JP2668876B2 - Servo motor controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a servo motor control device, and more particularly to a control device that continuously performs a series of operations without stopping the servo motor between successive processes. 2. Description of the Related Art Servo motors are widely used in various NC machine tools and robots. A control device for controlling the operation of the servo motor is generally designed to perform feedback control so that the servo motor operates according to a predetermined operation designation program. That is, for example, when a guidance command program for instructing a target rotation position and a target rotation speed is set, the servo motor speed is increased from 0 to the target rotation speed, and then a constant speed is maintained at the target rotation speed. The servomotor is feedback-controlled using the rotation position and the rotation speed as control elements so that the motor is rotated, and then reaches a target rotation position when the rotation speed is reduced to zero. JP 60-2084
The device described in the publication is an example of a control device that feedback-controls the rotational position and rotational speed of a servomotor as control elements. Problems to be Solved by the Invention By the way, in such a conventional servo motor control device, when a plurality of series of operation command programs are set to sequentially operate the servo motors, particularly, the rotational position of the servo motor is positioned. Even if the speed command is unnecessary, the servo motor is once stopped each time the operation by one operation command program is completed, and then the operation is newly started according to the next operation command program. For this reason, there is a problem that there is a large amount of dead time associated with deceleration at the end of the preceding operation command program and acceleration at the start of the subsequent operation designation program, resulting in a long time until the series of operation command programs is completed. there were. Means for Solving the Problems The present invention has been made in view of the above circumstances, and an object of the present invention is to individually operate the servo motors when a plurality of series of operation instruction programs are set. It is to operate continuously without stopping. And, in order to achieve such an object, the present invention
(A) For each of a plurality of processes for sequentially operating the servo motor, a target rotation position of the servo motor, a target time required to reach the target rotation position, a target rotation speed, and a target acceleration or a target output. Setting input means for inputting an operation command program in which arbitrary three data of torque are set, and (b) the target rotation speed of the previous step without stopping the servo motor between successive steps, Control pattern creation for creating a series of control patterns for each of the operation command programs based on a predetermined basic control pattern so as to shift to the target rotation speed of the process and satisfy the three data in each process. Means (c) such that the servomotor continuously performs a series of operations according to the control pattern,
The present invention is characterized in that feedback control is performed using a rotation position, a rotation speed, an acceleration or an output torque as control elements. According to the servo motor control device of the present invention, the operation according to the next operation command program is continuously performed without stopping the servo motors one by one at the end of the operation according to one operation command program. Therefore, the dead time associated with acceleration and deceleration is eliminated, and the time required to complete the series of operation command programs is shortened. In addition, since the servomotor is feedback-controlled using the rotational position, the rotational speed, and the acceleration or the output torque as control elements, a delay in following the control pattern by the servomotor is reduced, and the servomotor has high accuracy according to the control pattern. Operated by. Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a block diagram showing a hardware configuration of a servo motor control device according to the present embodiment.
10, a CPU 12, a ROM 14, and a RAM 16 are provided. Setting input device 1
Numeral 0 is for setting and inputting control data of the AC servomotor 18, and the control data is input to the CPU 12 by key input, paper tape, magnetic tape or the like. The control data consists of a plurality of series of process data as shown in FIG. 2, for example, and the process data is composed of a command program and a command content. The command program includes a position command program “POS”, a speed command program “SPD”, a standby command program “TIME”, a data command program “JMP” and the like. The position command program “POS” and the speed command program “SPD” each constitute an operation command program.
The AC servo motor 18 includes four setting elements of a target rotational position X, a target rotational speed F, a target acceleration K, and a target required time E until the target rotational position X is reached. It is set to a desired value based on the basic control pattern set in. The basic control pattern is, for example, as schematically shown in FIGS. 3 to 6. The basic control turn shown in FIG. 3 is applied to the position command program “POS” and the speed designation program “SPD” which are independently provided like the process data No. 01 in FIG. ₁
Accelerated phase I of the constant speed stage II of time t ₁ ~t _2, and time t ₁ ~t
₂ deceleration stage III. Then, the target rotational position X
Is an area S that is the product of the rotational speed and the time, the target rotational speed F is the rotational speed v in the constant speed stage II, the target acceleration K is the acceleration in the speed increasing stage I and the decelerating stage III, and the target required speed is time E defines the time t _3. The basic control pattern in FIG. 4 is the earliest operation command program in a series of operation command programs as shown in process data No. 03 in FIG. intended to be applied to the servo motor 18 requires no speed command program "SP" for positioning, speed increasing stages of time 0 to t ₁ I, the constant speed stage II of time t ₁ ~t _2, and time t ₁ ~ The shift stage III of t ₃ (decelerated in the figure). The target rotation position X determines the area S, the target rotation speed F determines the rotation speed v ₁ in the constant speed stage II,
Target acceleration K is determined acceleration in speed increasing stages I and shifting stage III, the target duration E defines the time t _3. The rotational speed v ₂ at time t ₃ is the target rotational speed F is applied in the next operation command program. The basic control pattern in FIG. 5 is an intermediate operation command program in a series of a plurality of operation floor programs as in the process data Nos. 04 and 05 in FIG. This is applied to the speed command program "SPD" that does not require positioning of the AC servo motor 18,
Constant speed phase I time 0 to t _1, and time t ₁ ~t ₂ shift stage II
(Decelerated in the figure). The target rotation position X defines an area S, and the target rotation speed F is set to a constant speed step I.
Define the rotational speed v ₁ at the target acceleration K speed change stage II
, The target required time E determines the time t ₂ . The rotational speed v ₂ at time t ₂ is the target rotation speed F is applied in the next operation command program. Further, the basic control pattern in FIG. 6 is applied to the last position command program “POS” and the speed command program “SPD” in a plurality of series of operation command programs as shown in process data No. 06 in FIG. What is done, time 0 to t ₁
Constant speed stage I and a deceleration stage II from time t _{1 to} t ₂ .
The target rotational position X defines the area S, the target rotational speed F defines the rotational speed v in the constant speed stage I, the target acceleration K defines the acceleration in the deceleration stage II, and the target required time E sets the time t ₂ . Establish. Here, as for such a basic control pattern, if any three of the target rotation position X, the target rotation speed F, the target acceleration K, and the target required time E are set, the remaining one is uniquely determined. Therefore, it is only necessary to arbitrarily select and set three of the four setting elements. Incidentally, the target rotational position X, the target rotational speed F and the target acceleration K can also be set by the position, moving speed and acceleration of the NC table 22 driven by the AC servomotor 18 via the feed screw 20. The position, moving speed and acceleration of the NC table 22 are AC.
The rotation position, rotation speed and acceleration of the servo motor 18 and 1
This is because they correspond one-to-one and are substantially the same as setting the target rotational position X, the target rotational speed F and the target acceleration K. The present invention includes such a setting method. The standby command program "TIME" stops the operation of the AC servomotor 18 for a fixed time, and the data command program "JMP" commands process data to be executed next. Returning to FIG. 1, the ROM 14 creates a control pattern based on the position command program “POS” and the speed command program “SPD”, and at the same time, the AC servo motor 18
So as to operate in accordance with its control pattern, a program memory 24 in which a series of processing logic for performing feedback control of rotational position, rotational speed and acceleration as control elements is stored. A control data memory 26 and a control pattern memory 28 in which control patterns are stored are provided. Then, the CPU 12 performs signal processing according to the processing logic stored in the program memory 24 of the ROM 14, and outputs a drive signal SS for driving the AC servomotor 18 to the motor drive device 30.
Output to The CPU 12 is supplied with a current signal SA representing the actual motor current of the AC servomotor 18 via the A / D converter 34 from the motor current detector 32 in addition to the above-described control data. A position signal SX representing the 18 actual rotational positions is supplied. The servo motor control device configured as described above has the seventh configuration.
It has the functions shown in the block diagram of the figure. This function is exhibited by executing the processing logic stored in the program memory 24,
The control data input from the setting input device 10 is first stored in the control data memory 26. In this embodiment, the control data memory 26 and the setting input device 10 constitute setting input means, and the process data Nos. 03 to 06 shown in FIG.
Correspond to a plurality of series of operation command programs for sequentially operating the AC servomotor 18. The control data stored in the control data memory 26 is a control pattern creation block for reading out a command program to be subjected to feedback control in the control data, in this embodiment, a position command program and a speed command program for each process data. Supply to 38. The control pattern creation block 38 creates a control pattern for operating the AC servomotor 18 according to the command program based on the read position command program, speed command program and the basic control pattern. That is, the control pattern of the process data No. 01 is based on the basic control pattern of FIG. 3, and the theoretical rotational position at which the AC servomotor 18 should be positioned is determined at a predetermined time interval, for example,
Created every 1 ms. FIG. 8 conceptually shows a control pattern of the process data No. 01 thus created. The control pattern of the process data No. 03 is the fourth
It is created in the same manner as above based on the basic control pattern shown. In this case, the modulation start point at which the shift from the constant speed stage to the shift stage can be obtained directly from the basic control pattern shown in FIG. 4, but as shown in FIG. using control patterns, it is possible to create a control pattern by calculating a shift begin point U where the area S ₁ and S ₂ are equal. The shift start point U is specifically determined as an operation time or a rotational position after the operation of the process data No. 3 is started. Further, the control patterns of the process data Nos. 04 and 05 are all created based on the basic control pattern of FIG. 5, and the control pattern of the process data No. 06 is based on the basic control pattern of FIG. Created. In these cases, the shift start point may be obtained from the basic control patterns or may be obtained using the basic control patterns shown in FIG. Then, such a control pattern for the series of process data Nos. 03 to 06 is continuously created as conceptually shown in FIG. The value of the one-time derivative of the theoretical rotational position, that is, the rotational speed in FIG. 10, is changed stepwise without becoming 0 in the middle according to the instruction program of a series of process data Nos. 03 to 06 having different target rotational speeds F. AC servo motor 18 according to this control pattern.
Is operated, the AC servomotor is operated.
The rotation speed of 18 is changed stepwise. The theoretical rotational positions X ₁ , X _{3 to} X _{6 in} FIG. 10 are process data No. 01, 0, respectively.
The target rotation positions are 3 to 06. Here, the position command program and the speed designation program usually include arbitrary three values out of four setting elements, and the control pattern is created so as to satisfy the three values. However, when only two of the target rotation position X, the target rotation speed F, the target acceleration K, and the target required time E are set, the predetermined reference rotation speed and the reference acceleration are set to the target rotation speed F, A control pattern is created as the target acceleration K. That is, for example, when only the target rotation position X and the target acceleration K are set, or when only the target rotation position X and the target required time E are set, the reference rotation speed is set as the target rotation speed F, respectively. When a pattern is created and only the target rotational position X and the target rotational speed F are set, a control pattern is created with the reference acceleration as the target acceleration K. When only the target rotation position X and the target required time E are set, a control pattern may be created with the reference acceleration as the target acceleration K. When the target rotation position X, the target rotation speed F, and the target acceleration K are input as the position, the moving speed, and the acceleration of the NC table 22, the pitch of the feed screw 20 is determined before the control pattern is created. To the target rotational position X, target rotational speed F and target acceleration K of the AC servo motor 18 or calculate the theoretical position to be located by the NC table 22 and convert it to the theoretical rotational position of the AC servo motor 18. What should I do? In this way, the control pattern created in the creation block 38 is stored in the control pattern memory 28 thereafter. Then, the theoretical rotation position of the control pattern is sequentially read out at the predetermined time interval and supplied to the position deviation calculation block 40. Position deviation calculation block
A position signal SX indicating the actual rotational position of the AC servomotor 18 is supplied to the encoder 40 from the encoder 36, and the position deviation calculation block 40 determines the position between the actual rotational position and the theoretical rotational position. The deviation is calculated and the result is output to the first operation block 42. The first calculation block 42 calculates the theoretical rotation speed of the AC servo motor 18 at that time, that is, a value corresponding to one-time differentiation of the control pattern, by calculating the position deviation according to a predetermined calculation expression. Is output to the speed deviation calculation block 44. The speed deviation calculation block 44 is supplied with a signal representing the actual rotation speed from a rotation speed calculation block 46 that calculates the actual rotation speed of the AC servomotor 18 based on the position signal SX. The speed deviation calculation block 44 calculates the speed deviation between the actual rotation speed and the theoretical rotation speed, and outputs the result to the second operation block 48. The second arithmetic block 48 calculates the theoretical acceleration of the AC servomotor 18 at that time by calculating the speed deviation according to a predetermined arithmetic expression, that is, a value corresponding to the second derivative of the control pattern, It is output to the acceleration deviation calculation block 50. The acceleration deviation calculation block 50 is supplied with a signal representing the actual acceleration from an acceleration calculation block 52 for calculating the actual acceleration of the AC servomotor 18 based on the position signal SX. The deviation calculation block 50 calculates an acceleration deviation between the actual acceleration and the theoretical acceleration, and outputs the result to the third calculation block 54. The third calculation block 54 is a block for calculating the acceleration deviation.
Based on the acceleration deviation calculated by step 50, a final target current for operating the AC servomotor 18 to eliminate the acceleration deviation is output, and the target current also includes the position deviation and the speed deviation. It has been decided to eliminate it. That is, the first calculation block 42 and the second calculation block 48 perform calculation processing so that the target current output from the third calculation block 54 eliminates the position deviation and the speed deviation. The target current output from the third calculation block 54 is synchronized with the actual rotation phase of the AC servomotor 18 in the phase synchronization block 56, and then, in the current deviation calculation block 58, the current with the motor current represented by the current signal SA. A deviation is calculated. Then, the current deviation is converted into a voltage signal in the fourth operation block 60, pulse-width modulated in the pulse width modulation block 62, and then output to the motor driving device 30 as a drive signal SS. Thereby, the AC servo motor 18 follows the control pattern created in the control pattern creation block 38,
The rotational position, the rotational speed, and the acceleration are feedback-controlled as control elements, and are operated according to the control data set by the setting input device 10. FIG. 11 (a) shows the control data of FIG.
FIG. 4 is a time chart showing a rotation speed when the AC servomotor 18 is operated, and time T _{1 to} T ₂ are process data No. 0.
AC at time T ₂ when operated according to 1.
The rotation position of the servo motor 18 is 400000 set as the target rotation position X of the process data No. 01. Further, the time T _{2 to} T ₃ is a state in which the operation of the AC servomotor 18 is stopped for 1 second by the process data No. 02, and the time T _{3 to} T ₄ is operated according to the process data No. 03. It is in a state. The rotational position of the AC servo motor 18 at time T ₄ is set as the target rotational position X of the process data No.03 30000
0, the rotation speed at that time is 10,000 set as the target rotation speed F of the next process data No. 4, and subsequently, the rotation speed changes from 10,000 to A according to the process data No. 4.
The C servo motor 18 can be operated continuously. In this way, the rotation speed of the AC servomotor 18 is changed stepwise according to the control pattern of the series of process data Nos. 03, 04, 05 and 06, and at the end of the last process data No. 06 therein. in T ₇ is decelerated until the rotational speed becomes zero. Then the time T ₇ ~T ₈ is, AC by the process data No.07
A state in which the operation of the servo motor 18 has been stopped for one second, the time T ₈ through T _9, in a state which is actuated in accordance with the steps data No.01 commanded by the data command program steps data No.08 is there. As described above, in the servo motor control device according to the present embodiment, when a series of operation command programs with different target rotation speeds F, that is, process data Nos. 03 to 06 are set, the AC is executed at the end of the operation by one operation command program. Without stopping the servomotor 18 one by one, the speed is changed to the target rotation speed F of the next operation command program and the rotation speed is changed in a stepwise manner, so that a series of operation command programs can be continuously executed. because you are, required time T ₃ through T ₇ until to terminate the series of operation command program is shortened. That is, in the conventional control device in which the AC servomotor 18 is stopped one by one every time one operation command program ends, as shown in FIG.
Since it takes a lot of time to decelerate and speed up the servomotor 18, the required time T _{3 to} T ₇ is ΔT as compared with the case of the present embodiment.
It just becomes longer. In the present embodiment, the AC servomotor 18 is feedback-controlled using the rotational position, the rotational speed, and the acceleration as control elements, so that the delay of the AC servomotor 18 following the control pattern is small, and The AC servomotor 18 can be operated with high accuracy. As mentioned above, although one Example of this invention was described in detail based on drawing, this invention can be implemented in another aspect. For example, in the above embodiment, the target rotation position X, the target rotation speed
F, the target acceleration K and the target required time E can be set to desired values, respectively. However, when the load torque is constant, the target output torque may be set instead of the target acceleration K. It doesn't matter. Further, in the above embodiment, a control pattern for instructing the theoretical rotational position is created, the position deviation is obtained, the speed deviation and the acceleration deviation are sequentially calculated, and the feedback control is performed. Or a feedback control by creating a control pattern for instructing a theoretical rotational position, a theoretical rotational speed and a theoretical acceleration, or a control pattern for instructing a theoretical rotational position, a theoretical rotational speed and a theoretical acceleration. It is also possible to do so. Note that the output torque of the AC servomotor 18 may be feedback controlled instead of the acceleration. Further, in the above-described embodiment, the case where the rotation speed is reduced in a stepwise manner has been described. However, the AC servomotor 18 may be used in a case where the rotation speed is increased or a case where the reduction and the acceleration are combined.
It is needless to say that various operation modes of can be set by the operation command program. In the above embodiment, the NC table is connected via the feed screw 20.
Although the control device of the AC servo motor 18 that reciprocates the 22 has been described, the present invention is also applicable to various other servo motor control devices such as the machine tool 7, the robot, or a measuring device using the servo motor as a drive source. Can be applied to. Although not specifically exemplified, the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art without departing from the spirit thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating the configuration of a servo motor control device according to one embodiment of the present invention. FIG. 2 visually shows an example of control data set and input to the control device of FIG. FIGS. 3 to 6 are conceptual diagrams of basic control patterns preset in the apparatus of FIG. FIG. 7 is a block diagram illustrating the function of the apparatus of FIG. FIG. 8 is a conceptual diagram showing an example of a control pattern created in the control pattern creation block of FIG. FIG. 9 is a view for explaining an example of a method of obtaining a shift start point in the control pattern creation block of FIG. FIG. 10 is a conceptual diagram showing an example of a control pattern created so as to change the rotation speed stepwise in the control pattern creation block of FIG. FIG. 11 is a time chart showing the rotation speed of the servomotor operated according to the control data of FIG. 2 in comparison with the case of the conventional control device. 10: Setting input device 18: AC servo motor (servo motor) 26: Control data memory 38: Control pattern creation block (control pattern creation means) Process data No. 03 to 06: Operation command program F: Target rotation speed X: Target Rotation position, K: Target acceleration

Claims (1)

(57) [Claims] For each of a plurality of processes for sequentially operating the servomotor, the target rotation position of the servomotor, the target time required to reach the target rotation position, the target rotation speed, and the target acceleration or the target output torque are determined. Setting input means for inputting an operation command program in which any three data are set, and from a target rotation speed of a previous process to a target rotation speed of a next process without stopping the servomotor between successive processes. And a control pattern creating means for creating a series of control patterns for each of said operation command programs based on a predetermined basic control pattern so as to satisfy said three data in each step, The rotation position, the rotation speed, the rotation speed, and the
And a feedback control of acceleration or output torque as a control element.