CONTROL UNIT FOR A VEHICLE

Description

[0001] The invention relates to an operating unit for a vehicle, which may, for example, be an infotainment system for controlling various vehicle components.

[0002] Control units with display modules, on which, for example, various menu-driven symbol fields can be displayed, allowing functions for a vehicle component to be selected when activated, e.g., by pressing down (also known as force sense), are becoming increasingly popular. The operator should receive tactile confirmation of the selection of a function, for example, through an additional active movement of the control element after its activation (so-called force feedback).

[0003] Touch-sensitive input devices are known from DE-A-10 2008 035 907 and DE-A-10 2012 000 568. FR-A-2 927 709, DE-A-10 2009 007 243, and WO-A-2006 / 124873 each disclose an input device with a laterally spring-loaded control element for haptic feedback. Furthermore, DE-A-100 43 805 discloses an electromechanical actuator for valve control of an internal combustion engine, wherein the actuator is provided with a measuring coil. DE-U-20 2011 004 616 describes a lifting armature drive.

[0004] For space and cost reasons, an electromagnet (tie-rod magnet) without permanent magnets is often used as the actuator for haptic feedback. The stator of such a tie-rod magnet is therefore operated electromagnetically. In order to adjust the desired movement of the control element's user interface, the temporal force curve on the actuator must be precisely adjustable. Furthermore, it may be necessary to actively build up the force with which the control element is moved forward and backward. This can be achieved using a double tie-rod magnet with a shared tie rod between two electromagnetic stators.

[0005] The force of an electromagnet in slowly changing magnetic fields depends essentially on the armature current and the air gap between the tie rod and the stator. However, the force curve in the case of haptic feedback is highly dynamic and includes frequency components above 1 kHz. The relationship between current and force is not trivial for the commonly used free-cutting steels or electrical steel sheets for magnetic flux guidance and can only be described using very complex modeling. Furthermore, the air gap is not precisely known due to mechanical tolerances and the movement of the user interface, which is why the force effect of a tie rod magnet can only be roughly estimated.

[0006] The object of the invention is to provide a relatively accurate and cost-effective force measurement in an actuator designed as an electromagnet for the haptic feedback of control elements of a vehicle control unit. The electromagnet can be designed as a single tie rod or a double tie rod.

[0007] To achieve this object, the invention proposes an operating unit for a vehicle, wherein the operating unit is provided with a housing with a front side, an operating element arranged on the front side of the housing, which has an operating surface, wherein the operating element is resiliently mounted, at least one sensor for detecting an actuating movement of the operating element, at least one (e.g. electromagnetic or piezoelectric) actuator for feedback movement of the operating element when an actuating movement of the operating element is detected by the sensor and an evaluation and control unit which is connected to the at least one sensor and to the actuator.

[0008] According to the invention, such an operating unit is provided with the actuator is designed as a tie-rod electromagnet with a first stator having a first excitation coil and an armature as the drive element, the armature is provided with a measuring coil to which a measuring voltage is applied when the armature is penetrated by a magnetic flux generated by the first excitation coil, and the first excitation coil and the measuring coil are connected to the evaluation and control unit, wherein the force with which the armature of the actuator can be moved towards the first stator and / or with which the deflection movement of the armature from its rest position and the return movement of the armature to its rest position takes place can be controlled and / or regulated by means of the evaluation and control unit.

[0009] With the inventive approach of measuring the magnetic flux passing through the tie rod using a measuring coil and the induced voltage drop across it, the force and movement of the tie rod can now be controlled and regulated. The movement of the tie rod can also be specifically damped, thus preventing overshoot in the respective end positions of the tie rod's forward and backward movement.

[0010] It can be further advantageous if the tie rod is arranged between two electromagnetically operated stators. In this embodiment of the invention, the tie rod therefore has a second stator with a second excitation coil, wherein the two stators are arranged on either side of the armature and the second excitation coil is also connected to the evaluation and control unit. By means of the evaluation and control unit, the respective force with which the drive element can be moved in the respective direction towards the first or second stator and / or the deflection movement of the drive element from its rest position as well as the return movement of the drive element to its rest position can be controlled and / or regulated.

[0011] To achieve the most homogeneous haptic feedback possible across the entire user interface, the control unit can advantageously be equipped with a housing with a front side, an operating element arranged on the front side of the housing, which has a center of mass and an operating surface, wherein the operating element is resiliently mounted on and / or in the housing along a vertical movement axis running substantially orthogonal to the operating surface and along a lateral movement axis running substantially transversely thereto, at least one sensor for detecting an actuating movement of the operating element in the direction of the vertical movement axis, an actuator arranged in and / or on the housing for feedback movement of the operating element at least also in the lateral movement axis upon a detected actuating movement of the operating element, wherein the actuator has an electromagnetically controllable drive element mechanically coupled to the operating element, which can be moved back and forth along an effective movement axis, and an evaluation and control unit,which is connected to the sensor and the actuator, whereby the center of mass of the control element lies on the effective movement axis of the drive element of the actuator. ,

[0012] In this development of the invention, the active haptic feedback of an actuation of the operating element is realized by a lateral deflection of the operating element. For actuation, the operating element is moved in a vertical movement axis that runs essentially orthogonal to the user interface. If this actuation movement is then detected by a sensor (force sense), an active movement of the operating element (force feedback) occurs, e.g. in a lateral movement direction or with a movement component in a lateral direction (e.g. through mechanical stimulation along a direction running at an acute angle to the user interface, e.g. to the left or right, up or down). Care must be taken to ensure that the operating element does not tilt. The operating element essentially comprises a display with corresponding display technology and technology (e.g. LCD display) and backlighting, so that it can have a not inconsiderable installation depth.Since the actuator can ideally only be positioned directly beneath this control element, its drive element for active haptic feedback in the lateral direction of movement engages the control element outside its center of mass. Without appropriate measures, this inevitably leads to the control element tilting, which is undesirable. Known solutions aim for positive guidance with a corresponding design of the spring system that mounts the control element to the control unit's housing. All of this is mechanically complex.

[0013] Therefore, this development of the invention provides for the control element and the actuator to be mechanically aligned relative to one another such that the center of mass of the control element lies on the active movement axis of the drive element. The center of mass of the control element thus lies on the extension of the active movement axis of the drive element. The active movement axis of the drive element thus runs at an acute angle to the intended lateral movement direction for the active haptic feedback. By moving the control element along the active movement axis of the drive element, the feedback movement of the control element has a vertical movement component in addition to the intended lateral movement component, which is not particularly disruptive. Rather, it is crucial that the user interface of the control element maintains its spatial orientation during active haptic feedback, i.e., experiences an oblique parallel displacement.

[0014] In principle, the excitation of the control element for haptic feedback results in the resulting movement of the control element in the form of a lateral main movement and a secondary movement normal to the user interface. Depending on the angle of the excitation, the normal movement component can vary in size. Therefore, as a rule, there is no pure lateral movement.

[0015] This measure makes it possible to execute the active haptic feedback movement purely translationally (with vertical and lateral movement components) by ensuring that the effective direction of the drive element passes through the center of mass of the control element.

[0016] Rotational movement components during active haptic feedback of the control element are further reduced by arranging the return spring elements, which are used to return the control element to its original position after active haptic feedback, in a common plane with the center of mass of the control element. The spring axes of action coincide with the axis of action of the actuator's drive element. If this were not the case, the pattern of the active haptic feedback movement of the control element would contain rotational components. For space reasons, the spring axes of action typically run parallel to the axis of action of the actuator's drive element, on both sides of this axis of action, thus largely neutralizing unwanted moments that could act on the control element during its return to its original position.

[0017] Furthermore, it is advantageous to actively control or regulate the haptics in the forward and return travel. For this purpose, it is crucial that the movement of the control element is as purely translational as possible, which can be achieved with the inventive approach. Furthermore, the inventive approach essentially ensures that the haptic sensation is always the same, regardless of the actuation location on the user interface. Complex design solutions for spring-loaded mounting of the control element in such a way that it executes a purely translational movement are no longer necessary with the invention.

[0018] It is expedient if the lateral movement axis of the operating element and the effective movement axis of the drive element of the actuator span a common vertical plane that is essentially orthogonal to the operating surface.

[0019] In a further embodiment of the invention, the housing can have an installation space below the control element, and the actuator can be arranged as close as possible to the control element and / or as far away from the center of mass of the control element as possible, given the installation space, to achieve the smallest possible angle between the effective movement axis of the actuator's drive element and the lateral movement axis of the control element. The smaller the angle between the effective movement axis of the actuator and the lateral movement axis of the control element, the greater the lateral movement component of the control element in relation to the lateral movement component during the feedback movement.

[0020] In a further embodiment of the invention, the operating unit has return spring elements for the operating element arranged on both sides of the operating element, with spring action axes which lie on the lateral movement axis or which lie in a plane which is substantially orthogonal to the plane spanned by the action axis of the drive element of the actuator and the lateral movement axis of the operating element, and are arranged symmetrically to the lateral movement axis.

[0021] The invention is explained in more detail below using an exemplary embodiment and with reference to the drawings. In detail: Fig. 1 schematically and in side view an operating unit for a vehicle component with a control element designed as a display element and spring-elastic mounting as well as active haptic feedback for actuating the control element, Fig. 2 a representation of an electromagnet, designed as a tie rod magnet with stator and armature for the basic explanation of the electromagnetically relevant properties of such an electromagnet, Fig. 3 a perspective representation of the actuator designed as a double electromagnet for the active haptic feedback and Fig. 4 a possible wiring of the electromagnet according to Fig. 3 .

[0022] In Fig. 1 A side view of an operating unit 10 is shown schematically, which has an operating element 12. In this exemplary embodiment, the operating element 12 is designed as a display assembly with a user interface 14 on which a plurality of symbol fields 16 can be displayed. The operating element 12 is usually backlit.

[0023] To execute an actuating movement in the vertical direction (see the double arrow 18) and to confirm such an actuating movement in the lateral direction (see the double arrow 20 in Fig. 1 ), the operating element 12 is elastically mounted on a housing 26 via first springs 22 and second springs 24. A sensor 28 detects whether the operating element has moved along the vertical movement axis 18. This is determined in an evaluation and control unit 30, whereupon the latter controls an actuator 32 designed as an electromagnet, which has a drive element 34. The stationary stator part 36 of the actuator 32 is supported on the housing 26, while the drive element 34 of the actuator 32 is mechanically coupled to the operating element 12. The effective movement axis of the drive element 34 is represented by the double arrow 38.

[0024] The larger and more complex the control element 12 is constructed, the heavier it is and the more space it requires. If the haptic feedback is required to be consistent across the entire user interface 14, the control element 12 should only perform a translational movement when providing haptic feedback. Theoretically, this can be achieved very simply by having the drive element 34 of the actuator 32 act on the center of mass 40 of the control element 12. However, this is not possible due to the space constraints.

[0025] If one still wants to achieve that the operating element 12 moves exclusively in a translational manner during active haptic feedback, a relatively simple structural solution is to arrange the actuator 32 in such a way that the center of mass 40 of the operating element 12 lies on the effective movement axis 38 of the drive element 34 of the actuator 32. This is shown in Fig. 1 shown, where in Fig. 1 It is also shown how the operating element 12 actively moves when an actuation movement is detected and the actuation of the operating element 12 is confirmed by haptic feedback. It should also be noted that the second spring elements 24 or their spring axes of action 42 ideally lie in a plane in which the center of mass 40 is located and in which the axis of action 38 of the actuator 32 lies, wherein the axes of action of the actuator 32 and the second springs 24 lie on a common line or run parallel to the axis of action 38 of the actuator 32 (in Fig. 1 this is indicated by the dashed double arrows 42).

[0026] Essentially orthogonal to this plane 44 is the plane spanned by the lateral movement axis 20 of the operating element 12 and the effective movement axis 38 of the drive element 34 of the actuator 32. This plane is related to Fig. 1 around the drawing plane.

[0027] The purely translational movement of the control element 12 during active haptic feedback therefore has both a lateral and a vertical component. The fact that this feedback movement is not purely lateral is irrelevant to the haptic sensation being consistent across the entire user interface 14 of the control element 12. What is crucial is that the control element 12 does not experience any rotational movement during active haptic feedback, thus resulting in a parallel displacement of the control element 12 in space.

[0028] As already described above, an electromagnet is often used as an actuator for the haptic feedback of control elements, particularly for reasons of space and cost. The force exerted by this electromagnet can only be estimated with considerable effort and depends significantly on the current and air gap of the electromagnet. The relevant conditions for an electromagnet are described below using Fig. 2 be clarified.

[0029] In Fig. 2 An electromagnet is shown whose stator and armature are made of highly permeable materials (usually free-cutting steel or electrical sheet), and whose magnetic field is generated by means of an energized excitation coil.

[0030] The force of such an electromagnet is typically calculated from the excitation current and the air gap size. However, the force curve in the case of haptic feedback is very dynamic, with frequency components above 1 kHz. The relationship between current and force is not trivial for the commonly used free-cutting steels or electrical steel sheets for magnetic flux guidance and can only be described using very complex modeling. In addition, the air gap is not precisely known due to mechanical tolerances and the movement of the user interface, meaning the force effect of the actuator can only be roughly estimated. This problem can be circumvented by using Maxwell's tensile force formula and a measuring coil to determine the magnetic flux density in the air gap. A voltage measurement is generally more cost-effective than a current measurement: F = B L 2 A L 2 μ 0 (F - actuator force, µ 0 - permeability of air, A L - air gap area, B L - magnetic flux density in the air gap)

[0031] The relatively low inhomogeneity of the air gap flux density in practical designs can be taken into account by a correction factor, which in turn leads to a simple realization of a force measurement using a measuring coil: F t = C μ 0 A L 1 N MS ∫ 0 t u t ′ dt ′ 2 (t - Time, C- Air gap correction factor, N MS - number of turns of the measuring coil, u(t)- induced voltage in the measuring coil)

[0032] The integration of the induced voltage can be performed digitally using a microcontroller that is usually already present in the system. Thus, the force is known at every moment of the control.

[0033] Fig. 3 shows the actuator 32 in perspective view. This actuator 32 is designed as a double electromagnet, whose drive element 34, as an armature 46, is arranged between a first stator 48 and a second stator 50 and can generate force in two opposite directions along the effective movement axis 38.

[0034] The first and second stators 48, 50 are attached to the housing 26, while the armature 46 is rigidly connected to the operating element 12. The first stator 48 has a first excitation coil 52, while the second stator 50 is provided with a second excitation coil 54. The armature 46 is surrounded by a measuring coil 56. A first and a second air gap 58, 60 are located on both sides of the armature 46. Since the force acting on the armature 46 is intended to be directed in one direction, the excitation coils 52, 54 are not energized simultaneously, but alternately. The structure of the measuring coil 56 on the armature 46 enables precise and cost-effective force measurement in both effective directions along the effective movement axis 38.

[0035] The control and evaluation of the voltage induced in the measuring coil 56 can be carried out, for example, by means of a microcontroller 62, which can be part of the evaluation and control unit 30. An example of a circuit with the microcontroller 62 is shown in Fig. 4 The induced voltage in the measuring coil 56 is first smoothed by a simple low-pass filter 64 to eliminate the PWM clock (frequency typically > 20 kHz) used to alternately control the two excitation coils 52, 54 from the measurement signal. The microcontroller 62 then records the induced voltage and digitally integrates it. The cutoff frequency of the low-pass filter 64 should be sufficiently higher than the highest frequency components of the force curve. BEZUGSZEICHENLISTE

[0036] 10Control unit 12Control element 14User interface of the control element 16Symbol fields 18Vertical movement axis of the control element 20Lateral movement axis of the control element 22Spring elements 24Spring elements 26Housing 28Sensor 30Control unit 32Actuator 34Drive element of the actuator 36Stator part of the actuator 38Actuator's effective movement axis 40Center of mass of the control element 42Spring effective axis 44Plane 46Armature 48Stator 50Stator 52Excitation coil 54Excitation coil 56Measuring coil 58Air gap 60Air gap 62Microcontroller 64Low-pass filter

Claims

1. An operating unit for a vehicle component, in particular an infotainment system for operating various vehicle components, having - a housing (26) having a front face, - an operating element (12) arranged on said front face of said housing (26), which comprises an operating surface (14), wherein said operating element (12) is spring-elastically mounted, - at least one sensor (28) for detecting an actuation movement of said operating element (12), - at least one actuator (32) for a feedback movement of said operating element (12) in the case of an actuation movement of said operating element (12) detected by said sensor (28), and - an analysis and control unit (30) which is connected to said at least one sensor (28) and said actuator (32), characterized in that - said actuator (32) is configured as an armature-type electromagnet having a first stator (48) comprising a first excitation coil (52), and an armature (46) as a drive element (34), - said armature (46) is provided with a measuring coil (56) to which a measuring voltage is applied when a magnetic flux generated by said first excitation coil (52) flows through said armature (46), and - said first excitation coil (52) and said measuring coil (56) are connected to said analysis and control unit (30), wherein by means of said analysis and control unit (30) the force is adapted to be controlled and / or regulated with the aid of which said armature (46) of said actuator (32) is adapted to be moved towards said first stator (48) and / or with the aid of which the deflection movement of said armature (46) out of its rest position as well as the return movement of said armature (46) into its rest position are adapted to be controlled and / or regulated.

2. The operating unit according to claim 1, characterized in that the armature-type electromagnet comprises a second stator (50) having a second excitation coil (54), wherein the two stators (48, 50) are arranged on both sides of the armature (46), and that said second excitation coil (54) is also connected to the analysis and control unit (30), wherein by means of said analysis and control unit (30) the respective force is adapted to be controlled and / or regulated with the aid of which said armature (46) is adapted to be moved into the respective direction towards the first and / or the second stator (48, 50) and / or the deflection movement of said armature (46) out of its rest position as well as the return movement of said armature (46) into its rest position are adapted to be controlled.