Driving method and system for frequency tracking of linear resonant motor

Abstract

The invention provides a driving method and system for frequency tracking of a linear resonant motor, and the method comprises the following steps: S1, controlling the linear resonant motor to drive a half period according to a preset time, detecting a back electromotive force signal generated in the motion process of the motor, recognizing the acceleration zero crossing point position based on the back electromotive force signal, and determining the frequency of the linear resonant motor according to the acceleration zero crossing point position; and starting the vibration timer to start timing. And S2, controlling the linear resonant motor to drive a half period according to double preset time, detecting a feature point of the counter electromotive force signal, and calculating actual vibration time of the half period according to the time position of the counter electromotive force feature point. And S3, judging whether the actual vibration time is within a preset frequency tracking range or not, if so, updating the preset time to the actual vibration time, and repeating the steps S2 to S3. According to the invention, real-time tracking and accurate control of the resonant frequency of the linear resonant motor are realized on the premise that normal vibration of the linear resonant motor is not affected through a half-cycle detection and dynamic adjustment technology.

Description

Technical Field

[0001] The present invention relates to the field of tactile feedback devices such as mobile phones and handles, and particularly to a driving method and system for linear resonant motor frequency tracking. Background Art

[0002] A linear resonant actuator (LRA) is a linear vibration motor based on the resonance principle and has a very wide range of applications in fields such as mobile phones, handles, and tactile feedback devices. Based on its working principle, the linear resonant motor has a specific resonant frequency f0, also called the resonance frequency. When the resonance frequency is used as the frequency of the LRA driving signal, the LRA can reach the best working state, that is, the state with the strongest vibration feeling. When the driving frequency deviates from the resonance frequency range by more than 2 Hz, the vibration feeling of the LRA will be greatly reduced. In applications, the resonance frequency of the LRA is often shifted due to the interference of many factors, such as the aging of internal components and the differences in the external environment. Most of the existing technologies first measure the resonance frequency of the LRA and then perform the driving. It is more cumbersome to perform relevant operations before each use. Summary of the Invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a driving method and system for linear resonant motor frequency tracking.

[0004] In order to achieve the above object, the present invention provides a driving method for linear resonant motor frequency tracking, which includes the following steps:

[0005] S1: Control the linear resonant motor to drive for half a cycle according to a preset time, detect the back electromotive force signal generated during the movement of the motor, identify the position of the acceleration zero crossing based on the back electromotive force signal, and start the vibration timer to start timing;

[0006] S2: Control the linear resonant motor to drive for half a cycle according to twice the preset time, detect the characteristic points of the back electromotive force signal, and calculate the actual vibration time of half a cycle according to the time position of the back electromotive force characteristic points;

[0007] S3: Determine whether the actual vibration time is within the preset frequency tracking range. If it is, update the preset time to the actual vibration time and repeat steps S2 - S3 to adjust the driving frequency of the linear resonant motor.

[0008] Preferably, when detecting the back electromotive force, it is determined whether the linear resonant motor is in a vibrating state by detecting the change in acceleration.

[0009] Preferably, in step 1, if the linear resonant motor is in a vibrating state, start the vibration timer to start timing; if the linear resonant motor is not in a vibrating state, repeat the process of driving and detecting the back electromotive force according to a preset time.

[0010] Preferably, in step 2, if the linear resonant motor is in a vibrating state, obtain the time of the current vibration timer and use it as the actual vibration time of the linear resonant motor for half a cycle; if the linear resonant motor is not in a vibrating state, return to step S1 to drive and track the driving frequency again.

[0011] Preferably, in step S3, if the actual vibration time is not within the frequency tracking range, repeat the process of step S1.

[0012] Preferably, the determination method of the frequency tracking range is: the product of the maximum count value and the minimum count value of the vibration timer and the system clock.

[0013] The present invention also provides a driving system for frequency tracking of a linear resonant motor, which includes:

[0014] A driving module, configured to generate a quasi-sine wave driving signal according to a preset time to drive the linear resonant motor to work for half a cycle;

[0015] A back electromotive force detection module, configured to detect the back electromotive force signal generated within half a cycle;

[0016] A frequency tracking module, which includes a control module and a vibration timer; the control module is configured to set a preset time and control the driving timing; the vibration timer is configured to determine the actual vibration time based on the characteristic points of the back electromotive force signal;

[0017] Wherein, the control module is configured to: compare the actual vibration time with the frequency tracking range; when the actual vibration time exceeds the frequency tracking range, iterate the driving and back electromotive force detection processes to determine the starting point of the next waveform and start re-tracking.

[0018] Preferably, the back electromotive force detection module detects the back electromotive force in a high impedance state.

[0019] Preferably, the driving system further includes:

[0020] A waveform timer, configured to record the time when each part of the driving waveform is output;

[0021] A clock module, configured to generate a fixed clock signal;

[0022] A protection module, configured to turn off the output when the driving module is abnormal;

[0023] An amplitude module, configured to adjust the amplitude according to the difference between the front and back of the back electromotive force.

[0024] A driving method and system for linear resonant motor frequency tracking provided by the present invention, compared with the prior art, its beneficial effects are as follows:

[0025] Through the half-cycle detection and dynamic adjustment technology, the present invention realizes the intelligent real-time tracking and precise control of the resonance frequency of the linear resonant motor without affecting the normal vibration performance of the linear resonant motor, and has outstanding advantages such as high control accuracy, fast response speed, and simple implementation. The specific manifestations are as follows:

[0026] 1. Real-time dynamic frequency matching: By controlling the linear resonant motor to work for half a vibration cycle within a preset time and detecting the back electromotive force signal generated within this half cycle, the actual vibration characteristic parameters of the motor are accurately obtained, realizing the real-time dynamic matching of the driving frequency and the mechanical resonance frequency, and ensuring that the motor always works in the optimal resonance state.

[0027] 2. Non-interfering frequency tracking: Only by using the back electromotive force signal generated during the normal operation of the motor can the real-time detection and tracking of the resonance frequency be completed, without adding additional detection circuits or interrupting the normal vibration process, realizing the seamless monitoring of the resonance frequency of the linear resonant motor (LRA).

[0028] 3. Vibration effect stability: The frequency adjustment process of the present invention is smooth and continuous. While realizing the real-time tracking of the resonance frequency, the overall vibration effect of the motor is completely unaffected, avoiding the problems of vibration interruption or amplitude fluctuation caused by frequency detection in the traditional method.

[0029] 4. System energy efficiency optimization: By continuously maintaining the motor to work at the best resonance point, the conversion efficiency of electrical energy to mechanical energy is significantly improved, the system power consumption is reduced, and the device battery life is extended.

[0030] 5. Strong environmental adaptability: It can automatically compensate for the resonance frequency drift caused by factors such as temperature change, mechanical aging, or load difference, ensuring that the motor can maintain stable vibration performance under various working conditions.

[0031] 6. Simplified implementation structure: The dedicated detection devices or complex control algorithms required in the traditional scheme are omitted, reducing the system complexity and implementation cost. Description of the Drawings

[0032] Figure 1 is a flowchart of a driving method for linear resonant motor frequency tracking provided by the present invention;

[0033] Figure 2 is a driving waveform diagram of a driving method for linear resonant motor frequency tracking provided by the present invention;

[0034] Figure 3System block diagram of a drive system for frequency tracking of a linear resonant motor provided by the present invention. Detailed implementation manners

[0035] The following uses specific specific examples to 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. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0036] Glossary: Preset time: A parameter stored in the system, which sets the driving time of the first waveform for the LRA and is set according to the different resonance frequencies of different LRAs. It can provide a better starting vibration state for the LRA. Driving half cycle: The driving waveform of the LRA for one cycle is two sine-wave-like waveforms, one positive and one negative, and half a cycle is one output waveform.

[0037] As Figure 1 shown, the present invention provides a driving method for frequency tracking of a linear resonant motor, which is characterized by including the following steps:

[0038] S1: Control the linear resonant motor to drive for half a cycle according to the preset time, detect the back electromotive force signal generated during the movement of the motor, identify the zero-crossing position of the acceleration based on the back electromotive force signal, and start the vibration timer to start timing;

[0039] S2: Control the linear resonant motor to drive for half a cycle according to twice the preset time, detect the characteristic points of the back electromotive force signal, and calculate the actual vibration time of half a cycle according to the time position of the back electromotive force characteristic points;

[0040] S3: Judge whether the actual vibration time is within the preset frequency tracking range. If it is, update the preset time to the actual vibration time and repeat steps S2 to S3 to adjust the driving frequency of the linear resonant motor.

[0041] Specifically, a half-cycle working mode is adopted to control the operation of the linear resonant motor, and the back electromotive force signal generated by the motor is detected in real time within a preset half cycle. Based on the analysis of the back electromotive force signal, the actual vibration time of the motor is obtained, and the driving waveform of the next working cycle is dynamically adjusted accordingly. Through a real-time feedback adjustment mechanism, the driving frequency automatically tracks the change of the mechanical resonance frequency of the motor, ensuring that the system always operates in the optimal resonance state. The present invention can complete the real-time detection and tracking of the resonance frequency only by using the back electromotive force signal during the normal operation of the motor, without the need for an additional detection circuit or interrupting the normal vibration process, realizing non-sensing frequency tracking. The entire frequency adjustment process of the present invention is smooth and continuous, without causing perceptible fluctuations in the vibration amplitude or phase jumps.

[0042] In the present invention, when detecting the back electromotive force, it is judged whether the linear resonant motor is in a vibrating state by detecting the change of acceleration.

[0043] Specifically, the present invention establishes a deterministic criterion for the vibration state by identifying the characteristic changes of the zero-crossing points of acceleration in the back electromotive force signal. Different from simple signal amplitude detection, this method can effectively distinguish real vibrations from abnormal states such as mechanical jamming. In addition, the zero-crossing point of acceleration corresponds to the extreme point of vibration displacement, providing an accurate time reference for the phase synchronization of the driving signal and ensuring the phase matching between the driving waveform and the mechanical vibration. The acceleration characteristics will show significant distortion in abnormal vibration modes. Therefore, by detecting the vibration state of the linear resonant motor, faults such as collision (peak acceleration exceeding the limit) and decoupling (acceleration signal disappearing) can be identified.

[0044] In step 1, if the linear resonant motor is in a vibrating state, start the vibration timer to start timing. If the linear resonant motor is not in a vibrating state, repeat the process of driving and detecting the back electromotive force according to the preset time.

[0045] Specifically, after detecting the vibration of the motor, obtain the zero-crossing point of acceleration. The starting point of the next driving waveform and the starting point of timing can be determined through the zero-crossing point of acceleration. By setting the preset time, it is possible to better find the starting point, avoiding slow startup when the preset time is too short and instability of the linear resonant motor when the time is too long.

[0046] In the present invention, in step 2, if the linear resonant motor is in a vibrating state, obtain the time of the current vibration timer and use it as the actual vibration time of the linear resonant motor for half a cycle. If the linear resonant motor is not in a vibrating state, return to step S1 to re-drive and track the driving frequency.

[0047] Specifically, this step is based on the output of step S1 for driving and back electromotive force detection, achieving dual driving and back electromotive force detection, making the detection results more accurate. The time position of the back electromotive force feature points (i.e., the zero-crossing points of acceleration) detected by the current step can more accurately reflect the actual vibration time of the linear resonant motor, improving the detection accuracy. Similarly, during the process of detecting the back electromotive force in this step, the optimal driving frequency of the linear resonant motor is adjusted in real time through a feedback mechanism, improving the accuracy of frequency tracking.

[0048] In step S3, if the actual vibration time is not within the frequency tracking range, the process of step S1 is repeated.

[0049] Specifically, in step S3, the time obtained by the vibration counter is used as the driving time for the next waveform to drive for half a cycle. After the driving waveform ends, the back electromotive force is monitored to obtain the vibration time of the current LRA for half a cycle, and it is continuously compared with the frequency tracking range. When the time obtained by the vibration counter is not within the tracking range, the system will return to step S1 to start driving and tracking again. If it is satisfied, step 3 will be repeated continuously to achieve real-time detection and adjustment of the vibration of the LRA.

[0050] In the present invention, the determination method of the frequency tracking range is: the product of the maximum count value and the minimum count value of the vibration timer and the system clock.

[0051] Figure 2 As shown, it is the waveform diagram of the quasi-sine wave for driving the linear resonant motor. Figure 2 It consists of three parts in total. T1 is the current rising section, where the current rises from 0 to the rated output current. T2 is the current holding section, where the current magnitude remains unchanged. T3 drops from the rated output current to 0. The present invention optimizes the quasi-sine wave driving timing of the linear resonant motor (LRA), divides the driving cycle into fixed-length T1 / T3 sections and dynamically adjustable T2 sections. Among them, the T2 section is the effective driving interval, and its length is dynamically adjusted by the preset time and the actual vibration time, but adjusting the duration of the T2 section will not change the output current (the vibration intensity is constant). By precisely controlling the driving time of the T2 section, the energy is more concentrated on the motor resonance stage, thereby improving the vibration efficiency and obtaining a stronger vibration effect under the same current. The durations of the T1 and T3 sections remain unchanged, providing a smooth current change and ensuring the stability of the system. This method achieves a higher energy efficiency vibration drive on the premise of hardware compatibility.

[0052] Based on the above driving method for linear resonant motor frequency tracking, the present invention also provides a driving system for linear resonant motor frequency tracking, which includes: a driving module, a back electromotive force detection module, and a frequency tracking module. The driving module is used to generate a quasi-sine wave driving signal according to a preset time to drive the linear resonant motor to work for half a cycle. The back electromotive force detection module is used to detect the back electromotive force signal generated within half a cycle. The frequency tracking module includes a control module and a vibration timer; the control module is used to set the preset time and control the driving timing; the vibration timer is used to determine the actual vibration time based on the characteristic points of the back electromotive force signal. Among them, the control module is configured to: compare the actual vibration time with the frequency tracking range; when the actual vibration time exceeds the frequency tracking range, iterate the driving and back electromotive force detection processes to determine the starting point of the next waveform and start re-tracking.

[0053] Among them, the back electromotive force detection module detects the back electromotive force in the high impedance state. The preset time includes the original preset time or the time of vibration timing. The back electromotive force detection module is preferably an H-bridge.

[0054] As Figure 3 shown, the driving system further includes:

[0055] A waveform timer for recording the output time of each part of the driving waveform. A clock module for generating a fixed clock signal, and the clock size is related to the frequency tracking range. A protection module that shuts down the output when the driving module is abnormal. That is, the output is shut down when it is detected that the current is too high or the temperature is too high. An amplitude module for adjusting the amplitude according to the difference before and after the back electromotive force so that it can reach the desired vibration intensity.

[0056] Among them, the amplitude module, the driving module, the waveform timer, and the frequency tracking module are combined into a total control module. The total control module is connected to the back electromotive force module, and two power drivers are respectively connected between the output section of the total control module and the back electromotive force module. Each power driver is formed by cascading two power triodes.

[0057] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all 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.

Claims

1. A driving method for frequency tracking of a linear resonant motor, characterized in that, It includes the following steps: S1: Control the linear resonant motor to drive for half a cycle according to a preset time, detect the back electromotive force signal generated during the motor movement, identify the acceleration zero-crossing position based on the back electromotive force signal, and start the vibration timer to start timing; S2: Control the linear resonant motor to drive for half a cycle according to twice the preset time, detect the characteristic points of the back electromotive force signal, and calculate the actual vibration time of half a cycle according to the time position of the back electromotive force characteristic points; S3: Judge whether the actual vibration time is within the preset frequency tracking range. If it is, update the preset time to the actual vibration time and repeat steps S2 - S3 to adjust the driving frequency of the linear resonant motor.

2. The driving method for linear resonant motor frequency tracking according to claim 1, wherein When detecting the back electromotive force, judge whether the linear resonant motor is in the vibration state by detecting the change in acceleration.

3. The driving method for linear resonant motor frequency tracking according to claim 2, characterized in that, In step 1, if the linear resonant motor is in the vibration state, start the vibration timer to start timing. If the linear resonant motor is not in the vibration state, repeat the process of driving and detecting the back electromotive force according to the preset time.

4. The driving method for frequency tracking of a linear resonant motor according to claim 2, wherein In step 2, if the linear resonant motor is in the vibration state, obtain the time of the current vibration timer and use it as the actual vibration time of half a cycle of the linear resonant motor. If the linear resonant motor is not in the vibration state, return to step S1 to re-drive and track the driving frequency.

5. The driving method for frequency tracking of a linear resonant motor according to claim 1, characterized in that In step S3, if the actual vibration time is not within the frequency tracking range, repeat the process of step S1.

6. The driving method for frequency tracking of a linear resonant motor according to claim 1, characterized in that, The determination method of the frequency tracking range is: the product of the maximum count value and the minimum count value of the vibration timer and the system clock.

7. A driving system for frequency tracking of a linear resonant motor, characterized in that, It includes: A driving module, used to generate a sine-wave-like driving signal according to the preset time to drive the linear resonant motor to work for half a cycle; A back electromotive force detection module, used to detect the back electromotive force signal generated within half a cycle; A frequency tracking module, which includes a control module and a vibration timer; the control module is used to set the preset time and control the driving timing; the vibration timer is used to determine the actual vibration time based on the characteristic points of the back electromotive force signal; Among them, the control module is configured to: compare the actual vibration time with the frequency tracking range; when the actual vibration time exceeds the frequency tracking range, iterate the driving and back electromotive force detection processes to determine the starting point of the next waveform and start re-tracking.

8. The drive system for linear resonant motor frequency tracking according to claim 7, characterized in that, The back electromotive force detection module detects the back electromotive force in the high impedance state.

9. The drive system for frequency tracking of a linear resonant motor according to claim 7, wherein, This driving system further includes: A waveform timer, used to record the output time of each part of the driving waveform; A clock module, used to generate a fixed clock signal; A protection module, which shuts down the output when the driving module is abnormal; An amplitude module, used to adjust the amplitude according to the difference before and after the back electromotive force.

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