Position estimation system for work machine

Abstract

To accurately and stably estimate a position of a work machine at a work site in an environment with poor visibility or in an environment with a poor reception state of radio waves from GNSS satellites.SOLUTION: A position estimation system S includes a work machine V1 and a position estimation device 200 disposed at a work site. The work machine V1 comprises lamps 50A-50D and a light emission control device 300. The position estimation device 200 comprises an imaging device 201 that images the lamps 50A-50D, and an image processing device 203 that processes images acquired by the imaging device 201. The image processing device 203 extracts a luminance change pattern in the image, calculates relative positions of the lamps 50A-50D in the image on the basis of the extracted pattern, and estimates the position of the work machine V1 at the work site on the basis of the relative positions of the lamps 50A-50D in the image, mounting positions of the lamps on the work machine V1, and an installation position of the imaging device 201 at the work site.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a position estimation system for a work machine. [Background technology]

[0002] BACKGROUND ART Automatically driven work machines that autonomously perform excavation and loading operations at work sites have been proposed. For automatically driven work machines, it is important to accurately estimate the position of the work machine at the work site.

[0003] Known technologies for estimating the position of a work machine at a work site include a technology in which a device for detecting the work machine's own position, such as a Global Navigation Satellite System (GNSS) receiver, is installed on the work machine itself, as well as a technology in which the position of the work machine is estimated in cooperation with a device installed outside the work machine.

[0004] For example, Patent Document 1 discloses a technology for estimating the position and attitude of a work machine by placing a marker on a target truck, photographing the marker with an imaging device installed on the work machine, and calculating the position and attitude of the marker. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-054072 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology disclosed in Patent Document 1 cannot capture appropriate images in environments with poor visibility, such as dark places or places with flying dust, making it difficult to accurately estimate the position of a work machine. Furthermore, with technology that estimates the position of a work machine using a GNSS receiver installed on the work machine, radio waves from GNSS satellites may not be received reliably at work sites that are underground or have surrounding obstructions, or even if the radio waves are received, the accuracy of the position estimation may be low. Furthermore, with technology that estimates the position of a work machine from the measurement results of a ranging device installed on the work machine, depending on the work site, there may be no terrain or structures that can serve as a reference for estimating the position of the work machine, leaving room for improvement in terms of accurately and stably estimating the position.

[0007] In view of the above-mentioned circumstances, the present invention aims to accurately and stably estimate the position of a work machine at a work site in an environment with poor visibility or poor reception of radio waves from GNSS satellites. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the work machine position estimation system of the present invention is a work machine position estimation system including a work machine operating at a work site and a position estimation device arranged at the work site, wherein the work machine is equipped with a plurality of light-emitting elements attached to different positions of the work machine and a light emission control device that controls the light emission of the plurality of light-emitting elements, and the position estimation device is equipped with an imaging device that images the plurality of light-emitting elements and an image processing device that processes images acquired by the imaging device, the light emission control device controls the light emission of the plurality of light-emitting elements using a light emission pattern that differs over time for each light-emitting element of the plurality of light-emitting elements, and the image processing device extracts from the image a pattern in which the brightness of pixels constituting the image obtained by imaging the plurality of light-emitting elements changes over time, calculates the relative positions of the plurality of light-emitting elements within the image based on the extracted pattern, and estimates the position of the work machine at the work site based on the calculated relative positions of the plurality of light-emitting elements within the image, pre-stored mounting positions of the plurality of light-emitting elements on the work machine, and an installation position of the imaging device at the work site. [Effects of the Invention]

[0009] According to the present invention, the position of a work machine at a work site can be estimated accurately and stably in a work site environment with poor visibility or poor reception of radio waves from GNSS satellites. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram schematically showing the appearance of a work machine according to a first embodiment. [Figure 2] FIG. 1 is a diagram showing the configuration of a position estimation system according to a first embodiment. [Figure 3] FIG. 2 is a diagram showing a schematic diagram of the arrangement of a work machine and a position estimation device at a work site. [Figure 4] FIG. 2 is a block diagram showing the functions of the light emission control device according to the first embodiment. [Figure 5] FIG. 10 is a diagram showing an example of encoding a light emission pattern. [Figure 6]FIG. 1 is a block diagram showing functions of an image processing apparatus according to a first embodiment. [Figure 7] 2 is a diagram showing an image captured by the imaging device when the work machine is positioned far from the imaging device with its front left part facing the imaging device as in FIG. 1; FIG. [Figure 8] 2 is a diagram showing an image captured by the imaging device when the work machine is positioned close to the imaging device with its right rear part facing the imaging device, opposite to that in FIG. 1; FIG. [Figure 9] FIG. 10 is a top view showing the positional relationship between the work machine and the imaging device when the number of lamps is two. [Figure 10] 10 is a diagram showing an image acquired by an imaging device in the case shown in FIG. 9; [Figure 11] 10 is a top view showing the positional relationship between the work machine and the imaging device when the number of lamps is increased to three compared to FIG. 9. [Figure 12] 12 is a diagram showing an image acquired by an imaging device in the case shown in FIG. 11. [Figure 13] 4 is a flowchart showing the flow of operations of the light emission control device and the position estimation device. [Figure 14] FIG. 6 is a diagram schematically showing the appearance of a work machine according to a second embodiment. [Figure 15] FIG. 10 is a diagram showing the configuration of a position estimation system according to a second embodiment. [Figure 16] FIG. 11 is a diagram schematically showing the arrangement of a work machine and a position estimation device according to a third embodiment at a work site. [Figure 17] FIG. 10 is a block diagram showing the functions of an image processing apparatus according to a third embodiment. [Figure 18] FIG. 10 is a diagram schematically showing the appearance of a work machine according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Components with the same reference numerals in each embodiment have similar components in each embodiment unless otherwise specified, and description thereof will be omitted.

[0012] [First embodiment] A first embodiment of the present invention will be described using Figures 1 to 13. Figure 1 is a diagram schematically showing the appearance of a work machine V1 according to the first embodiment. Figure 2 is a diagram showing the configuration of a position estimation system S according to the first embodiment. Figure 3 is a diagram schematically showing the arrangement of a work machine V1 and a position estimation device 200 at a work site.

[0013] The position estimation system S is a system that estimates the position of a work machine V1 at a work site. The position estimation system S is configured to include a work machine V1 that operates at the work site, and a position estimation device 200 that is placed at the work site. The work machine V1 and position estimation device 200 are connected to each other via a wireless communication network so that they can communicate with each other.

[0014] The work machine V1 is an automatically driven work machine that autonomously performs operations or tasks such as traveling, excavating, and loading at a work site. The work machine V1 shown in Fig. 1 is an articulated wheel loader. The work machine V1 may be a wheel loader other than an articulated type, or may be a work machine other than a wheel loader, such as a hydraulic excavator.

[0015] The work machine V1 is equipped with a bucket 1, which is a work tool for excavating and holding an object, and a lift arm 2 that rotatably supports the bucket 1. The lift arm 2 is rotatably supported on the front body 5F of the work machine V1, and the bucket 1 moves up and down as the lift arm 2 rotates. The lift arm 2 rotatably supports a bell crank 3, and when the bell crank 3 rotates, the bucket 1 also rotates relative to the lift arm 2 via the bucket link 4.

[0016] The work machine V1 is equipped with a front left wheel 21FL, a front right wheel 21FR, a rear left wheel 21RL, and a rear right wheel 21RR, and moves by driving these wheels. The work machine V1 is equipped with, for example, an articulated steering mechanism in which the body 5 bends between the front wheels 21FL, 21FR and the rear wheels 21RL, 21RR. The work machine V1 turns by creating an angle difference between the front body 5F and the rear body 5R, with the vertical direction of the body 5 as the turning axis. The front body 5F and the rear body 5R are connected via a steering cylinder 11.

[0017] The work machine V1 is equipped with a cab 6, which serves as a driver's seat, at the rear body 5R. Lamps 50A-50D are attached to the four corners of the upper surface of the cab 6 as a plurality of light emitters. That is, each of the lamps 50A-50D is attached to a different position on the work machine V1. For example, an LED or a light bulb is used for each of the lamps 50A-50D. Each of the lamps 50A-50D receives a light emission control signal from a light emission control device 300, and the light emission state is controlled as described in detail below.

[0018] As shown in Fig. 2, the work machine V1 is equipped with an engine 10 as a power source, and the engine 10 drives a hydraulic pump 14 and a driving force transmission device 22. The driving force transmission device 22 transmits the driving force of the engine 10 to front wheels 21FL, 21FR via a center joint 23 and a front differential 24F. The driving force transmission device 22 transmits the driving force of the engine 10 to rear wheels 21RL, 21RR via the center joint 23 and a rear differential 24R. This causes the vehicle body 5 to accelerate and travel.

[0019] The hydraulic pump 14 supplies hydraulic oil to the control valve 15 when driven by the engine 10. The hydraulic oil is distributed by the control valve 15 and supplied to the steer cylinder 11, the lift cylinder 12, the bucket cylinder 13, and the brakes 25F, 25R. When the steer cylinder 11 extends and retracts due to the supply of hydraulic oil, the angle between the front body 5F and the rear body 5R changes. In other words, the vehicle body 5 bends. When the lift cylinder 12 extends and retracts due to the supply of hydraulic oil, the angle of the lift arm 2 relative to the front body 5F changes. When the bucket cylinder 13 extends and retracts due to the supply of hydraulic oil, the angle of the bucket 1 relative to the lift arm 2 changes. When the brakes 25F, 25R operate due to the supply of hydraulic oil, the rotation of the wheels 21FL, 21FR, 21RR, 21RL is suppressed, and the vehicle body 5 is decelerated and stopped.

[0020] Furthermore, the work machine V1 is equipped with an automatic driving control device 100, a light emission control device 300, an engine control device 500, a hydraulic control device 600, a travel control device 700, and a communication device 101.

[0021] When automatic driving starts, the automatic driving control device 100 starts transmitting a pattern light emission start signal and causes the light emission control device 300 to start light emission control of the lamps 50A-50D. When automatic driving stops, the automatic driving control device 100 stops transmitting the pattern light emission start signal and causes the light emission control device 300 to stop light emission control of the lamps 50A-50D. The automatic driving control device 100 also generates engine control signals, hydraulic control signals, and travel control signals for moving the work machine V1 to the target position, with the pre-stored position of the work object being set as the target position. At this time, the automatic driving control device 100 generates these control signals in accordance with vehicle body position information that indicates the position of the work machine V1 at the work site and that is received from the position estimation device 200 via the communication device 101. The automatic driving control device 100 then generates control commands by combining the generated control signals with information on the work content (such as information on whether excavation work is being performed or loading work is being performed). The automatic driving control device 100 transmits the generated control commands to the hydraulic control device 600, engine control device 500, and travel control device 700.

[0022] The work object may be, for example, a collection site or stockyard where excavated materials such as earth and sand are accumulated in the case of excavation work, or a hopper or dump truck into which the excavated materials are loaded in the case of loading work.

[0023] The engine control signal, hydraulic control signal, and cruise control signal included in the control command transmitted by the automatic driving control device 100 are transmitted to the engine control device 500, hydraulic control device 600, and cruise control device 700, respectively. The engine control device 500 controls the rotation speed of the engine 10 in accordance with the engine control signal. The hydraulic control device 600 controls the opening and closing degree of the control valve 15 in accordance with the hydraulic control signal. The cruise control device 700 controls the gear ratio and cruise direction of the driving force transmission device 22 in accordance with the cruise control signal.

[0024] The light-emitting control device 300 controls the light emission of each of the lamps 50A to 50D based on a pattern light emission start signal from the automatic driving control device 100. While the light-emitting control device 300 is receiving the pattern light emission start signal from the automatic driving control device 100, it transmits a light-emitting control signal to the lamps 50A to 50D to control the light-emitting state of each of the lamps 50A to 50D. Note that instead of performing light-emitting control while receiving the pattern light-emitting start signal, the light-emitting control device 300 may start light-emitting control when it receives the pattern light-emitting start signal, and stop light-emitting control when it receives the pattern light-emitting start signal again during light-emitting control, or when it receives a pattern light-emitting stop signal. Details of the light-emitting control device 300 will be described later.

[0025] The position estimation device 200 includes an imaging device 201 that captures images of the lamps 50A-50D, an image processing device 203 that processes images acquired by the imaging device 201, and a communication device 202 that communicates with the work machine V1. The position estimation device 200 is installed at a predetermined location within the work site. For example, as shown in FIG. 3, the position estimation device 200 is installed at a predetermined location near the work target. Note that in this embodiment, the imaging device 201, communication device 202, and image processing device 203 are installed within the work site as an integrated position estimation device 200, but it is also possible for only the imaging device 201 to be installed within the work site, with the communication device 202 and image processing device 203 being installed outside the work site. Details of the image processing device 203 will be described later.

[0026] Fig. 4 is a block diagram showing the functions of the light emission control device 300 according to the first embodiment. Fig. 5 is a diagram showing an example of encoding of a light emission pattern.

[0027] As shown in FIG. 4, the light emission control device 300 includes a light emission pattern storage unit 310 and a light emission control signal generation unit 320.

[0028] The light emission pattern storage unit 310 stores in advance information on different light emission patterns (hereinafter also referred to as "light emission pattern information") corresponding to each of the lamps 50A to 50D. When the light emission control signal generation unit 320 receives a pattern light emission start signal from the automatic driving control device 100, it reads out the light emission pattern information stored in the light emission pattern storage unit 310. The light emission control signal generation unit 320 generates a light emission control signal that controls the light emission of each of the lamps 50A to 50D in accordance with the light emission pattern information that has been read out, and transmits the light emission control signal to the lamps 50A to 50D.

[0029] The light emission patterns of the lamps 50A to 50D vary over time. Each light emission pattern may be a light emission pattern in which each lamp 50A to 50D alternates between a light emission state (on state) and a non-light emission state (off state). Each light emission pattern may be represented as a graph showing the time-series change in the light emission state, as shown in FIG. 5. The light emission control signal may be a control signal that switches each lamp 50A to 50D between a light emission state and a non-light emission state.

[0030] 5, the individual identification information of each lamp 50A to 50D is encoded by appropriately combining the duration of the light-emitting state (ON) and the duration of the non-light-emitting state (OFF) of each lamp 50A to 50D. The transmission start code indicating the start of the code and the transmission end code indicating the end of the code are common to each lamp 50A to 50D. The data code portion is assigned to each lamp 50A to 50D so as to be different from one another; for example, numbers 1 to 4 are assigned to each lamp 50A to 50D, and the data is encoded using the corresponding Morse codes 1 to 4. The encoding method may be a method other than Morse code.

[0031] The apparent luminous flux of each lamp 50A-50D decreases depending on the proportion of the duration of the non-emission state included in the emission pattern. Therefore, the brightness of the lamps 50A-50D in the emission state is set so as to ensure illumination in dark places and the luminous flux necessary for direction indication.

[0032] 5, the light-emitting control device 300 may control the light emission of each of the lamps 50A to 50D using a light-emitting pattern that changes the intensity of the light emitted by each of the lamps 50A to 50D so that each of the lamps 50A to 50D alternates between an emitting state and a non-emitting state. However, the light-emitting control device 300 is not limited to this.

[0033] For example, the light-emitting control device 300 may control the light emission of each of the lamps 50A to 50D using a light-emitting pattern that changes the intensity of the light emitted by each of the lamps 50A to 50D over time so that the brightness of the light emitted by each of the lamps 50A to 50D changes.

[0034] Furthermore, for example, the light-emitting control device 300 may control the light emission of each of the lamps 50A to 50D using a light-emitting pattern that changes the wavelength (color) of light emitted by each of the lamps 50A to 50D over time. In this case, the light-emitting control device 300 may change the wavelength of light emitted by each of the lamps 50A to 50D by switching the color filters provided on each of the lamps 50A to 50D or the light-emitting elements that operate the LEDs.

[0035] Furthermore, for example, the light-emitting control device 300 may control the light emission of each of the lamps 50A to 50D using a light-emitting pattern that changes the polarization state of the light emitted by each of the lamps 50A to 50D over time. In this case, the light-emitting control device 300 may change the polarization state of the light emitted by each of the lamps 50A to 50D by switching the polarizing filters provided in each of the lamps 50A to 50D.

[0036] FIG. 6 is a block diagram showing the functions of the image processing device 203 according to the first embodiment.

[0037] The image processing device 203 includes a pattern extraction unit 210 , a relative position calculation unit 220 , an attachment position storage unit 230 , an installation position storage unit 240 , and a position estimation unit 250 .

[0038] Information about images captured by the imaging device 201 is transmitted from the imaging device 201 to the image processing device 203 at regular intervals (for example, every few tens of milliseconds). The pattern extraction unit 210 extracts a pattern in which the brightness of pixels constituting the images changes over time from a plurality of images captured consecutively in time series by the imaging device 201. The pattern extraction unit 210 compares the extracted pattern with pre-stored light emission pattern information for each of the lamps 50A to 50D. This allows the pattern extraction unit 210 to identify each light spot in the image that changes according to the extracted pattern as each of the lamps 50A to 50D appearing in the image. The pattern extraction unit 210 transmits pixel information for each identified light spot to the relative position calculation unit 220.

[0039] The relative position calculation unit 220 calculates the relative position of each of the lamps 50A to 50D within the image by calculating the relative position of each light spot within the image from the pixel information transmitted from the pattern extraction unit 210. The relative position calculation unit 220 transmits relative position information indicating the calculated relative positions of each of the lamps 50A to 50D to the position estimation unit 250.

[0040] The mounting position storage unit 230 stores mounting position information that indicates the actual positions at which the lamps 50A-50D are mounted on the body 5 of the work machine V1 or the positional relationship thereof (hereinafter also referred to as "mounting position"). The mounting position information for the lamps 50A-50D is predetermined and stored in the mounting position storage unit 230 in advance.

[0041] The installation position storage unit 240 stores installation position information indicating the position where the position estimation device 200 (imaging device 201) is actually installed in the work site. The installation position information of the position estimation device 200 (imaging device 201) is predetermined and stored in the installation position storage unit 240 in advance.

[0042] When the position estimation unit 250 receives the relative position information from the relative position calculation unit 220, it reads out the mounting position information of each of the lamps 50A-50D stored in the mounting position storage unit 230, and the installation position information of the position estimation device 200 (imaging device 201) stored in the installation position storage unit 240. The position estimation unit 250 estimates the position of the work machine V1 relative to the position estimation device 200 (imaging device 201) from the received relative position information and the read-out mounting position information. The position estimation unit 250 then performs coordinate transformation on the estimated position of the work machine V1 relative to the position estimation device 200 (imaging device 201) using the read-out installation position information, thereby estimating the position of the work machine V1 at the work site. The position estimation unit 250 transmits vehicle body position information indicating the estimated position of the work machine V1 at the work site to the communication device 202. The communication device 202 transmits the vehicle body position information from the position estimation unit 250 to the work machine V1.

[0043] The processing of the position estimation unit 250 will be described in detail using Figures 7 to 12. Figure 7 is a diagram showing an image acquired by the imaging device 201 when the work machine V1 is located at a position far from the imaging device 201 with its front left part facing the imaging device 201 as in Figure 1. Figure 8 is a diagram showing an image acquired by the imaging device 201 when the work machine V1 is located at a position close to the imaging device 201 with its rear right part facing the imaging device 201, opposite to Figure 1.

[0044] 7 and 8, the images show light spots corresponding to the lamps 50A to 50D. In Fig. 7 and Fig. 8, the distances between the light spots (ad, bd, ab in Fig. 7 and ad', bd', ab' in Fig. 8) are shown as the relative positions of the light spots.

[0045] The mounting positions of each of the lamps 50A-50D are the same in Figure 7 and Figure 8. However, in Figure 7, the work machine V1 is farther from the imaging device 201 than in Figure 8, and in Figure 8, the work machine V1 is closer to the imaging device 201 than in Figure 7. For this reason, the distances (ad, bd, ab) between each of the light points in the image in Figure 7 and the distances (ad', bd', ab') between each of the light points in the image in Figure 8 differ depending on the position and attitude of the work machine V1 relative to the imaging device 201, even though the actual distances between each of the lamps 50A-50D on the work machine V1 are the same. The position estimation unit 250 estimates the position of the work machine V1 relative to the imaging device 201 by back-calculating from the actual distances between each of the lamps 50A-50D acquired from the mounting position information and the distances between each of the lamps 50A-50D corresponding to each of the light points in each image.

[0046] It is preferable that the number of lamps 50A-50D attached to the work machine V1 be three or more. The reason for this will be explained using Figs. 9 to 12. Fig. 9 is a top view showing the positional relationship between the work machine V1 and the imaging device 201 when there are two lamps 50A-50D. Fig. 10 is a diagram showing an image captured by the imaging device 201 in the case shown in Fig. 9. Fig. 11 is a top view showing the positional relationship between the work machine V1 and the imaging device 201 when the number of lamps 50A-50D is increased to three compared to Fig. 9. Fig. 12 is a diagram showing an image captured by the imaging device 201 in the case shown in Fig. 11.

[0047] When the work machine V1 assumes the postures shown in Figures 9(a) and 9(b) relative to the image capturing device 201, the light spots corresponding to lamps 50A and 50D appear as in the images shown in Figures 10(a) and 10(b), respectively. In this case, even though the work machine V1 is closer to the image capturing device 201 in the case of Figure 9(b) than in Figure 9(a), the distance ad between the light spots is shorter, making it difficult to estimate the position of the work machine V1 relative to the image capturing device 201.

[0048] 11(a) and 11(b), when the work machine V1 assumes the same posture as shown in Figures 9(a) and 9(b) relative to the image capturing device 201, if three lamps 50A, 50B, and 50D are attached to the work machine V1, the light points corresponding to lamps 50A, 50B, and 50D will appear as in the images shown in Figures 12(a) and 12(b). In this case, even though the work machine V1 is closer to the image capturing device 201 in the case of Figure 11(b) than in Figure 11(a), the distance ad between the light points is shorter, while the distances ab and bd between the light points are longer, so the position of the work machine V1 relative to the image capturing device 201 can be estimated.

[0049] It is even more preferable that the number of lamps 50A-50D attached to the work machine V1 is four or more. In this case, the influence of errors that occur when calculating the relative positions using the least squares method or the like can be suppressed, and even if some of the lamps 50A-50D do not fall within the imaging range of the imaging device 201, the number of light points captured in the image can be three or more.

[0050] FIG. 13 is a flowchart showing the flow of operations of the light-emitting control device 300 and the position estimation device 200.

[0051] In step s1, the light-emitting control device 300 causes each of the lamps 50A to 50D to emit light in a light-emitting pattern that differs in time series for each of the lamps 50A to 50D.

[0052] In step s2, the imaging device 201 of the position estimation device 200 acquires images of the lamps 50A to 50D and transmits them to the image processing device 203.

[0053] In step s3, the image processing device 203 of the position estimation device 200 extracts a pattern in which the brightness of the pixels constituting the image changes over time from multiple images acquired consecutively in a time series, and identifies each of the lamps 50A to 50D appearing in the image from each light point in the image that changes according to the extracted pattern.

[0054] In step s4, the image processing device 203 calculates the relative positions of the lamps 50A to 50D within the image.

[0055] In step s5, the image processing device 203 estimates the position of the work machine V1 relative to the position estimation device 200 (imaging device 201) from the relative positions of each of the lamps 50A to 50D in the image and the mounting positions of each of the lamps 50A to 50D on the work machine V1.

[0056] In step s6, the image processing device 203 estimates the position of the work machine V1 at the work site from the position of the work machine V1 relative to the position estimation device 200 (imaging device 201) and the installation position of the position estimation device 200 (imaging device 201) at the work site.

[0057] In step s7, the communication device 202 of the position estimation device 200 transmits the estimated position of the work machine V1 at the work site to the work machine V1 as vehicle body position information.

[0058] As described above, the position estimation system S according to the first embodiment is a position estimation system including a work machine V1 operating at a work site and a position estimation device 200 located at the work site. The work machine V1 is equipped with multiple lamps 50A-50D attached to different positions on the work machine V1 and a light-emitting control device 300 that controls the light emission of the lamps 50A-50D. The position estimation device 200 is equipped with an imaging device 201 that captures images of the lamps 50A-50D and an image processing device 203 that processes images acquired by the imaging device 201. The light-emitting control device 300 controls the light emission of the lamps 50A-50D using a light-emitting pattern that differs over time for each lamp 50A-50D. The image processing device 203 has a pattern extraction unit 210 that extracts from the acquired image a pattern in which the brightness of the pixels constituting the image changes over time. The image processing device 203 also has a relative position calculation unit 220 that calculates the relative positions of the lamps 50A-50D within the image based on the extracted pattern. The image processing device 203 has a position estimation unit 250 that estimates the position of the work machine V1 at the work site based on the calculated relative positions of the lamps 50A to 50D, the pre-stored mounting positions of the lamps 50A to 50D on the work machine V1, and the installation position of the imaging device 201 at the work site.

[0059] With this configuration, the position estimation system S can use the emitting lamps 50A-50D as markers for estimating the position of the work machine V1, and can accurately estimate the position of the work machine V1 at the work site even in environments with poor visibility, such as dark places or places with flying dust. Moreover, the position estimation system S does not need to use radio waves from GNSS satellites to estimate the position of the work machine V1, and can accurately estimate the position of the work machine V1 at the work site without being affected by the reception environment of those radio waves. Furthermore, the position estimation system S estimates the position of the work machine V1 based on the predetermined installation position of the position estimation device 200 (imaging device 201), and can therefore accurately estimate the position of the work machine V1 at the work site even in environments where there is no terrain or structure that can serve as a reference for position estimation.

[0060] [Second embodiment] A second embodiment of the present invention will be described using Fig. 14 and Fig. 15. In the second embodiment, descriptions of components that are the same as those in the first embodiment will be omitted. Fig. 14 is a diagram schematically showing the appearance of a work machine V1 according to the second embodiment. Fig. 15 is a diagram showing the configuration of a position estimation system S according to the second embodiment.

[0061] A position estimation system S according to the second embodiment is equipped with distance measuring devices 51A-51D instead of lamps 50A-50D as light emitting bodies. Each of the distance measuring devices 51A-51D is a device that emits light (laser light) around the work machine V1 and measures the distance to objects in the vicinity. Each of the distance measuring devices 51A-51D may be configured with LiDAR, for example, and can measure the three-dimensional shape of the area around the work machine V1 by emitting laser light into the surrounding area and detecting reflected light from objects in the vicinity.

[0062] As in the first embodiment, the light emission of each of the distance measuring devices 51A to 51D is controlled by a light emission control signal from the light emission control device 300 according to pre-stored light emission pattern information. However, each of the distance measuring devices 51A to 51D cannot perform measurements when it is in a light emission stopped state. Therefore, it is preferable to set the ratio of the duration of the light emission state and the light emission stopped state included in the light emission pattern, and the timing of transition to the light emission state or the light emission stopped state so as not to interfere with the measurement of each of the distance measuring devices 51A to 51D.

[0063] Therefore, in the light emission pattern according to the second embodiment, the duration of the light emission stopped state is set to be shorter than the duration of the light emission state when each of the distance measuring devices 51A-51D measures distance. In other words, the light emission control device 300 according to the second embodiment controls the light emission of each of the distance measuring devices 51A-51D using a light emission pattern in which the duration of the light emission stopped state is shorter than the duration of the light emission state when each of the distance measuring devices 51A-51D measures distance. For example, if it is desired that each of the distance measuring devices 51A-51D detect an object in the vicinity of the work machine V1 within, for example, 100 ms at the latest after its appearance, the light emission control device 300 according to the second embodiment controls the light emission of each of the distance measuring devices 51A-51D using a light emission pattern in which the duration of the light emission stopped state does not exceed 100 ms at most.

[0064] With this configuration, the position estimation system S according to the second embodiment can use the light-emitting distance measuring devices 51A-51D as light-emitting elements for estimating the position of the work machine V1, making it possible to estimate the position of the work machine V1 at the work site with high accuracy. Furthermore, the position estimation system S according to the second embodiment can use the distance measuring devices 51A-51D that are pre-installed on the work machine V1 as light-emitting elements themselves, eliminating the need to specifically install light-emitting elements and making it possible to estimate the position of the work machine V1 at the work site with a simple configuration. Furthermore, the laser light emitted from the distance measuring devices 51A-51D is more monochromatic and directional than ordinary light, making it easier to distinguish from other surrounding light and making it preferable for use as a light-emitting element. Therefore, the position estimation system S according to the second embodiment can estimate the position of the work machine V1 at the work site with even higher accuracy.

[0065] [Third embodiment] A third embodiment of the present invention will be described using Fig. 16 and Fig. 17. In the third embodiment, descriptions of components that are the same as those in the first embodiment will be omitted. Fig. 16 is a diagram that schematically shows the arrangement of a work machine V1 and a position estimation device 200 according to the third embodiment at a work site. Fig. 17 is a block diagram showing the functions of an image processing device 203 according to the third embodiment.

[0066] A position estimation device 200 according to the third embodiment is installed on another work machine V2 operating at the work site. The work machine V2 is a different work machine from the work machine V1. The work machine V2 is equipped with a self-position detection device such as a GNSS receiver that detects its own position. The work machine V2 transmits its own position detected by the self-position detection device to the position estimation device 200 as installed vehicle body position information. In other words, the position estimation device 200 according to the third embodiment regards the self-position of the work machine V2 detected by the self-position detection device as the installed position of the position estimation device 200 (imaging device 201) at the work site.

[0067] The image processing device 203 according to the third embodiment includes an installation vehicle body position acquisition unit 245 instead of the installation position storage unit 240.

[0068] The installed vehicle body position acquisition unit 245 acquires installed vehicle body position information transmitted from the work machine V2 and transmits it to the position estimation unit 250. The position estimation unit 250 calculates the position of the position estimation device 200 (imaging device 201) at the work site by calculating the position of the work machine V2 at the work site based on the installed vehicle body position information from the installed vehicle body position acquisition unit 245. The position estimation unit 250 then estimates the position of the work machine V1 at the work site based on the calculated position of the position estimation device 200 (imaging device 201) at the work site.

[0069] With this configuration, the position estimation system S according to the third embodiment does not have the position estimation device 200 fixed to the work site, so it is possible to reduce the possibility that the range of movement of the work machine V1 at the work site is large and the work machine V1 will not fit within the imaging range of the imaging device 201. Furthermore, when the work machine V1 is working in a location where it is difficult to receive radio waves from GNSS satellites due to structures at the work site, the position estimation system S according to the third embodiment can estimate the position of the work machine V1 at the work site with higher accuracy, as long as the work machine V2 is located in a location where it can detect its own position, compared to when the position of the work machine V1 is simply detected by a GNSS receiver installed on the work machine V1.

[0070] [Fourth embodiment] A fourth embodiment of the present invention will be described using Fig. 18. In the fourth embodiment, descriptions of components that are the same as those in the first embodiment will be omitted. Fig. 18 is a diagram schematically showing the appearance of a work machine V1 according to the fourth embodiment.

[0071] The work machine V1 according to the fourth embodiment is equipped with lamps 50E to 50H in addition to lamps 50A to 50D. As with the first embodiment, the lamps 50A to 50D are attached to the rear body 5R located behind the steering cylinder 11. The lamps 50E to 50H are attached to the front body 5F located in front of the steering cylinder 11.

[0072] The position estimation device 200 according to the fourth embodiment can estimate the position of the front vehicle body 5F at the work site using lamps 50E-50H by a method similar to the position estimation method using lamps 50A-50D. In this embodiment, the position estimated using lamps 50A-50D corresponds to the position of the rear vehicle body 5R at the work site. In this embodiment, four lamps are attached to each of the front vehicle body 5F and the rear vehicle body 5R, but as described in the first embodiment, the position at the work site can be estimated by attaching at least three lamps to each of the front vehicle body 5F and the rear vehicle body 5R.

[0073] As a result, the position estimation device 200 according to the fourth embodiment can estimate the relative positional relationship between the front and rear vehicle sections 5F and 5R by calculating the difference between the position of the rear vehicle section 5R at the work site estimated using the lamps 50A-50D and the position of the front vehicle section 5F at the work site estimated using the lamps 50E-50H. The position estimation device 200 according to the fourth embodiment can estimate the angle formed between the front and rear vehicle sections 5F and 5R, i.e., the bending angle of the work machine V1, from the positional relationship between the front and rear vehicle sections 5F and 5R. Therefore, the position estimation device 200 according to the fourth embodiment can obtain the bending angle of the work machine V1 even if the work machine V1 is not equipped with a device for detecting the bending angle.

[0074] With this configuration, the position estimation system S according to the fourth embodiment can accurately estimate not only the position of the work machine V1 at the work site, but also the attitude of the work machine V1 at the work site.

[0075] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to these embodiments and various modifications can be made without departing from the spirit of the present invention. In the present invention, elements of one embodiment can be added to elements of another embodiment, elements of one embodiment can be replaced with elements of another embodiment, or some of the elements of one embodiment can be deleted. [Explanation of symbols]

[0076] 1...Bucket, 2...Lift arm, 3...Bell crank, 4...Bucket link, 5...Vehicle body, 5F...Front body, 5R...Rear body, 6...Cab, 10...Engine, 11...Steering cylinder, 12...Lift cylinder, 13...Bucket cylinder, 14...Hydraulic pump, 15...Control valve, 21FL...Front left wheel, 21FR...Front right wheel, 21RL...Rear left wheel, 21RR...Rear right wheel, 22...Drive force transmission device, 23...Center joint, 24F...Front differential, 24R...Rear differential, 25F, 25R...Brake, 50A~50D, 50E~50H...Lamp (illuminant) , 51A to 51D... ranging device (light-emitting body), 100... automatic driving control device, 101... communication device, 200... position estimation device, 201... imaging device, 202... communication device, 203... image processing device, 210... pattern extraction unit, 220... relative position calculation unit, 230... mounting position memory unit, 240... installation position memory unit, 245... installation vehicle body position acquisition unit, 250... position estimation unit, 300... light-emitting control device, 310... light-emitting pattern memory unit, 320... light-emitting control signal generation unit, 500... engine control device, 600... hydraulic control device, 700... travel control device, S... position estimation system, V1, V2... work machine

Claims

1. A work machine position estimation system including a work machine operating at a work site and a position estimation device disposed at the work site, the work machine includes a plurality of light emitters attached to different positions of the work machine, and a light emission control device that controls light emission of the plurality of light emitters, the position estimation device includes an imaging device that captures images of the plurality of light-emitting bodies, and an image processing device that processes images acquired by the imaging device; the light-emitting control device controls light emission of the plurality of light-emitting elements using light-emitting patterns that differ in time series for each of the plurality of light-emitting elements; The image processing device includes: extracting from the image a pattern in which the brightness of pixels constituting the image obtained by capturing the plurality of light-emitting bodies changes over time; calculating relative positions of the plurality of light-emitting elements within the image based on the extracted pattern; The position of the work machine at the work site is estimated based on the calculated relative positions of the plurality of light-emitting elements in the image, the pre-stored attachment positions of the plurality of light-emitting elements on the work machine, and the installation position of the imaging device at the work site. A work machine position estimation system characterized by:

2. The number of the plurality of light emitting devices attached to the work machine is three or more.

2. The work machine position estimation system according to claim 1.

3. the plurality of light-emitting bodies are constituted by a plurality of distance measuring devices that emit light into the surroundings and measure the distance to an object present in the surroundings; The light emission control device controls the light emission of the plurality of distance measuring devices using the light emission pattern in which the plurality of distance measuring devices alternate between a light emission state and a light emission stop state, and the duration of the light emission stop state is shorter than the duration of the light emission state when the plurality of distance measuring devices measure the distance.

2. The work machine position estimation system according to claim 1.

4. the work machine is an articulated wheel loader in which the front and rear portions of the vehicle body are articulated, At least three of the plurality of light emitting bodies are attached to each of the front and rear portions of the vehicle body.

2. The work machine position estimation system according to claim 1.

5. The light emission control device controls light emission of the plurality of light emitters using the light emission pattern that changes the intensities of the light emitted by the plurality of light emitters in a time series manner.

2. The work machine position estimation system according to claim 1.

6. The light emission control device controls light emission of the plurality of light emitters using the light emission pattern that changes wavelengths of light emitted by the plurality of light emitters in a time series manner.

2. The work machine position estimation system according to claim 1.

7. The light emission control device controls light emission from the plurality of light emitters using the light emission pattern that changes the polarization state of the light emitted by the plurality of light emitters in a time series manner.

2. The work machine position estimation system according to claim 1.

8. the position estimation device is installed on another work machine operating at the work site, the other work machine is equipped with a self-position detection device that detects its own position, The position estimation device determines the self-position of the other work machine detected by the self-position detection device as the installation position of the imaging device at the work site.

2. The work machine position estimation system according to claim 1.

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