GNSS field reference station for operating machinery

Abstract

The system selects the appropriate satellite for the work machine based on its operating conditions while minimizing the frequency of satellite switching, and then transmits RTK correction data to the machine. [Solution] In a GNSS field reference station that transmits RTK correction data to a work machine using GNSS, based on pre-stored design data of the final construction surface, pre-stored dimensional data of the work machine, and the current position of the work machine received from the work machine, if the front work machine can reach the construction target surface, the union of the second shielding area by the front work machine above the GNSS antenna and the first shielding area is set as the site-aerial shielding area. If the front work machine cannot reach the construction target surface, the first shielding area by the final construction surface above the GNSS antenna of the work machine is set as the site-aerial shielding area, and at least one positioning satellite outside the site-aerial shielding area is selected as the satellite to be used.

Description

Technical Field

[0001] The present invention relates to a GNSS on-site reference station for construction machinery that transmits RTK correction data to construction machinery such as hydraulic excavators using GNSS (Global Navigation Satellite System).

Background Art

[0002] In informationized construction, RTK-GNSS is widely used to obtain the three-dimensional position of construction machinery. In RTK-GNSS, GNSS positioning is performed simultaneously with a GNSS on-site reference station (hereinafter referred to as the reference station) whose position is known to the construction machinery, and by transmitting RTK correction data based on satellite signals obtained at the reference station to the construction machinery in real time, the position of the construction machinery can be obtained with high accuracy. As a means for transmitting RTK correction data from the reference station to the construction machinery, digital simple radios or specific low-power radios are often used. However, these radios have a small data capacity that can be transmitted at one time, and it may be difficult to transmit RTK correction data for satellite signals from all positioning satellites observed at the reference station.

[0003] On the other hand, as construction machinery using RTK-GNSS, a list of positioning satellites is created by selecting a number corresponding to the data capacity that can be transmitted by the radio from positioning satellites that can be observed without being blocked by the front work machine (hereinafter referred to as visible satellites) and transmitted to the reference station, and RTK correction data based on satellite signals observed at the reference station from the positioning satellites in the list is received from the reference station (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the visible satellites observable from the work machine change constantly depending on the operation of the front work machine, etc. Therefore, in the technology of Patent Document 1, as the visible satellites change according to the operation of the work machine, the combination of positioning satellites used for GNSS positioning (hereinafter referred to as "used satellites") switches frequently. In GNSS positioning, if the used satellites switch frequently, the positioning accuracy will not be constant. As a result, the continuity of construction may not be maintained, and unevenness may easily occur on the construction surface.

[0006] The object of the present invention is to provide a GNSS field reference station for work machinery that can improve the stability of RTK-GNSS positioning accuracy by suppressing the frequency of switching between satellites used. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a GNSS field reference station for a work machine that includes a controller for selecting the satellite to be used for calculating RTK correction data, generates the RTK correction data based on satellite signals received from the satellite and transmits it to a work machine using GNSS, wherein the controller calculates a first shielding area above the GNSS antenna of the work machine that is shielded by the final construction surface, based on pre-stored design data of the final construction surface, pre-stored dimensional data of the work machine, and the current position of the work machine received from the work machine, and the front work of the work machine The system provides a GNSS field reference station for a work machine that determines whether the machine can reach the surface to be worked on, calculates a second shielding region that the front work machine can shield above the GNSS antenna of the work machine, assuming the front work machine's tip is in contact with the surface to be worked on, sets the union of the first shielding region and the second shielding region as the current site-above-ground shielding region, and sets the first shielding region as the current site-above-ground shielding region if the front work machine cannot reach the surface to be worked on, and selects at least one positioning satellite outside the site-above-ground shielding region as the satellite to be used. [Effects of the Invention]

[0008] According to the present invention, the frequency of switching between satellites used can be suppressed, thereby improving the stability of RTK-GNSS positioning accuracy. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of a GNSS field reference station for a work machine according to one embodiment of the present invention, and a hydraulic excavator, which is an example of a work machine that communicates with it. [Figure 2] This is a functional block diagram of a GNSS field reference station for a work machine according to one embodiment of the present invention. [Figure 3] These are a plan view and a cross-sectional view showing an example of the final construction surface. [Figure 4] These are examples of plan and cross-sectional views of the final construction surface. [Figure 5] This diagram illustrates an example of an area of ​​shielding above a construction site. [Figure 6] This diagram illustrates an example of a method for calculating the union region of the occupying areas above a construction site, calculated for each of the multiple hydraulic excavators operating at the construction site. [Figure 7] This diagram illustrates an example of a method for calculating the union region of the occupying areas above a construction site, calculated for each of the multiple hydraulic excavators operating at the construction site. [Figure 8] This flowchart illustrates the selection process performed by the reference station controller of the satellite used for generating RTK correction data. [Figure 9] This is a flowchart showing the detailed procedure for step S102 in Figure 8. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] (Working machinery) Figure 1 is a schematic diagram of a GNSS field reference station for a work machine according to one embodiment of the present invention, and a hydraulic excavator, which is an example of a work machine that communicates with it. For the hydraulic excavator 1, the left side in Figure 1, where the front work implement 6 is attached, is the front of the slewing body 3. The hydraulic excavator 1 illustrated in Figure 1 is a crawler type, but it may also be a wheeled type. The hydraulic excavator 1 has at least one of the following: a machine guidance function that displays the positional relationship between the bucket tip (bucket claw) 12D and the final construction surface on a monitor 60 in the operator's cab 4, and a machine control function that restricts the movement of the front work implement 6 so that the bucket tip 12D does not exceed the final construction surface.

[0012] The hydraulic excavator 1 illustrated in Figure 1 comprises a crawler-type vehicle 2, a slewing body 3 rotatably mounted on the upper part of the vehicle 2, and a front work implement 6, which is a multi-jointed working arm whose base is attached to the front of the slewing body 3. The symbol G in the figure represents the ground (contact surface) on which the vehicle 2 makes contact.

[0013] The front work implement 6 has a boom 6A whose base end is connected to the slewing body 3 via axes extending to the left and right, an arm 6B whose base end is connected to the tip of the boom 6A via axes extending to the left and right, and a bucket 6C whose base end is connected to the tip of the arm 6B via axes extending to the left and right. In addition, a boom cylinder 11A, an arm cylinder 11B, and a bucket cylinder 11C are provided as hydraulic actuators to drive the boom 6A, arm 6B, and bucket 6C, respectively. By extending and retracting the boom cylinder 11A, arm cylinder 11B, and bucket cylinder 11C, the boom 6A, arm 6B, and bucket 6C rotate along a plane that is perpendicular to the ground surface G and extends forward and backward. The slewing body 3 can be driven to rotate left and right around a slewing centerline O perpendicular to the ground surface G by a slewing motor (not shown).

[0014] The hydraulic excavator 1 is equipped with a plurality of angle sensors 75A, 75B, 75C for detecting the angles of the boom 6A, arm 6B, and bucket 6C of the front working machine 6, and an angle sensor 23 for detecting the roll angle, pitch angle, and yaw angle of the revolving body 3. In this embodiment, an inertial measurement unit (IMU) is used as these angle sensors 75A, 75B, 75C, 23. The angle sensor 75A is attached to the boom 6A, the angle sensor 75B is attached to the arm 6B, the angle sensor 75C is attached to the bucket 6C, and the angle sensor 23 is attached to the revolving body 3. The outputs (detection signals) of the angle sensors 75A, 75B, 75C, 23 are input to the controller 40 via connecting lines. As the angle sensors of the front working machine 6, other types of angle sensors such as potentiometers and rotary encoders may be used. Also, the angle sensor 75C may be attached to the bucket link 6D instead of the bucket 6C.

[0015] The revolving body 3 is equipped with a cab 4, GNSS antennas (positioning antennas) 50A, 50B, a radio 7, a GNSS receiver 51, and a controller 40.

[0016] Inside the cab 4, a plurality of operation levers (not shown) operated by the operator and a monitor 60 for displaying the positional relationship between the bucket tip 12D, which is the tip of the bucket 6C, and the final construction surface are installed.

[0017] The two GNSS antennas 50A, 50B receive satellite signals (including satellite codes, carriers, satellite orbits, and satellite signal reception levels, etc.) from a plurality of positioning satellites (GNSS satellites).

[0018] The GNSS antenna 50A is the main antenna for receiving satellite signals to measure the position coordinates of the hydraulic excavator 1 (for example, the center of rotation line O), and the GNSS antenna 50B is the sub-antenna for receiving satellite signals to obtain the baseline vector from the GNSS antenna 50A and calculate the azimuth angle of the revolving body 3.

[0019] The GNSS receiver 51 calculates the position coordinates of the hydraulic excavator 1 and the azimuth of the slewing body 3 based on the satellite signals received by the GNSS antennas 50A and 50B. In this embodiment, the positions of the two GNSS antennas 50A and 50B and the azimuth angle of the slewing body 3 are calculated by a single GNSS receiver 51. However, the hydraulic excavator 1 may be equipped with two GNSS receivers 51, one for each of the two GNSS antennas 50A and 50B.

[0020] Radio 7 receives RTK correction data (described later) transmitted from GNSS field reference station 8 (hereinafter, reference station 8). Radio 7 also transmits data such as the model information of the hydraulic excavator 1 on which it is mounted, the position coordinates of its current location, and the orientation of the slewing body 3 to reference station 8.

[0021] The controller 40 is a computer that has the function of calculating the position coordinates of a desired part (bucket tip 12D in this embodiment) on the front work machine 6 based on the position and orientation calculated by the GNSS receiver 51 and the detection signals from the angle sensors 75A, 75B, 75C, 23.

[0022] (GNSS field reference station) Here, each positioning satellite transmits a satellite signal (electromagnetic wave) containing transmission time information. The GNSS receiver 51 estimates the distance between each positioning satellite and the GNSS antennas 50A and 50B from the reception time of the electromagnetic wave from each positioning satellite and the transmission time contained in that electromagnetic wave, and calculates the position of the GNSS antennas 50A and 50B. However, the calculated distance between each positioning satellite and the GNSS antennas 50A and 50B may contain errors. These errors occur due to factors such as the fact that the velocity change of electromagnetic waves generated by the ionosphere and water vapor present between the positioning satellite and the GNSS antennas 50A and 50B differs depending on the azimuth and elevation angles of each positioning satellite, that the orbital information transmitted from each positioning satellite is slightly different from the actual value, and that there are slight errors in the clocks between each positioning satellite.

[0023] To reduce such errors, RTK-GNSS (Real-time Kinematic GNSS) is used, as mentioned earlier, which receives RTK correction data with the radio 7 to determine position. The RTK correction data received by the radio 7 of the hydraulic excavator 1 is transmitted from the base station 8 for the work machine.

[0024] The base station 8 comprises a GNSS antenna 80, a GNSS receiver 81, a base station controller 82, and a radio 87.

[0025] The GNSS antenna 80 is installed at a location within a few kilometers of the hydraulic excavator 1, for example, at the construction site where the hydraulic excavator 1 is operating, and, like the GNSS antennas 50A and 50B on the hydraulic excavator 1, receives satellite signals from various positioning satellites. The geographic coordinate system of the GNSS antenna 80 is known.

[0026] The GNSS receiver 81 calculates the position coordinates of the GNSS antenna 80 based on the satellite signals received by the GNSS antenna 80, similar to the GNSS receiver 51 of the hydraulic excavator 1, and also generates RTK correction data. The functions of the GNSS receiver 81 will be briefly explained later using Figure 2.

[0027] The base station controller 82 is a computer equipped with memory devices (e.g., RAM, ROM, HHD, SSD) and a computing device (e.g., CPU), and has a satellite selection function that selects the positioning satellite (satellite to be used) to be used in the calculation of RTK correction data in the GNSS receiver 81. The functions of the base station controller 82 will be explained in detail in Figure 2 and subsequent figures.

[0028] Radio 87 transmits RTK correction data generated by GNSS receiver 81 to radio 7 on hydraulic excavator 1. For example, digital simple radios, low-power radios, etc., can be used for radios 87 and 7. The correction data transmitted from radio 87 of base station 8 is transmitted to GNSS receiver 51 on hydraulic excavator 1 via radio 7 and used for correction calculations of the position coordinates of hydraulic excavator 1.

[0029] (Functional block of the base station) Figure 2 is a functional block diagram of the base station 8. The work machine information receiving unit 87a shown in Figure 2 is the receiver part of the radio 87 and receives data such as the model information of the hydraulic excavator 1, the position coordinates of its current position, and the orientation of the slewing body 3 transmitted from the radio 7 of the hydraulic excavator 1. The RTK correction data transmitting unit 87b is the transmitter part of the radio 87 and transmits RTK correction data generated by the GNSS receiver 81. The transmitted RTK correction data is received by the radio 7 of the hydraulic excavator 1 as described above.

[0030] The GNSS receiver 81 includes an RF front-end unit 131, a baseband unit 132, a navigation processing unit 133, a satellite selection unit 134, and a correction data generation unit 135. The RF front-end unit 131 amplifies the satellite signals from each positioning satellite received by the GNSS antenna 80 of the reference station 8 and converts them into digital signals. The baseband unit 132 acquires observation data from the satellite signals converted into digital signals. The navigation processing unit 133 calculates the orbital information of each positioning satellite and the position coordinates of the reference station 8 from the observation data acquired by the baseband unit 132. The satellite selection unit 134 receives the satellite selection information made by the reference station controller 82 and selects the satellites to be used for calculating RTK correction data according to this selection information. The correction data generation unit 135 generates RTK correction data including the above observation data and information such as the position coordinates of the reference station 8 calculated based on the observation data. The RTK correction data generated by the correction data generation unit 135 is transmitted to the hydraulic excavator 1 from the aforementioned RTK correction data transmission unit 87b.

[0031] (Reference station controller) As shown in Figure 2, the reference station controller 82 includes a construction section memory unit 111, a construction plane memory unit 112, a dimension data memory unit 113, a satellite orbit memory unit 114, a position and direction identification unit 118, a machine dimension identification unit 117, a shielding area calculation unit 115, a shielding area setting unit 116, a satellite selection unit 122, a positioning accuracy prediction unit 123, a positioning accuracy determination unit 124, and a satellite transmission unit 125. The construction section memory unit 111, the construction plane memory unit 112, the dimension data memory unit 113, and the satellite orbit memory unit 114 are composed of the memory device or its memory area of ​​the reference station controller 82. The position and direction determination unit 118, the machine dimension determination unit 117, the shielding area calculation unit 115, the shielding area setting unit 116, the satellite selection unit 122, the positioning accuracy prediction unit 123, the positioning accuracy determination unit 124, and the satellite transmission unit 125 are functions executed by the calculation unit of the base station controller 82, and may be implemented by hardware elements such as circuits or by software elements. These elements will be described in order below.

[0032] -Construction section memory section / Construction plane memory section- The construction section memory unit 111 and the construction plan memory unit 112 store pre-stored design data of the final construction surface (final completed form). Figure 3(a) is a plan view showing an example of the final construction surface, and Figure 3(b) is a cross-sectional view showing an example of the final construction surface. The design data (3D data) of the final construction surface is a combination of a cross-sectional view 301 (Figure 3(a)) and a plan view 302 (Figure 3(b)) in which position coordinates are pre-given in a three-dimensional coordinate system such as latitude, longitude, and ellipsoidal height. The cross-sectional view 301 is a view of a cross section F perpendicular to the center line CL of the final construction surface 301C in the plan view 302. The cross-sectional view 301 is pre-recorded in the construction section memory unit 111, and the plan view 302 is pre-recorded in the construction plan memory unit 112.

[0033] -Dimensional data storage unit- The dimension data storage unit 113 has the dimension data of the hydraulic excavator 1 pre-recorded. The dimension data storage unit 113 stores the dimensions of the boom 6A, arm 6B, and bucket 6C of the front work implement 6, the positions of the GNSS antennas 50A and 50B, the position of the connecting axis (foot pin) between the slewing body 3 and the front work implement 6, and the position of the intersection point between the slewing centerline O of the slewing body 3 and the ground surface G (Figure 1), for each model of hydraulic excavator 1. The positions of the GNSS antennas 50A and 50B, the foot pin, and the intersection point between the slewing centerline O and the ground surface are given in the local coordinate system of the hydraulic excavator 1.

[0034] -Satellite orbit storage unit- The satellite orbit memory unit 114 sequentially records the orbital information of each positioning satellite calculated by the navigation processing unit 133 of the reference station GNSS receiver 81.

[0035] -Position and direction identification part- The position and orientation determination unit 118 extracts the hydraulic excavator 1 located on the plan view 302 recorded in the construction plan memory unit 112 based on the current position of the hydraulic excavator 1 (the intersection of the slewing centerline O and the ground surface) received from the hydraulic excavator 1 via the radio 87 (work machine information receiving unit 87a), and determines the current position of the hydraulic excavator 1 located on the plan view 302 and the current orientation of the slewing body 3.

[0036] - Machine Dimension Identification Section - The machine dimension identification unit 117 identifies the dimension data for the corresponding model based on the model information of the hydraulic excavator 1 whose current position has been received by the wireless device 87 (working machine information receiving unit 87a), and reads it from the dimension data recording unit 113.

[0037] -Occluded area calculation unit- The shielding area calculation unit 115 calculates the first shielding area 721 (Figure 5) based on the design data of the final construction surface (section view 301 and plan view 302) pre-stored in the construction section memory unit 111 and the construction plan view memory unit 112, the dimensional data of the hydraulic excavator 1 pre-stored in the dimension data memory unit 113, and the current position of the hydraulic excavator 1 received from the hydraulic excavator 1. The first shielding area 721 is a mask area where the air above the GNSS antennas 50A and 50B of the hydraulic excavator 1 is shielded by the final construction surface. The first shielding area 721 is set sequentially for each hydraulic excavator 1 if there are multiple hydraulic excavators 1 at the construction site (position coordinate area of ​​plan view 302). Furthermore, for a hydraulic excavator 1 equipped with two GNSS antennas 50A and 50B, as in the example in Figure 1, the first shielding area 721 is set for both GNSS antennas.

[0038] Furthermore, the shielding area calculation unit 115 determines whether the front work implement 6 of the hydraulic excavator 1, which is currently located, can reach the target surface of the final construction surface, that is, whether the hydraulic excavator 1 is positioned in a location where it can work on the target surface. The target surface is the surface that the hydraulic excavator 1 is currently working on, which is the final completed surface. In this embodiment, the target surface is automatically set by the shielding area calculation unit 115 based on the orientation of the slewing body 3. The process of setting this target surface will be described later using Figure 4(a). However, if the setting is manually entered by an operator such as a construction manager using the input device 89, the shielding area calculation unit 115 will set the target surface based on the setting made by the input device 89, regardless of the current orientation of the slewing body 3.

[0039] When the front work implement 6 reaches the construction target surface, the shielding area calculation unit 115 further calculates a second shielding area 610 (Figure 5). The second shielding area 610 is a masked area where the air above the GNSS antennas 50A and 50B of the hydraulic excavator 1 is shielded by the front work implement 6, which simulates a state where the bucket tip 12D is in contact with the construction target surface. The second shielding area 610 is set sequentially for each hydraulic excavator 1 if there are multiple hydraulic excavators 1 capable of working on each construction target surface. Also, similar to the first shielding area 721, for a hydraulic excavator 1 equipped with two GNSS antennas 50A and 50B, the second shielding area 610 is set for both GNSS antennas. The shielding area calculation unit 115 calculates the second shielding area 610 under the condition that the hydraulic excavator 1 is directly facing the construction target surface. The condition for the hydraulic excavator 1 to be directly facing the construction target surface is, for example, when the final construction surface 301A is the construction target surface in the cross-sectional view 301 of Figure 3(a), the condition is that the hydraulic excavator 1 faces the final construction surface 301A with the front work implement 6 facing the final construction surface 301A, and the front work implement 6 operates along the cross-sectional view 301 (Figure 4(b)).

[0040] -Occluded area setting section- The shielding area setting unit 116 sets the union of the first shielding area 721 and the second shielding area 610 as the current site-above-ground shielding area Si (Figure 5) for hydraulic excavators 1 whose front work equipment 6 can reach the construction target surface, and sets the first shielding area 721 as the current site-above-ground shielding area Si for hydraulic excavators 1 whose front work equipment 6 cannot reach the construction target surface. In this specification, "site-above-ground shielding area" refers to a masked area where the airspace above the GNSS antennas 50A and 50B of the hydraulic excavator 1 is shielded by the final construction surface or the front work equipment 6, assuming a state in which the bucket tip 12D is in contact with the construction target surface. i is the number of the hydraulic excavator 1 for which the site-above-ground shielding area is set (1, 2, 3...n). For example, the site-above-ground shielding area Si of the first hydraulic excavator 1 is denoted as site-above-ground shielding area S1, the site-above-ground shielding area Si of the second hydraulic excavator 1 is denoted as site-above-ground shielding area S2. Finally, the shielding region setting unit 116 calculates the union region Ss (Figure 7(d)) ​​of the shielding regions Si above the site.

[0041] Furthermore, if the GNSS positioning accuracy predicted when using a positioning satellite selected according to the union region Ss of the occluded areas Si above the site is below the acceptable accuracy, the occluded area setting unit 116 performs an exclusion process to exclude the occluded area Si above the site with the lowest priority, and recalculates the union region Ss of the occluded areas Si above the site.

[0042] One example of a site overhead shielding area Si with the lowest priority is the site overhead shielding area Si related to the hydraulic excavator 1 that is furthest from its respective construction target surface. The distance between the construction target surface and the hydraulic excavator 1 is, for example, the shortest distance between the pivot centerline O of the hydraulic excavator 1 and the final construction target surface 301A on the cross-sectional view 301, or the horizontal distance between the toe of the slope 301A1 of the final construction target surface 301A and the pivot centerline O in the example of Figure 3(a). Another example of a site overhead shielding area Si with the lowest priority is the site overhead shielding area Si related to the hydraulic excavator 1 that has the highest relative height to its respective construction target surface. The relative height of the construction target surface is, for example, the highest point of the final construction target surface 301A relative to the ground surface of the hydraulic excavator 1 on the cross-sectional view 301, or the height of the shoulder of the slope 301A2 in the example of Figure 3(a).

[0043] -Satellite Selection Section- The satellite selection unit 122 selects at least one positioning satellite that is outside the occluded area Si above the construction site as the satellite to be used. In this case, the satellite selection unit 122 selects, for example, all positioning satellites that are outside the occluded area Si above the construction site as the satellite to be used. If there are multiple hydraulic excavators 1 operating at the construction site, the satellite selection unit 122 selects at least one positioning satellite that is outside the union area Ss of the occluded areas Si above the construction site calculated for each hydraulic excavator 1 as the satellite to be used. In this case, the satellite selection unit 122 initially selects, for example, all positioning satellites that are outside the union area Ss of the occluded areas Si above the construction site as the satellite to be used. However, depending on the GNSS positioning accuracy expected when using the selected positioning satellites, the occluded area setting unit 116 may subsequently perform the exclusion process. In this case, the satellite selection unit 122 performs a re-selection process to re-select at least one positioning satellite that is outside the union area Ss after the exclusion process as the satellite to be used. In this case, the satellite selection unit 122, for example, initially selects all positioning satellites that are outside the union region Ss after the exclusion process as satellites to be used.

[0044] -Positioning Accuracy Prediction Unit- The positioning accuracy prediction unit 123 performs a prediction process to predict the GNSS positioning accuracy when using the satellites selected by the satellite selection unit 122. The method for calculating GNSS positioning accuracy is not limited, but in this embodiment, the positioning accuracy prediction unit 123 calculates, for example, DOP (Dilution of Precision) as the GNSS positioning accuracy in this prediction process. DOP is a parameter determined based on the geometric arrangement of the satellites used. Although the GNSS positioning accuracy can also be calculated individually for the position of the hydraulic excavator 1, the distance between the hydraulic excavator 1 and the reference station 8 is short, within a few kilometers, so in this embodiment, it is calculated only for the position of the reference station 8.

[0045] -Positioning accuracy determination unit- The positioning accuracy determination unit 124 determines whether the GNSS positioning accuracy predicted by the positioning accuracy prediction unit 123 exceeds a preset tolerance accuracy, that is, whether it is better than the tolerance accuracy. If the positioning accuracy determination unit 124 determines that the GNSS positioning accuracy exceeds the tolerance accuracy, the satellites to be used are determined based on the current selection. If the positioning accuracy determination unit 124 determines that the GNSS positioning accuracy is below the tolerance accuracy, the exclusion process by the occlusion area setting unit 116, the re-selection process by the satellite selection unit 122, and the prediction process by the positioning accuracy prediction unit 123 are repeatedly executed until the GNSS positioning accuracy exceeds the tolerance accuracy. Once the GNSS positioning accuracy exceeds the tolerance accuracy through this repeated process, the satellites to be used are determined based on the selection at the time the GNSS positioning accuracy exceeded the tolerance accuracy.

[0046] -Satellite Transmitter Used- The satellite transmission unit 125 transmits the satellite selection information (list) that has been determined by the positioning accuracy determination unit 124 to exceed the acceptable accuracy to the GNSS receiver 81. The transmitted satellite selection information is received by the satellite setting unit 134 as described above and used by the GNSS receiver 81 for calculating RTK correction data.

[0047] (Calculation of the second shielded region) Figure 4(a) is an example of a plan view of the final construction surface where the hydraulic excavator 1 operates, and Figure 4(b) is an example of a cross-sectional view thereof. The plan view in Figure 4(a) corresponds to the plan view 302 in Figure 3(b), and the cross-sectional view in Figure 4(b) corresponds to the cross-sectional view 301 in Figure 3(a). Using Figures 4(a) and 4(b), the calculation method for the second shielding area 610, that is, the shielding area by the front work machine 6, will be explained.

[0048] As previously described, the position and orientation identification unit 118 identifies the current position on the plan view 302 (the intersection point of the pivot center line O and the ground) and the current orientation vector AZ of the pivot body 3 for the hydraulic excavator 1, whose pivot center line O is located on the plan view 302, as shown in Figure 4(a), based on the information received from the hydraulic excavator 1 and the dimension data stored in the dimension data storage unit 113. Accordingly, the shielding area calculation unit 115 extracts a cross-sectional view 301 (Figure 4(b)) from the construction cross-section storage unit 111 that includes the current position of the hydraulic excavator 1 and is perpendicular to the center line CL of the final construction surface.

[0049] Furthermore, the shielding area calculation unit 115 selects and sets the target surface for construction from the final construction surfaces 301A and 301B. The target surface for construction that each hydraulic excavator 1 should perform is determined by the operator's manual setting using the input device 89. If it is not set manually, the shielding area calculation unit 115 automatically sets the target surface for construction according to the azimuth vector AZ of the slewing body 3 identified by the position and azimuth identification unit 118. For example, as shown in the example in Figure 4(a), if the azimuth vector AZ of the slewing body 3 is closer to the azimuth vector AZ-A, which points from the current position (slewing centerline O) of the hydraulic excavator 1 towards the final construction surface 301A along the cross-section F, than to the azimuth vector AZ-B, which points from the current position (slewing centerline O) of the hydraulic excavator 1 towards the final construction surface 301B along the cross-section F, then the final construction surface 301A is set as the current target surface for construction of the hydraulic excavator 1.

[0050] Once the construction target surface is set, the shielding area calculation unit 115 virtualizes a state in which the hydraulic excavator 1 is at its current position and facing the final construction surface 301A, which is the construction target surface, as shown in Figure 4(b), that is, a state in which the front work implement 6 operates along the cross-sectional view 301, and based on the current position and dimensional data, it virtualizes all the positions of the front work implement 6 in which the bucket tip 12D is in contact with the final construction surface 301A at the current position. In the example in Figure 4(b), three positions 605a, 605b, and 605c of the front work implement 6 are shown, but there are infinitely many positions of the front work implement 6 in which the bucket tip 12D is in contact with the final construction surface 301A, and in reality the number of positions of the front work implement 6 virtualized by the shielding area calculation unit 115 is even larger. In other words, the shielding area calculation unit 115 calculates the trajectory of the front work machine 6 when the bucket tip 12D moves along the final construction surface 301A at its current position, and calculates the three-dimensional envelope of the trajectory of the front work machine 6. The shielding area calculation unit 115 then calculates the area in the sky that is shielded by the attitude group of the front work machine 6 as seen from the GNSS antennas 50A and 50B as the second shielding area 610. For example, a positioning satellite 615c (Figure 5) located in the second shielding area 610 as seen from the GNSS antenna 50A is an invisible satellite whose satellite signal is shielded by the front work machine 6 as the bucket tip 12D moves along the final construction surface 301A. Note that the above calculation of the second shielding area is not performed for the final construction surface 301B, which was not set as the construction target surface.

[0051] (Calculation of the area of ​​obstruction above the site) Figure 5 shows an example of the occluded area Si above the construction site. Figure 5 shows the area above one hydraulic excavator 1 using a polar coordinate system 720 centered on the current position of the GNSS antenna 50A. In the polar coordinate system 720, the radial coordinate represents the elevation angle, and the angular coordinate represents the azimuth angle. Figure 5 corresponds to a view from the zenith side, projecting the occluded area onto a celestial sphere centered on the position coordinates measured by the GNSS antenna 50A. Using Figure 5, the calculation method for the aforementioned occluded area Si above the construction site, that is, the occluded area by the final construction surface and the front work machine 6, will be explained. Note that Figure 5 shows an example where a second occluded area 610 is calculated for the target hydraulic excavator 1, but as previously described, the second occluded area 610 is not calculated for hydraulic excavators 1 located in a position where the front work machine 6 does not reach the construction surface. In addition, although not specifically shown, similar polar coordinates centered on the current position of the GNSS antenna 50B are also generated as needed. For example, the shielding area calculated based on GNSS antenna 50B is larger than the shielding area calculated based on GNSS antenna 50A, and it is desirable to select the satellite to be used based on the shielding area based on GNSS antenna 50B. In such cases, the shielding area based on GNSS antenna 50B is used.

[0052] Figure 5 shows, for reference, a first shielding region 721 shielded by the final construction surface, a second shielding region 610 that can be shielded by the front work implement 6 with its bucket tip 12D in contact with the construction surface, and a third shielding region 723 that can be shielded by the front work implement 6 assuming all positions, without considering the positional relationship between the construction surface and the bucket tip 12D. Since Figure 5 is an example where the front work implement 6 reaches the construction surface, the shielding region calculation unit 115 sets the union of the first shielding region 721 and the second shielding region 610 as the current site-above-ground shielding region Si. However, for the hydraulic excavator 1 in a position where the front work implement 6 does not reach the construction surface, as previously described, the second shielding region 610 is not calculated, and the first shielding region 721 is set as the current site-above-ground shielding region Si.

[0053] For the sake of explanation, among the positioning satellites 615 located in the polar coordinate system 720, those that are outside all of the shielding areas—the first shielding area 721, the second shielding area 610, and the third shielding area 723—as shown in Figure 5, are assigned the designation 615a. Furthermore, positioning satellites 615 located in the third shielding area 723 but outside of the first shielding area 721 and the second shielding area 610 are assigned the designation 615b. Positioning satellites located in the first shielding area 721 or the second shielding area 610 are assigned the designation 615c. In this case, the shielding area setting unit 116 sets the union of the first shielding area 721 and the second shielding area 610 as the shielding area Si above the site. Positioning satellites 615c (black) located in the shielding area Si above the site are treated as invisible satellites and excluded from the satellites used. Then, positioning satellites 615a and 615b (white), which are outside the shielded area Si above the site, are treated as visible satellites and selected as satellites to be used by the satellite selection unit 122.

[0054] Furthermore, the satellite signal of positioning satellite 615b located in the third shielding area 723 may be temporarily blocked depending on the attitude of the front work machine 6. Therefore, including positioning satellite 615b in the list of satellites used may affect GNSS positioning accuracy. However, the situation in which the satellite signal of positioning satellite 615b is blocked is limited to when the bucket tip 12D of the front work machine 6 is not touching the surface to be worked on, so this does not lead to a deterioration in construction accuracy.

[0055] (If there are multiple hydraulic excavators) An example of how to calculate the union region Ss of the site-above-ground shielding region Si calculated for each of the multiple hydraulic excavators 1 operating at the construction site will be explained using Figures 6 and 7(a) to 7(d). Figure 6 corresponds to Figure 4(a), and Figures 7(a) to 7(d) correspond to Figure 5.

[0056] For example, suppose that on the plan view 302 of the construction site, the slewing centerlines O1, O2, and O3 of the three hydraulic excavators 1 are located as shown in Figure 6, and the azimuth vectors AZ1, AZ2, and AZ3 of the slewing bodies 3 of the three hydraulic excavators 1 are as shown in Figure 6. In this case, since the azimuth vectors AZ-A1, AZ-A2, and AZ-A3 of the slewing bodies 3 of each hydraulic excavator 1 are all closer to the azimuth vectors AZ-A1, AZ-A2, and AZ-A3 that are directly facing the final construction surface 301A than to the vector that is directly facing the final construction surface 301B, the shielding area calculation unit 115 sets the final construction surface 301A on the cross-sections F1, F2, and F3 that are perpendicular to the centerline CL at the slewing centerlines O1, O2, and O3 of each hydraulic excavator 1 as the target construction surface.

[0057] Once the construction target surface is set, as shown in Figures 7(a) to 7(c), the shielding area calculation unit 115 calculates the first shielding areas 721-1, 721-2, 721-3 and the second shielding areas 610-1, 610-2, 610-3 for each of the three hydraulic excavators 1. The shielding area setting unit 116 then sets the above-site shielding areas S1, S2, and S3 for each of the three hydraulic excavators 1, and further sets the union area Ss obtained by superimposing the above-site shielding areas S1, S2, and S3 on the polar coordinate system 720. Finally, the positioning satellite constellation 615v (white), which is outside the union area Ss of the above-site shielding areas S1, S2, and S3, is selected as the satellite to be used.

[0058] (Satellite selection process) Figure 8 is a flowchart illustrating the selection process performed by the reference station controller 82 for the satellite used to generate RTK correction data. The process shown in Figure 8 is repeatedly executed at predetermined time intervals while the hydraulic excavator 1 is operating at the construction site.

[0059] When the processing shown in Figure 8 begins, the reference station controller 82, using the position and orientation identification unit 118, identifies the current position of the hydraulic excavator 1 and the orientation of the slewing body 3 within the plan view 302, based on the model, current position, and orientation information received from the hydraulic excavator 1 and the plan view 302, as described above (step S101). If information such as the current position is received from multiple hydraulic excavators 1, the reference station controller 82 performs the processing in step S101 in parallel for each hydraulic excavator 1 (steps S101-1 to S101-n).

[0060] Next, the reference station controller 82 uses the shielding area calculation unit 115 to calculate the first shielding area 721 and the second shielding area 610 of the hydraulic excavator 1 at its current position, based on the current position, orientation, dimensional data of the hydraulic excavator 1 and the cross-sectional view 301, and sets the shielding area Si above the site using the shielding area calculation unit 115 (step S102). If the current position and orientation of multiple hydraulic excavators 1 are specified, the reference station controller 82 performs the process in step S102 in parallel for each hydraulic excavator 1 (steps S102-1 to S102-n).

[0061] Once the overhead shielding area Si is set, the reference station controller 82 uses the shielding area setting unit 116 to set and maintain the union area Ss of all overhead shielding areas Si set in step S102 (step S103).

[0062] Once the union region Ss is set, the reference station controller 82 uses the satellite selection unit 122 to select the positioning satellite group 615v that are outside the union region Ss based on the orbital information of each positioning satellite and the union region Ss of the overhead obstruction region Si, and the positioning accuracy prediction unit 123 predicts the GNSS positioning accuracy when using these positioning satellite group 615v (step S104).

[0063] Next, the base station controller 82 uses the positioning accuracy determination unit 124 to determine whether the GNSS positioning accuracy calculated in step S104 is higher than a preset allowable accuracy (step S105). If the predicted GNSS positioning accuracy is higher than the allowable accuracy (Yes), the base station controller 82 proceeds to step S106; if the predicted GNSS positioning accuracy is less than or equal to the allowable accuracy (No), it proceeds to step S107.

[0064] If the predicted GNSS positioning accuracy is higher than the acceptable accuracy, the reference station controller 82 transmits information about the satellite used (e.g., the identification number of the positioning satellite) selected by the satellite selection unit 122 to the GNSS receiver 81 via the satellite transmission unit 125 (step S106), and terminates the process shown in Figure 8.

[0065] If the predicted GNSS positioning accuracy is below the acceptable accuracy, the reference station controller 82 resets the n-1 union regions Ss by excluding the lowest priority of the n site-aerial shielding regions Si included in the current union region Ss (for example, the site-aerial shielding region related to the hydraulic excavator 1 furthest from the construction target surface) using the shielding region setting unit 116 (step S107), and returns to step S104. As a result, steps S104, S105, and S107 are repeated until the predicted GNSS positioning accuracy exceeds the acceptable accuracy, at which point the process moves to step S106 and the process shown in Figure 8 is completed.

[0066] Figure 9 is a flowchart showing the detailed procedure for each step S102 in Figure 8. In step S102, the reference station controller 82 uses the shielding area calculation unit 115 to calculate the first shielding area 721 by imagining a state in which the rotating body 3 is directly facing the construction target surface, based on the current position, orientation, dimensional data of the hydraulic excavator 1 and the cross-sectional view 301 (step S201a).

[0067] Next, the reference station controller 82 uses the shielding area calculation unit 115 to determine whether the hydraulic excavator 1 can work on the target surface at its current position, based on the distance between the hydraulic excavator 1 and the target surface, dimensional data, and the cross-sectional view 301 (step S201b).

[0068] If step S201b determines that the hydraulic excavator 1 can work on the target surface at its current position (Yes), the reference station controller 82 uses the shielding area calculation unit 115 to virtually calculate a second shielding area 610 by considering all possible positions in which the bucket tip 12D of the front work implement 6 contacts the target surface (step S201c). The shielding area calculation unit 115 then sets the site-above-ground shielding area Si to be the superimposed area of ​​the first shielding area 721 calculated in step S102a and the second shielding area 610 calculated in step S102c (step S201d), and proceeds to step S103.

[0069] On the other hand, if step S201b determines that the hydraulic excavator 1 is unable to work on the target surface at its current position (No), the reference station controller 82 uses the shielding area calculation unit 115 to set the first shielding area 721 as is, as the shielding area Si above the site related to the hydraulic excavator 1 (step S201e), and proceeds to step S103.

[0070] (effect) (1) The reference station controller 82 installed in the reference station 8 calculates a first shielding area 721 where the final construction surface shields the airspace above the GNSS antennas 50A and 50B, and a second shielding area 610 where the front work machine 6, which is hypothetically in contact with the bucket tip 12D of the work surface, can shield. If the front work machine 6 can reach the work surface, the union of the first shielding area 721 and the second shielding area 610 is set as the current site airspace shielding area Si. If the front work machine 6 cannot reach the work surface, the first shielding area 721 is set as the site airspace shielding area Si, and at least one positioning satellite 615 outside the site airspace shielding area Si is selected as the satellite to be used.

[0071] The area that can be shielded by the front work implement 6 changes moment by moment as the front work implement 6 operates. However, in this embodiment, the second shielding area 610 calculated with respect to the front work implement 6 does not take into account the actual orientation of the front work implement 6, but rather is an area that can be shielded by the front work implement 6, assuming that the bucket tip 12D is in contact with the target surface of the final construction surface. Therefore, it is uniquely determined by the current position of the hydraulic excavator 1 and does not change unless the hydraulic excavator 1 moves. The first shielding area 721 is also uniquely determined by the current position of the hydraulic excavator 1. Therefore, the selected satellite used does not switch unless the hydraulic excavator 1 moves.

[0072] Therefore, according to this embodiment, the frequency of switching between satellites can be suppressed, thereby improving the stability of RTK-GNSS positioning accuracy. In addition, since the satellites used are not switched more often than necessary, the computational load on the base station controller 82 and the GNSS receiver 51 and controller 40 of the hydraulic excavator 1 is also reduced.

[0073] Furthermore, in practice, the period during which RTK correction data is updated at the base station 8 is longer than the period during which the visibility of the positioning satellites actually changes in accordance with the operation of the hydraulic excavator 1, making it difficult to select the appropriate satellite in a timely manner according to the real-time attitude of the hydraulic excavator 1. In contrast, in this embodiment, as described above, the occluded area above the site is uniquely determined at the current position of the hydraulic excavator, and there is no need to update the RTK correction data unless the hydraulic excavator 1 moves. This also addresses the problem caused by the difference between the RTK correction data update period and the period during which the visibility / invisibility of the positioning satellites 615 changes due to the front work implement 6.

[0074] Furthermore, once the current position and dimensional data of the hydraulic excavator 1 are identified, the overhead shielding area Si for the hydraulic excavator 1 is uniquely determined. Therefore, if the hydraulic excavator 1 communicating with the reference station 8 has machine guidance and machine control functions, there is no need to add any new software or hardware elements on the hydraulic excavator 1 side.

[0075] (2) Furthermore, if there are multiple hydraulic excavators 1 that transmit RTK correction data, a union region Ss of the occluded areas Si above the site calculated for each hydraulic excavator 1 is set, and positioning satellites outside this union region Ss are selected as the satellites to be used. This makes it possible to transmit shared RTK correction data to multiple hydraulic excavators 1. Since the satellites used for the RTK correction data are visible satellites at the location of each hydraulic excavator 1, the reliability of the RTK-GNSS positioning accuracy at the location of each hydraulic excavator 1 can be ensured.

[0076] (3) In this embodiment, a prediction process is performed to predict the GNSS positioning accuracy when using satellites selected based on the union region Ss of the overhead occlusion regions Si at the site. If the calculated GNSS positioning accuracy is below the acceptable accuracy, an exclusion process is performed to exclude the overhead occlusion region with the lowest priority. If the calculated GNSS positioning accuracy is below the acceptable accuracy, a re-selection process is performed to re-select positioning satellites that have been excluded from the union region of the overhead occlusion regions after the exclusion process. This process is repeated until the GNSS positioning accuracy exceeds the acceptable accuracy. As a result, even if the GNSS positioning accuracy when using the selected satellites is below the acceptable accuracy, the number of overhead occlusion regions to be superimposed decreases, increasing the number of positioning satellites selected as satellites, and thus ensuring acceptable accuracy.

[0077] (4) The second shielding area 610 is calculated under the condition that the hydraulic excavator 1 is directly facing the surface to be constructed. By setting certain virtual conditions for calculating the second shielding area 610 in this way, the current position of the hydraulic excavator 1 and the second shielding area 610 can be uniquely determined.

[0078] (5) Furthermore, in order to calculate the second shielding area 610 according to the current position of the hydraulic excavator 1 under predetermined conditions, it is naturally necessary to determine the surface to be worked on by the hydraulic excavator 1. In this embodiment, the surface to be worked on can be automatically set based on the orientation of the slewing body 3, or it can be manually set by the input device 89. In any case, once the surface to be worked on is determined and the predetermined conditions are set as described above, the second shielding area 610 can be uniquely determined according to the current position of the hydraulic excavator 1.

[0079] (6) As shown in the example in Figure 1, if the hydraulic excavator 1 has two GNSS antennas 50A and 50B, the overhead shielding region Si can be calculated for both GNSS antennas 50A and 50B. For example, if the shielding region calculated based on GNSS antenna 50B is larger than the shielding region calculated based on GNSS antenna 50A, and it is desirable to select the satellite to be used based on the shielding region based on GNSS antenna 50B, the shielding region based on GNSS antenna 50B can be used. In this way, it is possible to handle cases where it is desired to calculate a second shielding region 610 for GNSS antenna 50B.

[0080] (modified version) The present invention is not limited to the embodiments described above and may include various modifications. For example, the present invention is not necessarily limited to a configuration comprising all the components described in each of the embodiments above. For example, it is possible to replace some of the components with other components. It is also possible to delete some of the components of the embodiments or add other components.

[0081] For example, although we used hydraulic excavator 1 as an example of a work machine that communicates with base station 8, the work machine that communicates with base station 8 could be any other work machine, such as a wheel loader or a bulldozer. [Explanation of Symbols]

[0082] 1...Hydraulic excavator (working machine), 6...Front work machine, 8...GNSS field reference station for working machine, 12D...Bucket tip (tip of front work machine), 50A, 50B...GNSS antenna, 82...Reference station controller (controller), 89...Input device, 301...Cross-sectional view (design data for the final construction surface), 301A...Final construction surface (surface to be constructed), 302...Plan view (design data for the final construction surface), 610...Second shielding area, 615...Positioning satellite, 615a, 615b...Positioning satellite (satellite used), 721...First shielding area, AZ...Azimuth vector (azimuth of the working machine), O...Swivel centerline (current position), Si...Shielding area above the site

Claims

1. A GNSS field reference station for a work machine, which includes a controller for selecting the satellite to be used in calculating RTK correction data, generates the RTK correction data based on the satellite signal received from the said satellite, and transmits it to the work machine using GNSS, The aforementioned controller, Based on the pre-stored design data of the final construction surface, the pre-stored dimensional data of the work machine, and the current position of the work machine received from the work machine, The first shielding region is calculated, in which the final construction surface shields the airspace above the GNSS antenna of the aforementioned work machine. Determine whether the front workpiece of the aforementioned work machine can reach the surface to be worked on. When the front work machine reaches the surface to be worked on, a second shielding region is calculated above the GNSS antenna of the work machine, assuming that the front work machine's tip is in contact with the surface to be worked on, and the union of the first shielding region and the second shielding region is set as the current shielding region above the work site. If the front work machine cannot reach the surface to be worked on, the first shielding area is set to the current shielding area above the site. Select at least one positioning satellite that is outside the aforementioned occupying area above the site as the satellite to be used. A GNSS field reference station for industrial machinery, characterized by the following features.

2. In the GNSS field reference station for work machinery described in claim 1, The aforementioned controller, If there are multiple such work machines, the overhead shielding area above the work site is calculated for each work machine. Select at least one positioning satellite as the satellite to use, which is outside the union region of multiple aforementioned shielding areas above the site. A GNSS field reference station for industrial machinery, characterized by the following features.

3. In the GNSS field reference station for work machinery described in claim 2, The aforementioned controller, A prediction process for predicting the GNSS positioning accuracy when using the aforementioned satellites, If the GNSS positioning accuracy is below the acceptable accuracy, an exclusion process is performed to exclude the lowest priority area of ​​obstruction above the site. A re-selection process is performed to re-select at least one positioning satellite that is outside the union region of the occupying areas above the site after the exclusion process has been carried out, as the satellite to be used. A GNSS field reference station for work machinery, characterized by performing the following functions.

4. In the GNSS field reference station for work machinery described in claim 3, The aforementioned controller, A GNSS field reference station for work machinery, characterized in that the exclusion process, the re-selection process, and the prediction process are repeated until the GNSS positioning accuracy exceeds the allowable accuracy.

5. In the GNSS field reference station for work machinery described in claim 3, A GNSS field reference station for construction machinery, characterized in that the lowest priority area of ​​the site above which the equipment is shielded is the area of ​​the site above which the equipment is shielded, which is furthest from the surface to be constructed.

6. In the GNSS field reference station for work machinery described in claim 3, A GNSS field reference station for construction machinery, characterized in that the lowest priority overhead shading area is the overhead shading area related to the construction machinery with the highest relative height to the surface to be constructed.

7. In the GNSS field reference station for work machinery described in claim 3, The controller is characterized in that it calculates DOP as the GNSS positioning accuracy in the prediction process, and is a GNSS field reference station for work machinery.

8. In the GNSS field reference station for work machinery described in claim 1, The controller is characterized in that it calculates the second shielding area under the condition that the work machine is directly facing the surface to be constructed. GNSS field reference station for work machine.

9. In the GNSS field reference station for work machinery described in claim 1, The controller is characterized by setting the construction target surface based on the orientation of the work machine, and is a GNSS field reference station for work machines.

10. In the GNSS field reference station for work machinery described in claim 1, The controller is characterized by setting the target surface for construction based on the settings input by the input device, and is a GNSS field reference station for work machinery.

11. In the GNSS field reference station for work machinery described in claim 1, The aforementioned controller, A GNSS field reference station for a work machine, characterized in that, when the work machine has two GNSS antennas, the GNSS field reference station for a work machine calculates the overhead shielding area for both GNSS antennas.

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