Method and device for controlling motor speed

Abstract

The present invention relates to the technical field of electric tools, and discloses a method and device for controlling motor speed. The method comprises: collecting current pressure and associated data of the motor at the current moment; determining the current motor fluctuation frequency based on the associated data of the motor at the current moment and the associated data of the motor at a previous moment; determining the current slip coefficient based on the current motor fluctuation frequency and the current pressure; when the current slip coefficient is not less than a slip coefficient threshold, controlling the motor speed according to a target speed, determining whether there is a risk of slipping between a screwdriver bit and a screw connected to the motor based on the current motor fluctuation frequency and the current pressure; and when there is a risk of slipping between the screwdriver bit and the screw connected to the motor, dynamically adjusting the motor speed to avoid slipping between the screwdriver bit and the screw connected to the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of electric tools, and in particular to a method and device for controlling the rotational speed of a motor. Background Art

[0002] In numerous fields, including industrial production, electronic equipment assembly, and furniture manufacturing, screw tightening is a critical step in the product assembly process. The quality of screw tightening directly impacts the structural stability, reliability, and service life of the product. As the manufacturing industry evolves toward automation and intelligentization, higher requirements are placed on the precision, efficiency, and consistency of screw tightening. As an important tightening tool, electric screwdrivers are widely used in various screw tightening scenarios due to their ease of operation and high efficiency.

[0003] In related technologies, the tightening process of screws is controlled by presetting torque values ​​or constant speeds. Specifically, users can pre-set a torque value on the electric screwdriver based on the screw specifications and tightening requirements. When the torque value is reached during the tightening process, the electric screwdriver automatically stops to prevent over-tightening. Another method is to set a constant speed, where the electric screwdriver drives the screw at a fixed speed until the tightening operation is completed.

[0004] While torque and speed parameters are pre-set and remain fixed during the tightening process, in actual tightening operations, the load changes dynamically depending on factors such as the screw penetration depth and the material and structure of the connected parts. This can easily lead to slippage between the motor-connected bit and the screw during tightening.

[0005] Therefore, how to prevent slippage between the screwdriver bit and the screw connected to the motor becomes a technical problem that needs to be solved. Summary of the Invention

[0006] In view of this, the present invention provides a method and device for controlling the speed of a motor.

[0007] In a first aspect, the present invention provides a method for controlling the speed of a motor, the method comprising: collecting the pressure at a current moment and associated data of the motor at the current moment; wherein the pressure is the pressure of the screwdriver bit and the screw connected to the motor, and the associated data includes the speed of the motor; determining the motor fluctuation frequency at the current moment based on the associated data of the motor at the current moment and the associated data of the motor at a previous moment before the current moment; determining the slip coefficient at the current moment based on the motor fluctuation frequency at the current moment and the pressure at the current moment; when the slip coefficient at the current moment is not less than the slip coefficient threshold, controlling the speed of the motor according to the target speed.

[0008] In a second aspect, the present invention provides a device for controlling the rotational speed, which includes: an acquisition module for collecting the pressure at a current moment and associated data of the motor at the current moment; wherein the pressure is the pressure of the screwdriver bit and the screw connected to the motor, and the associated data includes the rotational speed of the motor; a first determination module for determining the motor fluctuation frequency at the current moment based on the associated data of the motor at the current moment and the associated data of the motor at the previous moment at the current moment; a second determination module for determining the slip coefficient at the current moment based on the motor fluctuation frequency at the current moment and the pressure at the current moment; and a control module for controlling the rotational speed of the motor according to the target rotational speed when the slip coefficient at the current moment is not less than the slip coefficient threshold.

[0009] In a third aspect, the present invention provides a computer device comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the method for controlling the motor speed of the first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0010] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the method for controlling the motor speed according to the first aspect or any corresponding embodiment thereof.

[0011] In a fifth aspect, the present invention provides a computer program product comprising computer instructions for causing a computer to execute the method for controlling the speed of a motor according to the first aspect or any corresponding embodiment thereof.

[0012] The method for controlling the motor speed provided in this embodiment takes into account that a fixed torque and speed approach may cause slippage between the bit and the screw connected to the motor. This application collects the pressure between the bit and the screw connected to the motor and the speed of the motor at the current moment, and determines the motor fluctuation frequency at the current moment based on the motor speed at the current moment and the speed of the motor at the previous moment. The slip coefficient at the current moment is determined based on the motor fluctuation frequency and the pressure at the current moment, and when the slip coefficient at the current moment is not less than the slip coefficient threshold, the motor speed is controlled according to the target speed. That is, the risk of slippage between the bit and the screw connected to the motor is determined based on the motor fluctuation frequency and the pressure at the current moment. When there is a risk of slippage between the bit and the screw connected to the motor, the motor speed is dynamically adjusted to avoid slippage between the bit and the screw connected to the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 is a schematic diagram of a system for controlling motor speed according to an embodiment of the present invention;

[0015] Figure 2 is a flow chart of a method for controlling motor speed according to an embodiment of the present invention;

[0016] Figure 3 is another flowchart of a method for controlling motor speed provided in accordance with an embodiment of the present invention;

[0017] Figure 4 It is a structural diagram of a computer device provided by an optional embodiment of the present invention. DETAILED DESCRIPTION

[0018] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0019] Please refer to Figure 1 , Figure 1 FIG. 1 is a schematic diagram of a system for controlling motor speed according to an embodiment of the present invention. The system includes:

[0020] A pressure sensor, a current sensor, a speed sensor, a torque sensor, a register, a microprocessor, and a motor. The pressure sensor, the current sensor, the speed sensor, the torque sensor are respectively connected to the register for communication, and the register and the motor are respectively connected to the microprocessor for communication.

[0021] The pressure sensor detects the pressure between the bit and screw connected to the motor, the current sensor detects the motor current, the speed sensor detects the motor speed, and the torque sensor detects the motor torque. The register stores the pressure between the bit and screw connected to the motor, the motor current, the motor speed, and the motor torque. The microprocessor retrieves the pressure between the bit and screw connected to the motor, the motor current, the motor speed, and the motor torque from the registers. Based on these pressure, current, speed, and torque, the microprocessor determines the motor slip coefficient and controls the motor speed according to the target speed.

[0022] According to an embodiment of the present invention, an embodiment of a method for controlling the speed of a motor is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0023] In this embodiment, a method for controlling the speed of a motor is provided, which can be used for a microprocessor in a system for controlling the speed of a motor. Figure 2 FIG. 1 is a flow chart of a method for controlling motor speed according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0024] Step S201 , collecting the current pressure and the associated data of the motor at the current moment; wherein the pressure is the pressure of the screwdriver bit and the screw connected to the motor, and the associated data includes the rotational speed of the motor.

[0025] When the screw needs to be tightened, the motor can be rotated to drive the screwdriver bit connected to the motor to rotate, and the rotation of the screwdriver bit connected to the motor drives the screw to rotate, so that the screw is tightened.

[0026] The current moment can be the moment when the motor rotates and the screwdriver connected to the motor rotates. The pressure is the pressure between the screwdriver connected to the motor and the screw.

[0027] The associated data may be data generated during the rotation of the motor, wherein the associated data may include the rotation speed of the motor.

[0028] As an example, the associated data may also include the current of the motor, the torque of the motor, the vibration frequency of the motor, etc., which are not specifically limited here.

[0029] The current pressure on the screwdriver bit and screw connected to the motor can be detected by a high-precision pressure sensor pre-installed in the motor. Specifically, the high-precision pressure sensor pre-installed in the motor can detect the pressure on the screwdriver bit and screw connected to the motor in real time. That is, while the motor is operating, the high-precision pressure sensor pre-installed in the motor can detect the pressure on the screwdriver bit and screw connected to the motor in real time.

[0030] The current motor data can be obtained using Hall effect sensors pre-installed on the motor, or by back-EMF detection. The back-EMF detection method includes the following steps: When the motor rotates, a back-EMF is generated in the stator windings. The frequency of the back-EMF is proportional to the motor's speed. The motor's speed can be calculated by detecting the zero crossing point or frequency of the back-EMF.

[0031] Step S202 : determining the motor fluctuation frequency at the current moment based on the associated data of the motor at the current moment and the associated data of the motor at a moment before the current moment.

[0032] The previous moment of the current moment is the moment before the current moment. The previous moment can be the moment immediately before the current moment, or multiple moments before the current moment. For example, if the current moment is t, the previous moment of the current moment can be t-1. For another example, if the current moment is t, the previous moments of the current moment can be t-1, t-2, ..., tn, where t is greater than n.

[0033] The motor fluctuation frequency indicates the frequency at which the motor fluctuates around a certain stable value, which can indicate whether there is slippage between the screwdriver bit and the screw connected to the motor. After determining the associated data of the motor at the current moment and the associated data of the motor at the previous moment, the current motor fluctuation frequency can be further determined based on the associated data of the motor at the current moment and the associated data of the motor at the previous moment.

[0034] As an example, when the associated data includes the rotational speed of the motor, the motor fluctuation frequency at the current moment may be determined by the average of the rotational speed of the motor at the current moment and the rotational speed of the motor at moments before the current moment.

[0035] As an example, a dynamic model can be pre-constructed, wherein the speed of the motor at the current moment and the speed of the motor at the previous moment can be used as inputs of the dynamic model, and the motor fluctuation frequency at the current moment can be used as output of the dynamic model.

[0036] Step S203: determining the current slip coefficient according to the current motor fluctuation frequency and the current pressure.

[0037] As can be seen from the above, the pressure is the pressure between the bit and the screw connected to the motor. The motor fluctuation frequency at the current moment can indicate whether there is slippage between the bit and the screw connected to the motor. After determining the motor fluctuation frequency and the pressure at the current moment, the slip coefficient at the current moment can be further determined.

[0038] As an example, the slip coefficient at the current moment can be determined using the following formula:

[0039] ; Among them, ΔV is the motor fluctuation frequency, P is the pressure, and R is the slip coefficient. 、 is the coefficient.

[0040] As an example, a dynamic model may be pre-constructed, wherein the motor fluctuation frequency and the pressure of the motor at the current moment may be used as inputs of the dynamic model, and the slip coefficient at the current moment may be used as output of the dynamic model.

[0041] Step S204 : When the current slip coefficient is not less than the slip coefficient threshold, the speed of the motor is controlled according to the target speed.

[0042] The slip coefficient threshold may be a preset value.

[0043] As an example, the slip coefficient threshold value may be determined from a preset slip coefficient threshold value database based on the current correlation data and the current pressure. The preset slip coefficient threshold value database may be constructed using a machine learning algorithm.

[0044] When the slip coefficient at the current moment is not less than the slip coefficient threshold, it indicates that slippage may occur between the bit connected to the motor and the screw at the current moment. Therefore, the speed of the motor needs to be adjusted to avoid slippage between the bit connected to the motor and the screw. The target speed can be a speed at which the bit connected to the motor does not slip. The target speed can be a pre-set speed, and the target speed can be related to the type of screw, that is, after determining the type of screw, the target speed can be determined according to the type of screw. Controlling the speed of the motor according to the target speed can avoid slippage of the bit connected to the motor.

[0045] The method for controlling the motor speed provided in this embodiment takes into account that a fixed torque and speed approach may cause slippage between the bit and the screw connected to the motor. This application collects the pressure between the bit and the screw connected to the motor and the speed of the motor at the current moment, and determines the motor fluctuation frequency at the current moment based on the motor speed at the current moment and the speed of the motor at the previous moment. The slip coefficient at the current moment is determined based on the motor fluctuation frequency and the pressure at the current moment, and when the slip coefficient at the current moment is not less than the slip coefficient threshold, the motor speed is controlled according to the target speed. That is, the risk of slippage between the bit and the screw connected to the motor is determined based on the motor fluctuation frequency and the pressure at the current moment. When there is a risk of slippage between the bit and the screw connected to the motor, the motor speed is dynamically adjusted to avoid slippage between the bit and the screw connected to the motor.

[0046] In one possible implementation, the method further includes:

[0047] Step S301, according to the type of screw, determine the motor control parameters corresponding to the type of screw from a preset database; wherein the motor control parameters include: a speed threshold and a speed at an initial moment, wherein the speed threshold is greater than the target speed, and the initial moment is before the current moment.

[0048] The motor's rotation drives the screwdriver bit connected to the motor, which in turn drives the screw. The screw tightening process can be divided into three stages: an initial stage, a critical stage, and a final stage. The initial stage can be when the motor rotates rapidly, the critical stage can be when the current slip coefficient is no less than a slip coefficient threshold, and the final stage can be when the screw is tightened.

[0049] In this embodiment, for the initial stage, the rotation speed at the initial moment of the initial stage can be determined, that is, the motor rotates rapidly according to the rotation speed at the initial moment.

[0050] The screw type may indicate the type of screw. For example, the screw may be a self-tapping screw, a machine screw, etc., without specific limitation herein. The preset database may pre-store the correspondence between the screw type and the motor control parameters.

[0051] The speed threshold may indicate a limit value of the target speed in the critical stage. The speed threshold is greater than the target speed. The motor control parameters may indicate parameters for controlling the operation of the motor. The motor control parameters may include a speed threshold and a speed at an initial moment. The correspondence between the type of screw and the speed threshold may also be pre-stored in the preset database, that is, after determining the type of screw, the speed threshold may be determined, and further the target speed may be determined when the slip coefficient at the current moment is not less than the slip coefficient threshold.

[0052] Step S302: Control the motor according to the rotation speed at the initial moment.

[0053] During the initial stage of the motor, the motor speed can be controlled by the initial speed. For example, during the initial stage, the motor maintains the initial speed (such as 1200 RPM) to quickly screw in a screw.

[0054] The motor speed control method provided in this embodiment, by setting a speed threshold, can prevent the target speed from exceeding the speed threshold, thereby preventing slippage between the screw bit and the screw connected to the motor. Furthermore, by determining the corresponding motor control parameters based on the screw type from a preset database, the motor control strategy can be matched to the screw characteristics, ensuring that various types of screws can be tightened correctly and effectively. Furthermore, by controlling the motor based on the initial speed, screw tightening can be achieved quickly.

[0055] Please refer to Figure 3 , Figure 3 2 is another flow chart of a method for controlling motor speed according to an embodiment of the present invention.

[0056] In a possible implementation, the associated data also includes: current, torque, and vibration frequency; and Figure 3 As shown, the method includes:

[0057] Step S301, collect the current pressure and the associated data of the motor at the current moment; wherein the pressure is the pressure of the screwdriver bit connected to the motor, and the associated data includes the speed of the motor. Figure 2 Step S201 in the above process will not be described in detail here.

[0058] Step S302 : determining the motor fluctuation frequency at the current moment based on the associated data of the motor at the current moment and the associated data of the motor at a moment before the current moment.

[0059] Specifically, the above step S302 includes:

[0060] In step S3021, the current change rate is determined based on the current of the motor at the current moment and the current of the motor at a moment before the current moment.

[0061] The motor current can indicate the current output of the motor at the current moment. The motor torque can indicate the driving force that causes the output shaft of the motor to generate rotational motion at the current moment. The motor vibration frequency can indicate the number of times the motor completes vibration at the current moment.

[0062] In specific implementation, the current of the motor can be detected by an ammeter or by a motor driver. No specific limitation is made here and it can be implemented by those skilled in the art.

[0063] The torque of the motor may be detected by a static torque sensor or a dynamic torque sensor, which is not specifically limited here and can be implemented by those skilled in the art.

[0064] The vibration frequency of the motor can be detected by a three-axis accelerometer built into the motor, or by other devices capable of detecting vibration frequency. No specific limitation is made here and it can be implemented by those skilled in the art.

[0065] The current change rate may indicate the current change from a previous moment to a current moment. The current change rate may be determined by the difference between the current at the current moment and the current of the motor at a moment before the current moment, and the time difference between the current moment and the moment before the current moment.

[0066] As an example, when there are multiple motor currents at the previous moments before the current moment, the average value of the motor current at the previous moments can be determined first. Then, the current change rate can be determined based on the difference between the average value of the motor current at the previous moments and the current moment, and the time difference between the current moment and the immediately preceding moment. For example, if the current moment is t, the current at the current moment is A, and the previous moments include t-1, t-2, and t-3, the current at t-1 is A1, the current at t-2 is A2, and the current at t-3 is A3, the average current value can be (A1+A2+A3) / 3. The current change rate can be (A - (A1+A2+A3) / (the duration from t-1 to t).

[0067] In step S3022, the torque change rate is determined based on the torque of the motor at the current moment and the torque of the motor at a moment before the current moment.

[0068] The torque change rate may indicate a change in torque from a previous moment to a current moment. The torque change rate may be determined by the difference between the torque at the current moment and the torque of the motor at the previous moment, and the time difference between the current moment and the previous moment.

[0069] As an example, when the number of previous moments of the motor at the current moment is multiple, the average value of the torque of the motor at the previous moment of the current moment can be determined first, and then the torque change rate can be determined based on the difference between the average value of the torque of the motor at the previous moment of the current moment and the torque at the current moment, and the time difference between the current moment and the most adjacent previous moment of the current moment.

[0070] In step S3023, the speed change rate is determined based on the speed of the motor at the current moment and the speed of the motor at a moment before the current moment.

[0071] The speed change rate may indicate a change in speed from a previous moment to a current moment. The speed change rate may be determined by the difference between the current moment's speed and the motor's speed at a moment prior to the current moment, and the time difference between the current moment and the moment prior to the current moment.

[0072] As an example, when there are multiple previous moments of the motor at the current moment, the average value of the motor's speed at the previous moment of the current moment can be determined first, and then the speed change rate can be determined based on the difference between the average value of the motor's speed at the previous moment of the current moment and the speed at the current moment, and the time difference between the current moment and the most adjacent previous moment of the current moment.

[0073] In step S3024, the vibration frequency change rate is determined based on the vibration frequency of the motor at the current moment and the vibration frequency of the motor at a moment before the current moment.

[0074] The vibration frequency change rate may indicate a change in the vibration frequency from a previous moment to the current moment. The vibration frequency change rate may be determined by the difference between the vibration frequency at the current moment and the vibration frequency of the motor at the previous moment, and the time difference between the current moment and the previous moment.

[0075] As an example, when the number of previous moments of the motor at the current moment is multiple, the average value of the vibration frequency of the motor at the previous moment of the current moment can be determined first, and then the vibration frequency change rate can be determined based on the difference between the average value of the vibration frequency of the motor at the previous moment of the current moment and the vibration frequency at the current moment, and the time difference between the current moment and the most adjacent previous moment of the current moment.

[0076] In step S3025, the motor fluctuation frequency at the current moment is determined based on the current change rate, the torque change rate, the speed change rate, and the vibration frequency change rate.

[0077] After determining the current change rate, torque change rate, speed change rate, and vibration frequency change rate, the motor fluctuation frequency can be determined based on the current change rate, torque change rate, speed change rate, and vibration frequency change rate.

[0078] As an example, the motor pulsation frequency may be determined using the following formula.

[0079] ; Among them, ΔI is the current change rate, ΔN is the torque change rate, Δr is the speed change rate, ρ is the rate of change of vibration frequency, 、 、 、 is the coefficient.

[0080] As an example, a dynamic model can be used to determine the motor fluctuation frequency. The current change rate, torque change rate, speed change rate, and vibration frequency change rate can be used as inputs to the dynamic model, and the motor fluctuation frequency can be used as output.

[0081] Step S303: Determine the current slip coefficient based on the current motor fluctuation frequency and the current pressure. Figure 2 Step S203 in the above process will not be described in detail here.

[0082] Step S304: When the current slip coefficient is not less than the slip coefficient threshold, the motor speed is controlled according to the target speed. Figure 2 Step S204 in the above process will not be described in detail here.

[0083] The method for controlling the motor speed provided in this embodiment not only takes into account the motor speed, but also takes into account the influence of current, torque and vibration frequency on the motor fluctuation frequency. By determining the current change rate, torque change rate, speed change rate and vibration frequency change rate, the motor fluctuation frequency can be determined more accurately, thereby more accurately determining whether slippage occurs between the screwdriver bit and the screw connected to the motor.

[0084] In a possible implementation, controlling the speed of the motor according to the target speed in step S204 includes one of step S2041 and step S2042.

[0085] In step S2041, the speed of the motor is controlled to be the target speed.

[0086] In this embodiment, the target speed may be a fixed value. After the target speed is determined, the speed of the motor may be controlled at the target speed, and the speed of the motor may be controlled according to the target speed.

[0087] In step S2042 , the rotation speed of the motor is alternately controlled to be one of a target maximum rotation speed and a target minimum rotation speed.

[0088] In this embodiment, the target speed may be a range of values, wherein the range of the target speed in the pulse mode may be determined, wherein the range may be a pre-set range, for example, 200-500 RPM.

[0089] After the range value is determined, a target maximum speed and a target minimum speed within the range value may be determined, and then the speed of the motor may be alternately controlled according to the target maximum speed and the target minimum speed.

[0090] When alternating between a target maximum speed and a target minimum speed, the PID control algorithm can be used to achieve this. By comparing the deviation between the actual value and the currently required target maximum speed or target minimum speed, the actual value accurately tracks the target value through the regulation of the proportional, integral, and differential links. The proportional link (P) adjusts based on the current deviation; the larger the deviation, the stronger the regulation. The integral link (I) adjusts based on the accumulated deviation to eliminate the system's steady-state error. The differential link (D) adjusts based on the rate of change of the deviation to predict future system trends and improve system response speed and stability.

[0091] The method for controlling motor speed provided in this embodiment, on the one hand, controls the motor speed by maintaining a stable target speed, thereby preventing slippage between the screw and the bit connected to the motor. On the other hand, by alternately controlling the motor speed to either a target maximum speed or a target minimum speed, the accuracy of motor speed control can be improved, thereby preventing slippage between the screw and the bit connected to the motor.

[0092] In a possible implementation, after step S204, the method further includes:

[0093] Step S205, when the time duration for controlling the speed of the motor according to the target speed reaches a preset time duration and the pressure of the bit and screw connected to the motor is greater than the pressure threshold, perform at least one incremental operation until the target speed reaches the speed critical value; wherein, the incremental operation includes: determining the sum of the initial speed and the increase as the intermediate speed targeted by the incremental operation; wherein, the initial speed targeted by the first incremental operation is the target speed; within the time period corresponding to the incremental operation, the speed of the motor is controlled to be the intermediate speed.

[0094] The preset duration can be a pre-set duration. The preset duration can be 2 seconds or 3 seconds, and can be set based on actual needs, and is not specifically limited here. The pressure threshold can be a pre-set threshold. When the pressure between the screwdriver bit connected to the motor and the screw exceeds the pressure threshold, it can indicate that the connection between the screwdriver bit connected to the motor and the screw is stable.

[0095] As can be seen above, the process of tightening the screw can be divided into three stages: the rotation of the motor drives the screwdriver bit connected to the motor to rotate, and the rotation of the screwdriver bit connected to the motor drives the screw to rotate. These three stages can be divided into an initial stage, a critical stage, and a final stage. The initial stage can be the stage of rapid motor rotation, the critical stage can be the stage when the current slip coefficient is not less than the slip coefficient threshold, and the final stage can be the stage of tightening the screw.

[0096] When the time duration for controlling the motor speed according to the target speed reaches a preset time duration and the pressure between the bit connected to the motor and the screw is greater than a pressure threshold, the final stage may be entered to tighten the screw.

[0097] After entering the final stage, the speed may be increased starting from the initial speed, wherein the initial speed targeted by the first incremental operation is the target speed, that is, starting from the target speed, the speed is increased by the target speed according to the speed increase amount.

[0098] The intermediate speed may be the speed after each increment. During each increment, the motor speed may be controlled using the intermediate speed until the speed reaches a critical speed value. The critical speed value may be a pre-set value. For example, the critical speed value may be 800 RPM.

[0099] For example, the increase may be 20, the initial speed for the first increment operation may be 500RPM, the speed critical value may be 800RPM, the initial speed may increase by 20 to 520RPM, wherein 520RPM may be the intermediate speed, until the intermediate speed reaches 800RPM, the speed of the motor is controlled according to the speed critical value until the screw is tightened.

[0100] In one possible implementation, while controlling the motor speed based on a speed threshold, the motor current, motor torque, and motor vibration frequency may be continuously detected. The motor fluctuation frequency is determined based on the speed threshold, the motor current, motor torque, and motor vibration frequency. Furthermore, the slip coefficient is determined based on the motor fluctuation frequency and the pressure between the screwdriver bit and the screw connected to the motor. If the slip coefficient is not less than the slip coefficient threshold, steps S204 and S205 are repeated until the motor speed reaches zero.

[0101] In a possible implementation, please refer to Table 1, which shows the triggering conditions and control strategies of the initial stage, critical stage, and final stage.

[0102] Table 1

[0103]

[0104] In the method for controlling motor speed provided in this embodiment, when the pressure between the screwdriver bit and the motor is greater than a pressure threshold, continuing to operate at the original target speed may result in insufficient motor torque and an inability to effectively tighten the screw. By gradually increasing the motor speed through incremental operation, the motor can better adapt to high-load conditions and ensure that the screw can be tightened smoothly.

[0105] Furthermore, the incremental operation allows the motor to gradually increase its output power during the tightening process, preventing damage to the screw or workpiece caused by the sudden application of excessive torque. At the same time, by gradually increasing the motor speed, the screw can be tightened more evenly, reducing loosening or undertightening, and improving the quality and reliability of tightening.

[0106] In one possible implementation, the method further includes:

[0107] Step a1, obtaining the speed value of the intermediate speed.

[0108] Step a2: determining the increment for each increment operation according to the intermediate speed value and a preset increment mapping table; wherein the increment for the current increment operation is greater than the increment for the next increment operation.

[0109] The preset increment mapping table may store a mapping relationship between intermediate speeds and preset increments. For example, when the intermediate speed is 600 RPM, the preset increment may be 40; when the intermediate speed is 700 RPM, the preset increment may be 30, etc. After determining the speed value of the intermediate speed, the increment for the incremental operation may be determined from the preset increment mapping table.

[0110] Step a3: When the sum of the intermediate speed targeted by any incremental operation and the increment is not greater than the speed threshold, the intermediate speed targeted by the incremental operation is determined according to the increment targeted by the incremental operation.

[0111] Step a4: when the sum of the intermediate speed and the increase amount in any one increment operation is greater than the speed threshold, the intermediate speed is increased to the speed critical value.

[0112] When the sum of the intermediate speed and the increase at a certain time is greater than the speed critical value, it is only necessary to increase the intermediate speed to the speed critical value. When the sum of the intermediate speed and the increase at a certain time is not greater than the speed critical value, it is increased to the intermediate speed according to the increase.

[0113] The method for controlling the motor speed provided in this embodiment can quickly increase the intermediate speed by setting the corresponding relationship between the intermediate speed and the increase amount to speed up the screw tightening process. At the same time, it takes into account that the intermediate speed does not exceed the speed critical value, thereby avoiding slippage between the screwdriver bit connected to the motor and the screw.

[0114] In one possible implementation, the method further includes:

[0115] Step S201 : determining the preset ratio as the increment corresponding to the first incremental operation and the increment corresponding to the non-first incremental operation.

[0116] When the increment is a fixed value, the preset ratio can be determined as the increment corresponding to the first incremental operation and the increment corresponding to the non-first incremental operation. The increment corresponding to the first incremental operation and the increment corresponding to the non-first incremental operation can be a ratio, such as 5%. That is, based on the intermediate speed corresponding to the current incremental operation, the speed is increased by 5% of the intermediate speed corresponding to the current incremental operation to obtain the intermediate speed corresponding to the next incremental operation.

[0117] The method for controlling the motor speed provided in this embodiment, when a preset ratio is used to determine the increase, regardless of the initial speed, the speed change brought about by each incremental operation is a fixed ratio relative to the current speed. By making the incremental increase in speed proportional to the current speed, it can better adapt to the speed setting under different working conditions.

[0118] In one possible implementation, the method further includes:

[0119] Step S202: determining the preset difference as the increment corresponding to the first increment operation and the increment corresponding to the non-first increment operation.

[0120] When the increment is a fixed value, the preset difference can be determined as the increment corresponding to the first increment operation and the increment corresponding to a non-first increment operation. The increment corresponding to the first increment operation and the increment corresponding to a non-first increment operation can be a fixed value, such as 20, which means that the difference between the intermediate speed corresponding to the next increment operation and the intermediate speed corresponding to the previous increment operation can be 20.

[0121] The method for controlling the motor speed provided in this embodiment uses a preset difference value to determine the increment. Each increment operation causes the speed to increase by a fixed value, thereby achieving precise control of the speed change.

[0122] In one possible implementation, the method further includes:

[0123] Step S301: Control the display device to issue an early warning, and control the regulating device to apply pressure to the screwdriver bit connected to the motor.

[0124] When the time for controlling the motor speed according to the target speed reaches a preset time and the pressure of the bit and screw connected to the motor is greater than the pressure threshold, at least one incremental operation is performed until the target speed reaches the speed critical value. If it is detected that the slip coefficient is not less than the slip coefficient threshold, it indicates that the pressure of the bit and screw connected to the motor is insufficient, and an early warning can be issued through the display device.

[0125] As an example, the display device may be an LED light, and the warning may be issued by flashing the LED light.

[0126] As an example, the display device can display warning text and issue an early warning through the warning text.

[0127] After the control display device issues a warning, the adjustment device can be controlled to apply pressure to the screwdriver bit connected to the motor. The adjustment device can be a device (such as a robotic arm) that controls the screwdriver bit connected to the motor. The adjustment device can apply pressure to the screwdriver bit connected to the motor to stabilize the connection between the screwdriver bit connected to the motor and the screw.

[0128] In one possible implementation, during the processing of the initial stage, critical stage, and final stage, the motor current, motor torque, motor vibration frequency, pressure of the bit and screw connected to the motor, and slip coefficient can be recorded and stored in real time to support subsequent optimization and improvement of the processing of the initial stage, critical stage, and final stage.

[0129] In the method for controlling motor speed provided in this embodiment, when the slip coefficient is less than a slip coefficient threshold, the connection between the motor-connected bit and the screw is unstable. By applying pressure to the motor-connected bit, the pressure between the bit and the screw can be increased to prevent slippage between the bit and the screw. Furthermore, controlling the display device to issue an early warning effectively alerts technicians, allowing them to promptly understand potential slippage between the bit and the screw.

[0130] In this embodiment, a device for controlling the speed of a motor is also provided. The device is used to implement the above-mentioned embodiments and preferred embodiments, and the details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0131] This embodiment provides a device for controlling the speed of a motor, which includes: an acquisition module for collecting the pressure at a current moment and associated data of the motor at the current moment; wherein the pressure is the pressure of the screwdriver bit and the screw connected to the motor, and the associated data includes the speed of the motor; a first determination module for determining the motor fluctuation frequency at the current moment based on the associated data of the motor at the current moment and the associated data of the motor at a previous moment at the current moment; a second determination module for determining the slip coefficient at the current moment based on the motor fluctuation frequency at the current moment and the pressure at the current moment; and a control module for controlling the speed of the motor according to the target speed when the slip coefficient at the current moment is not less than the slip coefficient threshold.

[0132] In one possible implementation, the associated data also includes: current, torque and vibration frequency; and the above-mentioned first determination module includes: a first determination unit, used to determine the current change rate based on the current of the motor at the current moment and the current of the motor at the previous moment; a second determination unit, used to determine the torque change rate based on the torque of the motor at the current moment and the torque of the motor at the previous moment; a third determination unit, used to determine the speed change rate based on the speed of the motor at the current moment and the speed of the motor at the previous moment; a fourth determination unit, used to determine the vibration frequency change rate based on the vibration frequency of the motor at the current moment and the vibration frequency of the motor at the previous moment; a fifth determination unit, used to determine the motor fluctuation frequency at the current moment based on the current change rate, the torque change rate, the speed change rate and the vibration frequency change rate.

[0133] In a possible implementation, the control module includes: a first control unit, configured to control the rotational speed of the motor to be a target rotational speed.

[0134] In a possible implementation, the control module includes: a second control unit, configured to alternately control the rotational speed of the motor to be one of a target maximum rotational speed and a target minimum rotational speed.

[0135] In one possible implementation, the device further includes: a repeated execution module configured to execute at least one incremental operation until the target speed reaches a critical speed value when the duration of controlling the speed of the motor according to the target speed reaches a preset duration and the pressure of the bit and screw connected to the motor is greater than a pressure threshold; wherein the incremental operation includes: determining the sum of the initial speed and the increase as the intermediate speed targeted by the incremental operation; wherein the initial speed targeted by the first incremental operation is the target speed; and within a time period corresponding to the incremental operation, controlling the speed of the motor to be the intermediate speed.

[0136] In a possible implementation, the apparatus further includes: a third determining module configured to determine the preset ratio as an increment corresponding to a first incremental operation and an increment corresponding to a non-first incremental operation.

[0137] In a possible implementation, the apparatus further includes: a fourth determining module configured to determine the preset difference as an increment corresponding to a first incremental operation and an increment corresponding to a non-first incremental operation.

[0138] In a possible implementation, the apparatus further includes: an early warning control module, configured to control the display device to issue an early warning, and to control the regulating device to apply pressure to the screwdriver bit connected to the motor.

[0139] In one possible implementation, the above-mentioned device also includes: a fifth determination module, which is used to determine the motor control parameters corresponding to the type of screw from a preset database according to the type of screw; wherein the motor control parameters include: a speed threshold and a speed at an initial moment, wherein the speed threshold is greater than the target speed, and the initial moment is before the current moment; an initial control module, which is used to control the motor according to the speed at the initial moment.

[0140] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0141] In this embodiment, the device for controlling the motor speed is presented in the form of a functional unit, where the functional unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0142] An embodiment of the present invention further provides a computer device having the above-mentioned device for controlling the motor speed.

[0143] See also Figure 4 , Figure 4 is a structural diagram of a computer device provided by an optional embodiment of the present invention, such as Figure 4 As shown, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in the memory or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Equally, multiple computer devices can be connected, and each device provides part of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 4 A processor 10 is taken as an example.

[0144] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0145] The memory 20 stores instructions that can be executed by at least one processor 10, so as to enable at least one processor 10 to execute the method shown in the above embodiment.

[0146] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0147] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0148] The computer device further includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Figure 4 The bus connection is taken as an example.

[0149] The input device 30 can receive input digital or character information and generate key signal input related to user settings and function control of the computer device. Examples include a touch screen, keypad, mouse, trackpad, touchpad, pointing stick, one or more mouse buttons, trackball, joystick, etc. The output device 40 may include a display device, auxiliary lighting devices (e.g., LEDs), and tactile feedback devices (e.g., vibration motors). Such display devices include, but are not limited to, liquid crystal displays, light emitting diodes, monitors, and plasma displays. In some optional embodiments, the display device may be a touch screen.

[0150] The computer device further includes a communication interface for the computer device to communicate with other devices or a communication network.

[0151] The embodiment of the present invention also provides a computer-readable storage medium. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0152] A portion of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the form in which the computer program instruction exists in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc. Accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium that can be accessed by the computer.

[0153] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for controlling the speed of a motor, characterized in that: The method comprises: Collecting the current pressure and the associated data of the motor at the current moment; wherein the pressure is the pressure of the screwdriver bit and the screw connected to the motor, and the associated data includes the speed of the motor; determining a motor fluctuation frequency at a current moment according to the associated data of the motor at a current moment and the associated data of the motor at a previous moment; Determining a slip coefficient at a current moment according to the motor fluctuation frequency and the pressure at a current moment; When the slip coefficient at the current moment is not less than the slip coefficient threshold, the rotation speed of the motor is controlled according to the target rotation speed.

2. The method for controlling the motor speed according to claim 1, wherein: The associated data further includes: current, torque, and vibration frequency; and determining the motor fluctuation frequency at the current moment based on the associated data of the motor at the current moment and the associated data of the motor at a previous moment at the current moment, including: Determine a current change rate based on the current of the motor at a current moment and the current of the motor at a moment before the current moment; determining a torque change rate based on the torque of the motor at a current moment and the torque of the motor at a moment before the current moment; Determine a rate of change of the speed of the motor according to the speed of the motor at the current moment and the speed of the motor at a moment before the current moment; Determining a vibration frequency change rate based on the vibration frequency of the motor at a current moment and the vibration frequency of the motor at a moment before the current moment; The motor fluctuation frequency at the current moment is determined according to the current change rate, torque change rate, speed change rate and vibration frequency change rate.

3. The method for controlling the motor speed according to claim 1, wherein: The controlling the rotational speed of the motor according to the target rotational speed includes: Control the motor speed to the target speed; or, The rotation speed of the motor is alternately controlled to be one of a target maximum rotation speed and a target minimum rotation speed.

4. The method for controlling the motor speed according to claim 1, wherein: After controlling the speed of the motor according to the target speed, the method further includes: When the time duration for controlling the speed of the motor according to the target speed reaches a preset time duration and the pressure between the bit and the screw connected to the motor is greater than a pressure threshold, performing at least one increment operation until the target speed reaches a critical speed value; wherein the increment operation includes: The sum of the initial speed and the increase is determined as the intermediate speed targeted by the incremental operation; wherein the initial speed targeted by the first incremental operation is the target speed; During the time period corresponding to the incremental operation, the rotational speed of the motor is controlled to be the intermediate rotational speed.

5. The method for controlling the motor speed according to claim 4, characterized in that: The method further comprises: Determine the preset ratio as the increment corresponding to the first incremental operation and the increment corresponding to the non-first incremental operation; or The preset difference is determined as the increment corresponding to the first increment operation and the increment corresponding to the non-first increment operation.

6. The method for controlling the motor speed according to claim 4, characterized in that: When the time duration for controlling the speed of the motor according to the target speed reaches a preset time duration and the pressure between the bit and the screw connected to the motor is greater than a pressure threshold, performing at least one increment operation until the target speed reaches a critical speed value, the method further includes: The control display device issues an early warning, and the control regulating device applies pressure to the screwdriver bit connected to the motor.

7. The method for controlling the motor speed according to any one of claims 1 to 6, characterized in that: Before collecting the pressure at the current moment and the associated data of the motor at the current moment, the method further includes: Determining motor control parameters corresponding to the screw type from a preset database according to the screw type; wherein the motor control parameters include: a speed threshold and a speed at an initial moment, wherein the speed threshold is greater than the target speed and the initial moment is before the current moment; The motor is controlled according to the rotation speed at the initial moment.

8. A device for controlling the speed of a motor, characterized in that: The device comprises: An acquisition module, configured to acquire the current pressure and associated data of the motor at the current moment; wherein the pressure is the pressure of the screwdriver bit and the screw connected to the motor, and the associated data includes the speed of the motor; a first determining module, configured to determine a motor fluctuation frequency at a current moment based on the associated data of the motor at the current moment and the associated data of the motor at a previous moment before the current moment; a second determining module, configured to determine a slip coefficient at a current moment according to the motor fluctuation frequency and the pressure at the current moment; The control module is configured to control the rotational speed of the motor according to a target rotational speed when the slip coefficient at the current moment is not less than a slip coefficient threshold.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method for controlling the motor speed according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the method for controlling the speed of a motor according to any one of claims 1 to 7.

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