Guqin string automatic tuning method
Patent Information
- Application Number
- CN202611119623.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-27
- Publication Date
- 2026-09-29
AI Technical Summary
[0003]本发明的目的在于克服现有技术的不足，提供一种古筝琴弦自动调音方法及装置，通过弦序自动匹配、间歇式脉冲离散闭环控制、标定式双维度分级停机判定，解决现有自动调音方案采样易受干扰、过调风险高、扭矩保护无依据、状态判定混淆的技术问题，实现高精度、高安全性、高自动化的古筝自动调音
1.本发明提出的一种古筝琴弦自动调音方法，采用间歇式脉冲离散闭环控制，实现停转采样、脉冲步进的调节逻辑，彻底隔离了电机电磁噪声与机械振动对音频采样的干扰，同时解决了琴弦振动衰减导致的采样精度下降问题；配合分级步长策略，既保证了调音速度，又有效避免了连续转动的惯性过调问题，调音精度稳定控制在±5音分以内，同时增设弦序自动识别与参数绑定机制，可自动匹配对应弦序的标准音高与专属扭矩安全阈值，无需人工手动选择目标琴弦，提升了自动化程度，避免了人工选错弦序导致的调音错误。
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Figure CN122842518A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of musical instrument tuning technology, and in particular to an automatic tuning method for guzheng strings. Background Technology
[0002] The guzheng is a traditional Chinese plucked string instrument. Its pitch directly affects the performance, and regular tuning is an essential part of its use and maintenance. However, current technology has several limitations. Firstly, traditional manual tuning wrenches rely heavily on the user's ear for sound and experience, making them difficult for beginners to operate, resulting in low precision and a risk of string breakage due to uncontrolled force. Secondly, existing automatic tuning solutions for stringed instruments generally suffer from the following technical defects: Firstly, during continuous motor adjustment, the electromagnetic noise and mechanical vibration of the motor will interfere with audio acquisition. Combined with the natural attenuation of string vibration, this leads to insufficient pitch sampling accuracy and is prone to over-adjustment or adjustment deviation. Secondly, it lacks an automatic string sequence recognition mechanism, requiring manual selection of the target string and corresponding pitch, resulting in low automation and easy tuning errors due to incorrect string sequence selection. Third, the torque protection threshold lacks scientific calibration basis. Setting only a uniform upper limit of torque cannot adapt to the tension differences of strings with different string orders. Either the protection is too early, resulting in improper tuning, or the threshold is too high, which cannot effectively prevent string breakage. Fourth, the common practice of directly equating torque exceeding the limit with tuning completion confuses the boundary between normal tuning and abnormal protection shutdown, which not only poses a safety hazard but also fails to provide feedback to the user on the abnormal status of the strings or tuning pins. Fifth, continuous rotation adjustment is prone to over-adjustment due to motor inertia, and reverse correction will reduce tuning efficiency, making it difficult to balance speed and precision. To address the aforementioned issues, the industry urgently needs an automatic tuning solution for the guzheng that features anti-interference discrete closed-loop control, automatic string sequence recognition, and calibrated torque protection. This solution would lower the tuning threshold while effectively improving tuning accuracy, operational stability, and safety. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an automatic tuning method and device for guzheng strings. By using automatic string sequence matching, intermittent pulse discrete closed-loop control, and calibrated two-dimensional hierarchical shutdown judgment, this invention solves the technical problems of existing automatic tuning schemes, such as sampling being easily interfered with, high risk of overtuning, lack of basis for torque protection, and confusion in state judgment. This invention achieves high-precision, high-safety, and highly automated automatic tuning of the guzheng.
[0004] To achieve the above objectives, the present invention provides an automatic tuning method for guzheng strings, specifically including the following steps: Step 1: Pre-tuning preparation and string sequence parameter matching; assemble the corresponding replaceable fitting according to the string pin specifications of the guzheng to be tuned, identify the string sequence number of the string to be tuned, retrieve the standard pitch value corresponding to the string sequence and the pre-calibrated torque tension safety threshold, and the device enters standby mode. Step 2: Static initial sampling and deviation calculation; The drive motor remains stationary, the string to be tuned is plucked to make it vibrate and produce sound, the audio acquisition module collects the audio signal of the string vibration and completes noise reduction preprocessing, the control motherboard analyzes to obtain the actual pitch value, compares it with the corresponding standard pitch value, and calculates the direction and amount of pitch deviation; Step 3: Intermittent pulse closed-loop adjustment; the control motherboard generates a single pulse rotation command based on the current pitch deviation, controls the drive motor to rotate the string shaft by the corresponding angle and then stops immediately; after the motor vibration subsides and the string vibration stabilizes, static audio sampling and deviation calculation are performed again; the discrete closed-loop process of pulse rotation, stopping sampling, and deviation calculation is repeated to gradually reduce the pitch deviation; Step 4: Two-dimensional graded shutdown judgment; After each round of sampling, the judgment is performed: If the actual pitch falls within the preset standard tolerance range, it is judged that the tuning is completed normally and the adjustment is terminated; If the driving torque reaches the pre-calibrated safety threshold of the corresponding string sequence, the protection shutdown is triggered immediately, it is judged as an abnormal state and a prompt message is output, and it is not considered as the tuning is completed. Step 5: Cyclic tuning of multiple strings; after tuning a single string, switch to the next string to be tuned, and repeat steps 1 to 4 until all strings are tuned.
[0005] Furthermore, in step 1, the string sequence identification adopts either the string position sensing identification method or the pitch matching identification method; the string position sensing identification method identifies the relative position of the tuning pegs through the photoelectric displacement sensor built into the device and matches the corresponding string sequence number; the pitch matching identification method determines the string sequence of the current string to be tuned by matching the pitch frequency range of the first sample with the pre-stored pitch intervals of each string sequence.
[0006] Furthermore, in step 3, the step size of the pulse rotation adopts a hierarchical adaptive strategy: when the pitch deviation is greater than 20 cents, a large step size pulse is used for coarse adjustment; when the pitch deviation is less than or equal to 20 cents, a small step size pulse is used for fine adjustment; after each round of pulse rotation, a stable delay of 100~300ms is set before audio sampling is started.
[0007] Furthermore, in the discrete closed-loop process of step 3, if the pitch deviation does not change significantly after three consecutive rounds of sampling, or if the deviation direction is opposite to the expected direction, it is determined that the tuning pin is stuck or the rotation is abnormal, and the machine is immediately stopped and an abnormal prompt is output.
[0008] Furthermore, the pre-calibrated torque tension safety threshold is obtained through pre-calibration: for each string sequence of different models of guzheng, a mapping relationship between the output torque of the drive motor and the actual tension of the string is established through calibration tests, and the torque value corresponding to the rated safe tension of the string is taken as the safety threshold of that string sequence and stored in the storage unit of the control motherboard.
[0009] Furthermore, in step 2, the sampling frequency of the audio acquisition module is not lower than 48kHz, and the noise reduction preprocessing includes filtering out environmental background noise, high-frequency harmonics and overtone components, and extracting the fundamental frequency signal of the strings; and the driving motor is in a power-off and stop state throughout the sampling process to isolate the electromagnetic noise and mechanical vibration interference of the motor.
[0010] Furthermore, in step 4, the standard tolerance range is ±5 cents of the standard pitch value; after the protection shutdown is triggered, the device will indicate the abnormality through sound and light signals, and record the current pitch value and torque value for the user to troubleshoot string or tuning pin faults.
[0011] An intelligent electric tuning device includes a housing, an audio acquisition module, a string sequence recognition module, a control motherboard, a drive motor, an output connecting shaft, a replaceable adapter sleeve, a torque acquisition module, and a status indication module. The audio acquisition module is embedded in the front end of the housing and is used to acquire audio signals of string vibration. The string sequence recognition module is used to identify the string sequence number of the string to be tuned. The control motherboard is fixed inside the casing and is electrically connected to the audio acquisition module, string sequence recognition module, drive motor, torque acquisition module, and status indication module. The control motherboard has a built-in storage unit, deviation calculation unit, intermittent closed-loop control unit, and stop determination unit. The storage unit is used to store the standard pitch value and torque tension calibration threshold corresponding to each string sequence. The intermittent closed-loop control unit is used to generate pulse rotation commands and execute discrete closed-loop logic for rotation, stop, and sampling. The drive motor is fixed to the front end of the housing, and its output end is fixedly connected to the output connecting shaft. The output connecting shaft is provided with a quick-locking slot at its end, and the replaceable adapter sleeve is detachably connected to the quick-locking slot via a snap-fit structure. The torque acquisition module is integrated into the output end of the drive motor and is used to acquire drive torque data in real time. The status prompt module is used to output prompts for tuning completion, protection shutdown, and abnormal status.
[0012] Furthermore, the string sequence recognition module is a photoelectric displacement sensor that matches the string sequence by detecting the relative position and spacing of the string axes; or the string sequence recognition module is integrated into the audio acquisition module and the control motherboard, and the string sequence recognition is achieved by matching the audio frequency range.
[0013] Furthermore, the replaceable adapter sleeve is available in various inner diameter specifications to accommodate guzheng tuning pegs of different diameters and shapes; the outer shell surface is provided with anti-slip texture and is made of temperature- and moisture-resistant engineering plastic material.
[0014] The present invention has the following beneficial effects: 1. This invention proposes an automatic tuning method for guzheng strings, employing intermittent pulse discrete closed-loop control to achieve stop-sampling and pulse stepping adjustment logic. This completely isolates the interference of motor electromagnetic noise and mechanical vibration on audio sampling, while solving the problem of decreased sampling accuracy caused by string vibration attenuation. Combined with a graded step size strategy, it ensures tuning speed while effectively avoiding the problem of inertial overtuning during continuous rotation. The tuning accuracy is stably controlled within ±5 cents. Furthermore, an automatic string sequence recognition and parameter binding mechanism is added, which can automatically match the standard pitch and exclusive torque safety threshold of the corresponding string sequence. This eliminates the need for manual selection of target strings, improving the degree of automation and avoiding tuning errors caused by manual selection of incorrect string sequences.
[0015] 2. This invention proposes an automatic tuning method for guzheng strings, establishing a calibrated torque and tension mapping relationship and setting exclusive safety thresholds for different string sequences. Compared to a scheme with a uniform torque upper limit, the protection accuracy is significantly improved, preventing incomplete tuning due to excessively low thresholds and avoiding the risk of string breakage due to excessively high thresholds. It also clearly distinguishes between normal tuning completion and abnormal protection shutdown states, avoiding user misjudgment and possessing comprehensive abnormal feedback capabilities. Furthermore, it comes with a replaceable adapter sleeve, adaptable to the tuning peg sizes of different guzheng models, eliminating the need for multiple tuning tools and reducing carrying and usage costs. The device adopts a built-in electric drive structure, combined with a non-slip shell, ensuring stable grip, effortless operation, and high reliability over long-term use. Attached Figure Description
[0016] Figure 1 This is a flowchart of the steps of an automatic tuning method for guzheng strings proposed in this invention; Figure 2 This is a functional structure diagram of an intelligent electric tuning device for an automatic tuning method of guzheng strings proposed in this invention. Detailed Implementation
[0017] The technical solutions of the specific embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described specific embodiments are only a part of the specific embodiments of the present invention, and not all of them. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Example 1: Reference Figure 1-2 The present invention provides a specific implementation method: an automatic tuning method for guzheng strings, based on an intelligent electric tuning device, the specific process of which is as follows: Step 1: Pre-tuning preparation and string sequence parameter matching; First, select a replaceable adapter sleeve of the corresponding specification according to the diameter and shape of the tuning peg of the guzheng to be tuned. Align the adapter sleeve with the quick-locking slot at the end of the output connection shaft and press to lock it in place. Then, hold the tuning device and fully attach the replaceable adapter sleeve to the corresponding tuning peg of the guzheng to be tuned, and press the power button on the device. After the device is started, the string sequence recognition module detects the distance between the current tuning peg and the adjacent tuning pegs through a photoelectric displacement sensor. Combined with the preset guzheng tuning peg arrangement parameters, it automatically identifies the string sequence number of the string to be tuned (such as string 1, string 5, etc.). The control motherboard retrieves the standard pitch value corresponding to the string sequence and the pre-calibrated string torque tension safety threshold from the storage unit. After the device completes initialization, it enters standby mode. This step features three commonly used interchangeable sleeves, covering the tuning peg sizes of mainstream guzheng on the market. The snap-on quick-release structure allows for disassembly and assembly in seconds, without the need for additional tools. Step 2: Static initial sampling and deviation calculation; The drive motor remains powered off and stopped. The user gently plucks the strings of the guzheng to be tuned, causing them to vibrate stably and produce sound. The audio acquisition module at the front of the device collects sound wave signals in real time at a sampling frequency of 48kHz and transmits the raw audio signals to the control motherboard. The control board first performs noise reduction filtering on the signal, using a digital filtering algorithm to remove low-frequency background noise, high-frequency harmonic interference, and overtone components of the string vibration, extracting the pure fundamental frequency signal of the string. Then, it uses Fast Fourier Transform (FFT) to analyze the fundamental frequency signal, calculates the actual frequency value of the string vibration, and converts it into the corresponding pitch value. The control board compares the actual pitch value obtained from the analysis with the standard pitch value corresponding to the current string sequence, and calculates the pitch deviation and direction: if the actual pitch is lower than the standard value, it is determined that the pitch is too low and the tuning peg needs to be tightened to raise the pitch; if the actual pitch is higher than the standard value, it is determined that the pitch is too high and the tuning peg needs to be loosened to lower the pitch. The motor remains stopped throughout this step, which fundamentally avoids interference from motor noise on the sampling and ensures the accuracy of the initial deviation calculation. Step 3: Intermittent pulse closed-loop regulation; The control motherboard generates single-pulse rotation commands based on the current pitch deviation using a graded adaptive strategy. When the pitch deviation is greater than 20 cents, a large step pulse command is generated to control the drive motor to rotate the corresponding angle at the rated speed for rapid coarse adjustment; When the pitch deviation is less than or equal to 20 cents, a small step pulse command is generated to control the drive motor to rotate at a low speed and a small angle for fine adjustment. After the drive motor completes a single pulse rotation, it immediately stops. The control board then initiates a 200ms stabilization delay to allow the motor's residual vibration to completely subside and the string vibration to return to a stable state. After the delay, the audio acquisition module is restarted for static sampling, and the deviation calculation process is repeated. The pitch deviation is gradually reduced in a step-by-step manner through a discrete closed-loop cycle of single-pulse rotation, stop delay, static sampling, and deviation calculation. During the adjustment process, if the change in pitch deviation is less than 2 cents after 3 consecutive rounds of sampling, or if the direction of deviation is opposite to the expected adjustment direction, it is determined that the tuning pin is stuck, the string is slipping, or there is an assembly abnormality. The machine is immediately forced to stop, and an abnormality is indicated by the red indicator light and buzzer output of the status prompt module to avoid unnecessary work or damage to the string. Step 4: Two-dimensional hierarchical shutdown determination; After each round of sampling and deviation calculation is completed, the shutdown decision unit of the control motherboard executes two levels of decision logic; Pitch standard determination: If the actual pitch of the string is detected to fall within the preset standard tolerance range (±5 cents), it is determined that the tuning is completed normally. The control motherboard sends a stop lock command to the drive motor, and at the same time, the status indicator module lights up a green indicator light to indicate to the user that the current string tuning is complete. Torque safety judgment: If the drive torque returned by the torque acquisition module reaches the pre-calibrated safety threshold corresponding to the current string sequence during the adjustment process, the drive motor will be forced to stop and lock immediately, regardless of whether the pitch is up to standard. The status indicator module will light up a red indicator light and emit a buzzer, which is judged as an abnormal protection state and is not considered as the tuning is complete. In this embodiment, the torque tension safety threshold is obtained through a pre-calibration test: for each string of a standard 21-string guzheng, the actual tension value of the string and the output torque value of the drive motor are collected synchronously on the tension testing platform to establish a one-to-one mapping relationship. The torque value corresponding to 90% of the rated safety tension of each string is taken as the exclusive safety threshold of that string sequence and pre-stored in the storage unit. The graded judgment mechanism ensures that the tuning accuracy meets the requirements of professional performance, precisely limits the maximum tension from a physical perspective, and clearly distinguishes between normal completion and abnormal protection status, fundamentally avoiding the logical error of tuning completion when the torque exceeds the limit. Step 5: Tune multiple strings in a loop; After tuning a single string, remove the replaceable adapter from the current tuning peg and attach it to the tuning peg of the next string to be tuned. The device will automatically recognize the new string sequence and retrieve the corresponding parameters, repeating steps 2 through 4 in sequence to complete the tuning of all strings. After all strings are tuned, turn off the device power, remove the adapter, and store it properly.
[0019] The following points should be noted in this article: 1. The accompanying drawings of the embodiments disclosed herein only relate to the structures involved in the embodiments disclosed herein; other structures can be referred to in general design.
[0020] 2. Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.
[0021] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing specific embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for automatically tuning guzheng strings, characterized in that: The method specifically includes the following steps: Step 1: Pre-tuning preparation and string sequence parameter matching; assemble the corresponding replaceable fitting according to the specifications of the tuning pegs of the guzheng to be tuned, identify the string sequence number of the string to be tuned, retrieve the standard pitch value corresponding to the string sequence and the pre-calibrated torque-tension safety threshold, and the device enters standby mode. Step 2: Static initial sampling and deviation calculation; The drive motor remains stationary, the string to be tuned is plucked to make it vibrate and produce sound, the audio acquisition module collects the audio signal of the string vibration and completes noise reduction preprocessing, the control motherboard analyzes to obtain the actual pitch value, compares it with the corresponding standard pitch value, and calculates the direction and amount of pitch deviation; Step 3: Intermittent pulse closed-loop adjustment; the control motherboard generates a single pulse rotation command based on the current pitch deviation, controls the drive motor to rotate the string shaft by the corresponding angle and then stops immediately; after the motor vibration subsides and the string vibration stabilizes, static audio sampling and deviation calculation are performed again; the discrete closed-loop process of pulse rotation, stopping sampling, and deviation calculation is repeated to gradually reduce the pitch deviation; Step 4: Two-dimensional graded shutdown judgment; After each round of sampling, the judgment is performed: If the actual pitch falls within the preset standard tolerance range, it is judged that the tuning is completed normally and the adjustment is terminated; If the driving torque reaches the pre-calibrated safety threshold of the corresponding string sequence, the protection shutdown is triggered immediately, it is judged as an abnormal state and a prompt message is output, and it is not considered as the tuning is completed. Step 5: Cyclic tuning of multiple strings; after tuning a single string, switch to the next string to be tuned, and repeat steps 1 to 4 until all strings are tuned.
2. The automatic tuning method for guzheng strings according to claim 1, characterized in that: In step 1, the string sequence identification adopts either the string position sensing identification method or the pitch matching identification method. The string position sensing identification method identifies the relative position of the tuning pegs by using the photoelectric displacement sensor built into the device and matching the corresponding string sequence number. The pitch matching identification method determines the string sequence of the current string to be tuned by matching the pitch frequency range of the first sample with the pre-stored pitch intervals of each string sequence.
3. The automatic tuning method for guzheng strings according to claim 1, characterized in that: In step 3, the step size of the pulse rotation adopts a graded adaptive strategy: when the pitch deviation is greater than 20 cents, a large step size pulse is used for coarse adjustment; when the pitch deviation is less than or equal to 20 cents, a small step size pulse is used for fine adjustment; after each round of pulse rotation, a stable delay of 100~300ms is set before audio sampling is started.
4. The automatic tuning method for guzheng strings according to claim 1, characterized in that: In the discrete closed-loop process of step 3, if the pitch deviation does not change significantly after three consecutive rounds of sampling, or if the deviation direction is opposite to the expected direction, it is determined that the tuning pin is stuck or the rotation is abnormal, and the machine is stopped immediately and an abnormal prompt is output.
5. The automatic tuning method for guzheng strings according to claim 1, characterized in that: The pre-calibrated torque tension safety threshold is obtained through pre-calibration: for each string sequence of different models of guzheng, a mapping relationship between the output torque of the drive motor and the actual tension of the string is established through calibration tests, and the torque value corresponding to the rated safe tension of the string is taken as the safety threshold of that string sequence and stored in the storage unit of the control motherboard.
6. The automatic tuning method for guzheng strings according to claim 1, characterized in that: In step 2, the sampling frequency of the audio acquisition module is not less than 48kHz. The noise reduction preprocessing includes filtering out environmental background noise, high-frequency harmonics and overtone components, and extracting the fundamental frequency signal of the strings. The motor is in a power-off and stop state throughout the sampling process to isolate the electromagnetic noise and mechanical vibration interference of the motor.
7. The automatic tuning method for guzheng strings according to claim 1, characterized in that: In step 4, the standard tolerance range is ±5 cents of the standard pitch value. After the protection shutdown is triggered, the device will indicate the abnormality through sound and light signals and record the current pitch value and torque value for the user to troubleshoot string or tuning pin faults.
8. An intelligent electric tuning device for implementing the automatic tuning method for guzheng strings as described in claim 1, characterized in that: It includes a housing, an audio acquisition module, a string sequence recognition module, a control motherboard, a drive motor, an output connecting shaft, a replaceable adapter sleeve, a torque acquisition module, and a status indication module. The audio acquisition module is embedded in the front end of the housing and is used to acquire the audio signal of the string vibration. The string sequence recognition module is used to identify the string sequence number of the string to be tuned. The control motherboard is fixed inside the casing and is electrically connected to the audio acquisition module, the chord sequence recognition module, the drive motor, the torque acquisition module, and the status prompt module, respectively. The control motherboard has a built-in storage unit, a deviation calculation unit, an intermittent closed-loop control unit, and a stop determination unit; the storage unit is used to store the standard pitch value and torque tension calibration threshold corresponding to each string sequence; the intermittent closed-loop control unit is used to generate pulse rotation commands and execute discrete closed-loop logic of rotation, stop, and sampling; The drive motor is fixed to the front end of the housing, and its output end is fixedly connected to the output connecting shaft. The output connecting shaft is provided with a quick-locking slot at its end, and the replaceable adapter sleeve is detachably connected to the quick-locking slot via a snap-fit structure. The torque acquisition module is integrated into the output end of the drive motor and is used to acquire drive torque data in real time. The status prompt module is used to output prompts for tuning completion, protection shutdown, and abnormal status.
9. The intelligent electric tuning device according to claim 8, characterized in that: The string sequence recognition module is a photoelectric displacement sensor that matches the string sequence by detecting the relative position and spacing of the string axes; or the string sequence recognition module is integrated into the audio acquisition module and the control motherboard, and achieves string sequence recognition by matching audio frequency ranges.
10. The intelligent electric tuning device according to claim 8, characterized in that: The replaceable adapter sleeve is available in various inner diameter specifications to accommodate guzheng tuning pegs of different diameters and shapes; the outer shell surface is textured with anti-slip material and is made of heat- and moisture-resistant engineering plastic.