Method of controlling electrically adjustable seat assembly and electrically adjustable seat assembly

Abstract

The invention relates to a method for controlling an electrically adjustable seat assembly (2) having a vehicle seat (18) and two electric drive units (12), each of the two electric drive units (12) having an electric motor (14), the electrically adjustable seat assembly (2) having a control and analysis unit (20), the invention relates to a motor-driven adjustable seat assembly (2) comprising a control and analysis unit (4) which is connected to the motors (14) in a signaling manner for the purpose of controlling the motors (14), the motor-driven adjustable seat assembly (2) having an adjustment mechanism (4), the motors (14) being coupled to the adjustment mechanism (4) such that the motors work cooperatively via the adjustment mechanism (4), wherein at least one of the electric motors (14) is controlled by the control and evaluation unit (20), and wherein a measured variable (I) is acquired during the control, which measured variable has a functional relationship with a torque of the controlled electric motor (14).

Description

[0001] This invention relates to a method for controlling an electrically adjustable seat assembly. Furthermore, this invention also relates to an electrically adjustable seat assembly.

[0002] At least one vehicle seat is typically arranged in the interior space of a motor vehicle, and the vehicle seat is constructed as a single seat. This vehicle seat is usually part of a seat assembly that is first prefabricated and then installed into the interior space of the motor vehicle.

[0003] In most cases, in addition to the vehicle seat, the seat assembly also has two pairs of guide rails via which the seat assembly is installed in the interior space of the motor vehicle, and via these two pairs of guide rails, the vehicle seat can be moved or adjusted longitudinally. Such a seat assembly can be found, for example, in DE 10 2016 123 836 A1.

[0004] The object of the present invention is to provide an electrically adjustable seat assembly with an advantageous construction and an advantageous method for controlling the electrically adjustable seat assembly.

[0005] According to the invention, with respect to the method, this objective is achieved by the features of claim 1, and with respect to the electrically adjustable seat assembly, by the features of claim 12. Advantageous designs and improvements are the subject of the dependent claims. The advantages and designs mentioned with respect to the method can also be applied analogously to the seat assembly, and vice versa.

[0006] The method according to the invention is here configured for controlling the electrically adjustable seat assembly according to the invention.

[0007] The electrically adjustable seat assembly according to the invention is also designed and adapted to perform the method according to the invention in at least one operating mode. Furthermore, this electrically adjustable seat assembly, i.e., the electrically adjustable seat assembly according to the invention, is designed for motor vehicles, particularly passenger cars. This seat assembly is typically prefabricated and then installed into the interior space of the motor vehicle.

[0008] Independently, this seating assembly, namely the electrically adjustable seating assembly, includes a vehicle seat. This vehicle seat is typically configured as a single seat in this case, such as a driver's seat or a front passenger seat.

[0009] Furthermore, the seat assembly has two electric drive units. Each of the two electric drive units has an electric motor. Therefore, the seat assembly has two electric motors. Depending on the application, these electric motors are, for example, configured as so-called brushless motors.

[0010] Furthermore, the seat assembly includes a control and analysis unit that is connected to the two motors via signal technology for the purpose of controlling them. According to a variant, this control and analysis unit may be, for example, a separate control device. According to an alternative variant, each of the two motors is part of a unit with integrated control electronics, such as a motor unit consisting of the aforementioned brushless motor and control electronics. In this variant, the control electronics of the two units are typically associated with each other in a master-slave configuration and are usually interconnected via a data bus. Here, the control electronics with the master function acts as the aforementioned control and analysis unit. According to another alternative variant, each of the two motors is also part of a unit with integrated control electronics, but the control electronics of these two units are connected to a higher-level control device. In this case, the higher-level control device appropriately acts as the aforementioned control and analysis unit.

[0011] Independently, the electrically adjustable seat assembly further includes an adjustment mechanism. Here, the aforementioned two electric motors are connected to this adjustment mechanism, specifically, enabling the two motors to work in concert via the adjustment mechanism. The adjustment mechanism and the two electric motors are suitably part of an adjustment device by which the vehicle seat of the electrically adjustable seat assembly can be adjusted. Depending on the application, the adjustment mechanism is designed for longitudinal adjustment of the vehicle seat (i.e., adjustment of the longitudinal position of the vehicle seat), height adjustment of the vehicle seat, tilt adjustment of the vehicle seat, or backrest tilt adjustment of the vehicle seat.

[0012] During the execution of this method, at least one of the two motors is now controlled by a control and analysis unit, and during this control, measurement parameters are acquired that are functionally related to the torque of the controlled motor. Preferably, in this case, current intensity is acquired as a measurement parameter, which is functionally related to the current transmitted to the motor.

[0013] Therefore, this method is advantageous among other things because the collected measurement parameters typically provide information on how the regulating mechanism and the electric motor work together. Thus, it is generally possible to infer whether undesirable stresses exist. For example, such undesirable stresses may occur if large tolerances are allowed when assembling the seat assembly and / or installing the seat assembly into the aforementioned motor vehicle.

[0014] A further advantage is that, during the execution of this method, multiple measurement values ​​are determined for the measurement parameters, particularly for different adjustment positions of the regulating mechanism or for different rotor positions of the rotor of one motor in the electric motor. Based on the determined measurement values, a measurement value curve is established, and local or global extrema are determined for this measurement value curve. This allows for the acquisition of additional information.

[0015] In a favorable improvement, during the execution of the method, at least one virtual reference value, such as a virtual zero point or virtual zero position, is predetermined or modified based on the determined local or global extreme value. Specifically, at least one virtual reference value is chosen such that the aforementioned undesirable stress is reduced. Preferably, at least one virtual reference value is further predetermined or modified based on the determined local or global extreme value for at least one motor in the motor assembly. Alternatively, at least one virtual reference value is predetermined or modified for the regulating mechanism.

[0016] As previously described, in at least one application, the adjustment mechanism is designed for longitudinal adjustment of a vehicle seat, i.e., longitudinal position adjustment of the vehicle seat. In this case, the adjustment mechanism and the seat assembly suitably have two pairs of longitudinally elongated guide rails. Each guide rail pair has a floor guide rail and a seat guide rail connected to the floor guide rail. In this case, at least in the installed state of the seat assembly, the floor guide rail is connected to the seat guide rail, for example via a sliding bearing, or in other ways known per se, such that the seat guide rail can move longitudinally relative to the floor guide rail.

[0017] Furthermore, each guide rail pair is assigned one of two electric drive units, enabling the seat guide rail to move longitudinally relative to the floor guide rail by means of the motor of the assigned electric drive unit. In this case, a control and analysis unit is adapted to control the electric drive unit for adjustment purposes, so that the vehicle seat connected to the seat guide rail can move longitudinally relative to the floor guide rail under the control of the control and analysis unit, thereby enabling longitudinal adjustment. Thus, longitudinal adjustment, i.e., electric longitudinal adjustment, is achieved in this seat assembly.

[0018] The aforementioned floor rails are also designed for fixing to the floor assembly within the interior space of a motor vehicle. After fixing, the two floor rails are typically aligned parallel to each other with good approximation and parallel to the longitudinal direction. However, a flush arrangement is not mandatory. More precisely, in some cases, due to installation tolerances, a significant offset, such as 5 mm, may exist between the two floor rails in the longitudinal direction.

[0019] Based on at least two advantageous method variations, this method is now used to compensate for possible longitudinal offset of the floor guide rail.

[0020] According to one of these method variations, compensation is performed during each adjustment period. That is, compensation is approximately performed in real time.

[0021] According to another variation of the method, the electric drive unit is controlled such that calibration is first performed to compensate for any possible longitudinal offset of the floor guide rail. Here, appropriate measurement parameters are acquired during the calibration process, and particularly only during the calibration process, to determine local or global extrema, and preferably at least one virtual reference value is predetermined, particularly for at least one of the motors. Subsequently, if the vehicle seat needs to be adjusted longitudinally, the electric drive unit is typically controlled simply and synchronously by the control and analysis unit.

[0022] In this context, among other considerations, the following are also taken into account: It is anticipated that at least some motor vehicles will be adapted for fully autonomous driving control in the future. "Fully" here means that even the driver's supervisory role will no longer be required. This opens up entirely new possibilities for interior space design, particularly in the adoption of vehicle seats with a wider range of adjustment options. For example, longitudinal adjustments with a significantly greater range of motion than before are provided.

[0023] However, when using two pairs of guide rails with a larger adjustment range, the mechanical synchronization provided in DE 10 2016 123 836 A1 can no longer be easily achieved. Therefore, as in at least one embodiment of the seat assembly according to the invention, an electric drive unit is provided for each pair of guide rails. However, if, for example, due to installation tolerances, there is a significant offset between the two floor guide rails in the longitudinal direction, this usually results in adverse stress, which generally has a negative impact on function and / or leads to increased wear in the electric longitudinal adjustment.

[0024] To avoid or at least mitigate these disadvantages, the setup is to compensate for any potential misalignment between the two floor rails, thereby eliminating any possible adverse stresses. For this purpose, the aforementioned real-time compensation or the aforementioned calibration is performed.

[0025] Therefore, various advantages can be achieved in principle. Thus, cost reduction is feasible, among other things, particularly through reduced tooling costs, as larger installation tolerances can be tolerated with compensation via calibration. Furthermore, functional reliability can be improved because potential adverse stresses are compensated for. In addition, wear phenomena can be reduced.

[0026] Here, during the calibration process, for example, at least one of the longitudinal positions of the two seat rails is adjusted, that is, one of the longitudinal positions of the two seat rails. In particular, in this case, the relative distance between the longitudinal positions of the two seat rails is reduced. Alternatively or additionally, at least one virtual reference value is predetermined for at least one of the motors, that is, for example, a virtual zero position or virtual zero position, or at least one previously predetermined virtual reference value is changed.

[0027] Subsequently, if the vehicle seat needs to be adjusted longitudinally, the electric drive unit is typically controlled synchronously by the control and analysis unit. This means, for example, that essentially the same electrical signal, and in particular essentially the same voltage signal, is simultaneously transmitted to both electric drive units by the control and analysis unit. In this way, longitudinal adjustment with electrical synchronization is achieved.

[0028] Depending on the application, calibration is also performed before each longitudinal adjustment of the vehicle seat. Depending on the alternative variant, calibration is performed at certain time intervals.

[0029] However, calibration is preferably performed only before the first longitudinal adjustment of the vehicle seat, such as after the seat assembly is installed, after a part of the seat assembly is replaced, or before the first longitudinal adjustment after the control and analysis unit is reset / reset.

[0030] Further suitable is that, during the calibration process, one of the two electric drive units (hereinafter referred to as the first electric drive unit) is controlled by the control and analysis unit so that the seat rail (hereinafter referred to as the first seat rail) of which it belongs moves longitudinally back and forth from the initial position, so that it occupies multiple different longitudinal positions in sequence.

[0031] According to an advantageous embodiment, a current intensity is determined for each of the longitudinal positions of the first seat guide rail for the motor of the first drive unit. In an advantageous improvement, a current intensity curve is then determined based on the determined current intensity, and local or global extrema are determined for this current intensity curve.

[0032] Furthermore, the difference between the initial position and the longitudinal position of the extreme value is preferably determined as the longitudinal offset of the floor guide rail. This determined offset is then appropriately compensated during the calibration process.

[0033] Furthermore, it is advantageous that during the calibration process, the control and analysis unit controls another of the two electric drive units (hereinafter referred to as the second electric drive unit) so that the associated seat rail (hereinafter referred to as the second seat rail) remains in its position as the first seat rail moves back and forth.

[0034] As mentioned earlier, real-time compensation is performed as an alternative to calibration, i.e., compensation is made during the adjustment of the longitudinal position of the vehicle seat. In this case, control is typically performed such that one of the two seat rails initially gradually leads the other, then the other seat rail catches up again and eventually takes the lead. In the reference frame of one of the two seat rails, this is equivalent to the longitudinal fore-and-aft movement of the other seat rail as described above.

[0035] During this period, position-based current measurements should be performed appropriately, or current measurements should be performed based on the relative position between the two seat rails or based on the relative position between the current virtual zero positions of the two motors or the two motor rotors.

[0036] Alternatively, current measurements can be performed using cycle control, for example, by reading the cycle using the aforementioned control electronics or control device. Each cycle interval is typically allocated to the rotation angle of the rotor of one of the motors. For example, if current measurements are performed in 20µs cycles, approximately 30 to 40 current measurements are determined per rotor revolution, with one rotor revolution typically corresponding to a longitudinal adjustment displacement of 1 mm.

[0037] Preferably, at least one of the virtual zeros is then further adjusted or re-predetermined. This is preferably done during continuous operation, or alternatively during the next adjustment.

[0038] To do this, for example, the virtual zero position can be changed by a small increment (e.g., 90° rotor position) or by multiple such increments.

[0039] Therefore, this real-time compensation is advantageous among other things, because it can also compensate for the effects of changes, such as those caused by temperature expansion.

[0040] Independently, it is preferable that the aforementioned compensation is performed automatically by the control and analysis unit. That is, the control and analysis unit is constructed and adapted in this case to perform the compensation automatically.

[0041] Furthermore, it is advantageous to alternatively or additionally adjust the permissible adjustment displacement or adjustment stroke based on the determined extreme value or the determined offset. This permissible adjustment displacement or adjustment stroke is typically predetermined by a so-called soft stop, i.e., by a virtual limit. With this virtual limit, approaching physical boundaries, such as mechanical stops, should generally be avoided.

[0042] The embodiments of the present invention will be further described below with reference to the schematic diagrams. Wherein:

[0043] Figure 1 The side view shows a seat assembly with two rail pairs, a base unit, and a vehicle seat;

[0044] Figure 2 The perspective view shows the guide rail pairs along with the assigned drive units;

[0045] Figure 3 The block diagram shows the basic unit along with the electric motor of the drive unit;

[0046] Figure 4 The graph shows the relationship between current intensity and vertical position; and

[0047] Figure 5 The top view shows the guide rail pairs marked to illustrate the calibration process.

[0048] In all drawings, corresponding parts and dimensions always use the same reference labels.

[0049] exist Figure 1 The seat assembly 2 described below is shown in a side view. This seat assembly is constructed for a motor vehicle, such as a passenger car, not shown. Here, the seat assembly 2 is preferably prefabricated and then installed into the interior space of the motor vehicle, not shown.

[0050] In this embodiment, the seat assembly 2 has two pairs of elongated guide rails 4, which are parallel to each other and parallel to the longitudinal direction 6, at least in the installed state of the seat assembly 2. This is in Figure 2 The diagram shows that each guide rail pair 4 has a floor guide rail 8 and a seat guide rail 10 connected to the floor guide rail 8. In this case, the floor guide rail 8 is constructed in a manner not shown in detail for fixing to a floor assembly (not shown) within the interior space of the motor vehicle, and is connected to the seat guide rail 10 at least in the installed state of the seat assembly 2, such that the seat guide rail 10 can move longitudinally 6 relative to the floor guide rail 8.

[0051] Furthermore, each rail pair 4 is assigned an electric drive unit 12, enabling the seat rail 10 to move longitudinally 6 relative to the floor rail 8 via the assigned electric drive unit 12. In this case, each of the electric drive units 12 has its own electric motor 14.

[0052] In this embodiment, at least the motor 14 of the electric drive unit 12 is housed in the base unit 16 of the seat assembly 2. This base unit 16 is fixed to the seat rail 10 and supports the vehicle seat 18. In an alternative embodiment, not shown, the seat assembly 2 does not have this base unit 16. Instead, the vehicle seat 18 is directly fixed to the seat rail 10. In both embodiments, the vehicle seat 18 is preferably configured as a single seat.

[0053] In this embodiment, the two electric drive units 12, particularly the two electric motors 14, are further connected to the control and analysis unit 20 via signal technology. The control and analysis unit, according to... Figure 3 In this embodiment, it is integrated into the base unit 16. In this case, the control and analysis unit 20 is adapted to control the electric drive unit so that the vehicle seat 18 can move longitudinally relative to the floor rail under the control of the control and analysis unit 20, thereby enabling longitudinal adjustment. That is, longitudinal adjustment, i.e., electric longitudinal adjustment, is thus achieved in the seat assembly 2.

[0054] As previously stated, the floor rails 8 are designed to be fixed to the floor assembly within the interior space of a motor vehicle, and after being fixed, the two floor rails 8 are parallel and aligned with each other. However, a flush arrangement of the two floor rails 8 is not mandatory. More precisely, in some cases, due to installation tolerances, an installation offset 22 may exist between the two floor rails 8 viewed longitudinally 6. This is from... Figure 2 As can be seen in the image. Here, the installation offset of 22 on the right is indicated by a long dashed line.

[0055] This installation offset 22 typically presents a disadvantage; therefore, the aforementioned control and analysis unit 20 is adapted to automatically perform calibration, for example, during its initial commissioning, thereby at least partially compensating for the effects of the installation offset 22. After calibration, if the vehicle seat 18 needs to be adjusted longitudinally 6, the control and analysis unit 20 simply synchronizes the control of the electric drive unit 12 each time. For this purpose, the control and analysis unit 20 performs the corresponding adaptation.

[0056] In this embodiment, during the calibration process, at least one virtual reference value, i.e., a virtual zero position or zero location, is changed for at least one of the seat rails 10. This virtual reference value is set, for example, in a so-called standardized operation at the seat assembly 2 manufacturer. To this end, one of the two electric drive units 12 (hereinafter referred to as the first electric drive unit 12) is first controlled by the control and analysis unit 20 such that the associated seat rail 10 (hereinafter referred to as the first seat rail 10) moves from its initial position x A It begins to move back and forth along the longitudinal direction 6, so that it occupies multiple different longitudinal positions x in sequence.

[0057] During this period, the control and analysis unit 20 controls another electric drive unit (hereinafter referred to as the second electric drive unit 12) of the two electric drive units 12 so that the seat rail 10 (hereinafter referred to as the second seat rail 10) is kept in its position.

[0058] For each of these longitudinal positions x, a current intensity I is determined for the motor 14 of the first drive unit 12. Based on the determined current intensity I, a current intensity curve I(x) is then further determined, and local or global extrema I are determined for this current intensity curve I(x). E This is in Figure 4 The text indicates that the initial position x along the longitudinal direction 6 is further determined. A With extreme value I E Vertical position x E The difference between them.

[0059] This difference is ultimately set as the drive offset 24, and the aforementioned virtual zero position or zero location moves by an amount equal to the drive offset 24. Here, depending on the implementation variant, either the virtual zero position or zero location of the first seat guide 10 is moved, or the virtual zero position or zero location of the second seat guide 10, which has not been moved, is moved. Figure 2 In the text, the drive offset 24 is indicated by a short dashed line.

[0060] According to the alternative implementation variant, the drive offset is proportionally distributed to the two seat rails 10, and the zero position or zero position of the two seat rails 10 is then changed accordingly.

[0061] Furthermore, such a variant is preferred, wherein a so-called soft stop S is set by the manufacturer of seat assembly 2. Figure 5 As shown, each floor rail in the floor rails 8 is typically equipped with a mechanical stop M at each end, and the two mechanical stops M of one floor rail 8 limit the possible displacement of the seat rail 10 along the floor rail 8. However, due to the aforementioned installation offset 22, the mechanical stops M of the two floor rails 8 are also offset from each other, so that the possible displacement MV of the vehicle seat 18 is reduced compared to the possible displacement of the seat rail 10.

[0062] However, approaching the mechanical stop M is generally undesirable because it usually negatively impacts sound performance and durability. Therefore, it is preferable to set the approach to this mechanical stop M only once, as far as possible, i.e., for position determination.

[0063] After this approach, a soft stop S is preferably automatically set by the control and analysis unit 20. Specifically, it is generally set based on the position when approaching the mechanical stop M. This soft stop S is typically set for both floor rails 8 and at least temporarily limits the permissible displacement, wherein the temporarily permissible displacement of the vehicle seat 18 is also reduced compared to the temporarily permissible displacement of the seat rail 10. The soft stop S is a virtual reference value, wherein it is based on... Figure 5In this embodiment, the soft stop S shown on the left side of each floor rail 8 functions as a virtual zero or zero position for the corresponding floor rail 8.

[0064] During the aforementioned calibration process, based on Figure 5 In this embodiment, the front soft stop S of the upper floor guide rail 8 moves by a determined drive offset 24 until the calibrated front soft stop KS. That is, the aforementioned zero position or zero location is thus moved. Furthermore, the rear soft stop S shown on the right side of the floor guide rail 8 also moves by a determined drive offset 24 until the calibrated rear soft stop KS, wherein the two calibrated soft stops KS subsequently limit the final permissible movement displacement ZV of the vehicle seat 18.

[0065] This ensures that despite the installation offset 22, it does not approach any of the four mechanical stops M, whether for one floor rail 8 or for another. It should be noted that the control and analysis unit 20 typically only identifies that it has approached a certain mechanical stop M when determining the aforementioned position, but does not identify which mechanical stop it has approached. According to... Figure 5 In one embodiment, to determine the position, the vehicle seat 18 is moved to the far left, approaching the mechanical stop M of the floor rail 8 shown below. Then, a soft stop is performed relative to this setting.

[0066] List of reference numerals

[0067] 2 Seat Components

[0068] 4 guide rails

[0069] 6 Vertical

[0070] 8 floor rails

[0071] 10 Seat Rails

[0072] 12 drive units

[0073] 14 electric motors

[0074] 16 basic units

[0075] 18 vehicle seats

[0076] 20 Control and Analysis Units

[0077] 22 Installation Offset

[0078] 24 drive offset

[0079] x Vertical position

[0080] x A initial position

[0081] xE Vertical position of extreme values

[0082] I Current Intensity

[0083] I(x) Current Intensity Curve

[0084] I E extremum

[0085] M mechanical stop

[0086] Possible displacement of MV

[0087] S-Soft Stop

[0088] ZV allows for movement and displacement

[0089] Soft stop after KS calibration

Claims

1. Method for controlling an electrically adjustable seat assembly (2) having a vehicle seat (18) and two electric drive units (12), wherein - each of the two electric drive units (12) has an electric motor (14), - the electrically adjustable seat assembly (2) has a control and evaluation unit (20) which is connected to the electric motors (14) in a signal-technical manner for the purpose of controlling the electric motors (14), - the electrically adjustable seat assembly (2) has a regulating mechanism (4), - the electric motors (14) are coupled to the regulating mechanism (4) such that they work together via the regulating mechanism (4), - at least one of the electric motors (14) is controlled by the control and evaluation unit (20), and - a measured variable (I) which is a function of the torque of the electric motor (14) being controlled is acquired during the control.

2. Method according to claim 1, wherein A plurality of measurement values (I) is determined for the measurement quantity (I), wherein a measurement value curve (I(x)) is determined on the basis of the determined measurement values (I), and wherein a local or global extreme value (I E ) is determined for the measurement value curve (I(x)).

3. Method according to claim 2, wherein determining a local or global extremum (I E ) of the motor current (I) of the electric motor (14) and predetermining a virtual zero position for one of the electric motors (14) on the basis of the determined local or global extremum (I 4. Method according to any one of claims 1 to 3, wherein - the regulating mechanism (4) has two pairs (4) of guides which are elongated in the longitudinal direction (6), - each pair (4) of guides has a floor guide (8) and a seat guide (10) which is connected to the floor guide (8), - each pair (4) of guides is assigned one of the electric drive units (12) such that the seat guide (10) can be moved relative to the floor guide (8) in the longitudinal direction (6) via the assigned electric drive unit (12), - the control and evaluation unit (20) is adapted to control the electric drive units (12) for the purpose of adjustment such that the vehicle seat (18) which is connected to the seat guide (10) can be moved relative to the floor guide (8) in the longitudinal direction (6) under the control of the control and evaluation unit (20) and thus can be adjusted longitudinally.

5. Method according to claim 4, wherein The control of the electric drive units (12) is carried out in such a way that a calibration is first carried out to compensate for the offset (22) of the floor rail (8) in the longitudinal direction (6) and subsequently the vehicle seat (18) is adjusted in the longitudinal direction, the electric drive units (12) being controlled synchronously by the control and evaluation unit (20), wherein the measured variable (I) is acquired during the calibration, the local or global extreme value (I E ) is determined and the virtual zero position is predetermined for at least one of the electric motors (14).

6. Method according to claim 5, wherein, the calibration is carried out only before the first longitudinal adjustment of the vehicle seat (18).

7. Method according to claim 5 or 6, wherein during the calibration process one of the two electric drive units (12), a first electric drive unit (12), is controlled by the control and evaluation unit (20) such that the associated seat rail (10), a first seat rail (10), is moved back and forth along the longitudinal direction (6) from an initial position (x A ) so that it successively occupies a plurality of different longitudinal positions (x).

8. Method according to claim 7, wherein for the longitudinal position (x) of the first seat guide (10) the electric currents (I) of the electric motors (14) of the first drive unit (12) are each determined as measured values (I) of the measured variable (I).

9. Method according to claim 8, wherein a current intensity curve (I(x)) is determined on the basis of the determined current intensity (I), wherein a local or global extremum (I E ) is determined for the current intensity curve (I(x)), and wherein a difference between the initial position (x A ) and a longitudinal position (x E ) of the extremum (I E ) is determined as the offset (22) of the floor track (8) in the longitudinal direction (6).

10. Method according to claim 9, wherein during the calibration the two electric drive units (12) are controlled such that the determined offset (22) is compensated.

11. Method according to any one of claims 7 to 10, wherein during the calibration process the other one of the two electric drive units (12), namely the second electric drive unit (12), is controlled by the control and evaluation unit (20) such that the associated seat rail (10), namely the second seat rail (10), is held in its position.

12. An electrically adjustable seat assembly (2) configured and adapted for carrying out the method according to any one of the preceding claims in at least one operating mode.

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