Determining internal calibration reference for total station

Abstract

The inventive concept relates to a total station (10), a method (70) for calibrating a total station, and a method (60) for determining an internal calibration reference for a total station. The method (60) comprises: determining (S600) an alignment error of an optical axis (1030, 1032, 1034) of a reference measurement channel relative to an aiming axis (150) of the total station (10), wherein the reference measurement channel is a measurement channel (1022) comprising a light source or a measurement channel (1020, 1024) comprising an image sensor; rotating (S602) an aiming axis (150) of the total station (10) about a rotation point to a predetermined position in which a light beam emitted from the light source exits the central unit (100) via an objective lens (1000) of the central unit (100) and enters the central unit (100) via the objective lens (1000) after being reflected at a reflective optical element (112) fixedly coupled to the collimator (110) so as to propagate towards the image sensor; emitting (S604) a light beam from the light source; capturing (S606) an image with an image sensor; identifying (S608) a position of the light beam in the image; and determining (S610) an internal calibration reference for the total station (10) based on the determined alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel and the identified position of the light beam in the image.

Description

Technical Field

[0001] The present invention relates to a total station, a method for determining the internal calibration reference of the total station, and a calibration method for the total station. Background Technology

[0002] Land mapping is a technique for measuring and mapping the physical characteristics of an environment, such as land or topography. This technique is commonly used in land development, construction planning, and infrastructure projects. Land mapping typically involves using specialized equipment such as total stations to determine detailed environmental information, such as the location of geographic points and the distances and angles between these points.

[0003] A total station is a device that typically integrates an electronic distance measuring unit (EDM unit) with a movable central unit (telescope) that rotates about at least two axes (typically trunnions (or elevation axes) and an azimuth axis). The central unit is typically mounted on a collimator to rotate about a first axis (e.g., trunnions), which is in turn mounted on a base to rotate about a second axis (e.g., the azimuth axis) that intersects (e.g., is orthogonal) to the first axis, allowing the total station's aiming axis to rotate about a point of rotation (typically corresponding to the intersection of the first and second axes). In use, the total station is typically configured such that the first axis is oriented in the horizontal plane and the second axis is oriented in the vertical direction. Therefore, the total station's aiming axis is defined as the axis of the central unit orthogonal to the first axis, i.e., the axis about which the central unit can rotate relative to the collimator. The aiming axis is also the axis along which measurements are performed using the central unit through one or more of the central unit's various measuring devices (e.g., using an EDM unit).

[0004] Ideally, the optical axes of these devices (or measuring channels) should be aligned with the aiming axis. However, this may not always be the case due to mechanical defects, such as the first and second axes not being orthogonal, or the total station's aiming axis not being orthogonal to the first axis. This can also change over time due to environmental influences such as temperature variations, mechanical shocks, etc. Therefore, it is necessary not only to calibrate the total station in the factory but also in the field to identify and, if possible, compensate for any alignment errors between the aiming axis and the optical axes associated with the multiple measuring devices in the central unit.

[0005] One technique for calibrating a total station involves repeated measurements of a target using different faces (e.g., face 1 and face 2). Any discrepancy between the measurements of face 1 and face 2 indicates an alignment error between the total station's aiming axis and the optical axis associated with the measuring device used for the repeated measurements. However, this technique can be time-consuming because multiple measurements are required to calibrate the total station (e.g., the total station may include multiple optical axes). Furthermore, this technique requires the existence of one or more suitable targets that can be used for measurements of face 1 and face 2. Therefore, there is a need in the art for improvements. Summary of the Invention

[0006] In view of the above, one object of the present invention is to provide a method for determining internal calibration benchmarks, which allows for the calibration of total stations in a more efficient and / or more time-saving manner.

[0007] Another objective is to provide a method for determining internal calibration benchmarks that allows total stations to be calibrated without the need for external targets.

[0008] Another objective is to provide a total station capable of determining an internal reference, which allows the total station to calibrate its aiming axis and the optical axis associated with the measurement channel efficiently, for example, in a more time-efficient manner.

[0009] Another objective is to provide a total station capable of determining an internal reference, which allows the total station to calibrate its aiming axis and the optical axis associated with the measurement channel without using an external target.

[0010] Another objective is to at least partially mitigate, alleviate, or eliminate one or more of the aforementioned defects and disadvantages in the art (alone or in any combination) and to at least address the aforementioned problems.

[0011] According to a first aspect, a method for determining an internal calibration reference for a total station is provided. The total station includes a central unit mounted on a collimator for rotation about a first axis, wherein the collimator is mounted on a base of the total station for rotation about a second axis orthogonal to the first axis, thereby allowing the aiming axis of the total station to rotate about a point of rotation. The central unit includes a plurality of measurement channels, each measurement channel having an optical axis, wherein at least one of the plurality of measurement channels includes a light source, and wherein at least one of the plurality of measurement channels includes an image sensor. The method includes: determining the alignment error of the optical axis of a reference measurement channel relative to the aiming axis of the total station, wherein the reference measurement channel is a measurement channel including the light source or a measurement channel including the image sensor; rotating the aiming axis of the total station about the rotation point to a predetermined position, at which a light beam emitted from the light source exits the central unit via an objective lens of the central unit, and after reflection at a reflective optical element fixedly connected to the collimator, enters the central unit via the objective lens to propagate toward the image sensor; emitting the light beam from the light source; capturing an image with the image sensor; identifying the position of the light beam in the image; and determining the internal calibration reference of the total station based on the determined alignment error of the optical axis of the reference measurement channel and the identified position of the light beam in the image.

[0012] In the context of this invention, the term "fixed connection" should be interpreted as one entity being substantially stationary relative to another. Therefore, the phrase "reflective optical element fixedly connected to the aiming device" should be interpreted as a reflective optical element being substantially stationary relative to the aiming device, possibly having one or two degrees of freedom in a plane parallel to the surface of the optical reflective element. For example, the reflective optical element can be attached to the aiming device using fastening devices (e.g., adhesives and / or spring clips pressed against a post). Alternatively, the reflective optical element can be a polished surface of the aiming device. Alternatively, the reflective optical element can be enclosed in and / or formed part of the aiming device, but retains certain degrees of freedom of movement (controlled and / or uncontrolled) in a predetermined plane such that the normal vector of the predetermined plane is fixed relative to the aiming device. Therefore, in this case, the term "reflective optical element fixedly connected to the aiming device" can be interpreted as a reflective optical element forming part of the aiming device. Furthermore, the reflective optical element can be mounted on a mechanical actuator, and the direction of the normal of the reflective surface of the reflective optical element relative to the aiming device can be monitored by one or more sensors. The actuator can be piezoelectric. The one or more sensors may be capacitive sensors and / or differential sensors. The one or more sensors may be connected in a feedback loop to ensure that the normal of the reflective surface of the reflective optical element is fixed relative to the alidade.

[0013] The present invention establishes an internal calibration reference that allows the total station to be calibrated without the use of an external calibration reference (e.g., an external target). In other words, the external calibration reference used to determine the alignment error of the optical axis of the reference measurement channel relative to the aiming axis of the total station is transferred to the internal calibration reference, and the external calibration reference is no longer needed when calibrating the total station. Therefore, a more efficient and time-saving method for calibrating a total station is achieved.

[0014] Reflective optical elements can be mirrors configured to reflect light emitted by a light source.

[0015] One related advantage is that, in particular, the amount of reflected light can be increased compared to using a polished surface.

[0016] Another related advantage is that the reflective surface can be flatter. This, in turn, reduces the influence of reflective optics on the profile of the reflected beam.

[0017] Another related advantage is that reflective optical elements can be manufactured using conventional processes.

[0018] Another related advantage is that a reflector can be added to an existing total station, thereby enabling the determination of an internal calibration reference according to the present invention.

[0019] When the total station's aiming axis is in a predetermined position, the angle of incidence of the light beam at the reflecting optics can be smaller than the angle corresponding to the field of view associated with the image sensor. In other words, the angle of incidence of the light beam ensures that, after reflection at the reflecting optics, the reflected beam is within the field of view of the image sensor.

[0020] Therefore, after the light beam is reflected at the reflective optical element, it can be allowed to enter the central unit through the objective lens, and thus be detected by the image sensor of the central unit.

[0021] One related advantage is that the central unit can be more compact because the reflection angle of the light reflected by the reflecting optics can be similar to the angle of incidence. Therefore, the beam reflected by the reflecting optics can be detected by the total station without the need for a dedicated measurement channel configured solely for this purpose.

[0022] Another related advantage is that the same measurement channel (i.e., the measurement channel including the image sensor) can be used to detect both reflected beams and light emanating from the scene (when the total station is in use). Therefore, a separate (or dedicated) measurement channel configured only to detect reflected beams may not be necessary.

[0023] A reference measurement channel can be associated with a measuring device, and determining the alignment error of the optical axis of the reference measurement channel can include: performing a first measurement in a first face of the total station using the measuring device associated with the reference measurement channel; performing a second measurement in a second face of the total station using the measuring device associated with the reference measurement channel, wherein, in the second face, the center unit can be rotated 180° about each of the first and second axes of the total station compared to the first face; and comparing the first and second measurements, thereby determining the alignment error of the optical axis of the reference measurement channel relative to the aiming axis of the total station.

[0024] A related advantage is that the reference measurement channel can be calibrated relative to an external calibration reference (e.g., an external target). This, in turn, allows the use of a reference measurement channel calibrated relative to an external calibration reference to determine the internal calibration reference. In other words, calibrating a total station using an internal calibration reference corresponds to calibrating a total station using an external calibration reference.

[0025] The reference measurement channel can be a measurement channel that includes an image sensor.

[0026] The measurement channel including the light source and the measurement channel including the image sensor can be different measurement channels.

[0027] The method may further include: determining the relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor.

[0028] One related advantage is that the relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor (if present) can be compensated, thereby allowing the internal calibration reference to correspond to the external calibration reference to a greater extent. In particular, it may be advantageous to identify (and possibly compensate for) this relative alignment error when the measurement channel including the light source and the measurement channel including the image sensor are different measurement channels.

[0029] Determining the relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor may include: rotating the aiming axis of the total station about a rotation point to another predetermined position, at which a light beam emitted from the light source can exit the central unit via the objective lens of the central unit, and after reflection at the retroreflection optics, can enter the central unit via the objective lens to propagate toward the image sensor; emitting a light beam from the light source; capturing another image with the image sensor; and determining the relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor based on the position of the light beam in the other image.

[0030] Traditionally, the alignment of a measurement channel relative to the aiming axis of a total station can be determined using an internal or external calibration reference (e.g., using the surface 1 and surface 2 techniques described above). This means that this process needs to be repeated for each of the multiple measurement channels in the central unit. Due to the large number of measurements required, calibrating each of the multiple measurement channels can be time-consuming. Therefore, using a retroreflector to determine the relative alignment error between the optical axes of different measurement channels allows for the calibration of only one measurement channel relative to the aiming axis of the total station, while the alignment of the other measurement channels can be determined relative to that single measurement channel.

[0031] Furthermore, when calibrating (or verifying) a total station using an internal calibration benchmark, the current relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor can be compared with a determined relative alignment error. This, in turn, allows the total station (or its user) to verify whether any changes have occurred in the alignment between these channels and subsequently take appropriate action.

[0032] According to a second aspect, a calibration method for a total station using an internal calibration reference determined according to the method of the first aspect is provided. The total station includes a central unit mounted on a collimator to rotate about a first axis, wherein the collimator is mounted on a base of the total station to rotate about a second axis orthogonal to the first axis, thereby allowing the aiming axis of the total station to rotate about a point of rotation. The central unit includes a plurality of measurement channels, each measurement channel having an optical axis, wherein at least one of the plurality of measurement channels includes a light source, and wherein at least one of the plurality of measurement channels includes an image sensor. The calibration method includes: rotating the aiming axis of the total station around the rotation point to a predetermined position; determining an internal calibration reference at the predetermined position; and at the predetermined position, a light beam emitted from the light source exits the central unit via the objective lens of the central unit, and after reflection at a reflecting optical element, enters the central unit via the objective lens to propagate toward the image sensor; emitting the light beam from the light source; capturing an image with the image sensor; identifying the position of the light beam in the image; and comparing the identified position of the light beam in the image with the internal calibration standard to determine the alignment error of the optical axis of the reference measurement channel relative to the aiming axis of the total station.

[0033] The calibration method may further include: determining a current relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor; and verifying the relative alignment between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor by comparing the current relative alignment error with a relative alignment error determined according to the method of the first aspect.

[0034] The calibration method may further include: comparing the alignment error of the determined optical axis of the reference measurement channel relative to the aiming axis of the total station with an allowable threshold error range; and when the determined alignment error is outside the allowable threshold error range: issuing an alarm to the user of the total station, informing them that the determined alignment error of the optical axis of the reference measurement channel relative to the aiming axis of the total station is outside the allowable threshold error range.

[0035] The features described in the first aspect also apply to this second aspect when applicable. To avoid unnecessary repetition, please refer to the above.

[0036] According to a third aspect, a total station is provided. The total station includes: a central unit comprising a plurality of measurement channels, each measurement channel having an optical axis, wherein at least one of the plurality of measurement channels includes a light source, and wherein at least one of the plurality of measurement channels includes an image sensor; a collimator, the central unit mounted on the collimator for rotation about a first axis; a base, the collimator mounted on the base for rotation about a second axis orthogonal to the first axis, whereby the aiming axis of the total station can rotate about a point of rotation; a reflecting optical element fixedly connected to the collimator; and circuitry configured to perform: an alignment error determination function, the alignment error determination function being configured to determine an alignment error of the optical axis of a reference measurement channel relative to the aiming axis of the total station, wherein the reference measurement channel is either a measurement channel including the light source or a measurement channel including the image sensor; The system includes the following functions: a rotation function configured to rotate the aiming axis of the total station around a rotation point to a predetermined position, whereby a light beam emitted from the light source exits the central unit via the objective lens of the central unit, is reflected at the reflecting optical element, and then enters the central unit via the objective lens to propagate toward the image sensor; a light source control function configured to control the light source to emit the light beam; an image sensor control function configured to control the image sensor to capture an image; a position recognition function configured to recognize the position of the light beam in the image; and an internal calibration reference determination function configured to determine the internal calibration reference of the total station based on the alignment error of the optical axis of the determined reference measurement channel and the recognized position of the light beam in the image.

[0037] The reflective optical element may be a mirror configured to reflect the light emitted by the light source.

[0038] When the aiming axis of the total station is in the predetermined position, the incident angle of the light beam at the reflecting optical element can be smaller than the angle corresponding to the field of view associated with the image sensor.

[0039] A reference measurement channel can be associated with a measuring device, and wherein an alignment error determination function can be configured to determine the alignment error of the optical axis of the reference measurement channel relative to the aiming axis of the total station by being configured to perform the following operations: performing a first measurement in a first face of the total station using the measuring device associated with the reference measurement channel; rotating the center unit about a rotation point to a second face of the total station, wherein, in the second face, the center unit can be rotated 180° about each of the first and second axes of the total station compared to the first face; performing a second measurement in the second face of the total station using the measuring device associated with the reference measurement channel; and comparing the first and second measurements, thereby determining the alignment error of the optical axis of the reference measurement channel relative to the aiming axis of the total station.

[0040] The reference measurement channel can be a measurement channel that includes an image sensor.

[0041] The circuit can also be configured to perform a calibration function, which is configured to: rotate the aiming axis of the total station around a rotation point to a predetermined position; control the light source to emit a beam; control the image sensor to capture a second image; identify the position of the beam in the second image; and compare the identified position of the beam in the image with an internal calibration reference to determine the alignment error of the optical axis of the reference measurement channel relative to the aiming axis of the total station.

[0042] The measurement channel including the light source and the measurement channel including the image sensor can be different measurement channels.

[0043] The circuit can also be configured to perform a relative alignment error determination function, which is configured to determine the relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor.

[0044] The total station may further include: a retroreflective optics element; and wherein the relative alignment error determination function can be configured to determine the relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor by being configured to perform the following operations: rotating the aiming axis of the total station about a rotation point to another predetermined position, at which a light beam emitted from the light source can exit the central unit via the objective lens of the central unit and, after reflection at the retroreflective optics element, can enter the central unit via the objective lens to propagate toward the image sensor; controlling the light source to emit the light beam; controlling the image sensor to capture another image; and determining the relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor based on the position of the light beam in the other image.

[0045] The circuit can also be configured to perform a relative alignment verification function, which is configured to: determine the current relative alignment error between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor, and verify the relative alignment between the optical axis of the measurement channel including the light source and the optical axis of the measurement channel including the image sensor by comparing the current relative alignment error with the relative alignment error determined by the relative alignment error determination function.

[0046] The features of the first and / or second aspects described above also apply to this third aspect where applicable. To avoid unnecessary repetition, please refer to the foregoing.

[0047] Other features and advantages of the inventive concept will become apparent when examined in conjunction with the appended claims and the following description. Those skilled in the art will recognize that different features of the inventive concept can be combined to form variations other than those described below, without departing from the scope of the inventive concept. Attached Figure Description

[0048] Various aspects of the inventive concept, including its specific features and advantages, will be readily understood from the following detailed description and accompanying drawings, wherein: Figure 1 The total station is shown.

[0049] Figure 2 This is a schematic diagram of the circuit.

[0050] Figure 3 The interior of the central unit of the total station is shown.

[0051] Figure 4 Another view of the total station is shown.

[0052] Figure 5 A total station including retroreflective optics is shown.

[0053] Figure 6 This is a block diagram of a method for determining the internal calibration reference of a total station.

[0054] Figure 7 It is used according to Figure 6 The diagram shows a block diagram of a total station calibration method based on an internal calibration benchmark.

[0055] Figure 8 This is a schematic diagram of the cross-section of the aiming device. Detailed Implementation

[0056] The inventive concept will now be described more fully below with reference to the accompanying drawings, in which presently preferred variations of the inventive concept are shown and discussed. However, the inventive concept can be implemented in many different forms and should not be construed as being limited to the variations described herein; rather, these variations are provided for thoroughness and completeness, and to fully convey the scope of the inventive concept to those skilled in the art. As shown, features may be enlarged for illustrative purposes, and thus these features may be provided to illustrate the general structure of variations of the inventive concept. Throughout the specification, the same reference numerals refer to the same elements.

[0057] Figure 1 A total station 10 is shown. The total station 10 can be configured to map a scene (e.g., the environment or terrain near the total station) and measure distances to points within the scene. Furthermore, the total station 10 can be configured to determine angles between points in the scene. Figure 1 As can be seen from the example, the total station 10 includes a central unit 100, a sight 110, and a base 120.

[0058] The central unit 100 is mounted on the aiming device 110 to rotate about a first axis 130. When the total station 10 is in use, the first axis 130 can be parallel to the horizontal plane. The first axis 130 can be a trunnion. The aiming device 110 is mounted on the base 120 to rotate about a second axis 140 orthogonal to the first axis 130. Therefore, the aiming axis 150 of the total station 10 can rotate around the point of rotation ( Figure 1 (Not shown in the image) rotates. The aiming axis 150 may be referred to in the art as the "collimation axis". The aiming axis 150 may be orthogonal to the first axis 130. The rotation point may be defined by the first axis 130 and the second axis 140. The rotation point may be defined by the intersection of the first axis 130 and the second axis 140. The total station 10 may also include one or more motors (…). Figure 1 (not shown in the image), which is configured to rotate the aiming axis 150 of the total station 10 around the rotation point.

[0059] The total station 10 also includes circuitry 160. Although Figure 1 While circuit 160 is not explicitly shown, it should be understood that circuit 160 may be included in one or more of the central unit 100, the aiming device 110, and the base 120. It should also be understood that circuit 160 may be included in the external unit (…). Figure 1 (Not shown in the diagram), for example, in a handheld unit configured to control the total station 10. This handheld unit can also be configured to display measurement results determined by the total station 10. Circuit 160 in... Figure 2As shown in the diagram. Circuit 160 is configured to perform alignment error determination function 1600, rotation function 1602, light source control function 1604, image sensor control function 1606, position recognition function 1608, and internal calibration reference determination function 1610. Circuit 160 can also be configured to perform one or more of calibration function 1612, relative alignment error determination function 1614, and relative alignment verification function 1616. Figure 2 As shown in the example, circuit 160 may include one or more of a memory 162, a processing unit 164, a transceiver 166, and a data bus 168. The memory 162, processing unit 164, and transceiver 166 may communicate via the data bus 168. The processing unit 164 may include a central processing unit (CPU) and / or a graphics processing unit (GPU). Transceiver 166 may be configured to communicate with external devices. For example, transceiver 166 may be configured to communicate with a server, a computer peripheral device (e.g., external memory), etc. The external device may be a local device or a remote device (e.g., a cloud server). As another example, if circuit 160 is included in an external unit (e.g., a handheld unit), circuit 160 may communicate with and control the total station 10 via transceiver 166. Transceiver 166 may be configured to communicate with external devices via an external network (e.g., a local area network, the Internet, etc.). Transceiver 166 may be configured for wireless and / or wired communication. Suitable technologies for wireless communication are known to those skilled in the art. Some non-limiting examples include Wi-Fi, Bluetooth, and Near Field Communication (NFC). Suitable technologies for wired communication are known to those skilled in the art. Some non-limiting examples include USB, Ethernet, and FireWire.

[0060] Memory 162 may be a non-transitory computer-readable storage medium. Memory 162 may be random access memory. Memory 162 may be non-volatile memory. For example... Figure 2As shown in the example, memory 162 may store program code portions 1600, 1602, 1604, 1606, 1608, 1610, 1612, 1614, and 1616 corresponding to one or more functions. Program code portions 1600, 1602, 1604, 1606, 1608, 1610, 1612, 1614, and 1616 may be executable by processing unit 164, thereby enabling processing unit 164 to perform these functions. Therefore, when reference is made to circuit 160 being configured to perform a specific function, processing unit 164 may execute program code portions 1600, 1602, 1604, 1606, 1608, 1610, 1612, 1614, 1616, and 1618 corresponding to a specific function that may be stored in memory 162. However, it should be understood that one or more functions of circuit 160 may be implemented in hardware and / or in an application-specific integrated circuit (ASIC). For example, one or more functions can be implemented using a field-programmable gate array (FPGA). In other words, one or more functions of circuit 160 can be implemented in hardware or software, or a combination of both.

[0061] like Figure 1 As further shown, the central unit 100 includes an objective lens 1000. The objective lens 1000 may be a front lens. Figure 3 An example of the interior of the central unit 100 is shown. For example... Figure 3 As can be seen from the example, the central unit 100 may also include an eyepiece 1002. The objective lens 1000 and the eyepiece 1002 can be arranged such that the user of the total station 10 can view the scene to be measured through the eyepiece 1002. Specifically, the eyepiece 1002 may include a crosshair. The crosshair can be used to facilitate aiming. In other words, the user of the total station 10 can use the crosshair to aim the total station 10 at an object. Figure 3 Furthermore, the central unit 100 includes multiple measurement channels 102. Each measurement channel 1020, 1022, and 1024 can communicate with the environment surrounding the central unit 100 via the objective lens 1000 of the central unit 100. Each measurement channel 1020, 1022, and 1024 has optical axes 1030, 1032, and 1034, respectively. Figure 3 As can be seen from the examples, the optical axes 1030, 1032, and 1034 of measurement channels 1020, 1022, and 1024 can be redirected using optical components 1040, 1042, and 1044. For example, as... Figure 3 As shown in the example, the optical axes 1030, 1032, and 1034 of measurement channels 1020, 1022, and 1024 can preferably be redirected so that they partially overlap. For example... Figure 3As shown in the example, the optical axes 1030, 1032, and 1034 of the measurement channels 1020, 1022, and 1024 can overlap at least in the sections of the optical axes 1030, 1032, and 1034 near the objective lens 1000 (e.g., in the final sections of the optical axes 1030, 1032, and 1034 passing through the objective lens 1000). Even more preferably, one or more of the optical axes 1030, 1032, and 1034 of the measurement channels 1020, 1022, and 1024 can be redirected such that they overlap with the central axis 1036 of the central unit 100. The optical axis of the objective lens 1000 of the central unit 100 can be aligned with the central axis 1036 in the central unit 100. Optical components 1040, 1042, and 1044 can be configured to partially reflect and partially transmit light. Optical components 1040, 1042, and 1044 can be beam splitters. Optical components 1040, 1042, and 1044 may include a first optical component 1040, a second optical component 1042, and a third optical component 1044. Each optical component 1040, 1042, and 1044 may be configured to transmit light with wavelengths within a corresponding wavelength range and reflect light with wavelengths outside that corresponding wavelength range. At least one of the plurality of measurement channels 102 includes a light source. The light source may be a laser. Figure 3 As shown in the example, the light source can form part of a measurement device 1052 associated with measurement channel 1022. Measurement device 1052 can be an electronic ranging (EDM) unit. The EDM unit can be configured to measure distances to objects in the scene (e.g., external targets). The light source and / or EDM unit can include beamforming optics ( Figure 3 (Not shown in the image). A beam-forming optics device can be configured to collimate the beam emitted by the light source. The beam-forming optics device and the objective lens 1000 of the central unit 100 can be configured to collimate the beam. The beam can then be collimated. Therefore, the beam can be collimated within the central unit 100 and / or as it exits the central unit 100 via the objective lens 1000. At least one of the plurality of measurement channels 102, 1020, 1024, includes an image sensor. (As shown in the image) Figure 3As shown in the example, an image sensor may be included in measuring devices 1050 and 1054. Measuring devices 1050 and 1054 can be used to image a scene, for example, to locate external targets (e.g., mapping poles and / or entities on buildings (windows, towers, etc.)). Measuring devices 1050 and 1054 may be cameras. For example, central unit 100 may include a first camera and a second camera, each associated with a respective measuring channel 1020, 1024. Therefore, central unit 100 may include a first measuring device 1050, a second measuring device 1052, and a third measuring device 1054. The first measuring device 1050 and the third measuring device may each include an image sensor. For example, the first measuring device 1050 and / or the third measuring device 1054 may be cameras, and the second measuring device 1052 may be an EDM unit. Cameras 1050 and 1054 may include imaging optics (…). Figure 3 (Not shown in the image). The imaging optics can be configured to image an object at a certain distance (e.g., a distance greater than 0.5 meters) onto the image sensor. The imaging optics can be configured to image an object at infinity onto the image sensor. The imaging optics and the objective lens 1000 of the central unit 100 can be configured to image an object onto the image sensor. For example, the imaging optics and the objective lens 1000 of the central unit 100 can be configured to image an object at infinity onto the image sensor. Figure 3 As further illustrated in the example, the measurement channel 1022, which includes a light source, and the measurement channels 1020 and 1024, which include an image sensor, can be different measurement channels. Figure 3 It is evident that even though the measurement channel 1022, which includes the light source, and the measurement channels 1020 and 1024, which include the image sensor, may be different measurement channels, they may still share some components. For example, such as... Figure 3 As shown, multiple parts of the central axis 1036 of the central unit 100 can be shared among different measurement channels 1020, 1022, and 1024.

[0062] Different views of total station 10 Figure 4 As shown in [the image]. Figure 4 The image shows a simplified version of the interior of the central unit 100. (See image for reference.) Figure 4As can be seen, the total station also includes a reflecting optical element 112. The reflecting optical element 112 is fixedly connected to the aiming device 110. The reflecting optical element 112 can be securely connected to the aiming device 110. Here, "fixedly connected" should be understood as the reflecting optical element 112 being substantially stationary relative to the aiming device 110. For this purpose, the reflecting optical element 112 can be attached to the aiming device 110 using fastening devices, such as clamping (e.g., using a spring), and / or by using adhesive. The reflecting optical element 112 can be clamped using a component of an elastic material (e.g., metal, rubber, plastic, etc.). Alternatively, the reflecting optical element 112 can form part of the aiming device 110, for example, as part of the housing of the aiming device 110. For example, the reflecting optical element 112 can be a polished surface of the housing of the aiming device 110. Therefore, the phrase "reflecting optical element fixedly connected to the aiming device" can be interpreted as the reflecting optical element 112 forming part of the aiming device 110. The reflecting optical element 112 can be a mirror configured to mirror the light emitted by a light source. The mirror can be a silver mirror. The mirror can be a dielectric mirror. The mirror can be a plane mirror.

[0063] However, problems arise when one or more of the optical axes 1030, 1032, and 1034 of the multiple measurement channels 102 are not aligned with the aiming axis 150 of the total station 10 (e.g., not parallel and / or overlapping). For example, optical axes 1030, 1032, and 1034 may not be aligned with the central axis 1036 of the central unit 100 and / or the aiming axis 150 of the total station 10. As another example, optical axes 1030, 1032, and 1034 may be aligned with the central axis 1036 of the central unit 100, while the central axis 1036 of the central unit 100 may not be aligned with the aiming axis 150 of the total station 10. If one or more of the optical axes 1030, 1032, and 1034 of the multiple measurement channels 102 are not aligned with the aiming axis 150 of the total station 10, the user of the total station may use the eyepiece 1002 of the center unit 100 to aim at an object in the scene, and the misaligned measurement channel may be aimed at a different object in the scene. Therefore, in this case, the distance and / or other attributes (such as angles) determined by the total station 10 may be inaccurate. To avoid such a problem, the optical axes 1030, 1032, and 1034 of the measurement channels 1020, 1022, and 1024 are generally aligned with the aiming axis 150 of the total station 10. For this purpose, the alignment error determination function 1600 is configured to determine the alignment error of the optical axes 1030, 1032, and 1034 of the reference measurement channels 1020, 1022, and 1024 relative to the aiming axis 150 of the total station 10. The reference measurement channel is measurement channel 1022 including a light source or measurement channels 1020, 1024 including an image sensor. The reference measurement channel can be associated with measurement devices 1050, 1052, 1054. The reference measurement channel can be measurement channel 1020, 1024 including an image sensor. The alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10 can be determined using an external reference point (e.g., a target outside the total station 10). Therefore, by determining the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel and the aiming axis 150 of the total station 10, any misalignment between them can be explained and / or corrected. Those skilled in the art will recognize that there are various different ways to determine the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10. For example, the alignment error determination function 1600 can be configured to determine the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10 by performing a first measurement in the first face of the total station 10 using measuring devices 1050, 1052, 1054 associated with the reference measurement channel. In the first face of the total station 10, an external reference point can be aimed, for example, by an eyepiece 1002 in the total station 10.In other words, the total station 10 can be arranged in the first plane to perform measurements of external reference points. The first measurement can be based on multiple individual measurements. For example, the first measurement can be the average of multiple individual measurements. It should be understood that the first measurement can be determined in different ways based on multiple individual measurements. For example, the first measurement can be one or more of the average, weighted average, harmonic average, median, etc. of multiple individual measurements. The alignment error determination function 1600 can also be configured to rotate the center unit 100 about a rotation point to the second plane of the total station 10. In the second plane, compared to the first plane, the center unit 100 can be rotated 180° about each of the first axis 130 and the second axis 140 of the total station. The alignment error determination function 1600 can also be configured to perform a second measurement in the second plane of the total station 10 using measuring devices 1050, 1052, 1054 associated with the reference measurement channel. The second measurement can be based on multiple individual measurements. For example, the second measurement can be determined in a manner similar to that described in conjunction with the first measurement. The alignment error determination function 1600 can also be configured to compare the first measurement and the second measurement, thereby determining the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channels relative to the aiming axis 150 of the total station 10. For example, when the reference measurement channels are measurement channels 1020, 1024 including an image sensor (i.e., the first and second measurements are images captured using an image sensor), the alignment error can be determined by comparing the positions of external reference points in the images corresponding to the first measurement and the second measurement. If the external reference points are in the same position in the images, the alignment error of the optical axes 1030, 1034 of the reference measurement channels relative to the aiming axis 150 may not exist. However, if a non-zero alignment error exists, the positions of the external reference points in the images may correspond to the aiming axis 150 of the total station 10. Therefore, by determining this alignment error, it can be interpreted and / or corrected. Although the reference measurement channels have been described above as measurement channels 1020 and 1024 including an image sensor, it should be understood that the reference measurement channel can be a measurement channel other than one including an image sensor. For example, the reference measurement channel can be measurement channel 1022 including a light source. In this case, the first and second measurements can be measurements performed using a measurement device 1052 associated with the measurement channel 1022. For example, the light source can form part of an EDM unit, in which case the first and second measurements can be distance measurements. Therefore, the difference between the first and second distance measurements can be used to determine the alignment error between the optical axis 1032 of the reference measurement channel and the aiming axis 150 of the total station 10.

[0064] As can be understood from the above, determining the alignment error of the reference measurement channel can be both time-consuming and cumbersome. For example, the process requires an external reference point and typically requires multiple separate measurements to correctly determine the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10.

[0065] To mitigate this deficiency, the present invention relates to determining an internal calibration reference that can be used to calibrate the total station 10 and / or verify its current alignment. For this purpose, the total station includes a reflecting optics element 112 used in determining the internal calibration reference. To determine the internal calibration reference, a rotation function 1602 is configured to rotate the aiming axis 150 of the total station 10 about a predetermined position, where a light beam emitted from the light source exits the central unit 100 via the objective lens 1000, is reflected at the reflecting optics element 112, and then enters the central unit 100 via the objective lens 1000 to propagate toward the image sensor. The rotation function 1602 can be configured to control motors (not shown) arranged to rotate the central unit 100 about a first axis 130 and / or a second axis 140. The predetermined position of the aiming axis 150 can be a predetermined direction of the aiming axis 150. The light beam can be emitted from a measuring device 1052 including a light source. After emission, the light beam can be reflected at a reflector 1062. After reflection at mirror 1062, the light beam can propagate toward the second optical element 1042. A portion of the light beam can be reflected by the second optical element 1042, and a portion of that reflected portion can be transmitted through the third optical element 1044. After being transmitted through the third optical element 1044, the light beam (or a portion of the light beam) can exit the central unit 100 via the objective lens 1000. After reflection at reflective optical element 112, the light beam can enter the central unit 100 via the objective lens 1000. A portion of the light beam can be reflected at the third optical element 1044 and then propagate toward the image sensor of the third measuring device 1054. Alternatively or additionally, a portion of the light beam can be transmitted through the third optical element 1044 and the second optical element 1042. After being transmitted through the second optical element 1042, the transmitted portion of the light beam can be reflected by the first optical element 1040 toward the image sensor of the first measuring device 1050.

[0066] When the aiming axis 150 of the total station 10 is in a predetermined position, the angle of incidence of the light beam at the reflecting optical element 112 can be smaller than the angle corresponding to the field of view associated with the image sensor. The field of view associated with the image sensor may be 1°. Therefore, when the aiming axis 150 of the total station 10 is in a predetermined position, the angle of incidence of the light beam at the reflecting optical element 112 can be less than 1°. Therefore, when the aiming axis 150 of the total station 10 is in a predetermined position, the light beam can be incident on the reflecting optical element 112 close to the normal. Furthermore, at the predetermined position, the aiming axis 150 of the total station 10 can be substantially parallel to the normal of the reflecting surface of the reflecting optical element 112. For example, when the aiming axis 150 is in the predetermined position, the aiming axis 150 can point towards the reflecting optical element 112 along the second axis 140.

[0067] The light source control function 1604 is configured to control the light source to emit a light beam. The light source control function 1604 can also be configured to control the second measuring device 1052. The image sensor control function 1606 is configured to control the image sensor to capture an image. The image sensor control function 1606 can also be configured to control the first measuring device 1050 and / or the third measuring device 1054. Therefore, when the aiming axis 150 of the total station 10 is in a predetermined position, the light source control function 1604 can control the light source to emit a light beam, and the image sensor control function 1606 can control the image sensor to capture an image. In the image, the light beam reflected at the reflecting optical element 112 can be visible. For this purpose, the light source control function 1604 can be configured to adjust the intensity of the light beam. For example, the intensity of the light beam can be adjustable. Therefore, the light source can be an adjustable light source. For example, in the case where the light source includes a light-emitting diode (LED), the intensity of the light emitted from the LED can be electrically adjustable. Additionally or alternatively, the light source control function 1604 can also be configured to control an attenuator configured to attenuate the light beam. Those skilled in the art will recognize suitable attenuators that can be used. For example, a neutral density filter can be used to attenuate the light beam. The light source control function 1604 can be configured to move one or more neutral density filters to attenuate the light beam. For example, the one or more neutral density filters can be mounted on a motorized stage (e.g., motorized wheels) that can be controlled by the light source control function 1604. Furthermore, the image sensor control function 1606 can be configured to adjust the exposure time associated with the image sensor. In other words, the image sensor control function 1606 can control the amount of time during which the image sensor actively measures (and possibly sums) the incident energy of the light beam. Therefore, depending on the intensity of the light beam, the amount of time during which the image sensor is exposed to the light beam so that it is visible in the image can be set. Furthermore, the image sensor control function 1606 can be configured to adjust the integration time of the image sensor. The position recognition function 1608 is configured to recognize the position of the light beam in the image. The position recognition function 1608 can be configured to automatically recognize the position of the light beam in the image. The recognized position can be determined based on pixels in the image that have color values ​​corresponding to the light beam. The identified location can be determined based on pixels in the image whose pixel values ​​(corresponding to intensity) fall within a certain range. The pixel value range represents the range of expected pixel values ​​the light beam might have in the image. For example, the identified location can be determined based on pixels whose pixel values ​​are close to or at the highest pixel value in the image. In other words, the identified location can be determined based on pixels whose pixel values ​​are the highest values ​​in the image. The location identification function 1608 can be configured to receive input from a user of the total station 10 and identify the location of the light beam in the image based on the input from the user of the total station 10.For example, an image can be displayed to a user (e.g., on a control device and / or the screen of the total station 10), and the user can select the position of the beam in the image. However, this can usually be done automatically as described above.

[0068] The internal calibration reference determination function 1610 is configured to determine the internal calibration reference of the total station 10 based on the alignment errors of the optical axes 1030, 1032, and 1034 of the determined reference measurement channel and the position of the identified beam in the image. If the alignment errors of the optical axes 1030, 1032, and 1034 of the determined reference measurement channel are found to be small (or even non-existent), the internal calibration reference can be the position of the identified beam in the image. In this case, "small" should be understood as the alignment error being small enough to be indistinguishable during the operation of the total station 10 (i.e., during measurement). If the alignment errors of the optical axes 1030, 1032, and 1034 of the determined reference measurement channel are large, the internal calibration reference can be determined by compensating for the position of the identified beam in the image with the alignment errors of the optical axes 1030, 1032, and 1034 of the determined reference measurement channel. In other words, the position of the identified beam in the image can be compensated so that the compensated position corresponds to the position where the beam would be positioned if the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10 is small (or even non-existent). In this case, "large" should be understood as a sufficiently large alignment error that can be noticed during normal operation of the total station 10 (i.e., during measurement). Therefore, an internal calibration reference is established, which allows the total station 10 to be calibrated (or its calibration verified) without the use of an external calibration reference (e.g., an external target). In other words, the external calibration reference used in determining the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10 is transferred to the internal calibration reference, and the external calibration reference may no longer be needed when calibrating the total station 10. Therefore, more efficient and time-saving calibration (or calibration verification) of the total station 10 is allowed.

[0069] Circuit 160 can also be configured to perform calibration function 1612. Calibration function 1612 can be configured to rotate the aiming axis 150 of the total station 10 about a rotation point to a predetermined position. This predetermined position can be the same position as when the internal calibration reference is determined. When the aiming axis 150 of the total station 10 is in the predetermined position, calibration function 1612 can also be configured to control the light source to emit a light beam and control the image sensor to capture a second image. This second image can be captured in the same manner as the image captured when the internal calibration reference is determined. Calibration function 1612 can be configured to control one or more of the first measuring device 1050, the second measuring device 1052, and the third measuring device 1054. Calibration function 1612 can also be configured to identify the position of the light beam in the second image and compare the identified position of the light beam in the image with the internal calibration reference to determine the alignment error of the optical axes 1030, 1032, 1034 of the reference measuring channel relative to the aiming axis 150 of the total station 10. In other words, the total station 10 can be calibrated without the need for an external calibration reference (e.g., an external target). It should also be understood that the calibration of the total station 10 that has already been performed can be verified. For this purpose, circuit 160 can also be configured to perform a calibration verification function 1618, which is configured to verify the alignment of the optical axes 1030, 1032, 1034 of the reference measurement channels relative to the aiming axis 150 of the total station 10. When the calibration verification function 1618 determines that the alignment error determined by the calibration function 1612 is outside the range of approved alignment error values, the calibration verification function 1618 can be configured to alert the user of the total station 10. For example, the user of the total station 10 can be alerted that the determined alignment error cannot be compensated and that a new calibration may be required using an external calibration reference (e.g., an external target). Furthermore, the user of the total station 10 can be alerted that the determined alignment error exists and can be compensated, thus potentially eliminating the need for a new calibration using an external calibration reference.

[0070] The alignment errors of the optical axes 1030, 1032, and 1034 of the reference channel have been discussed above, and the optical axes 1030, 1032, and 1034 of the other measurement channels 102 may also have alignment errors relative to the aiming axis 150 of the total station 10. Therefore, the relative alignment errors of the optical axes 1030, 1032, and 1034 of the other measurement channels relative to the reference measurement channel can be determined. In particular, the relative alignment error of the optical axis 1032 of the measurement channel 1022, which includes the light source, with the optical axes 1030 and 1034 of the measurement channels 1020 and 1024, which include the image sensor, can be advantageously determined. This is because one of these measurement channels may be the reference measurement channel, while another of these measurement channels is used in conjunction with the reference measurement channel to determine the internal calibration reference. Therefore, in the presence of relative alignment errors, this may affect the determination of the internal calibration reference, and thus potentially affect any calibration (or verification) performed using the internal calibration reference. One method will now be described for determining the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor.

[0071] Therefore, such as Figure 5 As shown, the total station 10 may also include a retroreflective optical element 114, and the circuit 160 may also be configured to perform a relative alignment error determination function 1614. The retroreflective optical element 114 may be configured to reflect light. In other words, the light beam reflected by the retroreflective optical element 114 may (after reflection) be parallel to the incident light beam. Figure 5 Several features are not shown in the diagram. For example, the aforementioned reflective optical element 112 is not visible. This is done for illustrative purposes only, and it should be understood that one or more of the excluded features (such as the reflective optical element 112) may actually be present. Figure 5 In the total station shown, it should also be understood that the reflecting optics 112 and the retroreflective optics 114 can be arranged in different positions (e.g., in the aiming device 110). Preferably, the reflecting optics 112 can be arranged such that the normal of the reflecting surface of the reflecting optics 112 is substantially parallel to the second axis 140, and the retroreflective optics 114 can be arranged such that the normal of the incident surface of the retroreflective optics 114 is angularly oriented with respect to the second axis 140. For example, the reflecting optics 112 and the retroreflective optics 114 can be arranged as follows: Figure 8 The arrangement is shown. Figure 8 A cross-section of a portion of the aiming device 110 is shown schematically. (As shown) Figure 8As can be seen from the example, the reflecting optical element 112 can be attached to the aiming device 112 using a spring clip 1120 and an O-ring 1122. The aiming device 112 may include a hole 1124, whereby when the aiming axis 150 is in a predetermined position (i.e., pointing towards the reflecting optical element 112), the light beam emitted from the objective lens 1000 of the central unit 100 (by the aiming axis 150) is directed to the aiming device 112. Figure 8 (The line 800 in the diagram indicates that the reflective optical element 112 can be reached. Furthermore, as...) Figure 8 As shown, the retroreflective optics 114 can be recessed into the aiming device 110. To allow a light beam (indicated by line 802) to reach the recessed retroreflective optics 114 when the aiming axis 150 is in another predetermined position (i.e., pointing towards the retroreflective optics 114), the aiming device 110 may include a recess 116 that allows the light beam to propagate to and be reflected back by the retroreflective optics 114. For reference, in Figure 8 The second axis 140 is shown in the figure.

[0072] The retroreflecting optical element 114 can be a retroreflector. The retroreflecting optical element 114 can be a corner prism. The retroreflecting optical element 114 can be used with the aiming device 110 (e.g., Figure 5 (As shown) or fixedly connected to the base 120. When the retroreflection optics 114 is fixedly connected to the base 120, the aiming device 110 may include a through-hole so that the light beam can reach the retroreflection optics 114. The relative alignment error determination function 1614 can be configured to determine the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor. The relative alignment error determination function 1614 can be configured to rotate the aiming axis 150 of the total station 10 about the rotation point to another predetermined position, at which the light beam emitted from the light source can exit the central unit 100 via the objective lens 1000 of the central unit 100, and after reflection at the retroreflection optics, can enter the central unit 100 via the objective lens 1000 to propagate toward the image sensor. Therefore, the retroreflection optics 114 can be arranged such that when the aiming axis 150 is in another predetermined position, the light beam emitted by the light source can be incident on the retroreflection optics 114. This other predetermined position of the aiming axis 150 can be another predetermined direction of the aiming axis 150. The relative alignment error determination function 1614 can also be configured to control the light source to emit the light beam and control the image sensor to capture another image. The relative alignment error determination function 1614 can be configured to control one or more of the first measuring device 1050, the second measuring device 1052, and the third measuring device 1054.

[0073] The relative alignment error determination function 1614 can also be configured to determine the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor, based on the position of the light beam in another image. Since the retroreflective optics 114 can reflect the light beam back to its light source, the reflected beam can propagate along the same optical path (albeit in the opposite direction) as the light beam after being emitted by the light source, and a portion of the reflected beam can propagate to the image sensor. The above description, in conjunction with the determination of the internal calibration reference, has explained how the light beam can reach the image sensor after entering the central unit 100 via the objective lens 100, and the same principle can be applied to this case. However, since the retroreflective optics 114 can be configured such that the incident beam and the reflected beam are parallel to each other, the reflected beam can be parallel to the optical axis 1032 of the measurement channel 1022 including the light source. Therefore, the reflected light beam can be used to correlate the optical axis 1032 of the measurement channel 1022 including the light source with the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor. Through this correlation, the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor can be determined. In particular, when the image sensor is included in a camera having imaging optics configured to image objects at infinity, a light beam propagating at an angle relative to the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor can be imaged at a point (e.g., a pixel or a group of pixels) on the image sensor. In other words, different positions on the image sensor can correspond to different angles of the light beam relative to the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor. Therefore, the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor can be determined based on the position of the light beam on the image sensor. It should also be understood that the relative alignment between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor can be verified. For this purpose, circuit 160 can be configured to perform a relative alignment verification function 1616. The relative alignment verification function 1616 can be configured to determine the current relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor. The current relative alignment error can be determined in the same manner as the previously described relative alignment error.The relative alignment verification function 1616 can also be configured to verify the relative alignment of the optical axis 1032 of the measurement channel 1022, including the light source, with the optical axes 1030, 1034 of the measurement channels 1020, 1024, including the image sensor, by comparing the current relative alignment error with the relative alignment error determined by the relative alignment error determination function 1614. For example, the position of the light beam on the image sensor when the current relative alignment error is determined can be compared with the position of the light beam in another image. Therefore, the difference between these positions may be related to the difference between the current relative alignment error and the relative alignment error. If the difference between these positions is outside the approved range (e.g., the difference is too large), the verification will fail, and the relative alignment verification function 1616 can be configured to alert the user of the total station 10 to this situation. If the difference between these positions is within the approved range, the verification will succeed, and the relative alignment verification function 1616 can be configured to alert the user of the total station to this situation.

[0074] Figure 6This is a block diagram of a method 60 for determining the internal calibration reference of a total station 10. The total station 10 includes a central unit 100 mounted on a collimator 110 to rotate about a first axis 130, wherein the collimator 110 is mounted on a base 120 of the total station 10 to rotate about a second axis 140 orthogonal to the first axis 130, thereby allowing the aiming axis 150 of the total station 10 to rotate about a point of rotation. The central unit 100 includes a plurality of measurement channels 102, each measurement channel 1020, 1022, 1024 having optical axes 1030, 1032, 1034. At least one of the plurality of measurement channels 1022 includes a light source, and at least one of the plurality of measurement channels 1020, 1024 includes an image sensor. Method 60 includes: determining the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel S600 relative to the aiming axis 150 of the total station 10, wherein the reference measurement channel is a measurement channel 1022 including a light source or measurement channels 1020, 1024 including an image sensor; rotating the aiming axis 150 of the total station 10 around a rotation point S602 to a predetermined position, at which the light beam emitted from the light source exits the central unit 100 via the objective lens 1000 of the central unit 100. The beam, after being reflected at the reflective optical element 112 fixedly connected to the aiming device 110, enters the central unit 100 via the objective lens 1000 and propagates toward the image sensor; the beam S604 is emitted from the light source; the image sensor captures the image S606; the position of the beam S608 in the image is identified; and the internal calibration reference of the total station 10 is determined based on the alignment error of the optical axes 1030, 1032, 1034 of the determined reference measurement channel and the identified position of the beam in the image. The reflective optical element 112 may be a mirror configured to reflect the light emitted by the light source. When the aiming axis 150 of the total station 10 is in a predetermined position, the incident angle of the beam at the reflective optical element 112 may be smaller than the angle corresponding to the field of view associated with the image sensor.The reference measurement channel can be associated with measuring devices 1050, 1052, and 1054, and determining the alignment error of the optical axes 1030, 1032, and 1034 of the reference measurement channel in S600 can include: performing a first measurement (S612) in a first face of the total station 10 using the measuring devices 1050, 1052, and 1054 associated with the reference measurement channel; performing a second measurement (S614) in a second face of the total station 10 using the measuring devices 1050, 1052, and 1054 associated with the reference measurement channel, wherein, in the second face, the center unit 100 can be rotated 180° around each of the first axis 130 and the second axis 140 of the total station 10 compared to the first face; and comparing the first and second measurements (S616), thereby determining the alignment error of the optical axes 1030, 1032, and 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10. The reference measurement channel can be a measurement channel 1022 that includes an image sensor. The measurement channel 1022 including the light source and the measurement channels 1020 and 1024 including the image sensor can be different measurement channels. Method 60 may further include: determining, in S618, the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030 and 1034 of the measurement channels 1020 and 1024 including the image sensor. Determining the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor in step S618 may include: rotating the aiming axis 150 of the total station 10 around the rotation point S620 to another predetermined position, whereby a light beam emitted from the light source can exit the central unit 100 via the objective lens 1000 and, after reflection at the retroreflection optical element 114, enter the central unit 100 via the objective lens 1000 to propagate toward the image sensor; emitting the light beam S622 from the light source; capturing another image S624 with the image sensor; and determining the relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor in step S626 based on the position of the light beam in the other image.

[0075] Figure 7 It is used according to Figure 6The diagram shows a block diagram of a calibration method 70 for a total station 10 with an internal calibration reference determined by method 60. The total station 10 includes a central unit 100 mounted on a collimator 110 to rotate about a first axis 130, wherein the collimator 110 is mounted on a base 120 of the total station 10 to rotate about a second axis 140 orthogonal to the first axis 130, thereby allowing the aiming axis 150 of the total station 10 to rotate about a point of rotation. The central unit 100 includes a plurality of measurement channels 102, each measurement channel 1020, 1022, 1024 having optical axes 1030, 1032, 1034. At least one of the plurality of measurement channels 1022 includes a light source, and at least one of the plurality of measurement channels 1020, 1024 includes an image sensor. The calibration method 70 includes: rotating the aiming axis 150 of the total station 10 around a rotation point S700 to a predetermined position, determining an internal calibration reference at the predetermined position, and having a light beam emitted from the light source exit the central unit 100 via the objective lens 1000 of the central unit 100, and after being reflected at the reflecting optical element 112, enter the central unit 100 via the objective lens 1000 to propagate toward the image sensor; emitting the light beam from the light source S702; capturing an image with the image sensor S704; identifying the position of the light beam in the image S706; and comparing the identified position of the light beam in the image with the internal calibration reference S708 to determine the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channel relative to the aiming axis 150 of the total station 10. Furthermore, by determining the alignment error of the optical axes 1030, 1032, 1034 of the reference measurement channels relative to the aiming axis 150 of the total station 10, the optical axes 1030, 1034 of the measurement channels 1022 including the light source or the measurement channels 1020, 1024 including the image sensor can be calibrated relative to the aiming axis 150 of the total station. The calibration method 70 may further include: determining, in S710, the current relative alignment error between the optical axis 1032 of the measurement channel 1022 including the light source and the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor; and calibrating the current relative alignment error by comparing it with the alignment error of the measurement channels 1022 including the light source with the alignment error of the measurement channels 1020, 1024 including the image sensor. Figure 6The relative alignment error determined by method 60 is compared to verify the relative alignment of the optical axis 1032 of the measurement channel 1022 including the light source with the optical axes 1030, 1034 of the measurement channels 1020, 1024 including the image sensor in step S712. Calibration method 70 may further include: comparing the alignment error of the determined reference measurement channels' optical axes 1030, 1032, 1034 relative to the aiming axis 150 of the total station 10 with an allowable threshold error range in step S714; and when the determined alignment error is outside the allowable threshold error range: issuing an alarm S716 to the user of the total station 10, informing them that the alignment error of the determined reference measurement channels' optical axes 1030, 1032, 1034 relative to the aiming axis 150 of the total station 10 is outside the allowable threshold error range.

[0076] Those skilled in the art will recognize that the inventive concept is by no means limited to the preferred variations described above. Rather, many modifications and variations are possible within the scope of the appended claims.

[0077] For example, the total station 10 has been described as having three measurement channels (i.e., measurement channels 1020, 1022, and 1024, which respectively include a light source and an image sensor). However, it should be understood that the total station 10 (i.e., the central unit 100) may include additional measurement channels.

[0078] Furthermore, by studying the accompanying drawings, description, and appended claims, those skilled in the art can understand and implement the disclosed variations when practicing the claimed invention.

Claims

1. A method (60) for determining an internal calibration reference for a total station (10), the total station (10) comprising a central unit (100) mounted on a collimator (110) for rotation about a first axis (130), wherein, The aiming device (110) is mounted on the base (120) of the total station (10) to rotate about a second axis (140) orthogonal to the first axis (130), thereby enabling the aiming axis (150) of the total station (10) to rotate about a point of rotation. The central unit (100) includes a plurality of measurement channels (102), each measurement channel (1020, 1022, 1024) having an optical axis (1030, 1032, 1034). At least one of the plurality of measurement channels (1022) includes a light source, and at least one of the plurality of measurement channels (1020, 1024) includes an image sensor. The method (60) includes: Determine (S600) the alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel relative to the aiming axis (150) of the total station (10), wherein the reference measurement channel is either a measurement channel (1022) including the light source or a measurement channel (1020, 1024) including the image sensor. The aiming axis (150) of the total station (10) is rotated (S602) around the rotation point to a predetermined position. At the predetermined position, the light beam emitted from the light source exits the central unit (100) via the objective lens (1000) and, after being reflected at the reflective optical element (112) fixedly connected to the aiming device (110), enters the central unit (100) via the objective lens (1000) to propagate toward the image sensor. A beam of light (S604) is emitted from the light source; The image is captured using the image sensor (S606); Identify (S608) the position of the light beam in the image; and The internal calibration reference of the total station (10) is determined (S610) based on the alignment error of the optical axis (1030, 1032, 1034) of the determined reference measurement channel and the position of the identified beam in the image.

2. The method (60) according to claim 1, wherein, The reflective optical element (112) is a mirror configured to reflect light emitted by the light source in a mirror manner.

3. The method (60) according to claim 1 or 2, wherein, When the aiming axis (150) of the total station (10) is in the predetermined position, the incident angle of the light beam at the reflective optical element (112) is smaller than the angle corresponding to the field of view associated with the image sensor.

4. The method (60) according to any one of claims 1-3, wherein, The reference measurement channel is associated with the measurement devices (1050, 1052, 1054), and (S600) the alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel is determined to include: The first measurement (S612) is performed in the first face of the total station (10) using the measuring devices (1050, 1052, 1054) associated with the reference measuring channel; A second measurement (S614) is performed in the second plane of the total station (10) using the measuring devices (1050, 1052, 1054) associated with the reference measuring channel, wherein, in the second plane, the central unit (100) is rotated 180° about each of the first axis (130) and the second axis (140) of the total station (10) compared to the first plane; and By comparing (S616) the first measurement and the second measurement, the alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel relative to the aiming axis (150) of the total station (10) is determined.

5. The method (60) according to any one of claims 1-4, wherein, The reference measurement channel is the measurement channel (1022) that includes the image sensor.

6. The method (60) according to any one of claims 1-5, wherein, The measurement channel (1022) including the light source and the measurement channel (1020, 1024) including the image sensor are different measurement channels.

7. The method (60) according to claim 6, further comprising: Determine (S618) the relative alignment error between the optical axis (1032) of the measurement channel (1022) including the light source and the optical axis (1030, 1034) of the measurement channel (1020, 1024) including the image sensor.

8. The method (60) according to claim 7, wherein, Determining (S618) the relative alignment error between the optical axis (1032) of the measurement channel (1022) including the light source and the optical axes (1030, 1034) of the measurement channels (1020, 1024) including the image sensor includes: The aiming axis (150) of the total station (10) is rotated (S620) around the rotation point to another predetermined position. At the other predetermined position, the light beam emitted from the light source exits the central unit (100) via the objective lens of the central unit (100), and after being reflected at the retroreflection optical element (114), it enters the central unit (100) via the objective lens (1000) to propagate toward the image sensor. A beam of light (S622) is emitted from the light source; Capture another image using the image sensor (S624); and Based on the position of the light beam in the other image, the relative alignment error of the optical axis (1032) of the measurement channel (1022) including the light source and the optical axis (1030, 1034) of the measurement channel (1020, 1024) including the image sensor is determined (S626).

9. A calibration method (70) for a total station (10) using an internal calibration reference determined by the method (60) according to any one of claims 1-8, wherein, The total station (10) includes a central unit (100) mounted on a collimator (110) to rotate about a first axis (130), wherein the collimator (110) is mounted on a base (120) of the total station (10) to rotate about a second axis (140) orthogonal to the first axis (130), thereby enabling the aiming axis (150) of the total station (10) to rotate about a point of rotation, wherein the central unit (100) includes a plurality of measurement channels (102), each measurement channel (1020, 1022, 1024) having an optical axis (1030, 1032, 1034), wherein at least one of the plurality of measurement channels (102) includes a light source, and wherein at least one of the plurality of measurement channels (102) includes an image sensor, wherein the calibration method (70) includes: The aiming axis (150) of the total station (10) is rotated (S700) around the rotation point to a predetermined position, where the internal calibration reference is determined, and at the predetermined position, the light beam emitted from the light source exits the central unit (100) via the objective lens (1000) of the central unit (100), and after being reflected at the reflecting optical element (112), enters the central unit (100) via the objective lens (1000) to propagate toward the image sensor; A beam of light (S702) is emitted from the light source; The image is captured using the image sensor (S704); Identify (S706) the position of the light beam in the image; and The position of the identified beam in the image is compared with the internal calibration reference (S708) to determine the alignment error of the optical axis (103, 1032, 1034) of the reference measurement channel relative to the aiming axis (150) of the total station (10).

10. The calibration method (70) according to claim 9 further includes: Determine (S710) the current relative alignment error between the optical axis (1032) of the measurement channel (1022) including the light source and the optical axes (1030, 1034) of the measurement channels (1020, 1024) including the image sensor; and The relative alignment of the optical axis (1032) of the measurement channel (1022) including the light source with the optical axis (1030, 1034) of the measurement channel (1020, 1024) including the image sensor is verified (S712) by comparing the current relative alignment error with the relative alignment error determined by the method according to claim 7 or 8.

11. The calibration method (70) according to claim 8 or 9, further comprising: The alignment error of the optical axis (1030, 1032, 1034) of the determined reference measurement channel relative to the aiming axis (150) of the total station (10) is compared with the allowable threshold error range (S714); and When the determined alignment error is outside the allowable threshold error range: An alarm (S716) is issued to the user of the total station (10) informing him that the alignment error of the optical axis (1030, 1032, 1034) of the determined reference measurement channel relative to the aiming axis (150) of the total station (10) is outside the allowable threshold error range.

12. A total station (10), comprising: A central unit (100) includes a plurality of measurement channels (102), each measurement channel (1020, 1022, 1024) having an optical axis (1030, 1032, 1034), wherein at least one of the plurality of measurement channels (1022) includes a light source, and wherein at least one of the plurality of measurement channels (102) includes an image sensor; A telescope (110), on which the central unit (100) is mounted to rotate about a first axis (130); The base (120) on which the aiming instrument (110) is mounted to rotate about a second axis (140) orthogonal to the first axis (130), thereby enabling the aiming axis (150) of the total station (10) to rotate about a point of rotation; A reflective optical element (112), which is fixedly connected to the aiming device (110); and Circuit (160), the circuit being configured to perform: Alignment error determination function (1600), which is configured to determine the alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel relative to the aiming axis (150) of the total station (10), wherein the reference measurement channel is either a measurement channel (1022) including the light source or a measurement channel (1020, 1024) including the image sensor. A rotation function (1602) is configured to rotate the aiming axis (150) of the total station (10) around the rotation point to a predetermined position, at which a light beam emitted from the light source exits the central unit (100) via the objective lens (1000), and after reflection at the reflecting optical element, enters the central unit (100) via the objective lens (1000) to propagate toward the image sensor. A light source control function (1604) is configured to control the light source to emit a light beam. An image sensor control function (1606) is configured to control the image sensor to capture images. A position recognition function (1608) is configured to identify the position of the light beam in the image, and An internal calibration reference determination function (1610) is configured to determine the internal calibration reference of the total station (10) based on the alignment error of the optical axis (1030, 1032, 1034) of the determined reference measurement channel and the position of the identified beam in the image.

13. The total station (10) according to claim 12, wherein, The reflective optical element (112) is a mirror configured to reflect light emitted by the light source in a mirror manner.

14. The total station (10) according to claim 12 or 13, wherein, When the aiming axis (150) of the total station (100) is in the predetermined position, the incident angle of the light beam at the reflecting optical element (112) is smaller than the angle corresponding to the field of view associated with the image sensor.

15. The total station (10) according to any one of claims 12-14, wherein, The reference measurement channel is associated with the measuring devices (1050, 1052, 1054), and wherein the alignment error determination function (1600) is configured to determine the alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel relative to the aiming axis (150) of the total station (10) by being configured to perform the following operations: A first measurement is performed on the first face of the total station (10) using the measuring devices (1050, 1052, 1054) associated with the reference measuring channel; The central unit (100) is rotated about the rotation point to the second face of the total station (10), wherein, in the second face, the central unit (100) is rotated 180° about each of the first axis (130) and the second axis (140) of the total station (10) compared to the first face; A second measurement is performed on the second face of the total station (10) using the measuring devices (1050, 1052, 1054) associated with the reference measuring channel; and By comparing the first measurement and the second measurement, the alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel relative to the aiming axis (150) of the total station (10) is determined.

16. The total station (10) according to any one of claims 12-15, wherein, The reference measurement channel is the measurement channel (1022) that includes the image sensor.

17. The total station (10) according to any one of claims 12-16, wherein, The circuit (160) is also configured to perform: Calibration function (1612), the calibration function is configured as follows: Rotate the aiming axis (150) of the total station (10) around the rotation point to the predetermined position; Control the light source to emit a beam of light; Control the image sensor to capture a second image; Identify the position of the light beam in the second image; as well as The position of the identified beam in the image is compared with the internal calibration reference to determine the alignment error of the optical axis (1030, 1032, 1034) of the reference measurement channel relative to the aiming axis (150) of the total station (10).

18. The total station (10) according to any one of claims 12-17, wherein, The measurement channel (1022) including the light source and the measurement channel (1020, 1024) including the image sensor are different measurement channels.

19. The total station (10) according to claim 18, wherein, The circuit (160) is also configured to perform: A relative alignment error determination function (1614) is configured to determine the relative alignment error between the optical axis (1032) of the measurement channel (1032) including the light source and the optical axis (1030, 1034) of the measurement channels (1020, 1024) including the image sensor.

20. The total station (10) according to claim 19, wherein, The total station (10) also includes: Retroreflective optical element (114); and The relative alignment error determination function (1614) is configured to determine the relative alignment error between the optical axis (1032) of the measurement channel (1022) including the light source and the optical axes (1030, 1034) of the measurement channels (1020, 1024) including the image sensor by being configured to perform the following operations: The aiming axis (150) of the total station (10) is rotated around the rotation point to another predetermined position. At this other predetermined position, the light beam emitted from the light source exits the central unit (100) via the objective lens (1000), and after being reflected at the retroreflection optical element (114), enters the central unit (100) via the objective lens (1000) to propagate toward the image sensor. Control the light source to emit a beam of light, Control the image sensor to capture another image, and Based on the position of the light beam in the other image, the relative alignment error between the optical axis (1032) of the measurement channel (1022) including the light source and the optical axis (1030, 1034) of the measurement channels (1020, 1024) including the image sensor is determined.

21. The total station (10) according to claim 19 or 20, wherein, The circuit (160) is also configured to perform: The relative alignment verification function (1616) is configured to: Determine the current relative alignment error between the optical axis (1032) of the measurement channel (1022) including the light source and the optical axes (1030, 1034) of the measurement channels (1020, 1024) including the image sensor, and The relative alignment of the optical axis (1032) of the measurement channel (1022) including the light source with the optical axis (1030, 1034) of the measurement channel (1020, 1024) including the image sensor is verified by comparing the current relative alignment error with the relative alignment error determined by the relative alignment error determination function (1614).

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