Method and system for in-system estimation of actuator parameters

Abstract

A method for estimating actuator parameters of an actuator in situ and in real time may include: driving the actuator with a test signal that is imperceptible to a user of the device including the actuator during real-time operation of the device, measuring a voltage and a current associated with the actuator and caused by the test signal, determining one or more parameters of the actuator based on the voltage and current, determining an actuator type of the actuator based on the one or more parameters, and controlling a playback signal to the actuator based on the actuator type.

Description

Technical Field

[0001] The present disclosure generally relates to in-system detection of parameters associated with electromagnetic actuators, such as linear resonant actuators or tactile transducers. Background Art

[0002] Vibrotactile transducers, such as linear resonant actuators (LRA), are widely used in portable devices such as mobile phones to generate vibration feedback to users. Various forms of vibrotactile feedback produce different tactile sensations on the user's skin and can play an increasingly important role in human-computer interaction in modern devices.

[0003] LRA can be modeled as a mass-spring electromechanical vibration system. When driven with a properly designed or controlled drive signal, LRA can generate certain desired forms of vibration. For example, a clear and noticeable vibration pattern on a user's finger can be used to produce a feeling that mimics the click of a mechanical button. This noticeable vibration can then be used as a virtual switch to replace a mechanical button.

[0004] Figure 1 An example of a vibrotactile system in a device 100 is shown. The device 100 may include a controller 101 configured to control a signal applied to an amplifier 102. The amplifier 102 may then drive a tactile transducer 103 based on the signal. The controller 101 may be triggered by a trigger to output a signal. The trigger may, for example, include a pressure sensor or force sensor on a screen or virtual button of the device 100.

[0005] Among various forms of vibrotactile feedback, tonal vibrations of duration can play an important role in notifying the user of a device of certain predefined events, such as incoming calls or messages, emergency alerts, and timer warnings, etc. In order to effectively generate tonal vibration notifications, it may be desirable to operate the tactile actuator at its resonant frequency.

[0006] The resonant frequency f0 of the tactile transducer can be approximately estimated as:

[0007]

[0008] Where C is the compliance of the spring system, and M is the equivalent moving mass, which can be determined based on the actual moving parts in the tactile transducer and the mass of the portable device holding the tactile transducer.

[0009] The vibration resonance of a tactile transducer may vary over time due to sample-to-sample variations of individual tactile transducers, mobile device component variations, temporal component variations due to aging, component variations due to self-heating, and usage conditions such as the varying strength with which a user grips the device.

[0010] Figure 2A An example of a linear resonant actuator (LRA) modeled as a linear system including a mass-spring system 201 is shown. LRAs are nonlinear components that may behave differently depending on, for example, applied voltage levels, operating temperature, and operating frequency. However, under certain conditions, these components can be modeled as linear components.

[0011] Figure 2B An example of an LRA modeled as a linear system is shown, including an electrical equivalent model of the mass-spring system 201 of the LRA. In this example, the LRA is modeled as a third-order system with electrical and mechanical elements. In particular, Re and Le are the DC resistance of the coil-magnet system and the coil inductance, respectively; and Bl is the magnetic factor of the coil. The drive amplifier outputs a voltage waveform V(t) having an output impedance Ro. The terminal voltage V can be sensed across the terminals of the tactile transducer T (t). The mass-spring system 201 moves with a velocity u(t).

[0012] An electromagnetic load such as an LRA can be LRA To characterize, such as coil impedance Z coil and mechanical impedance Z mech The sum is shown as:

[0013] Z LRA =Z coil + Z mech (2)

[0014] Coil impedance Z coil Then a direct current (DC) resistor Re may be included in series with the inductor Le:

[0015] Z coil =Re+s*Le (3)

[0016] Mechanical impedance Z mech It can be defined by three parameters: the resistance Res at resonance, which represents the resistance of the mechanical friction of the mass-spring system representing the tactile transducer, the capacitance Cmes, which represents the capacitance of the equivalent moving mass M of the mass-spring system representing the tactile transducer, and the inductance Lces, which represents the compliance C of the mass-spring system of the tactile transducer. The electrical equivalent of the total mechanical impedance is the parallel connection of Res, Cmes, and Lces. The Laplace transform of this parallel connection is described as:

[0017]

[0018] The resonant frequency f0 of the tactile transducer can be expressed as:

[0019]

[0020] The quality factor Q of LRA can be expressed as:

[0021]

[0022] Referring to equation (6), this expression involves a sub-expression describing the parallel connection of resistors Re and Res (ie, ), and Figure 2B In Figure 1, these resistors are shown connected in series, which may not seem intuitive. However, this may be the case where the drive voltage Ve is oscillating but then suddenly switches off and becomes zero. Figure 2B The voltage amplifier shown in can be considered to have low source impedance, ideally zero source impedance. Under these conditions, when the drive voltage Ve becomes zero, the voltage amplifier virtually disappears from the circuit. At this point, Figure 2B The topmost terminal of the resistor Re and the bottommost terminal of the resistor Res are grounded, and thus the resistors Re and Res are actually connected in parallel, as reflected in equation (6).

[0023] Electromagnetic transducers, such as LRAs or microspeakers, may have slow response times. Figure 3 is a graph of an example response of an LRA, depicting an example drive signal for the LRA, a current through the LRA, and a back electromotive force (back EMF) of the LRA, where such back EMF may be proportional to the velocity of a moving element (eg, a coil or magnet) of the transducer. Figure 3 As shown in FIG. 1 , the rise time of the back EMF may be slow as energy is transferred to the LRA, and some "ringing" of the back EMF may occur after the drive signal ends as the mechanical energy stored in the LRA is released. In the context of a tactile LRA, this behavior may result in a "mushy" click or pulse sensation rather than a "crisp" tactile response. Therefore, it may be desirable to have an LRA with something like Figure 4 The response shown, where there is minimal ringing after the drive signal has ended, and can provide a more "crisp" tactile response in a tactile context. Therefore, it may be desirable to process the drive signal so that when the processed drive signal is applied to the transducer, the velocity or back EMF of the transducer is closer to the velocity of the transducer. Figure 4 speed or back EMF. Note that by Figure 4 Inclusion in the Background section does not intend to admit that Figure 4 The optimized waveform is the prior art.

[0024] In order to optimize the performance of an LRA or other actuator to generate a more desired response, the transducer drive system may need to apply optimized tuning parameters for a given actuator model, which traditionally may require implementation of an expensive factory calibration procedure. Therefore, it may be desirable to reduce factory calibration by seamlessly performing actuator parameter measurements during system power-up or during actuator use without affecting the user experience.

[0025] The human tactile system is particularly sensitive to frequencies in the range of 100-400Hz. Therefore, LRAs are typically designed to have resonant frequencies in the range of 150Hz-250Hz. In most cases, this resonant characteristic means a relatively large acceleration rise time. In addition, after the mass of the LRA is set in motion, reducing the amplitude of the input voltage may not instantly reduce the amplitude of the mass's motion. Instead, the mass's motion will slowly decay. By using optimized tuning parameters, the LRA algorithm can achieve consistent acceleration across multiple LRA samples, reduce rise / braking times, and / or enhance the end-user's experience of tactile effects. Summary of the invention

[0026] According to the teachings of the present disclosure, disadvantages and problems associated with determining parameters related to electromagnetic actuators may be reduced or eliminated.

[0027] According to an embodiment of the present disclosure, a method for estimating actuator parameters of an actuator in situ and in real time may include: during real-time operation of the device, driving the actuator with a test signal that is imperceptible to a user of the device including the actuator, measuring a voltage and a current associated with the actuator and caused by the test signal, determining one or more parameters of the actuator based on the voltage and the current, determining an actuator type of the actuator based on the one or more parameters, and controlling a playback signal to the actuator based on the actuator type.

[0028] According to an embodiment of the present disclosure, a system for estimating actuator parameters of an actuator in situ and in real time may include: a test signal generator, which is configured to generate a test signal that is imperceptible to a user of a device including an actuator so as to drive the actuator during real-time operation of the device; and a measurement subsystem, which is configured to measure a voltage and a current associated with the actuator and caused by the test signal, determine one or more parameters of the actuator based on the voltage and the current, determine an actuator type of the actuator based on the one or more parameters, and control a playback signal to the actuator based on the actuator type.

[0029] The technical advantages of the present disclosure will be apparent to those skilled in the art from the drawings, descriptions and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features and combinations particularly pointed out in the claims.

[0030] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the claims set forth in the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] A more complete understanding of the present embodiments and their advantages may be obtained by referring to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals indicate like features, and wherein:

[0032] Figure 1 An example of a vibrotactile system in a device known in the art is shown;

[0033] Figure 2A and Figure 2B Each shows an example of a linear resonant actuator (LRA) known in the art modeled as a linear system;

[0034] Figure 3 A graph showing an example waveform of an electromagnetic load known in the art;

[0035] Figure 4 A graph showing an example desired waveform of an electromagnetic load according to an embodiment of the present disclosure;

[0036] Figure 5 A block diagram illustrating selected components of an example mobile device according to an embodiment of the present disclosure;

[0037] Figure 6 A block diagram illustrating selected components of an example integrated haptic system according to an embodiment of the present disclosure;

[0038] Figure 7 shows selected components of an example system including an electromagnetic load according to an embodiment of the present disclosure;

[0039] Figure 8 A circuit diagram showing an example implementation of a sense resistor for measuring current according to an embodiment of the present disclosure; and

[0040] Fig. 9 A flow chart illustrating an example method of in-system estimation of actuator parameters and compensation thereof according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0041] The following description sets forth example embodiments according to the present disclosure. Further example embodiments and implementations will be apparent to those of ordinary skill in the art. In addition, those of ordinary skill in the art will recognize that various equivalent technologies may be applied to replace or combine the embodiments discussed below, and all such equivalents should be deemed to be included in the present disclosure.

[0042] Various electronic devices or smart devices may have transducers, speakers, and acoustic output transducers, such as any transducer for converting a suitable electrical drive signal into an acoustic output (such as an acoustic pressure wave or a mechanical vibration). For example, many electronic devices may include one or more speakers or loudspeakers for sound generation, such as for playback of audio content, voice communication, and / or for providing audible notifications.

[0043] Such a speaker or microphone may include an electromagnetic actuator, such as a voice coil motor, which is mechanically coupled to a flexible diaphragm, such as a conventional microphone cone, or which is mechanically coupled to a surface of the device, such as a glass screen of a mobile device. Some electronic devices may also include an acoustic output transducer capable of generating ultrasonic waves, such as for proximity detection type applications and / or machine-to-machine communications.

[0044] Many electronic devices may additionally or alternatively include more specialized acoustic output transducers, such as tactile transducers, which are customized to generate vibrations for tactile control feedback or notification to a user. Additionally or alternatively, the electronic device may have a connector, such as a socket, for removable mating connection with a corresponding connector of an accessory device, and may be arranged to provide a drive signal to the connector to drive one or more of the above-mentioned types of transducers of the accessory device when connected. Such an electronic device will therefore include a drive circuit for driving the transducer of the host device or connected accessory with a suitable drive signal. For acoustic or tactile transducers, the drive signal is typically an analog time-varying voltage signal, such as a time-varying waveform.

[0045] Figure 5 1 shows a block diagram of selected components of an example host device 502 according to an embodiment of the present disclosure. Figure 5 As shown, host device 502 may include housing 501 , controller 503 , memory 504 , force sensor 505 , microphone 506 , linear resonant actuator 507 , radio transmitter / receiver 508 , speaker 510 , and integrated haptic system 512 .

[0046] Housing 501 may include any suitable housing, shell, or other enclosure for housing the various components of host device 502. Housing 501 may be constructed of plastic, metal, and / or any other suitable material. In addition, housing 501 may be adapted (e.g., sized and shaped) to make host device 502 easily transportable on the person of a user of host device 502. Thus, host device 502 may include, but is not limited to, a smartphone, a tablet computing device, a handheld computing device, a personal digital assistant, a laptop computer, a video game controller, or any other device that can be easily transported on the person of a user of host device 502.

[0047] Controller 503 may be housed within housing 501 and may include any system, device or apparatus configured to interpret and / or execute program instructions and / or process data, and may include but is not limited to a microprocessor, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), or any other digital or analog circuit configured to interpret and / or execute program instructions and / or process data. In some embodiments, controller 503 interprets and / or executes program instructions and / or processes data stored in memory 504 and / or other computer-readable media accessible to controller 503.

[0048] The memory 504 may be housed within the housing 501, may be communicatively coupled to the controller 503, and may include any system, device, or means (e.g., a computer-readable medium) configured to retain program instructions and / or data for a period of time. The memory 504 may include random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a personal computer memory card international association (PCMCIA) card, flash memory, magnetic storage, optical magnetic storage, or any suitable selection and / or array of volatile or non-volatile memory that retains data after power to the host device 502 is turned off.

[0049] Microphone 506 may be at least partially housed within housing 501, may be communicatively coupled to controller 503, and may include any system, device, or apparatus configured to convert incoming sound at microphone 506 into an electrical signal that may be processed by controller 503, wherein such sound is converted into an electrical signal using a diaphragm or membrane having a capacitance that varies based on acoustic vibrations received at the diaphragm or membrane. Microphone 506 may include an electrostatic microphone, a condenser microphone, an electret microphone, a microelectromechanical system (MEMS) microphone, or any other suitable condenser microphone.

[0050] The radio transmitter / receiver 508 may be housed within the housing 501, may be communicatively coupled to the controller 503, and may include any system, device, or apparatus configured to generate and transmit radio frequency signals with the aid of an antenna, and to receive radio frequency signals and convert information carried by such received signals into a form usable by the controller 503. The radio transmitter / receiver 508 may be configured to transmit and / or receive various types of radio frequency signals, including, but not limited to, cellular communications (e.g., 2G, 3G, 4G, LTE, etc.), short-range wireless communications (e.g., Bluetooth), commercial radio signals, television signals, satellite radio signals (e.g., GPS), Wi-Fi, etc.

[0051] The speaker 510 may be at least partially contained within the housing 501, or may be external to the housing 501, may be communicatively coupled to the controller 503, and may include any system, device, or apparatus configured to produce sound in response to an electrical audio signal input. In some embodiments, the speaker may include a dynamic loudspeaker that employs a lightweight diaphragm mechanically coupled to a rigid frame via a flexible suspension that constrains a voice coil to move axially through a cylindrical magnetic gap. When an electrical signal is applied to the voice coil, the current in the voice coil generates a magnetic field, causing it to become a variable electromagnet. The magnetic systems of the coil and the driver interact to generate mechanical forces that cause the coil (and the cone attached thereto) to move back and forth, thereby reproducing sound under the control of an applied electrical signal from an amplifier.

[0052] The force sensor 505 may be housed within the housing 501 and may include any suitable system, device or apparatus for sensing force, pressure or touch (e.g., interaction with a person's finger) and generating an electrical signal or electronic signal in response to such force, pressure or touch. In some embodiments, such an electrical signal or electronic signal may be a function of the magnitude of the force, pressure or touch applied to the force sensor. In these and other embodiments, such an electronic signal or electronic signal may include a general purpose input / output signal (GPIO) associated with an input signal to which tactile feedback is given. The force sensor 505 may include, but is not limited to, a capacitive displacement sensor, an inductive force sensor (e.g., a resistor-inductor-capacitive sensor), a strain gauge, a piezoelectric force sensor, a force sensing resistor, a piezoelectric force sensor, a thin film force sensor, or a force sensor based on a quantum tunneling composite material. For the purpose of clarity and illustration in this disclosure, the term "force" used herein may refer not only to force, but also to a physical quantity indicating force or similar to force, such as, but not limited to, pressure and touch.

[0053] The linear resonant actuator 507 can be housed within the housing 501 and can include any suitable system, device, or apparatus for generating an oscillating mechanical force across a single axis. For example, in some embodiments, the linear resonant actuator 507 can rely on an AC voltage to drive a voice coil pressed against a moving mass connected to a spring. When the voice coil is driven at the resonant frequency of the spring, the linear resonant actuator 507 can vibrate with a perceptible force. Therefore, the linear resonant actuator 507 may be useful in tactile applications within a specific frequency range. Although, for the purpose of clarity and illustration, the present disclosure is described with respect to the use of the linear resonant actuator 507, it should be understood that any other type or types of vibration actuators (e.g., eccentric rotating mass actuators) can be used instead of the linear resonant actuator 507 or any other type or types of vibration actuators can be used in addition to the linear resonant actuator 507. Furthermore, it should also be understood that an actuator arranged to generate an oscillating mechanical force across multiple axes may be used in place of or in addition to the linear resonant actuator 507. As described elsewhere in this disclosure, the linear resonant actuator 507 may provide tactile feedback to a user of the host device 502 based on signals received from the integrated haptic system 512 for at least one of mechanical button replacement and capacitive sensor feedback.

[0054] The integrated tactile system 512 may be housed within the housing 501, may be communicatively coupled to the force sensor 505 and the linear resonant actuator 507, or may include any system, device, or apparatus configured to receive a signal from the force sensor 505 indicating a force applied to the host device 502 (e.g., a force applied by a human finger to a virtual button of the host device 502) and generate an electronic signal for driving the linear resonant actuator 507 in response to the force applied to the host device 502. Figure 6 Details of an example integrated haptic system according to embodiments of the present disclosure are depicted in FIG.

[0055] Although the specific example components above Figure 5 504, force sensor 505, microphone 506, radio transmitter / receiver 508, speaker(s) 510), but host device 502 according to the present disclosure may include one or more components not specifically listed above. Figure 5 Certain user interface components are depicted, but host device 502 does not include any Figure 5One or more other user interface components beyond those depicted (including but not limited to a keyboard, a touch screen, and a display) may also be included to allow a user to interact with and / or otherwise manipulate the host device 502 and its associated components.

[0056] Figure 6 1 shows a block diagram of selected components of an example integrated haptic system 512A according to an embodiment of the present disclosure. In some embodiments, the integrated haptic system 512A may be used to implement Figure 5 An integrated tactile system 512. Figure 6 As shown, the integrated haptic system 512A may include a digital signal processor (DSP) 602 , a memory 604 , and an amplifier 606 .

[0057] DSP 602 may include any system, device or apparatus configured to interpret and / or execute program instructions and / or process data. In some embodiments, DSP 602 may interpret and / or execute program instructions and / or process data stored in memory 604 and / or other computer-readable media accessible to DSP 602.

[0058] The memory 604 may be communicatively coupled to the DSP 602 and may include any system, device, or means (e.g., a computer-readable medium) configured to retain program instructions and / or data for a period of time. The memory 604 may include random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a Personal Computer Memory Card International Association (PCMCIA) card, flash memory, magnetic storage, optical-magnetic storage, or any suitable selection and / or array of volatile or non-volatile memory that retains data after power to the host device 502 is turned off.

[0059] Amplifier 606 may be electrically coupled to DSP 602 and may include a signal configured to increase the input signal V IN (e.g., a time-varying voltage or current) to generate an output signal V OUT Any suitable electronic system, device or apparatus. For example, amplifier 606 can use electrical power from a power supply (not explicitly shown) to increase the amplitude of the signal. Amplifier 606 can include any suitable amplifier class, including but not limited to a Class D amplifier.

[0060] In operation, memory 604 may store one or more haptic playback waveforms. In some embodiments, each of the one or more haptic playback waveforms may define a haptic response a(t) as a desired acceleration of a linear resonant actuator (e.g., linear resonant actuator 507) as a function of time. DSP 602 may be configured to receive a force signal V indicating a force applied to force sensor 505. SENSE In response to a force signal V indicating the sensed force SENSE In response to or independently of such reception, DSP 602 may retrieve a haptic playback waveform from memory 604 and process such haptic playback waveform to determine a processed haptic playback signal V IN In an embodiment where amplifier 606 is a class D amplifier, the processed haptic playback signal V IN In response to receiving a force signal V indicating the sensed force, a pulse width modulated signal may be included. SENSE , DSP 602 may cause the processed haptic playback signal V IN The processed haptic playback signal V is output to the amplifier 606, and the amplifier 606 can amplify the processed haptic playback signal V IN , to generate a tactile output signal V for driving the linear resonant actuator 507 OUT .

[0061] In some embodiments, the integrated haptic system 512A can be formed on a single integrated circuit, thereby achieving lower latency than existing methods of haptic feedback control. By providing the integrated haptic system 512A as part of a single monolithic integrated circuit, latency between the various interfaces and system components of the integrated haptic system 512 can be reduced or eliminated.

[0062] Figure 7 Selected components of an example system 700 including an electromagnetic load 701 according to an embodiment of the present disclosure are shown. System 700 may include or be integrated into, but is not limited to, a mobile device, a home application, a vehicle, and / or any other system, device, or apparatus including a human-machine interface. Electromagnetic load 701 may include any suitable load having a complex impedance, including but not limited to a tactile transducer, a microphone, a microspeaker, a piezoelectric transducer, a voice coil actuator, a solenoid, or other suitable transducer.

[0063] In operation, the signal generator 724 of the transducer drive subsystem 705 of the system 700 can generate a raw transducer drive signal x′(t) (which can be a waveform signal, such as a tactile waveform signal or an audio signal, in some embodiments). The raw transducer drive signal x′(t) can be generated based on the desired playback waveform received by the signal generator 724.

[0064] The raw transducer drive signal x′(t) may be received by a waveform preprocessor 726 , which may modify the raw transducer drive signal x′(t) based on one or more parameters generated by the impedance measurement subsystem 708 , wherein such one or more parameters may be associated with the electromagnetic load 701 .

[0065] The processed transducer driving signal x(t) can then be amplified by the amplifier 706 to generate a driving signal V(t) for driving the electromagnetic load 701. In response to the driving signal V(t), the sensing terminal voltage V T The sensed current I(t) may be sensed by a terminal voltage sensing block 707 (e.g., a voltmeter) and converted to a digital representation by a first analog-to-digital converter (ADC) 703. Similarly, the sensed current I(t) may be converted to a digital representation by a second ADC 704. The current I(t) may be sensed across a shunt resistor 702 having a resistance Rs coupled to the terminals of the electromagnetic load 701.

[0066] like Figure 7 As shown, the transducer drive subsystem 705 may include an impedance measurement subsystem 708 that may estimate the impedance of the electromagnetic load 701, including but not limited to the DC resistance Re and the coil inductance Le in the electromagnetic load 701. Based on such measurements, the impedance measurement subsystem 708 may transmit such parameters and / or any other suitable parameters (e.g., mechanical impedance parameters Res, Cmes, and Lces) to a waveform preprocessor 726. Based on such parameters, the waveform preprocessor 726 may modify the original transducer drive signal x′(t) in a manner intended to optimize the performance of the electromagnetic load 701 (e.g., modifying the driving or braking of the electromagnetic load to enhance the human perception of the crispness of the tactile effect).

[0067] Examples of methods for estimating one or more components of the electrical impedance and / or mechanical impedance of the electromagnetic load 701 are described in, but are not limited to, the following applications: U.S. patent application serial number 16 / 816,790, filed on March 12, 2020, and entitled “Methods and Systems for Improving Transducer Dynamics”; U.S. patent application serial number 16 / 816,833, filed on March 12, 2020, and entitled “Methods and Systems for Estimating Transducer Parameters”; U.S. patent application serial number 16 / 842,482, filed on April 7, 2020, and entitled “Thermal Model of Transducer for Thermal Protection and Resistance Estimation”; U.S. patent application serial number 16 / 369,556, filed on March 29, 2019, and entitled “Driver Circuitry”; and U.S. patent application serial number 16 / 369,556, filed on March 29, 2019, and entitled “Systems and Methods for Sensing Displacement of an Electromechanical Transducer"; all of which are incorporated herein by reference in their entirety.

[0068] For example, refer to Figure 2B , the velocity and position of the moving mass of the actuator can be respectively determined by the back EMF Vbemf (forward, called V B ) and I L Capture (e.g., back EMF V B Proportional to speed, and current I L is proportional to the position of the moving mass). Figure 2B The linear state-space model of the transducer model shown in is represented by the following equation:

[0069]

[0070]

[0071] in Figure 2B The voltage Ve of the transducer model shown in FIG. 1 can be determined by the sensing terminal voltage V TThus, the impedance measurement subsystem 708 can provide estimates of one or more internal parameters of the actuator, including the DC resistance Re, the coil inductance Le, the shunt mechanical resistance Res, the shunt capacitance Cmes, and / or the shunt inductance Lces, if measurements of the current and input voltage for the frequency region of interest are available.

[0072] To estimate such impedance parameters in situ, in operation, the impedance measurement subsystem 708 may generate a test signal (e.g., a pilot tone signal), and the waveform preprocessor 726 may combine such a test signal with the original transducer drive signal x′(t) to generate a processed transducer drive signal x(t), or may mute the original transducer drive signal x′(t) and generate the test signal as the processed transducer drive signal x(t). Such a test signal may have a transducer drive signal having a duration that is imperceptible to humans, an amplitude that is imperceptible to humans, and / or a frequency that is not typically used to excite the electromagnetic load 701 by the final application of the electromagnetic load 701 (e.g., a frequency that is significantly different from the resonant frequency of the electromagnetic load 701). Therefore, when the system 700 is operated and used in real time, the test signal may be imperceptible to a user of the system 700. For example, the imperceptible duration may be about 5 milliseconds. As another example, the imperceptible amplitude may be between about 170 millivolts and about 330 millivolts. Final Application of the Electromagnetic Load 701 Frequencies that are not typically used to excite the electromagnetic load 701 may depend on the type of electromagnetic load 701 and may vary based on the type of electromagnetic load 701 .

[0073] In addition, the impedance measurement subsystem 708 can measure the sensing terminal voltage V caused by driving the test signal to the electromagnetic load 701. T In addition, the impedance measurement subsystem 708 can estimate the parameters of the electromagnetic load 701 (e.g., DC resistance Re, coil inductance Le, parallel mechanical resistance Res, parallel capacitance Cmes and / or parallel inductance Lces) and transmit these parameters to the waveform preprocessor 726.

[0074] The waveform pre-processor 726 may then determine the type of electromagnetic load 701 present in the system 700 and, based thereon, perform optimized control of the raw transducer drive signal x′(t) to generate a processed transducer drive signal x(t).

[0075] Figure 8 FIG. 1 shows a circuit diagram of an example implementation of a sensing resistor 702 according to an embodiment of the present disclosure. Figure 8As shown, the sensing resistor 702 can be implemented using two optional resistors 802 and 803, where a switch 801 is used to select between the use of resistor 802 and resistor 803. The resistance of resistor 802 can be significantly higher than the resistance of resistor 803.

[0076] During playback of the test signal by the impedance measurement subsystem 708 and the waveform preprocessor 726, the tolerance for the voltage drop across the sense resistor 702 can be higher, which means that the resistance value R S It may be desirable to play a test signal only to increase the signal-to-noise ratio of the measurement of the sense current I(t) caused by the same voltage measurement device (e.g., second ADC 704) coupled to the terminals of the sense resistor 702. Therefore, the system 700 can operate in two different modes: a) a characterization mode, in which the larger resistor 802 is selected and the impedance measurement subsystem 708 measures the sense current I(t); and b) an activation mode, in which the smaller resistor 803 is selected (e.g., to have a smaller effect on the desired tactile operation of the electromagnetic load 701) and the expected human-perceptible waveform is driven to the electromagnetic load 701. Although not shown in detail in the figure, the impedance measurement subsystem 708 and / or another part of the transducer drive subsystem 705 can generate a control signal for operating the switch 801 to select between the resistor 802 and the resistor 803.

[0077] Fig. 9 A flow chart of an example method of in-system estimation of actuator parameters and compensation thereof according to embodiments of the present disclosure is shown. According to certain embodiments, method 900 may begin at step 902. As described above, the teachings of the present disclosure may be implemented in various configurations of system 700. Therefore, the preferred initialization point of method 900 and the order of the steps comprising method 900 may depend on the selected implementation.

[0078] At step 902, the system 700 may be powered on or reset. At step 904, after loading the firmware for implementing all or part of the transducer drive subsystem 705, the system 700 may enter the characterization mode, and the impedance measurement subsystem 708 may cause the test signal to be driven as the drive signal V(t) for driving the electromagnetic load 701. At step 906, the impedance measurement subsystem 708 may measure the sense terminal voltage V caused by driving the test signal to the electromagnetic load 701. T At step 908, the impedance measurement subsystem 708 may estimate parameters of the electromagnetic actuator 701 (e.g., DC resistance Re, coil inductance Le, parallel mechanical resistance Res, parallel capacitance Cmes, and / or parallel inductance Lces) and transmit these parameters to the waveform preprocessor 726.

[0079] At step 910, the waveform pre-processor 726 may determine the type of electromagnetic load 701 present in the system 700. At step 912, the system 700 may enter an active mode, wherein the waveform pre-processor 726 may perform optimization control of the raw transducer drive signal x′(t) to generate a processed transducer drive signal x(t).

[0080] although Fig. 9 A specific number of steps to be taken with respect to method 900 is disclosed, but it may be used in a manner similar to Fig. 9 The steps depicted in the figure may be performed in more or fewer steps. In addition, although Fig. 9 A particular order for steps to be taken with respect to method 900 is disclosed, but the steps comprising method 900 may be completed in any suitable order.

[0081] The method 900 may be implemented using the transducer drive subsystem 705, components thereof, or any other system operable to implement the method 900. In certain embodiments, the method 900 may be implemented partially or completely in software and / or firmware embodied in a computer-readable medium.

[0082] Although the foregoing discusses applications to linear electromagnetic loads, it should be understood that systems and methods similar or identical to the disclosed systems and methods may be applied to other linear or nonlinear systems.

[0083] As used herein, when two or more elements are referred to as being “coupled” to each other, the term means that the two or more elements are in electronic or mechanical communication, as the case may be, whether indirectly or directly, with or without intervening elements.

[0084] The present disclosure includes all changes, substitutions, changes, alterations and modifications to the example embodiments herein that will be understood by those of ordinary skill in the art. Similarly, where appropriate, the appended claims include all changes, substitutions, changes, alterations and modifications to the example embodiments herein that will be understood by those of ordinary skill in the art. In addition, in the appended claims, references to a device or system adapted to, arranged to, capable of, configured to, enabled to, operable to, or operable to perform a specific function or a component of a device or system include the device, system or component, regardless of whether it or the specific function is activated, turned on or unlocked, as long as the device, system or component is so adapted, arranged, capable of, configured to, enabled to, operable or operable. Therefore, without departing from the scope of the present disclosure, the systems, devices and methods described herein may be modified, added or omitted. For example, the components of the systems and devices may be integrated or separated. In addition, the operations of the systems and devices disclosed herein may be performed by more, less or other components, and the described methods may include more, less or other steps. In addition, the steps may be performed in any suitable order. As used in this document, "each" refers to each member of a set or each member of a subset of a set.

[0085] Although exemplary embodiments are shown in the drawings and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should not be limited in any way to the exemplary embodiments and techniques shown in the drawings and described above.

[0086] Unless specifically noted otherwise, items depicted in the drawings are not necessarily drawn to scale.

[0087] All examples and conditional language described herein are intended for teaching purposes to help readers understand the present disclosure and the concepts contributed by the inventors to promote the art, and are interpreted as not being limited to these specific examples and conditions. Although the embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions and modifications may be made thereto without departing from the spirit and scope of the present disclosure.

[0088] Although specific advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages. In addition, other technical advantages may become apparent to one of ordinary skill in the art after reviewing the foregoing drawings and descriptions.

[0089] To assist the Patent Office and any reader of any patent issuing from this application in interpreting the appended claims, Applicants wish to note that unless the phrase "means for" or "step for" is expressly used in a particular claim, they do not intend that any of the appended claims or claim elements be invoked under 35 U.S.C. §112(f).

Claims

1. A method for estimating actuator parameters of an actuator in situ and in real time, the method comprising: driving the actuator with a test signal imperceptible to a user of the device during real-time operation of the device including the actuator; measuring a voltage and a current associated with the actuator and caused by the test signal; determining one or more parameters of the actuator based on the voltage and the current; determining an actuator type of the actuator based on the one or more parameters; as well as A playback signal to the actuator is controlled based on the actuator type.

2. The method according to claim 1, wherein: The one or more parameters include a mechanical impedance parameter of the actuator.

3. The method according to claim 1, wherein: The one or more parameters include an electrical impedance parameter of the actuator.

4. The method according to claim 1, wherein: The test signal has an imperceptible duration.

5. The method according to claim 4, wherein: The imperceptible duration is less than 5 milliseconds.

6. The method according to claim 1, wherein: The test signal has an imperceptible amplitude.

7. The method according to claim 6, wherein: The imperceptible amplitude is between 170 mV and 130 mV.

8. The method according to claim 1, wherein: The frequency of the test signal is significantly different from the resonant frequency of the actuator.

9. The method according to claim 1, wherein: Measuring the current includes measuring a sense voltage across terminals of a sense resistor in series with the actuator.

10. The method of claim 9, further comprising operating the device in a plurality of modes, the plurality of modes comprising: a characterization mode, wherein the sense resistor has a first resistance, and wherein the current is measured; and An active mode wherein the sense resistor has a second resistance that is significantly less than the first resistance.

11. A system for estimating actuator parameters of an actuator in situ and in real time, the system comprising: a test signal generator configured to generate a test signal imperceptible to a user of a device including the actuator so as to drive the actuator during real-time operation of the device; and The measurement subsystem is configured to: measuring a voltage and a current associated with the actuator and caused by the test signal; determining one or more parameters of the actuator based on the voltage and the current; determining an actuator type of the actuator based on the one or more parameters; and A playback signal to the actuator is controlled based on the actuator type.

12. The system according to claim 11, wherein: The one or more parameters include a mechanical impedance parameter of the actuator.

13. The system according to claim 11, wherein: The one or more parameters include an electrical impedance parameter of the actuator.

14. The system according to claim 11, wherein: The test signal has an imperceptible duration.

15. The system of claim 14, wherein: The imperceptible duration is less than 5 milliseconds.

16. The system according to claim 11, wherein: The test signal has an imperceptible amplitude.

17. The system of claim 16, wherein: The imperceptible amplitude is between 170 mV and 130 mV.

18. The system of claim 11, wherein: The frequency of the test signal is significantly different from the resonant frequency of the actuator.

19. The system of claim 11, wherein: Measuring the current includes measuring a sense voltage across terminals of a sense resistor in series with the actuator.

20. The system of claim 19, wherein the measurement system is further configured to operate the device in a plurality of modes, including: a characterization mode, wherein the sense resistor has a first resistance, and wherein the current is measured; and An active mode wherein the sense resistor has a second resistance that is significantly less than the first resistance.

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