JPH0357028B2 - - Google Patents

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/feeding operations of the hoisting/uploading rope suspended from the boom, it is possible to suspend the hoisting/uploading rope. Control methods for horizontally moving a lifted or lowered load are already known. As devices used for such control, there are techniques disclosed in, for example, Japanese Patent Application Laid-Open Nos. 49-71650 and 58-52186.

However, it is difficult in practice to ideally adjust the relationship between the lifting and raising movements of the boom and the winding/feeding movements of the hoisting/lowering rope.
Hunting of suspended loads often occurs during horizontal movement operations. Therefore, a technique for preventing hunting is desired, but it is difficult to completely eliminate the causes of hunting. For this reason, it is considered effective for hunting prevention to detect early signs of hunting occurrence and thereby prevent transition to the hunting state.

However, from this standpoint, there has been no concrete method to effectively prevent hunting, and the problem remains 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 provides a method for detecting 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 of a crane.

(Means for Achieving the Object) In order to achieve the above object, the present invention provides a mechanism for elevating and elevating the boom of a crane and a cable suspended from the boom in response to an input operation from a boom operation input means. A drive control signal is given to a hoisting/up-down drive mechanism of the body, thereby simultaneously raising and raising the boom and hoisting and hoisting the cable-like body, thereby horizontally moving the load suspended from the cable-like body. A method for preventing hunting in which a temporal change in the elevation angle of the boom is detected, and the temporal change includes a retrograde component, and the retrograde component is larger than a predetermined value. Further, the hunting is prevented by changing the drive signal according to the amount of the retrograde component and reducing the driving speed of the boom and the rope-shaped body in the up and down winding.

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

Moreover, the above-mentioned "reducing the drive speed" includes the case where the drive is completely stopped.

(Example) The configuration and operation of a crane that prevents hunting according to an example of the present invention will be described below in ``Outline of Mechanical Configuration'', ``Configuration of Hydraulic Drive System'', and ``Configuration of Control Device and Hunting Prevention Operation''. Explain in this 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 Figure 1,
This crane 1 is configured as a tower crane, and a tower TW is installed on the top of the crane body 2.
is installed. And this crane 1
is equipped with a jib (boom) 3 attached to the tip of the tower TW so that it can be raised and raised freely. 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 wound around a jib elevating drum 5 provided inside the crane body 2. has been done.
Therefore, by rotating the jib elevating drum 5, the jib elevating rope 4 is wound/unrolled, and the jib 3 is thereby elevated as shown by arrows α and (-α). However, 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 rope 6 for hoisting and lifting. This hoisting/up-down rope 6 is wound around a hoisting/up-down drum 8 provided within the crane body 2. Therefore, by rotating the winding/up-down drum 8, the winding/up-down rope 6 is wound up/reeled out, and thereby the hook 7 is moved up and down in the vertical direction (Z direction in the figure). And jib 3
By simultaneously performing the lifting and raising movements of the hook 7 and the hoisting and lifting movements of the hook 7, the load 9 suspended from the hook 7 can be moved in the horizontal direction (while maintaining the height h from the horizontal plane). X shown
direction).

On the other hand, the crane body 2 is equipped with an engine EG as a power source for the crane.
A control device 10 for performing controls to be described later and an operation panel 11 for inputting operations by an operator are also attached. Also, a jib elevation angle detector 12 is installed near the jib foot of the jib 3 to detect the elevation angle θ of the jib 3 from the horizontal plane.
is provided. This jib elevation angle detector 1
As No. 2, an inclinometer-type device (for example, one equipped with a freely movable part and an oil damper) that detects the ground angle 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 rope 6 that is not needed for hoisting.
The rope winding/feeding amount detector 13 is constituted by a rotary encoder or the like, and is used to detect the winding/feeding amount of the hoisting/up-down rope 6 from the rotation angle of the idler sheave.

B. Configuration of Hydraulic Drive System FIG. 2 is a hydraulic circuit diagram showing the configuration 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 a main hydraulic pump 21 that is rotationally driven by an engine EG (not shown in FIG. 2).
Hydraulic pressure is applied to the jib elevation hydraulic motor 23a via the jib elevation direction control valve 22a. This jib elevation hydraulic motor 23a is
This is for rotationally driving the jib elevation drum 5 shown in FIG. In addition, the main hydraulic pump 21
The hydraulic pressure is also applied to the hoisting/up/down hydraulic motor 23b for rotationally driving the hoisting/up/down drum 8 shown in FIG. 1 via the hoisting/up/down directional control valve 22b.

Among these control valves 22a, 22b, the pilot part of the jib elevation control valve 22a has secondary side circuits 24a, 24a and 24a, respectively, for a jib raising solenoid proportional pressure reducing valve 26a and a jib lowering solenoid proportional pressure reducing valve 27a. 25a is connected. Similarly, the respective secondary side circuits 24b and 25b of the hoisting electromagnetic proportional pressure reducing valve 26b and the hoisting down electromagnetic proportional pressure reducing valve 27b are connected to the pilot part of the hoisting/lowering directional control valve 22b. There is.

Among these, the electromagnetic proportional pressure reducing valves 26a, 27
The primary side of a is connected to the secondary side circuits 30a and 31a of the jib elevation remote control valve 32a, respectively. This jib elevation remote control valve 32a is
It is equipped with a pair of variable pressure reducing valves (not shown), and depending on the operating direction and operating amount of the jib operating lever 33a, the secondary side circuit 30a or 31a is
It has the function of controlling the secondary pressure applied to the

Further, the secondary side circuits 30a and 31a of the remote control valve 32a for raising and lowering the jib are provided with jib lever pilot pressure detectors 36 and 37 for detecting the respective secondary pressures. And this jib lever pilot pressure detector 3
6 and 37, the operating direction and operating amount of the jib operating lever 33a can be detected.

On the other hand, the primary side of the electromagnetic proportional pressure reducing valves 26b and 27b for hoisting and hoisting is an electromagnetic switching valve 28,
29, respectively. And, on the primary side of these electromagnetic switching valves 28, 29, a secondary side circuit 3 of a remote control valve 32b for winding/up/down is connected.
A corresponding one of the pumps 0b and 31b is switchably connected to a secondary circuit 35 of a pilot hydraulic pump 34 driven by the engine EG. The hoisting/lowering remote control valve 32b, like the jib elevation/elevation remote control valve 32a, is equipped with a pair of variable pressure reducing valves (not shown), and the secondary This is for controlling the secondary pressure applied to the side circuit 30b or 31b. 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 suspended load 9 of FIG. 1, first, a mode changeover switch (not shown) provided on the operation panel 11 of 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 diagram, and the secondary circuit 3 of the pilot hydraulic pump 34 is
The hydraulic pressure from 5 is applied to the electromagnetic proportional pressure reducing valves 26b and 27b.
is given to the primary side of Therefore, at this time, the operation of the winding/up/down operation lever 33b becomes irrelevant to drive control.

When the operator operates the jib operation lever 33a, hydraulic pressure corresponding to the direction and amount of operation is applied from the jib elevation remote control valve 32a to the primary sides of the electromagnetic proportional pressure reducing valves 26a and 27a.

Electromagnetic proportional pressure reducing valves 26a, 27a and 26
b, 27b operate in response to control signals V, u (not shown in FIG. 2) from a control system, which will be described later, thereby controlling the secondary circuits 24a,
The oil pressure in 25a, 24b, 25b changes.
These oil pressures are supplied to the jib elevation direction control valve 22a.
and to each pilot portion of the hoisting/lowering directional control valve 22b.

Then, the jib elevation direction control valve 22a is switched to the jib up (or jib down) position, and the hydraulic pressure 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. is supplied to the hoisting/lowering hydraulic motor 23b. As a result, the hydraulic motor 23b rotates and accelerates, the hoisting/up-down drum 8 shown in FIG. 1 rotates, and the hoisting/up-down rope 6 is wound up or let out. As a result, the hook 7 is raised or lowered.

Then, the horizontal movement of the suspended load 9 is realized by adjusting and controlling the relationship between the lifting and raising movements of the jib 3 and the hoisting and lifting movements of the hook 7 using a control device that will be described later. However, in these operations, the hydraulic motors 23a, 23b (therefore, the boom elevating drum 5 and the hoisting/lowering drum 8)
The rotational speed is defined by the magnitude of the drive control signals V, u given to the electromagnetic proportional pressure reducing valves 26a, 27a and 26b, 27b.

C. Configuration and Operation of 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 is equipped with a jib elevation control system and a hoist up/down control system, of which the hoist up/down 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-1) Jib elevation control system First, in the jib elevation control system, the detected value _D1 of the jib lever pilot pressure detectors 36 and 37 explained in FIG. 2 is used as a control input, and this input is It is applied to the multiplier 42. As another input of this multiplier 42, jib elevation suppression pattern data D ₂ (described later) stored in the jib elevation suppression pattern storage device 41 is given. Then, a jib elevation signal _D3 is obtained by multiplying the detection value _D1 by this suppression pattern data _D2 . This jib elevation signal _D4 is given to a multiplier 56,
In this multiplier 56, a limit signal Sl from a control parameter setter 55, which will be described later, is multiplied by the jib drive control signal V, which is then applied to the electromagnetic proportional pressure reducing valve 43 for elevating the jib. However, this electromagnetic proportional pressure reducing valve 43 for elevating the jib
This corresponds to the jib-raising proportional electromagnetic pressure reducing valve 26a and the jib-lowering electromagnetic proportional pressure reducing valve 27a shown in FIG.

By giving such a jib drive control signal V to the jib suppression electromagnetic proportional pressure reducing valve 43, the jib elevation direction control valve 22a in FIG.
The jib elevating and elevating drive system 44 shown in FIG.
However, it operates based on the driving force of the engine EG.
As a result, the jib operating lever 33a in FIG.
The elevating motion of the jib 3 is started according to the operating direction and operating amount.

Here, the jib elevation/height 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, at the start of horizontal movement, the operator suddenly operates the jib operating lever 33a and the jib lever pilot pressure detector 3
Even if the detected value D ₁ of 6 and 37 becomes a large value, the value (<1) of the rising portion R ₁ of the suppression pattern data D ₂ in FIG. 4 is the detected value D ₁
jib elevation signal by multiplying by
D ₃ is a smaller value than the detected value D ₁ . For this reason, the directional control valves 22a and 22b are gradually switched during the period corresponding to the rising portion _R1 in FIG. Contributes to prevention of hunting.

Then, after starting the horizontal movement, for a certain amount of time
In the steady portion R ₂ after t ₀ (Fig. 4) has elapsed, the pattern data D ₂ becomes “1”,
The detected value _D1 corresponding to the operation amount of the jib operating lever 33a becomes the jib drive control signal V as it is. However, in the description here, it is assumed that the limit signal Sl is "1".

Therefore, at the start of horizontal movement, the occurrence of hunting is suppressed by slowly raising and lowering the jib, and as time passes, the raising and lowering of the jib accelerates, and in a steady state, the raising and lowering of the jib is performed as intended by the operator. will be realized. 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 characteristics of the present invention is achieved by the operation described below.

(C-2) Hoisting cargo vertical control system Next, the hoisting cargo vertical control system will be explained. As mentioned above, this hoist up/down control system has a feedforward control system and a feedback control system. Among these, in the feed forward control system, first, the third
The gib lever pilot pressure sensor 36 shown in the figure
The detection value D ₁ detected by 37 is applied to a 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 feed forward start-up pattern data D ₄ is the jib elevation suppression pattern D ₂ described above.
Similarly, this data is prepared to suppress sudden changes in motion at the start of horizontal movement, and has a pattern as shown in FIG. 4 described above with respect to time t. Then, data D ₅ obtained by multiplying these data D ₁ and D ₄ by a multiplier 45 is given 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 the value of K _F =K _ff cosθ (1) based on the feed forward gain K _ff and the jib elevation angle θ, and calculates this value K _F as data. _D5
Find the feed forward amount u _f by multiplying by .

Note that the factor "cos θ" is included in equation (1) above because the jib elevation angle θ is (θ
+Δθ), the amount of elevation of the tip of the jib is proportional to cosθ, so in order to compensate for this and achieve horizontal movement, the amount of winding/unwinding of the hoisting/up/down rope 6 must also be equal to cosθ. This is due to the fact that it has to be proportionate.

The feed forward amount u _f thus obtained is added to the feedback amount u _b in an adder 48 to form the winding/up/down drive control signal u. The hoisting/up/down drive control signal u is then given to the hoisting/up/down electromagnetic pressure reducing valve 49 as a pressure reducing control signal. This electromagnetic pressure reducing valve 49 for hoisting up and down is the same as the electromagnetic proportional pressure reducing valve 26 for hoisting shown in FIG.
b and the lowering electromagnetic proportional pressure reducing transformer 27b.

The hoisting vertical drive system 50 shown in FIG. 3, which is composed of the hoisting/up-down directional control valve 22b in FIG. 2, the hoisting/up-down hydraulic motor 23b, etc. Based on this, the winding/unwinding rope 6 shown in FIG. 1 is caused to wind up/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 rope winding/feeding amount detector 13 shown in FIG.
The actual amount l of the feeding amount is detected. 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.

In this calculator 51, this jib elevation angle θ
For the value of , calculate the target value l' of the winding/unwinding amount of the hoisting/lowering rope 6 required to maintain the suspended load 9 at a predetermined height h. Formula: l'=l _jib (sinθ− sinθ ₀ ) ...calculate using (2). However, l _jib is the length of the jib 3, and θ ₀ is the elevation angle of the jib at the start of horizontal movement.

The target value l' obtained in this way and the actual winding/unwinding amount l detected as described above are given to a subtractor 52, and in this subtractor 52, the deviation between them is calculated by: Δh =l'-l...(3) is obtained.

This deviation Δh is input to the calculator 53, which calculates the sum of the comparison control component: KpΔh and the integral control component: K _I ∫Δhdt=K _I Δh/s. However, s represents a Laplace operator. The feedback amount u _b thus obtained is added to the feedback amount u _f in the adder 48 as described above, and the winding/up/down control is executed based on the sum u.

Note that the calculator 53 determines whether it is horizontal retraction (beam raising) or horizontal extrusion (boom lowering) based on the boom lever pressure detection value _D1 , and in the case of horizontal extrusion, the above-mentioned boom back signal u _b It also has a function to invert the sign of and output it. During horizontal extrusion, the electromagnetic proportional pressure reducing valve 26b for hoisting the load, and
This is related to the fact that the electromagnetic proportional pressure reducing valve 27b for lower hoisting cargo is operated during horizontal retraction. That is, for example, when the height of the suspended load 9 becomes higher than the target value, it is necessary to increase the "lowering amount" of the rope 9 for hoisting and lowering during horizontal retraction, but the "hoisting amount" during horizontal extrusion must be increased. This is because it is necessary to reduce the It is well known that horizontal retraction and horizontal extrusion are reverse operations.

That is, here, feedback control is performed based on the deviation between the target value l' of the rope winding/unwinding amount and the actual value l, and by combining the already described feedback control and this feedback control, , the winding/unwinding of the hoisting/up-down rope 6 is performed in accordance with the raising and raising movements of the boom 3. 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 described.
One component of this anti-hunting control system is the hunting detector 54 shown in FIG. This hunting detector 54 inputs the jib elevation angle θ detected by the jib elevation angle detector 12, and detects a sign 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. 5a. Also, the angular velocity ω (=dθ/dt) found from this jib elevation angle θ is:
As shown in FIG. 5b, the constant value ω ₀ is obtained.

However, when hunting occurs in the crane, the jib elevation angle θ changes to an angle θ ₁ as shown in Figure 6a.
As shown, it begins to change while oscillating over time. 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 determined by determining the gir elevation angle θ based on the ground angle. Vessel 1
A detected value of 2 will have a larger vibration amplitude, as shown as θ ₂ in FIG. 6a.

Then, as hunting begins to occur and the amplitude gradually increases, a portion will eventually occur where the direction (sign) of the temporal change in the jib elevation angle θ ₂ as a detected value is reversed. . In the example of Figure 6a,
Although the jib 3 is intended to be elevated in a direction in which the elevation angle θ increases with the passage of time t, in the illustrated portion RV, the elevation angle changes with respect to time t, as shown by the tangent CL. This results in a decrease in the detected value θ ₂ . Therefore, by detecting such a reversal of change in the detected elevation angle value θ ₂ , 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. 6b. In FIG. 6b, the actual elevation angular velocity is expressed by ω ₁ and the elevation angular velocity ω ₂ obtained as a detected value. As can be seen from FIG. 6a, when observation is performed using the angular velocity ω, the angular velocity ω ₂ as a detected value is a negative value in the retrograde portion RV. Therefore, if there is a portion where ω ₂ <0, it can be determined that there is a sign of hunting occurring.

Although this embodiment is based on the condition of ω ₂ <0 as described above, in general, the reference value (threshold) ω _th as shown in FIG. 6b is arbitrarily set, and the angular velocity is A sign of the occurrence of hunting can be detected depending on whether the detected value ω ₂ has a vibration component that reaches such a reference value ω _th . This embodiment corresponds to the case where ω _th is set to “0”.

Next, the control parameter setting device 5 in FIG.
5 shows the operation of changing the drive control signal based on the above-mentioned hunting detection result, as shown in FIGS. 7 and 3.
This will be explained with reference to the figures. 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, the count value I of a counter (not shown) provided in the control parameter setting device 55 is set to a value (N+1) that is one more than a predetermined positive integer N.
Load. As can be seen from the operation described below, this integer N plays the role of specifying the time until the driving of the jib 3 and hoisting/lowering rope 6 is restarted when the driving is stopped once to prevent hunting. have. In this step S1, the feedback gain in the arithmetic unit 53 in FIG.
As K _P , a predetermined steady-state value K _P0
is set, and this steady value K _P0 is transferred to the arithmetic unit 53. Further, as the limit signal Sl given to the multiplier 56, the maximum value "1" corresponding to non-suppression is output. As a result, the computing unit 5
3 performs a feedback calculation in a steady state, and the elevation drive control command signal V is in a state consistent with the jib elevation signal _D3 .

In the next step _S2 in FIG.
4. 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 proceeds to step S4, where the count value I of the counter is incremented, and then the count value I is compared with the above integer N at step S5. After the start of horizontal movement, if no hunting has occurred, the process passes through steps S1 to S4, so the count value I remains at (N+1). Therefore, the determination at step S5 is "NO" and the process returns to step S2.

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 S3 to step S7, where the counter is cleared and I=0.

Then, in the next step S8, FIG.
It is determined whether the retrograde amount A _i of the angular velocity ω ₂ shown in is larger than the retrograde amount A _i-1 in the retrograde that occurred one control cycle T (Figure 6) before from that point. . Here, the reason why the control period T is considered as a time unit is because hunting occurs when the control period T is a vibration period. Further, for comparison in step S8, the previous retrograde amount A _i-1 is stored in a memory (not shown) in the control parameter setting device 55.

In this step S8, if the retrograde occurs for the first time or if the retrograde amount A is gradually decreasing even if the retrograde continues to occur, the judgment here is "NO" and the process proceeds to step S2. 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 K _P 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 the change pattern of the feedback gain K _P , and (b) shows the change pattern of the limit signal Sl. show. These are the control parameter setting device 5
5 is stored in a memory (not shown) in a lookup 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 a decreasing function of the retrograde amount A as a whole. Therefore, for example, if the retrograde amount A is A _i , K _Pi is the feedback gain K _P and the limit signal Sl
S _i is given as .

Therefore, the feedback gain K _P and the limit signal Sl are changed to these values K _Pi and S _i , but as is clear from FIG. 8, K _Pi <K _P0 , S _i <1 It is. 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/up-down rope 6 shown in FIG. 1 is reduced, and the hunting that has begun to occur is subdued.

However, if the retrograde amount A continues to increase due to such a reduction in the drive output, the process returns from step S9 to step S2 in FIG. The gain K _P and limit signal Sl are changed again based on _i+1 . In this case, in step S8, the retrograde amount A _i+1 is equal to the previous retrograde amount.
Since it is determined that A is larger than _i , the gain K _P(i+1) and limit signal obtained by changing it again are shown in Fig. 8.
S _i+1 becomes even smaller than the previous gain K _Pi and limit signal S _i . Therefore,
Drive control signal V, u for hunting prevention
further decreases, and by repeating this operation, the hunting that has begun to occur will attenuate.

However, it is conceivable that hunting may not be attenuated even if the drive outputs of the jib drive system 44 and the hoist vertical drive system 50 are successively reduced. Therefore, in this embodiment, FIG.
Each change characteristic line shown in b is set to "0" at a predetermined retrograde amount _A0 . Therefore, if the hunting is not easily attenuated, the retrograde amount A increases to more than _A0 , and the gain K _P and limit signal Sl become "0". Then, the driving of the jib 3 is stopped, and along with this, the hoisting and lowering rope 6 is
The winding up and down movement also stops. In other words, when it is difficult to attenuate the hunting, the horizontal movement operation is temporarily stopped and the hunting is forcibly stopped.

In this way, when the hunting is attenuated by lowering the gain K _P and the limit signal Sl to a finite value or "0", the seventh
The processing loop in the figure starts from step S8.
Now back to S2. Furthermore, once the vibrations have been damped to the point that no retrograde motion occurs, the step
It will now move from S3 to step S4.
Then, each time step S4 is passed, the count value I is sequentially incremented from "0", and finally becomes I=(N+1).

At this point, the process moves from step S5 to step S6, where the steady value K _P0 is given as the gain K _P and the maximum value "1" is given as the limit signal Sl. In other words, after no retrograde occurs, if the state in which no retrograde occurs continues for a period (NT) that is N times the control period T, the initial state (step S1
The state will return to the state specified by

FIG. 9 shows an example of temporal changes in each quantity due to such an operation. In this example, first, the gain K _P and the limit signal Sl are set to a steady value K _P0 and a maximum value "1", respectively (time t ₁ ). After that, this state continues for a while, but at time t ₂ , the amount of retrograde movement A of the detected angular velocity ω ₂ of the jib rises to a finite value (a in the same figure), and at time: (t ₂ +T), the amount of retrograde value A
further increases. Then, the gain K _P (b in the figure) and the limit signal Sl (c in the figure) begin to decrease.

However, at time (t ₂ + 2T), the retrograde amount A
begins to decrease, the gain K _P and limit signal Sl stop decreasing, and this state is maintained for a while. Thereafter, at time _t3 , the retrograde amount A starts to increase again, but in this case, the gain K _P and the limit signal Sl are lowered to "0" and the drive is temporarily stopped. This state also lasts for a while, and the count value I mentioned above increments sequentially.
At time _t4 , the retrograde amount A takes on a finite value again, so this count value I is cleared again.
This retrograde movement at time _t4 is caused by the swing of the hanging load 9 and the tower.
Because the TW vibration is not completely damped,
This is what happened.

Then, after time (t ₄ +T), the count value I is incremented again from "0", and when I=(N+1), the gain is increased.
K _P and limit signal Sl have returned to their initial values K _P0 and "1", respectively.

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.

FIG. 10 is a flowchart showing another example of the hunting prevention operation. The operation shown in FIG. 10 and the operation shown in FIG. 7 described above are as follows.
They differ in the following points. That is, in the operation shown in FIG. 10, the maximum backward movement amount A' after the start of control is stored and compared with the current backward movement amount A (step S18). Then, when the current retrograde amount A is larger than the maximum retrograde amount A', the gain K _P
and reset signal Sl, and set the current retrograde amount A to the new maximum retrograde amount.
A' (step S19). Note that this maximum retrograde amount A' is reset to "0" at the start of control (step S11), and is also reset at the time of return (step S16). Other steps S12-S15 and S17 are the same as steps S2-S5 and S7 in FIG. 7, respectively.

Therefore, each time the retrograde amount A increases and exceeds the past maximum retrograde amount A', the values of the gain K _P and the limit signal Sl are changed, thereby making it possible to obtain the desired hunting prevention effect.

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

In the above embodiment, the jib elevation angle speed ω ₂ is a fixed reference value ω _th (“0” in the above embodiment).
The occurrence of hunting was detected based on whether or not the above reference value ω _th reached the command angular velocity ω ₀
(Fig. 6b) may be variable depending on the size. In this case, for example, if Δω is a predetermined value and ω _th is determined so that ω _th = ω ₀ −Δω,
A state in which the angular velocity ω begins to vibrate with an amplitude greater than Δω can be determined as “hunting occurring”.

In the above embodiment, by utilizing the property that the actual angular velocity ω ₁ and the detected value ω ₂ have different values, and the latter has a larger amplitude than the former,
Hunting prevention is performed based on the detected value _ω2 . 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 ₁ and ω ₂ do not differ much. In this case, for example, the reference value ω _th
By setting the value to a positive value instead of "0", similar detection becomes possible.

The method of dealing with hunting after detection is not limited to the method of lowering the gain K _P or the limit signal Sl as described above. Other control parameters may be changed, or a drive 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 winding/up/down rope-like body formed of rope, wire, etc. is for main winding or auxiliary winding. Furthermore, the term "hanging load" in this invention includes a load held by a bucket.

(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 making it possible to effectively hunt the suspended load. It can be prevented.

[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. FIG. 9 is a diagram showing an example of a change pattern depending on the amount of reversal from the suppression signal, and is a time chart showing temporal changes in various quantities according to the embodiment. FIG. 10 is a flowchart showing another example of the hunting prevention operation of the present invention. 1... Crane, 2... Crane body, 3...
Jib, 4... Rope for elevating and elevating the jib, 6... Rope for hoisting and raising, 9... Hanging load, 12... Jib elevating and elevating angle detector, 31... Main hydraulic pump, 22a... Direction control valve for elevating and elevating the jib, 22b... Directional control valve for winding up and down,
26a, 26b, 27a, 27b...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 (1)

[Scope of Claims] 1. In response to an input operation from a boom operation input means, a drive control signal is given to a crane boom elevating and elevating drive mechanism and a hoisting and vertically driving mechanism for a cable-like body suspended from the boom; A method for preventing hunting when horizontally moving a load suspended from the cable by simultaneously raising and lowering the boom and hoisting the cable, the boom detect the temporal change in the elevation angle of the
If the temporal change includes a retrograde component and this retrograde component is larger than a predetermined value,
The hunting is prevented by changing the drive signal according to the amount of the retrograde component and reducing the drive speed of the boom and the rope-shaped body in the up and down winding. Method for preventing hunting during horizontal movement. 2. The criterion is whether or not the temporal change in the elevation angle includes a retrograde component;
A method for preventing hunting during horizontal movement of a suspended load of a crane according to claim 1. 3. Hunting prevention in horizontal movement of a suspended load of a crane according to claim 1 or 2, wherein the change in the drive control signal is performed by changing a control parameter in the control of the horizontal movement. Method.