A haptic feedback method and apparatus

Abstract

According to an aspect, a method for reducing distortion and improving mechanical displacement response of a haptic feedback device (100) is provided. The method comprises generating an input signal (200) for an actuator (105) of a haptic feedback device (100), wherein signal level of the input signal is configured to change at a higher frequency in a descending or ascending direction of a wave form of the input signal between two consecutive amplitudes of the input signal compared to the signal level change in an opposite direction of the waveform before and after the two consecutive amplitudes; and providing the input signal to the haptic feedback device. Devices and methods are disclosed.

Description

[0001] A HAPTIC FEEDBACK METHOD AND APPARATUS

[0002] TECHNICAL FIELD

[0003] This disclosure relates to haptic feedback . In particular, this disclosure relates to a method and a device for improved haptic feedback .

[0004] BACKGROUND

[0005] Haptic feedback technology is widely used in modern devices such as phones , virtual reality (VR) devices , automobiles and so forth . Haptic feedback refers to the experience of touch by applying forces , vibrations or motions to a user . Haptic feedback technologies may be used to create , for example , virtual obj ects in a computer simulation, to control virtual obj ects and to enhance remote control of machines and / or devices .

[0006] SUMMARY

[0007] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description . This summary is not intended to identify key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter . The scope of protection sought for various embodiments of the present disclosure is set out by the independent claims .

[0008] Example embodiments of the present disclosure may enable a method and an apparatus for generating a haptic feedback input signal with improved properties . The haptic feedback input signal may enable reducing distortion at haptic feedback devices , and may provide improved haptic feedback experience for a user of the haptic feedback device . An example embodiment may enable maximi zing displacement of a haptic feedback element providing the haptic feedback when actuated with the haptic feedback signal .

[0009] According to a first aspect there is provided method . The method may comprise generating an input signal for an actuator of a haptic feedback device , wherein signal level of the input signal i s conf igured to change at a higher frequency in a descending or ascending direction of a wave form of the input signal between two consecutive amplitudes of the input signal compared to the signal level change in an oppos ite direction of the waveform before and after the two consecutive amplitudes ; and providing the input signal to the haptic feedback device .

[0010] According to an implementation form of the first aspect , the signal level changes at a first frequency before reaching a first amplitude of the consecutive amplitudes , at a second frequency between the consecutive amplitudes , and at a third frequency after reaching a second amplitude of the consecutive amplitudes , and wherein the second frequency is higher than the first frequency and the third frequency .

[0011] According to an implementation form of the first aspect , the first and the third frequency comprise the same frequency .

[0012] According to an implementation form of the first aspect , the higher order frequency is configured to be substantially equal to an eigenfrequency of a haptic interaction element of the haptic feedback device configured to be actuated using the input signal .

[0013] According to an implementation form of the first aspect , the higher frequency i s conf igured to be substantially equal to a first eigenfrequency or a second eigenfrequency of a haptic interaction element of the haptic feedback device configured to be actuated using the input signal .

[0014] According to an implementation form of the first aspect , the second frequency i s conf igured to be substantially equal to an eigenfrequency of a haptic interaction element of the haptic feedback device to be actuated, and at least one of the first frequency or the third frequency is configured to be substantially equal to a lower order eigenfrequency of the haptic interaction element than the second frequency .

[0015] According to an implementation form of the first aspect , at least one of the first frequency or the third frequency is configured to be substantially equal to a first eigenfrequency of the haptic interaction element and the second frequency is configured to be substantially equal to a second eigenfrequency of the haptic interaction element .

[0016] According to an implementation form of the first aspect , the method may comprise obtaining data indicative of one or more eigenfrequencies of the haptic interaction element ; and configuring at least one of the frequencies based on the data .

[0017] According to an implementation form of the first aspect , the data comprise one or more measurements of displacement of the haptic interaction element with respect to an actuation frequency; and the method comprises configuring at least one of the frequencies at a frequency resulting in approximately highest displacement .

[0018] According to an implementation form of the first aspect , the method may comprise performing smoothing of the input signal in the opposite direction of the wave form .

[0019] According to a second aspect , an apparatus is provided . The apparatus may comprise an input signal generation circuitry configured to generate an input signal for an actuator of a haptic feedback device , wherein signal level of the input signal i s conf igured to change at a higher frequency in a descending or ascending direction of a wave form of the input signal between two consecutive amplitudes of the input signal compared to the signal level change in an oppos ite direction of the wave form before and after the two consecutive amplitudes ; and provide the input signal to the actuator of the haptic feedback device .

[0020] According to an implementation form of the second aspect , the signal level is configured to change at a first frequency before reaching a first amplitude of the consecutive amplitudes , at a second frequency between the consecutive amplitudes , and at a third frequency after reaching a second amplitude of the consecutive amplitudes , and wherein the second frequency is higher than the first frequency and the third frequency .

[0021] According to an implementation form of the second aspect , the first and the third frequency comprise the same frequency .

[0022] According to an implementation form of the second aspect , the higher order frequency is configured to be substantially equal to an eigenfrequency of a haptic interaction element of the haptic feedback device configured to be actuated using the input signal .

[0023] According to an implementation form of the second aspect , the higher frequency is configured to be substantially equal to a first eigenfrequency or a second eigenfrequency of a haptic interaction element of the haptic feedback device configured to be actuated using the input signal .

[0024] According to an implementation form of the second aspect , the second frequency is configured to be substantially equal to an eigenfrequency of a haptic interaction element of the haptic feedback device to be actuated, and at least one of the first frequency or the third frequency is configured to be substantially equal to a lower order eigenfrequency of the haptic interaction element than the second frequency .

[0025] According to an implementation form of the second aspect , at least one of the first frequency or the third frequency is configured to be substantially equal to the first eigenfrequency of the haptic interaction element and the second frequency is configured to be substantially equal to the second eigenfrequency of the haptic interaction element .

[0026] According to an implementation form of the second aspect , the apparatus further comprises a control circuitry configured to obtain data indicative of one or more eigenfrequencies of the haptic interaction element ; and conf igure at least one of the frequencies based on the data .

[0027] According to an implementation form of the second aspect , the data comprises one or more measurements of displacement of the haptic interaction element with respect to an actuation frequency; and at least one of the frequencies is configured at a frequency resulting in approximately highest displacement .

[0028] According to an implementation form of the second aspect , the input signal generation circuitry is conf igured to perform smoothing of the input signal in the opposite direction of the wave form .

[0029] According to an implementation form of the second aspect , the apparatus comprises the haptic feedback device .

[0030] According to an implementation form of the second aspect , the haptic interaction element comprises a knob, a display or a panel .

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings , which are included to provide a further understanding of the charging apparatus and constitute a part of this specification, illustrate examples and together with the description help to explain the principles of the charging apparatus . In the drawings :

[0033] FIG . 1 illustrates an example of a haptic feedback device according to an example embodiment ; FIG . 2 illustrates an example of a haptic feedback input signal according to an example embodiment ;

[0034] FIG . 3A il lustrates an example of a s ine wave haptic feedback input signal and measured response to the sine wave excitation ;

[0035] FIG . 3B illustrates an example of a square wave haptic feedback input signal and measured response to the square wave excitation ;

[0036] FIG . 3C illustrates a sine wave haptic feedback input signal with a high descending slope according to an example embodiment and measured response of the respective signal ;

[0037] FIG . 3D illustrates a sine wave haptic feedback input signal with a high descending slope and smoothing at a start and an end of the signal according to an example embodiment and measured response of the respective signal ;

[0038] FIG . 4 illustrates an example of two haptic feedback input signals comprising different frequencies according to example embodiments ;

[0039] FIG . 5 illustrates an example of an apparatus configured to perform one or more example embodiments .

[0040] FIG . 6 illustrates an example of measurement data indicative of resonance of a measured component according to an example embodiment ;

[0041] FIG . 7A illustrates an example of measured results of a haptic feedback device , when excited with a single-cycle square-wave impulse of 165 Hz ;

[0042] FIG . 7B illustrates an example of measured results of a haptic feedback device , when excited with a single-cycle sinewave impulse of 165 Hz ;

[0043] FIG . 7C illustrates an example of measured results of a haptic feedback device , when excited with a haptic feedback input signal of 165 Hz modified according to an example embodiment ; and FIG . 8 illustrates an example of a method for reducing distortion of a haptic feedback device according to an example embodiment .

[0044] Like reference numerals are used to designate like parts in the accompanying drawings .

[0045] DETAILED DESCRIPTION

[0046] Reference will now be made in detail to embodiments , examples of which are illustrated in the accompanying drawings . The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utili zed . The description sets forth the functions of the example and sequence of steps for constructing and operating the example . However, the same or equivalent functions and sequences may be accomplished by different examples .

[0047] Haptic technology, or haptics for short , is a technology that may provide a user of a related device utili zing haptics a notification, e . g . , a simulated touch experience as a response to an action or a function . This is called haptic feedback . Haptic feedback is generated by haptic feedback devices and they generally may provide the haptic feedback to the enclosure of the related device . For example , the haptic feedback device may provide a haptic feedback signal that may comprise a very quickly dissipating vibration signal generated by a voltage s ignal , so that the user acknowledges the pressing of the touchscreen the related device also utili zes .

[0048] Due to the nature of haptic feedback devices , they may be utili zed to generate sound as well . E . g . , the enclosure of a related device utilizing haptics may be designed to propagate sound signals as well . This means that the signal quality of the driving haptic input signal to the haptic feedback device may need to be well preserved, and the haptic feedback device itself may need to be able to convert the input signal to mechanical energy with high efficiency .

[0049] Distortion, ringing and unwanted under- or overtones may be generated by driving the haptic feedback device , either by an unoptimi zed signal form or too low- or too high signal power .

[0050] An obj ective of this disclosure is to provide an improved input signal for haptic feedback . The input signal may be modified such that distortion and ringing may be reduced . A more accurate and fast feedback input signal may be provided to enhance haptic feedback provided for a user of a haptic feedback device .

[0051] Example embodiments provide a method for generating an input signal to be provided for a haptic feedback device , an apparatus that is configured to execute the example method ( s ) and a haptic feedback device that is configured to receive the input signal from the apparatus .

[0052] FIG . 1 illustrates an example of a haptic feedback device 100 according to an example embodiment . The haptic feedback device 100 may comprise at least one supporting unit 103 , 104 ( suspension unit) for a haptic interaction element 101 . The supporting unit 103 , 104 may comprise , for example , a spring . The supporting unit 103 , 104 may comprise an elastic material . A haptic interaction element may also be referred to as a haptic interface element . The haptic interaction element 101 may comprise a surface . The haptic interaction element 101 may comprise , for example , a knob, a panel , a display, or the like configured to convey haptic feedback for a user . The haptic interaction element 101 may be configured to be mechanically displaced when actuated . For example , the surface may be caused to be biased or bend mechanically when actuated by an actuator . Mechanical bending may be measured as (mechanical) displacement of the surface with respect to a reference plane. For example, the haptic interaction element 101 may be configured to move between a first position and a second position when an actuator coupled with the haptic interaction element is triggered with an input signal. An input signal for a haptic feedback device may be also called a haptic feedback input signal. The haptic feedback device 100 may also comprise a base element 102. The base element 102 may act as a mechanical reference plane for the haptic interaction element 101. For example, the haptic interaction element 101 may be configured to mechanically bend downwards towards the base element 102 when actuated. The one or more supporting units 103, 104 may be configured between the haptic interaction element and the base element such that there is at least enough space for the displacement in the direction towards the base element.

[0053] Displacement 107 of the haptic interaction element (i.e., distance between the first position and the second position) may be such that a user is able to sense the movement of the haptic interaction element between the two positions when the user is in contact with the haptic interaction element 101. For example, when the user holds a finger on the haptic interaction element 101, the displacement 120 may be sensed by the user as vibration or a bump.

[0054] For example, the haptic feedback device 100 may comprise or be coupled to any suitable apparatus such as for example a mobile phone, a television, a computer, a music player, or some other type of user device. For example, the base element 102 may form at least a part of a frame of the apparatus. For example, the haptic interaction element 101 may be or be comprised in a screen or a display of the apparatus (e.g. an electronic apparatus) . The haptic feedback device 100 may be for example applicable to vehicles (e.g. cars or vessels) . For example , the haptic feedback device 100 may comprise a car panel such as an interior panel of a car (e . g . door panel , ceiling or roof panel , wall panel , frame panel , or some other part of the car interior) . The haptic interaction element 101 may for example comprise a di splay of a car . The haptic feedback device 100 may be alternatively comprised in a wearable device , such as a wearable electronic device . For example , the haptic feedback device 100 may be comprised in a portable electronic device , such as a watch .

[0055] Furthermore , the haptic feedback device 100 may comprise an actuator 105 . The actuator 105 may be excited by driving the actuator 105 with the input signal fed to an input port 106 . The haptic feedback device 100 may be configured to be excited ( actuated) to gain enough movement (displacement 120 ) between the haptic interaction element 101 and the base element 102 , such that a user may detect the excitation that is caused by driving the input signal to the input port 106 . The input signal may be configured to operate at a haptic frequency band . The haptic frequency band may refer to frequencies between 10 -300 Hz , preferably 20 -250 Hz , or more preferably 150 - 180 Hz .

[0056] The actuator 105 of the example haptic feedback device 100 illustrated in FIG . 1 may comprise , for example , a first magnetic element coupled with the haptic interaction element 101 . The first magnetic element may be configured to move along the displacement 120 of the haptic interaction element 101 . The haptic feedback device 100 may further comprise a second magnetic element coupled with the base element 102 . At least one of the first magnetic element or the second magnetic element may comprise a permanent magnet . The second magnetic element may be arranged to face the first magnetic element . The haptic feedback device 100 may also comprise a coil arranged between the first and the second magnetic element . For example , the coil may be coupled to the second magnetic element . The coil may be configured to be electrically excited with the input signal via the input port 106 . The coil may be configured to cause movement of haptic interaction element based on a magnetic field configured to be generated by the coil upon activation of the input signal . The displacement of the haptic interaction element 101 caused by the movement may occur in a direction perpendicular to a surface plane 108 of the base element 102 . The displacement 120 of the haptic interaction element 101 may be proportional to the input signal provided to the coil . The coil may be also referred to as a haptic coil or a feedback coil . However, the actuator design illustrated FIG . 1 is one example , and the actuator may be also implemented differently . For example , the actuator 105 could comprise a voice coil actuator or a Piezo Haptic actuator . The actuator 105 may further comprise any other type of a haptic actuator which may be applicable for actuating the haptic interaction element 101 .

[0057] The haptic feedback device 100 may comprise , or be configured to be coupled with, an apparatus 109 configured to provide the input signal for the actuator 105 . The apparatus 109 may comprise at least an input signal generation circuitry 110 . The input signal generation circuitry 110 may be configured to generate the input signal for the haptic feedback device , for example , in response to a trigger . The input signal generation circuitry 110 may be configured to excite power for actuating the movement (e . g . , mechanical bend) of the haptic interaction element . The input signal may be generated based on one or more parameters obtained by the input signal generation circuitry 110 . The parameters may comprise , for example , at least one of a maximum voltage or current level ( i . e . an amplitude ) of the input signal , one or more frequencies to be applied for the input signal or one or more smoothing operations to be performed . The one or more smoothing operations may comprise , for example , the method of least squares . For example , when the signal changes from a first frequency to a second frequency, or from a second frequency to a third frequency, there may be discontinuities or abrupt unwanted changes in the signal near the region where the signal changes direction . The method of least squares may be utili zed to either reduce / minimi ze the problems that may arise from said discontinuities ( a "pop" sound for example ) .

[0058] The apparatus may further comprise a control circuitry 111 . The control circuitry 111 may be configured to provide one or more of the parameters to the input signal generation circuitry 110 . For example , the control circuitry 111 may be configured to determine the one or more frequencies to be used in generating the input signal . The control circuitry 111 may be further configured, for example , to provide the trigger to the input signal generation circuitry 110 .

[0059] The input generation circuitry 110 and the control circuitry 111 may be implemented using analog or digital circuits , or a combination thereof . In the analog domain these circuitries may be implemented for example based on comparator, derivator, or integrator circuits , or the like . In the digital domain, the circuitries may comprise digital components such as for example logic gates , other digital logic, or processor circuitry such as a microcontroller unit (MCU) associated with at least one memory . The input signal generation circuitry and / or the control circuitry may be applicable to any user device configured to receive input signals for actuation of haptic feedback .

[0060] Haptic feedback devices , and in particular, the haptic interaction element may have at least one eigenfrequency, usually multiple eigenfrequencies . Eigenfrequency means a natural frequency or a resonant frequency of the haptic feedback device that tends to cause oscillations in the absence of any driving force . The eigenfrequencies may depend on the dimensions , the components , the materials etc . the haptic feedback device is constructed from . Therefore , a signal , that comprises one or more of these said eigenfrequencies , and is introduced as an input signal to a haptic feedback device , may cause the haptic interaction element to have higher displacement energy and longer ringing due to the resonance .

[0061] The input signal provided for the haptic feedback device may be divided into three separate distinguishable regions . In the first region, the input signal may be configured to cause the haptic interaction element to transition to the first position . For example , the haptic interaction element 101 may be driven to the first position (e . g . , up or down with respect to the base element 102 ) in response to an input voltage or current connected to the actuator . The input voltage may be selected based on a desired displacement value , i . e . , the first or the second position in relation to a reference plane . In the second region, the displacement ( tension) may be relieved by driving the input signal to an oppos ite maximum value from the first region, and further causing the haptic interaction element 101 to transition to the second position . The second region may be driven with a higher frequency than that of the first region . Hence , the transition between the first and the second position may be fast ( i . e . signal level changes faster from peak-to-peak compared to when using a lower frequency) . The higher frequency may preferably correspond to an eigenfrequency of the haptic interaction element 101 . Hence , higher displacement value may be achieved . Finally in the third region, the input signal may be driven such that the haptic interaction element transitions back to the original ( zero ) displacement value from the opposite displacement value with a slower frequency than the second region frequency . The displacement value may depend on the power or energy that the device is actuated with . For example , a 1 Volt peak-to-peak input signal may have a higher displacement value than a 0 . 5 Volt peak-to-peak input signal , unless the haptic feedback device in question is not already saturated between those said voltage values .

[0062] FIG . 2 illustrates an example embodiment of an input signal 200 for a haptic feedback device on timeamplitude axis . The time-axis (x) is divided by milliseconds (ms ) and the amplitude axis ( y) is normali zed between - 1 and 1 . The input signal 200 may be configured to control a haptic feedback device, such as the example haptic feedback device 100 of FIG . 1 . The input signal may be input to the haptic feedback device 100 to actuate the actuator, and thereby cause mechanical displacement of the haptic interaction element 101 . Hence , haptic feedback may be provided for a user interacting with the haptic feedback device 100 . For example , the user may sense the mechanical displacement with their finger when positioned on the haptic interaction element 101 .

[0063] In FIG . 2 , the input signal 200 comprises three regions : a first region 201 where the input s ignal 200 starts from 0 and reaches a normali zed input amplitude value of 1 , a second region 202 , where the input signal 200 is descending to a normalized input amplitude value of - 1 , and a third region 203 , wherein the input signal 200 again reaches the original value of 0 ("resting value" ) .

[0064] The purpose behind dividing the haptic input signal into three regions is that the signal behavior may be manipulated by an apparatus between these regions , to improve the quality of the haptic feedback response . For example , to reduce distortion, ringing or increase power efficiency, and maximi ze feedback amplitude , wherein feedback amplitude may be equated to the displacement of a surface ( i . e . , haptic feedback element ) .

[0065] An example embodiment of an input signal 200 may be generated by an input signal generation circuitry, for example . The input signal generation circuitry may comprise , for example , at least one processing unit such as a microcontroller unit (MCU) , an ARM-processor , an x86-processor , a Field- Programmable Gate-Array ( FPGA) , a co-processor, a controller, a digital signal processor ( DSP) , a processing circuitry with or without an accompanying DSP, an application specific integrated circuit (AS IC) , a hardware accelerator, a special-purpose computer chip or the l ike . The input s ignal 200 may be configured to control the actuator 105 of the example haptic feedback device 100 . The input signal 200 may be configured to change signal level within a wave period of the input signal at a first frequency in a first direction towards a first amplitude . This may be equated with the aforementioned first region 201 .

[0066] Furthermore , the input signal 200 may be further configured to change signal level within the wave period of the input signal at a second frequency in a second direction from the first amplitude to a second amplitude . This may be equated with the aforementioned second region 202 .

[0067] Finally, the input signal 200 may be further configured to change signal level within the wave period of the input signal at a lower frequency compared to the second frequency in the first direction from the second amplitude . This may be equated with the aforementioned third region 203 . The lower frequency at the third region 203 may correspond to the first frequency, or to a third frequency having a different value .

[0068] Additionally, the second frequency may be configured to be substantially equal to an eigenfrequency of a haptic interaction element of the haptic feedback device configured to be actuated using the input signal 200 . Further, the first frequency and / or the third frequency may be configured to be lower than the second frequency . For example , the second frequency may be substantially equal to a second eigenfrequency of the haptic interaction element . The first frequency and / or the third frequency may be substantially equal to a first eigenfrequency of the haptic interaction element , which is a lower frequency than the second eigenfrequency . However, the first frequency, the second frequency and the third frequency may be any frequencies within a desired haptic frequency band . Preferably, the second frequency is approximately the first eigenfrequency or the second eigenfrequency . The frequencies may also correspond to higher order eigenfrequencies ( from 3 to N) than the first or the second eigenfrequency . However, the first and the third frequencies are lower frequency or frequencies than the second frequency, e . g . , having a lower order eigenfrequency than the second frequency . The higher order eigenfrequency or frequencies may be selected, for example , when the lower order eigenfrequencies of a haptic interaction element to be actuated are below a haptic frequency band .

[0069] The eigenfrequency to be used may be determined based on a given value to the input generation circuitry . Alternatively, at least one of the first frequency, the second frequency or the third frequency may be tuned based on characteristics of the haptic interaction element and / or the haptic feedback device . The characteristics may comprise , for example , si ze and / or used material ( s ) . For example , if the eigenfrequency is not readily available , the eigenfrequency may be estimated based on one or more measurements of the haptic interaction element . The measurements may indicate one or more frequencies where resonance occurs . Hence , the input signal may be tuned for a haptic interaction element having unknown properties . The tuning may be performed, for example , by the input generation circuitry, or alternatively by a coupled control circuitry configured to perform the tuning . For example , the displacement values may be measured at different ( actuation) frequencies of the input signal . From the measurements , one or more resonances may be detected based on peak values of displacement and used to estimate the eigenfrequency . The chosen frequencies may be implementation specific .

[0070] The directions that are chosen for the input signal 200 may not affect the outcome of the displacement of a haptic feedback device , depending on the design of the haptic feedback device itself . However , the second direction i s oppos ite to the f irst direction . For example , the input signal may be configured to rise ( towards positive maximum value ) in the first direction and descend ( towards negative maximum value ) in the second direction , or vice versa . The frequency, according to which a rate of change of a waveform of the input signal is configured, may be modified to change when an amplitude of signal level of the input signal is reached .

[0071] The input signal 200 , when operating on the first region 201 , may generally be understood as a portion of a sinewave -like signal ( a half PI wavelength) . Rate of change of the input signal during in the first region 201 may be at least partially slower, than a respective sinewave that is operating on the first frequency . Moreover, the rate of change of the input signal in the first region is slower than the rate of change of the input signal in the second region .

[0072] For example , a pure sine wave with an amplitude of 1 , which takes a time of 3 . 5 ms to reach the peak amplitude ( a quarter of a full period) , would have a frequency of approximately 71 Hz , but the input s ignal 200 during the first region 201 may have a slightly slower slope when the signal starts at an addressed location 210 in FIG . 2 ( time between 0 to 1 ms ) , and when it reaches the amplitude of 1 at approximately 3 . 5 ms at the addressed location 211 when compared to a regular (pure ) sinewave of a frequency of 71 Hz .

[0073] The input signal 200 may be smoothed in the first region . In terms of frequency components of a signal , a smoothing operation may act as a low-pass filter, reducing the high-frequency components and passing the low-frequency components with little change . For example , the input signal generation circuitry may comprise a filter, such as a low-pass filter, for filtering at least a sine wave component of the first region 201 . The filter may be implemented with any suitable circuitry .

[0074] For example , in the first region 201 , the sinewave -like portion may comprise a sinewave, that is modified by the input signal generation circuitry to have less-steep slopes on the addressed locations 210 and 211 . This may be done by a s ignal editor software , it may be done mathematically (e . g . , based on appropriate code ) , or it may be done by an Al algorithm or the like , that is trained to optimi ze signals for certain behaviors .

[0075] Alternatively, or additionally, the input signal 200 during the first region 201 may be generated purely mathematically as , for example , a combination of sinewaves and / or constant factors , a multiplication of sinewaves and / or constant , a division of sinewaves and / or constants factors and the like .

[0076] The input signal 200 during the second region 202 i s then configured to the second frequency and the second direction . The input signal 200 during the second region 202 may comprise a portion of a sinewave which has a rate of change that is faster than the rate of change of the input signal 200 during the f irst region 201 . In other words , the input signal may have a steeper slope for the waveform in the second region . The second frequency may comprise approximately an eigenfrequency of the haptic interaction element to be operated . The portion of a sinewave during the second region 202 may comprise a pure sinewave , e . g . , it may not necessarily be modif ied as was the case in an example of the input signal 200 during the first region 201 .

[0077] The input signal 200 during the third region 203 may be configured to the first frequency, or it may be configured to a third frequency, and the first direction similarly as in the first region 201 . For example , the input signal may comprise a sinewave -like portion, which has a rate of change that is at least partially slower, than the rate of change of the input signal in the second region . Similarly, to the first region 201 , addressed locations 230 and 231 may comprise smoothed sinewave -like portions . The third frequency may or may not correspond to the first frequency, however, it is configured to be a lower frequency than the second frequency .

[0078] As mentioned, the input signal may be configured to have a slower rate of change during the first and the third region compared to the rate of the change of the input signal during the second region . In other words , a voltage level of the input signal may change slower during the first / third region than in the second region within same time period . The first , second and third region may be di stinguished by the change of direction of the signal with respect to a voltage level change . The first , second and third regions may be also referred to as a first , second and third portion of a wavelength of the input signal , respectively . Alternatively, the first , second and third regions may be referred to as a first , second and third portion of a (wave ) period of the input signal , respectively . The second portion of the wave period may be shorter than the first and the third portion of the wave period . The input signal 200 may be utilized to reduce distortion and / or ringing . Next , the input signal 200 is compared to alternative input signals of a haptic feedback device to illustrate the reduced distortion and / or ringing which may be achieved with the proposed configuration . FIG . 3A illustrates two measured signals : i ) an input signal 301 , which comprises a pure sinewave (e . g . , sin(2n:ft) , where f= frequency and t=time ) and that drives a haptic feedback device , causing ii ) a displacement response 302 at a haptic interaction element . In FIG . 3A, the displacement response 302 shows noticeable ringing at 310 after the input signal 301 has been driven to 0 . Each division in x-axis is 5 ms long .

[0079] FIG . 3B illustrates a case of the same measurement setup as in FIG . 3A, however, in thi s case a square-wave input signal 303 drives the same haptic feedback device . The displacement response 304 shows noticeable distortion at the peak displacement areas , and unwanted ringing at 311 , which may be unpleasant to an operator using a device utilizing the haptic feedback device . This is generally due to the high harmonic nature of square-wave signals .

[0080] FIG . 3C illustrates a measurement setup, wherein an input signal 305 is generated according to an example embodiment . The input signal 305 may comprise sinewave components at the first region 201 and third region 203 at a slower frequency than in FIG . 3A, and a higher frequency at the second region . Due to the slower slope in the first region 201 and third region 203 , the displacement response 306 has a noticeably reduced ringing at 312 , when compared to the cases in FIG . 3A or FIG . 3B .

[0081] Finally, FIG . 3D illustrates a measurement setup, wherein the same haptic feedback device ( as in FIGs . 3A-C) is driven by an example embodiment of an input signal 307 . The input signal 307 may be configured similarly to the input signal 200 with smoothing at the start and end of the input signal. The displacement response 308 may have reduced ringing response at 313 compared to any previous example. In addition, while the displacement response 308 of FIG. 3D is better than the displacement response 306 of FIG. 3C, the input signal 306 of FIG. 3D is also faster (approximately total of 7.5 ms) when comparing to the total time of the input signal 305 in FIG. 3C (approximately 10 ms) . This reduction in the total time it takes to generate the signal may increase power efficiency and the speed an operator of a related haptic feedback device experiences the haptic feedback signal.

[0082] FIG. 4 illustrates an example of two haptic feedback input signals according to an example embodiment: SI 401 and S2 402. SI 401 comprises a second region 202 that is tuned to approximately 210 Hz, and S2 402 comprises a second region 202 that is tuned to approximately 156 Hz. In other words, FIG. 4A illustrates input signals tuned for different haptic feedback devices (different eigenfrequencies) . Here, tuning may refer to modifying one or more frequencies of one or more input signal components. For example, the input signal may comprise a composite signal. The input signal may comprise, for example, three sine wave components. The first sine wave component may be configured to a first frequency. The second sine wave component may be configured to a second frequency. The third sine wave component may be configured to the first frequency. Alternative, a third frequency having a different value than the first and the second frequencies can be used for the third sine wave component, as describer earlier. At least the first and the third sine wave components may be smoothed. The three sine wave components may be added together in three phases, resulting the input signal. Hence, the input signals 401 and 402 may have steeper descending slope than ascending slopes and less distortion, resulting in improved haptic feedback . For example , the faster signal level rate of change between amplitudes of the signal level may cause a haptic interaction element to have faster and greater displacement with respect to an initial position of the haptic interaction element at a start of the respective region compared to the displacement caused by the input signal before reaching the first amplitude and after the second amplitude .

[0083] FIG . 5 illustrates an example embodiment of an apparatus 500 configured to practice one or more example embodiments .

[0084] The apparatus 500 may comprise at least one processor 502 , that may be configured to generate example embodiments of the input signal 200 . In addition, the apparatus 500 may comprise at least one memory 504 comprising computer program code 506 . The at least one memory 504 may comprise signal data , such as example embodiments of the input signal 200 for haptic feedback . Alternatively, the computer program code 506 may comprise computer code instructions ( such as ARM- or x86 ) that instructs the at least one processor 502 to generate the output signal . The apparatus 500 may also comprise I / O -module 508 , that may be used to provide example embodiments to a haptic feedback device . The I / O -module 508 may comprise a DAO (digital-to- analog converter) that takes a digital form of the haptic feedback input signal 200 provided by the at least one processor 502 and converts it to an analog signal for a haptic feedback device , such as the haptic feedback device 100 .

[0085] The apparatus 500 may comprise , for example , the apparatus 109 . The apparatus 500 may comprise means for generating an input signal to a haptic feedback device . The means may comprise , for example , the input signal generation circuitry 110 . The means may further comprise the control circuitry 111 . In an embodiment , the apparatus 500 comprises a haptic feedback device . In an example embodiment , the apparatus 500 may comprise the haptic feedback device 100 and the apparatus 109 . In addition, the apparatus 500 may comprise a user device , such as a mobile phone, a tablet , a television, a vehicle , a wearable device , a screen, a display or the like , configured to interact with a user with haptic feedback .

[0086] For example , the apparatus 500 may comprise a cellphone , wherein for example, a main processor of the cellphone handles the input signal 200 generation, or alternatively the cellphone may comprise a smaller DSP comprising low latency ( fast response ) due to optimi zed instruction set and / or fast buffer memory modules unit that may either comprise instruction to generate the input signal 200 or comprise the input signal 200 itself .

[0087] According to an example embodiment , the apparatus 500 may be configured to tune the input signal 200 for haptic feedback based on characteristics of the haptic feedback device . For example , the apparatus 500 may be configured to tune the input signal 200 during the first region 201 and third region 203 approximately to a first eigenfrequency of the respective haptic feedback device . This may reduce the required energy to drive the haptic feedback device to a desired displacement value during the first and / or third region 201 , 203 . Furthermore , the apparatus 500 may be configured to tune the input signal 200 during the second region 202 to a second eigenfrequency of the haptic feedback device . Hence , a well-defined haptic feedback signal may be achieved for improved haptic feedback to a user . The first and the second eigenfrequency may result a more optimal outcome (e . g . , maximi zed displacement response ) , however, the frequencies may be freely selected and comprise for example higher order eigenfrequencies without losing the effect of reduced distortion and improved haptic feedback .

[0088] In an embodiment , the apparatus 500 may be configured to obtain data indicative of one or more eigenfrequencies of a haptic interaction element . The data may comprise , for example , measurement data comprising displacement response of a haptic interaction element with respect to actuation frequencies . Based on the measurement data, the apparatus 500 may be configured to determine at least one of the first or the second frequency . For example , the apparatus 500 may select one or more frequencies corresponding to highest displacement values to tune the input signal .

[0089] FIG . 6 illustrates an example of measurement data indicative of resonance / eigenf requency of a measured component according to an example embodiment . The measurement data may comprise measured frequency response of a haptic feedback device , showing displacement response of a haptic interaction element of the haptic feedback device when actuated with one or more frequencies . The measurement may be done at one or more locations of the haptic interaction element , such as a panel . In this example , the measurements are done on three different locations on the device . The topmost frequency response is measured on a center of the panel showing one eigenfrequency 610 at 110 Hz and second eigenfrequency 612 at 165 Hz . Hence , the region 201 and the third region 203 may be tuned to 110 Hz , and the second region 202 may be tuned to 165 Hz . The selected frequencies may not need to be exactly the eigenfrequencies , and it may be sufficient to an approximate value .

[0090] However, not all haptic feedback devices may have eigenfrequencies in so called "haptic region" or haptic frequency band, which is generally a frequency band comprising of frequencies that provide a good haptic response to a user . The haptic region may be defined as 150 - 180 Hz , where human skin is the most sensitive and the frequency is still low enough that it may not produce any audible sound due to the dimensions of the haptic feedback device . However, the first eigenfrequency of this example may be used to reduce the required input power of the example embodiment , as the haptic feedback device may use the natural resonance to increase the displacement . The haptic frequency band may be also defined to be wider, such as 20 -250 Hz , depending on a use case . An apparatus configured to generate the input signal may be provided with haptic frequency band parameters for the frequency selection . When the eigenfrequencies are not located within the desired haptic frequency band, the first frequency and the second frequency may be selected to have any values within the haptic frequency band, as long as the second frequency is substantially higher than the first frequency . For example , the frequencies can be selected based on the provided displacement response data such that frequencies with highest displacement are selected even if they are not resonant frequencies . When other frequencies than the eigenfrequencies are used, the achieved displacement may be lower but accuracy and speed of the haptic feedback may still be improved .

[0091] FIG . 7A illustrates an example of measured results of a surface of a haptic feedback device , when excited with a single-cycle square-wave impulse of 165 Hz as shown at 701 . A measured acceleration of the surface displacement is shown at 702 , and finally at the di splacement response i s shown at 703 . Due to the high frequency content of the square-wave , the acceleration response is very uneven at 704 , as the surface tries to respond to the high frequency content of the squarewave edges . This may cause high frequency mechanical noi se ( F=ma, wherein acceleration has a high value and high frequency) . Force F is therefore high and may be capable to shake mechanical clearances which exist in real world configurations .

[0092] FIG . 7B illustrates an example of measured results of the same haptic feedback device as in FIG . 7A, when excited with a single-cycle sinewave impulse of 165 Hz as shown at 711 . A measured acceleration of the surface displacement is shown at 712 and the displacement response is shown at 713 . The acceleration response , while clearer than with the square-wave example of FIG . 7A, there is still an uneven acceleration response at the start and end of the sinewave impulse , as the sudden start and stop of the signal causes unwanted high frequency content and noise .

[0093] FIG . 7C illustrates an example of measured results of the haptic feedback device of the FIG . 7A and 7B, when excited with a haptic feedback input signal 200 according to an example embodiment , shown at 721 , where the input signal 200 during the first region 201 and the third region 203 is tuned approximately to 110 Hz , and the input signal 200 during second region 202 i s tuned approximately to 165 Hz . The acceleration response is shown at 722 and the di splacement response is shown at 723 . The acceleration response shows cleaner response at both the start and end of the impulse ( compared to FIGS . 7A and 7B) , as unwanted frequency components are removed ( filtered out ) from the impulse , and the actuated surface of the haptic feedback device may not have to follow abrupt changes .

[0094] FIG . 8 i llustrates an example of a method for reducing distortion of a haptic feedback device according to an example embodiment . The method may further enable increasing displacement of a haptic feedback element of the haptic feedback device . Hence , haptic feedback may be improved when actuated with an input signal generated with the method . The method may be performed, for example , by the apparatus 109 or the apparatus 500 . At 800 , the method may comprise generating the input signal for an actuator of the haptic feedback device , wherein signal level of the input signal is configured to change at a higher frequency in a descending or ascending direction of a wave form of the input signal between two consecutive amplitudes of the input signal compared to the signal level change in an opposite direction of the waveform before and after the two consecutive amplitudes . The signal level may be configured to change in a descending or ascending direction of a wave form of the input signal at a first frequency . The first frequency may be conf igured to be substantially lower compared to a second frequency . The second frequency may be configured for a direction opposite to the descending or ascending direction . The second frequency may be configured to be substantially equal to an eigenfrequency of a haptic interaction element of the haptic feedback device configured to be actuated using the input signal . The waveform may be configured to return to a baseline ( e . g . zero level of the signal level , from which level the waveform started) at a third frequency, wherein the third frequency is lower than the second frequency . The third frequency may correspond to the second frequency . The first / third frequency may be substantially equal to an eigenfrequency of the haptic interaction element , wherein the eigenfrequency corresponding to the first frequency i s a lower eigenfrequency than of the second frequency . The method may further comprise filtering the input signal at least at the portions of the first / third frequency to smoot the input signal , for example , at a start and at an end of the waveform .

[0095] At 802 , the method may comprise providing the input signal to the haptic feedback device . The input signal may be configured to actuate a haptic interaction element of the haptic feedback device . Hence , improved haptic feedback may be provided for a user of the haptic feedback device .

[0096] Further features of the method directly result for example from the functionalities and parameters of the devices 100 , 109 , or 500 as described in the appended claims and throughout the specification, and are therefore not repeated here . Different variations of the methods may be also applied, as described in connection with the various example embodiments .

[0097] It is obvious to a person skil led in the art that with the advancement of technology, the example embodiments may be implemented in various ways . The example embodiments are thus not limited to the examples described above ; instead they may vary within the scope of the claims .

[0098] An apparatus may be configured to perform or cause performance of any aspect of the methods described herein . Further, a computer program or a computer program product may comprise instructions for causing, when executed, an apparatus to perform any aspect of the methods described herein . Further, an apparatus may comprise means for performing any aspect of the method ( s ) described herein . According to an example embodiment , the means comprises at least one processor, and at least one memory including program code , the at least one processor, and program code configured to , when executed by the at least one processor, cause performance of any aspect of the method ( s ) . The means may comprise the structural elements described herein .

[0099] Any range or device value given herein may be extended or altered without losing the effect sought . Also , any embodiment may be combined with another embodiment unless explicitly disallowed .

[0100] Although the subj ect matter has been described in language specific to structural features and / or acts , it is to be understood that the subj ect matter defined in the appended claims is not necessarily limited to the specific features or acts described above . Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims .

[0101] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages . It will further be understood that reference to ' an ' item may refer to one or more of those items .

[0102] The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate . Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subj ect matter described herein . Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought .

[0103] The term ' comprising ' is used herein to mean including the method, blocks , or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements .

[0104] Although subj ects may be referred to as ' first ' or ' second' subj ects , this does not necessarily indicate any order or importance of the subj ects . Instead, such attributes may be used solely for the purpose of making a difference between subj ects .

[0105] As used in this application, the term ' circuitry' may refer to one or more or of the following : ( 1 ) hardware-only circuit implementations ( such as for example implementations in only analog and / or digital circuitry) and ( 2 ) combinations of hardware circuits and software, for example: (i) a combination of analog and / or digital hardware circuit (s) with sof tware / f irmware and (ii) any portions of hardware processor (s) with software (e.g. digital signal processor ( s ) ) , software, and memory (ies) that work together to cause an apparatus to perform the various example embodiments and (3) hardware circuit (s) and or processor ( s ) , such as a microprocessor ( s ) or a portion of a microprocessor ( s ) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0106] It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from scope of this specification.

Claims

CLAIMS1 . A method, the method comprising : generating an input signal ( 200 ) for an actuator ( 105 ) of a haptic feedback device ( 100 ) , wherein the input signal ( 200 ) is composed of three sine wave components added together in three phases , wherein a first sine wave component and a third sine wave component are configured to a lower frequency than a second sine wave component and wherein at least the second sine wave component is configured to approximately an eigenfrequency of a haptic interaction element ( 101 ) of the haptic feedback device ( 100 ) configured to be actuated using the input signal ( 200 ) , such that signal level of the input signal within a wave period is configured to have a faster rate of change between two consecutive amplitudes of the signal level of the input signal compared to a signal level rate of change before and after the two consecutive amplitudes ; and providing the input signal to the haptic feedback device .2 . The method of claim 1 , wherein the signal level changes at a first frequency configured for the first sine wave component before reaching a first amplitude of the consecutive amplitudes , at a second frequency configured for the second sine wave component between the consecutive amplitudes , and at a third frequency configured for the third sine wave component after reaching a second amplitude of the consecutive amplitudes , and wherein the second frequency is higher than the first frequency and the third frequency .3 . The method of claim 2 , wherein the second frequency is configured to be substantially equal to an eigenfrequency of a haptic interaction element ( 101 ) ofthe haptic feedback device to be actuated, and at least one of the first frequency or the third frequency is configured to be substantially equal to a lower order eigenfrequency of the haptic interaction element ( 101 ) than the second frequency .4 . The method of any preceding claim, further comprising : obtaining data indicative of one or more eigenfrequencies of the haptic interaction element ; and configuring at least one of the frequencies based on the data .5 . The method of claim 4 , wherein the data comprise one or more measurements of displacement of the haptic interaction element with respect to an actuation frequency; and the method comprises configuring at least one of the frequencies at a frequency resulting in approximately highest displacement .6 . The method of any preceding claim, comprising : performing smoothing of at least the first and the third sine wave components .7 . An apparatus ( 500 ) comprising an input signal generation circuitry configured to : generate an input signal ( 200 ) for an actuator ( 105 ) of a haptic feedback device ( 100 ) , wherein the input signal ( 200 ) is composed of three sine wave components added together in three phases , wherein a first sine wave component and a third sine wave component are configured to a lower frequency than a second sine wave component and wherein at least the second sine wave component is configured to approximately an eigenfrequency of a haptic interaction element ( 101 ) of the haptic feedback device ( 100 ) such that signal level of the input signal within a waveperiod is configured to change at a faster rate of change between two consecutive amplitudes of the signal level of the input signal compared to a signal level rate of change before and after the two consecutive amplitudes ; and provide the input signal to the actuator of the haptic feedback device .8 . The apparatus of claim 7 , wherein the signal level is configured to change at a first frequency configured for the first sine wave component before reaching a first amplitude of the consecutive amplitudes , at a second frequency configured for the second sine wave component between the consecutive amplitudes , and at a third frequency configured for the third sine wave component after reaching a second amplitude of the consecutive amplitudes , and wherein the second frequency is higher than the first frequency and the third frequency .9 . The apparatus ( 500 ) of claim 8 , wherein the second frequency is configured to be substantially equal to an eigenfrequency of a haptic interaction element of the haptic feedback device to be actuated, and at least one of the first frequency or the third frequency is configured to be substantially equal to a lower order eigenfrequency of the haptic interaction element than the second frequency .10 . The apparatus ( 500 ) of any of claims 7 to 9 , wherein the apparatus further comprises a control circuitry configured to : obtain data indicative of one or more eigenfrequencies of the haptic interaction element ; and configure at least one of the frequencies based on the data .

11. The apparatus (500) of claim 10, wherein the data comprises one or more measurements of displacement of the haptic interaction element (101) with respect to an actuation frequency; and at least one of the frequencies is configured at a frequency resulting in approximately highest displacement.

12. The apparatus (500) of any of claims 7 to 11, wherein the input signal generation circuitry is configured to perform smoothing of at least the first and the third sine wave components.

13. The apparatus of any of claims 7 to 12, wherein the apparatus (500) comprises the haptic feedback device (100) .

Images