JPH021045B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to a moving body that can be used, for example, to control fixed position stopping of a rotary rack having a large number of trays that are connected in an endless manner and move on a circulation path. The present invention relates to a stop control method.

(Prior Art) As a stop control method for a moving body as described above, a pulse transmitting means is provided which transmits a pulse at a period proportional to the speed of the moving body, and the pulse transmitting means starts from the time when the mobile body passes a fixed position. A stop control method is known in which the counting of pulses transmitted from the moving body is started, and when the pulse count value reaches the stop control start setting value, the driving of the moving body is canceled and the moving body is braked to a stop.

In such a stop control method, the drive of the movable body is canceled based on the coincidence of the pulse count value and the stop control start set value, and the movable body is stopped completely after a braking stop is performed. If the moving distance due to inertia is not constant at all times, there will be variations in the actual stopping position of the moving body. However, it is clear that the distance traveled by inertia from when the drive of the movable body is released and the brake is stopped until the movable body completely stops changes due to changes in the device over time and the like.

In order to solve such problems, conventionally, when a moving body stops, a stop position detection means is used to stop it at a target stop position, as described in Japanese Patent Application Laid-Open No. 51-113957. output a detection signal indicating whether it is an overrun or an underrun, and set a constant value to the stop control start setting value based on this detection signal.
Correction is performed by adding or subtracting to eliminate overrun or underrun, and the next stop control is performed based on the corrected stop control start setting value.

(Problem to be Solved by the Invention) In the conventional control method as described above, if the stop position of the moving body deviates from the target stop position, the stop control start setting is always set to a constant value regardless of the amount of deviation. Since the correction is made by adding or subtracting the value, if the distance corresponding to the above-mentioned constant value does not match the actual stop position deviation amount, the stop control is performed based on the corrected stop control start setting value. Even if I go,
As expected, a deviation will occur in the stopping position. That is, with such conventional control methods, it is impossible to perform highly accurate stop control on the millimeter scale.
In particular, similar correction control is performed even when a large overrun or underrun occurs due to an unexpected cause, so the stop control is performed until the next stop control, which should normally be able to stop at a fixed stop position. Correcting the control start set value results in an adverse effect.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, the present invention provides a pulse transmitting means that transmits pulses at a period proportional to the speed of a moving body. The stop control method starts counting the emitted pulses from the pulse emitting means from the time when the pulse emitting means passes, and when the pulse count value reaches a stop control start set value, the driving of the moving body is canceled and the moving body is braked to a stop. It is determined whether the pulse count value when the moving body stops is within a preset tolerance range that does not correspond to overrun or underrun, and the pulse count value that is within the tolerance range is determined. The average value of is calculated each time the moving body stops a set number of times, and the error between this average value and a preset target value that corresponds to when stopping at a fixed position is calculated, and the stop control is performed according to this error. This invention proposes a stop control method for a moving object, which is characterized in that the start set value is corrected and the next stop control is performed based on the corrected stop control start set value.

(Embodiment) Hereinafter, an embodiment of the present invention will be described based on the attached illustrative drawings. In FIG. 1, 1 is a drive gear 2
4 is a tray attached to the endless chain 1 at regular intervals; This is a driving induction motor that is linked together. As shown in FIGS. 2 and 3, each tray 4 includes a detection plate 7, a support guide roller 8, a support guide rail 9, a steady rest guide roller 10, and a steady rest guide rail 11. It is supported so that it can circulate in a fixed posture on a horizontal circulation path. PHS
-F and PHS-R are a pair of photoelectric switches that detect the detection plate 7 of the tray 4 passing through the cargo handling position, and are capable of simultaneously detecting both ends of the detection plate 7 at a fixed location beside the tray movement path. attached at intervals.

Incidentally, the origin tray 4a, which is the No. 1 tray among the series of trays 4, is attached with an origin detection plate 7a, and an origin detection photoelectric switch PHS- detects only this origin detection plate 7a. X is arranged between the pair of photoelectric switches PHS-F and PHS-R.

FIG. 4 shows the overall configuration of the stop control device, where 12 is an addition/subtraction counter, and when both the photoelectric switches PHS-F and PHS-R detect both ends of the detection plate 7, the AND gate 13 The signal output from the tray 4 is added during forward rotation and subtracted during reverse rotation according to the forward/backward movement discrimination signal 14 corresponding to the rotation direction of the tray 4, and a unique tray number is assigned to each tray passing through the material handling position. Output. Incidentally, the detection signal 15 of the photoelectric switch PHS-X is used to return the counter value to the origin (No. 1). Reference numeral 16 denotes a comparison circuit, which compares the called tray number inputted to this circuit with the detection tray number given from the addition/subtraction counter 12, and determines whether the tray that is one tray in front of the called tray in the tray movement direction is When it passes, it outputs a deceleration command 17, and when the calling tray number and the detected tray number match, it outputs a coincidence signal 18.

The drive device 19 includes the motor 5 and its control means, and switches the rotating speed of the tray 4 to a low speed when the deceleration command 17 is given. After the rotating speed of the tray 4 is switched to a low speed by this deceleration command 17, as shown in FIG.
When the tray 4 reaches the cargo handling position, first the front end of the detection plate 7 of the tray 4 is connected to the photoelectric switch PHS.
-R detects it (in the case of reverse rotation, the photoelectric switch PHS-F detects the rear end of the detection plate 7). As a result, a counting start command 22 is output from the AND gate 21 based on the signal applied from the OR gate 20 and the deceleration command 17. A counter 23 activated by this counting start command 22
As shown in FIG. 1, the pulse encoder PE, which is interlocked with the tray drive motor 5, counts pulses transmitted at extremely short intervals (for example, one pulse per 1 mm of the moving distance of the tray 4). 2
A comparison circuit 4 compares the count value of the counter 23 with a set value, and outputs a braking command 25 when the two values match. Upon receiving this braking command 25, the drive device 19 releases the drive of the motor 5 and simultaneously switches to a dynamic braking state. Therefore, as shown in FIG.
The set value X set in the comparator circuit 24 from the time when the front end of the
After continuing movement for a distance corresponding to 1 (number of pulses), braking is applied, and the movement is stopped after inertia movement indicated by distance L1.

On the other hand, the timer switch 26 is activated from the time when the braking command 25 is output, and the time set in the timer switch 26 (i.e., the braking command 25 is activated).
The stop position checking means 27 is activated after a period of time (slightly longer than the expected maximum time required for the tray 4 to stop) has elapsed after the output of the tray 4. This stop position checking means 27 checks the count value of the counter 23 (X2 in FIG. 5) when the tray is stopped.
) is within the predetermined set value width X3a to X3b (within the allowable stopping accuracy range), the counted value X2
is input into the storage means 28 and at the same time outputs the normal stop detection signal 29, and when the count value X2 is in an overrun state exceeding the maximum value X3b of the set value width or an underrun state in which it does not reach the minimum value X3a, respectively. Detection signals 30 and 31 corresponding to the detection signals 30 and 31 are output.

The normal stop detection signal 29 is transmitted to the comparison circuit 16.
It is inputted to the AND gate 32 along with the coincidence signal 18 from , and a fixed position stop completion signal 33 is output.

The storage means 28 stores the tray stop position corresponding count value X2 input as described above for each tray stop control, and upon completion of this storage, the counter 23 is reset. 34 is an arithmetic circuit which receives an average value calculation command 36 which is given every time the number of stop control counts counted by the preset counter 35 reaches a set value, for example 10 times, and calculates the average value calculated immediately before the value stored in the storage means 28. The average value X4 of the count value X2 corresponding to the tray stop position for 10 times is calculated. This average value X4 is input to the next stage comparison circuit 37,
The difference from the set value X5 corresponding to the center value of the set value widths X3a to X3b is calculated, and if the difference exceeds the allowable range, the average value deviation ±ΔX is calculated by the comparison circuit 37.
is output from. The average value deviation ±ΔX obtained in this way is added to the set value X1 by the set value correction means 38, and from then on, this corrected set value
X1±ΔX and the counted value from the counter 23 are compared.

Next, a specific control method will be explained based on FIGS. 4 to 7 (the rotation direction of the tray 4 is assumed to be the forward rotation direction indicated by the arrow in FIG. 5).
In order to call the trays 4 to the material handling position, when the drive device 19 is operated with the called tray number set and the motor 5 circulates the series of trays 4, the number of trays 4 passing through the material handling position is changed. are sequentially output from the addition/subtraction counter 12, and this detected tray number and the called tray number are compared in the comparison circuit 16, and when the tray 4 one place before the called tray passes the load handling position, a deceleration command is issued. 17 is output, and the moving speed of the tray 4 is switched to low speed as described above.

Therefore, the calling tray 4 approaches the cargo handling position at low speed, but the front end of the detection plate 7 in the tray 4 is exposed to the photoelectric switch as shown in FIG.
When detected by the PHS-R, the counter 23 is turned on by a counting start command 22, and the pulses sent from the pulse encoder PE are counted.
This count value is the setting value X1 (or the correction setting value described later)
X1±ΔX), a braking command 25 is output from the comparison circuit 24, and based on this braking command 25, the drive device 19 cancels the low-speed drive of the tray 4 by the motor 5 and simultaneously switches to dynamic braking. Therefore, as shown in FIG. 5, the calling tray 4 stops after moving by inertia by a distance L1.

As described above, the call tray 4 with the set number stops at the cargo handling position, but around the time the tray 4 stops, the stop position check means 27 is activated, and the counter 23 calculates the value at this time. Numerical value (Since the pulse encoder PE stops when the tray 4 stops, the numerical value on the counter 23 is the tray value from when the photoelectric switch PHS-R detects the front end of the detection plate 7 until the tray 4 stops.) (The count value corresponding to the moving distance, that is, the count value corresponding to the tray stop position) is stopped at the set value width
3b. Then, the count value X2 corresponding to the tray stop position is the set value width X3a to X3b.
In other words, both ends of the detection plate 7 in the call tray 4 are connected to a pair of photoelectric switches PHS-F,
When the calling tray 4 is stopped within the predetermined stopping accuracy range that the PHS-R can detect,
The normal stop detection signal 29 is output, and at this time, the comparison circuit 16 naturally outputs the coincidence signal 18, so the fixed position stop completion signal 33 is output from the AND gate 32, and the series of stop controls is as follows. Complete.

If the tray stop position corresponding count value X2 is not within the set value width X3a to X3b, the overrun detection signal 30 or the underrun detection signal 3
1 is output, so this detection signal 30 or 31
Using this, it is possible to display an abnormal stop in an appropriate manner or perform appropriate stop position correction control to correct the calling tray 4 to within a predetermined stop accuracy range.

On the other hand, when the tray stop position corresponding count value X2 is within the set value width X3a to X3b, the tray stop position corresponding count value X2 is stored in the storage means 28 for each tray stop control. . And when the stop control circuit reaches a set number of times, for example 10 times,
The average value X4 of the last 10 tray stop position corresponding count values X2 stored in the storage means 28 is calculated by the calculation circuit 34, and the difference between the set value X5 and the average value X4 is calculated by the comparison circuit 37. be done. If the difference exceeds the allowable range, the average deviation ±ΔX is output.

In Figure 6, the x mark indicates the tray stop position each time,
That is, it shows the count value X2 corresponding to the tray stop position, and A
indicates one group (10 times) of the tray stop position corresponding count value X2 when the average value X4 is approximately equal to the set value X5, and in this case, the average value deviation ±
ΔX is not output. B shows a group of count values X2 corresponding to the tray stop position when the difference between the average value X4 and the set value X5 becomes larger than the allowable range on the + side, and in this case, the average value deviation +ΔX is output. Ru. Also, C indicates a group of count values X2 corresponding to the tray stop position when the difference between the average value X4 and the set value Output.

Average value deviation ±ΔX output as above
Based on this, the set value correction means 38 sets the set value X1
However, as mentioned above, the occurrence of the average value deviation +ΔX is a result of the inertial movement distance L1 of the tray 4 after braking being increased, so it is necessary to advance the timing of braking by ΔX. Since the occurrence of the average value deviation -ΔX is a result of the inertial movement distance L1 of the tray 4 being shortened after braking, it is necessary to delay the timing of braking by ΔX. Therefore, the set value correction means 38 performs a correction of subtracting ΔX from the initial setting value X1 when the average value deviation is +ΔX, and performs a correction of adding ΔX to the initial setting value X1 when the average value deviation is −ΔX. Have them do it. As a result, the corrected set value X1±ΔX is used for subsequent tray stop control, and this set value X1±ΔX is compared with the counted value from the counter 23, so the timing at which the braking command 25 is output is is advanced or delayed by ΔX, and the stop position corresponding count value X2 coincides with or approaches the set value X5, which is the center of the predetermined stop accuracy range. That is, the stop control can be performed in the state shown by A in FIG. 6.

In the above embodiment, a case has been described in which the tray 4 rotates in the forward rotation direction, but the same control can be performed even when the tray 4 rotates in the reverse rotation direction. Furthermore, in the above embodiment, when the photoelectric switch PHS-F or PHS-R is turned on while the deceleration command 17 is being output, the tray 4 (moving body) is at the home position, which is the reference position for stop control. However, the method of detecting the passage of this fixed position is not limited to the method of this embodiment. Furthermore, a pulse encoder PE was used as a pulse transmitting means for transmitting pulses at a period proportional to the speed of the tray 4 (moving body), but holes (slits) were provided at small intervals in the tray movement direction as the detection plate 7. The pulse signal of a photoelectric switch that detects this hole may be counted by a counter, or a large number of detectors may be arranged in parallel at small intervals in the direction of movement of the detection plate 7, and from these detector groups, It is also possible to obtain a signal corresponding to the count value obtained from the counter 23.

Further, in the embodiment, the tray 4 is stopped by dynamic braking, but it is also possible to stop the tray 4 by using mechanical braking means. In this case as well, the above control is effective because the tray 4 moves a certain distance by inertia after applying the brake. Furthermore, in the embodiment, it is determined whether or not the tray stop position corresponding count value X2 is within the set value width X3a to X3b, and according to this determination, the normal stop detection signal 2 is output.
9. The overrun detection signal 30 and the underrun detection signal 31 are output, but with this method, if a counting error occurs in the counter 23, the stop position must be checked to match the actual tray stop position. I can't. Therefore, when the set time of the timer switch 26 has elapsed, the photoelectric switches PHS-F and PHS-R are turned on and off.
The stop position of the tray 4 is determined from the status, and when both are ON, a normal stop detection signal 29 is output, and when only the photoelectric switch PHS-F is ON, an overrun detection signal 30 is output, and the photoelectric switch PHS-R is output.
When only is ON, underrun detection signal 31
, respectively, and both photoelectric switches
Only when PHS-F and PHS-R are ON, the tray stop position corresponding count value X2 can be controlled to be stored in the storage means 28.

In addition, the above photoelectric switch PHS-F, PHS-R
A control method that determines the stop position of the tray 4 from the ON and OFF states of The method explained in , that is, the tray stop position corresponding count value X2
By combining the method of storing the relevant count value X2 in the storage means 28 only when the count value X2 is within the set value range X3a to X3b, it is possible to store the relevant count value It is also possible to perform control such that the counted value X2 is stored in the storage means 28 only when the numerical value X2 is within the set value range X3a to X3b.

In addition, since the stop position accuracy for each stop control of each moving body can be memorized as in the example, the memory can be printed out on a printer or displayed on a display to check the current stop accuracy. Trends can also be easily seen.

Further, in the embodiments, individually independent control means or circuits are used, but in reality, a computer can be used in conjunction with the program control method.

(Operations and Effects of the Invention) As described above, according to the movable body stop control method of the present invention, the pulse count value (in the embodiment, the tray stop position corresponding count value) when the movable body (tray 4 in the embodiment) stops. It is determined whether or not the numerical value The average value of the numerical values is calculated each time the moving object stops a set number of times, and the error between the average value (in the example, the position The deviation amount ±ΔX) is calculated, and according to this error, the stop control start set value (set value Since this is performed based on the corrected stop control start setting value, if the pulse count value when the moving body stops is outside the above-mentioned allowable value range, which is a so-called overrun or underrun state, the relevant The pulse count value is not used to correct the stop control start setting value. Therefore, even if an abnormal overrun or underrun occurs due to an unexpected cause, this will not affect the next stop control.
Countermeasures against occurrence of overrun or underrun, which are conventionally well known, can be taken.

Then, the error between the average value of the pulse count value at stop and the target value, that is, the number of pulses corresponding to the average value of the amount of positional deviation between the constant stop position and the actual stop position of the moving body, is determined. Therefore, the stop control start set value is corrected, so compared to the case where the stop control start set value is corrected by always adding or subtracting a constant value regardless of the error (positional deviation amount), the following Stop position accuracy during stop control can be made extremely high.

That is, according to the stop control method of the present invention, the inertial movement distance of the movable body after braking varies due to various causes, and the stop position of the movable body deviates from the center of the predetermined tolerance range in the + direction or - direction. If left as is, it is predicted that the stopping position of the moving body will be in an overrun or underrun state exceeding the above-mentioned allowable range, the timing of braking for the moving body can be automatically and By making accurate corrections and preventing overruns and underruns, it is possible to always keep the average stopping position accuracy of the moving body at or close to ±0.

Moreover, in the present invention, the above-mentioned Japanese Patent Application Laid-open No.
As described in Publication No. 113957, instead of simply adding or subtracting a fixed value to the stop control start set value after the stop control has been performed a set number of times, correction is made from the pulse count value at each stop. The calculated average value is used to correct the stop control start setting value when the stop control has been performed the set number of times, so the stop control start value is corrected each time while reducing the operating rate of the control equipment. The desired purpose can be achieved with almost no difference from the case where the correction is made every time.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view explaining the configuration of the rotary rack, Fig. 2 is a plan view showing the relationship between the tray and the detection switch, Fig. 3 is a side view of the same, and Fig. 4 is an illustration of an embodiment of the present invention. Fig. 5 is a diagram showing the relationship between the detected plate and the photoelectric switch during stopping, Fig. 6 is a diagram explaining the variation of the stopping position within the allowable stopping accuracy range, and Fig. 7 is the control diagram. This is a flowchart explaining the method. 1...Endless chain, 2...Drive gear, 3...Idle gear, 4...Tray, 5...Induction motor, 7, 7a...Detected plate (detected part), 1
2...Addition/subtraction counter, 16, 24, 37...
Comparison circuit, 19... Drive device, 23... Counter, 26... Timer switch, 27... Stop position checking means, 28... Memory means, 34... Arithmetic circuit, 35... Preset counter, 38...
...Set value correction means, PE...Pulse encoder,
PHS-F, PHS-R, PHS-X...Photoelectric switch (detector).

Claims (1)

[Claims] 1. A pulse transmitting means that transmits pulses at a period proportional to the speed of the moving body is provided, and the counting of pulses transmitted from the pulse transmitting means is started from the time the mobile body passes a fixed position, and the pulse count value stops. In a stop control method for releasing the drive of the moving body and stopping the moving body by braking when the control start set value is reached,
determining whether the pulse count value when the moving body stops is within a preset tolerance range that does not correspond to overrun or underrun;
Calculate the average value of the pulse count values within the tolerance range each time the moving object stops a set number of times, and calculate the error between this average value and the target value that is set in advance and corresponds to when stopping at a fixed position. A method for controlling a stop of a moving object, characterized in that the stop control start set value is corrected according to this error, and the next stop control is performed based on the corrected stop control start set value.