How to determine the scanning method and how to measure

Abstract

To enhance the efficiency of measurement in a measuring device.SOLUTION: A measuring device 200 has a measuring part 202 and a control part 204. The measuring part 202 performs scanning by irradiating electromagnetic waves while changing the irradiation direction. The control part 204 irradiates electromagnetic waves a total of M times in N consecutive main scans, and controls the measuring part 202 so that the irradiation timing of the electromagnetic waves differs from each other in the N consecutive main scans, and the electromagnetic waves are irradiated at least once in each main scan.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for performing measurements by irradiating electromagnetic waves. [Background technology]

[0002] Technologies have been developed that detect obstacles and the like by irradiating electromagnetic waves and scanning objects. Patent Document 1 discloses a technology in which a device installed in a vehicle or the like irradiates a laser beam to scan a target area, thereby detecting obstacles and the like. Patent Document 1 also discloses a technology that changes the lateral central axis of the scan area according to the steering angle of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-258604 Summary of the Invention [Problem to be solved by the invention]

[0004] In a measuring device such as that shown in Patent Document 1, measurements may be performed at a granularity higher than the required resolution (granularity of measurement), resulting in problems such as unnecessary power consumption.

[0005] The present invention has been made in consideration of the above-mentioned problems, and one object of the present invention is to provide a technique for improving the efficiency of measurement by a measurement device. [Means for solving the problem]

[0006] The first invention is A method for determining a scanning method for a measuring device installed on a moving body, comprising: The measurement device is a device that performs scanning by irradiating electromagnetic waves while changing the irradiation direction, determining a frequency higher than a frequency of vibration generated when the moving body is moving as a scanning frequency of the main scanning of the measuring device; This is a method for determining a scanning method, which determines the timing of irradiating electromagnetic waves so that, at the determined main scanning frequency, each pixel aligned in a line in the main scanning direction is irradiated with electromagnetic waves once in total over multiple consecutive main scanning scans.

[0007] The second invention is: The scanning method is determined by the above determination method, and is a measurement method in which the measurement device scans. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a measurement device according to a first embodiment. [Figure 2] FIG. 1 is a diagram conceptually illustrating oscillation scanning by a general measurement device. [Figure 3] FIG. 1 is a plan view of the scanning range of oscillation scanning by a general measurement device in the xy plane. [Figure 4] FIG. 1 is a diagram conceptually illustrating rotational scanning by a general measurement device. [Figure 5] This is a planar view of the scanning range of a rotational scan by a typical measurement device, expanded onto the xy plane. [Figure 6] This is a diagram of FIG. 3 with the trajectory removed. [Figure 7] FIG. 10 is a diagram illustrating an example of overlapping spots of electromagnetic waves. [Figure 8] 1 is a diagram illustrating an example of the scanning range of oscillation scanning by the measurement device of the present embodiment as viewed in a planar view on the xy plane. [Figure 9] This is a diagram in which the trajectory is removed from FIG. 8. [Figure 10] 10 is a diagram illustrating the spots of each electromagnetic wave in FIG. 9. FIG. [Figure 11] 1 is a diagram illustrating an example of a planar view of the scanning range of rotational scanning by the measurement apparatus of the present embodiment, expanded on the xy plane. FIG. [Figure 12]FIG. 9 is a diagram illustrating a part of the oscillation scan performed by the measurement device shown in FIG. 8. [Figure 13] FIG. 10 is a diagram illustrating a part of a rotational scan performed by a measurement device. [Figure 14] FIG. 10 is a diagram illustrating an example in which the scanning frequency in the main scanning direction is lowered. [Figure 15] FIG. 10 is a diagram illustrating a case where electromagnetic waves are irradiated at equal intervals by a measurement device. [Figure 16] 10A and 10B are diagrams for explaining pixels that are first irradiated with electromagnetic waves in each main scanning; [Figure 17] 10 is a diagram illustrating a case where the difference in the number of times electromagnetic waves are irradiated in each main scanning is 1 or less. FIG. [Figure 18] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control unit. [Figure 19] FIG. 2 is a diagram illustrating an example of a hardware configuration of a measurement unit. [Figure 20] FIG. 2 is a diagram illustrating an example of the hardware configuration of a measurement unit that irradiates light. [Figure 21] FIG. 10 is a diagram illustrating an example of the hardware configuration of a measurement device in which reflected waves are received without passing through a scanner. [Figure 22] FIG. 4 is a diagram illustrating an example of a light source drive signal. [Figure 23] FIG. 1 is a diagram illustrating a measurement device installed on a moving body. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and their description will be omitted where appropriate. Furthermore, unless otherwise specified, each block represents a functional configuration, not a hardware configuration.

[0010] FIG. 1 is a diagram illustrating a measuring device 200 according to the first embodiment. The measuring device 200 includes a measuring unit 202 and a control unit 204. The measuring unit 202 scans an object by emitting electromagnetic waves while changing the direction of emission and receiving reflected waves of the irradiated electromagnetic waves. The control unit 204 controls the scanning by the measuring unit 202. Furthermore, the control unit 204 measures the time from when the measuring unit 202 irradiates electromagnetic waves to when it receives reflected waves of the electromagnetic waves. This measurement result is used, for example, to determine the distance between the object that reflected the electromagnetic waves and the measuring device 200 (so-called ranging). The measuring device 200 is, for example, a Lidar (Light Detection and Ranging) sensor or a millimeter-wave radar.

[0011] The measurement unit 202 scans an object by changing the direction of electromagnetic wave irradiation over time in two directions, the main scanning direction and the sub-scanning direction. The sub-scanning direction is a direction that intersects with the main scanning direction (for example, a direction substantially perpendicular to the main scanning direction).

[0012] Scanning of an object using electromagnetic waves can be done by, for example, swing scanning or rotation scanning. Hereinafter, scanning by swing will be referred to as swing scanning, and scanning by rotation will be referred to as rotational scanning. These two types of scanning will be briefly explained below.

[0013] Fig. 2 is a diagram conceptually illustrating oscillation scanning by a general measurement device 60. In Fig. 2, the measurement device 60 is depicted as a cylindrical device. A scanning range 300 represents the range through which electromagnetic waves irradiated from the measurement device can pass.

[0014] 2(a) is a planar view of the oscillation scanning performed in the xz plane. FIG. 2(b) is a planar view of the oscillation scanning performed in the yz plane. For example, if the measurement device 60 is installed in a vehicle such as an autonomous vehicle, the z direction is the vehicle's traveling direction, the y direction is the vertical direction, and the x direction is a direction perpendicular to both the y and z directions.

[0015] In oscillation scanning, the irradiation direction of the electromagnetic wave is oscillated in the main scanning direction and the sub-scanning direction. However, while the irradiation direction of the electromagnetic wave is oscillated once in the sub-scanning direction, the irradiation direction of the electromagnetic wave is oscillated multiple times in the main scanning direction. In other words, the oscillation frequency in the main scanning direction is higher than the oscillation frequency in the sub-scanning direction.

[0016] 3 is a plan view of a scanning range 300 of oscillation scanning by a general measuring device 60 in the xy plane. A trajectory 302 represents the change in the irradiation direction of the electromagnetic wave emitted from the measuring device.

[0017] Generally, a measurement device irradiates electromagnetic waves intermittently. The crosses in FIG. 3 represent positions through which the electromagnetic waves irradiated from the measurement device pass. In other words, the crosses in FIG. 3 represent the timing at which the electromagnetic waves are irradiated from the measurement device. The measurement device irradiates the electromagnetic waves during scanning in the main scanning direction (the solid line portion of the locus 302). Hereinafter, with regard to oscillation scanning, the scanning performed while the direction of irradiation of the electromagnetic waves oscillates once in the main scanning direction will be referred to as "one main scan" or "one line of main scanning."

[0018] 4A and 4B are diagrams conceptually illustrating rotational scanning by a general measurement device 60. Fig. 4A is a planar view of the rotational scanning performed on the xz plane. Fig. 4B is a planar view of the rotational scanning performed on the yz plane.

[0019] In rotational scanning, the irradiation direction of the electromagnetic wave is changed (rotated) in one direction in the main scanning direction and oscillated in the sub-scanning direction. However, while the irradiation direction of the electromagnetic wave is oscillated once in the sub-scanning direction, the irradiation direction of the electromagnetic wave is rotated multiple times in the main scanning direction. In other words, the frequency of the rotation in the main scanning direction is higher than the frequency of the oscillation in the sub-scanning direction.

[0020] 5 is a plan view of a scanning range 300 of a rotary scan performed by a general measurement device 60, expanded onto the xy plane. As described above, the irradiation direction of the electromagnetic wave in rotary scan changes in one direction in the main scanning direction. Here, with regard to rotary scan, the scan performed while the irradiation direction of the electromagnetic wave changes 360 degrees in the main scanning direction is called "one main scan" or "one line of main scan."

[0021] In both the oscillation scanning and the rotation scanning, the measurement device 60 repeatedly performs the scanning represented by the locus 302. In other words, when the irradiation direction of the electromagnetic wave reaches the end point of the locus 302, the irradiation direction of the electromagnetic wave is reset to the start point of the locus 302 again.

[0022] 3 and 5, pixels 304, which are areas divided into a grid pattern, represent the resolution (measurement granularity) required of the measurement device 60. In other words, the measurement device 60 is required to irradiate each pixel 304 in the scan range 300 with electromagnetic waves at least once.

[0023] As shown in Figures 3 and 5, in a typical measurement device 60, electromagnetic waves are irradiated at the same timing (the timing at which each pixel 304 passes) in each of multiple main scans. Furthermore, there are multiple main scans in which the electromagnetic waves can be irradiated onto one pixel 304. As a result, one pixel 304 is irradiated with the electromagnetic waves multiple times. Figure 6 is a diagram in which the trajectory 302 is removed from Figure 3. Looking at Figure 6, it can be seen that the electromagnetic waves are irradiated onto each pixel 304 four times.

[0024] The size of the spot of the electromagnetic waves emitted from the measurement device is set, for example, to match the size of the pixel 304. Therefore, irradiating one pixel 304 with electromagnetic waves multiple times means that the spots of the multiple electromagnetic waves partially overlap each other. In other words, this means that the same location is scanned multiple times by the measurement device.

[0025] 7 is a diagram illustrating an example of overlapping electromagnetic wave spots. In FIG. 7, an electromagnetic wave spot 306 is shown irradiated onto the upper left pixel 304. As can be seen from this diagram, the multiple electromagnetic wave spots 306 partially overlap each other.

[0026] In this way, typical measurement devices perform scanning at a resolution higher than the required resolution. In other words, when a measurement device scans, it irradiates more electromagnetic waves than necessary. As a result, the measurement device consumes more power than necessary. In addition, various mechanisms of the measurement device (such as the light source) wear out more than necessary, shortening the life of the measurement device.

[0027] Therefore, the measuring device 200 of this embodiment irradiates electromagnetic waves a necessary and sufficient number of times to achieve the resolution required for the measuring device 200. In other words, the control unit 204 of this embodiment controls the irradiation of electromagnetic waves by the measuring unit 202 so that each pixel that represents the resolution required for the measuring device 200 is irradiated with electromagnetic waves once.

[0028] In this way, according to the measurement device 200 of this embodiment, electromagnetic waves are emitted a necessary and sufficient number of times to achieve the resolution required of the measurement device 200. Therefore, the power consumption of the measurement device 200 is reduced compared to a general measurement device. Furthermore, wear on various mechanisms (e.g., light source) of the measurement device 200 can be reduced, and the life of the measurement device 200 can be extended.

[0029] 8 is a diagram illustrating an example of the scanning range of oscillation scanning by the measurement device 200 of this embodiment, viewed in plan on the xy plane. The scanning range 220, trajectory 222, and pixel 224 have the same meanings as the scanning range 300, trajectory 302, and pixel 304 in FIG. 3, respectively.

[0030] 8, there are four main scanning directions in which electromagnetic waves can be irradiated onto one pixel (pixel 224), as in the case of Fig. 3. However, the measurement unit 202 irradiates electromagnetic waves onto one pixel 224 in only one of the four main scanning directions in which electromagnetic waves can be irradiated onto one pixel 224.

[0031] Fig. 9 is a diagram in which the locus 222 is removed from Fig. 8. As can be seen from Fig. 9, in the measurement device 200 of this embodiment, each pixel 224 is irradiated with electromagnetic waves once.

[0032] 10 is a diagram illustrating the electromagnetic wave spots in FIG. 9. In this example, the electromagnetic wave spots are set to match the size of the pixels 224. As can be seen from FIG. 10, in the measuring device 200 of this embodiment, the spots pass through all the pixels 224, but do not overlap with each other. Therefore, the measuring device 200 does not scan the same location multiple times.

[0033] 9 and 10, it can be seen that by irradiating electromagnetic waves as shown in FIG. 8, electromagnetic waves are irradiated a necessary and sufficient number of times to satisfy the resolution required of the measurement device 200.

[0034] The scanning performed by the measurement device 200 of this embodiment may be rotational scanning. Fig. 11 is a diagram illustrating an example of the scanning range of rotational scanning by the measurement device 200 of this embodiment, expanded in the xy plane and viewed in plan. As in the case of Fig. 8, the measurement unit 202 irradiates one pixel 224 with electromagnetic waves in only one of four main scanning directions that can irradiate the pixel 224 with electromagnetic waves.

[0035] The specific control by the control unit 204 in this embodiment satisfies the following first and second requirements. The first requirement is that "the measurement unit 202 irradiates electromagnetic waves a total of M times in N consecutive main scans." The second requirement is that "the timing at which the measurement unit 202 irradiates electromagnetic waves in each of the N consecutive main scans is different from each other." M is the number of pixels of the resolution required of the measurement device 200 in N consecutive main scans. For example, in FIG. 8, the number of pixels 224 is 8 in four consecutive main scans. Therefore, in FIG. 8, N=4 and M=8.

[0036] Here, specific definitions of N and M are as follows, for example. FIG. 12 is a diagram showing a part of the oscillation scan by the measurement device 200 shown in FIG. 8. A represents the width of one pixel in the sub-scanning direction (the height of the pixel 224). B represents the width of one pixel in the main scanning direction (the horizontal width of the pixel 224). X represents the horizontal width of the scanning range 220. dy represents the scanning interval in the sub-scanning direction.

[0037] N is the number of main scans that can be irradiated with electromagnetic waves to one pixel 224. For example, in FIG. 8, the value of N is 4. Specifically, N is the largest integer equal to or less than A / dy, or the smallest integer equal to or greater than A / dy. In the following, N is assumed to be the largest integer equal to or less than A / dy.

[0038] M is the number of pixels 224 included in the scanning range 220 in the main scanning direction (the number of pixels of the resolution required for the measurement device 200 in N consecutive main scanning passes). For example, in FIG. 8, the value of M is 8. Specifically, M is the smallest integer equal to or greater than X / B, or the largest integer equal to or less than X / B. In the following, M is assumed to be the smallest integer equal to or greater than X / B.

[0039] The meaning of each symbol described above is the same when the measurement device 200 performs rotational scanning. Fig. 13 is a diagram showing a part of rotational scanning by the measurement device 200. The meaning of each symbol in Fig. 13 is the same as the meaning of each symbol in Fig. 12.

[0040] When the electromagnetic waves are irradiated so as to satisfy the first requirement described above, the electromagnetic waves are irradiated M times in a plurality of scans (N consecutive scans) that can irradiate the electromagnetic waves to M pixels 224 included in one row of the scanning range 220. Then, by irradiating the electromagnetic waves so as to satisfy the second requirement in addition to the first requirement, the electromagnetic waves are irradiated once to each of the M pixels 224 included in one row of the scanning range 220.

[0041] In this way, according to the measurement device 200 of this embodiment, electromagnetic waves are emitted a necessary and sufficient number of times to achieve the resolution required of the measurement device 200. Therefore, the power consumption of the measurement device 200 is reduced compared to a general measurement device. Furthermore, wear on various mechanisms (e.g., light source) of the measurement device 200 can be reduced, thereby extending the life of the measurement device 200.

[0042] Here, one possible control for limiting the number of times that electromagnetic waves are irradiated onto one pixel is to reduce the frequency of scanning in the main scanning direction (lower the frequency of scanning in the main scanning direction). FIG. 14 is a diagram showing an example in which the scanning frequency in the main scanning direction is lowered. In this example, the scanning frequency in the main scanning direction is 1 / 4 of that in the cases of FIGS. 3 and 8, and the main scanning passes through each pixel 304 only once. Therefore, even if the measurement device irradiates electromagnetic waves at every timing when the pixel 304 is passed, the number of times that electromagnetic waves are irradiated onto each pixel 304 is one.

[0043] However, this method has the problem that the measurement device is easily affected by ambient vibrations. Measurement devices such as lidar sensors and millimeter-wave radar are installed on moving objects such as self-driving cars. Therefore, various vibrations that occur when the moving object is moving are transmitted to the measurement device.

[0044] In order to reduce the influence of such ambient vibrations, it is preferable to increase the scanning frequency in the main scanning direction of the measurement device to some extent, thereby increasing the difference between the scanning frequency in the main scanning direction and the frequency of other vibrations. In this regard, in the measurement device 200 of this embodiment, the scanning frequency in the main scanning direction is somewhat high (the aforementioned N is 2 or more), and the number of times that electromagnetic waves are irradiated to one pixel 224 is one. Therefore, (1) the number of times that electromagnetic waves are irradiated is set to a necessary and sufficient number to satisfy the resolution required of the measurement device 200, and (2) the scanning by the measurement device 200 is less susceptible to vibrations generated around the measurement device 200, etc.

[0045] Here, the timing of irradiating the electromagnetic wave in each main scan may or may not be equal intervals. Fig. 15 is a diagram illustrating a case where the electromagnetic wave is irradiated at equal intervals in each main scan. In Fig. 15, in each of the main scans of the first to fourth rows, the electromagnetic wave is irradiated at an interval of "one for every four pixels 224."

[0046] In order to change the pixel 224 to which the electromagnetic wave is irradiated in each of N consecutive main scans, the control unit 204 changes the pixel 224 to which the electromagnetic wave is first irradiated in each of N consecutive main scans. For example, in FIGS. 8 and 15, each time the irradiation direction of the electromagnetic wave moves to a lower row in the scanning range 220, the position of the pixel 224 to which the electromagnetic wave is first irradiated is shifted to the right by one pixel 224. Specifically, in FIG. 15, the pixel 224 to which the electromagnetic wave is irradiated first in the first main scan is the first pixel 224 from the left. On the other hand, the pixel 224 to which the electromagnetic wave is irradiated first in the second main scan is the second pixel 224 from the left.

[0047] However, the method of changing the pixel 224 to which the electromagnetic wave is first irradiated in each main scan is not limited to the above-mentioned method of "shifting one pixel to the right each time the pixel moves down one row." Fig. 16 is a diagram for explaining the pixel 224 to which the electromagnetic wave is first irradiated in each main scan. In Fig. 16, the pixels 224 to which the electromagnetic wave is first irradiated in the first to fourth main scans are the first pixel 224 from the left, the third pixel 224 from the left, the second pixel 224 from the left, and the fourth pixel 224 from the right, respectively.

[0048] The number of times that the electromagnetic wave is irradiated in each main scan may or may not be the same. In the former case, the number of times that the electromagnetic wave is irradiated in each main scan is M / N. In the case of Figure 8 described above, the number of times that the electromagnetic wave is irradiated in each main scan is the same (2 times).

[0049] Note that M / N may not be an integer. In this case, instead of making the number of times that electromagnetic waves are irradiated in each main scan equal, the control unit 204 sets the difference in the number of times that electromagnetic waves are irradiated in each main scan to be 1 or less. In other words, the control unit 204 sets the number of times that electromagnetic waves are irradiated in each main scan to either the smallest integer equal to or greater than M / N or the largest integer equal to or less than M / N.

[0050] 17 is a diagram illustrating a case where the difference in the number of times electromagnetic waves are irradiated in each main scan is 1 or less. In this example, the number of main scans on which electromagnetic waves can be irradiated to one pixel 224 is four (N=4). Also, the number of pixels 304 included in one row of the scanning range 220 is seven (M=7). Therefore, the measurement unit 202 irradiates electromagnetic waves twice in each of the first to third main scans, and once in the fourth main scan.

[0051] <Example of Hardware Configuration of Measuring Device 200> Each functional component of the measuring device 200 may be realized by hardware that realizes the functional component (e.g., a hardwired electronic circuit, etc.), or may be realized by a combination of hardware and software (e.g., a combination of an electronic circuit and a program that controls it, etc.). Below, a case where each functional component of the measuring device 200 is realized by a combination of hardware and software will be further described.

[0052] <<Example of hardware configuration of control unit 204>> 18 is a diagram illustrating an example of the hardware configuration of the control unit 204. The integrated circuit 100 is an integrated circuit that realizes the control unit 204. For example, the integrated circuit 100 is an SoC (System On Chip).

[0053] The integrated circuit 100 has a bus 102, a processor 104, a memory 106, a storage device 108, an input / output interface 110, and a network interface 112. The bus 102 is a data transmission path through which the processor 104, the memory 106, the storage device 108, the input / output interface 110, and the network interface 112 transmit and receive data to and from each other. However, the method of interconnecting the processor 104 and other components is not limited to bus connection. The processor 104 is an arithmetic processing unit implemented using a microprocessor or the like. The memory 106 is a main storage device implemented using a RAM (Random Access Memory) or the like. The storage device 108 is an auxiliary storage device implemented using a ROM (Read Only Memory), a flash memory, or the like.

[0054] The input / output interface 110 is an interface for connecting the integrated circuit 100 to peripheral devices. In Fig. 18, the input / output interface 110 is connected to an illuminator drive circuit 30 and a scanner drive circuit 32. The illuminator drive circuit 30 and the scanner drive circuit 32 will be described later.

[0055] The network interface 112 is an interface for connecting the integrated circuit 100 to a communication network. This communication network is, for example, a CAN (Controller Area Network) communication network. The method for connecting the network interface 112 to the communication network may be wireless connection or wired connection.

[0056] The storage device 108 stores a program module for realizing the functions of the control unit 204. The processor 104 reads the program module into the memory 106 and executes it to realize the functions of the control unit 204.

[0057] The hardware configuration of the integrated circuit 100 is not limited to the configuration shown in Fig. 18. For example, the program modules may be stored in the memory 106. In this case, the integrated circuit 100 may not include the storage device 108.

[0058] <<Example of hardware configuration of measurement unit 202>> FIG. 19 is a diagram illustrating an example of the hardware configuration of the measurement unit 202. The measurement unit 202 has an illuminator 10, a scanner 12, an illuminator drive circuit 30, a scanner drive circuit 32, and a receiver 50. The illuminator 10 irradiates electromagnetic waves used to scan an object. The scanner 12 changes the traveling direction of the electromagnetic waves irradiated from the illuminator 10 to a desired direction. In this way, the illuminator 10 and the scanner 12 enable the measurement unit 202 to irradiate electromagnetic waves to various locations outside the measurement unit 202. The electromagnetic waves whose traveling direction has been changed by the scanner 12 are irradiated outside the measurement device 200.

[0059] Electromagnetic waves reflected by an object outside the measurement device 200 (hereinafter referred to as reflected waves) enter the inside of the measurement device 200, and then their traveling direction is changed by the scanner 12. The receiver 50 receives the reflected waves whose traveling direction has been changed by the scanner 12.

[0060] The illuminator drive circuit 30 is a circuit that drives the illuminator 10. More specifically, the illuminator drive circuit 30 has a circuit that drives a mechanism (e.g., a light source) that irradiates electromagnetic waves. The scanner drive circuit 32 is a circuit that drives the scanner 12. More specifically, the scanner drive circuit 32 has a circuit that drives a mechanism (e.g., a mirror) that changes the irradiation direction of electromagnetic waves.

[0061] The control unit 204 detects that the reflected wave has been received by the receiver 50. For example, the receiver 50 is configured to transmit a predetermined signal to the control unit 204 in response to receiving the reflected wave. The control unit 204 detects that the reflected wave has been received by the receiver 50 by receiving this predetermined signal.

[0062] The control unit 204 measures the elapsed time from when the irradiator 10 irradiates the electromagnetic wave until the receiver 50 receives the reflected wave of the electromagnetic wave, and stores the measured time in a storage device (e.g., storage device 108) in association with the direction of irradiation of the electromagnetic wave (the timing of irradiation of the electromagnetic wave). This elapsed time is expressed, for example, as a value obtained by multiplying the number of clock signals counted from when the irradiator 10 irradiates the electromagnetic wave until the receiver 50 receives the reflected wave of the electromagnetic wave by the clock period. Alternatively, for example, this elapsed time may be expressed as the number of counted clock signals. Based on this elapsed time, for example, the distance between the scanned object and the measurement device 200 can be calculated.

[0063] The electromagnetic waves irradiated by the irradiator 10 may be light such as laser light, or may be radio waves such as millimeter waves. Below, an example of the hardware configuration of the measurement unit 202 when the irradiator 10 irradiates light will be described. A similar configuration can also be adopted for the measurement unit 202 when the irradiator 10 irradiates electromagnetic waves.

[0064] Fig. 20 is a diagram illustrating an example of the hardware configuration of a measurement unit 202 that irradiates light. The light source 14, the movable reflector 16, the light source drive circuit 36, and the movable reflector drive circuit 34 in Fig. 20 are examples of the illuminator 10, the scanner 12, the illuminator drive circuit 30, and the scanner drive circuit 32 in Fig. 19, respectively.

[0065] The light source 14 is any light source that emits light. The light source drive circuit 34 is a circuit that drives the light source 14 by controlling the supply of power to the light source 14. The light emitted by the light source 14 is, for example, laser light. In this case, the light source 14 is, for example, a semiconductor laser that emits laser light.

[0066] The movable reflecting unit 16 reflects light emitted from the light source 14, thereby changing the traveling direction of the light emitted from the light source 14. The light reflected by the movable reflecting unit 16 is irradiated to the outside of the measurement device 200. The movable reflecting unit 16 also changes the traveling direction of light reflected by an object outside the measurement device 200 (hereinafter referred to as reflected light).

[0067] The movable reflector drive circuit 36 ​​is a circuit that drives the movable reflector 16. The movable reflector 16 has one mirror that is configured to be rotatable in each of two axial directions, for example. The two axes are a first axis for changing the light irradiation direction in the main scanning direction and a second axis for changing the light irradiation direction in the sub-scanning direction. The mirror is, for example, a MEMS (Micro Electro Mechanical System) mirror.

[0068] The configuration of the movable reflector 16 is not limited to the configuration shown in Fig. 20. For example, the movable reflector 16 may be configured with two mirrors whose rotation axes intersect with each other. The rotation axes of these two mirrors are the first axis and the second axis, respectively.

[0069] The operations of the light source drive circuit 34 and the movable reflector drive circuit 36 ​​are controlled by the control unit 204. Specifically, the control unit 204 transmits a drive signal to the light source drive circuit 34, instructing it to drive the light source 14. This drive signal is read from, for example, the storage device 108. The light source drive circuit 34 drives the light source 14 based on the received drive signal. For example, if the drive signal is a pulse signal composed of two values, high and low, the light source drive circuit 34 drives the light source 14 (causes the light source 14 to emit light) at the timing when the pulse signal changes from low to high.

[0070] Similarly, the control unit 204 transmits a drive signal to the drive circuit 36 ​​of the movable reflector to instruct it to drive the movable reflector 16. This drive signal is also read from, for example, the storage device 108. The drive circuit 36 ​​of the movable reflector controls the attitude of the movable reflector 16 based on this drive signal. This control controls the direction of light irradiation. For example, the light irradiation direction is controlled as shown by the locus 222 in FIG. 8.

[0071] The measurement unit 202 further includes a photoreceiver 52. The photoreceiver 52 is an example of the receiver 50 in FIG. 19. For example, the photoreceiver 52 is configured using an APD (Avalanche Photodiode). The photoreceiver 52 receives reflected light whose traveling direction has been changed by the movable reflector 16.

[0072] The configuration of the measurement unit 202 is not limited to the configurations shown in Fig. 19 and Fig. 20. For example, in Fig. 19, the measurement unit 202 is configured so that the reflected waves reflected by an object are received by the receiver 50 via the scanner 12. However, the reflected waves reflected by an object may be received by the receiver 50 without passing through the scanner 12. Fig. 21 is a diagram illustrating an example of the hardware configuration of a measurement device 200 in which the reflected waves are received without passing through the scanner 12.

[0073] 19, for example, the measurement unit 202 is configured to be able to irradiate electromagnetic waves in various directions by changing the traveling direction of the electromagnetic waves irradiated from the irradiator 10 using the scanner 12. However, the configuration for irradiating electromagnetic waves in various directions is not limited to the configuration shown in FIG. 19. For example, the irradiator 10 itself may have a mechanism for rotating about each of the two axes described above. In this case, the measurement unit 202 can irradiate light in various directions by controlling the attitude of the irradiator 10. Also, in this case, the measurement unit 202 may not have the scanner 12 and the scanner drive circuit 32. Furthermore, in this case, the irradiator drive circuit 30 includes a drive circuit that causes the irradiator 10 to irradiate electromagnetic waves and a drive circuit that changes the attitude of the irradiator 10.

[0074] The hardware that realizes the control unit 204 (see Figure 18) and the hardware that realizes the measurement unit 202 (see Figures 19 and 20) may be packaged in the same housing, or may be packaged in separate housings.

[0075] <Method for controlling timing of electromagnetic wave irradiation by the measuring unit 202> The timing at which electromagnetic waves are emitted from the measurement device 200 can be controlled by a drive signal (hereinafter referred to as the light source drive signal) sent to the light source drive circuit 34. Therefore, a light source drive signal that controls the measurement unit 202 is generated in advance so as to satisfy the first and second requirements described above. This light source drive signal is stored in, for example, the storage device 108. The control unit 204 reads this light source drive signal from the storage device 108 and sends it to the light source drive circuit 34. In this way, the measurement unit 202 is controlled so as to satisfy the first and second requirements described above. The light source drive signal is generated, for example, before the measurement device 200 starts operating (for example, before the measurement device 200 is shipped).

[0076] Figure 22 is a diagram illustrating a light source drive signal. In both Figure 22(a) and Figure 22(b), the graph represents the light source drive signal. The arrows on the graph represent the points (pulses) where the value of the light source drive signal changes from 0 to 1. The light source irradiates electromagnetic waves at the timing indicated by the arrows. The trajectory of scanning by the measurement device controlled by the light source drive signal is shown above the graph.

[0077] Fig. 22(a) shows a light source drive signal that realizes scanning by the general measurement device shown in Fig. 2. In contrast, Fig. 22(b) shows a light source drive signal that realizes scanning by the measurement device 200 of this embodiment shown in Fig. 8.

[0078] <Installation example of measurement device 200> The measuring device 200 is installed on a moving body such as an automobile or a train. FIG. 23 is a diagram illustrating the measuring device 200 installed on a moving body. In FIG. 23, the measuring device 200 is fixed to the upper part of a moving body 240. The measuring device 200 is also connected to a control device 244. The control device 244 is a control device that controls the moving body 240. For example, the control device 244 is an ECU (Electronic Control Unit).

[0079] Here, the control unit 204 may be realized as part of a control device 244 that controls the moving object 240. In this case, a program module that realizes the above-mentioned control unit 204 is stored in a storage device included in the control device 244.

[0080] The location where the measuring device 200 is installed is not limited to the top of the moving body 240. For example, the measuring device 200 may be installed inside (e.g., indoors) the moving body 240. The measuring device 200 may also be installed on a stationary object.

[0081] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and it is also possible to adopt combinations of the above-described embodiments or various other configurations. Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and it is also possible to adopt combinations of the above-described embodiments or various other configurations. Below, examples of reference forms are added. 1. a measuring unit that scans by irradiating electromagnetic waves while changing the irradiation direction; a control unit that controls the measurement unit so that electromagnetic waves are irradiated a total of M times in N consecutive main scans, the electromagnetic waves being irradiated at different timings in the N main scans, and the electromagnetic waves being irradiated at least once in each main scan. 2. 2. The measuring device according to 1, wherein M is the number of pixels of the resolution obtained in the N consecutive main scans. 3. When the scanning interval in the sub-scanning direction is dy and the width of one pixel in the sub-scanning direction is A, N is either the largest integer equal to or smaller than A / dy or the smallest integer equal to or larger than A / dy, 3. The measuring device according to 1. or 2., wherein, when the width of a scan range in the main scanning direction is X and the width of one pixel in the main scanning direction is B, M is either the smallest integer equal to or greater than X / B or the largest integer equal to or less than X / B. 4. The control device according to any one of 1. to 3., wherein the control unit irradiates the electromagnetic wave at equal intervals in each main scan. 5. The control device described in any one of 1. to 4., wherein the control unit sets the number of times of electromagnetic wave irradiation in each of the N main scans to either the smallest integer greater than or equal to M / N or the largest integer less than or equal to M / N. 6. A control method in which a computer controls a measuring device that performs scanning by irradiating electromagnetic waves while changing the irradiation direction, comprising: A control method for controlling the measuring device so that electromagnetic waves are irradiated a total of M times in N consecutive main scans, the irradiation timing of the electromagnetic waves being different from each other in the N main scans, and the electromagnetic waves being irradiated at least once in each main scan. [Explanation of symbols]

[0082] 10 Irradiator 12 Scanner 14 Light source 16 Movable reflector 30 Irradiator drive circuit 32 Scanner driver circuit 34 Light source drive circuit 36 Movable reflector drive circuit 50 Receiver 52 Receiver 100 Integrated Circuits 102 Bus 104 processors 106 memory 108 Storage Devices 110 Input / Output Interface 112 Network Interface 200 Measuring Equipment 202 Measurement Department 204 Control Unit 220 scanning range 222 Trajectory 224 pixels 240 Mobile 244 Control Device 300 scanning range 302 Trajectory 304 pixels 306 Spots

Claims

1. A method for determining a scanning method for a measuring device installed on a moving body, comprising: The measurement device is a device that performs scanning by irradiating electromagnetic waves while changing the irradiation direction, determining a frequency higher than a frequency of vibration generated when the moving body is moving as a scanning frequency of the main scanning of the measuring device; A method for determining a scanning method, comprising: performing a plurality of successive main scans capable of irradiating one pixel with electromagnetic waves at the determined scanning frequency of the main scan; and determining the timing of irradiating the electromagnetic waves so that one pixel is irradiated with the electromagnetic waves only once in the plurality of successive main scans.

2. 2. The method of claim 1, A method for determining the timing of irradiating electromagnetic waves so that multiple spots of the electromagnetic waves do not overlap each other on a predetermined plane.

3. 3. The method according to claim 1, wherein: A method of determining the size of the electromagnetic wave spot according to the size of the pixel.

4. 4. The method according to claim 1, wherein the measurement device is a device that performs scanning by changing the direction of irradiation of electromagnetic waves over time in two directions, a main scanning direction and a sub-scanning direction, A method of determining that the scanning frequency in the main scanning direction is higher than the scanning frequency in the sub-scanning direction.

5. 5. The method of claim 4, a determination method for determining the electromagnetic wave irradiation timing such that the electromagnetic wave irradiation timings are different from one another in the plurality of consecutive main scans and the electromagnetic wave is irradiated at least once in each main scan;

6. 6. The method of claim 5, determining a scanning method such that electromagnetic waves are irradiated a total of M times in N consecutive main scans, the irradiation timings of the electromagnetic waves are different from one another in the N main scans, and the electromagnetic waves are irradiated at least once in each main scan; If the scanning interval in the sub-scanning direction is dy and the width of one pixel in the sub-scanning direction is A, then N is either the largest integer equal to or smaller than A / dy or the smallest integer equal to or larger than A / dy, A method for determining M as either the smallest integer equal to or greater than X / B or the largest integer equal to or less than X / B, where X is the width of the scan range in the main scanning direction and B is the width of one pixel in the main scanning direction.

7. 7. The method of claim 6, A method of determining the number of electromagnetic wave irradiations in each of the N main scans as either the smallest integer equal to or greater than M / N or the largest integer equal to or less than M / N.

8. 8. The method according to claim 6 or 7, A determination method, wherein M is the number of pixels of a resolution required for the measurement device in the plurality of consecutive main scans.

9. 9. The method according to claim 1, wherein A determination method for determining that electromagnetic waves are to be irradiated at equal intervals in each main scan.

10. A measurement method in which the measurement device scans using the scanning method determined by the determination method according to any one of claims 1 to 9.

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