JP2002019948A - Control device for carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly carry a workpiece to a precise position. SOLUTION: A load applied on a motor 42A for a first lift part 40A radically increases at the time when a slide member 70 moves to the first lift part 40A (2) and a workpiece holding part 80 holds the workpiece W. Additionally, a load of a motor 42B for a second lift part 40B radically increases at the time when the slide member 70 moves to the second lift part 40B (4). The carrier part 70 is smoothly elevated by maintaining synchronism of the first and second motors by adding an acceleration control part to a position and speed control part against such radical load variation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a transfer device for transferring a workpiece.

[0002]

2. Description of the Related Art For example, a device as shown in FIG. 2 is known as a transfer device for transferring a workpiece located between a first position and a second position separated in a transfer direction. This device is suitable for the first
A base portion 35B disposed between the first position and the second position, a first lift portion 40A provided at one end of the base portion 35B and having a first motor 42A, and a second motor 42B provided at the other end of the base portion. A second lift portion 40B comprising:
The first motor 42A of the first lift unit 40A and the second motor 42A
Servo control means for controlling the second motor 42B of the lift section 40B, a transport section 60 which is moved up and down by the two sets of lift sections, and provided in the transport section 60 to move in a direction parallel to the workpiece transport direction. The workpiece W is transported from the workpiece transport position at the first position to the workpiece transport position at the second position. FIG. 11 is a servo block diagram of a motor for controlling the first motor 42A of the first lift unit 40A and the second motor 42B of the second lift unit 40B of the transfer device. In FIG. 11, 200A is a first motor 42 of the first lift portion 40A.
A shows a control block of A, and 200B shows a control block of the second motor 42B of the second lift section 40B. The block diagrams for the first motor 42A and the second motor 42B have exactly the same configuration, and include a position control unit 202 for correcting a difference between a position command and a current value, and correcting a difference between a speed command and an actual speed value. Speed control unit 204, a current control unit 206 that corrects the difference between the current command and the actual current value, and a rotation drive motor unit 208.

In such a servo system, a slide member 70 for transporting the workpiece is located at the right end, and the first lift section 40A and the second lift section 40B are lifted to move the workpiece W.
Is held at the moment, a sudden load is applied to the first motor 42A of the first lift unit 40A. (FIG. 10D) Next, the load on the first motor 42A of the first lift unit 40A is reduced by moving the workpiece to the left transport end while holding the workpiece W. ((D) of FIG. 10) Conversely, the second motor 42 of the second lift portion 40B
B is in a load state completely opposite to that of the first motor 42A of the first lift section 40A. (E in FIG. 10) In order to prevent such a sudden change, in the conventional servo system of this type, the first motor 42A and the second motor 42A are used.
For the load fluctuation B, the servo gain of the position control unit 202 and the speed control unit 204 shown in FIG. 11 is changed according to the presence or absence of the workpiece W and the position of the slide member 70 for transporting the workpiece. (Parts indicated by arrows) have suppressed load fluctuations.

[0004]

However, the means for suppressing the load fluctuation by changing the servo gain of the position control unit 202 or the speed control unit 204 implemented in the transport control device has the following problems. is there. Fig. 11, 20
This will be described with reference to a servo block diagram of 0A. Load fluctuations depending on the presence or absence of the workpiece W and the position of the slide member 70 that transports the workpiece W enter the servo system as an external torque 210 (thick line). The external torque 210 is controlled by the position control unit 202, the speed control unit 204, and the current control unit 20.
The motor 208 acts as a negative torque with respect to the target torque output from the motor via the motor 6, and changes the acceleration, speed, and position of the motor 208. The change in position becomes an actual position feedback value as it is, and the position control unit calculates the target position command value from a higher order and compensates for the position. The position variation is also differentiated and converted into an actual speed feedback value, and the speed control unit calculates the target speed command value output from the position control unit and performs speed compensation. However, in the compensation system of these position / speed control units, the processing time is slow, and the sudden change in load depending on the presence or absence of the workpiece W and the position of the slide member 70 for transporting the workpiece cannot be compensated at high speed, and the phase lag cannot be achieved. And the displacement of the lift portion, the vibration during the operation of the slide member 70, and the like were generated.

[0005] The current control section 206 shows the actual current flowing in each of the first motor 42A for driving the first lift section 40A and the second motor 42B for driving the second lift section 40B in the transport control device. It is necessary to use the current detectors 140a and 140b and the A / D converter 128 as shown by a broken line in the servo control unit (main) 102A of No. 4 to measure. However, these components may cause a decrease in the reliability of the servo system due to a failure or disconnection of the wiring. In addition, parts and wiring materials and their production / adjustment, etc., cause a cost increase.

Further, even if the first motor of the first lift section and the second motor of the second lift section are synchronously operated, a synchronous deviation occurs for some reason, and the slide member section interferes with a work or the like. The transport device may be damaged.

Further, if the slide member portion interferes with the work or the like due to the synchronization shift and the transport device is damaged, it is difficult to manually and visually return the transport device because the mechanism is complicated even if the transport device is modified. However, a return operation depending on the worker's feeling may cause a secondary disaster.

[0008]

According to the first aspect of the present invention, there is provided servo control means for controlling a first motor of the first lift section and a second motor of the second lift section. And an acceleration control unit in place of the conventional current control unit in addition to the position control unit and the speed control unit.

According to the invention of claim 2 of the present invention, the acceleration control unit estimates the disturbance torque and the actual current applied to the motor using an observer function without using an acceleration detector and a current detector. An actual acceleration is calculated using the estimated value, and the calculated actual acceleration is fed back to an acceleration command output from a higher-order speed control unit to perform acceleration control.

According to a third aspect of the present invention, a means for monitoring a deviation amount of each of the first motor and the second motor and an allowable range of a difference between the positional deviation amounts are set. Means for outputting an alarm immediately when the difference between the positional deviation amounts exceeds the allowable range.

According to a fourth aspect of the present invention, when the synchronism between the first motor and the second motor is broken and an emergency stop is operated in response to the alarm from the alarm output means, an abnormal When a return command is input from the outside through an operation panel or the like after the cause is removed, the current position information of the first motor and the second motor is read, and the first and second motors in which the position deviation amount largely remains are read. An automatic return control means for automatically returning the current position of the other motor to the current position of one of the motors is further provided.

[0012]

According to the first aspect of the present invention, abrupt load fluctuations, variations in the weight of the work, and aging and temperature changes of the transfer device directly enter the acceleration control section as disturbance torque. High-speed correction with small delay can be performed.

According to the second aspect of the present invention, since the actual current value and the disturbance torque can be estimated by the observer function, the actual acceleration can be calculated only by the arithmetic processing.

According to the third aspect of the present invention, the position deviation amount is constantly monitored, and the difference between the position deviation amounts is compared with an allowable range. An alarm is output.

According to the invention of claim 4 of the present invention, since the current position of the motor having a large positional deviation amount is automatically returned as the target position, the operation is performed so that the current positions of both motors have the same value. Is done.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a production line using a transfer device using the control device of the present invention.
Processing stations MA, MB, and MC are arranged between the conveyor 20C for loading and unloading the workpiece W, and the conveyor 20C for loading the workpiece W and the processing station M.
A, MB, MC, between the conveyor 30C for unloading, between the conveyors 10A, 10B, 10C, 10C according to an embodiment of the present invention
D, is located. The transfer device 10A transfers the workpiece W from the carry-in conveyor 20C to the processing station MA. Similarly, the transfer device 10B sequentially transfers the workpiece W from the processing station MA to the processing station MB. The transfer operations of these transfer devices 10A to 10D are performed simultaneously.

Next, the structure of the single transfer apparatus shown in FIG. 1 will be described with reference to FIG. This equipment is a processing station that is separated in the transport direction
A base portion 35B disposed between a first position on the MA and a second position on the processing station MB; and a first lift portion 4 provided at one end of the base portion 35B and having a first motor 42A.
0A and a second motor 42 provided at the other end of the base portion.
B, a second lifting unit 40B including the first and second lifting units, a transporting unit 60 that is moved up and down by the two sets of lifting units, a slide member 70 provided in the transporting unit 60 and moving in a direction parallel to the workpiece transport direction, and a slide member. Third motor 90 for driving the motor 70
And a workpiece holding section 80.

Next, the transport operation by the transport device shown in FIG. 1 will be described with reference to FIGS. FIG. 2 shows the transfer operation of the transfer device, and FIG.
Indicates the transport operation trajectory at this time. Transfer device 10B
Is waiting at the initial position shown in the figure until the processing at the processing station MA in the previous process is completed. Then, the third motor 90 is driven to move the workpiece holding unit 80 rightward in accordance with the timing of the end of the machining at the machining station MA in the preceding process, and the slide member 70 is moved from the machining position of the machining station MA in the preceding process. Send to Thereafter, the transport unit 60 is raised by synchronously controlling the first and second motors 42A and 42B, the workpiece W is placed on the workpiece holding unit 80, and the workpiece W is further raised to the rising end position shown below. After that, the third motor 90 is driven to move the slide member 70 and the workpiece holding unit 80 to the left, and as shown by the arrow, is sent to the processing position of the processing station MB in the next process. Then, the first and second motors 42A, 4A,
2B is synchronously controlled to lower the transfer unit 60, leaving the workpiece W on the jig of the processing station MB and lowering it to a further position. Thereafter, the third motor 90 is driven to move the workpiece holder 80 rightward, and returns to the initial position shown in FIG.

Here, the transport section 60 includes a pair of lift sections 4.
Although it is supported by 0A and 40B, the overhang from the lift portions 40A and 40B becomes large at the positions indicated by and in FIG. For this reason, the lift 4
The load on the first motor 42A at 0A and the load on the second motor 42B at the lift section 40B are significantly different. This load change is shown in FIG.
This will be described with reference to the timing chart of FIG. At the right end position (timing t1) shown in FIG. 2, the first and second motors 42A and 42B start rotating to raise the transport unit 60, hold the workpiece W by the workpiece holding unit 80, and further The rotation is stopped at the timing of rising (timing t4). Here, when the workpiece W is held, the load on the first motor 42A of the lift unit 40A sharply increases. (FIG. 4. (D)) Then, as shown in FIG. 2, while the transport unit 60 is fed from the right end to the left end, the first motor 42A
Load gradually decreases. (FIG. 4. (D)) The load on the second motor 42B is reversed. (FIG. 4E)

FIG. 4 is a servo configuration diagram used for an NC or the like according to the present invention. This servo system includes a pulse distribution unit 100 that mainly performs pulse distribution and monitoring, and position interpolation, position command value generation, and position / velocity /
It is roughly constructed of servo control units 102A and 102B that perform current control. (The servo control unit is also used for the first motor
The motor configuration has exactly the same configuration. )

The pulse distribution unit 100 includes a host CPU 110
ROM 112 containing the operation program,
BRAM for storing external data and parameters
(Backup RAM) 114 and I / F for communication with the outside
(Interface) 108 and 116. Also, a sequence controller (hereinafter, PLC) 104
Gives external commands to the host CPU 110, such as emergency stop, operation preparation, and cycle start. The console 106 inputs an index point, a speed command value, and the like to the host CPU 110 through the communication I / F 108.

Next, the servo control units 102A and 102B
Communication I for receiving various data from pulse distribution unit 100
/ F118A, (servo control unit (sub) is communication I / F1
18B), a control CPU 120 for performing position interpolation / position command value generation and position control, a built-in ROM 122 containing an operation program for the CPU 120, and a DSP (digital signal processor) 1 for controlling acceleration.
24, and an inverter 126 that generates a rotating magnetic field vector for the motor 142. Inverter 1
The motor 142 is rotated by the current output from the motor 26.

Next, a state quantity estimation observer 4 will be described with reference to FIG.
02 will be described. The inside of the above frame is the actual machine 400, and the following frame is the state quantity estimation observer 402 configured using the actual machine 400 as a model. First, the symbols used in the block diagram of FIG. 6 will be described. Vu
404 is the input voltage value to the motor, Ke 406 is the back electromotive force constant of the motor, R408 is the armature resistance value of the motor, L4
10 is the motor inductance, S412 is the Laplace operator (differential), Iq414 is the actual current value, Kt416 is the torque constant of the motor, T418 is the disturbance torque, J420.
Is the load inertia, D422 is the viscous resistance of the motor, ω
m424 is the actual rotation speed of the motor.

The state quantity estimation observer 402
The following operation is realized by software in SP124. Physical quantities that can be detected in configuring the state quantity estimation observer 402 are a voltage command Vu404 to the motor and an actual rotation speed ωm424. The following two equations are derived from the actual machine 400 in FIG.

(Equation 1)

(Equation 2) The following equation of state is obtained from equations (1) and (2).

[0025]

(Equation 3)

(Equation 4) The state quantity estimation observer 402 in FIG. 6 sets the state quantity vector on the left side of the above equation (3) to Xhat (here, hat means an estimated value, and Xhat means Tlhat, ωmhat, Iqhat), and the right side. Is represented by an A matrix 432, a second matrix is a B matrix 426, and a first matrix on the right side of the following equation (4) is a C matrix 434. K428 is a parameter called an observer gain. The estimated state quantity Xhat 438 is derived by solving the state quantity estimation observer 402 in FIG. Using the derived Tlhat and Iqhat, the acceleration is obtained from the following equation.

(Equation 5) This αr is an acceleration command αr * which is an output from the speed command.
To form acceleration control. This servo block diagram using the acceleration control is shown in FIGS. As described above, the servo block includes the position control unit 304, the speed control unit 306, and the acceleration control unit 308. Since the estimated state quantity Xhat 438 is realized by software, it is of course discretized and calculated for each control cycle.

Next, the axis shift detecting process executed by the host CPU 110 according to the flowchart shown in FIG. 7 will be described. First, in the axis deviation detection processing, in step 500, the axis deviation between the first motor and the second motor of the lift section is checked based on the difference between the positional deviations of the respective motors. Then step 5
At 02, it is monitored whether the difference is within a preset allowable range. If it is within the permissible range, the operation is continued as it is. If it is out of the permissible range, an axis deviation alarm is output in step 504, and the subsequent axis deviation amounts of the first motor and the second motor are stored in step 506. Display that number.

Next, the axis shift correction control executed by the host CPU 110 will be described with reference to FIG. Step 60
If it is 0, it is checked whether or not an axis shift correction control request is included from an external command. This request is sent to the sequence controller 1
When an axis shift correction control request is received from an external command input by the operator in step 04, the process proceeds to step 602 and the current positions of the first motor and the second motor are read. Step 604
Then, the final command value before the axis shift correction control is obtained. In step 606, the difference between the final command value and the current position of the first motor and the second motor is calculated. In step 608, the current position of the motor with the larger difference is set as the reference position for automatic return. In step 610, a fixed amount correction is performed. In step 612, it is checked whether the current positions of the first motor and the second motor match, and if they match, an axis shift correction completion signal is output in step 614.

[0028]

[Other Embodiments] In the servo block diagram of FIG. 4, the drawing is divided into a pulse distribution unit and a servo control unit to perform processing, respectively.
The functions of the DSP 10 and the DSP 124 can be realized only by the host CPU 110. Although the acceleration control according to the present invention is realized using an observer for estimating a current and a disturbance torque, the present invention is not limited to this, and can be realized using an acceleration detector. The acceleration control according to the present invention is realized by using the observer for estimating the current and the disturbance torque. However, the present invention is not limited to this, and the acceleration control can be realized by using the actual current using the current detector. Although the acceleration control of the present invention is realized by using an observer for estimating a current and a disturbance torque, the present invention is not limited to this. This can be realized even if the electromotive force constant is corrected by using a table based on temperature or the like and correcting the parameters. Further, since the inertia also has a slow time constant, it can be realized even if the control is divided into several tables.

[0029]

According to the first aspect of the present invention, since acceleration control is provided in addition to the position control unit and the speed control unit, displacement of the lift unit, vibration during operation of the slide member, and the like can be reduced. Can be suppressed.

According to the second aspect of the present invention, the disturbance torque applied to the motor and the actual current are estimated by using the observer function. Current detectors and A that can increase costs due to
The parts such as the / D converter are eliminated as much as possible, and the reliability can be improved and the cost can be reduced.

According to the third aspect of the present invention, the means for monitoring the amount of deviation between the respective positions of the first motor and the second motor, and the means for setting the allowable range of the difference between the amount of positional deviation. And, when the difference between the positional deviation amount exceeds the allowable range, the alarm output means that outputs an alarm immediately, so that even if a positional deviation or the like occurs for some reason, the slide member portion and the workpiece etc. A warning can be issued and the transfer device stopped before the interference and damage to the transfer device.

Further, according to the invention of claim 4 of the present invention, an automatic return for automatically returning the current position of one of the first and second motors to the current position of one of the first and second motors where a large amount of positional deviation remains. Since the control means is provided, in the case where a position shift or the like occurs due to some cause and a warning of the abnormality of the transfer device is issued and an emergency stop is performed, the transfer device can be easily and automatically returned to a safe position after removing the cause of the abnormality.

[0033]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a production line using a transfer device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a transport operation by a transport device.

FIG. 3 is a diagram showing a trajectory of a transfer operation by the transfer device.

FIG. 4 is a servo configuration diagram according to a specific embodiment of the present invention.

FIG. 5 is a control block diagram according to a specific example of the present invention.

FIG. 6 is a specific state quantity estimation observer block diagram of the present invention.

FIG. 7 is a flowchart of an axis shift detection process.

FIG. 8 is a detailed flowchart of axis shift correction control.

FIG. 9 is a timing chart showing speed / load fluctuations of each motor in conventional control.

FIG. 10 is a control block diagram according to the related art.

[Explanation of symbols]

 10A, 10B, 10C, 10D ... Conveyor 20C, 30C ... Conveyor MA, MB, MC ... Processing station 35B ... Base 40A, 40B ... Lift 42A ... First motor (for lift) 42B ... Second motor (for lift) Reference numeral 60: transport unit 70: slide member 80: workpiece holding member 90: third motor (for transport) 100: pulse distribution unit 102A: servo control unit (main) 102B: servo control unit (sub) 104: can controller ( PLC) 106 Console (small operation panel) 108, 116, 118A, 118B Communication I / F 110 Host CPU 112 ROM 114 BRAM 124 Control CPU 122 CPU ROM 124 DSP (Digital Signal Processor) 126… Inverter (for MOSFET That the PWM control) 128 ... A / D converter (the invention not required for) 140a, 140b ... current detector (not required in the present invention) 142 ... servomotor 144 ... motorized electromagnetic brake 146 ... encoder (position detector)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) JJ09 KK11 KK18 KK19 LL03

Claims (4)

[Claims] 1. A base unit disposed between a first position and a second position separated in a transport direction, a first lift unit provided at one end of the base unit and having a first motor, and the base unit A second lift unit provided at the other end of the first lift unit and having a second motor; servo control means for controlling a first motor of the first lift unit and a second motor of the second lift unit; A transport unit that is moved up and down by the unit, and a slide member that is provided in the transport unit and moves in a direction parallel to the workpiece transport direction.
In a transfer device for transferring a workpiece to a position, the servo control means may cause a sudden change in load on the first and second motors which varies depending on a transfer position of the slide member, a variation in work weight, and an aging of the transfer device. A control device for a transport device, wherein the servo control means is provided with robustness by performing acceleration control in addition to a position control unit and a speed control unit with respect to a temperature change. 2. The servo control means comprises an acceleration control unit in addition to a position control unit and a speed control unit. The acceleration control unit uses an observer function without using an acceleration detector and a current detector. Estimating a disturbance torque and an actual current applied to a motor, calculating an actual acceleration using the estimated value, and feeding back the calculated actual acceleration to an acceleration command output from a higher-order speed control unit to perform acceleration control. The control device for a transfer device according to claim 1, wherein: 3. A control device for a transfer device according to claim 1, wherein said first motor and said second motor monitor a position deviation amount of each of said first and second motors, and a permissible range of a difference between said position deviation amounts. And a warning output means for outputting a warning immediately when the difference between the positional deviation amounts exceeds the allowable range. 4. The control device for a transfer device according to claim 3, wherein the synchronization of the first motor and the second motor is lost, and an emergency stop is operated in response to the alarm from the alarm output unit. In this case, when a return command is input from the outside via an operation panel or the like after the cause of the abnormality is removed, the current position information of the first motor and the second motor is read, and the first and second motors in which the position deviation amount largely remains are read. 2. A control device for a transfer device, further comprising an automatic return control means for automatically returning the current position of the other motor to the current position of one of the two motors.