Position correction method and system for open-loop control motor
By setting a travel switch and a controller at the initial position of the motor's motion axis and using the zero point area for position correction, the position error problem of the open-loop control motor is solved, and high-precision position correction and long-term accuracy are achieved. It is suitable for stepper motors and servo motors.
Patent Information
- Application Number
- CN202510888775.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-10-14
AI Technical Summary
Existing open-loop motor control methods are difficult to effectively eliminate position errors, resulting in position deviations that increase with operating time and travel, affecting the accuracy and safety of equipment operation.
By using a travel switch and a controller together, the travel switch is set at the initial position of the motor's motion shaft to set the zero point area. When the motor drives the object back, it is controlled to run to the zero point area, providing redundant space to achieve position zeroing and error correction.
It effectively avoids the accumulation of position errors, ensures the long-term accuracy of motion control, and improves the accuracy of position correction. It is suitable for stepper motors and servo motors, and is widely used and easy to use.
Smart Images
Figure CN120785220A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of motor control, and in particular relates to a position correction method and system for an open-loop controlled motor. Background Art
[0002] In modern industrial production, automated equipment, and precision instrumentation, accurate motor position control is crucial. However, in actual motor control, open-loop control often results in position errors due to various factors, such as mechanical problems and electrical interference. Conventional open-loop motor control methods struggle to effectively eliminate these errors. Position deviations increase with increasing operating time and travel, leading to incorrect equipment operation, impacting product processing and production requirements, and potentially causing equipment failure and safety issues. In many cases, closed-loop position control methods are necessary to correct position deviations to improve motor control accuracy and stability. Summary of the Invention
[0003] In order to solve the shortcomings of the prior art and achieve the purpose of correcting the motor position and improving the accuracy of the corrected position, the present invention adopts the following technical solutions: A position correction system for an open-loop controlled motor comprises a motor, a travel switch and a controller. The travel switch is arranged in conjunction with the initial position of the motor's motion shaft. A zero point area of the initial position is set based on the detection range of the travel switch (the effective detection area width is greater than 5 mm). The controller sets the motor's zero point position at the moment the motor drives an object away from the initial point based on the zero point area, and controls the change of the travel switch when the object completely leaves the zero point position. When the motor drives the object back, the controller controls the object to run to the zero point area. The zero point area provides redundant space for the return process of the motor control, so that the object runs to the zero point position within the detection range of the travel switch, thereby accurately performing position zeroing. In addition, the position of the travel switch is selected as the zero point area. From zero speed to starting to leave the motor position zero point is a low-speed state of the motor, thereby ensuring the consistency of the travel switch signal reading and high position correction accuracy.
[0004] Furthermore, the position of the motor is not recorded when it moves in the zero point area. When the object driven by the motor completely leaves the zero point position, the controller resets the current position to zero based on the travel switch to unify the actual operating mechanical position and the position of the control motor. When the motor runs to the target position L, due to system interference or other reasons, the mechanical position and the position of the control motor may be different. By resetting the position to zero, the actual operating mechanical position and the motor position required by the control are corrected.
[0005] Furthermore, the limit switch detects that the motor-driven object is at the first level when it is in the initial position. When the object driven by the motor leaves the zero position, the limit switch changes from the first level to the second level, thereby unifying the actual operating mechanical position and the position of the control motor.
[0006] Furthermore, when the motor drives the object to perform reciprocating motion, the motor drives the moving object back to the zero point, and the motor runs to the zero point area unconditionally. The controller controls the motor to drive the object to cross the zero point position based on the detection range of the travel switch and continue to move a certain distance (about 5 mm), thereby ensuring that the object runs to the zero point area and has a certain amount of redundant space, so that when it runs again (each time it is powered on or started up), the moving object starts from the zero point area, providing an accurate position reference for subsequent motion control.
[0007] Furthermore, when the motor drives the object to rotate, the motor drives the moving object back to the zero point, and the motor runs unconditionally to the zero point area. The controller controls the motor to drive the object to cross the zero position and continue to move a certain distance based on the detection range of the travel switch. The certain distance refers to the front end of the object crossing the zero position but the end of the object has not left the zero position. At this time, the zero position is exceeded but the tail of the object has not exceeded the zero position, which provides a certain redundant space for the object to return and reduces the detection burden on the travel switch. It is only necessary to ensure that part of the object is within the zero point area, and after startup, it is only necessary to change the travel switch at the moment the object leaves the zero position.
[0008] A method for correcting the position of an open-loop controlled motor comprises the following steps: Step 1: Set a travel switch at the initial position of the motor shaft and set the zero point area of the initial position based on the detection range of the travel switch (the effective detection area width is more than 5mm). The position of the travel switch is selected as the zero point area. From zero speed to starting and leaving the motor position zero point, the motor is in a low-speed state, thus ensuring the consistency of the travel switch signal reading and high position correction accuracy. Step 2: Based on the zero point area, set the motor zero point position when the motor drives the object away from the initial point; Step 3: When the object completely leaves the zero position, control the change of the travel switch; Step 4: After the motor reaches the target position, there is a deviation between the mechanical position and the position of the control motor; Step 5: When the motor drives the object back, it controls the object to run to the zero point area. The zero point area provides redundant space for the return process controlled by the motor, so that the object can run to the zero position within the detection range of the travel switch, thereby accurately returning to zero position. Step 6: During the motor movement, based on the actions in steps 3 and 5, the position deviation between the mechanical position and the control motor is corrected through the limit switch.
[0009] Furthermore, in step 6, the position of the motor is not recorded when it moves in the zero point area. When the object driven by the motor completely leaves the zero point position, the current position is reset to zero based on the travel switch to unify the actual operating mechanical position and the position of the control motor. When the motor runs to the target position L, due to system interference or other reasons, the mechanical position and the position of the control motor may be different. By resetting the position to zero, the actual operating mechanical position and the motor position required by the control are corrected.
[0010] Furthermore, the limit switch detects that the motor-driven object is at the first level when it is in the initial position. When the object driven by the motor leaves the zero position, the limit switch changes from the first level to the second level, thereby unifying the actual operating mechanical position and the position of the control motor.
[0011] Furthermore, in step 5, when the motor drives the object to perform reciprocating motion, the motor drives the moving object back to the zero point, and the motor runs unconditionally to the zero point area. Based on the detection range of the travel switch, the motor is controlled to drive the object to cross the zero point position and continue to move a certain distance (approximately 5 mm), thereby ensuring that the object runs to the zero point area and has a certain amount of redundant space, so that when it runs again (each time it is powered on or started up), the moving object starts from the zero point area, providing an accurate position reference for subsequent motion control.
[0012] Furthermore, in step 5, when the motor drives the object to rotate, the motor drives the moving object back to the zero point, and the motor runs unconditionally to the zero point area. Based on the detection range of the travel switch, the motor is controlled to drive the object to cross the zero position and continue to move a certain distance. The certain distance refers to the front end of the object crossing the zero position but the end of the object has not left the zero position. At this time, the zero position is exceeded but the tail of the object has not exceeded the zero position. This provides a certain redundant space for the object to return, and also reduces the detection burden on the travel switch. It is only necessary to ensure that part of the object is within the zero point area, and after startup, it is only necessary to change the travel switch at the moment the object leaves the zero position.
[0013] The advantages and beneficial effects of the present invention are: The present invention proposes a method and system for correcting the position of an open-loop controlled motor. By performing position zeroing each time the motor returns to the zero point region, this method effectively avoids dangerous or destructive movements caused by the accumulation of position errors during motor motion, thereby ensuring the long-term accuracy of motion control. The control method is simple and easy to implement, and has wide application in the field of automated equipment, particularly in the operation of stepper motors or servo motors. It also features low error, no error accumulation, simple implementation, positioning functionality, and high position correction accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 is a flow chart of a method in an embodiment of the present invention.
[0015] Figure 2 This is an example diagram of an object being driven to move by a motor based on the inventive method of the present invention in an embodiment of the present invention.
[0016] Figure 3 Schematic diagram of the system structure in an embodiment of the present invention. DETAILED DESCRIPTION
[0017] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.
[0018] In practice, open-loop motor control drives the motor by directly applying an input signal (such as voltage, PWM, or pulses) without feedback to detect the actual output. The controller adjusts the motor's speed or position based on preset commands but cannot automatically correct errors. Open-loop motor control is suitable for stepper or servo motors and offers a simple structure and low cost, but its accuracy and load adaptability are limited.
[0019] In order to solve the problem of low control accuracy, such as Figure 1 、 Figure 2 As shown, the present invention proposes a position correction method for an open-loop controlled motor. By position correction, the position deviation of the motor is automatically corrected to solve the position error caused by interference or abnormality of the motor control, and realize the correct application of the position of the open-loop controlled motor. The method includes the following steps: Step 1: Install a limit switch at the initial point of the motor's motion axis. The effective detection area of the limit switch should be wider than 5mm. If it detects that the motor has moved to the initial position, it will output a high level. Step 2: Determine the zero position of the motor, that is, the moment when the object driven by the motor leaves the initial point is the zero position, and the corresponding moment when the travel switch changes from high to low; Step 3: The motor does not record its position when it moves in the zero-point area. When the object driven by the motor leaves the zero-point position, the control system automatically sets the current position to 0 to unify the mechanical position (actual operating position) and the position of the controlled motor (control required position). The position of the limit switch is selected as the zero-point area. From speed 0 to starting and leaving the motor position 0, the motor is in a low-speed state, which ensures the consistency of the limit switch signal reading and high position correction accuracy. Step 4: The motor runs to the target position L. Due to system interference or other reasons, the mechanical position L1 and the control motor position L2 may be different (L1 is the actual running position, L2 is the control required position); Step 5: When the motor controls the moving object to return to the zero point, the motor unconditionally runs to the zero point area and controls the motor to continue moving about 5mm after reaching the zero point, thereby ensuring that the motor runs to the zero point area and has a certain amount of redundancy. Each time the power is turned on or turned on, the moving object returns to the zero point area, providing an accurate position reference for subsequent motion control. Step 6: During the reciprocating motion of the motor, any position error that may occur in the motor is automatically corrected as long as the actions of steps 3 and 5 are involved.
[0020] like Figure 3 As shown, a position correction system for an open-loop controlled motor includes a motor, a travel switch and a controller. The travel switch is arranged at the initial position of the motor motion shaft, and the zero point area of the initial position is set based on the detection range of the travel switch (the effective detection area width is more than 5 mm). The controller sets the motor zero point position when the motor drives the object to leave the initial point based on the zero point area, and controls the change of the travel switch when the object completely leaves the zero point position; when the motor drives the object to return, the controller controls the object to run to the zero point area. The zero point area provides redundant space for the return process of the motor control, so that the object can run to the zero point position within the detection range of the travel switch, thereby accurately returning the position to zero; and the position of the travel switch is selected as the zero point area, and the motor is in a low-speed state from zero speed to starting to leave the motor position zero point, thereby ensuring the consistency of the travel switch signal reading and high position correction accuracy.
[0021] The motor does not record the position when moving in the zero point area, and the controller resets the current position to zero based on the travel switch when the object driven by the motor completely leaves the zero point position, so as to unify the actual running mechanical position and the position of the control motor. When the motor runs to the target position L, due to system disturbance or other reasons, the mechanical position and the position of the control motor may be different. Through position resetting, the actual running mechanical position and the control required motor position are corrected. The travel switch detects the first level when the motor drives the object to the initial position, and the travel switch changes from the first level to the second level when the object driven by the motor leaves the zero point position, so as to unify the actual running mechanical position and the position of the control motor.
[0022] When the motor drives the object to perform reciprocating motion, the motor drives the moving object to return to the zero point, and the motor unconditionally runs to the zero point area. Based on the detection range of the travel switch, the controller controls the motor to drive the object to pass through the zero point position and continue to travel a certain distance (about 5mm), so as to ensure that the object runs to the zero point area and has a certain redundant space, so that the moving object starts from the zero point area when running again (each time power is turned on or the machine is started), and provides an accurate position reference for subsequent motion control.
[0023] When the motor drives the object to perform rotating motion, the motor drives the moving object to return to the zero point, and the motor unconditionally runs to the zero point area. Based on the detection range of the travel switch, the controller controls the motor to drive the object to pass through the zero point position and continue to travel a certain distance, which means that the front end of the object passes through the zero point position but the tail end of the object does not leave the zero point position. At this time, the object exceeds the zero point position but the tail end of the object does not exceed the zero point position, which provides a certain redundant space for the object to return and reduces the detection burden of the travel switch. Only the part of the object in the zero point area is needed to be ensured, and after starting, only the travel switch needs to be changed in an instant when the object leaves the zero point position.
[0024] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A position correction system for an open-loop controlled motor, comprising a motor, a travel switch, and a controller, characterized in that: The travel switch is arranged in conjunction with the initial position of the motor motion shaft, and the zero point area of the initial position is set based on the detection range of the travel switch. The controller sets the motor zero point position when the motor drives the object to leave the initial point based on the zero point area, and controls the change of the travel switch when the object completely leaves the zero point position; when the motor drives the object to return, the controller controls the object to run to the zero point area.
2. The position correction system of an open-loop control motor according to claim 1, characterized in that: The motor does not record its position when it moves in the zero point area. When the object driven by the motor completely leaves the zero point position, the controller resets the current position to zero based on the travel switch to unify the actual operating mechanical position and the position of the control motor.
3. The position correction system of an open-loop control motor according to claim 2, characterized in that: The limit switch is at the first level when detecting that the object driven by the motor is at the initial position. When the object driven by the motor leaves the zero position, the limit switch changes from the first level to the second level, thereby unifying the actual operating mechanical position and the position of the control motor.
4. The position correction system for an open-loop controlled motor according to claim 1, characterized in that: When the motor drives the object to perform reciprocating motion, the motor drives the moving object back to the zero point, and the motor runs unconditionally to the zero point area. The controller controls the motor to drive the object to continue moving a certain distance after passing the zero point position based on the detection range of the travel switch.
5. The position correction system of an open-loop control motor according to claim 1, characterized in that: When the motor drives the object to move, the motor drives the moving object back to the zero point, and the motor runs unconditionally to the zero point area. The controller controls the motor to drive the object to cross the zero point position and continue to move a certain distance based on the detection range of the travel switch. The certain distance means that the front end of the object crosses the zero point position but the end of the object does not leave the zero point position.
6. A method for correcting the position of an open-loop controlled motor, characterized in that The steps include: Step 1: Set a limit switch at the initial position of the motor shaft and set the zero point area of the initial position based on the detection range of the limit switch; Step 2: Based on the zero point area, set the motor zero point position when the motor drives the object away from the initial point; Step 3: When the object completely leaves the zero position, the position value is cleared, and the motor is controlled to run and enter the open-loop mode; Step 4: After the motor reaches the target position, the mechanical position may be inconsistent with the position of the control motor; Step 5: When the motor drives the object back, it controls the object to move to the zero point area; Step 6: During the motor movement, based on the actions in steps 3 and 5, the position deviation between the mechanical position and the control motor is corrected through the limit switch.
7. The method for correcting the position of an open-loop controlled motor according to claim 6, wherein: In step 6, the position of the motor is not recorded when it moves in the zero point area. When the object driven by the motor completely leaves the zero point position, the current position is reset to zero based on the travel switch to unify the actual operating mechanical position and the position of the control motor.
8. The method for correcting the position of an open-loop controlled motor according to claim 7, wherein: The limit switch is at the first level when detecting that the object driven by the motor is at the initial position. When the object driven by the motor leaves the zero position, the limit switch changes from the first level to the second level, thereby unifying the actual operating mechanical position and the position of the control motor.
9. The method for correcting the position of an open-loop controlled motor according to claim 6, wherein: In step 5, when the motor drives the object to perform reciprocating motion, the motor drives the moving object back to the zero point, and the motor runs unconditionally to the zero point area. Based on the detection range of the travel switch, the motor is controlled to drive the object to cross the zero point position and continue to move a certain distance.
10. The method for position correction of an open-loop controlled motor according to claim 6, characterized in that: In step 5, when the motor drives the object to move, the motor drives the moving object back to the zero point, and the motor runs unconditionally to the zero point area. Based on the detection range of the travel switch, the motor is controlled to drive the object to cross the zero position and then continue to move a certain distance. The certain distance refers to the front end of the object crossing the zero position but the end of the object does not leave the zero position.