized for motorways or expressways 200 ' The measuring planes are closer together compared to example i), which leads to a focus at greater distances and to an increased resolution. Example ii) represents a measurement range that is optimized for driving on a sloping roadway 200 " The measuring planes are tilted compared to example i). The one in the 3 c) different configurations shown 200 , 200 ' and 200 " can with a sensor designed according to the invention 100 can be adapted as required without having to make structural changes to the sensor, namely by changing the relative alignment of the transmitter boards 132 is changed, e.g. as in connection with 2 or 5 described.

In 4th is shown schematically how by setting different curvatures of a holding device 120 according to 2 different measuring ranges 200a-200c with one and the same sensor 100 can be achieved. The holding device is shown again on the left and corresponds to that in 2 described holding device, which is designed as a bimetal plate. In a first configuration 120a has the holding device 120 a first preset curvature. The curvature results in a relative alignment of the transmitter boards inserted into the holding device 132 causes the to a first measuring range (field of view) 200a leads. This measuring range 200a is optimized for urban driving scenarios, for example. At the first configuration 120a it can be a presetting, ie a configuration that is performed under normal conditions, in particular without additional heating or cooling, by the holding device 120 is taken. In certain situations, for example after the vehicle has been stationary for a long time or when the ambient conditions are cold, the holding device can be heated or cooled 120 however you still need to do the first configuration 120a adjust.

In a second configuration 120b has the holding device 120 a second curvature. The second curvature is created by a corresponding input of heat, that is to say by heating the holding device 120 set. The second curvature is less than the first curvature. The second curvature results in a relative alignment of the transmitter boards inserted into the holding device 132 causes which leads to a second measurement area (field of view) 200b. This measuring range 200b is optimized, for example, for driving scenarios out of town with increased vehicle speeds.

In a third configuration 120c has the holding device 120 a third curvature. The third curvature is created by a corresponding further increased heat input, that is to say by heating the holding device 120 set. The third curve is less than the second curve. The second curvature results in a relative alignment of the in the holding device 120 inserted transmission boards 132 causes which leads to a third measurement area (field of view) 200c. This measuring range 200c is optimized for driving scenarios on motorways or expressways, for example.

With decreasing curvature of the holding device 120 (synonymous with an increasing radius of curvature) the range and the resolution of the measuring range increases at the expense of vertical expansion. This means the smaller the curvature of the holding device 120 the better distant objects can be detected and resolved. In the case of a high curvature (e.g. in the state of the default setting 120a) on the other hand, objects that are closer to the sensor can be better detected and resolved.

5 shows an alternative embodiment of the invention. In 5 a) the structure is shown schematically. In this version there are two holding devices 120 and 130 provided in which the transmission boards 132 are each plugged in with their opposite ends. Depending on where the second holding device is 130 is attached, i.e. its pivot point 160 has, in this example below the bottom transmitter board 132 , other orientations of the entire assembly can be made. In this way, a global tilt angle of the measuring planes can be set relative to a presetting.

The second holding device 130 In this example, it has two sub-areas that are thermally isolated from one another 135 and 136 on. Both sub-areas are designed as bimetal plates and can be operated independently of one another by means of appropriately arranged heating / cooling devices 151 , 152 be heated or cooled. Becomes the upper part 135 cooled and thus contracts and at the same time becomes the lower sub-area 136 If it heats up and thus expands, a global tilt angle can be set. Both areas 135 , 136 must be thermally insulated from each other if they are made of identical materials. This means that a change in the measuring range (Field of View) can be made according to 3 c) iii) be achieved.

In 3b) is shown schematically in three examples, which measuring ranges 200d and 200e different temperature settings for the sub-areas 135 and 136 surrender. Depending on the setting, there is a larger tilt angle of the measuring planes compared to the presetting 200 , the same temperatures in both sub-areas 135 and 136 corresponds to.

6th shows a method for adapting a measuring range of an optoelectronic sensor according to a possible embodiment of the invention as a flow chart. In one step 300 the surroundings of a vehicle are detected by means of an electro-optical sensor designed according to the invention. In step 320 it is checked whether a driving situation or a driving scenario has changed in such a way that an adaptation of the field of view of the optoelectronic sensor is necessary in order to ensure optimal detection of the environment in a situation-appropriate manner. This check includes, for example, the evaluation of global position data of the vehicle, for example in the form of GPS coordinates. Alternatively or additionally, the check can include an evaluation of current speed data and / or data that characterize the current gradient of the roadway. The speed data or the data that characterize the current gradient of the roadway can be collected and made available, for example, by appropriate sensors in the vehicle. This makes it possible to determine whether the vehicle is in an urban driving situation, for example, or on an expressway, for example. Depending on the driving situation, other requirements can be placed on the measuring range (field of view) of the optoelectronic sensor, for example in connection with 3 was set out.

If the check shows that there has been no change in the driving situation, then the detection of the surroundings is carried out in step 300 continued. If the check shows that there has been a change in the driving situation, then in step 330 the measurement area (field of view) of the optoelectronic sensor is adjusted by changing an alignment of the transmitter boards with respect to one another, for example by adapting a curvature of a holding device into which the transmitter boards are inserted. This can be done, for example, in that the holding device is designed as a bimetallic element, as described above. The curvature of the holding device is determined by heating or cooling to a specific temperature. The relative orientation of the transmission boards inserted into the holding device is determined by the curvature of the holding device. This can be done, for example, in that an assignment of a specific temperature of the holding device to a driving situation is stored in the form of a table and the corresponding temperature is queried and then set. By detecting the current temperature of the holding device and a control loop, it can be ensured, for example, that the temperature of the holding device is kept constant.

Claims (10)

Optoelectronic sensor (100), in particular LiDAR macro scanner, comprising - a plurality of transmitter boards (132), each transmitter board (132) having at least one optical transmitter unit, - at least one holding device (120, 130) into which the transmitter boards (132) are inserted a measuring range (200) of the sensor (100) is determined by the alignment of the transmitter boards (132) to one another, the holding device (120, 130) being adaptable in such a way that the relative alignment of the transmitter boards (132) to one another can be changed, whereby a measuring range (200) and / or a resolution of the sensor (100) can be adjusted, characterized in that a curvature, in particular a vertical and / or a horizontal curvature, of the holding device (120, 130) can be adjusted. Photoelectric sensor (100) according to Claim 1 , characterized in that the sensor (100) has a housing, the holding device (120, 130) and the transmitter boards (132) being arranged within the housing. Optoelectronic sensor (100) according to one of the Claims 1 or 2 , characterized by that the holding device (120, 130) is designed as a bimetal element or has at least one bimetal element and comprises at least one heating device (150, 151, 152) and / or at least one cooling device (150, 151, 152), wherein the bimetal element can be heated or cooled , whereby a curvature of the holding device (120, 130) can be adjusted. Photoelectric sensor (100) according to Claim 3 , characterized in that at least one holding device (130) has two or more thermally insulated partial areas (135, 136), each partial area (135, 136) having a bimetallic element and the partial areas (135, 136) coolable and / or independently of one another are heatable. Optoelectronic sensor (100) according to one of the Claims 2 to 4th , characterized in that the housing has a temperature sensor inside which is connected to a control circuit in such a way that the temperature inside the housing, in particular the temperature of a bimetal element, is kept constant. Method for adapting a measuring range (200) of an optoelectronic sensor (100), wherein the optoelectronic sensor (100) according to one of the Claims 1 to 6th is designed, the measuring range (200) and / or the resolution of the sensor (100) being adapted as a function of the situation by changing an alignment of the transmitter boards (132) to one another, characterized in that an alignment of the transmitter boards (132) to one another is changed, by adapting a curvature of at least one holding device (120, 130) into which the transmitter boards (132) are inserted. Procedure according to Claim 6 , characterized in that the holding device (120, 130) is designed as a bimetallic element or has a bimetal element, the curvature of a holding device (120, 130) into which the transmitter boards (132) are inserted being adapted by cooling or cooling the holding device is heated. Method according to one of the Claims 6 or 7th , wherein the optoelectronic sensor (100) according to Claim 4 is formed, characterized in that a tilt angle of the measuring area (200) is set by selective heating and / or cooling of at least two different sub-areas (135, 136) of the holding device (130). Method according to one of the Claims 6 to 8th , characterized in that a temperature of the holding device (120, 130) is regulated by means of a control circuit. Method according to one of the Claims 6 to 9 , characterized in that a control signal for changing an alignment of the transmitter boards (132) with respect to one another is generated as a function of a current vehicle speed and / or a road gradient and / or location information.

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