JP2989656B2 - Automatic warehouse positioning device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a positioning device for an automatic warehouse.

(Prior art) At present, many automatic warehouses are on the market, and are operated in factories and logistics institutions, and have greatly contributed to rationalization of transport systems.

Examples of conventional automobile warehouses include, for example, multi-row multi-stage shelves, a plurality of loading / unloading stations for loading / unloading loads to / from each shelf, and a plurality of lifter traveling shafts, lifter elevating shafts, and fork telescopic shafts. And a transfer means for transferring a load, such as a pallet or a bucket, between each shelf and the loading / unloading station by driving each shaft in an arbitrary direction by an arbitrary amount.

In a conventional automatic warehouse of this type, since each axis of the transfer means is controlled by a positioning device using a DC motor, high-speed and high-precision positioning is possible,
There was a problem that the device became expensive.

Therefore, a positioning device is configured using an AC motor,
Although it is conceivable to drive the transfer means of the automatic warehouse, the AC motor, especially at low speed and low torque, cannot perform any control like a DC motor and collapses in an automatic warehouse. It was difficult to satisfy the conditions of high speed and high positioning without any problems.

(Problems to be Solved by the Invention) As described above, it is difficult for a conventional positioning device using an AC motor to perform a high-speed, high-positioning operation without collapse of a load.

Therefore, an object of the present invention is to provide a positioning device for an automatic warehouse that can perform high-speed and high-positioning using an AC motor without collapse of a load.

(Means for Solving the Problems) In view of the above-mentioned problems, the present invention includes a multi-row multi-stage shelf, and a transfer means for moving a load to each shelf position, and the transfer means is driven by an AC motor. In a positioning device for an automatic warehouse, the moving command unit outputs a command signal to move the transfer unit to a command position, and the command position and the moving unit of the movement command unit. A distance calculating unit that calculates a moving distance based on the current position of
A clamp speed setting unit for setting a clamp speed corresponding to the movement distance calculated by the distance calculation unit by searching table data of a relationship between the movement distance and the clamp speed and the deceleration distance, and a deceleration distance setting unit for setting a deceleration distance A deceleration start position setting unit that calculates a deceleration start position based on the command position and the deceleration distance set by the deceleration distance setting unit; a clamp speed set by the clamp speed setting unit; Acceleration / deceleration is calculated according to the deceleration start position calculated by the position setting unit, the current position signal calculated by the position calculation unit, and the current speed signal calculated by the speed calculation unit. An acceleration / deceleration calculation command unit that outputs a predetermined speed command signal so that the speed becomes a specified value, and the speed loop that controls the speed of the transfer unit. A position loop control unit that performs control and position control, and a position where the speed after the deceleration of the transfer means is set to a small constant low speed has a constant gradient passing through the speed line of the low speed and the target position. A command signal for setting the command speed to a low speed is output to the acceleration / deceleration calculation command unit when the position is before the intersection with the straight line representing the speed, and when the position is beyond the intersection, the vehicle is decelerated and rides on the straight line. A loop switching control unit that outputs a deceleration command signal to the acceleration / deceleration calculation command unit, and switches to control by a position loop control unit when the speed of the transfer unit rides on the straight line, and a clamp speed at a small moving distance is set. And calculating the difference between the desired speed and the current speed, which are determined to have reached the comparison position within the small movement distance, and when the speed difference is larger than the reference value, the speed is calculated. It calculates a small clamp speed and the deceleration distance from the corresponding to the acceleration correction calculation unit for outputting the small clamp velocity and deceleration distance to the acceleration operation command unit as a correction value, a configuration in which a.

(Example) In FIG. 2 showing an example of an automatic warehouse in which the present invention is implemented, a traveling rail 2 is laid along a longitudinal direction of a base 1, and a traveling platform 3 travels on the rail 2. Has become. The traveling direction of the traveling platform 3 is defined as a T direction.

On the base 1, a post 4 of the running rail 2 is provided with a multi-row multi-stage (shown as an example of 6 rows and 10 stages) shelves 4, and in front of the running rail 2, a multi-row with a control panel 5 is provided. (Shown in the example of six columns), the loading / unloading station 6 (6-1, 6-2 ... 6-
6) is arranged. An operation panel on the upper surface of the control panel 5
5a is provided.

On the other hand, on the front side above the shelf 4, an upper rail 7 is provided in parallel with the traveling rail 2, and a vertical rail 8 is installed between the two rails 2, 7, and the upper end thereof is an upper rail 7
, And the lower end thereof is fixed to the traveling platform 3. Therefore, the vertical rail 8 is movable in the T direction on the front side of the shelf 4 by the traveling of the traveling platform 3 in the T direction.

A lifter 10 having a fork 9 that can expand and contract in the front-rear direction is supported on the vertical rail 8 so as to be able to move up and down. Therefore, the lifter 10 can be moved to an arbitrary shelf position or an arbitrary entry / exit station position by moving up and down along the vertical rail 8 and moving the traveling platform 3 along the traveling rail 2. It is. Furthermore, by operating the fork 10 back and forth at each shelf or each loading / unloading station position and operating an appropriate operation sequence, for each shelf or each loading / unloading station,
It is possible to load and unload goods such as pallets and buckets. The lifting direction of the lifter 10 is defined as L direction, and the moving direction of the fork 9 is defined as F direction. In this example, it is assumed that the load is a bucket, and the loading / unloading operation sequence is such that the lifter 10 is lowered while the fork 9 carrying the bucket is extended to the bottom side of a certain shelf, and the fork 9 is contracted. In addition to loading the bucket on the shelf and extending the fork 9 at a position slightly lower than the bottom height of a certain shelf, the lifter 10 is raised slightly, and then the fork 9 is contracted to take the bucket on the fork 9. Let it be a sequence. Cradle 3
, Fork 9 and lifter 10 constitute a means for transferring the load.

In this example, the traveling operation of the traveling platform 3, the lifting / lowering operation of the lifter 10, and the expansion / contraction operation of the fork 9 are all controlled by a positioning device using an AC motor. For positioning, the control panel 5 is mainly composed of an NC device. Each entry / exit station is provided with a simple operation panel 11 (11-1, 11-2,..., 11-6) provided with a switch for an entry / exit command and an LED indicating an operation state.

As shown in FIG. 3, it is incorporated in the control panel 5,
A control device (NC device) 12 connected to each switch or lamps of the operation panel 5a is mainly composed of a CPU board 13, and is used to drive the lifter 10 up and down via a first inverter 14. of which is connected to 3-phase AC motor M _L, also a 3-phase AC motor M _T and the fork 9 for driving the traveling base 3 through a magnet switch MS1, MS2 which is connected in parallel with the second inverter 15 and which 3-phase AC motor M _F for expanding and contracting operation is connected. 3 each
Phase AC motor M _L, M _T, the position detector to the rotary shaft of the M _F which outputs a pulse signal proportional to the movement amount (encoder) PG is provided, the detection signal E of the position detector PG (E _L, E _T , E _F ) is CPU
It has been returned to the board 13. B indicates a brake.

The magnet switches MS1 and MS2 are connected to the second inverter 15
The order used also in the motor M _T or M _F, the switching signal from the CPU board 13 is for switching the inverter 15 to the motor M _T side or to the motor M _F side.

Thus, in this embodiment, the second motor M _T and the motor M _F
Since the inverter 15 is switched and used, the number of inverters can be reduced correspondingly, and the cost of the apparatus can be further reduced in addition to the cost reduction by using the AC servomotor. Here, in an automatic warehouse as shown in FIG. 2, the lifter 10 may be moved up and down while running the traveling platform 3 at the time of automatic operation, and the fork 9 may be moved up and down while moving the lifter 10 up and down. However, the traveling platform 3 does not travel while the fork 9 is extended and retracted. Thus, the motor M _T for running a motor M _F for extending and retracting the fork 9, the traveling table 3
Is operated for one inverter 15,
There is no problem in the general operation of the automatic warehouse.

In addition, the CPU board 13 receives signals (D _i ) from various sensors and signals (D ₀ ) for operating actuators such as various lamps.
Is output. Also, CPU board 13
Is a micro-programmable controller (MPC) 16 and an optional host computer (HOST) 17
Are connected to the switch board 18 of the operation panel 5a via digital or serial signal lines.

As shown in FIG. 4, the CPU board 13 is a general N board.
As with the C device, various members 20, 21,.
Connected. 20 is a patrol light and buzzer device. 21, 22, and 23 are devices for the switch board 18, and 21
Is a buzzer device, 22 is a 7-segment display driver, 23
Indicates a key encoder. 24 is a digital input (D _i ), 25 is battery-backed RAM, and 26 is RA
M and 27 are ROM, 28 is CPU, 29 is MPC32 interface, 30 is digital output (D ₀ ), 31 is a serial interface for inputting HOST17 signal, 32 is timer,
33 is a digital / analog (D / A) converter for outputting an analog signal to the first and second inverters 14 and 15;
Is a second or first programmable timer. ROM2
7, various interlock conditions are stored together with a sequence for returning each axis to the origin.

The CPU 28 is connected to a clock 36 and a watch dog timer 37 which receives and operates a clock signal of the clock 36. Each programmable timer 34, 35 has a position detector P
M to detect the direction by inputting the signal of the position detector between G and G
SM38,39,40 are connected. An OR gate 41 inputs an output signal of each member and outputs an interrupt signal to the CPU 28.

In the automatic warehouse having the above configuration, the CPU 28, the D / A 33, the inverters 14 and 15, and the position detector PG constitute a positioning device shown in FIG. 1, and controls the positioning of each axis. The illustrated positioning device has the same configuration for each axis. However, the third
As shown, in this embodiment, since the shared inverter 15 for the motor M _T and M _F, in Figure 1, a motor
M _T, the control member of the M _F is the form used in common one thing.

In Figure 1, the positioning device 42 of the present embodiment, the motor M shown in FIG. 3 in (M _L, M _T, M _F), a position detector PG and the inverter 14, 15 is formed in the CPU board 13 Control members 43 to 54
Are connected as shown.

The movement command unit 43 determines the movement position of each axis based on the operation of the operation panel 5a and the operation of the operation panel 11 on the station 6 side shown in FIG. and outputs a command signal will be moved to the (target position) x _1. Current position as x _0, shown in FIG. 5 the respective positional relationships on the x-axis.

The distance calculation section 44, the current position x ₀ from the position x ₁ of the command is subtracted, and requests the moving distance L by the following equation.

L = x ₁ −x ₀ (1) The clamp speed setting unit 45 and the deceleration distance setting unit 46 search the table data shown in FIG. 6 according to the distance L calculated by the distance calculation unit 44, and move Clamping speed according to distance L
V _CL and _{(V CL1, V CL2, V} CL3, V CL4), the deceleration distance △ L (△ L _1,
ΔL ₂ , ΔL ₃ , ΔL ₄ ). The clamp speed _VCL is a speed for regulating the maximum speed during movement. The deceleration distance ΔL is a distance required for positioning at a speed decelerated from the maximum speed, and is set by giving a rare margin of about 1 to 2 cm to the actually required distance. Accordingly, the table data shown in FIG. 6 sets the relatively large clamping speed _VCL and the deceleration distance ΔL according to the moving distance L when the moving distance is large, and sets the relatively small values when the moving distance L is small. Is set.

Deceleration start position setting unit 47 uses the deceleration distance △ L, and requests the deceleration start position x ₂ by the following equation.

x ₂ = x ₁ −ΔL (2) Therefore, as shown in FIG. 5, the deceleration start position x ₂ is set in front of the target position x _{1 by} the distance ΔL.

The acceleration / deceleration calculating unit 48 is configured to calculate the clamp speed _VCL , the deceleration start position x ₂ , the current position signal x calculated by the position calculating unit 54, and the current speed signal V calculated by the speed calculating unit 52, as shown in FIG. in the procedure shown in ~ FIG. 9 performs acceleration and deceleration operations, to speed loop control section 49, and outputs a predetermined velocity command signal V _S to acceleration alpha becomes a specified value alpha _S. FIG. 7 is a flowchart showing a calculation method for determining an acceleration characteristic in the above speed control.

In step 701, the current V _NW is sampled, and the parameters K ₁ and K ₂ are calculated by the following equations in steps 702 and 703, with the speed V _ST at the start of acceleration and the speed V _EN at the end of acceleration as V _EN .

Parameter K ₁ is a value that varies linearly from 0 toward the end point to 2 from the acceleration start point, the parameter K ₂ is linearly changing values toward the starting point from 0 to 2 from acceleration end point.

Next, in step 704, K ₁ ≦ K ₂ is determined, and in order to set the smaller value of K ₁ and K ₂ , in steps 705 and 706,
K = K ₁ and K = K ₂ are set respectively. Thus, to the intermediate point is K = K _1, midpoint after the K = K ₂ is set.

In step 707, △ additional acceleration to give the initial acceleration of the alpha, the magnification is the parameter set of n as a number between 1-2, the alpha ₀ as the maximum acceleration of the setting values, for the step 705, the next The acceleration α _C1 , α _C1 = △ α + K · n · α ₀ (5) is calculated according to the formula. Δα, n, α ₀ are preset values.
Δα is a set value for giving an initial acceleration and is a minute amount corresponding to one pulse. For step 706, α _C2 = K · n · α ₀ (6) is calculated.

In the next step 707, the acceleration α thus calculated
_C (α _C1 , α _C2 ) is determined by α _C ≧ α ₀ , and when α _C <α ₀ , at step 708, α _S =
and alpha _C, when the α _C ≧ α ₀ sets the acceleration control value alpha _S as α _S = α ₀ at step 709.

FIGS. 8 and 9 show acceleration characteristics obtained by the above calculation. FIG. 9 shows acceleration characteristics when n = 1 and FIG. 9 shows acceleration characteristics when n = 2.

As shown, the acceleration control value alpha _S in the initial △
α, which linearly increases toward the vertex value n · α ₀ located at the middle point of the speed. When n> 1, the shape is limited by the maximum acceleration α ₀ and becomes trapezoidal. In addition, since the additional acceleration △ α is not applied at the acceleration end point, the characteristics are smooth.

The acceleration / deceleration calculation 48 is based on the command speed V _S
The set clamping speed V _CL, the position signal x is deceleration control waiting for the deceleration start position x _2. The deceleration α is calculated as a deceleration control value α _S ′ by the same calculation as shown in FIGS. 7 to 9.

Loop switching control unit 53, as shown in FIG. 10, waiting for the velocity V of the deceleration becomes constant low speed V _0, which is set as a relatively small value, and the position P ₁ at that time, the speed
When the point P ₁ is located before the point P ₂ when the point P ₂ is located before and after the point P ₂ at the intersection P ₂ between the intersection point V ₂ and the straight line 1 having a constant gradient passing through the target position, a command is issued to the acceleration / deceleration calculation command unit 48. A command signal S1 is output so that the speed V _S becomes the low speed V _0, and when the point P ₁ exceeds the point P ₂ , a deceleration command signal S 2 is output so as to decelerate and ride on the straight line l. Switch SW when
To output a loop switching signal S3.

By the operation of the switch SW, the inverters 14 and 15 are switched from the speed loop control unit 49 to the position loop control unit 50.

The position loop control unit 50 feeds back the position signal x and the speed signal V, performs feedback control of the position and speed, and performs feedback control of the position and speed so that the current speed is on the straight line 1 in FIG. . This feedback control may be a normal Bang / Bang control.

Then, the position loop control unit 50 determines that the position x is the target position x ₁
Then, the control is terminated, the brake B is applied just in case, and the operation is stopped here.

In the positioning device 42 of the above configuration, the deceleration start position x ₂ and the clamping speed V _CL according to the moving distance L is set, the eighth
The speed curve shown in FIG. 10 is formed by the acceleration calculation shown in FIG. 9 and FIG. 9, and high-speed and high-precision positioning can be performed by the speed at which the S-time curve is drawn in a speed-time relationship.

However, in the positioning device configured as described above, if the moving distance L is too small at the clamping speed _VCL and the deceleration distance ΔL of 1 m or less shown in FIG. 6, the set value _VCL , △ _L can not correspond, in this state, a situation where the movement position x ends up over the target position x ₁ is generated.

That is, as shown in FIG. 11, when the moving distance L is several centimeters, such as several centimeters, the positions x ₃ , x ₃ = 20% of the total moving distance L = x ₀ + 0.2L (7), for example, a position x corresponding to 40% of the total moving distance
₄ (not shown), whereas it should become a maximum speed commensurate with _{x 4 = x 0 + 0.4L ......} (8), the position
desired speed V _C = f (L) than the corresponding decrease in x _3, thereafter,
The speed gradually increases to approach the set clamping speed V _CL4 , and at the end of acceleration, a situation occurs in which 50% of the total travel distance exceeds 100%, let alone.

Such a small movement distance L occurs, for example, when a movement command is output to correct a position shift. More specifically, for example, when there is a relative displacement between the shelf 4 and the station 6 based on an assembly error of the shelf 4, this occurs when a position offset is given between the opposing shelf 4 and the station. is there.

Therefore, in this example, the positioning device 42 is provided with an acceleration / deceleration correction operation unit 51, and a new clamp speed V _CL4 ′ and a new deceleration distance △ L ₄ ′ are calculated by the processing of FIG.

In Figure 12, the clamp velocity V _CL4 step 1201 and 1202 is set, it is determined that it has reached the comparative position x _3, desired speed V _C at the time in step 1203
The difference ΔV between the current speed V and the current speed V is obtained by the following equation.

ΔV = V _C −V (9) Next, in step 1204, the speed difference ΔV is set to a reference value Δ
Compared to V ₀ , no processing is performed when the reference value △ V ₀ or less, but when the speed difference ΔV is larger than the reference value △ V ₀ ,
In step 1205, the correction values V _CL4 ′ and △ L ₄ ′ are obtained by the following equation.

V _CL4 ′ = f ₁ (△ V) (10) ΔL ₄ ′ = f ₂ (△ V) (11) In the equations (8) and (9), the functions f ¹ and f ₂ are the speed difference △ If the difference ΔV is large according to V, it indicates that a smaller clamping speed V _CL4 ′ and a deceleration distance _{ΔL 4} ′ are added.

In step 1206, the calculated clamp speed V _CL4 ′ and deceleration distance _{ΔL 4} are output to the acceleration / deceleration calculation command unit 48.

The acceleration / deceleration calculation command section 48 is provided with the clamp speed V _CL4 ′ input from the acceleration / deceleration correction calculation section 51 and the deceleration start position △ L ₄ ′.
On the basis of the deceleration start position x ₂ obtained from, performs acceleration and deceleration operation shown in FIG. 7 to 9 figures, the speed control shown in Figure 10 below. Hereinafter, the same applies to the processing contents of the loop switching control unit 53 and the position loop control unit 50.

In the present example, a discontinuous point is generated between the acceleration alpha _S computed using the current acceleration alpha and Figure 8 and Figure 9 at position x _3, running a small distance at a low speed In between, there is no discontinuity in speed and there is no risk of collapse.

[Effects of the Invention] As described above, since the present invention is a positioning device for an automatic warehouse as described in the claims, in the open loop, smooth high-speed movement can be performed by arbitrary speed control,
By forming a closed loop rarely before the target position, high-speed and high-precision positioning can be performed without collapse of the load.

[Brief description of the drawings]

FIG. 1 is a block diagram of a positioning device according to an embodiment of the present invention, FIG. 2 is a perspective view showing an external appearance of an automatic warehouse embodying the present invention, and FIG. 3 is incorporated in a control panel of the automatic warehouse. FIG. 4 is a block diagram showing a specific configuration example of a CPU board of the NC device shown in FIG. 3, and FIG. 5 is an x-axis representing each axis. FIG. 6 is an explanatory diagram showing a relationship between a target position and each control position, FIG. 6 is an explanatory diagram of table data for searching a clamp speed and a deceleration distance, FIG. 7 is a flowchart showing an acceleration calculation method, FIG. FIG. 9 is an explanatory diagram showing acceleration characteristics when n = 1 and n = 2. FIG. 10 is an explanatory diagram showing a speed characteristic, FIG. 11 is an explanatory diagram showing an acceleration state when the moving distance is short, and FIG. 12 is a flowchart showing a correction calculation method when the moving distance is short. 3… Carrier 4… Shelf 9… Fork 10… Lifter 48… Acceleration / deceleration calculation command unit 50… Position loop control unit 51… Acceleration / deceleration correction calculation unit 53… Loop switching control unit M (M _{L, M T, M F)} ...... AC motor x ₀ ...... current position K _1, K ₂ ...... parameter x ₁ ...... target position x ₂ ...... deceleration start position alpha _{S ......} acceleration control value V _CL ...... Clamping speed △ L …… Deceleration distance

Claims (1)

(57) [Claims] An automatic warehouse positioning apparatus comprising a multi-row multi-stage shelf and a transfer means for moving a load to each shelf position, wherein the transfer means is moved to each shelf position by driving an AC motor. the movement command unit for outputting a command signal to move the transfer means to a position command (x ₁₎ and (43), the position of the command of the movement command unit (43) (x ₁₎ and the moving means of the current A distance calculator (44) for calculating a moving distance (L) based on the position (x ₀ ); and table data on a relationship between the moving distance (L), the clamping speed (V _CL ) and the deceleration distance (ΔL). A clamp speed setting unit (45) for setting a clamp speed (V _CL ) corresponding to the moving distance (L) calculated by the distance calculation unit (44) and a deceleration distance setting for setting a deceleration distance (ΔL) Section (46), the position (x ₁ ) of the command and the deceleration distance setting section ( A deceleration start position setting section (47) for calculating a deceleration start position (x ₂ ) based on the deceleration distance (ΔL) set by (46); and a clamp speed set in the clamp speed setting section (45). V _CL ), the deceleration start position (x ₂ ) calculated by the deceleration start position setting section (47), the position calculation section (54)
The current position signal (x) calculated in step (5) and the speed calculation unit (5
Acceleration / deceleration calculation is performed according to the current speed signal (V) calculated in 2), and a predetermined speed command signal (α) is sent to the speed loop controller (49) so that the acceleration / deceleration (α) becomes a specified value. V _S ), an acceleration / deceleration calculation command section (48), a speed loop control section (49) for controlling the speed of the transfer means and a position loop control section (50) for performing position control, A position (P ₁ ) at which a small constant low speed (V ₀ ) where the speed (V) after deceleration is set is a straight line (1) representing a constant low speed line and a constant gradient speed passing through the target position. When it is before the intersection point (P ₂ ) with the position (P ₂ ), a command signal (S 1) for setting the command speed (V _S ) to the low speed (V ₀ ) is output to the acceleration / deceleration calculation command unit (48). ₁₎ is the intersection (P ₂₎ before the deceleration command signal (S2) so as to ride on the decelerating linear (1) when it exceeds the A loop switching control unit (53) for outputting to an acceleration / deceleration calculation command unit (48) and switching to control by a position loop control unit (50) when the speed (V) of the transfer means rides on the straight line (1); A desired speed (V _c ) determined that the clamp speed (V _c14 ) at the small movement distance (L) is set and that the comparison position (x ₃ ) has been reached within the small movement distance (L). (ΔV) between the current speed and the current speed (V), and when the speed difference (ΔV) is larger than the reference value (ΔV ₀ ), a smaller clamping speed and a reduced deceleration distance corresponding to the deceleration difference (ΔV) are calculated. An acceleration / deceleration correction operation unit (51) for calculating and outputting the small clamp speed and deceleration distance as correction values to the acceleration / deceleration operation command unit (48).