Pick-and-place machine nozzle collision detection method, motor driver, medium

Abstract

The present invention relates to the field of motor control technology, and discloses a method for detecting collision of a nozzle of a placement machine, a motor driver, and a medium. The method comprises the following steps: after driving the nozzle to move to a specified position, the current speed and motor current are obtained in real time. If the difference between the current speed and the planned speed is greater than a preset threshold a and drops to 0, it is determined that a collision occurs; otherwise, if the motor current suddenly changes to a set maximum value, when the maximum value is maintained for more than a set time a and the motor displacement fluctuation amplitude is less than a threshold c, it is determined that a collision occurs. This solution only requires current and speed detection to achieve fast and accurate judgment of devices with complex systems and weight-sensitive components such as placement heads. The placement efficiency of the placement machine will not be significantly affected by the excessively long collision detection time, and there is no need to use additional components such as force sensors, which greatly reduces the requirements for the structure.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a nozzle collision detection method for a placement machine, a motor driver, and a medium. Background Art

[0002] During the placement process of the SMT machine, multiple parts need to coordinate their movements to complete the component suction, component identification and component placement process. The Z axis on the placement head module not only needs to use the suction nozzle to realize the process of sucking components from the feeder or automatic tray, but also needs to complete the placement of components on the circuit board. Due to the bending of the board itself and the difference in thickness of different components that may occur on complex circuit boards, the Z axis will 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 problem of suction and placement failure is prone to occur. When the Z axis descent height is set to a large value, it is easy to cause a significant collision of the Z axis, damaging the components or the suction nozzle.

[0003] At present, the collision detection of servo systems on the market mainly adopts the method of current monitoring or force sensor, which evaluates the change of load under different motion conditions and compares it with the set load threshold to determine whether a collision occurs. For example, patent CN118010283A discloses a collision detection method for a servo system, which mainly estimates the load torque through the position and moment of inertia of the motor, compares the load torque with the torque threshold, and the difference between the feedback position and the command position to determine whether the motor has collided; patent CN118596033A discloses a servo force control constant control method, which compares the pressure value of the pressure sensor after a collision contact occurs, adjusts the output torque of the servo motor, and achieves constant pressure.

[0004] However, the existing technologies have shortcomings in the application of nozzles in SMT machines. The Z axis of the placement head adopts a transmission method of synchronous wheel + belt + rack, and a spring is used to ensure that the Z axis naturally rebounds to a safe height. Affected by the spring force, friction, etc., the load torque estimation on this complex system is not accurate, and will change significantly with structural changes, and the scheme recognition accuracy is not high; although adding a force sensor can quickly and accurately identify, the cost will increase greatly, and the structure of the placement head needs to be redesigned, which will lead to a further increase in the weight of the placement head.

[0005] Therefore, there is a lack of a solution that can accurately and quickly identify the collision of the suction nozzle without adding additional costs and adjusting the structure. Summary of the invention

[0006] In order to solve the problems in the prior art, the purpose of the embodiments of the present invention is to provide a placement machine nozzle collision detection method, motor driver, and medium, which can accurately and quickly identify the collision of the nozzle without increasing additional costs and adjusting the structure.

[0007] In order to achieve the above-mentioned object, a first aspect of an embodiment of the present invention provides a nozzle collision detection method for a placement machine, comprising the following steps:

[0008] After driving the nozzle to the specified position, the current speed and motor current are obtained in real time.

[0009] If the difference between the current speed and the planned speed is greater than the preset threshold a and drops to 0, a collision is judged to have occurred; otherwise, if the motor current suddenly changes to reach the set maximum value, when the maximum value is maintained for more than the set time a and the motor displacement fluctuation amplitude is less than the threshold c, a collision is judged to have occurred.

[0010] Preferably, if the difference between the current speed and the planned speed is greater than a preset threshold and drops to 0, it is determined that a collision has occurred and the second stage of collision detection is entered: the speed loop and the position loop are removed, and the nozzle is driven to move by a single current loop control method to reduce the rebound amplitude of the nozzle after the collision.

[0011] Preferably, when the motor speed changes from negative to positive for the first time, the third stage of collision detection is entered. After detecting that the motor speed is lower than the threshold b and lasts for b, the current position is locked and the locked position is updated to the final target position. The velocity feedforward and acceleration feedforward are both set to 0 until the position of the motor stabilizes at the locked position and the entire motion process ends.

[0012] Preferably, the current of the third stage of collision detection is greater than the planned current corresponding to the locking position and less than the current of the second stage of collision detection. The current of the second stage of collision detection is greater than the planned current corresponding to the position of the second stage of collision detection and less than the current of the first stage of collision detection. The first stage of collision detection refers to the stage from driving the suction nozzle to the specified position to entering the second stage of collision detection. The planned current is the actual measured current of the motor at different positions.

[0013] Preferably, the motor current suddenly changes to a set maximum value. When the maximum value is maintained for more than a set time a and the motor displacement fluctuation amplitude is less than a threshold value c, it is determined that a collision has occurred and the third stage of collision detection is directly entered.

[0014] Preferably, the method is implemented based on current loop control of a servo motor.

[0015] Preferably, the method further comprises curve planning of the entire motion process, which is realized based on the position loop control of the servo motor, comprising the following steps:

[0016] After detecting the motion command, it enters the position loop control and switches the state to the motion parameter writing state;

[0017] In the motion parameter writing state, it is determined whether the preset target position exceeds the maximum boundary of the motion, if not, the total distance of the motion is divided to determine the designated position, and the initial parameters of the motion are written;

[0018] Calculate the key parameters of curve planning according to the initial parameters of the motion, including the motion time, motion speed and acceleration of each segment. After the calculation is completed, enter the motion state to drive the nozzle to move;

[0019] The planned speed, planned acceleration and planned target position of the motor are calculated and updated in real time according to the motor motion state, and the suction nozzle is driven to move to the preset target position.

[0020] Preferably, during the curve planning process, when the suction nozzle is driven to move to the specified position, collision detection is started. If no collision occurs and the final position reached by the motor is within a specified range from the preset target position, the curve planning is considered to be completed.

[0021] A second aspect of an embodiment of the present invention provides a motor driver, comprising:

[0022] Servo motor drive module, used to drive the motor movement;

[0023] Encoder position feedback module, used to obtain real-time position information of the motor;

[0024] Phase current feedback module, used to obtain the real-time current of the motor;

[0025] 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, complete the steps of the above method according to the real-time position information and the real-time current, realize motor control, and realize the inversion process through the servo motor drive module, so that the motor drives the suction nozzle to move downward.

[0026] A third aspect of an embodiment of the present invention provides a computer-readable storage medium, on which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, the above-mentioned collision detection method is implemented.

[0027] Through the above technical solution, only current and speed detection are needed to achieve fast and accurate judgment on devices with complex systems and weight-sensitive components such as placement heads. The placement efficiency of the placement machine will not be significantly affected due to excessively long collision detection time, and there is no need to use additional components such as force sensors, which greatly reduces the requirements for the structure.

[0028] 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

[0029] 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 specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0030] Figure 1 It is a schematic diagram of the structure of the Z-axis assembly of the chip mounter of the present invention;

[0031] Figure 2 This is a schematic diagram of the travel of the motor in the embodiment of the present invention when the motor normally completes the entire curve planning process and is not subject to collision during the movement process;

[0032] Figure 3 It is a schematic diagram of the travel of the motor subjected to collision during the entire curve planning process according to an embodiment of the present invention;

[0033] Figure 4 It is a schematic diagram of the speed of the motor when it is hit during the entire curve planning process;

[0034] Figure 5 is a flow chart of a nozzle collision detection method for a chip placement machine according to an embodiment of the present invention;

[0035] Figure 6 It is a logic flow chart of the motor position loop control according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here 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.

[0037] The schematic diagram of the Z-axis assembly of the placement machine is shown in Figure 1. The Z-axis assembly of the placement head includes two parts: the Z-axis structure 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 encoder position information and phase current to complete the calculation of the control algorithm, and realizes the closed-loop control of the position loop, speed loop and current loop. Then, the servo motor drive unit realizes the inversion process, drives the Z-axis motor to move downward to the target position, and completes the process of sucking components or placing components.

[0038] The Z-axis motor needs to drive the belt, slider assembly, nozzle rod and spring to move downward during the downward movement. The force analysis of the entire movement process is performed, and the maximum current set in the collision detection stage is defined as I max , the torque of the motor is defined as F n The total weight of the slider assembly, nozzle rod, nozzle and other transmission parts is F g , the tension of the spring is Ft If the motor moves downward, it is necessary to ensure F n - F g - F t >0. As the downward movement distance increases, the upward spring force F t Increase, the motor needs to provide greater torque, that is, the motor needs to generate greater current, when the nozzle comes into contact with the PCB board, reverse resistance will be generated at this time F , the resistance F As the deformation of the movement gradually increases, the speed of the motor will decrease rapidly, and the thrust of the motor will F n Will further increase until the maximum motion current I max , when the speed drops to 0, the force on the motor system becomes: F n ( I max ) - F g - F t - F= 0.

[0039] At this time, the motor is in a balanced state, so two aspects need to be considered in the actual detection process. One is that the speed of the motor quickly drops to 0 during normal movement, and the other is that the current of the motor reaches the maximum movement current and maintains it for a period of time. When the above two situations occur, it is considered that a collision has occurred.

[0040] When the Z-axis motor is locked, it can be considered that the motor is in a stable state and the force is balanced. The current at the force balance point is taken and amplified appropriately. This current can ensure that the motor moves downward for a certain distance without damaging the device due to a rapid increase in current caused by a collision. During the entire Z-axis downward movement process, only the end distance needs to be collided. The following example takes the last 20% of the entire stroke for collision detection. It can also be adjusted to different proportions such as 40%, 30%, 10% or 5% of the entire stroke according to actual production conditions. Therefore, the movement process of Z-axis placement can be divided into two types:

[0041] In the first category, when no collision occurs, the motor completes the entire curve planning process normally, and the motion process is not affected by the collision detection strategy. This process needs to ensure the appropriate value of the current, and the original motion curve will not be affected by the too small current setting value. The specific motion process is as follows Figure 2 shown.

[0042] In the second type, when a collision occurs, the system will detect changes in the motor speed or current. When the corresponding changes are detected, the maximum current of the motor will be limited in stages. After the collision process is completed, the speed fluctuations in the collision will be quickly suppressed, and the motor will be locked in the current position after it stabilizes. The specific movement process is as follows Figure 3 As shown, the speed corresponding to the motion process is Figure 4 shown.

[0043] Based on the above principle, a first aspect of an embodiment of the present invention provides a nozzle collision detection method for a placement machine. Example 1

[0044] A method for detecting collision of a nozzle of a placement machine comprises the following steps:

[0045] After driving the nozzle to the specified position, the current speed and motor current are obtained in real time.

[0046] If the difference between the current speed and the planned speed is greater than the preset threshold a and drops to 0, a collision is judged to have occurred; otherwise, if the motor current suddenly changes to reach the set maximum value, when the maximum value is maintained for more than the set time a and the motor displacement fluctuation amplitude is less than the threshold c, a collision is judged to have occurred.

[0047] Exemplarily, the preset threshold a is preferably 2-3 times the lead equivalent (lead equivalent: the distance the nozzle moves corresponding to one circle of motor movement). For example, if the lead equivalent in this example is 36000µm, the corresponding threshold a is preferably 72000µm / s, and the time a is set at the ms level. Exemplarily, the set time a is 1-20ms, preferably 5ms. The state in which the motor displacement fluctuation amplitude is less than the threshold c means that the distance between the motor and the target position remains basically unchanged, that is, a certain degree of jitter and displacement fluctuation can be ignored.

[0048] The above scheme only needs to detect current and speed to achieve fast and accurate judgment on devices with complex systems and weight sensitivity such as placement heads. It will not have a significant impact on the placement efficiency of the placement machine due to excessively long collision detection time, and there is no need to use additional components such as force sensors, which greatly reduces the requirements for the structure. Example 2

[0049] In another embodiment of the present invention, a nozzle collision detection method for a placement machine is implemented based on the current loop control of a servo motor, such as Figure 5 As shown, the following steps are included:

[0050] S1: After driving the nozzle to the specified position, it enters the first stage of collision detection and obtains the current speed and motor current in real time;

[0051] like Figure 5As shown, first, it is determined whether the motor performs collision detection in the default "initial state". If the motor does not execute the suction or placement instructions, that is, the motor is in the "normal motion state", the motor current is not limited, and it still runs according to the system default maximum parameters, and the collision that occurs in the middle is not detected.

[0052] When the vehicle reaches the designated position and starts to perform collision detection, two sets of detection conditions will be executed, one set is based on speed detection, and the other set is based on current detection, which are used to determine two different degrees of collision detection. These two sets of detections need to satisfy that the difference between the current position and the target position is greater than the distance to the target position, otherwise the natural positioning process will be directly executed without performing the collision detection process.

[0053] S2. If the difference between the current speed and the planned speed is greater than the preset threshold a and drops to 0, it is determined that a collision occurs and the second stage of collision detection is entered: the speed loop and the position loop are removed, and the nozzle is driven to move by the control method of a single current loop to reduce the rebound amplitude of the nozzle after the collision; otherwise, it goes to step S4;

[0054] The speed detection process is less sensitive than the current, so it is only used to detect collisions at high speeds and at a certain distance from the target position. The judgment condition is that when the curve planning is not completed, the current position of the motor is still a certain distance from the target position. When the curve planning speed is greater than 2 to 3 times the lead equivalent (lead equivalent: the distance the nozzle moves for one circle of the motor), there is a process where the speed changes from positive to negative (i.e. the nozzle rebound process), and there is a significant difference between the curve planning speed and the actual feedback current speed. It can be considered that a significant collision has occurred, causing the speed to quickly drop to 0, such as Figure 4 As shown in the figure, the speed drops quickly from the collision point to 0. Because the collision occurs at a large speed and acceleration, a certain degree of rebound will occur. Figure 3 As shown, at this time, from the first stage of collision detection (i.e. Figure 3 The "collision detection judgment collision" stage shown in the figure) enters the second stage of collision detection (i.e. Figure 3 The second stage of collision detection is actually the suppression of the speed rebound process after an obvious collision: Figure 4 As shown, the motor speed changes to move in the opposite direction. It is necessary to minimize the speed fluctuation time. Therefore, the speed loop and position loop are removed, and only a single current loop is used to quickly and directly apply a downward force so that the motor obtains a downward acceleration. Then the upward speed will be decayed to 0 more quickly. When it is detected that the speed changes from negative to positive (the direction of movement of the nozzle to the mounting point is positive, and the direction of rebound is negative), it is considered that this stage is over, and the collision detection stage 2 enters the collision detection stage 3 ( Figure 3 “Speed ​​recovery” phase shown).

[0055] S3, when the motor speed changes from negative to positive for the first time, it enters the third stage of collision detection. When the motor speed is detected to be lower than the threshold value b and lasts for b, the current position is locked and the locked position is updated to the final target position, and the in-place locking motor stage is entered: the velocity feedforward and acceleration feedforward are both set to 0, until the motor position stabilizes at the locked position, and the entire motion process ends.

[0056] Exemplarily, threshold b is preferably 0.5-1 times the lead equivalent (lead equivalent: the distance the nozzle moves corresponding to one circle of motor movement). For example, if the lead equivalent in this example is 36000µm, the corresponding threshold a is preferably 18000µm / s. Duration b is preferably 2-5ms. The third stage of collision detection will limit the motor current. The motor current uses the set third stage current value of collision detection. When the motor speed is lower than 0.5 to 1 times the lead equivalent and lasts for a period of time, it is considered that the motor has stabilized at the current position with only small speed fluctuations. The current position is updated to the final target position of the motor and locked at this position.

[0057] S4. If the motor current suddenly changes to the set maximum value, when the maximum value is maintained for more than the set time a and the motor displacement fluctuation amplitude is less than the threshold c, it is judged that a collision has occurred, the current position is locked and the locked position is updated to the final target position, and the collision detection is directly entered into the third stage from the first stage of collision detection.

[0058] The current detection process of step S4 is aimed at the situation that the curve planning is about to end and the motor moves to a position close to the target. The curve planning is about to end. Even if a slight collision occurs, the speed change of the motor is not obvious at this time, and the speed judgment condition is not reliable. However, because the target position cannot be reached, the current of the motor will increase significantly until the maximum current of the first stage of collision detection is reached. When the time for maintaining the maximum current is greater than the set time, the current detection cycle is usually consistent with the operating frequency of the current loop, and the stall judgment time is relatively long and is set at the ms level. During the detection time, the motor basically does not move, that is, the motor is in a state close to stall. It can be considered that the motor has collided, and the motor speed is low. There is no need to consider the process of suppressing speed rebound, and the collision detection can be directly changed from the first stage of collision detection to the third stage of collision detection.

[0059] The current of the third stage of collision detection is greater than the planned current corresponding to the locked position and less than the current of the second stage of collision detection. The current of the second stage of collision detection is greater than the planned current corresponding to the position of the second stage of collision detection and less than the current of the first stage of collision detection. The first stage of collision detection refers to the stage from driving the nozzle to the specified position to entering the second stage of collision detection. The planned current is the measured current of the motor at different positions. When the nozzle moves to different positions, the current of the motor is in the locked state until the corresponding position is reached. The interval of each measurement position can be set to 5mm to 10mm to obtain the corresponding linear fitting relationship between the current and the position. The fitting relationship is obtained before the implementation of the method of the present invention. In this implementation, based on the fitting relationship, the corresponding measured current can be directly called according to the position.

[0060] By combining the speed and current joint collision detection scheme, the collision process can be accurately and quickly detected and suppressed without affecting the normal movement process. On this basis, segmented current control and single current loop control are added to suppress the speed waveform after the collision, reduce the time to restore stability after the collision, and ensure the success rate of placement and suction without affecting the production efficiency of the machine; and because the maximum current is limited, even if a collision occurs, it will not affect the placement process of the nozzle, and will not cause damage to the components or nozzle due to excessive current. Example 3

[0061] In another embodiment of the present invention, a nozzle collision detection method for a placement machine further includes curve planning for the entire motion process, which is implemented based on the position loop control of the servo motor. Figure 6 As shown, the following steps are included:

[0062] (1) Initial state: After detecting the motion command, the position loop control is entered and the state is changed to the motion parameter writing state;

[0063] (2) Motion parameter writing state: In the motion parameter writing state, it is determined whether the preset target position exceeds the maximum boundary of the motion. If not, the total distance of the motion is divided to determine the specified position, and the initial parameters of the motion are written;

[0064] like Figure 2 and Figure 3 The "position control phase curve planning" shown is the entire movement of the nozzle, exemplarily taking 80% of the front stroke and 20% of the rear stroke. No collision detection is performed in the front stroke, and the intersection of the front stroke and the rear stroke is the specified position.

[0065] (3) Calculate the key parameters of curve planning based on the initial parameters of the motion, including the motion time, motion speed and acceleration of each segment. After the calculation is completed, enter the motion state to drive the nozzle to move;

[0066] (4) Motion state: The planned speed, planned acceleration and planned target position of the motor are calculated and updated in real time according to the motor motion state, and the suction nozzle is driven to move to the preset target position.

[0067] Step (4) involves Figure 2 or Figure 3 The curve planning method involved in the whole motion process shown is based on the existing technology, such as patent CN114740806A or patent CN114879609A. During the motion state, it will be determined whether the motion reaches the specified position, thereby starting the collision detection method in the above embodiment 1 or embodiment 2. If no collision is detected, it will be executed until the curve planning is completed. Figure 2 As shown, the curve planning is completed and the position determination state is entered, and step (5) is entered; if a collision is detected and the motor collision is completed, step (6) is entered.

[0068] Curve planning completion judgment state: In this state, the motor's curve planning has been completed, and the motor can reach the planned target position normally without collision.

[0069] For example, if the error range between the target position and the current position is within 100µm, it is considered that the curve planning has been completed, the Z axis has completed the placement movement normally, and the state machine is exited to wait for the next movement instruction.

[0070] Collision completed 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, and the motor is directly locked to the current position, such as Figure 3 The whole motion process is shown as follows. Since the operating frequency of the current loop is much higher than that of the position loop, the collision detection logic is implemented in the current loop in consideration of accuracy and speed.

[0071] The position loop will determine when to start collision detection and write the corresponding configuration parameters. In the position loop control, the maximum current of different motion stages will be divided. First, the maximum current of the first stage of collision detection during the placement and absorption process is defined, and the current is obtained through actual measurement. Because collision detection is only performed in the second half of the stroke, it is sufficient to use the curve to plan the maximum current of the deceleration section. This is also the current that ensures that the motor can be in place normally when no collision occurs, and at the same time avoids the collision intensity caused by the set current being too large when a collision occurs. When the nozzle moves to different positions, the motor is in a locked state until the corresponding current is measured. The interval of each measurement position can be set to 5mm to 10mm, and the corresponding linear fitting relationship between the current and the position is obtained. The fitting relationship is obtained before the implementation of the method of the present invention. In the implementation, based on the fitting relationship, the corresponding measured current can be directly called according to the position. Preferably, the planned current at the corresponding position in the first stage of collision detection is increased relative to the measured current, and the increase is set at 20% to 30%, which is used to suppress the speed fluctuation from the end of the collision to the stable stage, and as the current to restore the stable state after the end of the collision in the third stage of collision detection. At the same time, in order to solve the problem that the motor speed fluctuates greatly when a significant collision occurs and the speed is reversed after the collision, it is necessary to quickly decelerate the motor after the collision, and set the second-stage current of the collision detection. The second-stage current of the collision detection is obtained by increasing the third-stage current of the collision detection by a certain amplitude, and the setting range needs to be smaller than the current setting value of the first stage of the collision detection and larger than the current setting value of the third stage of the collision detection. The current settings of each stage in Example 1 and Example 2 are similar.

[0072] This collision detection solution does not require the addition of force sensors. It can achieve accurate and rapid collision detection through composite monitoring of current and speed, and limit and process the collision current in stages after the collision. It can solve the problem of high sensitivity to placement in the actual production process of the placement machine, reduce damage to components or nozzles in collisions, and does not affect the placement efficiency.

[0073] Based on the same inventive concept, a second aspect of an embodiment of the present invention provides a motor driver, such as Figure 1 As shown, including:

[0074] Servo motor drive module, used to drive the motor movement;

[0075] Encoder position feedback module, used to obtain real-time position information of the motor;

[0076] Phase current feedback module, used to obtain the real-time current of the motor;

[0077] 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, complete the steps of the above method according to the real-time position information and the real-time current, realize motor control, and realize the inversion process through the servo motor drive module, so that the motor drives the suction nozzle to move downward.

[0078] The solution of the present invention judges the above two states only through feedback speed and feedback current during the motor control process. The speed is obtained through the feedback position encoder, and the feedback current is obtained through analog-to-digital conversion chip sampling. Without the need to increase additional costs and adjust the structure, the collision process of the suction nozzle can be accurately and quickly identified and the force and speed fluctuation degree of the collision can be suppressed, thereby effectively reducing the impact on the production efficiency of the placement machine.

[0079] Based on the same inventive concept, a third aspect of an embodiment of the present invention provides a computer-readable storage medium, on which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, the above-mentioned collision detection method is implemented.

[0080] In summary, by using a joint collision detection scheme of speed and current, and adding segmented current control and single current loop control to suppress the speed waveform after the collision, the time to recover stability after the collision is reduced, while not affecting the production efficiency of the machine, the success rate of placement and absorption is guaranteed; for devices with complex systems and weight-sensitive devices such as placement heads, accurate and fast collision detection can be achieved without the use of additional components such as force sensors, which greatly reduces the requirements for the structure.

[0081] 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 explicitly listed, or also includes elements inherent to such process, method, commodity, or apparatus.

[0082] The above are only 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 modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for detecting collision of a nozzle of a placement machine, characterized in that: The following steps are involved: S1, after driving the nozzle to the specified position, obtain the current speed and motor current in real time. S2, if the difference between the current speed and the planned speed is greater than the preset threshold a and drops to 0, it is determined that a collision occurs, otherwise it goes to step S3; if the difference between the current speed and the planned speed is greater than the preset threshold a and drops to 0, it is determined that a collision occurs, and then the second stage of collision detection is entered: the speed loop and the position loop are removed, and the nozzle is driven to move by the control method of a single current loop to reduce the rebound amplitude of the nozzle after the collision. When the motor speed changes from negative to positive for the first time, the third stage of collision detection is entered. After detecting that the motor speed is lower than the threshold b and the duration is b, the current position is locked and the locked position is updated to the final target position, and the speed feedforward and acceleration feedforward are both set to 0 until the position of the motor is stabilized at the locked position, and the entire movement process ends; S3. If the motor current suddenly changes to the set maximum value, when the maximum value is maintained for more than the set time a and the motor displacement fluctuation amplitude is less than the threshold c, it is determined that a collision has occurred. After that, the third stage of the collision detection is directly entered. After detecting that the motor speed is lower than the threshold b and the duration is b, the current position is locked and the locked position is updated to the final target position. The speed feedforward and acceleration feedforward are both set to 0 until the position of the motor is stabilized at the locked position and the entire movement process ends.

2. The method according to claim 1, characterized in that The current of the third stage of collision detection is greater than the planned current corresponding to the locking position and less than the current of the second stage of collision detection. The current of the second stage of collision detection is greater than the planned current corresponding to the position of the second stage of collision detection and less than the current of the first stage of collision detection. The first stage of collision detection refers to the stage from driving the suction nozzle to the specified position to entering the second stage of collision detection. The planned current is the actual measured current of the motor at different positions.

3. The method according to claim 1 or 2, characterized in that: The method is implemented based on the current loop control of the servo motor.

4. The method according to claim 3, characterized in that The method also includes curve planning for the entire motion process, which is implemented based on the position loop control of the servo motor and includes the following steps: After detecting the motion command, it enters the position loop control and switches the state to the motion parameter writing state; In the motion parameter writing state, it is determined whether the preset target position exceeds the maximum boundary of the motion, if not, the total distance of the motion is divided to determine the designated position, and the initial parameters of the motion are written; Calculate the key parameters of curve planning according to the initial parameters of the motion, including the motion time, motion speed and acceleration of each segment. After the calculation is completed, enter the motion state to drive the nozzle to move; The planned speed, planned acceleration and planned target position of the motor are calculated and updated in real time according to the motor motion state, and the suction nozzle is driven to move to the preset target position.

5. The method according to claim 4, characterized in that During the curve planning process, when the suction nozzle is driven to move to the specified position, collision detection is started. If no collision occurs and the final position reached by the motor is within a specified range from the preset target position, the curve planning is considered to be completed.

6. A motor driver, characterized in that: include: Servo motor drive module, used to drive the motor movement; Encoder position feedback module, used to obtain the 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, complete the steps of the method as claimed in claim 1 according to the real-time position information and the real-time current, realize motor control, and realize the inversion process through the servo motor drive module, so that the motor drives the suction nozzle to move downward.

7. 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 a processor, the collision detection method according to any one of claims 1 to 5 is implemented.

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