JP2018205042A - Laser distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser distance measuring device capable of extending the life of the device while ensuring a distance measuring function. SOLUTION: By switching the output of a laser beam LL according to the external environment information acquired by a distance image sensor control unit 60, for example, it is sufficient for distance measurement such as an inter-vehicle distance, and a suitable output with no waste. It is possible to control so as to maintain the state in which the laser light LL is emitted from the laser light source unit 51. As a result, the life of the laser light source unit 51 and the entire laser distance measuring apparatus 100 can be extended while ensuring the distance measuring function of the distance image sensor 50. [Selection diagram] Figure 2

Description

  The present invention relates to a laser distance measuring device that performs distance measurement using a laser beam in a situation where an external environment may change.

  As an inter-vehicle distance alarm system that issues an alarm when the inter-vehicle distance is close, the scan laser radar is stopped based on information from the vehicle speed sensor, and the sub-sensor is used while the scan laser radar is stopped. When the movement of the preceding vehicle is detected by the above, there is known one that extends the life compared to the case where the scan laser radar is continuously operated by restarting the scan laser radar (see Patent Document 1).

  However, in the case of ranging, such as a vehicle that may move constantly during operation, it is considered necessary to always ensure the measurement of the distance between the vehicles when the laser is on. With regard to the output of the laser, for example, there is a high possibility that measurement is performed with an output that matches the worst condition, that is, always with a large output, and from this point of view, it is considered disadvantageous for extending the life. The fact that the scan laser radar may stop means that there is a time when the measurement of the inter-vehicle distance cannot be ensured, and even if the vehicle is close to stopping, a safety problem may occur. I cannot say that there is no.

JP 11-339198 A

  The present invention has been made in view of the above points, and an object of the present invention is to provide a laser distance measuring device capable of extending the life of the device while ensuring a distance measuring function.

  In order to achieve the above object, a laser distance measuring device according to the present invention is a laser distance measuring device that measures a distance based on a time until a laser beam emitted from a light source is received, and is based on external environment information. The output increase / decrease of the laser light emitted from the light source is switched.

  In the laser range finder described above, by switching the output of the laser beam according to the external environment information, the laser beam is emitted from the light source with a suitable output that is sufficient for distance measurement and without waste. Therefore, it is possible to extend the lifetime of the light source and the entire apparatus while ensuring the distance measuring function.

  In a specific aspect of the present invention, the laser beam is continuously output during operation of the vehicle while being mounted on the vehicle. In this case, during the operation of the vehicle, it is possible to improve the safety of driving the vehicle by continuing the distance measurement.

  In another aspect of the present invention, at least one of a measurement value of the illuminometer, map information, weather information, headlight on / off information, and wiper on / off information is acquired as external environment information. In this case, it is possible to increase the life of the apparatus while ensuring a distance measuring function while maintaining a state in which the increase or decrease of the output of the laser light is maintained in accordance with changes in the external environment such as weather.

  In still another aspect of the present invention, when information that conflicts with the determination of the increase or decrease in the output of the laser beam from the light source is received as external environment information, the information on the side that increases the output of the laser beam is given priority. In this case, the distance measurement can be maintained even if the external environment information conflicts with the determination of the output increase / decrease.

  In still another aspect of the present invention, the output of the laser light is changed in accordance with switching of the irradiation range of the laser light from the light source. In this case, it is possible to perform optimization from the viewpoint of extending the life of the apparatus while maintaining the distance measuring function while maintaining the output corresponding to the switching of the irradiation range of the laser light.

  In still another aspect of the present invention, as an output increase / decrease switching of the laser light emitted from the light source, a normal output mode in which the laser light from the light source is emitted at a standard output, and an increase in which the laser light output is increased from the standard. It is possible to switch to one of an output mode and a reduced output mode in which the output of the laser beam is reduced from the standard. In this case, by selecting one of the three modes, it is possible to extend the life of the apparatus while ensuring the distance measuring function.

  In still another aspect of the present invention, the distance is measured based on the time until the laser light emitted from the light source is received as reflected light. In this case, distance measurement can be reliably performed based on time measurement.

It is a figure which shows an example about the vehicle carrying the laser ranging apparatus which concerns on one Embodiment. It is a block diagram for demonstrating the structure of the laser ranging device mounted in the vehicle including the structure of a vehicle. It is a figure for demonstrating an example about switching of the output mode of a laser beam. It is a flowchart for demonstrating an example of operation | movement of a laser ranging apparatus.

  Hereinafter, a laser distance measuring apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a vehicle 500 equipped with a laser distance measuring device 100 according to the present embodiment. Here, the laser distance measuring device 100 is installed on the front side of the vehicle 500, and in order to properly maintain the inter-vehicle distance from the preceding vehicle, the laser distance measuring device 100 measures the distance relative to the preceding vehicle. Is going. In addition, as described above, the laser distance measuring device 100 is not limited to the front side of the vehicle 500, and may be disposed sideward or rearward.

  In the case shown in FIG. 1, for example, a person drives the leading vehicle 500A that runs at the head, while the vehicle 500B (500) that tracks the vehicle 500A and the 500C (500) that tracks the vehicle 500B are unmanned driving. Such an embodiment is conceivable. In other words, the tracking operation of the truck can be achieved by mounting the laser distance measuring device 100 on the following vehicles 500B, 500C (500) and functioning as a tracking sensor for constantly grasping the distance from the preceding vehicle.

  Hereinafter, a configuration example of the laser distance measuring device 100 mounted on the vehicle 500 will be described including a part of the configuration of the vehicle 500 with reference to the block diagram shown in FIG.

  The laser distance measuring device 100 scans a laser beam LL by, for example, a pulse wave or the like with a distance image sensor 50 in a predetermined angle range, and uses an object (typically, a forward vehicle) existing in the angle range. It is a distance measuring device that receives reflected light, measures a distance to an object, generates a distance image based on the measurement result, and outputs it, that is, a laser beam.

  As shown by being surrounded by a one-dot chain line in FIG. 2, the laser distance measuring device 100 as one aspect of the present embodiment includes a distance image sensor 50 and a distance image sensor control unit 60.

  Among these, the distance image sensor 50 includes, for example, a laser light source unit 51, a laser output control unit 52, a MEMS mirror 53, and a detection (irradiation) range control unit 54.

  The laser light source unit 51 emits the laser light LL while controlling the emission timing toward the MEMS mirror 53, and is a light source in the laser distance measuring device 100 configured by a laser diode or the like.

  The laser output control unit 52 is a drive circuit that controls the laser light output in the laser light source unit 51.

  The MEMS mirror 53 has a light reflecting surface on which it swings and is irradiated with laser light, and performs optical scanning in a desired angle range while reflecting the laser light LL emitted from the laser light source unit 51. Further, the MEMS mirror 53 makes it possible to receive the reflected light component of the laser light LL reflected on the object (preceding vehicle).

  The detection (irradiation) range control unit 54 is a drive circuit for adjusting the swing range (angular range) of the MEMS mirror 53, and as a result, adjusts the detection range or irradiation range in the laser distance measuring device 100. It has become a thing.

  Although not shown in detail, the distance image sensor 50 is configured by using, for example, a photosensor in addition to the above, and a light receiving unit that receives reflected light from the MEMS mirror 53, and the emitted laser light is reflected light. By having a time measurement unit that measures the time until light is received or a distance measurement unit that measures (calculates) the distance to the object based on the time measured by the time measurement unit, it is possible to measure time Based on this, distance measurement (distance measurement) can be reliably performed. That is, the laser distance measuring device 100 measures the distance based on the time until the laser light LL emitted from the laser light source unit 51 as a light source is received.

  In the laser distance measuring device 100, the distance image sensor control unit 60 is a control device that controls the entire operation of the distance image sensor 50. In the example shown in the drawing, the distance image sensor control unit 60 is separated from the main control unit 300 although it is shown in a state integrated with the main control unit 300 as a part of the main control unit 300 that performs overall control of the vehicle 500. It is good also as what comprises. The distance image sensor control unit 60 includes a CPU, various programs, and the like, and transmits a command signal to the laser output control unit 52 and the detection (irradiation) range control unit 54, so that the laser output in the laser distance measuring device 100 is output. And control of operations such as switching and detection range (angle) change. Furthermore, in the present embodiment, the distance image sensor control unit 60 is a part of the main control unit 300 that performs various controls related to the vehicle 500, and thus can acquire various information related to the vehicle 500. . In particular, the distance image sensor control unit 60 can select an appropriate laser light output according to the external environment, that is, the surrounding environment of the vehicle 500, by switching the laser output reflecting various information such as the acquired weather information. Thus, while ensuring the distance measuring function, the life of the light source and the entire apparatus is extended.

  Here, the information acquired by the distance image sensor control unit 60 and information from the outside of the laser distance measuring device 100 is referred to as external environment information. That is, it can be said that the distance image sensor control unit 60 is an external environment information acquisition unit that acquires external environment information for determining an optimum laser output. Examples of the external environment information include illuminometer measurement values, map information, weather information, headlight on / off information, wiper on / off information, and speed information. The laser distance measuring device 100 switches the laser output using at least one of these pieces of information.

  Hereinafter, in order to explain the specific contents of the external environment information in more detail, the configuration of the main controller 300 and the like in the vehicle 500 will be described.

  As described above, the main control unit 300 is a device that controls the operation of each unit in the vehicle 500, and includes, for example, a CPU and various programs. For this reason, the main control unit 300 is connected to each part of the vehicle 500 so as to appropriately operate, and governs the operation of each part, and can grasp the operation status of each part.

  In the example illustrated in FIG. 2, first, the main control unit 300 is connected to a headlight 210, a wiper 220, a vehicle speed sensor unit 230, and a human detection unit 240. For example, as illustrated in FIG. 1, these members are provided inside or outside the vehicle, and the mode of operation thereof changes according to the influence of the outside world or the like. For example, the headlight 210 that is turned on / off (on / off) serves as an index indicating whether the external environment is dark or bright. When the headlight 210 automatically turns on and off according to the measurement value of the illuminance meter LU (see FIG. 2) that measures the illuminance outside the vehicle 500, the laser output is switched according to this operation. It is possible. That is, it is conceivable to reflect information on the measurement value of the illuminometer LU indirectly or directly. In the case of the wiper 220, the presence / absence of the operation (on / off) and the difference in the speed of the operation are indices relating to the rainfall. In this case as well, it is possible to reflect rain gauge information indirectly or directly. In the case of the vehicle speed sensor unit 230, the road condition is an indicator of the road speed. For example, when a certain speed is maintained, it is assumed that the vehicle is traveling on a dedicated road or a highway. In this case, the required inter-vehicle distance is different from a normal road, and the distance to the detection target is considered to be long. Note that the detection range can be limited (narrowed). On the contrary, when the speed is low, the distance between the vehicles is shortened, so that the distance measuring distance can be shortened and the laser power can be lowered. Of the above, the traveling on the exclusive road or the expressway may be specified from map information described later. In the case of the human detection unit 240, on the contrary, it can be seen whether the road is a general road, not a dedicated road or a highway, and whether the traffic is particularly heavy. In a situation where it is judged that there are many people from the information of the human detection unit 240, it is also possible to adjust the laser output from the viewpoint of eye safety.

  Returning to FIG. 2, in addition to the above, the main control unit 300 is also connected to, for example, the communication unit 250, the map information data unit 260 in which various types of map information are stored, or the GPS unit 270 that can use the GPS function. Various information can be acquired from these. For example, the communication unit 250 may be connected to a public line IN such as an Internet line. In this case, for example, it is possible to acquire weather information or the like where the vehicle 500 is heading from a database DB such as weather information or acquire information from other vehicles via the public line IN. Note that acquiring information from other vehicles means that the own vehicle may provide information to other vehicles. In addition, it is conceivable to acquire geographical information from the map information data unit 260, the GPS unit 270, or the like. For example, it is conceivable to acquire information about whether or not the user has entered or exited the tunnel.

  As described above, the distance image sensor control unit 60 of the laser distance measuring device 100 can acquire various types of information other than the peripheral information of the vehicle 500 via the main control unit 300. The distance image sensor control unit 60 appropriately switches the output increase / decrease of the laser light emitted from the laser light source unit 51 as the light source based on the external environment information via the laser output control unit 52.

  In this embodiment, as an example, it is assumed that the laser output is switched in three modes as shown in FIG. More specifically, as the output increase / decrease switching of the laser light LL emitted from the laser light source 51, the normal output mode M for emitting the laser light LL from the laser light source 51 with a standard output, and the output of the laser light LL Is switched to one of the increase output mode H in which the output is increased from the standard (normal output mode M) and the decrease output mode L in which the output of the laser beam LL is decreased from the standard (normal output mode M) ( Selection of one mode). The difference in output is adjusted by, for example, a current supplied to the laser light source unit 51.

  For the above, the distance image sensor control unit 60 selects which mode to switch to based on the acquired information when acquiring various external environment information acquired via the main control unit 300. That is, the mode is set. In this case, it can be said that the distance image sensor control unit 60 functions as an output switching unit that switches between increasing and decreasing the output of the laser light based on the external environment information. Here, as described above, various external environment information can be considered variously. However, it is necessary to increase the output of the laser beam from the characteristics of the information, or it can be as usual or reduced. But there is a difference in whether there is no problem. That is, since the distance image sensor control unit 60 functions as an output switching unit, it selects an optimum laser beam output by selecting or comprehensively considering various acquired information. Further, the external environment information may include conflicting information when the distance image sensor control unit 60 determines the output increase / decrease of the laser light.

  Hereinafter, the external environment information acquired by the distance image sensor control unit 60 will be exemplified with respect to its properties and information acquisition means.

  For example, when there is little sunlight or almost no sunlight (nighttime) in the place where the vehicle 500 is traveling (distant nighttime), it is considered that disturbance light noise is reduced. It can be maintained that it is sufficient to properly measure the distance between the vehicle and the vehicle. With regard to information acquisition means for knowing that such a condition is satisfied, for example, for nighttime, it can be considered that information on lighting on / off of the illuminance meter LU and the headlight 210, and tunneling For example, it is conceivable that the location is specified by map information using the map information data unit 260. In addition, when there is a person at low speed and in the surroundings, the distance between the vehicles to be measured by the laser distance measuring device 100 may be short, so it is safe to reduce the laser light output to some extent. It is done. That is, this determination can be made by acquiring information from the vehicle speed sensor unit 230 and the human detection unit 240.

  On the other hand, in the case of heavy rain, snow, or fog, it is considered that the field of view is poor and the detection of laser light is likely to be reduced. In this case, it is considered necessary to increase the laser beam output to some extent. Regarding information acquisition means in such a case, in addition to information such as wiper on / off information, it is conceivable to acquire the weather condition of the destination in advance by various communications when, for example, a long tunnel is reached.

  Also, with regard to the various types of information as described above, it may conflict with whether or not the output of the laser beam may be lowered to some extent, for example, in the case of rain or fog even at night. May be generated at the same time. On the other hand, in this embodiment, the distance image sensor control unit 60 predetermines the information to be prioritized or the laser light output mode to be prioritized. Here, as an example, when the conflicting information is received as the external environment information, the distance image sensor control unit 60 gives priority to the information on the side that increases the output of the laser light, thereby improving the driving safety. Secure the highest priority. In other words, in the above example, if the side that increases the output of the laser beam is selected or the view is changed, priority is given to information that it is raining or fogging.

  Hereinafter, an example of the operation of laser output control by the laser distance measuring device 100 in the present embodiment will be described with reference to the flowchart of FIG.

  First, when the vehicle 500 is started, for example, when the engine of the vehicle 500 is started (step S101), the distance image sensor control unit 60 and other parts constituting the vehicle 500 (various types related to this operation) Sensor or the like) is activated (step S102). Here, in step S102, the distance image sensor control unit 60 starts distance measurement in the initial setting mode. As for the initial setting mode, for example, among the three output modes H, M, and L (see FIG. 3), in addition to the case where the normal output mode M is unconditionally set, the respective parts that are activated when the engine is started, for example, the headlight 210 and the wiper 220 Alternatively, the mode may be set based on external environment information acquired from a sensor that functions as a sensor that acquires external information of the vehicle 500, such as the vehicle speed sensor unit 230 or the human detection unit 240.

  When ranging in the initial setting mode is started, the distance image sensor control unit 60 checks whether or not new external environment information has been input (step S103). That is, it is determined whether or not information that may change the laser light output mode is newly acquired. In step S103, if new external environment information is not input (step S103: No), distance measurement is continued in the set mode (for example, in the initial setting mode at the time of initial setting) (step S107). .

  On the other hand, when the external environment information is newly input in step S103 (step S103: Yes), the distance image sensor control unit 60 further conflicts with the external environment information newly input. It is confirmed whether it is a thing (step S104).

  If it is determined in step S104 that there is conflicting information (step S104: Yes), the distance image sensor control unit 60 sets the priority mode in accordance with a predetermined priority rule (step S105). . That is, in the above example, priority is given to information on the side that increases the output of the laser beam. Therefore, in this case, a process of changing the output mode L from the three output modes H, M, and L to any one of the output modes H and M is performed, or the output mode M is selected. Is changed to the output mode H, and the distance measurement in the set mode is continued (step S107).

  On the other hand, if it is determined in step S104 that there is no conflicting information (step S104: No), a normal output mode is selected (step S106). That is, one of the three output modes H, M, and L is determined based on the input external environment information, and distance measurement in the determined mode is continued (step S107).

  When distance measurement is performed in the set mode in step S107, the distance image sensor control unit 60 confirms whether the vehicle 500 is completely stopped, that is, whether the engine is stopped (step S108). If it is determined in step S108 that the engine of the vehicle 500 is not stopped (step S108: No), the distance image sensor control unit 60 repeats the operations of steps S103 to S108 again. That is, until it is determined that the engine of the vehicle 500 has stopped (step S108: Yes), the laser distance measuring device 100 continues to perform distance measurement in any output mode. In other words, the laser distance measuring device 100 mounted on the vehicle 500 continuously outputs laser light during operation of the vehicle 500, and measures the inter-vehicle distance without stopping. As a result, driving safety of the vehicle 500 can be enhanced.

  If it is determined that the engine of the vehicle 500 has stopped (step S108: Yes), the operation of each part of the vehicle 500 including the laser distance measuring device 100 (various sensors, etc. relating to this operation) is stopped accordingly. (Step S109), and the process ends.

  As described above, in the laser distance measuring device 100 according to the present embodiment, by measuring the output of the laser light LL in accordance with the external environment information acquired by the distance image sensor control unit 60, for example, distance measurement such as an inter-vehicle distance. Therefore, it is possible to control the laser beam LL to be emitted from the laser light source unit 51 with a suitable output that is sufficient and without waste. The life of the light source unit 51 and the laser distance measuring device 100 as a whole can be extended.

[Others]
The present invention is not limited to the above embodiment, and can be implemented in various modes without departing from the scope of the invention.

  First, as described above, in the laser distance measuring device 100 of the above-described embodiment, the distance image sensor control unit 60 transmits a command signal to the laser output control unit 52 to thereby output the laser output in the laser distance measuring device 100. As a general control unit, a command signal is transmitted to the detection (irradiation) range control unit 54 to scan the detection range, that is, the irradiation range in which the laser beam is irradiated, in other words, the laser beam is scanned. The angle range can be changed as appropriate. The irradiation range (detection range) by the laser light varies depending on, for example, the road environment in which the vehicle 500 is traveling. For example, when driving on a highway, the distance between vehicles becomes long and the position of the preceding vehicle for distance measurement becomes far, but the irradiation range by laser light, that is, the angle range in which laser light is shaken (scanned) is narrow. good. In this case, for example, there is a possibility that the output of the laser light becomes excessive depending on the relationship with the scanning speed. Therefore, the distance image sensor control unit 60 changes the output of the laser light LL along with the switching of the irradiation range of the laser light LL from the laser light source unit 51, and maintains the output according to the switching of the irradiation range of the laser light LL. However, it is also possible to function as an irradiation range switching unit that optimizes from the viewpoint of extending the life of the apparatus while ensuring the distance measuring function.

  Further, in the above embodiment, as illustrated in FIG. 3, one of the three output modes H, M, and L is determined, that is, the output is switched in three stages. However, the number of selectable laser light outputs may be four or more. Conversely, switching may be performed in two modes of high output and low output.

  In addition, regarding the setting related to the priority items such as the setting of the priority mode exemplified in step S105, various modes are conceivable, such as determining the priority order for each piece of information.

  In the case shown in FIG. 1, the laser distance measuring device is mounted on a vehicle moving outdoors, and the distance between the vehicles is measured. However, the laser distance measuring device of the present invention is also applicable to other uses. In particular, it is considered to be suitable for a distance measuring device that is constantly installed (fixed) outdoors or in a situation close to it. For example, it is conceivable to apply the laser distance measuring device of the present application in monitoring at a railroad crossing, monitoring of a platform door of a station, monitoring at an entrance of a parking lot, and the like.

  In the above-described embodiment, various objects can be applied as the MEMS mirror, that is, the optical scanning unit. For example, in addition to using an electromagnetically driven two-dimensional galvanometer mirror, an electromagnetically driven, electrostatic method, piezoelectric method, A configuration in which the movable portion having the light reflecting surface is driven to swing by various driving methods such as a thermal method can be applied.

  DESCRIPTION OF SYMBOLS 50 ... Distance image sensor 51 ... Laser light source part 52 ... Laser output control part 53 ... MEMS mirror 54 ... Detection (irradiation) range control part 60 ... Distance image sensor control part 100 ... Laser distance measuring device 210 ... headlight, 220 ... wiper, 230 ... vehicle speed sensor unit, 240 ... human detection unit, 250 ... communication unit, 260 ... map information data unit, 270 ... GPS unit, 300 ... main control unit, 500, 500A, 500B, 500C ... Vehicle, DB ... Database, H ... Increase output mode, IN ... Public line, L ... Decrease output mode, LL ... Laser light, M ... Normal output mode

Claims (7)

A laser distance measuring device that measures a distance based on a time until laser light emitted from a light source is received,
A laser distance measuring device that switches between increasing and decreasing the output of laser light emitted from the light source based on external environment information.   The laser distance measuring device according to claim 1, wherein the laser distance measuring device is mounted on a vehicle and continuously outputs laser light during operation of the vehicle.   3. The device according to claim 1, wherein at least one of a measurement value of the illuminometer, map information, weather information, headlight on / off information, and wiper on / off information is acquired as the external environment information. The laser range finder described in 1.   The information on the side that increases the output of the laser beam is given priority when the information that conflicts with the determination of the increase or decrease in the output of the laser beam from the light source is received as the external environment information. The laser distance measuring device according to one item.   The laser distance measuring device according to any one of claims 1 to 4, wherein an output of the laser light is changed in accordance with switching of an irradiation range of the laser light from the light source.   As an output increase / decrease switching of the laser light emitted from the light source, a normal output mode in which the laser light from the light source is emitted at a standard output, an increased output mode in which the laser light output is increased from the standard, and a laser light The laser distance measuring device according to any one of claims 1 to 5, which enables switching to one of a reduced output mode in which an output is reduced from a standard.   The laser distance measuring device according to any one of claims 1 to 6, wherein a distance is measured based on a time until the laser light emitted from the light source is received as reflected light.

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