A multi-machine linkage control system for a servo electric screwdriver

Abstract

The application relates to a servo electric wrench multi-machine linkage control system which comprises an upper computer, a lower computer, a servo electric wrench and a detection module; the upper computer sends a working parameter signal to the lower computer through serial communication; the lower computer converts the working parameter signal into a control signal and sends the control signal to the servo electric wrench through an IO port; the servo electric wrench locks the task according to the control signal; the detection module is used for detecting the working state of the servo electric wrench and transmitting working state information to the upper computer through serial communication; and the serial communication is Modbus RTU communication. The servo electric wrench multi-machine linkage control system can connect multiple lower computers and servo electric wrenches with one upper computer, parameters can be conveniently unified, changed and debugged, IO port communication and serial communication are mixedly used, the advantages of IO port control, such as good real-time performance, strong stability and large information carrying capacity, are exerted, and the disadvantages of using only IO port control, such as complicated wiring, time and labor consumption of parameter debugging, are avoided.

Description

Technical Field

[0001] This invention relates to the field of servo electric screwdrivers, and in particular to a multi-machine linkage control system for servo electric screwdrivers. Background Technology

[0002] Bolt fastening is a critical process in the assembly stage of manufacturing, and the fastening speed and effect directly affect the efficiency of automated production in the factory. Fastening multiple bolts simultaneously can greatly improve production efficiency, which requires the simultaneous control of multiple servo electric screwdrivers to complete the fastening task synchronously.

[0003] Please see Figure 1 , Figure 1 This is a schematic diagram of an existing servo electric screwdriver control system. The existing servo electric screwdriver control system includes a host computer, a slave computer, a servo electric screwdriver, and a detection module. The host computer can interact with the operator. The operator sets the working parameters of the servo electric screwdriver through the host computer. The slave computer is connected to the host computer via I / O ports, receives parameter signals from the host computer, and controls the movement of the servo electric screwdriver according to these signals through the I / O ports. The detection module detects the working status information of the servo electric screwdriver and transmits this information to the slave computer. The slave computer transmits the working status information back to the host computer through I / O ports. The host computer displays the working status of the servo electric screwdriver for the operator to view.

[0004] Existing servo electric screwdriver control systems are suitable for controlling one or two servo electric screwdrivers. When the number of servo electric screwdrivers reaches three or more, the host computer's I / O resources become strained, and the excessive use of I / O ports leads to cumbersome wiring. When debugging parameters, commands must be sent to each I / O port connected to the slave computer individually, making the program cumbersome. Replacing all I / O port communication with serial communication results in too many serial signals being processed by the slave computer, leading to long polling times. While other high-speed communication methods solve the long polling time problem, they are too costly. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a servo electric screwdriver multi-machine linkage control system, which has the advantages of low cost and good multi-machine control synchronization.

[0006] A multi-machine linkage control system for servo electric screwdrivers includes a host computer, a slave computer, a servo electric screwdriver, and a detection module. The host computer sends working parameter signals to the slave computer. The slave computer converts the working parameter signals into control signals and sends the control signals to the servo electric screwdriver. The servo electric screwdriver performs a locking task according to the control signals. The detection module detects the working status of the servo electric screwdriver and transmits the working status information to the host computer.

[0007] This servo electric screwdriver multi-machine linkage control system enables the detection module to directly transmit working status information to the host computer, optimizing signal flow and reducing the burden on the slave computer; one host computer can connect to multiple slave computers and servo electric screwdrivers, facilitating unified modification and debugging of parameters.

[0008] Furthermore, the host computer sends operating parameter signals to the slave computer via serial communication; the slave computer sends control signals to the servo electric screwdriver via I / O ports; and the detection module transmits operating status information to the host computer via serial communication. This hybrid use of I / O port communication and serial communication leverages the advantages of I / O port communication—good real-time performance, high stability, and large information capacity—while avoiding excessive I / O resource consumption and cumbersome wiring.

[0009] Furthermore, the serial communication is Modbus RTU communication.

[0010] Furthermore, the host computer includes a human-machine interface screen and an information processing module; the operator sets the working parameters of the servo electric screwdriver by operating the human-machine interface screen; the information processing module transmits the working parameter signals to the slave computer via the Modbus protocol.

[0011] Furthermore, the lower-level machine includes a signal receiving module, a signal analysis module, and an I / O port; the signal receiving module receives the working parameter signal transmitted by the upper-level machine via the Modbus protocol and performs Modbus frame integrity judgment; the signal analysis module converts the working parameter signal into a control signal; and the I / O port sends the control signal to the servo electric screwdriver.

[0012] Furthermore, the signal receiving module includes a first Modbus frame integrity judgment unit; the first Modbus frame integrity judgment unit includes a slave station number judgment unit, a data length judgment unit, and a CRC check unit;

[0013] The slave station number determination unit performs the following functions: when data is received and the data length is greater than the slave station number length, it determines whether the slave station number matches; if it does not match, the data is deleted; if it matches, the data is transmitted to the data length determination unit.

[0014] The data length determination unit performs the following functions: it copies the data transmitted from the station number determination unit into the cache array; if the data length in the cache array does not exceed the expected data length, it continues to receive data; if the data length in the cache array reaches the expected data length, it transmits the data in the cache array to the CRC verification unit.

[0015] The CRC check unit performs the following functions: it performs CRC check on the data transmitted by the data length judgment unit; if the CRC check is incorrect, it deletes the data from the cache array; if the CRC check is correct, it transmits the data to the subsequent processing unit; the subsequent processing unit is the signal analysis module.

[0016] Furthermore, the detection module transmits the working status information to the host computer via the Modbus RTU protocol; the host computer's information processing module receives Modbus RTU data frames and performs frame integrity judgment; the host computer's information processing module includes a second Modbus frame integrity judgment unit; the second Modbus frame integrity judgment unit performs the same function as the first Modbus frame integrity judgment unit; the information processing module judges the working status of the servo electric screwdriver based on the working status information; the human-machine interaction screen displays the working status information and the working status judgment result.

[0017] Furthermore, the working status information includes the torque and number of rotations of the servo electric screwdriver; the working status includes OK status, floating lock status, and slipped tooth status; when the number of rotations is greater than the total number of floating lock rotations and less than the total number of slipped tooth rotations, and the torque is within the error range, the information processing module determines that the servo electric screwdriver is in OK status; when the number of rotations is greater than the total number of slipped tooth rotations, the information processing module determines that the servo electric screwdriver is in slipped tooth status; when the number of rotations is less than the total number of floating lock rotations, the information processing module determines that the servo electric screwdriver is in floating lock status; the total number of slipped tooth rotations = target number of rotations + number of slipped tooth rotations; the total number of floating lock rotations = target number of rotations - number of floating lock rotations; the target number of rotations is the number of rotations required for the servo electric screwdriver to complete the locking task; the error range, number of slipped tooth rotations, and number of floating lock rotations are all parameters set by the operator.

[0018] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an existing servo electric screwdriver control system;

[0020] Figure 2 This is a schematic diagram of a servo electric screwdriver multi-machine linkage control system according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the internal modules of a servo electric screwdriver multi-machine linkage control system according to an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram showing the relationship between torque T and time t during the operation of a servo electric screwdriver.

[0023] Figure 5This is a schematic diagram showing the relationship between the working state of a servo electric screwdriver and its torque and number of rotations. Detailed Implementation

[0024] The inventors, through analysis of existing technologies, discovered that one reason for the long polling time of the lower-level machine is that it needs to receive signals from the upper-level machine, signals from the detection module, and control signals to the servo electric screwdriver—the lower-level machine has too much information to process, leading to the long polling time. To address this, the signal flow can be optimized, allowing the detection module to directly send signals to the upper-level machine, thus reducing the burden on the lower-level machine.

[0025] The inventors also discovered that both using I / O port communication and using serial communication have their drawbacks. Using I / O port communication alone consumes excessive I / O resources, involves cumbersome wiring, and is difficult to debug parameters. However, I / O port communication has unique advantages such as good real-time performance, high stability, and large information capacity, and should not be completely abandoned. Therefore, the inventors creatively designed a servo electric screwdriver control system that uses both I / O port communication and serial communication. I / O port communication is used for aspects with high real-time signal transmission requirements, while serial communication is used for aspects with lower real-time requirements, achieving good multi-machine control performance at a lower cost.

[0026] Based on the above inventive concept, combined with Figure 2 and Figure 3 This invention provides a detailed description of a specific implementation method for a servo electric screwdriver multi-machine linkage control system.

[0027] Please see Figure 2 , Figure 2 This is a schematic diagram of a servo electric screwdriver multi-machine linkage control system according to an embodiment of the present invention.

[0028] A multi-machine linkage control system for servo electric screwdrivers includes a host computer, a slave computer, servo electric screwdrivers, and a detection module. The host computer interacts directly with the operator, who sets operating parameters. The host computer then transmits these operating parameter signals to the slave computer. The slave computer receives the operating parameter signals from the host computer and sends control signals to the servo electric screwdrivers based on these signals. The servo electric screwdrivers perform locking tasks under the control of the control signals. The detection module detects the operating status of the servo electric screwdrivers and transmits this status information back to the host computer.

[0029] Please see Figure 3 , Figure 3 This is a schematic diagram of the internal modules of a servo electric screwdriver multi-machine linkage control system according to an embodiment of the present invention.

[0030] Specifically, the host computer includes a human-machine interface screen and an information processing module. Operators can set unified operating parameters for the servo electric screwdriver through the human-machine interface screen; the information processing module stores the servo electric screwdriver operating parameters input by the operator and transmits the operating parameter signals to the slave computer via the Modbus RTU protocol.

[0031] Specifically, the lower-level machine is a CPU; the CPU includes a signal receiving module, a signal analysis module, and an I / O port; the signal receiving module receives the working parameter signals output by the upper-level machine via the Modbus RTU protocol and performs frame integrity judgment; the signal analysis module converts the working parameter signals into corresponding control signals; the I / O port outputs control signals to the servo electric screwdriver. In this embodiment, there are multiple lower-level machines, each controlling a different servo electric screwdriver; all multiple lower-level machines are signal-connected to the same upper-level machine.

[0032] The Modbus protocol data frame structure is: slave number + function code + data code + checksum. Modbus does not have fixed frame headers and trailers, and its length is also variable. Existing Modbus receivers detect data frame integrity by receiving all incoming data in a buffer array; when the idle time exceeds 3.5 character intervals, a data frame is considered complete, and the data in the buffer array is sent to the subsequent processing unit. This method of determining frame integrity based on idle time cannot detect errors in the data content or guarantee the correctness of the data length, and is prone to misjudgment when signal transmission is interfered with.

[0033] Therefore, this invention designs a Modbus frame integrity judgment unit based on the existing Modbus receiving unit. The first 5 bytes of a Modbus data frame represent the slave station number. Therefore, when data is received and the data length is greater than 5 bytes, the Modbus frame integrity judgment unit checks the first 5 bytes of the data frame to determine if the slave station number matches. If they do not match, the data is deleted; if they match, the data is copied to the buffer array, and data reception continues until the data length reaches the expected value. Then, a CRC check is performed on the data. If the CRC check fails, the data in the buffer array is deleted, and data is received again. If the CRC check is correct, it is determined that a data frame has been received, and the data in the buffer array is sent to the subsequent processing unit. The Modbus frame integrity judgment unit can detect whether the slave station number, data length, and data content are correct. Compared with the existing 3.5-character time detection method, it ensures the accuracy and stability of data reception. The expected data length is set according to actual needs. In this embodiment, the expected length of the control signal data frame is 256 bytes.

[0034] Further, the signal receiving module includes a first Modbus frame integrity judgment unit. The first Modbus frame integrity judgment unit includes a slave station number judgment unit, a data length judgment unit, and a CRC check unit. The slave station number judgment unit performs the following functions: when data is received and its length is greater than the slave station number length, it judges whether the slave station number matches; if it does not match, it deletes the data; if it matches, it transmits the data to the data length judgment unit. The data length judgment unit performs the following functions: it copies the data transmitted from the slave station number judgment unit into a buffer array; if the data length in the buffer array does not exceed the expected data length, it continues to receive data; if the data length in the buffer array reaches the expected data length, it transmits the data in the buffer array to the CRC check unit. The CRC check unit performs the following functions: it performs CRC check on the data transmitted by the data length judgment unit; if the CRC check is incorrect, it deletes the data in the buffer array; if the CRC check is correct, it transmits the data to the subsequent processing unit. In this embodiment, the slave station number length is 5 bytes, the expected data length is 256 bytes, and the subsequent processing unit is the signal analysis module of the lower-level machine.

[0035] Specifically, depending on the rotational speed, the servo electric screwdriver has a high-speed mode, a low-speed mode, and a zero-speed mode; the rotational speed of the servo electric screwdriver is directly controlled by the control signal output from the CPU I / O port. In this embodiment, the rotational speed of the servo electric screwdriver in high-speed mode is above 600 rpm, the rotational speed in low-speed mode is between 100 rpm and 600 rpm, and the rotational speed in zero-speed mode is 0.

[0036] The locking process of the servo electric screwdriver includes the thread insertion stage, the locking stage, the locking stage, and the OK stage. Please refer to [link / reference]. Figure 4 , Figure 4 This is a schematic diagram illustrating the relationship between torque T and time t during the operation of a servo electric screwdriver, T = f(t). Figure 4 As shown, during the tooth insertion stage, the derivative of torque T with respect to time t is relatively large, indicating that the servo electric screwdriver is in high-speed mode; during the locking stage, the derivative of torque T with respect to time t is relatively small, indicating that the servo electric screwdriver is in low-speed mode; during the tightening stage, the derivative of torque T with respect to time t is relatively large, indicating that the servo electric screwdriver is in high-speed mode; during the OK stage, the derivative of torque T with respect to time t is 0, indicating that the rotational speed of the servo electric screwdriver is 0. The unloading process of the servo electric screwdriver includes a start-up stage and an unloading stage; during the start-up stage, the servo electric screwdriver is in low-speed mode; after setting the number of rotations, it enters the unloading stage, and the servo electric screwdriver switches to high-speed mode.

[0037] Specifically, the detection module can detect the working status information of the servo electric screwdriver; the working status information includes the torque and number of rotations of the servo electric screwdriver. The detection module transmits the working status information to the host computer via the Modbus RTU protocol; the information processing module of the host computer receives the Modbus RTU data frame and performs frame integrity judgment, then judges the working status of the servo electric screwdriver based on the received working status information, and displays the working status information and judgment result on the human-machine interaction screen.

[0038] Furthermore, the information processing module of the host computer includes a second Modbus frame integrity judgment unit, which performs the same function as the first Modbus frame integrity judgment unit of the lower computer signal receiving module.

[0039] The operating status information includes the torque and number of rotations of the servo electric screwdriver. The operating status includes OK, floating lock, and stripped thread. Please refer to [link / reference]. Figure 5 , Figure 5 This diagram illustrates the relationship between the working status of the servo electric screwdriver and its torque and number of rotations. When the detection module detects that the number of rotations of the servo electric screwdriver is greater than the total number of rotations of the floating lock and less than the total number of rotations of the slipped teeth, and the torque of the servo electric screwdriver is within the error range, the information processing module determines that the servo electric screwdriver is in the OK state. When the detection module detects that the number of rotations of the servo electric screwdriver is greater than the total number of rotations of the slipped teeth, the information processing module determines that the servo electric screwdriver is in the slipped teeth state. When the detection module detects that the number of rotations of the servo electric screwdriver is less than the total number of rotations of the floating lock, the information processing module determines that the servo electric screwdriver is in the floating lock state. The total number of rotations of the slipped teeth = target number + number of rotations of the slipped teeth; the total number of rotations of the floating lock = target number - number of rotations of the floating lock. The target number of rotations is the number of rotations required for the servo electric screwdriver to complete the locking task. The error range, number of rotations of the slipped teeth, and number of rotations of the floating lock are all parameters set by the operator.

[0040] During operation, the operator sets the working parameters through the human-computer interaction screen of the host computer.

[0041] The operating parameters include the number of tooth-finding turns, the number of turns exempted from inspection, the cutting torque ratio, and the target number of turns r. 目标 Number of float lock cycles r 浮锁 Number of sliding teeth (r) 滑牙 Keep OK for T OK .

[0042] The number of tooth-seeking turns refers to the number of turns the servo electric screwdriver makes before performing the fastening task. Setting the number of tooth-seeking turns allows the servo electric screwdriver insert to align with the bolt hole position. Let x be the number of polygonal sides of the bolt or the number of pin lines of the screw, and the number of tooth-seeking turns be set to 1 / x.

[0043] The "no-inspection rotation count" refers to the range of rotation counts within which the servo electric screwdriver does not detect torque. When the rotation count of the servo electric screwdriver is within the range of the no-inspection rotation count, torque is not detected to prevent the torque from reaching its peak value at startup and causing misjudgment. The no-inspection rotation count is equal to or slightly greater than 0.3.

[0044] The torque-to-speed ratio refers to the ratio of torque to peak torque when the servo electric screwdriver switches speed modes. When the torque reaches a certain ratio of the peak torque, the servo electric screwdriver switches to low-speed mode to prevent torque overshoot caused by excessively high servo electric screwdriver speed. The torque-to-speed ratio is slightly equal to or slightly less than 90% of the target torque. The method for setting the target torque includes the following steps: S141, initializing working parameters, having all servo electric screwdrivers complete one bolt fastening task, and recording the completion result (OK, floating lock, or stripped thread) and peak torque of all servo electric screwdrivers; S142, calculating the average value of the peak torque corresponding to the servo electric screwdrivers with the completion result of OK, and setting the average value of the peak torque as the target torque.

[0045] The target number of revolutions r 目标 This refers to the number of rotations required for the servo electric screwdriver to perfectly complete the locking task. The target number of rotations, r... 目标 The setting method includes the following steps: S151, let the target number of laps r 目标 It equals the number of bolt or screw threads plus 0.5; that is, r. 目标 = Number of thread turns + 0.5.

[0046] The number of float lock rings r 浮锁 This refers to the total number of rotations (total number of float lock rotations) when the servo electric screwdriver just reaches the float lock, which is lower than the target number of rotations r. 目标 The difference. Total number of float lock turns = r 目标 -r 浮锁 The number of sliding teeth rings r 滑牙 This refers to the total number of rotations (total number of stripped rotations) when the servo electric screwdriver just slips a thread, which is higher than the target number of rotations r. 目标 The difference. Total number of slip teeth = r 目标 +r 滑牙 The number of float lock cycles r 浮锁 And the number of slip teeth r 滑牙 The setting method includes the following steps: S161, setting a larger number of float lock circles r 浮锁 And the number of slip teeth r 滑牙 Initial value; S162, have all servo electric screwdrivers complete one bolt fastening task, and record the actual completion result (OK, floating lock, or stripped thread) of all servo electric screwdrivers and the judgment result of the host computer; S163, if there is a case where the actual completion result is OK and the host computer judgment result is floating lock, then set the number of floating lock turns r. 浮锁Halve the number of rotations, repeat S162; S164. If there is a case where the actual completion result is OK and the host computer determines the result as stripped, reduce the number of stripped rotations r. 滑牙 Halve the number of turns, repeat S162; S165, if there is no actual completion result of OK, and the host computer determines the result as either floating lock or slipped tooth, then fix the number of floating lock turns r. 浮锁 And the number of slip teeth r 滑 tooth.

[0047] The OK hold time T OK This refers to the minimum waiting time required after a servo electric screwdriver completes a latching task. After the servo electric screwdriver completes latching, it needs to wait for T... OK The next bolt fastening task can only proceed after a certain time has elapsed. Setting an OK hold time allows multiple servo electric screwdrivers to start their next bolt fastening task simultaneously. The method for setting the OK hold time includes the following steps: S171, initializing working parameters, causing all servo electric screwdrivers to complete one bolt fastening task, and recording the completion time of all servo electric screwdrivers; S172, calculating the difference between the earliest and latest completion times, and setting the OK hold time to be greater than this difference.

[0048] After the operator sets the working parameters, the information processing module of the host computer transmits the working parameter signals to the slave computer via Modbus communication. The slave computer sends control signals to the servo electric screwdriver through the IO port according to the working parameter signals. The servo electric screwdriver performs locking operation according to the control signals. The detection module detects the working status information of the servo electric screwdriver and transmits the working status information to the host computer via Modbus communication. The information processing module of the host computer determines the working status of the servo electric screwdriver based on the working status information and displays the working status on the human-machine interaction screen.

[0049] This invention discloses a multi-machine linkage control system for servo electric screwdrivers, in which one host computer can connect to multiple slave computers and servo electric screwdrivers, facilitating unified modification and debugging of parameters. The working status information of the servo electric screwdrivers is directly transmitted to the host computer without going through the slave computers, making the wiring simpler. It uses a combination of IO port communication and Modbus communication, which not only leverages the advantages of IO port control such as good real-time performance, strong stability and large information carrying capacity, but also avoids the disadvantages of using only IO port control, such as cumbersome wiring and time-consuming and labor-intensive parameter debugging.

[0050] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A servo electric screwdriver multi-machine linkage control system, comprising a host computer, a slave computer, a servo electric screwdriver, and a detection module; The host computer sends working parameter signals to the slave computer; the slave computer converts the working parameter signals into control signals and sends the control signals to the servo electric screwdriver; the servo electric screwdriver performs the locking task according to the control signals; the detection module detects the working status of the servo electric screwdriver and transmits the working status information to the host computer. The host computer includes a human-machine interface screen and an information processing module; the operator sets the working parameters of the servo electric screwdriver by operating the human-machine interface screen; the information processing module transmits the working parameter signals to the slave computer via the Modbus protocol. The lower-level machine includes a signal receiving module, a signal analysis module, and an I / O port; the signal receiving module receives the working parameter signals transmitted by the upper-level machine via the Modbus protocol and performs Modbus frame integrity judgment; the signal analysis module converts the working parameter signals into control signals; the I / O port sends the control signals to the servo electric screwdriver; The signal receiving module includes a first Modbus frame integrity judgment unit; the first Modbus frame integrity judgment unit includes a slave station number judgment unit, a data length judgment unit, and a CRC check unit. The slave station number determination unit performs the following functions: when data is received and the data length is greater than the slave station number length, it determines whether the slave station number matches; if it does not match, the data is deleted; if it matches, the data is transmitted to the data length determination unit. The data length determination unit performs the following functions: it copies the data transmitted from the station number determination unit into the cache array; if the data length in the cache array does not exceed the expected data length, it continues to receive data; if the data length in the cache array reaches the expected data length, it transmits the data in the cache array to the CRC verification unit. The CRC check unit performs the following functions: it performs CRC check on the data transmitted by the data length judgment unit; if the CRC check is incorrect, it deletes the data from the cache array; if the CRC check is correct, it transmits the data to the subsequent processing unit; the subsequent processing unit is the signal analysis module. The detection module transmits the working status information to the host computer via the Modbus RTU protocol; the host computer's information processing module receives Modbus RTU data frames and performs frame integrity judgment; the host computer's information processing module includes a second Modbus frame integrity judgment unit; the second Modbus frame integrity judgment unit performs the same function as the first Modbus frame integrity judgment unit; the information processing module judges the working status of the servo electric screwdriver based on the working status information; the human-machine interaction screen displays the working status information and the working status judgment result.

2. The servo electric screwdriver multi-machine linkage control system according to claim 1, characterized in that: The host computer sends working parameter signals to the slave computer via serial communication; the slave computer sends control signals to the servo electric screwdriver via I / O ports; and the detection module transmits working status information to the host computer via serial communication.

3. The servo electric screwdriver multi-machine linkage control system according to claim 2, characterized in that: The serial communication is Modbus RTU communication.

4. The servo electric screwdriver multi-machine linkage control system according to claim 3, characterized in that: The working status information includes the torque and number of rotations of the servo electric screwdriver; the working status includes OK status, floating lock status, and slipped tooth status; when the number of rotations is greater than the total number of floating lock rotations and less than the total number of slipped tooth rotations, and the torque is within the error range, the information processing module determines that the servo electric screwdriver is in OK status; when the number of rotations is greater than the total number of slipped tooth rotations, the information processing module determines that the servo electric screwdriver is in slipped tooth status; when the number of rotations is less than the total number of floating lock rotations, the information processing module determines that the servo electric screwdriver is in floating lock status; the total number of slipped tooth rotations = target number of rotations + number of slipped tooth rotations; the total number of floating lock rotations = target number of rotations - number of floating lock rotations; the target number of rotations is the number of rotations required for the servo electric screwdriver to complete the locking task; the error range, number of slipped tooth rotations, and number of floating lock rotations are all parameters set by the operator.

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