Laser measurement system having multiple synchronization bases - Patents.com

Abstract

To provide a laser measuring system comprising first and second laser base stations, and a laser receiver.SOLUTION: A laser receiver detects a first laser signal from a first laser base station. Location information associated with the first laser base station is extracted from the detected first laser signal. The laser receiver detects a second laser signal from the second laser base station. Location information associated with the second laser base station is extracted from the detected second laser signal. The position of the laser receiver is determined based on the extracted location information associated with the first laser base station and the extracted location information associated with the second laser base station.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application claims priority to U.S. Application No. 16 / 710,090, filed September 11, 2019, the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0002] The present invention relates generally to laser measurement systems, and more particularly to laser measurement systems having multiple synchronization bases for providing complete position information relative to a laser receiver.

[0003] Preparation of a work site, such as a construction work site or an agricultural work site, typically involves grading and excavating portions of the work site into a desired topology. Position measurement is an important aspect of work site preparation to improve the accuracy of such grading and excavation. Laser measurement systems are often used on construction machinery (e.g., bulldozers, scrapers, excavators, etc.) to facilitate position measurement.

[0004] One conventional approach utilizes a laser measurement system to facilitate position measurement. In such a conventional laser measurement system, a laser diode in the laser transmitter projects a laser signal and a photodiode in the laser receiver receives the laser signal. The laser transmitter is provided with a reflective surface centered on the laser diode, and the laser receiver is provided with a reflective surface centered on the photodiode. Based on the reflection of the laser signal at the reflective surface, the distance between the laser transmitter and the laser receiver can be calculated. However, when the laser receiver in such a conventional laser measurement system has a reflective surface centered on the photodiode, the required size of the laser receiver is larger than when it does not have a reflective surface centered on the photodiode. Summary of the Invention [Problem to be solved by the invention]

[0005] In one or more embodiments, a system and method are provided for operating a laser receiver. The laser receiver detects a first laser signal from a first laser base station. From the detected first laser signal, location information associated with the first laser base station is extracted. The laser receiver detects a second laser signal from a second laser base station. From the detected second laser signal, location information associated with the second laser base station is extracted. A location of the laser receiver is determined based on the extracted location information associated with the first laser base station and the extracted location information associated with the second laser base station.

[0006] In one embodiment, the location information associated with the first laser base station comprises a horizontal angle associated with the first laser base station, a vertical angle associated with the first laser base station, a reference azimuth angle associated with the first laser base station, and coordinates associated with the first laser base station, and the location information associated with the second laser base station comprises a horizontal angle associated with the second laser base station, a vertical angle associated with the second laser base station, a reference azimuth angle associated with the second laser base station, and coordinates associated with the second laser base station. The horizontal angles associated with the first laser base station and the second laser base station may be determined based on modulation of the detected first laser signal and the detected second laser signal, respectively. The first and second laser signals may comprise a plurality of beams in an N-shape, and the vertical angles associated with the first laser base station and the second laser base station may be determined based on a time of receiving each of the plurality of beams of the detected first laser signal and the detected second laser signal, respectively. Coordinates associated with the first laser base station and the second laser base station and reference azimuth angles associated with the first laser base station and the second laser base station may be determined by demodulating the data stream within the detected first laser signal and the detected second laser signal, respectively.

[0007] In one embodiment, the first laser base station and the second laser base station are calibrated to determine the respective positions of the first laser base station and the second laser base station in a reference coordinate system.

[0008] According to one embodiment, a system and method for operating a laser base station is provided. A first laser signal is detected from another laser base station. Position information relating to the other laser base station is extracted from the detected first laser signal. The position information includes coordinates and a reference azimuth angle relating to the other laser base station, and horizontal and vertical angles relating to the other laser base station. A position of the laser base station is determined based on the extracted position information relating to the other laser base station. A second laser signal including the position of the laser base station is projected onto the laser receiver to determine the position of the laser receiver.

[0009] In one embodiment, the rotation of the laser base station is synchronized with the rotation of the other laser base stations based on the amplitude and timing of the detected first laser signal. The rotation of the laser base station may be further synchronized with the rotation of the other laser base stations based on a horizontal angle relative to the other laser base stations.

[0010] These and other advantages of the present invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a high-level schematic diagram showing a laser measurement system. [Diagram 2] FIG. 2 shows further details of the laser measurement system. [Diagram 3] FIG. 3 is a detailed diagram of the rotating head of the laser base station in the laser measurement system. [Figure 4] FIG. 4 is a diagram showing details of a laser receiver of the laser measurement system. [Figure 5A] FIG. 5A is a top view showing a laser measurement system. [Figure 5B] FIG. 5B is a perspective view showing a laser measurement system. [Figure 6] FIG. 6 is a diagram illustrating the method of operation of the laser measurement system. [Figure 7] FIG. 7 is a diagram illustrating a method for calibrating multiple laser base stations in a laser measurement system. [Figure 8] FIG. 8 is a diagram showing a method for determining the position of a laser receiver in a laser measurement system. [Figure 9] FIG. 9 is a timing diagram of the signal received by the laser receiver. [Figure 10] FIG. 10 is a high-level block diagram illustrating an exemplary laser receiver. [Figure 11] FIG. 11 is a high-level block diagram illustrating an exemplary laser transmitter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] FIG. 1 is a high-level schematic diagram illustrating a laser measurement system 100 in accordance with one or more embodiments. The laser measurement system 100 may be deployed in a construction job site, an agricultural job site, a warehouse, or other environment. The laser measurement system 100 includes a plurality of laser base stations 102-A, 102-B, 102-C (collectively referred to herein as laser base stations 102) and a laser receiver 104. Although shown in FIG. 1 as laser base stations 102-A, 102-B, 102-C and laser receiver 104, it should be understood that the laser base station 102 may include two or more laser base stations, and the laser receiver 104 may include any number of laser receivers (so long as the laser receivers do not cast shadows or interfere with each other).

[0013] First, the laser base stations 102 are calibrated to a reference coordinate system. During calibration, each laser base station 102 receives position information of pre-calibrated laser base stations 102 and determines its relative position in the reference coordinate system therefrom. In some embodiments, for example, each laser base station 102 may receive position information of two self-leveled laser base stations 102 or three pre-calibrated laser base stations 102 that are not self-leveled. To facilitate communication between the laser base stations 102 for such calibration purposes, each laser base station 102 is configured to include both a laser transmitter that continuously projects a laser signal with a rotating illumination and a light detector that detects the laser signal as a pulse due to the rotation of the laser transmitter. In operation, the calibrated laser base station 102 projects a laser signal with a rotating illumination to the laser receiver 104. The laser receiver 104 calculates (eg, triangulates) its position in a reference coordinate system (three-dimensional Cartesian coordinates) from the laser signal received from the calibrated laser base station 102 .

[0014] Preferably, the laser receiver 104 determines its position without transmitting light to the laser base station 102. Also, since the laser receiver 104 does not require a reflective surface to determine its position, the size of the laser receiver 104 is not larger than necessary. The details of the laser measurement system 100 are described below.

[0015] Figure 2 illustrates details of a laser measurement system 200 in accordance with one or more embodiments. In one embodiment, the laser base station 202 and the laser receiver 204 in Figure 2 are the laser base station 102 and the laser receiver 104, respectively, in Figure 1. It should be understood that while for convenience, one laser base station 202 is shown in Figure 2, the laser measurement system 200 may include multiple laser base stations, each of which operates in a manner similar to that described herein for the laser base station 202.

[0016] As illustrated in FIG. 2, the laser receiver 204 is configured to be mounted on a survey pole 206. However, it should be understood that various configurations for the laser receiver 204 are contemplated. For example, the laser receiver 204 may be configured to be mounted on a rover or other vehicle, such as a construction machine (e.g., an excavator, a dump truck, a bulldozer, etc.). As another example, the laser receiver 204 is a portable device or a buried portion of a portable device. Similarly, the laser base station 202 is shown in FIG. 2 mounted on a tripod 214, but may be mounted in any suitable manner.

[0017] The laser base station 202 projects (transmits) a laser signal in a rotating beam at a constant speed. In one embodiment, the laser base station 202 projects an N-shaped beam 208 as described in U.S. Patent No. 7,196,302, issued March 27, 2007, the entire disclosure of which is incorporated herein by reference. The N-shaped beam 208 is composed of a number of fan-shaped beams projected such that the cross section of the light flux of the beam 208 forms an N-shape. As illustrated in FIG. 2, the N-shaped beam 208 is composed of a vertical beam 210-A, a vertical beam 210-B, and an inclined beam 210-C inclined at an angle 212 with respect to the vertical beams 210-A and 210-B to form an N-shape.

[0018] The laser base station 202 projects a modulated (e.g., phase or frequency) N-shaped beam 208. For example, the laser base station 202 may modulate the N-shaped beam 208 with multiple subcarriers to transmit a data stream of a horizontal angle associated with the laser base station 202 and additional data. The data stream may include an identifier of the laser base station 202, the coordinates of the laser base station 202, a reference azimuth angle associated with the laser base station 202, laser head calibration data of the laser base station 202, horizontal and vertical angles associated with other laser base stations, their respective identifiers, and any other relevant information.

[0019] 2, the beam 208 projected by the laser base station 202 is illustrated as an N-shaped beam, it should be understood that the laser signal projected by the laser base station 202 may be in any suitable form. In one embodiment, the laser base station 202 projects an I-shaped beam (not shown in FIG. 2) that includes a single vertical beam. In this embodiment, the laser base station 202 provides two-dimensional coordinates.

[0020] FIG. 3 illustrates details of a rotating head 300 of a laser base station in accordance with one or more embodiments. In one embodiment, the rotating head 300 is the rotating head of the laser base station 102 of FIG. 1. The rotating head 300 includes a laser transmitter 302 for projecting a laser signal and a light detector 304 for detecting the laser signal. The rotating head 300 can project and detect laser signals 360 degrees around the rotating head 300 by projecting and detecting the laser signal, respectively, while rotating in a clockwise direction 318 (counterclockwise in some embodiments). It should be understood that FIG. 3 is a top-down view of the rotating head 300 and that the rotating head 300 may include additional components to facilitate projecting and detecting the laser signal.

[0021] Laser transmitter 302 includes laser diode 310, reflectors 308-A, 308-B, and 308-C (collectively referred to herein as reflector 308), and transmitter lenses 306-A, 306-B, and 306-C (collectively referred to herein as transmitter lenses 306). Laser diode 310 generates laser signal 320, which is reflected by reflectors 308-A, 308-B, and 308-C (reflectors 308-B and 308-C are semi-transparent reflectors and / or beam splitters) as laser signals 322-A, 322-B, and 322-C, respectively (collectively referred to herein as laser signals 322), which are projected through transmitter lenses 306-A, 306-B, and 306-C, respectively, to a light detector, for example, of another laser base station or laser receiver. In one embodiment, laser signals 322-A, 322-B, and 322-C form an N-shaped beam.

[0022] The laser transmitter 302 may be of any suitable configuration so long as the laser signal 322 is modulated with a common modulation signal. For example, in one embodiment, as shown in FIG. 3, the laser diode 310 is embedded in the rotating head 300 and rotates with the rotating head 300 when the rotating head 300 is rotated by a motor. In another embodiment, the laser diode 310 is disposed in a fixed portion of the laser base station (outside the rotating head 300) such that the laser beam axis of the laser diode 310 is coaxial with the rotation axis of the rotating head 300. In another embodiment, the laser diode 310 includes multiple laser diodes (e.g., three laser diodes) embedded in the rotating head 300, each of which is disposed behind a respective transmitter lens 306 (each laser diode has a common modulation signal) to project the laser signal 322 directly without the need for a reflector 308.

[0023] The light detection portion 304 includes a photodiode 316, a reflector 314, and a receiver lens 312. A laser signal 324 (e.g., from another laser base station) is detected through the receiver lens 312 and reflected by the reflector 314 towards the photodiode 316 for analysis. The photodiode 316 may be a PIN diode, an avalanche photodiode (APD), or any other type of diode suitable for the wavelength of the laser signal 324.

[0024] The light detector 304 may be of any suitable configuration. In one embodiment, as shown in FIG. 3, the photodiode 316 is embedded within the rotating head 300 and rotates with the rotating head 300 as the rotating head 300 is rotated by a motor. In another embodiment, the photodiode 316 is located on a fixed portion of the laser base station (outside the rotating head 300) such that the laser signal 324 is optically collimated and reflected toward the photodiode 316. In another embodiment, the photodiode 316 is embedded within the rotating head 300 and positioned behind the receiver lens 312 to directly receive the laser signal 324 projected through the receiver lens 312.

[0025] Figure 4 illustrates details of a laser receiver 400 in accordance with one or more embodiments. In one embodiment, the laser receiver 400 is the laser receiver 104 in Figure 1. It should be understood that Figure 4 is a top-level diagram of the laser receiver 400 and that the laser receiver 400 may include additional components to facilitate detection of a laser signal.

[0026] The laser receiver 400 includes a photodetector 402. The operation of the photodetector 402 of the laser receiver 400 is similar to the photodetector 304 of the laser base station 300 in Figure 3. In particular, a laser signal 408 (e.g., from the laser base station) is detected through the receiver lens 404 and focused onto a photodiode 406 (e.g., a PIN diode, a PN diode, etc.) for analysis.

[0027] In one embodiment, the light detector 402 is configured to detect the laser signal 408 from 360 degrees. For example, in one embodiment, the laser receiver 400 includes one or more optical elements to receive the laser signal 360 degrees around the laser receiver 400. Examples of the one or more optical elements include a conical mirror, a fisheye lens, a diffuser sphere, or any other method of collecting the laser signal around the laser receiver 400. In another embodiment, the laser receiver 400 includes multiple photodiodes (each with a limited field of view) to cover 360 degrees around the laser receiver 400. It should be understood that 360 degrees coverage by the photodiodes is not necessary as long as the laser receiver 400 receives laser signals from a sufficient number of laser base stations (e.g., two or three).

[0028] FIG. 5A is a top view and FIG. 5B is a perspective view illustrating further details of the laser measurement system 500 in one or more embodiments. In FIG. 5A and FIG. 5B, the laser base station 502 continuously projects a laser signal 506 (e.g., an N-shaped beam or an I-shaped beam) to the laser receiver 504 in a clockwise rotating rotating beam. In one embodiment, the laser base station 502 may be the laser base station 102 in FIG. 1 or the laser base station 202 in FIG. 2, and the laser receiver 404 may be the laser receiver 104 in FIG. 1 or the laser receiver 204 in FIG. 2. It should be understood that FIG. 5A and FIG. 5B are high-level diagrams illustrating the laser measurement system 500, and the laser measurement system 500 may include additional components.

[0029] The position of the laser receiver 504 may be defined in up to three dimensions by its Cartesian coordinates (X, Y, Z) relative to a reference coordinate system. FIG. 5A shows the X-axis 508-A and the Y-axis 508-B of the reference coordinate system (the Z-axis in the reference coordinate system is not shown in FIG. 5A but is perpendicular to both the X-axis 508-A and the Y-axis 508-B). The coordinates (X, Y, Z) may be determined based on the distance D514, the horizontal angle θ512, and / or the vertical angle φ518. The distance D514 is the distance between the laser base station 502 and the laser receiver 504. The horizontal angle θ512 is the angle that the laser receiver 504 takes with respect to the reference direction 516 (e.g., the direction in which the horizontal angle θ512 read by the encoder of the laser base station 502 is 0) and is measured by the laser receiver 504 from the laser signal 506. The vertical angle φ 518 is the angle that the laser receiver 504 makes with respect to the transmitter reference horizontal plane 520 and is calculated by the laser receiver 504 based on the arrival times of each beam in the N-shaped laser signal 506 .

[0030] The position of the laser base station 502 may be specified in up to six dimensions: three Cartesian coordinates (X, Y, Z) relative to a reference coordinate system and three orientation angles. The three orientation angles are a reference azimuth angle θ ref 510 and two tilt angles Vx and Vy of the rotation axis 522 of the rotating head in the laser base station 502. ref 510 is the angle formed by a reference plane (e.g., the plane of the reference coordinate system formed by the Y-axis 508-B and the Z-axis) and a reference direction 516. Vx and Vy are the tilt angles of the rotation axis 522. Note that the reference azimuth angle θ ref 510 may vary depending on the installation situation of the laser base station 502, but the reference azimuth angle θ ref It should be understood that the sum of 510 and the horizontal angle θ 512 will indicate the same direction for all base stations (if the bases are synchronized).

[0031] In one embodiment, the laser measurement system 500 comprises at least one laser receiver 504 and at least two self-leveled laser base stations 502 projecting an I-shaped laser signal 506. The laser receiver 504 in this embodiment can only measure its horizontal angle θ 512 from the laser signal 506, and therefore can only determine its two-dimensional position (excluding height information). Because there are at least two laser base stations 502 projecting leveled, I-shaped laser signals 506, the position of the laser base station 502 can be determined in three dimensions (two-dimensional Cartesian coordinates (X,Y) and a reference azimuth angle θ ref 510), which are digitally transmitted at low speed via laser signal 506 to the laser receiver 504. The two-dimensional Cartesian coordinates (X, Y) and reference azimuth angle θ ref Knowing 510, the laser receiver 504 calculates its position in two dimensions. The preferred coordinates of the laser base stations 502 are (0,0) and (1,0). In particular, the first laser base station 502 is a reference point with coordinates (0,0), and the second laser base station 502 defines an X-axis 508-A and a distance D 514 according to coordinates (1,0).

[0032] In one embodiment, the laser measurement system 500 comprises at least one receiver and at least two self-leveled laser base stations 502 projecting an N-shaped laser signal 506. The laser receiver 504 in this embodiment can measure its horizontal angle θ 512 and vertical angle φ 518, so that its full three-dimensional position can be determined. Because there are at least two laser base stations 502 projecting leveled, N-shaped laser signals 506, the position of the laser base station 502 can be determined in four dimensions (three-dimensional Cartesian coordinates (X, Y, Z) and a reference azimuth angle θ ref 510), which are digitally transmitted at low speed via laser signal 506 to the laser receiver 504. The three-dimensional Cartesian coordinates (X, Y, Z) and reference azimuth angle θ ref510, the laser receiver 504 calculates its position in three dimensions. The preferred coordinates of the first base station are (0,0,0) and (1,0,Z). The laser base station 502 is self-leveling so that the reference coordinate system is flush with the horizontal Z plane. The first laser base station 502 becomes a reference point with coordinates (0,0,0) and the second laser base station 502 has coordinates (1,0,Z), which has an offset in the z direction due to an arbitrary initial position relative to the reference z plane.

[0033] In one embodiment, the laser measurement system 500 includes at least one laser receiver 504 and at least three unleveled laser base stations 502 projecting an I-shaped laser signal 506. The laser receiver 504 in this embodiment can measure its horizontal angle θ 512 and vertical angle φ 518 so that its full three-dimensional position can be determined. Because there are at least three laser base stations 502 projecting an unleveled, N-shaped laser signal 506, the position of the laser base station 502 can be determined in four dimensions (three-dimensional Cartesian coordinates (X, Y, Z) and a reference azimuth angle θ ref 510), which are digitally transmitted at low speed via laser signal 506 to the laser receiver 504. The three-dimensional Cartesian coordinates (X, Y, Z) of at least two laser base stations 502, a reference azimuth angle θ refKnowing 510, the tilt angles Vx and Vy, the laser receiver 504 calculates its position in three dimensions. The preferred coordinates of the first base station 502 are (0,0,0), (1,0,0), (x,y,0). The first laser base station 502 is the reference point with coordinates (0,0,0), the second laser base station 502 defines the X-axis 508-A and the distance D 514 according to coordinates (1,0,0), and the third laser base station 502 is used to define the rotation along the X-axis 508-A by fixing the Z coordinate to zero using coordinates (x,y,0). The three center points of at least three laser base stations 502 define a Z-plane, which does not have to be horizontal in this case. When the Z-plane is defined, the tilt angles Vx and Vy of each base station are determined by each base station based on the horizontal and vertical angles of the other base stations.

[0034] In one embodiment, for example, when the laser base station 502 is leveled, the position of the laser base station 502 is expressed in four dimensions, namely, three Cartesian coordinates (X, Y, Z) and a reference azimuth angle θ ref 510. In other embodiments, for example when the laser base station 502 is not leveled, the position of the laser base station 502 is defined in six dimensions, namely three Cartesian coordinates (X, Y, Z), a reference azimuth angle θ ref 510, and tilt angles Vx and Vy. In another embodiment, for example when the laser base station 502 is leveled, the position of the laser base station 502 is defined in three dimensions, i.e., two Cartesian coordinates (X, Y) and a reference azimuth angle θ ref 510. The position of the laser receiver 504 is then defined in two dimensions, i.e., in two Cartesian coordinates (X, Y).

[0035] FIG. 6 illustrates a method 600 of operation of a laser measurement system including multiple laser base stations and laser receivers in accordance with one or more embodiments.

[0036] In step 602, the laser base stations (e.g., laser base station 102 in FIG. 1) are calibrated to a reference coordinate system. The laser base stations are calibrated such that their Cartesian coordinates, tilt angles of the rotation axes, and reference azimuth angles are known. In one embodiment, the laser base stations may each be calibrated by repeatedly performing the steps of method 700 of FIG. 7. In another embodiment, the laser base stations may be calibrated by manually defining their relative positions (e.g., coordinates and reference azimuth angles) in the reference coordinate system.

[0037] In step 604, a position of a laser receiver (e.g., laser receiver 104 in FIG. 1) in the reference coordinate system is determined based on position information associated with a plurality of calibrated laser base stations extracted from laser signals received from the plurality of calibrated laser base stations. In one embodiment, the position information includes coordinates, a reference azimuth angle, a horizontal angle, and a vertical angle associated with each of the plurality of calibrated laser base stations. The laser receiver calculates (e.g., triangulates) its relative position in the reference coordinate system based on the position information of each of the plurality of calibrated laser base stations. In one embodiment, the position of the laser receiver in the reference coordinate system is determined as described below with reference to method 800 of FIG. 8.

[0038] Figure 7 illustrates a method 700 for calibrating multiple laser base stations of a laser measurement system in accordance with one or more embodiments. In one embodiment, method 700 is performed at step 602 of Figure 6. The steps of method 700 are repeated iteratively by each of the multiple laser base stations such that the multiple laser base stations are calibrated to a reference coordinate system.

[0039] Method 700 begins at step 702, where it is determined whether a laser signal from one or more calibrated laser base stations is detected by each laser base station. Step 702 may correspond to a listening mode that each base station goes through upon powering up. The laser signal detected by each laser base station may be projected by the calibrated laser base station at step 706 during a previous cycle of method 700 to calibrate that laser base station. During the listening mode (step 702), each laser base station rotates at a reduced rotation speed (compared to its operational mode at step 706). In one embodiment, the rotation speed in the listening mode is: RR = RR / HFOV, where RR is the normal rotation speed during the operational mode and HFOV is the horizontal acceptance angle of the photodetector. In another embodiment, the rotation speed in listening mode is TIFF0007632818000002.tif2065. The laser signal may be detected using a light detector (e.g., light detector 304 in FIG. 3) of each laser base station. A laser signal detected in step 702 indicates that there is at least one laser base station of the plurality of laser base stations that has already been calibrated (during a previous cycle of method 700), and a laser signal not detected in step 702 indicates that the respective laser base station is a first laser base station of the plurality of laser base stations to be calibrated.

[0040] If, in step 702, no laser signal is detected from one or more calibrated laser base stations within a predetermined period of time, the method 700 proceeds to step 704, where the position of each laser base station in the reference coordinate system is defined as a reference position. In one embodiment, the position of each laser base station is defined as coordinates (0,0,0), but a reference azimuth angle is not defined until a second laser base station is available to define a reference azimuth angle. Other reference positions are also contemplated. Once the position of each laser base station is defined in step 704, each laser base station proceeds to step 705, where it projects a laser signal that transmits coordinates (0,0,0) excluding its reference azimuth angle. During step 705, each laser base station waits until it detects the laser signal of the other laser base station. Each laser base station demodulates its respective horizontal angle from the data stream of the detected laser signal and uses it to calculate its reference azimuth signal and complete the calibration. After the calibration, the method 700 proceeds to step 706.

[0041] In step 706, each calibrated laser base station projects a laser signal. Step 706 may correspond to an operation mode of each laser base station projecting a laser signal. During the operation mode, each calibrated laser base station operates at a high rotation speed (compared to the listening mode in step 702), e.g., 10 Hz, 20 Hz, etc., and projects a laser signal in a continuous rotating illumination, e.g., to one or more laser base stations or laser receivers. For example, each calibrated laser base station can project a laser signal, which is detected by one or more calibrated laser base stations in step 702 during a later cycle of the method 700 for calibrating the laser base station. As another example, each calibrated laser base station may project a laser signal, which is detected by a laser receiver (of a laser measurement system) to determine its position in a reference coordinate system in step 604 of FIG. 6. The laser signal may be projected using a laser transmission unit (e.g., laser transmission unit 302 in FIG. 3) of each laser base station.

[0042] In one embodiment, the laser signal projected by each calibrated laser base station is an N-shaped beam. For example, the laser signal may be the N-shaped beam 208 shown in FIG. 2, which includes a vertical beam 210-A, a vertical beam 210-B, and a beam 210-C tilted at an angle θ 212.

[0043] In one embodiment, the laser signal projected by each calibrated laser base station is modulated to transmit the horizontal angle of each calibrated laser base station along with a data stream of additional data. The laser signal may be modulated using any suitable modulation technique, such as frequency modulation or phase modulation. For example, in one embodiment, the laser signal is modulated with frequency domain code division multiple access (CDMA) modulation. In one embodiment, the laser signal is modulated as described in U.S. Patent No. 10,145,671, issued December 4, 2018, the entire disclosure of which is incorporated herein by reference.

[0044] The laser signal can be modulated with multiple subcarriers. In one embodiment, the laser signal is modulated with multiple subcarriers as described in U.S. Patent Application No. 16 / 665,118, filed October 28, 2019, the entire disclosure of which is incorporated herein by reference. The multiple subcarriers are sidebands of a carrier used to modulate the laser signal. The multiple subcarriers may include any suitable number of subcarriers. One virtual channel may be modulated (e.g., sampled at a multiple 1x) with a rough but not vague horizontal angle at each calibrated laser base station. For example, the laser signal may be modulated with a phase or frequency proportional to the horizontal angle at each calibrated laser base station. Also, in one embodiment, one or more additional virtual channels may be modulated (e.g., sampled at a multiple higher than 1x, such as 4x, 20x, etc.) with a rough but vague horizontal angle at each calibrated laser base station. This "vagueness" can be eliminated by using the above-mentioned "rough but not vague horizontal angle" as a reference.

[0045] The laser signals may also be modulated using a virtual channel modulated with a data stream of further data, which may include an identifier for each calibrated laser base station, coordinates for each calibrated laser base station, a reference azimuth angle for each calibrated laser base station, laser head calibration data for each calibrated laser base station, horizontal and vertical angles of laser signals received from other laser base stations, identifiers for the laser base stations, and any other relevant information.

[0046] In one embodiment, the baud rate of the modulation is set to half the rotation rate of each calibrated laser base station to demodulate the data stream from any angle around each calibrated laser base station. This ensures that the modulated laser signal is sampled twice per symbol. Any known phase modulation technique may be used. Also, in one embodiment, the laser signal is modulated with phase shift keying (PSK), such as binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 8-PSK, 16-PSK, etc., depending on the minimum signal-to-noise ratio (SNR) desired at a certain distance from each calibrated laser base station. In one example, using QPSK modulation provides a data rate at the rotation rate of each calibrated laser base station. For example, a 10 Hz rotation of each calibrated laser base station provides a data rate of 10 bits per second (bps). Using advanced modulation provides a higher data rate.

[0047] In one embodiment, the baud rate of the modulation is set to match the rotational speed of the laser base station, resulting in one sample per symbol. Using trellis coding and differential phase shift keying modulation, the data stream can be reliably demodulated by all receivers within 360 degrees of the laser base station.

[0048] If, in step 702, a laser signal is detected from one or more calibrated laser base stations within a predetermined time period, method 700 proceeds to step 708, where the rotation of each laser base station is roughly synchronized with the rotation of the one or more calibrated laser base stations based on the detected laser signal. In one embodiment, the laser signal detected by the optical detector of each laser base station is used for feedback to roughly synchronize the rotation. For example, each laser base station may adjust its rotation to maximize the amplitude of the signal detected by its respective optical detector. While the laser base station is roughly synchronized with the calibrated base station, it may demodulate the data stream transmitted by the calibrated base station.

[0049] In step 710, location information of one or more calibrated laser base stations is extracted from the detected laser signals. The location information may include coordinates of the one or more calibrated laser base stations in a reference coordinate system and reference azimuth angles of the calibrated laser base stations. The location information may be extracted from the data stream of the detected laser signals by demodulating the detected laser signals.

[0050] In step 712, the position of each laser base station in the reference coordinate system is determined based on the position information of the one or more calibrated laser base stations and the vertical and horizontal angles of the one or more calibrated laser base stations. In one embodiment, the position of each laser base station is triangulated from the position information of two or more calibrated laser base stations (e.g., the coordinates of the one or more calibrated laser base stations and the horizontal angles of each laser base station on the one or more calibrated laser base stations). If there is only one calibrated base station at this point, each base station becomes a second base station with coordinates (1,0,0) or (1,0,Z) that define the distance units and the reference azimuth angle. The triangulation does not provide the distance between the laser base stations. Instead, the relative distance is used. In one embodiment, the relative distance between the first two calibrated laser base stations is defined as 1.0, and the relative distance between all other laser base stations is defined relative to this. The triangulation is performed by each laser base station in a similar manner to that described below for the laser receiver.

[0051] In step 714, the rotation of each laser base station is precisely synchronized with the rotation of one or more calibrated laser base stations based on the extracted position information of the one or more calibrated laser base stations. Each base station starts projecting a laser signal that transmits only information about its position, except for the reference azimuth angle. All other calibrated base stations receive the horizontal and vertical angles from each base station and transmit those angles back in digital form via one or more virtual channels. When each base station demodulates its vertical and horizontal angle information (from the calibrated base station), it calculates its reference azimuth angle and precisely synchronizes its rotation. Synchronizing the rotation of each laser base station with the rotation of one or more calibrated laser base stations enables time-domain signal separation for detection of the laser signal (e.g., by multiple laser base stations or laser receivers). At any instant in time, the laser base station may calculate θ as the horizontal angle, ... ref When the reference azimuth angle is set as the instantaneous reference azimuth angle (θ-θ ref ) are the same, they will be synchronized correctly.

[0052] Once the position of each laser base station in the reference coordinate system has been determined (step 712) and the rotation of each laser base station has been precisely synchronized (step 714), each laser base station is calibrated. The method 700 then proceeds to step 706, where each calibrated laser base station projects a laser signal that communicates its position and a reference azimuth angle in an operational mode.

[0053] In one embodiment, one or more (e.g., all) of the multiple laser base stations may be relocated to a new location (e.g., in the field, at a work site, etc.) without compromising the integrity of the laser measurement system. Once the multiple laser base stations are calibrated, any of the multiple laser base stations may be relocated to a new location one at a time. Relocation is possible if there are at least two base stations stationary at a time. Once relocated, the relocated laser base station may perform the steps of method 700 to determine its new location within the original reference coordinate system.

[0054] FIG. 8 illustrates a method 800 for determining a position of a laser receiver in a laser measurement system based on laser signals received from multiple laser base stations in the laser measurement system in one or more embodiments. In one embodiment, the method 800 is performed in step 604 of FIG. 6. Each step of the method 800 may be performed by a laser receiver (e.g., laser receiver 104 in FIG. 1). In one embodiment, the multiple laser base stations include a first laser base station and a second laser base station that have been pre-calibrated, for example, according to method 700 of FIG. 7. It should be understood that the multiple laser base stations may include more than two laser base stations and that the method 800 is not limited to the first and second laser base stations.

[0055] In step 802, a first laser signal is detected from a first laser base station. The first laser signal may be modulated (e.g., phase or frequency) with a horizontal angle and a data stream associated with the first laser base station. The data stream may include an identifier of the first laser base station, coordinates of the first laser base station, a reference azimuth angle of the first laser base station, laser head calibration data of the first laser base station, horizontal and vertical angles of laser signals received from other laser base stations, an identifier of the laser base station, and any other relevant information. In one embodiment, the first laser signal includes a plurality of N-shaped beams (e.g., N-shaped beams 208 in FIG. 2).

[0056] In step 804, position information associated with the first laser base station in a reference coordinate system is extracted from the detected first laser signal. The position information associated with the first laser base station may include a horizontal angle associated with the first laser base station, a vertical angle associated with the first laser base station, a reference azimuth angle associated with the first laser base station, and coordinates associated with the first laser base station. In one embodiment, the position information associated with the first laser base station can be determined as described in U.S. Patent Application No. 16 / 665,118, filed October 28, 2019, the entire disclosure of which is incorporated herein by reference.

[0057] In one embodiment, the vertical angle φ associated with the first laser base station is determined based on the reception times of each of the multiple beams of the N-shaped first laser signal. For example, the vertical angle φ may be calculated according to Equation 1 below. TIFF0007632818000003.tif23113 (Formula 1) where k is a coefficient that indicates the physical alignment of the multiple N-shaped beams (e.g., the angle of the intermediate tilt beam (e.g., angle 212 of beam 210-C in FIG. 2)) and t 12Let t be the detection time difference between the first beam of the multiple N-shaped beams and the intermediate tilted beams (e.g., beams 210-A and 210-C), and t 23 Let be the detection time difference between the middle tilted beam and a third beam (eg, beams 210-C and 210-B) of the plurality of N-shaped beams.

[0058] In one embodiment, the horizontal angle θ associated with the first laser base station is determined based on the modulation of the first laser signal in an N-shape. For example, the first laser base station may modulate the laser signal with four subcarriers. The modulated signal (TxSignal) is expressed by the following Equation 2: where A is the instantaneous head rotation angle of the transmitter (from its encoder) of the first laser base station, C is the carrier phase, S is the subcarrier phase, and P1, P2, P3, and P4 are the phases of the modulated subcarrier signal. TIFF0007632818000004.tif11128 (Formula 2) Where: TIFF0007632818000005.tif1776, TIFF0007632818000006.tif1772, TIFF0007632818000007.tif1670, and The horizontal angle θ may be calculated according to the following Equation 3. TIFF0007632818000009.tif1481 ​​(Formula 3)

[0059] In one embodiment, coordinates (e.g., three-dimensional Cartesian coordinates) associated with the first laser base station are determined by demodulating the first laser signal. In particular, demodulating the first laser signal may extract a data stream including the coordinates associated with the first laser base station.

[0060] In step 806, a second laser signal is detected from a second laser base station. The second laser signal may be modulated (e.g., phase or frequency) with a horizontal angle and a data stream associated with the second laser base station. The data stream may include an identifier for the second laser base station, coordinates for the second laser base station, a reference azimuth angle for the second laser base station, laser head calibration data for the second laser base station, horizontal and vertical angles of laser signals received from other laser base stations, an identifier for the laser base station, and any other relevant information. In one embodiment, the second laser signal includes a plurality of N-shaped beams (e.g., N-shaped beams 208 in FIG. 2).

[0061] In step 808, position information associated with the second laser base station in a reference coordinate system is extracted from the detected second laser signal. The position information associated with the second laser base station may include a horizontal angle associated with the second laser base station, a vertical angle associated with the second laser base station, and a coordinate associated with the second laser base station. The position information may be extracted from the detected second laser signal as described for the position information associated with the first laser base station in step 804.

[0062] In step 810, a position of the laser receiver in the reference coordinate system is determined based on the demodulated position information associated with the first laser base station, the horizontal and vertical angles measured from the first laser base station, the demodulated position information associated with the second laser base station, and the horizontal and vertical angles measured from the second laser base station. The position (coordinates) of the laser receiver can be calculated from the two laser based systems using Equation 4: TIFF0007632818000010.tif1868 (Formula 4) Where: TIFF0007632818000011.tif1567, So that it becomes TIFF0007632818000012.tif1964 TIFF0007632818000013.tif2017 and TIFF0007632818000014.tif1516 is the projection point on the receiver side along the direction line from each laser base station. TIFF0007632818000015.tif1413 and TIFF0007632818000016.tif1313 are the coordinates of laser base stations A and B, respectively, and D a and D. b is the distance from the laser base station to the projection point, TIFF0007632818000017.tif1718 and TIFF0007632818000018.tif2018 is the normal or direction from laser base stations A and B to the laser receiver TIFF0007632818000019.tif2041 and TIFF0007632818000020.tif1839, where a, b, and c are TIFF0007632818000021.tif1661, TIFF0007632818000022.tif1358, is the auxiliary scalar of TIFF0007632818000023.tif1852, TIFF0007632818000024.tif14129, TIFF0007632818000025.tif12128, and θ a and θ b is the horizontal angle measured from multiple subcarriers, and φ a and φ b is the vertical angle calculated from the time difference ratio of the signals of N beams. Laser base station coordinates TIFF0007632818000026.tif1815, TIFF0007632818000027.tif1917 and base station reference azimuth angle θ Aref , θ Bref is demodulated from the data streams transmitted from both laser base stations.

[0063] For systems with more than one base station, the laser receiver positions can be averaged from all pairwise combined positions, or a best fit gradient search can be used to find the resulting position.

[0064] 9 is a timing diagram 900 illustrating signals received by a laser receiver from laser base stations A, B, and C in one or more embodiments. Timing diagram 900 is described with reference to FIG. 1, where laser base station A corresponds to laser base station 102-A, laser base station B corresponds to laser base station 102-B, laser base station C corresponds to laser base station 102-C, and the laser receiver corresponds to laser receiver 104.

[0065] As shown in timing diagram 900, the laser receiver receives the laser signals from all the laser base stations. Due to the synchronous rotation of the base station transmitters, the laser receiver receives the signals as pulses separated in the time domain. The laser receiver can derive its horizontal angle θ directly from the laser signal 904. A and the vertical angle φ A 9. Measure (for laser base station A) and receive a data stream 902 demodulated from the laser signal 904. The data stream 902 includes an identifier id ("A") of laser base station A and the coordinates of laser base station A. TIFF0007632818000028.tif1413 and the reference azimuth angle θ related to laser base station A Aref and the horizontal angle θ of laser base station B (relative to laser base station A). BAand the horizontal angle θ of laser base station C (relative to laser base station A). CA and the vertical angle φ of laser base station B (relative to laser base station A). BA and the vertical angle φ of laser base station C (relative to laser base station A). CA The data measured and demodulated from the laser signals from laser base station B and laser base station C is similar to the data measured and demodulated from the laser signal from laser base station A described above. Period T906 is a laser receiver initialization time indicating the time for the laser receiver to collect the coordinates and reference azimuth angles of all laser base stations A, B, and C.

[0066] Figure 10 is a high-level block diagram illustrating a laser receiver 1002 in accordance with one or more embodiments. In one embodiment, the laser receiver 1002 may be the laser receiver 104 in Figure 1. It should be understood that Figure 10 is a high-level representation of the laser receiver 1002 that illustrates, for illustrative purposes, the functional operational elements of the laser receiver 1002, and that the laser receiver 1002 may be implemented with additional structural or functional elements.

[0067] The laser receiver 1002 includes a light detector 1008 for detecting and receiving one or more laser signals 1016 (e.g., N-shaped beam 208 in FIG. 2). In one embodiment, the light detector 1008 may be the light detector 402 of FIG. 4. The light detector 1008 may comprise, for example, one or more photodetectors, photodiodes, or any other suitable device. Upon receiving the laser signal 1016, the light detection signal is provided as an input to a light detection signal processor 1006, which determines whether light is received by the laser receiver 1002. Of course, any necessary signal processing, such as, for example, analog-to-digital conversion, may be performed in a well-known manner, and any modulation data superimposed on the laser signal 1016 is extracted and analyzed by the light detection signal processor 1006 in conjunction with the processor 1004. A power supply 1014 provides power to the laser receiver 1002 in a well-known manner. The power supply 1014 may be, for example, a rechargeable battery (e.g., NiMH) or alkaline battery, or may be powered by an external power source, such as, for example, construction equipment associated with the laser receiver 1002. The memory 1012 stores computer program instructions (e.g., code) that, when executed by the processor 1004, perform operations, such as, for example, the steps of the method 800 of FIG. 8. However, those skilled in the art will appreciate that the laser receiver 1002 may be implemented with other structures and components (e.g., transimpedance amplifiers, bandpass filters, demodulators, analog-to-digital converters), and that FIG. 10 is a high-level representation of the components of such a laser receiver for illustrative purposes.

[0068] Figure 11 is a high-level block diagram illustrating a laser base station 1102 in accordance with one or more embodiments. In one embodiment, the laser base station 1102 may be the laser base station 102 in Figure 1. It should be understood that Figure 11 is a high-level representation of the laser base station 1102 that illustrates, for illustrative purposes, the functional computing elements of the laser base station 1102, and that the laser base station 1102 may be implemented with additional structural or functional elements.

[0069] The laser base station 1102 includes a laser transmit 1106 for projecting one or more laser signals 1114 in a rotating beam (e.g., N-shaped beam 208 of an I-shaped beam in FIG. 2). In one embodiment, the laser transmit 1106 may be the laser transmit 302 in FIG. 3. The laser base station 1102 may modulate data on the laser signal 1114. The rotary encoder 1108 measures the instantaneous angle (horizontal angle) of the head at the laser base station 1102. The laser base station 1102 also includes a light detector 1118 for detecting and receiving one or more laser signals 1120 (e.g., N-shaped beam 208 in FIG. 2). In one embodiment, the light detector 1118 may be the light detector 304 in FIG. 3. Upon receiving the laser signal 1120, a light detection signal is provided as an input to a light detection signal processor 1116, which determines whether light is received by the laser receiver 1102.

[0070] The power supply 1112 provides power to the laser base station 1102 in a well-known manner. The power supply 1112 may be, for example, a rechargeable battery (e.g., NiMH) or an alkaline battery, or may be powered by an external power source, such as, for example, construction equipment associated with the laser base station 1102. The memory 1110 stores computer program instructions (e.g., code) that, when executed by the processor 1104, perform operations, such as, for example, the steps of the method 700 of FIG. 7. However, those skilled in the art will appreciate that the laser base station 1102 may have other configurations and may be implemented with other components, and that FIG. 11 is intended to illustrate, at a high level, some components of such a laser base station.

[0071] The systems, devices, and methods described herein can be implemented using one or more computers using digital circuitry, or using well-known computer processors, memory units, storage devices, computer software, and other components. Typically, a computer comprises a processor for executing instructions and one or more memories for storing instructions and data. A computer may also include or be coupled to one or more mass storage devices, such as one or more magnetic disks, internal hard disks and removable disks, magneto-optical disks, optical disks, and the like.

[0072] The systems, apparatus, and methods described herein may be implemented using computers operating in a client-server relationship. Typically, in such a system, the client computers are located remotely from the server computer and communicate over a network. The client-server relationship may be defined and controlled by computer programs executing on each of the client and server computers.

[0073] The systems, apparatus, and methods described herein may be implemented within a network-based cloud computing system. In such a network-based cloud computing system, a server or other processor connected to a network communicates with one or more client computers over the network. The client computer may communicate with the server, for example, via a network browser application resident and operating on the client computer. The client computer may store data on the server and access the data over the network. The client computer may send a request for data or a request for an online service to the server over the network. The server may perform the requested service and provide the data to the client computer. The server may also send data suitable for causing the client computer to perform a specified function (e.g., perform an operation) and display the specified data on a screen. For example, the server may send a request to the client computer suitable for causing the client computer to perform one or more of the steps or functions of the methods and workflows described herein (including one or more of the functions of Figures 6-8). Certain steps or functions of the methods and workflows described herein (including one or more of the steps or functions of Figures 6-8) may be performed by a server or other processor in the network-based cloud computing system. Certain steps or functions of the methods and workflows described herein, including one or more of the steps of Figures 6-8, may be performed by a client computer in a network-based cloud computing system. Certain steps or functions of the methods and workflows described herein, including one or more of the steps of Figures 6-8, in any combination, may be performed by a server and / or a client computer in a network-based cloud computing system.

[0074] The systems, devices, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier (e.g., a non-transitory machine-readable storage device) for execution by a programmable processor, and each step in the methods and workflows described herein (including one or more of the steps or functions of Figures 6-8) may be implemented using one or more computer programs executable by such a processor. A computer program is a set of computer program instructions that can be used directly or indirectly in a computer to perform a particular operation or bring about a particular result. Computer programs can be written in any manner of programming language, including compiled and interpreted languages, and can be deployed in any manner, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in any computing environment.

[0075] It will be appreciated by those skilled in the art that the laser receiver 1002 in FIG. 10 and the laser base station 1102 in FIG. 11 may have other configurations and may be implemented with other components, and that FIGS. 10 and 11 are intended to illustrate, at a high level, some components of such laser receivers and laser base stations. For example, the laser receiver 1002 and the laser base station 1102 may also include one or more network interfaces for communicating with other devices over a network, and one or more input / output devices (e.g., a display, a keyboard, a mouse, a speaker, buttons, etc.) that enable user communication with other computers or systems. Such input / output devices may include peripherals such as a printer, a scanner, a display screen, etc. For example, the input / output devices may include a display device such as a cathode ray tube (CRT) or a liquid crystal display (LCD) monitor for displaying information to a user, a keyboard, and a pointing device such as a mouse or a trackball through which a user can input.

[0076] The processors 1004 and 1104 may include both general purpose and special purpose microprocessors, and may be a single processor or one of multiple processors. The processors 1004, 1104 may include, for example, one or more central processing units (CPUs). The processors 1004 and 1104 and / or the memories 1012 and 1110 may comprise, be supplemented by, or be incorporated in one or more application specific integrated circuits (ASICs) and / or one or more field programmable gate arrays (FPGAs).

[0077] Memories 1012 and 1110 each include a tangible, non-transitory computer-readable storage medium, and each may include high-speed random access memory such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDR RAM) or other random access solid-state memory devices, or non-volatile memory such as one or more magnetic disk storage devices, such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory, semiconductor storage devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disk read-only memory (CD-ROM), digital versatile disk read-only memory (DVD-ROM) disks, or other non-volatile solid-state storage devices.

[0078] It should be understood that the above detailed description is in all respects non-limiting, illustrative and exemplary. The scope of the invention disclosed herein should be determined not from the detailed description, but from the claims, which should be interpreted in accordance with the broadest scope permitted by patent law. It should be understood that the embodiments described and shown herein are merely illustrative of the principles of the invention, and that various modifications may be made by those skilled in the art without departing from the scope and spirit of the invention. Those skilled in the art could implement various other feature combinations without departing from the scope and spirit of the invention.

Claims

1. 1. A method of operating a laser receiver, comprising: detecting a first laser signal from a first laser base station; extracting location information associated with the first laser base station from the detected first laser signal; detecting a second laser signal from a second laser base station; extracting location information associated with the second laser base station from the detected second laser signal; determining a location of the laser receiver based on the extracted location information associated with the first laser base station and the extracted location information associated with the second laser base station; the position information associated with the first laser base station comprises coordinates in a reference coordinate system, a reference azimuth angle associated with the first laser base station, and horizontal and vertical angles associated with the first laser base station; the position information associated with the second laser base station comprises coordinates in the reference coordinate system, a reference azimuth angle associated with the second laser base station, and horizontal and vertical angles associated with the second laser base station.

2. the step of extracting position information associated with the first laser base station from the detected first laser signal includes determining a horizontal angle associated with the first laser base station based on a modulation of the detected first laser signal; and extracting position information associated with the second laser base station from the detected second laser signal includes determining a horizontal angle associated with the second laser base station based on a modulation of the detected second laser signal.

2. The method according to claim 1 .

3. the detected first laser signal includes a plurality of N-shaped beams, and the step of extracting position information associated with the first laser base station from the detected first laser signal includes determining a vertical angle associated with the first laser base station based on a time of receipt of each of the plurality of beams of the detected first laser signal; the detected second laser signal includes a plurality of beams in an N-shape, and the step of extracting position information associated with the second laser base station from the detected second laser signal includes determining a vertical angle associated with the second laser base station based on a time of receipt of each of the plurality of beams of the detected second laser signal.

2. The method according to claim 1 .

4. the step of extracting location information associated with the first laser base station from the detected first laser signal includes determining a coordinate and a reference azimuth angle associated with the first laser base station by demodulating the detected first laser signal; and extracting location information associated with the second laser base station from the detected second laser signal includes determining a coordinate and a reference azimuth angle associated with the second laser base station by demodulating the detected second laser signal.

2. The method according to claim 1 .

5. the first laser base station and the second laser base station are calibrated to the reference coordinate system; The position of the laser receiver is determined in the reference coordinate system.

2. The method according to claim 1 .

6. A laser receiver comprising: a light detector for detecting a first laser signal from a first laser base station and a second laser signal from a second laser base station; A processor; A memory storing computer program instructions that, when executed on the processor, cause the processor to: extracting location information associated with the first laser base station from the detected first laser signal; extracting location information associated with the second laser base station from the detected second laser signal; determining a location of the laser receiver based on the extracted location information associated with the first laser base station and the extracted location information associated with the second laser base station; the position information associated with the first laser base station comprises coordinates in a reference coordinate system, a reference azimuth angle associated with the first laser base station, and horizontal and vertical angles associated with the first laser base station; a reference azimuth angle associated with the second laser base station; and a horizontal angle and a vertical angle associated with the second laser base station.

7. the step of extracting position information associated with the first laser base station from the detected first laser signal includes determining a horizontal angle associated with the first laser base station based on a modulation of the detected first laser signal; and extracting position information associated with the second laser base station from the detected second laser signal includes determining a horizontal angle associated with the second laser base station based on a modulation of the detected second laser signal.

7. The laser receiver according to claim 6, wherein the laser receiver is a laser beam splitter.

8. the detected first laser signal includes a plurality of N-shaped beams, and the step of extracting position information associated with the first laser base station from the detected first laser signal includes determining a vertical angle associated with the first laser base station based on a time of receipt of each of the plurality of beams of the detected first laser signal; the detected second laser signal includes a plurality of beams in an N-shape, and the step of extracting position information associated with the second laser base station from the detected second laser signal includes determining a vertical angle associated with the second laser base station based on a time of receipt of each of the plurality of beams of the detected second laser signal.

7. The laser receiver according to claim 6, wherein the laser receiver is a laser beam splitter.

9. the step of extracting location information associated with the first laser base station from the detected first laser signal includes determining a coordinate and a reference azimuth angle associated with the first laser base station by demodulating the detected first laser signal; and extracting location information associated with the second laser base station from the detected second laser signal includes determining a coordinate and a reference azimuth angle associated with the second laser base station by demodulating the detected second laser signal.

7. The laser receiver according to claim 6, wherein the laser receiver is a laser beam splitter.

10. the first laser base station and the second laser base station are calibrated to the reference coordinate system; The position of the laser receiver is determined in the reference coordinate system.

7. The laser receiver according to claim 6, wherein the laser receiver is a laser beam splitter.

11. 1. A laser measurement system comprising: a first laser base station for projecting a first laser signal; a second laser base station for projecting a second laser signal; a laser receiver; The laser receiver includes: a light detection unit for detecting the first laser signal and the second laser signal; A processor; A memory storing computer program instructions that, when executed on the processor, cause the processor to: extracting location information associated with the first laser base station from the detected first laser signal; extracting location information associated with the second laser base station from the detected second laser signal; determining a location of the laser receiver based on the extracted location information associated with the first laser base station and the extracted location information associated with the second laser base station; the position information associated with the first laser base station comprises coordinates in a reference coordinate system, a reference azimuth angle associated with the first laser base station, and horizontal and vertical angles associated with the first laser base station; and a reference azimuth angle associated with the second laser base station, and a horizontal angle and a vertical angle associated with the second laser base station.

Images