ADJUSTMENT SYSTEM AND OPERATING METHOD WITH ADAPTATION ROUTINE

Abstract

It is provided an adjustment system for a vehicle, comprising an adjustment element adjustable along two mutually opposite adjustment directions, an adjustment drive with at least one electric drive motor for generating a drive force for adjusting the adjustment element, and an electronic control unit for controlling the drive motor by specifying a motor current for generating the drive force in a height required for an adjustment operation, wherein via the electronic control unit at least one control variable is specified for setting the motor current. The control variable is based on a torque constant for the electric drive motor and an efficiency parameter characterizing the efficiency of the adjustment drive, which in the regular operation of the adjustment system can be updated via an adaptation routine.

Claims

1. An adjustment system for a vehicle, comprising an adjustment element adjustable along two mutually opposite adjustment directions, an adjustment drive with at least one electric drive motor for generating a drive force for the adjustment of the adjustment element, and an electronic control unit for controlling the drive motor by specifying a motor current for generating the drive force in a height required for an adjustment operation, wherein via the electronic control unit at least one control variable is specified for setting the motor current, wherein the control variable is based on a torque constant for the electric drive motor and an efficiency parameter characterizing the efficiency of the adjustment drive, and the electronic control unit is configured to carry out an adaptation routine for updating the efficiency parameter in operation of the adjustment system.

2. The adjustment system according to claim 1, wherein the electronic control unit is configured to update and store at least one value for the efficiency parameter during the adaptation routine or to update and store at least one value for an auxiliary parameter during the adaptation routine, with which the efficiency parameter can be calculated.

3. The adjustment system according to claim 1, wherein the electronic control unit is configured to calculate a value for a coefficient of friction when carrying out the adaptation routine.

4. The adjustment system according to claim 2, wherein the electronic control unit is configured to calculate a value for a coefficient of friction when carrying out the adaptation routine, wherein the electronic control unit is configured to store the calculated value for the coefficient of friction as an updated value for the auxiliary parameter.

5. An adjustment system, comprising an adjustment element adjustable along two mutually opposite adjustment directions, an adjustment drive with at least one electric drive motor for generating a drive force for the adjustment of the adjustment element, and an electronic control unit for controlling the drive motor by specifying a motor current for generating the drive force in a height required for an adjustment operation, wherein via the electronic control unit at least one control variable is specified for setting the motor current, wherein the adjustment drive comprises a drive element coupled with the adjustment element for transmitting the drive force, which is adjustable in two mutually opposite driving directions, and the electronic control unit in an adaptation routine for updating the control variable is configured to initially adjust the drive element in a first phase in a first driving direction via the drive motor against a restoring force and subsequently, in a second phase, permit an adjustment of the drive element in the opposite second driving direction by lowering the motor current by action of the restoring force, and from at least two values for the motor current detected during the first phase and at least two values for the motor current detected during the second phase to form two difference values for updating the control variable.

6. The adjustment system according to claim 1, wherein the adjustment drive comprises a drive element coupled with the adjustment element for transmitting the drive force, which is adjustable in two mutually opposite driving directions, and the electronic control unit in an adaptation routine for updating the control variable is configured to initially adjust the drive element in a first phase in a first driving direction via the drive motor against a restoring force and subsequently, in a second phase, permit an adjustment of the drive element in the opposite second driving direction by lowering the motor current by action of the restoring force, and from at least two values for the motor current detected during the first phase and at least two values for the motor current detected during the second phase to form two difference values for updating the control variable, wherein the electronic control unit is configured to update a value for the efficiency parameter or a value for an auxiliary parameter, with which the efficiency parameter can be calculated, by utilizing the at least two difference values.

7. The adjustment system according to claim 5, wherein the electronic control unit is configured to detect the values for the motor current in the second phase for identical positions of the drive element, at which the values for the motor current were detected in the first phase.

8. The adjustment system according to claim 3, wherein the adjustment drive comprises a drive element coupled with the adjustment element for transmitting the drive force, which is adjustable in two mutually opposite driving directions, and the electronic control unit in an adaptation routine for updating the control variable is configured to initially adjust the drive element in a first phase in a first driving direction via the drive motor against a restoring force and subsequently, in a second phase, permit an adjustment of the drive element in the opposite second driving direction by lowering the motor current by action of the restoring force, and from at least two values for the motor current detected during the first phase and at least two values for the motor current detected during the second phase to form two difference values for updating the control variable, wherein the electronic control unit implements a search algorithm with which for a function dependent on the coefficient of friction and comprising the two difference values for the motor current a value for the coefficient of friction can be calculated, which is associated to a zero of the function, and the electronic control unit is configured to utilize the value for the coefficient of friction, which is associated to the zero, for specifying the updated efficiency parameter.

9. The adjustment system according to claim 1, wherein the electronic control unit furthermore is configured to determine and store an updated value for an idle current of the drive motor by means of the adaptation routine.

10. The adjustment system according to claim 9, wherein at least one of the electronic control unit is configured to use the updated value for the idle current for specifying the motor current during an adjustment operation, and the electronic control unit is configured to calculate the updated value for the idle current on the basis of the updated value for the efficiency parameter.

11. (canceled)

12. The adjustment system according to claim 1, wherein for the different adjustment directions of the adjustment element at least two different efficiency parameters are provided in the electronic control unit, so that the at least one control variable can be specified differently in dependence on the adjustment direction of the adjustment element.

13. The adjustment system according to claim 1, wherein the electronic control unit is configured to carry out the adaptation routine with an immovably fixed adjustment element or by adjusting the adjustment element.

14. The adjustment system according to claim 1, wherein the electronic control unit is configured to vary a value for the used torque constant in dependence on a measured temperature value for an adjustment of the adjustment element outside of the adaptation routine.

15. The adjustment system according to claim 1, wherein the electronic control unit is configured to vary a value for an idle current in dependence on a measured temperature value for an adjustment of the adjustment element outside of the adaptation routine.

16. The adjustment system according to claim 1, wherein the electronic control unit is configured to determine a value for the efficiency parameter on the basis of at least one value for an auxiliary parameter, which varies in dependence on a measured temperature value, for an adjustment of the adjustment element outside of the adaptation routine.

17. The adjustment system according to claim 1, wherein the electronic control unit is configured to only carry out the adaptation routine when the presence of at least two of the following adaptation criteria is electronically detected: the adjustment element is in a locked adjustment position at the vehicle, the execution of a previous adaptation routine dates back longer than at least one of a predefined time period and number of adjustment cycles, in the environment of the vehicle no valid authentication element of a user of the vehicle is present, by means of which unlocking of the vehicle can be triggered, in a vehicle interior of the vehicle no person is present, a signal for putting the electronic control unit into a sleep mode has been generated.

18. The adjustment system according to claim 1, wherein the adjustment element is a door of a vehicle.

19. The adjustment system according to claim 1, wherein the height of the motor current for an adjustment operation depends on an adjusting force manually acting on the adjustment element and the motor current to be specified can be determined via the electronic control unit in dependence on the required height of the drive force.

20. A method for operating an adjustment system for a vehicle, which comprises an adjustment element adjustable along two mutually opposite adjustment directions, and an adjustment drive with at least one electric drive motor for generating a drive force for the adjustment of the adjustment element, wherein for controlling the drive motor a motor current is specified for generating the drive force in a height required for an adjustment operation, and wherein at least one control variable is specified for setting the motor current, wherein at least one of a) the control variable is based on a torque constant for the electric drive motor and an efficiency parameter characterizing the efficiency of the adjustment drive, and in operation of the adjustment system an adaptation routine is carried out for updating the efficiency parameter and b) the adjustment drive comprises a drive element coupled with the adjustment element for transmitting the drive force, which is adjustable in two mutually opposite driving directions, and in an adaptation routine for updating the control variable the drive element initially is adjusted in a first phase in a first driving direction via the drive motor against a restoring force and subsequently, in a second phase, an adjustment of the drive element in the opposite second driving direction is permitted by lowering the motor current by action of the restoring force, and from at least two values for the motor current detected during the first phase and at least two values for the motor current detected during the second phase two difference values are formed for updating the control variable.

21. (canceled)

22. The method according to claim 20, wherein a value for the torque constant is determined in a calibration routine before a first operation of the adjustment system and by utilizing a force measurement on the adjustment element adjusted by means of the adjustment drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The attached Figures by way of example illustrate possible embodiments of the proposed solution.

[0044] FIG. 1A schematically shows a vehicle parked on a slope by representing forces to be applied by a user and on the part of the adjustment drive on opening of a side door of the vehicle.

[0045] FIG. 1B in a view corresponding with FIG. 1A shows the forces to be applied by a user and on the part of the adjustment drive on closing of the side door.

[0046] FIG. 2 in a perspective view shows an embodiment of an adjustment drive for the adjustment of a side door in the vehicle of FIGS. 1A and 1B.

[0047] FIG. 3 shows the course of a motor current for a drive motor of the adjustment drive of FIG. 2 on starting of the drive motor by emphasizing an idle current and by plotting the values for the motor current via positions of a drive element driven by the drive motor, which are detected by means of one or more Hall sensors.

[0048] FIG. 4 shows a course of the motor current via positions of the drive element driven by the drive motor, which are detected by means of one or more Hall sensors, during the execution of an embodiment of a proposed adaptation routine.

[0049] FIG. 5 shows a motor current-time-course on execution of the adaptation routine according to FIG. 4.

[0050] FIG. 6 shows the motor current-time-course of FIG. 5 by emphasizing further measurement times for the detection of a motor current in a first and a second phase of the adaptation routine.

[0051] FIG. 7 shows a schematic overview representation of the mode of operation of an embodiment of a proposed adjustment system by representing the parameters and control variables to be updated by means of an adaptation routine.

[0052] FIG. 8 shows a flow diagram for an embodiment of a proposed operating method.

DETAILED DESCRIPTION

[0053] FIGS. 1A and 1B by way of example show a vehicle F parked on a slope, in which an embodiment of a proposed adjustment system is provided in order to adjust a lateral vehicle door T by power assistance. With the adjustment system a servo drive for the adjustment of the lateral vehicle door T here is provided. The objective here is that a user adjusts the vehicle door T by manual application of an adjusting force, but the adjusting force to be applied manually here does not exceed a predefined measure so that the adjustment of the vehicle door T is perceived as smooth and comfortable for a user, although the weight of the vehicle door T is comparatively large. Typically, the adjusting force to be applied in the opening direction generally and hence also with the vehicle F parked on a horizontal plane is at least slightly larger than in the closing direction. This difference again is increased considerably when the vehicle F is parked on a slope like in FIGS. 1A and 1B and the vehicle door T to be opened is to be opened in the direction of the slope.

[0054] As is illustrated in FIGS. 1A and 1B with reference to the schematic representation of the forces for a respective adjusting movement of the vehicle door T, the objective is to provide a drive force F.sub.drive via at least one drive motor of the adjustment system, so that independently of the adjustment direction of the vehicle door T an adjusting force F.sub.open or F.sub.close to be applied manually always is equally large. For opening the vehicle door T, a combination of the manually applied adjusting force F.sub.open, which should lie in the range of 5 N. and the motor-generated drive force F.sub.drive then must be greater than a weight force F.sub.door acting on the vehicle door T, via which the vehicle door T is loaded in the direction of a closed position. For closing the opened vehicle door T the drive force F.sub.drive applied by a motor ultimately must counteract the adjusting movement of the vehicle door T in the closing direction, as otherwise the vehicle door T would be accelerated too much due to the weight force F.sub.door. Here, the drive force F.sub.drive applied by a motor consequently must be greater than the weight force F.sub.door, namely just by the amount of the adjusting force F.sub.close to be applied manually, which here again should lie in the range of 5 N.

[0055] In practice, the challenge now is to set the drive force F.sub.drive to be applied in an electronically controlled way via a motor current at the at least one drive motor such that the drive force F.sub.open or F.sub.close to be applied manually is set so as to be comfortable for the user. The respective force F.sub.open or F.sub.close to be applied manually hence should be regulated electronically in such a way that the vehicle door T can comfortably be adjusted independently of the adjustment direction and feels light.

[0056] In principle, a corresponding control of the drive force F.sub.drive to be applied by a motor is easily manageable and easily possible especially due to the corresponding design and possibly calibration of the adjustment system in a delivery state of the vehicle F. Throughout the service life, however, characteristic variables of the adjustment system and in particular of the motor drive possibly can change significantly, so that originally set and possibly even calibrated characteristic variables, which determine the motor current for the drive motor and hence the generated drive force, no longer are applicable. Hence, in the worst case undesired adjusting movements of the vehicle door T, impaired movement sequences during the adjustment of the vehicle door T and/or even malfunctions and abortions during the adjustment of the vehicle door T can occur. For example, changes that significantly have occurred due to wear at relevant characteristic variables possibly can lead to the fact that during an adjustment of the vehicle door T clamping cases no longer are reliably detected electronically.

[0057] Hence, there is a need for a possibility to detect possible changes in relevant characteristic variables also throughout the service life of the adjustment system and in response thereto take any measures so that the electronically controlled generation of a drive force applied by a motor still is effected reliably and the adjusting movement of the vehicle door T still can be monitored reliably. This is remedied by the proposed solution, for which possible embodiments are explained with reference to the further FIGS. 2 to 8.

[0058] FIG. 2 here initially shows an embodiment of a mechatronic adjustment drive A, as it can be employed for the adjustment of the vehicle door T at the vehicle F of FIGS. 1A and 1B. The drive A includes an electric drive motor 3 with an integrated motor brake 4 (for example in the form of a hysteresis brake). The drive motor 3 is coupled with the spindle drive 2 via a transmission 20, in order to transmit a motor-generated drive force and a resulting drive torque to the vehicle door T. The current position of the vehicle door T can be inferred via one or more Hall sensors, which on rotation of a drive element driven by the drive motor 3 generate discrete sensor signals. A corresponding drive element for example can be a motor shaft of the drive motor 3. The control of the drive motor 3 and in particular also an evaluation of generated sensor signals of a Hall sensor (or signals of an alternatively configured position sensor) are performed by an electronic control unit in the form of a controller 5.

[0059] The controller 5 integrates a processor-supported, in particular microcontroller-based evaluation and control logic in order to control the adjustment of the vehicle door T. and in particular by specifying the motor current for the drive motor 3 control the drive force F.sub.drive in a height appropriate for the respective operating situation. The evaluation and control logic implemented via the controller 5 is based on the fact that the drive force F.sub.drive to be transmitted to the vehicle door T via the drive motor 3 not only depends on the motor current to the drive motor 3 alone, but also in particular on an idle current I.sub.0 of the drive motor, a torque constant kT, a (total) gear ratio i of the transmission 20 and the spindle drive 2, and an efficiency parameter eff of the adjustment drive A characterizing the efficiency. Thus, it applies:

[00001]$\begin{array}{cc}{F}_{\mathrm{drive}}=\left(I_{\mathrm{motor}}-I_0\right).Math.\mathrm{kT}.Math.i.Math.\mathrm{eff}& \left(\mathrm{Equation}1\right)\end{array}$

[0060] Experience here shows that the efficiency eff of the adjustment drive A is different, depending on whether a driving or braking drive force F.sub.drive must be provided via the adjustment drive A, i.e. for example in dependence on whether the vehicle door T is opened or closed corresponding to FIGS. 1A and 1B. Thus, for providing the drive force a distinction can be made between a driving or supporting drive force F.sub.support and a braking drive force F.sub.brake. For the same, another efficiency eff.sub.support or eff.sub.brake also is each relevant with the corresponding motor current value I.sub.support or I.sub.brake:

[00002]$\begin{array}{cc}{F}_{\mathrm{support}}=\left(I_{\mathrm{support}}-I_0\right).Math.\mathrm{kT}.Math.{\mathrm{eff}}_{\mathrm{support}}.Math.i=\left(I_{\mathrm{sipport}}-I_0\right).Math.{\mathrm{kTeff}}_{\mathrm{support}}.Math.i& \left(\mathrm{Equation}2.1\right)\end{array}$$\begin{array}{cc}{F}_{\mathrm{support}}=\left(I_{\mathrm{brake}}-I_0\right).Math.\frac{\mathrm{kT}}{{\mathrm{eff}}_{\mathrm{brake}}}.Math.i=\left(I_{\mathrm{brake}}-I_0\right).Math.{\mathrm{kTeff}}_{\mathrm{brake}}.Math.i& \left(\mathrm{Equation}2.2\right)\end{array}$

[0061] The torque constant kT and the respective efficiency parameter eff.sub.support or eff.sub.brake here can be combined to obtain a control variable kTeff.sub.support or kTeff.sub.brake, which then is relevant for specifying the height of the motor current I.sub.support Or I.sub.brake in dependence on a required height of the drive force F.sub.support Or F.sub.brake.

[0062] An embodiment of the proposed solution now refers to the fact that the control variable kTeff.sub.support and/or kTeff.sub.brake is specified separately by values for the torque constant KT and the efficiency parameter eff.sub.support or eff.sub.brake, and the efficiency parameter eff.sub.support or eff.sub.brake is updated throughout the service life of the adjustment system and hence in operation of the adjustment system in connection with an adaptation routine controlled with the controller 5. Here, it was recognized that the torque constant kT of an adjustment drive A at best changes slightly throughout the service life. Here, merely a temperature dependence of the torque constant kT should possibly be observed. What is of decisive importance, on the other hand, is a separate observation of the efficiency parameter eff.sub.support or eff.sub.brake throughout the service life. Here again, the particular challenge consists in that in operation of the adjustment system and hence in the state of the adjustment system mounted in the vehicle F a calibration of relevant characteristic variables no longer is possible.

[0063] In the present case, not only a change of the efficiency parameter eff.sub.support or eff.sub.brake can be taken into account by the controller 5, but also a change of the idle current I.sub.0 occurring throughout the service life, which likewise is included in the equations 2.1 and 2.2 as a characteristic variable.

[0064] The significance of the idle current and its variability here is illustrated in detail by way of example in the diagram of FIG. 3. Here, a course of the motor current is shown via position signals of a motor shaft or a rotor of the drive motor 3 detected by means of one or more Hall sensors. From a resting, tensioned state of the adjustment system a comparatively large motor current initially is required in order to put the respective drive element into movement. The motor current then passes through a minimum, before a movement of the drive element becomes measurable with a further rise of the motor current. The respective minimum characterizes the idle current I.sub.0, which in FIG. 3 is shown at the points 1 and 1*. A possible change of the idle current I.sub.0 from a value at the point 1 to a value at the point 1* for example can be detected via an approximation of the idle current I.sub.0 of the drive motor 3 during an adaptation routine or via one or more adjustment cycles and hence adjustment operations with an adjustment of the vehicle door T triggered by a user. However, a possible change of the efficiency and hence of the efficiency parameter eff.sub.support or eff.sub.brake cannot be inferred therefrom.

[0065] Corresponding to an embodiment of the proposed solution, which is illustrated with reference to FIG. 4, it can therefor be provided to subject the adjustment drive A to two load situations during an adaptation routine and to determine a currently valid value for the efficiency parameters eff.sub.support and eff.sub.brake from values for the motor current detected at specific times.

[0066] During an adaptation routine, the controller 5 initially actuates the controller 5 in a first phase to perform an adjustment against a restoring force counteracting the adjustment, which for example results from the weight force acting on the vehicle door T and from tensile forces within the system. The motor-driven drive element of the adjustment drive A here is adjusted along a first driving direction. In the diagram of FIG. 4, this corresponds to the course of the motor current from a point 2 to a point 3. At the point 3, the motor current is lowered for a subsequent second phase to such an extent that by action of the applied restoring force a return of the drive element in an opposite second driving direction is effected. This is illustrated with reference to the points 4 and 5 in the diagram of FIG. 4.

[0067] At the points 2, 3, 4 and 5 of the diagram of FIG. 4 the respective values for the motor current are detected and differences I.sub.support and I.sub.brake are formed therefrom, which are utilized for updating the efficiency parameter eff.sub.support and eff.sub.brake. Here, use is made of the fact that in dependence on a currently valid coefficient of friction a function f() can be found for the cooperating components within the adjustment drive A, in particular within the transmission 20 and the spindle drive 2, for which the following must apply from the calculated difference values I.sub.support and I.sub.brake:

[00003]$\begin{array}{cc}f\left(\right)=I_{\mathrm{support}}.Math.f_{12}\left(\right)-I_{\mathrm{brake}}=0& \left(\mathrm{Equation}3\right)\end{array}$

[0068] A function f.sub.12 contained therein, which is dependent on the coefficient of friction , in particular can contain geometrically related characteristic variables to be regarded as invariable throughout the service life of the adjustment system, so that the function f() merely is dependent on the coefficient of friction , and for the solution of equation 3 shown above an appropriate value for the coefficient of friction valid in the adjustment drive A merely must be found analytically or iteratively.

[0069] On the basis of the coefficient of friction then determined, the efficiency parameters eff.sub.support and eff.sub.brake in turn can be inferred. The magnitudes of these efficiency parameters eff.sub.support and eff.sub.brake likewise are dependent on the coefficient of friction in a specific way, and thus it applies:

[00004]$\begin{array}{cc}{\mathrm{eff}}_{\mathrm{support}}=f_1\left(\right)& \left(\mathrm{Equation}4.1\right)\end{array}$$\mathrm{and}$$\begin{array}{cc}{\mathrm{eff}}_{\mathrm{brake}}=f_2\left(\right).& \left(\mathrm{Equation}4.1\right)\end{array}$

[0070] With a known value for the (current) coefficient of friction , a current value for the adjustment drive-specific efficiency parameter eff.sub.support and eff.sub.brakerelevant depending on the adjustment direction or operating situationcan thus be calculated and from the same a control variable kTeff.sub.support or kTeff.sub.brake can in turn be calculated.

[0071] On the basis of the mathematical relationships considered above and in an algorithm of the controller 5 an efficiency within the adjustment drive A consequently can be inferred without any force measurements to be provided in operation of the adjustment system, and hence an updated value for efficiency parameters eff.sub.support and eff.sub.brake can also be used. Here, a value for an efficiency parameter eff.sub.support or eff.sub.brake updated in an adaptation routine can be stored as an updated and stored value or alternatively merely an updated value for the coefficient of friction can be stored, from which on the basis of equations 4.1 and 4.2 a required value for the efficiency parameter eff.sub.support or eff.sub.brake can then be determined when necessary.

[0072] A corresponding adaptation routine for example is performed by the controller 5 at defined times, for example during an adjustment of the vehicle door T, in which the vehicle door T initially is adjusted in the one and then in the other adjustment direction. Alternatively a corresponding adaptation routine can also be carried out with a closed and in particular locked vehicle door T, as for the two load situations to be considered an adjustment of the vehicle door T itself ultimately is not absolutely necessary, but merely an adjustment of the drive-side drive element coupled therewith. i.e. for example of the motor shaft or rotor of the drive motor 3.

[0073] For example, the diagram of FIG. 5 also by way of example shows a course of the motor current over time for an adaptation routine carried out with a closed and locked vehicle door T. In particular measured values I.sub.2 and I.sub.3 are detected for the linearly rising motor current with a motor-driven adjustment of the drive element in the driving direction and for this purpose the respective positions of the drive element also are stored, for example via detected signals of one or more Hall sensors. With a backward adjustment of the drive element due to a linearly decreasing motor current, measurement values for the motor current again are detected at exactly the same positions of the drive element, for example values I.sub.4 and I.sub.5 (shown in FIG. 5, but not designated). From value pairs for the first phase with an adjustment of the drive element in the one driving direction and from value pairs for the second phase for a backward adjustment of the drive element in an opposite driving direction the above-mentioned values I.sub.support and I.sub.brake then are calculated.

[0074] On traversal in the opening direction from a braced state, the drive motor 3 initially starts, goes through the system clearance and finally operates against the door and connection rigidity and against a closing bracket of a door lock. After the starting current has decayed, analogously to the representation of FIG. 3, an updated value for the idle current I.sub.0 can be determinable when going through the system clearance. Subsequently, when going through the rising load the two (first) current values I.sub.2 and I.sub.3 can be detected at the two Hall positions to be stored. Thereafter, the motor current slowly is reduced until the drive element moves in the closing direction. At the Hall positions previously stored (second) current values for the motor current again are detected, from which the difference current values I.sub.support and I.sub.brake are calculated.

[0075] In principle, the adaptation routine, which is illustrated with reference to the diagram of FIG. 2, can be triggered automatically on the part of the controller 5 in response to the presence of different adaptation criteria. Here, for example, it is not only relevant that the execution of a previous adaptation routine dates back longer than a predefined time period and/or number of adjustment cycles and hence an updating of the efficiency parameter eff or of the adjustment direction-dependent variants in the form of the efficiency parameters eff.sub.support and eff.sub.brake appears to be expedient. Rather, it can also play a role here that the execution of a corresponding adaptation routine is carried out as unnoticed as possible for a user of the vehicle and hence in a non-disturbing way. For example, the execution of the adaptation routine in particular can depend on that it is detected that [0076] the vehicle door T is in a locked and closed adjustment position at the vehicle F, [0077] in the environment of the vehicle F no valid authentication element is present, for example in the form of a key transponder (which suggests that the vehicle F is permanently parked), [0078] no person is present in a vehicle interior of the vehicle F, and [0079] the controller 5 and hence the entire adjustment drive A is to be put into a sleep mode in order to save electricity.

[0080] Instead of a discrete measurement of merely four current values, a possible development corresponding to FIG. 6 also for example can provide that both in the first phase and in the second phase of the adaptation routine a value for the motor current is detected for each position of the drive element detected by means of sensors. From the then existing plurality of detected motor current values a gradient can each be determined, which is included in equation 3 for I.sub.support Or I.sub.brake.

[0081] In principle, an embodiment of the proposed solution also can provide that by means of measurement values detected in connection with the execution of the adaptation routine for an updating of the efficiency parameters eff.sub.support and eff.sub.brake an updating also is effected for a value of the idle current I.sub.0, i.e. the same is not (only) determined by going through the system clearance, but is calculated. It can thus be shown that the following applies for the idle current:

[00005]$\begin{array}{cc}{I}_0=\frac{I_{\mathrm{support}}.Math.{\mathrm{eff}}_{\mathrm{support}}-\frac{I_{\mathrm{brake}}}{{\mathrm{eff}}_{\mathrm{brake}}}}{\frac{1}{{\mathrm{eff}}_{\mathrm{brake}}}-{\mathrm{eff}}_{\mathrm{support}}}.& \left(\mathrm{Equation}5\right)\end{array}$

[0082] An updated value for the idle current I.sub.0 thus can be stored in a memory, in particular in a memory of the controller 5, after carrying out an adaptation routine. It here can also be taken into account that the idle current I.sub.0 is temperature dependent. Thus, different values for the idle current I.sub.0 can be stored in the memory in dependence on different temperatures. Here, for example, especially a measured temperature at the adjustment drive A and in particular in the region of the transmission 20 then is relevant. A current or updated value for the idle current I.sub.0 thus is also stored for example for an appropriate temperature value or temperature range. Several base or default values in the delivery state of the adjustment drive A can also be stored in a form to be overwritten. This in particular includes the possibility to store corresponding values for the idle current I.sub.0 in a table of the form shown below:

TABLE-US-00001 TABLE 1 Temp. ( C.) 30 20 10 0 20 40 60 80 I.sub.0, max 3.2 . . . . . . . . . 2.1 . . . . . . I.sub.0 2.5 . . . . . . . . . 1.83 . . . . . . I.sub.0, min 2.1 . . . . . . . . . 1.45 . . . . . . I.sub.0, default 2.45 . . . . . . . . . 1.74 . . . . . .

[0083] Alternatively or in addition, corresponding values for the coefficient of friction can be stored in a memory, in particular in tabular form corresponding to the Table shown below:

TABLE-US-00002 TABLE 2 Temp. ( C.) 30 20 10 0 20 40 60 80 .sub.max 0.150 . . . . . . . . . 0.090 . . . . . . 0.110 0.125 . . . . . . . . . 0.072 . . . . . . 0.082 .sub.min 0.090 . . . . . . . . . 0.050 . . . . . . 0.050 .sub.default 0.120 . . . . . . . . . 0.065 . . . . . . 0.071

[0084] For a possible updating of values of in such a table when carrying out an adaptation routine it can then also be verifiable whether a calculated updateable value for the coefficient of friction lies within predefined minimum and maximum values .sub.max and .sub.min and hence is plausible. Analogously, a corresponding plausibility check with reference to minimum and maximum values I.sub.0,max and I.sub.0,min can also be implemented for a value to be newly stored for the idle current I.sub.0.

[0085] A value for the control variable kTeff.sub.support or kTeff.sub.brake to be utilized for one or more adjustment operations or one or more adjustment cycles can be specified in the way explained above from characteristic variables remaining up-to-date throughout the service life of the adjustment system and here in particular values for the torque constant kT and the adjustment direction-dependent efficiency parameters eff.sub.support and eff.sub.brake. An additional adaptation or compensation at changed temperatures in the environment of the adjustment drive A and in particular in the transmission 20 here can also easily be realized via a temperature compensation with reference to the stored values for the idle current I.sub.0 and the coefficient of friction . For example, after defined times, for example every 2, 5 or 10 seconds or after detection of a temperature changed by a defined threshold value, a new determination of corresponding values for the torque constant kT can be effected on the part of the controller to below the efficiency parameter eff.sub.support and/or eff.sub.brake.

[0086] On this basis. FIG. 7 illustrates a possible fundamental procedure during the calibration of the adjustment drive A and an automated adaptation of relevant characteristic variables integrated into the adjustment drive A. It is provided, for example, that in a delivery state of the adjustment drive A and hence at the end of a manufacturing process for the adjustment drive A (so-called end-of-line, briefly EOL) values are measured and hence calibrated for the control variable kTeff. In connection with a corresponding EOL calibration, individual and hence specific values for the torque constant kT and the efficiency parameter eff or its adjustment direction-dependent variants eff.sub.support and eff.sub.brake then are present in the delivery state of the adjustment drive A for the respective adjustment drive A. Via the adaptation routine implemented on the part of the controller, repeatedly updated values for kTeff can then be utilized at the running time and hence in operation of the adjustment drive A throughout the service life, for example due to the above-described updating of values for the coefficient of friction and the idle current I.sub.0 on the basis of measurement values detected during an adaptation routine (which can do without a direct force measurement). On the one hand, a temperature-compensated value for the torque constant kT thereby is provided as KT_adapt and, finally on the basis of updated values for the coefficient of friction and possibly the idle current I.sub.0, an updated value kTeff_adapt for the control variable for specifying the motor current.

[0087] The flow diagram of FIG. 8 by way of example additionally illustrates the different steps to be carried out for an embodiment of a proposed operating method for an adjustment system corresponding to the previous explanations.

[0088] When the provided adaptation criteria are fulfilled in a first step 801, the controller 5 on the side of the adjustment drive automatically triggers the execution of an adaptation routine. The adaptation routine consequently is started in a step 802, for example with the vehicle door T completely closed and locked. In connection with the adaptation routine difference current values I.sub.support and I.sub.brake are determined. After a corresponding step 803, a current value for the coefficient of friction of the adjustment drive A then is determined therefrom via an algorithm of the basis of equation 3 implemented in the controller 5 (step 804 of FIG. 8). The determination of the updated value for the coefficient of friction includes its storage. In an optional step 805, a current or updated value for one or more efficiency parameters eff.sub.support, eff.sub.brake can also be determined already from the current value of the coefficient of friction and be stored. In particular on the basis of the difference current values I.sub.support or I.sub.brake determined in step 803, an updated value for the idle current I.sub.0 can be determined in a step 806 by utilizing correspondingly calculated values for the efficiency parameters eff.sub.support, eff.sub.brake. At the end of the adaptation routine carried out, an updated value for the control variable(s) kTeff.sub.support and kTeff.sub.brake then is determined in a step 807 from the newly calculated values.

[0089] With the embodiments explained above, a constant and foreseeable performance of the adjustment drive A can be ensured without providing any additional sensor system and it can be guaranteed throughout the service life that a control of the drive motor 3 and hence an adjusting movement of an adjustment element, for example the vehicle door T, also is reliably effected in the case of utilization-specific and wear-related changes of relevant characteristic variables and in particular neither does impair the detection of a clamping case. The proposed solution of course is not limited to the exemplary embodiments explained above, which merely are to be understood by way of example.

TABLE-US-00003 List of reference numerals 2 spindle drive 20 transmission 3 drive motor 4 motor brake 5 controller (electronic control unit) A adjustment drive F vehicle T vehicle door (adjustment element)