Method and device for controlling rotating speed of motor

Abstract

The invention relates to the technical field of electric tools, and discloses a method and device for controlling the rotating speed of a motor. The method comprises the following steps: acquiring pressure at the current moment and associated data of a motor at the current moment; determining the fluctuation frequency of the motor at the current moment according to the associated data of the motor at the current moment and the associated data of the motor at the previous moment of the current moment; determining a slip coefficient at the current moment according to the motor fluctuation frequency at the current moment and the pressure at the current moment; when the slipping coefficient at the current moment is not smaller than the slipping coefficient threshold value, the rotating speed of the motor is controlled according to the target rotating speed, whether the risk of slipping occurs to the bit and the screw connected with the motor or not is determined according to the fluctuation frequency of the motor at the current moment and the pressure at the current moment, and when the risk of slipping occurs to the bit and the screw connected with the motor, the motor is started. By dynamically adjusting the rotating speed of the motor, slipping between the screwdriver head and the screw connected with the motor is avoided.

Description

Technical Field

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

[0002] In many fields such as industrial production, electronic equipment assembly, and furniture manufacturing, the operation of tightening screws is a key link in the product assembly process, and its tightening quality directly affects the structural stability, reliability, and service life of the product. With the development of the manufacturing industry towards automation and intelligence, higher requirements are put forward for the precision, efficiency, and consistency of screw tightening. As an important tightening tool, the electric screwdriver is widely used in various screw tightening scenarios due to its convenient operation and high efficiency.

[0003] In related technologies, the tightening process of screws is controlled by presetting a torque value or a constant rotational speed. Specifically, users can preset a torque value on the electric screwdriver according to the specifications and tightening requirements of the screws. When the torque value is reached during the tightening process, the electric screwdriver will automatically stop working to prevent over-tightening of the screws. Another way is to set a constant rotational speed, and the electric screwdriver drives the screw to rotate at a fixed rotational speed until the tightening operation is completed.

[0004] However, the torque and rotational speed parameters are preset and remain fixed during the tightening process. However, in actual tightening operations, the load dynamically changes with factors such as the screwing depth of the screw, the material and structure of the connected part, resulting in easy slippage between the bit connected to the motor and the screw during the process of tightening the screw.

[0005] Therefore, how to avoid slippage between the bit connected to the motor and the screw has become a technical problem to be solved. Summary of the Invention

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

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

[0008] In a second aspect, the present invention provides a device for controlling the rotational speed. The device includes: a collection module configured to collect the pressure at the current moment and the associated data of the motor at the current moment; wherein the pressure is the pressure between the bit connected to the motor and the screw, and the associated data includes the rotational speed of the motor; a first determination module configured to determine 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 of the current moment; a second determination module configured to determine 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 configured to control 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, including: a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to implement the method for controlling the rotational speed of the motor according to the first aspect or any corresponding embodiment thereof.

[0010] In a fourth aspect, the present invention provides a computer-readable storage medium, on which computer instructions are stored. The computer instructions are used to cause a computer to execute the method for controlling the rotational speed of the motor according to the first aspect or any corresponding embodiment thereof.

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

[0012] The method for controlling the rotational speed of the motor provided in this embodiment takes into account that the method of fixing the torque and rotational speed may cause slip between the bit connected to the motor and the screw. This application collects the pressure between the bit connected to the motor and the screw and the rotational speed of the motor at the current moment, determines the motor fluctuation frequency at the current moment based on the rotational speed of the motor at the current moment and the rotational speed of the motor at the previous moment of the current moment, determines 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 controls 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. That is, by the motor fluctuation frequency at the current moment and the pressure at the current moment, it is determined whether there is a risk of slip between the bit connected to the motor and the screw. When there is a risk of slip between the bit connected to the motor and the screw, the rotational speed of the motor is dynamically adjusted to avoid slip between the bit connected to the motor and the screw. Description of the Drawings

[0013] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0014] Figure 1 is a schematic diagram of a system for controlling the rotational speed of a motor according to an embodiment of the present invention; Figure 2 is a flowchart of a method for controlling the rotational speed of a motor according to an embodiment of the present invention; Figure 3 is another flowchart of a method for controlling the rotational speed of a motor according to an embodiment of the present invention; Figure 4 is a schematic diagram of the structure of a computer device provided by an alternative embodiment of the present invention. Specific Embodiments

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0016] Please refer to Figure 1 , Figure 1 is a schematic diagram of a system for controlling the rotational speed of a motor according to an embodiment of the present invention. The system includes: a pressure sensor, a current sensor, a rotational speed sensor, a torque sensor, a register, a microprocessor, and a motor. Among them, the pressure sensor, the current sensor, the rotational speed sensor, and the torque sensor are respectively communicatively connected to the register, and the register and the motor are respectively communicatively connected to the microprocessor.

[0017] The pressure sensor can detect the pressure between the bit connected to the motor and the screw, the current sensor can detect the current of the motor, the rotational speed sensor can detect the rotational speed of the motor, and the torque sensor can detect the torque of the motor. Among them, the register can store the pressure between the bit connected to the motor and the screw, the current of the motor, the rotational speed of the motor, and the torque of the motor. The microprocessor can obtain the pressure between the bit connected to the motor and the screw, the current of the motor, the rotational speed of the motor, and the torque of the motor from the register, and determine the slip coefficient of the motor based on the pressure between the bit connected to the motor and the screw, the current of the motor, the rotational speed of the motor, and the torque of the motor, and control the rotational speed of the motor according to the target rotational speed.

[0018] According to an embodiment of the present invention, there is provided an embodiment of a method for controlling the rotational speed of a motor. 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 the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0019] In this embodiment, a method for controlling the rotational speed of a motor is provided, which can be used by a microprocessor in a system for controlling the rotational speed of a motor. Figure 2 It is a schematic flowchart of the method for controlling the rotational speed of a motor provided according to an embodiment of the present invention, as Figure 2 shown, the process includes the following steps: Step S201, collect the pressure at the current moment and the associated data of the motor at the current moment; wherein, the pressure is the pressure between the bit connected to the motor and the screw, and the associated data includes the rotational speed of the motor.

[0020] When it is necessary to tighten the screw, the motor can be rotated to drive the bit connected to the motor to rotate, and the bit connected to the motor rotates to drive the screw to rotate, so as to tighten the screw.

[0021] The current moment can be the moment when the motor rotates to drive the bit connected to the motor to rotate. The pressure is the pressure between the bit connected to the motor and the screw.

[0022] The associated data can be the data generated during the rotation of the motor. Among them, the associated data can include the rotational speed of the motor.

[0023] As an example, the associated data can 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.

[0024] The pressure between the bit connected to the motor and the screw at the current moment can be detected by a high-precision pressure sensor pre-configured on the motor. Among them, the high-precision pressure sensor pre-configured on the motor can detect the pressure between the bit connected to the motor and the screw in real time. That is to say, during the operation of the motor, the high-precision pressure sensor pre-configured on the motor can detect the pressure between the bit connected to the motor and the screw in real time.

[0025] The associated data of the motor at the current moment can be detected by a Hall sensor pre-configured on the motor, or can be determined by the back electromotive force detection method. Among them, the specific steps of the back electromotive force detection method can include: when the motor rotates, a back electromotive force will be generated in the stator winding. The frequency of the back electromotive force is proportional to the rotational speed of the motor. By detecting the zero crossing or frequency of the back electromotive force, the rotational speed of the motor can be calculated.

[0026] Step S202: Determine 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 of the current moment.

[0027] The previous moment of the current moment is the moment before the current moment. Among them, the previous moment can be the moment immediately before the current moment, or it can be multiple consecutive moments before the current moment. For example: when the current moment is t, the previous moment of the current moment can be t - 1; Another example: when the current moment is t, the previous moment of the current moment can be t - 1, t - 2....t - n, where t is greater than n.

[0028] The motor fluctuation frequency can indicate the frequency at which the motor fluctuates up and down around a certain stable value, and it can characterize whether there is slippage between the bit connected to the motor and the screw. Among them, after determining the associated data of the motor at the current moment and the associated data of the motor at the previous moment of the current moment, the motor fluctuation frequency at the current moment 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 of the current moment.

[0029] As an example, when the associated data includes the rotational speed of the motor, the motor fluctuation frequency at the current moment can be determined by the average value of the rotational speed of the motor at the current moment and the rotational speed of the motor at the previous moment of the current moment.

[0030] As an example, a dynamic model can be pre - constructed. Among them, the rotational speed of the motor at the current moment and the rotational speed of the motor at the previous moment of the current moment can be used as the input of the dynamic model, and the motor fluctuation frequency at the current moment can be used as the output of the dynamic model.

[0031] Step S203: Determine the slip coefficient at the current moment based on the motor fluctuation frequency at the current moment and the pressure at the current moment.

[0032] As can be seen from the above, the pressure is the pressure between the bit connected to the motor and the screw. The motor fluctuation frequency at the current moment can characterize whether there is slippage between the bit connected to the motor and the screw. After determining the motor fluctuation frequency at the current moment and the pressure at the current moment, the slip coefficient at the current moment can be further determined.

[0033] As an example, the following formula can be used to determine the slip coefficient at the current moment: ; where ΔV is the motor fluctuation frequency, P is the pressure, R is the slip coefficient, 、 are coefficients.

[0034] As an example, a dynamic model can be pre-constructed, where the motor fluctuation frequency at the current moment and the pressure at the current moment of the motor can be used as the inputs of the dynamic model, and the slip coefficient at the current moment can be used as the output of the dynamic model.

[0035] Step S204: When the slip coefficient at the current moment is not less than the slip coefficient threshold, control the speed of the motor according to the target speed.

[0036] The slip coefficient threshold can be a pre-set value.

[0037] As an example, the slip coefficient threshold can be determined in a pre-set slip coefficient threshold database according to the correlation data at the current moment and the pressure at the current moment. Among them, the pre-set slip coefficient threshold database can be constructed by a machine learning algorithm.

[0038] 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, it is necessary to adjust the speed of the motor to avoid slippage between the bit connected to the motor and the screw. The target speed can be the speed at which the bit connected to the motor does not slip. Among them, the target speed can be a pre-set speed, and the target speed can be related to the type of the screw. That is, after determining the type of the screw, the target speed can be determined according to the type of the screw. Controlling the speed of the motor according to the target speed can avoid slippage of the bit connected to the motor.

[0039] The method for controlling the speed of the motor provided in this embodiment takes into account that the method of fixing torque and speed may cause slippage between the bit connected to the motor and the screw. In this application, the pressure between the bit connected to the motor and the screw and the speed of the motor at the current moment are collected, and the motor fluctuation frequency at the current moment is determined according to the speed of the motor at the current moment and the speed of the motor at the previous moment of the current moment. The slip coefficient at the current moment is determined according to 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, the speed of the motor is controlled according to the target speed. That is, the risk of slippage between the bit connected to the motor and the screw is determined through the motor fluctuation frequency at the current moment and the pressure at the current moment. When there is a risk of slippage between the bit connected to the motor and the screw, the speed of the motor is dynamically adjusted to avoid slippage between the bit connected to the motor and the screw.

[0040] In a possible implementation manner, the above method further includes: Step S301: Determine the motor control parameters corresponding to the type of the screw from a pre-set database; among them, the motor control parameters include: a speed threshold and the speed at the initial moment, where the speed threshold is greater than the target speed, and the initial moment is before the current moment.

[0041] The rotation of the motor drives the rotation of the bit connected to the motor, and the rotation of the bit connected to the motor drives the rotation of the screw, so that the process of tightening the screw can be divided into three stages. These three stages can be divided into an initial stage, a critical stage, and a final stage. Among them, the initial stage can be the stage where the motor rotates rapidly, the critical stage can be the stage where the slip coefficient at the current moment is not less than the slip coefficient threshold, and the final stage can be the stage of tightening the screw.

[0042] 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.

[0043] The type of the screw can indicate the type of the screw. For example: the screw can be a self-tapping screw, a machine thread screw, etc., and no specific limitation is made here. The preset database can pre-store the correspondence between the type of the screw and the motor control parameters.

[0044] The rotation speed threshold can indicate the limit value of the target rotation speed in the critical stage. Among them, the rotation speed threshold is greater than the target rotation speed. The motor control parameters can indicate the parameters for controlling the operation of the motor. The motor control parameters can include the rotation speed threshold and the rotation speed at the initial moment. Among them, the correspondence between the type of the screw and the rotation speed threshold can also be pre-stored in the preset database, that is, after determining the type of the screw, the rotation speed threshold can be determined, and further the target rotation speed when the slip coefficient at the current moment is not less than the slip coefficient threshold can be determined.

[0045] Step S302, control the motor according to the rotation speed at the initial moment.

[0046] When the motor is in the initial stage, the rotation speed of the motor can be controlled by the rotation speed at the initial moment. For example: in the initial stage, the motor maintains the rotation speed at the initial moment (such as 1200 RPM) to quickly screw in the screw.

[0047] The method for controlling the rotation speed of the motor provided in this embodiment can avoid the target rotation speed exceeding the rotation speed threshold by setting the rotation speed threshold, so as to avoid slipping between the bit connected to the motor and the screw. And by determining the corresponding motor control parameters according to the screw type from the preset database, the motor control strategy can be matched with the screw characteristics to ensure that various types of screws can be correctly and effectively tightened. Moreover, controlling the motor according to the rotation speed at the initial moment can quickly realize the tightening of the screw.

[0048] Please refer to Figure 3 , Figure 3 which is another schematic flowchart of the method for controlling the rotation speed of the motor according to the embodiment of the present invention.

[0049] In a possible implementation, the associated data further includes: current, torque, and vibration frequency; and in combination with Figure 3 as shown, the method includes: Step S301, collect the pressure at the current moment and the associated data of the motor at the current moment; wherein, the pressure is the pressure between the bit connected to the motor and the screw, and the associated data includes the rotational speed of the motor. Please refer to Figure 2 Step S201 in, which will not be elaborated here.

[0050] Step S302, determine the motor fluctuation frequency at the current moment according to the associated data of the motor at the current moment and the associated data of the motor at the previous moment of the current moment.

[0051] Specifically, the above step S302 includes: In step S3021, determine the current change rate according to the current of the motor at the current moment and the current of the motor at the previous moment of the current moment.

[0052] The current of the motor can indicate the output current of the motor at the current moment. The torque of the motor can indicate the driving force that causes the output shaft of the motor to rotate at the current moment. The vibration frequency of the motor can indicate the number of vibrations completed by the motor at the current moment.

[0053] In specific implementation, the current of the motor can be detected by an ammeter, or the current of the motor can be detected by a motor driver. There is no specific limitation here, and it can be implemented by those skilled in the art.

[0054] The torque of the motor can be detected by a static torque sensor, or the torque of the motor can be detected by a dynamic torque sensor. There is no specific limitation here, and it can be implemented by those skilled in the art.

[0055] The vibration frequency of the motor can be detected by a three-axis accelerometer built into the motor, or the vibration frequency of the motor can be detected by other devices with the function of detecting vibration frequency. There is no specific limitation here, and it can be implemented by those skilled in the art.

[0056] The current change rate can indicate the current change situation of the current from the previous moment to the current moment. Among them, the current change rate can be determined by the difference between the current at the current moment and the current of the motor at the previous moment of the current moment, and the time difference between the current moment and the previous moment of the current moment.

[0057] As an example, when the number of previous moments of the motor at the current moment is multiple, the average value of the current of the motor at the previous moments of the current moment can be determined first, and then the current change rate can be determined according to the difference between the average value of the current of the motor at the previous moments of the current moment and the current of the current moment, and the time difference between the current moment and the nearest previous moment of the current moment. For example: the current moment is t, the current at the current moment is A, the previous moments of the current moment include t - 1, t - 2, and t - 3, the current at the t - 1 moment is A1, the current at the t - 2 moment is A2, and the current at the t - 3 moment is A3. The average value of the current can be (A1 + A2 + A3) / 3. The current change rate can be (A - (A1 + A2 + A3)) / (the duration from the t - 1 moment to the t moment).

[0058] In step S3022, according to the torque of the motor at the current moment and the torque of the motor at the previous moment of the current moment, the torque change rate is determined.

[0059] The torque change rate can indicate the torque change situation from the previous moment to the current moment. Among them, the torque change rate can be determined by the difference between the torque at the current moment and the torque of the motor at the previous moment of the current moment, and the time difference between the current moment and the previous moment of the current moment.

[0060] 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 moments of the current moment can be determined first, and then the torque change rate can be determined according to the difference between the average value of the torque of the motor at the previous moments of the current moment and the torque at the current moment, and the time difference between the current moment and the nearest previous moment of the current moment.

[0061] In step S3023, according to the rotational speed of the motor at the current moment and the rotational speed of the motor at the previous moment of the current moment, the rotational speed change rate is determined.

[0062] The rotational speed change rate can indicate the rotational speed change situation from the previous moment to the current moment. Among them, the rotational speed change rate can be determined by the difference between the rotational speed at the current moment and the rotational speed of the motor at the previous moment of the current moment, and the time difference between the current moment and the previous moment of the current moment.

[0063] As an example, when the number of previous moments of the motor at the current moment is multiple, the average value of the rotational speed of the motor at the previous moments of the current moment can be determined first, and then the rotational speed change rate can be determined according to the difference between the average value of the rotational speed of the motor at the previous moments of the current moment and the rotational speed at the current moment, and the time difference between the current moment and the nearest previous moment of the current moment.

[0064] In step S3024, according to the vibration frequency of the motor at the current moment and the vibration frequency of the motor at the previous moment of the current moment, determine the vibration frequency change rate.

[0065] The vibration frequency change rate can indicate the change of the vibration frequency from the previous moment to the current moment. Among them, the vibration frequency change rate can be determined by the difference between the vibration frequency at the current moment and the vibration frequency of the motor at the previous moment of the current moment, and the time difference between the current moment and the previous moment of the current moment.

[0066] As an example, when the number of previous moments of the motor at the current moment is multiple, the average value of the vibration frequencies of the motor at the previous moments of the current moment can be determined first, and then, according to the difference between the average value of the vibration frequencies of the motor at the previous moments of the current moment and the vibration frequency at the current moment, and the time difference between the current moment and the nearest previous moment of the current moment, determine the vibration frequency change rate.

[0067] In step S3025, according to the current change rate, torque change rate, rotational speed change rate, and vibration frequency change rate, determine the motor fluctuation frequency at the current moment.

[0068] After determining the current change rate, torque change rate, rotational speed change rate, and vibration frequency change rate, the motor fluctuation frequency can be determined according to the current change rate, torque change rate, rotational speed change rate, and vibration frequency change rate.

[0069] As an example, the following formula can be used to determine the motor fluctuation frequency.

[0070] ; where, ΔI is the current change rate, ΔN is the torque change rate, Δr is the rotational speed change rate, ρ is the vibration frequency change rate, 、 、 、 are coefficients.

[0071] As an example, the motor fluctuation frequency can be determined by using a dynamic model. Among them, the current change rate, torque change rate, rotational speed change rate, and vibration frequency change rate can be used as the inputs of the dynamic model, and the motor fluctuation frequency can be used as the output of the dynamic model.

[0072] Step S303, according to the motor fluctuation frequency at the current moment and the pressure at the current moment, determine the slip coefficient at the current moment. Please refer to Figure 2 Step S203 in, and no more details will be given here.

[0073] Step S304, when the slip coefficient at the current moment is not less than the slip coefficient threshold, control the rotational speed of the motor according to the target rotational speed. Please refer toFigure 2 Step S204 in [reference] will not be elaborated here.

[0074] The method for controlling the motor speed provided in this embodiment takes into account the influence of current, torque, and vibration frequency on the motor's fluctuation frequency in addition to the motor speed. By determining the current change rate, torque change rate, speed change rate, and vibration frequency change rate, the motor's fluctuation frequency can be determined more accurately, thereby more accurately determining whether there is slippage between the bit connected to the motor and the screw.

[0075] In a possible implementation, controlling the motor speed according to the target speed in the above step S204 includes one of step S2041 and step S2042.

[0076] In step S2041, control the motor speed to the target speed.

[0077] In this embodiment, the target speed can be a fixed value. After determining the target speed, the motor speed can be controlled at the target speed and the motor speed can be controlled according to the target speed.

[0078] In step S2042, alternately control the motor speed to be one of the target maximum speed and the target minimum speed.

[0079] In this embodiment, the target speed can be a range value, and the range value of the target speed in the pulse mode can be determined. The range value can be a preset range value. For example: 200 - 500 RPM.

[0080] Among them, after determining the range value, the target maximum speed and the target minimum speed in the range value can be determined, and then the motor speed can be alternately controlled according to the target maximum speed and the target minimum speed.

[0081] When alternately controlling the motor speed to be one of the target maximum speed and the target minimum speed, the PID control algorithm can be used to alternately control the motor speed to be one of the target maximum speed and the target minimum speed. Among them, by comparing the deviation between the actual value and the currently required target maximum speed or target minimum speed, and according to the adjustment effects of the proportional, integral, and differential links, the actual value can accurately track the target value. Proportional link (P): Adjust according to the current deviation. The larger the deviation, the stronger the adjustment effect. Integral link (I): Adjust according to the accumulation of the deviation, used to eliminate the steady-state error of the system. Differential link (D): Adjust according to the change rate of the deviation, used to predict the future trend of the system, and improve the response speed and stability of the system.

[0082] The method for controlling the motor speed provided in this embodiment, on the one hand, can avoid slippage between the bit connected to the motor and the screw by controlling the motor speed with a stable target speed. On the other hand, by alternately controlling the motor speed to be one of the target maximum speed and the target minimum speed, the control accuracy of the motor speed can be improved, thereby avoiding slippage between the bit connected to the motor and the screw.

[0083] In a possible implementation manner, after the above step S204, the method further includes: Step S205, when the duration of controlling the motor speed according to the target speed reaches a preset duration and the pressure between the bit connected to the motor and the screw is greater than a pressure threshold, perform at least one increment operation until the target speed reaches a speed critical value; wherein, the increment operation includes: determining the intermediate speed targeted by the increment operation as the sum of the initial speed and the increment; wherein, the initial speed targeted by the first increment operation is the target speed; during the time period corresponding to the increment operation, control the motor speed to be the intermediate speed.

[0084] The preset duration can be a preset time period. Among them, the preset duration can be 2s or 3s, and can be set according to actual needs, and no specific limitation is made here. The pressure threshold can be a preset threshold. Among them, when the pressure between the bit connected to the motor and the screw is greater than the pressure threshold, it can indicate that the connection between the bit connected to the motor and the screw is stable.

[0085] As can be seen from the above, the process of the motor rotating to drive the bit connected to the motor to rotate, and the bit connected to the motor rotating to drive the screw to rotate so as to tighten the screw can be divided into three stages. These three stages can be divided into an initial stage, a critical stage, and a final stage. Among them, the initial stage can be the stage where the motor rotates rapidly, the critical stage can be the stage where the current slip coefficient is not less than the slip coefficient threshold, and the final stage can be the stage of tightening the screw.

[0086] When the duration of controlling the motor speed according to the target speed reaches the preset duration and the pressure between the bit connected to the motor and the screw is greater than the pressure threshold, it can enter the final stage to tighten the screw.

[0087] After determining to enter the final stage, the speed can be increased starting from the initial speed. Among them, the initial speed targeted by the first increment operation is the target speed, that is, starting from the target speed, the speed of the target speed is increased according to the speed increment.

[0088] The intermediate speed can be the speed after each increase by the increment. During each time period of increasing the speed, the motor speed can be controlled by the intermediate speed until the speed after increasing the speed reaches the speed critical value. Among them, the speed critical value can be a preset value. For example: the speed critical value can be 800 RPM.

[0089] For example, the increase amount can be 20, the initial rotational speed for the first increment operation can be 500 RPM, the rotational speed critical value can be 800 RPM. After the initial rotational speed is increased by 20, it can be 520 RPM. Among them, 520 RPM can be the intermediate rotational speed. Until the intermediate rotational speed reaches 800 RPM, the rotational speed of the motor is controlled according to the rotational speed critical value until the screw is tightened.

[0090] In a possible implementation manner, when controlling the rotational speed of the motor according to the rotational speed critical value, the current of the motor, the torque of the motor, and the vibration frequency of the motor can be continuously detected. And the fluctuation frequency of the motor is determined according to the rotational speed critical value, the current of the motor, the torque of the motor, and the vibration frequency of the motor. And the slip coefficient is determined according to the fluctuation frequency of the motor and the pressure between the bit connected to the motor and the screw. When the slip coefficient is not less than the slip coefficient threshold, the above steps S204 and S205 need to be repeatedly executed until the rotational speed of the motor is zero.

[0091] In a possible implementation manner, please refer to Table 1. Table 1 shows the trigger conditions and control strategies in the initial stage, the critical stage, and the final stage.

[0092] Table 1

[0093] For the method for controlling the rotational speed of the motor provided in this embodiment, when the pressure between the bit connected to the motor and the screw is greater than the pressure threshold, if the motor continues to operate at the original target rotational speed, it may cause insufficient torque of the motor and the screw cannot be effectively tightened. By performing the increment operation and gradually increasing the rotational speed of the motor, the motor can better adapt to high-load working conditions and ensure that the screw can be tightened smoothly.

[0094] Moreover, the increment operation can enable the motor to gradually increase the output power during the tightening process, avoiding damage to the screw or the workpiece due to suddenly applying excessive torque. At the same time, by gradually increasing the rotational speed of the motor, the screw can be tightened more evenly, reducing the situations of loosening or insufficient tightening, and improving the quality and reliability of the tightening.

[0095] In a possible implementation manner, the above method further includes: Step a1, obtaining the rotational speed value of the intermediate rotational speed.

[0096] Step a2, determining the increase amount for each increment operation according to the rotational speed value of the intermediate rotational speed and the preset increase amount mapping table; wherein, the increase amount for the current increment operation is greater than the increase amount for the next increment operation.

[0097] The preset increment mapping table can store the mapping relationship between the intermediate speed and the preset increment. For example, when the intermediate speed is 600 RPM, the preset increment can be 40; when the intermediate speed is 700 RPM, the preset increment can be 30, etc. After determining the speed value of the intermediate speed, the increment for the increment operation can be determined from the preset increment mapping table.

[0098] Step a3: When the sum of the intermediate speed and the increment for any increment operation is not greater than the speed threshold, determine the intermediate speed for the increment operation according to the increment for the increment operation.

[0099] Step a4: When the sum of the intermediate speed and the increment for any increment operation is greater than the speed threshold, increase the intermediate speed to the speed critical value.

[0100] When the sum of the intermediate speed and the increment for 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 increment for a certain time is not greater than the speed critical value, increase to the intermediate speed according to the increment.

[0101] 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 increment, so as to speed up the process of tightening the screw. At the same time, considering that the intermediate speed does not exceed the speed critical value, it can avoid slipping between the bit connected to the motor and the screw.

[0102] In a possible implementation manner, the above method further includes: Step S201: Determine the increment corresponding to the first increment operation and the increment corresponding to the non-first increment operation as the preset ratio.

[0103] When the increment is a fixed value, the preset ratio can be determined as the increment corresponding to the first increment operation and the increment corresponding to the non-first increment operation. Among them, the increment corresponding to the first increment operation and the increment corresponding to the non-first increment operation can be a ratio, such as 5%, etc. That is, on the basis of the intermediate speed corresponding to the current increment operation, increase the speed by 5% of the intermediate speed corresponding to the current increment operation to obtain the intermediate speed corresponding to the next increment operation.

[0104] For the method for controlling the motor speed provided in this embodiment, when the preset ratio is determined as the increment, regardless of the initial speed, the speed change brought by each increment operation is a fixed ratio relative to the current speed. By the proportional relationship between the increment amplitude of the speed and the current speed, it can better adapt to the speed settings under different working conditions.

[0105] In a possible implementation manner, the above method further includes: Step S202, determine the preset difference as the increment corresponding to the first increment operation and the increment corresponding to non-first increment operations.

[0106] 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 non-first increment operations. Among them, the increment corresponding to the first increment operation and the increment corresponding to non-first increment operations can be a fixed value. For example: 20, etc., that is, the difference between the intermediate speed corresponding to the next increment operation and the intermediate speed corresponding to the current increment operation can be 20.

[0107] The method for controlling the motor speed provided in this embodiment uses the preset difference as the increment, and each increment operation will increase the speed by a fixed value, which can achieve precise control of the speed change.

[0108] In a possible implementation manner, the above method further includes: Step S301, control the display device to give an early warning, and control the adjustment device to apply pressure to the bit connected to the motor.

[0109] When the duration of controlling the motor speed according to the target speed reaches the preset duration and the pressure between the bit connected to the motor and the screw is greater than the pressure threshold, before performing at least one increment operation 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 between the bit connected to the motor and the screw is insufficient, then an early warning can be given through the display device.

[0110] As an example, the display device can be an LED light, and an early warning can be given by the flashing of the LED light.

[0111] As an example, the display device can display warning text to give an early warning through the warning text.

[0112] After controlling the display device to give an early warning, the adjustment device can be controlled to apply pressure to the bit connected to the motor. Among them, the adjustment device can be a device for controlling the bit connected to the motor (such as a robotic arm, etc.). Among them, the adjustment device can apply pressure to the bit connected to the motor to make the connection between the bit connected to the motor and the screw stable.

[0113] In a possible implementation manner, during the processing of the initial stage, the critical stage, and the final stage, the current of the motor, the torque of the motor, the vibration frequency of the motor, the pressure between the bit connected to the motor and the screw, and the slip coefficient can be recorded and stored in real time to provide support for subsequent optimization and improvement of the processing of the initial stage, the critical stage, and the final stage.

[0114] The method for controlling the motor speed provided in this embodiment is as follows: when the slip coefficient is less than the slip coefficient threshold, the connection between the bit connected to the motor and the screw is unstable. By applying pressure to the bit connected to the motor, the pressure between the bit connected to the motor and the screw can be increased to avoid slipping between the bit connected to the motor and the screw. Moreover, controlling the display device to give an early warning can effectively prompt the technician, enabling the technician to timely understand the possible slipping situation between the bit connected to the motor and the screw.

[0115] In this embodiment, a device for controlling the motor speed is also provided. This device is used to implement the above-mentioned embodiment and preferred implementation manners, and those that have been described will not be repeated. As used hereinafter, the term "module" can be a combination of software and / or hardware that can achieve a predetermined function. Although the device described in the following embodiments is preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0116] This embodiment provides a device for controlling the motor speed. The device includes: an acquisition module, configured to acquire the pressure at the current moment and the associated data of the motor at the current moment; wherein, the pressure is the pressure between the bit connected to the motor and the screw, and the associated data includes the speed of the motor; a first determination module, configured to determine the motor fluctuation frequency at the current moment according to the associated data of the motor at the current moment and the associated data of the motor at the previous moment of the current moment; a second determination module, configured to determine the slip coefficient at the current moment according to the motor fluctuation frequency at the current moment and the pressure at the current moment; a control module, configured to control 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.

[0117] In a possible implementation manner, the associated data further includes: current, torque, and vibration frequency; and the above-mentioned first determination module includes: a first determination unit, configured to determine the current change rate according to the current of the motor at the current moment and the current of the motor at the previous moment of the current moment; a second determination unit, configured to determine the torque change rate according to the torque of the motor at the current moment and the torque of the motor at the previous moment of the current moment; a third determination unit, configured to determine the speed change rate according to the speed of the motor at the current moment and the speed of the motor at the previous moment of the current moment; a fourth determination unit, configured to determine the vibration frequency change rate according to the vibration frequency of the motor at the current moment and the vibration frequency of the motor at the previous moment of the current moment; a fifth determination unit, configured to determine the motor fluctuation frequency at the current moment according to the current change rate, torque change rate, speed change rate, and vibration frequency change rate.

[0118] In a possible implementation manner, the above-mentioned control module includes: a first control unit, configured to control the speed of the motor to be the target speed.

[0119] In a possible implementation, the above 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.

[0120] In a possible implementation, the above device further includes: a repeating execution module configured to, when the duration of controlling the rotational speed of the motor according to the target rotational speed reaches a preset duration and the pressure between the bit connected to the motor and the screw is greater than a pressure threshold, perform at least one increment operation until the target rotational speed reaches a rotational speed critical value; wherein, the increment operation includes: determining the sum of the initial rotational speed and an increment as the intermediate rotational speed targeted by the increment operation; wherein, the initial rotational speed targeted by the first increment operation is the target rotational speed; during the time period corresponding to the increment operation, control the rotational speed of the motor to be the intermediate rotational speed.

[0121] In a possible implementation, the above device further includes: a third determination module configured to determine a preset ratio as the increment corresponding to the first increment operation and the increment corresponding to non-first increment operations.

[0122] In a possible implementation, the above device further includes: a fourth determination module configured to determine a preset difference as the increment corresponding to the first increment operation and the increment corresponding to non-first increment operations.

[0123] In a possible implementation, the above device further includes: a warning control module configured to control a display device to give a warning, and control an adjustment device to apply pressure to the bit connected to the motor.

[0124] In a possible implementation, the above device further includes: a fifth determination module configured to, according to the type of the screw, determine the motor control parameters corresponding to the type of the screw from a preset database; wherein, the motor control parameters include: a rotational speed threshold and the rotational speed at an initial moment, wherein the rotational speed threshold is greater than the target rotational speed, and the initial moment is before the current moment; an initial control module configured to control the motor according to the rotational speed at the initial moment.

[0125] The further function descriptions of the above respective modules and units are the same as those in the corresponding above embodiments, and will not be elaborated herein.

[0126] The device for controlling the rotational speed of the motor in this embodiment is presented in the form of functional units. Here, the functional units refer to ASIC (Application Specific Integrated Circuit) circuits, processors and memories that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0127] The embodiment of the present invention further provides a computer device having the above device for controlling the rotational speed of the motor.

[0128] Please refer to Figure 4 , Figure 4 which is a schematic structural diagram of a computer device provided by an alternative embodiment of the present invention. As shown in Figure 4 , the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Each component communicates with each other using different buses and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed within the computer device, including instructions stored in the memory or on the memory to display graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some alternative embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a set of blade servers, or a multi-processor system). Figure 4 In

[0129] Figure 4 , a single processor 10 is taken as an example.

[0130] The processor 10 can be a central processing unit, a network processor, or a combination thereof. Among them, the processor 10 can further include a hardware chip. The above hardware chip can be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The above programmable logic device can be a complex programmable logic device, a field programmable gate array, a general array logic, or any combination thereof.

[0131] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiments.

[0132] The memory 20 can include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the computer device, etc. In addition, the memory 20 can include high-speed random access memory and can also include non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some alternative embodiments, the memory 20 can optionally include a memory remotely set relative to the processor 10, and these remote memories can be connected to the computer device through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0132] The memory 20 can include volatile memory, such as random access memory; the memory can also include non-volatile memory, such as flash memory, a hard disk, or a solid-state drive; the memory 20 can also include a combination of the above types of memory.

[0133] 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 through a bus or other means. Figure 4 For example, taking the connection through the bus as an example.

[0134] The input device 30 can receive input digital or character information, and generate key signal inputs related to the user settings and function controls of the computer device, such as a touch screen, a keypad, a mouse, a trackpad, a touchpad, a pointing stick, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED), and a tactile feedback device (e.g., a vibration motor), etc. The above display device includes but is not limited to a liquid crystal display, a light-emitting diode, a display, and a plasma display. In some alternative embodiments, the display device may be a touch screen.

[0135] The computer device further includes a communication interface for the computer device to communicate with other devices or communication networks.

[0136] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-transitory 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 may be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium may also include a combination of the above types of memories. 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 the computer, the processor, or the hardware, the method shown in the above embodiment is implemented.

[0137] A part of the present invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can call or provide the methods and / or technical solutions according to the present invention through the operations of the computer. Those skilled in the art should understand that the forms of existence of computer program instructions in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executes the instructions, or the computer compiles the instructions and then executes the corresponding compiled program, or the computer reads and executes the instructions, or the computer reads and installs the instructions and then executes the corresponding installed program. Herein, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible by the computer.

[0138] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for controlling the rotational speed of a motor, characterized in that, The method includes: Collecting the pressure at the current moment and the associated data of the motor at the current moment; wherein, the pressure is the pressure between the bit connected to the motor and the screw, and the associated data includes the rotation speed of the motor. Determining the motor fluctuation frequency at the current moment according to the associated data of the motor at the current moment and the associated data of the motor at the previous moment of the current moment. Determining the slip coefficient at the current moment according to 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 rotation speed of the motor according to the target rotation speed.

2. The method for controlling the rotational speed of an electric motor 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 according to the associated data of the motor at the current moment and the associated data of the motor at the previous moment of the current moment includes: Determining the current change rate according to the current of the motor at the current moment and the current of the motor at the previous moment of the current moment. Determining the torque change rate according to the torque of the motor at the current moment and the torque of the motor at the previous moment of the current moment. Determining the rotation speed change rate according to the rotation speed of the motor at the current moment and the rotation speed of the motor at the previous moment of the current moment. Determining the vibration frequency change rate according to the vibration frequency of the motor at the current moment and the vibration frequency of the motor at the previous moment of the current moment. Determining the motor fluctuation frequency at the current moment according to the current change rate, torque change rate, rotation speed change rate, and vibration frequency change rate.

3. The method for controlling the rotational speed of an electric motor according to claim 1, characterized in that, Controlling the rotation speed of the motor according to the target rotation speed includes: Controlling the rotation speed of the motor to be the target rotation speed; or, Alternately controlling the rotation speed of the motor to be one of the target maximum rotation speed and the target minimum rotation speed.

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

5. The method for controlling the rotational speed of an electric motor according to claim 4, characterized in that, The method further includes: Determining the increment corresponding to the first increment operation and the increment corresponding to the non-first increment operation as the preset ratio; or, Determining the increment corresponding to the first increment operation and the increment corresponding to the non-first increment operation as the preset difference.

6. The method for controlling the rotational speed of an electric motor according to claim 4, characterized in that, Before performing at least one increment operation until the target rotation speed reaches the rotation speed critical value when the duration of controlling the rotation speed of the motor according to the target rotation speed reaches the preset duration and the pressure between the bit connected to the motor and the screw is greater than the pressure threshold, the method further includes: Controlling the display device to give an alarm, and controlling the adjusting device to apply pressure to the bit connected to the motor.

7. The method for controlling the rotational speed of an electric motor according to any one of claims 1-6, 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: Determine the motor control parameters corresponding to the type of the screw from a preset database according to the type of the screw; wherein, the motor control parameters include: a rotational speed threshold and a rotational speed at an initial moment, where the rotational speed threshold is greater than the target rotational speed, and the initial moment is before the current moment; Control the motor according to the rotational speed at the initial moment.

8. A device for controlling the rotational speed of a motor, characterized in that, The device includes: An acquisition module, configured to acquire the pressure at the current moment and the associated data of the motor at the current moment; wherein, the pressure is the pressure between the bit connected to the motor and the screw, and the associated data includes the rotational speed of the motor; A first determination module, configured to determine the motor fluctuation frequency at the current moment according to the associated data of the motor at the current moment and the associated data of the motor at the previous moment of the current moment; A second determination module, configured to determine the slip coefficient at the current moment according to the motor fluctuation frequency at the current moment and the pressure at the current moment; A control module, configured to control 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.

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

10. A computer-readable storage medium, characterized in that, Computer instructions are stored on the computer-readable storage medium, and the computer instructions are used to cause the computer to execute the method for controlling the rotational speed of the motor according to any one of claims 1 to 7.

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