Method for detecting target in measurement system

Abstract

For a measuring machine, a method is provided for identifying and detecting a selected target in a measuring system in which a plurality of targets are present. The light emission periods (T1, T2, T3) of the identification light of the light transmitters of the plurality of targets differ from each other, the light reception period (TA) of the light receiver of the measuring machine is set to be the same as the light emission period of the identification light of the selected target, the identification light of the selected target is amplified by accumulation processing each time the identification light of the selected target is received, the amplified signal is identified, and the selected target is detected.

Description

Technical Field

[0001] The present invention relates to a target detection method in a measurement system for detecting and measuring one target from a plurality of targets. Background Art

[0002] Conventionally, for example, at a work site, ground leveling work is sometimes performed using a single measuring machine and multiple ground leveling vehicles. Each vehicle has identification information and a target. The measuring machine acquires the target's identification information, automatically aims at, and tracks a specific ground leveling vehicle to perform measurement work. For example, Patent Document 1 uses a reflective tape with different black and white stripes as the identification information. A camera on the measuring machine captures an image, and a recognition unit detects the target's unique identification information based on differential processing of the captured image. Patent Document 2 employs a barcode on each target for identification, which is detected by laser scanning.

[0003] For example, the method disclosed in Patent Document 3 is known as a method for detecting and measuring one of multiple targets. In this method, a light pulse is emitted from the target toward a measuring instrument. A first image and a second image of the target are captured using an imaging device installed in the measuring instrument. The measuring instrument and the target are synchronized so that the light pulse is emitted simultaneously with the capture of the first image and not simultaneously with the capture of the second image. A difference image is then obtained between the first and second images, and the position of the light pulse in the difference image is used as identification information to determine the direction from the measuring instrument toward the target.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-138802

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-008406

[0008] Patent Document 3: U.S. Patent No. 11,092,434 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, in detection methods such as barcodes, when detecting a specific target, the measuring machine must first search all around to find the target, and its location is completely unclear. It is also possible that other targets are detected during the detection, so there is a problem that it takes time to find the specific target.

[0011] Furthermore, in conventional methods that determine the direction from the measuring instrument to the target by obtaining a difference image between the first and second images and using the position of a light pulse emitted from the target toward the measuring instrument in the difference image as identification information, image capture and light pulse emission are synchronized. To achieve this synchronization, the measuring instrument and target must each have synchronized, high-performance clocks that generate accurate clock signals. If both clocks fail to correctly generate clock signals, synchronization cannot be achieved, resulting in an inability to determine the direction from the measuring instrument to the target.

[0012] An object of the present invention is to provide a target detection method that solves the above-mentioned problems.

[0013] Means for solving problems

[0014] In order to achieve the above-mentioned purpose, the present invention relates to a method for detecting a target in a measuring system, wherein the measuring system detects one target from a plurality of targets and performs measurement, the measuring system includes a measuring machine, the measuring machine measures the target selected based on a selection signal that selects the one target, the plurality of targets emit identification light at different periods, the measuring machine includes: a light receiving unit that receives the identification light; an input unit that inputs the selection signal; a storage unit; and a control unit, the control unit sets the period of light received by the light receiving unit based on the selection signal, each time identification light is received, the identification light is stored in the storage unit as light receiving data, a calculation process is performed on the light receiving data stored in the storage unit to accumulate or average the light receiving data, and the target to be measured is detected based on the calculation result.

[0015] In this manner, the target to be measured can be detected without synchronizing the clocks between the measuring machine side and the target side.

[0016] The selection signal for selecting one target from a plurality of targets is preferably input through wireless communication.

[0017] If the light emission cycles of the plurality of targets are set to be asynchronous at least before each of the five cycles, the calculation process can be performed reliably and in a short time, which is preferable.

[0018] Preferably, each of the plurality of targets has a prism, the measuring instrument emits tracking light for tracking the prism toward the target to be measured detected by the control unit, and aligns the measurement optical axis with respect to the prism of the target to be measured based on the reflected light. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a perspective view schematically showing an embodiment of a measuring machine and a plurality of targets according to the present invention.

[0020] Figure 2 It is a block diagram of the measuring machine and target unit of the present invention.

[0021] Figure 3 (A) is a side view of the target unit of the present invention, Figure 3 (B) is a top view of the target unit of the present invention.

[0022] Figure 4 This is a periodic table showing the light receiving period of the light receiver of the present invention and the light emitting period of each light transmitter.

[0023] Figure 5 This is a flowchart showing the operation of detecting and measuring a target according to the present invention.

[0024] Description of labels

[0025] 1. Measurement system

[0026] 8-prism

[0027] 10 measuring machines

[0028] 23 Input unit

[0029] 25 Measuring machine communication department

[0030] 26 Distance Measurement Unit

[0031] 27 Tracking Department

[0032] 28 Storage Department

[0033] 29 Measuring machine control unit

[0034] 291 Light receiving processing unit

[0035] 40 light receivers

[0036] 70 light transmitter

[0037] 74 light sources

[0038] 77 light transmitter control unit

[0039] 78 light transmitter communication department

[0040] TU target unit

[0041] L identification light DETAILED DESCRIPTION

[0042] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

[0043] The present embodiment does not limit the invention but is an illustration, and all features and combinations thereof described in the present embodiment are not necessarily essential to the invention. In addition, in the following description of the embodiment, the same reference numerals are used for the same components, and repeated descriptions are appropriately omitted.

[0044] Figure 1This diagram schematically illustrates the structure of a measurement system 1 according to a preferred embodiment of the present invention. The measurement system 1 includes a measurement device 10 and multiple target units TU. In this embodiment, three target units TU1 through TU3 are included. Target units TU1 through TU3 have the same structure, except for the light emission period T described below. Unless otherwise specified, they are collectively referred to as target units TU.

[0045] The measuring machine 10 is a total station equipped with distance and angle measurement functions and tracking functions. The measuring machine 10 is mounted on a tripod 4 at the center of a reference point. The measuring machine 10 comprises a base 2a mounted on a leveler; a bracket 2b that rotates horizontally relative to the base 2a about a horizontal rotation axis H; and a telescope 2c that rotates vertically about a vertical rotation axis V at the center of the bracket 2b.

[0046] The target unit TU has a prism 8, which is a target object to be measured by the measuring machine 10, at the upper end of the rod 6. The lower end of the rod 6 is placed substantially perpendicular to the measuring point. The prism 8 has an optical property of retroreflecting light incident from all directions.

[0047] The target unit TU includes a light transmitter 70 that emits identification light L in a substantially horizontal direction and along a substantially entire circumference. Each target unit TU emits light at a different period. Specifically, the identification lights L1 to L3 emitted from the light transmitter 70 attached to the target units TU1 to TU3 are emitted at different periods T1 to T3, respectively.

[0048] The light emission period T of the light transmitter 70, which is different depending on the target unit TU installed, is the identification information inherent in the target unit TU. Figure 4 As shown, the measuring machine 10 includes a light receiver 40 as a light receiving unit capable of receiving light emitted from the light transmitter 70 , and can capture a specific target unit TU by analyzing the light reception signal of the light receiver 40 , thereby identifying the received target unit TU.

[0049] Figure 2 This is a block diagram of the configuration of the measuring machine 10 and target unit TU. The measuring machine 10 is a motor-driven total station and includes a horizontal angle detector 21, a vertical angle detector 22, a horizontal rotation drive unit M1, a vertical rotation drive unit M2, an input unit 23, a display unit 24, a measuring machine communication unit 25, a distance measuring unit 26, a tracking unit 27, a storage unit 28, and a measuring machine control unit 29.

[0050] The horizontal angle detector 21 and the vertical angle detector 22 are encoders. The horizontal angle detector 21 is mounted on the rotation axis of the bracket 2b and detects the horizontal angle of the bracket 2b. The vertical angle detector 22 is mounted on the rotation axis of the telescope 2c and detects the vertical angle of the telescope 2c. The horizontal rotation drive unit M1 and the vertical rotation drive unit M2 are motors. The horizontal rotation drive unit M1 moves the rotation axis of the bracket 2b, while the vertical rotation drive unit M2 moves the rotation axis of the telescope 2c. The two drive units work together to change the orientation of the telescope 2c.

[0051] The measuring machine communication unit 25 can communicate with an external network, such as the Internet, using the Internet Protocol (TCP / IP), to exchange information with the target unit TU. Wireless communication is not limited to this, and known wireless communication methods can be used. Measurement results (ranging and angle measurements) performed by the measuring machine 10 can also be transmitted to a processing terminal via the measuring machine communication unit 25.

[0052] The distance measuring unit 26 includes a light transmitting unit and a light receiving unit. For example, the light transmitting unit emits distance measuring light, such as an infrared pulsed laser, and the light receiving unit receives the reflected light. Distance measurement is performed based on the time difference between the distance measuring light and an internal reference light. In this embodiment, the measuring machine 10 aims at the prism 8 of the target unit TU and measures the distance to the prism 8.

[0053] The tracking unit 27 comprises a tracking light-emitting system that emits infrared laser light, for example, of a wavelength different from that of the ranging light, as tracking light, and a tracking light-receiving system comprising an image sensor such as a CCD or CMOS sensor. The tracking unit 27 can acquire a landscape image containing the tracking light and an image without the tracking light, and transmit both images to the measuring machine control unit 29. The measuring machine control unit 29 determines the center of the target image based on the difference between the two images. The measuring machine control unit 29 detects the target position as the location where the distance between the target image center and the center of the visual axis of the telescope 2c is within a certain value, and automatically tracks the target, ensuring that the telescope 2c is always oriented toward the target.

[0054] The storage unit 28 includes a ROM and a RAM. The ROM stores programs for the measuring machine control unit 29, and the RAM executes various controls. The RAM also stores various data sent from the light receiving calculation processing unit 291 described later.

[0055] The measuring machine control unit 29 is a microcontroller equipped with a CPU. It controls the transmission and reception of information via the measuring machine communication unit 25, the driving of the rotation axes of the horizontal rotation drive unit M1 and the vertical rotation drive unit M2, distance measurement by the distance measuring unit 26, angle measurement by the horizontal angle detector 21 and the vertical angle detector 22, and automatic tracking by the tracking unit 27. The measuring machine control unit 29 includes a light reception processing unit 291. Light reception signals received by the light receiver 40, acting as a light receiving unit, are input to the light reception processing unit 291 and stored in the storage unit 28 in association with the horizontal angle detector 21 at the time the light reception signals were acquired. The light reception processing unit 291 performs computational processing on the input signals to identify the target unit TU.

[0056] The input unit 23 and display unit 24 serve as interfaces for the measuring machine 10. The input unit 23 includes a power button, numeric keys, and an execute key, allowing the operator to input operations and information to the measuring machine 10. In this embodiment, measurement instructions and result confirmation are input directly through the input unit 23. However, a separate controller may be provided to remotely control the measuring machine 10.

[0057] The light receiver 40 is fixed to the bracket 2b and is positioned in front of the measuring instrument 10. The light receiver 40 is configured to receive light emitted by the target unit 70. The signal acquisition interval of the light receiver 40 is shorter than the emission period, which is sufficient for receiving pulsed light of different periods.

[0058] The light receiver 40 of this embodiment is equipped with a cylindrical lens (not shown) and a rectangular light-receiving sensor in the vertical direction, as well as a slit that limits the horizontal light-receiving range. This allows it to receive the identification light L of the target unit TU even when there is a height difference between the measuring machine 10 and the target. The light receiver 40 is fixed to the bracket 2b. Therefore, when the measuring machine 10 is rotated horizontally, the horizontal direction of the target unit TU is detected by receiving the identification light L. The light signal received by the light receiver 40 is input to the light-receiving arithmetic processing unit 291, where it is processed to identify the target unit TU corresponding to the input identification light L.

[0059] Next, use Figure 1 and Figure 3 The target unit TU is described. Figure 3 (A) is a side view of the target unit TU. Figure 3 (B) is a top view thereof.

[0060] The target unit TU includes a rod 6 as a target support component, a prism 8, and a light transmitter 70. The prism 8 is supported on the upper end of the rod 6 so that the central axis A of the rod 6 passes through the optical center of the prism 8. The distance (installation height) from the optical center of the prism 8 to the lower end of the rod 6 is known. During movement, the operator maintains the central axis A of the rod 6 in a vertical position while transporting it. At the measurement point, the operator maintains the central axis A of the rod 6 in a vertical position and places the lower end of the rod 6 against the measurement point, and the measuring machine 10 performs distance and angle measurement on the prism 8.

[0061] The light transmitter 70 includes a cylindrical housing 76, a light source 74, a light transmitter control unit 77, and a light transmitter communication unit 78. The light transmitter 70 is attached to the upper end of the prism 8 so that the central axis of the housing 76 coincides with the central axis A of the rod 6.

[0062] The light source 74 is, for example, an infrared LED (Light Emitting Diode), which emits ranging light and infrared light of a wavelength different from that of the tracking light as identification light L. The light source 74 is installed near the center of the housing 76 in such a manner that the identification light L is emitted around the central axis A toward the rod 6. On the outer peripheral surface of the housing 76, a plurality of light transmission ports 75 are arranged at equal intervals along the circumferential direction on a plane perpendicular to the central axis A of the rod 6. The number of the light transmission ports 75 is six in the example shown in the figure, but is not limited thereto. Figure 3 As shown in (B), it is preferred to emit the identification light Lc radially in the entire circumferential direction around the central axis A. This is because the operator does not need to consciously point the light-emitting port 75 toward the measuring machine 10, and the operation becomes easier. However, the light-emitting direction is not limited to this, and it can also be a part of the entire circumferential direction or one direction. This is because, in this case, the operator only needs to rotate the rod 6 so that the light emission direction is toward the measuring machine 10. The configuration of the light transmitter 70 is not limited to the upper end side of the prism 8, but can also be the lower end side. In addition, instead of setting the light source 74 inside the housing 76, infrared LEDs can be respectively set at the position of the light-emitting port 75.

[0063] The light transmitter communication unit 78 is a communication interface of the light transmitter 70 and can communicate with the measuring instrument 10. A command signal from the measuring instrument 10 is input via the light transmitter communication unit 78.

[0064] The light transmitter control unit 77 is, for example, a microcontroller with a CPU and memory mounted on a substrate. It controls the operation and deactivation of the light source 74 based on signals from the measuring machine 10. The light transmitter control unit 77 flashes the light source 74 at a set period T. This flashing period is set by the measuring machine 10 and input to the light transmitter control unit 77 via the communication units 25 and 78. The light emission period can be freely set or selected from a plurality of pre-set light emission periods. Regardless of the method selected, a different light emission period T is set for each target unit TU, and the light emission period T for each target unit TU is stored in the storage unit 28 via the measuring machine control unit 29.

[0065] In this embodiment, the light transmitter 70 controls the operation and stopping of the light source 74 based on signals from the measuring machine 10. This is advantageous from the perspective of power conservation. However, this is not essential, and the light transmitter 70 may also flash at a predetermined period T during measurement. In this case, the light transmitter communication unit 78 is not required, and the power can be turned on and off manually. Alternatively, a push switch (not shown) may be provided as an input unit, allowing the operator holding the rod 6 to issue commands to start and stop the lighting of the light source 74 from the target unit TU, and to send and receive commands to the measuring machine 10.

[0066] The measuring machine 10 has a recognition function of recognizing a specific target unit TU from among the plurality of target units TU at a work site where a plurality of target units TU exist.

[0067] In this embodiment, the light sources 74 of the three target units TU1 to TU3 emit light at different cycles T1 to T3, respectively. Specifically, the light transmitter 70 transmits pulsed light as identification light L at every cycle T. The identification light L is emitted horizontally around the light transmitter 70, receiving it at the light receiver 40 of the measuring instrument 10 and transmitting it to the light reception processing unit 291. In this embodiment, there is no need to synchronize the operations of the light reception processing unit 291 and the light transmitter control unit 77 of each target unit TU to align the timing of light emission and light reception. Instead, the light reception signals are stored in the storage unit 28, and the light reception signals obtained by the light reception processing unit 291 are processed, for example, integrated, using a predetermined method for each cycle T of the designated target unit TU, thereby detecting and identifying the identification light L. Furthermore, the light receiver 40 has the ability to seamlessly receive and identify pulsed light of different cycles.

[0068] Figure 4 The graph shows the predetermined time (light reception cycle TA) of the light receiver 40 and the emission of the identification lights L1 to L3 by the light transmitters 70 of the first to third target units TU1 to TU3. The horizontal axis shows the elapsed time.

[0069] The light transmitters 70 of target units TU1-TU3 emit pulsed light at different periods, T1-T3, respectively. The light signals received by the light receiver 40 are continuously input as light reception data into the light reception processing unit 291 and stored in the storage unit 28. The stored light reception data is divided into sections for each set light reception period, TA, and the divided data is stored sequentially in chronological order.

[0070] By setting the light reception period TA to the emission period T of the identification light L of the target unit TU to be identified, the target unit TU to be identified can be identified based on the identification light L. For example, when the first target unit TU1 is to be identified from among the three target units TU1 to TU3, the light reception period of the light receiver 40 is set to T1. Because the identification lights L1 to L3 emit at different periods, even if all the identification lights L1 to L3 are emitted simultaneously, the emission periods will be offset.

[0071] Next, refer to Figure 4 The method of identifying the first target unit TU1 will be described based on the relationship between the emission period of the identification lights L1 to L3 in the light transmitter 70 of each target unit TU1 to TU3 and the light reception period of the light receiver 40 of the measuring instrument 10.

[0072] When the selection signal input to the input unit 23 selects the first target unit TU1, the measuring machine control unit 29 of the measuring machine 10 sets the light reception period of the light receiver 40 to a period TA equal to the light emission period T1 of the first target TU1. Therefore, the light emission periods T2 and T3 of the light transmitters 70 of the second and third target units TU2 and TU3 differ from the light reception period TA of the light receiver 40.

[0073] Because the emission period T1 of the identification light L1 of the first target unit TU1 is equal to the light reception period TA, the second and subsequent light emissions are received after the first emission, overlapping with the first emission. Meanwhile, the identification lights L2 and L3 of the second and third target units TU2 and TU3 receive the first emission, but the second and subsequent light emissions differ from the light reception period TA and therefore do not overlap with the first emission. Each of these identification lights L2 and L3 overlaps with the first emission only when the emission time is a multiple of the light reception time.

[0074] The measuring machine control unit 29 stores the identification light L1 received by the light receiver 40 as light receiving data in the storage unit 23. The light receiving calculation processing unit 291 accumulates the light receiving data stored in the storage unit 23 when receiving the next light receiving data. Thus, each time the light receiving calculation processing unit 291 receives light receiving data, it stores it in the storage unit 23 in a time series, and sequentially accumulates it into the previously accumulated light receiving data. During this accumulation process, only the light receiving signal of the identification light L1 is amplified, making it easy to identify the difference between the identification light L1 and each of the identification lights L2 and L3. Each of the light emission cycles T1, T2, and T3 is set to be asynchronous for at least five cycles. Thus, experiments have confirmed that even with a small number of accumulations, each of the identification lights L1, L2, and L3 can be reliably identified. Furthermore, as described above, the light emission cycle of the identification light and the light receiving cycle only need not deviate significantly during the accumulation period. Thus, it is possible to identify a target without completely synchronizing the light emission cycle with the light receiving cycle.

[0075] Furthermore, to identify the second target unit TU2, the light reception period TA is set equal to the light emission period T2 of the second target TU2. To identify the third target unit TU3, the light reception period TA is set equal to the light emission period T3 of the third target TU3.

[0076] Then, based on Figure 5 The flowchart of FIG. 1 illustrates a process of locking a specific target unit TU, for example, the first target unit TU1 , from among a plurality of target units TU and performing measurement.

[0077] First, in step S101, the light transmitters 70 of the target units TU1-TU3 each cause the light source 74 to emit light at a lighting cycle T1-T3, thereby starting to emit identification light L1-L3. When the light receiver 40 receives the identification light L1-L3, the lighting cycles T1-T3 are stored in the storage unit 23. Alternatively, the lighting cycles T1-T3 can be input from the input unit 23 of the measuring instrument 10. Target units TU1-TU3, which emit light at lighting cycles T1-T3, are then positioned at a predetermined location at the measurement site.

[0078] Next, the process proceeds to step S102, where a specific target unit TU1 is selected. This selection can be input from the input unit 23 of the measuring machine 10, or the operator holding the target unit TU1 can send a selection signal to the measuring machine communication unit 25 via a controller (not shown) or the light transmitter communication unit 78 of the light transmitter 70.

[0079] Next, the process proceeds to step S103, and the light receiver 40 starts a light receiving operation. Here, the light receiving period TA is set to the light emission period T1 of the identification light L1.

[0080] Next, the process proceeds to step S104 , where the horizontal rotation drive unit M1 of the measuring machine 10 starts to be driven to horizontally rotate the bracket unit 2 b around the horizontal rotation axis H.

[0081] Next, in step S105, the identification light L1 received by the light receiver 40 is inputted as light reception data to the light reception processing unit 291 at any time, and is processed and accumulated as described above. Thus, the first target unit TU1 is identified as the selected target unit TU.

[0082] Next, the process proceeds to step S106. In order to align the optical axis of the telescope 2c with the prism 8 of the first target unit TU1, the measuring machine 10 drives the telescope 2c in the up and down directions by driving the vertical rotation drive unit M2, and causes the tracking light of the tracking unit 27 to scan up and down, thereby capturing the prism 8 based on the reflected light of the prism 8.

[0083] Next, the process proceeds to step S107 , where the photometric optical axis is aligned and locked with respect to the prism 8 of the first target unit TU1 , and distance and angle measurement is performed.

[0084] Furthermore, the present invention is not limited to the above-described embodiment. For example, the calculation processing only needs to set the light emission period of the target unit TU selected as the identification target and the light reception period of the measuring device 10 to be the same, so that the light reception calculation processing unit 291 can reliably identify signals of the same period. In addition to the above-described accumulation processing, averaging processing may also be used. Furthermore, the above-described embodiment can be modified based on the knowledge of those skilled in the art, and such modifications are also included in the scope of the present invention.

Claims

1. A method for detecting a target in a measurement system, wherein the measurement system detects and measures one target from a plurality of targets, wherein the method for detecting a target in the measurement system is characterized by: The measuring system includes a measuring machine configured to measure a target selected based on a selection signal for selecting the one target. The plurality of targets emit identification light at different periods. The measuring machine includes: a light receiving unit for receiving the identification light; an input unit for inputting the selection signal; a storage unit; and a control unit. The control unit sets the reception period of the light receiving unit based on the selection signal, stores the identification light as light receiving data in the storage unit each time the identification light is received, performs calculation processing on the light receiving data stored in the storage unit by accumulating or averaging, and detects the target to be measured based on the calculation result.

2. The method for detecting a target in a measurement system according to claim 1, wherein: The selection signal is input through wireless communication.

3. The method for detecting a target in a measurement system according to claim 1, wherein: The light emission periods of the plurality of targets are not synchronized at least before each of the five periods.

4. The method for detecting a target in a measurement system according to any one of claims 1 to 3, wherein: The plurality of targets each have a prism, The measuring machine emits tracking light that tracks the prism toward the target to be measured detected by the control unit, and aligns the measurement optical axis with respect to the prism of the target to be measured based on the reflected light.

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