JPH10291769A - Method for detecting rope length of crane and method for swing prevention control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting the rope length by a simple means without using any special detecting unit such as an encoder or an optical distance meter. SOLUTION: In a crane provided with a trolley driving device for making a load suspended by a rope travel, the fluctuation period T of load torque of the trolley driving device is detected, and the rope length L is found by using the expression L=[T/(2π)]<2> Xg (the letter π indicates the ratio of the circumference of a circle to its diameter, the letter g indicates gravity). The fluctuation period T adopts the mean value of the time (T2-T4) between mutually adjacent two maximum values P2, P4 of the detected data of load torque and the time (T1-T3) between mutually adjacent two minimum values P1, P3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crane anti-sway control method for controlling the run-out of a load suspended on a rope of a crane, for example, a suspended load suspended on a trolley of an overhead traveling crane, and the like. The present invention relates to a method for detecting a crane rope length required for a vehicle.

[0002]

2. Description of the Related Art As a method for suppressing the swing of a load suspended on a rope, for example, a suspended load suspended on a trolley of an overhead traveling crane, a container of a container crane, a grab bucket of an unloader, or the like during running or traveling. Can be roughly classified into two types: mechanical steady rest methods and electrical steady rest methods. The mechanical anti-sway method includes a method to control the run-out of the rope by providing a guide mast, for example, on the trolley itself, or a special rope hook that can suppress the run-out of the load by focusing on the structure of the container itself in the case of a container crane. There is a steady rest method using a rope tensioning device using a hydraulic cylinder in combination. However, such a mechanical steady rest method could not be applied to a general device or a large-sized device.

[0003] The electric steady rest method detects the swing angle or the swing speed of the suspended load and feeds it back to the drive system, or calculates and instructs a speed pattern capable of eliminating the shake at the end of acceleration / deceleration. There is a method of performing steady rest control. In the electrical steadying method, a means for detecting a swing angle is required. As a method for detecting the shake, there has been an optical shake angle detection method based on a combination of a light source, a camera, and an image processing device for the shake angle of a suspended load.

As such an optical deflection angle detection method, there is a method as disclosed in Japanese Patent Application Laid-Open No. 7-144883. That is, in the apparatus according to the method, as shown in FIG. 6, a reflecting prism 6 that reflects light in the incident direction is attached to the crane hook 4, while the trolley 1 emits light to the reflecting prism 6 and reflects the reflected light. A tracking device 5 that receives the reflection prism 6 and moves in two axes so as to always track the reflection prism 6 and a deflection angle processing device 8 that reads the rotation angle of the two axes during the tracking are attached. The configuration is such that a lightwave distance meter 7 for measuring the distance to the reflection prism 6 is mounted. The tracking device 5 includes a light transmitting unit, a light receiving unit,
The light transmitting unit emits a beam of light toward the reflecting prism 6, and the reflected light is received by the light receiving unit. The received light is placed on the focal plane 2
An image is formed on the photoelectric surface of the three-dimensional position detecting photodiode.
The automatic tracking operation detects the image position of the reflecting prism 6 formed on the photoelectric surface of the two-dimensional position detecting photodiode at this time, and outputs pulses of the X and Y two-axis pedestal according to the amount of deviation from the optical axis center. By driving the motor, the image of the reflecting prism 6 is always 2
The servo operation is performed so as to be at the center of the photoelectric surface of the three-dimensional position detecting photodiode. The tracking operation is performed by feeding back the change in the light receiving position from the center of the optical axis caused by the movement of the reflection prism 6 or the movement of the tracking device 5 or both, so that the light is always received at the center of the optical axis. The shake angle processing device 8 receives the shake angle signal from the shake angle measuring device 10, that is, detects the rotation angles of the tracking device 5 on the X axis and the Y axis, thereby calculating the amount by which the servo mechanism operates. The data of the deflection angle θ is obtained.

A light wave distance meter 7 is mounted on the oscillating tracking device 5, and measures the distance from the light wave distance meter 7 to the reflection prism 6 while also using the reflection prism 6 for the tracking device 5. Therefore, the rope length L, which is the distance between the tip of the jib 11 and the hook 4, is continuously measured while automatically tracking the moving suspended load 3. After all, XY of the suspended load 3
The Z coordinate value is calculated, and therefore, the swing angle measuring apparatus 10 can measure the suspended load swing angle θ in all directions.

However, since such an optical deflection angle detection device is an optical type, there is a concern that performance may be degraded due to dust, and accurate alignment of a light source and a camera is troublesome. Disadvantage that it becomes too expensive as a deflection angle detection device for
Further, it is common to install a camera near the hoisting winch of the trolley due to the structure of the crane, but there is a problem that the installation space is required.

As a method for solving this problem, a method of detecting a swing amount from a change in load torque of a trolley drive device is proposed in Japanese Patent Application Laid-Open No. 8-295486.
In this method, first, an electric motor torque that does not include a load torque fluctuation based on a rope runout is obtained, and this value is compared with an actually measured load torque fluctuation to obtain a runout load signal due to the rope runout. A shake amount proportional to the shake load signal is calculated, and the shake amount is multiplied by a gain determined by the rope length, and negatively fed back to the speed command of the trolley drive device to suppress the shake. By the way, as in the case of performing the control of the above publication, when performing the anti-sway control,
In general, it is necessary to measure the hanging rope length L, which is a factor that determines the swing cycle of the suspended load, and to measure the swing amount (shake angle) θ. FIG. 5 shows the swing angle θ and the rope length L when the load 3 is suspended from the trolley 1 by the rope 2.
Is shown. Regarding the amount of run-out,
It is disclosed that the load torque fluctuation can be estimated without using a special detection device, but a simple and useful method for the rope length has not been provided yet.

Accordingly, an encoder is attached to the shaft of the hoisting motor, and the pulse length is detected by counting the pulses, or a reflecting prism is attached to the crane hook as in the technique of Japanese Patent Application Laid-Open No. Hei 7-144883. The trolley is equipped with a lightwave distance meter that measures the distance to the reflecting prism, and has to rely on a conventionally known method of detecting the rope length.

[0009]

However, the conventional methods of using an encoder or providing a lightwave distance meter all require the provision of a special detection device, which complicates the configuration and increases the cost. There was a problem of becoming.

The present invention provides a method for detecting a rope length by a simple means without using a special detecting device such as an encoder or an optical distance meter, in order to solve such problems. An object of the present invention is to provide a control method for performing steady rest using a rope length detected by the method.

[0011]

In order to solve the above-mentioned problems, a rope length detecting method according to the present invention detects a fluctuation period T of a load torque of a trolley driving device for running a load suspended by a rope, and detects the fluctuation period. Calculation formula L = [T / (2π)] ² × g (where π: pi,
g: gravity acceleration) to determine the rope length L.

The fluctuation period T includes a time between two adjacent maximum values, a time between two adjacent minimum values, and a value between three or more consecutive maximum values in the detected data of the load torque of the trolley drive device. At least one of an average value of time, an average value of time between three or more consecutive minimum values, and a time twice as long as a time between adjacent maximum values and minimum values is adopted (claim 2). . In addition, as a method of finding the maximum value and the minimum value, sampling values of the load torque at predetermined time intervals are collected, and the sampling values continuously increase N1 times beforehand and then decrease M1 times continuously. The maximum point in this case is the maximum value, and the sampling value is a predetermined N2.
The minimum point when the number of times decreases continuously and then increases continuously M2 times is defined as the minimum value. Where N
1, M1, N2, and M2 are arbitrary integers.

Further, in order to avoid the influence of load torque fluctuation during acceleration, it is desirable to detect the fluctuation period T based on the load torque after completion of acceleration of the trolley drive device.

Further, the steady rest control method according to the present invention is characterized in that, when a steady rest of a crane provided with a trolley drive device for traveling a load suspended by a rope is carried out, the amount of swing of the rope is controlled by the swing amount of the rope. The swing is suppressed by negatively feeding back a value obtained by multiplying a gain determined by the rope length detected by any one of the methods 4 to a speed command of the trolley drive device.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1, 2 and 3 show the torque current of the electric motor of the trolley drive device when the crane is operating. Since the run-out remains for a while after the start of operation, the torque current fluctuates. Depending on the driving situation, the fluctuation may be slow in decay as shown in FIG. 1 or may be fast in decay as shown in FIG.

The fluctuation period of the torque current depends on the rope length, and the relational expression is expressed by T = 2π × (L / g) ^1/2 . Where π: Pi g: Gravity acceleration T: Fluctuation period of torque current L: Rope length

From this, the rope length L can be obtained from the following equation: L = [T / (2π)] ² × g (1) Therefore, the rope length can be obtained by simple calculation only by electrically detecting the torque current for the fluctuation of the load torque and without providing any special detecting device. Then, a gain is calculated based on the rope length, and the product of the gain and the amount of deflection (determined in the same manner as in Japanese Patent Application Laid-Open No. 8-295486) is calculated by using the load torque fluctuation. By giving negative feedback to the speed command, the swing of the suspended load is suppressed.

In calculating the variation period T of the load torque, in order to calculate the period T as accurate as possible,
It is detected by the following method, for example, according to the continuous state of the fluctuation of the load torque. Since various examples can be considered as a calculation method of the period, only a representative method is shown here.

(1) As shown in FIG. 1, two maximum values P2,
When P4 and two minimum values P1 and P3 are present, the period T is obtained by one of the following equations. (A) T = T4-T2 (time between two adjacent local maximums) (b) T = T3-T1 (time between two adjacent local minimums) (c) T = ｛ (T2-T4) + (T3-T1)｝ / 2
... (average time between two adjacent local maxima and time between two adjacent local minima)

(2) As shown in FIG. 2, two minimum values P1,
When there is P3 and the maximum value P2 between them, the period T is obtained by the following equation. (D) T = {T3-T1 + (T2-T1) × 2} / 2
... (The time between two adjacent minima and the adjacent maxima
Average value with twice the time between local minimums)

(3) As shown in FIG. 3, when there is a minimum value P1 and a maximum value P2, the period T is obtained by the following equation. (E) T = (T2-T1) × 2 (adjacent local maximum
Twice the time between the local minimums)

(4) In addition, when there are three or more maximum values or minimum values, the average value of the time between three or more consecutive maximum values or the value of the time between three or more consecutive minimum values. An average value of time may be adopted as the cycle.

Since the actual torque detection value is not smooth as shown in FIGS. 1 to 3 and includes a noise component as shown in FIG. 4, it is necessary to prevent the protrusion or dent due to noise from being erroneously detected as a peak point. It needs to be devised. In the present invention, the maximum value and the minimum value are accurately determined as follows from the graph of the torque fluctuation including the noise component as shown in FIG.

First, during acceleration, there is a variation not related to the swing of the rope. Therefore, after the completion of the acceleration, the detection of torque is started after a lapse of a fixed time, and the torque detection is performed every predetermined short time (scan time). Sampling and collecting multiple sampling values. Then, when the sampling value increases monotonically by N1 times or more and then monotonically decreases by M1 times or more, the maximum value during that period is defined as a maximum value max1, and another maximum value max2 is obtained in the same manner. Similarly, after the sampling value monotonically decreases by N2 times or more, and then increases monotonically by M2 times or more, the minimum value during that time is defined as the minimum value min1, and another minimum value min2 is obtained in the same manner. By obtaining the maximum value and the minimum value as described above, the fluctuation period T of the load torque can be obtained, and the rope length can be obtained based on the values.

Here, N1, M1, N2, and M2 are arbitrary values, but if they are too large, the extreme value may not be obtained. If the values are too small, the peak value of the noise component is erroneously detected as an extreme value. It is necessary to determine in consideration of these situations because there is fear. If the scan time is too short, the peak value of the noise component may be erroneously detected as an extreme value, so the scan time is changed according to the situation. The example of FIG. 4 shows a case where N1 = M1 = N2 = M2 = 4.
In this case, the maximum value when continuously rising four times (black circles) and then successively falling four times (white circles) is defined as a first maximum value max1, falling continuously four times (black circles), and subsequently rising four times continuously (white circles). ) Is the first minimum value min1. Similarly, max2 is the second maximum value and min2 is the second minimum value in the next time range.

The above will be described with reference to FIG. The waveform shown by the solid line indicates the instantaneous value of the detected waveform at each scan. The horizontal axis indicates time, and the numbers indicate scan numbers. When the amplitude of the scan number S + 1 immediately to the right of the scan number S is larger than that of the scan number S, a black circle (●) is added. When the amplitude is smaller, a white circle (○) is added. Then, since the amplitude of the scan number 2 immediately to the right of the scan number 1 is larger than that of the scan number 1, the mark becomes ●, and since the amplitude of the scan number 3 is larger than the amplitude of the next scan number 2, the mark becomes ●. . Similarly, scan number 4 is represented by ●,
The scan number 5 also becomes ●. However, since the amplitude of the scan number 6 is smaller than the amplitude of the scan number 5, the white circle (○) is displayed this time. Similarly, the scan number 7 becomes ○ and the scan number 8 becomes ○. The next scan number 9 is ●, the scan number 10 is also ●, the scan number 11 is also ス キ ャ ン, the scan number 12 is also ●, and the scan number 13 is also ●. The next scan number 14 is ○, and the scan number 15 is ○. The scan number 16 is ○, the scan number 17 is ○, and the scan number 18 is ○. Similarly, scan number 19
From ● ○○○○○○○○○○ ●● ○ ● ○ ● ○○○○○
●●●●● And the scan number 46 becomes ●.

In the case of N1 = M1 = N2 = M2 = 4, the maximum value when rising continuously four times (that is, four consecutive circles) and then descending four times continuously (that is, four consecutive ○). Since the value is the first maximum value max1, the scan number 1 →
Up to the scan number 5, four black circles continue, but after that, there are only three black circles (ie, not four consecutive circles), so the maximum value during this period is regarded as noise, and the process proceeds to the next step. From scan number 9 to scan number 13, there are five consecutive ● s (that is, four or more consecutive), and since there are five ○ s (that is, four or more consecutive), The amplitude of the scan number 13 which is the maximum value is the maximum value max1.
Becomes

The determination of the minimum value is performed in the same manner. That is, ●●● of the scan number 19 or less is noise, and ○○○○○○○ ●●● of the scan number 22 or less is 8
It is not a local minimum value because there are no four consecutive continuations of ● even though there is a continuation. Subsequent scan numbers 33 and below are also noise in ● ○ ●, and from scan number 36, ○○○○○ ●●●●●
The amplitude of the scan number 40, which is the minimum value in between, becomes the minimum value min1.

As described above, N1 = M1 = N2 = M2
The value is determined by the rigidity of the rope.If the value is too large, the extreme value may not be obtained.If the value is too small, the peak value of the noise component may be erroneously detected as the extreme value. It is better to decide by adjustment on site.
Once the installation location is determined, the manner in which noise is generated is substantially determined.

In the steadying control of the crane, the rope length L is obtained from the load torque fluctuation period T obtained in this way by the above equation (1). Therefore, the amount of rope swing is multiplied by a gain determined by the rope length. This value may be negatively fed back to the speed command of the trolley drive device.

Table 1 shows that when the rope length and the suspended weight are changed, the rope length L detected by using the equation (1) from the fluctuation cycle T of the load torque of the trolley drive device obtained by the present invention and the equation (1). And the experimental results with the true rope length and their errors. As can be seen from the table, in the seven tests, the first test was 3.2 m, the detected rope length was 3.20 m, and the error was 0 in the first test.
In the second test of the same rope length with increased weight, the detected rope length was 3.34 m, the error (L0 -L) / L0 was 4.3%, and in the third test, the true rope length was 6.4 m. On the other hand, the detection rope length is 6.21 m, the error is 3.0%, and the fourth to
In the seventh test, the weight was gradually increased with respect to the true rope length of 9.6 m, and the resulting detected rope length was 8.94 m (6.8% error) and 9.45 m (1.5 error).
%), 9.45 m (error 1.5%), and 9.30 m (error 3.1%). As a result, the error is 7% or less regardless of the rope length and the suspended weight.

[0032]

[Table 1]

[0033]

As described above, according to the present invention,
The rope length can be detected based on the load torque fluctuation of the trolley drive device without using any special detection device such as an encoder or a lightwave distance meter, so the configuration is simplified as no detection device is required Cost can be reduced. Therefore, an economical steady rest device can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention, showing an example of a change in load torque of a trolley drive device.

FIG. 2 is an explanatory diagram of the present invention, and is a diagram illustrating another example of a variation in load torque of a trolley drive device.

FIG. 3 is an explanatory diagram of the present invention, and is a diagram showing still another example of a variation in load torque of the trolley drive device.

FIG. 4 is an explanatory diagram of the present invention, showing a change in load torque including a noise component of the trolley drive device, and a maximum value and a minimum value.

FIG. 5 is a diagram showing a trolley, a rope, and a suspended load, and a swing angle and a rope length of the crane in question.

FIG. 6 is a diagram showing a known optical deflection angle detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Trolley 2 Rope 3 Hanging load 4 Crane hook 5 Tracking device 6 Reflection prism 7 Lightwave distance meter 8 Deflection angle processing device 10 Deflection angle measuring device 11 Jib P1, P3 Minimum value P2, P4 Maximum value

Claims (5)

[Claims] 1. A crane provided with a trolley driving device for traveling a load suspended by a rope, wherein a fluctuation period T of a load torque of the trolley driving device is detected, and a rope is calculated from the fluctuation period T using the following arithmetic expression. Length L
The method for detecting the rope length of a crane, characterized in that: L = [T / (2π)] ² × g (where π: pi,
g: gravity acceleration) 2. The fluctuation period T is defined as a time between two adjacent maximum values, a time between two adjacent minimum values, and three or more consecutive maximum values in the detection data of the load torque of the trolley drive device. Adopting at least one of an average value of time between values, an average value of time between three or more consecutive minimum values, and a time twice as long as a time between adjacent maximum values and minimum values. The method for detecting a rope length of a crane according to claim 1, wherein: 3. The maximum value and the minimum value are obtained by collecting a sampling value of the load torque at predetermined time intervals, and the sampling value continuously increases for a predetermined number of times, and thereafter, increases by a predetermined number of times. The maximum point when continuously decreasing is the maximum value, the sampling value is continuously decreased by a predetermined number of times, and then the minimum point when the predetermined number is continuously increased by the minimum value is the minimum value. 3. The method according to claim 2, wherein the rope length of the crane is adopted. 4. The crane rope length detecting method according to claim 1, wherein the fluctuation period T is detected based on a load torque after the acceleration of the trolley drive device is completed. . 5. A trolley drive device which, when a swing load of a crane provided with a trolley drive device for running a load suspended by a rope is to be stabilized, is multiplied by a gain determined by a rope length to a swing amount of the rope. A crane steadying control method for suppressing runout by negatively feeding back the speed command of the above, wherein the gain is obtained based on the rope length detected by the method according to any one of claims 1 to 4, and the gain and the shake amount are obtained. The product of
A steady rest control method for a crane, wherein negative feedback is provided to a speed command of a trolley drive device.