Method and device for adjusting a control element with active haptic feedback

Abstract

Method for adjusting the deflection (1) of a control element (11) with active haptic feedback, characterized by the following features: - the deflection (1) caused by an impulse excitation of the control element (11) is subjected to measurement for a limited time, - based on the measurement, a function of the magnitude (2) of the deflection (1) characteristic of the control element (11) over time is determined, - the function is examined for specific extrema (12) and their number is recorded, - depending on the number of extreme points (12), a desired global maximum (13) of the function for the control element (11) is determined and - the control element (11) is adjusted with the aim of achieving a homogeneous subjective intensity of haptic feedback so that the function will exhibit the specified maximum (13) in the future with the same stimulation.

Description

[0001] The present invention relates to a method for adjusting a control element with active haptic feedback. The present invention also relates to a corresponding device, a corresponding computer program, and a corresponding storage medium. State of the art

[0002] Control elements that provide active haptic feedback are well known. Such processes are implemented in touchscreens, touchpads, and keypads, for example.

[0003] In the automotive industry, it is common practice to equip vehicle controls with active haptic feedback according to Fig. 1. This technology allows users to receive tactile feedback when making an input on a touchscreen or other control element. This typically involves simulating a click sensation, which can be generated by various mechanisms such as motors or electromagnets. The goal is to provide the user with confirmation of their input, comparable to pressing a physical button.

[0004] Active haptic feedback is often generated by a brief, pulse-like movement of the surface of the control element, which the user touches with their finger. This movement can be perceived as a vibration or a click. The main direction of the deflection (10)—whether horizontal or vertical—is irrelevant for the perception of the haptic feedback.

[0005] Fig. Figure 2 shows an example of the precise characterization and evaluation of the haptic feedback of a control element (10) by measuring the deflection over time. This function describes the intensity and duration of the haptic feedback and allows the deflection of the surface to be evaluated. As part of product development and testing, corresponding measurements are performed and analyzed to standardize the haptic feedback of the control elements.

[0006] Conventional haptic feedback is provided by pulse-like deflection of the surface in the form of a half-oscillation (“half-wave”) according to Fig. 3. This deflection is immediately and strongly dampened to prevent further vibrations and thus convey a precise click sensation. The user's perception is largely determined by the amplitude, i.e., the maximum deflection. Therefore, in conventional control units, the characteristic of a sharply defined, single maximum deflection immediately after the excitation is used as a typical indicator of the quality of the haptic feedback. Fig. 3 at its first extreme point (12).

[0007] DE102016005642A1 describes a control element for a motor vehicle that includes an actuator that can deflect a user interface upon manual input. An acceleration sensor is connected to the user interface and measures its acceleration, which serves as a controlled variable in a control loop. This control loop controls the drive device so that the deflection of the user interface is damped. After a certain number of oscillation periods, the oscillation of the user interface is significantly reduced, so that the maximum deflection is limited to a predefined amount, for example, 30% of the original deflection. This means that the haptic feedback is time-limited and perceived as a particularly high-quality signal.

[0008] DE102017104541A1 describes an actuator with a vibration that has a defined cutoff frequency below 120 Hz. This cutoff frequency is characterized by a 70 percent drop in the maximum amplitude; from this frequency onward, the spectrum remains continuously below the defined cutoff amplitude. The electrical control signal that generates the vibration consists of a sequence of an excitation and a braking signal, both generated within 16 milliseconds.

[0009] DE102022108877A1 describes an actuating element that is mounted to oscillate at two natural frequencies. The lower natural frequency, resulting from the actuating element's mounting, is in the range of 50 Hz to 100 Hz. The actuating element has a mass between 500 g and 1000 g. The excitation signal for the element's electrodynamic or piezoelectric actuator is selected such that it is de-energized as soon as the maximum deflection is reached, at the latest after the first overshoot of the rest position, when a deflection is undershot that is one-tenth of the maximum deflection.

[0010] DE102022118723A1 describes a method for calibrating a desired haptic feedback of an actuator for a motor vehicle. The feedback is measured to obtain a curve, from which a feature is then extracted. Based on this feature, the control signal is adjusted. The method can be performed repeatedly or once for end-of-line calibration.

[0011] DE 10 2019 108 425 B3 discloses the subject matter of the preamble of claim 1, wherein a variable is derived from the characteristic function, such as the number of oscillation periods, and the control signal for future excitations is determined based on an algorithm trained by machine learning, using at least one measured environmental variable and properties of the characteristic function as input variables. Disclosure of the invention

[0012] For the purposes of the following explanations, Fig. 4, the magnitude (2) of the deflection (1) is used to simplify representation and analysis. This convention facilitates understanding of the subsequent figures and the identification of the relevant deflection features.

[0013] One challenge is ensuring a consistent and high-quality user experience in mass production of controls with active haptic feedback. With the introduction of new technologies and approaches to generating haptic feedback, such as different types of actuators or mounting methods, new uncertainties arise that complicate the standardization of haptic feedback in mass production.

[0014] In particular, it is evident that with the aforementioned novel actuators or bearing methods, the generation of a single half-wave is no longer consistently possible. Rather, due to manufacturing tolerances and other influencing factors within mass production, variations in the number of dominant half-waves occur during the deflection process (compare Fig. 5). One control element could therefore exhibit a dominant maximum in this sense, while another control element of the same production series reaches the global maximum (13) several times in a single excitation.

[0015] This results in the challenge that if the maximum deflection were set uniformly across all controls, regardless of the actual number of extreme points of the function characteristic of the individual control, the feedback would be perceived with varying intensity for different controls. Thus, while a control with a single maximum provides a certain intensity of feedback, a control with multiple maxima could appear noticeably weaker or stronger (14) in its intensity to the user. This would lead to inconsistency in the user experience and impair the perceived quality of the haptic feedback as well as user satisfaction.

[0016] The described problem is solved by a method for adjusting an operating element with active haptic feedback, a corresponding device, a corresponding computer program and a corresponding storage medium according to the independent claims.

[0017] This approach has the advantage of enabling adaptive calibration of the haptic feedback of vehicle controls, thereby achieving a consistent subjective intensity of haptic feedback across all controls, even if they vary during production.

[0018] A measurement identifies the specific displacement-time function and determines the maximum and number of extreme points. Based on this, different target values ​​for maximum displacement are defined to ensure consistent haptic perception.

[0019] This compensates for production-related fluctuations in the haptic properties of the control elements. End-of-line calibration according to the invention, in which each control element is individually measured and adjusted at the end of the production line, thus increases the quality of the final product.

[0020] Setting a threshold corresponding to a certain percentage of the determined maximum deflection value helps ensure that only those deflections that provide significant haptic feedback are considered dominant. This definition and selection of the extreme points relevant for haptic feedback refines the haptic quality, providing the user with a precise and responsive tactile sensation.

[0021] Further advantageous embodiments of the invention are specified in the dependent patent claims. Short description of the drawings Fig. Figure 1 shows how an electromagnetic excitation causes a deflection that is accompanied by active haptic feedback. Fig. Figure 2 shows the function graph of the signed deflection over time (“deflection-time curve”), which was determined by measuring an actual control element. Fig. Figure 3 shows the function of the pulse-like deflection of a state-of-the-art control unit, which reaches its global maximum at an extreme point on the first half-wave. Fig. Figure 4 illustrates a graphic convention whereby the following figures represent the magnitude of the deflection instead of the deflection. Fig. Figure 5 illustrates that deflections whose magnitude repeatedly reaches a given global maximum over time are accompanied by haptic feedback that exhibits a greater subjective intensity. Fig. Figure 6 illustrates the core idea of ​​setting a similar or consistent subjective intensity of feedback for control elements of the same type from common mass production. Fig. Figure 7 illustrates the definition of the term “dominant half-wave” used in the following description using a threshold value. Embodiments of the invention

[0022] Fig. Figure 6 illustrates the procedure for setting a consistent subjective intensity (15) of the haptic feedback for identical control elements from mass production. This is achieved by individually measuring and adjusting each control element at the end of the production line, the so-called end-of-line. The deflection of the control element caused by electromagnetic excitation is measured, and the characteristic deflection-time function is determined. The function is then examined for relevant extreme points.

[0023] Fig. 7 illustrates the determination of this relevance using the maximum deflection x maxA certain percentage of this maximum, for example, 80%, is set as the threshold value. Those extreme points – in this case, three – at which the magnitude of the deflection exceeds this threshold value are classified as relevant or “dominant” and taken into account in the subsequent calibration. Based on the number of these extreme points, a target value is defined for the global maximum to be achieved, for example, 40 µm for one, 20 µm for two, 16 µm for three, and 12 µm for four relevant extremes. The control unit according to Fig. 7 would thus be set to be deflected up to a maximum of 16 µm upon future excitation. List of reference symbols 1 deflection 2 Amount (of deflection) 10 deflection 11 Control element 12 Extreme point 13 global maximum 14 greater subjective intensity 15 matching subjective intensity

Claims

[1] Method for adjusting the deflection (1) of an operating element (11) with active haptic feedback, having the following features: - the deflection (1) caused by a pulse-like excitation of the control element (11) is subjected to a measurement for a limited time and - based on the measurement, a function of the amount (2) of the deflection (1) over time which is characteristic of the operating element (11) is determined, characterized by following features: - the function is examined for certain extreme points (12) and their number is recorded, - depending on the number of extreme points (12), a desired global maximum (13) of the function for the control element (11) is determined and - the control element (11) is set so that the function has the specified maximum (13) in the future with the same excitation. [2] Method according to claim 1, characterized by following features: - the control element (11) is mass-produced and - the maximum (13) is determined in such a way that the haptic feedback associated with the deflection (1) caused by the excitation develops a consistent subjective intensity (15) for control elements (11) of the same type from mass production. [3] Method according to claim 1 or 2, characterized by following feature: - the maximum (13) is chosen higher, the smaller the number of extreme points (12) is. [4] Method according to one of claims 1 to 3, characterized by following features: - when examining the function determined by the measurement, its global maximum (13) is determined, - depending on the maximum (13) a threshold value is set and - only those extreme points (12) at which the amount (2) of the deflection (1) exceeds the threshold value are included in the recorded number. [5] Method according to claim 4, characterized by following feature: - the threshold is 40% to 90% of the maximum (13). [6] Method according to one of claims 1 to 5, characterized by at least one of the following characteristics: - if the number is 1, the maximum (13) is set to the amount of, for example, 40 µm, - if the number is 2, the maximum (13) is set at 40% to 60% of the amount, - if the number is 3, the maximum (13) is set at 30% to 50% of the amount, - if the number is 4, the maximum (13) is set at 20% to 40% of the amount. [7] Method according to one of claims 1 to 6, characterized by following feature: - the excitation is electromagnetic. [8] Device, characterized by following features: - the device is designed to carry out a method according to one of claims 1 to 7. [9] Computer program which is designed to carry out all the steps of a method according to one of claims 1 to 7. [10] A machine-readable storage medium having stored thereon a computer program according to claim 9.

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