Sensor system for an actuator, actuator and method for moving an actuator part

Abstract

Sensor system (1) for an actuator (50), in particular a lifting column, with a force sensor (2) which is designed to detect a total force (F l ), which acts on an actuator part (3) which is mounted movably relative to an actuator base (12, 13), and an acceleration sensor (4) which is designed to detect an acceleration (a) of the actuator part (3), characterized by a processing device (5) which is designed to control a motor drive (6) of the actuator (50) for moving the actuator part (3) on the basis of the detected total force (F l ) and the detected acceleration (a) in such a way that a movement of the actuator part (3) guided by a user is supported.

Description

[0001] The present invention relates to a sensor system for an actuator, in particular a lifting column, an actuator with such a sensor system, a mobile X-ray system with such an actuator and a method for moving an actuator part of an actuator which is movably mounted relative to an actuator base.

[0002] Moving heavy loads typically requires considerable effort from the user. To facilitate such movements, actuators that support the movement with counterweights or spring systems are known. While such solutions reduce the effective weight of the load felt by the user, they do not reduce the inertia associated with the load's high mass. Therefore, performing rapid movements or accelerating the load still requires considerable effort.

[0003] This disadvantage can be eliminated with motor-driven actuators. A user can conveniently move the load by controlling the motor, for example, by pressing buttons or a joystick. However, the disadvantage is that the precision of a motor-controlled actuator movement is limited by the speed at which this movement is to be performed.

[0004] DE 38 36 473 A1 discloses a drawer guide with an automatic closing and opening mechanism, wherein at least one pair of magnet arrangements comprising several mutually associated, oppositely and similarly polarized magnets is arranged with one part on a guide rail and the other part on the drawer guide. A load sensor can detect a drawer load and the mass acceleration of the drawer, and depending on the mass acceleration, a current flow through the magnets designed as electromagnets on the guide rail can then be automatically adjusted by appropriate control. DE 10 2011 084 295 A1 discloses a movable C-arm X-ray device with a C-arm comprising an X-ray source and an X-ray detector. At least one measuring device is arranged on the C-arm, which is operatively connected to the C-arm in such a way that an acceleration of the C-arm can be measured.

[0005] It is an object of the present invention to further improve the actuator support in the movement of a load, in particular to enable high precision in the positioning of the load even at high movement speeds.

[0006] This object is achieved by a sensor system for an actuator, in particular a lifting column, an actuator with such a sensor system, a mobile X-ray system with such an actuator and a method for moving an actuator part of an actuator which is movably mounted relative to an actuator base, according to the independent claims.

[0007] A sensor system for an actuator, in particular a lifting column, according to a first aspect of the invention comprises a force sensor and an acceleration sensor. The force sensor is configured to detect a total force acting on an actuator part movably mounted relative to an actuator base. The acceleration sensor is configured to detect an acceleration of the actuator part. According to the invention, the sensor system further comprises a processing device configured to control a motor drive of the actuator for moving the actuator part based on the detected total force and the detected acceleration in such a way that a user-guided movement of the actuator part is supported.

[0008] An actuator part within the meaning of the invention is, in particular, an actuator component that is movably mounted or movable relative to the actuator base, i.e., another actuator component, in particular displaceable relative to the actuator base. An example of such an actuator part is a plunger or piston that is, for example, motor-driven and translationally movable relative to an actuator base designed as a housing, in particular a cylinder. Another example is, for example, a slide-like segment of a lifting column that is displaceable, for example, by actuating a cable pull, against a column-like segment of the lifting column designed as an actuator base.

[0009] The actuator part is preferably configured to carry a load, e.g., an X-ray head of an X-ray system.

[0010] A total force within the meaning of the invention is, in particular, the sum of all forces acting on the actuator part, particularly during a movement of the actuator part relative to the actuator base. In a user-guided movement of the actuator part, the total force can, for example, consist of a force exerted on the actuator part by the user for guidance, the (inertial) force corresponding to the resulting acceleration, as well as the weight of the actuator part and / or an associated load. The total force can vary over time, particularly during a movement of the actuator part.

[0011] One aspect of the invention is based on the approach of relating the force caused by an acceleration on a part of an actuator that is movable relative to a base to a measured total force acting on the actuator part. Based on the measured acceleration and the measured total force, a drive, e.g., a motor, of the actuator can then be controlled to move the actuator part.

[0012] The acceleration or the corresponding (inertial) force and the total force preferably result in a force actively exerted on the actuator part, e.g. by a user during a guided movement of the movable part, or at least a measure of this force. The drive can therefore be controlled on the basis of the acceleration and the total force in such a way that the user-guided movement of the actuator part is supported. This allows the user to position even heavy loads connected to the actuator part precisely and quickly. In particular, the user is enabled to move such heavy loads intuitively. In particular, it is not necessary for the user to operate a special control device, e.g. in the form of a handle or grip, to cause a movement of the actuator part or to support a movement of the actuator part that the user has guided.The invention thus enables control device-free support in the movement of loads.

[0013] To detect the acceleration of the actuator part, an acceleration sensor, e.g., in the form of a micromechanical system (MEMS) on an integrated circuit (IC), is preferably provided, and a force sensor, e.g., in the form of a load cell, is provided to detect the total force acting on the actuator part. With the aid of a processing device, which can be implemented, for example, by a printed circuit board (PCB) equipped with appropriate data acquisition and processing electronic components or an application-specific integrated circuit (ASIC), a measure of the force exerted on the actuator part can be determined, and corresponding control commands for controlling the drive can be generated.

[0014] For example, the processing device can be configured to precisely determine the force exerted on the X-ray head by a user for the guided movement of an X-ray head, in particular an X-ray collimator that is carried by a lifting column and is movably mounted relative to a mobile substructure, e.g. a trolley, and to use this force to control a motor drive of the lifting column. The user can thus accelerate the X-ray head to high speeds with their hands without exerting great force and still position it precisely. No special handles or contact points need to be provided. Instead, the user can exert force on the X-ray head at any point on the X-ray head to move it. This force can be registered by the force sensor and taken into account when controlling the drive.

[0015] Preferred embodiments of the invention and further developments thereof are described below, which, unless expressly excluded, can be combined with one another as desired and with the aspects of the invention described below.

[0016] In a preferred embodiment, the processing device is configured to determine, based on the detected total force and the detected acceleration, a measure of a force exerted on the actuator part, in particular by a user to move the actuator part, preferably by a hand movement of the user, and to use this measure for controlling the drive. The processing device can, in particular, be configured to track a hand movement of the user based on the determined measure with the aid of the drive, i.e., to cause the drive to track the actuator part to the hand movement. This allows for reliable relief of the user when moving the actuator part or an associated load.

[0017] In a further preferred embodiment, the processing device is configured to control the drive based on a stored calibration value. For this purpose, the sensor system, in particular the processing device, can have a memory in which the calibration value is or can be stored. Using a stored calibration value as a basis allows the drive to be controlled depending on a force exerted by a user on the actuator part without knowledge of the mass of the actuator part or the associated load.

[0018] In a further preferred embodiment, the stored calibration value corresponds to a total force acting on the actuator part when the actuator part is at rest, i.e., when the actuator part is at a standstill. The calibration value can, in particular, correspond to the weight of the actuator part and / or an associated load. This allows the influence of the weight of the actuator part on the total force detected during movement of the actuator part to be determined and taken into account when controlling the drive.

[0019] In a further preferred embodiment, the force sensor is configured to detect the total force acting on the actuator part in a calibration mode when the actuator part is at rest. Preferably, the sensor system is operable in a calibration mode or can be switched to calibration mode. The processing device is preferably configured to store the total force detected when the actuator part is at rest as a calibration value. This enables precise detection of the weight of the actuator part or the associated load.

[0020] Preferably, the sensor system or actuator is configured to signal the calibration mode to the user. For example, the processing device can be configured to output or initiate the output of a corresponding optical or acoustic signal in calibration mode. This can ensure that the user does not exert any force on the actuator part while detecting the calibration value.

[0021] Alternatively or additionally, it is also conceivable that the sensor system or the actuator is configured to block the movement of the actuator part relative to the actuator base in calibration mode. For example, the processing device can be configured to block the actuator part in calibration mode using a locking mechanism provided to simplify the positioning of the actuator part relative to the actuator base. This can prevent accidental movement of the actuator part by the user during calibration.

[0022] In a further preferred embodiment, the processing device is configured to normalize the total force detected by the force sensor with a total force acting on the actuator part when the actuator part is at rest, i.e., when the actuator part is at a standstill. The processing device is preferably configured to normalize the detected total force using the stored calibration value. This allows the total force acting on the stationary actuator part to be provided quickly and reliably.

[0023] In addition, the processing device is preferably configured to determine the force exerted on the actuator part, or at least a measure thereof, based on the total force standardized in this way. Accordingly, the exerted force or the measure thereof can be determined even without knowledge of the mass of the actuator part or the associated load. This makes it possible, for example, to easily retrofit actuators, especially lifting columns, with the sensor system.

[0024] In a further preferred embodiment, the processing device is configured to control the drive based on a quotient of a force exerted on the actuator part, in particular by a user, preferably for moving the actuator part, and a total force acting when the actuator part is at rest. The processing device can in particular be configured to determine this quotient based on the standardized total force that acts upon movement of the actuator part based on the total force detected by the force sensor. The quotient can form a measure of the force exerted on the actuator part, for example by a user, in particular by their hand movement, for moving the actuator part. The drive can thus quickly and precisely track the user's hand movement.

[0025] In a further preferred embodiment, the force sensor is designed as a load cell. Such a load cell can be particularly compact and can therefore be easily integrated into the actuator, especially at different locations.

[0026] In a further preferred embodiment, the force sensor is configured to measure the total force by detecting the tension of a cable supporting the actuator part. For this purpose, the force sensor can be connected to the cable on one side and to the actuator part on an opposite side. A change in the cable tension from a resting state, for example, from calibration mode, allows for the reliable determination of a measure of the force exerted by a user on the actuator part.

[0027] In other words, the processing device can be configured to monitor a deviation of the cable tension from a calibration value and, in particular, to use the deviation of the cable tension from the calibration value, together with the detected acceleration, as the basis for controlling the drive. The detection of the cable tension can be implemented in a particularly simple and compact manner.

[0028] In a further preferred embodiment, the force sensor is configured to measure the total force by detecting a weight acting on a spindle supporting the actuator part. This makes it possible to arrange the force sensor in a particularly protected manner within the actuator, for example, within a column element of a lifting column.

[0029] An actuator, in particular a lifting column, according to a second aspect of the invention comprises an actuator base, an actuator part movably mounted relative to the actuator base, a motor drive for moving the actuator part, and a sensor system according to the first aspect of the invention. The actuator part is preferably designed as a carriage that is movable, for example, along a side surface of the actuator base. Furthermore, the actuator part is preferably configured to support a load, such as an X-ray head. For this purpose, the actuator part can have a fastening means, such as threaded holes for screwing the load, a locking mechanism for suspending the load, and / or the like.

[0030] In a preferred embodiment, the acceleration sensor and the processing device are arranged on and / or in the actuator part. The actuator, in particular the actuator base, can thus be designed particularly compactly. Alternatively or additionally, the force sensor is also arranged on and / or in the actuator part. This enables direct and therefore less error-prone detection of the total force acting on the actuator part.

[0031] In a further preferred embodiment, the force sensor is arranged in a recess of the actuator part. The force sensor can, in particular, be accommodated in a pocket formed by the actuator part and a side surface of the actuator base. The force sensor can thus be particularly reliably protected from external influences that could impair the detection of the total force.

[0032] A mobile X-ray system according to a third aspect of the invention comprises a mobile substructure, an actuator according to the second aspect of the invention mounted on the mobile substructure, and an X-ray head mounted on the actuator part movably mounted relative to the actuator base.

[0033] In a method for moving an actuator part of an actuator, in particular a lifting column, which is movably mounted relative to an actuator base, according to a fourth aspect of the invention, (i) a total force acting on the actuator part and (ii) an acceleration of the actuator part are detected. According to the invention, (iii) a motor drive of the actuator for moving the actuator part is controlled on the basis of the detected total force and the detected acceleration, in particular on the basis of a measure of a force exerted on the actuator part, such that a movement of the actuator part guided by a user is supported. The measure of the force exerted on the actuator part can be determined on the basis of the detected total force and the detected acceleration.

[0034] The description of preferred embodiments of the invention given so far contains numerous features, some of which are summarized in the individual dependent claims. However, these features can also be considered individually and combined into further meaningful combinations. In particular, these features can each be combined individually and in any suitable combination with the sensor system according to the first aspect of the invention, the actuator according to the second aspect of the invention, the X-ray system according to the third aspect of the invention, and the method according to the fourth aspect of the invention.

[0035] The properties, features, and advantages of the invention described above, as well as the manner in which they are achieved, are explained in more detail in conjunction with the figures in the following description of exemplary embodiments of the invention. Throughout the figures, the same reference numerals are used for the same or corresponding elements of the invention. The exemplary embodiments serve to explain the invention and do not limit the invention to the combinations of features specified therein, including with regard to functional features. Furthermore, features of the exemplary embodiments suitable for this purpose can also be explicitly considered in isolation and combined with any of the claims.

[0036] They show, at least partly schematically: Fig. 1A an example of a sensor system for an actuator; Fig. 1B a free body diagram with the forces acting on a load; Fig. 2 shows a first example of an actuator with a sensor system in a sectional view; Fig. 3 a second example of an actuator with a sensor system in a sectional view; Fig. 4 an example of a mobile X-ray system; and Fig. 5 an example of a method for moving an actuator part.

[0037] Fig. Figure 1A shows an example of a sensor system 1 for an actuator, in particular a lifting column. The sensor system 1 comprises a force sensor 2 configured to measure a total force F lto measure the force acting on an actuator part 3 of the actuator that is movably mounted relative to an actuator base of the actuator, e.g., a housing (not shown). The sensor system 1 also has an acceleration sensor 4 that is configured to detect an acceleration a acting on the actuator part 3. A processing device 5 of the sensor system 1 is configured to, based on the detected total force F l and the detected acceleration a to control a drive 6 of the actuator to move the actuator part 3.

[0038] In the example shown, the drive 6 is configured to rotate a nut 9 via a gear 11. The nut 9 preferably has an internal thread that engages with an external thread 10a of a spindle 10. With the aid of the nut 9 and the spindle 10, a rotational movement of a shaft of the drive 6 can therefore be converted into a translational movement of the actuator part 3.

[0039] The force sensor 2, the acceleration sensor 4 and the drive 6 are, as in Fig. 1, is signal- or data-connected to the processing device 5. At least some of the connections, in particular between the processing device 5 and the drive 6, can also be wireless, for example, in order not to impair the movement of the actuator part 3 relative to the drive 6.

[0040] To move a load 25, which is connected to the actuator part 3, for example via a fastening means 7, for example screwed to threaded holes 7a of the fastening means 7, the user can apply a force F h on the load 25 and thus also on the actuator part 3. This force F, exerted for example by the user's hand h can be measured by force sensor 2 as part of the total force F l be recorded.

[0041] This shows Fig. 1B shows a free-body diagram showing the forces acting on a load with mass M. The total force F l also a non-constant (inertial) force F l = M a, which corresponds to the acceleration a caused by the force exerted on the load 25 or the actuator part 3. As in Fig. 1A and Fig. As shown in Figure 1B, this force acts on the load 25 as force F h For the total force F lresults accordingly: Fl=M⋅a−Fh.

[0042] Therefore, only by measuring the acceleration a using the acceleration sensor 4 is it possible to use the processing device 5 to calculate the force F exerted by the user on the load 25 or the actuator part 3 h or at least to determine a measure thereof. It is preferably irrelevant whether the load 25 is already in motion, e.g., because the actuator is moved as a whole—for example, if the actuator is mounted on a movable platform such as a cart or vehicle.

[0043] The measure of force F h can be used as the basis for controlling the drive 6. This enables the drive 6 to support the movement of the load 25 caused by a user.

[0044] In order to enable support by the drive 6 to be independent of the mass M of the load 25 to be moved, the processing device 5 preferably takes into account a calibration value when controlling the drive 6, which calibration value is stored, for example, in a memory 8 of the sensor system 1, in particular of the processing device 5.

[0045] The calibration value preferably corresponds to a total force F detected by the force sensor 2 in a calibration mode of the sensor system 1 l0 , in which the actuator part 3 is at rest, ie stationary. Since no force F h is exerted on the load 25 or the actuator part 3 and there is no acceleration of the actuator part 3, the total force F detected by the force sensor 2 l0 = M·a0 of the weight force, where a0 is the acceleration due to gravity.

[0046] The processing device 5 is preferably configured to convert the force F measured by the force sensor 2 l with the total force F recorded when actuator part 3 is at rest l0 to be standardized so that the measure of the force F exerted during movement of the actuator part 3 is h a quotient results in: FhFl0=M⋅aFl0−FlFl0 or FhFl0=aa0−FlFl0.

[0047] The quotient FhFl0 can be measured by measuring the acceleration a and the total force F acting on the actuator part 3 l using the calibration value F stored in memory 8 l0 and the acceleration due to gravity a0 can be calculated quickly, ie essentially in real time, and can therefore be used as a basis for controlling the drive 6 in order to achieve tracking of the actuator part 3 or the load 25 connected thereto.

[0048] Fig. 2 shows an example of an actuator 50 with a sensor system 1 in a sectional view. The sensor system 1 has a force sensor 2, an acceleration sensor 4 and a processing device 5. The actuator 50 is designed as a lifting column, which has a first base part 12, a second base part 13 and an actuator part 3. The second base part 13 is column-shaped and is movably mounted, in particular telescopically displaceable, relative to the first, also column-shaped base part 12. The actuator part 3 is movably mounted, in particular telescopically displaceable, relative to the second column-like base part 13, in particular displaceable along a side surface 14 of the second base part 13. For this purpose, the actuator part 3 can be designed as a carriage, which is arranged between two guide rails 23, of which Fig. 2, only one is visible. The guide rails 23 run in a longitudinal direction of the actuator 50, i.e., parallel to a longitudinal axis 22.

[0049] A drive 6 in the form of a motor is provided to move the components of the actuator 50 relative to one another. The drive 6 is arranged on a first end plate 18 of the first base part 12, which defines an upper end of the first base part 12.

[0050] In the example shown, the components of the sensor system 1 are integrated into the actuator part 3, i.e., arranged on or in the actuator part 3. The force sensor 2 is configured to detect a total force acting on the actuator part 3, while the acceleration sensor 4 is configured to detect an acceleration of the actuator part 3. Based on the detected total force and the detected acceleration, the processing device 5 can control the drive 6 such that a movement of the actuator part 3 relative to the base parts 12, 13 performed by a user is supported.

[0051] For this purpose, the actuator part 3 can be connected to the first base part 12 via a cable 15. The actuator part 3 is preferably carried by a cable 16 of the cable 15, wherein it can be fastened to an outer end of the cable 16. In the example shown, the actuator part 3 has a recess 20 for fastening the cable 16, in which the cable 16 can run in sections. The force sensor 2 is arranged, for example, at an inner end of the recess 20, in particular connected to the cable 16. The force sensor 2 can thereby detect the total force acting on the actuator part 3 by detecting a cable tension of the cable 16.

[0052] The cable 16 is guided over a pulley 17 mounted on the second base part 13 and is attached to the first base part 12, in particular to the first end plate 18, with one end facing the base part. Upon movement of the second base part 13 relative to the first base part 12, the cable pull 15 also causes the actuator part 3 to move relative to the second base part 13.

[0053] To move the second base part 13 relative to the first base part 12, a drive 6 is arranged on the first end plate 18 and can be fastened to the first base part 12, in particular in the region of the first end plate 18, for example coupled to a nut 9 via a gear. An internal thread of the nut 9 engages with an external thread of a spindle 10, so that a rotation of the nut 9 driven by the drive 6 causes a translation of the spindle 10. The spindle 10 is fastened to an upper end of the second base part 13 facing away from the first base part 12, in particular the first end plate 18, in particular to a second end plate 24 of the second base part 13, so that when the spindle 10 is translated, the second base part 13 is also moved relative to the first base part 12. At the same time, a movement of the actuator part 3 relative to the second base part 13 is also caused via the cable pull 15.

[0054] In order to support the actuator 50 in an extended state, a weight compensation means 19 is preferably provided, which can be designed, for example, as a gas spring. A cylinder 19a of the gas spring is connected to the second base part 13, while a piston 19b of the gas spring is connected to the first base part 12. The weight force of a load (not shown) connected to the actuator part 3, which also acts on the second base part 13 via the deflection pulley 17, can thereby be absorbed. This enables weight compensation of the second base part 13 and the actuator part 3 or the load coupled thereto, so that, for example, a smaller drive 6 can be used.

[0055] Unlike in Fig. 2, the drive 6 can also be arranged on a bottom 21 of the first base part 12, which defines a lower end of the first base part 12.

[0056] The nut 9 can be sleeve-like and extend in the longitudinal direction of the actuator 50, i.e., parallel to the longitudinal axis 22, essentially through the entire first base part 12, in order to be able to interact with the spindle 10 even when the second base part 13 is fully extended. Of course, it is also possible to interchange the arrangement of the nut 9 and spindle 10, so that the spindle 10 is rotated by the drive 6 and causes a translation of the nut 9. The described modes of action remain unchanged.

[0057] Also different from the Fig. In the example shown in Figure 2, instead of fastening the inner end of the cable 16 to the first end plate 18, a further drive can also be provided, with which the actuator part 3 can be moved, if necessary, independently of the movement of the second base part 13 relative to the first base part 12.

[0058] The further, in Fig. The drive (not shown in Figure 2) can be configured, for example, to drive a cable drum on which the cable 16 can be wound or unwound. By appropriately controlling the additional drive, a shortening or lengthening of the cable 16 and thus a displacement of the actuator part 3 along the side surface 14 can be effected.

[0059] Fig. Figure 3 shows a second example of an actuator 50 with a sensor system 1 in a sectional view, wherein the load 25 carried by an actuator part 3 is also shown schematically. Both the actuator 50 and the sensor system 1 correspond to the Fig. 2. In particular, the sensor system 1 also has a force sensor 2 for detecting a total force acting on an actuator part 3 and an acceleration sensor 4 for detecting an acceleration of the actuator part 3. A processing device 5 is configured to control a drive 6, with which the slide-like actuator part 3, guided by guide rails 23, can be moved along a side surface 14 of a second base part 13, based on the detected total force and the detected acceleration. The second base part 13 is also mounted so as to be movable, in particular telescopically displaceable, relative to a first base part 12.

[0060] As in Fig. In the example shown in Figure 2, the force sensor 2 is arranged on or in the actuator part 3. In principle, however, it is also possible to arrange the force sensor 2 at a different location, as long as the force sensor 2 can detect the entire total force acting on the actuator part 3 there. For example, the force sensor 2 can be arranged at an upper end of the second base part 13 opposite the first base part, in particular at a second end plate 24 of the second base part 13, which defines an upper end of the second base part 13, if no weight compensation means 19 is provided, i.e., no part of the total force is compensated.The force sensor 2 could preferably be connected on one side to the second base part 13 and on an opposite side to a spindle 10, which converts a rotation of a nut 9 driven by the drive 6 into a translation and thereby causes the movement of the second base part 13 relative to the first base part 12.

[0061] In this, in Fig. In the embodiment not shown in Figure 3 without weight compensation means 19, the force sensor 2 is thus protected inside the second base part 13 and can measure the total force acting on the actuator part 3 by detecting the weight of the load 25 resting on the spindle 10. The load 25, for example, an X-ray head, is attached to the actuator part 3. The weight of the load 25 is transferred to the second base part 13 via the deflection pulley 17 of a cable pull 15, where it can then be detected.

[0062] Fig. 4 shows an example of a mobile X-ray system 60 with an actuator 50 configured as a lifting column 50, which has a base part 12, an actuator part 3 movably mounted relative to the base part 12, a drive 6 for moving the actuator part 3, and a sensor system 1 with a force sensor 2, an acceleration sensor 4, and a processing device 5. The X-ray system 60 has a mobile substructure 61, which in the present example is configured as a three- or four-wheeled cart. The X-ray system 60 also has an X-ray head 62 for generating X-ray radiation. The X-ray head 62 is mounted on the actuator part 3, preferably using a linear actuator 63, and can thus be positioned, for example, relative to a patient.

[0063] The force sensor 2 is configured to detect a total force acting on the X-ray head 62 connected to the actuator part 3, for example when the X-ray head 62 is guided by hand for positioning by a user. The acceleration sensor 4 is configured to detect the acceleration of the X-ray head 62, for example during such a movement. The processing device 5 is configured to control the drive 6 for moving the actuator part 3 and thus also the X-ray head 62 relative to the base part 12, specifically based on the detected total force and the detected acceleration. A user-guided movement of the X-ray head 62 can thus be assisted by the drive 6. This significantly reduces the force required by the user for the movement and allows intuitive and rapid positioning of the X-ray head 62 despite its heavy weight.

[0064] Fig.5 shows an example of a method 100 for moving an actuator part of an actuator relative to a base part of the actuator.

[0065] In a method step S1, the sensor system is operated in a calibration mode. In this case, a total force acting on the actuator part is detected while the actuator part is at rest, i.e., while the actuator part is not moving or is at a standstill. For this purpose, a force sensor is preferably provided, which can, for example, be arranged such that it supports or carries the actuator part, optionally also indirectly. In calibration mode, with the actuator part stationary, the force sensor essentially detects the weight of the actuator part or a load attached to it.

[0066] The total force measured by the force sensor with the actuator at rest is preferably stored in a memory as a calibration value during method step S1. Calibration mode can then be terminated.

[0067] In a further method step S2, the total force acting on the actuator part is recorded when the sensor system is no longer in calibration mode, i.e., for example, when the actuator part is moved by a user. The total force can then be composed of several forces, for example, the weight of the actuator, the (inertial) force caused by acceleration, and a force exerted by the user to move the actuator part. Compared to the calibration mode, the total force recorded by the force sensor changes accordingly when the actuator part is moved.

[0068] In a further method step S3, an acceleration of the actuator part is detected, which is caused, for example, by the user moving the actuator part. An acceleration sensor can be provided for this purpose.

[0069] In a further method step S4, a measure of the force exerted on the actuator part, for example, by the user, is determined based on the detected total force and the detected acceleration. The detected total force can be standardized with the stored calibration value. Preferably, the detected acceleration is also standardized with a standardization value, in particular the acceleration due to gravity. The standardization value can also be stored in the memory, i.e., together with the calibration value.

[0070] Preferably, a quotient of the force exerted on the actuator part and the calibration value is determined as a measure of the force exerted on the actuator part.

[0071] In a further method step S5, a drive configured to move the actuator part relative to the base part is controlled based on the determined measure of the force exerted on the actuator part. This allows the actuator part to reliably and precisely track a movement performed by the user. List of reference symbols 1 sensor system 2 force sensor 3 Actuator part 4 Accelerometer 5 Processing device 6 Drive 7 Fasteners 7a threaded hole 8 storage 9 Mother 10 spindle 10a external thread 11 gearboxes 12 first base part 13 second base part 14 side surface 15 cable pull 16 rope 17 pulley 18 first end plate 19 Weight compensation agents 19a cylinder 19b piston 20 recess 21 Floor 22 Longitudinal axis 23 Guide rail 24 second end plate 25 load 50 actuator 60 X-ray system 61 Substructure 62 X-ray head 63 Linear actuator 100 procedures S1-S5 process steps F l Total force a acceleration F h force exerted M mass

Claims

[1] Sensor system (1) for an actuator (50), in particular a lifting column, with a force sensor (2) which is designed to detect a total force (F l ) which acts on an actuator part (3) which is movably mounted relative to an actuator base (12, 13), and an acceleration sensor (4) which is arranged to detect an acceleration (a) of the actuator part (3), characterized by a processing device (5) which is designed to control a motor drive (6) of the actuator (50) to move the actuator part (3) on the basis of the detected total force (F l ) and the detected acceleration (a) in such a way that a movement of the actuator part (3) guided by a user is supported. [2] Sensor system (1) according to claim 1, characterized by that the processing device (5) is designed to, on the basis of the detected total force (F l) and the detected acceleration (a) a measure of a force (F h ) and to use it as a basis for controlling the drive (6). [3] Sensor system (1) according to one of claims 1 or 2, characterized by that the processing device (5) is arranged to control the drive (6) on the basis of a stored calibration value. [4] Sensor system (1) according to claim 3, characterized by that the stored calibration value is correlated with a total force (F l0 ) when the actuator part (3) is at rest. [5] Sensor system (1) according to one of claims 3 or 4, characterized by that the force sensor (2) is designed to measure the total force (F l0 ) with the actuator part (3) at rest in a calibration mode (S1). [6] Sensor system (1) according to one of the preceding claims, characterized by that the processing device (5) is designed to convert the total force (F l ) with a total force (F l0 ) with the actuator part (3) at rest. [7] Sensor system (1) according to one of the preceding claims, characterized by that the processing device (5) is designed to control the drive (6) on the basis of a quotient of a force (F h ) and a total force (F l0 ) to control. [8] Sensor system (1) according to one of the preceding claims, characterized by that the force sensor (2) is designed as a load cell. [9] Sensor system (1) according to one of the preceding claims, characterized bythat the force sensor (2) is designed to measure the total force (F l ) by detecting a rope tension of a rope (16) by which the actuator part (3) is carried. [10] Sensor system (1) according to one of claims 1 to 9, characterized by that the force sensor (2) is designed to measure the total force (F l ) by detecting a weight that rests on a spindle (10) carrying the actuator part (3). [11] Actuator (50), in particular a lifting column, with an actuator base (12, 13), an actuator part (3) movably mounted relative to the actuator base (12, 13), a motor drive (6) for moving the actuator part (3) and a sensor system (1) according to one of the preceding claims. [12] Actuator (50) according to claim 11, characterized by that the acceleration sensor (4) and the processing device (5) are arranged on and / or in the actuator part (3). [13] Actuator (50) according to one of claims 11 or 12, characterized by that the force sensor (2) is arranged in a recess (20) of the actuator part (3). [14] Mobile X-ray system (60) with a mobile substructure (61), an actuator (50) according to one of claims 11 to 13 mounted on the mobile substructure (61) and an X-ray head (62) which is mounted on the actuator part (3) which is movably mounted relative to the actuator base (12, 13). [15] Method (100) for moving an actuator part (3) of an actuator (50), in particular a lifting column, which is movably mounted relative to an actuator base (12, 13), wherein a total force (F l ) (S2) and an acceleration (a) of the actuator part (3) (S3) is detected, characterized by that a motor drive (6) of the actuator (50) for moving the actuator part (3) on the basis of the detected total force (F l) and the detected acceleration (a) is controlled (S5) in such a way that a movement of the actuator part (3) guided by a user is supported.

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