JPH078160B2 - Motor controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement of a device for controlling a direct drive motor (hereinafter referred to as a DD motor).

[Prior Art] Conventionally, in a motor used to drive a joint of a robot arm,
When the arm is moved from the start point to the end point, the motor is given a speed command signal represented by a trapezoidal speed curve or a triangular speed curve.

However, when speed control is performed using a trapezoidal speed curve or a triangular speed curve, the acceleration of the motor becomes discontinuous, which causes a problem that the arm vibrates during high speed rotation.

In order to prevent this, some motors use a speed curve represented by a spline curve to smoothly rotate the motor.

[Problems to be Solved by the Invention] In this way, there is a problem that the speed pattern is fixed by an algorithm and the speed calculation becomes complicated, which is not suitable for real-time processing.

The present invention has been made in order to solve such a problem, and it is possible to smoothly rotate a motor, calculate a command value in a short time, and have a degree of freedom in a curve pattern of the command value. It is intended to realize the control device of.

[Means for Solving the Problems] The present invention relates to a motor control device for controlling a direct drive motor, which corresponds to dimensionless displacement and dimensionless time data in which the rotational displacement and time of the motor are dimensionless respectively. The cam curve memory for which multiple types of prepared cam curve tables are prepared, the memory in which the data necessary for controlling the motor is written, and the data written in this memory are sequentially fetched and executed.
When issuing a motor operation command, the stroke h, which is the total amount of rotation of the motor until the target position is reached, the movement time tn, which is the total rotation time of the motor until the target position is reached, and the data of the type of cam curve table. This is the time the motor has rotated up to the present time by selecting the cam curve table in the cam curve memory according to the interpreter given to the cam curve command unit described later and the type of cam curve table given from this interpreter. The movement real time Rt is updated every time the command value is obtained, and the updated movement real time Rt is divided by the movement time tn to obtain the dimensionless time T.
Then, the dimensionless displacement S corresponding to this dimensionless time T is obtained from the selected cam curve table. When the corresponding dimensionless displacement data is not in the cam curve table, the dimensionless displacement prepared in the cam curve table is obtained. The dimensionless displacement S is obtained by performing an interpolation operation using the data of
The actual displacement s is obtained by multiplying
And a positioning servo driver that controls so that the rotational position of the motor matches the command value based on the command value obtained by this cam curve command unit. This is a characteristic motor control device.

[Examples] The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a motor control device according to the present invention.

In the figure, 10 is a keyboard for inputting the moving distance (stroke) and moving time of the motor driven object and the data of the type of cam curve table described later, and 20 is an NC command that receives the input of the keyboard 10 and responds to this input. Is a non-volatile memory in which the NC command from the data input unit 20 is stored.

An interpreter 40 sequentially fetches NC commands from the memory 30 and executes them.

50 is a cam curve memory provided a plurality of types of cam curve table 50 ₁ ~50n. Here, the cam curve table is a table in which the rotational displacement of the motor and the time-dimensionalized data are associated with each other.

Reference numeral 60 denotes a cam curve command unit, which uses the cam curve type data provided by the interpreter 40 to determine the cam curve table 50 ₁
One of .about.50n is selected, and a command value satisfying the stroke and movement time given from the interpreter 40 is calculated while referring to the selected cam curve table.

70 is a positioning servo driver that controls the DD motor 80 based on the command value calculated by the cam curve command unit 60 so that the motor rotation position matches the command value.

The operation of the apparatus thus configured will be described.

The NC command is written in the memory 30 by the keyboard 10 via the data input unit 20. Interpreter 40 is memory 30
NC commands are sequentially fetched from and executed.

When issuing a motor operation command, the interpreter 40 gives the cam curve command unit 50 the stroke h, the moving time tn, and the data of the type of the cam curve table, and uses a timer (not shown) for each time τ. To sample. Here, the stroke h is the total rotation amount of the motor before reaching the target position, and the movement time tn is the total rotation time of the motor until reaching the target position.

As shown in FIG. 2, the cam curve is a graph showing the relationship between the dimensionless displacement S and the dimensionless time T in which the rotational displacement and the time of the motor are made dimensionless for each constant time ΔT. As shown in FIG. 3, the cam curve table is the value of the dimensionless displacement S taken at each time ΔT and the reciprocal 1 / ΔT of the table pitch.
The dimensionless maximum velocity Vm and the dimensionless maximum acceleration Am are stored.

The cam curve command unit 60 is activated every time τ by the timer described above. The operation of the cam curve command unit 60 will be described with reference to the flowchart of FIG.

In FIG. 4, first, in process A1, the movement real time Rt is updated. That is, the moving real time Rt + τ is set to the new moving real time.
Set to Rt. The actual movement time Rt is the time the motor has rotated up to the present time. The reason for updating is that every time the cam curve command unit 60 is activated every time τ, the rotation time of the motor is increased by τ as compared with the previous activation.

Then, in process A2, the updated moving real time Rt is converted into the dimensionless time T. This conversion is performed by T = Rt / tn. The dimensionless time T increases in proportion to the movement real time Rt.
When Rt reaches the moving time tn, T = 1.

Next, in process A3, the index ΔTn in the cam curve table is obtained from the dimensionless time T. This calculation is ΔTn = In
It is performed by t (T / ΔT). Here, Int (T / ΔT) is an operation in which the fractional part of the divided value T / ΔT is truncated and only the integer part is left. For example, if T / ΔT = 5.35, then Int (T /
ΔT) = 5. The index ΔTn means the number of the dimensionless displacement data prepared in the cam curve table. By taking Int (T / ΔT), it is possible to find out what number data is the dimensionless time T that is closest to the value of the dimensionless time T and is equal to or less than the calculated value of the dimensionless time T. The value of the dimensionless time T obtained by the calculation is a continuous value that can take various values, whereas the dimensionless time data prepared in the cam curve table is a discrete value. Apply the appropriate processing.

Next, in process A4, the dimensionless displacement S is calculated by the interpolation calculation given by the following equation using the data prepared in the cam curve table.
Ask for.

S = {S (ΔTn ₊₁ ) −S (ΔTn)} · {(T / ΔT) −ΔTn} + S (ΔTn) ...
(1) S (ΔTn): value of S at index ΔTn S (ΔTn ₊₁ ): value of S at index ΔTn ₊₁ FIG. 5 is a graph for explaining how to perform the interpolation operation by the equation (1). is there.

FIG. 5 shows a case where the divided value T / ΔT is a value including a decimal part. The value of S we are trying to find is
It lies between the ΔTnth dimensionless displacement value S (ΔTn) and the ΔTn ₊ 1th dimensionless displacement value S (ΔTn _{+ 1} ). Division value T / ΔT
The fractional part of is T / ΔT−ΔTn. Dimensionless displacement S (ΔT
The data numbers of n) and S (ΔTn ₊₁ ) are different from each other. From this, the difference between S and S (ΔTn) can be obtained by multiplying S (ΔTn _{+ 1} ) -S (ΔTn) by T / ΔT-ΔTn.
The dimensionless displacement S is obtained by adding S (ΔTn) to this difference.

Then, in process A5, the actual displacement s is obtained by S × h = s.

Then, in process A6, the actual displacement s is determined by the positioning servo driver.
It is given to 70 as a command value.

Next, in process A7, when T ≧ 1, the process of the cam curve command unit 60 is terminated, and when it is not satisfied, the process from A1 is repeated again.

The rotational position of the motor is controlled in this procedure.

[Effect] According to the present invention, the following effects can be obtained.

Since a plurality of types of cam curve tables are stored and can be selected, the motor can be controlled so that the speed and acceleration can be set according to the purpose.

Since the cam curve table is dimensionless, it is possible to correspond to any combination of stroke and movement time.

Since the cam curve table is prepared in advance, the command value can be calculated in a short time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a motor control device according to the present invention, and FIGS. 2 to 5 are operation explanatory diagrams of the device of FIG. 10 ...... keyboard, 20 ...... data input unit, 30 ...... memory, 40 ...... interpreter, 50 ...... cam curve memory, 50 ₁
~ 50n …… Cam curve table, 60 …… Cam curve command section, 7
0 …… Positioning servo driver, 80 …… DD motor.

Claims (1)

[Claims] 1. A motor control device for controlling a direct drive motor, wherein a plurality of types of cam curve tables are provided which correspond to dimensionless displacement and dimensionless time data in which the rotational displacement and time of the motor are dimensionless respectively. The prepared cam curve memory, the memory in which the data necessary for controlling the motor is written, and the data written in this memory are sequentially fetched and executed.
When issuing a motor operation command, the stroke h, which is the total amount of rotation of the motor until the target position is reached, the movement time tn, which is the total rotation time of the motor until the target position is reached, and the data of the type of cam curve table. This is the time the motor has rotated up to the present time by selecting the cam curve table in the cam curve memory according to the interpreter given to the cam curve command unit described later and the type of cam curve table given from this interpreter. The movement real time Rt is updated every time the command value is obtained, and the updated movement real time Rt is divided by the movement time tn to obtain the dimensionless time T.
Then, the dimensionless displacement S corresponding to this dimensionless time T is obtained from the selected cam curve table. When the corresponding dimensionless displacement data is not in the cam curve table, the dimensionless displacement prepared in the cam curve table is obtained. The dimensionless displacement S is obtained by performing an interpolation operation using the data of
The actual displacement s is obtained by multiplying
And a positioning servo driver that controls so that the rotational position of the motor matches the command value based on the command value obtained by this cam curve command unit. Characteristic motor control device.