CN-121971812-A - Multichannel transcranial focusing ultrasonic regulation and control system and method based on high-frequency precise control SPWM

CN121971812ACN 121971812 ACN121971812 ACN 121971812ACN-121971812-A

Abstract

The embodiment of the application provides a multichannel transcranial focusing ultrasonic regulation and control system and method based on high-frequency precise control SPWM. The system comprises a main control module, an ultrasonic driving module, a frequency tracking module, a power module and an ultrasonic transducer, wherein the main control module is used for SPWM signal generation, driving strategy switching and frequency tracking algorithm deployment, the ultrasonic driving module is used for receiving the SPWM signal output by the main control module, outputting a target sinusoidal driving signal to the ultrasonic transducer after amplification and filtering, and the frequency tracking module is used for realizing real-time detection and tracking of the actual resonant frequency of the transducer. The application reduces the hardware cost of multichannel driving, reduces the total harmonic distortion of driving signals, improves the frequency and phase control precision, realizes multichannel driving by a single MCU, is compatible with the regulation and control of cortex and deep brain regions, improves the energy utilization efficiency and ensures the stability of the treatment process.

Inventors

LIN JINCHAO
LIN XINJIE
PANG YU

Assignees

重庆邮电大学

Dates

Publication Date: 20260505
Application Date: 20260323

Claims (8)

1. A multichannel transcranial focusing ultrasonic regulation and control system based on high-frequency precise control SPWM is characterized by comprising a main control module, an ultrasonic driving module, a frequency tracking module, a power supply module and an ultrasonic transducer; The main control module is connected with the ultrasonic driving module and comprises a DMA controller and a timer, and the main control module is used for generating an SPWM signal; The ultrasonic driving module is used for receiving the SPWM signal output by the main control module, and amplifying and filtering the SPWM signal to obtain a target sinusoidal driving signal; The frequency tracking module comprises a phase discriminator and a PID control unit, the phase discriminator comprises an exclusive-OR gate and a D trigger, and the frequency tracking module is used for monitoring the resonant frequency of the ultrasonic transducer in real time and feeding back the resonant frequency of the ultrasonic transducer to the main control module; The power module comprises a low-dropout linear voltage regulator and a switch voltage-reducing circuit, wherein the low-dropout linear voltage regulator is used for reducing the input direct-current voltage to a first voltage value, the switch voltage-reducing circuit is used for reducing the input direct-current voltage to a second voltage value, and the first voltage value is smaller than the second voltage value.
2. The high-frequency precisely controlled SPWM-based multichannel transcranial focusing ultrasonic regulation and control system of claim 1 wherein the ultrasonic driving module comprises a grid driver, a half-bridge driving circuit and a filtering matching circuit; the grid driver is used for controlling the number of output sine waves; The half-bridge driving circuit is used for amplifying the voltage of the SPWM signal; The filtering and matching circuit comprises an LC low-pass filtering circuit and an impedance matching circuit, wherein the LC low-pass filtering circuit is used for filtering the SPWM signal amplified by the half-bridge driving circuit into a sine wave, and the impedance matching circuit is used for carrying out impedance matching with the ultrasonic transducer.
3. The multichannel transcranial focusing ultrasonic regulation and control method based on the high-frequency precise control SPWM is characterized by being applied to the multichannel transcranial focusing ultrasonic regulation and control system based on the high-frequency precise control SPWM, and comprises the following steps: generating a standard sine table according to the sampling points by Matlab, calculating a corresponding DMA controller table-lookup step length in a preset modulation wave frequency range by adopting an integer amplification method, and solidifying the standard sine table and the DMA controller table-lookup step length into a Flash memory of a main control module; calculating and generating an SPWM code table by utilizing Matlab according to a preset carrier frequency, a modulation wave frequency range, frequency steps and a timer clock, and solidifying the generated SPWM code table into a Flash memory of a main control module; Generating an SPWM signal based on a standard sine table and a DMA controller table lookup step length aiming at cortical brain region regulation, and generating an SPWM signal based on an SPWM code table aiming at deep brain region regulation; After the generated SPWM signal is processed by a grid driver, a half-bridge driving circuit and a filtering matching circuit, outputting a sinusoidal driving signal matched with an ultrasonic transducer; the voltage and loop current at two ends of the ultrasonic transducer are collected in real time, and the voltage signals and the current signals collected by the phase discriminator and the PID controller are used for processing, so that the real-time tracking of the resonant frequency of the ultrasonic transducer is realized.
4. A method according to claim 3, wherein said generating a standard sine table from the number of sampling points using Matlab comprises: determining sampling points according to hardware memory limitation, performing discrete sampling on a standard sine wave, and generating a discrete sine sequence containing a plurality of sampling points; Linearly mapping the amplitude range of the discrete sine sequence to the counting range of a singlechip timer to generate an integer normalization sequence; Applying direct current bias to the normalization sequence to enable the central point of the sine wave to correspond to 50% of duty ratio, and generating a biased sine code table; compiling the biased sine code table into a static array, and storing the static array into a Flash memory of a main control module.
5. The method of claim 4, wherein generating the SPWM signal for cortical brain region regulation based on a standard sine table and DMA controller table look-up step size comprises: Receiving an externally set target frequency and a target phase, and judging whether the target frequency is in a modulating wave frequency range; if yes, calculating a 64-bit table lookup step according to the target frequency and the fixed sampling frequency; Calculating initial index offset according to the target phase, and pointing a source address pointer of the DMA controller to an address corresponding to the phase offset value before starting DMA controller transmission; the timer generates an interrupt or trigger signal at a fixed sampling frequency, and drives the DMA controller to read a value corresponding to the current step length from the sine table; generating a triangular carrier wave in the timer, comparing the sine modulation wave read by the DMA controller with the triangular carrier wave in real time, outputting a high level by a PWM pin of the main control module if the sine value is larger than the triangular carrier wave value, and outputting a low level by the PWM pin of the main control module if the sine value is smaller than or equal to the triangular carrier wave value; and detecting the target frequency and the target phase in real time, and when detecting the new target frequency and the new target phase, recalculating the step length and resetting the pointer of the DMA controller.
6. A method according to claim 3, wherein generating the SPWM code table using Matlab calculation from a preset carrier frequency, modulation wave frequency range, frequency step and timer clock comprises: determining a carrier ratio according to a carrier frequency and a target frequency in a modulation wave frequency range; Determining pulse width time according to the carrier ratio and a preset carrier period; the pulse time is converted into the value of the timer comparison register according to the counting period of the timer.
7. The method of claim 6, wherein generating SPWM signals for deep brain region regulation based on SPWM code tables comprises: Receiving an externally set target frequency, judging whether the target frequency is in a modulation wave frequency range, if not, not updating or triggering error prompt, if so, calculating an index value according to the target frequency, and positioning to a pre-stored code table array head address through the index value; when switching the frequency, closing the output channel of the timer, updating the transmission source address of the DMA controller to be the newly calculated code table array head address, setting the transmission length of the DMA controller to be the carrier ratio parameter corresponding to the target frequency, restarting the output channel and re-enabling the timer; The timer triggers a flag bit signal according to a carrier period, and the DMA controller responds to the flag bit signal, reads a numerical value from a code table stored in Flash and writes the numerical value into a capture/comparison register of the timer; When the code table finishes one sine period, the DMA pointer is automatically reset to the array head address, and the DMA pointer is circularly output to generate a continuous sine modulation signal.
8. A method according to claim 3, wherein the processing of the voltage and current signals acquired with the phase detector and PID controller comprises: Inputting the collected voltage signal and current signal into an exclusive-OR gate for processing to obtain a signal representing the phase difference of the voltage signal and the current signal; Inputting the acquired voltage signal and current signal into a D trigger for processing to obtain signals representing the phase directions of the voltage signal and the current signal; Inputting a signal representing the phase difference of the voltage signal and the current signal into a PID control unit for processing, and determining the frequency adjustment direction; Signals representing the phase directions of the voltage signal and the current signal are input into a PID control unit for processing, and the frequency adjustment amplitude is determined.

Description

Multichannel transcranial focusing ultrasonic regulation and control system and method based on high-frequency precise control SPWM Technical Field The application relates to the technical field of ultrasonic treatment, in particular to a multichannel transcranial focusing ultrasonic regulation and control system and method based on high-frequency precise control SPWM. Background In the technical field of therapeutic ultrasound, the driving circuit is used as a core control unit of an ultrasonic transducer, and the performance of the driving circuit directly determines the frequency precision, amplitude stability, waveform purity and multi-channel cooperativity of ultrasonic output, so that the targeting, effectiveness and safety of scenes such as transcranial ultrasonic nerve regulation and control are affected. Currently, the mainstream design scheme of the therapeutic ultrasound driving circuit is generally composed of a signal generating module and a signal amplifying module, and the specific technical path is as follows: 1. the signal generation part generally adopts a direct digital synthesis (DIRECT DIGITAL SYNTHESIS, DDS) chip as a core device, and a microcontroller is used for configuring chip parameters to generate square wave signals with specific frequency so as to provide a basic frequency reference for a subsequent amplifying module; 2. And the signal amplifying part sends the square wave signal output by the DDS chip to the grid driver to drive the half-bridge driving circuit to amplify power, and then the high-order harmonic wave is filtered by the low-pass filter to obtain a sine wave signal to drive the ultrasonic transducer. Problems and disadvantages of the prior art: (1) The cost is high, the multipath expansion is difficult, a single DDS chip can only output one path of square wave signal, and the multichannel drive needs to configure an independent DDS chip for each channel, so that the superposition of hardware cost, the increase of volume and the improvement of wiring complexity are caused, and the miniaturization development of a multichannel system is hindered; (2) The wave distortion is large, the phase precision is low, a great amount of harmonic residues exist in the sine wave obtained by the square wave through half-bridge amplification and filtering, the total harmonic distortion (Total Harmonic Distortion, THD) is as high as 10-30%, uncontrollable phase delay is introduced in the filtering process, and the high requirement of the phased array ultrasonic probe on the phase precision cannot be met; The driving suitability is poor, the existing scheme does not design a differential driving strategy aiming at the requirements of different types of ultrasonic transducers (single focusing/phased arrays), and is difficult to be compatible with different control scenes of cortex and deep brain regions. Disclosure of Invention The application provides a multichannel transcranial focusing ultrasonic regulation and control system and method based on high-frequency precise control SPWM, which are used for solving the problems of high cost, difficult multipath expansion, large waveform distortion, low phase precision and poor driving suitability of the traditional transcranial focusing ultrasonic driving system. In a first aspect, the application provides a multichannel transcranial focusing ultrasonic regulation and control system based on high-frequency precise control SPWM, which comprises a main control module, an ultrasonic driving module, a frequency tracking module, a power supply module and an ultrasonic transducer; The main control module is connected with the ultrasonic driving module and comprises a DMA controller and a timer, and the main control module is used for generating an SPWM signal; The ultrasonic driving module is used for receiving the SPWM signal output by the main control module, and amplifying and filtering the SPWM signal to obtain a target sinusoidal driving signal; The frequency tracking module comprises a phase discriminator and a PID control unit, the phase discriminator comprises an exclusive-OR gate and a D trigger, and the frequency tracking module is used for monitoring the resonant frequency of the ultrasonic transducer in real time and feeding back the resonant frequency of the ultrasonic transducer to the main control module; The power module comprises a low-dropout linear voltage regulator and a switch voltage-reducing circuit, wherein the low-dropout linear voltage regulator is used for reducing the input direct-current voltage to a first voltage value, the switch voltage-reducing circuit is used for reducing the input direct-current voltage to a second voltage value, and the first voltage value is smaller than the second voltage value. Optionally, the ultrasonic driving module comprises a grid driver, a half-bridge driving circuit and a filtering matching circuit; the grid driver is used for controlling the number of output sine waves; The half-br