A tracking method and detection device for the resonance frequency of a linear motor

Abstract

A linear motor resonant frequency tracking method and device are disclosed. According to one embodiment, a linear motor resonant frequency tracking method may include: controlling the linear motor to enter a high impedance state and obtaining a back electromotive force signal; performing zero-crossing detection on the back electromotive force signal; when zero-crossing is detected, obtaining two sampled electromotive forces at equal intervals after the zero-crossing moment and a third sampled electromotive force after the two sampled electromotive forces; and determining the resonant frequency of the linear motor based on the three sampled electromotive forces and sampling parameters obtained. The present invention can achieve the acquisition of the true resonant frequency of the linear motor based on a shorter time acquisition signal, thereby providing a reference for controlling the motor.

Description

Technical Field

[0001] This application relates to the field of electronic equipment technology, and more specifically, to a method and apparatus for tracking and detecting the resonant frequency of a linear motor. Background Technology

[0002] Haptic feedback technology is generally achieved through motor vibration. A linear motor mainly consists of components such as a spring, a magnetic mass, and coils. The spring suspends the mass inside the motor. The mass can move up and down in an applied, changing magnetic field, and this vibration is perceived by people, thus producing a tactile effect.

[0003] During operation, to efficiently generate tactile effects, an ideal spring-loaded mass is driven at its inherent resonant frequency. For example, the closer the frequency of the driving waveform is to the motor's true resonant frequency, the shorter the time required for the motor to reach resonance, and the more pronounced the vibration effect. Conversely, during braking, the closer the frequency of the driving waveform is to the motor's true resonant frequency, the faster the motor can brake. Therefore, obtaining an accurate motor resonant frequency is a crucial prerequisite for achieving vibration control.

[0004] When the actual resonant frequency of a smart device deviates from its factory-designed resonant frequency due to factors such as the usage environment and component aging, the vibration of the motor will change. Existing methods for detecting the resonant frequency of linear motors are generally only used in a few scenarios such as power-on, are slow, and are prone to causing vibration spikes, making it difficult to truly track the resonant frequency of the linear motor in real time. Summary of the Invention

[0005] To address the aforementioned technical problems in the prior art, this application is proposed. Embodiments of this application provide a method, detection device, and control system for tracking and detecting the resonant frequency of a linear motor. This system can quickly determine the resonant frequency, thereby facilitating frequency calibration of the drive waveform as needed to achieve optimal vibration control.

[0006] According to one aspect of this application, a method for tracking the resonant frequency of a linear motor is provided, comprising: controlling the linear motor to enter a high-resistance state and acquiring a back electromotive force (EMF) signal; performing zero-crossing detection on the back EMF signal; when a zero-crossing is detected, acquiring two equally spaced sampled EMFs after the zero-crossing moment and a third sampled EMF after the two sampled EMFs; and determining the resonant frequency of the linear motor based on the acquired three sampled EMFs and sampling parameters.

[0007] In some embodiments, before controlling the motor to enter a high-resistance state, the method further includes: in response to receiving a tracking enable signal of the resonant frequency before driving the linear motor, adding a super-drive waveform of several cycles to drive the linear motor before the start of the drive waveform.

[0008] In some embodiments, the time for obtaining the reverse electromotive force is less than half a resonant period.

[0009] In some embodiments, zero-crossing detection of the back electromotive force signal includes: comparing the amplitude of the back electromotive force at the acquired sampling point with a set threshold to determine the zero-crossing time of the back electromotive force; or determining the polarity of the back electromotive force at the acquired sampling point to determine the zero-crossing time when the polarity of the back electromotive force changes direction.

[0010] In some embodiments, obtaining two equally spaced sampled electromotive forces after the zero-crossing time and a third sampled electromotive force after the two sampled electromotive forces includes: determining the zero-crossing time based on the later sampled point among the two sampled points where the polarity changes direction, wherein there is a sample point interval m between the two sampled points, where m is a positive integer; setting a sampling sequence number N, and obtaining the reverse electromotive forces of the N*m, 2N*m, and (2N+1)*m sampled points after the zero-crossing time as the three sampled electromotive forces, where N is a positive integer.

[0011] In some embodiments, the two equally spaced sampling electromotive forces include a first sampling electromotive force and a second sampling electromotive force, and determining the resonant frequency of the linear motor based on the acquired three sampling electromotive force signals and sampling parameters includes: calculating the amplitude of the reverse electromotive force at the corrected sampling point based on the amplitudes of the second sampling electromotive force and the third sampling electromotive force; and determining the resonant frequency of the linear motor based on the amplitude of the first sampling electromotive force, the amplitude of the reverse electromotive force at the corrected sampling point, and the sampling parameters.

[0012] In some embodiments, the method further includes: determining the correction factor based on the amplitude of the back electromotive force at the two sampling points where the polarity changes direction, wherein the amplitude of the back electromotive force at the correction sampling point is associated with the correction factor.

[0013] In some embodiments, determining the resonant frequency of the linear motor based on the first sampled electromotive force, the back electromotive force at the corrected sampling point, and the sampling parameters includes: determining a ratio r between the amplitude of the back electromotive force at the corrected point and the amplitude of the first sampled electromotive force; and determining the resonant frequency of the linear motor based at least on the ratio r and the sampling parameters, wherein the resonant frequency is positively correlated with the ratio r and negatively correlated with the time interval between the second sampled electromotive force and the zero-crossing moment.

[0014] Another aspect of this application provides a tracking and detection device for the resonant frequency of a linear motor, comprising: a monitoring unit for acquiring a back electromotive force signal after controlling the linear motor to enter a high-resistance state; and a calculation unit for performing zero-crossing detection on the back electromotive force signal, acquiring two equally spaced sampled electromotive forces after the zero-crossing moment and a third sampled electromotive force after the two sampled electromotive forces when a zero-crossing is detected, and determining the resonant frequency of the linear motor based on the acquired three sampled electromotive forces and sampling parameters.

[0015] Another aspect of this application provides a linear motor drive control system, including: the aforementioned linear motor tracking and detection device; and a drive circuit that can drive the linear motor according to the determined resonant frequency.

[0016] Compared with the prior art, the linear motor resonant frequency tracking and detection method and apparatus of this application can be applied to any driving mode. By quickly and accurately determining the true resonant frequency of the motor in a short time, it can not only be directly applied to detection or tracking scenarios, but also has almost no impact on the waveform to be played in other scenarios because it does not require several resonant cycles to detect the resonant frequency. It can calculate and output the resonant frequency in real time, which facilitates frequency amplitude correction of the driving waveform as needed, improves the vibration control effect of the motor, and thus significantly improves the user experience. Attached Figure Description

[0017] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0018] Figure 1 A flowchart is shown below illustrating a linear motor resonant frequency tracking method according to an embodiment of this application;

[0019] Figure 2 A schematic diagram illustrating a method for controlling a motor to enter a high-resistance state according to an embodiment of this application is shown.

[0020] Figure 3 A schematic diagram illustrating zero-crossing detection and acquisition of the sampled electromotive force signal after the zero-crossing moment according to an embodiment of this application is shown.

[0021] Figure 4 A flowchart illustrating a method for determining the resonant frequency of a linear motor according to an embodiment of this application is shown.

[0022] Figure 5A flowchart illustrating a method for calculating the resonant frequency of a linear motor according to an embodiment of this application is shown.

[0023] Figure 6 A flowchart of a linear motor drive control method according to an embodiment of this application is shown;

[0024] Figure 7 A block diagram of a linear motor resonant frequency tracking and detection device according to an embodiment of this application is shown.

[0025] Figure 8 The figure shows a structural block diagram of a linear motor control system according to an embodiment of the present application. Detailed Implementation

[0026] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely a part of the embodiments of this application, and not all of them. Furthermore, implementing any example of an embodiment of this application does not necessarily require simultaneously achieving all the above advantages. It should be understood that this application should not be limited to the specific details of these exemplary embodiments. Rather, embodiments of this application can be implemented without these specific details or by employing other alternatives, without departing from the spirit and principles of this application as defined in the claims.

[0027] This embodiment provides a method for tracking the resonant frequency of a linear motor, primarily used for detecting the resonant frequency of a linear motor. (Reference) Figure 1 It shows a flowchart of a linear motor resonant frequency tracking and detection method provided in an embodiment of this application, such as... Figure 1 As shown, the method 100 may include the following steps:

[0028] Step S110: Control the linear motor to enter a high-resistance state and acquire a back electromotive force signal.

[0029] The back electromotive force (EMF) is induced by the movement of the permanent magnet (mass) of the motor relative to the wound coil. Since the mass vibrates at its natural resonant frequency, the induced back EMF signal will also have this resonant frequency. In one embodiment, the back EMF can be obtained by sampling the EMF generated at the ends of the linear motor due to its motion. Under normal motor drive vibration, the back EMF is always present, but it is easily submerged in a large drive voltage and difficult to detect. Therefore, in one embodiment, the motor can be first brought into a high-resistance state, for example, by disconnecting the drive. In the high-resistance state, without a drive signal, the back EMF can be directly detected without the need for complex calculations to separate it from the monitoring signal.

[0030] In one embodiment, the linear motor can implement the resonant frequency tracking method of the present invention after receiving a tracking enable signal. The enable signal can be triggered by the user or according to the driving mode. For example, a corresponding tracking enable signal can be generated according to the current driving state. After receiving the enable signal, the control system generates a control signal to control the output of the driving chip so that the motor enters a high-impedance state.

[0031] Figure 2 A schematic diagram illustrating a method for controlling a motor to enter a high-resistance state according to an embodiment of this application is shown. Figure 2 As shown, the resonant frequency tracking of the present invention can be implemented at any driving time period of the linear motor, that is, the motor can be controlled to enter a high-resistance state according to the driving state such as before driving, during driving, or after driving.

[0032] refer to Figure 2 First, the drive state when the tracking enable signal is received can be determined. For example, if the tracking enable signal of the resonant frequency is received before the linear motor is driven, i.e., if the frequency tracking enable signal 1 is triggered, and the drive waveform has not yet been played, several cycles of overdrive waveform can be added before the drive waveform to be played to drive the linear motor. Then, in response to the tracking enable signal 1, the drive is disconnected to enter a high-impedance state. After the tracking is completed, the drive waveform can be played to drive the motor to vibrate. If the enable signal is received during the vibration process when the motor enters the vibration state, for example, if the frequency tracking enable signal 2 is triggered, and the playback is in progress, the current drive is disconnected for a predetermined time, resonant frequency tracking is performed, and the vibration waveform is resumed after the tracking is completed. If the enable signal is received after the current drive has ended, for example, if the frequency tracking enable signal 3 is triggered, the resonant frequency can be directly tracked for the residual vibration, and the resonant frequency is output after the tracking is completed.

[0033] It should be noted that, although Figure 2 Enable signal 1, enable signal 2, and enable signal 3 are distinguished by numbers, but it is understood that these enable signals can also use the same trigger, and they are still within the protection scope of this application.

[0034] The resonant frequency tracking method in this embodiment can be implemented at any position during the playback of the vibration drive waveform by the linear motor driver chip. For example, tracking can be achieved in any driving mode, before the start of the drive waveform, during a brief disconnection of the drive at any position in a long vibration drive, or at the end of the waveform playback. Without affecting the vibration, the resonant frequency is tracked and updated in real time, allowing the drive frequency to be adjusted according to actual needs, ensuring stable motor vibration and achieving the highest energy efficiency ratio.

[0035] In one embodiment, the two pins of the motor can be grounded to discharge the signal, causing the linear motor to enter a high-resistance state. Specifically, the two pins of the motor can be grounded before acquiring the back electromotive force signal. The brief contact discharge makes the voltage signal detected at the two ends of the motor input pins afterward close to the actual back electromotive force signal.

[0036] If the acquisition time of the back electromotive force signal is too long, vibration spikes and dents will occur. For example, regarding the tracking enable signal 2 mentioned above, if the drive is disconnected for a long time during normal driving, the motor amplitude will be unstable, which will adversely affect the tactile effect. Therefore, unlike some existing technologies, in one embodiment of the present invention, only a very short predetermined duration of back electromotive force signal can be acquired. Then, the operation of starting drive, resuming drive, or changing the drive signal to perform braking operation can be performed according to the actual situation. The predetermined duration of the acquired back electromotive force signal can be less than half a resonant period of the linear motor. This resonant period can be calculated by tracking the resonant frequency of the motor during vibration. This can reduce the adverse effects on the user's tactile effect and can advantageously and quickly respond to subsequent control operations.

[0037] In one embodiment, after acquiring the back electromotive force signal, the acquired electromotive force signal can be processed, for example, by first performing low-pass filtering and then by smoothing preprocessing to obtain a glitch-free signal of interest.

[0038] return Figure 1 After acquiring the reverse electromotive force signal, step S120 can be performed to perform zero-crossing detection on the acquired reverse electromotive force signal.

[0039] For example, the acquired back electromotive force signal can be sampled first, and zero-crossing detection can be performed based on the sampled data. The sampling frequency for the back electromotive force can be in the range of 12-96 kHz, such as a sampling frequency of 24-48 kHz.

[0040] In one embodiment, the amplitude of the back electromotive force (EMF) signal at the acquired sampling point can be compared with a set threshold to determine whether the acquired back EMF signal has crossed zero and the time of zero crossing. For example, the amplitude of each back EMF in the sampling sequence can be compared with a reference threshold. If the value of the back EMF is detected to be less than the set reference threshold, it indicates that the back EMF has crossed zero, and the time of zero crossing corresponding to the zero crossing state is determined.

[0041] In another embodiment, the polarity of the back electromotive force at the acquired sampling point can be determined to identify the zero-crossing moment when the polarity of the back electromotive force changes direction.

[0042] See Figure 3The diagram illustrates a zero-crossing detection method according to an embodiment of this application. For example, the polarity of the sampled back electromotive force can be determined. If the polarities of the back electromotive forces at two adjacent or separated sampling points are the same, it can be considered that no zero-crossing has occurred. Conversely, if the back electromotive forces at two adjacent or separated sampling points change direction, for example, when the back electromotive force changes from positive to negative or from negative to positive, it can be determined that a zero-crossing has occurred.

[0043] like Figure 3 As shown, the polarity of two adjacent or separated sampling points (t_L, s_L) and (t_R, s_R) can be detected. Here, t_L and t_R represent the times of the two sampling points, respectively, and the two sampling points are separated by m sampling points (m is a positive integer, such as 1, 2, 3, etc.). s_L and s_R represent the amplitudes of the back electromotive force (EMF) at the two sampling points, respectively. If the polarities of s_L and s_R are detected to be opposite, it can be determined that the back EMF has crossed zero, and the time corresponding to the reversed back EMF sampling point can be determined as the zero-crossing moment. For example, t_R can be determined as the zero-crossing moment. Simultaneously, the amplitudes of these two sampling points and the sampling point interval m can be recorded. It can be seen that t_L and t_R are not true zero-crossing moments; they can also be called quasi-zero-crossing points. Therefore, in one embodiment, the zero-crossing time can be corrected, which will be described in detail later.

[0044] In one embodiment, the sampling operation and zero-crossing detection of the back electromotive force signal can be performed simultaneously. A timer can be started after the zero-crossing moment is detected, and drive can be resumed after a predetermined time following the zero-crossing moment, wherein the predetermined time can be less than one-quarter of the resonant period. It can be seen that the resonant frequency tracking method of this embodiment only requires the acquired back electromotive force signal to have one zero-crossing state. Compared with the prior art method that determines the resonant frequency based on two or more zero-crossing points, this invention can greatly reduce the duration of drive disconnection, thereby minimizing the impact on motor vibration.

[0045] After zero-crossing detection, the tracking method of this application can proceed to step S130, where, upon detecting a zero-crossing, two equally spaced sampled electromotive forces after the zero-crossing moment and a third sampled electromotive force after the two sampled electromotive forces are acquired.

[0046] When a zero-crossing is detected, the zero-crossing moment can be determined first, and two equally spaced sampling points (hereinafter referred to as the first and second sampling electromotive forces, respectively) and a third sampling electromotive force following the two sampling points can be selected as the starting point. The zero-crossing moment can be determined using the methods described above. For example, when comparing the amplitude of the acquired back electromotive force signal with a set threshold, the time corresponding to the sampling point that is less than the set threshold can be determined as the zero-crossing moment; when determining the polarity of the back electromotive forces of adjacent or spaced sampling points, the time corresponding to one of the two sampling points where the polarity changes can be selected as the zero-crossing moment.

[0047] In one embodiment, the zero-crossing time can be determined based on the later sampling point among the two sampling points where the polarity change occurs. The two sampling points have a sampling interval m, that is, the time interval between the two sampling points is m / fs, where m is a positive integer and fs is the sampling frequency. At the same time, the sampling sequence number N is set, and the reverse electromotive force of the N*m, 2N*m, and (2N+1)*m sampling points after the zero-crossing time is obtained as the three sampling electromotive forces for subsequently determining the resonant frequency, where N is a positive integer.

[0048] See still Figure 3 For example, when it is determined that s_L and s_R, which are sampled at intervals of m, have opposite polarities, t_R can be determined as the zero-crossing time. Starting from this time, two equally spaced sampled electromotive force signals and a third sampled point after these two points are selected. Preferably, this interval is an integer multiple of the sample interval m to facilitate the subsequent calculation of the resonant frequency. That is, the first sampled electromotive force signal can be expressed as (t_N, s_N) = (t_L, s_R) / (t_R) / (s ... N*m ,s N*m The second sampled electromotive force signal can be expressed as (t_2N, s_2N) = (t 2N*m ,s 2N*m The third sampling point and the second sampling point have a set time interval. Preferably, the third sampling point and the second sampling point are also spaced m times apart, that is, the electromotive force signal of the third sampling point can be expressed as (t_2N+1, s_2N+1)=(t (2N+1)*m ,s (2N+1)*m ), where m and N are both positive integers, such as 1, 2, 3, 4, 5, etc. N*m, 2N*m, and (2N+1)*m represent the sampling sequence numbers of the first, second, and third sampling points after t_R. When the sampling frequency fs is predetermined, the time intervals between these three sampling points and t_R are N*m / fs, 2N*m / fs, and (2N+1)*m / fs, respectively.

[0049] In a specific example, for instance, the sampling interval m can be set to 1, and the sampling sequence number N can be set to 5. Accordingly, the three selected sampling points are (t_5, s_5), (t_10, s_10), and (t_11, s_11), that is, the second and third sampling points are adjacent sampling electromotive force signals.

[0050] return Figure 1 After acquiring three sampled electromotive force (EMF) signals, the method proceeds to step S140, where the resonant frequency of the linear motor is determined based on the acquired three sampled EMF signals and sampling parameters. After the zero-crossing point, the motor can be considered to undergo damped oscillation; therefore, the true resonant frequency of the linear motor can be determined based on the relationship between the amplitudes of the three sampled EMF signals, the relevant sampling parameters, and the damping coefficient. The sampling parameters may include time parameters and / or frequency parameters. The time parameter may be the time interval between the three sampled EMF signals and the zero-crossing point, and the frequency parameter may be the sampling frequency, etc.

[0051] As mentioned earlier, since the determined zero-crossing time t_R is not the actual zero-crossing point, in order to more accurately calculate the resonant frequency of the linear motor, a zero-crossing correction can be performed, and the resonant frequency of the motor can be determined based on the electromotive force signal of the corrected sampling point.

[0052] Figure 4 A flowchart illustrating a method for determining the resonant frequency of a linear motor according to an embodiment of this application is shown. Figure 4 As shown, methods for determining the resonant frequency of a linear motor through correction include:

[0053] In step S210, the amplitude of the reverse electromotive force at the corrected sampling point is calculated based on the amplitudes of the second and third sampled electromotive forces.

[0054] In one embodiment, a correction sampling point may be set between a second sampling point (e.g., the 2N*m sampling point) and a third sampling point (e.g., the (2N+1)*m sampling point), wherein the interval (m) between the second and third sampling points is the same as the interval (m) between the two sampling points (t_L, t_R) that are determined to have reversed.

[0055] In order to determine the back electromotive force of the corrected sampling point, in one embodiment, the correction factor can be determined based on the back electromotive force of the two sampling points where the polarity changes, and the magnitude of the back electromotive force of the corrected sampling point is associated with the correction factor.

[0056] See Figure 3 When determining the zero-crossing time based on the polarity of sampling points (t_L, s_L) and (t_R, s_R), the correction factor c can be determined as follows:

[0057] c = |s_R| / (|s_L|+|s_R|).

[0058] Based on this, the amplitude of the back electromotive force at the corrected sampling point can be estimated. For example, the back electromotive force s' at the corrected sampling point can be calculated as follows: 2N :

[0059] s' 2N =(1-c)*s 2N +c*s 2N+1 , where s in the formula 2N s 2N+1 Corresponding to Figure 3 Given s_2N and s_(2N+1) shown, calculate s'. 2N This can be viewed as a correction to the reverse electromotive force at the 2N*m sampling point after time t_R.

[0060] In step S220, the resonant frequency of the linear motor is determined based on the amplitude of the first sampled electromotive force, the amplitude of the reverse electromotive force at the corrected sampling point, and the sampling parameters.

[0061] Given the estimated back electromotive force at the correction point, the resonant frequency of the linear motor can be determined based on the relationship between the amplitudes of the back electromotive force at the first sampling point (e.g., the N*mth sampling point) and the back electromotive force at the correction sampling point, as well as sampling parameters such as sampling frequency and sampling interval.

[0062] Figure 5 A flowchart illustrating a method for calculating the resonant frequency of a linear motor according to an embodiment of this application is shown, as follows: Figure 5 As shown, the calculation method may include the following steps:

[0063] Step S310: Determine the ratio r between the amplitude of the reverse electromotive force at the correction point and the amplitude of the first sampled electromotive force.

[0064] This ratio r can be considered as the zero-crossing point t. ZC The ratio of the back electromotive force at two equally spaced time points is referenced. Figure 3 It can be represented as: Where s N Corresponding to Figure 3 The amplitude s_N of the reverse electromotive force at the N*m sampling point is shown in the figure.

[0065] Step S320: Determine the resonant frequency of the linear motor based at least on the ratio r and the sampling parameters. The sampling parameters may include time parameters and / or frequency parameters. The time parameter may be the time interval between the three sampled electromotive forces and the zero-crossing moment, and the frequency parameter may be the sampling frequency, etc. For example, the resonant frequency is positively correlated with the ratio r and negatively correlated with the time interval between the second sampled electromotive force and the zero-crossing moment.

[0066] In one embodiment, the resonant frequency of the linear motor can be determined by the following calculation:

[0067] f = p*r + q, where f is the resonant frequency of the motor, p is a value related to the sampling parameters and motor damping, for example, it can be expressed as p = k / (Δt*D) = k*fs / (2N*m*D), that is, f is positively correlated with the ratio r, negatively correlated with the time interval Δt between the second sampling electromotive force and the zero-crossing time t_R, and specifically negatively correlated with the sampling interval m and the sampling sequence number N, where k is a constant that can be adjusted according to actual needs, D is the motor damping, and q is the correction value of p, the correction relationship can be determined in advance through experiments.

[0068] Figure 6 A flowchart of a linear motor drive control method according to an embodiment of this application is shown, which can, for example, respond to... Figure 2 The tracking enable signal 2 is used for control, such as Figure 6 As shown, it includes:

[0069] In step S410, the drive is disconnected. For example, the application of drive voltage or drive signal to the linear motor is stopped.

[0070] In step S420, the motor input pins are briefly grounded and discharged to enter a high-resistance state, so that the voltage signal across the motor terminals measured subsequently can be close to the reverse electromotive force.

[0071] In step S430, the back electromotive force signal generated by the motor under high resistance is acquired, and signal processing such as filtering and smoothing can be performed. In one embodiment of this application, the acquisition time can be less than the half-resonance period of the motor. By reducing the time of disconnecting the drive, the adverse effects on the user's tactile experience can be reduced.

[0072] In step S440, the obtained reverse electromotive force is zero-crossing detected, and the resonant frequency of the motor is calculated.

[0073] For example, a reference can be used. Figure 1-5 The methods described will not be repeated here.

[0074] In step S450, the drive is restored at the point where the waveform is broken. The drive waveform can be corrected according to the determined resonant frequency to obtain a drive waveform with the actual resonant frequency. The drive waveform with the actual resonant frequency is used to restore the drive of the linear motor at the point of break, so that the motor has a better driving effect.

[0075] It is understood that although only tracking enable signal 2 has been described above, the control process is also applicable to tracking enable signal 1 or tracking enable signal 3. For example, in response to tracking enable signal 3, an embodiment of this application can use a modified drive waveform with the actual resonant frequency to drive the motor to vibrate, thereby shortening the time required for motor braking and reducing the drive power consumption of the motor.

[0076] The motor resonant frequency tracking method provided in this invention can accurately obtain the actual resonant frequency of the motor by detecting the back electromotive force in a short time. It can be directly applied to detection or tracking scenarios. Furthermore, since it does not require several resonant cycles to detect the resonant frequency, it has almost no impact on the waveform to be played in other scenarios, thereby improving the overall vibration effect of the motor.

[0077] This invention also provides a linear motor resonant frequency tracking and detection device. For example... Figure 7 As shown, the linear motor control device 500 according to an embodiment of this application may include: a monitoring unit 510, which is connected to the motor to acquire a back electromotive force signal after controlling the linear motor to enter a high-resistance state; and a calculation unit 520, which is connected to the monitoring unit 510 to perform zero-crossing detection on the back electromotive force signal, and when a zero-crossing is detected, acquire two equally spaced sampled electromotive forces after the zero-crossing moment and a third sampled electromotive force after the two sampled electromotive forces, and determine the resonant frequency of the linear motor based on the acquired three sampled electromotive forces and the sampling parameters.

[0078] In one example, the monitoring unit 510 may be configured to acquire a back electromotive force signal of less than half a resonant period.

[0079] In one example, the calculation unit 520 may be configured to perform zero-crossing detection in the following manner: comparing the acquired back electromotive force value with a set threshold to determine the zero-crossing time of the back electromotive force; or determining the polarity of the acquired back electromotive force at the sampling point to determine the zero-crossing time when the back electromotive force changes direction.

[0080] In one example, the calculation unit 520 may be configured to acquire two equally spaced sampled electromotive force signals after the zero-crossing time and a third sampled electromotive force signal following the two sampled electromotive force signals in the following manner: the zero-crossing time is determined based on the later sampled point among the two sampled points where the polarity of the reverse electromotive force signal changes direction, wherein there is a sample point interval m between the two sampled points, where m is a positive integer; a sampling sequence number N is set, and the reverse electromotive force of the N*m, 2N*m, and (2N+1)*m sampled points after the zero-crossing time is acquired as the three sampled electromotive forces, where N is a positive integer.

[0081] In one example, the two equally spaced sampled electromotive forces include a first sampled electromotive force and a second sampled electromotive force, and the calculation unit 520 is configured to determine the resonant frequency of the linear motor in such a way as: calculating the amplitude of the reverse electromotive force at the corrected sampling point based on the amplitudes of the second and third sampled electromotive forces; and determining the resonant frequency of the linear motor based on the amplitude of the first sampled electromotive force, the amplitude of the reverse electromotive force at the corrected sampling point, and the sampling parameters.

[0082] In one example, the calculation unit 520 may also be configured to determine the correction factor based on the magnitude of the back electromotive force at the two sampling points where the polarity changes, the magnitude of the back electromotive force at the correction sampling points being associated with the correction factor.

[0083] In one example, the calculation unit 520 may be configured to determine the resonant frequency of the linear motor by: determining a ratio r of the amplitude of the back electromotive force at the correction point and the amplitude of the first sampled electromotive force; and determining the resonant frequency of the linear motor based at least on the ratio r and the sampling parameters, wherein the resonant frequency is positively correlated with the ratio r and negatively correlated with the time interval between the second sampled electromotive force and the zero-crossing moment.

[0084] The specific functions and operations of each unit and module in the aforementioned drive control device 500 have been described above. Figure 1-5 The drive control method is described in detail here, so only a brief introduction is given here, and unnecessary repetition is omitted.

[0085] The following reference Figure 8 To describe a linear motor control system, such as Figure 8 The linear motor control system may include at least a detection device 620 and a drive unit 630.

[0086] The detection device 620 is coupled to the linear motor 610 and is used to sense the back electromotive force of the linear motor and track and obtain the resonant frequency of the motor. See details [link to relevant documentation]. Figure 1-7The relevant descriptions are omitted here. The drive unit 630 can drive the linear motor according to the tracked and detected resonant frequency, and the drive circuit can adopt an H-bridge or other circuits. Although not shown, the control system may also include a drive generation circuit, which can provide a drive signal (e.g., a sine wave signal, a square wave signal, etc.) to the drive unit 630 according to the tracked and obtained resonant frequency, thereby controlling the motor to vibrate in the optimal energy efficiency mode, improving the best effect of tactile vibration provided to the user.

[0087] In one embodiment, although not shown, the control system may further include a tracking enable signal detection unit, which, in response to receiving a tracking enable signal of the resonant frequency before the linear motor is driven, sends a signal to the drive generation circuit to add a superdrive waveform of several cycles before the start of the drive waveform to drive the linear motor; in response to receiving a tracking enable signal of the resonant frequency during the linear motor drive, sends a signal to the drive generation circuit to stop providing the drive waveform to the drive unit; and in response to receiving a tracking enable signal of the resonant frequency after the linear motor drive is completed, sends a signal to the detection device to perform a resonant frequency tracking operation.

[0088] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0089] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0090] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0091] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0092] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for tracking the resonant frequency of a linear motor, comprising: Controlling the linear motor to enter a high-impedance state and obtaining a back electromotive force signal of a predetermined duration, wherein the predetermined duration is less than a half resonance period of the linear motor; Performing zero-crossing detection on the back electromotive force signal; When a zero crossing is detected, 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 are obtained in the reverse electromotive force signal of the predetermined time length after the zero crossing moment, 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; as well as The resonance frequency of the linear motor is determined according to the amplitudes of the three sampled electromotive forces and the sampled parameters.

2. The method according to claim 1, wherein: Before controlling the motor to enter the high-impedance state, the method further includes: In response to receiving a tracking enable signal of a resonant frequency before the linear motor is driven, an overdrive waveform having several cycles is added before the start of the drive waveform to drive the linear motor.

3. The method according to claim 1 or 2, further comprising: The driving is resumed after a predetermined time after the zero-crossing instant, the predetermined time being less than a quarter of the resonance period.

4. The method according to claim 1 or 2, wherein: The zero-crossing detection of the back electromotive force signal comprises: Compare the amplitude of the back electromotive force at the acquired sampling point with a set threshold value to determine the zero-crossing moment of the back electromotive force; or The polarity of the reverse electromotive force at the acquired sampling point is judged to determine the zero-crossing moment when the polarity of the reverse electromotive force changes direction.

5. The method according to claim 4, wherein: Acquiring 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 time length after the zero-crossing moment includes: Determine the zero-crossing time according to the later sampling point of the two sampling points at which the polarity changes, wherein there is a sampling point interval m between the two sampling points, where m is a positive integer; The sampling sequence number N is set, and the back electromotive force of the N*m, 2N*m, and (2N+1)*m sampling points after the zero-crossing moment is obtained as the first sampling electromotive force, the second sampling electromotive force, and the third sampling electromotive force, respectively, where N is a positive integer.

6. The method according to claim 1 or 5, wherein: Determining the resonant frequency of the linear motor based on the three sampled electromotive forces and sampled parameters includes: Calculating the amplitude of the reverse electromotive force at the modified sampling point according to the amplitudes of the second sampled electromotive force and the third sampled electromotive force; 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 at the correction sampling point, and the sampling parameters.

7. The method according to claim 6, wherein: The method further comprises: The correction factor is determined according to the amplitude of the back electromotive force at two sampling points where the polarity changes, and the amplitude of the back electromotive force at the correction sampling point is associated with the correction factor.

8. The method according to claim 6, wherein: 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 at the modified sampling point, and the sampling parameters includes: Determining a ratio r between the amplitude of the back electromotive force at the correction sampling point and the amplitude of the first sampling electromotive force; and The resonant frequency of the linear motor is determined based at least on the ratio r and the sampling parameters, wherein the resonant frequency is positively correlated with the ratio r, and negatively correlated with the time interval between the second sampled electromotive force and the zero-crossing moment.

9. A tracking and detection device for a linear motor resonant frequency, comprising: A monitoring unit, which is used to obtain a back electromotive force signal of a predetermined time length after controlling the linear motor to enter a high-impedance state, wherein the predetermined time length is less than a half resonance period of the linear motor; as well as A calculation unit is used to perform zero-crossing detection on the back electromotive force signal, and when zero-crossing is detected, obtain a first sampling electromotive force corresponding to a first sampling point in the back electromotive force signal of the predetermined time length after the zero-crossing moment, 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, and determine the resonant frequency of the linear motor according to the amplitudes and sampling parameters of the three obtained 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 device according to claim 9; as well as A driving circuit drives the linear motor according to the resonant frequency.

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