JPH0217882A - Speed control for motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a speed control method for a motor that moves movable parts such as an arm and a Cartesian table in order to move these movable parts at a target speed. Regarding.

[Prior Art] Conventionally, when controlling the speed of a motor that moves a movable part such as an arm or a Cartesian table, a proportional control method has been widely used. This proportional control method is configured so that the difference between the target speed and the current speed is determined as a speed deviation, and the value obtained by multiplying this speed deviation by a constant called a gain is used as the driving force to supply electric power to the motor. . In this control method, when a non-zero speed deviation occurs, a driving force is generated to make this speed deviation zero, but since the motor and moving parts are subject to frictional resistance and viscous resistance due to air, etc., the frictional resistance and viscous resistance are The motor is in a steady state, leaving a speed deviation sufficient to generate a driving force that is balanced by the motor. That is,
There are disadvantages in that the steady-state speed deviation does not become zero and the motor speed only reaches a speed smaller than the target speed.

In order to eliminate this drawback, as shown in FIGS. 4 and 5, in addition to the proportional control method, a method of performing integral correction has been adopted. In this motor control method, a value obtained by multiplying the time-integrated value of the speed deviation by a constant called an integral gain is added to the driving force obtained by the proportional control method as a correction value for the motor driving force. is being supplied with electricity. Therefore, a non-zero speed deviation remains in each control cycle, and as time passes, its value accumulates and becomes larger. The motor speed increases and is corrected so that it approaches the target speed, and eventually the motor Target speed can be reached.

[Problems to be Solved by the Invention] In this motor speed control method, even if there is frictional resistance of the motor and moving parts or viscous resistance due to air, etc., the steady speed deviation becomes zero, and especially the inertia of the motor and moving parts is small, the motor speed can be reliably maintained at the target speed. However, if the inertia of the motor or moving parts is large, the time required to accelerate the motor to the target speed becomes long, and the correction value obtained from the time integration of the speed deviation becomes very large, causing the target speed to be greatly exceeded. Velocity occurs. Furthermore, the integral correction value included in this speed includes not only a component for balancing frictional resistance and viscous resistance, but also a component for generating the acceleration required to approach the target speed.

In order to reduce this component to zero, the speed must pass through the target speed, and if the inertia is large, this component is particularly large, causing vibrations around the target speed and causing problems such as not being in a steady state. It is occurring.

In addition, as a method to eliminate this drawback, integral correction is not performed until the speed approaches the target speed, and when the speed deviation, which is the difference between the target speed and the current speed, becomes smaller than a certain value, the integral correction is started. Although this method has been adopted, new drawbacks have arisen, such as that it becomes difficult to set the value of the speed deviation at which the integral correction is started.

The object of the present invention is to eliminate all of the above-mentioned drawbacks and to provide a motor speed control method that reliably maintains the motor speed at a target speed without photographing.

[Means for Solving the Problems] In order to solve the above problems, a rotation detecting section that detects the rotation of the motor and sets the rotation amount of one control cycle as the current speed, and a command value of the target speed from the main control section. A servo control section is provided which controls the rotation speed of the motor to a target speed in response to the rotation amount of the motor in the control period. The Chibo control unit: 1) integrates the target speed command values sent from the main control unit;
This integrated value is set as a temporary target position, and the current speed is integrated to set the current position.

2) Calculate the temporary position deviation, which is the difference between the temporary target position and the current position.

3) Corresponding to the tentative position deviation, calculate a tentative target speed which is a value increasing from zero and at which the amount of rotation in one control period is smaller than the tentative position deviation.

4) Calculate the speed deviation, which is the difference between this tentative target speed and the current speed.

5) The value obtained by multiplying the speed deviation by a predetermined value is used as a driving force, and the corresponding electric power is supplied to the motor, and the process returns to 1).

It is configured as follows.

[Function] In the above motor speed control method, the main control section calculates the target speed command value as the motor rotation amount for one control cycle from the stop position of the movable part and the target position, and this is sent to the servo control section. It will be done. When this target speed command value is sent, the target speed command value is added to the temporary target position of the previous control cycle (i.e., the currently stopped position) to calculate a new temporary target position. . The difference between this temporary target position and the current position (that is, the target speed command value) is the temporary position deviation, and the temporary target speed is generated according to this temporary position deviation, and the electric power corresponding to this temporary target speed is used as the driving force. is supplied to the motor, and the motor starts rotating. At this time, since the temporary target speed is set so that the amount of rotation in one control period is smaller than the temporary position deviation, the current speed of the motor does not reach the temporary target position.

In the next control cycle, the above control is repeated, and a new temporary target position larger than the previous one is calculated from the new target speed command value and the current position, but at what rate does the current position increase? As a result, the temporary position deviation increases, the temporary target speed also increases, and the motor rotates faster than before. As the control cycle progresses, the temporary target speed increases and becomes equal to the command value of the target speed from the main control unit, but the current speed of the motor is smaller than the temporary target speed due to the frictional resistance and viscous resistance. value. Furthermore, when the control cycle advances and a new temporary target position is calculated while the target speed command value is a constant value, the temporary target position increases and the temporary target speed becomes lower than the desired speed. growing.

When the driving force due to the speed deviation between the temporary target speed and the current speed reaches a point where it balances the resistance force due to the frictional resistance and viscous resistance, the command value of the target speed, which is the increase hOfjl of the temporary target position, and the current position becomes equal to the current speed, which is the amount of increase in the current speed, and the speed of the motor becomes a steady state, allowing the motor to rotate stably at a desired speed.

[Example] Hereinafter, an example will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a control device for a movable part consisting of an articulated arm (not shown) that moves in response to the rotation of a motor 2 or two tables (not shown) positioned perpendicular to each other. . This control device 1 includes a main control unit 3 that outputs a command value of a target speed as the amount of rotation of a motor 2 in one control cycle when moving a movable part to a target position, and a main control unit 3 that outputs a command value of a target speed as the rotation amount of a motor 2 in one control cycle; A servo control unit 4 that outputs a command signal, a power generation unit 5 that outputs electric power to the motor 2 to obtain a driving force according to the driving force command signal, and a power generation unit 5 that detects the rotation of the motor 2 and calculates the rotation d of one control cycle, that is, the current rotation. It consists of a rotation detection section 6 that determines the speed. As shown in FIGS. 2 and 3, the servo control section 4 1) receives the target speed command value sent from the main control section 3, integrates this command value, and temporarily calculates the product value. The target position is set, and the current speed is set as the current position.

2) Use the temporary position deviation, which is the difference between the temporary target position and the current position, as a line.

3) Corresponding to the tentative position deviation, calculate a tentative target speed which is a value increasing from zero and at which the rotation M in one control period is smaller than the tentative position deviation.

4) Calculate the speed deviation, which is the difference between this tentative target speed and the current speed.

5) A value obtained by multiplying the speed deviation by a predetermined value is used as a driving force, and a power supply command signal is output to supply electric power corresponding to this to the motor 2, and the process returns to 1).

It is configured as follows.

In the above control device, the main control unit 3 calculates a command value for the target speed as the amount of rotation of the motor 2 in one control cycle from the stop position and the target position of the movable part, and sends this to the servo control unit 4. When this target speed command value is sent, the target speed command value is tightened to the temporary target position of the previous control cycle (that is, the current stopped position), and a new temporary target position is calculated. do. The difference between this temporary target position and the current position, that is, the command value of the target speed, is taken as the temporary position deviation, and the temporary target speed is generated according to this temporary position deviation, and the electric power according to this temporary target speed is The driving force is supplied from the generator '5 to the motor 2, and the motor 2 starts rotating. At this time, since the temporary target speed is set so that the amount of rotation in one control cycle is smaller than the temporary position deviation, the current speed of the motor 2 does not reach the temporary target position.

In the next control cycle, the above control is repeated, and a new temporary target position that is larger than the previous one is calculated from the target speed command value from the main control unit 3 and the current position, but what is the rate of increase? , the current position is not increasing. Therefore, the temporary position deviation increases and the temporary target speed also increases. As the control cycle progresses, the temporary target speed increases and becomes equal to the command value of the target speed, but the current speed of the motor 2 becomes a value smaller than the temporary target speed due to the mechanical resistance and viscous resistance. It becomes. As the control cycle progresses roughly and a new temporary target position is calculated, the temporary target position increases and the temporary target speed becomes larger than the desired speed. When the driving force due to the speed deviation between the temporary target speed and the current speed reaches a point where it balances the resistance force due to the frictional resistance and viscous resistance, the command value of the target speed, which is the amount of increase in the temporary target position, and the current position The current speed, which is an increase m, becomes equal to the current speed, and the speed of the motor 2 becomes a steady state, so that the motor 2 can stably rotate at a desired speed.

In addition, in this state, if the resistance force due to the frictional resistance of the motor 2 or the movable parts changes for some reason, the temporary target speed changes to generate a driving force that balances this resistance force, and a new can enter a stable state.

[Effects of the Invention] As explained above, the present invention integrates the target speed command value for each control cycle, integrates the current speed for each control cycle, and calculates the deviation of the integrated value for each control cycle. Since the motor is configured to be driven by calculating a target speed according to this deviation, this corresponds to the driving force consumed in each control cycle due to the frictional resistance of the motor and moving parts and the viscous resistance of the air. It is possible to give an extra command value to generate the driving force, and not only can the target speed of the motor be reliably maintained at a predetermined speed, but also because the inertia of the moving parts and motor is large, the motor can move from a stopped state to a predetermined target speed. Even if it takes a long time to reach , the component of the motor command value that causes acceleration is small, the motor does not significantly exceed the target speed, and there are advantages such as almost no vibration in the motor speed.

Further, the present invention has the advantage that there is no need to perform special control to make the steady speed deviation zero even if frictional resistance and viscous resistance occur, and the control itself can be performed easily.

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining the present invention in detail, FIG. 2 is a flowchart according to the present invention, FIG. 3 is a block diagram explaining the control operation of the present invention, and FIG. 4 is a conventional motor control method. FIG. 5 is a control block diagram of a conventional example.

Claims (1)

[Scope of Claims] A rotation detection unit that detects the rotation of the motor and sets the rotation amount of one control cycle as the current speed, and a rotation detection unit that receives a target speed command value from the main control unit as the rotation amount of the motor in one control cycle. In a speed control method for a motor including a servo control unit that controls the rotational speed of the motor to a target speed, 1) integrating target speed command values sent from the main control unit;
This integrated value is set as a temporary target position, and the current speed is integrated to set the current position. 2) Calculate the temporary position deviation, which is the difference between the temporary target position and the current position. 3) Corresponding to the provisional position deviation, calculate a provisional target speed that increases from zero and has a rotation amount in one control cycle that is smaller than the provisional position deviation. 4) Calculate the speed deviation, which is the difference between this tentative target speed and the current speed. 5) The value obtained by multiplying the speed deviation by a predetermined value is used as a driving force, and the corresponding electric power is supplied to the motor, and the process returns to 1). A motor speed control method characterized by: