Mobile target with improved absolute position and orientation determination

Abstract

The invention relates to a mobile target with improved absolute position and orientation determination. The invention relates to a mobile target. The mobile target is configured to be arranged on a motion unit, which is arranged to move in an environment. The mobile target comprises a reflective element, an inertial measurement unit (IMU), a receiving unit configured to receive first position data on an actual absolute position of the mobile target transmitted by a geodetic instrument, a computing unit configured to continuously determine an actual relative position and orientation of the mobile target in the environment based on the IMU data, wherein the actual absolute position based on the first position data is used as a drift corrector, and a data and / or power interface configured to interact with a corresponding data and / or power interface of the motion unit for data and / or power transfer. Furthermore, a housing of the mobile target accommodates the reflective element, the IMU, the receiving unit, the computing unit, and the data and / or power interface.

Description

Technical Field

[0001] The present invention relates to a moving target configured to be aimed and tracked by a geodetic instrument and arranged on a motion unit configured to move in an environment. Background Technology

[0002] For example, prior art smart targets are described in public EP 2722647A1, which include an inertial measurement unit (IMU) in addition to a reflector (especially a retroreflector) to determine the orientation of the target in three-dimensional space.

[0003] However, the known arrangement of separating the IMU from the reflector has drawbacks. Firstly, the IMU's position relative to the reflector can be changed, requiring a new calibration after each change to ensure the reflector's orientation remains accurately determined. Secondly, several components must be installed when mounting the smart target, making the installation process more complex and prone to errors.

[0004] Furthermore, using existing smart targets to monitor the trajectory of moving units (such as robotic arms or construction vehicles) is also disadvantageous. If, during tracking of the smart target's reflector using a geodetic instrument (e.g., a total station), the tracking process is interrupted, for example due to an obstacle encountered, and thus the reflector's targeting is lost, the moving unit, and therefore the smart target, continues to move forward. The total station initially lacks information about the reflector's actual position and orientation, which is why it must then search for the smart target again to be able to re-aime and track it. This means that the trajectory cannot be captured during that period. Therefore, existing smart targets cannot guarantee reliable and complete monitoring of the moving unit's trajectory. Summary of the Invention

[0005] Therefore, the object of the present invention is to provide a moving target that overcomes the shortcomings of the prior art.

[0006] Another object of the present invention is to provide a system that overcomes the shortcomings of the prior art.

[0007] Another object of the present invention is to provide a moving target whose position and orientation can be reliably, accurately and continuously determined.

[0008] Another object of the present invention is to provide a mobile target that allows for easy and error-free assembly.

[0009] This invention relates to a moving target configured to be aimed at and tracked by a geodetic instrument (particularly a theodolite or total station) such that the actual absolute position of the moving target can be determined in relation to the absolute position of the geodetic instrument. The moving target is configured to be mounted on a motion unit, which is configured to move in the environment, thereby allowing the moving target to also move in the environment.

[0010] The moving target includes: a reflective element, particularly a retroreflective element (e.g., a retro-reflective tape target or a retroreflective (triple) prism or cat's-eye reflector), which is configured to reflect a measuring beam emitted by a geodetic instrument for aiming at the moving target back to the geodetic instrument; and an inertial measurement unit (IMU) for recording IMU data associated with the moving target.

[0011] The moving target also includes: a receiving unit configured to receive first position data about the actual absolute position of the moving target transmitted by a geodetic instrument; a calculation unit configured to continuously determine the actual relative position and orientation of the moving target in the environment based on IMU data (also known as attitude estimation), wherein the actual absolute position based on the first position data is used as a drift-corrector; and a data and / or power interface configured to interact with a corresponding data and / or power interface of the motion unit (in other words, a real-time interface for streaming data from the moving target to the motion unit) for data and / or power transmission.

[0012] In addition, the housing of the mobile target contains reflective elements, an IMU, a receiving unit, a computing unit, and data and / or power interfaces.

[0013] In the following description, the terms "absolute position of the moving target," "relative position and orientation (relative attitude, respectively) of the moving target," and "absolute attitude of the moving target" are used, which will be briefly explained below. The absolute position of the moving target is determined by a geodetic instrument, which requires a line of sight between the geodetic instrument and the moving target. The relative attitude of the moving target is determined by the fusion of data from a relative sensor (such as an IMU), for which a line of sight between the geodetic instrument and the moving target is not required. The absolute attitude of the moving target is determined based on the fusion of its absolute position and relative attitude.

[0014] Therefore, the moving target of the present invention can continue to determine its relative attitude (i.e., estimate its absolute attitude) even without an absolute positioning signal from a geodetic instrument. This allows the geodetic instrument to extrapolate / amplify the absolute attitude of the moving target based on the fusion of the absolute position of the moving target provided by the geodetic instrument itself and the relative attitude (attitude estimation) of the moving target provided by the moving target. This amplification allows for very rapid and accurate determination of the absolute attitude of the moving target, and therefore also allows for reliable relocking of the moving target by the geodetic instrument after loss of lock. In other words, IMU data (or even sensor data from one or more additional sensors) can be used to augment the first position data to rapidly and accurately determine the absolute attitude of the moving target.

[0015] Furthermore, the first position data, IMU data, and / or position and orientation data are directly available on the motion unit, which enables faster processing in the motion unit's computational unit.

[0016] Since the moving target is positioned on the motion unit, the attitude of the motion unit can also be determined and tracked by determining the attitude of the moving target and information about the positioning of the moving target on the motion unit.

[0017] The configuration of a moving target with a housing that accommodates a reflective element, an IMU, a receiving unit, a computing unit, and a data and / or power interface also has the following advantages:

[0018] • The distance / orientation between the reflector and the IMU is always the same and known, which means that the IMU only needs to be calibrated once. However, in the case of state-of-the-art smart target setups where the IMU is a separate unit from the target (e.g., for smart poles), the distance / orientation between the reflector and the IMU cannot be guaranteed to always be the same (e.g., the IMU may slide, be adjusted, or be temporarily removed). This is why a new calibration must be performed after each change in the position of the IMU relative to the reflector to ensure that the relative position and orientation (estimated attitude) of the reflector are still accurately determined.

[0019] • Installing moving targets on the motion unit is easier and more reliable because the target can be arranged as a whole on the motion unit, and the reflector and IMU do not need to be attached separately. This saves work steps during installation and is less prone to errors because no unit can be forgotten or incorrectly attached (e.g., with the wrong orientation).

[0020] • Thanks to its robust casing and compact design, all parts are better protected; individual parts will not fall out.

[0021] • Communication or data services between components installed in a mobile target (e.g., between IMU, receiving unit, computing unit, and data and / or power interface) can occur over short distances, which is why signal interference may not occur in the case of wireless connection. However, for smart targets of the prior art, such as IMU located outside the housing of the reflector, wireless connection must cover a larger area and is therefore more susceptible to interference.

[0022] • If the communication or data service occurs via a wired connection between the units, the cable is installed inside the housing and is not suspended outside the target between the individual units, and therefore will not tangle there;

[0023] • A single power supply is used for all units in the moving target;

[0024] • Lighter weight because a single housing is used for all units, which also saves on production steps and parts / materials.

[0025] The term "shell" is understood to refer to a robust protective enclosure for the various components of a moving target, wherein the dimensions of the enclosure are designed and, if necessary, connected to the components in a manner that prevents them from moving (or allows them to move only to a desired extent). Furthermore, the enclosure must be shaped in such a way that the reflective elements can still be aimed at by the measuring beam of a geodetic instrument.

[0026] Geodetic instruments (often also known as ground absolute positioning systems (TAPS)) serve as absolute attitude or positioning systems that can reference a local or global coordinate system (e.g., with a reference target / prism or GNSS). TAPS can be configured for, for example, indoor and outdoor use as well as for long-range applications up to several hundred meters (e.g., 200 m to 500 m).

[0027] Therefore, the moving target according to the invention can be configured for closed-loop applications and dynamic measurements, making it particularly suitable for robotic, high-precision positioning, or highly dynamic measurement applications within the accuracy range of TAPS signals. Closed-loop applications require a more reliable data stream and low latency to achieve a high phase margin in the control loop. However, good time synchronization between all sensors is paramount to improve dynamic accuracy.

[0028] In other words, the moving target includes a computing unit that runs, for example, real-time algorithms to compute its own attitude estimate (determining the moving target's actual relative position and orientation in the environment), which is related to, for example, the absolute position of the moving target determined by TAPS and / or the absolute position of TAPS itself. IMU data can be used to amplify the measurement frequency and corresponding frequency limits of TAPS, as well as increase the phase margin and Nyquist frequency.

[0029] The moving target also allows the transfer of raw or pre-processed data streams from all connected devices to each other. Attitude estimation is defined as 6DOF information for position and orientation. Furthermore, velocity and acceleration in each degree of freedom dimension can yield up to 18 values ​​(see table below). This definition includes each combination or abstraction of the 18 values, such as the following examples: xyz (3D coordinates), xy-yaw (2D plane with orientation), xyz-roll-pitch-yaw (6DOF position), etc. Each value may optionally include a covariance, where the covariance is the estimation accuracy of the corresponding value of the attitude estimate. Furthermore, the reliability of the covariance can further aid in weighting corresponding sensor signals in multi-sensor fusion.

[0030]

[0031] In an exemplary embodiment of the moving target according to the invention, the moving target and / or motion unit may further include at least one sensor unit, wherein the at least one sensor unit may be configured as: a Global Navigation Satellite System (GNSS) receiver, such as a GPS antenna (with or without RTK to calculate global position, but also to improve attitude estimation in case of loss of line of sight), a camera system (e.g., including calibration and real-time orientation algorithms), a visual inertial system (VIS), a time-of-flight camera system (e.g., including calibration and real-time orientation algorithms), a light detection and ranging (LIDAR) system, a depth detection camera system, a radar system (mmWaver radar), a barometer, or a magnetometer. Optionally, the housing of the moving target may include at least one sensor unit.

[0032] In another exemplary embodiment of the mobile target according to the invention, if the mobile target includes at least one sensor unit (8), the computing unit may be further configured to continuously determine the actual relative position and / or orientation of the mobile target in the environment based on sensor data collected by the at least one sensor unit, and / or if the motion unit includes at least one sensor unit, the computing unit of the motion unit is configured to continuously determine another actual relative position and / or orientation of the mobile target in the environment based on sensor data collected by the at least one sensor unit, wherein the determined other actual relative position and / or orientation of the mobile target in the environment is transmitted from the motion unit (particularly via a data and / or power interface) to the mobile target and processed by the computing unit of the mobile target to determine the actual relative position and / or orientation of the mobile target in the environment.

[0033] In other words, moving targets and / or motion units can be augmented with additional sensors to improve attitude estimation, time synchronization optimization, and drift reduction. Specifically, moving targets and / or motion units, for example, including cameras with VIS or lidar with Simultaneous Localization and Mapping (SLAM), can improve attitude estimation and eliminate IMU (rotational) drift. In other words, one or more additional sensors can augment a moving target to advantageously improve the accuracy and reliability of determining the moving target's actual relative position and orientation (attitude estimation). Furthermore, based on sensors and algorithms within the moving target, its absolute attitude can be measured even when absolute TAPS (dead reckoning) is lost. Depending on the type of sensors within the moving target and / or motion unit, the customer can continue their mission for a limited period with limited absolute attitude accuracy. Optionally, additional sensors can be used to optimize time synchronization and / or drift reduction / drift correction. In other words, the motion unit can also, for example, send attitude estimation data to the moving target to ensure more stable and faster realignment / rediscovery (rapid relocking) in dead reckoning. Motion unit attitude estimation is supported by data sources because more sensors can typically be mounted on the motion unit, and attitude estimation can be more accurate (e.g., wheel odometers, dual-antenna GNSS, and other sensors).

[0034] In another exemplary embodiment, the moving target may further include a transmitting unit configured to transmit position and orientation data, including data relating to the actual relative position and orientation of the moving target, to a receiving unit of a geodetic instrument. Optionally, the housing of the moving target may further include the transmitting unit.

[0035] One advantage of configuring a moving target with a transmitting unit, receiving unit, and data interface is that it allows data to be exchanged from the geodetic instrument to the moving target, from the moving target to the motion unit, and back again. This interconnects all the sensors in these devices, meaning that position determination, or attitude determination, can be performed more robustly and accurately. Furthermore, for example, the moving target can receive all the raw sensor data and the calculated covariance of the attitude estimate and send (stream) it to the TAPS and the motion unit.

[0036] In another embodiment, both the receiving unit and the transmitting unit can be included by a transceiver unit. Optionally, the transceiver unit can be configured as a radio transceiver.

[0037] Optionally, TAPS can transmit data streams to the moving target via a low-latency connection, which can be 3D data or 6DOF data. If properly configured, the radio connection can be used for time synchronization and (consistent bidirectional) data streaming to reduce latency and improve dynamic accuracy.

[0038] In another embodiment, the receiving unit may be configured to receive time information associated with the first location data. The transmitting unit may be configured to transmit time information associated with the IMU data and / or location and orientation data. Furthermore, the computing unit may be configured to perform time synchronization (e.g., TSN, PTP, NTP, or PPS) based on the time information associated with the first location data and the time information associated with the IMU data and / or location and orientation data.

[0039] In another embodiment, the computing unit can be configured to perform drift correction based on a drift corrector to correct for deviations between the actual relative position and the actual absolute position (caused by, for example, IMU drift). The transmitting unit can be configured to transmit position and orientation data to the receiving unit of the geodetic instrument, further including data related to such corrected actual relative position, such that if the geodetic instrument's alignment and tracking of the moving target is interrupted, particularly during the moving target's movement in the environment, realignment of the geodetic instrument with the moving target is enabled based on the position and orientation data. Optionally, realignment of the geodetic instrument with the moving target is enabled based on data related to the corrected actual relative position.

[0040] In other words, once the reflector can be tracked again, the position and orientation data stream can be transmitted to TAPS for immediate relocking in the event of a loss of lock. The data stream inherently features a robust and reliable system where TAPS acquires all possible information as quickly as possible to relock, even when line of sight is lost, without requiring manual relocking. Furthermore, the focus is on high-accuracy navigation and static and dynamic measurements with real-time attitude information (attitude estimation). It can be used both indoors and outdoors, as well as for semi-autonomous or unmanned applications.

[0041] In another embodiment, the computing unit can be configured to perform time synchronization of the timing information associated with the first location data, IMU data, position and orientation data, and / or sensor data with GNSS global time, if the sensor unit is configured as a GNSS receiver, particularly a GNSS antenna. In other words, GNSS can also be used to synchronize all sensors with GNSS global time.

[0042] In another embodiment, the receiving unit may be configured to receive second position data about the actual absolute position of the moving target transmitted by another geodetic instrument, and the transmitting unit may be configured to transmit position and orientation data to the receiving unit of the other geodetic instrument.

[0043] In another embodiment, the computing unit may be configured to process first and second position data, and based on such processing, provide improved accuracy in determining the actual absolute position, wherein such improved actual absolute position can be used as a drift corrector. Determining whether the accuracy has been improved can, for example, be based on a comparison of the accuracy value for determining the actual absolute position with a given / pre-calculated / predefined accuracy value. This comparison may optionally be performed by the computing unit of the moving target or the computing unit of a geodetic instrument.

[0044] In another embodiment, the moving target can be configured such that if the receiving unit receives an information signal from a geodetic instrument / device (particularly during movement of the moving target in the environment) indicating that the alignment and tracking of the moving target by the geodetic instrument / device is interrupted, and / or a first accuracy value for determining the actual absolute position of the moving target is lower than a first predefined accuracy value, and / or receives an information signal from a computing unit indicating that a second accuracy value for determining the actual relative position and orientation of the moving target in the environment is lower than a second predefined accuracy value, and / or receives an information signal from an input unit / user interface indicating that alignment and tracking of the moving target must be performed by another geodetic instrument (in other words, a manual switch from the first TAPS to the other TAPS), then the transmitting unit transmits a switch signal to the receiving unit of the other geodetic instrument. The switch signal is provided to trigger the other geodetic instrument to perform alignment and tracking of the moving target. Optionally, alignment of the moving target by the other geodetic instrument can be enabled based on position and orientation data, particularly based on data related to the corrected actual relative position. Optionally, the comparison between the first accuracy value and the first predefined accuracy value is performed by the calculation unit of the geodetic instrument, and / or the comparison between the second accuracy value and the second predefined accuracy value is performed by the calculation unit of the moving target. Optionally, the input unit / user interface may be included in the moving target or may be separate from the moving target, wherein the input unit / user interface is configured to exchange signal data with the receiving unit of the moving target.

[0045] In other words, a moving target can be attached to multiple TAPSs to improve accuracy, redundancy, robustness, and ensure flawless absolute attitude determination even when the line of sight to another TAPS is interrupted. This can also be used to reposition TAPSs, lock them onto the moving target, and estimate the repositioned TAPS position based on the moving target's attitude estimation (automatic stationing).

[0046] In another embodiment, the moving target (particularly the housing of the moving target) may include a mounting element configured to interact with a complementary mounting element of the motion unit to provide an arrangement of the moving target on the motion unit.

[0047] In another implementation, the determination of the actual relative position and orientation of the moving target in the environment can be performed by a computing unit based on a (multi)sensor fusion algorithm (especially a state estimation algorithm or attitude estimation algorithm).

[0048] For example, a Kalman filter can estimate position errors, velocity errors, attitude errors, gyroscope biases, and accelerometer biases (e.g., caused by so-called IMU drift) based on the difference between the observed actual relative position and the actual absolute position of a moving target, where the errors (or drift) can then be corrected. Furthermore, for example, the position of the moving target determined by GNSS can optionally be included in this drift correction to improve drift determination and thus improve drift correction.

[0049] In other words, a moving target can include a multi-sensor data fusion algorithm to calculate its own pose estimate relative to its absolute position. This can be streamed to TAPS to improve tracking or streamed to the motion unit.

[0050] In another embodiment, the computing unit can be configured to continuously determine the velocity and / or acceleration of the moving target based on IMU data. The computing unit can be further configured to continuously determine the actual relative position and orientation of the moving target in the environment based on the velocity and / or acceleration of the moving target.

[0051] In another embodiment, the computing unit can be configured to further determine the vibrations of the moving target based on IMU data, particularly during the movement of the moving target in the environment, and to provide improved accuracy in determining the actual absolute position and / or actual relative position based on the determined vibrations. Determining whether this accuracy has been improved can, for example, be based on a comparison of the accuracy value for determining the actual absolute position and / or actual relative position with a given / pre-calculated / predefined accuracy value. This comparison can optionally be performed by the computing unit of the moving target or the computing unit of a geodetic instrument. Optionally, the computing unit can be configured to determine inconsistencies in the motion patterns provided to the motion unit based on the determined vibrations.

[0052] In other words, the IMU in the moving target also indicates the vibration of the system (moving target and motion unit), which can be used to improve the accuracy of attitude and reliability calculations of other sensors, as well as serve as an indicator of potential misbehavior of the motion unit.

[0053] In another embodiment, the computing unit may be further configured to continuously determine the actual relative position and orientation of the moving target in the environment based on the absolute position of the geodetic instrument.

[0054] In another embodiment, the motion unit can be configured as follows:

[0055] • Robots, especially wheeled or legged robots,

[0056] • Robotic rotating arm,

[0057] • Film camera,

[0058] • Construction machinery, especially graders, excavators, bulldozers, cranes, or pavers.

[0059] • Transport vehicles, especially cars or motorcycles, or

[0060] • Unmanned aerial vehicles (UAVs).

[0061] In another embodiment, if the reflective element is configured as a reflective prism, the computing unit may be configured to compensate for prism errors based on first position data and / or position and orientation data.

[0062] In other words, TAPS data can be augmented with IMU data or even data from one or more additional sensors to apply corrections (e.g., prism correction). Specifically, moving targets can compensate for prism errors by knowing each other's TAPS and prism orientation, as well as the corresponding system prism errors.

[0063] In another embodiment, the receiving unit may be configured to receive first orientation data about the actual relative orientation of a moving target in the environment, determined and transmitted by a geodetic instrument.

[0064] In other words, if TAPS also has 6DOF target detection, then TAPS can transmit the 6DOF information stream related to the moving target to the receiving unit of the moving target or the receiving unit of the motion unit.

[0065] In another embodiment, the moving target includes target identification information provided for identification by a geodetic instrument, wherein the target identification information may be transmitted to a receiving unit of the geodetic instrument by means of a transmitting unit, or may be derived by the geodetic instrument from a comparison of the trajectory of the moving target in the environment with the trajectories of other moving targets in the environment.

[0066] In other words, the moving target includes a target ID to identify and always track the correct target, especially the correct prism. The target ID can also be established by comparing the trajectory of the moving target and the TAPS.

[0067] In another embodiment, the transmitting unit can be configured to transmit position and orientation data to the receiving unit of a geodetic instrument, wherein the transmitting unit of the geodetic instrument can subsequently transmit the position and orientation data to the receiving unit of the motion unit.

[0068] In another implementation, position and orientation data (attitude estimation data) can be streamed from a geodetic instrument (TAPS) to the motion unit (rather than from a moving target).

[0069] In another embodiment, the first location data, IMU data, location and orientation data, and / or sensor data can be transmitted to the motion unit via a data and / or power interface that interacts with a corresponding data and / or power interface, wherein the data and / or power interface can be configured to be wired or wireless. Optionally, all data streams from and to the moving target include the covariance of each value.

[0070] In another embodiment, the motion unit can be configured to determine its actual absolute position and / or actual relative position and orientation in the environment based on transmitted first position data, IMU data, position and orientation data, and / or sensor data. Optionally, the motion unit can be configured to transmit the actual absolute position and / or actual relative position and orientation determined by the motion unit back to the moving target via an interactive data and / or power interface, and the transmitting unit of the moving target can be configured to transmit the actual absolute position and / or actual relative position and orientation determined by the motion unit to the receiving unit of the geodetic instrument.

[0071] In other words, the moving target has bidirectional interfaces to the motion unit and TAPS to improve the moving target's attitude estimation by receiving additional estimates from the motion unit, and to enable TAPS to perform additional computations. All interfaces allow for high-accuracy time synchronization and bidirectional low-latency data streaming for real-time setups such as closed-loop applications or dynamic measurements. Furthermore, the motion unit can stream back its own attitude estimates to optimize the moving target's attitude estimation in the event of line-of-sight interruption, to relock as quickly as possible (or never lose lock).

[0072] The present invention further relates to a system for improving the aiming and tracking of a moving target, wherein the system comprises: a moving target according to one embodiment of the foregoing embodiments; a geodetic instrument, particularly a theodolite or total station, configured to aim at and track the moving target such that the actual absolute position of the moving target can be determined in relation to the absolute position of the geodetic instrument; and a motion unit, wherein the moving target is disposed on the motion unit and the motion unit is configured to move in the environment such that the moving target also moves in the environment.

[0073] The transmission / transmission / communication of position and orientation data (including data relating to the actual / current relative position and orientation of the moving target) (and optionally further data) to the receiving unit of the geodetic instrument / equipment can be performed by means of a transmitting unit included in the moving target (especially the housing of the moving target) and / or by means of a transmitting unit included in the motion unit.

[0074] In another embodiment of the system of the present invention, data can be transmitted from the transmitting unit of the moving target to the receiving unit of the geodetic instrument, and then from the transmitting unit of the geodetic instrument to the receiving unit of the moving unit. For example, this data transmission can be performed via Ethernet or radio. Attached Figure Description

[0075] The invention is illustrated in more detail below by way of example only, with reference to the schematic examples shown in the accompanying drawings. In the drawings, the same elements are labeled with the same reference numerals. The described embodiments are generally not shown to scale and should not be construed as limiting the invention. Specifically,

[0076] Figure 1 A schematic diagram of a smart target in the prior art is shown;

[0077] Figures 2A to 2B An exemplary embodiment of the moving target of the present invention is shown;

[0078] Figure 3 A schematic diagram of the tracing process performed by the system according to the present invention is shown;

[0079] Figure 4 A schematic diagram of drift correction performed by the system of the present invention is shown. Detailed Implementation

[0080] Figure 1 A schematic diagram of a prior art smart target 100 is shown. In this smart target 100, a target 101 having a reflector 102 (particularly a retroreflector 102) is mounted on a surveying rod 103 so that the location of the contact point between the surveying rod 103 and the object can be determined by using a geodetic instrument (e.g., a total station) to determine the position of the target 102. The smart target further has a separate IMU 104 also mounted on the surveying rod 103.

[0081] The intelligent target 100 is configured to input the repeatedly determined position and repeatedly determined inertial state data of the target 101 into a predefined filter algorithm, and derive the reference attitude data of the survey rod 103 from it, while taking into account the defined spatial relationship of the IMU relative to the reflector 102, and using the reference attitude data to derive the position of the contact point.

[0082] In particular, the prior art intelligent target 100 lacks the ability to determine the relative position and orientation of target 101, and to adjust the relative position of target 101 to the absolute position determined by the total station in order to correct IMU drift. Furthermore, due to the lack of relative position and orientation of target 101, the intelligent target 100 cannot perform a simplified or faster new alignment of target 101 based on relative position and orientation after losing alignment. This is why the prior art intelligent target 100 is only suitable for static or very slow surveying operations. Therefore, it is impossible to use the prior art intelligent target 100 to capture the trajectory of the motion unit equipped with intelligent target 100 as completely as possible, or to track the motion unit with a total station. Moreover, the two-part structure of the prior art intelligent target 100 with an IMU 104 separate from target 101 suffers from the aforementioned disadvantages.

[0083] Figure 2A An exemplary embodiment of the mobile target 1 of the present invention is shown, wherein the mobile target 1 includes a retroreflective element 2 configured as a prism, an IMU 3, a receiving unit 4, a computing unit 5, and a data and power interface 6, wherein these components 2-6 are all housed in the housing 7 of the mobile target 1.

[0084] Figure 2B The illustrated embodiment also includes a GNSS receiver 8 (e.g., a GPS antenna), a mounting element 9, and a transmitting unit 10, all housed within the housing 7. In the illustrated embodiment, the mounting element 9 and the data and power interface 6 are designed as protruding elements that can be inserted into corresponding mating recesses of the motion unit 11 when the mobile target 1 is positioned on the motion unit 11 (e.g., a construction vehicle or robotic arm). Of course, the mounting element 9 can also have different shapes, such as recesses, hooks, etc., as long as a secure hold to the motion unit 11 is ensured. In the illustrated embodiment, the data and power interface 6 is designed as a type of USB connector (e.g., USB-C) that can be inserted into a corresponding USB mating connector of the motion unit 11. The data and power interface 6 can also be configured differently, for example, as power line communication (PLC) or digital power line (DPL) or as an inductive charging station for charging the battery in the mobile target 1, combined with a radio connection (such as (remote) Bluetooth) for data transmission.

[0085] Transmitting unit 10 is configured to transmit data via a radio connection (e.g., to a corresponding receiving unit of geodetic instrument 12), and receiving unit 4 is configured to receive data provided via a radio connection (e.g., from a corresponding transmitting unit of geodetic instrument 12).

[0086] Figure 3A schematic diagram of the tracking process performed by the system 21 according to the invention is shown. A motion unit configured for the vehicle 11 moves along path 13 in the environment 14. Since the moving target 1 is fixedly connected to the vehicle 11 via mounting unit 9, the position or attitude of the vehicle 11 can also be determined by determining the position or attitude of the moving target 1.

[0087] The total station 12 has aimed its measuring beam 18 at the reflector 2 of the moving target 1. The measuring beam 18 is reflected back to the total station 12, so that the actual absolute position 16 of the moving target 1 is determined based on the absolute position of the total station 12. This actual absolute position 16 is transmitted by the total station's transmitting unit / transmission unit / sending unit to the receiving unit 4 of the moving target 1.

[0088] In order to continue following the route 13 of the moving target 1, and therefore also the route 13 of the car 11, or even if the moving target 1 loses its aim due to a large obstacle in the field of view of the total station 12, it can be quickly re-aimed by the total station 12, the IMU 3 of the moving target 1 records IMU data, based on which the computing unit determines the relative position 15 and relative orientation of the moving target. Because the IMU 3 is subject to so-called IMU drift (or gyroscope drift), the deviation between the current relative position 15 and the actual absolute position 16 occurs over time. Drift correction performed by the computing unit 5 (where the actual absolute position 16 is used as a drift corrector) corrects the deviation that has occurred between the relative position 15 and the absolute position 16. Then, the corrected actual relative position 15 or the corresponding position data 20 is transmitted from the transmitting unit / transmission unit / sending unit 10 of the moving target 1 to the receiving unit of the total station 12 via radio, so that the total station 12 knows the current position of the moving target 1 very accurately even if the moving target 1 is lost, thereby making realignment easier.

[0089] In addition, the moving target 1 has a GPS antenna 8, through which GPS data 19 can be received. The GPS antenna 8 can determine the position of the moving target and include it in the drift correction in order to improve the drift correction.

[0090] The moving target 1 is connected to the vehicle 11 via the data and power interface 6, and is therefore powered and can exchange data accordingly. This means that the data provided by the vehicle 11 (e.g., the relative position of the vehicle 11) can be used to determine the relative position 15 of the moving target 1 for drift correction.

[0091] Figure 4A schematic diagram of drift correction performed by the system 21 of the present invention is shown. A motion unit 11 (e.g., a construction vehicle) moves along a trajectory 13 in an environment 14 (e.g., a construction site), such that a moving target 1 attached to the construction vehicle 11 also moves along the trajectory 13. During this movement, the moving target 1 is aimed and tracked by a geodetic instrument 12 (e.g., a total station). The IMU 3 of the moving target 1 permanently captures IMU data, based on which the actual relative position 15 of the moving target 1 in the environment 14 is continuously determined. Since the actual relative position 15 deviates from the actual absolute position 16 (which is determined by the total station 12), after covering a certain distance due to IMU drift, drift correction based on the actual absolute position is performed by a sensor fusion algorithm executed in the computing unit 5, which corrects the deviation 17 between the actual relative position 15 and the actual absolute position 16. After traveling another distance, the relative position 15 again deviates from the absolute position 16, which is why the aforementioned drift correction is performed again. This allows the trajectory of the moving target 1, and therefore the trajectory 13 of the motion unit 11, to be recorded as accurately and completely as possible.

[0092] Although the invention has been illustrated above with reference to some preferred embodiments, it should be understood that many modifications and combinations of different features of the embodiments can be made. All such modifications are within the scope of the appended claims.

Claims

1. A moving target (1) configured to be aimed at and tracked by a geodetic instrument (12), such that the actual absolute position (16) of the moving target (1) can be determined in relation to the absolute position of the geodetic instrument (12), the geodetic instrument (12) being particularly a theodolite or total station, wherein, The moving target (1) is configured to be arranged on a motion unit (11), the motion unit (11) being configured to move in an environment (14) such that the moving target (1) is also capable of moving in the environment (14), wherein the moving target (1) comprises: • A reflective element (2) configured to reflect a measuring beam emitted by the geodetic instrument (12) for aiming at the moving target (1) back to the geodetic instrument (12). • An inertial measurement unit (IMU) (3), which is used to record IMU data related to the moving target (1), • A receiving unit (4), configured to receive first position data about the actual absolute position (16) of the moving target (1) transmitted by the geodetic instrument (12). • A calculation unit (5) configured to continuously determine the actual relative position (15) and orientation of the moving target (1) in the environment (14) based on the IMU data, wherein the actual absolute position (16) based on the first position data is used as a drift corrector, and • A data and / or power interface (6), which is configured to interact with a corresponding data and / or power interface of the motion unit (11) for data and / or power transmission. The housing (7) of the moving target (1) houses the reflective element (2), the IMU (3), the receiving unit (4), the computing unit (5), and the data and / or power interface (6).

2. The moving target (1) according to claim 1, wherein, The moving target (1) and / or the motion unit (11) include at least one sensor unit (8), particularly the housing (7) of the moving target (1) and / or the motion unit (11) include at least one sensor unit (8), wherein the at least one sensor unit (8) is configured to • Global Navigation Satellite System (GNSS) receiver • Visual Inertial System (VIS) • Time-of-flight camera system, • Light detection and ranging LIDAR system, • Depth detection camera system, • Radar system • Barometer, or • Magnetometer.

3. The moving target (1) according to claim 2, wherein, • If the moving target (1) includes at least one sensor unit (8), the computing unit (5) is further configured to continuously determine the actual relative position (15) and / or orientation of the moving target (1) in the environment (14) based on sensor data collected by the at least one sensor unit (8), and / or • If the motion unit (11) includes at least one sensor unit (8), the computing unit of the motion unit (11) is configured to continuously determine another actual relative position and / or orientation of the moving target (1) in the environment (14) based on the sensor data collected by the at least one sensor unit (8), wherein the determined other actual relative position and / or orientation of the moving target (1) in the environment (14) is transmitted from the motion unit (11) to the moving target (1), particularly via the data and / or power interface, and is processed by the computing unit (5) of the moving target (1) to determine the actual relative position (15) and / or orientation of the moving target (1) in the environment (14).

4. The moving target (1) according to any one of the preceding claims, wherein, The moving target (1) further includes a transmitting unit (10) configured to transmit position and orientation data to a receiving unit of the geodetic instrument (12), the position and orientation data including data relating to the actual relative position (15) and orientation of the moving target (1), and in particular, the housing (7) of the moving target (1) further includes the transmitting unit (10).

5. The moving target (1) according to claim 4, wherein, Both the receiving unit (4) and the transmitting unit (10) are comprised of a transceiver unit, wherein the transceiver unit is configured as a radio transceiver.

6. The moving target (1) according to claim 4 or 5, wherein, • The receiving unit (4) is configured to receive time information related to the first location data. • The transmitting unit (10) is configured to transmit time information related to the IMU data and / or the location and orientation data, and • The computing unit (5) is configured to perform time synchronization based on the time information associated with the first location data and the time information associated with the IMU data and / or the location and orientation data.

7. The moving target (1) according to any one of claims 4 to 6, wherein, The calculation unit (5) is configured to perform drift correction based on the drift corrector to correct the deviation between the actual relative position (15) and the actual absolute position (16), wherein the transmitting unit (10) is configured to transmit the position and orientation data, which further includes data related to such corrected actual relative position (15), to the receiving unit of the geodetic instrument (12) so that if, particularly during the movement of the moving target (1) in the environment (14), the alignment and tracking of the moving target (1) by the geodetic instrument (12) is interrupted, the geodetic instrument (12) is enabled to realign the moving target (1) based on the position and orientation data, particularly based on the data related to the corrected actual relative position (15).

8. The moving target (1) according to claims 3 and 6, wherein, The computing unit (5) is configured to perform time synchronization with GNSS global time if the sensor unit (8) is configured as a GNSS receiver: • First location data, • The IMU data, • The location and orientation data, and / or • The sensor data.

9. The moving target (1) according to any one of claims 4 to 8, wherein, • The receiving unit (4) is configured to receive second position data about the actual absolute position (16) of the moving target (1) transmitted by another geodetic instrument, and • The transmitting unit (10) is configured to transmit the location and orientation data to the receiving unit of the other geodetic instrument.

10. The moving target (1) according to claim 9, wherein, The computing unit (5) is configured to process the first position data and the second position data, and based on such processing, to provide improved accuracy in determining the actual absolute position (16), wherein such improved actual absolute position (16) is used as the drift corrector.

11. The moving target (1) according to claim 9 or 10, wherein, The moving target (1) is configured such that if the receiving unit (4) receives an information signal from the following device, especially if the moving target (1) receives the information signal from the following device while moving in the environment (14), • The geodetic instrument (12), the information signal indicates o The alignment and tracking of the geodetic instrument (12) with the moving target (1) is interrupted, and / or o The first accuracy value used to determine the actual absolute position (16) of the moving target (1) is lower than a first predefined accuracy value, and / or • The computing unit (5), the information signal indicating that the second accuracy value for determining the actual relative position (15) and orientation of the moving target (1) in the environment (14) is lower than a second predefined accuracy value, and / or • An input unit, wherein the information signal indicates that the alignment and tracking of the moving target (1) must be performed by the other geodetic instrument, and in particular, wherein the input unit is comprised of the moving target (1). The transmitting unit (10) then transmits a switching signal to the receiving unit of the other geodetic instrument, wherein the switching signal is provided to trigger the other geodetic instrument to perform the alignment and tracking of the moving target (1), and in particular, wherein the alignment of the moving target (1) by the other geodetic instrument is enabled based on the position and orientation data, particularly based on the data related to the corrected actual relative position (15).

12. The moving target (1) according to any one of the preceding claims, wherein, The moving target (1) includes a mounting element (9), and in particular, the housing (7) of the moving target (1) houses the mounting element (9), which is configured to cooperate with a complementary mounting element of the motion unit (11) to provide the arrangement of the moving target (1) on the motion unit (11).

13. The moving target (1) according to any one of the preceding claims, wherein, The computing unit (5) performs the determination of the actual relative position (15) and orientation of the moving target (1) in the environment (14) based on the sensor fusion algorithm.

14. The moving target (1) according to any one of the preceding claims, wherein, The computing unit (5) is configured to continuously determine the velocity and / or acceleration of the moving target (1) based on the IMU data, wherein the computing unit (5) is further configured to continuously determine the actual relative position (15) and orientation of the moving target (1) in the environment (14) based on the velocity and / or acceleration of the moving target (1).

15. A system (21) for improving the aiming and tracking of a moving target (1), wherein, The system (21) includes: • The moving target (1) according to any one of claims 1 to 14. • A geodetic instrument (12), particularly a theodolite or total station, configured to aim at and track the moving target (1), such that the actual absolute position (16) of the moving target (1) can be determined in relation to the absolute position of the geodetic instrument (12), and • Motion unit (11), wherein, The moving target (1) is arranged on the motion unit (11), and o The motion unit (11) is configured to move in the environment (14) such that the moving target (1) also moves in the environment (14).

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