JPH06301423A - Control system for multiple axes - Google Patents

Abstract

PURPOSE:To make a slave shaft follow up a main shaft in real time by finding a position command value of the slave shaft by using a cam curve where nondimensional positions of the main shaft and nondimensional positions of the slave shaft are made to correspond to each other. CONSTITUTION:A counter 54 counts pulses which are proportional to the quantity of rotation of the main shaft to detect the rotational position of the main shaft 30. A cam curve storage part 55 stores the cam curve which prescribes the relation between nondimensional positions of the main shaft 30 and nondimensional positions of the slave shaft 31. Data on the maximum count of the counter 54 assigned to the full scale of the nondimensional positions of the main shaft 30 and the quantity of rotation of the slave shaft 31 assigned to the full scale of the nondimensional positions of the slave shaft 31 are set in a data setter 56. The nondimensional positions of the main shaft 30 are made dimensional with the maximum count set in the counter 54 and the nondimensional positions of the slave shaft 31 are made dimensional with the actual quantity of rotation of the slave shaft 31. Then the position command value of the slave shaft 31 for following up the main shaft 30 is found by using the cam curve and the data for making the positions dimensional.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-axis control system for moving a slave shaft by following the movement of a main shaft.

[0002]

2. Description of the Related Art Devices for moving a slave shaft to follow the movement of a master shaft are used in many production machines. For example, it is used in a machine that operates a cutter for a chart sent at a constant speed at regular intervals and perforates the chart at regular intervals. In this machine, since the cutter operation is performed following the chart feed operation, the drive shaft of the chart feed roller serves as the main shaft, and the axis for operating the cutter serves as the slave shaft. Conventionally, a cam mechanism has been used as a device for moving the slave shaft by following the movement of the master shaft. An example of the cam mechanism is shown in FIG. In FIG. 9, 1 is a main shaft and 2 is a slave shaft. Reference numeral 3 is a motor for driving the main shaft 1, 4 is a worm-shaped cam fixed to the main shaft 1, and 5 is a groove formed in the cam 4 to form a worm shape. 6 is the slave shaft 2
The rotary table fixed to the rotary table 7 is a roller provided around the rotary table 6 and engaged with the groove 5. In such a device, when the main shaft 1 rotates, the rotational power is transmitted to the slave shaft 2 via the cam 4 and the roller 7, and the rotary table 6 is positioned. However, in a device that transmits power with a cam mechanism, if you want to change the tracking relationship between the main shaft and the slave shaft,
It is difficult to change the tracking relationship because the cam must be redesigned and manufactured. Further, when it is desired to increase the distance between the main shaft 1 and the slave shaft 2, the main shaft 1 must be lengthened, and the power transmission efficiency deteriorates due to twisting or bending of the shaft. Therefore, there is a problem that it is difficult to increase the distance.

As a device for solving such a problem, there is conventionally an electronic system in which servo motors are provided on the main shaft and the slave shaft, respectively, and the operations of these motors are controlled by a common controller. An example thereof is shown in FIG. In FIG. 10, 10 is a main shaft, and 11 and 12 are slave shafts. Reference numeral 13 is a motor for driving the main shaft 10, 14 is a rotation sensor for generating one pulse every one rotation of the motor 13, 15 and 16 are servomotors for respectively driving the slave shafts 11 and 12, and 17 and 18 are motors 15 respectively. And a servo driver for positioning the rotational positions of 16 and 19,
Is a rotation detection signal output from the rotation sensor 14 and is a start signal D
As a position command signal S ₁ to each servo driver 17 and 18
And S ₂ for the controller. A cam curve storage unit 20 stores a cam curve that gives a position command value.
The cam curve is, for example, a curve that represents a change with time of the motor position command value. A position command value and a time value are stored in the cam curve storage unit 8 in correspondence with a table format. The cam curve storage unit 8 stores a program for performing positioning control in addition to the table values of a plurality of types of cam curves.

The operation of such a system will be described. FIG. 11 is a time chart of each signal. The rotation amounts of the motors 15 and 16 of the slave shafts are set in advance in the controller 20, and the controller 20 knows the operating speed of the entire system from the interval of the start signal D, and the rotation time of the slave shaft is determined from the rotation amount and the operating speed. Decide Then, a cam curve that falls within the determined rotation time is selected, and the table value of the selected cam curve is given to the servo driver. As shown in the time charts of the position command signals S ₁ and S ₂ , various cam curves are used according to the interval of the start signal D.

However, this system has the following problems. That is, since the rotation time of the slave shaft is determined based on the interval between the time when the present start signal is generated and the time when the previous start signal is generated, the synchronization of the slave shaft with respect to the master shaft is always delayed by one block operation. Here, the block operation is an operation performed during the generation interval of the activation signal. Therefore, if the operating speed of the system fluctuates significantly, for example,
As indicated by the mark, the operation of the slave shaft may be inconsistent, and the slave shaft may miss the reaction by one block operation with respect to the master shaft. As a result, there is a problem that real-time tracking is not possible.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the conventional example at the same time, and the following relationship between the main shaft and the slave shaft can be easily changed, and the main shaft to the slave shaft can be easily changed. An object of the present invention is to realize a multi-axis control system in which a power transmission path can be easily lengthened and a slave shaft can follow a master shaft in real time.

[0007]

SUMMARY OF THE INVENTION The present invention is a multi-axis control system for moving a slave shaft by following the movement of the master shaft, outputting a number of pulses which are connected to the master shaft and are proportional to the amount of rotation of the master shaft. Encoder, the number of output pulses of this encoder is counted, the rotation position of the spindle is detected by the count, and the counter is reset when the maximum count is reached, the dimensionless position of the spindle and the dimensionless position of the slave axis. The cam curve storage unit that stores the cam curve that defines the relationship between, the maximum count of the counter assigned to the full-scale portion of the dimensionless position of the spindle, and the slave axis assigned to the full-scale portion of the dimensionless position of the slave axis. From the data setter in which the data of the rotation amount is set and the ratio of the count of the counter and the maximum count set in the data setter for each calculation cycle, The dimensionless position of the axis is determined, the dimensionless position of the slave axis corresponding to the dimensionless position of the determined master axis is read from the cam curve storage unit, and the dimensionless position of the slave axis read is set in the data setter. A calculation unit that determines the position command value of the slave axis from the dimensioned value and the slave unit position command value calculated by this calculation unit is given. A multi-axis control system, comprising: a motor control unit that originally controls a rotational position of a drive motor for a driven shaft.

[0008]

In the present invention as described above, the follow-up relationship between the main shaft and the slave shaft is determined by the cam curve which defines the relationship between the dimensionless position of the main shaft and the dimensionless position of the slave shaft. The dimensionless conversion of the dimensionless position of the main axis is
The maximum count is set in the counter that measures the rotational position of the spindle. The dimensionlessization of the dimensionless position of the slave axis is
The actual rotation amount of the slave shaft is used. Then, the position command value of the slave axis for following the movement of the master axis is obtained using the cam curve in which the dimensionless positions correspond to each other and the data for dimensioning.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram showing an embodiment of the present invention. In FIG. 1, 30 is a main shaft and 31 is a slave shaft. Reference numeral 32 is an encoder that is connected to the main shaft 30 and outputs an encoder pulse P ₁ having a pulse number proportional to the rotation amount of the main shaft 30, 33 is a motor that drives the slave shaft 31, and 34 is an encoder that detects the rotation of the motor 33. is there. Reference numeral 40 is a servo driver that feedback-controls the rotation of the motor 33, 50 is a command value generation unit that generates a command value to be given to the servo driver, 70 is a sequencer that gives data used for command value calculation to the command value generation unit 50, and 80 is a cam. A cam curve generation unit that generates a curve and transfers the generated cam curve table value to the command value generation unit 50 via the communication line 81 such as RS232C.

In the command value generator 50, 51 is a position finger.
The CPU 52 that controls the calculation of the command value and the generation of the command value
RO that stores the program for calculating the command value
M and 53 are RAs that store data and variables necessary for calculation
M and 54 are encoder pulses P ₁Counting the number of pulses
It is a counter that does. 55 is a tune that remembers the cam curve
It is a line storage unit. The cam stored in the cam curve storage unit 55
The curve shows the relationship between the dimensionless position of the main axis and the dimensionless position of the slave axis.
It is a defined cam curve. Figure 2 shows an example of a cam curve
You The cam curve storage unit 55 stores the value of the dimensionless position of the spindle.
The value of the dimensionless position of the slave axis is stored in correspondence with the table format.
Has been done. This kind of cam curve is from cam curve 1
Multiple types up to the curve n are prepared. 56 is data setting
And a dimensionless function stored in the cam curve storage unit 55.
Stores data for making the dimension curve dimensional.
This data includes the range of 0 to 1 of the dimensionless position of the main axis and
Data assigned to the 0 to 1 range of the dimensionless position of the axis
It The setting data for the data setter 56 is the sequencer 7
0 to DI / DO interface (data input / data
Output interface) 57. 58 is
Table value of the cam curve generated by the cam curve generation unit 80
Is a cam curve buffer for temporary storage. Temporary storage
The generated table value is stored in the cam curve storage unit 55.
59 connects the communication line 81 to the cam curve buffer 58
It is a communication interface. 60 is calculated by the CPU 51
Command to output the position command value under the control of CPU 51
Value output circuit, 61 is the position output by the command value output circuit 60
Subtraction that takes the deviation between the command value and the position detection value of encoder 24
And 62 is the motor rotation based on the deviation obtained by the subtractor 61.
Outputs control signal for feedback control of rolling position
It is a position control unit.

The cam curve generator 80 uses the CAD function of a general-purpose computer such as a personal computer to plot the points through which the cam curve passes on the display screen and generate a cam curve of arbitrary shape. The specific configuration of the cam curve generator 80 is as follows.
For example, it is described in the application specification of Japanese Patent Application No. 3-65083 by the present applicant. In addition, R is stored in the cam curve storage unit 55.
It is also possible to provide an AM and a ROM, store the cam curve of an arbitrary shape generated by the cam curve generation unit 80 in the RAM, and store the standardized cam curve in the ROM.

In the servo driver 40, 41 is an F / V converter for obtaining a speed detection signal from the detection signal of the encoder 34, and 42 is a speed command value given by the output of the position control section 62 and given from the F / V converter 41. A subtractor 43 that takes the deviation of the detected speed value is a speed controller that outputs a control signal for feedback controlling the rotation speed of the motor based on the deviation taken by the subtractor 42. 44 is a current detection circuit for detecting the current flowing through the coil of the motor 33,
Reference numeral 45 is a subtracter that takes the deviation between the output of the speed control unit 43 and the output of the current detection circuit 44, and 46 is the torque control by controlling the current flowing through the coil of the motor 33 based on the deviation taken by the subtractor 45. The current control unit 47 is a drive circuit that receives the output of the current control unit 47 and supplies an exciting current to the coil of the motor 33.

FIG. 3 is a block diagram of the essential parts of the system of FIG. In FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals. Hereinafter, the same applies in the drawings. Reference numeral 511 is a command value calculation means provided in the CPU 51 and performing a calculation for obtaining a position command value. Prior to the position control, the cam curve storage unit 55
The cam curve is stored in. In addition, the data setter 5
In 6, the maximum count C _max and the rotation amount S _C are set. The maximum count C _max is the maximum count of the counter 54 and is a value assigned to the range of 0 to 1 of the dimensionless position of the spindle on the cam curve. The counter 54 counts up each time the encoder pulse P ₁ is received, and is reset when the count reaches the maximum count C _max , and the count becomes 0.
become. The count of the counter 54 corresponds to the detected rotational position of the spindle. The rotation amount S _C is the actual rotation amount of the slave shaft, and is a value assigned to the range of 0 to 1 of the dimensionless position of the slave shaft on the cam curve.

The command value calculation means 511 calculates the slave shaft position command value by performing the following calculation for each calculation cycle. The dimensionless position t _i of the main axis is obtained from the following equation. t _i = C _i / C _max C _i : Count of counter 54 in the current calculation cycle The dimensionless position s (t _i ) of the slave axis corresponding to the dimensionless position t _i of the master axis is obtained from the cam curve. Based on the difference between the previous dimensionless position s of the follower shaft in operation period (t _i-1) and the non-dimensional position s of the follower shaft in the current computation cycle (t _i), in the current calculation cycle from the following equation The position command value P _outi of the slave axis is _calculated . P _outi = S _C {s (t _i ) −s (t _i−1 )}

FIG. 4 is a flow chart showing the procedure for calculating the position command value. The process shown in FIG. 4 is performed every calculation cycle. 4, when the count C _i of the counter 54 is input, and compares the count C _i-1 in the count C _i and the previous operation cycle in the current calculation cycle at decision A1. If the comparison result is C _i ≧ C _i−1 , the counter 5
4 has not been reset. In this case, the position command value is obtained in the same manner as described above. If the comparison result is C _i <C _i−1 , the counter 54 is reset between the previous calculation cycle and the current calculation cycle. In this case, the number of encoder pulses generated from the count input time to the counter reset time in the previous calculation cycle is calculated. The number of pulses corresponds to the amount of rotation of the spindle between the count input time and the counter reset time in the previous calculation cycle. This rotation amount P _out1 is calculated by the following equation. P _out1 = S _C {s (1) -s (t _i-1 )} Next, C _max and S _C are refreshed. Then, the dimensionless position t _{i of the} main axis and the dimensionless position s (t _i ) of the slave axis are obtained in the same manner as in the case where the new set value is not reset. Then, the slave shaft position command value P _outi is calculated by the following equation. P _outi = S _C {s (t _i ) −s (0)} + P _out1 The first term on the right-hand side of the above equation is the rotational position of the slave shaft from the reset time of the counter to the count input time in the current calculation cycle. Is the change amount of. The amount of change is calculated based on the time of resetting because the values of C _max and S _C are refreshed by resetting. The position command value thus obtained is output to drive the slave shaft.

The cam curve may be a combination of a plurality of types of cam curves in the range of 0 to 1 at the non-dimensional position. An example of such a cam curve is shown in FIG. In the cam curve of FIG. 5, different types of cam curves are used in the ranges of M ₁ , M ₂ , and M ₃ . By connecting multiple types of cam curves, the movement of the slave shaft can be finely controlled, and the followability of the slave shaft can be made closer to the cam mechanism.

Further, the cam curve may have a decreasing portion. An example of such a cam curve is shown in FIG.
In FIG. 6, the range of 0 to 1 of the slave shaft corresponds to the rotation amount P _C.
When this cam curve is used, the slave shaft makes a normal rotation by P _C as shown in FIG. 7, and then moves back by P _{C in} the original position. By using a cam curve having a decreasing portion, it is possible to cause the slave shaft to perform both normal rotation and reverse rotation even if the main shaft performs only normal rotation.

[0018]

According to the present invention, the following effects can be obtained. Since the position command value of the slave shaft is obtained by using the cam curve in which the dimensionless position of the spindle and the dimensionless position of the slave shaft are obtained, the rotation time of the slave shaft as in the conventional example of FIG. 10 is obtained. No need. That is, in the present invention, the cam curve is such that the positions of the main shaft and the slave shaft are directly associated with each other without providing a time axis. As a result, the slave shaft can be made to follow the master shaft in real time, and the same followability as the cam mechanism can be obtained. In the conventional example of FIG. 9, when it is desired to increase the distance between the main shaft and the slave shaft, the main shaft must be lengthened, and thus it is difficult to increase the distance. On the other hand, in the present invention, since the movement of the main shaft is transmitted by the encoder pulse as shown in FIG. 8, the distance from the main shaft to the slave shaft can be easily increased by lengthening the encoder signal line 35. The follow-up relationship between the main shaft and the slave shaft is defined by an electronic cam curve. The cam curve can be easily changed by rewriting the table value. Therefore, the follow-up relationship between the main shaft and the slave shaft can be easily changed as compared with the cam mechanism.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a cam curve used in the system according to the present invention.

3 is a main part configuration diagram of the system of FIG. 1. FIG.

FIG. 4 is a flowchart showing an operation procedure of the system of FIG.

FIG. 5 is a diagram showing another example of a cam curve used in the system according to the present invention.

FIG. 6 is a diagram showing another example of a cam curve used in the system according to the present invention.

7 is a diagram showing a rotational position of a driven shaft that moves according to the cam curve of FIG.

FIG. 8 is an explanatory diagram of a transmission path in the system of FIG.

FIG. 9 is a diagram showing a configuration example of a conventional cam mechanism.

FIG. 10 is a diagram showing a configuration example of a conventional multi-axis control system.

11 is a time chart of signals in the system of FIG.

[Explanation of symbols]

 30 spindle 31 slave axis 32, 34 encoder 33 motor 40 servo driver 50 command value generation unit 51 CPU 511 command value calculation means 54 counter 55 cam curve storage unit 56 data setter 62 position control unit

Claims (1)

[Claims] 1. In a multi-axis control system for moving a slave shaft to follow the movement of the master shaft, an encoder connected to the master shaft, which outputs a number of pulses proportional to the amount of rotation of the master shaft, and an output of this encoder. Count the number of pulses,
A cam curve storage unit that stores the cam curve that defines the relationship between the dimensionless position of the spindle and the counter that is reset when the rotational position of the spindle is detected by counting and the maximum count is reached. And a data setter in which the maximum count of the counter assigned to the full scale of the dimensionless position of the spindle and the rotation amount data of the slave axis assigned to the full scale of the dimensionless position of the slave axis are set, and the operation cycle For each time, the dimensionless position of the spindle is obtained from the ratio of the count of the counter and the maximum count set in the data setting device, and the dimensionless position of the slave axis corresponding to the dimensionless position of the determined spindle is stored in the cam curve storage unit. The dimensionless position of the slave axis is read out from the data setter and the slave axis position command is made from the dimensioned value. And a motor control unit that receives the position command value of the slave axis calculated by this calculation unit and controls the rotational position of the drive motor for the slave shaft based on the position command value provided. A multi-axis control system characterized by being provided.