Arrangement and procedure for measuring an object

Abstract

Arrangement for measuring a measuring object (10), in particular for determining the coordinates of the measuring object (10), wherein the arrangement comprises the following: - a motion device (3, 4; 23, 4; 33, 34) configured to move a sensor (7; 27; 37) held on the arrangement during operation of the arrangement and configured to detect the object being measured (10), relative to the object being measured (10), - an actuator device (8; 38; 48; 58; 68; 71) via which the sensor (7; 27; 37) is coupled to the motion device (3, 4; 23, 4; 33, 34) during operation of the arrangement and which is designed to at least partially compensate for vibrational movements of the sensor (7; 27; 37), - a vibration measuring device (9) designed to generate information about vibrations of the arrangement and / or the sensor (7; 27; 37) by measuring at least one measured quantity, - a control device (19) which is connected to the vibration measuring device (9) and the actuator device (8; 38; 48; 58; 68; 71) and which is configured to control the actuator device (8; 38; 48; 58; 68; 71) in such a way that the vibration movements of the sensor (7; 27; 37) are at least partially compensated, wherein all moving parts of the arrangement, which serve to move the entire sensor (7; 27; 37) relative to the object being measured, are coupled to the sensor (7; 27; 37) via the actuator device (8; 38; 48; 58; 68; 71), characterized by the fact that the actuator assembly (8; 38; 48; 58; 68; 71) has a plurality of motors (41) and wherein each of the motors (41) can be controlled independently of any other motor (41) or motors (41) of the actuator assembly (8; 38; 48; 58; 68; 71) by the control unit (19), a plurality of the motors (41) are configured and arranged to each generate a movement with respect to a single linear degree of freedom of the movement and thus along a linear axis of motion of the motor (41), and the linear axes of motion of at least two motors (41) of the actuator assembly (8; 38; 48; 58; 68; 71) are parallel to each other, wherein each of the motors (41) with parallel axes of motion is coupled to the motion assembly (3, 4; 23, 4; 33, 34) via a first coupling element (5; 45; 55; 65) and is coupled or can be coupled to the sensor (7; 27; 37) via a second coupling element (6; 36; 46; 56; 66), and wherein the first coupling element (5; 45; 55; 65) or the second coupling element (6; 36; 46; 56; 66) each is rotatably coupled to the motors (41) with parallel axes of movement via a joint (4; 42; 62).

Description

[0001] The invention relates to an arrangement and a method for measuring a measurement object. The arrangement includes a movement device configured to move a sensor, which is held on the arrangement during operation, relative to the measurement object. As a step in the method for measuring a measurement object, a sensor is moved relative to the measurement object by means of a movement device in order to bring the sensor into a detection position for detecting the measurement object.

[0002] The sensor is designed to detect the object being measured. The sensor can be a permanent or temporary part of the setup, or it can be entirely separate from the setup. For example, different sensors can be selectively attached to the measuring setup and used to measure the object.

[0003] By capturing the object being measured, its coordinates can be obtained, for example, by evaluating the sensor's measurement results using an evaluation unit within the system. The object being measured is typically a workpiece. However, it can alternatively be a living subject such as a person or an animal.

[0004] The setup can be, in particular, a conventional measuring setup such as a coordinate measuring machine, a machine tool, or a robot, for example, an articulated robot. Generally, the term coordinate measuring setup or coordinate measuring machine is used when the measuring setup serves to determine the coordinates of the object being measured.

[0005] Regarding the term coordinate measuring machine, it should be noted that this is not limited to portal-type coordinate measuring machines, but also includes, for example, gantry-type machines, horizontal-arm machines, and articulated-arm machines. Coordinate measuring arrangements also optionally include machines that, while not primarily designed as coordinate measuring arrangements, are configured to operate like one. Examples include robot arms with rotary joints to which a sensor for detecting a workpiece surface (e.g., a fringe projection sensor) is attached, or machine tools to which a sensor for detecting the workpiece surface (e.g., a tactile sensor) is attached instead of a machining tool. Furthermore, it is possible for the machining tool itself to be combined with such a sensor.Hexapod mechanisms are also known, for example, on which a sensor for detecting the workpiece surface (e.g. a tactile sensor) is attached instead of a machining tool.

[0006] Furthermore, the term coordinate measuring machine also includes a device that, for example, uses tomographic methods to shine invasive radiation onto the workpiece and records, for example, radiographs and / or reflection images. In particular, a three-dimensional image of the workpiece can be generated from several such images using reconstruction methods, from which the inspection characteristics can then be determined.

[0007] In measuring setups, and especially in coordinate measuring machines, the measurement accuracy and speed depend on the amplitude and frequency of vibrations of the sensor used for measurement. Common causes of sensor vibrations are movements of the sensor by the motion device to bring it into a measuring position, and vibrations transmitted from the surrounding ground via the motion device.

[0008] DE 40 01 981 A1 describes measures for reducing vibrations at the free end of the measuring arm of a coordinate measuring machine, to which a probe is attached. An additional mass is movably suspended from the measuring arm. The movement of this additional mass is dampened, for example, by an oil film. Alternatively, an active system with a vibration sensor and a drive for the movable additional mass is provided. A controller regulates the drive so that the vibration decays as quickly as possible. While this allows for the damping of the vibration, the inertia of the oscillating system is increased due to the additional mass on the measuring arm. Therefore, if the vibration changes or is newly excited, time is required to reduce the vibration amplitudes.

[0009] Especially in measurement setups with imaging sensors, for example cameras for capturing two-dimensional images, considerable rest periods are required after sensor movement before usable images can be generated. Vibrations occurring during sensor movement would lead to a blurring of the structures in the captured image, since the image acquisition takes place over a period of time.

[0010] In principle, it is also possible to attempt to compensate for the vibrations transmitted from the surrounding ground to the measuring setup directly at the feet of the setup. However, even in this case, the moving masses are considerable, and immediate cancellation of the vibrations of the measuring setup is not possible. Therefore, despite the compensation, the sensor itself still exhibits vibrations.

[0011] WO 2012 / 130 832 A1 describes a coordinate measuring machine for determining at least one spatial coordinate of a measuring point on a measured object, comprising a first frame element, a second frame element, a linear drive unit with a motor for moving the second frame element relative to the first frame element in a direction of movement, and a position measuring device for determining a drive position of the second frame element relative to the first frame element. An active compensation actuator causes a counter-displacement of the first and second frame elements relative to each other in order to at least partially compensate for dynamic deflections due to vibrations.

[0012] DE 10 2009 042 014 A1 describes a handling device for moving an application device in the form of a measuring device, comprising a manipulator that receives the application device. The manipulator is mounted on a support structure of a parallel kinematic system, which includes a base and has at least two driven axes of motion for moving the support structure relative to the base. The parallel kinematic system can be used for the active damping of vibrations. The manipulator can be an industrial robot that, together with the parallel kinematic system, is movable on rollers or tracks.

[0013] US 2016 / 0223316A1 discloses a coordinate measuring machine comprising: a carrier as a support and positioning structure for an end effector, wherein the end effector is movable in at least three degrees of freedom and positionable by the carrier; a stationary measuring table as a carrier for a possible target object; at least one image detector for capturing images; a control unit that controls the movement of the end effector by the carrier and controls image acquisition with the image detector; and an evaluation unit for processing electronic signals and / or data supplied by the image detector. The image detector is rigidly connected to the measuring table and is mechanically decoupled from the carrier.The evaluation unit is configured to determine the position of the end effector in six degrees of freedom by receiving image data representing an image that covers at least part of the end effector, determining image positions of reference points relative to the end effector in the image, and determining a position of the end effector based on the image positions of the reference points.

[0014] US 2008 / 0271332A1 describes a method for measuring coordinates on a workpiece using a coordinate probe movably connected to a positioning platform by means of one or more actuators, wherein the position of the probe relative to the positioning platform is measurable by probe encoders, the method comprising, in any suitable order, the following steps: moving the positioning platform to a predetermined location with respect to a fixed reference; controlling the actuators to move the coordinate probe relative to the positioning platform while holding the positioning platform stationary at the fixed reference to capture the surface of a workpiece in a local workspace accessible to the coordinate probe; obtaining a local measurement of the workpiece by combining the measurement data with probe position data supplied by the probe encoders;Moving the positioning platform relative to a fixed reference point to another location.

[0015] DE 699 01 021 T2 discloses a unit for mounting an element on a support structure with three mounting devices, each of which has the form of a deformable triangle.

[0016] DE 10 2018 132 436 A1 describes an assembly, in particular in a microlithographic projection exposure system, comprising an optical element; a joint arrangement for the mechanical mounting of the optical element; and a damping device for damping at least one vibration excitation occurring in the joint arrangement by generating at least one counter-vibration which at least partially compensates for the vibration excitation.

[0017] US 2013 / 0299669 A1 relates to a vibration isolation device intended to be placed between a structure and an anchoring plate of a device. The device has a grid of bars, each bar comprising at least one axial actuator, the grid being an active hexapod comprising six identical isolation bars arranged according to a regular geometry, the six bars being arranged such that the control of the tensile and compressive forces in each of the six bars enables force and torque control with respect to six separate degrees of freedom.

[0018] US 2010 / 0032876A1 discloses a device for attaching a supported structure to a supporting base, wherein the supported structure has a center of mass and wherein the device comprises: at least three vibration-isolating sleeves, each sleeve comprising two associated non-parallel elastic struts, a first end of each strut being attached to the supporting base and a second end of each strut being attached to the supported structure at a respective attachment point, wherein the device has a projected elastic center that substantially coincides with the center of mass.

[0019] US 2016 / 0178362A1 describes a method for counteracting a force on a stylus of a stylus unit, wherein the stylus unit is mounted on a coordinate measuring machine and moved by it along a defined motion path with a number of motion points to approach a measurement point on an object. The stylus unit includes an actuator arranged and constructed such that a counterforce acts on the stylus in a variable and defined manner with respect to at least one actuation direction, the counterforce depending on an applied actuation signal. The method includes the following: By receiving motion information about an expected and / or measured movement of the stylus unit, the motion information provides information about a force acting on the stylus due to the movement of the stylus unit.A force parameter is derived for at least one specific point of movement based on the movement information. By determining the control signal for at least one specific point of movement based on the derived force parameter, the control signal causes the actuator to exert a defined counterforce on the sensing element, which is related to the force acting on the sensing element at the respective point of movement.

[0020] DE 101 11 377 A1 discloses a probe head with a stylus movable relative to the probe head in at least one measuring direction and an associated counterweighting device that can counterweight the movable part carrying the stylus in a target position in at least one measuring direction.

[0021] It is an object of the present invention to provide an arrangement for measuring an object by which measurement errors are at least reducible compared to the solutions described above. It is a further object of the present invention to provide a corresponding method for measuring an object.

[0022] It is proposed to couple the sensor of the measuring arrangement to the motion device via an actuator and to at least partially compensate for vibrations of the sensor by means of the actuator. The actuator is thus located in the transition zone between the motion device and the sensor. Therefore, the mass moved during the compensation of the sensor's vibrations is small. In particular, non-essential parts of the motion device do not need to be driven to compensate for vibrations.

[0023] In particular, the following is proposed: An arrangement for measuring an object, especially for determining the coordinates of the object, wherein the arrangement comprises the following: - a movement device designed to move a sensor, which is designed to detect the object being measured and is held on the arrangement during operation of the arrangement, relative to the object being measured, - an actuator device via which the sensor is coupled to the motion device during the operation of the arrangement and which is designed to at least partially compensate for vibrational movements of the sensor, - a vibration measuring device designed to generate information about vibrations of the arrangement and / or the sensor by measuring at least one measured quantity, - a control device connected to the vibration measuring device and the actuator device, designed to control the actuator device in such a way that the vibration movements of the sensor are at least partially compensated.

[0024] Furthermore, the following is proposed: A method for measuring an object, in particular for determining the coordinates of the object, wherein the method comprises the following steps: - A sensor is moved relative to a measuring object by means of a movement device in order to bring the sensor into a detection position for detecting the measuring object, - Information about vibrations of the motion device, the sensor and / or at least one device connected to the motion device and / or the sensor is generated by measuring at least one measured quantity, - An actuator device, via which the sensor is coupled to the motion device, is controlled by a control device taking into account the information about the vibrations in such a way that vibrational movements of the sensor are at least partially compensated.

[0025] The motion device can be of any type. It has at least one moving part to which the sensor is coupled, and the sensor is moved by the movement of this part. Furthermore, the motion device has at least one drive for generating the movement of the moving part. In particular, the motion device can have several moving parts that are also movable relative to each other, whereby two or more parts movable relative to each other can be directly coupled to each other and / or only indirectly coupled to each other. Numerous types of serial and / or parallel kinematics are known. The type of motion device results from the respective type of measuring arrangement. For example, in the case of a gantry-type coordinate measuring machine, the kinematics are known to be serial, with movement along three linear axes.For example, in articulated robots, two arms are directly coupled to each other via at least one joint. Articulated robots with six joints are known, each joint possessing one rotational degree of freedom. The rotational degrees of freedom of the six joints are not independent of each other; that is, a rotation of one joint can be fully or partially compensated for by a rotation of a second joint.

[0026] A sensor designed to detect the object being measured is understood to be a device that generates at least one measurement signal during the detection of the object. The sensor can be tactile and / or non-contact. A tactile sensor scans the object by contacting its surface. This can be, in particular, a switching sensor or a measuring sensor.

[0027] In particular, the sensor can be an optical sensor. Besides optical sensors, there are other non-contact sensors, such as sensors for measuring electrical capacitance or electrical inductance. Optical sensors are frequently used for measuring a workpiece, for verifying workpiece features, and / or for quality assurance during the machining and / or manufacturing of a workpiece. Optical sensors are used especially as components of machine-guided scanners. Optical sensors are understood to be sensors that receive and detect electromagnetic radiation of any wavelength from the workpiece. With regard to the present invention, imaging optical sensors are considered in particular, where the image can be one-dimensional, two-dimensional, or three-dimensional. One-dimensional images are, for example,Two-dimensional images are generated by sensors with a row matrix of sensor elements. For example, standard digital cameras produce two-dimensional images. It is also possible, for instance, to scan two-dimensional areas of the object being measured using point sensors or one-dimensional sensors, thus generating two-dimensional images. Three-dimensional images can be generated, for example, by TOF (Time of Flight) cameras. Stereo camera systems or pattern projection systems offer another possibility.

[0028] In many cases, the sensor forms a structural unit with other components that serve to connect the sensor to the motion device, for example via a quick-change interface, to transmit sensor signals, and optionally to process sensor signals. The sensor unit can also include at least one operating device for the sensor, such as a sensor controller. For example, in the case of a camera, this could be a camera controller, such as a zoom mechanism and / or image capture control. In the case of a tactile sensor, it could be a device for generating a probing force. The structural unit can optionally be connected to and disconnected from the motion device.

[0029] The sensor's physical unit can include an actuator designed to at least partially compensate for the sensor's vibrations. However, it is preferred within the scope of the invention to couple the sensor's physical unit to the motion device via the actuator. In this case, the sensor's physical unit can optionally be decoupled from or coupled to the actuator. This makes it possible, in particular, to couple different sensors to the motion device via the actuator. The various sensors, or their physical units if applicable, behave differently with respect to vibrations. Due to the vibration measurement device and with a corresponding design of the control device, rapid compensation of the sensor's vibrations can be achieved in any case.

[0030] The actuator assembly comprises at least one unit that generates movement of the sensor, which is coupled to the actuator assembly at least during operation of the measuring arrangement, when controlled accordingly by the control unit. This unit can be, for example, an electric motor, such as a linear motor, or a moving coil with a moving armature. An electric motor and a moving coil have means for generating a magnetic field, such as a coil or a coil system, whereby the magnetic field generates a force or torque that drives a moving part.

[0031] The unit that generates movement of the sensor coupled to the actuator, and which is therefore by definition a motor, can also have a different operating principle. For example, piezoelectric elements are suitable as motors. Depending on the desired amplitude of movement, several piezoelectric elements can be combined (especially stacked). Since only small amplitudes of movement are often required to correct vibrations, single piezoelectric elements or combinations of a small number of piezoelectric elements are sufficient in many cases. They are particularly preferred as the linear-axis motors described below.Piezoelectric elements and other motors and actuators with low inertia have the advantage that, through appropriate control using a time-dependent electrical voltage, a compensating movement and / or force can be generated over a wide frequency range. They are therefore well-suited for the common situation in coordinate measuring technology where the frequencies of the excited vibrations can change depending on the state of motion of the motion device and the sensor, the type and mass of the sensor, and whether and with what force the sensor is tactilely probing a workpiece. Even with different resonant frequencies of different sensors, the vibrations of each individual sensor can be compensated in this way without additional effort.

[0032] The arrangement and method described in this document are particularly well-suited for scanning and measuring workpieces, i.e., when measurement information is continuously acquired while the sensor is moving. The sensor is therefore continuously moved to a new position to capture the object being measured.

[0033] According to the claims, the actuator assembly comprises not just one motor, but a plurality of motors. Each motor can be controlled independently of the other motor(s) by the control unit. The plurality of motors are configured and arranged to generate movement with respect to a single linear (straight-line) degree of freedom. In other words, each motor has a linear axis of motion. This makes it possible to compensate for vibrations of the sensor with respect to several linearly independent degrees of freedom. However, the linear axes of motion of the motors do not necessarily have to correspond to independent degrees of freedom, but can also be at angles other than right angles to each other.

[0034] Furthermore, according to the attached claims, the linear axes of motion of at least two motors of the actuator assembly are parallel to each other. The actuator assembly can be rotatable such that the linear motion of at least one of the motors with parallel axes of motion results in a rotational motion of the sensor coupled to the actuator assembly, and optionally in a superposition of the linear motion and a rotational motion. In particular, the motors with parallel axes of motion can be components of a parallel kinematic system. According to the claims, each of the motors with parallel axes of motion is coupled to the motion assembly via a first coupling element and is coupled or can be coupled to the sensor via a second coupling element. The motors with the parallel axes of motion can be coupled to the first coupling element on one side and to the second coupling element on the opposite side.The first and second coupling elements are common to motors with parallel axes of motion. In practice, coupling elements are often referred to as platforms. These are primarily plate-shaped coupling elements.

[0035] A relative movement of the first and second coupling elements is therefore generated by the movement of the respective motor or by several motors. Preferably, the motors with parallel axes of motion are rotatably connected to the first coupling element and / or rotatably to the second coupling element. As claimed, the first coupling element or the second coupling element is each rotatably coupled to the motors with parallel axes of motion via a joint. In particular, three motors with parallel axes of motion can be present. In this case, it is preferred that each of the three motors is rotatably connected to at least one of the coupling elements via a ball joint or a gimbal joint. It is preferred that each joint of the actuator assembly be backlash-free. This applies not only to the embodiment described above.

[0036] In another embodiment of the actuator assembly with a plurality of motors, the linear axes of motion of different motors are neither parallel nor perpendicular to each other. In this case as well, it is preferred that the actuator assembly is coupled to the motion device via a first coupling element and to the sensor via a second coupling element, or that it can be coupled to the sensor. The motors with their linear axes of motion are coupled on one side to the first coupling element and on the opposite side to the second coupling element, and each motor is movably connected to at least one of the coupling elements via a joint (preferably a ball joint or a gimbal joint). A special type of this embodiment is a hexapod, which allows movement of the sensor with respect to all six independent degrees of freedom, i.e.,is made possible by the three independent linear degrees of freedom of motion and the three independent rotational degrees of freedom of motion.

[0037] In an embodiment with only one motor, the actuator can also be coupled to the motion device via a first coupling element and to the sensor via a second coupling element, or be capable of being coupled to them. For example, the first and second coupling elements can additionally be connected to each other via at least one articulated connection, wherein the articulated connection does not include a motor or does not include a motor that drives a movement along a linear axis of motion.

[0038] In any case, the actuator device can have at least one motor by which a linear relative movement of the first and second coupling elements can be generated, in particular a linear relative movement that leads to an increase or decrease in the distance between the coupling elements.

[0039] In particular, the first coupling element can be connected to the second coupling element via a combination of the motor and an articulated joint. This allows for the superposition of linear motion with a rotary motion at the joint, or even just rotary motion if the motor is not currently driving a linear motion that would result in a linear relative motion between the first and second coupling elements in the area of ​​the articulated joint. Specifically, the articulated joint can be implemented as described below.

[0040] An advantageous embodiment of a joint comprises a monolithic body combined with a motor of the actuator assembly. Monolithic means that the body consists of a single piece of homogeneous material. The body is rigid in the direction of movement of the motor and elastically deformable in directions perpendicular to it. The force or movement generated by the motor is therefore transmitted via the joint without alteration. In particular, the monolithic body can thus be part of, or form, a joint connection between the motor and one of the coupling elements. The elasticity in directions perpendicular to it enables linear movements caused by other motors and / or rotational movements or torques generated by several motors with parallel linear axes of motion.An example of a suitable, especially monolithic, body is a cylindrical body such as a metal wire.

[0041] However, in another configuration, the monolithic body can be non-cylindrical, but can have at least one longitudinal section where it exhibits less resistance to elastic deformation than in at least one other section. This elastic deformation causes the body to bend, which corresponds to a rotation of part of the body about an axis of rotation perpendicular to its longitudinal axis. For example, if the body is in a relaxed state and straight along its longitudinal axis, and then bending forces occur, particularly due to movement caused by the associated motor, the body will deform in the at least one longitudinal section with less resistance to elastic deformation, thus becoming curved.However, there are also embodiments in which the monolithic body is already bent in its relaxed state and is brought by the bending forces either into a state of lesser bending (i.e., with a larger bending radius), no bending, or greater bending (i.e., with a smaller bending radius). For example, the monolithic body can be a metal wire that has a recess or circumferential constriction in the aforementioned longitudinal section. A monolithic body with at least one such longitudinal section has the advantage that the bending of the body takes place within a defined area.

[0042] In particular, when designing the monolithic body with at least one such longitudinal section, a guide can be provided which, under the influence of bending forces, guides a relative movement of the first or the second coupling element and the monolithic body along the longitudinal axis of the monolithic body. The guide is connected to the coupling element that performs the relative movement with respect to the monolithic body. The guide directs the relative movement such that the monolithic body moves approximately along its longitudinal axis relative to the guide.

[0043] In other words, an arrangement is proposed in which the actuator is coupled to the motion device via a first coupling element and is coupled, or can be coupled, to the sensor via a second coupling element, wherein the actuator has at least one motor by which a linear relative motion of the first and the second coupling element can be generated. The first coupling element is connected to the second coupling element via a combination of the motor and an articulated connection. - the motor is connected directly or indirectly to the first coupling element on one side and to the second coupling element on the opposite side via the articulated connection, wherein a guide designed to guide the linear relative movement at the articulated connection is connected to the first coupling element, or - the motor is connected directly or indirectly to the second coupling element on one side and to the first coupling element on the opposite side via the articulated connection, wherein a guide designed to guide the linear relative movement at the articulated connection is connected to the second coupling element.

[0044] The procedure for measuring an object can be designed accordingly.

[0045] Particularly if the motor is a linear motor, and especially if it has at least one piezoelectric element, the motor is sensitive to forces acting on it perpendicular to the direction of the linear axis. The linear axis is the axis along which the motor generates linear motion. Preferably, this axis runs approximately in the direction of a longitudinal axis of the articulated connection. In some operating conditions, the linear axis can also run exactly in the direction of the longitudinal axis. This depends in particular on the bending state of the articulated connection. Along this longitudinal axis, the articulated connection connects the motor to the coupling element, which in turn connects the articulated connection to the motor.The guide, which is connected to the other coupling element, therefore not only fulfills the function of guiding the relative movement of the first or the second coupling element along the longitudinal axis, but also stabilizes the motor and thus protects it at least partially from the effects of lateral forces.

[0046] As already mentioned, the articulated connection can consist of a monolithic body that is elastically bent when subjected to a bending force, thereby performing a joint movement. In one embodiment of the method, the articulated connection is therefore used in the form of a monolithic body. It has also been mentioned that the monolithic body can have at least one longitudinal section in which the body exhibits less resistance to elastic deformation than in at least one other section.

[0047] More generally, the combination of at least one linear degree of freedom and at least one rotational degree of freedom, achieved through the design of the actuator assembly, expands the possibilities for compensating sensor vibrations. It is therefore preferred that a plurality of motors are configured and arranged to each generate a movement with respect to a single linear degree of freedom or a single rotational degree of freedom. Several of the motors in the actuator assembly can be part of a parallel kinematic system, as in the case of a hexapod, and / or part of a serial kinematic system. In serial kinematics, the movement of a motor located closer to the actuator assembly also moves all motors located closer to the sensor. "Closer" here refers to their position within the kinematic chain of motors.This does not necessarily mean that the respective motor is geometrically closer, i.e., has a smaller geometric distance.

[0048] For example, the operation of a measuring device can be analyzed with regard to the sensor's vibration amplitudes in relation to a plurality of the six independent degrees of freedom of motion. A suitable actuator design can then be selected that compensates for the sensor's vibrations when appropriately controlled by the control unit, reducing the vibration amplitudes with respect to one or more degrees of freedom to a predetermined maximum amplitude value. The amplitude values ​​for different degrees of freedom can optionally be specified differently. Subsequently, the sensor is coupled to the motion device via the selected actuator, and the sensor's vibrations are at least partially compensated upon subsequent operation of the measuring device.

[0049] At least one of the majority of the actuator motors can be configured to generate rotary motion. Micromotors, such as those used in dental technology, are particularly suitable for this purpose. Especially when only very small movements are required for vibration compensation, the use of motors with linear axes of motion is preferred, as these can be manufactured to be very rigid with respect to other axes of motion. This is particularly true for motors with at least one piezoelectric element. Generally, motors or other actuators, such as force generators, are preferred that are rigid with respect to all other degrees of freedom of motion that are not those degrees of freedom with respect to which the motor or actuator effects or contributes to vibration compensation.

[0050] The arrangement can include a sensor holder designed to hold a sensor configured for detecting the object being measured. In a particular embodiment of the sensor holder, the sensor, or optionally one of several sensors, can be coupled to and detached from the sensor holder. Three-point mountings are known, for example, which are magnetically and / or mechanically secured against unintentional disconnection. The sensor holder can be part of the motion device. In this case, the actuator can be part of the sensor's physical unit and / or part of the sensor holder. If at least part of the actuator can be detached from the sensor holder, then, in addition to the interface for mechanically coupling the sensor's physical unit, an interface for transmitting signals to this part of the actuator can also be provided.The signals must be present for the entire actuator assembly. These signals can be measurement signals from the vibration measuring device and / or control signals.

[0051] If the sensor is not detachably connected to the motion device, then the motion device terminates at the actuator device or at the sensor. In this case, for example, a sensor housing is considered part of the sensor. The actuator device is therefore either part of the motion device or a separate device through which the sensor is coupled to the motion device. In the latter case, it is possible that, in addition to the actuator device, at least one component of the arrangement is provided through which the sensor is directly connected to the motion device, for example, a joint.

[0052] The vibration measuring device can be configured, in particular, to continuously determine and / or measure the position, velocity, and / or acceleration of at least a part of the base, the motion device, the actuator device, and / or the sensor. Alternatively or additionally, it can determine a force on a part or a moment on a part of the motion device, the actuator device, and / or the sensor for measuring a test object. The vibration measuring device therefore has at least one measuring sensor that continuously acquires a primary measured variable of the part, in particular continuously or quasi-continuously. For example, the measured variable can be acquired cyclically, for instance, once in each operating cycle of the measuring sensor or the vibration measuring device.The measured variable can be, for example, the acceleration or the position of the part with respect to at least one degree of freedom of motion, and preferably with respect to all three linearly independent degrees of freedom of motion, and optionally also with respect to at least one rotational degree of freedom of motion. It is particularly preferred that the acceleration of the part is measured with respect to all six independent degrees of freedom of motion. It is also possible that the vibration measuring device includes sensors that measure different primary measured variables, such as, on the one hand, the position and, on the other hand, the acceleration of the part or different parts. The vibration measuring device can, in particular, be a distributed device in which, for example, several measuring sensors are distributed at different locations.Optionally, the vibration measuring device can have a central unit to process the measured values, depending on the design of one or more sensors, and / or output them to the control unit.

[0053] If the primary measured variable is the acceleration of a part, then it is preferred to determine the part's position by double integration over time. When measuring acceleration, it can happen that the measured acceleration systematically deviates from the actual acceleration. If, based on the measured acceleration, the control unit then activates the actuator to at least partially compensate for the sensor's vibrations, the sensor's position can continuously drift away from the desired position. This is also known as "drift." However, such drift can also occur with other configurations for acquiring information about the vibrations of the arrangement and / or the sensor.To avoid this, it is preferred that, in addition to the acceleration, a position or other measurement relevant to the sensor's position is measured (for example, at the sensor, the actuator, the motion device, or the base), and that the measured position value is taken into account by the control unit. Capacitive displacement sensors or strain gauges, for example, are also suitable as position sensors.

[0054] If the primary measured quantity is the force on the part, this can be converted into the part's acceleration, for example, using the oscillating mass, and then proceeded as with measuring acceleration. However, it is also possible to determine the required counterforce to compensate for the sensor's vibrations from the measured force and to control the actuator accordingly.

[0055] It is preferred that not only the sensor's acceleration is determined, either by direct measurement at the sensor and / or indirectly at the assembly, and used for at least partial compensation of the sensor's vibrations, but also that the acceleration of the workpiece being measured or to be measured by the sensor is measured. In this case, the difference between the sensor's acceleration and the workpiece's acceleration is used as time-dependent information to compensate for the sensor's vibrations by controlling the actuator. This has the advantage that vibrations of the workpiece can also be at least partially compensated. For the workpiece measurement, it is important that the sensor and the workpiece are as vibration-free as possible relative to each other.To measure the acceleration of the workpiece, at least one acceleration sensor can be arranged near the workpiece, for example on a workpiece holder.

[0056] When this description refers to the position of the sensor, it specifically refers to the position of the so-called TCP (short for the English technical term "Tool Center Point").

[0057] Furthermore, it is preferred that the sensor's acceleration is high-pass filtered before the corresponding information is used to control the actuator. In other words, the at least partial compensation of the sensor's vibrations preferably takes place based on high-pass filtered acceleration measurements for the sensor. This is based on the understanding that low-frequency accelerations, which result at least to a large extent from the sensor's movement by means of the motion device, are both intended and can be compensated for by other vibration correction measures, for example, directly at the drives. The amplitudes of vibrations due to these low-frequency accelerations are generally considerably larger than the amplitudes of the high-frequency vibrations at the sensor. High-pass filtering is therefore also advantageous because the required travel distances, i.e.,The amplitudes generated by the actuator are smaller, allowing the actuator to be designed in a correspondingly more compact and smaller form. For example, in many cases, piezoelectric elements can be used as the actuator's motors, unlike motors, especially those with electromagnetic drives, or other actuators with a larger travel distance than piezoelectric elements. This also reduces the inertia of the motors and the entire actuator, enabling faster response to and compensation of excited vibrations. One method of high-pass filtering involves using an accelerometer that is not sensitive, or only minimally sensitive, to low-frequency accelerations.

[0058] Preferably, the acceleration with which the sensor is moved by the motion device is subtracted from the acceleration measured for the sensor, and the vibrations of the sensor are at least partially compensated based on the resulting difference. In particular, the resulting difference can be high-pass filtered as described above. The acceleration with which the sensor is moved by the motion device is, in particular, the acceleration known to the control system of the motion device, especially the target acceleration or the acceleration obtained from a measuring system of the motion device and / or at least from the drive of the motion device. In particular, the acceleration with which the sensor is moved by the motion device can be constant, at least temporarily, non-periodic, and / or have exclusively low frequencies.This allows a significant portion of the acceleration acting on the sensor to be easily eliminated and therefore not taken into account for at least partial compensation of the sensor's vibrational movements.

[0059] One advantage of the invention is that the measuring sensors can be arranged on one or more parts of the arrangement that are kinematically further away from the sensor than the actuator assembly. While it is possible to arrange a measuring sensor for acquiring the primary measurement variable of the vibration measuring device directly on the sensor for measuring a workpiece, this results in additional effort, particularly with interchangeable sensors, for providing the measuring sensor and for transmitting the measured information to the control unit. Although the actuator assembly is arranged close to the sensor for measuring a workpiece so that the sensor's vibrational movement can be compensated for with low inertia.However, information about the vibrational motion can also be measured remotely from the sensor, particularly at at least one part of the actuator assembly, the motion device, or the base of the arrangement. For example, the information can be measured in at least one local area where vibrations of the motion device are excited, such as in the area of ​​a drive or at the base.

[0060] If the information about the vibrations is not measured at the sensor, or not exclusively, then it is preferred that the control device uses a mathematical and / or physical model (in particular a computer-implemented model) to control the actuator device in order to at least partially compensate for the sensor's vibrations. The model makes it possible, in particular, to estimate and / or calculate how the sensor would vibrate if the vibration were not compensated.

[0061] In any case, it is preferred that information about the amplitude (in particular the three-dimensional amplitude vector), the phase position and the frequency of the sensor's vibrations is determined from the information about the at least one measured quantity at at least one part of the arrangement or the sensor or the base, and that the control device controls the actuator device accordingly to at least partially compensate the vibrations.

[0062] In particular, the actuator can be controlled by the control unit using frequency feedback, whereby frequency feedback is understood to mean the generation of a counter-movement to the oscillation with the same frequency and approximately the same or the same amplitude. During the counter-movement to the oscillation, the sensor would move in the opposite direction to the oscillation. However, since the oscillation is wholly or partially compensated by the corresponding control of the actuator, neither the uncompensated oscillation nor the counter-movement with the full amplitude occurs. Only if an oscillation has been newly excited or modified can it take part of an oscillation period or longer for the compensation to take effect. At the beginning of this phase of the movement, the oscillation still occurs with almost the full amplitude.Even in this phase, the sensor does not perform a counter-movement, unless the oscillation is temporarily overcompensated.

[0063] The control signal according to the frequency feedback can be applied with at least 10 percent, in particular at least 20 percent, and preferably at least 40 percent of the vibration amplitude determined using the vibration measuring device. From these minimum values, significant at least partial compensation of the sensor's vibration can be achieved. Alternatively or additionally, the control signal according to the frequency feedback can be applied with a maximum of 90 percent, in particular at most 80 percent, and preferably at most 70 percent of the vibration amplitude determined using the vibration measuring device. Frequency feedback with the aforementioned maximum values ​​has the advantage that, in many cases, overshoot of the compensation, i.e., an out-of-phase movement of the sensor opposite to the excited vibration, can be avoided.

[0064] The control unit can include a microprocessor or be implemented by a microprocessor, which is particularly important as part of a modular unit that also includes the actuator. A programmable processor, such as an FPGA (Field Programmable Gate Array), is a particularly suitable microprocessor. In any case, the microprocessor, which may optionally be composed of multiple processor units, has control logic according to which the actuator is controlled to at least partially compensate for the sensor's vibrations. Specifically, the microprocessor can be connected to the data bus mentioned below and receive the information required to control the operation of the actuator via this bus. A power supply for the microprocessor is also optionally provided via the data bus.

[0065] An exemplary embodiment of a control system is now described that is capable of controlling the actuator, taking into account information about vibrations of the sensor, the motion device, and / or at least one device connected to the motion device and / or the sensor, in such a way that the sensor's vibrations are at least partially compensated. In particular, a state-level control system can be used, in which values ​​of two or more state variables, such as the position and velocity or the position and acceleration of the sensor, constitute input variables for the control system. Alternatively or additionally, a cascaded control system similar to that frequently used in coordinate measuring machine drives is possible. Depending on the type of actuator, the speed control, in particular, can be omitted, unlike in drive control.In this case, only, for example, a current control for the respective motor of the actuator device and a position control of the sensor's position are cascaded.

[0066] In particular, the control system can be designed as described in US 2018 / 0106586 A1, using the aforementioned information about the sensor's position or position(s) meaningful to the sensor's position instead of position measurements from the coordinate measuring machine's position measurement system. The acceleration measurements used for the control system described in the document are those of the aforementioned at least one measuring sensor. The computational model mentioned in the document can be the mathematical and / or physical model mentioned above.

[0067] One embodiment of the arrangement features a signal connection from the vibration measuring device, in particular from the measuring sensor or sensors, to the control unit. Preferably, the signal connection is a data bus, especially a real-time data bus. Such a bus has the advantage that not only signals containing measurement information but also signals containing other information can be transmitted. In many cases, existing measuring arrangements already have a data bus.

[0068] Exemplary embodiments of the invention will now be described with reference to the accompanying drawing. The individual figures in the drawing show: Fig. 1 schematically a jointed robot arm with a sensor arranged at the free end of the jointed arm for measuring a workpiece, Fig. 2 schematically a horizontal arm measuring device, Fig. 3 schematically a coordinate measuring machine in portal design, Fig. 4 an actuator assembly with three motors, wherein a sensor is arranged on the actuator assembly, Fig. 5 a side view of the motors of the actuator assembly Fig. 4, wherein one of the three motors has contracted and therefore a rotary movement of the actuator assembly has taken place, Fig. 6 a top view of the actuator assembly Fig. 4 and Fig. 5 Fig. 7 another actuator arrangement forming a serial kinematics arrangement, in which a first stage of the kinematics provides a rotational degree of freedom of movement and a second stage of the kinematics provides a linear degree of freedom of movement, Fig. 8 an actuator device designed as a hexapod, Fig. 9 schematically an arrangement with a plurality of measuring sensors, a control device and an actuating device, Fig. 10 a schematic detailed representation of a part of an actuator assembly, for example one of the based on the Fig. Actuator devices described in sections 4 to 8, wherein a coupling element is connected to another coupling element via a motor, in particular a linear motor, and via an articulated connection, Fig. 11 the actuator assembly Fig. 10 in a different operating state in which the articulated connection is bent and parts of the articulated connection are therefore different from the operating state of Fig. 10 are shifted, Fig. 12 A schematic representation of part of an actuator assembly similar to the one in Fig. 10 and Fig. 11 Actuator device shown, however, the articulated connection only has one longitudinal joint section which is more easily elastically deformable under the influence of bending forces than other longitudinal sections and therefore functions as a joint. Fig. 13 the actuator assembly Fig. 12 in a different operating state in which the articulated connection is bent and part of the articulated connection is therefore opposite to the operating state of Fig. 12 is shifted.

[0069] The in Fig. The articulated robot 1 shown in Figure 1 has, in embodiment 5, arms 3 coupled to each other in pairs via a joint 4. A first arm 3a is connected to the stationary base 2 of the articulated robot 1 and is immobile except for unintentional vibrations. In an alternative embodiment, this arm can be rotatably coupled to the base. The first arm 3a is connected to a second arm 3b via a first joint 4a. The second arm 3b is connected to a third arm 3c via a second joint 4b, which in turn is connected to a fourth arm 3d via a third joint 4c. In the embodiment, the last arm, with its free end, is a fifth arm 3e, which is connected to the fourth arm 3d via a fourth joint 4d. At the free end of the fifth arm 3e is a coupling element 5, which in the embodiment is designed as a platform.Actuators of an actuator assembly 8 are arranged on the side of the first coupling element 5 opposite the fifth arm 3e. Exemplary embodiments of the actuators and actuator assemblies will be discussed in more detail later. When at least one actuator of the actuator assembly 8 is moved, for example by contraction or expansion of an actuator, a second coupling element 6, which is connected to the actuators of the actuator assembly 8, is moved relative to the first coupling element 5. Depending on the design of the actuator assembly, any combination of degrees of freedom of movement can be provided in this way, and corresponding movements can be executed. A sensor for measuring a workpiece 10 is connected to the second coupling element 6 on the side opposite the actuator assembly 8.

[0070] The arrangement formed by the articulated robot arm 1 and the sensor 7, for example a camera for capturing two-dimensional images, is connected to at least one measuring sensor of a vibration measuring device. The possible types of measuring sensors for obtaining information about vibrations of the arrangement, and in particular of the sensor that measures a workpiece during operation, have already been discussed. Specifically, this involves an accelerometer. The number of measuring sensors of the vibration measuring device can also vary depending on the embodiment. In the Fig. In the embodiment shown in Figure 1, two measuring sensors are provided for the vibration measuring device. A first measuring sensor 9a is connected to the base 2. In this way, vibrations of the base 2, which are transmitted to the sensor 7 via the articulated arm, can be measured, particularly when the first measuring sensor 9a is configured as an accelerometer. A second measuring sensor 9b, preferably also an accelerometer, is connected to the fifth arm 3e.

[0071] As shown by dashed lines in Fig. As shown in Figure 1, the measuring sensors 9a, 9b and the actuating devices of the actuator assembly 8 are connected to a control unit 19. This control unit is designed to control the actuator assembly and, in particular, its actuating devices independently of one another in such a way that the vibrational movements of the sensor are at least partially compensated.

[0072] In Fig. 1 and also Fig. 2 and Fig. Figure 3 shows exemplary embodiments of measuring arrangements in which the sensor for measuring a workpiece is connected to a motion device via an actuator. Since the actuator provides at least one degree of freedom of movement, this connection can be described as a movable coupling.

[0073] As mentioned above, sensors can be interchangeably mounted on the moving parts of measuring setups or can be a permanent component of the measuring setup. In particular, this is possible, for example, with the articulated arm robot made of Fig. 1. The second coupling element 6 may be provided with an interchangeable interface for the releasable attachment of the sensor 7. It is possible, though not preferred, that the first coupling element 5 may instead or additionally have such an interchangeable interface. In this case, the actuator 8 can be removed from the articulated arm of the articulated robot 1. A different actuator can then be mounted in its place. Alternatively or additionally, an actuator can be omitted, at least temporarily, and a sensor can be connected directly to the first coupling element 5. This description of the possibilities for coupling sensors and actuators is not limited to the embodiment shown in Figure 1. Fig. 1. Limited. For example, the designs of measuring arrangements that are in Fig. 2 and Fig. The figures shown in 3 should also be designed in this way.

[0074] Especially the in Fig. 1. The measuring setup shown, but also any other

[0075] A measuring arrangement, such as an articulated robot with more than five or fewer than five arms, increases the measurement accuracy when measuring workpieces and / or reduces measurement times. Particularly when scanning workpieces, the actuator, which at least partially compensates for sensor vibrations, allows for faster movement of the sensor 7 relative to the workpiece 10 while maintaining the same measurement accuracy. Alternatively, the movement can be as slow as with conventional measuring arrangements, and the measurement accuracy is increased because sensor vibrations are at least partially compensated.

[0076] In the following exemplary embodiments of a measuring arrangement according to Fig. 2 and Fig. 3 is not like the design of the Fig. 1 a control device is shown. However, it can be used in the same way as in Fig. Figure 1 shows that a control unit is always present for the actuator assembly. Generally, not only with regard to the embodiments shown in the figure description, the control unit, which serves to actuate the actuator assembly in order to at least partially compensate for vibrations of the sensor, can be a separate control unit from the control unit of the measuring arrangement. Alternatively, it can be integrated into the control unit of the measuring arrangement. The control unit of the measuring arrangement controls, in particular, the movements of the motion devices and optionally also performs functions related to the evaluation of the measurement information acquired by the sensor during the measurement of the workpiece or other object. For example, the control unit can determine the coordinates of the measured workpiece in a known manner.

[0077] The in Fig. The horizontal-arm coordinate measuring machine 21 shown in Figure 2 has a base 22. Extending upwards from the base 22, a first arm 23a supports a second, horizontally extending arm 23b. The arms 23 form a movement mechanism. The movements of this movement mechanism are not described in detail here, as they are generally known. In particular, the horizontal arm 23b is movable in a horizontal direction along its longitudinal axis. This movement can cause vibrations of the sensor 27, which is attached to the free arm on the right. Fig. The end of the horizontal arm 23b shown in Figure 2 is coupled to the horizontal arm 23b via a joint 4 and an actuator assembly 8. The joint 4 allows the sensor 27 to be aligned in different directions.

[0078] The one in the upper right corner Fig. The curved double arrow shown in Figure 2 can indicate a rotational movement that can be executed by means of joint 4. In any case, this curved double arrow indicates oscillatory movements corresponding to a rotational degree of freedom of the motion, the axis of rotation of which is perpendicular to the plane of the figure. Fig. 2. Furthermore, a straight double arrow is shown above the horizontal arm 23b. This indicates that the horizontal arm can oscillate up and down in its longitudinal direction, particularly when performing a movement. An embodiment of the actuator device 8, which can specifically compensate for these two degrees of freedom of movement with respect to vibrations of the sensor, will be described later with reference to Fig. Section 7 was discussed in more detail. The actuator assembly of the... Fig. 7 but not only for use in the in Fig. The measuring arrangement shown in section 2 is suitable, but also for other measuring arrangements.

[0079] The actuator unit 8 in Fig. 2 is like in Fig. Figure 1 is shown schematically. Any embodiment of an actuator device can be used, which can be coupled via a first coupling element 5 on the one hand to the motion device of the measuring arrangements and via a second coupling device 6 on the other hand to the sensor for improving a measured object.

[0080] At the in Fig. The sensor 27 shown in Figure 2 is a tactile sensor with a stylus 28. However, this is similar to the sensors shown in Figure 2. Fig. 1 and Fig. The three illustrated embodiments of a measuring arrangement are merely an example. Other sensor types can be used. Therefore, as already mentioned, in Fig. 1 a camera is indicated as sensor 7 and is in Fig. 3 an optical sensor 37 indicated, which may be, for example, a confocal sensor or a triangulation sensor.

[0081] The vibration measuring device of the in Fig. The measuring arrangement shown in 2, in contrast to the measuring arrangement in Fig. The invention uses three measuring sensors instead of two in the vibration measuring device. However, the number of measuring sensors in a vibration measuring device according to the invention is not limited to two or three. Information about the sensor's vibrations can be obtained with just a single measuring sensor. More than three measuring sensors can also be provided. In particular, each measuring sensor can be arranged in a different area of ​​the measuring arrangement than the other measuring sensors.

[0082] In the exemplary embodiment of the Fig. 2 A first measuring sensor is connected near the base 22 to the first, vertically extending arm 23a. This allows vibrations transmitted from the base 22 to the motion device and thus also to the sensor to be measured. A second measuring sensor 9b is connected to the horizontal arm 23 near its free end.

[0083] This allows vibrations near joint 4 to be measured. Furthermore, a third measuring sensor 9c is arranged directly next to sensor 27, through which the vibrations of sensor 27 can be measured directly.

[0084] Although vibrations can be measured directly at the sensor using the third measuring sensor 9c, the additional measuring sensors 9a and 9b are advantageous. For example, if vibrations are transmitted to the motion device via the base 22 and the excitation of these vibrations begins, the first measuring sensor 9a detects these vibrations earlier than the third measuring sensor 9c at the sensor 27 used for measuring the workpiece. Therefore, an early response is possible, and a counter-movement can be generated by the actuator device as soon as the sensor begins to vibrate, or would begin to vibrate, due to the excitation at the base 22. In many cases, sensor vibration can then be completely avoided. The same applies to the excitation of a sensor vibration due to a vibration of the horizontal arm 23b. In this case, the second measuring sensor 9b measures the vibration earlier than the third measuring sensor 9c at the sensor 27.

[0085] In Fig. Figure 3 shows a coordinate measuring machine 31 in a portal design. The motion mechanism of this coordinate measuring machine is not described in detail here, as it is generally known. In particular, a portal 33 is movable along a base 32. A quill 34 is movably coupled to the portal 33 in a manner also known. At the lower end of the quill is an actuator 38 for compensating vibrations of the sensor, here the sensor 37. The workpiece is again, as also in Fig. 2 and Fig. 1, designated with reference numeral 10. The in Fig. The measuring arrangement shown in section 3 again has three measuring sensors of the vibration measuring device. A first measuring sensor 9a is arranged at the base of the portal 33 and serves a similar purpose to the embodiments of the Fig. 1 and Fig. 2. The measurement of vibrations transmitted to the motion device via the base 32. A second measuring sensor 9b is arranged at the lower end of the quill 34, where the quill 34 is connected to the first coupling element 5. A second coupling element is included in the design of the Fig. 3 not as in Fig. 1 and Fig. 2 present, but as sensor base 36 of the sensor 37. The third measuring sensor 9c is arranged on this sensor base 36 in order to be able to measure vibrations directly at the sensor 37.

[0086] The following describes an embodiment of an actuator device, which is particularly useful in the measuring arrangements of the Fig. 1 to Fig. 3 can be used. The special feature of this type of actuator device, which is now based on Fig. The difference described in section 4 lies in the fact that a plurality of actuators, in particular motors, are present, each of which can individually generate a linear motion. As already described above, they have a linear axis of motion. In the type of actuator system described here, the axes of motion of several motors or actuators are parallel to each other. However, each of the motors is connected to a coupling element via a joint. This coupling element is preferably, but not necessarily, the same for all motors with parallel axes of motion. If it is not the same coupling element, the axes of motion of all motors are only parallel to each other in a neutral state of motion and otherwise form an angle to each other or are skew to each other.

[0087] The special embodiment of the Fig. Figure 4 has three motors 41a, 41b, 41c. However, it is also possible to provide only two or more than two motors with parallel axes of motion. The motors can be further specified, for example for a single motor, by means of Fig. As described in section 7, the coupling elements can also be combined with joints which, together with connecting elements, directly connect the two opposing coupling elements. Each joint, according to its design, restricts the relative movement possibilities of the two coupling elements. However, multiple motors with parallel or non-parallel axes of motion also intentionally restrict the movement possibilities.

[0088] At the in Fig. In the embodiment shown in Figure 4, the three motors 41 are rigidly connected to the second coupling element 46, via which the sensor 49 is connected for measuring a measuring object. However, in other embodiments, the motors can also be connected to the first coupling element, via which the actuator assembly is connected to the motion mechanism of the measuring arrangement. The three motors 41 are, in the embodiment shown in Figure 4, rigidly connected to the second coupling element 46, via the sensor 49 for measuring an object. Fig. In the embodiment shown in Figure 4, each coupling element 42a, 42b, 42c is connected to the first coupling element 45 via a joint. In this particular embodiment, the control unit 47 for controlling the motors of the actuator assembly 48 is located on the first coupling element 45. The control unit 47 is connected, for example, via a data bus (not shown) to at least one measuring sensor of the arrangement in order to obtain the information required for vibration compensation.

[0089] The three engines 41 are, as shown by the schematic top view of the Fig. Figure 6 shows that the forces are evenly distributed in the circumferential direction of the second coupling element 46. As will be described in more detail below, this enables movements corresponding to a multitude of independent degrees of freedom. In the top view of the Fig. The joints 42 and the first coupling element 45 are omitted.

[0090] In the embodiment described here, the joints 42 are designed as monolithic, in particular cylindrical, bodies that connect the respective motor 41 to the first coupling element 45 in the manner of wires. The monolithic bodies are very rigid in the direction of their respective longitudinal axis, but they can be elastically bent, as is the case, for example, in the Fig. The movement state shown in section 5 is the case for joint 42b.

[0091] The side view of the Fig. Figure 5 only shows the first motor 41a and the second motor 41b, as the third motor 41c is obscured by the second motor 41b. The in Fig. The motion state shown in Figure 5 arises from a contraction of the first motor 41a, which is designed, for example, as a stack of piezoelectric elements. This shortens the distance between the first coupling element 45 and the second coupling element 46 in the region of the first motor 41a and its joint 42a. The elastically bendable elements 42b and 42c of the second motor 41b and the third motor 41c bend as shown in Figure 5. Fig. 5 shown. Fig. 6 shows the corresponding axis of rotation represented by a dashed line, with the dashed line pointing in the direction of view. Fig. 6 lies before the second coupling element 46 and in the representation of the Fig. 5 lies in the area of ​​the first coupling element 45, as shown by a cross. The position of the axis of rotation is not fixed with respect to the actuator assembly 48 and changes slightly due to the contraction or expansion of the respective motor.

[0092] But it is not only based on Fig. 5 and Fig. The rotational degree of freedom of movement described in section 6 is provided by the actuator device 48. Rather, corresponding rotational movements of 120° each around the perpendicular to the plane of the figure are possible. Fig. The rotation of the second coupling element 46 can be performed on a rotating axis of rotation if only the second motor 41b or the third motor 41c contracts or expands. By combining contractions or expansions of all three motors 41, arbitrary tilting movements of the second coupling element 46 relative to the first coupling element 45 can even be achieved. Naturally, the maximum tilting angle is limited by the maximum possible expansions / contractions of the motors and their distances from each other. Furthermore, also limited by the maximum possible expansions / contractions of the motors, linear movements of the two coupling elements 45 and 46 can be achieved in any tilting position relative to each other. The linear movement is perpendicular to the surface of the second coupling element 46, that is, parallel to the axes of movement of the motors 41.Furthermore, superpositions of the aforementioned rotational and tilting movements and linear motion are possible. Linear movements perpendicular to the motors' axes of motion are not possible. Overall, however, movements with respect to the three rotationally independent degrees of freedom and in the direction of the aforementioned motors' axes of motion are enabled.

[0093] Based on Fig. 4 to Fig. The type of actuator device described in section 6, with motors whose axes of motion are parallel to each other, represents only one form of parallel kinematics; another form of parallel kinematics will be described later using… Fig. 8 described. In any form of parallel kinematics, in particular a first coupling element and a second coupling element can be movably connected to each other via the actuating device.

[0094] However, an actuator assembly can also have serial kinematics. In such serial kinematics, at least one actuating device forms one movement stage, and at least one further actuating device forms another movement stage. A specific embodiment of such serial kinematics will now be described using the following examples: Fig. 7 described.

[0095] In this embodiment, a first coupling element 65, via which the actuator 68 can be connected to, or is connected to, the motion device of a measuring arrangement, again incorporates the control unit 47 for controlling the motors. As in the other embodiments, the control unit can instead be located elsewhere and, for example, be implemented by controlling the measuring arrangement. Furthermore, a second coupling element 66 is provided. As in other embodiments of actuator assemblies, the coupling elements can be implemented as platforms with surfaces that are parallel and facing each other in a neutral state of motion. According to the principle of serial kinematics, a third coupling element 67 is present; the second coupling element 66 forms the transition or interface between the first and second motion stages.The first movement stage begins at the first coupling element 65. The second movement stage ends at the third coupling element 67. In this embodiment, the first movement stage is configured such that only one of the six independent degrees of freedom is realized, namely a rotational degree of freedom. In this embodiment, the second movement stage also has only a single independent degree of freedom, which is a linear degree of freedom. However, serial kinematics for the actuator device according to the invention are not limited to each movement stage offering only a single degree of freedom. Rather, for example, the first movement stage can be configured as follows: Fig. 7 by such a device with an additional rotational degree of freedom of movement and / or at least one additional linear degree of freedom of movement.

[0096] Returning to the example of the Fig. In the first movement stage, a motor 41a has a linear axis of motion perpendicular to the surface of the second coupling element 66. Additionally, two joints 62a and 62b are attached to the second coupling element 66, and each of these two joints 62 is connected to the first coupling element 65 via a connection 61a or 61b that is also rigid with respect to bending. The joints 62 enable a rotational movement of the first coupling element 65 relative to the second coupling element 66 about an axis of rotation parallel to the surface of the second coupling element 66, which is located in the Fig. 7 is indicated by a dashed line. This movement is achieved by a contraction / expansion of the first motor 41a, whose axis of movement is perpendicular to the surface of the second coupling element 66. This results in a rotational movement of the joint 42a, through which the first motor 41a is connected to the first coupling element 65. In this embodiment, the joint 42a, as in the embodiment of the Fig. 4 to Fig. 6 is designed as a monolithic body. A corresponding rotational movement of joint 42a therefore leads to bending of the monolithic body.

[0097] In this embodiment, the second motion stage is realized by a single, second motor 41b, whose linear axis of motion is perpendicular to the coupling elements 66, 67, which are designed as platforms. Overall, the serial kinematics of the actuator assembly 68 thus realizes a combination of a single rotational degree of freedom with a single linear degree of freedom. Of course, serial kinematics can provide further degrees of freedom, for example, a second rotational degree of freedom for the first motion stage. Furthermore, serial motion kinematics can have additional motion stages, such as a third motion stage with an additional linear degree of freedom. Multiple motion stages can also provide combinations of at least one rotational and one linear degree of freedom.This is also possible for just one movement level.

[0098] In particular, the actuator device 68 according to Fig. The realized combination of one rotary and one linear degree of freedom of movement is particularly well suited for compensating for vibrations of the sensor 27 on the horizontal arm measuring device 21. Fig. 2. Suitable. Serial kinematics can therefore be used instead of the one in Fig. Actuator assembly 8 shown in Figure 2 is provided, in which the first coupling element 5 is replaced by the first coupling element 65 and the second coupling element 6 is replaced by the third coupling element 67. The serial kinematics are located between them. The rotational degree of freedom of the motion enables vibration compensation with respect to the force indicated by the curved double arrow in Figure 2. Fig. 2 indicated axes of rotation. The linear degree of freedom of the motion allows for vibration compensation with respect to the vertical direction of vibration, which is shown in Fig. 2 is indicated by a straight double arrow.

[0099] A particularly advantageous actuator device 71, especially well suited for articulated-arm robots, is a hexapod, as described in Fig. Figure 8 shows the first coupling element 65 at the top of the illustration. The actuator assembly 71 can be connected, or is connected, to the motion device of a measuring arrangement via this coupling element. The actuator assembly is connected, or can be connected, to a sensor via the second coupling element 66 on the opposite side. Each of the coupling elements 65 and 66 has a set of six gimbal-mounted joints 69 and 70 on its facing surface. The gimbal-mounted joints attached to the first coupling element 65 are designated by reference numerals 69a to 69f, and those attached to the second coupling element 66 are designated by reference numerals 70a to 70f.As is generally known in a hexapod, the joints are arranged in pairs close together, and each motor 41a to 41f is coupled to the coupling elements 65 and 66 via a joint 69 on the first coupling element 65 and a joint 70 on the second coupling element 66. Each of the motors 41 has a straight axis of motion. However, the axes of motion of the motors 41 are never all parallel to each other simultaneously, especially not in a neutral position where the surfaces of the coupling elements 65 and 66 are parallel to each other. The axes of motion of the two motors 41 attached to the closely arranged pairs of joints 69 and 70 form a V-shape relative to each other, with the opening angle and orientation of the V varying slightly depending on the hexapod's state of motion.

[0100] Furthermore, as already mentioned, the gimbal-mounted joints 69 and 70 form pairs of closely spaced joints. The pair of motors 41 assigned to a pair of joints 69 is not also a pair of motors assigned to a pair of joints 70. Rather, for example, the first motor 41a couples the first joint 69a on the first coupling element 65 with the first joint 70a on the second coupling element 66, forming a pair of closely spaced joints with the sixth joint 70f on the second coupling element 66. Conversely, the first joint 69a on the first coupling element 65 forms a pair of closely spaced joints with the second joint 69b on the first coupling element, and so on.

[0101] A hexapod has the advantage that not only the [missing information] can be [missing information] based on [missing information]. Fig. 4 to Fig. The actuator assembly described in section 6, 48, does not enable four independent degrees of freedom of movement, but rather all six independent degrees of freedom. Therefore, the hexapod also gains the two missing linear degrees of freedom of movement. It is thus possible to adjust the coupling elements, designed as platforms in this and other embodiments, parallel to each other in all three linearly independent directions of movement. Naturally, it is also possible to adjust the platforms, which are not aligned parallel to each other, relative to each other with respect to the three linearly independent degrees of freedom of movement.

[0102] Based on the schematic representation of the Fig. Section 9 now describes the processing of measurement information about the vibration movements of the sensor and other parts of the measurement arrangement, as well as the generation of control signals for the control of the actuator device in order to at least partially compensate for the vibration movements of the sensor.

[0103] Fig. Figure 9 schematically shows a plurality of measuring sensors 9 in the upper part of the figure. Specifically, a first measuring sensor 9a, a second measuring sensor 9b, and an nth measuring sensor 9n are shown, where n is a natural integer. Therefore, any number of measuring sensors can be present. The measuring sensors 9 are parts of a vibration measuring device 72, whereby the individual measuring sensors can be distributed across the measuring arrangement. The vibration measuring device also does not have Fig. The internal measurement signal transmission means shown in section 9 are used on and / or utilize transmission means of the measurement setup, such as the aforementioned data bus. However, the transmission of measurement information from the measuring sensors to the control unit 19 does not necessarily have to be wired. Rather, it is also possible to transmit the signals relating to the measurement information and / or information obtained through processing wirelessly, for example, via radio. Optical transmission links without fiber optics are also possible. Furthermore, fiber optics can also be used to transmit optical signals.

[0104] Returning to Fig. The measurement signals generated by the measuring sensors 9 and optionally further processed by the vibration measuring device 72 are transmitted to an optional preprocessing unit 73 of the control unit 19. If no preprocessing takes place or the preprocessing unit 73 is not present, the signals are transmitted directly from the vibration measuring device 72 to the counter-motion calculation unit 75. If preprocessing by the preprocessing unit 73 takes place, then, in particular, the previously mentioned difference calculation for non-periodic or low-frequency accelerations during the movement of the sensor by the motion device can be performed. Alternatively or additionally, the previously mentioned high-pass filtering can take place during preprocessing.Alternatively or additionally, the time-dependent measurement information about the vibration movements can be smoothed so that implausible fluctuations are reduced or eliminated.

[0105] This corresponds to high-pass filtering. Therefore, it is particularly preferred that the information about the vibrational motions be band-pass filtered.

[0106] It should be clarified once again that the measurement information from the measuring sensors is continuously generated and processed in order to at least partially compensate for the vibrational movements of the sensor.

[0107] The information preprocessed by the preprocessing unit 73, or, as mentioned, the information obtained from the vibration measuring unit 72, is fed to the counter-motion calculation unit 75. This unit calculates the counter-motion corresponding to the current or expected vibration of the sensor, or alternatively, a corresponding counterforce. The counter-motion is calculated, for example, by phase-shifting the vibration by 180° (i.e., by half a vibration period).

[0108] The information about the resulting counter-movement or counter-force is output to a control signal generation device 77, which generates and outputs the corresponding control signals for controlling the actuator device and in particular the individual control signals of the motor or motors of the actuator device.

[0109] The in the Fig. Parts 10 to 13 of an actuator assembly shown can be used, in particular, in one of the actuator assemblies of the Fig. 4 to Fig. 8 may be provided, for example the area of ​​the motor 41a and the joint 42a of one of the actuator devices of the Fig. 4 to 7 form or each the area of ​​one of the motors 41a, 41b, 41c and the joint 42a, 42b, 42c of one of the actuator devices of the Fig. Form 4 to 6.

[0110] The ones in the Fig. The parts of an actuator assembly shown in Figures 10 to 13 are supplemented by an additional articulated connection between the motor 41 and the second coupling element 56, such that the motor 41 is connected to the second coupling element 56 via this additional articulated connection. Such an arrangement can form the area of ​​one of the motors 41a to 41f and the two joints associated with the motor. Each of the motors 41a to 41f is associated with one of the joints 69a to 69f and one of the joints 70a to 70f. The respective motor with the two associated joints forms a double-jointed connection of the coupling elements 65, 66.

[0111] Fig. Figure 10 shows an actuator device 58 with a first coupling element 55 and a second coupling element 56. Each of these two coupling elements 55, 56 can be any of the in Fig. 4 to Fig. The 8 coupling elements shown are connected. This means that the first coupling element 55 can also be, for example, the second coupling element 46 in Fig. It can be 4.

[0112] The motor 41 is connected to the second coupling element 56 on one side (the lower side of the motor 41 in the illustration). Contrary to what is shown, this connection can also be indirect, i.e., the motor 41 can be connected to the second coupling element 56 via an additional connecting element. On the opposite side of the motor 41 (the upper side of the motor 41 in the illustration), the motor 41 is connected to the first coupling element 55 via a monolithic body 42, which forms a hinged connection.

[0113] The monolithic body 42, for example a metal wire, has two elastic longitudinal sections 53 that function as hinges by having a constriction at these points. The constriction is created, for example, by milling or turning a circumferential groove. Although the monolithic body 42 is made of a homogeneous material and is therefore elastic throughout, due to the constriction, bending forces acting on it cause bending almost exclusively at the constrictions and thus in the two elastic longitudinal sections 53.

[0114] A guide 51a, 51b is located on the longitudinal section between the two elastic longitudinal sections 53. This guide is formed, for example, by two opposing jaws or shells that partially encompass these longitudinal sections. The guide 51a, 51b is connected to the second coupling element 56 via a support 50a, 50b. The support 50a, 50b can, for example, be implemented by rigid leaf springs that remain curved along their course from the second support 56 to the guide 51a, 51b, even in the relaxed state or in the state of minimum tension.

[0115] The guide 51a, 51b guides the movement of the monolithic body 42 in its longitudinal direction when the motor 41 (which is, for example, a linear motor and in particular a motor with at least one piezoelectric element) generates such a movement.

[0116] Fig. Figure 11 shows that the monolithic body 42, acting as a hinged connection, can undergo a pivoting or rotational movement through bending in the two elastic longitudinal sections 53, thereby changing the orientation of the first coupling element 55 relative to the second coupling element 56. This also causes the support 50a, 50b to bend, thus absorbing some of the lateral forces that would otherwise act on the motor 41.

[0117] The in Fig. The operating state shown in 11 is different from the one in Fig. However, the operating state shown in Figure 10 was not caused by a linear movement of the motor, but by a movement of another part of the actuator assembly. This other part is located in the Fig. 10 and Fig. 11 not shown. The movement could, for example, have been caused by another of the motors 41b, 41c, if the one in Fig. 10 and Fig. 11. Part of the actuator assembly shown. Part of the in Fig. The actuator assembly 48 shown in Figures 4 to 6 forms, for example, the motor 41a and the monolithic body 42a.

[0118] The guide 51a, 51b stabilizes the motor 41 against transverse forces, i.e., forces acting perpendicular to the direction of the linear axis of the motor 41. The linear axis is the axis along which the motor 41 extends or contracts approximately in the direction of the longitudinal axis of the monolithic body 42 when the motor 41 is operated.

[0119] The in the Fig. 12 and Fig. The embodiment of an actuator device 58 shown in Figure 13 differs from the one shown in Figure 13. Fig. 10 and Fig.As illustrated in Figure 11, the monolithic body 42 has only one elastic longitudinal section 53, which acts as a hinge. This elastic longitudinal section 53 is located in the section between the guide 51 and the first coupling element 55. In this embodiment, the support 52 can be designed to be very rigid, since there is no hinged section of the monolithic body 42 between the guide 51 and the motor 41. For example, the support 52 can therefore be designed as a rotationally symmetrical sleeve that extends around the motor 41 and is attached to the guide 51, which is designed, for example, as a hollow cylinder. Reference symbol list 1 articulated arm robot 2 Basic 3 articulated arm 4 joint 5 first coupling element 6 second coupling element 7 Sensor (for measuring an object) 8 Actuator setup 9 Measuring sensor (for generating information about vibrations of the arrangement and / or the sensor) 10 workpieces 19 Control unit 21 Horizontal arm measuring device 22 base 23 Arm 27 Sensor 28 stylus 31 Portal measuring device 32 base 33 Portal 34 quills 36 Sensor base 37 Sensor 38 Actuator device 41 Engine 42 joint 45 first coupling element 46 second coupling element 47 Control unit 48 Actuator device 49 Sensor (for measuring an object) 50 support 51 Leadership 53 elastic longitudinal section 55 first coupling element 56 second coupling element 58 Actuator device 61 connection 62 joint 65 first coupling element 66 second coupling element 67 third coupling element 68 Actuator device 69 gimbal joint 70 gimbal joint 71 Actuator device 72 Vibration measuring device 73 Preprocessing unit 75 Counter-movement calculation device 77 Control signal generation device 79 Actuator

Claims

[1] Arrangement for measuring an object (10), in particular for determining the coordinates of the object (10), wherein the arrangement comprises the following: - a motion device (3, 4; 23, 4; 33, 34) configured to move a sensor (7; 27; 37) held on the arrangement during operation of the arrangement and configured to detect the object being measured (10), relative to the object being measured (10), - an actuator device (8; 38; 48; 58; 68; 71) via which the sensor (7; 27; 37) is coupled to the motion device (3, 4; 23, 4; 33, 34) during operation of the arrangement and which is designed to at least partially compensate for vibrational movements of the sensor (7; 27; 37), - a vibration measuring device (9) designed to generate information about vibrations of the arrangement and / or the sensor (7; 27; 37) by measuring at least one measured quantity, - a control device (19) which is connected to the vibration measuring device (9) and the actuator device (8; 38; 48; 58; 68; 71) and which is configured to control the actuator device (8; 38; 48; 58; 68; 71) in such a way that the vibration movements of the sensor (7; 27; 37) are at least partially compensated, wherein all moving parts of the arrangement, which serve to move the entire sensor (7; 27; 37) relative to the object being measured, are coupled to the sensor (7; 27; 37) via the actuator device (8; 38; 48; 58; 68; 71), characterized by , that the actuator assembly (8; 38; 48; 58; 68; 71) has a plurality of motors (41) and wherein each of the motors (41) can be controlled independently of any other motor (41) or motors (41) of the actuator assembly (8; 38; 48; 58; 68; 71) by the control unit (19), a plurality of the motors (41) are configured and arranged to each generate a movement with respect to a single linear degree of freedom of the movement and thus along a linear axis of motion of the motor (41), and the linear axes of motion of at least two motors (41) of the actuator assembly (8; 38; 48; 58; 68; 71) are parallel to each other, wherein each of the motors (41) with parallel axes of motion is coupled to the motion assembly (3, 4; 23, 4; 33, 34) via a first coupling element (5; 45; 55; 65) and is coupled or can be coupled to the sensor (7; 27; 37) via a second coupling element (6; 36; 46; 56; 66), and wherein the first coupling element (5; 45; 55; 65) or the second coupling element (6; 36; 46; 56; 66) each is rotatably coupled to the motors (41) with parallel axes of movement via a joint (4; 42; 62). [2] Arrangement according to claim 1, wherein at least six of the motors (41) are configured and arranged to each generate a movement with respect to a single linear degree of freedom of the movement and wherein the six motors (41) form a hexapod. [3] Arrangement according to claim 1 or 2, wherein the plurality of motors (41) can at least partially compensate for vibrational movements of the sensor (7; 27; 37) with respect to at least one linear degree of freedom of movement and at least one rotational degree of freedom of movement. [4] Arrangement according to one of claims 1 to 3, wherein the actuator device (8; 38; 48; 58; 68; 71) is coupled to the motion device (3, 4; 23, 4; 33, 34) via a first coupling element (5; 45; 55; 65) and is coupled or can be coupled to the sensor (7; 27; 37) via a second coupling element (6; 36; 46; 56; 66), wherein the actuator device (8; 38; 48; 58; 68; 71) has at least one motor (41) by which a linear relative motion of the first and the second coupling element (6; 36; 46; 56; 66) can be generated, wherein the first coupling element (5; 45; 55; 65) is coupled to the second coupling element (6; 36; 46; 56; 66) via a combination of the motor (41) with an articulated connection; 66) is connected, whereby - the motor (41) is connected on one side directly or indirectly to the first coupling element (5; 45; 55; 65) and on an opposite side via the articulated connection to the second coupling element (6; 36; 46; 56; 66), wherein a guide designed to guide the linear relative movement at the articulated connection is connected to the first coupling element (5; 45; 55; 65), or - the motor (41) is connected on one side directly or indirectly to the second coupling element (6; 36; 46; 56; 66) and on an opposite side via the articulated connection to the first coupling element (5; 45; 55; 65), wherein a guide designed to guide the linear relative movement at the articulated connection is connected to the second coupling element (6; 36; 46; 56; 66). [5] Arrangement according to claim 4, wherein the articulated connection comprises a monolithic body which is elastically bent when a bending force is applied and thereby performs a movement of a joint. [6] Arrangement according to claim 5, wherein the monolithic body has at least one longitudinal section in which the body has less resistance to elastic deformation than in at least one other section. [7] Method for measuring an object (10), in particular for determining the coordinates of the object (10), wherein the method comprises the following steps: - a sensor (7; 27; 37) is moved relative to a measurement object by means of a movement device (3, 4; 23, 4; 33, 34) in order to bring the sensor (7; 27; 37) into a detection position for detecting the measurement object (10), - Information about vibrations of the motion device (3, 4; 23, 4; 33, 34), the sensor (7; 27; 37) and / or at least one device connected to the motion device (3, 4; 23, 4; 33, 34) and / or the sensor (7; 27; 37) is generated by measuring at least one measured quantity, - an actuator device (8; 38; 48; 58; 68; 71), via which the sensor (7; 27; 37) is coupled to the motion device (3, 4; 23, 4; 33, 34), is controlled by a control device (19) taking into account the information about the vibrations in such a way that vibrational movements of the sensor (7; 27; 37) are at least partially compensated, wherein all moving parts of the arrangement, which serve to move the entire sensor (7; 27; 37) relative to the object being measured, are coupled to the sensor (7; 27; 37) via the actuator device (8; 38; 48; 58; 68; 71), characterized by , that the actuator assembly (8; 38; 48; 58; 68; 71) has a plurality of motors (41) and wherein each of the motors (41) is controlled independently of any other motor (41) or motors (41) of the actuator assembly (8; 38; 48; 58; 68; 71) by the control unit (19), a plurality of the motors (41) are controlled such that each generates a movement with respect to a single linear degree of freedom of the movement and thus along a linear axis of motion of the motor, and the linear axes of motion of at least two motors (41) of the Actuator device (8; 38; 48; 58; 68; 71) are parallel to each other, wherein each of the motors (41) with parallel axes of motion is coupled to the motion device (3, 4; 23, 4; 33, 34) via a first coupling element (5; 45; 55; 65) and is coupled to the sensor (7; 27; 37) via a second coupling element (6; 36; 46; 56; 66), and wherein the first coupling element (5; 45; 55; 65) or the second coupling element (6; 36; 46; 56; 66) is rotatably coupled to the motors (41) with parallel axes of motion via a joint (4; 42; 62). [8] Method according to claim 7, wherein at least six of the motors (41) are controlled such that each generates a movement with respect to a single linear degree of freedom of the movement, wherein the six motors (41) form a hexapod. [9] Method according to claim 7 or 8, wherein the plurality of motors (41) at least partially compensate vibrational movements of the sensor (7; 27; 37) with respect to at least one linear degree of freedom of movement and at least one rotational degree of freedom of movement.

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