DE102021209427A1 - Method and device for determining at least one spatial position and orientation of at least one measurement object - Google Patents

Abstract

A measuring device (110) for determining at least one spatial position and orientation of a measurement object (112) is proposed. The measuring device (110) comprises at least one target ensemble (114) with at least three retroreflectors (116). The retroreflectors (116) of the target ensemble (114) have known coordinates in a target ensemble coordinate system (118). The measurement object (112) has the target ensemble (114). The measuring device (110) comprises at least six localization units (120). Each of the localization units (120) is set up to generate at least one illuminating light beam (122) and to illuminate at least one of the retroreflectors (116) with the illuminating light beam (122). Each of the retroreflectors (116) used to determine the position and orientation is illuminated by at least one of the localization units (120). Each of the localization units (120) is set up to receive at least one reflected light beam (124) from the retroreflector (116) it illuminates and to generate at least one measurement signal. The measuring device (110) also includes at least one evaluation unit (126), which is set up to determine the spatial position and orientation of the measurement object (112) from the measurement signals of the localization units (120). Determining the spatial position and orientation of the measurement object (112) comprises the following steps: i) determining at least one distance (128) from the respective localization unit (120) to the at least one retroreflector (116) illuminated by it from the measurement signal; andii) determining a 6D pose of the target ensemble (114) in a coordinate system (130) of the localization units (120) taking into account the known coordinates of the retroreflectors (116) in the target ensemble coordinate system (118) and the distances (128) determined in i) .

Description

technical field

The invention relates to a device for determining at least one spatial position and orientation of at least one measurement object, a coordinate measuring machine and a method for determining at least one spatial position and orientation of at least one measurement object. The present invention relates in particular to the field of coordinate measuring technology.

Technical background

Coordinate measuring machines and machine tools usually have a very stable mechanical design, but are typically not accurate enough to meet the requirements without computer-aided corrections, also known as "computer-assisted corrections" or CAA. Methods are therefore known which make it possible to detect the systematic errors in all six degrees of freedom of such a machine as a function of its position. These errors can be described, for example, as a position error, which indicates the translational error in the direction of the movement axis, two translation errors, which indicate the translational error in the two directions transverse to the movement axis, a roll error, which indicates the rotational error around the movement axis, and yaw - and a pitch error, which indicate the rotational error around the two axes transverse to the axis of movement.

Typical methods for detecting the errors use, for example, laser interferometers, in particular multi-beam laser interferometers, with which, for example, the position error can be detected directly and the two translation errors perpendicular to the axis of movement and yaw and pitch errors, in particular with the help of suitable optical attachments. Autocollimation telescopes can also be used to record yaw and pitch errors.

However, the methods described have a number of disadvantages, in particular that the errors cannot be detected in volume, but only by axis, since the detection area is straight and not all six degrees of freedom can be detected simultaneously. Even axis-by-axis detection can only be possible if translation axes are involved. In the case of rotary axes, for example in an articulated robot, this may no longer be possible. Alternatively, measurements can also be taken in space: but only along a space-straight path. The first problem can be solved by 3D multilateration. This includes multi-laser methods in which the 3D position of a target in space and thus also the incorrect movement of the machine in space can be determined. Such methods are known to those skilled in the art. The second problem can be solved by extending 3D multilateration, as in WO 2020/104666 . This describes the use of a target consisting of three retroreflectors that are installed in a fixed assembly and whose distances from one another are known. The position and orientation of these three targets can be determined by using six distance measurements. For certain applications, however, greater flexibility or the measurement of larger volumes may be necessary, which is difficult to implement with the known methods.

object of the invention

It is therefore the object of the present invention to provide a device and a method for determining at least one spatial position and orientation of a measurement object, which at least largely avoids the disadvantages of known devices and methods. In particular, it should be possible to determine the spatial position and orientation of the measurement object with greater flexibility and to measure larger volumes.

General Description of the Invention

This object is addressed by an apparatus and a method having the features of the independent patent claims. Advantageous developments, which can be implemented individually or in any combination, are presented in the dependent claims.

In the following, the terms "have", "have", "comprise" or "include" or any grammatical deviations thereof are used in a non-exclusive manner. Accordingly, these terms can refer both to situations in which, in addition to those indicated by these terms guided characteristics, no further characteristics are present, or to situations in which one or more further characteristics are present. For example, the phrase "A has B,""A has B,""A includes B," or "A includes B" can both refer to the situation in which there is no other element in A other than B (ie to a situation in which A consists exclusively of B), as well as to the situation in which, in addition to B, there are one or more other elements in A, e.g. element C, elements C and D or even further elements .

Furthermore, it is pointed out that the terms "at least one" and "one or more" as well as grammatical variations of these terms, if they are used in connection with one or more elements or features and are intended to express that the element or feature is provided once or several times can generally only be used once, for example when the feature or element is introduced for the first time. If the feature or element is subsequently mentioned again, the corresponding term “at least one” or “one or more” is usually no longer used, without restricting the possibility that the feature or element can be provided once or more than once.

Furthermore, the terms “preferably”, “particularly”, “for example” or similar terms are used below in connection with optional features, without alternative embodiments being restricted thereby. Thus, features introduced by these terms are optional features and are not intended to limit the scope of the claims, and in particular the independent claims, by these features. Thus, as will be appreciated by those skilled in the art, the invention may be practiced using other configurations. Similarly, features introduced by "in an embodiment of the invention" or by "in an exemplary embodiment of the invention" are understood as optional features without intending to limit alternative configurations or the scope of the independent claims. Furthermore, through these introductory expressions, all possibilities to combine the features introduced here with other features, be they optional or non-optional features, remain untouched.

1. i) Bestimmen mindestens einer Distanz von der jeweiligen Lokalisierungseinheit zu dem mindestens einen von dieser beleuchteten Retroreflektor aus dem Messsignal; und
2. ii) Bestimmen einer 6D-Pose des Targetensembles in einem Koordinatensystem der Lokalisierungseinheiten unter Berücksichtigung der bekannten Koordinaten der Retroreflektoren im Targetensemble-Koordinatensystem und der in i) bestimmten Distanzen.

In a first aspect of the present invention, a measuring device for determining at least one spatial position and orientation of a measurement object is proposed. The measuring device comprises at least one target ensemble with at least three retroreflectors. The target ensemble retroreflectors have known coordinates in a target ensemble coordinate system. The measurement object has the target ensemble. The measuring device comprises at least six localization units. Each of the localization units is set up to generate at least one illuminating light beam and to illuminate at least one of the retroreflectors with the illuminating light beam. Each of the retroreflectors used to determine the position and orientation is illuminated by at least one of the localization units. Each of the localization units is set up to receive at least one reflected light beam from the retroreflector it illuminates and to generate at least one measurement signal. The measuring device comprises at least one evaluation unit which is set up to determine the spatial position and orientation of the measurement object from the measurement signals of the localization units. Determining the spatial position and orientation of the measurement object includes the following steps:

1. i) determining at least one distance from the respective localization unit to the at least one retroreflector illuminated by it from the measurement signal; and
2. ii) determining a 6D pose of the target ensemble in a coordinate system of the localization units, taking into account the known coordinates of the retroreflectors in the target ensemble coordinate system and the distances determined in i).

Within the scope of the present invention, a “measurement object” can be understood as an object to be measured that is of any shape. For example, the measurement object can be a measuring head of a sensor or a tool with which a component can be scanned. The measurement object can in particular be an end effector of a coordinate measuring machine or a machine tool.

In the context of the present invention, a “measuring device” can be understood to mean a device which is set up to determine the at least one spatial position and orientation of the measurement object. The spatial position and orientation can be determined in a coordinate system, for example a Cartesian coordinate system or a spherical coordinate system. Other coordinate systems are also conceivable. The determination of the spatial The position and orientation of the measurement object can take place in a coordinate system using at least one further coordinate system, as described in more detail below. The coordinate systems used can differ, for example, in the position of their origin, also referred to as the coordinate origin or zero point. The coordinate systems can be converted into one another, for example by at least one transformation.

A “spatial position” can be understood within the scope of the present invention as a three-dimensional point (X, Y, Z) in a coordinate system, in particular a position of the measurement object. The spatial position can be defined by the location coordinates X, Y and Z. An “orientation” can be understood as meaning a position in space, in particular a rotation, of the measurement object, in particular an angular position. The orientation can be specified by at least three angles, for example Euler angles or pitch angles and roll angles and yaw angles. The spatial position and orientation of the measurement object can also be referred to as six-dimensional information or 6D information.

A “retroreflector”, also referred to as a reflector, can be understood within the scope of the present invention as any device which reflects a light beam in the direction from which the light beam arrived. For example, the retroreflector can be a marker. For example, the retroreflector can be selected from the group consisting of: a cat's eye; a cat's eye with a reflective layer; a marker described in U.S. 2011/0007326 A1 , U.S. 2013/0050410 A1 or US 2017/0258531 A1 , the content of which is hereby incorporated into this application; a cube prism; a corner cube. The retroreflectors can each have at least one holder for arranging and/or attaching the retroreflectors to the measurement object.

In the context of the present invention, a “target” can be understood to mean a retroreflector whose position is to be determined. Within the scope of the present invention, a “target ensemble” can be understood to mean an entirety of the retroreflectors arranged on the measurement object. The target ensemble can have a plurality of retroreflectors, for example three, four, five, six or more retroreflectors. Applications are also conceivable in which the measuring device can have a plurality of target ensembles.

The target ensemble retroreflectors have known coordinates in a target ensemble coordinate system.

In the context of the present invention, a “coordinate system” can be understood to mean a mathematical system which is suitable for clearly describing the position of a point in space using coordinates. Different coordinate systems are conceivable. For example, the coordinate system can be a Cartesian coordinate system or a spherical coordinate system. Within the scope of the present invention, the term “coordinate” can be understood as a numerical specification that at least partially describes a position of a point in a space, in particular with respect to an axis of the coordinate system used. For example, the position in a Cartesian coordinate system can be clearly described by the three coordinates X, Y and Z, which can also be referred to as location coordinates. Within the scope of the present invention, a “target ensemble coordinate system” can be understood to mean a coordinate system which has at least one spatial reference, in particular at least one predetermined spatial reference, to the position of at least one of the retroreflectors of the target ensemble. In particular, the origin of the target ensemble coordinate system can be defined in relation to the position of at least one of the retroreflectors of the target ensemble. For example, the origin of the target ensemble coordinate system can be located at the position of one of the retroreflectors. Further spatial references, in particular to the positions of the further retroreflectors, are possible and are explained further below by way of example.

The measuring device comprises at least six localization units and at least three retroreflectors. In the context of the present invention, a “localization unit” can basically be understood to mean any device that is set up to generate at least one item of localization information. The localization information can be selected from at least one piece of information from the group consisting of: a measurement signal depending on the location of the retroreflector illuminated by the localization unit; information about a distance or distance from the retroreflector illuminated by the localization unit to the localization unit; information about a position of the retroreflector illuminated by the localization unit relative to the localization unit; and information about a change in length. The localization units can be set up for an incremental interferometric distance measurement. The localization units can be set up for an absolute distance measurement. Within the scope of the present invention, “distance”, also referred to as distance or distance, can be understood to mean a relative distance, for example a relative change in position, or an absolute distance. When using incrementally measuring interferometers, which by definition can only detect changes in distance, the so-called "dead zone" can be determined in a preceding step and the absolute distance can be deduced. This degree of freedom can also be part of the target function.

Each of the localization units can be set up to illuminate at least one of the retroreflectors with the illuminating light beam. Each of the retroreflectors used to determine the position and orientation is illuminated by at least one of the localization units. A retroreflector can be illuminated by a plurality of locating units. The illumination of the retroreflectors by the localization units can be done as in WO 2020/104666 described.

The measuring device has at least three retroreflectors and at least six localization units. A position of the localization units and a position of the retroreflectors can each be linearly independent of one another. An association, also referred to as "mapping", configuration or lighting scheme, which indicates which retroreflector is illuminated by which localization unit and/or which localization unit illuminates which retroreflector, can be known.

In one embodiment, the measuring device can have exactly three retroreflectors and six localization units. One, in particular a first, of the retroreflectors can be illuminated by three of the locating units. One of the two further retroreflectors, in particular a second retroreflector, can be illuminated by two of the three further localization units. The further retroreflector, in particular a third retroreflector, can be illuminated by the one remaining one of the six localization units. Such a configuration may also be abbreviated or referred to as (three-two-one).

In a further embodiment, the measuring device can comprise three retroreflectors and seven localization units. One, in particular a first, of the retroreflectors can be illuminated by three of the locating units. One of the two further retroreflectors, in particular a second retroreflector, can be illuminated by two of the four further localization units. The further retroreflector, in particular a third retroreflector, can be illuminated by the two remaining of the seven localization units. Such a configuration may also be abbreviated or referred to as (three-two-two).

In a further embodiment, the measuring device can comprise seven retroreflectors and seven localization units. In this embodiment, each of the seven retroreflectors can be illuminated by exactly one of the seven localization units. Conversely, in this embodiment, each of the seven localization units can illuminate exactly one of the seven retroreflectors. Such a configuration may also be abbreviated or referred to as (one-one-one-one-one-one-one).

The measuring device can have a control unit. In the context of the present invention, a “control unit” can basically be understood to mean a device that is set up to control or regulate at least one component or one process. For example, the control unit can have at least one data processing device, for example at least one computer or microcontroller. The control unit can be designed in particular as a central control unit for the entire measuring device. Alternatively, however, a decentralized control unit with a plurality of individual components that cooperate with one another is also possible. The control unit can also have at least one user interface, for example at least one keyboard and/or at least one display. The control unit can be set up to align the localization units relative to the retroreflectors.

Each of the localization units is set up to generate at least one illuminating light beam and to illuminate at least one of the retroreflectors with the illuminating light beam. In the context of the present invention, an “illuminating light beam” can basically be understood to mean any light beam that is emitted and/or sent out in order to illuminate the retroreflector. In particular, the illuminating light beam can be a light beam generated by one of the localization units for illuminating one of the retroreflectors. The localization units can each have at least one lighting unit. The lighting unit can have a light source have, in particular a laser source. In the context of the present invention, “light” can be understood to mean electromagnetic radiation in at least one spectral range selected from the visible spectral range, the ultraviolet spectral range and the infrared spectral range. The term visible spectral range basically covers a range from 380 nm to 780 nm. The term infrared (IR) spectral range basically covers a range from 780 nm to 1000 µm, with the range from 780 nm to 1.4 µm being referred to as near infrared (NIR), and the range from 15 µm to 1000 µm is called far infrared (FIR). The term ultraviolet basically includes a spectral range from 100 nm to 380 nm. Within the scope of the present invention, a “ray of light” can basically be understood to mean a quantity of light which is emitted and/or transmitted in a specific direction.

Each of the localization units may comprise at least one element selected from the group consisting of: a laser tracker; a LIDAR sensor, an FMCW LIDAR sensor.

In the context of the present invention, a “laser tracer”, also referred to as “laser tracker”, can in principle be understood to mean any desired tracking interferometer. In the context of the present invention, a “tracking interferometer” can be understood to mean an interferometer that is set up to track a position of a retroreflector at different points in time. The laser tracer can be set up to follow a retroreflector moving in space by means of a laser beam, in particular in order to determine spatial coordinates of the moving retroreflector and/or of a measurement object connected to the retroreflector.

In the context of the present invention, a “LIDAR sensor” can basically be understood to mean any device which is based on the LIDAR (“light detection and ranging”) measurement principle, also known as LADAR (laser detection and ranging). In particular, the LIDAR sensor can be set up to generate and receive a light beam, for example a laser beam, in particular the light beam previously emitted by it and reflected back to it, and from this to determine a distance between the LIDAR sensor and the retroreflector, for example exploiting differences in return times and wavelengths. The localization unit can preferably have an FMCW LIDAR sensor. "FMCW" is an abbreviation for the English expression "Frequency Modulated Continuous Wave". The FMCW LIDAR sensor can be set up to generate the light beam, the frequency of which is continuously tuned according to the FMCW method. For example, the frequency of the light beam can be linearly modulated with time. A combination of LIDAR methods and FMCW methods are known in principle to those skilled in the art, for example from Chipscale Lidar, Benham Behroozpur Baghmisheh, Technical Report no. UCB/EECS.2017-4. For example, the LIDAR unit as in U.S. 9,559,486 B2 , U.S. 8,913,636 B2 or U.S. 2016/123718 A1 be designed. FMCW LIDAR sensors are more robust and less expensive than laser tracers.

Each of the localization units is set up to receive at least one reflected light beam from the retroreflector it illuminates and to generate at least one measurement signal in response to the reflected light beam. In the context of the present invention, a “measurement signal” can basically be understood to mean any, in particular an electrical, signal, for example a voltage or a current, which was generated according to the reflected, received light beam or using the reflected, received light beam.

The measuring device also has at least one evaluation unit. Within the scope of the present invention, an “evaluation unit” can be understood to mean a device which is set up to carry out one or more evaluation steps. For example, the evaluation unit can have at least one data processing device, for example at least one computer or microcontroller. The evaluation unit can be designed in particular as a central evaluation unit for the entire measuring device. Alternatively, however, a decentralized evaluation unit with a number of individual components that cooperate with one another is also possible. The evaluation unit can be part of the localization units or another device. The evaluation unit can also have at least one user interface, for example at least one keyboard and/or at least one display.

The evaluation unit is set up to determine the spatial position and orientation of the measurement object from the measurement signals of the localization units. The evaluation unit can be set up to process the measurement signals from the localization units. Determining the spatial position and orientation of the measurement object by the evaluation unit includes determining at least one distance, in particular a distance, from the respective localization unit to the at least one retroreflector illuminated by it from the measurement signal. For example, the evaluation unit can be set up to determine a distance between the LIDAR sensor and the retroreflector from the measurement signal of the LIDAR sensor, for example by evaluating differences in return times and wavelengths. Methods of this type for determining a distance or a change in distance from measurement signals from the localization units are known to those skilled in the art.

Determining the spatial position and orientation of the measurement object also includes determining a 6D pose of the target ensemble in a coordinate system of the localization units, taking into account the known coordinates of the retroreflectors in the target ensemble coordinate system and the distances determined in i). In particular, a 6D pose of the target ensemble can be determined in the coordinate system of the localization units, taking into account the known coordinates of the retroreflectors in the target ensemble coordinate system, the known coordinates of the localization units in the localization coordinate system and the distances determined in i). Within the scope of the present invention, a “6D pose of the target ensemble” can be understood to mean six-dimensional information which defines the spatial position and orientation of the target ensemble. As stated above, the measurement object has the target ensemble, so that the 6D pose of the target ensemble can correspond to the 6D pose of the measurement object, and in particular to the spatial position and orientation of the measurement object, or the spatial position and orientation of the measurement object from the 6D pose of the target ensemble can be determined.

To determine the 6D position of the measurement object, the target ensemble to be measured can be described in its own coordinate system, the target ensemble coordinate system. The coordinates of the retroreflectors in the target ensemble coordinate system may be previously known and/or predetermined. For example, the coordinates of the retroreflectors in the target ensemble coordinate system can be determined, e.g. in a previous step, and can be assumed to be fixed and correct for the determination of the pose. For example, the coordinates of the retroreflectors in the target ensemble coordinate system can be stored in a data memory of the evaluation unit, for example in the form of a lookup table.

The target ensemble coordinate system can be a Cartesian coordinate system. For example, one of the retroreflectors, in particular a first retroreflector, can be arranged in an origin of the Cartesian coordinate system in the target ensemble coordinate system. One of the further retroreflectors, in particular a second retroreflector, can be arranged on one of the axes of the Cartesian coordinate system. For example, the second retroreflector can be on the X-axis. A further retroreflector, in particular a third retroreflector, can be arranged in a plane which is spanned by the aforementioned axis and another axis of the Cartesian coordinate system, for example in the XY plane. Alternatively or additionally, the target ensemble coordinate system can also be defined by permutations: for example, the second reflector can be arranged on the Y or Z axis and the third reflector can then be arranged in YZ or XZ. The target ensemble coordinate system can be unambiguously described and/or defined by such an alignment of the target ensemble coordinate system with respect to three of the at least three retroreflectors. If more than three retroreflectors are provided, the additional retroreflectors can be described in the target ensemble coordinate system. According to the invention, the target ensemble is thus not described by the distances between the targets, but these are described in a separate, preferably Cartesian, coordinate system.

For example, the target ensemble coordinate system can be chosen as follows. For example, the first retroreflector can be located at the origin of the target ensemble coordinate system. Accordingly, the coordinates of the first retroreflector in the target ensemble coordinate system may be R ₁ = [0|0|0]. The second retroreflector may be located on the X-axis of the target ensemble coordinate system. The coordinates of the second retroreflector may be R ₂ = [x ₂ |0|0] in the target ensemble coordinate system. The X coordinate x ₂ cannot be equal to 0. The X coordinate can be x ₂ > 0 or x ₂ < 0. The third retroreflector can be arranged in the XY plane. The coordinates of the third retroreflector may be R ₃ = [x ₃ |y ₃ |0] in the target ensemble coordinate system. The X coordinate x ₃ and the Y coordinate y ₃ can be non-zero. The Y coordinate can be y ₃ > 0 or y ₃ < 0. The X ₃ coordinate can be x3 !=0; the sign of x ₃ depends on the sign of x ₂ . Coordinates of further retroreflectors, for example a fourth to nth retroreflector, of the target ensemble can be defined in the target ensemble coordinate system as R ₄ = [x ₄ |y ₄ |z ₄ ]... R _n = [x _n |y _n |z _n ] are specified. A different orientation, choice or positioning of the target ensemble coordinate system is also possible. If three retroreflectors are used, 3 items of position information of the retroreflectors result nander, these being in the form of Cartesian coordinates. Each additional retroreflector to be used can be specified accordingly in this coordinate system.

It is pointed out that both in this example and in the following examples, the ordinal numbers of the retroreflectors or also, in the following examples, of the localization units are used as designations for differentiation. Accordingly, the retroreflectors may be interchangeable or interchangeable. The localization units in the following examples can also be interchangeable or interchangeable. Based on the above example, the second retroreflector or the third retroreflector can be arranged at the origin of the target ensemble coordinate system, for example, instead of the first retroreflector. Other swaps are possible.

The evaluation unit can be set up to determine the spatial position and orientation of the measurement object using the following multilateration method. In the context of the present invention, a “multilateration method” can basically be understood as any method for determining the spatial position of at least one point, the method being based on the use of distances between the point and a plurality of other points. The distances can be determined by determining the distance in step i). The evaluation unit can be set up to solve a linear system of equations to determine the spatial position and orientation of the measurement object. The target function for solving the system of linear equations is not the XYZ position of the individual targets, but the 6D pose of the target ensemble coordinate system in the coordinate system of the localization units. The unknown that defines the 6D pose in the coordinate system of the localization units can be described by a transformation matrix "T". The transformation matrix can transform the target ensemble coordinate system into the coordinate system of the localization units. Such a transformation matrix can include the information about the translational and rotational position. The evaluation unit can be set up to determine the transformation matrix for determining the 6D pose of the target ensemble in the coordinate system of the localization units.

In the context of the present invention, a “coordinate system of the localization units” can be understood to mean a coordinate system which has at least one spatial reference, in particular at least one predefined spatial reference, to the position of at least one of the localization units. In particular, the origin of the coordinate system of the localization units can be defined in relation to the position of at least one of the localization units. For example, the origin of the coordinate system of the localization units can be arranged in the position of one of the localization units. The coordinate system of the localization units can be a Cartesian coordinate system. Coordinates of the localization units in the localization coordinate system can be known, in particular previously known. For example, the necessarily known position of the localization units can be described in more detail in the coordinate system of the localization units. One of the localization units, for example a first localization unit, can be arranged in an origin of the Cartesian coordinate system. One of the further localization units, in particular a second localization unit, can be arranged on one of the axes of the Cartesian coordinate system, for example a positive X-axis of the coordinate system of the localization units. A further localization unit, in particular a third localization unit, can be arranged in a plane which is spanned by the aforementioned axis and another axis of the Cartesian coordinate system, for example in the XY plane. All conceivable permutations are possible. If more than three localization units are provided, then the further localization units can be clearly described in the coordinate system of the localization units. The coordinates of the localization units in the localization coordinate system can be determined in an upstream calibration process, in which the position of the localization units is determined.

In the context of the present invention, a “transformation matrix” can be understood to mean a matrix by means of which a coordinate transformation can be carried out. The transformation matrix can have rows and columns. For example, a transformation matrix can include m rows, n columns and m×n entries. The transformation matrix T can, for example, be a 4×4 matrix, ie a matrix with four rows and four columns. For example, the coordinates of the same point in the coordinate system of the localization units can be determined or calculated using the transformation matrix from the coordinates of a point in the target ensemble coordinate system. The transformation can include a translation, ie a displacement of the coordinate system, and/or a rotation, ie a rotation of the coordinate system. For example, the transformation matrix can be structured as follows: $$T=\left[\begin{array}{cc}D& t_{xy\mathrm{e.g}}\\ 0& 1\end{array}\right]$$

Here D is a rotation matrix, also called a rotation matrix, for which the following applies: $$D=D_{\mathrm{e.g}}\cdot D_y\cdot D_x=\left[\begin{array}{ccc}\text{cos}g& -\text{<figure-callout id="0" label="sin g" filenames="DE102021209427A1\_0015.png" state="{{state}}">sin</figure-callout>}g& 0\\ \text{sin}\mathrm{<figure-callout\; id="0"\; label="g\; cos\; g"\; filenames="DE102021209427A1\_0015.png"\; state="\{\{state\}\}">g</figure-callout>}& \text{cos}g& 0\\ 0& 0& 1\end{array}\right]\cdot \left[\begin{array}{ccc}\text{cos}\beta & 0& \text{<figure-callout id="0" label="sin β" filenames="DE102021209427A1\_0015.png" state="{{state}}">sin</figure-callout>}\beta \\ 0& 1& 0\\ -\text{<figure-callout id="0" label="sin β" filenames="DE102021209427A1\_0015.png" state="{{state}}">sin</figure-callout>}\beta & 0& \text{cos}\beta \end{array}\right]\cdot \left[\begin{array}{ccc}1& 0& 0\\ 0& \text{cos}a& -\text{sin}a\\ 0& \text{sin}a& \text{cos}a\end{array}\right]$$

In this case, D _z describes a rotation about the Z axis by the angle γ, D _y describes a rotation about the Y axis by the angle β and D _x describes a rotation about the X axis by the angle α. Furthermore, t _xyz describes a translation, the following applies: $$t_{xy\mathrm{e.g}}={\left[\begin{array}{ccc}{t}_x& t_y& t_{\mathrm{e.g}}\end{array}\right]}^T$$

The target function for determining the parameters of the transformation matrix T can be described as "the measured distance l _i,m of the i-th localization unit to its targeted retroreflector R at the m-th measurement position corresponds to the distance of the multiplied by the transformation matrix T, position of the from the i-th localization unit illuminated retroreflector P _R,map ( _i ) in the target ensemble coordinate system to the position of the i-th localization unit P _T,i in the coordinate system of the localization units”: $$\begin{array}{c}{l}_{i,m}=\left|P_{T,i}-T\cdot P_{R,map\left(i\right)}\right|=\\ \sqrt{{\left(P_{T,i}-T\cdot P_{R,map\left(i\right)}\right)}_x^2+{\left(P_{T,i}-T\cdot P_{R,map\left(i\right)}\right)}_{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="DE102021209427A1\_0014.png,DE102021209427A1\_0015.png"\; state="\{\{state\}\}">y</figure-callout>}}^2+{\left(P_{T,i}-T\cdot P_{R,map\left(i\right)}\right)}_{\mathrm{e.g}}^2}.\end{array}$$

The parameters of the transformation matrix T can be determined iteratively. For this purpose, the evaluation unit can be set up to solve an optimization problem. Solving the optimization problem may involve minimizing an error function F with $$f=\left|P_{T,i}-T\cdot P_{R,map\left(i\right)}\right|-l_{i,m}.$$

In a further aspect of the present invention, a coordinate measuring machine for measuring at least one workpiece is proposed. The coordinate measuring machine comprises at least one measuring device according to one of the embodiments described above or according to one of the embodiments explained further below. Furthermore, the coordinate measuring machine has at least one measurement object, which is set up to scan the workpiece.

In the context of the present invention, a “coordinate measuring machine” can basically be understood to mean any device that is set up to record at least one spatial coordinate of an object, for example an X, Y or Z coordinate of a Cartesian coordinate system or a spherical coordinate of a spherical coordinate system or to determine. Within the scope of the present invention, a “measurement” of an object can be understood to mean the determination, the derivation and/or the registration of at least one property of the object. In particular, the property can be a distance of the object from the measurement object and/or a position, location or position of the object in space or relative to the measurement object. The property can also be a texture, for example a surface texture. In the context of the present invention, a “workpiece” can in principle be understood as any object whose measurement is required or desired, for example, as part of a work process, in particular for aligning the object. Within the scope of the present invention, “scanning” of the workpiece can in principle be understood to mean that the measurement object interacts with the workpiece. This can be, for example, a tactile or an optical scanning.

1. a) Bereitstellen des mindestens einen Messobjekts, wobei das Messobjekt das Targetensemble aufweist, wobei das Targetensemble die Retroreflektoren aufweist, wobei die Retroreflektoren des Targetensembles bekannte Koordinaten in einem Targetensemble-Koordinatensystem aufweisen;
2. b) Erzeugen des mindestens einen Beleuchtungslichtstrahls mit jeder der Lokalisierungseinheiten und Beleuchten der Retroreflektoren mit den Beleuchtungslichtstrahlen, wobei jede der Lokalisierungseinheiten mindestens einen der Retroreflektoren beleuchtet, wobei jeder der zur Bestimmung der Position und Orientierung herangezogenen Retroreflektoren von mindestens einer der Lokalisierungseinheiten beleuchtet wird;
3. c) Empfangen jeweils mindestens eines der von den Retroreflektoren reflektierten Lichtstrahlen und Erzeugen mindestens eines Messsignals mit jeder der Lokalisierungseinheiten, wobei jede der Lokalisierungseinheiten den reflektierten Lichtstrahl des von ihr beleuchteten Retroreflektors empfängt;
4. d) Bestimmen der räumlichen Position und Orientierung des Messobjekts aus den Messsignalen der Lokalisierungseinheiten mit der mindestens einen Auswerteeinheit, wobei das Bestimmen der räumlichen Position und Orientierung des Messobjekts die folgenden Schritte umfasst:
   1. A) Bestimmen der Distanz von der jeweiligen Lokalisierungseinheit zu dem mindestens einen von dieser beleuchteten Retroreflektor aus dem Messsignal; und
   2. B) Bestimmen der 6D-Pose des Targetensembles in dem Koordinatensystem der Lokalisierungseinheiten unter Berücksichtigung der bekannten Koordinaten der Retroreflektoren in dem Targetensemble-Koordinatensystem, insbesondere der bekannten Koordinaten der Lokalisierungseinheiten im Lokalisierungskoordinatensystem, und der in A) bestimmten Distanzen.

In a further aspect of the present invention, a method for measuring at least one measurement object with a measuring device according to one of the above-described or according to a of the embodiments detailed below. The procedure includes the following steps:

1. a) providing the at least one measurement object, the measurement object having the target ensemble, the target ensemble having the retroreflectors, the retroreflectors of the target ensemble having known coordinates in a target ensemble coordinate system;
2. b) generating the at least one illumination light beam with each of the localization units and illuminating the retroreflectors with the illumination light beams, each of the localization units illuminating at least one of the retroreflectors, each of the retroreflectors used to determine the position and orientation being illuminated by at least one of the localization units;
3. c) receiving in each case at least one of the light beams reflected by the retroreflectors and generating at least one measurement signal with each of the localization units, each of the localization units receiving the reflected light beam of the retroreflector illuminated by it;
4. d) Determining the spatial position and orientation of the measurement object from the measurement signals of the localization units with the at least one evaluation unit, the determination of the spatial position and orientation of the measurement object comprising the following steps:
   1. A) determining the distance from the respective localization unit to the at least one retroreflector illuminated by it from the measurement signal; and
   2. B) Determining the 6D pose of the target ensemble in the coordinate system of the localization units considering the known coordinates of the retroreflectors in the target ensemble coordinate system, in particular the known coordinates of the localization units in the localization coordinate system, and the distances determined in A).

With regard to embodiments and definitions, reference can be made to the above description of the measuring device and the coordinate measuring machine. The method steps can be carried out in the order given, with one or more of the steps being able to be carried out at least partially simultaneously and with one or more of the steps being able to be repeated several times. In addition, other steps, whether or not mentioned here, can additionally be performed.

For example, the determination of the spatial position and orientation of the measurement object in step d) can be preceded by a determination of the coordinates of the retroreflectors in the target ensemble coordinate system.

Furthermore, within the scope of the present invention, a computer program is proposed which, when run on a computer or computer network, executes at least step d) of the method for measuring the measurement object in one of its configurations.

Furthermore, within the scope of the present invention, a computer program with program code means is proposed in order to carry out at least step d) of the method according to the invention in one of its configurations when the program is run on a computer or computer network. In particular, the program code means can be stored on a computer-readable data carrier.

In particular, the program code means can be stored on a computer-readable data carrier and/or a computer-readable storage medium.

As used herein, the terms "computer-readable data carrier" and "computer-readable storage medium" may refer in particular to non-transitory data storage, for example a hardware data storage medium on which computer-executable instructions are stored. The computer-readable data carrier or the computer-readable storage medium can in particular be or include a storage medium such as a random access memory (RAM) and/or a read-only memory (ROM).

In addition, within the scope of the present invention, a data carrier is proposed on which a data structure is stored which, after loading into a working and/or main memory of a computer ters or computer network can execute the method according to the invention in one of its configurations.

A computer program product with program code means stored on a machine-readable carrier is also proposed within the scope of the present invention in order to carry out the method according to the invention in one of its configurations when the program is executed on a computer or computer network.

A computer program product is understood as the program as a tradable product. In principle, it can be in any form, for example on paper or on a computer-readable data medium, and can be distributed in particular via a data transmission network.

Finally, within the scope of the present invention, a modulated data signal is proposed, which contains instructions that can be executed by a computer system or computer network for executing a method according to one of the described embodiments.

With regard to the computer-implemented aspects of the invention, one, several or even all method steps of the method according to one or more of the configurations proposed here can be carried out by means of a computer or computer network. Thus, in general, any of the method steps including the provision and/or manipulation of data can be performed using a computer or computer network. In general, these steps may include any of the method steps excluding steps that require manual labor, such as providing the measurement object and/or certain aspects of performing actual measurements.

The devices according to the invention, in particular the measuring device and the coordinate measuring machine, and the method according to the invention have numerous advantages over known devices and methods. In this way, increased flexibility with regard to possible applications and the measurement of larger volumes can be possible. The devices according to the invention, in particular the measuring device and the coordinate measuring machine, and the method according to the invention can use target ensembles with different numbers of at least three retroreflectors.

• Ausführungsform 1: Messvorrichtung zur Bestimmung von mindestens einer räumlichen Position und Orientierung eines Messobjekts, wobei die Messvorrichtung umfasst
  • - mindestens ein Targetensemble mit mindestens drei Retroreflektoren, wobei die Retroreflektoren des Targetensembles bekannte Koordinaten in einem Targetensemble-Koordinatensystem aufweisen, wobei das Messobjekt das Targetensemble aufweist,
  • - mindestens sechs Lokalisierungseinheiten wobei jede der Lokalisierungseinheiten eingerichtet ist, mindestens einen Beleuchtungslichtstrahl zu erzeugen und mindestens einen der Retroreflektoren mit dem Beleuchtungslichtstrahl zu beleuchten, wobei jeder der zur Bestimmung der Position und Orientierung herangezogenen Retroreflektoren von mindestens einer der Lokalisierungseinheiten beleuchtet ist, wobei jede der Lokalisierungseinheiten eingerichtet ist, von dem von ihr beleuchteten Retroreflektor mindestens einen reflektierten Lichtstrahl zu empfangen und mindestens ein Messsignal zu erzeugen,

• - mindestens eine Auswerteeinheit, welche eingerichtet ist, aus den Messsignalen der Lokalisierungseinheiten die räumliche Position und Orientierung des Messobjekts zu bestimmen, wobei das Bestimmen der räumlichen Position und Orientierung des Messobjekts die folgenden Schritte umfasst:
  1. i. Bestimmen mindestens einer Distanz von der jeweiligen Lokalisierungseinheit zu dem mindestens einen von dieser beleuchteten Retroreflektor aus dem Messsignal,
  2. ii. Bestimmen einer 6D-Pose des Targetensembles in einem Koordinatensystem der Lokalisierungseinheiten unter Berücksichtigung der bekannten Koordinaten der Retroreflektoren im Targetensemble-Koordinatensystem und der in i) bestimmten Distanzen.

In summary, the following embodiments are particularly preferred within the scope of the present invention:

• Embodiment 1 Measuring device for determining at least one spatial position and orientation of a measurement object, the measuring device comprising
  • - at least one target ensemble with at least three retroreflectors, the retroreflectors of the target ensemble having known coordinates in a target ensemble coordinate system, the measurement object having the target ensemble,
  • - at least six localization units, each of the localization units being set up to generate at least one illumination light beam and to illuminate at least one of the retroreflectors with the illumination light beam, each of the retroreflectors used to determine the position and orientation being illuminated by at least one of the localization units, each of the localization units is set up to receive at least one reflected light beam from the retroreflector it illuminates and to generate at least one measurement signal,

• - at least one evaluation unit, which is set up to determine the spatial position and orientation of the measurement object from the measurement signals of the localization units, the determination of the spatial position and orientation of the measurement object comprising the following steps:
  1. i. Determining at least one distance from the respective localization unit to the at least one retroreflector illuminated by it from the measurement signal,
  2. ii. Determining a 6D pose of the target ensemble in a coordinate system of the localization units, taking into account the known coordinates of the retroreflectors in the target ensemble coordinate system and the distances determined in i).

Embodiment 2 Measuring device according to the previous embodiment, wherein the evaluation unit is set up to determine a transformation matrix for determining the 6D pose of the target ensemble in the coordinate system of the localization units.

Embodiment 3 Measuring device according to the previous embodiment, wherein the transformation matrix is set up to transform the target ensemble coordinate system into the coordinate system of the localization units.

• - wobei P_T,i die Position der i-ten Lokalisierungseinheit im Koordinatensystem der Lokalisierungseinheiten ist,
• - wobei T die Transformationsmatrix ist,
• - wobei P_R, _map(i) die Position des von der i-ten Lokalisierungseinheit beleuchteten, m-ten Retroreflektors im Targetensemble-Koordinatensystem ist, und
• - wobei 1_i,m die von der Auswerteeinheit bestimmte Distanz der i-ten Lokalisierungs-einheit zu dem von dieser beleuchteten, m-ten Retroreflektor ist.

Embodiment 4 Measuring device according to one of the two previous embodiments, wherein the evaluation unit is set up to solve an optimization problem for determining components of the transformation matrix, wherein solving the optimization problem includes minimizing an error function F with $$f=\left|P_{T,i}-T\cdot P_{R,map\left(i\right)}\right|-l_{i,m}$$

• - where P _T,i is the position of the i-th localization unit in the localization unit coordinate system,
• - where T is the transformation matrix,
• - where P _R , _map(i) is the position of the m th retroreflector illuminated by the i th localization unit in the target ensemble coordinate system, and
• - where 1 _i,m is the distance, determined by the evaluation unit, between the i-th localization unit and the m-th retroreflector illuminated by it.

Embodiment 5: Measuring device according to one of the preceding embodiments, wherein the target ensemble coordinate system is a Cartesian coordinate system, wherein one of the retroreflectors is arranged in an origin of the Cartesian coordinate system, wherein one of the further retroreflectors is arranged on one of the axes of the Cartesian coordinate system, wherein one of the at least one further retroreflector is arranged in a plane which includes the aforementioned axis and a further axis of the Cartesian coordinate system.

Embodiment 6 Measuring device according to one of the two previous embodiments, wherein the coordinate system of the localization units is a Cartesian coordinate system.

Embodiment 7: Measuring device according to one of the preceding embodiments, wherein each of the localization units comprises at least one element selected from the group consisting of: a laser tracker; a LIDAR sensor, an FMCW LIDAR sensor.

Embodiment 8: Measuring device according to one of the preceding embodiments, wherein each of the localization units comprises at least one element selected from the group consisting of: a laser; a LIDAR unit, preferably an FMCW LIDAR unit.

Embodiment 9: Measuring device according to one of the preceding embodiments, wherein the measuring device comprises six localization units and three retroreflectors.

Embodiment 10: Measuring device according to one of the preceding embodiments, wherein the measuring device comprises seven localization units and three retroreflectors.

Embodiment 11: Measuring device according to one of the preceding embodiments, wherein the measuring device comprises seven localization units and seven retroreflectors.

Embodiment 12 Measuring device according to one of the preceding embodiments, wherein the measuring device also has a control unit, wherein the control unit is set up to align the localization units relative to the retroreflectors.

Embodiment 13 Coordinate measuring machine for measuring at least one workpiece, the coordinate measuring machine comprising at least one measuring device according to one of the preceding embodiments relating to a measuring device, the coordinate measuring machine having at least one measurement object which is set up to scan the workpiece.

1. a) Bereitstellen des mindestens einen Messobjekts, wobei das Messobjekt das Targetensemble aufweist, wobei das Targetensemble die Retroreflektoren aufweist, wobei die Retroreflektoren des Targetensembles bekannte Koordinaten in einem Targetensemble-Koordinatensystem aufweisen;
2. b) Erzeugen des mindestens einen Beleuchtungslichtstrahls mit jeder der Lokalisierungseinheiten und Beleuchten der Retroreflektoren mit den Beleuchtungslichtstrahlen, wobei jede der Lokalisierungseinheiten mindestens einen der Retroreflektoren beleuchtet, wobei jeder der zur Bestimmung der Position und Orientierung herangezogenen Retroreflektoren von mindestens einer der Lokalisierungseinheiten beleuchtet wird;
3. c) Empfangen jeweils mindestens eines der von den Retroreflektoren reflektierten Lichtstrahlen und Erzeugen mindestens eines Messsignals mit jeder der Lokalisierungseinheiten, wobei jede der Lokalisierungseinheiten den reflektierten Lichtstrahl des von ihr beleuchteten Retroreflektors empfängt;
4. d) Bestimmen der räumlichen Position und Orientierung des Messobjekts aus den Messsignalen der Lokalisierungseinheiten mit der mindestens einen Auswerteeinheit, wobei das Bestimmen der räumlichen Position und Orientierung des Messobjekts die folgenden Schritte umfasst:
   1. A) Bestimmen der Distanz von der jeweiligen Lokalisierungseinheit zu dem mindestens einen von dieser beleuchteten Retroreflektor aus dem Messsignal; und
   2. B) Bestimmen der 6D-Pose des Targetensembles in dem Koordinatensystem der Lokalisierungseinheiten unter Berücksichtigung der bekannten Koordinaten der Retroreflektoren in dem Targetensemble-Koordinatensystem und der in A) bestimmten Distanzen.

Embodiment 14 Method for measuring at least one measurement object with a measuring device according to one of the preceding embodiments relating to a measuring device, the method comprising the following steps:

1. a) providing the at least one measurement object, the measurement object having the target ensemble, the target ensemble having the retroreflectors, the retroreflectors of the target ensemble having known coordinates in a target ensemble coordinate system;
2. b) generating the at least one illumination light beam with each of the localization units and illuminating the retroreflectors with the illumination light beams, each of the localization units illuminating at least one of the retroreflectors, each of the retroreflectors used to determine the position and orientation being illuminated by at least one of the localization units;
3. c) receiving in each case at least one of the light beams reflected by the retroreflectors and generating at least one measurement signal with each of the localization units, each of the localization units receiving the reflected light beam of the retroreflector illuminated by it;
4. d) Determining the spatial position and orientation of the measurement object from the measurement signals of the localization units with the at least one evaluation unit, the determination of the spatial position and orientation of the measurement object comprising the following steps:
   1. A) determining the distance from the respective localization unit to the at least one retroreflector illuminated by it from the measurement signal; and
   2. B) determining the 6D pose of the target ensemble in the coordinate system of the localization units considering the known coordinates of the retroreflectors in the target ensemble coordinate system and the distances determined in A).

Embodiment 15 Method for measuring at least one measurement object according to the preceding embodiment, wherein the determination of the spatial position and orientation of the measurement object in step d) is preceded by a determination of the coordinates of the retroreflectors in the target ensemble coordinate system.

character list

Further details and features emerge from the following description of exemplary embodiments, in particular in connection with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments. The exemplary embodiments are shown schematically in the figures. The same reference numerals in the individual figures designate elements that are the same or have the same function or that correspond to one another in terms of their functions.

• 1 eine schematische Darstellung eines ersten Ausführungsbeispiels einer Messvorrichtung zur Bestimmung von mindestens einer räumlichen Position und Orientierung eines Messobjekts;
• 2 eine schematische Darstellung eines weiteren Ausführungsbeispiels der Messvorrichtung;
• 3 eine schematische Darstellung eines Targetensembles in einem Targetensemble-Koordinatensystem;
• 4 eine schematische Darstellung einer Transformation eines Targetensemble-Koordinatensystems in ein Koordinatensystem der Lokalisierungseinheiten; und
• 5 eine schematische Darstellung eines Verfahrens zur Vermessung mindestens eines Messobjekts.

Show in detail:

• 1 a schematic representation of a first exemplary embodiment of a measuring device for determining at least one spatial position and orientation of a measurement object;
• 2 a schematic representation of a further exemplary embodiment of the measuring device;
• 3 a schematic representation of a target ensemble in a target ensemble coordinate system;
• 4 a schematic representation of a transformation of a target ensemble coordinate system into a coordinate system of the localization units; and
• 5 a schematic representation of a method for measuring at least one measurement object.

Description of the exemplary embodiments

1 shows a schematic representation of a first embodiment of measuring device 110 for determining at least one spatial position and orientation of a measurement object 112. The measuring device comprises at least one target ensemble 114 with at least three retroreflectors 116. The retroreflectors 116 have known coordinates in a target ensemble coordinate system 118. Furthermore, the measurement object 112 has the target ensemble 114, as in 1 to see. The measuring device 110 comprises at least six localization units 120. The exemplary embodiment in 1 12 shows a measuring device 110 with three retroreflectors 116 and six localization units 120. A position of the localization units 120 and a position of the retroreflectors 116 can each be linearly independent of one another.

Each of the localization units 120 is set up to generate at least one illumination light beam 122 and to illuminate at least one of the retroreflectors 116 with the illumination light beam 122 . Each of the retroreflectors 116 used to determine the position and orientation is illuminated by at least one of the localization units 120 . Each of the localization units 120 is set up to receive at least one reflected light beam 124 from the retroreflector 116 it illuminates and to generate at least one measurement signal. In 1 the illumination light rays 122 and the reflected light rays 124 are illustrated with double arrows.

1. i) Bestimmen mindestens einer Distanz 128 von der jeweiligen Lokalisierungseinheit 120 zu dem mindestens einen von dieser beleuchteten Retroreflektor 116 aus dem Messsignal; und
2. ii) Bestimmen einer 6D-Pose des Targetensembles 114 in einem Koordinatensystem 130 (siehe 4) der Lokalisierungseinheiten 120 unter Berücksichtigung der bekannten Koordinaten der Retroreflektoren 116 im Targetensemble-Koordinatensystem 118 und der in i) bestimmten Distanzen 128.

Measuring device 110 has at least one evaluation unit 126 . The evaluation unit 126 is set up to determine the spatial position and orientation of the measurement object 112 from the measurement signals of the localization units 120, with the determination of the spatial position and orientation of the measurement object 112 comprising the following steps:

1. i) determining at least one distance 128 from the respective localization unit 120 to the at least one retroreflector 116 illuminated by it from the measurement signal; and
2. ii) determining a 6D pose of the target ensemble 114 in a coordinate system 130 (see 4 ) of the localization units 120, taking into account the known coordinates of the retroreflectors 116 in the target ensemble coordinate system 118 and the distances 128 determined in i).

As in 1 As can be seen, each of the localization units 120 can be connected to the evaluation unit 126, in particular with a cable 131 in each case. However, wireless connections are also conceivable.

The retroreflectors 116 can be designed as markers, for example. For example, retroreflector 116 may be selected from the group consisting of: a cat's eye; a cat's eye with a reflective layer; a marker described in U.S. 2011/0007326 A1 , U.S. 2013/0050410 A1 or US 2017/0258531 A1 , the content of which is hereby incorporated into this application; a cube prism; a corner cube. The retroreflectors 116 can each have at least one holder 133 for arranging and/or attaching the retroreflectors 116 to the measurement object 112 1 In the exemplary embodiment illustrated, the three retroreflectors 116 are attached to the measurement object 112 and are illuminated by six localization units 120 .

The localization units 120 can each have at least one lighting unit 132 . The lighting unit 132 can have a light source 134, in particular a laser source. In particular, each of the localization units 120 can comprise at least one element selected from the group consisting of: a laser tracker; a LIDAR sensor, an FMCW LIDAR sensor. The localization units 120 can be set up to generate at least one item of localization information. The localization information can be selected from at least one piece of information from the group consisting of: a measurement signal depending on the location of the retroreflector 116 illuminated by the localization unit 120; information about a distance or distance from the retroreflector 116 illuminated by the localization unit 120 to the localization unit 120; information about a position of the retroreflector 116 illuminated by the localization unit 120 relative to the localization unit 120; and information about a change in length. In particular, the LIDAR sensor can be set up to generate and receive a light beam, for example a laser beam, in particular the light beam previously emitted by it and reflected back to it, and from this to determine a distance between the LIDAR sensor and the retroreflector, for example exploiting differences in return times and wavelengths.

A mapping, also referred to as a "mapping", configuration or lighting scheme, which indicates which retroreflector 116 is illuminated by which localization unit 120 and/or which localization unit 120 illuminates which retroreflector 116 may be known. In particular, a retroreflector 116 can be illuminated by a plurality of localization units 120 . For example, one of the retroreflectors 116 of three of the localization units 120 may be illuminated. One of the two further retroreflectors 116 can be illuminated by two of the three further localization units 120 . The further retroreflector 116, in particular a third retroreflector 116, can be illuminated by the one remaining one of the six localization units 120. Such a configuration may also be abbreviated or denoted as (three-two-one) and is shown in the embodiment in FIG 1 shown, which is to be described here as an example for a better understanding of the configuration.

The three retroreflectors 116 may be referred to as first retroreflector 136, second retroreflector 138, and third retroreflector 140. FIG. The six localization units 116 can be used as the first localization tion unit 142, second locating unit 144, third locating unit 146, fourth locating unit 148, fifth locating unit 150 and sixth locating unit 152 are referred to. In this configuration, for example, the first retroreflector 136 can be illuminated by the first localization unit 142 , the second localization unit 144 and the third localization unit 146 . The second retroreflector 138 may be illuminated by the fourth localization unit 148 and the fifth localization unit 150 . The third retroreflector 140 can be illuminated by the sixth localization unit 116 . This corresponds to the configuration (three-two-one) and is in 1 to see. The localization units 120 can be interchangeable or interchangeable. The retroreflectors 116 can also be interchangeable or interchangeable. For example, referring to the example above, the second retroreflector 138 may be illuminated by the sixth locating unit 152 and the third retroreflector 140 may be illuminated by the fifth locating unit 150 . Other combinations are possible.

The localization units 120 can be arranged in space, for example in a space surrounding or enclosing the measurement object 112, as shown in FIG 1 to see. The measuring device 110 can also have a control unit 154 . The control unit 154 may include at least one data processing device, such as at least one computer or microcontroller. The control unit 154 can be designed in particular as a central control unit 154 for the entire measuring device 110 . Alternatively, however, a decentralized control unit 154 with a plurality of individual components that cooperate with one another is also possible. The control unit 154 can also have at least one user interface, for example at least one keyboard and/or at least one display. The control unit 154 can be set up to align the localization units 120 relative to the retroreflectors 116 .

2 shows a schematic representation of another embodiment of the measuring device 110. This embodiment includes a measuring device 110 with seven retroreflectors 116 and seven localization units 120. In this embodiment, each of the seven retroreflectors 116 can be illuminated by exactly one of the seven localization units 120. Conversely, each of the seven localization units 120 can illuminate exactly one of the seven retroreflectors 116 in this embodiment. Such a configuration may also be abbreviated or referred to as (one-one-one-one-one-one-one). This configuration is in 2 and is to be described here again as an example for better understanding. The seven retroreflectors 116 may be referred to as the first retroreflector 136, the second retroreflector 138, the third retroreflector 140, the fourth retroreflector 156, the fifth retroreflector 158, the sixth retroreflector 160, and the seventh retroreflector 162. The seven locating units 120 may be referred to as the first locating unit 142, the second locating unit 144, the third locating unit 146, the fourth locating unit 148, the fifth locating unit 150, the sixth locating unit 152, and seventh locating unit 164. In this configuration, for example, the first retroreflector 136 can be illuminated by the first localization unit 142 . The second retroreflector 138 can be illuminated by the second localization unit 144 . The third retroreflector 140 may be illuminated by the third localization unit 146 . The fourth retroreflector 156 can be illuminated by the fourth localization unit 148 . The fifth retroreflector 158 can be illuminated by the fifth localization unit 150 . The sixth retroreflector 160 can be illuminated by the sixth localization unit 152 . The seventh retroreflector 138 can be illuminated by the seventh localization unit 164 . As already explained elsewhere, further combinations and/or interchanges are possible.

Other configurations or lighting schemes not shown in the figures are also possible, for example the configuration (three-two-two). In this configuration, the measuring device 110 can include three retroreflectors 116 and seven localization units 120 . One of the retroreflectors 116 can be illuminated by three of the locating units 120 . One of the two further retroreflectors 116 can be illuminated by two of the four further localization units 120 . The further retroreflector 116 can be illuminated by the two remaining of the seven localization units 120 .

The measuring device 110 has the evaluation unit 126 which is set up to determine the spatial position and orientation of the measurement object 112 from the measurement signals of the localization units 120 . As part of step ii), determining the spatial position and orientation of the measurement object 112 includes determining the 6D pose of the target ensemble 114 in the coordinate system 130 of the localization units 120. As already stated, the measurement object 112 has the target ensemble 114, so that the 6D - Pose of the target ensemble 114 can correspond to the 6D pose of the measurement object 112, and in particular the spatial position and orientation of the measurement object 112, or the spatial posi tion and orientation of the measurement object 112 from the 6D pose of the target ensemble 114 can be determined. To determine the 6D position of the measurement object 112, the target ensemble 114 that is to be measured can be described in its own coordinate system, the target ensemble coordinate system 118.

3 12 shows a schematic representation of a target ensemble 114 having three retroreflectors 116 in a target ensemble coordinate system 118. The retroreflectors 116 of the target ensemble 114 have known coordinates in the target ensemble coordinate system 118. FIG. The target ensemble coordinate system 118 can be a Cartesian coordinate system. For example, the target ensemble coordinate system 118 can be selected in such a way that one of the retroreflectors 116 , in particular the first retroreflector 136 , is arranged in an origin 166 in the target ensemble coordinate system 118 . 3 shows the origin 166 of the target ensemble coordinate system 118, the X-axis 168, the Y-axis 172 and the Z-axis 170 of the target ensemble coordinate system 118 as well as the first retroreflector 136 arranged in the origin 166. One of the further retroreflectors 116, in particular the second retroreflector 138, may be located on one of the axes of the target ensemble coordinate system 118. For example, the second retroreflector 138 can lie on the X-axis 168, as in FIG 3 shown. A further retroreflector 116, in particular the third retroreflector 140, can be arranged in a plane which is spanned by the aforementioned axis and another axis of the target ensemble coordinate system 118, for example in the XY plane 174.

According to this embodiment, the coordinates of the first retroreflector 136 in the target ensemble coordinate system 118 may be R ₁ = [0|0|0]. The coordinates of the second retroreflector 138 in the target ensemble coordinate system 118 may be R ₂ = [x ₂ |0|0]. The X coordinate x ₂ cannot be equal to 0. The X coordinate can be x ₂ > 0 or x ₂ < 0. The coordinates of the third retroreflector may be R ₃ = [x ₃ |y ₃ |0] in the target ensemble coordinate system 118 . The X coordinate x ₃ and the Y coordinate y ₃ can be non-zero. The Y coordinate can be y ₃ > 0 or y ₃ < 0. The X ₃ coordinate can be x3 !=0; the sign of x ₃ depends on the sign of x ₂ . Coordinates of further retroreflectors 116, for example a fourth to n-th retroreflector 116, of the target ensemble 114 can be defined in the target ensemble coordinate system 118 as R4 = [x ₄ |y ₄ |z ₄ ]...R _n = [x _n |y _n |z _n ] must be specified. A different orientation, selection or positioning of the target ensemble coordinate system 118 is also possible.

If three retroreflectors 116 are used, three items of position information of the retroreflectors 116 result, these being in the form of Cartesian coordinates. The target ensemble 114 can have more than three retroreflectors 116, for example a plurality of four, five, six and more retroreflectors 116. If more than three retroreflectors 116 are provided, the further retroreflectors 116 can be specified in the target ensemble coordinate system 118. According to the invention, the target ensemble 116 is thus not described by the distances between the targets, but these are described in a separate, preferably Cartesian, coordinate system.

The coordinates of the retroreflectors 116 in the target ensemble coordinate system 118 may be previously known and/or predetermined. For example, the coordinates of the retroreflectors 116 in the target ensemble coordinate system 118 can be determined, for example in a previous step, and can be assumed to be fixed and correct for the determination of the pose. For example, the coordinates of the retroreflectors 116 in the target ensemble coordinate system 118 can be stored in a data memory of the evaluation unit 126, for example in the form of a lookup table.

The evaluation unit 126 can be set up to determine the spatial position and orientation of the measurement object 112 using a multilateration method. In this case, the distances of the retroreflectors 116 to the localization units 120 measured in step i) can be used to determine the spatial position of the retroreflectors 116 of the target ensemble 114 . The evaluation unit 126 can be set up to solve a system of linear equations in order to determine the spatial position and orientation of the measurement object 112 . The target function for solving the system of linear equations is not the XYZ position of the individual targets, but the 6D pose of the target ensemble coordinate system 118 in the coordinate system 130 of the localization units 120. The unknown that defines the 6D pose in the coordinate system 130 of the localization units 120 can be described by a transformation matrix "T". The transformation matrix can transform the target ensemble coordinate system 118 into the coordinate system 130 of the localization units 120 . Such a transformation matrix can include the information about the translational and rotational position. The evaluation unit 126 may be set up to determine the transformation matrix for determining the 6D pose of the target ensemble 118 in the coordinate system 130 of the localization units 120 .

4 shows a schematic representation of a transformation 176 of a target ensemble coordinate system 118 into a coordinate system 130 of the localization units 120. In the case shown, it is a translation, ie a displacement of the coordinate system. The transformation 176 as the effect of the transformation matrix on the target ensemble coordinate system 118 is illustrated here schematically by the arrow from the origin (see position of the first retroreflector marked with reference numerals 116, 136 in 4 ) of the target ensemble coordinate system 118 to the origin 166 of the coordinate system 130 of the localization units 120. As an alternative or in addition to the translation, the transformation 176 can also include, for example, a rotation, ie a rotation of the coordinate system. The transformation matrix can, for example, be structured as follows: be: $$T=\left[\begin{array}{cc}D& t_{xy\mathrm{e.g}}\\ 0& 1\end{array}\right]$$

Here D is a rotation matrix, also called a rotation matrix, for which the following applies: $$D=D_{\mathrm{e.g}}\cdot D_y\cdot D_x=\left[\begin{array}{ccc}\text{cos}g& -\text{<figure-callout id="0" label="sin g" filenames="DE102021209427A1\_0015.png" state="{{state}}">sin</figure-callout>}g& 0\\ \text{sin}\mathrm{<figure-callout\; id="0"\; label="g\; cos\; g"\; filenames="DE102021209427A1\_0015.png"\; state="\{\{state\}\}">g</figure-callout>}& \text{cos}g& 0\\ 0& 0& 1\end{array}\right]\cdot \left[\begin{array}{ccc}\text{cos}\beta & 0& \text{<figure-callout id="0" label="sin β" filenames="DE102021209427A1\_0015.png" state="{{state}}">sin</figure-callout>}\beta \\ 0& 1& 0\\ -\text{<figure-callout id="0" label="sin β" filenames="DE102021209427A1\_0015.png" state="{{state}}">sin</figure-callout>}\beta & 0& \text{cos}\beta \end{array}\right]\cdot \left[\begin{array}{ccc}1& 0& 0\\ 0& \text{cos}a& -\text{sin}a\\ 0& \text{sin}a& \text{cos}a\end{array}\right]$$

In this case, D _z describes a rotation about the Z axis by the angle γ, D _y describes a rotation about the y axis by the angle β and D _x describes a rotation about the x axis by the angle α. Furthermore, t _xyz describes a translation, the following applies: $$t_{xy\mathrm{e.g}}={\left[\begin{array}{ccc}{t}_x& t_y& t_{\mathrm{e.g}}\end{array}\right]}^T$$

The target function for determining the parameters of the transformation matrix T can be described as "the measured distance l _i,m of the i-th localization unit to its targeted retroreflector R at the m-th measurement position corresponds to the distance of the multiplied by the transformation matrix T, position of the from the i-th localization unit illuminated retroreflector P _R,map ( _i ) in the target ensemble coordinate system to the position of the i-th localization unit P _T,i in the coordinate system of the localization units”: $$\begin{array}{c}{l}_{i,m}=\left|P_{T,i}-T\cdot P_{R,map\left(i\right)}\right|=\\ \sqrt{{\left(P_{T,i}-T\cdot P_{R,map\left(i\right)}\right)}_x^2+{\left(P_{T,i}-T\cdot P_{R,map\left(i\right)}\right)}_{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="DE102021209427A1\_0014.png,DE102021209427A1\_0015.png"\; state="\{\{state\}\}">y</figure-callout>}}^2+{\left(P_{T,i}-T\cdot P_{R,map\left(i\right)}\right)}_{\mathrm{e.g}}^2}.\end{array}$$

5 zeigt eine Ausführungsform eines Verfahrens zur Vermessung mindestens eines Messobjekts 112 mit einer Messvorrichtung 110 gemäß einer der weiter oben beschriebenen oder gemäß einer der weiter unten noch ausgeführten Ausführungsformen. Das Verfahren umfasst die folgenden Schritte:

1. a) (Bezugszeichen 178) Bereitstellen des Messobjekts 112, wobei das Messobjekt 112 das Targetensemble 114 aufweist, wobei das Targetensemble 114 die Retroreflektoren 116 aufweist, wobei die Retroreflektoren 116 des Targetensembles 114 bekannte Koordinaten in einem Targetensemble-Koordinatensystem 118 aufweisen;
2. b) (Bezugszeichen 180) Erzeugen des mindestens einen Beleuchtungslichtstrahls 122 mit jeder der Lokalisierungseinheiten 120 und Beleuchten der Retroreflektoren 116 mit den Beleuchtungslichtstrahlen 122, wobei jede der Lokalisierungseinheiten 120 mindestens einen der Retroreflektoren 116 beleuchtet, wobei jeder der zur Bestimmung der Position und Orientierung herangezogenen Retroreflektoren 116 von mindestens einer der Lokalisierungseinheiten 120 beleuchtet wird;
3. c) (Bezugszeichen 182) Empfangen jeweils mindestens eines der von den Retroreflektoren 116 reflektierten Lichtstrahlen 124 und Erzeugen mindestens eines Messsignals mit jeder der Lokalisierungseinheiten 120, wobei jede der Lokalisierungseinheiten 120 den reflektierten Lichtstrahl 124 des von ihr beleuchteten Retroreflektors 116 empfängt;
4. d) (Bezugszeichen 184) Bestimmen der räumlichen Position und Orientierung des Messobjekts 112 aus den Messsignalen der Lokalisierungseinheiten 120 mit der mindestens einen Auswerteeinheit 126, wobei das Bestimmen der räumlichen Position und Orientierung des Messobjekts 112 die folgenden Schritte umfasst:
   1. A) (Bezugszeichen 186) Bestimmen der Distanz 128 von der jeweiligen Lokalisierungseinheit 120 zu dem mindestens einen von dieser beleuchteten Retroreflektor 116 aus dem Messsignal; und
   2. B) (Bezugszeichen 188) Bestimmen der 6D-Pose des Targetensembles 114 in dem Koordinatensystem 130 der Lokalisierungseinheiten 120 unter Berücksichtigung der bekannten Koordinaten der Retroreflektoren 116 in dem Targetensemble-Koordinatensystem 118 und der in A) bestimmten Distanzen 128.

The parameters of the transformation matrix T can be determined iteratively. For this purpose, the evaluation unit 126 can be set up to solve an optimization problem. Solving the optimization problem may involve minimizing an error function F with $$f=\left|P_{T,i}-T\cdot P_{R,map\left(i\right)}\right|-l_{i,m}.$$

5 1 shows an embodiment of a method for measuring at least one measurement object 112 with a measuring device 110 according to one of the embodiments described above or according to one of the embodiments explained further below. The procedure includes the following steps:

1. a) (reference numeral 178) providing the measurement object 112, the measurement object 112 having the target ensemble 114, the target ensemble 114 having the retroreflectors 116, the retroreflectors 116 of the target ensemble 114 having known coordinates in a target ensemble coordinate system 118;
2. b) (reference number 180) generating the at least one illumination light beam 122 with each of the localization units 120 and illuminating the retroreflectors 116 with the illumination light beams 122, each of the localization units 120 illuminating at least one of the retroreflectors 116, each of the retroreflectors used to determine the position and orientation 116 is illuminated by at least one of the localization units 120;
3. c) (reference numeral 182) receiving at least one of the light beams 124 reflected by the retroreflectors 116 and generating at least one measurement signal with each of the localization units 120, each of the localization units 120 receiving the reflected light beam 124 of the retroreflector 116 illuminated by it;
4. d) (reference number 184) determining the spatial position and orientation of the measurement object 112 from the measurement signals of the localization units 120 with the at least one evaluation unit 126, wherein the determination of the spatial position and orientation of the measurement object 112 comprises the following steps:
   1. A) (reference number 186) determining the distance 128 from the respective localization unit 120 to the at least one retroreflector 116 illuminated by it from the measurement signal; and
   2. B) (reference numeral 188) determining the 6D pose of the target ensemble 114 in the coordinate system 130 of the localization units 120, taking into account the known coordinates of the retroreflectors 116 in the target ensemble coordinate system 118 and the distances 128 determined in A).

The method steps can be carried out in the order given, with one or more of the steps being able to be carried out at least partially simultaneously and with one or more of the steps being able to be repeated several times.

In addition, other steps, whether or not mentioned in the present application, can additionally be carried out. In particular, the determination of the spatial position and orientation of the measurement object 112 in step d) 184 can be preceded by a determination of the coordinates of the retroreflectors 116 in the target ensemble coordinate system 118 .

Reference List

110

measuring device

112

measurement object

114

target ensemble

116

retroreflector

118

Target ensemble coordinate system

120

localization unit

122

illumination light beam

124

reflected light beam

126

evaluation unit

128

distance

130

Coordinate system of localization units

131

Cable

132

lighting unit

133

bracket

134

light source

136

first retroreflector

138

second retroreflector

140

third retroreflector

142

first localization unit

144

second localization unit

146

third localization unit

148

fourth localization unit

150

fifth localization unit

152

sixth localization unit

154

control unit

156

fourth retroreflector

158

fifth retroreflector

160

sixth retroreflector

162

seventh retroreflector

164

seventh localization unit

166

Origin of the coordinate system

168

X axis

170

Z axis

172

Y axis

174

XY plane

176

transformation

178

process step a)

180

process step b)

182

process step c)

184

process step d)

186

sub-step A)

188

sub-step B)

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2020104666 [0004, 0019]
• US20110007326 A1 [0014, 0080]
• US 20130050410 A1 [0014, 0080]
• US20170258531 A1 [0014, 0080]
• US 9559486 B2 [0028]
• US 8913636 B2 [0028]
• US2016123718A1 [0028]

Claims (10)

Measuring device (110) for determining at least one spatial position and orientation of a measurement object (112), the measuring device (110) comprising - at least one target ensemble (114) with at least three retroreflectors (116), the retroreflectors (116) of the target ensemble (114) having known coordinates in a target ensemble coordinate system (118), the measurement object (112) having the target ensemble (114). , - at least six localization units (120), each of the localization units (120) being set up to generate at least one illuminating light beam (122) and to illuminate at least one of the retroreflectors (116) with the illuminating light beam (122), each of the spatial The retroreflectors (116) used for position and orientation are illuminated by at least one of the localization units (120), each of the localization units (120) being set up to receive at least one reflected light beam (124) from the retroreflector (116) it illuminates and at least one to generate a measurement signal - at least one evaluation unit (126), which is set up to determine the spatial position and orientation of the measurement object (112) from the measurement signals of the localization units (120), the determination of the spatial position and orientation of the measurement object (112) comprising the following steps : i) determining at least one distance (128) from the respective localization unit (120) to the at least one retroreflector (116) illuminated by it from the measurement signal, ii) determining a 6D pose of the target ensemble (114) in a coordinate system (130) of the localization units (120) taking into account the known coordinates of the retroreflectors (116) in the target ensemble coordinate system (118) and the distances (128) determined in i) . Measuring device (110) according to the preceding claim, wherein the evaluation unit (126) is set up to determine the 6D pose of the target ensemble (114) in the coordinate system (130) of the localization units (120) to determine a transformation matrix. Measuring device (110) according to the preceding claim, the transformation matrix is set up to transform the target ensemble coordinate system (118) into the coordinate system (130) of the localization units (120). Measuring device (110) according to one of the two preceding claims, wherein the evaluation unit (126) is set up to determine components of the transformation matrix to solve an optimization problem, wherein solving the optimization problem includes minimizing an error function F with $$f=\left|P_{T,i}-T\cdot P_{R,map\left(i\right)}\right|-l_{i,m}$$

- where P _T,i is the position of the i-th localization unit (120) in the coordinate system (130) of the localization units (120), - where T is the transformation matrix, - where P _R,map(i) is the position of the i -th localization unit (120) illuminated, m-th retroreflector (116) in the target ensemble coordinate system (118), and - where l _i,m is the distance (128), determined by the evaluation unit (126), of the i-th localization unit (120 ) to the m-th retroreflector (116) illuminated by it. Measuring device (110) according to one of the preceding claims, wherein the target ensemble coordinate system (118) is a Cartesian coordinate system, wherein one of the retroreflectors (116) is arranged in an origin (166) of the Cartesian coordinate system, wherein one of the further retroreflectors (116) is arranged on one of the axes of the Cartesian coordinate system, one of the at least one further retroreflector (116) being arranged in a plane which spans the aforementioned axis and a further axis of the Cartesian coordinate system. Measuring device (110) according to one of the two preceding claims, wherein the coordinate system (130) of the localization units (120) is a Cartesian coordinate system. Measuring device (110) according to one of the preceding claims, wherein each of the localization units (120) comprises at least one element selected from the group consisting of: a laser tracker; a LIDAR sensor, a FMCW-LL-DAR sensor. Measuring device (110) according to one of the preceding claims, wherein the measuring device (110) comprises six localization units (120) and three retroreflectors (116), or wherein the measuring device (110) comprises seven localization units (120) and three retroreflectors (116), or wherein the measuring device (110) comprises seven localization units (120) and seven retroreflectors (116). Coordinate measuring machine for measuring at least one workpiece, wherein the coordinate measuring machine comprises at least one measuring device (110) according to one of the preceding claims relating to a measuring device (110), wherein the coordinate measuring machine has at least one measurement object (112) which is set up to scan the workpiece. Method for measuring at least one measurement object (112) with a measuring device (110) according to one of the preceding claims relating to a measuring device (110), the method comprising the following steps: a) Providing the at least one measurement object (112), the measurement object (112) having the target ensemble (114), the target ensemble (114) having the retroreflectors (116), the retroreflectors (116) of the target ensemble (114) having known coordinates in a target ensemble coordinate system (118); b) generating the at least one illumination light beam (122) with each of the localization units (120) and illuminating the retroreflectors (116) with the illumination light beams (122), each of the localization units (120) illuminating at least one of the retroreflectors (116), each of the retroreflectors (116) used to determine the position and orientation are illuminated by at least one of the localization units (120); c) receiving at least one of the light beams (124) reflected by the retroreflectors (116) and generating at least one measurement signal with each of the localization units (120), each of the localization units (120) detecting the reflected light beam (124) of the retroreflector ( 116) receives; d) Determining the spatial position and orientation of the measurement object (112) from the measurement signals of the localization units (120) with the at least one evaluation unit (126), the determination of the spatial position and orientation of the measurement object (112) comprising the following steps: A) determining the distance (128) from the respective localization unit (120) to the at least one retroreflector (116) illuminated by it from the measurement signal; and B) Determining the 6D pose of the target ensemble (114) in the coordinate system (130) of the localization units (120) taking into account the known coordinates of the retroreflectors (116) in the target ensemble coordinate system (118) and the distances (128 ).

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