CN113093647B - Method and device for identifying reverse gap based on response data of numerical control machine tool - Google Patents

Abstract

The invention discloses a method and device for identifying backlash based on response data of a numerically controlled machine tool, belonging to the technical field of numerical control, comprising: extracting a command speed signal _vc ( t), the current signal I(t), the encoder displacement signal p _e (t) and the encoder speed signal _ve (t), to obtain the time t ₀ at which the command speed crosses zero in the command speed signal, and the interval thereafter is The time t ₃ of the preset duration; the time delay e _i relative to the command speed signal in the encoder speed signal is eliminated to obtain the command speed signal v _c (t-e _i ), and according to e _v (t)=v _c (t‑e _i )‑v _e (t) calculate the speed difference e _v (t); calculate the speed difference e _v (t) _at the sudden change time _{t 1 and} the current signal I ( t) the sudden change time t ₂ in the time period t ₀ ~ t ₃ ; calculate the displacement increment generated by the encoder displacement signal p _e (t) in the time period t ₁ ~ t ₂ , and identify its absolute value as the backlash . The invention can improve the identification accuracy and realize the dynamic backlash identification for the semi-closed-loop control machine tool.

Description

Method and device for backlash identification based on response data of CNC machine tools

technical field

The invention belongs to the technical field of numerical control, and more particularly, relates to a method and a device for identifying backlash based on response data of a numerically controlled machine tool.

Background technique

The backlash of CNC machine tools is due to the existence of mechanical gaps from the head end of the machine tool kinematic chain to the actuator, resulting in the existence of the movement amount of the actuator and the theoretical value when the machine tool actuator changes from forward motion to reverse motion. The error is manifested in that the feed system has a large nonlinear following error when it is reversed, and there is a large cross-quadrant protrusion when executing the circle outline command, which reduces the machining accuracy of the machine tool, especially for high-precision machine tools. The existence of backlash limits the improvement of machine tool accuracy. Therefore, it is particularly important to accurately measure and compensate for backlash.

Backlash exists at the junction of mechanical parts, including the gap between the motor shaft and the gear shaft due to the key connection, the gap between the gear pair, the gap between the gear and the screw caused by the key connection, the gap caused by the key connection in the coupling, the wire Therefore, it cannot be directly measured. The traditional measurement method is to record the position difference at the same command position when the worktable is reversing movement, and most of them are measured by dial indicators, laser interferometers and grating rulers.

Dial indicator measurement is manual measurement, the measurement process is simple, but it requires the measurement personnel to operate the whole process, there is a large manual measurement error, and it is mostly used in occasions with large backlash.

Although the laser interferometer has higher measurement accuracy, it also has the disadvantages of manual measurement error and low degree of automation. At the same time, the above two measurement methods are both read when the feed axis is stationary, and the measured backlash is static, which cannot reflect the relationship between backlash and feed speed. The reference of the "Compensation of Backlash at Different Speeds" function is not significant.

At present, there is also a commonly used method to measure the backlash by using a grating ruler. The grating scale and the encoder on the machine tool record the difference between the grating scale data of the same encoder position before and after the reverse direction, as the backlash value of this point. This method avoids the influence of Abbe's error in the use of laser interferometer, and can measure the backlash of the whole machine tool.

In addition to the above-mentioned traditional measurement methods, there is also a method to identify the mechanical gap based on the current signal of the machine tool in the current research.

对该信号敏感段小波包分量重构后求方差作为丝杠磨损状态的预测。虽然该方法足够简洁的确定滚珠丝杠的磨损情况，但不同的机床中得到的“磨损量-特征量”曲线有所不同，不能定量的计算出反向间隙的磨损量大小。In the patent document with the application number CN2015105593135, titled "A method for predicting the wear state of a ball screw of a CNC machine tool", the method considers that the wear amount of the screw is the size of the backlash, and by collecting the three-phase current i of the CNC machine tool _u , i _v , i _w , calculate the root mean square value

After reconstruction of the wavelet packet components of the signal sensitive segment, the variance is calculated as the prediction of the wear state of the lead screw. Although this method is simple enough to determine the wear of the ball screw, the "wear amount-characteristic amount" curves obtained in different machine tools are different, and the wear amount of the backlash cannot be quantitatively calculated.

In the paper "Servo System Online Transmission Gap Identification and Its Negative Effect Suppression", the triangular wave speed signal is used to control the drive motor, and the gap amplitude is identified by calculating the integral of the speed difference between the time t1 when the gears are separated and the time t2 when they mesh again. . However, the torque current fluctuates and the speed is large, and there are many spikes after differentiation, which leads to inaccurate detection at t1 and t2.

In general, the existing backlash identification methods for CNC machine tools have the technical problems of low identification accuracy and inability to realize dynamic backlash identification for semi-closed-loop control machine tools.

SUMMARY OF THE INVENTION

In view of the defects and improvement requirements of the prior art, the present invention provides a method and device for backlash identification based on the response data of a numerically controlled machine tool, the purpose of which is to solve the identification accuracy of the existing backlash identification method of a numerically controlled machine tool. The technical problem of dynamic backlash identification for semi-closed-loop control machine tools cannot be realized.

In order to achieve the above object, according to one aspect of the present invention, a method for identifying backlash based on response data of a CNC machine tool is provided, including:

Extract the command speed signal v _c (t), the current signal I (t), the encoder displacement signal p _e (t) and the encoder speed signal v _e ( t), obtain the time t ₀ at which the command speed crosses zero in the command speed signal, and the time t ₃ after the time t ₀ and the interval of the preset time length t _last ;

After eliminating the time delay e _i relative to the command speed signal v _c (t) in the encoder speed signal v _e (t), the synchronized command speed signal v _c (te _i ) is obtained, and according to e _v (t )=v _c (te _i )-v _e (t) to calculate the speed difference e _v (t); respectively calculate the sudden change in time t ₁ and the current of the speed difference e _v (t) in the time period t ₀ to t ₃ the sudden change time t ₂ of the signal I(t) in the time period t ₀ to t ₃ ;

Calculate the displacement increment generated by the encoder displacement signal p _e (t) in the time period t ₁ to t ₂ , and identify its absolute value as the backlash.

In the actual operation of the machine tool, there will be obvious nonlinear following errors in the reverse motion. It is difficult to eliminate these following errors only by PID control. The main factors that cause the nonlinear following errors are the backlash and friction. Mechanical play exists between the lead screw and the nut, and the lead screw moves against the nut before the reverse process begins. The technical principle that the present invention carries out backlash identification is as follows:

(1) When the command speed is zero, the reverse process starts. Due to the hysteresis of the command response, the reverse time of the encoder is delayed to time t ₁ ;

(2) At time t ₁ , the encoder moves in the opposite direction. Due to the existence of backlash, the lead screw is separated from the nut at this time, and the lead screw is in a no-load state at this time, so the acceleration becomes larger, which is relative to the slowly changing command speed. , the speed of the encoder increases suddenly, so according to the sudden change of speed, it corresponds to the start time of the "gap period";

(3) After the encoder walks through the gap length, the "gap period" ends, and the lead screw and the nut are in contact again, but due to the large friction force at low speed, in order to overcome the friction force to drive the load movement, the current increases, so in the reverse The position where the rate of change of the current in the middle direction is the largest is t ₂ ;

(4) The absolute value of the displacement increment of the encoder in the time period t ₁ to t ₂ is the size of the backlash.

_The present invention can determine the reverse data segment, that _is , the time _{segment t 0} ~ t ₃ , by reasonably setting the value of the preset time length t _last , it can be ensured that the entire process of the occurrence of the backlash is included in the determined time period t ₀ to t ₃ . Therefore, the present invention utilizes the instruction data with less fluctuation The reverse data segment can be accurately found, and the specific time period in which the reverse gap occurs can be determined within the time period t ₀ to t ₃ , thereby narrowing the target range, effectively reducing the problem of inaccurate identification parameters, and improving the identification accuracy.

The invention only needs to extract the response data of the machine tool from the servo, and can complete the identification of the backlash without the aid of other measuring tools such as a grating ruler, and the extraction of the response data will not affect the normal operation of the CNC machine tool. Therefore, the invention can realize Dynamic backlash identification is realized for semi-closed-loop control machine tools without measuring equipment such as grating rulers.

further,

Among them, T represents the trajectory period of the CNC machine tool.

Experiments show that the duration of the backlash will not exceed 1/20 of the track period T. The present invention sets the duration of the backlash to 1/20 of the track period, so that the reverse data segment can be determined more accurately. At the same time, it can effectively speed up the identification speed.

Further, the criterion for the time t ₀ when the command speed crosses zero in the command speed signal is:

v _c (t ₀ )*v _c (t ₀ +1)<0;

Alternatively, _vc (t ₀ )* _vc (t ₀ +2)<0 and _vc (t ₀ +1)=0.

The above criterion can accurately determine the time t ₀ at which the command speed crosses zero in the command speed signal, that is, the start time of the reverse data segment, which is beneficial to accurately determine the reverse data segment.

Further, the calculation method of the sudden change time t ₂ of the current signal I(t) in the time period t ₀ to t ₃ is as follows:

The current signal I(t) is low-pass filtered and differentiated to obtain the signal dI _low (t);

Find the extreme value moment of the signal dI _low (t) in the time period t ₀ to t ₃ , that is, obtain the sudden change moment t ₂ of the current signal I(t) in the time period t ₀ to t ₃ .

Due to the interference of high-frequency signals such as vibration and electromagnetic interference when the machine tool is running, the directly collected current signal is relatively cluttered. Interference signal, accurately calculate the sudden change moment of the current signal, that is, the end moment of the backlash.

Further, the method for identifying the backlash based on the response data of the numerically controlled machine tool provided by the present invention further comprises: compensating the backlash obtained by the identification.

The invention compensates the recognized backlash on the machine tool that accurately recognizes the backlash, and can effectively improve the machining accuracy of the numerically controlled machine tool.

According to another aspect of the present invention, a backlash identification device based on response data of a numerically controlled machine tool is provided, comprising: a data extraction module, a reverse data segment marking module, a gap period identification module and a backlash identification module;

The data extraction module is used to extract the command speed signal v _c (t), the current signal I (t), the encoder displacement signal p _e (t) and the code generated on the target horizontal feed axis when the CNC machine tool executes the reverse command speed signal v _e (t);

The reverse data segment marking module is used to obtain the time t ₀ at which the command speed crosses zero in the command speed signal, and the time t ₃ after the time t ₀ which is separated by a preset time length t _last ;

The gap period identification module removes the time delay e _i relative to the command speed signal v _c (t) in the encoder speed signal v _e (t) to obtain the synchronized command speed signal v _c (te _i ), and Calculate the speed difference _{e v} (t) according to e _v (t)= _vc (te _i )-ve (t); the gap period identification module is also used to calculate the speed difference e _v (t) in the time period respectively the sudden change time t ₁ in the period t ₀ to t ₃ and the sudden change time t ₂ of the current signal I(t) in the time period t ₀ to t ₃ ;

The backlash identification module is used to calculate the displacement increment generated by the encoder displacement signal p _e (t) in the time period t ₁ to t ₂ , and identify its absolute value as the backlash.

The backlash identification device based on the response data of the numerically controlled machine tool provided by the present invention further comprises: a backlash compensation module;

The backlash compensation module is used to compensate the backlash identified by the backlash identification module.

According to another aspect of the present invention, a computer-readable storage medium is provided, including a stored computer program; when the computer program is executed by a processor, the device where the computer-readable storage medium is located is controlled to execute the CNC machine tool-based response data provided by the present invention backlash identification method.

In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

The backlash identification method and device based on the response data of the numerical control machine tool provided by the present invention firstly identifies the backlash data segment, the start time is the time of the command speed process, and the end time is the time after the start time after a preset time period ; Further, in the back gap data segment, identify the start time and end time of the "gap period", wherein the start time is the moment of sudden change of speed in the back gap data segment, and the end time is the moment of sudden change of the current signal; finally, The displacement increment of the encoder of the CNC machine tool is identified as the backlash between the start time and the end time of the "gap period". In this way, based on the technical principle that the response data of the machine tool in each control cycle is closely related to the state of the machine tool during the machining control process of the numerical control system, combined with the specific principle of the backlash generation, the identification of the backlash can be completed, and the backlash can be identified. Improve the identification accuracy; because the present invention only needs to extract the response data of the machine tool from the servo, and can complete the identification of the backlash without the aid of other measuring tools such as a grating ruler, and will not affect the normal operation of the CNC machine tool. Therefore, the present invention can Realize dynamic backlash identification for semi-closed-loop control machine tools without measuring equipment such as grating rulers.

Description of drawings

1 is a flowchart of a method for identifying backlash based on response data of a numerically controlled machine tool provided by an embodiment of the present invention;

2 is a schematic diagram of the mechanical feed structure of the existing Baoji machine tool;

Fig. 3 is the control block diagram of the existing Baoji machine tool;

FIG. 4 is a schematic diagram of backlash calculation according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

In the present invention, the terms "first", "second" and the like (if present) in the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

In order to solve the technical problems that the existing method for backlash identification of CNC machine tools is not high in accuracy and cannot realize dynamic backlash identification for semi-closed-loop control machine tools, the present invention provides a backlash identification based on response data of CNC machine tools. The method and device, the overall idea of which is as follows: directly using the response data of the numerical control machine tool for identification, firstly identifying the backlash data segment, the start time of which is the time of the command speed process, and the end time of which is the preset time after the start time. time; further in the back gap data segment, identify the start time and end time of the "gap period", wherein the start time is the moment of sudden change of speed in the back gap data segment, and the end time is the time of sudden change of current signal; finally , identify the displacement increment of the encoder of the CNC machine tool as the reverse gap between the start and end moments of the "gap period"; thus improve the identification accuracy of the reverse gap, avoid relying on other measuring tools such as grating rulers, and also Avoid affecting the normal operation of the CNC machine tool, so as to realize the dynamic backlash identification for the semi-closed-loop control machine tool.

The following are examples.

Example 1:

A backlash identification method based on response data of CNC machine tools, as shown in Figure 1, includes:

Extract the command speed signal v _c (t), the current signal I (t), the encoder displacement signal p _e (t) and the encoder speed signal v _e ( t), obtain the time t ₀ when the command speed crosses zero in the command speed signal, and the time t ₃ after the time t ₀ and the interval t _last by the preset time; Command pulse signal with opposite movement direction; in practical application, the target horizontal feed axis can be horizontal feed x-axis or horizontal feed y-axis, and the backlash identification method in the direction of each horizontal feed axis is the same, without loss of generality Naturally, in this embodiment, the target horizontal feed axis is specifically the horizontal feed x-axis; in each feed direction of the CNC machine tool, there are matching encoders and sensors. When backlash identification is performed for the axis, the response data are collected from the encoder and sensor in the corresponding feed direction;

After eliminating the time delay e _i relative to the command speed signal v _c (t) in the encoder speed signal v _e (t), the synchronized command speed signal v _c (te _i ) is obtained, and according to e _v (t )=v _c (te _i )-v _e (t) to calculate the speed difference e _v (t); respectively calculate the sudden change in time t ₁ and the current of the speed difference e _v (t) in the time period t ₀ to t ₃ the sudden change time t ₂ of the signal I(t) in the time period t ₀ to t ₃ ;

Calculate the displacement increment generated by the encoder displacement signal p _e (t) in the time period t ₁ ~ t ₂ , and identify its absolute value as the backlash;

In the actual operation of the machine tool, there will be obvious nonlinear following errors in the reverse motion. It is difficult to eliminate these following errors only by PID control. The main factors that cause the nonlinear following errors are the backlash and friction. Mechanical play exists between the lead screw and the nut, and the lead screw moves against the nut before the reverse process begins. The technical principle that the present invention carries out backlash identification is as follows:

(1) When the command speed is zero, the reverse process starts. Due to the hysteresis of the command response, the reverse time of the encoder is delayed to time t ₁ ;

(2) At time t ₁ , the encoder moves in the opposite direction. Due to the existence of backlash, the lead screw is separated from the nut at this time, and the lead screw is in a no-load state at this time, so the acceleration becomes larger, which is relative to the slowly changing command speed. , the speed of the encoder increases suddenly, so according to the sudden change of speed, it corresponds to the start time of the "gap period";

(3) After the encoder walks through the gap length, the "gap period" ends, and the lead screw and the nut are in contact again, but due to the large friction force at low speed, in order to overcome the friction force to drive the load movement, the current increases, so in the reverse The position where the rate of change of the current in the middle direction is the largest is t ₂ ;

(4) The absolute value of the displacement increment of the encoder in the time period t ₁ to t ₂ is the size of the backlash.

_The present invention can determine the reverse data segment, that _is , the time _{segment t 0} ~ t ₃ , by reasonably setting the value of the preset duration t _last , it can be ensured that the entire process of backlash occurrence is included in the determined time period t ₀ to t ₃ . In practical applications,

In this embodiment,

Among them, T represents the trajectory period of the CNC machine tool.

Experiments show that the duration of the backlash will not exceed 1/20 of the track period T. The utility model sets the duration of the backlash to 1/20 of the track period, which can more accurately determine the reverse data segment. While ensuring the identification accuracy, it can effectively speed up the identification speed; it should be noted that this is only an optional implementation of the present invention, and should not be construed as the only limitation of the present invention. In practical applications, for the actual numerical control The machine tool can also directly set the value of t _last when the duration of its backlash is known.

As an optional implementation manner, in this embodiment, the criterion for the time t ₀ when the commanded speed crosses zero in the commanded speed signal is:

v _c (t ₀ )*v _c (t ₀ +1)<0;

Alternatively, _vc (t ₀ )* _vc (t ₀ +2)<0 and _vc (t ₀ +1)=0.

The above criterion can accurately determine the time t ₀ at which the command speed crosses zero in the command speed signal, that is, the start time of the reverse data segment, which is beneficial to accurately determine the reverse data segment.

As an optional implementation manner, in this embodiment, the calculation method of the sudden change time t ₂ of the current signal I(t) in the time period t ₀ to t ₃ is as follows:

The current signal I(t) is low-pass filtered and differentiated to obtain the signal dI _low (t);

Find the extreme value moment of the signal dI _low (t) in the time period t ₀ to t ₃ , that is, obtain the sudden change moment t ₂ of the current signal I(t) in the time period t ₀ to t ₃ .

Due to the interference of high-frequency signals such as vibration and electromagnetic interference when the machine tool is running, the directly collected current signal is relatively cluttered. In addition to the interference signal, the moment of sudden change of the current signal, that is, the end moment of the backlash, is accurately calculated.

The method for identifying the backlash based on the response data of the numerical control machine tool provided in this embodiment further includes: compensating the backlash obtained by the identification.

The utility model compensates the recognized backlash on the machine tool that accurately recognizes the backlash, and can effectively improve the machining accuracy of the numerically controlled machine tool.

Example 2:

A backlash identification device based on response data of a numerically controlled machine tool, comprising: a data extraction module, a reverse data segment marking module, a gap period identification module, a backlash identification module and a backlash compensation module;

The data extraction module is used to extract the command speed signal v _c (t), the current signal I (t), the encoder displacement signal p _e (t) and the code generated on the target horizontal feed axis when the CNC machine tool executes the reverse command speed signal v _e (t);

The reverse data segment marking module is used to obtain the time t ₀ at which the command speed crosses zero in the command speed signal, and the time t ₃ after the time t ₀ which is separated by a preset time length t _last ;

The gap period identification module removes the time delay e _i relative to the command speed signal v _c (t) in the encoder speed signal v _e (t) to obtain the synchronized command speed signal v _c (te _i ), and Calculate the speed difference _{e v} (t) according to e _v (t)= _vc (te _i )-ve (t); the gap period identification module is also used to calculate the speed difference e _v (t) in the time period respectively the sudden change time t ₁ in the period t ₀ to t ₃ and the sudden change time t ₂ of the current signal I(t) in the time period t ₀ to t ₃ ;

The backlash identification module is used to calculate the displacement increment generated by the encoder displacement signal p _e (t) in the time period t ₁ to t ₂ , and identify its absolute value as the backlash;

The backlash compensation module is used to compensate the backlash identified by the backlash identification module;

In this embodiment, for the specific implementation of each module, reference may be made to the descriptions in the foregoing method embodiments, which will not be repeated here.

Example 3:

A computer-readable storage medium includes a stored computer program; when the computer program is executed by a processor, the device where the computer-readable storage medium is located is controlled to execute the method for backlash identification based on the response data of a numerically controlled machine tool provided in Embodiment 1 above.

The beneficial effects that can be obtained by the present invention will be further described below by taking the application of the above embodiment in the BM8-H Baoji vertical machining center as an example. The structure of the servo feed system of the BM8-H Baoji CNC machine tool is shown in Figure 2. The machine tool adopts a ball screw drive system, and the ball screw converts the rotary motion into the linear motion of the worktable through the nut; as shown in Figure 3, the machine tool adopts Semi-closed loop control, the feedback signal of the position loop comes from the rotational displacement of the screw input measured by the incremental encoder of the motor, the feedback of the speed loop comes from the differential value of the feedback of the position loop, and the feedback of the current loop comes from the current of the driving motor; In order to compare the identification accuracy of the present invention, grating rulers are installed on the x-axis and y-axis table of the machine tool; the numerical control system is the Huazhong 8 domestic numerical control system.

For the feed X axis, the specific identification process is as follows:

S1: The machine tool executes the position triangular wave command signal of F3000, and the machine tool moves in the forward and reverse directions;

S2: Set the machine data acquisition software channel to collect the command speed signal vc(t) of the feed X axis, the current signal I(t), the encoder displacement p _e (t), and the encoder speed signal v _e (t);

因此t₃＝3547ms，间隙期区间为[3359,3547]；S3: Reverse process automatic marking: according to the zero-crossing criterion of command speed: v _c (t ₀ )*v _c (t ₀ +1)<0 or v _c (t ₀ )*v _c (t ₀ +2)< 0 and v _c (t ₀ +1)=0, accurately find out the command speed zero-crossing point t ₀ =3359ms. According to experience, the reverse duration will not exceed 1/20 of the trajectory period, so let the reverse duration

Therefore, t ₃ =3547ms, and the gap interval is [3359,3547];

S4: Determination of the start time _t1 and the end time _t2 of the gap period: based on the collected response data, it can be known that the time delay of the encoder speed relative to the command speed is e _i =15ms, and the difference between the two is obtained to obtain the speed difference e _v (t ); the sudden change time corresponding to e _v (t) in t ₀ ~ t ₃ is t ₁ =3382ms; the current signal I(t) is subjected to 50Hz low-pass filtering and then differentiated by dI _low (t), at t ₀ ~ t _{3 Find} the _{moment of sudden} change in the current signal in is 1.6μm, and the identification error is 6.7%; at the same speed, other identification methods that do not rely on grating scales often have identification errors of more than 20%. It can be seen that the identification method proposed by Ben Fangming has high identification accuracy. .

The above determined reverse data segment (ie time segment t ₀ to t ₃ ), and the calculation method of the start time t ₁ and the end time t ₂ of the gap period in this time segment are shown in FIG. 4 .

According to the same method, let the CNC machine tool execute the F1000, F6000 and F8000 position triangular wave command signals on the feed X axis; according to the same method, the zero CNC machine tool executes the F1000, F3000, F6000 and F8000 position triangle wave command signals on the feed Y axis; Table 1 shows the backlash identified based on the method provided in the above embodiment and the backlash measured directly by the grating ruler. According to the results shown in Table 1, at different speeds, the maximum error is only 16%. It can be seen that the above-mentioned backlash identification method based on the response data of the CNC machine tool provided by the present invention has high identification accuracy .

Table 1. Clearance identification results of Baoji machine tools at different speeds

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (8)

1. a backlash identification method based on CNC machine tool response data, is characterized in that, comprises: Extract the command speed signal v _c (t), the current signal I (t), the encoder displacement signal p _e (t) and the encoder speed signal v generated on the target horizontal feed axis when the numerical control machine tool executes the reverse command _e (t), obtaining the time t ₀ at which the command speed crosses zero in the command speed signal, and the time t ₃ after the time t ₀ and the interval between the time t 0 and the preset time length t _last ; After the time delay amount e _i of the encoder speed signal v _e (t) relative to the command speed signal v _c (t) is eliminated, the synchronized command speed signal v _c (te _i ) is obtained, and according to e _v (t)= _vc (te _i )-ve (t) to calculate the speed difference _{e v} (t); respectively calculate the speed difference e _v (t) in the time period t ₀ -t ₃ the sudden change in time t ₁ and the sudden change in time t ₂ of the current signal I(t) in the time period t ₀ to t ₃ ; The displacement increment generated by the encoder displacement signal p _e (t) in the time period t ₁ -t ₂ is calculated, and the absolute value thereof is identified as the backlash. 2. the backlash identification method based on numerical control machine tool response data as claimed in claim 1, is characterized in that,

Wherein, T represents the track period of the CNC machine tool. 3. the backlash identification method based on numerical control machine tool response data as claimed in claim 1 is characterized in that, the criterion of the time t ₀ when the command speed crosses zero in the command speed signal is: v _c (t ₀ )*v _c (t ₀ +1)<0; Alternatively, _vc (t ₀ )* _vc (t ₀ +2)<0 and _vc (t ₀ +1)=0. 4 . The method for identifying backlash based on the response data of a numerically controlled machine tool according to claim 1 , wherein the current signal I(t) is at a sudden change time t ₂ in the time period t ₀ to t ₃ , Its calculation method is as follows: The current signal I(t) is subjected to low-pass filtering and then differentiated to obtain a signal dI _low (t); Find the extreme value moment of the signal dI _low (t) in the time period t ₀ -t ₃ , that is, obtain the sudden change moment t of the current signal I(t) in the time period t ₀ -t _{3 2} . 5 . The method for identifying backlash based on the response data of a numerically controlled machine tool according to claim 1 , further comprising: compensating for the backlash identified. 6 . 6. A backlash identification device based on CNC machine tool response data, characterized in that it comprises: a data extraction module, a reverse data segment marking module, a gap period identification module and a backlash identification module; The data extraction module is used to extract the command speed signal v _c (t), the current signal I (t), the encoder displacement signal p _e ( t) and the encoder speed signal _ve (t); The reverse data segment marking module is used to obtain the time t ₀ at which the command speed crosses zero in the command speed signal, and the time t ₃ after the time t ₀ that is separated by a preset time length t _last ; The gap period identification module, after eliminating the time delay amount e _i relative to the command speed signal v _c (t) in the encoder speed signal v _e (t), obtains the synchronized command speed signal v _c (te _i ), and calculate the speed difference _{e v} (t) according to e _v (t)= _vc (te _i )-ve (t); the gap identification module is also used to calculate the speed respectively the sudden change time t1 of the difference e _v (t) in the time period t ₀ to t ₃ and the sudden change time t ₂ of the current signal I(t) in the time period t ₀ to t _{3 ;} The backlash identification module is configured to calculate the displacement increment generated by the encoder displacement signal p _e (t) in the time period t ₁ -t ₂ , and identify its absolute value as the backlash. 7. The backlash identification device based on the response data of a numerically controlled machine tool as claimed in claim 6, further comprising: a backlash compensation module; The backlash compensation module is used for compensating the backlash identified by the backlash identification module. 8. A computer-readable storage medium, characterized in that it comprises a stored computer program; when the computer program is executed by a processor, the device where the computer-readable storage medium is located is controlled to perform the method described in any one of claims 1-5. The backlash identification method based on the response data of CNC machine tools.

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