A method and system for automatically calibrating the position of a lifting foot stepping motor of a keyhole machine

Abstract

The application provides a position automatic calibration method and system of a lock eye machine lifting presser foot stepping motor, and belongs to the technical field of sewing machine motor control. It solves the problem that the existing stepping motor cannot normally automatically lift and release the presser foot due to accumulated error caused by step loss. The calibration method comprises the following steps: issuing a lifting presser foot command and a step number Px1 to the stepping motor, controlling the stepping motor to run in the forward or reverse direction for a fixed step number Px1, and then stopping rotation; issuing a releasing presser foot command to control the stepping motor to run in the reverse or forward direction, and calculating the actual step number Px in real time; simultaneously, receiving the detection signal fed back by the sensor in real time; when Px≦Px0, if the edge change detection signal fed back by the sensor is received, issuing an automatic calibration step number Px3 to the stepping motor, continuing to run for the step number Px3, and then stopping running, and the releasing presser foot ends. The calibration method has the advantages that the accumulated error caused by step loss and the false error of the sensor can be eliminated.

Description

Technical Field

[0001] This invention belongs to the field of sewing machine motor control technology, and relates to an automatic position calibration method and system for the lifting and pressing foot motor of a buttonhole machine. Background Technology

[0002] A stepper motor is an open-loop control element that converts electrical pulse signals into angular or linear displacement. Under non-overload conditions, the motor's speed and stopping position depend only on the frequency and number of pulse signals, and are unaffected by load changes. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle in a set direction, called the "step angle." Its rotation occurs step by step at fixed angles. The angular displacement can be controlled by controlling the number of pulses, thus achieving accurate positioning; simultaneously, the motor's speed and acceleration can be controlled by controlling the pulse frequency, thus achieving speed regulation.

[0003] A stepper motor is a type of induction motor. Its working principle is to use electronic circuits to convert direct current into multi-phase timing control current that is supplied in a time-sharing manner. Only when this current is used to power the stepper motor can it work normally. The driver is a multi-phase timing controller that supplies power to the stepper motor in a time-sharing manner.

[0004] Existing direct-drive buttonhole machines typically use open-loop stepper motors to control the presser foot lifting mechanism in order to reduce costs. The stepper motor control meets the mechanical requirements for lifting, lowering, and partially lifting the presser foot. Simultaneously, the initial position of the stepper motor is determined by a combination of a sensor 4 and a baffle 3 mounted on the presser foot lifting mechanism 2. Figure 1 The diagram shows the positional relationship between the pressure foot lifting mechanism 2, the baffle 3, and the sensor 4 when the stepper motor is in its initial position. After power-on, the stepper motor first finds its initial position (located by sensor 4, as shown in the diagram). Figure 1 (As shown), then it receives commands from the main control to perform actions such as raising and lowering the pressure foot. When the pressure foot is raised, the baffle 3 moves away from the sensor 4, causing the sensor 4 to output a high / low level, such as... Figure 2 As shown; when the pressure foot is released, the baffle 3 blocks the sensor 4, causing the sensor 4 to output a level signal opposite to that when the pressure foot is released, such as... Figure 1 As shown, if the signal output of sensor 4 does not match the preset value when the pressure foot is lifted or lowered, an error message indicating abnormal sensor 4 signal will be reported and the machine will stop.

[0005] However, because open-loop control of stepper motors lacks accurate position feedback, when there are changes in mechanical load or loss of control signals in the hardware, the stepper motor may skip steps when lifting or lowering the pressure foot, resulting in cumulative errors. For example, if skipped steps occur when lifting the pressure foot, the lifting height of the pressure foot will become increasingly lower. Figure 1From the top, it appears that the distance between the baffle 3 and the sensor 4 decreases, while during the release of the pressure foot (running a fixed number of steps from the lifted position of the pressure foot), the position of the baffle 3 increases, eventually colliding with the mechanism and producing a sound. Furthermore, if there is a missed step during the release of the pressure foot, the baffle 3 may not return to the position of the sensor 4, causing the sensor 4 to output a signal opposite to that during the release, resulting in false alarms from the sensor 4 and affecting user experience. Therefore, the problem with the existing technology is that when the stepper motor experiences missed steps during operation, the stepper motor will accumulate errors, leading to the inability to automatically lift and release the pressure foot normally. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned technical problems by proposing an automatic calibration method and system for the position of the press foot motor of a buttonhole machine, which can automatically calibrate the position of the press foot motor in a timely manner to avoid cumulative errors and thus ensure the normal operation of the automatic press foot lifting and lowering.

[0007] The objective of this invention can be achieved through the following technical solution: an automatic position calibration method for the lifting and pressing foot motor of a buttonhole machine, characterized by comprising the following steps:

[0008] The stepper motor is given a command to lift the presser foot and the number of steps Px1 required to lift the presser foot. The stepper motor is controlled to rotate forward or in reverse for a fixed number of steps Px1 and then stop rotating, and the presser foot is lifted.

[0009] The stepper motor is given a command to release the pressure foot, and the stepper motor is controlled to rotate in reverse or forward at the position after running a fixed number of steps Px1. The pressure foot is released and the actual number of steps Px taken by the stepper motor during the release of the pressure foot is calculated in real time. At the same time, the detection signal is received from the sensor in real time.

[0010] If the sensor receives an edge change detection signal when Px≦Px0, it sends an automatic calibration step number Px3 to the stepper motor, controls the stepper motor to continue running for Px3 steps and then stops, and releases the pressure foot to end the process; otherwise, it outputs a sensor error signal, where Px0 is a preset error step number.

[0011] In the above-mentioned automatic position calibration method for the stepper motor of a buttonhole machine, the step of issuing a command to lift the presser foot and the number of steps Px1 required to lift the presser foot to the stepper motor, controlling the stepper motor to rotate forward or reverse for a fixed number of steps Px1 and then stop rotating, the step of which includes the following steps before lifting the presser foot:

[0012] The preset step count Px1, the automatic calibration step count Px3, and the error reporting step count Px0 are specified. The step count Px1 is the number of steps required to lift the pressure foot.

[0013] In the above-mentioned automatic position calibration method for the stepper motor of a buttonhole machine, the step of issuing a command to lift the presser foot and the number of steps Px1 required to lift the presser foot to the stepper motor, controlling the stepper motor to rotate forward or reverse for a fixed number of steps Px1 and then stop rotating, the step of which includes the following steps before lifting the presser foot:

[0014] After the system is turned on, the stepper motor automatically searches for the initial position.

[0015] In the above-mentioned automatic calibration method for the position of the stepper motor of a buttonhole machine, the error reporting step number Px0 = the number of steps Px2 for releasing the pressure foot + the compensation step number Px4. When Px≦Px0, if an edge change signal is received from the sensor, an automatic calibration step number Px3 is sent to the stepper motor. The stepper motor is controlled to continue running for Px3 steps from the detection of the edge change signal and then stop running. The release of the pressure foot ends as follows:

[0016] When Px≦Px2, if an edge change detection signal is received from the sensor, an automatic calibration step number Px3 is sent to the stepper motor, and the stepper motor is controlled to continue running for Px3 steps before stopping and releasing the pressure foot; otherwise, the stepper motor is controlled to continue running for Px4 steps.

[0017] In the above-mentioned method for automatically calibrating the position of the stepper motor of a buttonhole machine, the edge change signal is the high and low level change output by the sensor.

[0018] An automatic position calibration system for the stepper motor of a buttonhole machine, characterized in that it includes a main control module and a stepper motor and a sensor connected to the main control module, wherein the main control module includes:

[0019] The presser foot lifting unit sends a command to lift the presser foot and the number of steps Px1 required to lift the presser foot to the stepper motor, controls the stepper motor to rotate forward or in reverse for a fixed number of steps Px1 and then stops rotating, thus lifting the presser foot.

[0020] The presser foot lifting unit sends a command to the stepper motor to release the presser foot, controlling the stepper motor to rotate in reverse or forward at the position after running a fixed number of steps Px1. The presser foot is released and the actual number of steps Px taken by the stepper motor during the release of the presser foot is calculated in real time. At the same time, the unit receives the detection signal from the sensor in real time.

[0021] The judgment unit determines whether Px ≦ Px0. If it receives an edge change detection signal from the sensor, it sends an automatic calibration step number Px3 to the stepper motor, controls the stepper motor to continue running for Px3 steps and then stops, and releases the pressure foot to end the operation. Otherwise, it outputs a sensor error signal, where Px0 is a preset error step number.

[0022] In the above-mentioned automatic position calibration system for the lifting foot step motor of a buttonhole machine, the operation panel is used to preset the number of steps Px1, the number of automatic calibration steps Px3, and the number of error reporting steps Px0. The number of steps Px1 is the number of steps for lifting the pressing foot.

[0023] In the aforementioned automatic position calibration system for the stepper motor of a buttonhole machine, the automatic position calibration system further includes an initial position search unit, which is used for the stepper motor to automatically search for the initial position after the system is turned on.

[0024] In the aforementioned automatic position calibration system for the stepper motor of a buttonhole machine, the main control module is electrically connected to the stepper motor via a stepper motor drive module.

[0025] In the aforementioned automatic position calibration system for the stepper motor of a buttonhole machine, the sensor is a stepper sensor.

[0026] Compared with existing technologies, the automatic position calibration method and system for the lifting and pressing foot motor of this buttonhole machine has the following advantages:

[0027] 1. When releasing the pressure foot, upon receiving an edge change detection signal from the sensor, an automatic calibration step count Px3 is sent to the stepper motor. The stepper motor continues to move for Px3 steps and then stops. Since the height of the pressure foot mechanical structure corresponding to the sensor edge change detection signal is fixed, each time the edge change detection signal is detected, it continues to move for Px3 steps and then stops. This ensures that the height of the baffle is consistent after each pressure foot release. Therefore, when lifting the pressure foot, the starting point is always the position after the pressure foot is released, which can eliminate the error of the previous operation and effectively solve the problem of accumulated error, thereby improving control accuracy.

[0028] 2. A compensation step count Px4 is introduced. If the sensor edge change signal is not detected after the pressure foot has completed the pressure foot operation step count Px2, the sensor will not report an error. This is because the actual number of steps taken may be less than the pressure foot operation step count Px2 due to missed steps. In this case, the compensation step count Px4 is then performed. If the sensor edge change signal was not detected after completing the pressure foot operation step count Px2 due to missed steps, then the compensation step count Px4 will definitely detect the sensor edge change signal, rather than indicating a sensor malfunction. Therefore, the compensation step count Px4 can eliminate the situation where the sensor falsely reports an error due to the missed step. If the sensor edge change signal is still not detected after completing the compensation step count Px4, then the sensor is indeed malfunctioning, and an error will be reported. Attached Figure Description

[0029] Figure 1This is a structural diagram showing the positional relationship between the pressure foot lifting mechanism, the baffle, and the sensor when the stepper motor is in its initial position.

[0030] Figure 2 This is a structural diagram showing the positional relationship between the lifting foot mechanism, the baffle, and the sensor after the baffle leaves the sensor when the pressure foot is lifted.

[0031] Figure 3 This is a flowchart of the automatic calibration method for this location.

[0032] Figure 4 This is a block diagram of the automatic position calibration system.

[0033] In the diagram, 1 is a stepper motor; 2 is a presser foot lifting mechanism; 3 is a baffle plate; and 4 is a sensor. Detailed Implementation

[0034] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0035] Example 1

[0036] like Figure 3 As shown, the automatic position calibration method for the lifting and pressing foot motor of this buttonhole machine includes the following steps:

[0037] A command to lift the presser foot and the number of steps Px1 required to lift the presser foot are sent to stepper motor 1. The stepper motor 1 is controlled to rotate forward or in reverse for a fixed number of steps Px1 and then stop rotating, and the presser foot is lifted.

[0038] A command to release the pressure foot is sent to the stepper motor 1, controlling the stepper motor 1 to reverse or rotate forward at the position after running a fixed number of steps Px1. The pressure foot is released and the actual number of steps Px taken by the stepper motor 1 during the release of the pressure foot is calculated in real time. At the same time, the detection signal is received from the sensor 4 in real time.

[0039] If the edge change detection signal is received from sensor 4 when Px≦Px0, an automatic calibration step number Px3 is sent to stepper motor 1, and stepper motor 1 continues to move for Px3 steps before stopping and releasing the pressure foot. Otherwise, an error signal is output from sensor 4, where Px0 is the preset error step number.

[0040] Of course, the stepper motor 1 is then given a command to lift the presser foot and the required number of steps Px1. The stepper motor 1 is then controlled to rotate forward or backward for a fixed number of steps Px1 before stopping. Before lifting the presser foot, various parameters need to be preset, including setting a preset number of steps Px1, an automatic calibration number of steps Px3, and an error reporting number of steps Px0. Here, the number of steps Px1 is the number of steps required to lift the presser foot. After the system is started, the stepper motor 1 automatically searches for the initial position, which is as follows: Figure 1 The position of the baffle 3 is such that it is directly opposite the sensor 4, and the baffle 3 is fixedly mounted on the lifting foot mechanism 2. The preset value of the automatic calibration step count Px3 is the number of steps the stepper motor 1 continues to run after detecting the signal from the sensor 4 when it starts up and finds its initial position.

[0041] When the pressure foot is released, upon receiving the edge change detection signal from sensor 4 (where the edge change signal is the high / low level change output by sensor 4), an automatic calibration step count Px3 is sent to stepper motor 1. Stepper motor 1 continues to move Px3 steps and then stops. Since the height position of the pressure foot mechanical structure corresponding to the edge change detection signal from sensor 4 is fixed, each time the edge change detection signal is detected, it continues to move Px3 steps and then stops. This ensures that the height of the baffle 3 is consistent after each pressure foot release. Therefore, when lifting the pressure foot, the starting point is always the position after the pressure foot is released, which can eliminate the error from the previous operation. This effectively solves the problem of accumulated error, improves control accuracy, and eliminates mechanical collision noise caused by positional errors without increasing costs.

[0042] Furthermore, to eliminate the false alarm problem of sensor 4, this method introduces a compensation step count Px4. Specifically, the error reporting step count Px0 = the number of steps the pressure foot takes Px2 + the compensation step count Px4. When Px≦Px0, if an edge change signal is received from sensor 4, an automatic calibration step count Px3 is sent to stepper motor 1. Stepper motor 1 continues to run for Px3 steps from the detection of the edge change signal and then stops, ending the pressure foot release. Specifically, when Px≦Px2, if an edge change detection signal is received from sensor 4, an automatic calibration step count Px3 is sent to stepper motor 1. Stepper motor 1 continues to run for Px3 steps and then stops, ending the pressure foot release. Otherwise, stepper motor 1 continues to run for Px4 steps. The compensation step count Px4 can also be preset, and both the compensation step count Px4 and the automatic calibration step count Px3 can be adjusted by the user according to the actual situation (mechanical position), improving its adaptability and user-friendliness.

[0043] A compensation step count Px4 is introduced. If the pressure foot completes the pressure foot operation step count Px2 and no edge change signal is detected from sensor 4, sensor 4 will not report an error. This is because the actual number of steps taken may be less than the pressure foot operation step count Px2 due to a missed step. In this case, if the missing step count Px2 was caused by a missed step, then the compensation step count Px4 will definitely detect the edge change signal from sensor 4, rather than indicating a malfunction in sensor 4 itself. Therefore, the introduction of the compensation step count Px4 can eliminate the situation where sensor 4 falsely reports an error due to a missed step, improving the accuracy of the position and the user experience. If the edge change signal from sensor 4 is still not detected after completing the compensation step count Px4, then sensor 4 is indeed malfunctioning, and an error will be reported from sensor 4.

[0044] Example 2

[0045] like Figure 4 As shown, the automatic position calibration system for the stepper motor 1 of this buttonhole machine includes a main control module, a stepper motor 1 connected to the main control module, and a sensor 4. The main control module is electrically connected to the stepper motor 1 via a stepper motor 1 drive module. In this embodiment, the sensor 4 is a stepper sensor. The main control module includes:

[0046] The initial position search unit is used for the stepper motor 1 to automatically search for the initial position after the system is turned on;

[0047] The presser foot lifting unit sends a command to lift the presser foot and the number of steps Px1 required to lift the presser foot to the stepper motor 1, and controls the stepper motor 1 to rotate forward or in reverse for a fixed number of steps Px1 before stopping, thus lifting the presser foot.

[0048] The presser foot lifting unit sends a command to the stepper motor 1 to release the presser foot, controlling the stepper motor 1 to rotate in reverse or forward at the position after running a fixed number of steps Px1. The presser foot is released and the actual number of steps Px taken by the stepper motor 1 during the release of the presser foot is calculated in real time. At the same time, the unit receives the detection signal from the sensor 4 in real time.

[0049] The judgment unit determines whether Px ≦ Px0. If it receives the edge change detection signal from sensor 4, it sends an automatic calibration step number Px3 to stepper motor 1, controls stepper motor 1 to continue running for Px3 steps and then stops running, and releases the pressure foot to end the process. Otherwise, it outputs an error signal from sensor 4, where Px0 is a preset error step number.

[0050] The error reporting step count Px0 = the number of steps Px2 for releasing the pressure foot + the compensation step count Px4. Specifically, when Px≦Px0, if an edge change signal is received from sensor 4, an automatic calibration step count Px3 is sent to stepper motor 1, controlling stepper motor 1 to continue running for Px3 steps from the detection of the edge change signal until it stops, ending the pressure foot release. Otherwise, stepper motor 1 continues running for Px4 steps.

[0051] The operation panel allows you to preset the number of steps to lift the pressure foot (Px1), release the pressure foot (Px2), automatically calibrate (Px3), and compensate (Px4).

[0052] Other control principles are the same as in Implementation 1, and will not be repeated here.

[0053] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for automatically calibrating the position of the stepper motor of a buttonhole machine, characterized in that, Includes the following steps: The stepper motor is given a command to lift the presser foot and the number of steps Px1 required to lift the presser foot. The stepper motor is controlled to rotate forward or in reverse for a fixed number of steps Px1 and then stop rotating, and the presser foot is lifted. The stepper motor is given a command to release the pressure foot, and the stepper motor is controlled to rotate in reverse or forward at the position after running a fixed number of steps Px1. The pressure foot is released and the actual number of steps Px taken by the stepper motor during the release of the pressure foot is calculated in real time. At the same time, the detection signal is received from the sensor in real time. Px0 is defined as the preset number of error reporting steps, where Px0 = number of steps Px2 for releasing the pressure foot + number of compensation steps Px4. When Px≦Px2, if an edge change detection signal is received from the sensor, an automatic calibration step number Px3 is sent to the stepper motor, controlling the stepper motor to continue running for Px3 steps and then stop running to end the pressure foot release. Otherwise, the stepper motor is controlled to continue running for Px4 steps. If an edge change detection signal is not received from the sensor after running for Px4 steps, a sensor error signal is output.

2. The method for automatically calibrating the position of the stepper motor of a buttonhole machine according to claim 1, characterized in that, The steps described above include issuing a command to lift the pressure foot and the required number of steps Px1 to the stepper motor, controlling the stepper motor to rotate forward or reverse for a fixed number of steps Px1 before stopping. Before lifting the pressure foot, the steps also include: The preset step count Px1, the automatic calibration step count Px3, and the error reporting step count Px0 are specified. The step count Px1 is the number of steps required to lift the pressure foot.

3. The method for automatically calibrating the position of the stepper motor of a buttonhole machine according to claim 2, characterized in that, The steps described above include issuing a command to lift the pressure foot and the required number of steps Px1 to the stepper motor, controlling the stepper motor to rotate forward or reverse for a fixed number of steps Px1 before stopping. Before lifting the pressure foot, the steps also include: After the system is turned on, the stepper motor automatically searches for the initial position.

4. The method for automatically calibrating the position of the stepper motor of a buttonhole machine according to claim 3, characterized in that, The edge change signal refers to the high and low level changes output by the sensor.

5. An automatic position calibration system for the stepper motor of a buttonhole machine, characterized in that, The system includes a main control module and stepper motors and sensors connected to the main control module. The main control module includes: The presser foot lifting unit sends a command to lift the presser foot and the number of steps Px1 required to lift the presser foot to the stepper motor, controls the stepper motor to rotate forward or in reverse for a fixed number of steps Px1 and then stops rotating, thus lifting the presser foot. The presser foot lifting unit sends a command to the stepper motor to release the presser foot, controlling the stepper motor to rotate in reverse or forward at the position after running a fixed number of steps Px1. The presser foot is released and the actual number of steps Px taken by the stepper motor during the release of the presser foot is calculated in real time. At the same time, the unit receives the detection signal from the sensor in real time. The judgment unit defines Px0 as the preset number of error steps, where Px0 = number of steps Px2 for releasing the pressure foot + number of compensation steps Px4. When Px≦Px2, if an edge change detection signal is received from the sensor, an automatic calibration step number Px3 is sent to the stepper motor, and the stepper motor is controlled to continue running for Px3 steps before stopping to end the pressure foot release. Otherwise, the stepper motor is controlled to continue running for Px4 steps. If an edge change detection signal is not received from the sensor after running for Px4 steps, a sensor error signal is output.

6. The automatic position calibration system for the lifting and pressing foot motor of a buttonhole machine according to claim 5, characterized in that, The operation panel is used to preset the number of steps Px1, the number of steps to automatically calibrate Px3, and the number of steps to report errors Px0. The number of steps Px1 is the number of steps to lift the pressure foot.

7. The automatic position calibration system for the lifting and pressing foot motor of a buttonhole machine according to claim 6, characterized in that, The automatic position calibration system also includes an initial position search unit, which is used for the stepper motor to automatically search for the initial position after the system is turned on.

8. The automatic position calibration system for the lifting and pressing foot motor of a buttonhole machine according to claim 5, 6, or 7, characterized in that, The main control module is electrically connected to the stepper motor through the stepper motor drive module.

9. The automatic position calibration system for the lifting and pressing foot motor of a buttonhole machine according to claim 8, characterized in that, The sensor in question is a stepper sensor.

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