Method for commissioning a sensor unit, sensor unit and motion unit with sensor unit

Abstract

The invention relates to a method for commissioning a sensor unit (16), comprising an acceleration sensor and / or tilt sensor, which is / are connected to a motion unit (10) in any mounting orientation, and wherein the method comprises the following commissioning steps to perform a translational axis calibration of a sensor coordinate system (x1, y1), (x3, y3): performing a translational movement of the motion unit (10), acquiring the acceleration and / or rotational velocity values ​​occurring during the translational movement in order to determine a motion vector (x2, y2), (x4, y4), teaching in a correction factor to transform an axis of the original sensor coordinate system (x1, y1), (x3, y3) in the direction of the determined motion vector (x2, y2), (x4, y4).

Description

The present invention relates to a method for commissioning a sensor unit, as well as a sensor unit and a motion unit with a sensor unit. In the prior art, sensor units for detecting the movement of a motion unit, in particular a mobile working machine or a mobile component of a working machine, are known, wherein the sensor unit may comprise an inclination sensor and an acceleration sensor. The sensor unit is connected to the motion unit. Typically, the sensor unit for detecting translational movements is aligned manually, which can lead to significant measurement inaccuracies, especially with complex motion sequences or misaligned mounting points. Manual adjustment is also error-prone and time-consuming, as the actual motion vector cannot always be precisely determined. Additionally, measured acceleration values ​​can be distorted by sensor misalignment. For example, in practice it often happens that the sensor unit on a mobile device is not mounted exactly along the direction of travel, which can lead to an offset between the actual motion vector of the machine and the orientation of the sensor coordinate system. US Patent 2011 / 0202225 A1 discloses a device equipped with an accelerometer that uses GPS and known orientation data to determine the accelerometer's orientation when the vehicle is stationary and in motion. The orientation data is derived from known surface information, the measured GPS velocity, and the measured GPS heading. US Patent 2016 / 0109270 A1 discloses a method for assigning network identifiers to a group of sensor modules that measure a three-dimensional action vector and are direction-dependent in three-dimensional space. Each sensor module is mounted at a different position on a machine, so the orientation of each sensor module is different. The method comprises one or two stages. In the first stage, the machine is brought into a steady state, and measurements of a static action vector from a sensor module identified by a network identifier are correlated with expected measurements from a sensor module with a corresponding orientation and position.In the second stage, the machine is put into a dynamic state, and measurements of a dynamic action vector from a sensor module identified by a network identifier are correlated with expected measurements from a sensor module with the corresponding orientation and position. The object of the present invention is to provide a method for commissioning a sensor unit which, while avoiding the disadvantages known from the prior art, enables a precise and reliable determination of the movement of a motion unit. In particular, it aims to enable fast, reliable, and automated axis adjustment of the sensor coordinate system to the translational motion vector of the motion unit. Furthermore, the task includes providing a sensor unit and a motion unit. The problem is solved with respect to the method by the features of claim 1, with respect to the sensor unit by the features of claim 8 and with respect to the motion unit by the features of claim 9. Advantageous embodiments of the invention are specified in the dependent claims. According to the invention, a method for commissioning a sensor unit is claimed, comprising an acceleration sensor and / or preferably an inclination sensor, which is / are connected to a motion unit in any mounting orientation, and wherein the method comprises the following commissioning steps in a preferred sequence to perform a translational axis calibration of a sensor coordinate system: - Performing a translational movement of the motion unit, in particular at least temporarily; - Capturing the acceleration and / or rotational velocity values ​​occurring during the translational movement, preferably also inclination values, in order to determine a motion vector; - Teaching in a correction factor for transforming an axis of the original sensor coordinate system in the direction of the determined motion vector. In other words, the sensor unit is preferably aligned in a fixed, but arbitrary, Cartesian sensor coordinate system. Targeted translational movements of the machine or the affected body part are used to acquire measurements, from which the effective motion vector is determined. A correction factor can then be derived from this, transforming the original sensor coordinate system to the direction of movement. In particular, this allows the actual motion vector to be determined, whereby a correction factor can be derived using trigonometric calculations, especially arctangent to determine the yaw angle for movements in the x-direction. Preferably, it can be determined from the rotational speed values ​​or rotation rates of the tilt sensor whether a translational movement is taking place, from which the motion vector can subsequently be derived. In particular, a translation can be detected if the rotational speed values ​​approach zero. Preferably, automated calibration is enabled, allowing precise detection of translational movements even with an initial sensor offset from the motion vector – with the acceleration values ​​being further corrected by the roll and pitch values ​​determined by the tilt sensor. In a preferred first step, a translational movement of the motion unit is performed, at least temporarily, in the actual direction of movement. In a preferred second step, the relevant measurement data during the movement – ​​in particular the acceleration and / or rotational velocity values ​​– are acquired. This data is evaluated to determine the actual motion vector and to optimally adapt the sensor coordinate system to the actual direction of movement.In the preferred third step, a correction factor is taught in to transform an axis of the original sensor coordinate system to the determined translational motion vector. This conversion is preferably performed using a transformation matrix, enabling precise measurement of the translational motion regardless of the initial mounting orientation. The correction factor can also be manually validated or adjusted if necessary. For further optimization, the measured acceleration values ​​can preferably be corrected using the angle values ​​from the tilt sensor to ensure precise alignment of the sensor coordinate system with the actual motion vector under varying operating conditions. Preferably, the movement unit can be a mobile component of a working machine and / or a body part of a mobile working machine. The method according to the invention has the advantage of automatic calibration and adjustment of the sensor coordinate system to an actual direction of movement, so that the sensor unit can be installed in any given mounting position, even if this is spatially offset from an ideal axis of movement of the motion unit. This allows the sensor unit to be used for the precise measurement and adjustment of the axis position during translational movements of the motion unit. In other words, the method enables automatic axis calibration and compensation for assembly errors. It analyzes acceleration and / or rotational speed values ​​to detect sections of pure linear motion along one of the main axes of the motion unit. These sections serve as a reference. Trigonometric calculations based on this reference motion determine a correction factor that not only aligns the sensor data with the true direction of motion during this phase, but also corrects systematic deviations in sensor orientation due to assembly inaccuracies, preferably by incorporating additional tilt values. According to a preferred embodiment, the acceleration sensor is used to determine the speed of the motion unit, wherein, following commissioning, the detected acceleration values ​​are continuously adjusted by the current inclination values, in particular inclination angles, in order to correct an influence on the speed determination due to a changing orientation of the sensor coordinate system relative to a gravitational vector. Advantageously, this method ensures precise measurement of translational acceleration even under variable operating conditions. In particular, even if the start-up process is affected by the motion unit encountering hills, a precise velocity calculation can still be performed. In other words, following the correction of mounting offsets, the acceleration values ​​are continuously adjusted during operation using the current tilt angles. This allows for a precise determination of the actual translational acceleration even under variable operating conditions – such as cornering, uneven terrain, or other dynamic changes in tilt. Preferably, acceleration and / or rotational speed values ​​are evaluated to detect a temporary translational movement segment of the motion unit. This offers the advantage of flexible calibration by enabling the detection and adaptation to any movement. Therefore, it is not necessary for the movement to be predefined for calibration. In other words, the movement can be performed arbitrarily, with a time-limited translational movement segment being automatically detected and evaluated. An operator performing the movement thus does not need to pay attention to a precise direction of movement. Preferably, inclination values ​​can also be used for reference or correction. Any movement can be determined by measuring the rotation rate of the tilt sensor. In particular, a rotation rate approaching zero indicates a purely translational movement. According to the invention, the speed of the moving unit is measured using an accelerometer and, additionally, a radar sensor. This improves the reliability and accuracy of the speed measurement, with the two measurement methods being able to partially overlap redundantly or only be used temporarily if one of the measurement methods fails. For example, the speed measurement using the accelerometer can then be used if the radar signal fails or cannot be evaluated for speed measurement. This can occur, for example, if a reflected radar signal is disrupted due to external environmental conditions, in particular aqueous surfaces. Preferably, the calibration can be carried out taking into account environmental conditions such as vibrations or uneven terrain by filtering or compensating the sensor data accordingly. Additionally, it may be preferable to simultaneously capture and calibrate the translational movement in multiple axes of the sensor coordinate system. This can improve the precision of complex motion profiles. Furthermore, it is advantageous to read in pre-existing motion profiles of the motion unit. This can increase or simplify the efficiency of the calibration by utilizing existing motion profiles. In particular, the procedure can be adapted to different types of mobile machinery as motion units by using machine-specific motion profiles or calibration routines. Furthermore, it is conceivable that the calibration could be performed in real time during the operation of the mobile machine. In this case, the calibration could be dynamically adapted to changing operating conditions. The invention further relates to a sensor unit for determining the speed of a motion unit, which is connected to the motion unit in any mounting orientation and wherein the sensor unit is put into operation or is operated by means of a previously mentioned method. Preferably, the sensor unit comprises an accelerometer and a radar sensor to determine the speed of the moving unit, using the speed values ​​of the accelerometer if a radar signal is not available. Furthermore, the invention also relates to a motion unit with a previously mentioned sensor unit, wherein the motion unit is designed as a mobile working machine. The invention will now be explained in more detail using exemplary embodiments and with reference to the drawings. The figures show schematically: Fig. 1: perspective view of a mobile work machine with an offset accelerometer and tilt sensor, Fig. 2: perspective view of a moving body part of a construction machine with an offset accelerometer and tilt sensor. Figure 1 shows a motion unit 10, in particular a mobile field machine 14, with a sensor unit 16 mounted in an orientation that deviates from an ideal direction of motion b. The illustration demonstrates that a sensor coordinate system (x1, y1) does not exactly coincide with a motion vector (x2, y2) or a principal axis of the motion unit 10, which is a common occurrence in practice. This misalignment is a typical application scenario for a translational axis calibration method, since the sensor unit 16, despite its spatially offset mounting, is intended to enable precise measurements of the actual direction of motion b. For the commissioning of the sensor unit 16, comprising an accelerometer and an inclination sensor, a calibration procedure is carried out to perform a translational axis calibration of the sensor coordinate system (x1, y1). The procedure comprises the following steps: performing a translational movement of the motion unit 10, in particular along the direction of movement b; recording the acceleration and / or rotational velocity values ​​occurring during the translational movement, preferably also inclination values, in order to determine a motion vector (x2, y2), (x4, y4); and teaching in a correction factor to transform an axis of the original sensor coordinate system (x1, y1), (x3, y3) in the direction of the determined motion vector (x2, y2), (x4, y4). Figure 2 shows another embodiment using the example of a crane 11. Here, the sensor unit 16 with acceleration and tilt sensor is also mounted in a non-ideal position on a crane receiver 12 as a motion unit 10, such that the sensor coordinate system (x3, y3) deviates from the intended axis of motion b of the crane receiver 12 (x4, y4). Figure 2 further illustrates that automatic calibration may also be necessary for a moving part of a construction machine in order to detect the actual translational motion vector (x4, y4) and to compensate for any mounting misalignments of the sensor unit 16. Reference symbol list 10 Motion unit 11 Crane 12 Crane receiver 14 Mobile work machine for field use 16 Sensor unit b Motion axis of the motion unit (x1, y1), (x3, y3) Cartesian coordinate system of the sensor unit (x2, y2), (x4, y4) Motion vector and Cartesian coordinate system of the motion unit

Claims

Method for commissioning a sensor unit (16) comprising an accelerometer and / or tilt sensor connected to a motion unit (10) in any mounting orientation, the method comprising the following commissioning steps to perform translational axis calibration of a sensor coordinate system (x1, y1), (x3, y3): • Performing a translational movement of the motion unit (10), • Acquiring the acceleration and / or rotational velocity values ​​occurring during the translational movement to determine a motion vector (x2, y2), (x4, y4), • Teaching in a correction factor to transform an axis of the original sensor coordinate system (x1, y1), (x3, y3) in the direction of the determined motion vector (x2, y2), (x4, y4), wherein the velocity of the motion unit (10) is determined by means of the accelerometer and / or by means of a radar sensor.where, in the event of a failure or interference of the radar signal, the speed determination is carried out at least temporarily on the basis of acceleration values ​​which are transformed in the direction of the motion vector (x2, y2), (x4, y4) using the learned correction factor. Method according to claim 1, characterized in that the acceleration sensor is used to determine the speed of the motion unit (10), wherein the sensor unit (16) additionally comprises an inclination sensor, wherein, following commissioning, the detected acceleration values ​​are continuously adjusted by current inclination values ​​in order to correct an influence on the speed determination due to a changing orientation of the sensor coordinate system (x1, y1), (x3, y3) relative to a gravitational vector. Method according to claim 1 or 2, characterized in that the acceleration and / or rotational velocity values ​​are evaluated in order to detect a temporary translational movement section of the motion unit (10) and to capture the movement vector (x2, y2), (x4, y4) for this movement section in order to perform the calibration on the basis of a freely chosen movement. Method according to one of claims 1 to 3, characterized in that the speed of the motion unit (10) is measured by means of the acceleration sensor and additionally by means of the radar sensor in order to improve the precision and reliability of the speed determination. Method according to one of claims 1 to 4, characterized in that the translational movement in several axes of the sensor coordinate system (x1, y1), (x3, y3) is simultaneously detected and calibrated in order to precisely map complex motion profiles. Method according to one of claims 1 to 5, characterized in that previously known motion profiles of the motion unit (10) are read in, which are taken into account when determining the motion vector (x2, y2), (x4, y4). Method according to one of claims 1 to 6, characterized in that the calibration is carried out in real time during the operation of the motion unit (10), in particular a mobile working machine (14), in order to compensate for dynamic changes in the sensor position or the operating conditions. Sensor unit for determining the speed of a motion unit (10), which is connected to the motion unit (10) in any mounting orientation, and wherein the sensor unit (16) is commissioned or operated by means of a method according to one of claims 1 to 7, wherein the sensor unit (16) has an accelerometer and a radar sensor to determine the speed of the motion unit (10), wherein the speed values ​​of the accelerometer are used at least temporarily if a radar signal is not available. Motion unit with a sensor unit (16) according to claim 8, wherein the motion unit (10) is designed as a mobile working machine (14) or a working machine with a mobile component, wherein the sensor unit (16) is connected to the mobile component or a body part of the mobile working machine (14) in any mounting orientation.

Images