JPS63133889A - Method for controlling linear step motor - Google Patents

Abstract

PURPOSE:To accurately position a conveying truck by using both a method of detecting a relative address by a sensor to determine a stopping position and a method of detecting by calculating an exciting phase corresponding to a correct stopping position in advance. CONSTITUTION:When information of object stopping position is input by an external device 31, the stopping position is stored in a stopping position memory 324 and an exciting phase at the target stopping position is stored in an exciting phase calculator 328. An exciting phase deciding circuit 326 switches to a suit able exciting phase so as to become a decelerating or feeding mode in response to the varying speed of a sensor pattern. When a truck enters a station, the exciting phase is determined in response to a stopping distance calculated by a stopping distance calculator 325. When the stopping distance becomes 0, the positioning is held. At this time, when the exciting phase in which the positioning is held is different from that calculated before starting, it is corrected by a correcting circuit 330.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method of controlling a linear step motor.

2. Description of the Related Art As a conventional example of a conveying device in which the next side of a linear step motor is a fixed side, there is, for example, a structure shown in a perspective view of FIG.

FIG. 6 schematically shows the configuration of a four-phase VR type (variable reluctance type) linear step motor.

71 is a transport vehicle, and a slit plate 7 for shielding the linear step motor secondary side plate 74 and the photosensor 83 from light.
5, running wheels 72 that roll on running rails 81, and guide rollers 73 for guiding the transport vehicle 71. A linear step motor [next side 82] is installed at the station on the fixed side where the transport vehicle 71 should stop.
A photosensor 83 is arranged. In this example, a four-phase VR type (variable reluctance type) linear step motor is shown, and four photosensors 8 and 3 are arranged side by side to detect position information and speed information of the transport vehicle 71. .

Since four photosensors 83 are used, the transport carriage 71
By moving a slit plate 75 attached to the slit plate 75, eight patterns can be output. The reason for this is that a 4-phase linear step motor is used, so when 1-2 phase excitation is performed, 1
This is because each step moves 178 pitches. In other words, eight patterns are required in order to have eight steps in one pitch.

FIG. 5(a) shows sensors Pt, PZ, P3. An example of the positional relationship between the arrangement dimensions of P4 and the slit plate 75 is shown.

For example, set the tooth pitch of the slit plate to 8 nm (tooth length 4e
+, groove width 4 mm), and the sensor spacing was 14 m.

7m and 14m, so when the slit plate is moved in the direction of the arrow, the output signal of each sensor P1 to P4 will be the fifth
It changes as shown in figure (b).

The sensor output signal is an rHighJ signal when the light is blocked by the teeth of the slit plate 75, and a 1''LowJ signal when the light is not blocked.

Figure 5(c) is a table showing sensor output in 4-bit binary numbers.
, is 21 digits, P2 is 22 digits, P□ is 23 digits, and the "sensor pattern" is expressed in hexadecimal. In other words, every time the slit plate moves 1m in the direction of the arrow, the "sensor pattern" changes from 9 → 8 → C → E → 6 → 7 → 3 → 1 → 9...
...and repeat the change with 8Im as one pitch.

If the slit plate is moved in the opposite direction to the arrow mark, 9→
1→3→7→6→E→C→8→9...

Figure 5(d) shows the “sensor pattern” and “excitation pattern”
This is a table that corresponds to

For example, in the case of sensor pattern 9, the excitation phase in the range where the small teeth of the secondary plate and the small teeth of the primary core overlap is φ3-φ4.
6, that is, the “sensor pattern”
By knowing this, the excitation phase for positioning can be determined.

The configuration of the control device is shown in FIG.

The external device 31 is a control device that controls peripheral devices (not shown), such as a microcomputer, a sequencer, or the like. When the destination station and stop position are input from the external device 31, the linear step motor controller 32 determines an excitation pattern based on the pattern signal of the photosensor 35, and transfers the signal to the linear step motor driver 33.
Enter. The linear step motor driver 33 supplies excitation current according to the excitation pattern input from the linear step motor controller 32, and excites a predetermined phase of the linear step motor 34.

A detailed circuit block diagram of the linear step motor controller 32 is shown in FIG.

First, when the destination station and stop position are input from the external device 31, the stop position information is temporarily stored on the memory in the stop position storage circuit 324 via the receiving circuit 323.
Sensor pattern formation circuit 3 towards the future station
The excitation phase for acceleration mode is determined by the excitation phase determination circuit 326 according to the "sensor pattern" shown in FIG.
Convert to 3 output signals.

Next, when the carriage 71 enters the station, it receives the signal from the sensor 3f and obtains the "sensor pattern" shown in FIG. 5(c).

Next, the rate of change of the "sensor pattern" is input to a truck speed calculation circuit 321 that detects the speed of the truck, and an excitation phase determining circuit 326 determines the excitation phase to be in deceleration or feed mode in accordance with one truck speed. Also, when the trolley enters the station, the number of changes in the "sensor pattern" is simultaneously added or subtracted by the distance integration circuit 322, and the stop position storage circuit 3
24, a stop distance calculation circuit 325 calculates the distance of the current position from the specified stop position, and an excitation phase determination circuit 326 performs appropriate acceleration/deceleration control. Determine the excitation phase of

Next, when the distance from the designated stop position to the current position becomes 0, the excitation phase corresponding to the "sensor pattern" in FIG. 5(d) is excited to maintain positioning.

Conventional stopping position detection uses a counting circuit to add up each time the "sensor pattern" changes, and then compares the resulting value with the specified target stop position. If the numbers are the same, the target stop is executed. It is relatively judged that the cart has arrived at the position. Therefore, when the transport vehicle is held in position, the "sensor pattern" may be counted incorrectly due to vibration (damping) of the transport vehicle, and in this case, the transport vehicle completes the fixed position stop with a deviation of 1 to 2 steps. There was a drawback.

Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and uses a closed loop control method for a linear step motor to detect a relative address using a sensor and stop the conveyance cart when stopping it at a stop position. It is an object of the present invention to provide a control method that allows accurate positioning of a transport vehicle by using both a method of determining the position and a method of detecting in advance by calculation the excitation phase corresponding to the correct stop position.

Means for Solving the Problems The first invention has a linear step motor whose primary side is a fixed side and whose secondary side is a movable side, and the speed of the movable side and the distance from a predetermined reference point are detected by a sensor. In a closed loop control method that determines the excitation phase of a linear step motor based on a signal, a table is created in advance that associates the sensor output signal with the excitation phase, and the movable side is set at a specified position using the table and a specified stop position. The excitation phase for stopping at is determined by calculation, and when the movable side moves and is stopped and held at the specified position, the excitation phase at that time is detected by the sensor signal, and the excitation phase determined by the calculation is determined. As a result of the comparison, if the excitation phases are the same, the movable side is stopped and held at that position, and if the excitation phases are not the same, it is switched to the excitation phase determined by the above calculation and the stop and hold position is correct. It is characterized by being moved to a certain position.

In addition, the second invention is such that the secondary side of the linear step motor is a fixed side and the primary side is a movable side, the speed of the movable side and the distance from a predetermined reference point are detected by a sensor, and the linear step motor is controlled based on the signal of the sensor. In a closed loop control method for determining the excitation phase, a table is created in advance that associates the output signal of the sensor with the excitation phase, and the excitation phase is determined based on the table and the specified stop position to stop the movable side at the specified position. is determined by calculation, and when the movable side moves and is stopped and held at the specified position, the excitation phase at that time is detected by the sensor signal, and compared with the excitation phase determined by the calculation. If the resulting excitation phases are the same, the movable side is stopped and held at that position, and if the excitation phases are not the same, the movable side is switched to the excitation phase determined by the above calculation and the stop and hold position is moved to the correct position. shall be.

Example Embodiments of the present invention will be described below based on the drawings.

As an example, the configuration of a conveyance device using a linear stop motor will be described with reference to FIG. 3.

Furthermore, since the configuration of the control device in this case is also shown in FIG. 4, the explanation of FIGS. 3 and 4 will be omitted.

Linear step motor controller 3 in this embodiment
FIG. 1 shows a detailed circuit block diagram of No. 2, and FIG. 2 shows a control flow chart for accelerating, decelerating, and positioning the transport vehicle 71 in this embodiment. Further, the positional relationship between the sensor and the slit plate, the sensor pattern table, and the excitation pattern table in this embodiment are the same as those shown in FIG.

A detailed circuit block diagram of the linear step motor controller 32 shown in FIG. 1 will be explained below.

First, when the destination station and target stop position information is input from the external device 31, the stop position information is temporarily stored on the memory in the stop position storage circuit 324 via the receiving circuit 323.

Next, the excitation phase calculation circuit 328 at the time of stop calculates and recognizes the correct excitation phase for positioning and stopping (holding) the transport vehicle 71 at the target stop position before the transport vehicle 71 starts.

The calculation method will be specifically explained using an example.

If the target stop position is n and the step amount within one pitch is S, find the remainder of n÷S, (mod)m.

The excitation phase is determined by the excitation phase calculation table for positioning shown in FIG. 8, and the excitation phase is temporarily stored in the stop storage circuit 324. For example, if the target stop position is 250, the step amount within one pitch in this embodiment is 8, so 250
0÷8=31...2, and the remainder is 2. According to the table in FIG. 8, it is recognized that the two-phase excitation of φ4-φ1 is the correct excitation pattern at the time of final positioning.

Next, the conveyance vehicle 71 heads toward the destination station, and the sensor pattern forming circuit 320 carries out the
An excitation phase determination circuit 326 determines the excitation phase for acceleration mode based on the sensor pattern, and the excitation output circuit 327 converts the excitation phase into an output signal of the linear step motor driver 33.

Next, when the carriage 71 enters the station, the sensor pattern forming circuit 320 receives the signal from the sensor 3f and obtains a "sensor pattern" as shown in FIG. 5(C).

Next, the speed of the truck 71 is detected by the truck speed calculation circuit 321 based on the rate of change of the "sensor pattern."

The excitation phase determination circuit 326 switches to an appropriate excitation phase to set the deceleration or feed mode in accordance with the truck speed. Furthermore, when the trolley 71 enters the station, at the same time the number of changes in the "sensor pattern" is added or subtracted by the distance integration circuit 322, and compared with the target stop position stored in the stop position storage circuit 324, the stop distance is calculated. An excitation phase determining circuit 326 determines an excitation phase for performing appropriate acceleration/deceleration control while calculating the distance from the specified stop position to the current position in a circuit 325 .

Next, when the distance between the specified stop position and the current position becomes 0, the "sensor pattern" at that time is detected, and the fifth
The excitation phase corresponding to the "sensor pattern" shown in FIG. 3(d) is determined by the excitation phase determination circuit 326, and continuous excitation is performed to maintain positioning.

Next, the excitation phase for which positioning and holding was performed using the aforementioned "sensor pattern" and the excitation phase calculated by calculation before starting the bogie are compared in the excitation output circuit 329 at the time of stop, and if they are different, the correction circuit 330 The excitation phase is corrected to the excitation phase calculated by calculation before starting the cart, and the excitation phase is switched via the excitation output circuit 327.

Next, a control method for accelerating, decelerating and positioning the transport vehicle 71 at a designated station in this embodiment will be explained based on the flowchart of FIG. 2.

Information on the destination station and stop position is received as a start command from the external device 31 (step 200). Based on the information on the specified stop position, the correct excitation phase is calculated in order to stop the transport vehicle 71 at the target stop position, and the excitation phase is temporarily stored in the memory (step 201).
.

Based on the information of the destination station, a comparison is made with the current station where the trolley 71 is currently stopped.

The acceleration direction of the transport vehicle is determined based on the difference (step 202). If the difference is 0, that is, if the destination station and the current station where the trolley 71 is currently stopped are the same, it is determined that the movement is within the station, and the designated stop position and the current stop position where the trolley 71 is currently stopped are determined to be intra-station movement. The acceleration direction of the truck is determined based on the difference, and the truck is moved (step 209). When moving to another station, once the acceleration direction is determined (step 202), the cart is accelerated toward the destination station (step 20).
3). When the sensor 3f detects that the cart has escaped from the departure station, the acceleration control ends (step 20).
4) Next, at the destination station, the vehicle waits for the trolley to enter (step 205).

When the trolley 71 enters at a higher speed than the preset speed V□ (step 206), deceleration control is performed (step 207), the speed is decelerated until the set speed v2 is reached (step 208), and thereafter the speed is maintained at an appropriate speed. The cart 71 is moved toward the target stop position (step 209). Also, trolley 7
Count the amount of change in the "sensor pattern" from the time when 1 enters from the station, integrate the distance from the entry point, and calculate the difference between the result and the value of the target stop position.
The distance from the target stop position to the position of the cart 71 is calculated (step 210), and when the value becomes zero (0), it is determined that the cart 71 has arrived at the stop position (step 211), and the position is maintained (step 212).

Next, it is checked whether the excitation phase currently held in position based on the above-mentioned "sensor pattern" is correct (step 213). That is, the excitation phase recognized by calculation before starting the trolley 71 (step 201) is compared with the currently excited excitation phase (step 212), and if they are different, the excitation phase recognized by calculation (step 201) is changed. The correction is made, the excitation phase is switched, the carriage 71 is moved to the correct position, and one carriage 71 is again positioned and held (step 214).

Effects of the Invention As explained in the embodiments, the present invention, when performing closed-loop control of a linear step motor, can accurately position the conveyor cart at a stop position with simple control, and can even stop at a position other than the stop position. This has the effect of correcting and stopping at the correct position.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram of the linear step motor controller of the present invention, Fig. 2 is a flowchart of the control of the present invention, Fig. 3 and the following show a conventional example, Fig. 3 is a perspective view of the conveying device, and Fig. 4 is a flowchart of the control of the present invention. Configuration diagram of the control device, Fig. 5 is an explanatory diagram, Fig. 6
This figure is a block diagram of a linear step motor, FIG. 7 is a circuit block diagram of a linear step motor controller, and FIG. 8 is an excitation phase calculation table for positioning. 31 is an external device, 32 is a linear step controller,
33 is a linear step motor driver, 34 is a linear step motor, and 35 is a photo sensor.

Claims (2)

[Claims] (1) The primary side of the linear step motor is the fixed side and the secondary side is the movable side. The speed of the movable side and the distance from a predetermined reference point are detected by a sensor, and the excitation phase of the linear step motor is determined based on the signal from the sensor. In the closed-loop control method to be determined, a table is created in advance that associates the output signal of the sensor with the excitation phase, and the excitation phase for stopping the movement at the specified position is calculated using the table and the specified stop position. When the decision is made and the movable side moves and is stopped and held at the specified position, the excitation phase at that time is detected by the sensor signal, and compared with the excitation phase determined by the calculation, and as a result of the comparison, the excitation phase is the same. If so, the movable side is stopped and held at that position, and if the excitation phases are not the same, it is switched to the excitation phase determined by the calculation described above, and the stopped and held position is moved to the correct position. control method. (2) The secondary side of the linear step motor is the fixed side and the primary side is the movable side. The speed of the movable side and the distance from a predetermined reference point are detected by a sensor, and the excitation phase of the linear step motor is determined based on the signal from the sensor. In the closed-loop control method to be determined, a table is created in advance that associates the output signal of the sensor with the excitation phase, and the excitation phase for stopping the movable side at the specified position is calculated using the table and the specified stop position. When the movable side moves and is stopped and held at the specified position, the excitation phase at that time is detected by the sensor signal and compared with the excitation phase determined by the calculation, and as a result of the comparison, the excitation phase is determined. If the excitation phases are the same, the movable side is stopped and held at that position, and if the excitation phases are not the same, the excitation phase is switched to the excitation phase determined by the calculation, and the stop and hold position is moved to the correct position. How to control a motor.