WO2018154745A1

WO2018154745A1 - Electronic cam pattern generation method and electronic cam pattern generation device

Info

Publication number: WO2018154745A1
Application number: PCT/JP2017/007326
Authority: WO
Inventors: 昇西原; 学濱口
Original assignee: 三菱電機株式会社
Priority date: 2017-02-27
Filing date: 2017-02-27
Publication date: 2018-08-30
Also published as: JPWO2018154745A1; JP6407478B1

Abstract

Provided is an electronic cam pattern generation method in a synchronous control system which controls a secondary shaft in synchronization with a primary shaft position, the method including: a first step of setting a plurality of sections relative to the primary shaft position; a second step of setting a boundary condition for the plurality of sections; and a third step for generating, as a septic function of the primary shaft position in at least one section of the plurality of sections, an electronic cam pattern indicating a position of the secondary shaft on the basis of the boundary condition.

Description

Electronic cam pattern generation method and electronic cam pattern generation apparatus

The present invention relates to an electronic cam pattern generation method and an electronic cam pattern generation apparatus in a synchronous control system.

Industrial machines such as packaging machines are equipped with multiple axes for carrying and processing workpieces, and servo motors corresponding to each axis are controlled so as to cooperate with each other in a desired operation pattern and timing. There are many that perform a series of machining processes. As described above, a system that controls a plurality of servo motors in cooperation with each other is also called a synchronous control system.

Some synchronous control systems have an electronic cam function. In the electronic cam function, instead of using a mechanical cam that rotates around the main shaft, the slave servo motor is controlled in synchronization with the main shaft position, thereby causing the object such as a workpiece or tool to perform a desired operation. It is a function. In a servo motor system having an electronic cam function, precise machining is possible by precisely controlling a plurality of servo motors corresponding to a plurality of axes according to a desired operation pattern.

A synchronous control system having an electronic cam function generally controls a slave servo motor in accordance with a desired operation pattern composed of a plurality of target positions defined in time series. In order to realize control according to a desired operation pattern composed of a plurality of target positions defined in time series, for each section in which one of two temporally adjacent target positions is a start position and the other is an end position There is a method of generating a curve and connecting these curves to generate an electronic cam pattern. The electronic cam pattern is a pattern in which values such as the position, speed, and acceleration of the slave servomotor are determined according to the spindle position in order to realize the electronic cam function described above.

As an example of such a synchronous control system, Patent Document 1 discloses that by setting the position, speed, and acceleration at the boundary points of two sections adjacent in time to the same value and performing spline interpolation of each section, A servo motor control system capable of obtaining an electronic cam pattern with small acceleration fluctuation at a boundary point corresponding to a joint of each section is disclosed.

JP 2006-172438 A

In the technique described in Patent Document 1, quintic function spline interpolation is used to generate an electronic cam pattern for position control. However, even if the spline interpolation of the quintic function is used, the jerk fluctuation at the boundary point of the spline interpolation cannot be suppressed. When jerk fluctuation occurs, impact and vibration on a mechanical device using an electronic cam function of an industrial machine or the like increases, and the life of a tool or the like constituting the mechanical device may be shortened. For example, in the case where the mechanical device is a packaging machine, the life of the rotary cutter mechanism is shortened if jerk fluctuation occurs.

The present invention has been made in view of the above, and an object thereof is to obtain an electronic cam pattern generation method and an electronic cam pattern generation device capable of suppressing impact and vibration on a mechanical device.

In order to solve the above-described problems and achieve the object, an electronic cam pattern generation method according to the present invention is an electronic cam pattern generation method in a synchronous control system that controls a slave shaft in synchronization with a main shaft position. And a first step of setting a plurality of sections according to the position. In the electronic cam pattern generation method according to the present invention, the electronic cam pattern generation device is configured to set a boundary step for a plurality of sections, and a boundary step based on the boundary conditions in at least one section of the plurality of sections. And a third step of generating an electronic cam pattern indicating the position of the slave shaft as a seventh-order function of the main shaft position.

The method of generating an electronic cam pattern according to the present invention has an effect that it is possible to suppress impacts and vibrations on a mechanical device.

The figure which shows the structural example of the synchronous control system concerning Embodiment 1. FIG. FIG. 3 is a diagram illustrating a configuration example of a control circuit according to the first embodiment. The flowchart which shows an example of the process sequence in the electronic cam pattern production | generation part of Embodiment 1. The figure which shows an example of the area set in Embodiment 1, and the electronic cam pattern of a driven shaft position The figure which shows the follower speed when the electronic cam pattern of the follower position is determined as shown in FIG. The figure which shows a follower axis acceleration when the follower position electronic cam pattern is determined as shown in FIG. The figure which shows the jerk of a driven shaft when the electronic cam pattern of a driven shaft position is defined as shown in FIG. The figure which shows the structural example of the synchronous control system concerning Embodiment 2. FIG. A flowchart which shows an example of the process sequence in the electronic cam pattern production | generation part of Embodiment 2. The figure which shows an example of the electronic cam pattern in case the calculation error in a floating point calculation arises in the electronic cam pattern of Embodiment 2. The figure which shows an example of the electronic cam pattern after the area division | segmentation of Embodiment 2 was performed

Hereinafter, an electronic cam pattern generation method and an electronic cam pattern generation device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a synchronous control system according to the first embodiment of the present invention. As shown in FIG. 1, a synchronous control system 100 according to the first embodiment is a synchronous control system that controls a slave shaft in synchronization with a main shaft position, and includes a control device 1, a servo amplifier 2, and a motor 3. The synchronous control system 100 according to the first embodiment is used to realize processes such as processing and conveyance in industrial machines such as packaging machines. In FIG. 1, one set of the servo amplifier 2 and the motor 3 is shown, but a plurality of sets of the servo amplifier 2 and the motor 3 may be used.

The synchronous control system 100 of Embodiment 1 is used for a rotary cutter device in a packaging machine, for example. The rotary cutter device is a device that cuts a sheet conveyed at a constant speed by a conveyor so as to have a desired sheet length by a rotary cutter. When the synchronous control system 100 is used for a rotary cutter device, the axis of the conveyor is the main axis and the axis of the rotary cutter is the secondary axis. By controlling the motor 3 corresponding to the slave shaft in synchronization with the main shaft position, the rotary cutter can cut the sheet with a desired sheet length.

The rotary cutter device is an example of a mechanical device to which the synchronization control system 100 of the first embodiment is applied. The synchronization control system 100 of the first embodiment is not limited to this example, and is a slave shaft in synchronization with the main shaft position. The present invention is applicable to any mechanical device as long as it is a mechanical device that operates this motor.

In order to control the motor 3 corresponding to the slave shaft in synchronization with the main shaft position, the synchronous control system 100 of the present embodiment is an electronic in which values such as the position, speed, and acceleration of the motor 3 are defined according to the main shaft position. Use a cam pattern. The main shaft position is the rotation angle of the main shaft.

The control device 1 generates an electronic cam pattern, generates a command for the servo amplifier 2 based on the input spindle position and the electronic cam pattern, and outputs the command to the servo amplifier 2. The control device 1 is an example of an electronic cam pattern generation device according to the present invention. The servo amplifier 2 controls the motor 3 corresponding to the slave shaft based on the command. The spindle position may be input from a pulse generator (not shown) that detects the position of the spindle, or may be a virtually generated spindle position when the spindle is a virtual axis. Further, when the spindle position is a virtually generated spindle position, the control device 1 may generate the spindle position. In FIG. 1, the servo amplifier and the motor corresponding to the main shaft are not illustrated, but the synchronous control system 100 includes the servo amplifier and the motor corresponding to the main shaft, and the control device 1 issues a command to the servo amplifier corresponding to the main shaft. It may be generated.

As shown in FIG. 1, the control device 1 generates an electronic cam pattern generation unit 10 that generates an electronic cam pattern, and a command generation that generates and outputs a command to the servo amplifier 2 based on the spindle position and the electronic cam pattern. Part 15. The electronic cam pattern generation unit 10 includes a section setting unit 11, a pattern generation unit 12, a natural waveform generation unit 13, and a connection unit 14.

Next, the hardware configuration of the control device 1 will be described. The electronic cam pattern generation unit 10 and the command generation unit 15 are realized by a processing circuit. The processing circuit is a control circuit including a processor, for example.

FIG. 2 is a diagram illustrating a configuration example of the control circuit. The control circuit 200 illustrated in FIG. 2 includes a processor 201 and a memory 202. The processor 201 is a CPU (Central Processing Unit), a microprocessor, or the like. The memory 202 corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, or a magnetic disk.

When the electronic cam pattern generation unit 10 and the command generation unit 15 are realized by the control circuit 200 illustrated in FIG. 2, the functions of the electronic cam pattern generation unit 10 and the command generation unit 15 are stored in the memory 202. The program for realizing the functions of the electronic cam pattern generation unit 10 and the command generation unit 15 is realized by being executed by the processor 201. The memory 202 is also used as a storage area when a program is executed by the processor 201.

Alternatively, the electronic cam pattern generation unit 10 and the command generation unit 15 may be realized by a processing circuit that is dedicated hardware. The processing circuit that is dedicated hardware includes, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. Further, the electronic cam pattern generation unit 10 and the command generation unit 15 may be realized by a processing circuit, a part of which is dedicated hardware, and the remaining part may be realized by the control circuit 200 described above.

Next, the electronic cam pattern generation method of this embodiment will be described. FIG. 3 is a flowchart showing an example of a processing procedure in the electronic cam pattern generation unit 10 of the present embodiment. As shown in FIG. 3, first, the section setting unit 11 sets a section according to the spindle position (step S1). In step S1, the section may be set in any way. For example, if there is a condition defined regarding the relationship between the main axis and the slave axis, the section setting unit 11 sets the section according to this condition.

An example of a condition defined for the relationship between the main axis and the slave axis is one or more positions to pass through. Here, the position to be passed is indicated by a coordinate value in a two-dimensional coordinate system including, for example, a main shaft position and a sub shaft position, that is, a rotation angle of the sub shaft. That is, for example, the position to be passed is indicated by a coordinate value on the xy plane when the principal axis position is x and the slave axis position is y when the reference position is the origin. Here, when four positions to pass through are set on the xy plane, the section setting unit 11 sets each section so that these four points become the boundaries of the sections.

The section setting unit 11 instructs the connecting unit 14 with information indicating the set section. The information indicating the section is, for example, information indicating the correspondence between the spindle position range with the reference position as the origin and the section identification information. For example, when there are three set sections, information indicating the sections includes section # 1 in which the spindle position is from 0 to m1, section # 2 in which the spindle position is from m1 to m2, and the spindle position is This is information indicating the range of each section in which m2 to m3 are section # 3.

Also, there may be a section in which a waveform unique to the mechanical device, that is, a unique function is defined. For example, there may be a section in which the slave shaft position operates so as to be directly proportional to the main shaft position. In this embodiment, an example in which there is a section in which a specific waveform is defined will be described. As described above, when there is a section in which a specific waveform is determined, the section setting unit 11 sets a section in which a specific waveform is determined as one section.

After step S1, the section setting unit 11 instructs the specific waveform generation unit 13 to generate a specific waveform together with information indicating a section for generating a specific waveform, and the specific waveform generation unit 13 generates a specific waveform. The characteristic waveform generation unit 13 outputs information indicating the generated characteristic waveform to the connection unit 14 together with identification information indicating the corresponding section (step S2). The information indicating the eigen waveform may be, for example, a calculation formula, or may be the degree of the polynomial and the coefficient of each order when it is determined that the eigen waveform is represented by a polynomial. The information indicating the natural waveform is not limited to these, and any information may be used as long as the connecting unit 14 can generate the natural waveform.

In addition, the section setting unit 11 sets one of the sections not instructed to generate a pattern as a processing target section, outputs a boundary condition related to the processing target section to the pattern generation unit 12, and outputs a pattern to the pattern generation unit 12. Directs generation. Here, the pattern indicates this function when the slave shaft position is expressed by a function having the spindle position as a variable. In the present embodiment, this function is a seventh order function. When receiving the pattern generation instruction, the pattern generation unit 12 calculates the coefficient of the seventh-order function using the boundary condition (step S3). Although details of Step S2 and Step S3 will be described later, the coefficient of the seventh-order function is determined so that the acceleration becomes 0 and the jerk, that is, the jerk, becomes 0 at the boundary of the section.

The pattern generation unit 12 determines a pattern, that is, a function using the calculated coefficient (step S4). The pattern generation unit 12 outputs information indicating the determined pattern to the connection unit 14 together with identification information indicating the corresponding section. The information indicating the determined pattern may be, for example, a calculation formula or the coefficient calculated in step S3. The information indicating the determined pattern is not limited to these, and may be information that allows the connecting unit 14 to generate the determined pattern. The section setting unit 11 determines whether the processing of all sections has been completed, that is, for all sections, either a pattern generation instruction to the pattern generation section 12 or a specific waveform generation instruction to the natural waveform generation section 13. It is determined whether or not (step S5), and when the processing for all the sections is completed (step S5, Yes), the electronic cam pattern generation processing is ended. If there is a section in which processing is not completed (No in step S5), the processing from step S3 is repeated by changing the processing target section and instructing the pattern generation unit 12 to generate a pattern.

Through the above processing, the linking unit 14 can receive information indicating the pattern of each section and information indicating the specific waveform. The connecting unit 14 generates an electronic cam pattern by sequentially connecting the patterns of the sections, and outputs information indicating the electronic cam pattern to the command generating unit 15. In other words, the pattern of each section is an electronic cam pattern of each section. An example of information indicating an electronic cam pattern is a calculation formula for information indicating each section and the electronic cam pattern for each section. Alternatively, the information indicating the electronic cam pattern may be information indicating each section, and the order and coefficient for each section. Here, the electronic cam pattern generated by the connecting unit 14 is output to the command generating unit 15, but information indicating the electronic cam pattern generated by the connecting unit 14 is stored in a storage unit (not shown) to generate the command. The unit 15 may read information indicating the electronic cam pattern from the storage unit.

Next, step S2 and step S3 described above will be described with specific examples. FIG. 4 is a diagram illustrating an example of the section set in the present embodiment and the electronic cam pattern at the driven shaft position. In the example shown in FIG. 4, it is assumed that the coordinate values of four points on the xy plane are specified as the positions to pass through, where the above-described main shaft position is x and the slave shaft position is y. Hereinafter, coordinate values on the xy plane are expressed as (x coordinate value, y coordinate value).

In the example shown in FIG. 4, the coordinate values of the four points that are positions to be passed are (0, P0), (m1, P1), (m2, P2), and (m3, P3), respectively. In the example shown in FIG. 4, the spindle position from 0 to m1 is set as section # 1, the spindle position from m1 to m2 is set as section # 2, and the spindle position from m2 to m3 is set as section # 3. Hereinafter, patterns corresponding to section # 1, section # 2, and section # 3, that is, functions are expressed as F ₁ (k) and F using k which is the spindle position with the start position of each section as the origin of the spindle position. ₂ (k), and F ₃ (k). In FIG. 4, the spindle position is indicated by x with a certain reference position as a limit. If the x coordinate value of the spindle position at the start position of each section is xs, k = x−xs. In the example illustrated in FIG. 4, k = x in the section # 1, k = x−m1 in the section # 2, and k = x−m2 in the section # 3.

It is assumed that a unique waveform is determined for the section # 2. Therefore, F ₂ (k) is a function indicating a natural waveform. Here, it is assumed that the slope of F ₂ (k) is a linear function of the fixed value β. That is, F ₂ (k) = βk + P1. F ₂ (k) is generated in step S2 described above.

For section # 1, F ₁ (k) is defined as a seventh-order function of k as shown in the following equation (1). A0 to A7 are coefficients.
F ₁ (k) = A0 + A1k + A2k ² + A3k ³ + A4k ⁴ + A5k ⁵ + A6k ⁶ + A7k ⁷ (1)

The section setting unit 11 sets the section length X ₁ as the boundary condition of section # 1, the slave shaft position P1 at the start position of the section, the slave shaft position P1 at the end position of the section, and the slave shaft at the start position of the section. Is defined as V0 and the speed of the slave shaft at the end position of the section is defined as V1. Furthermore, the acceleration and jerk of the slave axis are set to 0 at the start position and end position of the section as boundary conditions. Thus, the boundary conditions are the position, speed, acceleration, and jerk of the slave shaft at each of the start position and end position of the section. The speed at the start position of the section and the speed at the end position of the section in each section may be input from the outside or may be determined in advance.

The speed of the slave shaft is obtained by differentiating equation (1) by k, that is, dF ₁ (k) / dk, and is represented by the following equation (2).
dF ₁ (k) / dk = A1 + 2A2k + 3A3k ² + 4A4k ³ + 5A5k ⁴ + 6A6k ⁵ + 7A7k ⁶ (2)

In addition, the acceleration d ² F ₁ (k) / dk ^{2 of} the slave shaft and the jerk d ³ F ₁ (k) / dk ³ of the slave shaft are expressed by the following equations (3) and (4), respectively.
d ² F ₁ (k) / dk ² = 2A2 + 6A3k + 12A4k ² + 20A5k ³ + 30A6k ⁴ + 42A7k ⁵ (3)
d ³ F ₁ (k) / dk ³ = 6A3 + 24A4k + 60A5k ² + 120A6k ³ + 210A7k ⁴ (4)

Substituting the boundary conditions of the position, velocity, acceleration, and jerk at the end position at the start position of the section into the above expression (1) to expression (4), and solving the simultaneous equations, the following expression (5 The coefficients A0 to A7 are obtained as shown in FIG.
A0 = P0, A1 = V0, A2 = 0, A3 = 0,
A4 = − (15V1 + 20V0) / X ₁ ³ + (35P1-35P0) / X ₁ ⁴
A5 = (39V1 + 45V0) / X 1 4 - (84P1-84P0) / X 1 5
A6 = − (34V1 + 36V0) / X ₁ ⁵ + (70P1-70P0) / X ₁ ⁶
A7 = (10V1 + 10V0) / X ₁ ⁶ − (20P1-20P0) / X ₁ ⁷ (5)

The slave shaft position at the start position of section #n is Pns, the slave shaft position at the end position of section #n is Pne, the function corresponding to section #n is F _n (x), and the speed at the start position of section #n is Vns, when the velocity at the end position of the section #n Vne, generalizes the section length of the section #n as X _n, equation (1) and (5), the following equation (6) and (7) It becomes.
_{F n (k) = A0 +} A1k + A2k 2 + A3k 3 + A4k 4 + A5k 5 + A6k 6 + A7k 7
(6)
A0 = Pn, A1 = Vn, A2 = 0, A3 = 0,
A4 = - (15Vne + 20Vns) / X n 3 + (35Pne-35Pns) / X n 4
A5 = (39Vne + 45Vns) / X n 4 - (84Pne-84Pns) / X n 5
A6 = - (34Vne + 36Vns) / X n 5 + (70Pne-70Pns) / X n 6
A7 = (10Vne + 10Vns) / X n 6 - (20Pne-20Pns) / X n 7
... (7)

In step S3 described above, the pattern generation unit 12 calculates a coefficient according to the above equation (7) for each section for which no specific waveform is defined, and determines a function as in the equation (6). And the connection part 14 connects the function of each area, and can obtain an electronic cam pattern as shown in FIG.

As described above, in the electronic cam pattern generation method in the synchronous control system 100 of the present embodiment, the control device 1 sets the first step for setting a plurality of sections according to the spindle position and the boundary conditions for the plurality of sections. The above-described step S1 that is the second step to be set is included. In addition, the electronic cam pattern generation method in the synchronous control system 100 of the present embodiment uses an electronic cam pattern indicating the position of the slave shaft based on the boundary condition in the seventh order of the main shaft position in at least one of the plurality of sections. Steps S3 and S4, which are third steps generated as a function, are included.

FIG. 5 is a diagram showing the follower speed when the follower position electronic cam pattern is determined as shown in FIG. FIG. 6 is a diagram showing the driven shaft acceleration when the driven cam position electronic cam pattern is determined as shown in FIG. FIG. 7 is a diagram showing the jerk of the driven shaft when the electronic cam pattern at the driven shaft position is determined as shown in FIG. By using the electronic cam pattern of the present embodiment, the acceleration and jerk at the boundary of each section become zero. In other words, compared to the case where a quintic function is used to generate an electronic cam pattern, the movement of the servo motor becomes smoother, the load on the mechanical device due to impact and vibration is suppressed, and a longer life of the mechanical device is expected. it can.

Further, the passing position is determined by each mechanical device, and an arbitrary number of sections and section length can be set. Further, even if an arbitrary section is a unique waveform unique to the apparatus, the patterns of the sections before and after the section may be determined according to the boundary condition of the section of the specific waveform. Note that when there is no section having a natural waveform, the control device 1 does not need to include the natural waveform generation unit 13, and the function of all the sections may be determined by the pattern generation unit 12.

In the above example, the control device 1 has a function as an electronic cam pattern device that generates an electronic cam pattern. Instead of the control device 1, an electronic cam pattern device that generates an electronic cam pattern is used. You may provide the control apparatus which produces | generates the instruction | command with respect to the servo amplifier 2 based on a spindle position and an electronic cam pattern. In this case, the electronic cam pattern device includes the electronic cam pattern generation unit 10 shown in FIG. 1, and the electronic cam pattern output from the electronic cam pattern generation unit 10 is input to the control device. Based on the cam pattern, a command for the servo amplifier 2 is generated and output to the servo amplifier 2.

Embodiment 2. FIG.
FIG. 8 is a diagram illustrating a configuration example of a synchronization control system according to the second exemplary embodiment of the present invention. As shown in FIG. 8, the synchronous control system 100a of the second embodiment includes a control device 1a, a servo amplifier 2, and a motor 3. The control device 1a is the same as the control device 1 of the first embodiment except that the electronic cam pattern generation unit 10a is provided instead of the electronic cam pattern generation unit 10 of the first embodiment. The electronic cam pattern generation unit 10a adds the error evaluation unit 16 to the electronic cam pattern generation unit 10 of the first embodiment, and includes the pattern generation unit 12a instead of the pattern generation unit 12. It is the same as the device 1. Components having the same functions as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and redundant description is omitted. Hereinafter, differences from the first embodiment will be mainly described.

The electronic cam pattern generation unit 10a of the present embodiment is realized by a processing circuit in the same manner as the electronic cam pattern generation unit 10 of the first embodiment. This processing circuit may be dedicated hardware as in the first embodiment, or may be a control circuit including a processor.

In the present embodiment, a method for generating an electronic cam pattern in consideration of a calculation error in a floating-point operation when generating an electronic cam pattern will be described. FIG. 9 is a flowchart illustrating an example of a processing procedure in the electronic cam pattern generation unit 10a of the present embodiment. As shown in FIG. 9, the processing procedure in the electronic cam pattern generation unit 10a of the present embodiment is performed except that steps S11 to S13 are added between step S3 and step S4 of the processing described in FIG. This is the same as the first embodiment.

After step S3, the pattern generation unit 12a outputs the calculated coefficient to the error evaluation unit 16. The error evaluation unit 16 performs error evaluation using the coefficient acquired from the pattern generation unit 12a (step S11). Specifically, the error evaluation unit 16 calculates an error caused by, for example, a floating point calculation. Depending on the synchronous control system, a calculation error may occur when performing calculation using an electronic cam pattern such that the command generation unit 15 cannot handle double precision real numbers. In particular, there are cases where the accuracy of calculation is limited, for example, an inexpensive device cannot perform calculations using double precision real numbers. In each section, the spindle position is 0 at the start position, but the value of the spindle position increases toward the end position. In this embodiment, since the seventh-order calculation of the spindle position is performed, the calculation error tends to increase as the value of the spindle position increases. For this reason, in the present embodiment, in consideration of such a calculation error, if the calculation error is large, the section is divided as described later. Specifically, the error evaluation unit 16 calculates the maximum value of error that occurs when, for example, a single precision real number is used.

The error evaluation unit 16 determines whether or not the error may exceed a threshold value within the section (step S12). If the error does not exceed the threshold value (step S12, No), the error evaluation unit 16 proceeds to the pattern generation unit 12a. Notify that. Thereby, step S4 and subsequent steps are performed. When the error exceeds the threshold value (step S12, Yes), the error evaluation unit 16 instructs the pattern generation unit 12a to divide the section. Thereby, the pattern generation unit 12a performs section division (step S13) and returns to step S3. The pattern generation unit 12a also sets boundary conditions for divided sections in section division. As described above, the control device 1a determines whether to divide the section according to the calculation error when calculating the electronic cam pattern.

FIG. 10 is a diagram illustrating an example of an electronic cam pattern in the case where a calculation error occurs in a floating point calculation in the electronic cam pattern. In the example shown in FIG. 10, the curve 300 shows the electronic cam pattern shown in FIG. 4 in the first embodiment, and the curve 301 shows the electronic cam pattern when a calculation error occurs in the floating point calculation. . In the curve 301, an error occurs due to a calculation error in the floating point calculation near the end point of the section # 3.

In such a case, in the present embodiment, section # 3 is divided into two, and a seventh-order function is determined for the divided sections in the same manner as in the first embodiment. FIG. 11 is a diagram illustrating an example of an electronic cam pattern after section division is performed. In FIG. 11, after the electronic cam pattern shown in FIG. 10 is generated, the above-described step S13 is performed for the section # 3. Thereby, section # 3 is divided into section # 3a and section # 3b. Any division method may be used, but in the example shown in FIG. 11, the original section is equally divided into two.

Since the value of the spindle position is small at the start of the section, the calculation error in the floating point calculation is smaller in the first half of the section than in the second half. Therefore, in the first half section # 3a among the divided sections, the function calculated for section # 3 is used by the method described in the first embodiment. In other words, the function F _3a of the section # 3a (k) is used as the same as F ₃ (k), it can be determined half the segment length of the section length of the section # 3, that as X _3/2. Thereby, the boundary conditions of section # 3a, that is, the slave shaft position and speed at the start position and end position can be determined.

Next, the function F _3b (X ₃ -k) of section # 3b which is the latter half section substitutes X ₃ -k instead of k for F ₃ (k), and the same boundary condition P2 as section # 3 And P3 are used to obtain the following equations (8) and (9). A0 'to A7' are coefficients.
F _3b (X ₃ −k) = A0 ′ + A1′k + A2′k ² + A3′k ³ + A4′k ⁴ + A5′k ⁵ + A6′k ⁶ + A7′k ⁷ (8)
A0 ′ = P3, A1 ′ = − V3, A2 ′ = 0, A3 ′ = 0,
A4 ′ = (20V3 + 15V2) / X ₃ ³ − (35P3-35P2) / X ₃ ⁴
A5 ′ = − (45V3 + 39V2) / X ₃ ⁴ + (84P3-84P2) / X ₃ ⁵
A6 ′ = (36V3 + 34V2) / X ₃ ⁵ − (70P3-70P2) / X ₃ ⁶
A7 ′ = − (10V3 + 10V2) / X ₃ ⁶ + (20P3-20P2) / X ₃ ⁷ (9)

The electronic cam pattern obtained by using this embodiment can reduce the calculation error at the time of floating point calculation as compared with the first embodiment. This is because the floating point arithmetic error may increase near the end position of the section due to the floating point arithmetic when calculated according to the equations (6) and (7) described in the first embodiment. In the latter half of the divided section, using the equations (8) and (9) to calculate the 7th order function from the end position to the start position, the vicinity of the end point is obtained. This is because the floating-point arithmetic error can be suppressed. In other words, in the electronic cam pattern generation method of the present embodiment, the step S13, which is the fourth step of setting a divided section by dividing a section, and the electronic cam pattern of the divided section for each divided section is the main shaft position. Step S4, which is a fifth step generated as a seventh-order function of the divided section, and the electronic cam pattern of the divided section including the end position of the section among the divided sections includes the end position of the divided section as a starting point. Calculated toward the starting position. As a result, when the calculation performance is low in the synchronous control system, for example, even when a double precision real number cannot be handled, the floating point calculation error can be suppressed and the impact and vibration on the mechanical device can be suppressed. In other words, in this embodiment, an electronic cam pattern based on a seventh-order function can be calculated with an inexpensive system.

Also, it is not necessary to equally divide the section into two when performing section division. For example, based on the error evaluated by the error evaluation unit 16, the error, that is, the portion before the floating point arithmetic error exceeds the threshold value, may be divided into two.

In the above example, the control device 1a has a function as an electronic cam pattern device that generates an electronic cam pattern. However, instead of the control device 1a, an electronic cam pattern device that generates an electronic cam pattern and a spindle You may provide the control apparatus which produces | generates the instruction | command with respect to the servo amplifier 2 based on a position and an electronic cam pattern.

The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1, 1a control device, 2 servo amplifier, 3 motor, 10, 10a electronic cam pattern generation unit, 11 section setting unit, 12, 12a pattern generation unit, 13 eigen waveform generation unit, 14 connection unit, 15 command generation unit, 16 Error evaluation unit, 100, 100a synchronous control system.

Claims

An electronic cam pattern generation method in a synchronous control system for controlling a slave shaft in synchronization with a spindle position,
A first step of setting a plurality of sections according to the spindle position;
A second step of setting boundary conditions for the plurality of sections;
A third step of generating an electronic cam pattern indicating the position of the driven shaft based on the boundary condition as a seventh-order function of the spindle position in at least one section of the plurality of sections;
An electronic cam pattern generation method comprising:
2. The electronic cam pattern generation method according to claim 1, wherein the boundary condition is a position, speed, acceleration, and jerk of a slave shaft at each of a start position and an end position of the section.
3. The electronic cam pattern generation method according to claim 2, wherein both the acceleration and the jerk in the boundary condition are zero.
A fourth step of dividing the section and setting a divided section;
A fifth step in which, for each divided section, the electronic cam pattern of the divided section is generated as a seventh-order function of the spindle position;
Including
The electronic cam pattern of the divided section including the end position of the section among the divided sections is calculated from the end position of the divided section toward the start position of the section. 3. The electronic cam pattern generation method according to 1 or 2.
5. The electronic cam pattern generation method according to claim 4, wherein the electronic cam pattern generation device determines whether or not to divide the section according to a calculation error when calculating the electronic cam pattern.
An electronic cam pattern generation device for generating an electronic cam pattern used in a synchronous control system for controlling a slave shaft in synchronization with a main shaft position,
A section setting unit that sets a plurality of sections according to the spindle position and sets boundary conditions for the plurality of sections;
A pattern generation unit that generates an electronic cam pattern indicating a position of the driven shaft based on the boundary condition as a seventh-order function of the spindle position in at least one of the plurality of sections;
An electronic cam pattern generation device comprising: