Method and device for estimating rotation angle of rotary drum, electronic equipment and storage medium

Abstract

The invention provides a drum rotation angle estimation method and device, electronic equipment and a storage medium. According to the method for estimating the rotation angle of the rotary drum, when the rotary drum rotates, the pulse count of an incremental encoder is obtained; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor. And then the resolution of the incremental encoder, the pulse counting mode of the incremental encoder and the reduction ratio of the drum reduction gearbox are obtained. And finally, based on the pulse count, the resolution, the counting mode and the reduction ratio of the drum reduction gearbox, calculating to obtain a rotation angle value of the drum. Therefore, by means of the method, the rotating angle value of the drum can be accurately calculated, stable operation of drum winding drum equipment is guaranteed, and the situation that faults occur frequently is effectively restrained. The problem that the rotation angle of the drum is not accurately estimated in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the field of industrial control technology, and in particular to a method, device, electronic device and storage medium for estimating a rotation angle of a drum. Background Art

[0002] In actual production, the accuracy and stability of the drum rotation angle counting are the key to the normal operation of the equipment. However, in the prior art, due to the lack of an effective drum rotation angle estimation method, the drum rotation angle estimation is prone to inaccurate, resulting in unstable operation of the drum reel equipment and frequent failures. Summary of the invention

[0003] In view of this, the present application provides a method, device, electronic device and storage medium for estimating the rotation angle of a drum, so as to solve the problem of inaccurate estimation of the rotation angle of the drum in the prior art.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] The first aspect of the embodiment of the present application discloses a method for estimating a rotation angle of a drum, comprising:

[0006] When the drum rotates, the pulse count of the incremental encoder is obtained; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor;

[0007] Obtaining the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reduction box;

[0008] The drum rotation angle value is calculated based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box.

[0009] Optionally, the above method, before obtaining the pulse count of the incremental encoder, further includes:

[0010] The pulse isolation amplifier board is used to isolate and amplify the pulse signal of the incremental encoder.

[0011] Optionally, in the above method, the step of calculating the drum rotation angle value based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box includes:

[0012] Substituting the product of the pulse counting mode, the resolution and the reduction ratio of the drum reduction box into a preset conversion scale calculation formula to calculate the conversion scale;

[0013] The conversion scale is multiplied by the pulse number to calculate the drum rotation angle value.

[0014] Optionally, the above method, after calculating the drum rotation angle value based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box, further comprises:

[0015] Detecting whether the rotation angle value of the drum reaches 360 degrees;

[0016] If the rotation angle value of the drum reaches 360 degrees, the motor speed of the drum motor is controlled to return to zero.

[0017] Optionally, the above method, after controlling the motor speed of the drum motor to return to zero if the drum rotation angle value reaches 360 degrees, further comprises:

[0018] When it is detected that the first reel is in the threading position, the inlet clamp is closed, the outlet clamp is closed, the inlet locking pin is closed, the outlet locking pin is closed and the motor speed is zero, the drum rotation angle value is cleared.

[0019] The second aspect of the present application discloses a device for estimating a rotation angle of a drum, comprising:

[0020] A first acquisition unit is used to acquire a pulse count of an incremental encoder when the drum rotates; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor;

[0021] A second acquisition unit is used to acquire the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reduction box;

[0022] The calculation unit is used to calculate the drum rotation angle value based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box.

[0023] Optionally, the above device further includes:

[0024] The signal processing unit is used to perform signal isolation and signal amplification using the pulse signal of the incremental encoder of the pulse isolation amplifier board.

[0025] Optionally, in the above device, the computing unit includes:

[0026] The first calculation subunit is used to substitute the product of the pulse counting mode, the resolution and the reduction ratio of the drum reduction box into a preset conversion scale calculation formula to calculate the conversion scale;

[0027] The second calculation subunit is used for multiplying the conversion scale by the pulse number to calculate the drum rotation angle value.

[0028] Optionally, the above device further includes:

[0029] A first detection unit is used to detect whether the rotation angle value of the drum reaches 360 degrees;

[0030] The control unit is used to control the motor speed of the drum motor to return to zero if the rotation angle value of the drum reaches 360 degrees.

[0031] Optionally, the above device further includes:

[0032] The second detection unit is used to reset the drum rotation angle value to zero when detecting that the first reel is in the threading position, the inlet clamp is closed, the outlet clamp is closed, the inlet locking pin is closed, the outlet locking pin is closed, and the motor speed is zero.

[0033] The third aspect of the present application discloses an electronic device, comprising:

[0034] one or more processors;

[0035] a storage device having one or more programs stored thereon;

[0036] When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described in any one of the first aspects of the present application.

[0037] A fourth aspect of the present application discloses a computer storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the method described in any one of the first aspects of the present application is implemented.

[0038] It can be seen from the above technical scheme that in a method for estimating the drum rotation angle provided by the present application, when the drum rotates, the pulse count of the incremental encoder is obtained; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor. Then the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reducer are obtained. Finally, based on the pulse count, the resolution, the counting method, and the reduction ratio of the drum reducer, the drum rotation angle value is calculated. It can be seen that by using the method of the present application, the drum rotation angle value can be accurately calculated to ensure the stable operation of the drum reel equipment and effectively curb the frequent failures. The problem of inaccurate drum rotation angle estimation in the prior art is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0040] Figure 1 It is a flow chart of a method for estimating a drum rotation angle disclosed in an embodiment of the present application;

[0041] Figure 2 This is a schematic diagram of an application scenario of a rotary drum disclosed in another embodiment of the present application;

[0042] Figure 3 This is an exemplary diagram of a rotation control component of a rotating drum disclosed in another embodiment of the present application;

[0043] Figure 4 It is a schematic diagram of a device for estimating the rotation angle of a drum disclosed in another embodiment of the present application;

[0044] Figure 5 A schematic diagram of an electronic device disclosed in another embodiment of the present application. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0047] Furthermore, in this document, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0048] As can be seen from the background technology, in actual production, due to the lack of an effective method for estimating the drum rotation angle, inaccurate estimation of the drum rotation angle is prone to occur, resulting in unstable operation of the drum winding equipment and frequent failures.

[0049] In view of this, the present application provides a method, device, electronic device and storage medium for estimating the rotation angle of a drum, so as to solve the problem of inaccurate estimation of the rotation angle of the drum in the prior art.

[0050] The present application embodiment provides a method for estimating the rotation angle of a drum, such as Figure 1 As shown, specifically including:

[0051] S101. When the drum rotates, obtain a pulse count of an incremental encoder; wherein the pulse count is the number of pulses generated when the incremental encoder measures the rotation of the drum motor.

[0052] It should be noted that the application scenarios of the drum in this embodiment are as follows Figure 2 As shown, the components represented by each number are: 1. drum positioning block; 2. drum; 3. drum rotating shaft; 4. first reel; 5. winding aid; 6. inlet clamp; 7. inlet clamp hydraulic cylinder; 8. inlet locking pin; 9. second reel; 10. outer support arm; 11. drum positioning block; 12. outlet clamp; 13. outlet clamp hydraulic cylinder; 14. outlet locking pin.

[0053] When the first reel is in the threading position, the initial position of the drum is defined as 0°, and the angle value of the first reel after rotating from the threading position to the take-up position is 180°; when the second reel is in the threading position, the initial position of the drum is defined as 180°, and the angle value of the second reel after rotating from the threading position to the take-up position is 360°. The threading reel and the take-up reel are distributed on the center line of the drum, 180° apart from each other.

[0054] The rotating drum control components such as Figure 3 As shown, it includes: brake, angle encoder, reducer, drum reducer, drum gear plate, drum transmission motor and incremental encoder. The incremental encoder is installed on the lead-out shaft at the tail end of the drum motor to measure the motor rotation. The couplings of the drum transmission device are all rigidly connected, so there is a fixed proportional relationship between the pulse count of the incremental encoder and the rotation angle value of the drum. The pulse count of the incremental encoder can be converted into the drum rotation angle value to achieve the measurement of the angle value.

[0055] It should also be noted that when the drum rotates, the incremental encoder measures the number of pulses generated when the drum motor rotates, which is the pulse count. The incremental encoder can convert displacement into periodic electrical signals, and then convert these electrical signals into pulse counts, using the number of pulses to represent the size of the displacement. Every time the target object moves a unit distance, the encoder will generate a certain number of pulse signals, which is called the pulse count of the incremental encoder.

[0056] Optionally, in another embodiment of the present application, before executing step S101, the following may also be included:

[0057] The pulse isolation and amplification board is used to isolate and amplify the pulse signal of the incremental encoder.

[0058] It should be noted that a PE1315A pulse isolation amplifier board is installed in the drum transmission cabinet, and a 4*2*0.75 signal shielded cable is laid from the transmission cabinet to the controller. The pulse signal of the incremental encoder at the end of the motor is amplified and connected to the pulse counting board of the AC450 controller for counting. Isolation is to prevent other signals from entering the PLC control system, and amplification is to ensure the accuracy of the PLC counting board and prevent pulse loss. The signal shielded cable consists of four groups of twisted pairs, each of which has a copper wire shielding layer, and the four groups of twisted pairs are wrapped with a copper wire shielding layer. The purpose is to prevent the signal from being interfered with by the outside.

[0059] S102, obtaining the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reduction box.

[0060] It should be noted that the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reducer are obtained to calculate the drum rotation angle value in combination with the pulse counting. The resolution of the incremental encoder refers to the minimum angle change that the encoder can detect, usually expressed as the number of pulses corresponding to a unit angle change, also known as the number of pulses or lines. For example, an incremental encoder has a resolution of 1000 lines, which means that it can detect 1000 pulses 1 for every degree of rotation. The higher the resolution, the higher the accuracy of the encoder. In this embodiment, the resolution of the incremental encoder is 1024. The counting method of the incremental encoder pulses uses the method of counting both the rising and falling edges of the encoder A / B channel, so the value is 4. The reduction ratio of the drum reducer refers to the ratio of the input shaft speed to the output shaft speed in the reducer.

[0061] S103, calculating the drum rotation angle value based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box.

[0062] It should be noted that a program is compiled in the controller to convert the number of incremental encoder pulses at the end of the motor into the drum angle value. The physical angle value of the drum rotating one circle from the initial position is 360 degrees. Based on the pulse count, the resolution of the incremental encoder, the counting method of the incremental encoder pulses and the reduction ratio of the drum reducer, the preset pulse number to angle value calculation formula can be used to calculate the drum rotation angle value. The drum rotation angle value can be used to know how many degrees the drum has rotated.

[0063] In a method for estimating the rotation angle of a drum provided in an embodiment of the present application, when the drum rotates, the pulse count of the incremental encoder is obtained; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor. Then the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reducer are obtained. Finally, based on the pulse count, the resolution, the counting method, and the reduction ratio of the drum reducer, the value of the rotation angle of the drum is calculated. It can be seen that the method of the present application can accurately calculate the value of the rotation angle of the drum, ensure the stable operation of the drum reel equipment, and effectively curb the frequent failures. The problem of inaccurate estimation of the rotation angle of the drum in the prior art is solved.

[0064] Optionally, in another embodiment of the present application, an implementation of the above step S103 may include:

[0065] The product of the pulse counting method, the resolution and the reduction ratio of the drum reduction box is substituted into a preset conversion scale calculation formula to calculate the conversion scale.

[0066] The conversion scale is multiplied by the pulse number to calculate the drum rotation angle value.

[0067] It should be noted that the conversion scale calculation formula is as follows:

[0068] SF=360÷(Fact×PPR×Z)

[0069] Among them, Fact is the pulse counting method, PPR is the resolution of the incremental encoder, and Z is the reduction ratio of the reducer. Therefore, after obtaining the resolution, the counting method and the reduction ratio of the drum reducer, the conversion scale SF can be calculated.

[0070] The calculation formula of the drum rotation angle value is as follows:

[0071] POS=SF×POSMV

[0072] Among them, SF is the conversion scale, and POSMV is the pulse count of the incremental encoder. Therefore, after calculating the conversion scale, the conversion scale and the pulse count are multiplied to obtain the drum rotation angle value.

[0073] Optionally, in another embodiment of the present application, after executing step S103, the following may also be included:

[0074] Detect whether the rotation angle value of the drum reaches 360 degrees.

[0075] If the drum rotation angle reaches 360 degrees, the motor speed of the drum motor is reset to zero.

[0076] It should be noted that after the drum rotation angle is calculated, it is detected whether the drum rotation angle value reaches 360 degrees. If the drum rotation angle value reaches 360 degrees, the drum has rotated one circle, and the motor speed of the drum motor is controlled to zero to prepare for the next drum rotation count.

[0077] Optionally, in another embodiment of the present application, after executing the above steps and clearing the motor speed of the drum motor if the drum rotation angle value reaches 360 degrees, the following may also be included:

[0078] When it is detected that the first reel is in the threading position, the inlet clamp is closed, the outlet clamp is closed, the inlet locking pin is closed, the outlet locking pin is closed and the motor speed is zero, the drum rotation angle value is cleared.

[0079] It should be noted that it is detected whether the first reel is in the threading position, whether the inlet clamp and the outlet clamp of the drum are closed, and whether the inlet locking pin and the outlet locking pin of the drum are closed. When it is detected that the first reel is in the threading position, the inlet clamp is closed, the outlet clamp is closed, the inlet locking pin is closed, the outlet locking pin is closed, and the motor speed is zero, the drum rotation angle value is cleared to prepare for the next drum rotation count.

[0080] Another embodiment of the present application also provides a device for estimating the rotation angle of a drum, such as Figure 4 As shown, including:

[0081] The first acquisition unit 401 is used to acquire the pulse count of the incremental encoder when the drum rotates; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor.

[0082] The second acquisition unit 402 is used to acquire the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reduction box.

[0083] The calculation unit 403 is used to calculate the drum rotation angle value based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box.

[0084] In this embodiment, the specific execution process of the first acquisition unit 401, the second acquisition unit 402 and the calculation unit 403 can be found in the corresponding Figure 1 The content of the method embodiment will not be repeated here.

[0085] In a drum rotation angle estimation device provided by an embodiment of the present application, when the drum rotates, the first acquisition unit 401 acquires the pulse count of the incremental encoder; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor. Then the second acquisition unit 402 acquires the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reducer. Finally, the calculation unit 403 calculates the drum rotation angle value based on the pulse count, the resolution, the counting method, and the reduction ratio of the drum reducer. It can be seen that the method of the present application can accurately calculate the drum rotation angle value, ensure the stable operation of the drum reel equipment, and effectively curb the frequent failures. The problem of inaccurate drum rotation angle estimation in the prior art is solved.

[0086] Optionally, in another embodiment of the present application, the device for estimating the rotation angle of the drum may further include:

[0087] The signal processing unit is used to perform signal isolation and signal amplification using the pulse signal of the incremental encoder of the pulse isolation amplifier board.

[0088] In this embodiment, the specific execution process of the signal processing unit can refer to the corresponding method embodiment content above, which will not be repeated here.

[0089] Optionally, in another embodiment of the present application, an implementation of the above-mentioned calculation unit 403 may include:

[0090] The first calculation subunit is used to substitute the product of the pulse counting mode, the resolution and the reduction ratio of the drum reduction box into a preset conversion scale calculation formula to calculate the conversion scale.

[0091] The second calculation subunit is used for multiplying the conversion scale by the pulse number to calculate the drum rotation angle value.

[0092] In this embodiment, the specific execution process of the first computing subunit and the second computing subunit can be found in the corresponding method embodiment described above, and will not be repeated here.

[0093] Optionally, in another embodiment of the present application, the device for estimating the rotation angle of the drum may further include:

[0094] The first detection unit is used to detect whether the rotation angle value of the drum reaches 360 degrees.

[0095] The control unit is used to control the motor speed of the drum motor to return to zero if the rotation angle value of the drum reaches 360 degrees.

[0096] In this embodiment, the specific execution process of the first detection unit and the control unit can refer to the corresponding method embodiment content above, which will not be repeated here.

[0097] Optionally, in another embodiment of the present application, the device for estimating the rotation angle of the drum may further include:

[0098] The second detection unit is used to reset the drum rotation angle value to zero when detecting that the first reel is in the threading position, the inlet clamp is closed, the outlet clamp is closed, the inlet locking pin is closed, the outlet locking pin is closed, and the motor speed is zero.

[0099] In this embodiment, the specific execution process of the second detection unit can refer to the corresponding method embodiment content above, which will not be repeated here.

[0100] Another embodiment of the application also provides an electronic device, such as Figure 5 As shown, specifically including:

[0101] One or more processors 501 .

[0102] The storage device 502 stores one or more programs.

[0103] When one or more programs are executed by one or more processors 501 , the one or more processors 501 implement any one of the methods in the above embodiments.

[0104] Another embodiment of the present application further provides a computer storage medium on which a computer program is stored, wherein when the computer program is executed by a processor, any one of the methods in the above embodiments is implemented.

[0105] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0106] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0107] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for estimating a drum rotation angle, characterized in that: include: When the drum rotates, the pulse count of the incremental encoder is obtained; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor; Obtaining the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reduction box; The drum rotation angle value is calculated based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box.

2. The method according to claim 1, characterized in that: Before obtaining the pulse count of the incremental encoder, the method further includes: The pulse isolation amplifier board is used to isolate and amplify the pulse signal of the incremental encoder.

3. The method according to claim 1, characterized in that The method of calculating the drum rotation angle value based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box includes: Substituting the product of the pulse counting mode, the resolution and the reduction ratio of the drum reduction box into a preset conversion scale calculation formula to calculate the conversion scale; The conversion scale is multiplied by the pulse number to calculate the drum rotation angle value.

4. The method according to claim 1, characterized in that After the drum rotation angle value is calculated based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box, the method further includes: Detecting whether the rotation angle value of the drum reaches 360 degrees; If the rotation angle value of the drum reaches 360 degrees, the motor speed of the drum motor is controlled to return to zero.

5. The method according to claim 1, characterized in that If the rotation angle value of the drum reaches 360 degrees, after controlling the motor speed of the drum motor to return to zero, the method further includes: When it is detected that the first reel is in the threading position, the inlet clamp is closed, the outlet clamp is closed, the inlet locking pin is closed, the outlet locking pin is closed and the motor speed is zero, the drum rotation angle value is cleared.

6. A device for estimating the rotation angle of a drum, characterized in that: include: A first acquisition unit is used to acquire a pulse count of an incremental encoder when the drum rotates; wherein the pulse count is the number of pulse signals generated when the incremental encoder measures the rotation of the drum motor; A second acquisition unit is used to acquire the resolution of the incremental encoder, the counting method of the incremental encoder pulses, and the reduction ratio of the drum reduction box; The calculation unit is used to calculate the drum rotation angle value based on the pulse count, the resolution, the counting method and the reduction ratio of the drum reduction box.

7. The device according to claim 6, characterized in that The computing unit comprises: The first calculation subunit is used to substitute the product of the pulse counting mode, the resolution and the reduction ratio of the drum reduction box into a preset conversion scale calculation formula to calculate the conversion scale; The second calculation subunit is used for multiplying the conversion scale by the pulse number to calculate the drum rotation angle value.

8. The device according to claim 6, characterized in that Also includes: A first detection unit is used to detect whether the rotation angle value of the drum reaches 360 degrees; The control unit is used to control the motor speed of the drum motor to return to zero if the rotation angle value of the drum reaches 360 degrees.

9. An electronic device, characterized in that: include: one or more processors; a storage device having one or more programs stored thereon; When the one or more programs are executed by the one or more processors, the one or more processors are enabled to implement the method according to any one of claims 1 to 5.

10. A computer storage medium, characterized in that: A computer program is stored thereon, wherein when the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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