JPH04303390A - Load lifting wire drive control device for crane with telescopic boom - Google Patents

Abstract

PURPOSE:To enhance the control accuracy by allowing the drive speed of a load lifting wire to follow up the telescopic speed of a boom. CONSTITUTION:Wire drive feed-back control 54 for wire drive is carried out in accordance with a comparison between a desired value and an actual value of a variation in length of a load lifting wire 19 which is calculated from a variation in condition of a boom 14, and feed-forward control 58 for wire drive is carried out in accordance with a variation speed of the above-mentioned desired value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire drive control device for a crane equipped with an extendable boom, which controls the winding and unwinding of a hanging wire in accordance with the extension and contraction of the boom.

0002

[Prior Art] Conventionally, in accordance with the expansion and contraction of the boom of a crane, a wire for hanging a load hung on the boom is wound.
Various devices have been proposed as devices for controlling unwinding.

For example, Japanese Patent Laid-Open No. 60-122693 discloses that, based on the actual amount of change in the length of the boom from the reference position (that is, the amount of expansion and contraction of the boom) and the angle of elevation of the boom, An apparatus is shown for controlling a load wire drive motor to offset the apparent winding or unwinding of a load wire. In other words, if the boom is extended or retracted without driving the wire at all, the height of the hook at the lower end of the wire will change depending on the amount of expansion or contraction. A system has been proposed that performs wire-driven feedback control in accordance with the expansion and contraction of the boom.

[0004] Furthermore, Japanese Utility Model Application No. 64-56489 discloses that the length of the wire from the top sheave at the tip of the boom to the hook does not change even if the boom expands and contracts. A device is described that performs feedback control of the drive of the winch so that the amount of change in wire payout length and the amount of change in wire payout length are always the same.

[0005]

[Problems to be Solved by the Invention] The above device only performs feedback control of the winch drive according to the extension and contraction of the boom, so when the change in the amount of extension and contraction of the boom is large, that is, when the boom is moving at a large speed. When the winch is driven to extend and retract, the winding or unwinding speed of the winch does not follow this, and the deviation between the target value and the actual value increases, making it difficult to obtain good control accuracy. Further, even immediately after the boom starts to extend and retract, that is, at the start of the boom extension and retraction, the drive speed of the winch is difficult to follow, and the deviation tends to widen.

In view of these circumstances, the present invention aims to improve control accuracy by making the driving speed of the hanging load wire (that is, the winding or unwinding speed of the wire) closely follow the boom expansion and contraction speed. It is an object of the present invention to provide a hoisting wire drive control device for a crane with a telescoping boom, which can more preferably follow the drive speed of the hoisting wire even at the start-up of boom extension and contraction.

[0007]

[Means for Solving the Problems] The present invention includes a telescopic boom, a telescopic driving means for telescopically driving the boom, and a wire driving means for winding and unwinding a hanging load wire. A crane with a retractable boom in which a hanging load wire let out from a driving means hangs from a proper position on the boom, includes a wire length detection means for detecting an amount of change in the length of the hanging load wire from a reference state; boom state detection means for detecting a change in the state of the boom;
Feedback control of the wire driving means is performed based on a comparison between the target value of the amount of change in the payout length of the hanging load wire calculated based on the detected value of the boom condition detecting means and the detected value by the wire length detecting means. The present invention includes a feedback control means and a boom change feedforward control means for performing feedforward control of the wire driving means based on the rate of change of the target value of the wire payout length (claim 1).

The invention further includes command input feedforward control means for performing feedforward control of the wire driving means based on an operation command signal input to the telescopic driving means (claim 2), and (Claim 3) By providing an expansion/contraction speed suppressing means for controlling the expansion/contraction driving means so as to suppress the wire driving speed to a speed corresponding to a maximum value of the wire driving speed by the wire driving means (Claim 3).
, it is possible to obtain better effects as described below.

[0009]

[Function] First, according to the device according to claim 1, in addition to performing feedback control of the wire drive based on the comparison between the target value and the actual detected value of the amount of change in the length of the hanging load wire, Wire-driven feedforward control is performed based on the rate of change of the above target value, that is, the speed corresponding to the boom extension/contraction speed, so if the boom extension/contraction speed is large, a large feedforward control amount is set accordingly. By doing so, the driving speed of the hanging load wire can always be made to follow the above-mentioned expansion/contraction speed well.

Furthermore, according to the apparatus according to claim 2, feedforward control of the wire drive is performed based on the operation command signal inputted to the telescopic drive means when the boom starts to extend and retract. Even at the start of expansion and contraction, the driving speed of the hanging load wire can be followed satisfactorily.

Furthermore, according to the apparatus according to claim 3, the expansion and contraction speed of the boom is suppressed to a speed equal to or less than the maximum value of the wire driving speed by the wire driving means, regardless of the operation command signal. The boom is prevented from being driven to extend or contract at a speed that exceeds the limit of following the drive speed.

0012

Embodiment FIG. 2 shows the overall structure of a crane with a telescopic boom according to an embodiment of the present invention.

A swivel base 12 is rotatably disposed on the lower traveling body 10 of the crane, and a boom 14 and a hoisting cylinder 16 for raising and lowering the boom 14 are disposed on the swivel base 12. The boom 14 is made up of an outer boom member 14a and an inner boom member 14b, and the entire boom 14 is extendable and retractable as the inner boom member 14b moves in and out of the outer boom member 14a. Furthermore, a jib 15 is detachably attached to the tip of the inner boom member 14b.

A main winding winch 18 is rotatably provided on the swivel base 12, and a main winding wire (hanging load wire) 19 paid out from the main winding winch 18 is attached to the swivel base 1.
2, the guide sheave 22 provided at the tip of the boom 14, and the sheave for hanging the main hoist hook 24, and then 27, and the tip end is fixed to the tip end of the boom 14. Further, an auxiliary winding winch 28 is rotatably provided at a position adjacent to the main winding winch 18, and the auxiliary winding wire 29 paid out from this auxiliary winding winch 28 is connected to the guide sheave 20 on the swivel base 12, and An auxiliary winding hook 32 is fixed to the tip of the jib 15 in a state where it is hung around the guide sheave 31 at the tip of the jib 15.

Therefore, when the boom 14 is stationary, the main winding wire 19 and the auxiliary winding wire 29 are wound or unwound by the rotation of the main winding winch 18 and the auxiliary winding winch 28, respectively, so that the boom 14 is The main hoisting hook 26 and the auxiliary hoisting hook 32 move up and down with respect to the tip and the tip of the jib 15, respectively.

Next, a hydraulic circuit for driving the boom 14 to extend and retract will be explained based on FIG. 3.

In FIG. 3, 34 is a hydraulic pump, 36 is a telescoping cylinder, and 38 is a main control valve. The expansion and contraction of the telescoping cylinder 36 drives the inner boom member 14b in the direction of protrusion and retraction with respect to the outer boom member 14a. The boom 14 is configured to be extended and retracted. The main control valve 38 is composed of a three-position throttle switching valve, and the spool is operated in response to the pilot pressure p that rises by operating the operating lever of the pilot valve 40, so that the main control valve 38 can be moved from the center position to the left or right position in the figure. can be switched to Specifically, in the neutral position shown in the figure, boom 1
4 in a stationary state, and in the left position, the boom 14 is retracted by guiding the discharge oil of the hydraulic pump 34 to the head side of the telescopic cylinder 36, and in the right position, the boom 14 is guided to the rod side of the telescopic cylinder 36. The boom 14 is extended.

In the figure, 42 is a main relief valve, and 44 is a counter balance valve.

Furthermore, one of the features of this device is that an oil passage 45 is provided which bypasses the main control valve 38 and connects the hydraulic pump 34 and the tank 43, and a pressure compensator is installed in the middle of this oil passage 45. A flow rate control valve (expansion/contraction speed suppressing means) 46 is provided. This flow control valve with pressure compensation 46 operates only when the pressure of the oil supplied from the hydraulic pump 34 to the telescopic cylinder 36 increases to a certain level or more, and releases the discharged oil directly to the tank 43. This is to keep the expansion and contraction speed of the boom 14 below a certain value at all times. Here, the critical pressure at which the pressure compensated flow control valve 46 operates is set such that the expansion and contraction speed is suppressed to such an extent that the wire winding speed by the main winch 18 can follow the expansion and contraction of the boom 14, that is, the The rotational speed is set to be suppressed to a speed commensurate with the maximum rotational speed of the main winch 18.

Next, the rotational drive system of the main winding winch 18 will be explained based on FIG. 1. In this embodiment, the rotation drive control of the main hoisting winch 18, specifically, the main hoisting winch 18 is controlled to keep the absolute height (above the ground) of the main hoisting hook 26 constant regardless of the amount of expansion and contraction of the boom 14. wire 1
A case will be described in which the present invention is applied to the winding or unwinding control of the winding wire 9, but the present invention can also be applied to the drive control of the auxiliary winding wire 29. If you apply it, you can get better results.

The above system includes a detection section S, a control calculation section C
, and a drive section (wire drive means) D.

[0022] The detection unit S detects the engine rotation speed N of the crane.
an engine rotation speed sensor 46 that detects E; a pilot pressure sensor 47 that converts the pilot pressure p into an electrical signal;
A boom length sensor (boom state detection means) 48 detects the amount of change in the boom length (i.e., the amount of expansion and contraction) lB based on the initial state, and a boom heave angle sensor ( Boom state detection means) 50,
It also includes a wire length sensor (wire length detection means) 52 that detects the amount of change lW in the length of the suspended load wire (i.e., the length of the main winding wire 19 paid out from the main winding winch 18) based on the initial state. There is.

The control calculation unit C includes a feedback control unit 5
4. Command input feedforward control section 56, boom change feedforward control section 58, and nonlinear compensation section 6
It is equipped with 0.

The feedback control unit 54 controls the wire payout as the boom 14 expands and contracts based on the boom heave angle θB detected by the boom heave angle sensor 50 and the boom length change amount IB detected by the boom length sensor 48. Calculate the apparent change in length (in other words, the change in wire payout length necessary to keep the height of the main winding hook 26 above the ground constant regardless of the expansion and contraction of the boom 14) Δl, and calculate this. Feedback control is performed based on the deviation ΔlW between this target value Δl and the actual wire length change amount lW detected by the wire length sensor 52. Quantity u
3 is calculated.

Here, the target value Δl of the amount of change in the length of the main winding wire is determined by the amount of change in the length of the main winding wire.
If the number of turns of wire between is N, it is expressed by the following formula. Δl=lB+N・lB sinθB Also, the feedback control amount u3 is the deviation Δl
It is calculated by adding the value obtained by multiplying W by the proportional gain KP and the value obtained by multiplying the integrated value ΣlW of the deviation ΔlW by the integral gain Ki.

The command input feedforward control section 56 calculates a feedforward control amount u1 based on the pilot pressure p by multiplying the pilot pressure p detected by the pilot pressure sensor 47 by a feedforward gain Kf1. .

Boom change feedforward control section 58
differentiates the target value Δl calculated by the feedback control section 54 with respect to time, and applies a feedforward gain Kf2 to the change rate of the target value dΔl/dt obtained thereby.
The feedforward control amount u2 is calculated based on the rate of change dΔl/dt.

[0028] The rate of change dΔl/dt is determined by, for example, the following approximate formula dΔl/dt=(11Δlt−6Δlt−1
-3Δlt-2-2Δlt-3). Here, Δt is the sampling period (seconds), and Δl
t-i indicates the target value Δl at a time (Δt·i) seconds before time t.

The nonlinear compensator 60 adds correction to the sum of the feedback control amount u3 and the feedforward control amounts u1, u2 to compensate for linearity, and outputs this value as the basic control amount u.

The drive section D includes an electromagnetic proportional pressure reducing valve 62, a control valve 64, and a winch drive motor 66, and the electromagnetic proportional pressure reducing valve 62 generates pilot pressure by receiving a signal from the nonlinear compensation section 60. By operating the spool of the control valve 64 in accordance with this pilot pressure, the drive control of the main winch 18 by the winch drive motor 66 is performed.

Note that since the flow rate flowing into the control valve 64 depends on the engine speed NE, the various gains Kf1, Kf2, Kp, Ki used in the arithmetic control section C are as follows:
Based on the engine speed NE detected by the engine speed sensor 46, an appropriate value is calculated as appropriate. However, if the engine is operated at a constant rotation speed, the various gains described above may also be fixed to constant values.

According to such a device, while the boom 14 is extended or retracted by operating the lever of the pilot valve 40, the target value Δl of the wire length change amount based on the expansion/contraction change amount IB and the actual wire length change are determined as in the conventional device. Deviation ΔlW from the amount lW
is calculated at regular sampling intervals Δt, and feedback control is performed based on this, so that the main winding wire 19 is wound by the main winding winch 18 so that the height of the main winding hook 26 is always kept constant. The take-up or unwind operation is controlled.

Furthermore, in this device, feedforward control is executed based on the rate of change dΔl/dt of the target value, that is, the feedforward control amount u1 is set according to the expansion and contraction speed of the boom 14, so that the boom Even if boom 14 is extended or contracted at a high speed, this boom 14
The rotational drive of the main hoisting winch 18 can reliably follow the expansion and contraction of the main hoisting hook 26, and the height of the main hoisting hook 26 can be held constant with high precision without widening the control deviation.

Furthermore, in this embodiment device, the boom 14
Boom 1 based on the pilot pressure p for actuating
4 is detected, and feedforward control based on this pilot pressure p is also executed, so it is possible to suppress control deviation immediately after the boom 14 starts extending and contracting, and as a result, the drive of the main winding wire 19 Control can be executed smoothly from the start.

In addition, a pressure-compensated flow rate control valve 46 is provided in the hydraulic drive circuit for expanding and contracting the boom, so that the expansion and contraction speed of the boom 14 is always controlled by the main winch 18 regardless of the amount of lever operation of the pilot valve 40. Since the speed is kept below the maximum drive speed of the main winding winch 18, it is possible to prevent the control deviation from expanding due to the boom 14 expanding and contracting at a speed that exceeds the followable speed of the main winding winch 18. Therefore, this expansion/contraction speed suppressing means can make the effect obtained by the feedforward control more reliable.

It should be noted that the present invention is not limited to these embodiments, but can also be modified as follows.

(1) In the above embodiment, control was shown to maintain the absolute height (height above the ground) of the main hoisting hook 26 constant regardless of the expansion and contraction of the boom 14, but the device of the present invention can be applied. The control is not limited to such control, and can also be applied, for example, to a case where the distance from the hanging sheave 24 at the tip of the boom 14 to the main hoisting hook 26 is maintained constant. In this case, boom length sensor 4
The actual boom length change amount IB detected in step 8 may be directly set as the target value Δl of the wire length change amount, and then the same calculations as above may be performed. Furthermore, if the control calculation unit C is configured to be able to switch between a mode in which the target value Δl is set as is to the boom length change amount lB, and a mode in which it is set to lB+N·lB sin θB,
It is possible to obtain a device that can selectively perform control to maintain the height of the main hoist hook 26 above the ground constant and control to maintain a constant distance from the hanging sheave 24 to the main hoist hook 26.

(2) In the above embodiment, feedforward control is performed based on the pilot pressure p detected by the pilot pressure sensor 47, but this feedforward control is performed based on the pilot pressure p detected by the pilot pressure sensor 47. It may be based on the operation command signal, and instead of the pilot pressure p, a corresponding value, for example, the operating amount of the operating lever in the pilot valve 40 is detected, and feedforward control is performed based on this operating amount. The same effect as above can also be obtained by doing the following.

[0039]

Effects of the Invention As described above, the present invention provides a target value for the amount of change in the length of the hanging load wire calculated based on changes in the state of the boom and a detected value for the amount of change in the length of the actual length of the wire for hanging the load. In addition to performing feedback control of the wire drive based on a comparison with By executing feedforward control accordingly, the drive of the hoisting wire can always follow the expansion and contraction of the boom, thereby greatly improving control accuracy. There is an effect that can be achieved.

Furthermore, the apparatus according to claim 2 is configured to perform feedforward control of the wire driving means based on an operation command signal regarding extension and contraction of the boom. In particular, it is possible to prevent control deviation from increasing even at the start of boom extension and contraction, which is difficult to follow with wire drive, and has the effect of further improving control accuracy.

Further, the apparatus according to claim 3 is provided with an expansion/contraction speed suppressing means for suppressing the expansion/contraction speed of the boom to a speed corresponding to the maximum value of the wire drive speed or less, so that the speed that can be followed by the wire drive is reduced. It is possible to prevent the boom from being extended or retracted at an exceeding speed, thereby making it possible to further ensure the effect of the feedforward control.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a wire drive control device in an embodiment of the present invention.

FIG. 2 is an external view showing an example of a crane with a telescopic boom provided with the wire drive control device.

FIG. 3 is a circuit diagram of a boom telescoping drive hydraulic circuit provided in the telescoping boom-equipped crane.

[Explanation of symbols]

14 Boom 18 Main hoisting winch (wire driving means) 19 Main hoisting wire (hanging load wire) 26 Main hoisting hook 34 Hydraulic pump (telescopic driving means) 36 Telescopic cylinder (telescopic driving means) 38 Main control valve (telescopic driving means) 40 Pilot valve 46 Flow control valve with pressure compensation (expansion/contraction speed suppression means) 4
8 Boom length sensor (boom state detection means) 50
Boom elevation angle sensor (boom state detection means) 52 Wire length sensor (wire length detection means) 54 Feedback control section 56 Command input feedforward control section 58 Boom change feedforward control section C Control calculation section D Drive section (wire drive means) S detection part

Claims (3)

[Claims] 1. A suspended load that is provided with an extensible boom, an extensible driving means for driving the boom to extend and retract, and a wire driving means for winding and unwinding a suspended load wire, and a suspended load that is unwound from the wire driving means. In a crane with a retractable boom in which the wire is suspended from a proper position on the boom, wire length detection means detects an amount of change in the length of the hanging wire from a reference state, and detects a change in the state of the boom from the reference state. The wire is driven based on a comparison between the target value of the amount of change in the length of the hanging load wire calculated based on the detected value of the boom state detecting means and the value detected by the wire length detecting means. The present invention is characterized by comprising a feedback control means for performing feedback control of the means, and a boom change feedforward control means for performing feedforward control of the wire driving means based on a rate of change of the target value of the wire payout length. Load wire drive control device for a crane with a telescopic boom. 2. A hoisting wire drive control device for a crane with a telescopic boom according to claim 1, wherein a command input feed performs feedforward control of the wire driving means based on an operation command signal input to the telescopic driving means. A load wire drive control device for a crane with a telescoping boom, characterized in that it is equipped with forward control means. 3. A hoisting wire drive control device for a crane with a telescoping boom according to claim 1 or 2, wherein the boom expansion and contraction speed is suppressed to a speed corresponding to a maximum value of the wire drive speed by the wire drive means or less. A hoisting wire drive control device for a crane with a telescopic boom, characterized in that it is provided with a telescopic speed suppressing means for controlling the telescopic driving means.