Stepping motor control method and system

Abstract

The invention relates to the technical field of stepping motor control, and particularly discloses a stepping motor control method and system. In the system, 12v voltage output by a voltage-stabilized power supply module is in power supply connection with a stepping motor driving module; the temperature sensor and the limit switch module are in bidirectional signal transmission connection with the ARM control module; the stepping motor driving module is in signal connection with the ARM control module so that the rotating torque and the holding torque of the stepping motor can be adjusted according to data transmitted to the ARM control module by the temperature sensor. According to the technical scheme, the rotating torque and the holding torque of the stepping motor can be adaptively adjusted according to the external environment temperature. According to the system, the switching mirror base can stably and smoothly run to a corresponding position under the conditions of different high and low temperatures, and can be firmly locked to an original position under the condition of high vibration magnitude after reaching the corresponding position.

Description

Technical Field

[0001] The present invention relates to the technical field of stepper motor control, and in particular to a stepper motor control method and system. Background Art

[0002] In stepper motor control equipment, torque and holding torque are two important indicators to measure the performance of stepper motors. Appropriate torque can ensure the smoothness and stability of the equipment during movement; appropriate holding torque can ensure that the equipment can be stably parked at the corresponding position under the corresponding vibration level. Under different temperature conditions, the friction resistance between the motor and the guide rail will change due to thermal expansion and contraction. At low temperatures, the friction resistance is large. During the movement, a large torque is required so that the motor can move stably and smoothly to the corresponding position within a specified time period; in the holding state, with the help of large friction resistance, it does not require excessive holding torque to stay firmly in the corresponding position. At the same time, because most of the energy of the holding torque is converted into heat energy that is harmful to the system, the system needs to set a smaller holding torque at this time. In the high temperature process, contrary to the low temperature, the system requires a small torque and a large holding torque.

[0003] The torque and holding torque of traditional stepper motor control solutions are generally constant or modified by manual input. They have poor environmental adaptability and imperfect performance control. Specifically: 1. The torque is a constant value. At low temperatures, the friction resistance between the motor and the guide rail increases due to the thermal expansion and contraction of the mechanical structure. In order to balance the torque setting under high and low temperature conditions, the torque is generally set to the maximum value. When this setting is at high temperature, the motor runs too fast. When the original braking distance is not enough, it may cause the mechanical moving part to rush through the electrical limit and hit the mechanical limit. This condition damages the mechanical structure.

[0004] 2. The setting of holding torque. Traditional solutions are limited by the performance of the stepper motor control chip. When the stepper motor enable pin is turned off in the holding state, the holding torque output by the stepper motor is too small. Under the condition of relatively large vibration level, the holding torque at this time does not meet the requirements and may push the mechanical structure controlled by the motor away from the original position, which is contrary to the holding state and cannot meet the vibration level requirements. Without turning off the enable pin, the holding torque is equal to the rotation torque. In the holding state, this will bring the following problems: Waste of resources. At this time, the energy consumption for maintenance is equal to the energy consumption for rotation. The energy is converted into heat that is not needed by the system, and the energy conversion efficiency is close to 0. When the motor is not rotating, the motor coil is in a high-voltage heating state for a long time, which is a damage to the stepper motor and affects its performance and service life; The generated heat radiates to the entire system, which also has an uncertain impact on the stability of the entire system.

[0005] Based on this, those skilled in the art urgently need to provide a new technical solution to solve the technical problems existing in the above-mentioned existing stepper motor control. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects existing in the above-mentioned prior art, thereby providing a stepper motor control method and system.

[0007] A stepper motor control system, comprising: a voltage-stabilized power supply module, a host computer, a power supply control module, a stepper motor drive module, an ARM control module, a temperature sensor, a limit switch module, a stepper motor, and a structural component driven by the stepper motor; The 12V voltage output by the voltage-stabilized power supply module is connected to the temperature sensor, the limit switch module, the ARM control module and the stepper motor drive module through the power control module; the 12V voltage output by the voltage-stabilized power supply module is connected to the stepper motor drive module; The temperature sensor and limit switch module are both connected to the ARM control module for bidirectional signal transmission; The stepper motor drive module is connected to the ARM control module by signal, so that the rotation torque and holding torque of the stepper motor are adjusted according to the data transmitted to the ARM control module by the temperature sensor; The host computer is communicatively connected with the ARM control module; The structural component driven by the stepper motor is connected to the stepper motor.

[0008] Preferably, the 12V voltage output by the voltage-stabilizing power supply module is stepped down twice by the power supply control module, and the output voltages are 5V and 3.3V respectively. Specifically: The power control module includes: a voltage conversion unit and a low voltage drop linear voltage regulator unit; The 12V voltage output by the voltage stabilizing power supply module is reduced by the voltage conversion unit for the first time to output a 5V voltage, which is connected to the limit switch module; The low voltage difference linear voltage regulator unit performs a second step-down process on the 5V voltage output by the voltage conversion unit to output a 3.3V voltage, and is connected to the ARM control module, the temperature sensor and the stepper motor drive module.

[0009] Preferably, the DAC output of the ARM control module is used as the reference level of the stepper motor drive module.

[0010] Preferably, based on the maximum value of the DAC output voltage of 3.3v exceeding the reference working level range of the stepper motor drive module, the stepper motor control system further includes: a protection module to make the input voltage of the stepper motor drive module less than 2.87v and the internal reference voltage less than 3v; The protection module is composed of a resistor R27 and a resistor R28 connected in series; One end of the resistor R27 is connected to the DAC output end of the ARM control module, and the other end is connected to one end of the resistor R28; The connection ends of resistor R27 and resistor R28 are connected to the stepper motor drive module; The other end of the resistor R28 is grounded.

[0011] Preferably, the structural component driven by the stepper motor is specifically a switching mirror base.

[0012] A stepper motor control method is implemented by using a stepper motor control system; the stepper motor control method comprises the following steps: Step 1, operate the host computer to send a command for the switching mirror base to move to the left limit; Step 2, the ARM control module receives and parses the command information of the host computer; Step 3, after the ARM control module obtains the instruction to switch the mirror base to move left, it executes steps 3-1 to 3-6: Step 3-1, the ARM control module controls the temperature sensor to collect ambient temperature information in real time, and completes the analysis in real time in the ARM control module; Step 3-2, selecting different DAC outputs according to the converted temperature information, thereby controlling the output of different rotation torques; Step 3-3, turn on the corresponding enable signal and set the signal level to 0; Step 3-4, set the DIR direction signal to 1, indicating that the switching mirror base will move left; Step 3-5, the pulse control signal STEP is set to the PWM signal output by the timer, with a period of 1ms, a frequency of 1Khz, and a duty cycle of 50%. The timer is turned on and the stepper motor starts to rotate; Step 3-6, reporting to the upper computer that the mirror base starts to move left; Step 4: During the rotation of the stepper motor, the ARM control module determines in real time whether the left limit signal is 0; if so, execute step 5; if not, keep moving and repeat step 4 until the judgment result is yes; Step 5: When the left limit signal is detected to be zero, it indicates that at this moment, the switching mirror base has moved to the left limit position, and at this moment, the stepper motor control torque is converted from a rotation torque state to a holding torque state; Step 6: When the movement stops, feedback is given to the upper computer that the switching mirror base has moved to the left limit.

[0013] Preferably, when the left limit signal is detected to be zero, it indicates that at this moment, the switching mirror base has moved to the left limit position, and at this moment, the stepper motor control torque is converted from a rotation torque state to a holding torque state, specifically: Step 5-1, according to the temperature information converted in real time, different DAC outputs are selected to control the holding torque corresponding to the output; Step 5.2, turn off the timer output, set the STEP signal to 0, and stop the stepper motor from rotating. At this time, the stepper motor has reached the left limit position and uses the holding torque to stably stop at the corresponding position.

[0014] The technical solution of the present invention has the following advantages: The technical solution of the present invention can adaptively adjust the rotation torque and holding torque of the stepper motor according to the external ambient temperature. This system enables the switching mirror base to stably and smoothly run to the corresponding position under different high and low temperature conditions, and after reaching the corresponding position, it can be firmly locked in the original position under high vibration level conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is the overall block diagram of the stepper motor control system; Figure 2 This is the functional module block diagram of the stepper motor driver chip HR4988; Figure 3 It is the DAC output level limiting circuit; Figure 4 It is a flow chart of the stepper motor control method. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Example 1 The rotation torque and holding torque based on the traditional stepper motor control scheme are generally constant values ​​or manually input and modified, and the environmental adaptability is poor and the performance control is imperfect. Therefore, this embodiment discloses a stepper motor control system, including: a voltage-stabilized power supply module, a host computer, a power supply control module, a stepper motor drive module, an ARM control module, a temperature sensor, a limit switch module, a stepper motor, and a structural component driven by the stepper motor; The 12V voltage output by the voltage-stabilized power supply module is connected to the temperature sensor, the limit switch module, the ARM control module and the stepper motor drive module through the power control module; the 12V voltage output by the voltage-stabilized power supply module is connected to the stepper motor drive module; The temperature sensor and limit switch module are both connected to the ARM control module for bidirectional signal transmission; The stepper motor drive module is connected to the ARM control module by signal, so that the rotation torque and holding torque of the stepper motor are adjusted according to the data transmitted to the ARM control module by the temperature sensor; The host computer is connected to the ARM control module for communication; the host computer: provides control command input and status feedback display; The structural component driven by the stepper motor is connected to the stepper motor.

[0022] It should be noted that the traditional control system lacks a temperature environment detection mechanism. This system adds a temperature sensor to make real-time adjustments to provide more reliable protection under different high and low temperature conditions. When the friction is large at low temperatures, the rotational torque is increased and the holding torque is reduced; when the temperature is high, the rotational torque is reduced and the holding torque is appropriately increased to make the motor position more secure.

[0023] In this embodiment, the voltage-stabilized power supply module is a DC voltage-stabilized power supply: 220V to 32V 6A, providing 12V voltage input for the entire system; the 12V voltage output by the voltage-stabilized power supply module is stepped down twice by the power control module, and the output voltages are 5V and 3.3V respectively. Specifically: The power control module includes: a voltage conversion unit DC-DC and a low voltage difference linear voltage regulator unit LDO; The 12V voltage output by the voltage stabilizing power supply module is reduced by the voltage conversion unit for the first time to output a 5V voltage, which is connected to the limit switch module; The low voltage difference linear voltage regulator unit performs a second step-down process on the 5V voltage output by the voltage conversion unit to output a 3.3V voltage, and is connected to the ARM control module, the temperature sensor and the stepper motor drive module.

[0024] In this embodiment, the ARM control module adopts an ARM-STM32 control chip, which has the following functions: 1. receiving and parsing host computer instructions, 2. reading temperature status information, 3. providing stepper motor drive module control logic, 4. reading limit switch module status information; In this embodiment, the stepper motor drive module uses the HR4988 stepper motor drive chip. The HR4988 stepper motor drive chip integrates a stepper motor driver and converts the control logic into the motor's A-phase and B-phase control inside the chip. The functional block diagram is shown in the figure. Figure 2As shown; 1. Functional module: VREF: reference voltage input, used to set the reference level of DAC output. STEP: step signal input, used to control the stepping action of the stepper motor. DIR: direction signal input, used to control the rotation direction of the stepper motor. nRESET: reset signal input, used to reset the chip state. nENABLE: enable control signal input, used to enable or disable the chip. nSLEEP: sleep mode control signal input, used to reduce power consumption. 2. Internal structure: DAC digital analog converter: converts digital signals into analog voltages to control the current of the motor. Proportional control: adjusts the motor current according to the feedback signals of Sense1 and Sense2 to achieve precise control. PWM control: pulse width modulation control, used to adjust the speed and torque of the motor. Control logic circuit: processes STEP and DIR signals to generate logic signals to control the stepper motor. Pre-driver: drives the DMOS full bridge to provide drive current for the stepper motor. 3. Output port: OUT1A / OUT1B: output port of phase A of the stepper motor. OUT2A / OUT2B: output port of phase B of the stepper motor. Sense1 / Sense2: Current detection port, used to monitor motor current.

[0025] like Figure 1 The input control signals mainly involved in this system control are: stepper motor controller enable control signal nENABLE, stepper motor rotation control direction signal DIR, stepper motor pulse control signal STEP, and reference level signal VREF. The nNABLE enable control signal and direction DIR signal are connected to the common IO pin of the ARM control module, the stepper control STEP signal needs to be connected to the timer pin of the ARM control module, and the reference level signal VREF is connected to the DAC output pin of the ARM; Output enable control signal nENABLE: It is low level effective; when the input is 1, the output signal of the entire stepper motor driver is invalid, when the input is 0, the output of the entire stepper motor driver is normal; Stepper motor pulse control signal STEP: This control end is effective for rising edge triggering. Each rising edge controls the stepper motor driver to drive the stepper motor to move one step; Stepper motor rotation direction control signal DIR: The movement direction of the stepper motor is controlled by changing the high and low levels of the input signal DIR.

[0026] Reference level VREF of stepper motor driver chip: The reference working level range is 0.8V~3V: In this design, the DAC output of the ARM control module is used as the reference level of the stepper motor driver module. Specifically: the traditional fixed level is modified to the DAC output of the ARM control module. Because the DAC output is an analog quantity, the voltage value is any value in the range of 0~3.3V to achieve adjustable output capacity. The maximum value of the DAC output is 3.3V, which exceeds the reference working level range, so the following is made in the circuit: Figure 3 Protection, specifically a protection module, a part of the stepper motor control system, the protection module is a DAC output level limiting circuit composed of a series resistor R27 and a resistor R28; like Figure 3 One end of the resistor R27 is connected to the DAC output end of the ARM control module, and the other end is connected to one end of the resistor R28; The connection end of resistor R27 and resistor R28 is connected to the REF pin of the stepper motor drive module; The other end of the resistor R28 is grounded.

[0027] VREF=DAC output voltage*R28 / (R27+R28), the maximum input voltage range is controlled to be less than 2.87V, ensuring that the internal reference voltage will not be over-voltage and less than 3V. The rotation torque and holding torque of the motor are positively correlated with the reference level. The larger the reference level, the larger the rotation torque and holding torque of the motor. In this embodiment, the parameter of resistor R27 is 3 kilo ohms ±5%. The parameter of resistor R28 is 20 kilo ohms ±5%.

[0028] In addition, in the present embodiment, the stepper motor is a hybrid linear stepper motor. In addition, in the present embodiment, the structural component driven by the stepper motor is specifically a switching mirror base.

[0029] Temperature sensor: DS18B20, the temperature sensor is used to read the ambient temperature around the stepper motor, and then transmit the temperature information to the ARM-STM32 control chip. The temperature measurement range is -55℃~+125℃, the temperature conversion time is less than 750ms, and the temperature information is read using a single bus interface. The power supply range of the chip is 2.5V~5.5V, so the temperature measurement performance of this chip fully meets the design of this system: the ambient temperature of the stepper motor is collected, and the ARM control module adjusts the corresponding DAC output according to the corresponding temperature information, thereby controlling the rotation torque and holding torque under different ambient temperature conditions.

[0030] The limit switch module uses Hall elements, specifically the YS1138 unipolar Hall effect sensor, with an operating voltage of 3.8V~40V, a standard Gauss value of 250Gauss at the operating point, a standard Gauss value of 200Gauss at the release point, a hysteresis of 50Gauss, and an operating temperature of ~40℃~150℃. It is a motion module detection unit, fixedly installed at the two limit positions of the switching mirror base to determine whether the switching mirror base has moved in place.

[0031] Example 2 A stepper motor control method is implemented by using a stepper motor control system; the stepper motor control method comprises the following steps: Step 1, operate the host computer to send a command for the switching mirror base to move to the left limit; Step 2, the ARM control module receives and parses the command information of the host computer; Step 3, after the ARM control module obtains the instruction to switch the mirror base to move left, it executes steps 3-1 to 3-6: Step 4: During the rotation of the stepper motor, the ARM control module determines in real time whether the left limit signal is 0; if so, execute step 5; if not, keep moving and repeat step 4 until the judgment result is yes; Step 5: When the left limit signal is detected to be zero, it indicates that at this moment, the switching mirror base has moved to the left limit position, and at this moment, the stepper motor control torque is converted from a rotation torque state to a holding torque state; Step 6: When the movement stops, feedback is given to the upper computer that the switching mirror base has moved to the left limit.

[0032] like Figure 4 Step 3 specifically includes: Step 3-1, the ARM control module controls the temperature sensor to collect ambient temperature information in real time, and completes the analysis in real time in the ARM control module; Step 3-2, selecting different DAC outputs according to the converted temperature information, thereby controlling the output of different rotation torques; Step 3-3, turn on the corresponding enable signal and set the signal level to 0; Step 3-4, set the DIR direction signal to 1, indicating that the switching mirror base will move left; Step 3-5, the pulse control signal STEP is set to the PWM signal output by the timer, with a period of 1ms, a frequency of 1Khz, and a duty cycle of 50%. The timer is turned on and the stepper motor starts to rotate; Step 3-6, reporting to the upper computer that the mirror base starts to move left; For step 5, when the left limit signal is detected to be zero, it indicates that at this moment, the switching mirror base has moved to the left limit position. At this time, the stepper motor control torque is converted from the rotation torque state to the holding torque state, specifically: Step 5-1, according to the temperature information converted in real time, different DAC outputs are selected to control the holding torque corresponding to the output; Step 5.2, turn off the timer output, set the STEP signal to 0, and stop the stepper motor from rotating. At this time, the stepper motor has reached the left limit position and uses the holding torque to stably stop at the corresponding position.

[0033] It should be noted that through steps 1 to 6, the stepper motor control system moves the switching mirror base to the left limit position according to the host computer command, and has the corresponding holding torque at the left limit position. At the same time, the operation process of the switching mirror base moving to the right is similar. It only needs to modify the moving direction DIR signal and detect the right limit signal in real time during the start of the movement. Under different temperatures, the temperature information fed back by the temperature sensor is used to adjust the corresponding DAC output in real time, thereby controlling different rotational torques and holding torques.

[0034] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A stepper motor control system, characterized in that: include: Voltage-stabilized power supply module, host computer, power control module, stepper motor drive module, ARM control module, temperature sensor, limit switch module, stepper motor and structural components driven by the stepper motor; The 12V voltage output by the voltage-stabilized power supply module is connected to the temperature sensor, the limit switch module, the ARM control module and the stepper motor drive module through the power control module; the 12V voltage output by the voltage-stabilized power supply module is connected to the stepper motor drive module; The temperature sensor and limit switch module are both connected to the ARM control module for bidirectional signal transmission; The stepper motor drive module is connected to the ARM control module by signal, so that the rotation torque and holding torque of the stepper motor are adjusted according to the data transmitted to the ARM control module by the temperature sensor; The host computer is communicatively connected with the ARM control module; The structural component driven by the stepper motor is connected to the stepper motor.

2. The stepper motor control system according to claim 1, characterized in that: The 12V voltage output by the voltage-stabilized power supply module is stepped down twice by the power control module, and the output voltages are 5V and 3.3V respectively. Specifically: The power control module includes: a voltage conversion unit and a low voltage drop linear voltage regulator unit; The 12V voltage output by the voltage stabilizing power supply module is reduced by the voltage conversion unit for the first time to output a 5V voltage, which is connected to the limit switch module; The low voltage difference linear voltage regulator unit performs a second step-down process on the 5V voltage output by the voltage conversion unit to output a 3.3V voltage, and is connected to the ARM control module, the temperature sensor and the stepper motor drive module.

3. The stepper motor control system according to claim 2, characterized in that: The DAC output of the ARM control module is used as the reference level of the stepper motor drive module.

4. The stepper motor control system according to claim 3, characterized in that: Since the maximum value of the DAC output voltage is 3.3v, which exceeds the reference working level range of the stepper motor drive module, the stepper motor control system also includes: a protection module to make the input voltage of the stepper motor drive module less than 2.87v and the internal reference voltage less than 3v; The protection module is composed of a resistor R27 and a resistor R28 connected in series; One end of the resistor R27 is connected to the DAC output end of the ARM control module, and the other end is connected to one end of the resistor R28; The connection ends of resistor R27 and resistor R28 are connected to the stepper motor drive module; The other end of the resistor R28 is grounded.

5. The stepper motor control system according to claim 4, characterized in that: The structural component driven by the stepper motor is specifically a switching mirror base.

6. A stepper motor control method, characterized in that: The stepper motor control system described in claim 5 is used to implement the stepper motor control method, which comprises the following steps: Step 1, operate the host computer to send a command for the switching mirror base to move to the left limit; Step 2, the ARM control module receives and parses the command information of the host computer; Step 3, after the ARM control module obtains the instruction to switch the mirror base to move left, it executes steps 3-1 to 3-6: Step 3-1, the ARM control module controls the temperature sensor to collect ambient temperature information in real time, and completes the analysis in real time in the ARM control module; Step 3-2, selecting different DAC outputs according to the converted temperature information, thereby controlling the output of different rotation torques; Step 3-3, turn on the corresponding enable signal and set the signal level to 0; Step 3-4, set the DIR direction signal to 1, indicating that the switching mirror base will move left; Step 3-5, the pulse control signal STEP is set to the PWM signal output by the timer, with a period of 1ms, a frequency of 1Khz, and a duty cycle of 50%. The timer is turned on and the stepper motor starts to rotate; Step 3-6, reporting to the upper computer that the mirror base starts to move left; Step 4: During the rotation of the stepper motor, the ARM control module determines in real time whether the left limit signal is 0; if so, execute step 5; if not, keep moving and repeat step 4 until the judgment result is yes; Step 5: When the left limit signal is detected to be zero, it indicates that at this moment, the switching mirror base has moved to the left limit position, and at this moment, the stepper motor control torque is converted from a rotation torque state to a holding torque state; Step 6: When the movement stops, feedback is given to the upper computer that the switching mirror base has moved to the left limit.

7. The stepper motor control method according to claim 6, characterized in that: When the left limit signal is detected to be zero, it indicates that at this moment, the switching mirror base has moved to the left limit position. At this time, the stepper motor control torque is converted from the rotation torque state to the holding torque state, specifically: Step 5-1, according to the temperature information converted in real time, different DAC outputs are selected to control the holding torque corresponding to the output; Step 5.2, turn off the timer output, set the STEP signal to 0, and stop the stepper motor from rotating. At this time, the stepper motor has reached the left limit position and uses the holding torque to stably stop at the corresponding position.

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