CN116155167B - A tracking method and detection device for the resonance frequency of a linear motor - Google Patents
A tracking method and detection device for the resonance frequency of a linear motor Download PDFInfo
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- CN116155167B CN116155167B CN202111438413.4A CN202111438413A CN116155167B CN 116155167 B CN116155167 B CN 116155167B CN 202111438413 A CN202111438413 A CN 202111438413A CN 116155167 B CN116155167 B CN 116155167B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/032—Reciprocating, oscillating or vibrating motors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
- H02P23/14—Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/06—Linear motors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
A method and apparatus for tracking the resonant frequency of a linear motor are disclosed. According to an embodiment, a method for tracking a resonant frequency of a linear motor may include controlling the linear motor to enter a high-impedance state and acquiring a reverse electromotive force signal, performing zero-crossing detection on the reverse electromotive force signal, acquiring two sampling electromotive forces and a third sampling electromotive force after the two sampling electromotive forces which are equally spaced after a zero-crossing time when the zero-crossing is detected, and determining a resonant frequency of the linear motor according to the acquired three sampling electromotive forces and sampling parameters. The invention can realize the acquisition of the real resonant frequency of the linear motor based on the acquisition signal in a short time, thereby providing a reference for controlling the motor.
Description
Technical Field
The present application relates to the field of electronic devices, and more particularly, to a method and apparatus for tracking and detecting a resonant frequency of a linear motor.
Background
Haptic feedback techniques are typically implemented by motor vibration. The linear motor mainly comprises a spring, a mass block with magnetism, a coil and other components, and the mass block is suspended inside the motor by the spring. The mass can move up and down in an applied varying magnetic field, which vibration is perceived by humans to produce a haptic effect.
In operation, to efficiently generate haptic effects, the spring-loaded mass is ideally driven at its natural resonant frequency. For example, the closer the frequency of the driving waveform is to the true resonant frequency of the motor, the shorter the time it takes for the motor to come into resonance, the more pronounced the vibration effect, while in the braking phase, the closer the frequency of the driving waveform is to the true resonant frequency of the motor, the more rapid the braking of the motor can be achieved. Therefore, obtaining an accurate motor resonance frequency is an important precondition for achieving vibration control.
When the actual resonant frequency of the intelligent device deviates from the resonant frequency of the factory design due to the use environment, element aging and other reasons, the vibration quantity of the motor is changed. The existing method for detecting the resonant frequency of the linear motor is generally applied to fewer scenes such as starting up, is low in speed and easy to cause burrs of vibration quantity, and is difficult to truly track the resonant frequency of the linear motor in real time.
Disclosure of Invention
The present application has been made to solve the above-mentioned technical problems occurring in the prior art. The embodiment of the application provides a tracking detection method, a detection device and a control system for the resonant frequency of a linear motor, which can rapidly determine the resonant frequency, so that the frequency calibration of a driving waveform is conveniently carried out according to the requirement, and the optimal vibration control effect is achieved.
According to one aspect of the application, a tracking method of a resonance frequency of a linear motor is provided, comprising controlling the linear motor to enter a high-impedance state and acquiring a reverse electromotive force signal, performing zero-crossing detection on the reverse electromotive force signal, acquiring two sampling electromotive forces and a third sampling electromotive force, wherein the two sampling electromotive forces are equally spaced after zero-crossing time and the third sampling electromotive force is equal to the two sampling electromotive forces when zero crossing is detected, and determining the resonance frequency of the linear motor according to the three acquired sampling electromotive forces and sampling parameters.
In some embodiments, before controlling the motor to enter the high impedance state, further comprising adding a number of cycles of overdrive waveform to drive the linear motor before the drive waveform begins in response to receiving a tracking enable signal of the resonant frequency before driving the linear motor.
In some embodiments, the time for which the back electromotive force is acquired is less than half a resonance period.
In some embodiments, the zero-crossing detection of the back electromotive force signal comprises comparing the amplitude of the back electromotive force of the acquired sampling point with a set threshold value to determine the zero-crossing time of the back electromotive force, or judging the polarity of the back electromotive force of the acquired sampling point to determine the zero-crossing time when the polarity of the back electromotive force changes.
In some embodiments, obtaining the two sampled electromotive forces with equal intervals after the zero crossing time and the third sampled electromotive force after the two sampled electromotive forces comprises determining the zero crossing time according to the later sampling point in the two sampling points with the polarity changed, wherein the two sampling points are provided with a sampling point interval m, m is a positive integer, setting a sampling ordinal number N, and obtaining the inverse electromotive forces of the Nth, 2Nth and (2N+1) th sampling points after the zero crossing time as the three sampled electromotive forces, wherein N is a positive integer.
In some embodiments, the equally spaced two sampled electromotive forces include a preceding first sampled electromotive force and a following second sampled electromotive force, determining a resonant frequency of the linear motor from the acquired three sampled electromotive force signals and sampling parameters includes calculating an amplitude of an inverse electromotive force of a correction sampling point from the amplitudes of the second sampled electromotive force and the third sampled electromotive force, and determining the resonant frequency of the linear motor based on the amplitude of the first sampled electromotive force, the amplitude of the inverse electromotive force of the correction sampling point, and the sampling parameters.
In some embodiments, the method further comprises determining the correction factor based on magnitudes of back electromotive forces of two sampling points where the polarity is changed, the magnitudes of back electromotive forces of the correction sampling points being associated with the correction factor.
In some embodiments, determining the resonant frequency of the linear motor based on the first sampled electromotive force, the counter electromotive force of the corrected sampling point, and the sampling parameter includes determining a ratio r of both the magnitude of the counter electromotive force of the corrected point and the magnitude of the first sampled electromotive force, and determining the resonant frequency of the linear motor based on at least the ratio r and the sampling parameter, wherein the resonant frequency is positively correlated with the ratio r and negatively correlated with the time interval of the second sampled electromotive force from the zero crossing time.
Another aspect of the present application provides a tracking and detecting apparatus for a resonant frequency of a linear motor, including a monitoring unit for acquiring a reverse electromotive force signal after controlling the linear motor to enter a high-resistance state, and a calculating unit for performing zero-crossing detection on the reverse electromotive force signal, acquiring two sampling electromotive forces and a third sampling electromotive force after the two sampling electromotive forces which are equally spaced after the zero-crossing time when zero crossing is detected, and determining the resonant frequency of the linear motor according to the acquired three sampling electromotive forces and sampling parameters.
Another aspect of the present application also provides a linear motor drive control system including the aforementioned linear motor tracking detection device, and a drive circuit that drives the linear motor according to the determined resonance frequency.
Compared with the prior art, the tracking detection method and device for the resonant frequency of the linear motor can be applied to any driving mode, the real resonant frequency of the motor can be rapidly and accurately determined in a short time, the method and device can be directly applied to detection or tracking of scenes, meanwhile, the resonant frequency can be detected without a plurality of resonant periods, waveforms to be played in other scenes are hardly influenced, the resonant frequency can be calculated and output in real time, frequency amplitude correction is conveniently carried out on the driving waveform according to requirements, the vibration control effect of the motor is improved, and therefore user experience is remarkably improved.
Drawings
The above and other objects, features and advantages of the present application will become more apparent by describing embodiments of the present application in more detail with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate the application and together with the embodiments of the application, and not constitute a limitation to the application. In the drawings, like reference numerals generally refer to like parts or steps.
FIG. 1 shows a flow chart of a method for tracking resonant frequency of a linear motor according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a method for controlling a motor to enter a high resistance state according to an embodiment of the present application;
Fig. 3 is a schematic diagram showing a sample electromotive force signal after zero crossing detection and zero crossing time acquisition according to an embodiment of the present application;
FIG. 4 illustrates a flow chart of a method of determining a resonant frequency of a linear motor provided in accordance with an embodiment of the present application;
FIG. 5 shows a flow chart of a method of determining the resonant frequency of a linear motor according to an embodiment of the present application;
fig. 6 shows a flowchart of a linear motor drive control method provided according to an embodiment of the present application;
FIG. 7 shows a block diagram of a linear motor resonant frequency tracking detection device provided in accordance with an embodiment of the present application;
fig. 8 illustrates a block diagram of a linear motor control system provided according to an embodiment of the present application.
Detailed Description
Hereinafter, exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings. It will be apparent that the described embodiments are only some of the embodiments of the present application and not all of the embodiments of the present application. Also, not all of the above advantages need be achieved at the same time to practice any of the examples of embodiments of the application. It should be understood that the application should not be limited to the specific details of these example embodiments. Rather, embodiments of the application may be practiced without these specific details or in other alternative ways, without departing from the spirit and principles of the application, which are defined by the claims.
Embodiments herein provide a tracking method of a resonant frequency of a linear motor, which is mainly applied to detecting the resonant frequency of the linear motor. Referring to fig. 1, which is a flowchart illustrating a method for tracking and detecting a resonant frequency of a linear motor according to an embodiment of the present application, as shown in fig. 1, the method 100 may include the following steps:
step S110, the linear motor is controlled to enter a high-resistance state, and a reverse electromotive force signal is obtained.
The counter electromotive force is induced by the movement of the permanent magnet (mass) of the motor relative to the wound coil, and the induced counter electromotive force signal will also have this resonance frequency as the mass vibrates at the natural resonance frequency. In one embodiment, the back electromotive force may be obtained by collecting electromotive forces generated at both ends thereof by the movement of the linear motor. In an embodiment, the motor can be driven to enter a high-resistance state by switching off, for example, and in the high-resistance state, the back electromotive force can be directly detected and obtained without a driving signal, and the back electromotive force is not separated from a monitoring signal by means of complex calculation.
In an embodiment, the linear motor may implement the resonant frequency tracking method of the present invention after receiving a tracking enable signal, where the enable signal may be triggered by a user or according to a driving mode, for example, a corresponding tracking enable signal may be generated according to a current driving state, and the control system generates a control signal for controlling the output of the driving chip to bring the motor into a high impedance state after receiving the enable signal.
Fig. 2 is a schematic diagram of a method for controlling a motor to enter a high-resistance state according to an embodiment of the application. As shown in fig. 2, the resonant frequency tracking of the present application may be implemented in an arbitrary driving period of the linear motor, that is, the motor may be controlled to be in a high-impedance state accordingly based on a driving state such as before driving, during driving, or at the end of driving.
Referring to fig. 2, it may be determined that a driving state when a tracking enable signal is received, for example, in response to a tracking enable signal of a resonant frequency being received before a linear motor is driven, i.e., if a frequency tracking enable signal 1 is triggered, at this time, a driving waveform is not yet played, a super-drive waveform of several periods may be added before a driving waveform to be played starts to drive the linear motor, and in response to the tracking enable signal 1 being disconnected to enter a high-impedance state, and then the driving waveform may start to drive the motor to vibrate after the tracking is completed, and if an enable signal is received during vibration in response to the motor entering a vibration state, for example, a frequency tracking enable signal 2 is triggered and playing is underway, a current driving is disconnected for a predetermined time, and a vibration waveform is restored after the tracking is completed, in response to a reception enable signal, for example, a frequency tracking enable signal 3 is triggered, and a resonant frequency is directly tracked for a residual vibration, and a resonant frequency is outputted after the tracking is completed.
It should be noted that while the enable signal 1, the enable signal 2, and the enable signal 3 are digitally distinguished in fig. 2, it is understood that these enable signals may also use the same triggers and remain within the scope of the present application.
The resonant frequency tracking method of the embodiment can be implemented at any position of the vibration driving waveform played by the linear motor driving chip, for example, tracking can be realized before the driving waveform starts in any driving mode, short-cut driving can be realized at any position in long vibration driving, and tracking can be realized when waveform playing is finished. The resonance frequency is tracked and updated in real time while the vibration is not influenced, so that the driving frequency can be adjusted according to actual needs, the stable vibration quantity of the motor is ensured, and the motor vibrates with the highest energy efficiency ratio.
In one embodiment, the two terminal pins of the motor are grounded to discharge the linear motor into a high resistance state. Specifically, the grounding discharge can be performed on the pins at two ends of the motor before the back electromotive force signals are collected, and the short contact discharge can enable the voltage signals detected at two ends of the input pin of the motor to be close to the real back electromotive force signals.
If the back electromotive force signal is collected for too long, vibration burrs and depressions will be generated, for example, for the above-described tracking enable signal 2, i.e., in a normal driving state, if the off driving time is long, the motor amplitude will be unstable, which will adversely affect the haptic effect. For this reason, unlike some prior arts, in an embodiment of the present invention, only a short, predetermined length of the back electromotive force signal may be collected, and then the operation of starting driving, resuming driving, or changing the driving signal to perform the operation of braking may be performed according to the actual situation. The predetermined duration of the collected back electromotive force signal may be less than half a resonance period of the linear motor, which may be converted by tracking a resonance frequency of the obtained motor during vibration, which may reduce adverse effects on a user's haptic effect, and may advantageously perform a subsequent control operation in rapid response.
In one embodiment, after the acquisition of the back electromotive force signal, the acquired electromotive force signal may be subjected to signal processing, for example, low-pass filtering may be performed first, and then a signal of interest without burrs may be obtained through smoothing preprocessing.
Returning to fig. 1, step S120 may be performed after the back electromotive force signal is acquired, and zero-crossing detection may be performed on the acquired back electromotive force signal.
For example, the acquired back electromotive force signal may be sampled first, and zero-crossing detection may be performed based on the sampled data. The frequency at which the back electromotive force is sampled may be in the range of 12-96kHz, for example, a sampling frequency of 24-48 kHz.
In an embodiment, the amplitude of the acquired back electromotive force signal at the sampling point may be compared with a set threshold value to determine whether the acquired back electromotive force signal has zero crossing and the zero crossing time. For example, the amplitude of each back electromotive force of the sampling sequence is compared with a reference threshold value, if the detected back electromotive force is smaller than the set reference threshold value, the back electromotive force is indicated to have zero crossing, and the zero crossing moment corresponding to the zero crossing state is determined.
In another embodiment, polarity judgment can be performed on the obtained reverse electromotive force of the sampling point, and the zero crossing time when the polarity of the reverse electromotive force changes can be determined.
Referring to fig. 3, a schematic diagram of zero crossing detection provided in accordance with an embodiment of the present application is shown. For example, the polarity of the sampled back electromotive force may be determined, and if the polarities of the back electromotive forces of two adjacent or spaced sampling points are the same, zero crossing may not be considered to occur, whereas if the back electromotive forces of two adjacent or spaced sampling points change direction, for example, when the back electromotive force changes from positive to negative or from negative to positive, the zero crossing may be determined to occur.
As shown in fig. 3, polarities of two adjacent or spaced sampling points (t_l, s_l) and (t_r, s_r) may be detected, where t_ L, t _r is a time of two sampling points, respectively, which are spaced apart by m sampling points (m is a positive integer, for example, 1, 2, 3..equal), s_ L, s _r is a magnitude of a counter electromotive force of the two sampling points, respectively, and if it is detected that the polarities of s_ L, s _r are opposite, it may be determined that the counter electromotive force crosses zero, and a time corresponding to the counter electromotive force sampling point after the change may be determined as a zero crossing time, for example, t_r may be determined as a zero crossing time, and the magnitudes of the two sampling points and the sampling point interval m may be recorded. It can be seen that t_ L, t _r is not the true zero crossing instant, which may also be referred to as a quasi zero crossing, for which reason in one embodiment the zero crossing time may be modified, as will be described in more detail later.
In one embodiment, the sampling operation and the zero crossing detection of the back electromotive force signal may be performed simultaneously, and a timer may be started after the zero crossing time is detected, starting to count time, and the driving may be resumed after a predetermined time after the zero crossing time, wherein the predetermined time may be less than a quarter of the resonance period. It can be seen that, in the resonant frequency tracking method of the embodiment, only one zero crossing state is required to exist in the acquired back electromotive force signal, and compared with the method for determining the resonant frequency based on more than two zero crossing points in the prior art, the method can greatly shorten the duration of the disconnection driving, thereby minimizing the influence on the vibration effect of the motor.
After the zero-crossing detection, the tracking method of the present application may proceed to step S130, and upon detecting that zero crossing occurs, two sampled electromotive forces at equal intervals after the zero-crossing time and a third sampled electromotive force after the two sampled electromotive forces are acquired.
When the zero crossing is detected, the zero crossing time may be determined first and two sampling points (hereinafter, referred to as a first sampling electromotive force and a second sampling electromotive force, respectively) and a third sampling electromotive force after the two sampling points, which are equally spaced in time sequence of the sampling sequence, may be selected with the zero crossing time as a starting point. The zero crossing time may be determined by the method described above, for example, in a manner of comparing the amplitude of the acquired back electromotive force signal with a set threshold, a time corresponding to a sampling point smaller than the set threshold may be determined as the zero crossing time, and in a manner of determining the polarity of the back electromotive force of adjacent or separated sampling points, a time corresponding to one of two sampling points, in which the polarity is changed, may be selected as the zero crossing time.
In an embodiment, the zero crossing time may be determined according to a subsequent sampling point of the two sampling points where the polarity change occurs, where a sampling point interval m is between the two sampling points, that is, the interval between the two sampling points in time sequence is m/fs, where m is a positive integer, and fs is a sampling frequency, and the sampling number N is set at the same time, and the counter electromotive forces of the n×m, 2n×m, and (2n+1) ×m sampling points after the zero crossing time are obtained as three sampling electromotive forces for determining the resonance frequency subsequently, where N is a positive integer.
Still referring to fig. 3, for example, when it is determined that s_ L, s _r of m sampling points have opposite polarities, t_r may be determined as zero crossing time and two sampling electromotive force signals equally spaced in time series and a third sampling point after the two sampling points are selected with the zero crossing time as a starting point, preferably, the interval is an integer multiple of the sampling point interval m, so as to facilitate the subsequent calculation of the resonance frequency, i.e., the first sampling electromotive force signal may be expressed as (t_n, s_n) = (t N*m,sN*m), and the second sampling electromotive force signal may be expressed as (t_2n, s_2n) = (t 2N*m,s2N*m). The third sampling point and the second sampling point have a set time interval, preferably, m sampling points are also spaced between the third sampling point and the second sampling point, that is, the electromotive force signal of the third sampling point may be represented as (t_2n+1, s_2n+1) = (t (2N+1)*m,s(2N+1)*m), where m and N are positive integers, for example, values of 1,2,3, 4, 5, etc., n×m, 2n×m, (2n+1) ×m represents the sampling sequence numbers of the first sampling point, the second sampling point, and the third sampling point after t_r, and the time of the three sampling point distances t_r is n×m/fs, 2n×m/fs, and (2n+1) ×m/fs, respectively, where the sampling frequency fs is predetermined.
In a specific example, for example, the sample interval m may be set to 1, the sampling number N may be set to 5, and accordingly, the three selected sampling points are (t_5, s_5), (t_10, s_10), (t_11, s_11), respectively, that is, the second sampling point and the third sampling point are adjacent sampled electromotive signals.
Returning to fig. 1, after acquiring three sampled electromotive force signals, the method may proceed to step S140 to determine the resonant frequency of the linear motor from the acquired three sampled electromotive force signals and the sampling parameter. After the zero crossing point, the motor can be considered to oscillate with damping, so that the true resonant frequency of the linear motor can be determined from the relation between the magnitudes of the three sampled electromotive signals and the associated sampling parameters and damping coefficients. The sampling parameters may include a time parameter and/or a frequency parameter, the time parameter may be a time interval between three sampling electromotive forces and a zero crossing time, and the frequency parameter may be a sampling frequency.
As described above, since the determined zero-crossing time t_r is not an actual zero-crossing point, in order to calculate and obtain the resonant frequency of the linear motor more accurately, zero-crossing correction may be performed, and the resonant frequency of the motor may be determined based on the electromotive force signal of the corrected sampling point.
Fig. 4 shows a flowchart of a method of determining a resonant frequency of a linear motor according to an embodiment of the present application. As shown in fig. 4, the method for determining the resonant frequency of the linear motor by means of correction includes:
in step S210, the amplitude of the back electromotive force of the corrected sampling point is calculated from the amplitudes of the second sampled electromotive force and the third sampled electromotive force.
In one embodiment, a modified sampling point may be set, where the modified sampling point is set between a second sampling point (for example, 2n+1 th sampling point) and a third sampling point (for example, 2n+1 th sampling point), and the interval (m) between the second sampling point and the third sampling point is the same as the interval (m) between two sampling points (t_ L, t _r) where the inversion is determined to occur.
To determine the back electromotive force of the corrected sampling point, in one embodiment, the correction factor may be determined according to the back electromotive force of the two sampling points, the polarities of which are changed, the magnitude of the back electromotive force of the corrected sampling point being associated with the correction factor.
Referring to fig. 3, when the zero crossing time occurs according to the polarities of the sampling points (t_l, s_l), (t_r, s_r), the correction factor c may be determined as follows:
c=|s_R|/(|s_L|+|s_R|)。
on this basis, the magnitude of the back electromotive force of the corrected sampling point can be estimated, and for example, the back electromotive force s' 2N of the corrected sampling point can be calculated as follows:
s '2N＝(1-c)*s2N+c*s2N+1, where s 2N、s2N+1 in the formula corresponds to s_2n and s_ (2n+1) shown in fig. 3, s' 2N obtained by calculation can be regarded as a correction of the back electromotive force of 2n×m sampling points after the time t_r.
In step S220, a resonant frequency of the linear motor is determined based on the magnitude of the first sampled electromotive force, the magnitude of the inverse electromotive force of the corrected sampling point, and the sampling parameter.
In the case where the back electromotive force of the correction point is estimated, the resonance frequency of the linear motor may be determined according to the relationship between the back electromotive force of the first sampling point (for example, the nth sampling point) and the magnitude of the back electromotive force of the correction sampling point, and sampling parameters such as the sampling frequency, the sampling interval, and the like.
Fig. 5 is a flowchart of a calculation method for determining a resonant frequency of a linear motor according to an embodiment of the present application, and as shown in fig. 5, the calculation method may include the following steps:
step S310, determining a ratio r between the magnitude of the back electromotive force of the correction point and the magnitude of the first sampling electromotive force.
This ratio r can be regarded as the ratio of the back electromotive forces at two time points equally spaced after the zero-crossing point t ZC, and can be expressed as follows with reference to fig. 3: where s N corresponds to the magnitude s_n of the back electromotive force at the nth sample point shown in fig. 3.
In step S320, the resonant frequency of the linear motor is determined based on at least the ratio r and the sampling parameter, where the sampling parameter may include a time parameter and/or a frequency parameter, the time parameter may be a time interval between three sampled electromotive forces and a zero crossing time, and the frequency parameter may be a sampling frequency. For example, the resonance frequency is positively correlated with the ratio r and negatively correlated with the time interval of the second sampled electromotive force from the zero crossing time.
In one embodiment, the resonant frequency of the linear motor may be determined by the following calculation:
f=p×r+q, where f is the resonant frequency of the motor, p is a value related to the sampling parameter and motor damping, for example, it may be expressed as p=k/(Δt×d) =k×fs/(2n×m×d), i.e., f is positively related to the ratio R, and is negatively related to the time interval Δt of the second sampled electromotive force from the zero crossing time t_r, and specifically to the sampling interval m, the sampling number N, where k is a constant, which can be adjusted according to actual needs, D is the motor damping, q is a correction value of p, and the correction relationship may be predetermined through experiments.
Fig. 6 shows a flowchart of a linear motor driving control method provided according to an embodiment of the present application, which may be controlled in response to the tracking enable signal 2 of fig. 2, for example, as shown in fig. 6, including:
In step S410, the driving is turned off. For example, the application of the driving voltage or the driving signal to the linear motor is stopped.
In step S420, the two ends of the input pin of the motor are briefly grounded and discharged to a high-resistance state, so that the voltage signal across the two ends of the motor, which is measured later, can be made to approach the back electromotive force.
In step S430, the back electromotive force signal generated by the motor in the high-resistance state is collected, and signal processing such as filtering and smoothing processing may be performed. In one embodiment of the application, the time taken can be less than the half-resonance period of the motor, and by reducing the time to turn off the drive, the adverse impact on the user's haptic effect can be reduced.
In step S440, zero-crossing detection is performed on the acquired back electromotive force, and the resonance frequency of the obtained motor is calculated.
For example, the method described with reference to FIGS. 1-5 may be employed, and will not be repeated here.
In step S450, the driving is resumed at the disconnected position of the return waveform, where the driving waveform can be modified according to the determined resonant frequency to obtain a driving waveform with an actual resonant frequency, and the driving waveform with the actual resonant frequency is adopted to resume driving the linear motor at the disconnected position, so that the motor has a better driving effect.
It will be appreciated that although described above with respect to the tracking enable signal 2 only, the control procedure is equally applicable to the tracking enable signal 1 or the tracking enable signal 3, for example, in response to the tracking enable signal 3, an embodiment of the present application may employ a modified driving waveform having an actual resonant frequency to drive the motor to vibrate, thereby shortening the time required for braking the motor and reducing the driving power consumption of the motor.
According to the tracking method for the motor resonant frequency, the actual resonant frequency of the motor can be accurately obtained through detecting the obtained back electromotive force in a short time, the method can be directly applied to detection or tracking of scenes, and the resonant frequency can be detected without a plurality of resonant periods, so that waveforms to be played in other scenes are hardly affected, and the overall vibration effect of the motor can be improved.
The embodiment of the application also provides a device for tracking and detecting the resonant frequency of the linear motor. As shown in fig. 7, the linear motor control apparatus 500 according to an embodiment of the present application may include a monitoring unit 510 connected to a motor for acquiring a reverse electromotive force signal after controlling the linear motor to enter a high resistance state, and a calculating unit 520 connected to the monitoring unit 510 for performing zero crossing detection on the reverse electromotive force signal, acquiring two sampling electromotive forces at equal intervals after the zero crossing time and a third sampling electromotive force after the two sampling electromotive forces when the zero crossing is detected, and determining a resonant frequency of the linear motor according to the acquired three sampling electromotive forces and sampling parameters.
In one example, the monitoring unit 510 may be configured to acquire an inverse electromotive force signal of less than half a resonance period.
In one example, the calculation unit 520 may be configured to perform zero-crossing detection by comparing the value of the acquired back electromotive force with a set threshold value to determine a zero-crossing time of the back electromotive force, or performing polarity judgment on the back electromotive force of the acquired sampling point to determine a zero-crossing time when the back electromotive force changes direction.
In one example, the calculation unit 520 may be configured to acquire two sampled electromotive force signals equally spaced after the zero crossing time and a third sampled electromotive force signal after the two sampled electromotive force signals by determining the zero crossing time according to a later sampling point of two sampling points where the polarity of the inverted electromotive force signal changes, where the two sampling points have a sampling point interval m between them, where m is a positive integer, setting a sampling ordinal N, and acquiring the inverted electromotive force of the nth, 2n×m, (2n+1) m sampling points after the zero crossing time as the three sampled electromotive forces, where N is a positive integer.
In one example, the two equally spaced sampled electromotive forces include a preceding first sampled electromotive force and a following second sampled electromotive force, and the calculation unit 520 may be configured to determine the resonant frequency of the linear motor in such a manner that the magnitude of the back electromotive force of the correction sampling point is calculated from the magnitudes of the second and third sampled electromotive forces, and the resonant frequency of the linear motor is determined based on the magnitude of the first sampled electromotive force, the magnitude of the back electromotive force of the correction sampling point, and the sampling parameter.
In one example, the computing unit 520 may be further configured to determine the correction factor according to magnitudes of back electromotive forces of two sampling points where the polarity is changed, the magnitudes of back electromotive forces of the correction sampling points being associated with the correction factor.
In one example, the calculation unit 520 may be configured to determine a resonant frequency of the linear motor in a manner that a ratio r of the back electromotive force of the correction point and the magnitude of the first sampled electromotive force is determined, and determine the resonant frequency of the linear motor based on at least the ratio r and a sampling parameter, wherein the resonant frequency is positively correlated with the ratio r and negatively correlated with a time interval of the second sampled electromotive force from the zero crossing time.
The specific functions and operations of the respective units and modules in the above-described drive control apparatus 500 have been described in detail in the drive control method described above with reference to fig. 1 to 5, and thus are only briefly described herein, and unnecessary repetitive descriptions are omitted.
The linear motor control system is described below with reference to fig. 8, and as illustrated in fig. 8, the linear motor control system may include at least a detection device 620, and a driving unit 630.
The detecting device 620 is coupled to the linear motor 610, and is used for sensing the back electromotive force of the linear motor and tracking to obtain the resonant frequency of the motor, and is specifically described with reference to fig. 1-7 and related description, which are not repeated herein. The driving unit 630 may drive the linear motor according to the resonance frequency detected by tracking, and the driving circuit may use an H-bridge circuit. Although not shown, the control system may further include a driving generating circuit that may provide a driving signal (e.g., a sinusoidal signal, a square wave signal, etc.) to the driving unit 630 according to the resonance frequency obtained by tracking, thereby controlling the motor to vibrate in an optimal energy efficiency ratio mode, improving an optimal effect of the tactile vibration feeling provided to the user.
In an embodiment, although not shown, the control system may further include a trace enable signal detection unit that may transmit a signal to the drive generation circuit to drive the linear motor by adding a super-drive waveform of several periods before the start of the drive waveform in response to receiving the trace enable signal of the resonant frequency in the linear motor drive, transmit a signal to the drive generation circuit to stop providing the drive waveform to the drive unit in response to receiving the trace enable signal of the resonant frequency after the end of the linear motor drive, and transmit a signal to the detection device to perform a trace operation of the resonant frequency in response to receiving the trace enable signal of the resonant frequency.
The basic principles of the present application have been described above in connection with specific embodiments, but it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are merely examples and not intended to be limiting, and these advantages, benefits, effects, etc. are not to be construed as necessarily possessed by the various embodiments of the application. Furthermore, the specific details disclosed herein are for purposes of illustration and understanding only, and are not intended to be limiting, as the application is not necessarily limited to practice with the above described specific details.
The block diagrams of the devices, apparatuses, devices, systems referred to in the present application are only illustrative examples and are not intended to require or imply that the connections, arrangements, configurations must be made in the manner shown in the block diagrams. As will be appreciated by one of skill in the art, the devices, apparatuses, devices, systems may be connected, arranged, configured in any manner. Words such as "including," "comprising," "having," and the like are words of openness and mean "including but not limited to," and are used interchangeably therewith. The terms "or" and "as used herein refer to and are used interchangeably with the term" and/or "unless the context clearly indicates otherwise. The term "such as" as used herein refers to, and is used interchangeably with, the phrase "such as, but not limited to.
It is also noted that in the apparatus, devices and methods of the present application, the components or steps may be disassembled and/or assembled. Such decomposition and/or recombination should be considered as equivalent aspects of the present application.
The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit embodiments of the application to the form disclosed herein. Although a number of example aspects and embodiments have been discussed above, a person of ordinary skill in the art will recognize certain variations, modifications, alterations, additions, and subcombinations thereof.
Claims (10)
1. A method of tracking a resonant frequency of a linear motor, comprising:
controlling the linear motor to enter a high-resistance state, and acquiring a reverse electromotive force signal with a preset time length, wherein the preset time length is less than a half resonance period of the linear motor;
Zero-crossing detection is carried out on the reverse electromotive force signal;
When a zero crossing is detected, acquiring a first sampling electromotive force corresponding to a first sampling point, a second sampling electromotive force corresponding to a second sampling point and a third sampling electromotive force corresponding to a third sampling point after the second sampling point in the back electromotive force signal of the preset time after the zero crossing time, wherein the interval between the first sampling point and the zero crossing time is equal to the interval between the second sampling point and the first sampling point, and
And determining the resonant frequency of the linear motor according to the obtained amplitude values of the three sampling electromotive forces and the sampling parameters.
2. The method of claim 1, wherein prior to controlling the motor to enter a high resistance state, further comprising:
in response to receiving a tracking enable signal of a resonant frequency before driving the linear motor, a super-drive waveform of a plurality of periods is added before the drive waveform starts to drive the linear motor.
3. The method of claim 1 or 2, further comprising resuming driving after a predetermined time after the zero crossing, the predetermined time being less than one quarter of the resonant period.
4. The method of claim 1 or 2, wherein zero crossing the back electromotive force signal comprises:
Comparing the amplitude of the obtained back electromotive force of the sampling point with a set threshold value to determine the zero crossing time of the back electromotive force, or
And judging the polarity of the obtained reverse electromotive force of the sampling point, and determining the zero crossing moment when the polarity of the reverse electromotive force changes.
5. The method of claim 4, wherein obtaining a first sampled electromotive force corresponding to a first sampling point, a second sampled electromotive force corresponding to a second sampling point, and a third sampled electromotive force corresponding to a third sampling point after the second sampling point in the back electromotive force signal of the predetermined duration after the zero crossing time comprises:
determining zero crossing time according to the later sampling point in the two sampling points with the polarity changed, wherein a sampling point interval m is arranged between the two sampling points, and m is a positive integer;
Setting a sampling ordinal number N, and obtaining the back electromotive forces of the Nth, 2Nth and (2N+1) th sampling points after the zero crossing moment as the first, second and third sampling electromotive forces respectively, wherein N is a positive integer.
6. The method of claim 1 or 5, wherein determining the resonant frequency of the linear motor from the acquired three sampled electromotive forces and the sampling parameter comprises:
Calculating the amplitude of the back electromotive force of the corrected sampling point based on the amplitudes of the second and third sampled electromotive forces, and
And determining the resonant frequency of the linear motor based on the amplitude of the first sampled electromotive force, the amplitude of the back electromotive force of the corrected sampling point and the sampling parameter.
7. The method of claim 6, wherein the method further comprises:
And determining a correction factor according to the amplitude of the back electromotive force of the two sampling points with the polarity changed, wherein the amplitude of the back electromotive force of the correction sampling points is related to the correction factor.
8. The method of claim 6, wherein determining a resonant frequency of a linear motor based on the magnitude of the first sampled electromotive force, the magnitude of the counter electromotive force of the corrected sampling point, and a sampling parameter comprises:
determining a ratio r of the magnitude of the back electromotive force of the corrected sampling point to the magnitude of the first sampled electromotive force, and
A resonant frequency of the linear motor is determined based at least on the ratio r and a sampling parameter, wherein the resonant frequency is positively correlated with the ratio r and negatively correlated with a time interval of the second sampled electromotive force from the zero crossing instant.
9. A tracking detection device for a resonant frequency of a linear motor, comprising:
A monitoring unit for acquiring a back electromotive force signal for a predetermined period of time, which is less than half a resonance period of the linear motor, after controlling the linear motor to enter a high resistance state, and
And the calculation unit is used for carrying out zero crossing detection on the reverse electromotive force signal, acquiring a first sampling electromotive force corresponding to a first sampling point, a second sampling electromotive force corresponding to a second sampling point and a third sampling electromotive force corresponding to a third sampling point after the second sampling point in the reverse electromotive force signal with the preset duration after the zero crossing moment when the zero crossing is detected, and determining the resonant frequency of the linear motor according to the acquired amplitude values and sampling parameters of the three sampling electromotive forces, wherein the interval between the first sampling point and the zero crossing moment is equal to the interval between the second sampling point and the first sampling point.
10. A linear motor drive control system comprising:
the tracking detection apparatus of claim 9, and
And a drive circuit that drives the linear motor according to the resonance frequency.
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| US9121753B2 (en) * | 2013-02-06 | 2015-09-01 | Analog Devices Global | Control techniques for motor driven systems utilizing back-EMF measurement techniques |
| CN108183654B (en) * | 2018-01-15 | 2020-11-17 | 上海艾为电子技术股份有限公司 | Method and device for calibrating resonant frequency of linear vibration device |
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