JPS6360895A - Hunting preventive method in horizontal movement of hung load of crane - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for preventing hunting of a suspended load during horizontal movement of the suspended load by a crane.

(Prior art and its problems) By simultaneously performing the lifting and raising operations of the boom of the crane and the winding/unwinding operations of the hoisting and lifting ropes suspended from the boom, it is possible to A control method for horizontally moving a suspended load is already known. Devices used for such control include, for example, Japanese Patent Laid-Open Nos. 49-71650 and 58-58.
There is a technique disclosed in No. 52186 and the like.

However, it is actually difficult to ideally adjust the relationship between the elevating and lifting motions of the boom and the winding/feeding motions of the hoisting/lowering rope, and hunting of the suspended load may occur during horizontal movement. It often occurs. Therefore, a technique for preventing hunting is desired, but it is difficult to completely eliminate the causes of hunting.

Therefore, it is important to detect early signs of hunting and thereby prevent the transition to a hunting state.
It is considered effective for preventing hunting.

However, from this standpoint, there has been no concrete method to effectively prevent hunting, and there is a problem that prevention of hunting during horizontal movement of suspended loads remains insufficient. Ta.

(Object of the Invention) The present invention is intended to overcome the above-mentioned problems in the prior art, and is intended to provide a crane that can detect early signs of hunting occurrence, thereby effectively preventing hunting of suspended loads. The purpose of the present invention is to provide a method for preventing hunting during horizontal movement of a suspended load.

(Means for Achieving the Object) In order to achieve the above-mentioned object, the present invention provides an elevation drive mechanism for a boom of a crane and a cable-shaped body suspended from the boom in response to an input operation from a boom operation input means. A drive control signal is given to the hoisting/up-down drive mechanism of the boom, thereby raising and raising the boom and hoisting and hoisting the cable-like body at the same time, thereby horizontally moving the load suspended from the cable-like body. Targeting the hunting prevention method, detecting the elevation angle of the boom by an elevation angle detection means, and determining whether a temporal change in the elevation angle includes a vibration component that satisfies a predetermined standard; When the vibration component is included, the drive signal is changed according to the degree of the vibration to prevent hanging.

However, the term "boom" in this invention includes a jib such as a jib crane.

(Example) The configuration and operation of a crane that prevents hunting according to an example of the present invention will be described below in the following sections: ``Overview of mechanical configuration,'' ``Configuration of hydraulic drive system,'' and ``Configuration of control device and anti-hunting operation.'' Explain in order.

Finally, a modification of this invention will be mentioned.

A. Overview of Mechanical Configuration of Crane FIG. 1 is a schematic external view showing an overview of the mechanical configuration of a crane that prevents hunting according to an embodiment of the present invention. In FIG. 1, this crane 1 is constructed as a tower crane, and a tower TW is attached to the upper part of a crane body 2. As shown in FIG. And this crane 1
is a jib (
boom) 3. In such a tower crane, the rigidity is relatively low due to the presence of the tower TW, and the present invention is particularly effective for such a low-rigidity crane.

On the other hand, one end of a jib elevating rope 4 is fixed to the tip of the jib 3, and the other end of the jib elevating rope 4 is attached to a jib elevating drum 5 installed inside the crane body 2 (pulled).
is wrapped around. Therefore, by rotating the jib elevating drum 5, the jib elevating rope 4 is wound/unrolled, and the jib 3 is moved in the direction indicated by the arrow α.
, (-α), and the height H of the tip changes.

On the other hand, a hook 7 is suspended from the tip of the jib 3 by a hoisting and lowering row 16. This winding and lowering row 16 is
It is wound around a hoisting and lifting drum 8 provided within the crane body 2. Therefore, by rotating the winding/lowering drum 8, the winding/lowering row 76 is wound up/feeded out, and thereby the hook 7 is raised and lowered in the vertical direction (7 directions shown in the figure). By simultaneously performing the lifting and raising movements of the jib 3 and the hoisting and lifting movements of the hook 7, the load 9 suspended from the hook 7 is leveled while maintaining the height h from the horizontal plane. Direction (X shown)
direction).

How to use: In addition to being equipped with an engine EG as a power source for the crane, the crane body 2 is also equipped with a control device @ 10 for controlling the crane, which will be described later, and an operation panel 11 for inputting operations by the operator. There is. Further, a jib elevation angle detector 12 is provided near the jib foot of the jib 3 to detect an elevation angle θ of the jib 3 from a horizontal plane. As the jib elevation angle detector 12, an inclinometer type sensor for detecting the ground angle (for example, one equipped with a freely movable part and an oil damper) is used.

Further, a rope winding/feeding amount detector 13 is attached to an idler sheave (not shown) that is provided near the tip of the jib 3 and guides the hoisting/up/down rope 6. The rope winding/feeding amount detector 13 is constituted by a rotary encoder or the like, and is for detecting the winding/feeding amount of the hoisting/lowering rope 6 from the rotation angle of the idler sheave.

B. Construction of Hydraulic Drive System FIG. 2 is a hydraulic circuit diagram showing the construction of a hydraulic drive system for raising and raising the jib 3 and hoisting and raising the hook 7. In FIG. 2, this hydraulic drive system includes engine EG (
Hydraulic pressure from the main hydraulic pump 21 (not shown in FIG. 2) is supplied to the jib elevation directional control valve 22a.
is applied to the jib elevation hydraulic motor 23a via the hydraulic motor 23a. This jib elevation hydraulic motor 23a is for rotationally driving the jib elevation drum 5 shown in FIG.

Further, the hydraulic pressure from the main hydraulic pump 21 is also applied to a hoisting/up/down hydraulic motor 23b for rotationally driving the hoisting/up/down drum 8 shown in FIG. 1 via a hoisting/up/down directional control valve 22b.

Of these control valves 22a, 22b, the pilot portion of the jib elevation control valve 22a is provided with respective secondary side circuits 24a of a jib-raising electromagnetic proportional pressure reducing valve 26a and a jib-lowering electromagnetic proportional pressure reducing valve 27a.

25a is connected. Similarly, the respective secondary side circuits 24b and 25b of the hoisting electromagnetic ratio side pressure reducing valve 26b and the hoisting lowering electromagnetic proportional pressure reducing valve 27b are connected to the pilot part of the hoisting/lowering directional control valve 22b. ing.

Among these, the primary side of the electromagnetic proportional pressure reducing valve 268.27a is the secondary side circuit 30a of the remote control valve 32a for elevating the jib,
31a, respectively.

This jib elevation/elevation remote control valve 32a is equipped with a pair of variable pressure reducing valves (not shown), and controls the secondary pressure to be applied to the secondary side circuit 30a or 31a according to the operating direction and operating amount of the jib operating lever 33a. It has the function of controlling.

In addition, the secondary side circuit 3 of this jib elevation remote control valve 32a
0a and 31a are provided with jib lever pilot pressure detectors 36 and 37 for detecting the respective secondary pressures. The jib lever pilot pressure detectors 36 and 37 can detect the operating direction and operating amount of the jib operating lever 33a.

On the other hand, the electromagnetic proportional pressure reducing valves 26b and 2 for lowering and lowering
The primary sides of 7b are connected to the secondary sides of electromagnetic switching valves 28 and 29, respectively. And these electromagnetic switching valves 28
．． On the primary side of 29, a corresponding one of the secondary circuits 30b and 31b of the remote control valve 32b for hoisting and up/down, and a secondary circuit 35 of the pilot hydraulic pump 34 driven by the engine EG are connected. Connected in a switchable manner. The remote control valve 32b for hoisting and lowering is the same as the remote control valve 32 for raising and lowering the jib.
Similarly to a, a pair of variable pressure reducing valves (not shown) are provided, and the secondary pressure applied to the secondary circuit 30b or 31b is controlled according to the operating direction and operating amount of the hoisting/lowering operating lever 33b. belongs to. In addition, in the figure, CV
indicates a check valve.

An outline of the drive operation of the hydraulic drive system having such a configuration during horizontal movement is as follows. That is, when horizontally moving the hanging load 9 in FIG. 1, first, a mode changeover switch (not shown) provided on the operation panel 11 in FIG. 1 is switched to the horizontal movement control mode. Then, the electromagnetic switching valves 28 and 29 in FIG. 2 are biased upward in the figure, and the hydraulic pressure from the secondary circuit 35 of the hydraulic pump 34 is applied to the primary side of the electromagnetic proportional pressure reducing valves 26b and 27b to the pylon 1. It will be done.

Therefore, at this time, the winding/lowering operation lever 33b
The operation becomes independent of drive control.

When the operator operates the jib operating lever 33a, hydraulic pressure is applied from the jib elevation remote control valve 32a to the electromagnetic proportional pressure reducing valves 25a, 27 according to the operating direction and operating amount.
given to the primary side of a.

Electromagnetic proportional pressure reducing valves 26a, 27a and 26b.

27b operate in response to control signals V and u (not shown in FIG. 2) from a control system, which will be described later, thereby changing the oil pressure in the secondary circuits 24a, 25a, 24b, and 25b. do. These oil pressures are applied to the respective pilot portions of the jib elevation direction control valve 22a and the hoisting and raising direction control valve 22b.

Then, the jib elevation direction control valve 22a is switched to the jib up (or jib down) position, and pressure oil from the main hydraulic pump 21 is supplied to the jib elevation hydraulic motor 23a. As a result, the hydraulic motor 23a rotationally accelerates, and the jib elevating drum 5 shown in FIG. 1 rotates. As a result, the jib elevation rope 4 shown in FIG. 1 is wound up or let out, and the jib 3 is raised or lowered.

On the other hand, the hoisting/lowering directional control valve 22b in FIG. It is supplied to the hydraulic motor 23b for hoisting and lifting. As a result, the hydraulic motor 23b rotates and accelerates, and the hoisting/up-down drum 8 shown in FIG. 1 rotates, so that the hoisting/up-down row 16 is wound up or fed out. As a result, the hook 7 is raised or lowered.

The horizontal movement of the suspended load 9 is realized by adjusting and controlling the relationship between the elevating motion of the jib 3 and the hoisting and hoisting motion of the seven hooks 7 using a control device, which will be described later.

Configuration and operation of C0 control device FIG. 3 is a block diagram showing the configuration of a control device 10 formed to realize an embodiment of the present invention. This control device @10 includes a jib elevation control system and a hoisting cargo vertical control system, of which the hoisting cargo vertical control system has a feedforward control system and a feedback control system. Further, this control system is provided with means for preventing hunting, corresponding to the features of the present invention.

The configuration and operation of these will be explained below.

(c-i) Jib elevation control system First, in the jib elevation control system, the detected value D1 of the jib lever pilot pressure detector 36,37 explained in FIG. 2 is used as a control input, and this input is multiplied by Vessel 4
Give to 2. Other inputs to this multiplier 42 include jib elevation suppression pattern data D2 (back) stored in the jib elevation suppression pattern storage device 41. ) is given. Then, a jib elevation signal D3 is obtained by multiplying the detected value D1 by this suppression pattern data D2. This jib elevation signal D4 is given to a multiplier 56, and in this multiplier 56, a control parameter setting device 5 to be described later
The limit signal S1 from 5 is multiplied to form the jib drive control signal 2, which is applied to the electromagnetic proportional pressure reducing valve 43 for elevating and elevating the jib. However, this electromagnetic proportional pressure reducing valve 43 for elevating and raising the jib corresponds to the proportional electromagnetic pressure reducing valve 26a for raising the jib and the proportional electromagnetic pressure reducing valve 27a for lowering the jib shown in FIG.

By applying such a jib drive control signal (2) to the jib elevation electromagnetic proportional pressure reducing valve 43, the jib elevation control signal shown in FIG. 3, which is configured by the jib elevation direction control valve 22a of FIG. The jib elevation drive system 44 operates based on the driving force of the engine EG. the result,
The elevating motion of the jib 3 is started in accordance with the operating direction and operating amount of the jib operating lever 33a shown in FIG.

Here, the jib elevation suppression pattern data D2 shown in FIG. 3 mentioned above will be explained. During the horizontal movement of the hanging load 9, hunting is most likely to occur during the period immediately after the horizontal movement is started. Therefore, in this embodiment, pattern data as shown in FIG. 4 is provided as the jib elevation suppression pattern data D2, with the elapsed time t from the start of horizontal movement as a parameter. Then, even if the operator suddenly operates the jib operating lever 33a at the start of horizontal movement and the detected value D1 of the jib lever pilot pressure detector 36-37 becomes a large value, the suppression pattern data D2 in FIG. By multiplying this detection value D1 by the value (ku1) of the rising portion R1, the jib elevation signal D3
is a smaller value than the detected value D1. Therefore, during the period corresponding to the rising portion R1 in FIG.
a.

Since the switching of the jib 22b is carried out gradually, the elevating and raising movements of the jib 3 are slow, which contributes to preventing hunting at the start of horizontal movement.

Then, after the horizontal movement starts, a certain amount of time t.

In the steady portion R2 after (Fig. 4) has elapsed, the pattern data D2 becomes "1", and the jib operating lever 3
The detected value D1 corresponding to the manipulated variable 3a becomes the jib drive control signal V as it is. However, in the description here, it is assumed that the limit signal s1 is 111 II.

Therefore, at the start of horizontal movement, the occurrence of hunting is suppressed by a slow jib elevation movement, and as time passes, the jib elevation is accelerated, and in steady state, the jib elevation movement is realized as intended by the operator. will be done. However, the prevention of hunting by this configuration does not correspond to the feature of the present invention, but is supplementary to the present invention. Hunting prevention according to the features of the present invention is achieved by the operation described below.

(C-2) Lifting up and down control Next, the hanging load up and down control system will be explained. As described above, this hoisting vertical control system has a feedforward control system and a feedback control system. this house,
In the feedforward control system, first, the detected value D1 detected by the jib lever pilot pressure detector 36, 37 shown in FIG. 3 is given to the multiplier 45. As another input of this multiplier 45, feedforward rising pattern data D4 stored in a feedforward rising pattern storage 46 is applied.

This feedforward start-up pattern data D4 is data prepared to suppress a sudden change in motion at the start of horizontal movement, similar to the previously described jib elevation suppression pattern D2, and is data prepared as described above for time t. It has a pattern as shown in FIG. Then, data D5 obtained by multiplying these data D and D by a multiplier 45 is provided to an arithmetic unit 47.

The value of the jib elevation angle θ detected by the jib elevation angle detector 12 is also input to this calculator 47 . Then, the calculator 47 calculates K F = K ((CO
The value of Sθ-(1) is calculated and obtained, and this value K is multiplied by the data D5 to obtain the feedforward fk ut.

The reason why the factor "CO8θ" is included in the above equation (1) is because the amount of elevation of the tip of the jib when the jib elevation angle θ changes to (θ + Δθ) is proportional to COSθ. This is due to the fact that in order to compensate for this and realize horizontal movement, the amount of winding/feeding out of the winding/lowering row 16 must also be made proportional to COS θ.

The feedforward signal U[ obtained in this way is added to the feedback signal ub in an adder 48 to form the winding/up/down drive control signal U. This winding/up/down drive control signal U is then given to the shipping winding/up/down electromagnetic pressure reducing valve 49 as a pressure reducing control signal.

This electromagnetic pressure reducing valve 49 for lifting and lowering hoisting is composed of the electromagnetic proportional pressure reducing valve 26b for soil loading and the electromagnetic proportional area pressure changing valve 27b for lowering hoisting shown in FIG.
corresponds to

The hoisting hoisting vertical drive system 50 shown in FIG. 3, which is constituted by the hoisting/up-down directional control valve 22b in FIG. 2, the hoisting/up-down hydraulic motor 23b, etc. , the winding/lowering row 76 shown in FIG. 1 is caused to wind/unwind.

The above is the configuration and operation of the feedforward control system.

Next, the feedback control system will be explained.

In this feedback control system, first, the actual amount l of the winding/feeding amount of the winding/lowering rope 6 is detected by the rope winding/feeding amount detector 13 shown in FIG. On the other hand, the value of the jib elevation angle θ detected by the jib elevation angle detector 12 described above is also given to the calculator 51.

This calculator 51 calculates a target value 1' of the winding/feeding amount of the hoisting/lowering rope 6 required to maintain the suspended load 9 at a predetermined height h, based on the value of the jib elevation angle θ. Calculation formula: Calculate using the % formula (%). However, 1. is the length ib of jib 3, and θ. is the jib elevation angle at the start of horizontal movement.

The target value 1' obtained in this way and the actual winding/feeding amount 1 detected as described above are calculated by the subtractor 5.
2, and the subtracter 52 calculates these deviations: Δhl' l (3).

This deviation Δh is input to the arithmetic unit 53, and the arithmetic unit 53
In , the sum of the proportional control component: Δh and the integral control component: KIfΔhdt=KIΔh/s is determined. However, S represents a Laplace operator. The feedback amount Ub obtained in this way is added to the feedforward Nuf in the adder 48 as described above, and the winding/up/down control is executed based on the sum U.

That is, here, feedback control is performed based on the deviation of the target value 1' of the rope winding/feeding amount from the actual value l, and by combining the feedforward control described above and this feedback control, the boom 3 is controlled. The winding/unwinding of the rope 6 for winding up and down is performed in accordance with the up-and-down movement. As a result, the suspended load 9 is moved horizontally.

(C-3) Hunting Prevention Control System Next, a hunting prevention control system provided in accordance with the features of the present invention will be explained. One component of this anti-hunting control system is the hunting detector 54 shown in FIG. The hunting detector 54 inputs the jib elevation angle θ detected by the jib elevation angle detector 12, and detects signs of occurrence of hunting based on its temporal change.

That is, first considering an ideal situation in which hunting does not occur, the jib elevation angle θ changes linearly with respect to time t as shown in FIG. 5(a). Also, the angular velocity ω (=dθ/dt
) is a constant value ω as shown in FIG. 5(b). becomes.

However, when hunting occurs in the crane, the jib elevation angle θ changes with time while oscillating, as shown as angle θ1 in FIG. 6(a). In addition, in the case of cranes with low rigidity, such as the tower crane considered here, bending vibrations of the tower TW etc. are added, so jib elevation angle detection is performed to determine the jib elevation angle θ based on the ground angle. The detected value of the device 12 is shown in FIG. 6(a).
It has a larger vibration amplitude, as shown as θ2 in .

Then, as hunting begins to occur and its amplitude gradually increases, a portion will eventually occur where the direction (sign) of the temporal change in the jib elevation angle θ2 as a detected value is reversed. In the example of FIG. 6(a), even though the jib 3 is to be elevated in a direction in which the elevation angle θ increases as time t passes,
In the illustrated portion RV, the detected elevation angle θ2 decreases with respect to time t, as indicated by the tangent CL.

Therefore, by detecting such a reversal of change in the detected elevation angle value θ2, it is possible to detect signs of occurrence of hunting.

An example of this situation observed from the temporal change of the angular velocity ω is shown in FIG. 6(b). In FIG. 6(b'), the actual elevation angular velocity is expressed by ω1, and the elevation angular velocity ω2 obtained as a detected value is expressed, respectively. This figure 6 (
As shown in a), when observation is performed using the angular velocity ω, the angular velocity ω2 as the detected value is the retrograde portion RV
is a negative value. Therefore, if a portion where ω2<0 exists, it can be determined that there is a sign of hunting occurrence.

However, although this embodiment is based on the condition of ω2〈O as described above, in general, the reference value (threshold value) ωth as shown in FIG. 6(b) is arbitrarily set, and the angular velocity is A sign of the occurrence of hunting can be detected depending on whether the detected value ω2 has a vibration component that reaches such a reference value θ)th. This embodiment corresponds to the case where "0" is set as ω1h.

Next, the operation of the control parameter setting device 55 shown in FIG. 3 to change the drive control signal based on the hunting detection result described above will be explained with reference to FIGS. 7 and 3. However, here, it is assumed that the control parameter setting device 55 is configured by a microcomputer or the like.

First, in step S1 of FIG. 7, a count value I of a counter (not shown) set in the control parameter setting device 55 is set to a value (N-1) greater than a predetermined positive integer N by 1. -1) is loaded. This integer N is determined by the jib 3 to prevent hunting, as will be seen from the operation described later.
It also has the role of specifying the time until the drive starts again when the drive of the winding up/down row 16 is once stopped. In this step S1, the third
As the feedback gain in the calculator 53 shown in the figure, o is set to a predetermined steady value, and this steady value o is transferred to the calculator 53.

Furthermore, as the limit signal S1 given to the multiplier 56,
The maximum value II II I+ corresponding to non-suppression is output.

As a result, the calculator 53 performs a feedback calculation in a steady state, and the elevation drive control command signal V becomes equal to the jib elevation signal D3.

In the next step S2 in FIG. 7, the angle θ (accurately θ2) detected by the jib elevation angle detector 12 is input to the hunting detector 54 described above. Then, in step S3, it is determined whether or not there is a reversal in the change in angle θ based on the criteria described above.

If no reversal has occurred, the process advances to step S4, where the count value I of the counter is incremented, and then step S4 is performed.
5, the count value I and the integer N are compared. After the start of horizontal movement, if hunting does not occur even by - degrees, the above steps 81 to S4 are passed through as is.
The count value ■ remains <N+1). Therefore, the determination in step S5 is 'NO', and step S2
Return to.

Assume that while these operations are being repeated, signs of hunting begin to appear in the crane, and the temporal change in elevation angle reverses. Then, the process moves from step 3 to step S7, where the counter is cleared and becomes I=0.

Then, in the next step S8, the retrograde amount Ai of the angular velocity ω2 shown in FIG. , -1 is determined. Here, the reason why the control period T is considered as a time unit = 24 - is because hunting occurs when this control period T is used as a vibration period. Also, this step S8
For comparison in , the previous retrograde amount A1-1 is stored in a memory (not shown) in the control parameter setting device 55.

In this step S8, when retrograde movement occurs for the first time, or even if retrograde movement continues to occur, the amount of retrograde movement A is gradually decreasing, the judgment here is 'NO' and the process proceeds to step S2. and return.

On the other hand, when the amount of retrograde motion is increasing, the process proceeds from step S8 to step S9, and the feedback gain and limit signal Sl are changed to values corresponding to the amount of retrograde motion A at that time. Examples of patterns for this change are shown in FIG. 8, of which (a) shows a change pattern for the feedback gain, and (b) shows a change pattern for the limit signal S1. These are stored in a memory (not shown) in the control parameter setting device 55 in a look-up table format. However, instead of using the table method, calculations according to this function form may be performed each time. As can be seen from this figure, these change patterns are, as a whole, a decreasing function with respect to the retrograde amount A. Therefore, for example, if the retrograde MA is A1, i is the feedback gain KP, S is the limit signal Sl,
are given respectively.

Therefore, the feedback gain KP and limit signal S1 are set to these values by 1. However, as is clear from Fig. 8, KPi<KPO・S′<
It is 1. Therefore, both the elevation drive control signal V and the hoisting vertical drive control signal U shown in FIG. . Therefore, the operating speed of the jib 3 and the hoisting/lowering row 16 shown in FIG. 1 is reduced, and the hunting that has begun to occur is subdued.

However, if the backward movement amount A continues to increase due to such a reduction in drive output, step S in FIG.
9, the process returns to step S2, and then proceeds to step S9 again, where the gain KP and limit signal S1 are changed again based on the new retrograde amount A, +1. In this case, since it was determined in step S8 that the retrograde amount Ai+1 is larger than the previous retrograde amount A, as shown in FIG.
1) and the limit signal S・ is equal to the previous gain by 1
1+1 and the limit signal S.

Therefore, the drive control signal V for preventing hunting,
By further decreasing u and repeating this operation, the hunting that has begun to occur is attenuated.

However, it is conceivable that hunting may not be attenuated even if the drive outputs of the jib drive system 44 and the load hoist vertical drive system 50 are successively reduced. Therefore, in this embodiment, each change characteristic line shown in FIGS. 8(a) and 8(b) corresponds to a predetermined retrograde amount A. The value is set to "0". Therefore, if hunting does not attenuate easily, the amount of retrograde movement A increases to more than Ao, and the gain and limit signal S1 become 0''.Then, the drive of the jib 3 stops, and accordingly The winding up and down movement of the winding up and down row 16 is also stopped.In other words, when it is difficult to attenuate the hunting, the horizontal movement movement is stopped immediately,
Hunting is forcibly stopped.

In this way, when the hunting is attenuated by reducing the gain and the limit signal S1 to a finite value or "O", the processing loop of FIG. 7 returns from step S8 to step S2. Further, when the vibration is attenuated to such an extent that no retrograde movement occurs, the process moves from step S3 to step S4. Then step S
4, the count value I is sequentially incremented from .largecircle.'', and finally becomes I-(N+1>).

At this point, the process moves from step S5 to step S6, where o is given to the steady-state value as the gain, and the maximum value 111 I+ is given as the limit signal S1. In other words, after no retrograde occurs -28=, if the state in which no retrograde occurs continues for a period (NT) that is N times the control period T, the state returns to the initial state (the state specified in step S1). It turns out.

FIG. 9 shows an example of temporal changes in the eight quantities due to such an operation. In this example, first, the gain and the limit signal SJ! , are set to a steady value KPo and a maximum value 11111, respectively (time 11). after that,
This state continues for a while, but at time t2, the amount of backward movement A of the detected angular velocity value ω2 of the jib rises to a finite value ((a) in the same figure), and at time = ('t2+T), the amount of backward movement A further increases. Then, the gain ((b) in the same figure) and the limit signal S1 ((c) in the same figure) start to decrease.

However, at time (t 2 + 27), retrograde fiA
begins to decrease, so the gain and limit signal S
j! The drop in value stops and this state will be maintained for a while. After that, at time t3, the retrograde amount A starts to increase again, but in this case, the gain and the limit signal S1 are lowered to 0'', and the drive is temporarily stopped.This state also continues for a while, The above-mentioned count value I is incremented sequentially, but since the retrograde MA takes a finite value again at time t4, this count value ■ is cleared again. T
This occurs because the vibration of W is not completely damped.

After time (t4+T), the count value I is incremented again from 0'', and when I-(N+1>), the gain and limit signal Sl are changed to their respective initial values K 1 "1". It has returned to O.

By repeating such operations, signs of the occurrence of hunting can be discovered at an early stage, and based on this, the growth of hunting can be prevented.

D. Modifications Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and for example, the following modifications are possible.

■ In the above embodiment, the occurrence of hunting was detected based on whether or not the jib elevation angular velocity ω2 reached a fixed reference value ωth ('O'' in the above embodiment), but the above reference value ω1
□ is the command angular velocity ω. It may be variable depending on the size (FIG. 6(b)). In this case, for example, if Δω is a predetermined value and ωth is determined so that ωth − ω0 − Δω, then the angular velocity ω
A state in which the signal begins to vibrate with an amplitude of 60 or more can be determined as "hunting occurring."

(2) In the above embodiment, hunting prevention is performed based on the detected value ω2 by utilizing the property that the actual angular velocity ω1 and the detected value ω2 have different values, and the latter has a larger amplitude than the former. This allows the occurrence of hunting to be detected at an early stage. However, the present invention is applicable even if the rigidity of the crane is not so low and ω and ω2 do not differ much. In this case, similar detection is possible by setting the reference value ωth to a positive value instead of "0", for example.

(2) The method of dealing with hunting after it is detected is not limited to the method of lowering the gain or limit signal S1 as described above. The control parameters of the equation may be changed, or a driving component having a phase opposite to the hunting phase may be added. However, according to the above embodiment, hunting can be effectively prevented with a simple configuration.

■ It does not matter whether the upper and lower winding cords formed of ropes, wires, etc. are for main winding or auxiliary winding. Furthermore, "shipping" in this invention includes cargo held in packets.

(Effects of the Invention) As explained above, according to the present invention, it is determined whether or not the temporal change in the elevation angle of the boom (jib) includes a vibration component exceeding a predetermined standard. When a vibration component is included, the crane drive signal is changed according to the degree of vibration, so signs of hunting can be detected early, thereby effectively preventing hunting of suspended loads. can do.

[Brief explanation of drawings]

Fig. 1 is a schematic external view of a crane to which an embodiment of the present invention is applied, Fig. 2 is a hydraulic circuit diagram of the hydraulic drive system of the crane shown in Fig. 1, and Fig. 3 is a diagram of the control system of the embodiment. 4 is an explanatory diagram of the suppression pattern, FIGS. 5 and 6 are explanatory diagrams of the hunting detection principle, FIG. 7 is a flowchart showing the operation of the embodiment, and FIG. 8 is an illustration of the feedback gain and suppression signal. FIG. 9 is a time chart showing temporal changes in various quantities according to the embodiment. 1... Crane, 2... Crane body, 3...
...Jib, 4...Jib elevation rope, 6...
- Rope for hoisting and lifting, 9... Hanging load, 12... Jib elevation angle detector, 31... Main hydraulic pump, 22a... Jib elevation direction control valve, 22b... Hoisting and elevation direction Control valve, 26a, 26b, 27a, 27'o... Solenoid proportional pressure reducing valve, 32a, 32b... Remote control valve, 33a... Jib operating lever, 33b... Hoisting/up/down operating lever, 36.37 ... Jib lever pilot pressure detector, 54... Hunting detector, 55... Control parameter setting device, TW... Tower

Claims (3)

[Claims] (1) In response to an input operation from the boom operation input means,
A drive control signal is applied to a crane boom elevating/elevating drive mechanism and a hoisting/raising/lowering drive mechanism for a cable-shaped body suspended from the boom, thereby causing the boom to be simultaneously hoisted and hoisted. The method for preventing hunting when horizontally moving a load suspended from the cable-shaped body includes detecting the elevation angle of the boom by an elevation angle detection means, and detecting a predetermined value based on a temporal change in the elevation angle. It is characterized in that it is determined whether or not a vibration component that satisfies a standard is included, and when the vibration component is included, the drive signal is changed according to the degree of the vibration to prevent hunting. ,
A method for preventing hunting during horizontal movement of a crane's suspended load. (2) The method for preventing hunting in horizontal movement of a suspended load of a crane according to claim 1, wherein the criterion is whether or not the temporal change in the elevation angle includes a retrograde component. (3) In the horizontal movement of a suspended load of a crane according to claim 1 or 2, the change in the drive control signal is performed by changing a control parameter in the control of the horizontal movement. How to prevent hunting.