CN116155166A - Detection method and detection device for resonant frequency of linear motor - Google Patents
Detection method and detection device for resonant frequency of linear motor Download PDFInfo
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- CN116155166A CN116155166A CN202111438389.4A CN202111438389A CN116155166A CN 116155166 A CN116155166 A CN 116155166A CN 202111438389 A CN202111438389 A CN 202111438389A CN 116155166 A CN116155166 A CN 116155166A
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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
Abstract
A method and apparatus for detecting a resonant frequency of a linear motor are disclosed. According to an embodiment, a method for detecting a resonant frequency of a linear motor may include: driving the linear motor at a preset resonant frequency; controlling the linear motor to enter a high-resistance state, and acquiring reverse electromotive force signals of a plurality of periods; and determining a resonant frequency of the linear motor according to time points of the plurality of peaks based on the reverse electromotive force signal. The invention can rapidly determine the resonant frequency of the motor, thereby facilitating the frequency calibration of the driving waveform according to the requirement and ensuring the stable vibration quantity.
Description
Technical Field
The present disclosure relates to the field of electronic devices, and more particularly, to a method and apparatus for detecting a resonant frequency of a linear motor.
Background
Linear motors are widely used in haptic feedback implementation technologies with their small size, fast start-up, low power consumption, etc. 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 may undergo a single axis motion in an applied varying magnetic field, such vibration being 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 reasons of use environment, physical impact, element aging and the like, the vibration quantity of the motor is changed. The existing linear motor resonant frequency detection method is low in detection speed and high in signal-to-noise ratio requirement on signals, and because the detected vibration is long, the detection method is generally only applied to fewer scenes such as factory leaving or starting, and the resonant frequency of the linear motor is difficult to truly and synchronously track.
Disclosure of Invention
The present application has been proposed in order to solve the above-mentioned technical problems occurring in the prior art. The embodiment of the application provides a detection method and a detection device 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 control effect of stable and consistent vibration quantity is achieved.
According to an aspect of the present application, there is provided a method of detecting a resonant frequency of a linear motor, including: driving the linear motor at a preset resonant frequency; controlling the linear motor to enter a high-resistance state, and acquiring reverse electromotive force signals of a plurality of periods; and determining a resonant frequency of the linear motor according to time points of the plurality of peaks based on the reverse electromotive force signal.
In some embodiments, driving the linear motor at the preset resonant frequency includes overdriving the linear motor, followed by conventional driving.
In some embodiments, determining the resonant frequency of the linear motor from the time points of the plurality of peaks based on the back electromotive force signal may include: sampling the reverse electromotive force signal, and performing analog-to-digital conversion on the sampled data to obtain a digital signal; determining a plurality of time points when the back electromotive force occurs to the plurality of peaks according to the quantized value of the digital signal; determining a resonance period of the linear motor based on the plurality of time points at which the peak occurs; and determining the resonant frequency of the linear motor according to the resonant period.
In some embodiments, the method may further comprise: and removing low-order data from the digital signal as the quantized value.
In some embodiments, determining a plurality of points in time at which the plurality of peaks occur in the back electromotive force according to the quantized value of the digital signal comprises: comparing the absolute value of the quantized value with a preset threshold value; recording a first moment when the absolute value of the quantized value is equal to or larger than the preset threshold value; continuing sampling and analog-to-digital conversion operation, and recording a second moment when the quantized value is equal to or smaller than the preset threshold value; and calculating an average value of the first time and the second time, and determining the average value as a point in time when one peak value of the back electromotive force occurs.
In some embodiments, the method may further comprise: driving the linear motor again at the determined resonance frequency; controlling the linear motor to enter a high-resistance state again, and acquiring a second reverse electromotive force signal of a plurality of periods; and determining a resonant frequency of the linear motor based on the second back electromotive force signal according to the point-in-time update of the plurality of peaks.
In some embodiments, the method may further comprise: in response to receiving an end detection signal during the driving, an inverse overdrive is performed on the linear motor after the normal driving.
In some embodiments, the method may further comprise: in response to receiving an end detection signal during the high resistance state, the linear motor is overdriven in anti-phase.
In some embodiments, the waveform amplitude of the inverted overdrive is associated with the time length of the drive.
Another aspect of the present application provides a detection apparatus for a resonant frequency of a linear motor, including: the monitoring module is used for driving the linear motor at a preset resonant frequency and acquiring reverse electromotive force signals of a plurality of periods after controlling the linear motor to enter a high-resistance state; and a calculation module configured to determine a resonant frequency of the linear motor from time points of the plurality of peaks based on the back electromotive force signal.
Another aspect of the present application also provides a resonant frequency detection system of a linear motor, including: the aforementioned linear motor detecting device; and a driving unit for vibrating the linear motor using a driving waveform having the preset resonance frequency or having the determined resonance frequency.
Compared with the prior art, the method and the device for detecting the resonant frequency of the linear motor have the advantages that the resonant frequency is determined by detecting the peak value of the reverse electromotive force, the requirement on the signal to noise ratio can be reduced, and the resonant frequency of the motor can be determined by using fewer detection periods. In addition, the starting vibration of the motor is controlled, so that the detection process is further accelerated; in addition, the detection flow can be ended in both driving operation and detection operation, so that the detection method can be used in various conditions to accurately determine the real resonant frequency of the motor, and the vibration control effect of the motor is improved.
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The foregoing and other objects, features and advantages of the present application will become more apparent from the following more particular description of embodiments of the present application, as illustrated in the accompanying 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 not constitute a limitation to the application. In the drawings, like reference numerals generally refer to like parts or steps.
Fig. 1 shows a flowchart of a method for detecting a resonant frequency of a linear motor according to an embodiment of the present application;
FIG. 2 illustrates a flow chart of a method of determining a resonant frequency of a linear motor from a plurality of peak points in time, provided in accordance with an embodiment of the present application;
fig. 3 shows a flowchart of a method of determining a point in time of a peak of a back electromotive force according to an embodiment of the present application;
fig. 4 shows a schematic diagram of a time point of determining a peak value of a back electromotive force according to an embodiment of the present application;
fig. 5 is a schematic diagram showing a calculation method for determining a resonance period of a back electromotive force according to an embodiment of the present application;
fig. 6 shows a flowchart of a detection method for determining a resonant frequency of a linear motor according to an embodiment of the present application;
FIG. 7 shows a flow chart of a method for detecting resonant frequency of a linear motor according to an embodiment of the present application;
fig. 8 shows a block diagram of a detection device for a resonant frequency of a linear motor according to an embodiment of the present application;
fig. 9 illustrates a block diagram of a detection system for a resonant frequency of a linear motor according to an embodiment of the present application.
Detailed Description
Hereinafter, example 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 present application. It should be understood that the present application should not be limited to the specific details of these example embodiments. Rather, embodiments of the present application may be practiced without these specific details or with other alternatives, without departing from the spirit and principles of the application, which are defined by the claims.
The embodiment provides a detection method of a resonant frequency of a linear motor, which can be applied to various application occasions such as factory setting, frequency calibration in actual use and the like. Referring to fig. 1, which is a flowchart illustrating a method for 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, driving the linear motor at a preset resonant frequency.
In an embodiment, the method for detecting the resonant frequency of the linear motor may be implemented after receiving the detection enable signal, where the enable signal may be triggered by a user or may be triggered according to a driving mode, for example, a corresponding detection enable signal may be generated according to a current driving state, and the control system generates a control signal for generating a driving signal to drive the linear motor after receiving the enable signal.
For example, in response to the control signal, the signal generating circuit may generate a driving signal having a preset resonant frequency and provide the driving signal to the linear motor to cause the motor to vibrate. The driving signal may be a sine wave, a square wave, or the like, and the driving period or duration may also be preset, and in an embodiment, the set driving duration may be a plurality of resonance periods, for example, the cumulative duration of the driving signal may be 0.01-0.3s.
It can be understood that the duration or period of the driving signal may be adjusted according to the driving condition, that is, the driving duration is not limited to the above range, but a smaller duration or a smaller driving period may be selected, so as to accelerate the overall detection flow.
To this end, in one embodiment, this step may include overdriving the linear motor first and then driving conventionally. For example, the driving circuit may first provide the driving signal of one or more periods to the linear motor for super-driving at a first voltage, and then provide the driving signal of one or more periods to the linear motor for normal driving at a second voltage, where the first voltage is greater than the second voltage, so that the vibration starting speed can be increased, and the cumulative duration of super-driving and normal driving may be less than 0.1s, or even less than 0.01s.
Step S120, controlling the linear motor to enter a high-resistance state, and acquiring a reverse electromotive force signal of a plurality of periods.
The back electromotive force is induced by the movement of a permanent magnet (mass) of the linear motor with respect to the wound coil, and the induced back electromotive force signal will also have a natural resonant frequency due to the vibration of the mass at this resonant frequency. In one embodiment, the back electromotive force may be obtained by collecting electromotive forces generated at both ends thereof by vibration generated by driving the linear motor. In step S110, the linear motor is driven under normal vibration, and the back electromotive force is always present, but is easily submerged in a larger driving voltage and difficult to detect, so in an embodiment, the motor may be first driven to enter a high-resistance state, for example, by turning off the driving, and in the high-resistance state, the back electromotive force may be directly detected and obtained without a driving signal, without separating the back electromotive force from the monitoring signal by means of complex calculation. Specifically, the driving signal of the linear motor may be disconnected and the pins at both ends of the motor may be ground discharged before the back electromotive force signal is collected, so that the voltage signal detected at both ends of the motor may be close to the back electromotive force signal.
In one embodiment, the linear motor can be maintained in a high-resistance state for a plurality of periods, and the number of the periods in the high-resistance state can be set according to actual needs. By means of the principle of the invention, the detection of the resonance frequency can be realized through the high-resistance state with less periods, and in an embodiment, the number of the periods of the high-resistance state can be less than 5, for example, 4, 3 or even 2 periods of the high-resistance state can be maintained. When the duration of the high resistance state reaches a predetermined number, the detection flow may be ended or a new round of detection flow may be performed, which will be described later in detail.
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.
Step S130 may be performed after acquiring the back electromotive force signal, based on which the resonant frequency of the linear motor is determined according to the time points of the plurality of peaks.
In the high resistance state, the linear motor will output a counter electromotive force having a resonance frequency. The back electromotive force has two peaks (extremum) of wave crest and wave trough in one period, so that the time point of the peak of the back electromotive force can be determined by tracking and detecting the information such as the amplitude of the back electromotive force signal, and the period of the peak of the back electromotive force can be determined by tracking the determined time point of at least 2 peaks, thereby determining the resonant frequency of the linear motor. It is understood that the "time point of peak" herein is a time point corresponding to the maximum absolute value of the amplitude of the back electromotive force, that is, a time point when the back electromotive force occurs in a peak or a trough.
According to the embodiment, the resonance frequency of the linear motor is determined based on the time information of the peak value, so that compared with a method for determining the resonance frequency through the zero crossing point of the back electromotive force, the requirement on the signal to noise ratio of a signal can be reduced, and the resonance frequency of the linear motor can be determined under a smaller detection period, so that the detection process can be accelerated. The current accurate resonant frequency can be obtained rapidly in practical application, so that the vibration effect of the motor is ensured.
Fig. 2 shows a flowchart of a method for determining a resonant frequency of a linear motor from a plurality of peak points in time, according to an embodiment of the present application. As shown in fig. 2, the peak time point of the motor electromotive force can be determined and the resonance frequency of the motor can be determined based on the following steps:
step 210, sampling the reverse electromotive force signal, and performing analog-to-digital conversion on the sampled data to obtain a digital signal.
For example, the acquired back electromotive force signal may be sampled at a predetermined sampling frequency and then passed through an input analog-to-digital converter (ADC) which converts the analog input signal into a digital signal, which may then be processed to detect the magnitude of the electromotive force.
In one embodiment, the analog-to-digital converter may employ low precision analog-to-digital conversion hardware, and by employing the resonant frequency calculation method described below, accurate resonant frequencies may still be obtained using low precision ADC devices.
Step 220, determining a plurality of time points when the back electromotive force occurs at the plurality of peak values according to the quantized value of the digital signal.
For example, after determining that the first peak value occurs and recording the time point of the back electromotive force according to the magnitude and polarity of the back electromotive force represented by the quantized value of the digital signal, sampling is continued for a predetermined period (for example, the period may be determined based on a preset resonance period), the extremum of the period is detected to determine the time point when the second peak value occurs, and so on, it is also possible to determine each time point of the third, fourth, etc. plurality of peak values within a prescribed period of time/period.
In an embodiment, before implementing step 220, signal processing such as low bit depth quantization may be performed on the digital signal obtained after the analog-to-digital conversion, so as to detect a peak point in time, for example, the low bit data may be removed from the digital signal as the quantized value, and a point in time when the back electromotive force occurs to a peak may be determined based on the low bit depth quantized value. For example, the 16-bit data obtained after ADC processing is 0x 1000 1000 1000 1111, and the quantized value obtained by processing the digital signal of the inverse electromotive force is 0x 1000 1000 0000 0000 after removing the low-bit data, such as the last 4 bits or the last 8 bits, by low-bit-depth quantization processing, for example, erasing the low-bit data. In this way, the signal to noise ratio requirements can be significantly reduced, and the method for determining the peak time point will be described in detail below.
Step 230, determining a resonant period of the linear motor based on the plurality of time points at which the peak occurs.
After each time point of the plurality of peaks is determined, a peak-to-peak period (i.e., a time interval between a peak and an adjacent peak) and/or a peak-to-valley period (i.e., a time interval between a peak and an adjacent valley) can be determined correspondingly, and the resonance period can be determined by a peak-to-peak period or a peak-to-valley period, or a period of reverse electromotive force can be converted and determined according to a plurality of peak-to-peak periods or peak-to-valley periods to serve as a resonance period of the linear motor.
Step 240, determining the resonant frequency of the linear motor according to the resonant period.
After determining the resonant period, the resonant frequency of the motor may be calculated based on f0=1/T, where f0 is the resonant frequency of the motor and T is the resonant period determined in step 230.
Fig. 3 shows a flowchart of a method for determining a point in time of a peak value of an inverse electromotive force according to a quantized value of a digital signal according to an embodiment of the present application. As shown in fig. 3, the peak time point of the motor back electromotive force may be determined based on the following steps:
step 222, comparing the absolute value of the quantized value with a preset threshold.
For example, as described above, the sampled digital signal may be first subjected to a low bit depth quantization process to obtain a quantized value, and then the absolute value thereof may be compared with a preset threshold. The preset threshold may be smaller than a peak value (maximum value) of the back electromotive force. In one embodiment, a sliding window operation may be employed for smoothing the data for noise reduction processing.
Step 224, recording a first moment when the absolute value of the quantized value is equal to or greater than the preset threshold value.
For example, referring to fig. 4, a schematic diagram of a time point of determining a peak value of a back electromotive force according to an embodiment of the present application is shown. When the value of the determined quantized value exceeds a preset threshold value, i.e., the back electromotive force steps into the peak section, a time t1 when it is equal to or greater than the threshold value for the first time may be recorded.
And 226, continuing the sampling and analog-to-digital conversion operation, and recording a second moment when the quantized value is equal to or smaller than the preset threshold value.
After stepping into the peak section, the reverse electromotive force of the motor will approach its peak value, but since the magnitude of the reverse electromotive force of each sampling point near the peak value is close, errors are liable to occur, and in this embodiment, the sampling and analog-to-digital conversion operations are continued instead of recording the timing at the peak value, and the second timing when the quantized value is equal to or smaller than the preset threshold value is recorded.
For example, referring to fig. 4, the sampling and analog-to-digital conversion operation may be continued after the first time t1 is recorded to obtain a quantized value that is equal to or smaller than the preset threshold value for the first time t2. In the case of performing the low-order deep processing, there may be a case where quantized values of two or more sampling points adjacent to t2 are the same, and t2 may be replaced with a time corresponding to a last sampling point among the two or more sampling points.
Step 228, calculating the average value of the first time and the second time, and determining the average value as a point in time when the back electromotive force has a peak value.
Referring to fig. 4, on the basis of the obtained first time t1 and second time t2, a time point tp1= (t1+t2)/2 at which one peak of the back electromotive force occurs can be determined.
By repeating the above steps, it is possible to determine the respective time points of the plurality of peaks (peaks and valleys) within the prescribed duration/period of the back electromotive force, for example, the time points of the peaks tp2, tp3 and the like shown in fig. 4.
Referring to fig. 5, a schematic diagram of a calculation method for determining a resonance period of a back electromotive force according to an embodiment of the present application is shown in fig. 5, after determining a time point at which each peak occurs, a half period h (or referred to as a peak-to-valley period) and a full period c (or referred to as a peak-to-peak period) of the back electromotive force may be calculated according to the time point, for example, a series of adjacent peaks may be found, a corresponding half period h and full period c may be calculated, and a resonance period T may be obtained for h and c by, for example, weighting calculation. In an embodiment, for the back electromotive force waveform schematic diagram shown in fig. 5, half periods h1, h2, h3 between the peaks and the troughs and full periods c1, c2 between the peaks, the peaks and the troughs can be calculated, and a certain numerical calculation is performed to determine a resonance period of the back electromotive force, for example, t= (2×h1+2×h2+2×h3+c1+c2)/5 can be specifically used to calculate the resonance period, so that the resonance frequency f0=1/T of the motor can be determined.
In addition, the existing technology for detecting the resonance frequency of the motor generally carries out braking operation directly after detection in a high-resistance state, and the obtained resonance frequency may still deviate from the true resonance frequency of the motor. To solve the technical problem, embodiments herein provide a method for detecting a resonant frequency of a linear motor, which includes alternately performing a driving operation and a detecting operation, and after the detecting operation, controlling the motor to perform a new driving operation. Specifically, during a driving operation, the driving waveform may be updated to drive the motor based on the detected and determined resonance frequency to improve the vibration intensity of the motor; during the detection operation, the motor is controlled to enter a high resistance state, the back electromotive force across the motor is monitored, and the true resonant frequency of the motor is calculated. By alternately executing a plurality of driving operations and detecting operations, the detecting precision of the resonant frequency can be stably improved, thereby ensuring stable vibration quantity and smooth vibration sense.
Referring to fig. 6, which is a flowchart illustrating a method for determining a resonant frequency of a linear motor according to an embodiment of the present application, it is understood that the steps illustrated in fig. 6 may be operation steps performed continuously based on the foregoing detection method, for example, the following steps may be performed based on the method illustrated in fig. 1:
step 310, driving the linear motor again at the determined resonance frequency.
For example, after step 130 of fig. 1 is performed, a resonant frequency of the motor (hereinafter, referred to as a first resonant frequency) may be determined, but the first resonant frequency may deviate from a real frequency of the motor, and for this purpose, a gradient driving voltage may be applied to the motor again in response to the absence of receiving a signal to stop detection, and overdriving and regular driving may be performed with a driving waveform having the determined first resonant frequency.
Step 320, controlling the linear motor to enter a high-resistance state again, and acquiring a second back electromotive force signal for a plurality of periods.
This step may be performed in a similar manner to step 120 of fig. 1, for example, the linear motor may be maintained in a high-impedance state for several periods, and the collected back electromotive force signal may be subjected to signal processing to obtain a second back electromotive force signal, which is not described herein.
Step 330, based on the second back electromotive force signal, determining a resonant frequency of the linear motor according to the point-in-time update of the plurality of peaks.
This step may be performed in a similar manner to step 130 of fig. 1, for example, the back electromotive force signal may be sampled, quantized in low bit depth, and tracked to determine a point of time at which the back electromotive force is peaked, and then a period of the back electromotive force may be determined through at least 2 points of time at which the back electromotive force is peaked, so that a resonant frequency (hereinafter referred to as a second resonant frequency) of the linear motor may be determined, which is closer to a real resonant frequency of the motor than the first resonant frequency, that is, a detection accuracy of the resonant frequency is improved through a driving operation and a detection operation performed alternately.
Step 340, determining whether an end detection signal is received.
For example, if the end detection signal is not received, the process may return to step 310 to continue with a new round of driving and detecting operations. Otherwise, in response to receiving the end detection signal during the high resistance state, the linear motor may be overdriven in reverse phase, i.e., overdriven in a phase opposite to the reverse electromotive force to shorten the braking time, so that the motor rapidly stops vibrating, and then the driving is turned off.
In one embodiment, the present invention may also end the detection process during the driving operation, so that the detection of the present invention is adapted to various situations. For example, in response to receiving the end detection signal during the driving, the linear motor is overdriven in reverse phase after the normal driving to end the detection flow. I.e. during driving operation, the motor may be overdriven, driven conventionally and overdriven in opposite phase.
In one embodiment, to enable the motor to exit detection of the resonant frequency as soon as possible, the waveform amplitude of the drive operation and/or the anti-phase overdrive in the detection operation may be set to be associated with the time length of the drive. For example, the motor can be combined with super-drive and conventional drive to control the maximum duration of the detection operation, and the integral amplitude of the inverted super-drive waveform has a linear relation related to the duration, so that the motor can rapidly start and stop after the detection is finished.
Fig. 7 shows a flowchart of a method for detecting a resonant frequency of a linear motor according to an embodiment of the present application. As shown in fig. 7, the detection flow may include a driving operation and a detection operation that are alternately performed, specifically, it includes:
in step 410, the driving frequency of the linear motor is determined. In the initial driving operation, the driving frequency may be a preset resonance frequency, and in a subsequent re-driving stage, the driving frequency may be updated to the resonance frequency determined in the previous detecting operation.
In step 420, the motor is overdriven. For example, the driving circuit of the motor may be implemented by adjusting the level of the voltage applied to both ends of the motor, and the adjusted voltage may be calculated based on a preset voltage, thereby enabling the motor to rapidly start vibrating.
In step 430, the motor is driven conventionally. For example, the driving voltage is adjusted to a preset voltage after one or more periods of overdriving is performed, and the motor is driven at the voltage for one or more periods.
In step 440, it is determined whether the motor has received a signal to end the detection.
In response to receiving an end detection signal during the driving, the linear motor is overdriven in reverse phase after the normal driving, thereby rapidly braking the motor. It will be appreciated that for the first drive operation, the value of the termination enable signal may be controlled to be 0, i.e. without jumping out of the detection flow.
In response to not receiving an end detection signal during the driving, a jump is made to step 450.
In step 450, the motor is controlled to enter a high-impedance state, and a reverse electromotive force signal generated by motor motion induction is obtained.
For example, the application of a drive voltage or drive signal to the linear motor may be stopped and a brief ground discharge may be made across the motor input pin, such that the subsequently measured voltage signal across the motor may be made to approximate the counter electromotive force. After the motor enters a high-resistance state, a reverse electromotive force signal of a plurality of periods can be acquired. During the process of acquisition, the acquired signals may be sampled and quantized, and the specific method may refer to the foregoing description, which is not repeated here.
In step 460, the resonant frequency of the motor is calculated based on the peak period of the back electromotive force.
For example, a digital signal of the back electromotive force may be obtained based on a quantization method of a low bit depth, and compared with a preset threshold value to determine a first time when the back electromotive force steps into a peak interval, and further sample a second time when the quantized value steps out of the peak interval, determine a peak time of the back electromotive force based on an average value of the first time and the second time, and determine a peak period based on a plurality of peak times to calculate a resonance frequency of the motor. In particular, the method described with reference to fig. 2-5 may be employed, and will not be repeated here.
In step 470, it is determined whether a signal to end the detection is received.
In response to receiving the end detection signal during the detection process, the linear motor may be overdriven in anti-phase to thereby rapidly brake the motor. In one embodiment, the inverted overdrive and the inverted overdrive in step 440 may use identical waveforms, e.g., the overall amplitude of the two inverted overdrive waveforms has a linear relationship associated with the drive time.
In response to not receiving the end signal, the control motor jumps to step 410 to re-enter the drive operation for the next round. Through a plurality of alternate operations of driving and detecting, the embodiment can steadily improve the accuracy of resonant frequency detection.
According to the method for detecting the motor resonant frequency, which is provided by the embodiment of the invention, the resonant frequency is determined based on the peak time of the reverse electromotive force, so that the requirement on the signal-to-noise ratio can be reduced, and the hardware requirement of a system is reduced. In addition, the accuracy of detection can be improved through the alternation of driving operation and detection operation, the stability of vibration quantity is ensured, in addition, the resonance frequency can be determined through the control of starting vibration of the motor by using fewer detection periods, and the detection process is further accelerated.
The embodiment of the invention also provides a device for detecting the resonant frequency of the linear motor. As shown in fig. 8, the linear motor resonance frequency detection apparatus 500 according to an embodiment of the present application may include: the monitoring module 510 is connected with the motor and is used for driving the linear motor at a preset resonant frequency and acquiring reverse electromotive force signals of a plurality of periods after controlling the linear motor to enter a high-resistance state; and a calculation module 520 connected to the monitoring module 510 and configured to determine a resonant frequency of the linear motor from time points of the plurality of peaks based on the back electromotive force signal.
In one example, the monitoring module 510 may be configured to collect the back electromotive force signal for a predetermined time, and may also filter, e.g., low pass filter, the collected back electromotive force signal and perform a smoothing pre-process to obtain a signal of interest free of glitches.
In one example, the calculation module 520 may be configured to determine the resonant frequency of the linear motor in the following manner: sampling the reverse electromotive force signal, and performing analog-to-digital conversion on the sampled data to obtain a digital signal; determining a plurality of time points when the back electromotive force occurs to the plurality of peaks according to the quantized value of the digital signal; determining a resonance period of the linear motor based on the plurality of time points at which the peak occurs; and determining the resonant frequency of the linear motor according to the resonant period.
In one example, the computing module 520 may be configured to further perform: and removing low-order data from the digital signal as the quantized value.
In one example, the calculation module 520 may be configured to determine a plurality of points in time at which the plurality of peaks occur in the back electromotive force by: comparing the absolute value of the quantized value with a preset threshold value; recording a first moment when the absolute value of the quantized value is equal to or larger than the preset threshold value; continuing sampling and analog-to-digital conversion operation, and recording a second moment when the quantized value is equal to or smaller than the preset threshold value; and calculating an average value of the first time and the second time, and determining the average value as a point in time when one peak value of the back electromotive force occurs.
In one example, the monitoring module 510 may be configured to acquire a number of periods of the second back electromotive force signal after driving the linear motor again at the determined resonant frequency and controlling the linear motor again to enter a high resistance state; the calculation module 520 may be configured to determine a resonant frequency of the linear motor from the point-in-time updates of the plurality of peaks based on the second back electromotive force signal.
The specific functions and operations of the respective units and modules in the above-described resonance frequency detection apparatus 500 have been described in detail in the detection methods described above with reference to fig. 1 to 5, and thus are only briefly described herein, and unnecessary repetitive descriptions are omitted.
The detection system of the resonant frequency of the linear motor is described below with reference to fig. 9, and as illustrated in fig. 9, the detection system of the resonant frequency of the linear motor 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 determining the resonant frequency of the linear motor, and is specifically described with reference to fig. 1-8 and related description, which are not repeated herein. The driving unit 630 may drive the linear motor using a driving waveform having a preset resonant frequency or a detected and determined resonant frequency, and the driving unit may use an H-bridge or the like. Although not shown, the control system may further include a driving generation circuit that may provide a driving signal (e.g., a sinusoidal signal, a square wave signal, etc.) to the driving unit 630 according to a preset resonance frequency or a resonance frequency determined by detection, thereby stably implementing tracking detection of the resonance frequency of the linear motor, improving detection accuracy, facilitating stabilization of the vibration amount of the motor, and ensuring optimal effects of the haptic vibration sensation provided to the user.
In one embodiment, the driving unit 630 drives the linear motor at a preset resonant frequency includes overdriving the linear motor and then performing a conventional driving.
In an embodiment, the driving unit 630 may be configured to super-drive the linear motor in an opposite phase after the normal driving in response to receiving an end detection signal during the driving.
In an embodiment, the driving unit 630 may be configured to reverse-phase overdriving the linear motor in response to receiving an end detection signal during the high resistance state.
In an embodiment, the waveform amplitude of the inverted overdrive is associated with the time length of the drive.
The basic principles of the present application have been described above in connection with specific embodiments, however, it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are merely examples and not limiting, and these advantages, benefits, effects, etc. are not to be considered as necessarily possessed by the various embodiments of the present 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 intended to be limited to the details disclosed herein as such.
The block diagrams of the devices, apparatuses, devices, systems referred to in this 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 to 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 the 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 (11)
1. A method of detecting a resonant frequency of a linear motor, comprising:
driving the linear motor at a preset resonant frequency;
controlling the linear motor to enter a high-resistance state, and acquiring reverse electromotive force signals of a plurality of periods; and
based on the back electromotive force signal, a resonance frequency of the linear motor is determined according to time points of a plurality of peaks.
2. The detection method according to claim 1, wherein driving the linear motor at the preset resonant frequency includes overdriving the linear motor and then performing a normal driving.
3. The detection method according to claim 1, wherein determining a resonance frequency of the linear motor from time points of a plurality of peaks based on the back electromotive force signal includes:
sampling the reverse electromotive force signal, and performing analog-to-digital conversion on the sampled data to obtain a digital signal;
determining a plurality of time points when the back electromotive force occurs to the plurality of peaks according to the quantized value of the digital signal;
determining a resonance period of the linear motor based on the plurality of time points at which the peak occurs; and
and determining the resonant frequency of the linear motor according to the resonant period.
4. A detection method according to claim 3, wherein the method further comprises:
and removing low-order data from the digital signal as the quantized value.
5. The detection method according to claim 3 or 4, wherein determining a plurality of points in time at which the plurality of peaks occur in the back electromotive force according to the quantized value of the digital signal includes:
comparing the absolute value of the quantized value with a preset threshold value;
recording a first moment when the absolute value of the quantized value is equal to or larger than the preset threshold value;
continuing sampling and analog-to-digital conversion operation, and recording a second moment when the quantized value is equal to or smaller than the preset threshold value; and
and calculating the average value of the first moment and the second moment, and determining the average value as a time point when the back electromotive force appears to be one peak value.
6. The detection method according to claim 2, further comprising:
driving the linear motor again at the determined resonance frequency;
controlling the linear motor to enter a high-resistance state again, and acquiring a second reverse electromotive force signal of a plurality of periods; and
and based on the second back electromotive force signal, determining the resonant frequency of the linear motor according to the time point update of the plurality of peaks.
7. The detection method of claim 6, further comprising:
in response to receiving an end detection signal during the driving, an inverse overdrive is performed on the linear motor after the normal driving.
8. The detection method according to claim 1 or 6, further comprising:
in response to receiving an end detection signal during the high resistance state, the linear motor is overdriven in anti-phase.
9. The detection method of claim 8, wherein a waveform amplitude of the inverted overdrive is associated with a time period of the drive.
10. A device for detecting a resonant frequency of a linear motor, comprising:
the monitoring module is used for driving the linear motor at a preset resonant frequency and acquiring reverse electromotive force signals of a plurality of periods after controlling the linear motor to enter a high-resistance state; and
a calculation module configured to determine a resonant frequency of the linear motor from time points of the plurality of peaks based on the back electromotive force signal.
11. A system for detecting a resonant frequency of a linear motor, comprising:
the detection device of claim 10; and
and a driving unit for vibrating the linear motor using a driving waveform having the preset resonant frequency or having the determined resonant frequency.
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