Final-process force control method of Z-axis linear motor module of chip mounter, driver and medium

Abstract

The invention relates to the technical field of motor control, and discloses a chip mounter Z-axis linear motor module end-process force control method, a driver, a medium and a method, and the method comprises the following steps: S1, after a preset end-process position is reached, motor control is switched from position loop control to speed loop control, so that a motor keeps uniform motion; s2, monitoring whether a real-time current value fed back by the motor reaches a threshold current Iset1 or not and maintaining the real-time current value for a preset time length; s3, if the real-time current value reaches Iset1 and is maintained for a preset time length, continuously monitoring whether the real-time current value reaches a threshold current Iset2 and is maintained for a preset time length; and S4, if the real-time current value reaches Iset2 and is maintained for a preset time length, judging that collision occurs. According to the scheme, the speed ring is adopted to control the motor to move at a constant speed to carry out precise force control, meanwhile, the dynamic current threshold value is set to carry out two times of collision detection, collision detection is achieved while force control is carried out, a sensor does not need to be additionally used, and the requirements for mounting precision and compact structure are met.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to a final-stroke force control method, a driver, and a medium for a Z-axis linear motor module of a placement machine. Background Art

[0002] In the automated production process of a placement machine, the Z-axis of the placement head module performs two crucial tasks: first, driving the suction nozzle down to the precise position of the feeder (feeder or automated tray) to pick up tiny electronic components; second, accurately placing the picked-up components onto the predetermined pad locations on the printed circuit board (PCB). This process requires the Z-axis to possess high speed, high precision, and reliable contact force sensing capabilities.

[0003] However, for complex circuit boards, the bending of the board itself and the difference in thickness of different components may cause the Z-axis to be more sensitive to the suction and placement height during the actual placement process. When the Z-axis descent height is set more conservatively, the suction and placement failure is likely to occur. When the Z-axis descent height is set too high, it is easy to cause a significant collision of the Z-axis, damaging the components or the suction nozzle.

[0004] Currently, the Z-axis motion control systems for SMT machines on the market primarily include linear motors and servo motors. Servo motors drive the load in the Z direction via a belt and master and slave pulleys. The meshing clearance and tension changes between the belt and gears can lead to efficiency losses in the servo system, significantly impacting control performance during high-speed, high-precision control. Precision force control typically involves adding force sensors. Because of the transmission mechanism, current changes are significant, making simple current sensing solutions inadequate.

[0005] Because linear motors convert electrical energy into linear motion, eliminating the mechanical transmission link required by rotary motors, they offer higher energy transfer efficiency and significantly outperform servo motors in high-speed and high-precision control. They also provide more accurate thrust and load changes throughout the entire motion range. Currently, precision force control testing for Z-axis linear motors primarily utilizes force sensors. The core principle is still to evaluate changes in load pressure under different motion conditions and compare them with a set load pressure threshold to determine whether contact with the target position has occurred. However, this approach is not feasible for the Z-axis of a placement machine, which is sensitive to placement accuracy and has a compact structure.

[0006] Therefore, it is urgent to develop a precise force control solution for the Z-axis linear motor of the placement machine nozzle, which can accurately realize collision detection with controllable load pressure without relying on additional force sensors. Summary of the Invention

[0007] In order to solve the problems in the prior art, the purpose of the embodiments of the present invention is to provide a final force control method, driver, and medium for the Z-axis linear motor module of a placement machine, which can accurately realize collision detection with controllable load pressure without the need for additional sensors and adjustment structures.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for controlling the final stroke force of a Z-axis linear motor module of a placement machine, comprising the following steps: S1: After reaching the preset end position, the motor control switches from position loop control to speed loop control to keep the motor moving at a constant speed. S2, monitor whether the real-time current value of the motor feedback reaches the threshold current I set1 And maintain the preset time length for collision detection, where I set1 The theoretical current value I corresponding to the motor maintaining uniform motion set The difference is a fixed positive value; S3, if the real-time current value reaches I set1 If the preset time is maintained, the real-time current value is continuously monitored to see whether it reaches the threshold current I set2 And maintain the preset time length to confirm the collision, I in different positions set2 with I set1 The difference is a fixed positive value; S4, if the real-time current value reaches I set2 If the real-time current value is reduced to less than I set1 , it is determined that no collision has occurred, and step S2 is executed again until the designated position is reached.

[0009] Preferably, the theoretical current value I set Meet the following conditions: K f *I set +mg=F f , where K f is the linear motor thrust constant, m is the total mass of the motor secondary and the load, F f It is the sum of the spring resistance on the Z axis and the structural resistance on the Z axis, and g is the gravity constant.

[0010] Preferably, F f It is obtained by calibration, specifically: selecting measurement points at the end interval, measuring the static current of the motor in the force balance state at each measurement point, and according to K f *I set +mg=F fThe Z-axis structural resistance of each measurement point is calculated, and the calculation results are fitted to obtain an approximate curve to obtain the calibration results of the Z-axis structural resistance at different positions, where the spring resistance on the Z-axis is calculated according to the measurement position.

[0011] Preferably, I set1 with I set The difference is 0.1-0.4A, I set2 with I set1 The difference is 0.1-0.4A.

[0012] Preferably, the speed of the uniform motion is 1-5 μm / ms.

[0013] Preferably, the threshold current I reached in step S2 set1 The preset duration is 50-100ms, and the threshold current I is reached in step S4. set2 The default duration is 100-200ms.

[0014] A second aspect of the present invention provides a final stroke force control system for a Z-axis linear motor module of a placement machine, comprising: The speed loop control module is configured to switch the motor control from position loop control to speed loop control after the motor reaches a preset end position, so that the motor maintains a constant speed; The collision detection module is configured to monitor whether the real-time current value of the motor feedback reaches the threshold current I after passing through the speed loop control module. set1 And maintain the preset time length for collision detection, where I set1 Slightly higher than the theoretical current value I corresponding to the motor maintaining uniform motion set ; The collision confirmation module is configured to, after the collision detection module, if the real-time current value reaches I set1 If the preset time is maintained, the real-time current value is continuously monitored to see whether it reaches the threshold current I set2 And maintain the preset duration, I set2 >I set1 , perform collision confirmation; The curve planning module is configured to, after the collision confirmation module, if the real-time current value reaches I set2 If the real-time current value is reduced to less than I set1 , it is determined that no collision has occurred, and the collision detection module function is re-executed until the designated position is reached.

[0015] Preferably, the theoretical current value I set Meet the following conditions: K f *I set +mg=F f , where Kf is the linear motor thrust constant, m is the total mass of the motor secondary and the load, g is the gravity constant, F f The sum of the spring resistance on the Z axis and the structural resistance on the Z axis; F f It is obtained by calibration, specifically: selecting measurement points at the end interval, measuring the static current of the motor in the force balance state at each measurement point, and according to K f *I set +mg=F f The Z-axis structural resistance of each measurement point is calculated, and the calculation results are fitted to obtain an approximate curve to obtain the calibration results of the Z-axis structural resistance at different positions, where the spring resistance on the Z-axis is calculated according to the measurement position.

[0016] A third aspect of the present invention provides a motor driver, comprising: Linear motor drive module, used to drive the motor movement; Encoder position feedback module, used to obtain real-time position information of the motor; Phase current feedback module, used to obtain the real-time current of the motor; The MCU control module is used to receive the real-time position information fed back by the encoder position feedback module and the real-time current fed back by the phase current feedback module, and complete the steps of the above method through the linear motor drive module according to the real-time position information and the real-time current.

[0017] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program or instruction stored thereon, which, when executed by a processor, implements the end-of-stroke force control method for the Z-axis linear motor module of the placement machine as described above.

[0018] Through the above technical scheme, the technical scheme of the present invention is aimed at the Z-axis linear motor drive module, and utilizes the characteristics of the linear motor module that can more accurately estimate the thrust and load changes. The speed loop is used to control the uniform speed movement of the motor for precise force control, and the dynamic current threshold is set to perform two collision detections. Therefore, collision detection is achieved while force control is performed through speed loop control, without the need for additional sensors, meeting the requirements of mounting accuracy and compact structure; two collision detections are used at the cost of appropriately reducing the force control accuracy, thereby improving the accuracy of collision detection while reducing the collision intensity. Accurate collision detection results provide an accurate basis for motor force control, further promoting the accuracy of force control.

[0019] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings: Figure 1 This is a schematic diagram of the actual situation of the speed loop controlling uniform motion of the present invention; Figure 2 Schematic diagram of current threshold setting for two-stage collision detection according to an embodiment of the present invention; Figure 3 is a schematic diagram of feedback current when a collision occurs in an embodiment of the present invention; Figure 4 This is a flowchart of the application of the method of the embodiment of the present invention in the entire process. DETAILED DESCRIPTION

[0021] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0022] A first aspect of an embodiment of the present invention provides a method for controlling the final stroke force of a Z-axis linear motor module of a placement machine, comprising the following steps: S1: After reaching the preset end position, the motor control switches from position loop control to speed loop control to keep the motor moving at a constant speed. The Z-axis assembly of the placement head consists of two parts: the Z-axis linear motor module and the motor driver. The host computer sends specific motion instructions to the MCU control module through the communication interface. The MCU receives the feedback of the encoder position information and phase current to complete the calculation of the control algorithm, realizing the closed-loop control of the position loop, speed loop and current loop. Then, the motor drive unit realizes the inversion process, drives the Z-axis linear motor downward to the target position, and completes the process of sucking components or placing components.

[0023] During the downward movement of the Z-axis linear motor, it needs to drive the motor's secondary, nozzle rod, and spring to move downward, directly converting electrical energy into linear motion. A force analysis is performed on the entire motion process. The expected thrust can be obtained using the formula: F set =K f *I+mg-ma-F f ,in: F set : The expected thrust of the setting; K f : linear motor thrust constant; I: given current value, used to generate the desired motor thrust; m: total mass of the motor secondary and load; a: acceleration of the motor; F f : External resistance, including Z-axis structural resistance and Z-axis spring resistance.

[0024] Precision force control requires the expected thrust F of the motor set Assuming the external resistance F f Always keep constant. In the existing drive control scheme, the motor speed is constantly changing, and the acceleration and current will change rapidly, resulting in the actual F set It is impossible to accurately limit the force, which is inconsistent with the realization of precise force control. Therefore, the present invention provides a precise force control solution, which uses a speed loop control in the final section to give the motor a uniform speed, thereby ensuring that the motor's acceleration is always 0, thereby simplifying the above formula to obtain: F set =K f *I+mg-F f .

[0025] When the motor is in uniform motion, if the desired thrust F is set set remains unchanged, and the external resistance F f Since the load mass remains constant, the motor's set current value, I, can be easily calculated. This solution exploits the linear or fixed-value variation of the linear motor's external resistance by moving the motor at a constant speed. However, since the load cannot be accurately estimated in a Z-axis servo system implemented using a belt and drive pulley, this solution cannot accurately calculate the current. A more feasible solution is to directly drive the load of the Z-axis linear motor module through the linear motor and control the actual load thrust according to the set current.

[0026] When the SMT machine is picking up and placing components, force control can be performed within a few millimeters of travel at the end, effectively avoiding collisions while ensuring efficiency.

[0027] In summary, in actual operation, if the position loop is used to control the Z-axis motor to maintain a constant speed, the conventional curve planning method will cause the reference speed output by the motor position loop to change continuously because there is an error between the actual position of the motor and the expected target position. This will cause the actual running speed of the motor to change continuously. The change in speed will cause the acceleration to change continuously. The ma term cannot be directly ignored, and the acceleration is difficult to calculate accurately, making it difficult to directly obtain the expected F setTo ensure that acceleration a is as close to zero as possible, the final stage of motor operation is achieved by switching the motor from position control to velocity control, maintaining constant speed until the motor reaches its target position or a collision occurs. No further evaluation or analysis of the motor's position is required; the velocity loop alone ensures a near-constant motor speed. To prevent the high motor output force from causing a rapid drop in speed during a collision, generating reverse acceleration and resulting in a high actual collision intensity, the reference velocity should be set to a relatively low value, preferably between 1 and 5 µm / ms.

[0028] S2, monitor whether the real-time current value of the motor feedback reaches the threshold current I set1 And maintain the preset time length for collision detection, where I set1 Slightly higher than the theoretical current value I corresponding to the motor maintaining uniform motion set ; The actual situation of the speed loop controlling uniform motion is as follows Figure 1 As shown in the figure, the target position and speed at the current moment are calculated by the position loop curve. After the position loop controls the motor to reach the specified end, as shown in the figure, Figure 1 The switching point shown is when the force control judgment condition is reached, the speed loop control is turned on, and the target position is gradually approached at a low speed. At this time, the motor current I measure Basically presents a linear increase state. For example, at point A I measure is 0.8A, and at point B I measure If the fixed collision current detection threshold is 1.2A, the intensity of the collision at point A and the intensity of the collision at point B will be different due to the motor current I measure The thrust F generated is different in size set It is also inconsistent, which does not meet the requirements of precision force control. For the Z-axis linear motor module of the placement machine, it is necessary to consider the actual working and movement conditions, that is, for precision components, it is necessary to ensure that the collision intensity during placement is within a controllable range to avoid damaging the components. If you want to obtain a more accurate force control solution, you need to adopt dynamic current processing, that is, to ensure that the motor current I measure The difference between the current and the set collision detection threshold current is always fixed. For example, when the difference is 0.2A, the collision detection threshold at point A in the figure above is 1.0A, while the collision detection threshold at point B is 1.2A.

[0029] For the Z-axis linear motor module, the actual current calibration is feasible. In the stroke of the force control link, when the Z-axis moves downward at a low speed and uniform speed, according to the thrust calculation formula mentioned above, when the motor moves downward at a low speed and uniform speed, the motor is mainly affected by the load and the constant gravity of the secondary part, and external resistance, among which the external resistance F f Including spring tension F fspringand the structural resistance F fstructure Therefore, the motor current gradually increases as the Z-axis spring stretches. The weight of the load end, such as the nozzle rod, can be directly measured. fspring The dynamometer can be used to perform a simple calibration based on the actual stretching distance of the spring. For example, the elastic coefficient of the motor can be obtained by testing:

[0030] The elastic coefficient is about 0.033N / mm, and the thrust constant of the motor is K f This can be obtained from the motor's data sheet. The motor current corresponding to the spring's tension can be calculated based on the motor's actual position. For example, if the motor moves to the target position and the spring stretches an additional 60 mm, the corresponding spring tension is 2.52 N, and the stretching of the spring requires a motor current of approximately 0.32 A.

[0031] In the uniform speed running range, in addition to the spring tension F fspring In addition, the motor movement will also be affected by the Z-axis structural resistance F fstructure The influence of the structural resistance can also be obtained by calibration. Measure the static current of the motor at each position within the force control range. At this time, the motor is in a force balance state, F set Equal to 0, there is no additional downward thrust, that is, we get: K f ×I set +mg=F f =F fspring +F fstructure .

[0032] By this formula, the total external resistance F can be calculated f , the spring tension F fspring It can be calculated based on the calibration of the spring part, so the structural resistance F fstructure It can also be further calculated. It is preferred to measure at equal intervals, such as 0.1mm, 0.5mm, 1mm or 2mm, to ensure the reliability of the measurement, and finally fit a line about the resistance F of the entire force control stroke structure. fstructure Approximate curve of F. fstructure The fluctuation is very small during short-stroke, low-speed and uniform motion, but in order to ensure the performance of precise force control, this approximate curve needs to be used for calculation in actual motion.

[0033] In summary, the force conditions of the Z-axis linear motor module at each position within the force control stroke can be obtained relatively accurately. By setting the thrust, the corresponding theoretical current value I can be calculated. set , according to I set Set the dynamic current detection threshold I set1 Curve. At this time, I set1Only slightly higher than the actual motor current value, a rough comparison is performed for collision detection, exemplarily the expected motor thrust F set It can be set to 1N. If the motor is in ideal operation, the feedback current value of the motor should always be within the set current I set1 Below, as Figure 2 If a collision occurs, the motor feedback current should increase to the set current I set1 If it lasts for 50-100ms, such as 100ms, it enters collision detection phase 2.

[0034] S3, if the real-time current value reaches I set1 If the preset time is maintained, the real-time current value is continuously monitored to see whether it reaches the threshold current I set2 And maintain the preset time length to confirm the collision, I in different positions set2 with I set1 The difference is a fixed positive value.

[0035] S4, if the real-time current value reaches I set2 If the real-time current value is reduced to less than I set1 , it is determined that no collision has occurred, and step S2 is executed again until the designated position is reached.

[0036] The threshold current I is reached in step S2 set1 The preset time length is 50-100ms, which is used to ensure that the speed of the motor can be reduced to nearly 0 within the corresponding time when a collision or resistance occurs. set2 The preset time is 100-200ms, which is used to ensure effective judgment of motor collision or passing through abnormal resistance points.

[0037] In order to improve the reliability of collision detection, the present invention sets two current curves for collision detection for the Z-axis linear motor module, which can effectively improve the reliability of collision detection by slightly reducing the force control accuracy. set If the setting value is too small, the abnormal resistance of some axes may cause external interference to increase during the movement, resulting in an increase in the motor current, while the axis itself has not collided. This will lead to incorrect collision detection results and reduce the accuracy of the detection results. In order to improve the reliability of the detection, add collision detection stage 2. Figure 3 As shown, in the collision detection stage 2, the setting current I of stage 1 in step S2 is set1 On the basis of the set thrust, an additional 1N is added to reach the set current I set2According to the motion characteristics of the linear motor module of the placement head, if the motor is abnormal due to the resistance of the axis itself, the force I set2 It can ensure that the motor moves normally through the abnormal resistance point, and then the motor current will be reduced to below the set current I set1 , it can be considered that no collision occurred in the process, the motor is still moving normally, and the system returns to the collision detection stage 1, thereby greatly reducing the false triggering of the collision detection. Figure 2 As shown, if it is a normal collision when the component contacts the PCB, due to the contact resistance at the end, the current of the motor will continue to increase until it reaches the set current value I set2 And maintain for 100-200ms, preferably 200ms, at which time it is determined that the motor has collided, and then decelerates and stops. set1 with I set The difference, I set2 with I set1 The difference is 0.1-0.4A, preferably 0.1-0.2A.

[0038] The technical solution of the present invention uses a two-stage judgment method, which has the following advantages over a one-stage judgment method: directly using a single current threshold to perform a one-stage collision detection judgment cannot avoid misjudgment due to abnormal structural resistance. If a collision occurs, the feedback current of the motor will increase significantly higher than the single current threshold I. set1 , the motor speed is immediately reduced, resulting in a greater reverse acceleration of the motor, which in turn leads to the actual thrust F set1 The two-stage judgment is because the first stage only needs to judge whether the set current I is exceeded in a short time. set1 The next detection stage is to set the current value I set2 The motor current has a small single change. If the speed in the first stage is reduced to 0, the second stage will basically only bear the set thrust. The thrust will not be significantly increased due to rapid changes in acceleration and large set current. The two-stage judgment can minimize damage to precision components while not affecting the control accuracy. The above judgment scheme can minimize damage to precision components while not affecting the control accuracy.

[0039] After determining that the motor is in a collision process, because the motor itself moves at a constant speed at a relatively low speed and the current threshold of the collision detection is only slightly higher than the locking current at the collision position, the motor speed will not fluctuate significantly even if a collision occurs. The motor can directly decelerate and stop near the collision position, and then lock at the current position to quickly complete the entire collision detection stabilization process, without the need to adopt corresponding suppression strategies for speed fluctuations after the collision.

[0040] For example, the application process of the method of the embodiment of the present invention in the whole process is as follows: Figure 4 As shown: (1) Initial state: When the motion command is detected, the position loop control is entered and the state is switched to the motion parameter writing state; (2) Motion parameter writing status: In order to improve the flexibility of the precision force control mode configuration, some variables can be set as formal parameters for the above process and written through the host computer. For example: the default variables that need to be transmitted during the motor movement are the target position Order_Pos, the target maximum velocity Order_Vel, and the target maximum acceleration Order_Acc. The precision force control mode requires the following additional parameters: (1) First, the precision force control mode needs to be enabled. Only when the software receives the enable signal will the subsequent precision force control execution logic be triggered. Otherwise, it will still proceed according to normal point-to-point motion, and no collision process will be detected during the process; (2) Force control stroke Run_Pos: The recommended maximum stroke can reach 10mm. If the set value exceeds the actual stroke value, a precision force control solution is adopted for the entire stroke, that is, the entire stroke adopts a low uniform speed motion mode until it contacts the PCB surface and collides. The trigger position of the force control is set to target position 1, and the final position is set to target position 2; (3) Vel_Uniform for the uniform speed segment motion: It is recommended that the speed value remain fixed. If the speed allows the host computer to adjust, multiple sets of calibration processes may be required for the current at different speeds. The calibration process is relatively complicated. If it is for a certain use environment, such as the state of the Z-axis of the placement machine sucking and placing components, only a fixed speed is required; (4) The expected collision detection force F set2 With F set1 After receiving, the corresponding I is obtained through calculation set2 with I set1 The two sets of parameters serve as the boundaries of the two-step collision detection and execute the specific collision detection process; (5) Motor collision detection duration Touch_TimeSet, this parameter is recommended to remain fixed and judged according to the code logic. It is recommended that the detection time of the first segment be within 50-100ms and the detection time of the second segment be within 200-500ms. In theory, it is only necessary to ensure that the collision detection can be effectively performed within the designed stroke. The reliability and effectiveness of the actual detection process need to be evaluated based on the actual detection object, so the collision detection process can be directly judged; (3) Position loop curve planning calculation state: Through the position loop curve planning with terminal velocity, the key parameters of the curve planning are calculated, including the movement time and movement speed of each segment, and the movement acceleration and deceleration. After the calculation is completed, the motion state is entered; (4) Position loop motion state: Calculate the given values ​​of the motion process, including the planned speed, planned acceleration, and planned target position of the motor, complete the entire curve planning process to the target position 1, and then execute the speed loop control according to the final speed of the curve planning; (5) Speed ​​loop motion state: In this stage, the motor will move downward at a low and uniform speed, and will perform collision judgment through two-stage current detection. If a collision is detected, it will enter the collision completion stop state. If no collision occurs, it will enter the curve planning completion position judgment state. (6) Curve planning completion judgment state: This state is when the current motion position of the motor has reached the final target position 2, and the state machine exits after reaching it; (7) Collision completion state: This state is the state where the collision has been detected and the motor collision has ended. The speed has basically stabilized near 0, the motor is directly locked to the current position, and the entire movement process is completed.

[0041] Based on the same inventive concept, a second aspect of an embodiment of the present invention provides a final stroke force control system for a Z-axis linear motor module of a placement machine, comprising: The speed loop control module is configured to switch the motor control from position loop control to speed loop control after the motor reaches a preset end position, so that the motor maintains a constant speed; The collision detection module is configured to monitor whether the real-time current value of the motor feedback reaches the threshold current I after passing through the speed loop control module. set1 And maintain the preset time length for collision detection, where I set1 Slightly higher than the theoretical current value I corresponding to the motor maintaining uniform motion set ; The collision confirmation module is configured to, after the collision detection module, if the real-time current value reaches I set1 If the preset time is maintained, the real-time current value is continuously monitored to see whether it reaches the threshold current I set2 And maintain the preset duration, I set2 >I set1 , perform collision confirmation; The curve planning module is configured to, after the collision confirmation module, if the real-time current value reaches I set2 If the real-time current value is reduced to less than I set1 , it is determined that no collision has occurred, and the collision detection module function is re-executed until the designated position is reached.

[0042] Furthermore, the theoretical current value I set Meet the following conditions: K f *I set +mg=F f, where K f is the linear motor thrust constant, m is the total mass of the motor secondary and the load, g is the gravity constant, F f The sum of the spring resistance on the Z axis and the structural resistance on the Z axis; F f It is obtained by calibration, specifically: selecting measurement points at the end interval, measuring the static current of the motor in the force balance state at each measurement point, and according to K f *I set +mg=F f The Z-axis structural resistance of each measurement point is calculated, and the calculation results are fitted to obtain an approximate curve to obtain the calibration results of the Z-axis structural resistance at different positions, where the spring resistance on the Z-axis is calculated according to the measurement position.

[0043] According to a third aspect of an embodiment of the present invention, a motor driver is provided, comprising: Linear motor drive module, used to drive the motor movement; Encoder position feedback module, used to obtain real-time position information of the motor; Phase current feedback module, used to obtain the real-time current of the motor; The MCU control module is used to receive the real-time position information fed back by the encoder position feedback module and the real-time current fed back by the phase current feedback module, and complete the steps of the final force control method of the Z-axis linear motor module of the above-mentioned placement machine through the linear motor drive module according to the real-time position information and the real-time current.

[0044] A fourth aspect of an embodiment of the present invention provides a computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed by a processor, a method for controlling the end-of-stroke force of a Z-axis linear motor module of a placement machine is implemented.

[0045] To sum up, the technical solution of the present invention is aimed at the Z-axis linear motor drive module. It utilizes the characteristics of the linear motor module that can more accurately estimate the thrust and load changes, adopts the speed loop to control the uniform motion of the motor for precise force control, and sets the dynamic current threshold to perform two collision detections. Therefore, while force control is performed through speed loop control, collision detection is achieved at the same time, without the need for additional sensors, meeting the requirements of mounting accuracy and compact structure; two collision detections are adopted at the cost of appropriately reducing the force control accuracy, thereby improving the accuracy of collision detection while reducing the collision intensity. Accurate collision detection results provide an accurate basis for motor force control, further promoting the accuracy of force control.

[0046] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such process, method, commodity, or apparatus.

[0047] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for controlling the final force of a Z-axis linear motor module of a placement machine, characterized in that: The following steps are involved: S1: After reaching the preset end position, the motor control switches from position loop control to speed loop control to keep the motor moving at a constant speed. S2, monitor whether the real-time current value of the motor feedback reaches the threshold current I set1 And maintain the preset time length for collision detection, where I set1 The theoretical current value I corresponding to the motor maintaining uniform motion set The difference is a fixed positive value; S3, if the real-time current value reaches I set1 If the preset time is maintained, the real-time current value is continuously monitored to see whether it reaches the threshold current I set2 And maintain the preset time length to confirm the collision, I in different positions set2 with I set1 The difference is a fixed positive value; S4, if the real-time current value reaches I set2 If the collision lasts for a preset period of time, it is determined that a collision has occurred; If the real-time current value decreases to less than I set1 , it is determined that no collision has occurred, and step S2 is executed again until the designated position is reached.

2. The method according to claim 1, characterized in that Theoretical current value I set Meet the following conditions: K f *I set +mg=F f , where K f is the linear motor thrust constant, m is the total mass of the motor secondary and the load, F f It is the sum of the spring resistance on the Z axis and the structural resistance on the Z axis, and g is the gravity constant.

3. The method according to claim 2, characterized in that F f It is obtained by calibration, specifically: selecting measurement points at the end interval, measuring the static current of the motor in the force balance state at each measurement point, and according to K f *I set +mg=F f The Z-axis structural resistance of each measurement point is calculated, and the calculation results are fitted to obtain an approximate curve to obtain the calibration results of the Z-axis structural resistance at different positions, where the spring resistance on the Z-axis is calculated according to the measurement position.

4. The method according to claim 3, characterized in that I set1 with I set The difference is 0.1-0.4A, I set2 with I set1 The difference is 0.1-0.4A.

5. The method according to any one of claims 1 to 4, characterized in that: The speed of the uniform motion is 1-5 μm / ms.

6. The method according to claim 5, characterized in that The threshold current I is reached in step S2 set1 The preset duration is 50-100ms, and the threshold current I is reached in step S4. set2 The default duration is 100-200ms.

7. A final stroke force control system for a Z-axis linear motor module of a placement machine, characterized in that: include: The speed loop control module is configured to switch the motor control from position loop control to speed loop control after the motor reaches a preset end position, so that the motor maintains a constant speed; The collision detection module is configured to monitor whether the real-time current value of the motor feedback reaches the threshold current I after passing through the speed loop control module. set1 And maintain the preset time length for collision detection, where I set1 Slightly higher than the theoretical current value I corresponding to the motor maintaining uniform motion set ; The collision confirmation module is configured to, after the collision detection module, if the real-time current value reaches I set1 If the preset time is maintained, the real-time current value is continuously monitored to see whether it reaches the threshold current I set2 And maintain the preset duration, I set2 >I set1 , perform collision confirmation; The curve planning module is configured to, after the collision confirmation module, if the real-time current value reaches I set2 If the collision lasts for a preset period of time, it is determined that a collision has occurred; If the real-time current value decreases to less than I set1 , it is determined that no collision has occurred, and the collision detection module function is re-executed until the designated position is reached.

8. The system according to claim 7, characterized in that Theoretical current value I set Meet the following conditions: K f *I set +mg=F f , where K f is the linear motor thrust constant, m is the total mass of the motor secondary and the load, g is the gravity constant, F f The sum of the spring resistance on the Z axis and the structural resistance on the Z axis; F f It is obtained by calibration, specifically: selecting measurement points at the end interval, measuring the static current of the motor in the force balance state at each measurement point, and according to K f *I set +mg=F f The Z-axis structural resistance of each measurement point is calculated, and the calculation results are fitted to obtain an approximate curve to obtain the calibration results of the Z-axis structural resistance at different positions, where the spring resistance on the Z-axis is calculated according to the measurement position.

9. A motor driver, characterized in that: include: Linear motor drive module, used to drive the motor movement; Encoder position feedback module, used to obtain real-time position information of the motor; Phase current feedback module, used to obtain the real-time current of the motor; The MCU control module is used to receive the real-time position information fed back by the encoder position feedback module and the real-time current fed back by the phase current feedback module, and complete the steps of the method as claimed in claim 1 through the linear motor drive module according to the real-time position information and the real-time current.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program or instruction, and when the computer program or instruction is executed by the processor, the final stroke force control method of the Z-axis linear motor module of the placement machine as described in any one of claims 1-6 is implemented.

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