A method and system for normalizing the back electromotive force of a linear resonant motor

Abstract

The embodiment of the present invention provides a linear resonant motor control method and system. During the automatic over-driving and automatic braking phases of the LRA driving chip, the error signal after normalizing the back electromotive force signal is amplified and used to adjust the amplitude of the driving voltage waveform, thereby improving the problem that the closed-loop oscillator speed value deviates from the designed speed due to inconsistent BL coefficients. During the automatic over-driving process, the LRA speed control accuracy can be improved. During the automatic braking process, the aftershock problem caused by insufficient braking waveform control accuracy can be improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of linear resonant motor control, and in particular, to a linear resonant motor control method and system. Background Art

[0002] A linear resonant actuator (LRA) is usually used to provide a haptic feedback effect on a portable terminal. The LRA includes components such as springs, coils, and oscillators. It is driven by an LRA drive chip. The drive chip applies an exciting current to the coil to generate a magnetic field, which pushes the magnetic oscillator in a certain direction. When the direction of the exciting current changes, the magnetic field and the driving force also change. Therefore, if a periodic voltage signal is applied to the coil by the drive chip, the generated periodic exciting current will push the oscillator to vibrate back and forth, achieving the haptic feedback effect. Due to the resonant characteristics of the LRA, the amplitude of the oscillator vibration shows a band-pass characteristic with respect to the driving signal frequency. When the driving signal frequency is at the natural frequency (F0) of the oscillator, the amplitude of the oscillator vibration reaches the maximum and the vibration efficiency is the best.

[0003] To achieve a better haptic feedback effect, the linear resonant motor drive chip supports effects such as automatic braking and automatic over-driving.

[0004] In the existing linear resonant motor drive chip, the automatic braking and automatic over-driving functions obtain the oscillator speed information by detecting the back electromotive force (BEMF) of the LRA oscillator. Among them, the magnetic force coefficient BL of the linear resonant motor needs to be used, which is composed of the magnetic flux density in the oscillator air gap and the length of the coil wire. Due to factors such as machining deviation, component aging, and temperature drift of the linear resonant motor, there is a certain deviation between the BL value of the LRA finished product and the design value. During the automatic over-driving process, this deviation will cause the speed control accuracy of the LRA to deteriorate. During the automatic braking process, this deviation will cause the braking waveform to end earlier or later, generating aftershocks higher than expected. Summary of the Invention

[0005] Therefore, the embodiments of the present invention provide a linear resonant motor control method and system to solve the above technical problems in the prior art.

[0006] To achieve the above object, the embodiments of the present invention provide the following technical solutions:

[0007] According to the first aspect of the embodiments of the present invention, the embodiments of the present application provide a linear resonant motor control method, the method includes:

[0008] Perform back electromotive force consistency calibration on the linear resonant motor, and record the forward gain calibration value G ol，finaland the back electromotive force feedback gain calibration value G bemf，final ;

[0009] Collect the measured value of the second back electromotive force at both ends of the linear resonant motor according to a preset period;

[0010] Use the back electromotive force feedback gain calibration value G bemf，final , normalize the measured value of the second back electromotive force to the target value to obtain a second normalized back electromotive force signal;

[0011] Parse the vibration effect instruction from the vibration enabling signal through a preset rule, and adjust and output an over-drive signal and a brake signal according to the amplitude input signal and the second normalized back electromotive force signal;

[0012] According to the over-drive signal and the brake signal, amplify the normalized error signal to adjust the amplitude of the driving voltage waveform to obtain a first driving voltage waveform amplitude adjustment signal;

[0013] Use the forward gain calibration value G ol，final Adjust the first driving voltage waveform amplitude adjustment signal to obtain a second driving voltage waveform amplitude adjustment signal;

[0014] Use the measured value of the second back electromotive force to detect the back electromotive force frequency, calculate the frequency of the driving waveform according to the error between the back electromotive force frequency and the preset natural frequency value, and use the second driving voltage waveform amplitude adjustment signal as the amplitude of the driving waveform to obtain a driving waveform DDS output signal; and

[0015] Use the driving waveform DDS output signal to generate two PWM signals, and drive the linear resonant motor through a driving circuit.

[0016] Further, perform back electromotive force consistency calibration on the linear resonant motor, including:

[0017] Receive a calibration trigger signal from the host computer and detect whether the calibration trigger signal is high;

[0018] If the calibration trigger signal is high, set the closed-loop control gain value G cl to 0, set the forward gain value G ol to 1, and drive the linear resonant motor LRA with a periodic waveform of the full input amplitude corresponding to the rated voltage V rated provided by the manufacturer;

[0019] Detect the voltage amplitude V of the periodic waveform at both ends of the linear resonant motor LRA ;

[0020] Set the closed-loop control gain value G clSet it to 0, and set the forward gain value G ol to the rated voltage V rated and the first ratio of the voltage amplitude V LRA Drive the linear resonant motor with a full input amplitude according to a preset duration, so that the driving waveform reaches a stable vibration amplitude;

[0021] Collect the measured value of the first back electromotive force at both ends of the linear resonant motor;

[0022] Utilize the back electromotive force feedback gain value G bemf , normalize the measured value of the first back electromotive force to a target value to obtain a first normalized back electromotive force signal;

[0023] Adjust the back electromotive force feedback gain value G bemf , so that the peak value of the first normalized back electromotive force signal is close to 1. At this time, the back electromotive force feedback gain value G bemf is the back electromotive force feedback gain calibration value G bemf，final , and the rated voltage V rated and the first ratio of the voltage amplitude V LRA is the forward gain calibration value G ol，final .

[0024] Furthermore, collecting the measured value of the first back electromotive force / the measured value of the second back electromotive force at both ends of the linear resonant motor includes:

[0025] Detect the first voltage signal V1 / the second voltage signal V2 at both ends of the linear resonant motor;

[0026] Detect the first current signal I1 / the second current signal I2 flowing through the port of the linear resonant motor;

[0027] Utilize the first voltage signal V1 / the second voltage signal V2, the first current signal I1 / the second current signal I2, and the preset coil resistance parameter R to calculate the measured value of the first back electromotive force / the measured value of the second back electromotive force;

[0028] The calculation formula for the measured value of the first back electromotive force / the measured value of the second back electromotive force is:

[0029] V BEMF1 = V1 - I1R

[0030] V BEMF2 = V2 - I2R

[0031] where, V BEMF1 is the measured value of the first back electromotive force, and V BEMF2 is the measured value of the second back electromotive force.

[0032] Further, parse the vibration effect instruction from the vibration enabling signal according to a preset rule, and adjust and output an over-drive signal and a brake signal based on the amplitude input signal and the second normalized back electromotive force signal, including:

[0033] Set the initial value of the over-drive signal and the initial value of the brake signal to low;

[0034] Detect whether the vibration enabling signal issued by the host computer becomes valid;

[0035] If the vibration enabling signal becomes valid, start reading the amplitude input signal and the second normalized back electromotive force signal;

[0036] Calculate the second ratio of the current second normalized back electromotive force signal to the current amplitude input signal;

[0037] Detect whether the current amplitude input signal is greater than a preset amplitude threshold;

[0038] If the current amplitude input signal is greater than the preset amplitude threshold, determine whether the second ratio is less than a first preset ratio threshold;

[0039] If the second ratio is less than the first preset ratio threshold, pull up the over-drive signal;

[0040] If the second ratio is greater than or equal to the first preset ratio threshold, pull down the over-drive signal;

[0041] If the current amplitude input signal is not greater than the first preset amplitude threshold, determine whether the current amplitude input signal is zero;

[0042] If the current amplitude input signal is zero, determine whether the second ratio is less than a second preset ratio threshold;

[0043] If the second ratio is not less than the second preset ratio threshold, pull up the brake signal;

[0044] If the second ratio is less than the second preset ratio threshold, pull down the brake signal.

[0045] Further, based on the over-drive signal and the brake signal, amplify the normalized error signal to adjust the amplitude of the drive voltage waveform, and obtain a first drive voltage waveform amplitude adjustment signal, including:

[0046] Obtain a normalized oscillator speed error using the amplitude input signal and the second normalized back electromotive force signal;

[0047] Obtain a preset value of the closed-loop control gain according to the high and low conditions of the over-drive signal and the brake signal;

[0048] Multiply the normalized oscillator rate error by the preset value of the closed-loop control gain to obtain the output value of the closed-loop control gain.

[0049] Further, according to the high or low conditions of the over-drive signal and the brake signal, obtaining the preset value of the closed-loop control gain includes:

[0050] Detect whether the over-drive signal is high;

[0051] If the over-drive signal is high, set the preset value of the closed-loop control gain to the first preset value;

[0052] Detect whether the brake signal is high;

[0053] If the brake signal is high, set the preset value of the closed-loop control gain to the second preset value;

[0054] If both the over-drive signal and the brake signal are low, set the preset value of the closed-loop control gain to zero.

[0055] Further, detect the back electromotive force frequency using the measured value of the second back electromotive force, and calculate the frequency of the drive waveform according to the error between the back electromotive force frequency and the preset natural frequency value, including:

[0056] Compare the magnitudes of the back electromotive force frequency and the preset natural frequency value;

[0057] If the back electromotive force frequency is lower than the preset natural frequency value, increase the frequency of the drive waveform;

[0058] If the back electromotive force frequency is higher than the preset natural frequency value, decrease the frequency of the drive waveform.

[0059] Further, generate two PWM signals using the drive waveform DDS output signal, and drive the linear resonant motor through a drive circuit, including:

[0060] The two generated PWM signals include a PWMP signal and a PWMN signal;

[0061] Judge the polarity of the drive waveform DDS output signal;

[0062] If the polarity of the drive waveform DDS output signal is positive, pull down the PWMN signal, invert the PWMP signal, and convert the absolute value of the drive waveform DDS output signal into the duty cycle information of the PWMP signal;

[0063] If the polarity of the output signal of the driving waveform DDS is negative, pull down the PWMP signal, invert the PWMN signal, and convert the absolute value of the output signal of the driving waveform DDS into the duty cycle information of the PWMP signal;

[0064] The driving circuit converts the high level of the PWMP signal into the upper transistor turn-on signal of the output power transistor at the OUTP terminal and the lower transistor turn-off signal of the output power transistor at the OUTP terminal;

[0065] The driving circuit converts the low level of the PWMP signal into the lower transistor turn-on signal of the output power transistor at the OUTP terminal and the upper transistor turn-off signal of the output power transistor at the OUTP terminal;

[0066] The driving circuit converts the high level of the PWMN signal into the upper transistor turn-on signal of the output power transistor at the OUTN terminal and the lower transistor turn-off signal of the output power transistor at the OUTN terminal;

[0067] The driving circuit converts the low level of the PWMN signal into the lower transistor turn-on signal of the output power transistor at the OUTN terminal and the upper transistor turn-off signal of the output power transistor at the OUTN terminal.

[0068] According to the second aspect of the embodiments of the present invention, an embodiment of the present application provides a linear resonant motor control system, and the system includes:

[0069] The digital circuit part, which includes:

[0070] The BEMF detection module is used to collect the measured value of the second back electromotive force at both ends of the linear resonant motor according to a preset period;

[0071] The driving voltage control module is used to perform back electromotive force consistency calibration on the linear resonant motor, and record the forward gain calibration value G ol，final and the back electromotive force feedback gain calibration value G bemf，final ; use the back electromotive force feedback gain calibration value G bemf，final , normalize the measured value of the second back electromotive force to a target value to obtain a second normalized back electromotive force signal;

[0072] The playback control module is used to parse the vibration effect instruction from the vibration enable signal according to a preset rule, and adjust and output an over-drive signal and a brake signal according to the amplitude input signal and the second normalized back electromotive force signal;

[0073] The driving voltage control module is further used to adjust the amplitude of the driving voltage waveform by amplifying the normalized error signal according to the over-drive signal and the brake signal to obtain a first driving voltage waveform amplitude adjustment signal; use the forward gain calibration value G ol，fina1Adjust the first drive voltage waveform amplitude adjustment signal to obtain a second drive voltage waveform amplitude adjustment signal;

[0074] An F0 detection module, configured to detect the back electromotive force frequency by using the measured value of the second back electromotive force, and calculate the frequency of the drive waveform according to the error between the back electromotive force frequency and a preset natural frequency value;

[0075] A direct digital frequency synthesizer for the drive waveform, configured to obtain a DDS output signal of the drive waveform according to the calculated frequency of the drive waveform and using the second drive voltage waveform amplitude adjustment signal as the amplitude of the drive waveform; and

[0076] A PWM modulator, configured to generate two PWM signals by using the DDS output signal of the drive waveform, and drive the linear resonant motor through a drive circuit.

[0077] Further, the system further includes:

[0078] An analog circuit part, where the analog circuit part includes: a drive circuit, a voltage detection ADC, and a current detection ADC;

[0079] The voltage detection ADC is configured to detect a first voltage signal V1 / second voltage signal V2 across the linear resonant motor; the current detection ADC is configured to detect a first current signal I1 / second current signal I2 flowing through the port of the linear resonant motor; the BEMF detection module calculates a first measured value of the back electromotive force / second measured value of the back electromotive force by using the first voltage signal V1 / second voltage signal V2, the first current signal I1 / second current signal I2, and a preset coil resistance parameter R;

[0080] The two PWM signals generated by the PWM modulator include a PWMP signal and a PWMN signal; the PWM modulator is further configured to determine the polarity of the DDS output signal of the drive waveform; if the polarity of the DDS output signal of the drive waveform is positive, pull down the PWMN signal, invert the PWMP signal, and convert the absolute value of the DDS output signal of the drive waveform into the duty cycle information of the PWMP signal; if the polarity of the DDS output signal of the drive waveform is negative, pull down the PWMP signal, invert the PWMN signal, and convert the absolute value of the DDS output signal of the drive waveform into the duty cycle information of the PWMP signal;

[0081] The driving circuit is used to convert the high level of the PWMP signal into the on signal of the upper transistor of the output power transistor at the OUTP terminal and the off signal of the lower transistor of the output power transistor at the OUTP terminal; the driving circuit converts the low level of the PWMP signal into the on signal of the lower transistor of the output power transistor at the OUTP terminal and the off signal of the upper transistor of the output power transistor at the OUTP terminal; the driving circuit converts the high level of the PWMN signal into the on signal of the upper transistor of the output power transistor at the OUTN terminal and the off signal of the lower transistor of the output power transistor at the OUTN terminal; the driving circuit converts the low level of the PWMN signal into the on signal of the lower transistor of the output power transistor at the OUTN terminal and the off signal of the upper transistor of the output power transistor at the OUTN terminal.

[0082] Compared with the prior art, in the automatic over-driving and automatic braking stages of the LRA driving chip, the linear resonance motor control method and system provided by the embodiments of the present application amplify the error signal after normalizing the back electromotive force signal to adjust the amplitude of the driving voltage waveform. In the acceleration stage, if the speed of the LRA oscillator is too low, the error of the normalized back electromotive force signal is greater than zero, and the driving voltage control module provides a driving voltage waveform higher than the rated voltage for over-driving. If the speed of the LRA oscillator is too high, the error of the normalized back electromotive force signal is less than zero, and the driving voltage control module provides a driving waveform lower than the rated voltage for driving. In the braking stage, if the speed of the LRA oscillator is too high, the error of the normalized back electromotive force signal is less than zero, and the amplitude of the inverted braking driving voltage waveform is increased. If the speed of the LRA oscillator is lower than a preset threshold, the error of the normalized back electromotive force signal is less than a preset threshold, and the playback of the braking driving voltage waveform is stopped in advance to avoid aftershocks caused by excessive braking. The control module uses the normalized error signal of the back electromotive force signal as the input, thereby improving the problem that the closed-loop oscillator speed value deviates from the designed speed due to inconsistent BL coefficients. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings described below are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained according to the provided drawings.

[0084] The structures, ratios, sizes, etc. shown in this specification are only used to cooperate with the content disclosed in the specification for those who are familiar with this technology to understand and read, and are not used to limit the limited conditions for the implementation of the present invention. Therefore, they do not have technical essence. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that the technical content disclosed by the present invention can cover.

[0085] Figure 1 Schematic structural diagram of a linear resonant motor control system provided by an embodiment of the present invention;

[0086] Figure 2 Schematic flowchart of a linear resonant motor control method provided by an embodiment of the present invention;

[0087] Figure 3 Schematic diagram of the working principle of the drive voltage control module provided by an embodiment of the present invention. Detailed implementation manners

[0088] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0089] The principle of automatic over-driving and automatic braking of existing linear resonant motor drive chips is to detect the back electromotive force (BEMF) and sense the real-time speed of the LRA oscillator. During the acceleration or braking stage of the LRA, the measured value of the BEMF is subtracted from the target value of the BEMF to obtain the BEMF error value. This error is quickly calculated by the controller to obtain the drive voltage waveform to drive the LRA. During the acceleration stage, if the speed of the LRA oscillator is low, a drive voltage waveform higher than the rated voltage is provided for over-driving. If the speed of the LRA oscillator is high, a drive waveform lower than the rated voltage is provided for driving. During the braking stage, if the speed of the LRA oscillator is high, the amplitude of the braking drive voltage waveform is increased. If the speed of the LRA oscillator is lower than a preset threshold, the playback of the braking drive voltage waveform is stopped in advance to avoid aftershocks caused by excessive braking.

[0090] The functions of automatic braking and automatic over-driving in existing linear resonant motor drive chips obtain the oscillator speed information by detecting the back electromotive force (BEMF) of the LRA oscillator. The relationship between the back electromotive force BEMF and the oscillator speed v is as follows:

[0091] BEMF = BLv

[0092] Among them, BL is the magnetic force coefficient of the linear resonant motor, which is composed of the magnetic flux density in the oscillator air gap and the length of the coil wire. Due to factors such as machining deviation, component aging, and temperature drift of the linear resonant motor, there is a certain deviation between the BL value of the LRA finished product and the design value. During the automatic over-drive process, this deviation will cause the LRA speed control accuracy to deteriorate. During the automatic braking process, this deviation will cause the braking waveform to end earlier or later, generating aftershocks higher than expected.

[0093] To solve the above technical problems, as Figure 1 shown, an embodiment of the present application provides a linear resonant motor control system, including: a digital circuit part 1 and an analog circuit part 2. The digital circuit part 1 includes: a BEMF detection module 11, a driving voltage control module 12, a playback control module 13, an F0 detection module 14, a driving waveform direct digital frequency synthesizer 15, and a PWM modulator 16. The analog circuit part 2 includes: a driving circuit 21, a voltage detection ADC 22, and a current detection ADC 23.

[0094] Specifically, the BEMF detection module 11 is used to collect the measured value of the second back electromotive force at both ends of the linear resonant motor 3; the driving voltage control module 12 is used to perform back electromotive force consistency calibration on the linear resonant motor 3 and record the forward gain calibration value G ol，final and the back electromotive force feedback gain calibration value G bemf，final ; using the back electromotive force feedback gain calibration value G bemf，final , the measured value of the second back electromotive force is normalized to the target value to obtain a second normalized back electromotive force signal; the playback control module 13 is used to parse the vibration effect instruction from the vibration enable signal through a preset rule, and adjust and output an over-drive signal and a braking signal according to the amplitude input signal and the second normalized back electromotive force signal; the driving voltage control module 12 is further used to amplify the normalized error signal according to the over-drive signal and the braking signal to adjust the amplitude of the driving voltage waveform, obtaining a first driving voltage waveform amplitude adjustment signal; using the forward gain calibration value G ol，final to adjust the first driving voltage waveform amplitude adjustment signal to obtain a second driving voltage waveform amplitude adjustment signal; the F0 detection module 14 is used to detect the back electromotive force frequency using the measured value of the second back electromotive force, and calculate the frequency of the driving waveform according to the error between the back electromotive force frequency and the preset natural frequency value; the driving waveform direct digital frequency synthesizer 15 is used to obtain a driving waveform DDS output signal according to the calculated frequency of the driving waveform and using the second driving voltage waveform amplitude adjustment signal as the amplitude of the driving waveform; and the PWM modulator 16 is used to generate two PWM signals using the driving waveform DDS output signal and drive the linear resonant motor 3 through the driving circuit.

[0095] Further, a voltage detection ADC 22 is configured to detect a first voltage signal V1 / second voltage signal V2 across the linear resonant motor 3; a current detection ADC 23 is configured to detect a first current signal I1 / second current signal I2 flowing through the port of the linear resonant motor 3; the BEMF detection module 11 calculates a first measured back electromotive force value / second measured back electromotive force value by using the first voltage signal V1 / second voltage signal V2, the first current signal I1 / second current signal I2, and a preset coil resistance parameter R.

[0096] Compared with the prior art, a linear resonant motor control system provided by an embodiment of the present application amplifies an error signal after normalizing a back electromotive force signal to adjust the amplitude of a driving voltage waveform during the automatic over-driving and automatic braking phases of an LRA driving chip. During the acceleration phase, if the LRA oscillator speed is too low, the error of the normalized back electromotive force signal is greater than zero, and the driving voltage control module provides a driving voltage waveform higher than the rated voltage for over-driving. If the LRA oscillator speed is too high, the error of the normalized back electromotive force signal is less than zero, and the driving voltage control module provides a driving waveform lower than the rated voltage for driving. During the braking phase, if the LRA oscillator speed is too high, the error of the normalized back electromotive force signal is less than zero, and the amplitude of the reverse braking driving voltage waveform is increased. If the LRA oscillator speed is lower than a preset threshold, the error of the normalized back electromotive force signal is less than a preset threshold, and the playback of the braking driving voltage waveform is stopped in advance to avoid aftershocks caused by excessive braking. The control module uses the normalized error signal of the back electromotive force signal as an input, thereby improving the problem that the closed-loop oscillator speed value deviates from the designed speed due to inconsistent BL coefficients.

[0097] Corresponding to the above-disclosed linear resonant motor control system, an embodiment of the present invention also discloses a linear resonant motor control method. The following details the linear resonant motor control method disclosed in the embodiment of the present invention in conjunction with the above-described linear resonant motor control system.

[0098] As Figure 2 shown, an embodiment of the present application provides a linear resonant motor control method, which specifically includes the following steps.

[0099] The BEMF detection module 11 collects a second measured back electromotive force value across the linear resonant motor 3. The BEMF detection module 11 receives the output voltage signal V and current signal I of the voltage detection ADC 22 and the current detection ADC 23 respectively, and uses the preset LRA coil resistance parameter R to calculate the BEMF signal (i.e., the measured back electromotive force value) through the following calculation: V BEMF1 = V - IR.

[0100] Specifically, the measured values of the second back electromotive force at both ends of the linear resonant motor are collected according to a preset period, which specifically includes: the voltage detection ADC 22 detects the second voltage signal V2 at both ends of the linear resonant motor 3; the current detection ADC 23 detects the second current signal I2 flowing through the ports of the linear resonant motor 3; the BEMF detection module 11 calculates the measured value of the second back electromotive force by using the second voltage signal V2, the second current signal I2, and the preset coil resistance parameter R; the calculation formula for the measured value of the second back electromotive force is:

[0101] V BEMF2 = V2 - I2R

[0102] where V BEMF2 is the measured value of the second back electromotive force.

[0103] Specifically referring to Figure 3 , the drive voltage control module 12 consists of an adder 121, a subtractor 122, an amplifier with a gain of Gb emf (i.e., the back electromotive force feedback gain amplifier 123), an amplifier with a gain of G cl (i.e., the closed-loop control gain amplifier 124), and an amplifier with a gain of G ol (i.e., the forward gain amplifier 125). The connection relationship is as Figure 3 shown. The adder 121 and the subtractor 122 are both externally connected to the amplitude input signal input terminal; the input terminal of the back electromotive force feedback gain amplifier 123 is connected to the output terminal of the BEMF detection module 11, and the output terminal of the back electromotive force feedback gain amplifier 123 is connected to the playback control module 13 and the adder 121; the output terminal of the subtractor 122 is connected to the input terminal of the closed-loop control gain amplifier 124. The input terminal of the closed-loop control gain amplifier 124 is also connected to the overdrive signal output terminal, the brake signal output terminal, and the calibration trigger signal receiving terminal of the playback control module 13. The output terminal of the closed-loop control gain amplifier 124 is connected to the input terminal of the forward gain amplifier 125. The input terminal of the forward gain amplifier 125 is also connected to the output terminal of the adder 121. The output terminal of the forward gain amplifier 125 is connected to the output terminal of the drive waveform direct digital frequency synthesizer 15.

[0104] In the embodiment of the present invention, G ol is the forward gain value of the forward gain amplifier 125, which is determined through a calibration program to compensate for the forward gain loss caused by factors such as the internal resistance of the power tube of the chip drive circuit, the parasitic resistance of the printed circuit board trace, the parasitic resistance of the flexible circuit board and the interface, and the distortion of the drive waveform. G bemfis the back electromotive force feedback gain value of the back electromotive force feedback gain amplifier 123. The drive voltage control module 12 amplifies and normalizes the measured BEMF value through the back electromotive force feedback gain amplifier 123 and uses it to compare with the input amplitude. Its value can also be determined through a calibration program, which is used to eliminate the inconsistency of the BEMF signal amplitude caused by the differences in the BL values of different motors.

[0105] In the embodiment of the present invention, the drive voltage control module 12 performs back electromotive force consistency calibration on the linear resonant motor 3 and records the forward gain calibration value G ol，final and the back electromotive force feedback gain calibration value G bemf，final . Among them, performing back electromotive force consistency calibration on the linear resonant motor 3 specifically includes: the host computer directly sends a calibration trigger signal to the drive voltage control module 12, and the drive voltage control module 12 detects whether the calibration trigger signal is high; if the drive voltage control module 12 detects that the calibration trigger signal is high, then the drive voltage control module 12 detects that it has received the calibration trigger signal from the host computer, sets the closed-loop control gain value G cl to 0, sets the forward gain value G ol to 1, and drives the LRA linear resonant motor 3 with the periodic waveform of the full input amplitude (100%) corresponding to the rated voltage V rated provided by the manufacturer; detects the voltage amplitude V LRA of the periodic waveform at both ends of the linear resonant motor 3 through the voltage detection ADC 22 (here, the amplitudes of V rated and V LRA can be either the RMS value or the peak-to-peak value); sets the closed-loop control gain value G cl to 0, sets the forward gain value G ol to the first ratio of the rated voltage V rated to the voltage amplitude V LRA , and drives the linear resonant motor 3 with the full input amplitude (100%) for a preset duration to make the drive waveform reach a stable vibration amplitude. The preset duration should be designed long enough to ensure that the LRA amplitude can reach a stable vibration amplitude under the drive waveform of this preset duration; collects the first measured back electromotive force value at both ends of the linear resonant motor 3 through the BEMF detection module 11. Specifically, the voltage detection ADC 22 detects the voltage signal at both ends of the linear resonant motor 3 at this time, denoted as the first voltage signal V1; the current detection ADC 23 detects the current signal flowing through the port of the linear resonant motor 3 at this time, denoted as the first current signal I1; the BEMF detection module 11 calculates the first measured back electromotive force value using the first voltage signal V1, the first current signal I1, and the preset coil resistance parameter R; uses the back electromotive force feedback gain value G bemf, the first measured back electromotive force value is normalized to a target value to obtain a first normalized back electromotive force signal; adjust the back electromotive force feedback gain value G bemf， to make the peak value of the first normalized back electromotive force signal close to 1, and the back electromotive force feedback gain value G bemf at this time is the back electromotive force feedback gain calibration value G bemf，final , the rated voltage V rated and the voltage amplitude V LRA of the first ratio is the forward gain calibration value G ol，final .

[0106] The drive voltage control module 12 uses the back electromotive force feedback gain calibration value G bemf，final to normalize the second measured back electromotive force value to a target value to obtain a second normalized back electromotive force signal.

[0107] The playback control module 13 analyzes the vibration effect instruction from the vibration enable signal through a preset rule, and adjusts and outputs an over-drive signal and a brake signal according to the amplitude input signal and the second normalized back electromotive force signal.

[0108] Specifically, on the one hand, the playback control module 13 detects the vibration enable signal and the amplitude input signal sent by the host computer, and on the other hand, receives the second normalized back electromotive force signal output by the drive voltage control module 12. Analyze the vibration effect instruction from the vibration enable signal through a preset rule, and adjust and output an over-drive signal and a brake signal according to the amplitude input signal and the second normalized back electromotive force signal, which specifically includes: the playback control module 13 first sets the initial value of the over-drive signal and the initial value of the brake signal to low; the playback control module 13 detects that the vibration enable signal sent by the host computer becomes valid; if the vibration enable signal becomes valid, start reading the amplitude input signal and the second normalized back electromotive force signal; calculate the second ratio of the current second normalized back electromotive force signal to the current amplitude input signal; detect whether the current amplitude input signal is greater than a preset amplitude threshold (such as 50%); if the current amplitude input signal is greater than the preset amplitude threshold, determine whether the second ratio is less than a first preset ratio threshold (such as 70%); if the second ratio is less than the first preset ratio threshold, pull up the over-drive signal; if the second ratio is greater than or equal to the first preset ratio threshold, pull down the over-drive signal; if the current amplitude input signal is not greater than the first preset amplitude threshold, determine whether the current amplitude input signal is zero; if the current amplitude input signal is zero, determine whether the second ratio is less than a second preset ratio threshold (such as 10%); if the second ratio is not less than the second preset ratio threshold, pull up the brake signal; if the second ratio is less than the second preset ratio threshold, pull down the brake signal.

[0109] The driving voltage control module 12 amplifies the normalized error signal according to the over-drive signal and the brake signal to adjust the amplitude of the driving voltage waveform, and obtains a first driving voltage waveform amplitude adjustment signal.

[0110] Further, according to the over-drive signal and the brake signal, amplifying the normalized error signal to adjust the amplitude of the driving voltage waveform to obtain a first driving voltage waveform amplitude adjustment signal, which specifically includes: the subtractor 122 uses the amplitude input signal and the second normalized back electromotive force signal to obtain a normalized oscillator speed error; the closed-loop control gain amplifier 124 obtains a closed-loop control gain preset value according to the high and low conditions of the over-drive signal and the brake signal; the closed-loop control gain amplifier 124 multiplies the normalized oscillator speed error by the closed-loop control gain preset value to obtain a closed-loop control gain output value.

[0111] In the embodiment of the present invention, G cl is the closed-loop control gain value of the closed-loop control gain amplifier 124. The amplitude input signal and the feedback normalized BEMF signal are subtracted by the subtractor to obtain a normalized oscillator speed error, and this error is amplified during the automatic over-drive and automatic braking processes to adjust the output amplitude. The larger G cl is, the better the amplitude tracking performance is, but the stability becomes worse.

[0112] According to the above description of obtaining the closed-loop control gain output value, the G cl value is determined by the over-drive signal and the brake signal. Further, the closed-loop control gain amplifier 124 obtains a closed-loop control gain preset value according to the high and low conditions of the over-drive signal and the brake signal, which specifically includes: the closed-loop control gain amplifier 124 detects whether the over-drive signal is high; if the over-drive signal is high, the closed-loop control gain preset value is set to a first preset value (for example, the first preset value is 10); detects whether the brake signal is high; if the brake signal is high, the closed-loop control gain preset value is set to a second preset value (for example, the first preset value is 5); if both the over-drive signal and the brake signal are low, the closed-loop control gain preset value is set to zero.

[0113] The forward gain amplifier 125 adjusts the first driving voltage waveform amplitude adjustment signal by using the forward gain calibration value G ol，final to obtain a second driving voltage waveform amplitude adjustment signal.

[0114] The F0 detection module 14 detects the back electromotive force frequency using the measured value of the second back electromotive force, and calculates the frequency of the drive waveform based on the error between the back electromotive force frequency and the preset natural frequency value. Specifically, it includes: comparing the magnitudes of the back electromotive force frequency and the preset natural frequency value; if the back electromotive force frequency is lower than the preset natural frequency value, increasing the frequency of the drive waveform; if the back electromotive force frequency is higher than the preset natural frequency value, decreasing the frequency of the drive waveform.

[0115] The direct digital frequency synthesizer 15 of the drive waveform obtains the DDS output signal of the drive waveform according to the calculated frequency of the drive waveform and uses the second drive voltage waveform amplitude adjustment signal as the amplitude of the drive waveform. The direct digital frequency synthesizer 15 of the drive waveform (Direct Digital Synthesizer, DDS) can generate a periodic signal with variable amplitude and frequency. The periodic signal generated by the direct digital frequency synthesizer 15 of the drive waveform can be any periodic signal stored in the internal memory of the DDS (including sine wave, square wave, trapezoidal wave, rounded square wave, etc.). According to the above description, in the embodiment of the present application, the DDS output signal of the drive waveform output by the direct digital frequency synthesizer 15 of the drive waveform is a periodic signal, the amplitude of which is determined by the amplitude output signal (the second drive voltage waveform amplitude adjustment signal) of the drive voltage control module 12. In addition, the frequency of this periodic signal is determined by the frequency output signal (the calculated frequency of the drive waveform) of the F0 detection module 14.

[0116] The PWM (Pulse width modulation) modulator 16 generates two PWM signals using the DDS output signal of the drive waveform, and drives the linear resonant motor 3 through the drive circuit.

[0117] Specifically, the above steps specifically include: The two PWM signals generated by the PWM modulator 16 include the PWMP signal and the PWMN signal; The PWM modulator 16 determines the polarity of the output signal of the driving waveform DDS; If the polarity of the output signal of the driving waveform DDS is positive, the PWMN signal is pulled low, the PWMP signal is inverted, and the absolute value of the output signal of the driving waveform DDS is converted into the duty cycle information of the PWMP signal; If the polarity of the output signal of the driving waveform DDS is negative, the PWMP signal is pulled low, the PWMN signal is inverted, and the absolute value of the output signal of the driving waveform DDS is converted into the duty cycle information of the PWMP signal; The driving circuit converts the high level of the PWMP signal into the on signal of the upper transistor of the output power transistor at the OUTP terminal and the off signal of the lower transistor of the output power transistor at the OUTP terminal; The driving circuit converts the low level of the PWMP signal into the on signal of the lower transistor of the output power transistor at the OUTP terminal and the off signal of the upper transistor of the output power transistor at the OUTP terminal; The driving circuit converts the high level of the PWMN signal into the on signal of the upper transistor of the output power transistor at the OUTN terminal and the off signal of the lower transistor of the output power transistor at the OUTN terminal; The driving circuit converts the low level of the PWMN signal into the on signal of the lower transistor of the output power transistor at the OUTN terminal and the off signal of the upper transistor of the output power transistor at the OUTN terminal.

[0118] A linear resonant motor control method provided by an embodiment of the present application drives the motor with a rated driving voltage during factory calibration or power-on calibration, and collects the measured value of the back electromotive force of the linear resonant motor under the rated driving voltage through the voltage detection ADC, the current detection ADC, and the BEMF detection module. By calibrating the back electromotive force feedback gain value G bemf and the forward gain value G ol , the measured value of the back electromotive force is normalized to the target value. Among a large number of motors, for a linear resonant motor with a high BL value, the calibrated back electromotive force feedback gain value G bemf is small; For a motor with a high BL value, the calibrated back electromotive force feedback gain value G bemf and the input control gain (forward gain value G ol ) are large. Thus, the problem that the measured value of the oscillator speed deviates from the actual speed caused by the inconsistency of the BL coefficient is improved.

[0119] Compared with the prior art, in the automatic over-driving and automatic braking stages of the LRA driving chip, for a linear resonant motor control method provided by an embodiment of the present application, the error signal after normalizing the back electromotive force signal is amplified and used to adjust the amplitude of the driving voltage waveform. In the acceleration stage, if the speed of the LRA oscillator is low, the error of the normalized back electromotive force signal is greater than zero, and the driving voltage control module provides a driving voltage waveform higher than the rated voltage for over-driving. If the speed of the LRA oscillator is high, the error of the normalized back electromotive force signal is less than zero, and the driving voltage control module provides a driving waveform lower than the rated voltage for driving. In the braking stage, if the speed of the LRA oscillator is high, the error of the normalized back electromotive force signal is less than zero, and the amplitude of the reverse braking driving voltage waveform is increased. If the speed of the LRA oscillator is lower than a preset threshold, the error of the normalized back electromotive force signal is less than a preset threshold, and the playback of the braking driving voltage waveform is stopped in advance to avoid aftershocks caused by excessive braking. The control module uses the normalized error signal of the back electromotive force signal as the input, thereby improving the problem that the closed-loop oscillator speed value deviates from the designed speed due to inconsistent BL coefficients.

[0120] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A linear resonant motor control method, characterized in that The method includes: Perform back electromotive force consistency calibration on the linear resonant motor and record the forward gain calibration value G ol,final and the back electromotive force feedback gain calibration value G bemf,final ; Collecting the measured value of the second back electromotive force at both ends of the linear resonant motor according to a preset period; Utilize the back electromotive force feedback gain calibration value G bemf,final , normalize the measured value of the second back electromotive force to the target value to obtain a second normalized back electromotive force signal; Analyzing the vibration effect instruction from the vibration enable signal through a preset rule, and adjusting and outputting an over-drive signal and a brake signal according to the amplitude input signal and the second normalized back electromotive force signal; According to the over-drive signal and the brake signal, amplifying the normalized error signal to adjust the amplitude of the driving voltage waveform, and obtaining a first driving voltage waveform amplitude adjustment signal; Using the forward gain calibration value G ol,final Adjust the amplitude adjustment signal of the first driving voltage waveform to obtain a second driving voltage waveform amplitude adjustment signal; Detecting the back electromotive force frequency by using the measured value of the second back electromotive force, calculating the frequency of the driving waveform according to the error between the back electromotive force frequency and a preset natural frequency value, and using the second driving voltage waveform amplitude adjustment signal as the amplitude of the driving waveform to obtain a driving waveform DDS output signal; and Generating two PWM signals by using the driving waveform DDS output signal, and driving the linear resonant motor through a driving circuit; According to the over-drive signal and the brake signal, amplifying the normalized error signal to adjust the amplitude of the driving voltage waveform, and obtaining a first driving voltage waveform amplitude adjustment signal, including: Obtaining a normalized oscillator speed error by using the amplitude input signal and the second normalized back electromotive force signal; Obtaining a preset value of the closed-loop control gain according to the high or low situation of the over-drive signal and the brake signal; Multiplying the normalized oscillator speed error by the preset value of the closed-loop control gain to obtain a closed-loop control gain output value.

2. The linear resonant motor control method according to claim 1, wherein, Performing back electromotive force consistency calibration on the linear resonant motor, including: Receiving a calibration trigger signal from the host computer and detecting whether the calibration trigger signal is high; If the calibration trigger signal is high, set the closed-loop control gain value G cl to 0, set the forward gain value G ol to 1, and drive the LRA, the linear resonant actuator, with the periodic waveform of the full input amplitude corresponding to the rated voltage V rated provided by the manufacturer; Detect the voltage amplitude V of the periodic waveforms at both ends of the linear resonant motor LRA ; Set the closed-loop control gain value G cl to 0, and set the forward gain value G ol to the first ratio of the rated voltage V rated to the voltage amplitude V LRA Drive the linear resonant motor with a full input amplitude for a preset duration so that the driving waveform reaches a stable vibration amplitude; Collecting the measured value of the first back electromotive force at both ends of the linear resonant motor; Utilize the back electromotive force feedback gain value G bemf , normalize the measured value of the first back electromotive force to a target value to obtain a first normalized back electromotive force signal; Adjust the back electromotive force feedback gain value G bemf , so that the peak value of the first normalized back electromotive force signal is close to 1. At this time, the back electromotive force feedback gain value G bemf is the back electromotive force feedback gain calibration value G bemf,final , the rated voltage V rated and the first ratio of the voltage amplitude V LRA is the forward gain calibration value G ol,final .

3. The linear resonant motor control method according to claim 2, wherein Collecting the measured value of the first back electromotive force at both ends of the linear resonant motor / the measured value of the second back electromotive force, including: Detecting the first voltage signal V1 / the second voltage signal V2 at both ends of the linear resonant motor; Detecting the first current signal I1 / the second current signal I2 flowing through the port of the linear resonant motor; Calculating the measured value of the first back electromotive force / the measured value of the second back electromotive force by using the first voltage signal V1 / the second voltage signal V2, the first current signal I1 / the second current signal I2, and a preset coil resistance parameter R; The calculation formula of the measured value of the first back electromotive force / the measured value of the second back electromotive force is: V BEMF1 = V1 - I1R V BEMF2 = V2 - I2R Among them, V BEMF1 is the measured value of the first back electromotive force, V BEMF2 is the measured value of the second back electromotive force.

4. The linear resonant motor control method according to claim 1, wherein Analyzing the vibration effect instruction from the vibration enable signal through a preset rule, and adjusting and outputting an over-drive signal and a brake signal according to the amplitude input signal and the second normalized back electromotive force signal, including: Setting the initial value of the over-drive signal and the initial value of the brake signal to low; Detecting whether the vibration enable signal sent by the host computer becomes valid; If the vibration enable signal becomes valid, start reading the amplitude input signal and the second normalized back electromotive force signal; Calculating the second ratio of the current second normalized back electromotive force signal to the current amplitude input signal; Detecting whether the current amplitude input signal is greater than a preset amplitude threshold; If the current amplitude input signal is greater than the preset amplitude threshold value, determine whether the second ratio is less than the first preset ratio threshold value; If the second ratio is less than the first preset ratio threshold value, raise the over-drive signal; If the second ratio is greater than or equal to the first preset ratio threshold value, lower the over-drive signal; If the current amplitude input signal is not greater than the first preset amplitude threshold value, determine whether the current amplitude input signal is zero; If the current amplitude input signal is zero, determine whether the second ratio is less than the second preset ratio threshold value; If the second ratio is not less than the second preset ratio threshold value, raise the brake signal; If the second ratio is less than the second preset ratio threshold value, lower the brake signal.

5. The linear resonant motor control method according to claim 1, characterized in that Obtain the preset value of the closed-loop control gain according to the high and low conditions of the over-drive signal and the brake signal, including: Detect whether the over-drive signal is high; If the over-drive signal is high, set the preset value of the closed-loop control gain to the first preset value; Detect whether the brake signal is high; If the brake signal is high, set the preset value of the closed-loop control gain to the second preset value; If both the over-drive signal and the brake signal are low, set the preset value of the closed-loop control gain to zero.

6. The linear resonant motor control method according to claim 4, wherein Detect the back electromotive force frequency by using the measured value of the second back electromotive force, and calculate the frequency of the driving waveform according to the error between the back electromotive force frequency and the preset natural frequency value, including: Compare the magnitudes of the back electromotive force frequency and the preset natural frequency value; If the back electromotive force frequency is lower than the preset natural frequency value, increase the frequency of the driving waveform; If the back electromotive force frequency is higher than the preset natural frequency value, decrease the frequency of the driving waveform.

7. The linear resonant motor control method according to claim 1, wherein Generate two PWM signals by using the driving waveform DDS output signal, and drive the linear resonant motor through a driving circuit, including: The two generated PWM signals include a PWMP signal and a PWMN signal; Judge the polarity of the driving waveform DDS output signal; If the polarity of the driving waveform DDS output signal is positive, lower the PWMN signal, invert the PWMP signal, and convert the absolute value of the driving waveform DDS output signal into the duty cycle information of the PWMP signal; If the polarity of the driving waveform DDS output signal is negative, lower the PWMP signal, invert the PWMN signal, and convert the absolute value of the driving waveform DDS output signal into the duty cycle information of the PWMP signal; Convert the high level of the PWMP signal into the upper tube turn-on signal of the output power tube at the OUTP end and the lower tube turn-off signal of the output power tube at the OUTP end by the driving circuit; Convert the low level of the PWMP signal into the lower tube turn-on signal of the output power tube at the OUTP end and the upper tube turn-off signal of the output power tube at the OUTP end by the driving circuit; Convert the high level of the PWMN signal into the upper tube turn-on signal of the output power tube at the OUTN end and the lower tube turn-off signal of the output power tube at the OUTN end by the driving circuit; The drive circuit converts the low level of the PWMN signal into the turn-on signal of the lower transistor of the output power transistor at the OUTN terminal and the turn-off signal of the upper transistor of the output power transistor at the OUTN terminal.

8. A linear resonant motor control system, characterized in that, The system includes: A digital circuit section, which includes: A BEMF detection module for collecting the measured value of the second back electromotive force across the linear resonant motor at a preset period; A drive voltage control module, which is used to calibrate the back electromotive force consistency of the linear resonant motor and record the forward gain calibration value G ol,final and the back electromotive force feedback gain calibration value G bemf,final ; By using the back electromotive force feedback gain calibration value G bemf,final , normalizing the measured value of the second back electromotive force to a target value to obtain a second normalized back electromotive force signal; A playback control module for parsing a vibration effect instruction from a vibration enable signal according to a preset rule, and adjusting and outputting an over-drive signal and a braking signal according to an amplitude input signal and the second normalized back electromotive force signal; The driving voltage control module is further configured to, according to the over-drive signal and the braking signal, amplify the normalized error signal to adjust the amplitude of the driving voltage waveform, so as to obtain a first driving voltage waveform amplitude adjustment signal; and use the forward gain calibration value G ol,final to adjust the first driving voltage waveform amplitude adjustment signal to obtain a second driving voltage waveform amplitude adjustment signal; An F0 detection module for detecting the back electromotive force frequency using the measured value of the second back electromotive force, and calculating the frequency of the drive waveform according to the error between the back electromotive force frequency and a preset natural frequency value; A direct digital frequency synthesizer for the drive waveform, which is used to obtain a DDS output signal of the drive waveform according to the calculated frequency of the drive waveform and using the second drive voltage waveform amplitude adjustment signal as the amplitude of the drive waveform; and A PWM modulator for generating two PWM signals using the DDS output signal of the drive waveform, and driving the linear resonant motor through a drive circuit; According to the over-drive signal and the braking signal, the amplified normalized error signal is used to adjust the amplitude of the drive voltage waveform to obtain a first drive voltage waveform amplitude adjustment signal, including: Obtaining a normalized oscillator speed error using the amplitude input signal and the second normalized back electromotive force signal; Obtaining a preset value of the closed-loop control gain according to the high or low conditions of the over-drive signal and the braking signal; Multiplying the normalized oscillator speed error by the preset value of the closed-loop control gain to obtain an output value of the closed-loop control gain.

9. The linear resonant motor control system according to claim 8, characterized in that The system further includes: An analog circuit section, the analog circuit section includes: a drive circuit, a voltage detection ADC, and a current detection ADC; The voltage detection ADC is used to detect the first voltage signal V1 / second voltage signal V2 across the linear resonant motor; the current detection ADC is used to detect the first current signal I1 / second current signal I2 flowing through the port of the linear resonant motor; the BEMF detection module calculates the measured value of the first back electromotive force / second back electromotive force using the first voltage signal V1 / second voltage signal V2, the first current signal I1 / second current signal I2, and a preset coil resistance parameter R; The two PWM signals generated by the PWM modulator include a PWMP signal and a PWMN signal; the PWM modulator is further used to judge the polarity of the DDS output signal of the drive waveform; if the polarity of the DDS output signal of the drive waveform is positive, the PWMN signal is pulled low, the PWMP signal is inverted, and the absolute value of the DDS output signal of the drive waveform is converted into the duty cycle information of the PWMP signal; if the polarity of the DDS output signal of the drive waveform is negative, the PWMP signal is pulled low, the PWMN signal is inverted, and the absolute value of the DDS output signal of the drive waveform is converted into the duty cycle information of the PWMP signal; The driving circuit is used to convert the high level of the PWMP signal into the turn-on signal of the upper transistor of the output power transistor at the OUTP terminal and the turn-off signal of the lower transistor of the output power transistor at the OUTP terminal; the driving circuit converts the low level of the PWMP signal into the turn-on signal of the lower transistor of the output power transistor at the OUTP terminal and the turn-off signal of the upper transistor of the output power transistor at the OUTP terminal; the driving circuit converts the high level of the PWMN signal into the turn-on signal of the upper transistor of the output power transistor at the OUTN terminal and the turn-off signal of the lower transistor of the output power transistor at the OUTN terminal; the driving circuit converts the low level of the PWMN signal into the turn-on signal of the lower transistor of the output power transistor at the OUTN terminal and the turn-off signal of the upper transistor of the output power transistor at the OUTN terminal.

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