Linear active haptics and method for haptic feedback of the operation of a linear active haptics contact element

Abstract

The invention relates to a method for active haptic feedback of the operation of a linear active haptics contact element, having: a planar actuation region with at least one contact element for activating at least one specified function, and a sensor system which is configured in such a way that it detects the actuation of one of the contact elements and identifies which of the contact elements, and at least one voice coil or an electromagnetic actuator with a stationary part and a movable part for outputting haptic feedback of the operation of the detected contact element, as well as at least one control device which is connected for signal transmission to at least the sensor system and the at least one actuator and which can activate the at least one actuator, wherein, on detection by the sensor system of the actuation of, or the intention to actuate, at least one of the actuators, the latter is activated in such a way that DC voltage is applied thereto, such that it applies a predetermined counter-force counter to the actuation direction of the operation to the contact element or the planar actuation region, such that a force is exerted counter to the actuation direction, and the energization of the actuator is changed as soon as an abort criterion is detected.

Description

[0001] Linear active haptics and methods for haptic feedback of the operation of a contact element of a linear active haptic system

[0002] The invention relates to improved haptic feedback in a linear active haptic of a control element.

[0003] Linearly guided control elements with active haptic feedback to the user (also known as linear active haptics) are well-known. In this system, the haptic feedback is triggered by voltage pulses via a linearly guided actuator. This actuator, starting from its rest position (i.e., when no electrical voltage is applied), can be excited by voltage pulses and thus accelerated from its rest position. This results in a perceptible "vibration" of the control element's surface. The linear force-displacement curve is essentially defined and limited (and cannot be changed) by mechanical return springs (with relatively large spring constants).

[0004] German patent DE 10 2008 046 102 B4 discloses such a linearly guided control element for use in a vehicle, which provides haptic feedback to the user upon activation. Part of the control element is a voice coil (e.g., also referred to as a voice coil). The patent also provides a control element for specifically activating the voice coil when the control element is activated. However, there is room for improvement in usability, particularly due to the limited force-displacement curve. Therefore, an object of this invention is to provide improved haptic feedback from a linear active haptic system, as well as a corresponding active haptic system that allows for a more flexible force-displacement curve, thus resulting in improved usability with haptic feedback.

[0005] This problem is solved according to the invention by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0006] A method is provided for active haptic feedback of the operation of a contact element of a linear active haptic system, which comprises: a planar actuation area with at least one contact element for controlling at least one predefined function, as well as sensors designed to detect actuation of one of the contact elements and which contact element, as well as at least one voice coil or an electromagnetic actuator with a fixed and a moving part for outputting haptic feedback of the operation of the detected contact element, as well as at least one control unit in signal communication with at least the sensors and the at least one actuator, which can control the at least one actuator, wherein, upon detection of actuation or an intention to actuate at least one of the actuators by the sensors, it is controlled in such a way thatthat it is supplied with direct current, so that it applies a predetermined counterforce against the direction of operation to the contact element or the planar actuation area, so that a force is exerted against the direction of operation, and as soon as a termination criterion has been detected, the current supply to the actuator is changed.

[0007] Furthermore, it is provided that a termination criterion is that a predetermined distance has been traveled through the contact element or the planar actuation area in the direction of actuation. It is also provided that, upon detection of a termination criterion, the application of DC voltage is modified such that it is suspended for a predetermined period, or the DC voltage is increased such that a counterforce is generated that exceeds a predetermined maximum actuation force.

[0008] Furthermore, it is provided that if a termination criterion is detected, the actuator will be additionally supplied with an alternating voltage for a specified period of time.

[0009] Furthermore, it is provided that a force-displacement curve for operating one or more functions can be specified by changing the applied DC voltage to generate the counterforce, depending on the actuation distance traveled.

[0010] Furthermore, a linear active haptic control unit for a vehicle is provided, comprising: a planar actuation area with at least one contact element for controlling a function of the vehicle, as well as sensors designed to detect an actuation or an intention to actuate one of the contact elements and which of the contact elements, as well as at least one voice coil or an electromagnetic actuator with a fixed and a moving part for outputting haptic feedback of an operation of the detected contact element, wherein each actuator is fixed at one area on a structure of the vehicle and movably connected at another area to the planar actuation area, as well as at least one control unit in signal communication with at least the sensors and the at least one actuator, which is configured to control the actuator.

[0011] Furthermore, it is provided that the area of ​​operation is designed as a rigid surface, which is formed as a touchscreen with contact elements configured as touch controls, or wherein the area of ​​operation is formed as a movable surface, at least in areas where one or more contact elements are provided. It is further provided that the sensor technology is designed as a pressure sensor or as a proximity sensor.

[0012] Furthermore, it is provided that each actuator is mechanically connected to mechanical return springs, wherein the return force of the return springs is dimensioned such that it returns the actuator to a predetermined initial position when a DC voltage is applied.

[0013] Furthermore, a vehicle is provided, comprising at least one control unit designed to control at least one function of the vehicle, as well as a linear active haptic system as described, provided as part of the control unit.

[0014] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures in the drawing, which shows details of the invention, and from the claims. The individual features can be implemented individually or in any combination in a variant of the invention.

[0015] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawing.

[0016] Fig. 1 shows a schematic representation of important components for carrying out the method according to one embodiment of the present invention.

[0017] Fig. 2 shows a schematic representation of important components for carrying out the method according to an alternative embodiment of the present invention.

[0018] In the following figure descriptions, identical elements or functions are marked with the same reference symbols.

[0019] The basic concept of the invention is to provide more flexible haptic feedback via linear active haptics. Active haptics refers to a system that provides active haptic feedback (generated by an actuator) when a control element is operated. Linear active haptics means that the control element, e.g., a button, a touchscreen contact element, etc., is actuated linearly (i.e., not rotated). Linear active haptics is part of a control unit designed to control at least one function of the vehicle. The control unit can be designed as a planar actuation area, as described below.

[0020] When operating a surface-based control area such as a touchscreen, active haptic feedback is possible by using an actuator that actively provides the feedback. Various designs are possible to provide such active haptic feedback (with linear operation), one of which uses a voice coil or other suitable electromagnetic actuators with a fixed and a moving part, as mentioned earlier.

[0021] As already mentioned, surface-mounted operating areas such as touchscreens are well-known. Such a touchscreen has one or more contact elements that serve as a control panel to operate one (or more) functions. The contact elements serve to detect a user's operating request and transmit it to a control unit designed to control the function associated with the contact panel.

[0022] To detect the operation of a contact element that serves as a linearly guided control element, suitable sensors are provided, e.g., a pressure sensor. A proximity sensor can also be provided to identify the contact element to be operated. Advantageously, the sensors are arranged beneath a protective surface so that they are not visible to the user and are also protected from damage.

[0023] Furthermore, one or more actuators are provided, which are activated when the contact element is actuated and provide the user with haptic feedback. Voice coils (also known as voice coils) or other electromagnetic actuators (with a fixed and a moving part) can be used as actuators. These are fixed to a structure of the vehicle, such as a steering wheel or body, at one point and movably connected to the surface area of ​​the contact element at another point.

[0024] A voice coil comprises a magnet (a magnetic mass) and a coil. Depending on the actuator's design, either the coil (if the magnetic mass is fixed) or the magnetic mass (if the coil is fixed) moves when current / voltage is applied, causing it to vibrate. These vibrations are transmitted to the contact element and thus to the touchscreen, allowing the user to perceive the vibrations as haptic feedback on their interaction with the contact element or the entire touchscreen. The excitation can be achieved by controlling the voice coil via a control unit that is at least in signal communication with it, which in turn triggers the application of a predefined alternating current (a predefined alternating voltage).

[0025] According to the invention, an active haptic system is provided in which operation is carried out exclusively as a linear operation of a contact element of a planar actuation area such as a touchscreen, wherein the actuator that provides the haptic feedback is formed as a voice coil, i.e. as an electromagnetic actuator with a fixed and a moving part.

[0026] Active haptics can be advantageously used, for example, in a multifunction steering wheel or an instrument panel. In particular, active haptics can have a (closed) surface-mounted actuation area, such as a touchscreen, which has several contact elements. Touching these elements allows for the control of multiple functions. Since, in this case, the entire surface of the touchscreen is actuated when a contact element is operated (i.e., pressed "downwards" in the direction of actuation B), a single actuator is sufficient for haptic feedback. However, multiple actuators can also be provided, for example, to offer redundancy. In the prior art, the described actuator is designed as a voice coil and is used to output haptic feedback based on the detected actuation (e.g., touching) of a contact element. According to the invention, haptic feedback is also output upon operation.However, the output is different from what is known from the prior art, as described below.

[0027] The same design is used as previously described. Figures 1 and 2 show different embodiments, which are described below. In all embodiments, the active haptic system has a flat actuation area 1, such as a touchscreen, as a control surface with one or more contact elements 2 that can control different vehicle functions. A voice coil (an electromagnetic actuator with a fixed and a moving part) is used as the actuator 4. This voice coil is controlled and energized (voltage applied) via a control unit 6. It is fixed at one end to a structure (chassis) of the vehicle, such as a steering wheel or body, and movably connected at another end to the flat actuation area 1.In contrast to the prior art, the voice coil (the actuator 4) is energized (subjected to DC voltage) when an actuation / intention to actuation is detected, so that it moves against the actual actuation direction B and thus provides a counterforce G to the actuation direction B of the user, which the user feels.

[0028] In one embodiment, the sensor detects the activation of a (specific) contact element 2 when a user touches it. In response to this detection, the voice coil is energized (powered with voltage) and thus pushes (depending on the touchscreen design) either the entire operating surface (the activation area 1) (Figure 1) or only the contact element 2 (Figure 2) upwards, i.e., towards the user and against the direction of activation B. The sensor 3 is part of the contact element 2 and is designed, for example, as a pressure sensor. In another embodiment, a proximity sensor is provided as sensor 3 to detect a user's intention to operate the device. This sensor detects the approach of a user (e.g., a finger) towards the activation area 1 (for operating one of the contact elements 2, and which one of the contact elements 2), thus indicating an intention to activate the contact element 2.As soon as the proximity sensor detects a specific control area (contact element) that the user wishes to activate, the voice coil is energized (powered up) and thus pushes (depending on the touchscreen design) either the entire activation area 1 (Figure 1) or only the contact element 2 (Figure 2) upwards, i.e., towards the user and against the direction of activation B. The proximity sensor can also be part of the contact element 2, but can also be implemented as a separate sensor.

[0029] The actuation area 1 is designed as a touchscreen with a closed, rigid surface on which one or more contact elements 2, designed as touch controls, are provided for controlling individual functions. As soon as an actuation of one of the contact elements 2 is detected, the voice coil (the actuator 4) is energized (powered up) and thus presses against the actuation area 1, which therefore moves as a whole in the opposite direction of actuation B, as indicated in Figure 1. If the user is already applying pressure to the contact element 2, they will feel the movement in the opposite direction of actuation B. If they have not yet touched the contact element 2, the flat actuation area 1 is pushed out in the opposite direction of actuation B (i.e., "upwards") before the user touches it, so that they must exert a certain force to move the contact element 2 (the actuation area 1) in the direction of actuation B.In this configuration, it is sufficient to use a single voice coil as actuator 4. However, multiple actuators 4 can also be used, e.g., for redundancy purposes.

[0030] In an alternative embodiment, the planar actuation area 1 is formed as a movable surface, at least in areas where one or more contact elements 2 are provided, as indicated in Figure 2. Advantageously, each contact element 2 has a movable surface that can move out of the actuation area 1. Furthermore, an actuator 4, such as a voice coil, is provided below each contact element 2. As soon as actuation is detected, the voice coil is energized (powered with voltage) and thus presses against the contact element 2, which therefore moves in the opposite direction of actuation B. If the user is already applying pressure to the contact element 2, they will feel the movement in the opposite direction of actuation B. If they have not yet touched the contact element 2, it is pushed out in the opposite direction of actuation B (i.e., "upwards") before the user touches it.In this version, the user can immediately see that his operation has been recognized, and in a version where each contact element 2 is movable, that he has hit the correct control panel (contact element), or he can see that the system has recognized the correct control panel.

[0031] In one embodiment, it is provided that the contact element 2 (or the entire actuation area 1 if it is designed as a rigid surface) must be pressed a certain distance in the actuation direction B to reliably assume that operation is intended. Likewise, it can be specified that if a certain distance is exceeded or a maximum permissible force is exceeded (i.e., excessive pressure is applied), no operation is intended.

[0032] In one embodiment, after a definable and adjustable actuation distance (the distance the contact element may be moved in the actuation direction B), the voltage applied to actuator 4 is changed, e.g., interrupted, for a short period (e.g., 20-40 ms). This results in an acceleration due to the interplay of the user's actuation force and the actuator's counterforce. The user thus receives a perceptible "actuation confirmation" as a jolt, i.e., haptic feedback of the actuation. This jolt can also be used as a termination criterion, signaling to the user that they should end the operation (e.g., because it has been detected by the control unit 6).

[0033] However, it can also be provided that, upon reaching a predetermined distance in actuation direction B (depth of depression of the contact element 2 or the flat actuation area 1), the contact element 2 (or the flat actuation area) simulates an end stop, i.e., provides a higher counterforce G to the maximum actuation force potentially applied by a user in actuation direction B. This allows the user to feel that they have pressed the contact element 2 (or the flat actuation area 1) far enough / with sufficient force and can stop operating it. In one embodiment, the user's current force can be determined, and the voice coil provides a counterforce that is a predetermined amount higher. Alternatively, the counterforce can be fixed at a predetermined amount that is higher than the maximum permissible force applied by the user in actuation direction B.

[0034] Additionally or alternatively, it can be provided that when a predetermined distance is reached in the direction of actuation B (depth of depression of the contact element or the surface actuation area), additional haptic feedback is provided, e.g., in the form of a vibration. This can be achieved by superimposing the DC voltage applied to the voice coil (to move the voice coil) with an AC voltage, which causes the coil to vibrate, and this vibration is then transmitted to the contact element 2 or the actuation area 1. This superposition occurs for a predetermined period sufficient for the user to perceive it as haptic feedback, for example, a few milliseconds.

[0035] Furthermore, as in the prior art, mechanical return springs 5 ​​are provided, but their return force can be significantly weaker compared to the mechanical return springs required in the prior art. These springs serve only to return the voice coil to a predetermined initial position after the voltage is removed, and not to provide the necessary counterforce to the force that must be exerted on the contact element 2 to detect its operation. This counterforce is provided by the voice coil itself through the voltage applied and the resulting force, which is variably adjustable by the current and acts in the opposite direction to the actuation direction B.

[0036] The technical prerequisites for implementing the proposed linear active haptic feedback are already in place in most cases, requiring only minor adjustments. As previously described, both linearly guided active haptic feedback and mechanical return springs 5 ​​are known. Rapid displacement measurement using optical or capacitive sensors is also readily available, allowing for the rapid detection of the traveled distance of the contact element 2 (or the area of ​​actuation 1). Furthermore, proximity sensors are often already integrated into the contact element 2 to enable contactless operation detection. Accurate identification of a single contact element 2 from among a multitude of adjacent contact elements 2 is also already possible.

[0037] By detecting an impending user action using proximity sensors, user interaction can be recognized even before contact element 2 is touched, and the actuator 4 can then be supplied with DC voltage. This generates a counterforce to the user's direction of action B, with an adjustable force by specifying a permissible force (in Newtons, e.g., 0-1 ON), thus providing the user with a force-displacement profile (depending on the measured distance traveled).

[0038] It can be provided that the force required to actuate contact element 2 is decreased or increased depending on the actuation distance traveled by changing the applied voltage. In this way, the force-displacement curve for each contact element 2 within the actuation range 1 can be freely designed; that is, it can be provided that the user must apply a different force to actuate contact element 2 and thus control the associated function for each contact element 2. This requires that the current actuation distance (= input variable for the voltage control) is known within a few milliseconds thanks to the available, very fast displacement measurement (optical / capacitive). By changing the applied DC voltage (to generate the counterforce) depending on the actuation distance traveled, a very flexible design of the force-displacement curve required to operate a function is possible.This enables a versatile and customizable user experience, which is not possible with current technology due to the use of mechanical return springs with high spring constants. For example, the force-displacement curve can be freely adjusted and modified by the user, or different force-displacement curves can be selected for different functions / controls. The system can predefine several force-displacement curves, which the user can then select for a specific function. Alternatively, the user can define their own force-displacement curves, meaning they can individually "teach" contact element 2 for each function by specifying the force and displacement required to operate that function.

[0039] For example, a setting could be such that a light press changes the speed or volume by one unit, and a strong press changes it by 10 units (the applied DC voltage is increased, for example, when a predetermined actuation distance is reached, so that the force applied to control the second function, i.e., to change by 10 units, must be increased).

[0040] Another setting allows a function to be triggered only after an initial press of contact element 2. This initial press might display a text field or an audible message indicating that further pressing (longer / stronger) will activate / deactivate / reset the selected function. The force required to activate the function can also be increased. Such settings are particularly useful for critical functions, such as transitions from autonomous / highly automated driving to manual driving. This two-stage operation can also be advantageous when further presses reset parameters.

[0041] In one version, the user can select the force required to control a function, i.e., what he understands by "light" and "strong", e.g. by appropriately teaching the contact element 2 or selecting the force-displacement curve from predefined displacement-force curves.

[0042] It can also be provided that when operating a contact element 2 (and thus the entire actuation area 1, if it is designed as a rigid surface), a small force must be applied for a predetermined initial travel distance in actuation direction B, which corresponds, for example, to one-third of the total possible travel distance, in order to counteract the force exerted by the voice coil, while a higher force is required thereafter. The transition of the required force for actuation provides the user with haptic feedback that the actuation has been detected.

[0043] The flat operating area 1 is advantageously designed as a touchscreen, as already mentioned. Furthermore, the actuator 4 is selected or constructed such that a predetermined travel distance to an end stop is provided.

[0044] In one embodiment, the described linear active haptics are used in a (multifunction) steering wheel 7. Here, parts of the active haptics are fixed to a structure 7 (chassis) of the vehicle, such as the steering wheel structure, or to the vehicle body. Functions that can be operated via the contact elements 2 include, for example, a turn signal, windshield wipers, a windshield washer system, infotainment system functions such as volume control or radio station selection, driver assistance functions such as cruise control and distance control, lighting functions (exterior and interior lights), climate control, seat heating, etc. The term "operation" or "activation" here refers not only to switching a function on or off, but also, for example, to...Control of volume (louder / quieter), temperature (warmer / colder), speed (faster / slower), or driving behavior (more / less distance; sporty driving, Eco mode, etc.). The examples mentioned are to be understood as mere suggestions. Any functions controllable via linear active haptics can be provided. Depending on their location within the vehicle, different or the same functions may be available at different positions, e.g., in the steering wheel and / or in the infotainment system (instrument panel).

[0045] The invention was described using an application in a vehicle such as a passenger car or a commercial vehicle. However, it can also be used in other areas of mobility or in static applications. List of reference numerals

[0046] 1 large operating area (touchscreen)

[0047] 2 contact elements

[0048] 3 Sensors (proximity sensor, pressure sensor)

[0049] 4 Actuator (voice coil)

[0050] 5 mechanical return springs

[0051] 6 Control unit

[0052] 7. Vehicle structure (chassis)

[0053] B Direction of action

[0054] G counterpressure to B

Claims

Patent claims 1. Method for active haptic feedback of an operation of a contact element (2) of a linear active haptics, which has: - a planar actuation area (1 ) with at least one contact element (2) for controlling at least one predefined function, as well as - Sensors (3) designed to detect actuation of one of the contact elements (2) and which of the contact elements (2), as well as - at least one voice coil or electromagnetic actuator (4) with a fixed and a moving part for outputting haptic feedback of an operation of the detected contact element (2), as well as - at least one control unit (6) in signal communication with at least the sensor (3) and the at least one actuator (4), which can control the at least one actuator (4), wherein - when the sensor (3) detects an actuation or an intention to actuate at least one of the actuators (4), it is controlled in such a way that it is supplied with direct current, so that it applies a predetermined counterforce (G) against the direction of actuation (B) to the contact element (2) or the planar actuation area (1), so that a force is exerted against the direction of actuation (B), and - as soon as a termination criterion is detected, the current supply to the actuator (4) is changed.

2. Method according to claim 1, wherein a termination criterion is that a predetermined distance has been covered through the contact element (2) or the planar actuation area (1) in the actuation direction (B).

3. Method according to claim 1 or 2, wherein, upon detection of a termination criterion, the application of direct current is changed such that - the application of direct current is suspended for a specified period of time, or - the DC voltage is increased in such a way that a counterforce (G) is generated which exceeds a predetermined maximum actuating force.

4. Method according to one of the preceding claims, wherein, upon detection of a termination criterion, the actuator (4) is additionally supplied with an alternating voltage for a predetermined period of time.

5. Method according to one of the preceding claims, wherein a force-displacement curve for operating one or more functions can be specified by changing the applied DC voltage to generate the counterforce (G) depending on a traveled actuation distance.

6. Linear active haptics of a vehicle control unit, which features: - a planar actuation area (1 ) with at least one contact element (2) for controlling a function of the vehicle, as well as - Sensors (3) designed to detect an actuation or an intention to actuate one of the contact elements (2) and which of the contact elements (2), as well as - at least a voice coil or an electromagnetic actuator (4) with a fixed and a movable part for outputting haptic feedback of an operation of the detected contact element (2), wherein each actuator (4) is fixed at one area on a structure (7) of the vehicle and movably connected at another area to the planar actuation area (1), as well as - at least one control unit (6) in signal communication with at least the sensor (3) and the at least one actuator (4), which is configured to control the actuator (4) according to the method according to one of the preceding claims.

7. Linear active haptics according to claim 6, wherein the planar actuation area (1) is designed as a rigid surface which is formed as a touchscreen with contact elements (2) formed as touch control elements, or wherein the planar actuation area (1) is at least in areas where one or several contact elements (2) are provided, forming a movable surface.

8. Linear active haptics according to one of claims 5 to 7, wherein the sensor (3) is designed as a pressure sensor or as a proximity sensor.

9. Linear active haptics according to one of claims 5 to 8, wherein each actuator (4) is mechanically connected to mechanical return springs (5), wherein a return force of the return springs (5) is dimensioned such that it returns the actuator (4) to a predetermined initial position upon termination of an application of DC voltage.

10. Vehicle comprising at least one control unit designed to control at least one function of the vehicle, and a linear active haptic provided as part of the control unit according to one of claims 5 to 8.

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