Segmented characterization of electromechanical actuators

Abstract

A method includes applying a high frequency signal to an electromechanical actuator and measuring a first response of the electromechanical actuator to the high frequency signal, estimating an electrical parameter of the electromechanical actuator based on the first response, applying a low frequency broadband signal to the electromechanical actuator and measuring a second response of the electromechanical actuator to the low frequency broadband signal, and estimating a mechanical parameter of the electromechanical actuator based on the second response and the estimated electrical parameter.

Description

Background Art

[0001] Electromechanical actuators typically require calibration, which involves characterizing the actuator by stimulating it. Characterizing the actuator involves determining the parameters of the actuator. One known method of stimulating an electromechanical actuator in order to characterize it is to use a chirp signal. A chirp signal is a sinusoidal signal whose frequency increases or decreases as it sweeps through many different frequencies. However, a disadvantage of using a chirp signal to characterize an electromechanical actuator is that the amount of time required to obtain accurate results is relatively long, which may be undesirable in certain situations, such as during the manufacture of a large number of devices that include electromechanical actuators that need to be calibrated. Another disadvantage of using a chirp signal to characterize an electromechanical actuator is that the chirp signal is perceptible. Another disadvantage of using a chirp signal to characterize an electromechanical actuator is that if the chirp signal is applied for a long enough time, it may cause thermal effects, such as heating.

[0002] Another known method for exciting an electromechanical actuator for characterization is to use short-duration, high-amplitude pulses to measure the pulse response. However, a disadvantage of using pulses to characterize electromechanical actuators is that the pulses can be destructive to the actuator. Furthermore, in some cases, using pulses to characterize electromechanical actuators is not practical.

[0003] In general, it is desirable to have a method for characterizing electromechanical actuators that is fast, accurate, repeatable, and unobtrusive. Summary of the Invention

[0004] In one embodiment, the present disclosure provides a method comprising applying a high-frequency signal to an electromechanical actuator and measuring a first response of the electromechanical actuator to the high-frequency signal, estimating electrical parameters of the electromechanical actuator based on the first response, applying a low-frequency, broadband signal to the electromechanical actuator and measuring a second response of the electromechanical actuator to the low-frequency, broadband signal, and estimating mechanical parameters of the electromechanical actuator based on the second response and the estimated electrical parameters.

[0005] In another embodiment, the present disclosure provides a non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing a method comprising applying a high-frequency signal to an electromechanical actuator and measuring a first response of the electromechanical actuator to the high-frequency signal, estimating an electrical parameter of the electromechanical actuator based on the first response, applying a low-frequency, broadband signal to the electromechanical actuator and measuring a second response of the electromechanical actuator to the low-frequency, broadband signal, and estimating a mechanical parameter of the electromechanical actuator based on the second response and the estimated electrical parameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1is an example circuit diagram representation of the electrical impedance of an electromechanical actuator according to an embodiment of the present disclosure, the parameters of which can be estimated piecewise.

[0007] Figure 2 is a diagram showing a method for performing an electromechanical actuator (such as Figure 1 An example diagram of the process of piecewise estimation of parameters of an electromechanical actuator).

[0008] Figure 3 is an example diagram illustrating a first step of a segmented electromechanical actuator characterization process according to an embodiment of the present disclosure.

[0009] Figure 4 is an example diagram illustrating high-frequency compensation of low-frequency estimation employed in the first step of a segmented electromechanical actuator characterization process according to an embodiment of the present disclosure.

[0010] Figure 5 is an example graph of the impedance magnitude of a resonant tank of an electromechanical actuator as a function of frequency according to an embodiment of the present disclosure.

[0011] Figure 6 1 are example corresponding time-domain and frequency-domain plots of an example LF broadband excitation signal employed in the second step of the segmented electromechanical actuator characterization process according to an embodiment of the present disclosure.

[0012] Figure 7 is an example diagram illustrating a second step of a segmented electromechanical actuator characterization process according to an embodiment of the present disclosure.

[0013] Figure 8 is an example diagram of HF tone and LF broadband excitation signals used in the segmented electromechanical actuator characterization process according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0014] Figure 1 is an example circuit diagram representation of the electrical impedance of an electromechanical actuator 100 according to an embodiment of the present disclosure, the parameters of which can be estimated in a piecewise manner. The electromechanical actuator 100 can be a voice coil motor, a linear resonant actuator (LRA), an ultrasonic acoustic output transducer, a tactile transducer of a vibrotactile system, a speaker, or other types of electromechanical actuators. Figure 1 In FIG, an electromechanical actuator 100 is depicted as having a mechanical portion (also referred to as a resonant tank) and a coil portion. An embodiment is described in which the parameters of the coil can be estimated first in a piecewise manner, and then the estimated parameters of the resonant tank can be used to subsequently estimate the parameters of the resonant tank. The electromechanical actuator parameters are generally referred to as Thiele / Small (TS) parameters. The electromechanical actuator 100 can be included in a device such as a mobile phone or other device for use.

[0015] The coil of the electromechanical actuator 100 is characterized by having a resistance parameter (Re), also known as DC resistance, and an inductance parameter (Le), also known as coil inductance, in series, which are electrical parameters of the electromechanical actuator 100. The resultant impedance of Re and Le in series is Figure 1 The resonant circuit of the electromechanical actuator 100 can be modeled as a spring system with a moving mass. The resonant circuit is characterized by a parallel resonant resistance parameter (Res), an inductance parameter (Lces) representing the compliance of the spring system, and a capacitance parameter (Cmes) representing the moving mass of the spring system. These parameters are the mechanical parameters of the electromechanical actuator 100. The mechanical parameters of the electromechanical actuator 100 can also be called resonance parameters. The composite impedance of Res, Lces, and Cmes in parallel is Figure 1 is referred to as Zmech. Zmech can be equivalently represented by the mechanical parameter Res, the resonant frequency (F0), and the quality factor (Q). Res, Lces, and Cmes can be understood as electrical analog parameters of the mechanical parameters Res, F0, and Q, which are related by equations (1) to (3).

[0016]

[0017]

[0018] Res=Lces*2π*F0**Q (3)

[0019] like Figure 1 As shown, an excitation voltage V(t) is applied to the electromechanical actuator 100. The application of the excitation voltage V(t) induces a current I(t) that flows through the series-connected Re and Le (Zcoil), and then through the parallel-connected Res, Lees, and Cmes (Zmech). More specifically, the current I(t) flows through the impedance Zcoil, which generates a voltage Vcoil across the coil, and the current I(t) flows through the impedance Zwech, generating a voltage Vmech across the resonant tank, as shown. The voltage Vmech may also be referred to as the back electromotive force voltage Vbemf.

[0020] As described in more detail below, the excitation voltage V(t) includes two components - a high frequency (HF) tone and a low frequency (LF) broadband signal - which are designed to elicit respective electrical and mechanical responses from the electromechanical actuator 100, which responses can be used as respective bases for estimating respective electrical and mechanical parameters of the electromechanical actuator 100, in that order. That is, in a piecewise manner, the electrical parameters are estimated first and then used to estimate the mechanical parameters. As described below, the HF and LF broadband components can be applied to the electromechanical actuator 100 simultaneously, or they can be applied separately in time in either order. Although Figure 1While forcing a voltage into the electromechanical actuator 100 to induce a measured current is shown, both of which are used to estimate parameters of the electromechanical actuator 100, other embodiments are contemplated in which a current is forced into the electromechanical actuator 100 that generates a measured voltage, both of which are used to estimate parameters of the electromechanical actuator 100. Reference will now be made to Figure 2 Systems and methods for performing piecewise estimation of electrical and mechanical parameters of an electromechanical actuator 100 are generally described.

[0021] Figure 2 is a diagram showing a method for performing an electromechanical actuator (such as Figure 1 FIG2 is an example of a process for segmented estimation of parameters of an electromechanical actuator 100). Typically, the electrical parameters of the coil are first estimated in time, such as Figure 2 The estimated electrical parameters are then used to estimate the mechanical parameters of the resonant tank, as shown in the left part of Figure 2 As shown in the right portion of FIG. An excitation voltage V(t) is applied to the electromechanical actuator, and the electromechanical actuator responds in the form of a measurable current I(t). More specifically, the excitation voltage V(t) applied to excite an electrical response from the coil is a short HF tone, and the excitation voltage V(t) applied to excite a resonant response (a broadband response) from the resonant tank is a short LF broadband signal (also referred to as a resonant excitation signal), each of which will be described in more detail below.

[0022] The coil current I(t) in response to the HF tone excitation signal V(t) is measured and used together with the excitation signal V(t) as the basis for characterizing the coil according to the first step. That is, based on the following equation (4), as follows about Figure 3 and Figure 4 As described in more detail, the electrical parameters Re and Le of the coil are estimated (e.g., using least squares estimation), where j is the imaginary square root of -1, and ω is the angular frequency of the HF tone, which has a value much larger than 2π*F0; and V(t) and I(t) are complex-valued samples of the excitation signal and the response, respectively.

[0023] V(t)=I(t)*(Re+jωLe) (4)

[0024] The resonant tank current I(t) in response to the LF broadband excitation signal V(t) is measured and used together with the excitation voltage V(t) and the estimated Re and Le values ​​to calculate the back EMF voltage Vbemf (or Vmech) according to equation (5).

[0025]

[0026] The measured resonant tank current I(t) response and the calculated back EMF voltage Vbemf(t) are then used as the basis for characterizing the resonant tank according to the second step. That is, based on equation (6), as follows Figures 5 to 7 As described in more detail, the mechanical parameters Res, Lces, Cmes of the resonant tank are estimated (eg, using least squares estimation), where s is the Laplace transformed variable.

[0027]

[0028] Once the electrical and mechanical parameters are estimated, a model of the electromechanical actuator can be built and the electromechanical actuator can be calibrated. Knowledge of the electromechanical actuator parameters can be used by a device including the electromechanical actuator to adjust and optimize the signal played back to the electromechanical actuator.

[0029] The segmented nature of parameter estimation—with separate excitation signals for the coil and resonant tank—advantageously enables the duration of the HF excitation signal and the LF broadband excitation signal to be relatively short, which may facilitate faster characterization and calibration of electromechanical actuators than previous methods. Shorter characterization times may be advantageous during the manufacture of devices (e.g., mobile phones) that incorporate electromechanical actuators (e.g., tactile transducers of vibrotactile systems), particularly where large quantities of devices are manufactured. Furthermore, short characterization times can make playback of the excitation signals effectively imperceptible and, therefore, advantageously allow electromechanical actuators to be characterized and calibrated on demand, such as during operation of the device by a consumer, rather than just at the time of manufacture. The ability to characterize and calibrate on demand may be particularly valuable because the parameters of an electromechanical actuator may change over time after the device is manufactured, for example, based on usage, temperature, aging, and other factors. Further advantageously, the segmented approach of first estimating two parameters (Re and Le) and then subsequently estimating the other three parameters (Res, Lces, and Cmes) may be more stable than estimating five parameters simultaneously. In other words, a piecewise approach of first estimating the electrical parameters and then subsequently estimating the mechanical parameters can reduce the complexity of the problem of characterizing electromechanical actuators.

[0030] While embodiments first estimate electrical parameters and then use the estimated electrical parameters to estimate mechanical parameters, the HF excitation signal and the LF broadband signal can be applied in any order. Furthermore, in one embodiment, the HF excitation signal and the LF broadband excitation signal can be applied simultaneously, as long as there is sufficient clearance between the HF and LF broadband signals so that they do not generate mutually interfering harmonics. In other words, calculating / estimating parameters in a piecewise manner is a different operation from applying the HF and LF broadband excitation signals. More specifically, while the electrical parameters are estimated first and then used to estimate the mechanical parameters, the HF excitation signal does not need to be applied before the LF broadband excitation signal is applied, but can be applied simultaneously or afterward.

[0031] Figure 3 is an example diagram illustrating a first step of a segmented electromechanical actuator characterization process according to an embodiment of the present disclosure. Figure 3 A circuit diagram 300 is included showing the application of an HF excitation signal V(t) to a Figure 1 The response of the coil of the electromechanical actuator 100 in the form of an induced current I(t), the estimator 301, and example waveforms of V(t) and I(t). In one embodiment, the HF excitation signal V(t) is a 2 kHz pilot tone burst, but other embodiments are envisioned with tone bursts of other frequencies that are sufficiently separated from the frequency band of the LF broadband excitation signal used in the second step of the segmented characterization process described in more detail below. Figure 3 In the example shown, approximately 240 data samples of V(t) and I(t) are collected at a frequency of 48 kHz over approximately 5 milliseconds, which has been empirically determined to be sufficient to produce accurate results for test samples of electromechanical actuators. A least squares estimator 301 uses the HF excitation signal V(t) and the response current I(t) to estimate Re and Le.

[0032] The least squares estimator 301 includes a regressor 302 and an output function 308 that outputs a voltage V(t). The output function 308 includes an offset 304 and a linear function block 306. The offset 304 may correspond to an offset of a current monitor that measures the current I(t) (e.g., an analog-to-digital converter that uses a known value sensing resistor and converts the voltage measured across the resistor), which needs to be mitigated in order to more accurately estimate Re and Le. The regressor 302 receives the current I(t) and the feedback voltage V(t) as inputs. The output of the regressor 302 is provided as input to the linear function block 306. The offset 304 is subtracted from the output of the linear function block 306 to produce the voltage V(t). In one embodiment, the estimator 301 uses the well-known least squares estimation method to estimate Re and Le using the voltage V(t) and the current I(t) using the collected data samples according to equation (4) above. Although embodiments have been described in which least squares estimation is used to estimate Re and Le, they may also be estimated by other well-known estimation methods, including but not limited to least mean square (LMS) estimation or other iterative methods, and adaptive filtering. In addition, the HF excitation signal V(t) includes a minimum offset to facilitate accurate estimation of Re and Le.

[0033] As will be more clearly understood from the following description of the second step of the segmented characterization, accurate estimates of the mechanical parameters by the second step may require accurate estimates of the electrical parameters by the first step. This is in contrast to previous approaches, such as those described in U.S. Patent Nos. 10,726,683 and 11,263,877, each of which is incorporated herein by reference in its entirety for all purposes. In those patents, the back EMF voltage is estimated at two different tone frequencies, and the difference (amplitude and phase) of the back EMF voltages is calculated. In this approach, "the estimates of the DC resistance Re and inductance Le may not need to be accurate (e.g., within an error range of approximately 10% may be acceptable), and therefore, fixed values ​​from an offline calibration or data sheet specification may be sufficient." The acceptability of the Re and Le errors in the patented approach is due to the fact that the errors in the voltage estimates caused by errors in Re and Le can be essentially eliminated by taking the difference. In contrast, as described below, the second step of the embodiment of the present disclosure directly uses the estimated back EMF voltage (Vbemf) (i.e., not by taking a difference) to estimate the mechanical parameters. Therefore, the current monitor offset mitigation can significantly improve the accuracy of the characterization of the electromechanical actuator. In addition, the following description of Figure 4 The compensation for the real part offset of Zcoil is used to improve the accuracy of the characterization of the electromechanical actuator.

[0034] Figure 4is an example diagram illustrating high-frequency compensation of low-frequency estimation employed in the first step of a segmented electromechanical actuator characterization process according to an embodiment of the present disclosure. Figure 4 The DC coil resistance Re (at Figure 4 Theoretically, the value of the DC coil resistance Re should be fixed and should not change with frequency, such as Figure 4 However, by measuring the imaginary and real parts of the coil impedance at different high frequencies (respectively as Figure 4 As shown by the curves Zim and Zreal in , it is observed that the value of the real part Zreal moves up as the frequency increases. Assuming that the parasitic capacitance in the coil (such as Figure 4 The shift in Zreal is explained by the Zpar in FIG, and the skin effect may also cause this shift.

[0035] In one embodiment, the first step compensates for the Zreal offset by a fixed scaling factor. In one embodiment, for each of many samples of the electromechanical actuator, a high-frequency estimate of ReDC is made while the coil is slightly heated. Additionally, for each sample, a low-frequency estimate of ReDC is obtained by playing a pilot tone at a very low frequency. As the difference between the high-frequency and low-frequency estimates, a scaling factor is obtained. That is, the scaling factor is a predetermined value by which the high-frequency estimate of Re is multiplied to obtain the low-frequency estimate of Re. The scaling factor is applied to the value given by Figure 3 The Re value determined by the estimator 301 may be referred to herein as a high-frequency compensation of the low-frequency estimate. Since the estimation of the mechanical parameters of the electromechanical actuator according to the second segmentation step may be sensitive to the estimation accuracy of Re, the high-frequency compensation of the low-frequency estimate may improve the accuracy of the estimation of the mechanical parameters.

[0036] Figure 5 FIG is an example diagram showing the magnitude of the impedance Zmech of the resonant tank of the electromechanical actuator according to an embodiment of the present disclosure as a function of frequency. Figure 5 As shown, the center frequency where the resonance circuit impedance is the largest is the resonance frequency F0 of the resonance circuit, Res is the peak impedance value, and the bandwidth around the peak is related to the quality factor Q. Figure 5 In the example of , F0 is about 200 Hz, Q is about 8, and Res is about 1.6 ohms, but different electromechanical actuators can have different Res, F0, and Q values. Figure 6 The CMOS (as shown) is designed to have a wide enough frequency band to cover the resonant tank impedance peak, thereby enabling estimation of the mechanical parameters of the resonant tank.

[0037] Figure 6 Included are corresponding time domain and frequency domain plots of an example LF broadband excitation signal employed in the second step of the segmented electromechanical actuator characterization process according to an embodiment of the present disclosure. Figure 6 In the exemplary embodiment of FIG6 , the LF broadband excitation signal comprises two cycles of a sinusoidal waveform multiplied by a window. An integer number of cycles is used in the LF broadband excitation signal to avoid introducing any DC or HF content into the excitation waveform. Although two cycles of a sinusoidal waveform are shown in FIG6 , other integer numbers of cycles may be used. By tapering the data values ​​to zero at the ends of the sinusoidal waveform, the window has a smoothing effect, as shown in FIG6 . Figure 6 (and Figure 8 Examples of window types are shown in Figure 6 As shown, and may include but are not limited to rectangular windows, Nuttall windows, flat-top windows and Gaussian windows. In one embodiment, the Nuttall window provides a smooth waveform with a sufficiently wide frequency band, as shown from Figure 6 As can be observed in the frequency domain diagram, the instantaneous on and off of the LF broadband excitation signal provides a sufficiently wide frequency band to cover the resonant tank impedance peak, thus enabling the estimation of the mechanical parameters of the resonant tank.

[0038] Figure 7 is an example diagram illustrating a second step of a segmented electromechanical actuator characterization process according to an embodiment of the present disclosure. Figure 7 The estimator 701 and the circuit diagram 700 are shown, which illustrate the process of converting a LF wideband excitation signal (e.g., as described with respect to FIG. Figure 6 The above) is applied to Figure 1 The resonant circuit of the electromechanical actuator 100 induces a response in the form of a current I(t) and a back electromotive force voltage Vbemf. Figure 6 As described above, the LF broadband excitation signal is designed to excite a frequency band near the resonant frequency of the resonant circuit (ie, near F0), and the frequency band is wide enough to cover the resonant peak, for example Figure 5 As shown. The response current I(t) is measured and, together with the estimated Re and Le from the first step, used to calculate the back electromotive force voltage Vbemf(t) according to equation (5) above. The measured current I(t) and the calculated Vbemf(t) are then used by the estimator 701 to estimate the mechanical parameters Res, Lces, and Cmes (or alternatively Res, F0, and Q) of the resonant tank of the electromechanical actuator.

[0039] The least squares estimator 701 includes a regressor 702 and an output function 708 that outputs a back electromotive force voltage Vbemf(t). The output function 708 includes an offset 704 (e.g., the offset 704 of the current monitor as described above, which needs to be mitigated to more accurately estimate Res, Lces, and Cmes) and a linear function block 706. The regressor 702 receives the current I(t) and the fed-back back electromotive force voltage Vbemf(t) as input. The output of the regressor 702 is provided as input to the linear function block 706. The offset 704 is subtracted from the output of the linear function block 706 to generate the back electromotive force voltage Vbemf(t). In one embodiment, the estimator 701 uses least squares estimation to use the collected data samples to estimate Res, Lces, and Cmes using the back electromotive force voltage Vbemf(t) and the current I(t) according to the above equation (6), but may use the same method as described above regarding Figure 3 Other estimation methods described.

[0040] Figure 8 Included are example diagrams of HF tones and LF broadband excitation signals employed in the characterization of a segmented electromechanical actuator according to an embodiment of the present disclosure. Figure 8 In an example embodiment, the HF tone portion of the excitation signal comprises 10 cycles of a 2 kHz sinusoidal pilot tone waveform with a burst duration of approximately 5 milliseconds, designed to excite the coil for estimating Re and Le as described above, and the LF broadband portion of the excitation signal comprises two cycles of a 200 Hz sinusoidal waveform multiplied by a Nuttall window, designed to excite the resonant tank for estimating Res, F0 and Q (or alternatively Res, Lces and Cmes) as described above.

[0041] exist Figure 8 In the example of FIG, the playback of the HF excitation signal is performed first in time, and the playback of the LF broadband excitation signal is performed second in time. However, in other embodiments, the playback of the LF broadband excitation signal is performed first in time, and the playback of the HF excitation signal is performed second in time. Although in these two embodiments, the electrical parameters (Re, Le) are estimated first and then used to estimate the mechanical parameters (Res, Lces, Cmes or Res, F0 and Q). In addition, in other embodiments, as long as the HF excitation signal and the LF broadband excitation signal do not generate mutually interfering harmonics, the playback of the HF excitation signal and the playback of the LF broadband excitation signal are performed simultaneously.

[0042] exist Figure 8In the example shown, the peak amplitude of the HF excitation signal is approximately 0.2 volts. However, other embodiments are contemplated in which the peak amplitude of the HF excitation signal is other values. Furthermore, if more cycles are played, so that a similar amount of energy is applied to excite the electromechanical actuator, the amplitude of the HF excitation signal may be reduced (e.g., to reduce or avoid interference with the user). Figure 8 In the example shown, the peak amplitude of the LF broadband excitation signal is approximately 1 volt, but embodiments with other peak amplitudes are also contemplated. Furthermore, if multiple broadband cycles are played, the amplitude of the LF broadband excitation signal can be reduced, thereby improving the signal-to-noise ratio (SNR). Furthermore, the playback of the HF and / or LF broadband excitation signals and the measurement of their responses can be repeated multiple times to improve the SNR.

[0043] exist Figure 8 In the example of , the HF excitation signal is a 2 kHz sinusoidal tone. However, other embodiments using high frequencies other than 2 kHz can be envisaged. For example, the HF excitation signal can be significantly higher than the resonant frequency of the electromechanical actuator, e.g. high enough to avoid overlapping of the frequency responses of the electromechanical actuator to the corresponding HF and LF broadband excitation signals. In other words, taking into account the electrical (coil) and mechanical (resonant tank) construction of the electromechanical actuator, the frequency of the HF excitation tone may be high enough to avoid interfering with the response of the coil to the HF excitation signal resulting from the mechanical resonance of the electromechanical actuator. In other words, the HF excitation signal can be outside the frequency band of the resonant frequency of the electromechanical actuator, such as e.g. Figure 5 In one embodiment, the HF excitation signal tone frequency may be within a frequency range centered about five to ten times the mechanical resonant frequency of the electromechanical actuator to create a significant frequency gap between the HF excitation signal and the LF broadband excitation signal.

[0044] exist Figure 8 In the example of , the LF broadband excitation signal comprises 2 cycles of a 200 Hz sinusoidal waveform multiplied by a Nuttall window. While the resonant frequency F0 may be one of the parameters of the electromechanical actuator determined by the described embodiments, the possible range of resonant frequencies may be experimentally predetermined by testing a sample of electromechanical actuator instances and used to design the LF broadband excitation signal. The possible resonant frequency range may then be used to select a frequency of a sinusoidal waveform (multiplied by the window) of the LF broadband excitation signal centered around that range, and the window may be selected to cover a band of the resonant frequency range spectrally. In other words, the predetermined range may be understood as an a priori guess at a resonant frequency that is more accurately estimated using the parameter estimation embodiments of the present disclosure. Therefore, although Figure 8The frequency of the sine waveform in the example is 200 Hz, but other frequencies may be selected based on a predetermined range of possible resonant frequencies. In addition, as described above, the sine waveform may be multiplied by other types of windows.

[0045] In one embodiment, an HF excitation signal and / or an LF broadband excitation signal may be applied to the electromechanical actuator, and its response may be measured multiple times to improve the signal-to-noise ratio (SNR). Furthermore, during the multiple applications of the LF broadband excitation signal, one or more parameters of the LF broadband excitation signal may be adjusted, such as the frequency of the sinusoidal waveform, the amplitude of the sinusoidal waveform, the integer number of periods of the sinusoidal waveform, and the type of window multiplied by the sinusoidal waveform.

[0046] Given that the signal processing computation time can be small relative to the excitation and measurement times, it can be observed that characterizing an electromechanical actuator in the described segmented manner can require only about tens of milliseconds, which can be significantly faster than previous approaches, resulting in the advantages described herein. The characterization time can vary depending on various factors, such as the resonant frequency of the electromechanical actuator, the number of samples of each of the HF and LF excitation signal components, and the number of times the excitation signal is applied and the response is measured.

[0047] Furthermore, embodiments of the present disclosure can enjoy the benefit of lower power consumption compared to conventional methods such as the chirp method described above. Conventional methods employing chirp stimulation can consume relatively large amounts of power due to the long duration required to sweep across the frequency range to achieve a response from the coil and resonant tank. In contrast, embodiments of the present disclosure divide the stimulation into two parts separated by a gap—the HF and LF components specifically targeting the coil and resonant tank, respectively—each of which can be a relatively narrow frequency band (in fact, the HF stimulation can be a tone), and each part can be a small number of cycles, and therefore consume very little power relative to conventional chirp stimulation methods. For similar reasons, embodiments of the present disclosure can consume less power than conventional pulse methods due to the relatively large pulse amplitudes required.

[0048] It should be understood, especially by those of ordinary skill in the art having the benefit of this disclosure, that the various operations described herein, particularly those associated with the accompanying drawings, may be implemented by other circuits or other hardware components. Unless otherwise indicated, the order in which each operation of a given method is performed may be changed, and the various elements of the systems shown herein may be added, reordered, combined, omitted, modified, etc. This disclosure is intended to encompass all such modifications and variations, and therefore, the above description should be considered illustrative rather than restrictive.

[0049] Similarly, although this disclosure is directed to specific embodiments, certain modifications and changes may be made to these embodiments without departing from the scope and coverage of this disclosure. In addition, any benefits, advantages, or solutions to problems described herein with respect to specific embodiments are not intended to be construed as key, required, or essential features or elements.

[0050] Likewise, further embodiments will be apparent to those skilled in the art with the benefit of this disclosure, and such embodiments should be considered to be included herein. 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 advance the art, and are to be interpreted as not being limited to these specifically recited examples and conditions.

[0051] This disclosure includes all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that would be understood by a person of ordinary skill in the art. Similarly, the appended claims cover all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that would be understood by a person of ordinary skill in the art, where appropriate. In addition, in the appended claims, references to a device or system or component of a device or system that is adapted, arranged, capable, configured, enabled, operable, or operative to perform a particular function include that device, system, or component, regardless of whether it or that particular function is activated, turned on, or unlocked, so long as the device, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative.

[0052] Finally, software can cause or configure the functionality, fabrication, and / or description of the apparatus and methods described herein. This can be implemented using a general-purpose programming language (e.g., C, C++), a hardware description language (HDL) (including Verilog HDL, VHDL, etc.), or other available programs. Such software can be provided on any known non-transitory computer-readable medium, such as a tape, semiconductor, magnetic or optical disk (e.g., CD-ROM, DVD-ROM, etc.), a network, a wired line, or another communication medium, on which are stored instructions capable of causing or configuring the apparatus and methods described herein.

[0053] To assist the Patent Office and any reader of this application and any patent that issues herefrom in interpreting the appended claims, Applicants wish to indicate that they do not intend for any appended claim or claim element to be incorporated by reference in accordance with 35 U.S.C. §112(f) unless “means for” or “step for” are expressly used in a particular claim. Furthermore, use of the term “configured to” is not intended to be incorporated by reference in accordance with 35 U.S.C. §112(f).

Claims

1. A method comprising: applying a high frequency signal to an electromechanical actuator and measuring a first response of the electromechanical actuator to the high frequency signal; estimating an electrical parameter of the electromechanical actuator based on the first response; applying a low-frequency, broadband signal to the electromechanical actuator and measuring a second response of the electromechanical actuator to the low-frequency, broadband signal; as well as A mechanical parameter of the electromechanical actuator is estimated based on the second response and the estimated electrical parameter.

2. The method according to claim 1, in, The applying of the high frequency signal and the applying of the low frequency broadband signal are performed simultaneously.

3. The method according to claim 2, in, The high frequency signal and the low frequency broadband signal are selected such that they do not generate harmonics that interfere with each other.

4. The method according to claim 1, in, The applying of the high-frequency signal is performed before the applying of the low-frequency broadband signal.

5. The method according to claim 1, in, The applying of the high-frequency signal is performed after the applying of the low-frequency broadband signal.

6. The method according to claim 1, further comprising: The electrical parameters and the mechanical parameters of the electromechanical actuator are estimated during calibration of the electromechanical actuator during manufacturing of a device comprising the electromechanical actuator.

7. The method according to claim 1, further comprising: The electrical and mechanical parameters of the electromechanical actuator are estimated during consumer operation of a device including the electromechanical actuator.

8. The method according to claim 1, in, The electrical parameters and the mechanical parameters are obtained in less than 50 milliseconds.

9. The method according to claim 1, in, The applying of the high frequency signal and measuring the first response and / or the applying of the low frequency broadband signal and measuring the second response are repeated multiple times to improve a signal-to-noise ratio.

10. The method according to claim 1, in, The low-frequency broadband signal spectrally covers a frequency band centered around a range of mechanical resonance frequencies experimentally predetermined from a sample of instances of the electromechanical actuator.

11. The method according to claim 1, in, The low-frequency broadband signal includes a sinusoidal waveform multiplied by a window.

12. The method according to claim 11, in, The applying of the low frequency broadband signal and the measuring of the second response are repeated a plurality of times; and For each of the multiple times, one or more of the following are adjusted: the frequency of the sinusoidal waveform; the amplitude of the sinusoidal waveform; an integer number of cycles of the sinusoidal waveform; and The type of window.

13. The method according to claim 11, in, The high frequency signal is sufficiently higher than the frequency of the sinusoidal waveform of the low frequency broadband signal to avoid overlap in their respective frequency responses.

14. The method according to claim 1, in, The high frequency signal is sufficiently high to avoid interference with the first response from mechanical resonance of the electromechanical actuator.

15. The method according to claim 14, in, The high frequency signal is approximately one order of magnitude higher than the resonant frequency of the electromechanical actuator.

16. The method according to claim 1, in, The high-frequency signal is outside the frequency band of the resonant frequency of the electromechanical actuator.

17. The method according to claim 1, in, The estimating the mechanical parameter comprises: calculating a back electromotive force voltage using the estimated electrical parameter and the measured second response; and The mechanical parameter is estimated using the calculated back-EMF voltage and the measured second response.

18. The method according to claim 1, in, The electrical parameters include direct current (DC) resistance (Re); as well as Wherein, estimating the electrical parameter comprises: estimating Re based on the first response; and A predetermined scaling factor is applied to the estimated Re to compensate for shifts in the real part of the impedance of the coil portion of the electromechanical actuator at high frequencies.

19. The method according to claim 1, in, The estimating the electrical parameter includes compensating for an offset of a circuit used to measure the first response.

20. The method according to claim 1, in, The electrical parameters include a direct current (DC) resistance (Re) and an electrical coil inductance (Le) of the electromechanical actuator; and The mechanical parameters include the resonant resistance (Res), the resonant frequency (F0) and the quality factor (Q) of the electromechanical actuator or their equivalents.

21. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing a method, the method comprising: applying a high frequency signal to an electromechanical actuator and measuring a first response of the electromechanical actuator to the high frequency signal; estimating an electrical parameter of the electromechanical actuator based on the first response; applying a low-frequency, broadband signal to the electromechanical actuator and measuring a second response of the electromechanical actuator to the low-frequency, broadband signal; as well as A mechanical parameter of the electromechanical actuator is estimated based on the second response and the estimated electrical parameter.

22. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The applying of the high frequency signal and the applying of the low frequency broadband signal are performed simultaneously.

23. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 22, in, The high frequency signal and the low frequency broadband signal are selected such that they do not generate harmonics that interfere with each other.

24. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The applying of the high-frequency signal is performed before the applying of the low-frequency broadband signal.

25. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The applying of the high-frequency signal is performed after the applying of the low-frequency broadband signal.

26. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, further comprising: The electrical parameters and the mechanical parameters of the electromechanical actuator are estimated during calibration of the electromechanical actuator during manufacturing of a device comprising the electromechanical actuator.

27. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, further comprising: The electrical and mechanical parameters of the electromechanical actuator are estimated during consumer operation of a device including the electromechanical actuator.

28. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The electrical parameters and the mechanical parameters are obtained in less than 50 milliseconds.

29. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The applying of the high frequency signal and measuring the first response and / or the applying of the low frequency broadband signal and measuring the second response are repeated multiple times to improve a signal-to-noise ratio.

30. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The low-frequency broadband signal spectrally covers a frequency band centered around a range of mechanical resonance frequencies experimentally predetermined from a sample of instances of the electromechanical actuator.

31. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The low-frequency broadband signal comprises a sinusoidal waveform multiplied by a window.

32. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 31, in, applying the low-frequency broadband signal and measuring the second response are repeated a plurality of times; as well as For each of the multiple times, one or more of the following are adjusted: the frequency of the sinusoidal waveform; the amplitude of the sinusoidal waveform; an integer number of cycles of the sinusoidal waveform; and The type of window.

33. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 31, in, The high frequency signal is sufficiently higher than the frequency of the sinusoidal waveform of the low frequency broadband signal to avoid overlap in their respective frequency responses.

34. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The high frequency signal is sufficiently high to avoid interference with the first response from mechanical resonance of the electromechanical actuator.

35. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 34, in, The high frequency signal is approximately one order of magnitude higher than the resonant frequency of the electromechanical actuator.

36. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The high frequency signal is outside the frequency band of the resonant frequency of the electromechanical actuator.

37. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The estimating the mechanical parameter comprises: calculating a back electromotive force voltage using the estimated electrical parameter and the measured second response; and The mechanical parameter is estimated using the calculated back-EMF voltage and the measured second response.

38. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The electrical parameters include direct current (DC) resistance (Re); as well as Wherein, estimating the electrical parameter comprises: estimating Re based on the first response; and A predetermined scaling factor is applied to the estimated Re to compensate for shifts in the real part of the impedance of the coil portion of the electromechanical actuator at high frequencies.

39. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The estimating the electrical parameter includes compensating for an offset of a circuit used to measure the first response.

40. A non-transitory computer-readable storage medium having computer program instructions stored thereon for implementing the method of claim 21, in, The electrical parameters include a direct current (DC) resistance (Re) and an electrical coil inductance (Le) of the electromechanical actuator; and The mechanical parameters include the resonant resistance (Res), the resonant frequency (F0) and the quality factor (Q) of the electromechanical actuator or their equivalents.

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