KR20140141937A

KR20140141937A - Method of controlling servo motor using one-chip microcomputer

Info

Publication number: KR20140141937A
Application number: KR1020130063315A
Authority: KR
Inventors: 임성주; 김유찬; 이미숙
Original assignee: 이미숙
Priority date: 2013-06-03
Filing date: 2013-06-03
Publication date: 2014-12-11

Abstract

The present invention relates to a control method of a servo motor, in which a microcomputer receives a signal regarding a rotational speed and a position using an encoder coupled to a servo motor, and a control unit in the microcomputer controls the overload, A control method of a servo motor using a one-chip microcomputer capable of selectively controlling an overload, a rotation speed and a position of the servomotor according to a control program input to the control unit, It is possible to selectively control any one or more of them so that the main operation and function of the servo motor can be selected.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control method of a servo motor using a one-chip microcomputer,

The present invention relates to a control method of a servo motor, in which a microcomputer receives a signal regarding a rotational speed and a position using an encoder coupled to a servo motor, and a control unit in the microcomputer controls the overload, And controlling the overload, rotation speed, and position of the servo motor using a one-chip microcomputer.

In general, a servo mechanism is a feedback control system configured to follow an arbitrary change of a target value such as an automatic control system, that is, an object's position, orientation, posture, etc., so that the control amount is in a mechanical position. The servomotors used in this system are called servomotors. They are DC motors and AC motors.

These servomotors are capable of static electricity, reversing, smooth operation at a low speed, and can be rapidly accelerated and decelerated, and are used in various fields. In particular, they are used for robot welding or automatic welding.

The servomotor used for such automatic welding is usually a mechanical driving device, that is, an encoder is attached to a servomotor in which a speed reducer is formed, and a signal generated by the encoder is received by a control unit, And then transmitted to the motor drive circuit for use in controlling the servo motor.

At this time, a circuit for converting a signal or receiving and comparing an encoder signal is separately constructed and mechanically performed. Therefore, the configuration of the circuit is absolutely required, and the speed does not follow or the overload There is a concern.

As a related art related to control of a conventional servo motor, there is a servo motor system for precision torque control disclosed in Japanese Patent Registration No. 10-1188419.

The above-mentioned patent discloses a servo motor system for controlling the drive of a servo motor. The servo motor receives a first electrical signal corresponding to a load in accordance with the movement of the servo motor from a load cell mounted on the servo motor, and detects a torque of the servo motor A torque detector; A sequence controller for sequentially generating a target position command according to the torque; And a torque control position compensator for receiving a second electrical signal corresponding to a rotational position of the servomotor from an encoder mounted on the servomotor and detecting a position of the servomotor and generating a feedback position signal, A sequential position command generator for storing a target position command corresponding to each torque in storage means and generating a target position command in accordance with the torque from the torque detector; And a target torque notification generation section for generating an on / off control signal by comparing the torque from the torque detection section with a predetermined target torque, wherein the torque control position compensation section generates the on / And the position of the servo motor is controlled by outputting the feedback position signal.

The control method of the servo motor shown in the above patent is a control method of a servo motor for controlling the driving of the servo motor. The servo motor control method includes the steps of: Detecting a torque of the servomotor by receiving a first electrical signal corresponding to the load; Sequentially generating a target position command according to the torque; And receiving a second electrical signal corresponding to a rotational position of the servo motor from an encoder mounted on the servo motor to detect a position of the servo motor and generating a feedback position signal, Off control signal to control the position of the servo motor by outputting the current or previous feedback position signal according to the on / off control signal, And outputs the selected position signal as the feedback position signal, and outputs the selected position signal as the feedback position signal, Compares the command and the feedback position signal and outputs the command in accordance with a command corresponding to the position difference. And the position of the beam motor is controlled.

In the servo motor system and control method proposed in the above patent, the load is measured by the load cell by moving the position of the servo motor according to the load value applied to the servo motor, so that the present position of the servo motor can be detected There is no position sensing means of the sensor.

Therefore, it is impossible to trace the weld line when it is used for welding which does not cause load change.

As another conventional technique, there is a servo motor controlled by digital frame data and a pseudo-second signal, which are disclosed in Japanese Patent No. 10-0965230.

In this patent, digital frame data including ID information and displacement information, which are connected by a serial communication method to a control device and composed of byte strings transmitted from the control device, and PWM A servo motor controlled by digital data and digital signal controlled by data, comprising: a signal input port to which the digital frame data and the PWM data are input; A PWM signal processor for converting the PWM data into a PWM signal for driving the servo motor; A digital communication data processing unit for converting the displacement information of the digital frame data into a PWM signal for driving a servo motor; If the input signal input to the input port is digital frame data, ID of the input digital frame data is compared with the ID assigned to the input port, and if the input signal is identical to the input ID, the displacement information of the input digital frame data is input to the digital communication data processing unit A signal discrimination unit for inputting PWM data, which is input when the input signal is PWM data, to the PWM signal processing unit; A PWM generator for generating a PWM drive pulse by the PWM signal processing unit and the servo motor drive PWM signal inputted from the digital communication processing unit; And a motor driving unit for driving the servomotor by a PWM driving pulse generated by the PWM generator. A servo motor controlled by the digital frame data and the pMM signal has been proposed. The servo motors can be used to maintain the servo motors in a predetermined position. However, since a plurality of servo motors can be driven so as to reduce an error when an error occurs, compared with the absolute position initially input by an input signal, If not, it is not possible to use it.

Therefore, the servo motor proposed in the above patent also can not be used as a servo motor used for welding because it is impossible to trace a weld line, overload limitation, speed control, and the like.

Accordingly, the present invention provides a control method of a servo motor capable of controlling a servo motor, wherein the servo motor is driven by a motor drive circuit, the motor drive circuit exchanges signals with a microcomputer, A control method of a servo motor using a one-chip microcomputer including a control unit for controlling a position and an overload, a PWM output unit, an overload detection A / D converter, a rotation speed detection counter unit, and a position detection counter unit It has its purpose.

In addition, the microcomputer can selectively control the servo motor according to the selection of the control program input to the control unit, thereby enabling the servo motor using the one-chip microcomputer to select the main operation and the function of the servo motor There is another purpose in providing a control method.

A control method for a servo motor using a one-chip microcomputer according to the present invention is a control method for a servo motor, in which a speed reducer for reducing a rotation speed is attached to one side of the servo motor, Wherein the servo motor is driven by a motor driving circuit, and the motor driving circuit controls a servo motor by giving or receiving a signal by a microcomputer, wherein the microcomputer controls the speed, And a PWM output unit for receiving a signal generated by the control unit and outputting the PWM signal as a PWM signal.

As a result, the control method of the servo motor using the one-chip microcomputer according to the present invention can selectively control at least one of the speed, the position and the overload of the servo motor according to the selection of the control program inputted to the control unit, The main operation and function of the motor can be selected.

In addition, when the present invention is applied to welding, the present invention can be applied to various fields such as a welding line tracking, a weaving device, or a welding speed control.

1 is a block diagram of the present invention
2 is a flow chart of a motor-driven main program according to the present invention;
FIG. 3 is a flow chart for setting a motor reference position according to the present invention.
FIG. 4 is a flow chart for detecting the current position of the motor according to the present invention.
5 is a flow chart for controlling the position of a motor according to the present invention.
6 is a flowchart for speed detection sampling according to the present invention.
Fig. 7 is a flow chart of a motor speed control according to the present invention.
FIG. 8 is a flow chart of the overload detection of the motor according to the present invention.
9 is a flow chart for controlling overload of a motor according to the present invention.

A control method of a servo motor using a one-chip microcomputer according to the present invention is a control method of a servo motor, in which a speed reducer for reducing a rotation speed is attached to one side of the servo motor, Wherein the servo motor is driven by a motor driving circuit, and the motor driving circuit controls a servo motor by giving or receiving a signal by a microcomputer, wherein the microcomputer controls the speed, And a PWM output unit for receiving a signal generated by the control unit and outputting the PWM signal as a PWM signal.

In addition, the control unit includes a speed control unit for controlling the speed of the servomotor, a position control unit for controlling the position, and an overload control unit for controlling the overload.

The microcomputer includes an overload detection A / D converter for converting a load signal received from the motor driving circuit from an analog signal to a digital signal and sending the digital signal to a control unit, a rotation speed detection counter for sending a rotation speed signal received from the encoder to the control unit, And a position detecting counter for sending the position information received from the position detecting unit to the control unit.

The microcomputer is characterized in that it can select an operation to be performed by the servo motor by selecting and controlling some or all of the speed, position, and overload of the servo motor according to the selection of the program.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of the present invention. In the method of controlling a servo motor using a one-chip microcomputer according to the present invention, the servo motor 1 is provided at one side thereof with a speed reducer 2 And an encoder 3 for sensing the rotational speed and position of the servomotor 1 is attached to the other side of the servomotor 1. The servomotor 1 is driven by a motor driving circuit 40, The microcomputer 10 controls the servo motor 1 by giving or receiving a signal to or from the microcomputer 10. The microcomputer 10 selects one or more of the speed, And a PWM output unit 30 for receiving a signal generated by the control unit 20 and outputting the PWM signal as a PWM signal.

Preferably, the control unit 20 includes a speed control unit 21 for controlling the speed of the servo motor, a position control unit 22 for controlling the position, and an overload control unit 23 for controlling the overload. (10) comprises an overload detection A / D converter (31) for converting a load signal received from the motor drive circuit (40) from an analog signal to a digital signal, And a position detection counter 33 for sending the position information received from the encoder 3 to the control unit 20. The rotation speed detection counter 32 may be a microcomputer,

In addition, the microcomputer 10 is characterized in that it can select an operation to be performed by the servo motor 1 by selecting and controlling some or all of the speed, position, and overload of the servo motor 1 according to the selection of a program .

First, the servomotor 1 can be used as a general servo motor surface, and an AC servo motor, a DC servo motor, or a BLDC (Brush Less Direct Current) motor can be used as the servo motor.

The speed reducer 2 is used to increase the torque while reducing the rotational speed of the motor. The encoder 3 may use a rotary encoder or a linear encoder.

The communication for driving the servomotor 1 may be an analog method or a PWM method. In the present invention, the PWM method is suitable and the PWM signal is transmitted from the microcomputer 10 to the motor driving circuit 40 do.

The speed converter for detecting the current speed of the servomotor 1 counts the rotational speed signal received from the encoder 3 by the rotational speed detecting counter 32 formed in the microcomputer 10, .

The position detecting device for detecting the current position of the servo motor 1 relatively detects the present position of the servo motor based on the output signal with respect to the position of the encoder 3. [ That is, when detecting the A output signal of the encoder and detecting the B output signal of the encoder when the signal is changed from H to L as opposed to when the signal is changed from L (Low) to H (high) In the position comparison for controlling the driving position of the motor, the controller compares the counter position information from the encoder with the setting position of the motor to be driven, and controls the direction and speed of the motor by the PWM signal.

A load detecting device for detecting the load state of the servomotor 1 converts a current flowing in the motor into a voltage and then converts the voltage into a digital value by an overload detection A / D converter 31 formed in the control part, When the value is compared with the maximum allowable current of the motor and the converted value exceeds a certain range of the maximum allowable current value, the driving of the motor can be stopped by the PWM signal.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a flowchart of a motor-driven main program according to the present invention. When it is necessary to change the setting value in the initial setting state, the routine returns to the setting value input server routine.

The motor reference position setting is shown in Fig. 3, and a description thereof will be described later.

When the motor reference setting is completed, the current motor position is compared with the set position and if not, the routine goes to the position setting server routine. The position setting server routine is shown in FIGS. 4 and 5. If the current motor position is the same as the set position, .

The motor speed control server routine is shown in Figs. 6 to 8, and after the speed control of the motor is performed, the routine proceeds to a motor overload processing server routine for checking whether the current applied to the motor is overloaded, And 10, respectively.

FIG. 3 is a flowchart for setting the reference position of the motor according to the present invention. First, when the ON / OFF state is detected with respect to the position sensor and the position sensor is ON, the CW speed setting value, that is, the forward rotation speed When the position sensor is OFF, the CCW speed setting value, that is, the counterclockwise rotation speed value which is rotated counterclockwise is input to the motor, and the PWM signal Is set to CCW and the speed is controlled by outputting.

Of course, when the set time becomes shortest, the PWM signal is outputted as OFF, and a warning such as an alarm for the device error is taken, and the process is repeated to set the position detection counter and the current position to the initial position.

When the initial position of the motor is set, a change in position caused by the use of the servo motor is detected in real time. A flowchart for detecting the current position of the servo motor is shown in Fig.

In case of CW direction, the position counter is decremented by 1. In case of CCW direction, the position counter is incremented by 1 and the counter value is changed to the current position And then it is repeatedly performed through a return (RET).

As shown in FIG. 5, the flowchart of the position control drives the motor by using the initial position set in FIG. 3 and the current position determined in FIG. 4. The initial position (setting position) and the current position If the initial position and the current position set by input are the same, it is natural that the PMW off signal, that is, the state in which driving for changing the position of the motor is not required, is outputted. If the current position is higher than the initial position, the PMW signal is outputted as the CCW signal The process of outputting the PMW signal as a CW signal is returned (RET) and repeated until the initial position and the current position become the same.

When the position setting is completed, the routine goes to the motor speed control server routine for controlling the speed of the motor, and the related flowchart is shown in FIG. 6 and FIG.

FIG. 6 is a flowchart for speed detection sampling according to the present invention. In the interruption by the time generator, a time is set by a time counter, and when there is a set time, a value counted by a speed count counter is moved to a current speed and stored. The current speed of the motor is counted by the interrupt by the encoder input and this value becomes the current speed value.

FIG. 7 is a flowchart related to speed control of a motor according to the present invention, in which a set speed set at a speed at which a motor is to be driven is input, and a speed coefficient counter value measured by an input signal at an encoder is compared, If the current speed is higher than the set speed, it decelerates through the PWM signal. In the opposite case, the PWM signal is output.

8 is a flowchart related to the overload detection of the motor according to the present invention. In the case of sampling time, that is, a time to be measured at a constant time, the current flowing in the motor is converted into a voltage, To a digital value. Since the voltage value measured in this way is very severe in a short period of time, a certain range is set and averaged to a value other than a predetermined range and stored as a detected current value.

FIG. 9 is a flowchart for controlling overload of a motor according to the present invention. When a current value applied to a motor through a motor drive power source is recognized as an overcurrent and an error has occurred, a state set to an overcurrent after an error delay time is released Then, if the detected current value is higher than the set current value, the motor is stopped.

The motor may be stopped or an alarm signal for an overcurrent error may be sent when the detected current value is 80% or more of the maximum allowable current value of the motor.

In the above-described embodiment, the control unit includes a speed control unit for controlling the speed of the servomotor, a position control unit for controlling the position, and an overload control unit for controlling the overload. The present invention is applicable to the speed control unit, the position control unit, You can use some or all of them.

That is, the microcomputer can select an operation to be performed by the servo motor by selecting and controlling some or all of the speed, position, and overload of the servo motor according to the selection of the program. For example, when it is desired to control only the speed of the servo motor Only the speed of the motor can be controlled by the control unit, and only the position can be controlled even if it is desired to control the position only.

When the present invention is used for welding, when the position is controlled, it is possible to control the position of the servo motor as a probe sensor and apply it to control the position of the welding rod. When controlling the speed, That is, the electrode may be used to move the wire laterally with respect to the welding direction to form a wide bead, or to control the welding speed.

In addition, the weld line can be traced through the overcurrent control. That is, it is of course possible to designate the set value shown in FIG. 9 as a value of the state in which the best welding quality can be obtained, and to use the measured current value for welding line trace by minimizing the set value and the error range.

In addition, it can be used in various forms such as weld line tracking, welding speed control, weaving speed control, and the like.

1. Servo motor 2. Decelerator 3. Encoder
10. Microcomputer
20. Control unit 21. Speed control unit 22. Position control unit
23. Overload control section
30. PWM output 31. Overload detection A / D converter
32. Rotation speed detection counter 33. Position detection counter
40. Motor drive circuit 50. Motor drive power source

Claims

A control method for a servo motor,
A decelerator 2 for reducing the rotational speed is attached to one side of the servo motor 1 and an encoder 3 for sensing the rotational speed and position of the servo motor 1 is attached to the other side, 1 is driven by the motor driving circuit 40 and the motor driving circuit 40 controls the servo motor 1 by giving or receiving a signal by the microcomputer 10,
The microcomputer 10 includes a controller 20 for selecting at least one of speed, position and overload of the servomotor 1, a PWM controller 20 for receiving a signal generated by the controller 20 and outputting the PWM signal, And an output unit (30). The method of controlling a servo motor using the one-chip microcomputer.

The method according to claim 1,
The control unit 20 includes a speed control unit 21 for controlling the speed of the servomotor, a position control unit 22 for controlling the position of the servomotor, and an overload control unit 23 for controlling the overload. Control method of servo motor.

The method according to claim 1,
The microcomputer 10 includes an overload detection A / D converter 31 for converting a load signal received from the motor drive circuit 40 from an analog signal to a digital signal and sending the same to a control unit, And a position detection counter 33 for sending the position information received from the encoder 3 to the control unit 20, and a rotation speed detection counter 32 which is sent to the control unit 20, DC Servo motor control method.

The method according to claim 1,
The microcomputer 10 can select one or more of the speed, position, and overload of the servomotor 1 according to the selection of the program and select the operation to be performed by the servomotor 1, Control Method of DC Servo Motor Using Computer.