Motor control method applied to press production

Abstract

The application relates to a motor control method applied to a rivet production, which comprises the following steps: firstly, the relationship curve between the torque and the speed of the motor is obtained from the mechanical characteristics of the motor, and the optimal acceleration control curve is determined; secondly, the motor is adjusted to the speed control mode, the position of the motor is controlled to the pre-detection position based on the optimal acceleration control curve; the speed of the motor is adjusted to a lower speed, the load torque of the motor is observed by using the observer method, and whether the rivet exists and is qualified is detected according to the size of the load torque; finally, the rivet and the sheet metal part are riveted until all the stations complete the riveting. The riveting speed of the application can normally break through the rated speed of the motor, the riveting efficiency is high, the rivet without the rivet and the unqualified rivet can be detected without additionally increasing the torque sensor and the displacement sensor, the detection cost is low, and in general, the application has high work efficiency and high cost performance.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a motor control method applied to the production of pressing materials. Background Technology

[0002] In the production of overlapping and fastening processes, two different materials are often pressed together by pressing. A riveting machine is one such pressing device. It is a mechanical device that uses rivets to rivet sheet metal parts together. By pressing, the rivets are perfectly fastened to the sheet metal parts. It is widely used in industries such as automotive wheel hubs, windshield wipers, clutches, and shock absorbers.

[0003] The motor is one of the core components of a riveting machine, primarily used to provide pressure during the riveting process. The quality of motor control directly affects the efficiency and quality of the riveting machine. During riveting, rivets may be missing or misplaced due to operator negligence, or the rivets themselves may be defective, such as lacking teeth or threads. If these issues are not detected promptly, they will directly lead to insecure riveting. Therefore, how to effectively control the motor, ensuring riveting efficiency while simultaneously detecting and alarming for missing or defective rivets in real time, has become an indispensable problem in the motor control of riveting machines.

[0004] Reference 1, Chinese Patent Application No. 2022105774431, discloses a servo-driven blow-nail riveting nut device, which realizes automated rivet feeding and riveting operations. This not only greatly improves work efficiency and the pass rate of sheet metal riveting, but also saves labor costs and reduces problems such as missing or absent rivets in sheet metal riveting. By installing a rivet nut sensor above the blow-nail mechanism, the presence or absence of rivet nuts in the rivet feeding mechanism can be detected. If the nut sensor does not detect a rivet nut, it will send a signal to the electrical control cabinet, and a three-color alarm light will emit an alarm signal, allowing staff to add rivet nuts in time to solve the problem. This not only saves labor costs but also effectively reduces problems such as missing or absent rivets in sheet metal riveting. Torque and displacement sensors installed on the riveting machine can collect pressure and travel data during the riveting process and transmit the data to the online detection module in the industrial control computer, thereby realizing the monitoring of the riveting process quality and the tracking, storage, and management of quality data.

[0005] Traditional riveting machines typically rely on visual inspection by workshop operators to check for missing or defective rivets during the riveting process, as well as for whether the rivets have threads. After riveting is complete, the operators then test the rivets by touch to ensure they are secure. This method is crude and not intelligent enough. It not only increases labor costs but also leads to misjudgments due to worker negligence and inattention.

[0006] The method in Reference 1 automates the detection process to some extent, but it requires the addition of torque and displacement sensors, which increases the cost of the equipment. It does not fully leverage the advantages of the riveting machine itself, resulting in increased overall equipment cost and low cost-effectiveness. Summary of the Invention

[0007] The purpose of this invention is to provide a motor control method for use in pressing production, so as to solve the problems encountered in the above-mentioned background art.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A motor control method for use in pressing production includes the following steps:

[0010] S1. Starting from the mechanical characteristics of the motor, the relationship curve between the motor's torque and speed is obtained, and the optimal acceleration control curve is determined.

[0011] S2. Adjust the motor to speed control mode and control the motor position to the pre-detection point based on the optimal acceleration control curve.

[0012] S3. Adjust the motor speed to a lower speed. At the same time, use an observer to observe the motor load torque. Based on the magnitude of the load torque, check the presence and quality of the rivets. If the rivets do not meet the requirements, an alarm will sound and the motor will stop. If the rivets meet the requirements, the motor will be further adjusted to torque control mode.

[0013] S4. Rivet the rivets and sheet metal parts. Once the rivets are in place, readjust the motor to speed control mode. If there are still stations that have not been riveted, switch stations to continue riveting until all stations have completed riveting. Then, based on the optimal acceleration control curve, return the motor position control to the initial point, thus completing the motor control of the entire riveting process.

[0014] Compared with the prior art, the beneficial effects of the present invention are: the riveting speed of the present invention can normally exceed the rated speed of the motor, the riveting efficiency is high, no additional torque sensor and displacement sensor are needed to detect rivets without nails and unqualified rivets, the detection cost is low, and overall, the present invention has high working efficiency and high cost performance. Attached Figure Description

[0015] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:

[0016] Figure 1 This is a flowchart of a motor control method applied to the pressing production process according to the present invention;

[0017] Figure 2 This is a schematic diagram of the mechanical characteristic curves found in existing motor practical manuals;

[0018] Figure 3 This is a flowchart illustrating the position control to the pre-detection point in this invention;

[0019] Figure 4 This is a flowchart of the press riveting process in this invention;

[0020] Figure 5 This is a schematic diagram of the mechanical characteristic curve of the riveting motor in Embodiment 2 of the present invention;

[0021] Figure 6 This is a schematic diagram of the speed curve of the riveting motor in Embodiment 2 of the present invention;

[0022] Figure 7 This is a waveform diagram of the load torque of the riveting motor in Embodiment 2 of the present invention. Detailed Implementation

[0023] To make the technical means, creative features, achieved objectives, and effects of this invention readily understandable, the invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the relevant components of the invention.

[0024] According to the technical solution of the present invention, without changing the essential spirit of the present invention, those skilled in the art can propose various interchangeable structural methods and implementations. Therefore, the following detailed embodiments and accompanying drawings are merely exemplary descriptions of the technical solution of the present invention, and should not be regarded as the entirety of the present invention or as a limitation or restriction of the technical solution of the present invention.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1, as Figure 1 As shown, a motor control method applied to pressing production includes the following steps:

[0027] S1. Starting from the mechanical characteristics of the motor, the relationship curve between the motor's torque and speed is obtained, and the optimal acceleration control curve is determined.

[0028] You can find similar information by checking the user manual for the riveting machine motor. Figure 2 The mechanical characteristic curves are shown. The horizontal axis represents the motor's rotational speed n, in revolutions per minute (r / min), and the vertical axis represents the motor's torque T, in Nm.b This represents the rated speed of the motor, n. max This indicates the maximum speed of the motor, T. max This represents the maximum torque of the motor. When the motor speed is at its rated speed n... max When the motor operates in the constant torque region, the output torque of the motor is a constant value T. max When the motor speed is at the rated speed n max At the above time, the motor operates in the constant power region. At this time, the torque that the motor can output varies. When the motor speed changes, the torque also changes. The relationship between torque and speed is non-linear and there is no fixed functional relationship. This invention uses curve fitting to fit their relationship.

[0029] In the constant power region of the motor, N points are sampled, assuming the sampled speed data is n. i For i∈[1,2,…,N], the sampled torque data is T. i For i∈[1,2,…,N], choose the curve:

[0030] T 拟合 =a*n 5 +b*n 4 +c*n 3 +d*n 2 +e*n+f Equation 1

[0031] The sampled speed and torque data are fitted, where abcdef represents T. 拟合 The coefficients are calculated using the following method:

[0032]

[0033]

[0034]

[0035] In the formula A T This represents the transpose of matrix A, (A T *A) -1 This represents matrix A. T The inverse matrix of the product of matrix A and matrix A.

[0036] Assume the motor's moment of inertia is J and its acceleration is A. cc When the motor is unloaded, we have:

[0037]

[0038] In the formula A cc The unit is revolutions per minute per second, or r / min / s;

[0039] In summary, the optimal acceleration curve can be obtained as follows:

[0040]

[0041] S2. Adjust the motor to speed control mode and control the motor position to the pre-detection point based on the optimal acceleration control curve.

[0042] Adjust the motor to speed control mode; the motor will start from the initial point. Please refer to [link / reference]. Figure 3 Control according to the following steps:

[0043] S201. Determine the total distance S from the initial point to the pre-detection point. 总 ;

[0044] S202. Set the motor control speed n 控制 For the command speed n 指令 =n 起跳 , where n 起跳 The starting speed is determined by whether the riveting machine vibrates; as long as it does not vibrate, the higher the value, the better.

[0045] S203. Distance traveled: S 已走 Zeroing, i.e., S 已走 =0;

[0046] S204. Deceleration distance S 降速 Zeroing, i.e., S 降速 =0;

[0047] S205. Enter the next control cycle T. cy ;

[0048] S206. Calculate the distance traveled.

[0049] S207. Calculate the deceleration distance S 降速 If the command speed is less than the maximum speed, i.e., n 指令 <n max If the deceleration distance is equal to the distance already traveled, then S 降速 =S 已走 If the command speed is greater than or equal to the maximum speed, i.e., n 指令 >=n max Then S 降速 Keep the previous value unchanged;

[0050] S208. Calculate the remaining distance S 剩余 =S 总 -S 已走 ;

[0051] S209. Calculate the command acceleration based on the current command velocity n. 指令 By referring to the optimal acceleration curve, the commanded acceleration A can be calculated using Equation 5. cc ;

[0052] S210. Calculate command speed n 指令 If the remaining distance is longer than the deceleration distance, i.e., S 剩余 >=S 降速 Then acceleration is needed, i.e., n 指令 =n 指令 +A cc T cy If the remaining distance is shorter than the deceleration distance, i.e., S 剩余 <S 降速 Then it is necessary to reduce the speed, i.e., n 指令 =n 指令 -A cc T cy ;

[0053] S211. Instruction speed limit: If the instruction speed exceeds the maximum speed, i.e., n... 指令 >n max Then n 指令 =n max If the command speed is lower than the takeoff speed, i.e., n 指令 <n 起跳 Then n 指令 =n 起跳 ;

[0054] S212. Set the new control speed n of the motor. 控制 For the command speed n 指令 ;

[0055] S213. Jump to check if the instruction speed n 指令 and takeoff speed n 起跳 They are not equal, that is, n 指令 ≠n 起跳 Then jump to step S205, if the command speed n 指令 and takeoff speed n 起跳 Equal, i.e., n 指令 ==n 起跳 If the motor position has been controlled to the pre-detection point, the process ends.

[0056] S3. Adjust the motor speed to a lower speed. At the same time, use an observer to observe the motor load torque. Based on the magnitude of the load torque, check the presence and quality of the rivets. If the rivets do not meet the requirements, an alarm will sound and the motor will stop. If the rivets meet the requirements, the motor will be further adjusted to torque control mode.

[0057] Following the previous step, set the motor's control speed n. 控制 Let n be the takeoff speed. 起跳 The motor continues to run at a low speed until it enters the riveting detection area, where the presence and quality of the rivets are checked. When the rivet is correctly placed, the motor will touch it, and the motor's load torque will no longer be zero. When the rivet is defective, the resistance it exerts on the motor will become very large, causing the motor's load torque to rise rapidly. Therefore, the load torque T of the motor can be detected... 负载 The size of the rivet is used to detect and judge its presence and quality. It is worth noting that when the rivet is properly positioned, the motor's load torque T... 负载 Very small, compared to the motor's maximum torque T max In other words, T 负载 The difference is negligible, requiring extremely high detection accuracy. Using current detection results from the motor control circuit for judgment is prone to errors due to insufficient accuracy, sometimes misjudging the absence of a rivet. This necessitates a different approach; this invention proposes using an observer to detect the T... 负载 The testing method and detailed process are described below.

[0058] Assuming the actual position of the motor is p and its actual speed is v, we have:

[0059]

[0060] In the formula It represents the differential of the motor position, and the unit is rad / s.

[0061] When the motor is under load, we have:

[0062]

[0063] In the formula This represents the derivative of the motor speed, and its unit is rad / s. 2 .

[0064] Rewriting equations 7 and 8 in the form of state equations, we have:

[0065]

[0066] Assume ω1 is the observed signal of the actual position p, ω2 is the observed signal of the actual velocity v, and ω3 is the load torque term. The observed signal, e, is the observation error between ω1 and the actual position p. Equation 9 can be written in the form of the observer equation:

[0067]

[0068] In the formula This represents the differential of ω1. This represents the differential of ω². This represents the derivative of ω3, with units of k1, k2, and k3 representing the gain parameters of the observer.

[0069] The characteristic equation of Equation 10 is:

[0070] C(s)=s 3 +k1s 2 +k2s+k3 Formula 11

[0071] According to the Routh stability criterion, the necessary and sufficient condition for stability in Equation 11 is:

[0072]

[0073] By performing forward differencing on Equation 10, we obtain:

[0074]

[0075] By performing a bilinear transformation on Equation 13 and applying the Routh stability criterion, the necessary and sufficient condition for the stability of Equation 12 is:

[0076]

[0077] Pick Equation 14 can be simplified to:

[0078]

[0079] In this invention, considering the condition of Equation 15, the values ​​of each gain parameter are as follows:

[0080]

[0081] Substituting Equation 16 into Equation 13, the observed signal ω3 for each control cycle can be obtained. After a certain detection time, once the data stabilizes, the load torque T can be calculated. 负载 Observational signals:

[0082] T 负载 =-Jω3 Equation 17

[0083] Using T 负载 Inspect the rivets, when T 负载 Less than the critical value -T 临界1 When T indicates that there is no nail, the rivet is not placed correctly. 负载 Greater than the critical value of 2T 临界2If the riveting fails, it indicates the rivet is defective, possibly due to missing teeth or threads. These situations signify an abnormal rivet inspection result, requiring an alarm signal to be issued and the riveting process to end. Otherwise, it indicates the rivet is qualified and correctly placed, and riveting can continue. After the inspection is complete, set the motor's control speed n. 控制 Set the value to 0 to stop the motor. This step is now complete.

[0084] S4. Rivet the rivets and sheet metal parts. Once the rivets are in place, readjust the motor to speed control mode. If there are still stations that have not been riveted, switch stations to continue riveting until all stations have completed riveting. Then, based on the optimal acceleration control curve, return the motor position control to the initial point, thus completing the motor control of the entire riveting process.

[0085] Once the test is complete, if the rivet is found to be normal, the motor will start from the test point. Please refer to [link / reference needed]. Figure 4 Continue with the following steps for control:

[0086] S401. Set a suitable riveting limit speed n 压铆 and riveting limiting torque T 压铆 ;

[0087] S402. Set the motor control speed n 控制 =n 压铆 ;

[0088] S403. Enter the next control cycle T. cy ;

[0089] S404. If the actual output torque of the motor is less than T 压铆 If the condition is met, proceed to step S402; otherwise, proceed to step S405.

[0090] S405. Record the current actual critical position p of the motor. 临界 ;

[0091] S406. Adjust the motor control mode to torque control and set the motor control torque T. 控制 =0;

[0092] S407. If the actual speed of the motor is not 0, then jump to step S406; otherwise, jump to step S408.

[0093] S408. Adjust the motor control mode to speed control, and control the motor position to the position p recorded in step S405, following the method in step S3. 临界 Place;

[0094] S409. If there are any remaining stations that have not completed the riveting process, then proceed to step S410; otherwise, proceed to step S413.

[0095] S410. Following the method in step S3, control the position of the motor to the pre-detection point;

[0096] S411. Switch workstations and rotate the worktable to the next workstation;

[0097] S412. Riveting inspection. If the inspection is normal, proceed to step S402; otherwise, proceed to step S413.

[0098] S413. Following the method in step S3, control the position of the motor to the initial point.

[0099] Example 2: The following example from actual production illustrates the entire process:

[0100] I. Acceleration of the riveting motor

[0101] Motor inertia J = 7.96 × 10 -3 kg.m 2 Maximum torque T max = 56 N·m, rated speed n b =2000r / min, maximum speed n max =3000r / min. Torque and speed data are sampled every 10r / min between the rated speed and the maximum speed, resulting in a total of N = 101 points. Using equations 1 to 4, the coefficients of the fitted curve can be obtained as follows:

[0102]

[0103] According to Equation 6, the optimal acceleration curve of the riveting motor can be obtained as follows: Figure 5 As shown.

[0104] II. Riveting motor speed

[0105] The starting speed n of the motor 起跳 =200r / min, control period T cy =0.0001s, according to Figure 3 The method can be used to obtain the speed curve of the riveting motor, as shown in the figure. Figure 6 As shown.

[0106] from Figure 6As can be seen, the speed waveform of the riveting motor is a saddle-shaped waveform. The slope of the curve is constant below 2000 r / min, and gradually decreases above 2000 r / min. If existing methods are used, the speed waveform is trapezoidal. When the motor speed increases to 2000 r / min, the motor is prone to vibration, resulting in low efficiency. The speed of this invention can normally exceed 2000 r / min. Compared with existing technologies, this invention has high riveting efficiency.

[0107] III. Riveting Inspection

[0108] Control period T cy =0.0001s, according to Equation 16, the observer gain parameter can be obtained:

[0109]

[0110] According to equations 13 and 17, the waveform of the load torque can be observed as follows: Figure 7 As shown.

[0111] from Figure 7 As can be seen, after about 50 control cycles, the load torque value observed by the observer basically stabilizes, and the unit of the detected load torque is a percentage relative to the maximum torque of the motor.

[0112] In this example, T 临界1 =0.5%, T 临界2 =10%, when the observed load torque value is in T 临界1 The following indicates no rivets are present, when the observed load torque value is within T. 临界2 If the above conditions are met, the rivet is considered defective; otherwise, the rivet is considered normal.

[0113] This invention does not rely on additional torque and displacement sensors; it achieves normal rivet detection simply by utilizing the motor control system built into the riveting machine. Compared with existing technologies, this invention has a lower detection cost.

[0114] The riveting speed of this invention can normally exceed the rated speed of the motor, with high riveting efficiency. It can detect missing or unqualified rivets without the need for additional torque and displacement sensors, resulting in low detection costs. Overall, this invention has high working efficiency and high cost-effectiveness.

[0115] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A motor control method applied to pressing production, characterized in that, Includes the following steps: S1. Starting from the mechanical characteristics of the motor, derive the relationship curve between the motor's torque and speed, and determine the optimal acceleration control curve; S2. Adjust the motor to speed control mode and control the motor position to the pre-detection point based on the optimal acceleration control curve; S3. Adjust the motor speed to a lower speed. At the same time, use the observer to observe the motor load torque. Check the presence and quality of the rivets based on the magnitude of the load torque. If the rivets do not meet the requirements, an alarm will sound and the motor will stop. If the rivets meet the requirements, the motor will be further adjusted to torque control mode. S4. Rivet the rivets and sheet metal parts. Once the rivets are in place, readjust the motor to speed control mode. If there are still stations that have not been riveted, switch stations to continue riveting until all stations have completed riveting. Then, based on the optimal acceleration control curve, return the motor position control to the initial point to complete the motor control of the entire riveting process. In step S1, the relationship between the motor's torque and speed is fitted using a curve fitting method. In the constant power region of the motor, N points are sampled, assuming the sampled speed data is n. i For i∈[1,2,…,N], the sampled torque data is T. i For i∈[1,2,…,N], choose the curve: T 拟合 = a * n 5 + b * n 4 + c * n 3 + d * n 2 + e * n + f Equation 1 The sampled speed and torque data are fitted, where abcdef represents T. 拟合 The coefficients are calculated using the following method: In the formula A T This represents the transpose of matrix A, (A T *A) -1 This represents matrix A. T The inverse matrix of the product of matrix A and matrix A; Assume the motor's moment of inertia is J and its acceleration is A. cc When the motor is unloaded, we have: In the formula A cc The unit is revolutions per minute per second, or r / min / s; In summary, the optimal acceleration curve can be obtained as follows: 。 2. The motor control method for pressing production according to claim 1, characterized in that: In step S2, the motor position is controlled to the pre-detection point, and the control is performed according to the following steps: S201. Determine the total distance S from the initial point to the pre-detection point. 总 ; S202. Set the motor control speed n 控制 For the command speed n 指令 =n 起跳 , where n 起跳 The starting speed is determined by whether the riveting machine vibrates; as long as it does not vibrate, the higher the value, the better. S203. Distance traveled: S 已走 Zeroing, i.e., S 已走 =0; S204. Deceleration distance S 降速 Zeroing, i.e., S 降速 =0; S205. Enter the next control cycle Tcy; S206. Calculate the distance traveled. ; S207. Calculate the deceleration distance S 降速 If the command speed is less than the maximum speed, i.e., n 指令 <n max If the deceleration distance is equal to the distance already traveled, then S 降速 =S 已走 If the command speed is greater than or equal to the maximum speed, i.e., n 指令 >=n max Then S 降速 Keep the previous value unchanged; S208. Calculate the remaining distance S 剩余 =S 总 -S 已走 ; S209. Calculate the command acceleration based on the current command velocity n. 指令 By referring to the optimal acceleration curve, the commanded acceleration A can be calculated using Equation 5. CC ; S210. Calculate command speed n 指令 If the remaining distance is longer than the deceleration distance, i.e., S 剩余 >=S 降速 Then acceleration is needed, i.e., n 指令 =n 指令 +A cc T cy If the remaining distance is shorter than the deceleration distance, i.e., S 剩余 <S 降速 Then it is necessary to reduce the speed, i.e., n 指令 =n 指令 -A cc T cy ; S211. Instruction speed limit: If the instruction speed exceeds the maximum speed, i.e., n... 指令 >n max Then n 指令 =n max If the command speed is lower than the takeoff speed, i.e., n 指令 <n 起跳 Then n 指令 =n 起跳 ; S212. Set the new control speed n of the motor. 控制 For the command speed n 指令 ; S213. Jump to check if the instruction speed n 指令 and takeoff speed n 起跳 They are not equal, that is, n 指令 ≠n 起跳 Jump to step S205, if the command speed n 指令 and takeoff speed n 起跳 Equal, i.e., n 指令 =n 起跳 This indicates that the motor position has been controlled to the pre-detection point, and the process is now complete.

3. The motor control method for pressing production according to claim 1, characterized in that: In step S3, the observer is used to evaluate T. 负载 The specific steps for conducting the detection are as follows: Assuming the actual position of the motor is p and its actual speed is v, we have: In the formula It represents the differential of the motor position, and the unit is rad / s; When the motor is under load, we have: In the formula This represents the derivative of the motor speed, and its unit is rad / s. 2 ; Rewriting equations 7 and 8 in the form of state equations, we have: Assume ω1 is the observed signal of the actual position p, ω2 is the observed signal of the actual velocity v, and ω3 is the load torque term. The observed signal, e, is the observation error between ω1 and the actual position p. Equation 9 can be written in the form of the observer equation: In the formula This represents the differential of ω1. This represents the differential of ω². This represents the derivative of ω3, and k1, k2, and k3 represent the gain parameters of the observer; The characteristic equation of Equation 10 is: C(s) = s 3 + k1s 2 + k2s + k3 Equation 11 According to the Routh stability criterion, the necessary and sufficient condition for stability in Equation 11 is: By performing forward differencing on Equation 10, we obtain: By performing a bilinear transformation on Equation 13 and applying the Routh stability criterion, the necessary and sufficient condition for the stability of Equation 12 is: Pick Equation 14 can be simplified to: Considering that the condition of Equation 15 is satisfied, the values ​​of each gain parameter are as follows: Substituting Equation 16 into Equation 13, the observed signal ω3 for each control cycle can be obtained. After a certain detection time, once the data stabilizes, the load torque T can be calculated. 负载 Observational signals: T 负载 =-Jω3 Equation 17; Among them, T cy It is the control cycle.

4. The motor control method for pressing production according to claim 1, characterized in that: In step S4, after the detection is completed, if the rivet is found to be normal, the motor will continue to be controlled from the detection point according to the following steps: S401. Set a suitable riveting limit speed n 压铆 and riveting limiting torque T 压铆 ; S402. Set the motor control speed n 控制 =n 压铆 ; S403. Enter the next control cycle T. cy ; S404. If the actual output torque of the motor is less than T 压铆 If the condition is met, proceed to step S402; otherwise, proceed to step S405. S405. Record the current actual critical position p of the motor. 临界 ; S406. Adjust the motor control mode to torque control and set the motor control torque T. 控制 =0; S407. If the actual speed of the motor is not 0, then jump to step S406; otherwise, jump to step S408. S408. Adjust the motor control mode to speed control, and following the method in step S3, control the motor position to the position p recorded in step S405. 临界 Place; S409. If there are any remaining stations that have not completed the riveting process, then proceed to step S410; otherwise, proceed to step S413. S410. Following the method in step S3, control the position of the motor to the pre-detection point; S411. Switch workstations and rotate the worktable to the next workstation; S412. Riveting inspection. If the inspection is normal, proceed to step S402; otherwise, proceed to step S413. S413. Following the method in step S3, control the position of the motor to the initial point.

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