JP4882166B2 - Position synchronization controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a position synchronization control device that controls operation of a mechanically insulated drive unit at a predetermined conveyance ratio when an article is conveyed by combining two conveyance systems, and in particular, an electric motor The present invention relates to a position synchronization control device capable of performing synchronous position control with respect to a drive unit even if the gear ratio of a reduction gear connecting the drive device including the drive unit is not accurately known.
[0002]
[Prior art]
A control device that performs variable speed control of an induction motor and a synchronous motor is used in a production line of a factory that transports articles along a transport path. In particular, when a transport path is configured by combining a plurality of transport systems that are mechanically insulated from each other, it is necessary to select an optimal control method in order to control the position of each transport system.
[0003]
FIG. 6 is a diagram illustrating a system for transporting the article B by combining the two transport paths 10 and 20. This system is for example a synchro oscillator if it is a transport system that is not mechanically isolated from each other, i.e. a single transport system incorporating two or more drive units mechanically connected by a belt, chain or the like. In addition, synchronous speed control is possible using droop control or pulse train. At this time, one of the synchronous control methods is selected according to the accuracy of speed control required by the transport system and the necessary cost.
[0004]
On the other hand, unlike the conveyance system which is not mechanically insulated, when the two conveyance paths 10 and 20 constitute an independent conveyance system, the conveyance system is mechanically insulated. In this transport system, the synchronous speed control for adjusting the speed by combining them is performed using a synchro oscillator or a pulse train. In such a conveyance system, in order to designate the position of the article B to be transferred in the conveyance path within a predetermined range, not only the speed synchronous control as described above but also the positions of the mutual conveyance systems are synchronized. By controlling, the relative positional relationship in which the article B is delivered from one transport path to the other transport path must be precisely controlled.
[0005]
FIG. 7 shows a configuration for synchronous speed control of a mechanically insulated transport system. In this transport system, the speed is set by an external speed command value N for the drive unit 11 that drives the transport path 10, but the drive unit 11 for the drive unit 21 that drives the transport path 20. This is controlled by a synchronous speed command formed by passing the signal of the pulse encoder 13 attached to the machine shaft to the speed control circuit 22.
[0006]
Here, the speed control circuit 12 of the drive unit 11 includes a drive device 1, an electric motor M1, a reduction gear G1, and a pulse coder PG1. Similarly, the speed control circuit 22 of the drive unit 21 includes a drive device 2, an electric motor M2, a reduction gear G2, and a pulse coder PG2. The output pulse of the pulse encoder 13 is supplied to the speed control circuit 22 through the frequency divider 14 as a pulse having a frequency corresponding to the speed of the conveyance path 10. In the drive device 2 of the speed control circuit 22, the speed control of the drive unit 21 is performed so as to synchronize with the drive unit 11 by the frequency of the pulse train and the number of pulses.
[0007]
However, since the reduction gear G2 is interposed between the electric motor M2 and the drive unit 21, a positional deviation occurs during long-time operation. Therefore, when a reduction gear G2 different from the gear ratio of the reduction gear G1 is provided, a frequency divider 14 is provided to correct the speed command in the synchronous speed control, and these gear ratios are set accurately. It is possible to eliminate the positional deviation between the two transport paths 10 and 20.
[0008]
FIG. 8 shows a configuration for performing synchronous position control in a mechanically insulated transport system similar to that of FIG. Here, software control means 15 for correcting the gear ratio and a limit switch 17 for detecting the position of the conveyance path 20 are provided on the drive device 2 side. The software control means 15 sets the ratio based on the signal frequency-divided by the frequency divider 14, thereby enabling detailed position correction according to the gear ratio at the 32-bit level. Further, the initial position of the transport path 20 can be known by the limit switch 17.
[0009]
[Problems to be solved by the invention]
In the case of the synchronous speed control, the positional deviation does not become a problem in the system. However, in the case of performing the synchronous position control, various inconveniences occur if the article conveyance position is not fixed at the position shown in FIG. .
[0010]
In the conventional control system, a gear is interposed between the motor that drives each of the plurality of conveyance paths and the drive unit. Therefore, if the gear ratio of this gear is not accurately known, a frequency divider or software divider is used. Therefore, it is impossible to accurately control the synchronous position of the transport system. In addition, when the force of the electric motor is transmitted to the conveyance path by a slippery coupling means such as a V-belt, a shift occurs in the synchronous position during long-term operation. Further, when the drive unit is directly connected to the electric motor without using the reduction gear, the problem of the gear ratio is eliminated, but the capacity of the drive device is increased, resulting in an increase in cost.
[0011]
In addition, when using inexpensive gears that vary greatly with the design specifications, the gear ratio itself is not accurate, and it is necessary to find the exact gear ratio through operation tests and set the program. . It takes time and effort to set the gear ratio for all mechanical systems before shipment, such as when inexpensive gears are attached to mass-produced products, because such program setting takes time. There was a problem.
[0012]
An object of the present invention is to provide a position synchronization control apparatus capable of reducing the cost of a transport system and reducing adjustment elements and parts requiring maintenance.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, there is provided a position synchronization control device that controls the operation of a drive unit of each mechanically insulated transport system at a predetermined transport ratio when an article is transported by combining two transport systems. Is done. The position synchronization control device drives each drive unit via a reduction gear, and first and second drive means for controlling the synchronous speed by a ratio set value corresponding to the gear ratio of each reduction gear ; Output to the first and second drive means at the first and second timing detection means for detecting the conveyance timing of the article by each drive unit and the conveyance timing detected by the first and second timing detection means And a speed command value correcting unit that corrects a synchronous speed with respect to one of the driving units by calculating a position deviation of each of the driving units based on the speed command value.
Further, another position synchronization control device of the present invention includes first and second drive means for controlling the speed of each drive unit through a reduction gear, respectively, and a first timing for detecting an article conveyance timing by each of the drive units. The first and second timing detection means, and the drive units based on the speed command values output to the first and second drive means at the conveyance timing detected by the first and second timing detection means. And a speed command value correcting means for correcting the synchronous speed with respect to the one driving means by multiplying the calculated position deviation by the position control gain amount of the one driving means.
Furthermore, another position synchronization control device according to the present invention includes first and second driving means for controlling the respective synchronous speeds of the respective driving units via reduction gears, and a first timing for detecting an article conveyance timing by the respective driving units. The first and second timing detection means, and the drive units based on the speed command values output to the first and second drive means at the conveyance timing detected by the first and second timing detection means. And a speed command value correcting means for correcting the synchronous speed by adding an initial position correction amount in each driving unit to the calculated position deviation.
Furthermore, another position synchronization control device of the present invention detects first and second drive means for controlling the speed of each drive unit via a reduction gear, and the conveyance timing of an article by each drive unit. Each drive based on speed command values output to the first and second drive means at the transport timing detected by the first and second timing detection means and the first and second timing detection means And a speed command value correcting means for correcting a synchronous speed by adding a position offset amount due to a change with time in each driving section to the calculated position deviation.
[0014]
In this position synchronization control device, even if the gear ratio of the reduction gear connecting the drive device including the electric motor and the drive unit is not accurately known, the synchronous position control for the drive unit is possible.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a position synchronization control apparatus of the present invention.
[0016]
The two conveyance paths 10 and 20 constitute a conveyance system that is not mechanically insulated from each other. In this transport system, the speed of the drive unit 11 that drives the transport path 10 is set by a speed command value N1 from the outside. Further, the rotational speed signal of the electric motor M1 is input from the pulse coder PG1 to the driving device 2, and a positional deviation is calculated between the rotational speed signal from the pulse coder PG2 of the electric motor M2 and the driving unit 21 that drives the conveyance path 20 is operated. And synchronous speed control.
[0017]
The difference from the conventional position synchronization control device (FIG. 8) is that an incremental encoder (pulse encoder 13) attached to the drive unit 11 of the transport path 10 is not necessary. Further, not only the position detection signal (LS2) of the conveyance path 20 is input from the limit switch 17 to the driving device 2, but also the limit switch 16 is provided in the conveyance path 10 from which the position detection signal of the conveyance path 10 is provided. Another difference is that (LS1) is configured to be input to the driving device 2. These limit switches 16 and 17 are installed on the transport paths 10 and 20 so that they are simultaneously turned on when the article B to be transported reaches the boundary position between the transport path 10 and the transport path 20. That is, the limit switches 16 and 17 detect the conveyance timing of the articles by the driving units 11 and 21 by repeating ON and OFF in synchronization with the conveyance cycle of the articles B on the conveyance paths 10 and 20. 1 and 2 constitute a timing detection means.
[0018]
The electric motors M1 and M2 controlled by the driving devices 1 and 2 drive the driving units 11 and 21 via the reduction gears G1 and G2, respectively. The gear ratios of the reduction gears G1 and G2 are not accurate but are known. Under such system conditions, synchronous speed control can be performed by setting the gear ratio in advance.
[0019]
Further, the synchronous position control is performed so that the deviation of the position where the limit switches 16, 17 are turned on and off does not change with the passage of time. When the position deviation changes, the drive device 2 increases the speed setting value for the electric motor M2 in order to converge the change to zero.
[0020]
FIG. 2 is a diagram for explaining alignment of two transport systems by limit switches.
FIG. 4A shows the case where the article B transferred from the transport path 10 to the transport path 20 is displaced in the transport path 20. Here, the delimitation part of the stage of the conveyance paths 10 and 20 on which the article B is placed is detected by the signals LS1 and LS2 of the limit switches 16 and 17. The limit switches 16 and 17 are arranged so that LS1 and LS2 are simultaneously turned on. In the case of FIG. 5B, since the positions of the transport paths 10 and 20 are controlled so that LS1 and LS2 are turned on simultaneously, the positional deviation of the article B in the transport path 20 does not occur.
[0021]
FIG. 3 is a diagram for explaining the position deviation detected based on the limit switch signals LS1 and LS2.
When the LS1 and LS2 of the limit switches 16 and 17 provided on the transport paths 10 and 20 are turned on at the same timing, it is shown that synchronous position control without positional deviation is possible. In this way, when the machine adjustment is performed in advance so that the synchronization position of the transport system matches, the position synchronization control device controls the speed so that the limit switches 16 and 17 are turned on at the same time. Position synchronization control can be performed so that the position deviation of the paths 10 and 20 converges to zero.
[0022]
FIG. 4 is a block diagram showing a configuration of a speed command value correction circuit for performing the synchronous position control.
The position command signal θ1 from the pulse coder PG1, the position detection signal θ2 from the pulse coder PG2, and the digital signals LS1 and LS2 from the limit switches 16 and 17, respectively, are input to the interface circuit 31 of the speed command value correction circuit 30. Yes.
[0023]
The edge detection circuit 32 detects the rising timing of the digital signal LS1, and determines the timing for turning on and off the sample hold circuit 33 for the position command signal θ1 from the pulse coder PG1. Similarly, the edge detection circuit 34 detects the rising timing of the signal LS2, and determines the timing for turning on and off the sample hold circuit 35 for the position detection signal θ2.
[0024]
The position detection circuit 36 is connected to the edge detection circuit 32 and the sample hold circuit 33 and detects the position of the drive unit 1. Similarly, the position detection circuit 37 is connected to the edge detection circuit 34 and the sample hold circuit 35 to detect the position of the drive unit 2. These position detection signals θ1 and θ2 are input to a subtractor 38, and a positional deviation amount Δθ between the drive units 1 and 2 is obtained. The integration circuit 39 calculates a time integration value for each sampling of the positional deviation amount Δθ.
[0025]
The ratio setting circuit 40 is connected to the sample hold circuit 33 so that a speed setting signal for the driving apparatus 1 is input to determine the synchronization speed of the driving apparatus 2. Here, the gear ratios α: β, a: b of the reduction gears G1, G2 and the conveyance ratio m: n in the drive units 1 and 2 are set, and the synchronization speed N2 of the drive device 2 from the set speed N1 for the drive device 1 is set. Is determined by the following equation (1).
[0026]
[Expression 1]
N2 = N1 × (β / α) × (a / b) × (n / m) (1)
If the gear ratios α: β and a: b are accurate, the drive device 2 can be controlled at a position accurately synchronized with the synchronization speed N2. However, since there are actually differences between products, the position gradually shifts as the operation continues. Therefore, the interface circuit 31 of the speed command value correction circuit 30 is supplied with the signals LS1 and LS2 from the limit switches 16 and 17 that are turned on each time the driving units 1 and 2 are moved by one stage, respectively. Control is performed.
[0027]
In this synchronous position control device, the relative positional relationship between the transport paths 10 and 20 detected by the limit switches 16 and 17 may be unchanged. Here, the speed is controlled by mechanical adjustment in advance so that the signals LS1 and LS2 of the limit switches 16 and 17 are simultaneously turned on.
[0028]
FIG. 5 is a diagram for explaining the principle of speed correction of the speed command value correction circuit 30 for the drive device 2.
Now, it is assumed that the digital signals LS1 and LS2 from the limit switches 16 and 17 are input to the speed command value correction circuit 30 with a position deviation Δθ. At this time, the corrected speed command value for the driving device 2 is output as a value corrected by the magnitude of ΔN so that the positional deviation Δθ is 0, and then returns to the original magnitude.
[0029]
Therefore, the synchronization speed N2 shown in the equation (1) is input to the subtractor 41, the difference from the position detection signal θ2 is calculated, and integrated by the integration circuit 42, so that the synchronization speed N2 for the driving device 2 is corrected. The
[0030]
Further, the time integration value of the positional deviation amount Δθ is added by the adder 43, and the adder 44 adds the offset signal θoffset at the position determined by the offset adjustment circuit 45 in consideration of the temporal change of the mechanical system. The gain circuit 46 multiplies the output of the adder 44 by a position control gain (APR gain). In the gain circuit 47, the F / F gain is multiplied by the synchronous speed N2 shown in the equation (1). The outputs of these gain circuits 46 and 47 are added together by an adder 48 and output as a corrected speed command for the drive circuit 2.
[0031]
As described above, the synchronous position setting of the driving device 2 is based on the difference (position deviation) between the position command N2 corrected for the driving device 2 and the position detection amount (θ2) by the pulse coder PG2, the positional deviation amount Δθ and the initial position correction. Δθ0 is added and further multiplied by a position control gain (APR gain), which can be expressed as the following equation (2).
[0032]
Synchronous position setting of drive unit 2
[Expression 2]
= [Σ {θ1 × (β / α) · (a / b) · (n / m) −θ2} + Δθ0 + ΣΔθ] × (APR gain) (2)
Further, in the case where correction by the position offset signal θoffset is possible in consideration of the change over time of the mechanical system, the following equation (3) is obtained.
[0034]
Synchronized position setting of the drive unit 2
[Equation 3]
= [Σ {θ1 × (β / α) · (a / b) · (n / m) −θ2} + Δθ0 + θof fset + ΣΔθ] × (APR gain) (3)
Here, θ represents the number of pulse trains per sampling, and Σ represents time integration of the position for each sampling. Therefore, when realized by software, if the amount of ΣΔθ overflows, the synchronization alignment control becomes impossible, so normally it is held as a 64-bit variable. As a result, the correction can be performed almost infinitely.
[0036]
As described above, in the position synchronous control device of the present invention, when two articles that are mechanically insulated are combined to convey an article, the motors M1 and M2 are connected to the drive units 11 and 21. Even if the gear ratio of the existing reduction gears G1 and G2 is not accurately known, the limit switches 16 and 17 are provided as the first and second timing detection means for detecting the conveyance timing of the articles by the respective driving units. Synchronous position control can be performed.
[0037]
Further, unlike the conventional one in which an expensive detector such as an incremental encoder is provided in the drive units 11 and 21 of the transport system, using the speed control pulse coders PG1 and PG2 attached to the motors M1 and M2, Since the position synchronization control can be easily performed, it is possible to reduce the cost by reducing the adjustment elements and the parts requiring maintenance from the conventional transport system.
[0038]
Further, when a plurality of mechanically insulated transport systems are combined, synchronous position control between the driving device 1 and the driving device 2 is performed, and then synchronous position control between the driving device 2 and the driving device 3 is performed. Therefore, it is possible to easily expand a plurality of transfer systems by combining them one after another.
[0039]
Even if the gear ratios of the reduction gears G1 and G2 are not accurately known, or even when using inexpensive gears that have a large variation with respect to the design specifications, a troublesome ratio for each combined transport system Since it is not necessary to make settings, the cost of the transport system can be easily reduced.
[0040]
Furthermore, the provision of the offset adjustment circuit 45 has an advantage that costly maintenance is not required for a positional shift over time such as a shift in the synchronization position during a long-term operation.
[0041]
【Effect of the invention】
As described above, according to the position synchronization control apparatus of the present invention, when an article is conveyed by combining two conveyance systems, the cost of the conveyance system is reduced, and adjustment elements and parts required for maintenance are reduced. Since this is possible, it is possible to easily control the operation of the drive unit of each conveyance system that is mechanically insulated at a predetermined conveyance ratio.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a position synchronization control device of the present invention.
FIG. 2 is a diagram for explaining alignment of two transport systems by a limit switch.
FIG. 3 is a diagram for explaining a position deviation detected based on limit switch signals LS1 and LS2.
FIG. 4 is a block diagram showing a configuration of a speed command value correction circuit for performing synchronous position control.
FIG. 5 is a diagram illustrating a speed correction principle of a speed command value correction circuit for a driving device.
FIG. 6 is a diagram illustrating a system for transporting an article by combining two transport paths.
FIG. 7 is a diagram showing a configuration for performing synchronous speed control in a conventional mechanically insulated conveyance system.
FIG. 8 is a diagram showing a configuration for performing synchronous position control in a conventional mechanically insulated transfer system.
[Explanation of symbols]
1, 2 ... Drive device,
10, 20 ... conveying path,
11, 21 ... drive unit,
M1, M2 ... Electric motor,
PG1, PG2 ... Pulse coder,
G1, G2 ... reduction gear,
16, 17 ... limit switch,
30 ... Speed command value correction circuit

Claims (7)

In a position synchronous control device that controls the operation of a drive unit of each mechanically insulated transport system at a predetermined transport ratio when transporting an article by combining two transport systems,
First and second drive means for driving each drive unit via a reduction gear and controlling the synchronous speed by a ratio set value corresponding to the gear ratio of each reduction gear ;
First and second timing detection means for detecting the conveyance timing of the article by each of the driving units;
By calculating the positional deviation of each drive unit based on the speed command value output to the first and second drive means at the transport timing detected by the first and second timing detection means, Speed command value correcting means for correcting the synchronous speed with respect to the driving means;
A position synchronization control device comprising: In a position synchronous control device that controls the operation of a drive unit of each mechanically insulated transport system at a predetermined transport ratio when transporting an article by combining two transport systems,
First and second drive means for controlling the speed of each drive unit through respective reduction gears;
First and second timing detection means for detecting the conveyance timing of the article by each of the driving units;
Based on the speed command values output to the first and second drive means at the transport timing detected by the first and second timing detection means, the position deviation of each drive unit is calculated and calculated. by multiplying the position control gain of hand driving means to the position deviation, the speed command value correcting means for correcting the synchronous speed for said one of the drive means,
Position置同phase controller you comprising: a. In a position synchronous control device that controls the operation of a drive unit of each mechanically insulated transport system at a predetermined transport ratio when transporting an article by combining two transport systems,
First and second drive means for controlling the speed of each drive unit through respective reduction gears;
First and second timing detection means for detecting the conveyance timing of the article by each of the driving units;
Based on the speed command values output to the first and second drive means at the transport timing detected by the first and second timing detection means, the position deviation of each drive unit is calculated and calculated. A speed command value correcting means for correcting the synchronous speed by adding an initial position correction amount in each of the driving units to the position deviation ;
Position置同phase controller you comprising: a. In a position synchronous control device that controls the operation of a drive unit of each mechanically insulated transport system at a predetermined transport ratio when transporting an article by combining two transport systems,
First and second drive means for controlling the speed of each drive unit through respective reduction gears;
First and second timing detection means for detecting the conveyance timing of the article by each of the driving units;
Based on the speed command values output to the first and second drive means at the transport timing detected by the first and second timing detection means, the position deviation of each drive unit is calculated and calculated. A speed command value correcting means for correcting a synchronous speed by adding a position offset amount due to a change with time in each driving unit to the position deviation ;
Position置同phase controller you wherein Rukoto equipped with. Said first, second drive means, the position synchronization according to any one of 4 to claims 1, characterized in that performing the synchronous speed control by deviation from the synchronous speed command value by using each pulse encoder Control device.   A frequency divider having a ratio setting value according to the gear ratio of each reduction gear;
6. The position synchronization control apparatus according to claim 5, wherein the pulse encoder signal of said one drive means is divided and output to the other drive means.   5. The position synchronization control device according to claim 1, wherein the first and second timing detection means are limit switches provided in an article conveyance path of each drive unit.

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