WO2025223669A1

WO2025223669A1 - Method of moving object using electromagnet, control system, and actuator system

Info

Publication number: WO2025223669A1
Application number: PCT/EP2024/061580
Authority: WO
Inventors: Andrzej Tunkiel
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2024-04-26
Filing date: 2024-04-26
Publication date: 2025-10-30
Anticipated expiration: 2026-10-26

Abstract

A method of moving an object (34a-34c), the method comprising providing an actuator (14a) carrying an electromagnet (22a, 22b); providing, in a control system (50), distance data (62) indicative of a distance (70) between the electromagnet (22a, 22b) and the object (34a-34c); controlling, by the control system (50), the actuator (14a) to move the electromagnet (22a, 22b); and controlling, by the control system (50), during movement of the electromagnet (22a, 22b) and based on the distance data (62), an electric current (60a, 60b) to the electromagnet (22a, 22b) such that the electromagnet (22a, 22b) generates a magnetic field (72) exerting a force on the object (34a-34c). A control system (50) and an actuator system (12) are also provided.

Description

METHOD OF MOVING OBJECT USING ELECTROMAGNET, CONTROL SYSTEM, AND ACTUATOR SYSTEM

Technical Field

The present disclosure generally relates to moving objects using an electromagnet. In particular, a method of moving an object using an electromagnet, a control system configured to control an actuator and an electromagnet, and an actuator system comprising such control system, are provided.

Background

When painting a car body, the doors thereof are typically painted together with the rest of the car body, e.g., the bodywork. Some reasons for this include a desire for color matching and efficiency. At some point, the doors have to be opened to be able to paint all surfaces of the car body. In some plants for painting car bodies, an industrial robot is used to open and close the doors to allow access to all the surfaces of the door and around the associated door frames. To this end, the industrial robot may carry a rod that is moved into a slit in the door meant for the windowpane. Such manipulation of the door requires the industrial robot to touch the door, which implies either touching wet paint and spoiling the finish, or obstructing some part of the car body from being painted.

US 4946336 A discloses a manipulator for contact-free opening and closing of the doors of a passenger car body. The manipulator comprises an arm pivotable around a vertical axis and around a horizontal axis. A plurality of magnets are provided on the arm. The magnets act on the door from below and the arm is tilted down around the horizontal axis to remove the magnetic force on the door. Summary

In the manipulator in US 4946336 A, the magnets need to be positioned very close to the door, risking to contact a painted surface, or need to be very strong, adding costs. Moreover, the control of the movements of the door is very limited and the manipulator is for example not capable of handling jerking movements of the door.

One object of the invention is to provide an improved method of moving an object using an electromagnet.

A further object of the invention is to provide an improved control system for controlling an actuator and an electromagnet.

These objects are achieved by the method according to appended claim 1 and by the control system according to appended claim 8.

The invention is based on the realization that by providing an actuator carrying an electromagnet to magnetically force the object, and by controlling the electromagnet based on a distance between electromagnet and the object during movements of the actuator, the object can be moved accurately as well as with a relatively low magnetic force and/or at a relatively large distance from the electromagnet.

According to a first aspect, there is provided a method of moving an object, the method comprising providing an actuator carrying an electromagnet; providing, in a control system, distance data indicative of a distance between the electromagnet and the object; controlling, by the control system, the actuator to move the electromagnet; and controlling, by the control system, during movement of the electromagnet and based on the distance data, an electric current to the electromagnet such that the electromagnet generates a magnetic field exerting a force on the object.

The electric current to the electromagnet is thus automatically regulated based on the distance data during movement of the electromagnet. With such regulation, the object can for example be magnetically forced by magnetic attraction to move along with the actuator without being forced into contact with the electromagnet. The method may however alternatively or in addition be carried out using a magnetic repulsion.

The electric current to the electromagnet may be immediately adjusted based on the distance data. Hence, a risk of jerking movements of the door is reduced. The electromagnet may include a coil of wire that produces a magnetic field when the electric current flows through it.

By controlling the electric current based on the distance data, the control system employs a feedback control loop. The feedback control loop may for example include a proportional-integral-derivative (PID) controller where the distance data is used as the measured variable and the electric current is used as the control variable.

Throughout the present disclosure, the actuator may be an industrial robot. Other types of actuators, including a workpiece positioner, are however possible.

In case the object is a door, the method enables the electromagnet to act on a side of the door, e.g., such that the electromagnet is offset from the door in a direction transverse to a main extension plane of the door. This for example enables the magnetic force to be efficiently used in an opening direction of the door. In this way, high forces on the door can be generated in view of a given magnetic field. Alternatively, a rating of the electromagnet can be reduced, hence increasing cost-efficiency. Alternatively, the distance can be relatively large, hence providing an increased margin of safety to contacting the door.

Moreover, when the electromagnet acts on a side of the door, a wide range of different relative positions between the electromagnet and the door can be used, such as any positions adjacent to a main face of the door that is generally parallel with a main extension plane of the door. For example, the electromagnet may be positioned adjacent to any of a plurality of positions on the door that are offset in a radial direction with respect to the hinge. This greatly improves flexibility of the method.

The object may for example belong to a vehicle body, such as being a door, a hood, a tailgate or a lid. In these cases, the method may comprise moving the object from a closed position to an open position by the magnetic field and then painting the object in the open position.

The method is however not limited to painting applications or to objects of vehicle bodies. As one alternative example, the method may be used in connection with cleaning of a plant. For example, a sterilized object, such as a lid, can be moved by the magnetic field without being touched and thereby contaminated.

The object maybe made of, or include, a material having a magnetic permeability p of at least 1 x io^_5 H/m (henries per meter), such as iron, electrical steel or ferritic stainless steel.

The method may employ a sensor providing sensor data. The sensor data may be the distance data. In these cases, the actuator may carry the sensor.

Alternatively, the control system may be configured to determine the distance data based on the sensor data, e.g., based on the sensor data and a position of the electromagnet. In these cases, the sensor may be provided outside of the actuator, i.e., the actuator may not carry the sensor.

In any case, the sensor may for example be an ultrasonic sensor, an optical sensor or a lidar (light detection and ranging) sensor. Alternatively, the electromagnet may be used to measure the distance by leveraging the principles of electromagnetic induction and the properties of magnetic fields. In these cases, the sensor may for example be a magnetic field sensor, such as a Hall effect sensor, that can measure the strength and/or gradient of the magnetic field.

The control of the electric current may be performed based on a target distance value. The target distance value may be a constant value. Thus, the electric current to the electromagnet may be controlled based on the distance data to maintain the distance constant. The target distance value does however not necessarily have to be constant and can instead vary over time. In any case, if a PID controller is implemented in the control system, the target distance value may be used as the desired setpoint.

For each position of the object, the actuator may be controlled to move the electromagnet substantially in an offset direction, or in an offset direction, between the electromagnet and the object. The offset direction may be a direction of the distance.

The object may be movable relative to a base structure in only a single degree of freedom. In the example of a vehicle body, the object may be constituted by a door, a hood, a tailgate or a lid, and the base structure may be constituted by a bodywork.

The single degree of freedom may be a rotational degree of freedom.

The actuator may be controlled to move the electromagnet about the single degree of freedom. For example, both the electromagnet and the object may move about a common axis. Alternatively, both the electromagnet and the object may move in parallel with a common axis.

The electromagnet may be a first electromagnet and the electric current may be a first electric current. In these cases, the method may further comprise providing the actuator to carry a second electromagnet; controlling, by the control system, the actuator to move the first and second electromagnets while the object is positioned between the first and second electromagnets; and controlling, by the control system, during movement of the first and second electromagnets and based on the distance data, a second electric current to the second electromagnet such that the second electromagnet generates a magnetic field exerting a force on the object. The second electromagnet may be of the same type as the first electromagnet, for example of identic design. The second electromagnet may be in a fixed relationship with the first electromagnet. The second electromagnet may function as a counterbalance to the first electromagnet. In some examples, each of the first and second electromagnets provides an attractive magnetic field. In these cases, the object can be controlled to behave as if the object was held by a first string from the first electromagnet and by a second string from the second electromagnet. The object can thereby be actively held stably in a desired position. This greatly suppresses jerking movements of the object.

According to a second aspect, there is provided a control system comprising at least one data processing device and at least one memory having at least one computer program stored therein, the at least one computer program comprising program code which, when executed by the at least one data processing device, causes the at least one data processing device to control an actuator carrying an electromagnet to move the electromagnet; provide distance data indicative of a distance between the electromagnet and an object; control, during movement of the electromagnet and based on the distance data, an electric current to the electromagnet such that the electromagnet generates a magnetic field exerting a force on the object.

The at least one computer program may comprise program code which, when executed by the at least one data processing device, causes the at least one data processing device to perform, or command performance of, various operations as described herein, in particular all operations as described in connection with the first aspect.

The control of the electric current may be performed based on a target distance value.

The at least one computer program may comprise program code which, when executed by the at least one data processing device, causes the at least one data processing device to for each position of the object, control the actuator to move the electromagnet substantially in an offset direction, or in an offset direction, between the electromagnet and the object. The at least one computer program may comprise program code which, when executed by the at least one data processing device, causes the at least one data processing device to control the actuator to move the electromagnet in a single degree of freedom.

The single degree of freedom may be a rotational degree of freedom.

The electromagnet may be a first electromagnet and the electric current may be a first electric current. In these cases, the at least one computer program comprises program code which, when executed by the at least one data processing device, causes the at least one data processing device to control the actuator carrying the first electromagnet and a second electromagnet to move the first and second electromagnets while the object is positioned between the first and second electromagnets; and control, during movement of the first and second electromagnets and based on the distance data, a second electric current to the second electromagnet such that the second electromagnet generates a magnetic field exerting a force on the object.

According to a third aspect, there is provided an actuator system comprising the control system according to the second aspect and the actuator. The actuator of the third aspect may be of any type described in connection with the first or second aspects, and vice versa.

The actuator may be an industrial robot.

Brief Description of the Drawings

Further details, advantages and aspects of the present disclosure will become apparent from the following description taken in conjunction with the drawings, wherein:

Fig. 1: schematically represents a top view of a plant including a vehicle body and an actuator system comprising two industrial robots;

Fig. 2: schematically represents a perspective view of an end effector of one of the industrial robots including two electromagnets;

Fig. 3: is a block diagram showing components of the actuator system; Fig. 4: schematically represents a partial top view of the plant when the end effector is positioned with respect to a closed door of the vehicle body;

Fig. 5: schematically represents a partial top view of the plant when the door is caused to perform an opening movement by magnetic force;

Fig. 6: schematically represents a partial top view of the plant when the opening movement is braked;

Fig. 7: schematically represents a partial top view of the plant when the door is stopped in an open position;

Fig. 8: schematically represents a partial top view of the plant during opening of the door by magnetic force using an end effector according to a further example;

Fig. 9: schematically represents a partial top view of the plant during magnetic closing of a door according to a further example;

Fig. 10: schematically represents a top view of a further example of magnetic manipulation of an object; and

Fig. 11: schematically represents a top view of a further example of magnetic manipulation of an object.

Detailed Description

In the following, a method of moving an object using an electromagnet, a control system configured to control an actuator and an electromagnet, and an actuator system comprising such control system, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.

Fig. 1 schematically represents a top view of a plant 10, here exemplified as a plant for painting vehicle bodies. The plant 10 of this example includes an actuator system 12. The actuator system 12 comprises a first actuator in the form of a first industrial robot 14a and a second actuator in the form of a second industrial robot 14b. The first industrial robot 14a of this example operates as a contactless electromagnetic door operator. The second industrial robot 14b of this example is a conventional painting robot.

The first industrial robot 14a of this specific and non-limiting example comprises a base 16 and a manipulator 18 movable relative to the base 16. The manipulator 18 may for example be a serial manipulator programmable in three or more axes, such as in six or seven axes. The manipulator 18 carries an end effector 20a according to one example, here fixed to a distal end of the manipulator 18.

The end effector 20a of this example comprises a first electromagnet 22a and a second electromagnet 22b. The end effector 20a of this example further comprises a sensor 24a, here exemplified as an ultrasonic sensor. Although Fig. 1 shows a space between the sensor 24a and the first electromagnet 22a, the sensor 24a may be positioned immediately adjacent to a front end of the first electromagnet 22a such that any offset therebetween maybe neglected. The first industrial robot 14a thus carries the first and second electromagnets 22a, 22b and the sensor 24a. Electromagnets and ultrasonic sensors are relatively cheap components.

The second industrial robot 14b is here of a same design as the first industrial robot 14a but carries a painting head 26, instead of the end effector 20a, for applying paint 28.

The plant 10 of this example further includes a vehicle body 30 for a passenger car. The vehicle body 30 of this specific and non-limiting example comprises a bodywork 32a, two doors 34a rotatable relative to the bodywork 32a around a respective hinge 36, a hood 38, a tailgate 40 and a lid 42, here a fuel lid. Each of the doors 34a, the hood 38, the tailgate 40 and the lid 42 are examples of objects as described herein made of, or comprising, a ferromagnetic material and here also each comprising only a rotational degree of freedom with respect to the bodywork 32a. The bodywork 32a is one example of a base structure. Each door 34a comprises a window opening 44 into which the end effector 20a can move. In Fig. 1, each door 34a is illustrated in an open position 46.

Fig. 2 schematically represents a perspective view of the end effector 20a. As shown, the end effector 20a of this specific example comprises a U-shaped support structure 48 carrying the first and second electromagnets 22a, 22b and the sensor 24a in a fixed relationship. The first and second electromagnets 22a, 22b are here oppositely arranged and face each other.

Fig. 3 is a block diagram showing some components of the actuator system 12. The actuator system 12 comprises a control system 50. The control system 50 of this example comprises a data processing device 52 and a memory 54. The memory 54 has a computer program stored therein. The computer program comprises program code which, when executed by the data processing device 52, causes the data processing device 52 to perform, or command performance of, various operations as described herein. The control system 50 is configured to control electric motors 56 of the first industrial robot 14a to drive respective axes thereof to move the end effector 20a in space.

The actuator system 12 of this example further comprises a first driver 58a for generating a first electric current 60a to the first electromagnet 22a and a second driver 58b for generating a second electric current 60b to the second electromagnet 22b. The first and second drivers 58a, 58b are controlled by the control system 50.

The sensor 24a is configured to provide distance data 62 indicative of a distance to an object. The distance data 62 is communicated from the sensor 24a to the control system 50 and is thereby also provided in the control system 50, e.g., in the memory 54 thereof. The control system 50 is also configured to provide a target distance value 64. The target distance value 64 may for example be set by a user when programming the actuator system 12. In this example, a constant target distance value 64 is used. The target distance value 64 may for example be at least 3 mm, such as 20 mm. Fig. 4 schematically represents a partial top view of the plant io when the end effector 20a is positioned with respect to the door 34a in a closed position 66. In Fig. 4, the end effector 20a has been moved into the window opening 44 and somewhat lowered such that the door 34a is positioned between the first and second electromagnets 22a, 22b. The target distance value 64 maybe set such that the door 34a is centered between the first and second electromagnets 22a, 22b, e.g., based on dimensions of the end effector 20a and the door 34a.

Each of the first and second electromagnets 22a, 22b faces an opposite side of the door 34a and is thereby offset in a direction transverse to a main extension plane 68 of the door 34a. The end effector 20a does however not contact the door 34a.

As shown in Fig. 4, both the first electromagnet 22a and the sensor 24a are positioned at a distance 70 from the door 34a. The sensor 24a thus provides distance data 62 corresponding to the distance 70. The distance 70 as illustrated in Fig. 4 also corresponds to an offset direction between the first electromagnet 22a and the door 34a. By knowing the distance 70, a distance between the first and second electromagnets 22a, 22b and a thickness of the door 34a, the control system 50 can also determine a distance between the second electromagnet 22b and the door 34a.

The control system 50 is configured to control the first and second electric currents 60a, 60b to the first and second electromagnets 22a, 22b, respectively, based on the distance data 62. In this example, a PID controller is implemented in the control system 50. The PID controller of this example uses the distance data 62 as the measured variable, the first and second electric currents 60a, 60b as the control variables, and the target distance value 64 as the desired setpoint.

Fig. 5 schematically represents a partial top view of the plant 10. In Fig. 5, the control system 50 controls the end effector 20a to move along a circular arc centered at the hinge 36 while maintaining the orientation of the end effector 20a fixed with respect to the door 34a. The end effector 20a thus always moves in the offset direction between the first electromagnet 22a and the door 34a. During this movement, the control system 50 controls the first driver 58a such that the first electric current 60a is sent to the first electromagnet 22a, and the second driver 58b such that the second electric current 60b is not sent to the second electromagnet 22b. The first electric current 60a is controlled based on the distance data 62.

Due to the first electric current 60a, a magnetic field 7231 is generated by the first electromagnet 22a that magnetically attracts the door 34a towards the first electromagnet 22a simultaneously with the movement of the end effector 20a. Should the distance 70 increase, e.g., due to the movement of the end effector 20a, the control system 50 immediately corrects this by controlling the first electromagnet 22a such that a strength of the magnetic field 72a! increases. On the contrary, should the distance 70 decrease, e.g., due to the magnetic field 7231, the control system 50 immediately corrects this by controlling the first electromagnet 22a such that the strength of the magnetic field 7231 decreases. In this way, the control system 50 accurately and immediately controls the magnetic field 7231 during the movement of the end effector 20a, here to maintain the distance 70 constant. This provides for a very accurate control of the door 34a by magnetic force to undergo an opening movement 74 where the door 34a rotates around the hinge 36 and where the end effector 20a moves along with the end effector 20a without contacting the end effector 20a.

Fig. 6 schematically represents a partial top view of the plant 10. In Fig. 6, the control system 50 controls the first driver 58a such that the first electric current 60a is no longer sent to the first electromagnet 22a. Instead, the second driver 58b is controlled such that the second electric current 60b is sent to the second electromagnet 22b in accordance with the distance data 62. Due to the second electric current 60b, a magnetic field 72b is generated by the second electromagnet 22b that magnetically attracts the door 34a towards the second electromagnet 22b. At the same time, the movement of the end effector 20a is slowed down. The opening movement 74 is thereby braked. As one alternative, both the first and second electromagnets 22a, 22b may be simultaneously active during the opening movement 74 to more stably hold the door 34a therebetween by both magnetic fields 72a!, 72b.

Fig. 7 schematically represents a partial top view of the plant 10 when the door 34a has been stopped in the open position 46. The first industrial robot 14a can thus stably and reliably move the door 34a from the closed position 66 to the open position 46 and stop the door 34a in the open position 46 without contacting the door 34a.

Once the door 34a is in the open position 46, the second industrial robot 14b may paint surfaces of the bodywork 32a that are now accessible. The first industrial robot 14a may or may not remain in the position shown in Fig. 7 during such painting. In any case, a light coat of Vaseline may optionally be used on the sensor 24a to prevent contamination by the paint 28.

After painting, the first industrial robot 14a may move the door 34a from the open position 46 back to the closed position 66 without contacting the door 34a. Such procedure may be reverse to the above-described procedure for causing the opening movement 74 of the door 34a. Thus, the second electromagnet 22b may be active during a closing movement and the first electromagnet 22a may be used to brake the closing movement.

The control system 50 may then control one or both of the first and second electromagnets 22a, 22b to perform a degaussing process, i.e., to provide an alternating magnetic field that gradually reduces in strength to reduce any residual magnetism in the door 34a. Such degaussing process is known as such to the skilled person.

Fig. 8 schematically represents a partial top view of the plant 10 during the opening movement 74 of the door 34a by magnetic force using an end effector 20b according to a further example. The first industrial robot 14a may use the end effector 20b instead of the end effector 20a. The end effector 20b differs from the end effector 20a by not comprising the second electromagnet 22b. In Fig. 8, the door 34a may, instead of being forced by the second electromagnet 22b, stop in the open position 46 after the opening movement 74 due to friction in the hinge 36, or by a hard stop or a soft stop, e.g., integrated in the hinge 36. When the first industrial robot 14a carries the end effector 20b, the first industrial robot 14a functions as a contactless electromagnetic door opener with respect to the door 34a. The end effector 20b may act on an opposite side of the door 34a in order to magnetically force the door 34a to undergo the closing movement.

Fig. 9 schematically represents a partial top view of the plant 10 during a closing movement 76 of a door 34b according to a further example by magnetic force using an end effector 20c according to a further example. The door 34b differs from the door 34a in that the door 34b comprises a permanent magnet 78. The end effector 20c differs from the end effector 20a by not comprising the second electromagnet 22b or the sensor 24a. In the example in Fig. 9, a sensor 24b is provided at the hinge 36. The sensor 24b sends sensor data 80 indicative of a rotational position of the door 34b around the hinge 36 to the control system 50. Since the position of the end effector 20b, and hence also of the first electromagnet 22a, is known to the control system 50, the control system 50 determines the distance 70 based on the position of the first electromagnet 22a and the sensor data 80. The control system 50 controls the first electromagnet 22a to provide the magnetic field 72a! attracting the door 34b, and the permanent magnet 78 therein, in order to cause the door 34b to undergo the opening movement 74. Conversely, the control system 50 controls the first electromagnet 22a to provide a reverse magnetic field 7232 repelling the permanent magnet 78 in the door 34b in order to cause the door 34b to undergo the closing movement 76. The magnetic field 7231 can for example be reversed to the magnetic field 7232 by changing a direction of the first electric current 60a. One, several or all of the magnetic fields 7231, 7232 and 72b may also be referred to with reference numeral "72".

Fig. 10 schematically represents a top view of a further example of magnetic manipulation of an object 34c, such as a workpiece. In Fig. 10, the object 34c is contactlessly manipulated by the end effector 20b to move two- dimensionally over a base structure 32b, such as a horizontal floor.

Fig. 11 schematically represents a top view of a further example of magnetic manipulation of the object 34c in a contactless manner by the end effector 20b. In Fig. 11, the object 34c is constrained to move linearly by a base structure 32c, such as a rail.

While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.

Claims

1. A method of moving an object (34a-34c), the method comprising:

- providing an actuator (14a) carrying an electromagnet (22a, 22b);

- providing, in a control system (50), distance data (62) indicative of a distance (70) between the electromagnet (22a, 22b) and the object (34a- 34c);

- controlling, by the control system (50), the actuator (14a) to move the electromagnet (22a, 22b); and

- controlling, by the control system (50), during movement of the electromagnet (22a, 22b) and based on the distance data (62), an electric current (60a, 60b) to the electromagnet (22a, 22b) such that the electromagnet (22a, 22b) generates a magnetic field (72) exerting a force on the object (34a-34c).

2. The method according to claim 1, wherein the control of the electric current (60a, 60b) is performed based on a target distance value (64).

3. The method according to any of the preceding claims, wherein for each position of the object (34a-34c), the actuator (14a) is controlled to move the electromagnet (22a, 22b) substantially in an offset direction between the electromagnet (22a, 22b) and the object (34a-34c).

4. The method according to any of the preceding claims, wherein the object (34a, 34c) is movable relative to a base structure (32a; 32c) in only a single degree of freedom.

5. The method according to claim 4, wherein the single degree of freedom is a rotational degree of freedom.

6. The method according to claim 5, wherein the actuator (14a) is controlled to move the electromagnet (22a, 22b) about the single degree of freedom.

7. The method according to any of the preceding claims, wherein the electromagnet (22a, 22b) is a first electromagnet (22a) and the electric current (60a, 60b) is a first electric current (60a), and wherein the method further comprises:

- providing the actuator (14a) to carry a second electromagnet (22b);

- controlling, by the control system (50), the actuator (14a) to move the first and second electromagnets (22a, 22b) while the object (340-340) is positioned between the first and second electromagnets (22a, 22b); and

- controlling, by the control system (50), during movement of the first and second electromagnets (22a, 22b) and based on the distance data (62), a second electric current (60b) to the second electromagnet (22b) such that the second electromagnet (22b) generates a magnetic field (72) exerting a force on the object (340-340).

8. A control system (50) comprising at least one data processing device (52) and at least one memory (54) having at least one computer program stored therein, the at least one computer program comprising program code which, when executed by the at least one data processing device (52), causes the at least one data processing device (52) to:

- control an actuator (14a) carrying an electromagnet (22a, 22b) to move the electromagnet (22a, 22b);

- provide distance data (62) indicative of a distance (70) between the electromagnet (22a, 22b) and an object (34a-34c);

- control, during movement of the electromagnet (22a, 22b) and based on the distance data (62), an electric current (60a, 60b) to the electromagnet (22a, 22b) such that the electromagnet (22a, 22b) generates a magnetic field (72) exerting a force on the object (34a-34c).

9. The control system (50) according to claim 8, wherein the control of the electric current (60a, 60b) is performed based on a target distance value (64).

10. The control system (50) according to claim 8 or 9, wherein the at least one computer program comprises program code which, when executed by the at least one data processing device (52), causes the at least one data processing device (52) to:

- for each position of the object (34a-34c), control the actuator (14a) to move the electromagnet (22a, 22b) substantially in an offset direction between the electromagnet (22a, 22b) and the object (34a-34c).

11. The control system (50) according to any of claims 8 to 10, wherein the at least one computer program comprises program code which, when executed by the at least one data processing device (52), causes the at least one data processing device (52) to:

- control the actuator (14a) to move the electromagnet (22a, 22b) in a single degree of freedom.

12. The control system (50) according to claim 11, wherein the single degree of freedom is a rotational degree of freedom.

13. The control system (50) according to any of claims 8 to 12, wherein the electromagnet (22a, 22b) is a first electromagnet (22a) and the electric current (60a, 60b) is a first electric current (60a), and wherein the at least one computer program comprises program code which, when executed by the at least one data processing device (52), causes the at least one data processing device (52) to:

- control the actuator (14a) carrying the first electromagnet (22a) and a second electromagnet (22b) to move the first and second electromagnets (22a, 22b) while the object (340-340) is positioned between the first and second electromagnets (22a, 22b); and

- control, during movement of the first and second electromagnets (22a, 22b) and based on the distance data (62), a second electric current (60b) to the second electromagnet (22b) such that the second electromagnet (22b) generates a magnetic field (72) exerting a force on the object (340-340).

14. An actuator system (12) comprising the control system (50) according to any of claims 8 to 13 and the actuator (14a). 15- The actuator system (12) according to claim 14, wherein the actuator (14a) is an industrial robot.