Method and system for in-system estimation of actuator parameters - Patents.com

Abstract

A method for estimating actuator parameters for an actuator in situ and in real time may include driving the actuator with a test signal imperceptible to a user of the device during real-time operation of a 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 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 relates generally to in-system sensing of parameters associated with electromagnetic actuators, such as linear resonant actuators or tactile transducers. [Background technology]

[0002] Vibro-tactile transducers, e.g., linear resonant actuators (LRAs), are widely used in portable devices such as mobile phones to generate vibratory feedback to users. Various forms of vibro-tactile feedback can produce different tactile sensations on the user's skin and may play an increasingly important role in human-machine interaction in modern devices.

[0003] An LRA can be modeled as a mass-spring electro-mechanical vibration system. When driven by a properly designed or controlled drive signal, the LRA can generate some desired type of vibration. For example, a crisp and distinct vibration pattern on a user's finger can be used to create a perception that mimics a mechanical button click. This distinct vibration can be used as a virtual switch to replace the mechanical button.

[0004] 1 shows an example of a vibro-tactile system in a device 100. 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 include, for example, a pressure or force sensor on a screen or a virtual button of the device 100.

[0005] Among various forms of vibro-haptic feedback, sound vibrations of a certain duration can play an important role to notify a device user of certain predefined events, such as an incoming call or message, an emergency alert, a timer warning, etc. To efficiently generate sound vibration notifications, it may be desirable to operate a haptic actuator at its resonant frequency.

[0006] The resonant frequency f0 of the tactile transducer is

number

[0007] The vibration resonance of a tactile transducer can change over time due to sample-to-sample variations in individual tactile transducers, variations in mobile device assemblies, temporary changes in components due to aging, changes in components due to self-heating, and usage conditions such as different strengths with which a user grips the device.

[0008] 2A shows an example of a Linear Resonant Actuator (LRA) modeled as a linear system including a mass-spring system 201. LRAs are nonlinear components that may behave differently depending on applied voltage levels, operating temperature, operating frequency, etc. However, these components may be modeled as linear components within certain conditions.

[0009] FIG. 2B shows an example of an LRA modeled as a linear system, including an electrical equivalent model of the LRA's mass-spring system 201. In this example, the LRA is modeled as a third-order system with electrical and mechanical components. In particular, Re and Le are the DC resistance and coil inductance of the coil-magnetic system, respectively, and Bl is the magnetic force coefficient of the coil. The driver amplifier outputs a voltage waveform V(t) with an output impedance Ro. The terminal voltage V T (t) can be sensed across the terminals of a tactile transducer. The mass-spring system 201 moves with a velocity u(t).

[0010] An electromagnetic load such as an LRA has a coil impedance Z coil and mechanical impedance Z mech Sum of: Z LRA =Z coil +Z mech (2) Impedance Z seen as LRA It can be characterized by:

[0011] Coil impedance Z coil is the direct current (DC) resistance Re in series with the inductance Le: Z coil =Re+s*Le (3) may include.

[0012] Mechanical impedance Z mech can be defined by three parameters including resonance resistance Res, which represents the electrical resistance representing the mechanical friction of the tactile transducer mass-spring system; capacitance Cmes, which represents the electrical capacitance representing the equivalent moving mass M of the tactile transducer mass-spring system; and inductance Lces, which represents the compliance C of the tactile transducer mass-spring system. 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:

number

[0013] The resonant frequency f0 of the tactile transducer is

number

[0014] The quality factor Q of the LRA is

number

[0015] Referring to equation (6), it contains a sub-equation that describes the parallel connection of resistors Re and Res (i.e.,

number

[0016] Electromagnetic transducers such as LRAs or microspeakers may have slow response times. FIG. 3 is a graph of an example LRA response describing an example drive signal for the LRA, the current through the LRA, and the back electromotive force (back EMF) of the LRA, which may be proportional to the speed of the moving element (e.g., coil or magnet) of the transducer. As shown in FIG. 3, the attack time of the back EMF slows as energy is transferred to the LRA, and a "ringing" of the back EMF may occur after the drive signal ends as the mechanical energy stored in the LRA is discharged. In the context of a haptic LRA, such operating characteristics may result in a "mushy" clicking or pulsing sensation rather than a "crisp" haptic response. Thus, it may be desirable for the LRA to instead have a response similar to that shown in FIG. 4, which may minimize ringing after the drive signal ends and provide a more "crisp" haptic response in a haptic context. Therefore, it may be desirable to apply processing to the drive signal such that when the processed drive signal is applied to the transducer, the velocity or back EMF of the transducer more closely resembles those of Figure 4. Please note that by including Figure 4 in this Background section, applicants do not intend to admit that the optimized waveform of Figure 4 is prior art.

[0017] To optimize the performance of an LRA or other actuator to produce a more desirable response, the transducer drive system may need to apply tuning parameters optimized for the specific actuator model, which may traditionally require the implementation of costly factory calibration procedures. Therefore, it may be desirable to reduce factory calibration by seamlessly performing actuator parameter measurements while the system is powered on or the actuator is in use, without impacting the user experience.

[0018] The human haptic system is particularly sensitive to frequencies in the range of 100-400 Hz. Thus, LRAs are often designed to have a resonant frequency in the range of 150-250 Hz. This resonant characteristic means that in most cases, the acceleration rise time is relatively long. Furthermore, after the LRA mass begins to move, reducing the amplitude of the input voltage may not instantly reduce the amplitude of the mass movement. Instead, the mass movement will slowly decay. Through the use of optimized tuning parameters, the LRA algorithm may enable consistent acceleration across multiple LRA samples, reduce rise / braking times, and / or improve the end user's experience of the haptic effect. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] U.S. Patent Application Serial No. 16 / 816,790 [Patent Document 2] U.S. Patent Application Serial No. 16 / 816,833 [Patent Document 3] U.S. Patent Application Serial No. 16 / 842,482 [Patent Document 4] U.S. Patent Application Serial No. 16 / 369,556 [Patent Document 5] U.S. Patent Application Serial No. 17 / 497,110 Summary of the Invention [Problem to be solved by the invention]

[0020] In accordance with the teachings of the present disclosure, disadvantages and problems associated with determining parameters associated with electromagnetic actuators may be reduced or eliminated. [Means for solving the problem]

[0021] According to an embodiment of the present disclosure, a method for estimating actuator parameters for an actuator in situ and in real time may include driving the actuator with a test signal imperceptible to a user of the device during real-time operation of a 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 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.

[0022] According to an embodiment of the present disclosure, a system for in situ and real-time estimation of actuator parameters for an actuator may include a test signal generator configured to generate a test signal imperceptible to a user of the device to drive the actuator during real-time operation of the device including the actuator, and a measurement subsystem associated with the actuator and configured to measure voltages and currents caused by the test signal, determine one or more parameters of the actuator based on the voltage and current, determine an actuator type for the actuator based on the one or more parameters, and control a playback signal to the actuator based on the actuator type.

[0023] The technical advantages of the present disclosure will become readily apparent to those skilled in the art from the drawings, description, and claims contained herein. The object and advantages of the embodiments will be realized and attained at least by the elements, features, and combinations particularly pointed out in the claims.

[0024] It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory only and are not restrictive of the present disclosure, as claimed.

[0025] The present embodiments and their advantages may be more fully understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals refer to like features and in which: [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 illustrates an example of a vibro-tactile system in a device, as known in the art. [Figure 2A] FIG. 1 illustrates an example of a linear resonant actuator (LRA) modeled as a linear system, as known in the art. [Figure 2B] FIG. 1 illustrates an example of a linear resonant actuator (LRA) modeled as a linear system, as known in the art. [Diagram 3] FIG. 1 is a graph of an exemplary waveform of an electromagnetic load, as known in the art. [Figure 4] FIG. 2 illustrates a graph of a desired exemplary waveform of an electromagnetic load, in accordance with an embodiment of the present disclosure. [Diagram 5] FIG. 2 illustrates a block diagram of selected components of an exemplary mobile device in accordance with an embodiment of the present disclosure. [Figure 6] FIG. 2 illustrates a block diagram of selected components of an integrated haptic system, according to an embodiment of the present disclosure. [Figure 7] FIG. 2 illustrates selected components of an exemplary system including an electromagnetic load, in accordance with an embodiment of the present disclosure. [Figure 8] FIG. 2 illustrates a circuit diagram of an example implementation of a sense resistor for measuring current, in accordance with an embodiment of the present disclosure. [Figure 9] FIG. 1 illustrates a flowchart of an exemplary method for in-system estimation of actuator parameters and compensation thereof, in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The following description illustrates exemplary embodiments of the present disclosure. Further exemplary embodiments and implementations will be apparent to those skilled in the art. In addition, those skilled in the art will recognize that various equivalent techniques may be applied in place of or in conjunction with the embodiments described below, and all such equivalents should be considered to be encompassed by the present disclosure.

[0028] Various electronic or smart devices may have transducers, speakers, and acoustic output transducers, for example, any transducer for converting a suitable electrical drive signal into an acoustic output such as sound waves, pressure waves, or mechanical vibrations. For example, many electronic devices may include one or more speakers or loudspeakers for generating sound, such as, for example, playing audio content, communicating voice, and / or providing audible notifications.

[0029] Such speakers or loudspeakers may consist of an electromagnetic actuator, e.g., a voice coil motor, that is mechanically coupled to a flexible diaphragm, e.g., a conventional loudspeaker cone, or to a surface of the device, e.g., a glass screen in a mobile device. Some electronic devices may also include acoustic output transducers capable of generating ultrasonic waves, e.g., for use in proximity detection type applications and / or machine-to-machine communication.

[0030] Many electronic devices may additionally or alternatively include more specialized acoustic output transducers, e.g., haptic transducers, tuned to generate vibrations for haptic control feedback or notification to the user. Additionally or alternatively, the electronic device may have a connector, e.g., a socket, for a detachable mating connection with a corresponding connector of an accessory device, and may be configured to provide a drive signal to the connector to drive one or more transducers of the above-mentioned types of the accessory device when connected. Thus, such electronic devices include a drive circuit for driving the transducers of the host device or the connected accessory with an appropriate drive signal. In the case of an acoustic or haptic transducer, the drive signal is typically an analog time-varying voltage signal, e.g., a time-varying waveform.

[0031] 5 illustrates a block diagram of selected components of an exemplary host device 502, in accordance with an embodiment of the present disclosure. As shown in FIG. 5, the host device 502 may include an enclosure 501, a controller 503, a memory 504, a force sensor 505, a microphone 506, a linear resonant actuator 507, a wireless transmitter / receiver 508, a speaker 510, and a haptic system 512.

[0032] The enclosure 501 may include any suitable housing, casing, or other enclosure for housing the various components of the host device 502. The enclosure 501 may be constructed from plastic, metal, and / or any other suitable material. Additionally, the enclosure 501 may be adapted (e.g., in size and shape) such that the host device 502 is easily carried by a person of a user of the host device 502. Thus, the 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 notebook computer, a video game controller, or any other device that is easily carried by a person of a user of the host device 502.

[0033] The controller 503 may be contained within the enclosure 501 and may include any system, device, or apparatus configured to interpret and / or execute program instructions and / or process data, including, but 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, the controller 503 interprets and / or executes program instructions and / or processes data stored in the memory 504 and / or other computer readable media accessible to the controller 503.

[0034] Memory 504 may be contained within enclosure 501 and communicatively coupled to controller 503 and may include any system, device, or apparatus (e.g., computer-readable medium) configured to retain program instructions and / or data for a period of time. Memory 504 may include random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), Personal Computer Memory Card International Association (PCMCIA) cards, flash memory, magnetic storage devices, magneto-optical storage devices, or any suitable selection and / or array of volatile memory or non-volatile memory that retains data after power to host device 502 is turned off.

[0035] The microphone 506 may be at least partially contained within the enclosure 501 and may be communicatively coupled to the controller 503 and may include any system, device, or apparatus configured to convert sound incident on the microphone 506 into an electrical signal that can be processed by the controller 503 using a diaphragm or membrane having an electrical capacitance that changes based on sonic vibrations received by the diaphragm or membrane. The microphone 506 may include an electrostatic microphone, a condenser microphone, an electret microphone, a microelectromechanical system (MEMS) microphone, or any other suitable capacitive microphone.

[0036] The wireless transmitter / receiver 508 may be housed within the enclosure 501 and may be communicatively coupled to the controller 503 and may include any system, device, or apparatus configured to utilize an antenna to generate and transmit radio-frequency signals, as well as to receive radio-frequency signals and convert information carried by such received signals into a form usable by the controller 503. The wireless 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), Wireless Fidelity, etc.

[0037] The speaker 510 may be at least partially contained within the enclosure 501, may be external to the enclosure 501, may be communicatively coupled to the controller 503, and may include any system, device, or apparatus configured to generate sound in response to an electrical audio signal input. In some embodiments, the speaker may include a dynamic loudspeaker, which 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, a magnetic field is generated by the current in the voice coil, making it a variable electromagnet. The coil and the magnetic system of the driver interact to generate a mechanical force that moves the coil (and attached cone) back and forth, thereby reproducing sound under the control of the electrical signal applied from the amplifier.

[0038] The force sensor 505 may be housed within the enclosure 501 and may include any suitable system, device, or apparatus for sensing force, pressure, or contact (e.g., interaction with a human finger) and generating an electrical or electronic signal in response to such force, pressure, or contact. In some embodiments, such an electrical or electronic signal may be a function of the magnitude of the force, pressure, or contact applied to the force sensor. In these and other embodiments, such an electronic or electrical signal may include a general purpose input / output signal (GPIO) associated with an input signal to which haptic feedback is provided. The force sensor 505 may include, but is not limited to, a capacitive displacement sensor, an inductive force sensor (e.g., a resistive-inductive-capacitive sensor), a strain gauge, a piezoelectric force sensor, a force-sensing resistor, a piezoelectric force sensor, a thin film force sensor, or a quantum tunneling composite-based force sensor. For purposes of clarity and explanation in this disclosure, the term "force" as used herein may refer not only to force, but also to a physical quantity indicative of force or a physical quantity similar to force, such as, but not limited to, pressure and contact.

[0039] The linear resonant actuator 507 may be housed within the enclosure 501 and may include any suitable system, device, or apparatus for generating a mechanical vibration force across a single axis. For example, in some embodiments, the linear resonant actuator 507 may rely on an alternating 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 may vibrate with a perceptible force. Thus, the linear resonant actuator 507 may be beneficial in haptic applications within a certain frequency range. For purposes of clarity and explanation, the present disclosure is described in connection with the use of a linear resonant actuator 507, but it should be understood that any other type of vibration actuator (e.g., an eccentric rotating mass actuator) may instead be used in place of or in addition to the linear resonant actuator 507. Additionally, it should also be understood that an actuator configured to generate a vibration mechanical force across multiple axes may instead 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 in the form of at least one of a replacement for a mechanical button and capacitive sensor feedback.

[0040] The integrated haptic system 512 may be contained within the enclosure 501 and may be communicatively coupled to the force sensor 505 and the linear resonant actuator 507, and may include any system, device, or apparatus configured to receive a signal from the force sensor 505 indicative of a force applied to the host device 502 (e.g., a force applied by a human finger on a virtual button of the host device 502) and generate an electronic signal to drive the linear resonant actuator 507 in response to the force applied to the host device 502. Details of an integrated haptic system according to an embodiment of the present disclosure are shown in FIG.

[0041] 5 depicts certain exemplary components as being integrated into the host device 502 (e.g., controller 503, memory 504, force sensor 505, microphone 506, wireless transmitter / receiver 508, speaker 510), a host device 502 according to the present disclosure may include one or more components not specifically listed above. For example, while FIG. 5 depicts certain user interface components, the host device 502 may include one or more other user interface components in addition to those depicted in FIG. 5 (including, but not limited to, a keypad, a touch screen, and a display) to enable a user to interact with and / or operate the host device 502 and its associated components.

[0042] Figure 6 illustrates a block diagram of selected components of an 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 the integrated haptic system 512 of Figure 5. As shown in Figure 6, the integrated haptic system 512A may include a digital signal processor (DSP) 602, a memory 604, and an amplifier 606.

[0043] 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 process data stored in memory 604 and / or other computer-readable media accessible to DSP 602.

[0044] Memory 604 may include any system, device, or apparatus (e.g., computer-readable medium) that can be communicatively coupled to DSP 602 and configured to retain program instructions and / or data for a period of time. Memory 604 may include any suitable selection and / or arrangement of random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), Personal Computer Memory Card International Association (PCMCIA) cards, flash memory, magnetic storage devices, optical magnetic storage devices, or any suitable selection and / or arrangement of volatile memory or non-volatile memory that retains data after power to host device 502 is turned off.

[0045] The amplifier 606 may be electrically coupled to the DSP 602 and may receive an input signal V IN (e.g., a time-varying voltage or current) to produce an output signal V OUT The amplifier 606 may comprise any suitable electronic system, device, or apparatus configured to generate a digital signal. For example, the amplifier 606 may use power from a power source (not explicitly shown) to increase the amplitude of the signal. The amplifier 606 may include any suitable amplifier class, including but not limited to a class D amplifier.

[0046] During operation, memory 604 may store one or more haptic playback waveforms. In some examples, 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 generates a force signal V indicative of the force applied to force sensor 505. SENSE The force signal V may be configured to receive a force signal V indicative of the sensed force. SENSE In response to receiving, or independent of such reception, the DSP 602 retrieves haptic playback waveforms from the memory 604 and processes such haptic playback waveforms to generate a processed haptic playback signal V IN In an embodiment where the amplifier 606 is a class D amplifier, the processed haptic playback signal VIN may include a pulse width modulated signal. The force signal V indicative of the sensed force SENSE In response to receiving the processed haptic playback signal V IN may be output to an amplifier 606, which outputs a processed haptic playback signal V IN to generate a haptic output signal V for driving the linear resonant actuator 507. OUT may be generated.

[0047] In some embodiments, the integrated haptic system 512A may be formed on a single integrated circuit, thus enabling lower latency than existing approaches to haptic feedback control. By providing the integrated haptic system 512A as part of a single monolithic integrated circuit, latency between various interfaces and system components of the integrated haptic system 512A may be reduced or eliminated.

[0048] 7 illustrates selected components of an example system 700 including an electromagnetic load 701, according to an embodiment of the disclosure. The system 700 may include, but is not limited to, or be integrated with any other system, device, or apparatus including a mobile device, a home application, a vehicle, and / or a human-machine interface. The electromagnetic load 701 may include any suitable load having a complex impedance, including, but is not limited to, a tactile transducer, a loudspeaker, a microspeaker, a piezoelectric transducer, a voice-coil actuator, a solenoid, or other suitable transducer.

[0049] In operation, the signal generator 724 of the transducer drive subsystem 705 of the system 700 may generate a raw transducer drive signal x'(t) (which in some embodiments may be a waveform signal such as a haptic waveform signal or an audio signal). The raw transducer drive signal x'(t) may be generated based on a desired playback waveform received by the signal generator 724.

[0050] The raw transducer drive signal x'(t) may be received by the waveform pre-processor 726, which may modify the raw transducer drive signal x'(t) based on one or more parameters generated by the impedance measurement subsystem 708, such one or more parameters may be associated with the electromagnetic load 701.

[0051] The processed transducer drive signal x(t) may then be amplified by an amplifier 706 to generate a drive signal V(t) for driving the electromagnetic load 701. In response to the drive signal V(t), the sensed terminal voltage V of the electromagnetic load 701 may be T The current I(t) may be sensed by a terminal voltage sensing block 707, e.g., a volt-meter, 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) is coupled to a resistor R s The input voltage can be sensed across a shunt resistor 702 having a

[0052] 7, 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 coil inductance Le of the electromagnetic load 701. Based on such measurements, the impedance measurement subsystem 708 may communicate such parameters and / or any other suitable parameters (e.g., mechanical impedance parameters Res, Cmes, and Lces) to the waveform pre-processor 726. Based on such parameters, the waveform pre-processor 726 may modify the raw transducer drive signal x'(t) in a manner intended to optimize the performance of the electromagnetic load 701 (e.g., modify the drive or damping of the electromagnetic load to enhance human perception of the vividness of haptic effects).

[0053] Examples of approaches for estimating one or more components of the electrical and / or mechanical impedance of the electromagnetic load 701 include, but are not limited to, U.S. patent application Ser. No. 16 / 816,790, filed March 12, 2020, and entitled "Methods and Systems for Improving Transducer Dynamics," U.S. patent application Ser. No. 16 / 816,833, filed March 12, 2020, and entitled "Methods and Systems for Estimating Transducer Parameters," U.S. patent application Ser. No. 16 / 842,482, filed April 7, 2020, and entitled "Thermal Model of Transducer for Thermal Protection and Resistance Estimation," U.S. patent application Ser. No. 16 / 369,556, filed March 29, 2019, and entitled "Driver Circuitry," and U.S. patent application Ser. No. 16 / 369,556, filed October 8, 2021, and entitled "Systems and Methods for Sensing Displacement of an Electrical and / or Mechanical Impedance of an Electrical and Mechanical Load," all of which are incorporated herein by reference. No. 17 / 497,110, entitled "Electromechanical Transducer," all of which are incorporated herein by reference in their entireties.

[0054] For example, referring to FIG. 2B, both the speed and the position of the moving mass of the actuator are determined by the back EMF Vbemf (forward, V B (also called) and I L (e.g., back EMFV B is proportional to the velocity of the moving mass, and the current I L (where θ is proportional to the position of the moving mass). The linear state space model of the transducer model illustrated in Figure 2B is given by

number

[0055] To estimate such impedance parameters in situ during operation, the impedance measurement subsystem 708 may generate a test signal (e.g., a pilot tone signal) and the waveform pre-processor 726 may either combine such test signal with the raw transducer drive signal x'(t) to generate the processed transducer drive signal x(t) or mute the raw 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 with a duration that is imperceptible to humans, an amplitude that is imperceptible to humans, and / or a frequency that is not typically used in the ultimate application of the electromagnetic load 701 to stimulate the electromagnetic load 701 (e.g., a frequency that is much different than the resonant frequency of the electromagnetic load 701). Thus, the test signal may not be perceived by a user of the system 700 when the system 700 is operated and used in real time. For example, the imperceptible duration may be approximately 5 milliseconds. In another example, the imperceptible amplitude may be approximately 170 millivolts to approximately 330 millivolts. The frequency that is not normally used in the end application of the electromagnetic load 701 to stimulate the electromagnetic load 701 may depend on the type of electromagnetic load 701 and may vary based on the type of electromagnetic load 701.

[0056] Additionally, the impedance measurement subsystem 708 measures the sense terminal voltage V TIn addition, the impedance measurement subsystem 708 can estimate 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 communicate such parameters to the waveform pre-processor 726.

[0057] 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 the processed transducer drive signal x(t).

[0058] 8 shows a circuit diagram of an example implementation of a sense resistor 702 according to an embodiment of the present disclosure. As shown in FIG. 8, the sense resistor 702 may be implemented using two selectable resistors 802 and 803, along with a switch 801 to select between the use of resistor 802 and resistor 803. The resistance of resistor 802 may be significantly higher than the resistance of resistor 803.

[0059] During playback of the test signal by the impedance measurement subsystem 708 and the waveform pre-processor 726, there may be a higher tolerance to voltage drop across the sense resistor 702, which may be achieved by reducing the resistance R only during playback of the test signal in order to increase the signal-to-noise ratio of measurements of the sensed current I(t) made using the same voltage measurement device (e.g., the second ADC 704) coupled to the terminals of the sense resistor 702. SThis means that it may be desirable to select a larger resistor 802 than the impedance measurement subsystem 708. Thus, the system 700 may operate in two different modes: a) a characteristic mode in which a larger resistor 802 is selected and the impedance measurement subsystem 708 measures the sensed current I(t), and b) an activation mode in which a smaller resistor 803 is selected (e.g., to lessen the effect of the desired tactile operation of the electromagnetic load 701) and an intended human-perceptible waveform is driven into the electromagnetic load 701. Although not shown in detail in the figures, another portion of the impedance measurement subsystem 708 and / or transducer drive subsystem 705 may generate a control signal to operate the switch 801 to select between resistor 802 and resistor 803.

[0060] 9 illustrates a flow chart of an exemplary method for in-system estimation of actuator parameters and compensation thereof, according to an embodiment of the present disclosure. According to some embodiments, the method 900 may begin at step 902. As noted above, the teachings of the present disclosure may be implemented in a variety of configurations of the system 700. Thus, the preferred initialization point for the method 900 and the order of the steps comprising the method 900 may depend on the implementation chosen.

[0061] In step 902, the system 700 may power on or reset. In step 904, after loading firmware for implementing all or a portion of the transducer drive subsystem 705, the system 700 may enter a characterization mode, in which the impedance measurement subsystem 708 may drive a test signal as a drive signal V(t) to drive the electromagnetic load 701. In step 906, the impedance measurement subsystem 708 measures the sense terminal voltage V(t) resulting from driving the test signal to the electromagnetic load 701. TIn 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 communicate such parameters to the waveform pre-processor 726.

[0062] In step 910, the waveform pre-processor 726 may determine the type of electromagnetic load 701 present in the system 700. In step 912, the system 700 may enter a start-up mode, in which the waveform pre-processor 726 may perform optimized control of the raw transducer drive signal x'(t) to generate a processed transducer drive signal x(t).

[0063] Although Figure 9 discloses a particular number of steps taken with respect to method 900, it may be performed with more or less steps than those depicted in Figure 9. Additionally, although Figure 9 discloses a particular order of steps performed with respect to method 900, the steps comprising method 900 may be completed in any suitable order.

[0064] Method 900 may be implemented using transducer drive subsystem 705, components thereof, or any other system operable to implement method 900. In certain embodiments, method 900 may be implemented partially or fully in software and / or firmware embodied in a computer-readable medium.

[0065] Although the above describes an application to linear electromagnetic loads, it should be appreciated that systems and methods similar or similar to those disclosed may be applied to other linear or non-linear systems.

[0066] As used herein, when two or more elements are referred to as being "coupled" to one another, such terminology indicates that such two or more elements are in electronic or mechanical communication, whether indirectly or directly connected, with or without intermediary elements, as applicable.

[0067] The present disclosure encompasses all changes, substitutions, variations, modifications, and alterations to the embodiments herein that would be understood by one of ordinary skill in the art. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, modifications, and alterations to the embodiments herein that would be understood by one of ordinary skill in the art. Moreover, any reference in the appended claims to an apparatus or system, or an apparatus or system component, adapted to, arranged to, capable of, configured to, enabled to, operable to, or operating to perform a particular function encompasses that apparatus, system, or component, so long as it is so adapted, arranged, capable, configured, enabled, operable, or operating, regardless of whether it or that particular function is activated, turned on, or unlocked. Thus, modifications, additions, or omissions may be made to the systems, devices, and methods described herein without departing from the scope of the disclosure. For example, system and device components may be integrated or separated. Moreover, operations of the systems and apparatus disclosed herein may be performed by more, fewer, or other components, and the methods described may include more, fewer, or other steps. In addition, the steps may be performed in any suitable order. As used herein, "each" refers to each number in a set or each number in a subset of a set.

[0068] Although example embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of technologies, whether currently known or not, and the present disclosure should in no way be limited to the example implementations and technologies illustrated in the figures and described above.

[0069] Unless specifically noted otherwise, items depicted in the drawings are not necessarily drawn to scale.

[0070] All examples and conditional language described herein are intended for educational purposes to aid the reader in understanding the disclosure and concepts contributed by the inventors to further the art, and are to be construed as being, but not limited to, such specifically described examples and circumstances. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations may be made without departing from the spirit and scope of the disclosure.

[0071] Although certain advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages. In addition, other technical advantages may become readily apparent to one of ordinary skill in the art after reviewing the foregoing figures and description.

[0072] In order to assist the Patent Office and any reader of any patent issuing on this application in interpreting the claims appended below, unless the words "means for" or "step for" are expressly used in a particular claim, applicants do not intend that the appended claims or any of their claimed elements be construed as invoking 35 USC Section 112(f).

Claims

1. A method for estimating actuator parameters for an actuator in-situ and in real-time, 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 generated 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; controlling a reproduction signal to the actuator based on the actuator type; and a method including the above steps.

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

3. The method according to claim 1, wherein the one or more parameters include electrical impedance parameters 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 approximately 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 from approximately 170 millivolts to approximately 330 millivolts.

8. The method according to claim 1, wherein the test signal has a frequency significantly different from a resonance frequency of the actuator.

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

10. operating the device in a plurality of modes including a characteristic mode in which the sense resistor has a first resistance and the current is measured, and a startup mode in which the sense resistor has a second resistance significantly smaller than the first resistance; and further comprising operating the device in a plurality of modes including a startup mode in which the sense resistor has a second resistance significantly smaller than the first resistance; The method according to claim 9.

11. A system for estimating actuator parameters for an actuator in-situ and in real-time, comprising: ​ During real-time operation of the device including the actuator, a test signal generator configured to generate a test signal imperceptible to a user of the device to drive the actuator; associated with the actuator, measuring the voltage and current generated 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, controlling a playback signal to the actuator based on the actuator type, a measurement subsystem configured as such; A system comprising.

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

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

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

15. The system according to claim 14, wherein the imperceptible duration is less than approximately 5 milliseconds.

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

17. The system according to claim 16, wherein the imperceptible amplitude is from approximately 170 millivolts to approximately 330 millivolts.

18. The system according to claim 11, wherein the test signal has a frequency significantly different from the resonance frequency of the actuator.

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

20. The measurement system is a characteristic mode in which the sense resistor has a first resistance and the current is measured, and a startup mode in which the sense resistor has a second resistance significantly smaller than the first resistance, further configured to operate the device in a plurality of modes including, The system according to claim 19.

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