A servo total station and a multi-prism recognition method

Abstract

The present invention discloses a servo total station and a multi-prism recognition method. The total station includes a target recognition unit, a servo drive unit, a measurement unit, a main control unit, a communication unit, and a storage unit. The present invention can simultaneously recognize and output the coordinate and angle information of all prisms within the field of view; only one ATR is required in the present invention, and subsequent measurements can be automatically performed by rotating according to the angle information recognized initially; the present invention dynamically adjusts the laser intensity and reception gain according to the prism distance, signal strength, etc., to ensure the stability and accuracy of the signal under different distances and light conditions, and further obtain clear and stable spot characteristics, which is especially suitable for stable measurement under the condition of large atmospheric jitter. In short, it has significant advantages over traditional single-target servo total stations in terms of measurement efficiency, operation convenience, environmental adaptability, and intelligent data processing, especially showing obvious efficiency improvement and environmental adaptability in the scenario of multiple prisms.

Description

Technical Field

[0001] The present invention belongs to the technical field of automated surveying, and particularly relates to a servo total station and a multi-prism recognition method. Background Art

[0002] A servo total station is an intelligent electronic total station capable of automatically searching for, tracking, identifying, and accurately aiming at a target and obtaining information such as angles, distances, three-dimensional coordinates, and images. Among them, the automatic target recognition function is the core and decisive factor for the measurement accuracy of the total station. The automatic target recognition function requires the instrument to automatically aim at the prism, which involves two steps: identifying the prism and aligning with the prism.

[0003] The current main method for identifying the prism is to use a 2D sensor to identify the prism. The laser diode in the instrument emits a beam of laser, which is coaxially projected onto the telescope axis through optical components and emitted from the objective lens. After the laser reaches the prism, the prism reflects the laser back into the telescope. The beam splitter in the telescope separates the reflected received beam and guides the received beam to the 2D sensor to form a light spot. The 2D sensor converts the received optical signal into corresponding image data, and the calculation module inside the instrument performs image processing on the image data to obtain the center point coordinates of the light spot. After conversion, the angle offset value of the center of the prism reflection light spot relative to the center of the instrument is obtained. Since the total station needs to aim at the target before measuring the angle and distance of the target, after obtaining the angle offset value of the center of the prism reflection light spot relative to the center of the instrument, it is also necessary to move the center of the telescope of the instrument to the center of the prism, and this process is realized by the servo system.

[0004] The traditional manual total station manually aims at each measurement point. Although the existing servo total stations have changed the manual aiming to automatic aiming and the measurement efficiency has been improved to some extent, they basically measure single points, and for the application scenarios of multi-target measurement, the measurement efficiency still needs to be improved. Summary of the Invention

[0005] The present invention provides a servo total station and a multi-prism recognition method to solve the problem of multi-prism recognition during the measurement of the total station, thereby improving the measurement efficiency.

[0006] The technical solutions provided by the present invention are as follows:

[0007] A servo total station, comprising a target recognition unit, a servo drive unit, a measurement unit, a main control unit, a communication unit and a storage unit; the target recognition unit is used to identify and locate multiple prism targets, and the target recognition unit includes a laser emission module, a laser reception module and a processing and control module; the laser emission module is used to emit a laser beam covering the entire field of view, the laser reception module is used to receive the reflected light and form an image, and the processing and control module is used to process the image to obtain the position information of each prism target; the servo drive unit is used to drive the telescope of the total station to rotate in the horizontal direction and the telescope of the total station to rotate in the vertical direction according to the position information of the prism target provided by the target recognition unit, so as to achieve aiming at the target prism; the measurement unit includes a distance measurement unit and an angle measurement unit, the distance measurement unit is used to measure the distance to the target prism after aligning with the prism, and the angle measurement unit is used to measure the angles of the horizontal axis and the vertical axis of the total station; the main control unit is used to receive the operation instructions of the user or external communication instructions, and decompose the operation instructions or communication instructions into execution tasks of each unit module, so as to achieve automatic alignment and measurement of the prism target; the communication unit is used to provide communication support between the inside of the total station and external devices, output the internal measurement data and device status to an external monitoring system, or receive external communication instructions; the storage unit is used to provide a data storage function, and support the temporary storage and long-term storage of measurement data.

[0008] Further, the laser reception module in the target recognition unit includes a reception lens and a photoelectric sensor, the reception lens converges the reflected light onto an image sensor, and the image sensor converts the received reflected light into an electrical signal to form an image.

[0009] Further, the processing and control module in the target recognition unit is also used to automatically adjust the intensity of laser emission, the reception gain and exposure time of the image sensor.

[0010] Further, the total station also includes a graphic interaction unit, and the graphic interaction unit includes an input device and an output device, which are used to provide an interaction interface between the user and the instrument, and the user inputs operation instructions through this unit and views the measurement results and system status in real time.

[0011] Further, the total station also includes an inclination compensation unit, and this inclination compensation unit is used to collect the inclination angle of the vertical axis of the total station, and will automatically compensate the angle when the total station is inclined.

[0012] Further, when the total station inputs and outputs, it simultaneously includes data of multiple prism targets, and this data includes prism type, constant, distance, angle, and the coordinates of the prism in the total station coordinate system.

[0013] A multi-prism recognition method based on the above total station, characterized in that it includes a learning prism stage and a monitoring prism stage;

[0014] Learning prism stage: First, manually aim at the prism located at the middle position of the field of view, and this position is recorded as the preferred position; then the laser emission module projects the laser into the telescope field of view so that the laser covers all prism positions; the laser reception module captures the light beams reflected by each prism and converts the optical signals into images through the image sensor; the processing and control module of the target recognition unit first preprocesses the image to ensure the contrast and clarity of the prism light spots, and then distinguishes the light spots of each prism from the image background through threshold segmentation to form independent light spots; finally, obtain and save the prism information including the center coordinates of each light spot.

[0015] Monitoring prism stage: First, align with the preferred position through the servo drive unit, and then obtain the position information of all prisms in the field of view through the target recognition unit and compare it with the prism information saved in the learning prism stage. If all the prisms in the learning prism stage exist, align with each prism in turn through the servo drive unit and measure the distance of the prism through the ranging unit, otherwise output the prism loss information.

[0016] Furthermore, the processing and control module of the target recognition unit automatically adjusts the laser intensity and the reception gain of the image sensor according to the actual situation: when multiple prism reflection light spots are received, first obtain the first image according to the default gain, and then divide the light spots into two groups according to the difference between the light spots and the ideal value. First, perform feature extraction on the group with appropriate gain to calculate the center positions of the light spots of each prism; for the group with inappropriate gain, first select a light spot from it, set an appropriate gain value for it and perform feature extraction to obtain the center position of the light spot, and then perform regrouping processing on the other light spots in this group under this gain value; repeat the above process until all light spots are traversed.

[0017] Furthermore, the preprocessing performed by the processing and control module on the image includes spatial domain filtering and frequency domain filtering, and the threshold segmentation uses the Otsu method or the maximum entropy method.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] (1) Efficient simultaneous recognition and output of multiple targets

[0020] Traditional servo total stations can only aim at and measure single targets one by one, and can only output the data of one prism each time. When dealing with multiple targets, it is necessary to repeat aiming, measuring and data transmission many times. The present invention can cover the entire field of view and simultaneously recognize and output the coordinates and angle information of all prisms in the field of view. This function is applicable to multi-prism monitoring scenarios, avoiding the cumbersome operations of learning and aiming one by one, and significantly improving the measurement efficiency especially in projects with a large number of prisms in the field of view.

[0021] (2) Automatic rotation and multi-target fast mode

[0022] The total station of the present invention has the ability to automatically turn to each prism, eliminating the need for manual aiming. Its working process has been optimized to obtain the angular information of multiple prisms during a single automatic target recognition (ATR) process, and based on this information, it automatically rotates to each prism to complete distance measurement, achieving fast data acquisition. In traditional total stations, monitoring multiple targets requires N ATR searches to be completed one by one, while the total station of the present invention only requires one ATR, and then automatically rotates for measurement according to the angular information initially recognized, thus reducing the ATR search process by N - 1 times.

[0023] (3) Enhanced environmental adaptability

[0024] The present invention has stronger adaptability in complex field environments. Under conditions of large weather changes and strong signal interference, single-target servo total stations may have data measurement deviations or even interruptions due to unstable signals. For example, in extreme weather such as rain and fog, if the reflection signal of the current prism of a single-target instrument is weak or missing, it may misidentify the data of other nearby prisms as target data, affecting the measurement accuracy. The present invention, however, intelligently detects the signal strength changes of each prism in the field of view, avoids mismeasurement, and at the same time intelligently identifies the prism with signal disappearance and reports anomalies by comparing historical data, making the monitoring more reliable.

[0025] (4) Intelligent image processing and gain control

[0026] The present invention supports multi-spot recognition processing of images and has advanced functions of image preprocessing, spot separation, and feature extraction. Through spatial domain and frequency domain filtering, high-quality image recognition effects can be maintained in various noise environments. In addition, the present invention dynamically adjusts the laser intensity and receiving gain according to the prism distance, signal strength, etc., to ensure the stability and accuracy of the signal under different distances and light conditions, and then obtains clear and stable spot features, which is especially suitable for stable measurement under large atmospheric jitters.

[0027] (5) Convenient multi-target data interface

[0028] The multi-target servo total station supports the simultaneous output of measurement data of multiple targets on the data interface, including information such as the distance, angle, and coordinates of each prism. This parallel output method improves the data transmission efficiency, is suitable for cooperating with external monitoring systems for real-time monitoring and analysis, greatly reduces the measurement and data processing time, and thus reduces the measurement cost.

[0029] Generally speaking, the present invention has significant advantages over traditional single-target servo total stations in terms of measurement efficiency, operation convenience, environmental adaptability, and intelligent data processing. Especially in the scenario of multiple prisms, it shows obvious efficiency improvement and environmental adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention.

[0031] Figure 1 It is a schematic diagram of the composition of the servo total station module provided by an embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of the basic working process of the servo total station provided by an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of the process of the servo total station learning a prism provided by an embodiment of the present invention;

[0034] Figure 4 It is a schematic diagram of an image within a certain field of view of the servo total station provided by an embodiment of the present invention;

[0035] Figure 5 It is a schematic diagram of the target recognition process of the servo total station provided by an embodiment of the present invention;

[0036] Figure 6 It is a schematic diagram of the process of the servo total station monitoring the prism stage provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] As Figure 1 shown, the servo total station provided in this embodiment mainly includes a target recognition unit, a servo drive unit, a measurement unit, a main control unit, a communication unit, and other auxiliary units.

[0039] The target recognition unit is mainly used to identify and locate multiple prism targets, and its core functions include laser intensity adjustment, spot exposure control, and multi-prism image processing. Specifically, this unit further includes the following modules:

[0040] 1. Laser emission module: Its core task is to emit a laser beam to cover the entire field of view of the telescope. The emission light source is a laser diode. The light source is coupled to the emission mirror through an optical fiber and a coupling lens, and then the emission mirror emits the laser. By setting a specific emission angle, the laser beam evenly covers the reflection positions of multiple prisms, ensuring that each prism can receive the laser.

[0041] 2. Laser reception module: It includes a reception lens and an image sensor. After the laser returns from the reflection prism, the reception lens (objective lens) converges the received light onto the image sensor, and the image sensor is responsible for converting the received reflected light spot optical signal into an electrical signal to form a two-dimensional image.

[0042] 3. Processing and control module: It processes the received image signal and completes tasks such as image preprocessing, light spot segmentation, and feature extraction. This module also has the function of automatically adjusting the laser intensity, the reception gain of the sensor, and the exposure time to adapt to different distances and ambient light.

[0043] The servo drive unit is mainly used to drive the theodolite's sighting part to rotate horizontally and the telescope to rotate vertically to achieve automatic aiming at the target prism. The servo system adjusts the theodolite telescope to align with the prism center according to the angle data provided by the target recognition unit to achieve efficient automatic aiming. Specifically, this unit includes a horizontal drive module and a vertical drive module. The horizontal drive module is used to control the horizontal rotation of the instrument so that the telescope can align with prisms in different directions. The vertical drive module is used to control the vertical rotation of the telescope so that the instrument can align with prisms at different heights. The combination of horizontal and vertical rotations enables the instrument to automatically align and lock the position of each target prism.

[0044] The main control unit, as the core control module of the entire system, is mainly used to coordinate each module of the instrument, especially to control the transfer of the recognition data of the target recognition unit to the servo drive unit to achieve automatic alignment and measurement. The main control unit receives operation instructions from the user or external communication instructions, and through data processing and signal transmission, decomposes the operation into execution tasks for each module. The communication unit provides communication support between the internal part of the instrument and external devices, outputs the internal measurement data and device status to the external monitoring system, or receives external instructions for operation. The communication unit supports a variety of wired and wireless communication methods, including serial port, USB, Ethernet, optical fiber, WIFI, Bluetooth, etc. It enables the theodolite to be used as a sensor of an external system to achieve remote monitoring and data sharing.

[0045] The measuring unit includes a distance measuring unit and an angle measuring unit. The distance measuring unit is responsible for measuring the distance to the target prism after aligning with the alignment prism. It uses laser ranging technology, usually based on pulsed or phase measurement. The laser signal is emitted from the transmitting end, reflected by the prism and returned to the instrument. The distance measuring unit calculates the target distance based on the time or phase difference of the laser during transmission and return, and the measurement accuracy reaches the millimeter level. The angle measuring unit usually includes a precision angle encoder, which is used to measure the rotation angles of the total station in the horizontal and vertical directions (the angles of the horizontal axis and vertical axis of the total station). The high-precision angle measurement of the angle measuring unit is crucial for target aiming, enabling the total station to accurately locate the angle of the target.

[0046] The storage unit is used to provide a data storage function, supporting the temporary and long-term storage of measurement data. It includes the storage of all information from user input data, measurement process data to the final measurement results, providing support for data export and historical records.

[0047] In some embodiments, this servo total station further includes a graphic interaction unit. The graphic interaction unit includes input devices (such as keyboards, touch screens, etc.) and output devices (such as liquid crystal displays, indicator lights, speakers, etc.), which are used to provide an interaction interface between the user and the instrument. The user inputs operation instructions through this unit and can view the measurement results and system status in real time on the display screen. Through intuitive graphic display, it enables the user to operate the instrument more conveniently.

[0048] In some embodiments, this servo total station further includes a tilt compensation unit: which is used to collect the tilt angle of the vertical axis of the total station. When the instrument is tilted, it will automatically compensate for the angle to ensure that the measurement data can still maintain accuracy.

[0049] As Figure 2 shown, the basic working process of the servo total station is as follows: The user inputs measurement instructions through the graphic interaction unit or receives control signals from external devices through the external communication unit. After receiving the instructions, the main control unit starts the target recognition unit to identify and measure the angle of the prism, and determines the position of the prism in the instrument coordinate system. The servo drive unit rotates the instrument according to the measured angle data to align the telescope center with the target prism. The distance measuring unit measures the precise distance of the prism, the angle measuring unit records the angle information of the instrument, and the tilt compensation unit corrects the error caused by the instrument tilt. The data is transmitted to the external system through the external communication unit or stored in the storage unit to complete the data acquisition process.

[0050] The working process of the servo total station is divided into two main stages: the learning prism stage and the monitoring prism stage. As Figure 3 shown, in the learning prism stage, if in a certain area, such as Figure 4, five prisms, namely P1, P2, P3, P4, and P5, can be seen simultaneously from the instrument end. Since P3 is in the center, setting P3 as the target prism allows for seeing five prisms simultaneously, with the highest efficiency. The user first manually aims at P3 and clicks to measure. Then, the instrument runs the program according to Figure 5 until the characteristic information (such as the center coordinates) of all prisms is calculated. Figure 6 Figure Figure 6 is a schematic diagram of the process in the monitoring prism stage. The monitoring stage is similar to the learning stage, except that the input information is the information of the preferred prism and the information of other prisms within the area of the preferred prism. During the monitoring process, the system monitors the signal strength of each prism in real time. All measurement data is output to the external system in real time through the communication unit and stored in the storage unit to ensure subsequent analysis of the data.

[0051] In addition, during the monitoring process, the multi-target servo total station is more adaptable to the environment. In monitoring applications, especially in field applications, the received signal strength of the automatic target is often affected by the weather. Under extreme weather conditions such as rain and fog, the return light signal of the prism may even disappear completely. If there is only one prism in the field of view, the single-target servo total station and the multi-target servo total station will perform the same and both will display that no prism is found. If there are multiple prisms in the field of view, due to the influence of the weather, the signal of the current prism is very weak and the return light signal cannot be received at all, while there is a return light signal for another prism or several prisms in the field of view. At this time, according to the search strategy of the single-target servo total station, the instrument will search for the prism closest to the crosshair of the telescope, which will cause the instrument to export the measurement data of another prism as the measurement data of the currently to-be-measured prism, resulting in relatively large errors. For the same scenario, the total station in this embodiment will adopt a more intelligent strategy. Specifically, the total station in this embodiment will compare the prism data in the field of view with the previous data to find the disappeared prism and display that no prism is found in the field of view.

[0052] The most basic function of the processing control module of the target recognition unit is the ability to process multiple light spots in the image. The processing steps are as follows: S1, preprocess the image; S2, segment the prism light spots in the image; S3, extract the features of each prism light spot.

[0053] The image preprocessing in step S1 generally includes geometric operations, grayscale transformation, and filtering transformation of the image. The main purpose is to eliminate image recognition interference as much as possible, which is conducive to image feature extraction and recognition analysis. Image filtering mainly uses spatial domain filtering or frequency domain filtering to improve the quality of the image. The spatial domain refers to the visible image plane space to the naked eye, and spatial domain filtering performs convolution operations on the image. Specifically, when implementing, a sliding window of a fixed size is generally used to scan the image, sliding from left to right and from top to bottom one by one, calculating and updating the pixel value at the center of the window until all pixel values of the entire image are scanned and replaced, that is, the spatial domain filtering of the image is completed. Since spatial domain filtering directly acts on the image itself, different filtering methods have relatively strict requirements for the type of noise, and the best filtering method needs to be determined according to the characteristics of different noises. Noise is generally a high-frequency component and is difficult to distinguish through spatial domain operations. However, in the frequency domain, low-frequency components and high-frequency components can be easily separated through Fourier transform. Only by using a low-pass filter to retain the low-frequency components of the image and suppress the high-frequency components can the noise be removed, and then the image is inverse-transformed from the frequency domain back to the spatial domain, that is, the frequency domain filtering is completed.

[0054] Step S2 is mainly for image segmentation. The main purpose of image segmentation is to distinguish the prism target from the background. Since the prism is illuminated by the way of active light emission, the prism spot is relatively bright compared to the background. This is generally achieved by threshold segmentation. The basic principle of the threshold segmentation method is: by setting different feature thresholds, the image pixel points are divided into several classes of target regions and background regions with different gray levels. In terms of determining the optimal threshold, possible methods include the Otsu method, the maximum entropy method, etc.

[0055] Step S3 is mainly for feature extraction of the prism target. When there is only one prism in the image, only the features of one prism target need to be extracted at this time. Since the purpose of automatic target recognition is to align with the center of the prism, the coordinates of the center of the spot need to be extracted at this time. When there are multiple prism targets in the image. First, each prism target needs to be separated to obtain the regions of several prism targets, and feature extraction is performed on each region. In the case of interfering targets, it is also necessary to distinguish the targets and distinguish the prism targets from the interfering targets. After obtaining all the prism target regions in the image, the next step is to perform feature extraction on each prism target. In particular, the feature of the center of the prism must be extracted.

[0056] In the application of the total station, the distance range of the prism is about 1.5m to 3000m. According to the calculation formula of the spherical cap area, the total area of the laser at a distance R can be obtained as S1 = 2π * R 2*(1 - sin(90 - θ / 2)), where θ is the divergence angle of the light beam. Returning to the laser energy, let the energy emitted by the laser be P. Assuming there is no attenuation during the laser transmission and the area of the prism is A, then the energy received on the prism at a distance R is P1 = P * A / S1. Similarly, assuming total internal reflection of the prism, the total area of the light beam returning from the prism to the instrument end is S2 = 2π * (2R) 2 *(1 - sin(90 - θ2 / 2)), where R is still the distance between the prism and the instrument, and θ2 is the angle of the prism relative to the laser emission point. Assuming the total area of the instrument receiving end is B, then the energy received by the instrument is P2 = P1 * B / S2 = P * A / S1 * B / S2. It can be seen from here that the reflection ability of the prism is inversely proportional to the fourth power of the distance. In this case, for the same system, due to different distances, the intensity of the energy will vary by many times. Coupled with the attenuation of the laser energy caused by the atmosphere, and this attenuation may vary with different weather conditions. Therefore, for an automatic target recognition system, due to changes in distance and environment, the received energy changes greatly. So, in order to achieve the clearest edge of the prism spot, it is necessary to automatically adjust the receiving gains of the laser and the receiver according to different situations.

[0057] When the system receives a single prism spot, the adjustment is relatively simple, which is to adjust according to the edge clarity of the prism spot under different system gains. At the same time, due to the jitter of the atmosphere, it is necessary to adjust the gain to make the spot relatively stable at this time. Or perform filtering on a single image, or screen out unstable images from multiple consecutive images. Ensure that the data is relatively stable or close to the real result when performing feature extraction later.

[0058] When the system receives multiple prism spots, the adjustment is relatively more complex. One strategy is to adjust the system gain for each prism according to the spots in the image. Another strategy is to group the prisms. After obtaining the first image with the default gain, group the spots with a small difference from the ideal value (assuming the empirical value is 10%) into one group, and group the spots with a large difference from the ideal value into another group. First, perform feature extraction on the targets with appropriate gain, and calculate the central positions of all targets. Then process the target group with unreasonable gain. First, select a target, select an appropriate gain value for the target, and at the same time select the relevant group. Repeat the above process until all targets are traversed.

[0059] In terms of interfaces, both the input and output are data containing several prism targets. Each target may include the type of the prism, the prism constant, distance, angle, or coordinates in the total station coordinate system. On traditional servo total stations, the input and output interfaces are for single-target data. During the monitoring phase, if a traditional single-target servo total station is used, the user needs to learn each point, measure the distance, angle, or coordinate information of this target, and at the same time, the user designates or the system automatically assigns an ID to this point. When the servo total station in this embodiment faces the situation of only a single prism in the field of view, the working process is the same as that of an ordinary single-target servo total station. When there are multiple prisms in the field of view, in addition to providing the working mode of a single-target servo total station, another multi-target fast mode is also provided. Specifically, when multiple prisms appear in the field of view, the multi-target servo total station will output the coordinates of all prisms in the field of view or the angles of multiple prisms within the range set by the user. The advantage of this is that it can save time. The multi-target servo total station changes the ATR (Automatic Target Recognition) search in the process from N times to 1 time, and changes the N - 1 times of manually aiming at the prism to N - 1 times of automatically rotating to the prism target. The time saved has great advantages in projects with more prisms. What was mentioned above is that time can be saved during the prism learning process. Similarly, during the monitoring process, the angles of all prisms in the field of view can also be obtained through one ATR. The ATR search time can also be saved by N - 1 times.

[0060] In summary, the multi-target recognition process of the servo total station includes steps such as laser coverage, optical signal reception, image preprocessing, spot segmentation, multi-target feature extraction, and data output. After multiple gain adjustments, angle recognition, and signal monitoring, it realizes the efficient measurement and monitoring of multiple prisms. Through the above steps, the servo total station not only realizes multi-target recognition and high-precision measurement, but also can adapt to various environments, ensuring the stability and reliability of data. These functions make it have high efficiency, strong adaptability, and precision in multi-target measurement scenarios, and are especially suitable for large-scale, multi-prism monitoring projects.

[0061] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other changes in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of each embodiment of the present application.

Claims

1. A servo total station, characterized in that, It includes a target recognition unit, a servo drive unit, a measurement unit, a main control unit, a communication unit, and a storage unit; The target recognition unit is used to identify and locate multiple prism targets. The target recognition unit includes a laser emission module, a laser reception module, and a processing and control module. The laser emission module is used to emit a laser beam covering the entire field of view. The laser reception module is used to receive the reflected light and form an image. The processing and control module is used to process the image to obtain the position information of each prism target: The processing and control module of the target recognition unit first preprocesses the image to ensure the contrast and clarity of the prism light spot, and then distinguishes the light spots of each prism from the image background through threshold segmentation to form independent light spots. Finally, it obtains and saves the prism information including the center coordinates of each light spot; The processing and control module of the target recognition unit automatically adjusts the laser intensity and the reception gain of the image sensor according to the actual situation: When multiple prism reflection light spots are received, after obtaining the first image with the default gain first, the light spots are divided into two groups according to the difference between the light spots and the ideal value. First, feature extraction is performed on the group with appropriate gain to calculate the center positions of the prism light spots. For the group with inappropriate gain, first select a light spot from it, set an appropriate gain value for it and perform feature extraction to obtain the center position of the light spot, and then perform regrouping processing on the other light spots in this group under this gain value; Repeat the above process until all light spots are traversed. The servo drive unit is used to drive the theodolite aiming part to rotate in the horizontal direction and the theodolite telescope to rotate in the vertical direction according to the position information of the prism target provided by the target recognition unit to achieve aiming at the target prism; The measurement unit includes a distance measurement unit and an angle measurement unit. The distance measurement unit is used to measure the distance to the target prism after aligning with the prism, and the angle measurement unit is used to measure the angles of the horizontal axis and the vertical axis of the theodolite; The main control unit is used to receive the operation instructions of the user or external communication instructions, and decompose the operation instructions or communication instructions into the execution tasks of each unit module to achieve automatic alignment and measurement of the prism target; The communication unit is used to provide communication support between the inside of the theodolite and external devices, output the internal measurement data and device status to the external monitoring system, or receive external communication instructions; The storage unit is used to provide a data storage function, supporting the temporary storage and long-term storage of measurement data.

2. The servo total station according to claim 1, wherein The laser reception module in the target recognition unit includes a receiving lens and a photoelectric sensor. The receiving lens converges the reflected light onto the image sensor, and the image sensor converts the received reflected light into an electrical signal to form an image.

3. The servo total station according to claim 2, characterized in that, The processing and control module in the target recognition unit is also used to automatically adjust the intensity of laser emission, the reception gain of the image sensor, and the exposure time.

4. A servo total station according to claim 1, characterized in that, The theodolite also includes a graphic interaction unit. The graphic interaction unit includes an input device and an output device, and is used to provide an interaction interface between the user and the instrument. The user inputs operation instructions through this unit and views the measurement results and system status in real time.

5. A servo total station according to claim 1, characterized in that, The total station further includes an inclination compensation unit, which is used to collect the vertical axis inclination angle of the total station and automatically compensate the angle when the total station is inclined.

6. A servo total station according to claim 1, characterized in that, When the total station inputs and outputs, it simultaneously includes data of multiple prism targets, and the data includes prism type, constant, distance, angle, and the coordinates of the prism in the total station coordinate system.

7. A method for identifying a multi-prism based on the total station according to any one of claims 1 to 6, characterized in that, It includes a learning prism stage and a monitoring prism stage; Learning prism stage: First, manually aim at the prism located in the middle position of the field of view, and this position is recorded as the preferred position; then the laser emission module projects the laser into the telescope field of view so that the laser covers all prism positions; the laser reception module captures the light beams reflected by each prism, and converts the optical signal into an image through the image sensor; the processing and control module of the target recognition unit first preprocesses the image to ensure the contrast and clarity of the prism light spot, and then distinguishes the light spots of each prism from the image background through threshold segmentation to form independent light spots; finally, obtain and save the prism information including the center coordinates of each light spot. Monitoring prism stage: First, align with the preferred position through the servo drive unit, then obtain the position information of all prisms in the field of view through the target recognition unit and compare it with the prism information saved in the learning prism stage. If all the prisms in the learning prism stage exist, then align with each prism in turn through the servo drive unit and measure the distance of the prism through the ranging unit, otherwise output prism loss information.

8. The multi-prism recognition method according to claim 7, wherein The preprocessing performed by the processing and control module on the image includes spatial domain filtering and frequency domain filtering, and the threshold segmentation adopts the Otsu method or the maximum entropy method.

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