Control member with electronic evaluation of the haptic feedback

An assembly consisting of a control member which comprises a carrier, an operating part movably supported on the carrier, an electromagnetic actuator comprising an armature and a coil for driving the operating part movingly relative to the carrier is provided. The assembly further comprises an electronic control system connected in an electrically conductive manner with the electromagnetic actuator for applying a control voltage to the electromagnetic actuator for a predetermined control period in a control step in order to generate a haptic feedback; a measuring circuit connected in an electrically conductive manner to the electromagnetic actuator for measuring a current present at the electromagnetic actor and for generating a measuring signal proportional thereto; and an evaluation unit connected in an electrically conductive manner at least to the measuring circuit and designed, in a measuring step offset in time relative to the control step, to apply a measuring voltage to the electromagnetic actuator by the electronic control system for a predetermined test period shorter than the control period, in order to measure by the measuring circuit the current which arises at the electromagnetic actuator as the test period elapses due to the application of the measuring voltage and to generate a measuring signal proportional thereto, and in order to obtain a characteristic value of the actuator based on the measuring signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims foreign priority of German application Serial Numbers DE 10 2015 119 615.8 filed on Nov. 13, 2015 and DE 10 2016 103 766.4 filed on Mar. 2, 2016, the entireties of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a control member comprising: a carrier, an operating part movably supported on the carrier, an electromagnetic actuator comprising an armature and a coil for driving the operating part movingly relative to the carrier, the assembly further comprising an electronic control system connected in an electrically conductive manner with the electromagnetic actuator for applying a control voltage to the electromagnetic actuator for a predetermined control period in a control step in order to generate a haptic feedback.

Description of the Prior Art

Regularly, there is a problem with such control members with electromagnetic actuators in that the generated haptic feedback, i.e. the strength of the impact or vibration excitation, varies to a great extent depending on the mechanical tolerances, in particular the tolerances relating to the relative orientation of the armature and the coil, possibly of the iron core and the armature, but also depending on the temperature and air humidity. This is unwanted. Therefore, there is a demand for a test method and an assembly for carrying out this method for detecting such tolerances on the operating part without any measurement, if possible, in order to carry out a mechanical readjustment of the relative arrangement if necessary. Furthermore, there is a demand for a control method and a corresponding assembly, which are capable of taking account of changes in the haptic feedback or compensate them at least partially, which are the result, for example, of mechanical changes of the actuator occurring during operation or due to the change of external influences, such as temperature and air humidity. These changes may be the result of, for example, excessive heating or wear in the mounting or bearing arrangement of the operating part. It was found that, in particular, electromagnetic actuators with a flat-armature design are affected by this problem because their advantageously great driving force varies greatly depending on the minimum distance (=resting distance) between the armature and the coil. At least during operation, manually measuring this distance is difficult.

SUMMARY OF THE PRESENT INVENTION

Against this background, the object on which the invention is based lies in providing an assembly which comprises, among other things, a control member and in which the haptic feedback associated with the control member and generated by an actuator is improved and, in particular, can be determined with respect to its action, so that it can be examined, if necessary, and adapted if required.

This object is achieved by an assembly according to claim1. Advantageous embodiments are in each case the subject matter of the dependent claims. Equally advantageous methods are in each case the subject matter of the independent claims. It must be noted that the features cited individually in the claims can be combined with each other in any technologically meaningful manner and represent other embodiments of the invention. The description, in particular in connection with the figures, additionally characterizes and specifies the invention.

The invention relates to an assembly including a control member, an electronic control system connected to the electromagnetic actuator in an electrically conductive manner, a measuring circuit connected to the electromagnetic actuator in an electrically conductive manner, and an evaluation unit connected in an electrically conductive manner at least to the measuring circuit. The control member has a carrier, an operating part movably supported on the carrier, and an electromagnetic actuator. The actuator comprises an armature and a coil for driving the operating part movingly relative to the carrier. According to a preferred embodiment, the actuator is counteracted by returning means which cause an elastic return of the operating part into its initial position, hereinafter referred to as the rest position.

The electronic control system provided according to the invention is provided for applying a control voltage to the electromagnetic actuator for a predetermined control period in a control step in order to generate a haptic feedback. The measuring circuit is provided for measuring a current present at the electromagnetic actuator and for generating a measuring signal proportional thereto. The evaluation unit provided according to the invention is designed, in a measuring step offset in time relative to the control step, to apply a measuring voltage to the electromagnetic actuator by means of the electronic control system for a predetermined test period shorter than the control period, in order to measure the current which arises at the electromagnetic actuator as the test period elapses due to the application of the measuring voltage, and to generate a measuring signal proportional thereto, and in order to obtain a characteristic value of the actuator based on the measuring signal. This makes a check of the function of the assembly according to the invention possible.

Preferably, the characteristic value relates to an inductance of the actuator, for example at the point in time at which the test period elapses, more preferably its inductance in the rest position. The term inductance in the rest position means the inductance value of the actuator that results when the operating part, and thus the actuator, just about remain in the rest state, for example due to inertia and friction effects, and before their departure from the rest position is caused. The inductance in the rest position is estimated, for example, based on the current resulting from the application of the measuring voltage as the test period elapses.

Preferably, the test period is selected in such a way that the saturation current is not reached by the actuator or its coil. The saturation current is understood to be the current at which a linear, for example (exponential), rise of the current during the application of the measuring voltage, which is substantially determined by the inductance, ends and is now substantially and over the further course determined predominantly by the ohmic resistance and the size of the voltage present.

Preferably, the test period and the measuring voltage are selected in such a way that the acceleration of the non-operated operating part caused in the measuring step is less than 2.5 g, preferably less than 1.5 g, more preferably less than 0.5 g. A non-operated operating part is understood to be a “freely movable” operating part, i.e. an operating part that is not subjected to load due to contact with or operation by an input means, such as the finger of an operator.

According to a preferred variation, the test period is less than 5.0 ms, more preferably less than 2.0 ms, still more preferably 1.0 ms, most preferably 0.5 ms.

For example, the maximum absolute value of the measuring voltage corresponds to the maximum absolute value of the control voltage. Preferably, the maximum absolute value of the measuring voltage is less than the maximum absolute value of the control voltage.

The measuring voltage and/or the control voltage are preferably configured as a square-wave signal; preferably, both are pulse width modulated.

According to a preferred embodiment, the evaluation unit and the electronic control system are connected in an electrically conductive manner and are designed to vary the control period and/or the control voltage depending on the characteristic value obtained in the measuring step. This enables a correction of the haptic feedback, and in particular a compensation of changes relating to the haptic feedback which occur during operation.

Preferably, the coil and the armature are disposed in such a way that the armature is disposed outside the volume defined by the coil in all positions and is preferably configured as a flat armature. The term flat armature in the sense of the invention is to be interpreted broadly and is supposed to relate to such electromagnetic actuators in which the armature on principle does not enter the coil interior of the coil generating the magnetic field. Particularly with regard to its shape, the armature is otherwise supposed to be configured in any way. For example, a ferromagnetic core, for example an iron core, is further disposed in the interior of the coil, as a field-concentrating or field-directing measure.

According to a preferred embodiment, at least the electrically conductive connection between the electromagnetic actuator and the evaluation unit and/or between the electromagnetic actuator and/or the measuring circuit is configured in a detachable manner. If required, for example in the event of maintenance, the control member can thus be examined.

In a preferred embodiment with a simple design, the measuring circuit is configured as a voltage divider, and the current is determined based on a voltage present at the voltage divider. For example, the characteristic value of the actuator is determined by means of an analog-digital converter from the voltage present at the voltage divider at the point in time at which the test period elapses.

Preferably, the electronic control system and/or the electronic evaluation system are attached to the control member in order thus to form a fixed component of the assembly according to the invention.

The invention further relates to a test method. This test method includes a step of providing a control member comprising a carrier, an operating part movably supported on the carrier, an electromagnetic actuator comprising an armature and a coil for driving the operating part movingly relative to the carrier.

In another subsequent, simultaneous or preceding providing step, an electronic control system connected in an electrically conductive manner to the electromagnetic actuator for applying a measuring voltage to the actuator is provided. In another subsequent, simultaneous or preceding providing step, a measuring circuit connected in an electrically conductive manner to the electromagnetic actuator for measuring a current present at the electromagnetic actor and for generating a measuring signal proportional thereto is furthermore provided. In another subsequent, simultaneous or preceding providing step, an evaluation unit connected in an electrically conductive manner at least to the measuring circuit is provided.

In a step subsequent to the above-described providing steps, a measuring voltage is applied to the electromagnetic actuator by means of the electronic control system for a predetermined test period. In a simultaneous measuring step, the current which arises at the electromagnetic actuator as the test period elapses due to the application of the measuring voltage is measured and a measuring signal proportional to the measured current is generated by means of the measuring circuit. In a subsequent evaluation step, an evaluation of the measuring signal and an assignment to a value that is characteristic for the electromagnetic actuator takes place using the evaluation unit. For example, the characteristic value relates to an inductance of the actuator. Preferably, this characteristic value relates to its inductance in the rest position. In a comparatively simple manner and particularly during operation, the test method according to the invention makes it possible to check the function of the assembly according to the invention.

Preferably, the test period is selected in such a way that the saturation current is not reached by the actuator or its coil. The saturation current is understood to be the current at which a linear rise of the current during the application of the measuring voltage, which is substantially determined by the inductance, ends and is now substantially and over the further course determined predominantly by the ohmic resistance and the size of the voltage present.

Preferably, the test period and the measuring voltage are also selected in the test method in such a way that the acceleration of the non-operated operating part caused in the measuring step is less than 2.5 g, preferably less than 1.5 g, more preferably less than 0.5 g. A non-operated operating part is understood to be a “freely movable” operating part, i.e. an operating part that is not subjected to load due to contact with or operation by an input means, such as the finger of an operator.

According to another embodiment of the test method according to the invention, in a final adjusting step subsequent to the evaluation step, the relative arrangement of the armature and the coil is changed, such as varied or adjusted, depending on the characteristic value.

The invention further relates to a control method, also referred to as an adaptive control method, with the following steps. This test method comprises a step of providing a control member. This control member comprises a carrier, an operating part movably supported on the carrier, an electromagnetic actuator comprising an armature and a coil for driving the operating part movingly relative to the carrier.

In another subsequent, simultaneous or preceding providing step, an electronic control system connected in an electrically conductive manner to the electromagnetic actuator for applying a control voltage and a measuring voltage to the actuator is provided.

In another subsequent, simultaneous or preceding providing step, a measuring circuit connected in an electrically conductive manner to the electromagnetic actuator for measuring a current present at the electromagnetic actor and for generating a measuring signal proportional thereto is furthermore provided.

In another subsequent, simultaneous or preceding providing step, an evaluation unit connected in an electrically conductive manner at least to the measuring circuit is provided.

In a step subsequent to the above-described providing steps, a measuring voltage is applied to the electromagnetic actuator by means of the electronic control system for a predetermined test period. In a simultaneous measuring step, the current which arises at the electromagnetic actuator as the test period elapses due to the application of the measuring voltage is measured and a measuring signal proportional to the measured current is generated by means of the measuring circuit. In a subsequent evaluation step, an evaluation of the measuring signal and an assignment to a value that is characteristic for the electromagnetic actuator takes place using the evaluation unit. For example, the characteristic value relates to an inductance of the actuator. Preferably, this characteristic value relates to its inductance in the rest position.

In a subsequent step, a specific control voltage and/or a specific control period is determined using the characteristic value, for example by a comparison with predetermined values by the evaluation unit.

In a subsequent control step, the electromagnetic actuator is controlled with at least one of the specific control voltage and the specific control period by means of the electronic control system. This control step is triggered, for example, by the detection of a contact or operation of the operating part.

Because of the control method according to the invention, it is thus possible to be able to carry out an adjustment of the control by varying the control voltage and/or the control period, in particular during operation, without interfering with the actuator, in particular without changing the relative arrangement of its armature and coil.

According to a preferred variation of the method, it is provided that the test period is shorter than the control period, in particular than the specific control period.

Preferably, the test period is selected in such a way that the saturation current is not reached by the actuator or its coil. The saturation current is understood to be the current at which a linear rise of the current during the application of the measuring voltage, which is substantially determined by the inductance, ends and is now substantially and over the further course determined predominantly by the ohmic resistance and the size of the voltage present.

Preferably, the test period and the measuring voltage are selected in such a way that the acceleration of the non-operated operating part caused in the measuring step is less than 2.5 g, preferably less than 1.5 g, more preferably less than 0.5 g. A non-operated operating part is understood to be a “freely movable” operating part, i.e. an operating part that is not subjected to load due to contact with or operation by an input means, such as the finger of an operator.

According to a preferred variation, the test period is less than 5.0 ms, more preferably less than 2.0 ms, still more preferably 1.0 ms, most preferably 0.5 ms.

The assembly according to the invention and the control method according to the invention are preferably used in a motor vehicle.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

FIG. 1shows an embodiment of the assembly according to the invention. It has a control member1. This control member1comprises an operating part2defining an operating surface11on a surface facing towards the operator. The operating part2is movably supported relative to a carrier5. Furthermore, returning means10in the form of springs are provided between the carrier5and the operating part2in order to cause an elastic return of the operating part2into a rest position shown inFIG. 1. Furthermore, an electromagnetic actuator12is provided in order to drive the operating part2from the rest position, counteracting the operative direction of the returning means. The electromagnetic actuator12has a coil6on the side of the carrier made from an electrical conductor and a preferably ferromagnetic armature3on the side of the operating part, between which an air gap is formed. The current-carrying coil6cooperates with the armature3, driving the operating part2. The actuator12has a ferromagnetic core4extending through the coil6in order to concentrate or direct the magnetic field generated by the coil6. The armature3on the side of the operating part is configured as a flat armature. The actuator12is provided for driving the operating part2in a motor-operated manner in order to generate a haptic feedback for the operator by means of the movement of the operating surface11under the finger of the operator that contacts the operating surface11. The motive force of the actuator12and thus the effect of the haptic feedback are substantially determined by the clear distance d of the gap, i.e. the clear distance between the core4and the armature3in its rest position. A change of this distance d associated with the rest state causes an operating point shift of the actuator, because its force is an exponential function of the distance d, the assembly1reacts sensitively to a deviation with regard to this distance d.

The motive drive by the actuator12is achieved by an electronic control system7that applies a control voltage to the coil6of the actuator12. As was explained above, the action of the actuator12is dependent, among other things, on the clear distance d. According to the invention, this distance d is indirectly determined via the inductance of the actuator12. For this purpose, a measuring circuit9connected to the electronic control system7in an electrically conductive manner and an evaluation unit8connected to both in an electrically conductive manner are provided. They are designed to carry out the test method according to the invention as it can be carried out, for example, after the assembly of the control member1according to the invention, as suggested inFIG. 2, but also during operation in an intermediary manner between the generation of a haptic feedback caused by an operation or a contact. For this purpose, a short pulse, preferably a square-wave pulse, is input into the actuator12with a measuring voltage. Due to its inertia, the operating part2including the armature3moves only very little. In the process, due to the coil6of the actuator12, the current arising after the test period is dependent, among other things, on the inductance, i.e. ultimately on the clear distance d between the armature3and the ferromagnetic core4associated with the coil6. The current arising at the point in time at which the test period elapses, or at least the current arising immediately thereafter—the current continues to flow at approximately the same strength for a certain time—is a measure for the inductance and is measured by the measuring circuit9, and the measuring signal obtained thereby is evaluated by the evaluation unit8. For example, the measuring circuit9has a shunt for measuring the current.

Preferably, the measurement takes place using a voltage divider in order to generate a measuring signal proportional to the current; a measuring circuit9containing such a voltage divider is shown inFIG. 5. The measurement signal generated by the measuring circuit9serves an evaluation unit8for assignment to a characteristic value of the actuator, preferably of the inductance in its rest state. The term inductance in its rest state is supposed to be understood to mean at least the state in which the operating part2and thus the actuator12are in the rest state. Preferably, the test period is selected in such a way that the saturation current is not yet reached by the actuator or its coil. For this purpose, a short pulse, preferably a squarewave pulse, is input into the actuator12with a measuring voltage. Due to its inertia, the operating part2including the armature3moves only very little. In the process, due to the coil6of the actuator12, the current arising after the test period is dependent, among other things, on the clear distance d between the armature3and the ferromagnetic core4associated with the coil6. This clear distance as a value characteristic for the actuator12, which is thus determined indirectly, is compared by the evaluation unit8with a predetermined value in step S4. If there is no minimum match, a manual adjustment of the relative arrangement of the armature3and the coil6or core4is required in Step S6. The test method can be applied iteratively in order to obtain an optimum alignment and thus a maximum haptic feedback.

In an optional step S5, the control method according to the invention, also referred to as adaptive control method, may also be used by the control voltage, in particular the control voltage pulse, being varied depending on the measured distance d, in particular depending on the measured deviation of the predetermined distance from the measured distance d.

An embodiment of the control method according to the invention is described with reference toFIG. 3. After starting the assembly, in particular the electronic control system, in step S6, for example after switching on the engine control of the motor vehicle, the inductive coupling of the actuator is measured in the measuring step S7of the control method according to the invention, as was described above in the test method. Depending on the characteristic value determined in the measuring step S7, the controlling voltage, in particular the control voltage pulse, is adapted in step S8by the evaluation unit cooperating with the electronic control system.

FIG. 4describes a variation of the control method according to the invention, which is carried out triggered by a signal in step S9. For instance, this triggering takes place in cyclical intervals. Assuming a constant inductance, the current through the actuator, and thus the strength of the force excitation by the actuator12, also depends on the controlling voltage and the ohmic resistance of the coil6. The controlling voltage, for example the on-board voltage of the motor vehicle, may fluctuate during operation. In addition, the coil resistance may fluctuate depending on the temperature or for other reasons. In order to improve the haptic feedback, a short pulse, preferably a square-wave pulse, is input into the actuator12with a measuring voltage in step S10. Due to its inertia, the operating part2including the armature3moves only very little. In the process, due to the coil6of the actuator12, the current arising after the test period and measured in step S11results in a value characteristic for the actuator12, which is compared by the evaluation unit with a predetermined value in step S12. By comparison and iteratively carrying out the steps S10, S11and S12, among other things by varying the control parameters, such as the control period, and the comparison with predetermined values by means of a lookup table, such a control period is determined for controlling the actuator, for example, in which the desired controlling behavior and thus the strength of the haptic feedback is reached, and thus the iterative execution of the steps S10, S11, S12is ended in step S13in order to carry out the further control, which as a rule was triggered by the detection of a contact or operation of the operating part2on its operating surface12, with the previously determined values in Step S14. It is thus possible by means of the control method according to the invention to at least partially compensate changes in the haptic feedback, for example due to changes in the temperature and the on-board voltage, by varying the control behavior, such as the control voltage and/or the control period.

The measuring circuit9according to the invention is described with reference toFIG. 5. The inductance of the actuator12is embodied by the inductive resistor L. The measuring circuit comprises two transistors T1and T2for selectively applying to the actuator a pulse width modulated control voltage using the transistor T1and a pulse width modulated measuring voltage using the transistor T2. On the one hand, the control voltage from the supply voltage V is modulated by the controlling voltage UAnsteurerpresent at the transistor T1, whereas the modulation of the measuring voltage from the supply voltage V is modulated by the controlling voltage UMesspresent at the transistor T2. In the measuring step, the transistor T1is switched to block, whereas the transistor T2blocks in the control step. At the transistor T2, which is open in the measuring step, a voltage drop occurs at the ohmic resistor R, by which the measuring voltage present at the actuator12, in this case the coil L,6is reduced compared to the supply voltage V. The associated current is determined by means of an analog-digital converter ADC associated with the evaluation unit8by determining the voltage dropping at the resistor R at the voltage divider formed from the resistor R and the inductance L of the coil6.