CN110872057A - Swing reducing system for crane load - Google Patents
Swing reducing system for crane load Download PDFInfo
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- CN110872057A CN110872057A CN201811010043.2A CN201811010043A CN110872057A CN 110872057 A CN110872057 A CN 110872057A CN 201811010043 A CN201811010043 A CN 201811010043A CN 110872057 A CN110872057 A CN 110872057A
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- crane
- oscillation
- reducing system
- swing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C13/00—Other constructional features or details
- B66C13/04—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack
- B66C13/06—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack for minimising or preventing longitudinal or transverse swinging of loads
- B66C13/063—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack for minimising or preventing longitudinal or transverse swinging of loads electrical
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C13/00—Other constructional features or details
- B66C13/18—Control systems or devices
- B66C13/48—Automatic control of crane drives for producing a single or repeated working cycle; Programme control
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- Mechanical Engineering (AREA)
- Automation & Control Theory (AREA)
- Control And Safety Of Cranes (AREA)
Abstract
The invention provides an oscillation reducing system for crane load, which comprises a crane, an intelligent camera, a load, an index and a guide interface. The crane comprises a base, a fixing frame, a front arm, a suspension arm and a suspension line, wherein the fixing frame is arranged on the base, the base is connected with the suspension arm through the front arm, and the suspension arm is connected with the suspension line. The intelligent camera is composed of a video camera and a computer and is arranged at the front end of the suspension arm. The load is connected with a suspension line through a hook, the index is placed at the top of the hook, the suspension line penetrates through the center of the hook, and the image and the position of the load are acquired by an intelligent camera. The guide interface is arranged on the fixed frame and comprises a light-emitting diode and a rotary control rod; two light-emitting diodes are used for indicating an operator to input a control command. Therefore, the oscillation reducing system for the crane load can help a novice operator to reduce the oscillation movement of the load.
Description
Technical Field
The present invention relates to an oscillation reducing system for crane loads, and more particularly, to an oscillation reducing system for crane loads that helps a novice operator to reduce load oscillations.
Background
Since the introduction of cranes into the construction industry for use, cranes have played an important role in the construction industry. In general, a crane is used to transport building materials from one point to another point in a construction site, and the crane is used to perform a transport work, so that the efficiency of the transport work becomes a key factor affecting the progress of a construction project. Accordingly, the working time of the crane is minimized, and the efficiency of the construction project can be improved.
Secondly, the crane cycle can be divided into three parts, including lifting the load, transporting the load and lowering the load. By accelerating the transport phase (mainly the horizontal rotation of the cantilever), the duration of the operating cycle can be reduced. However, accelerating the rotation of the crane boom reckless may result in severe oscillatory movements of the suspended load. This is an undesirable phenomenon in construction sites as it can pose a danger to the surrounding environment. Furthermore, if the oscillating movement exceeds the tolerance level, the operator must wait until it stops before any further operations can be performed. Thus, the main problem of crane control is to move the load as fast as possible while preventing its oscillating movement.
In practice, the crane operator can reduce the oscillations of the load by means of special control techniques. During the transport phase, an experienced operator prevents the load from oscillating substantially by continuously varying the rotation speed of the boom. In case the prevention of oscillations is not successful at the end of the transport phase, the operator may compensate for the oscillations by an additional gyrating motion. One of the compensation methods performed after the transport phase is to rotate the boom in the direction of the load oscillation, which oscillation can be considerably eliminated if the operation is expedient. The actual operation is generally repeated by turning and stopping the boom. In a controlled slewing motion, acceleration and deceleration of the boom exerts a force on the load. If a force is applied in the proper time and direction, negative work can be done on the load, which reduces the energy of the oscillating motion. However, if the boom is not properly controlled, the negative work caused is reduced, resulting in a poor swing reducing effect.
Furthermore, a major obstacle for a novice operator to perform swing reducing operations after a transport phase may be a lack of timing for controlling the boom. Inexperienced operators may have difficulty accelerating and decelerating the boom at optimal times. Which reduces its oscillating damping effect. Thus, novice operators may spend more time completing the same hauling task than experienced operators. As experienced operators age, the need for automated solutions is increasing.
In view of the foregoing, there is a need for a system to guide a novice operator in compensating for oscillations in a slice of a rotating crane. In view of the above, the present inventors have been invested in a variety of research and development energies and spirits, and have continued to make breakthroughs and innovations in the field, and have been expecting to solve the conventional deficiencies by a novel technical means, and have promoted industrial development in addition to bringing about a more excellent product to society.
Disclosure of Invention
The invention mainly aims to provide an oscillation reducing system for a crane load, and mainly aims to help a novice operator to reduce load oscillation during crane operation. In order to simplify the control of the oscillation reducing system of the crane load, the repeated rotation and stop of the suspension arm are reduced to one time of starting and stopping; that is, the operator need only input a simple command to start and stop rotation. By directing the operator to rotate and stop the boom at the appropriate time and direction, the negative work experienced by the load is maximized. The swing reducing system for the crane load can shorten the difference between the swing reducing capabilities of a novice operator and an experienced operator. Furthermore, the swing reducing system for crane loads of the present invention attempts to reduce the swing problem by guiding the operator rather than directly controlling the crane, since the commands input by the human operator and the computer may interfere with each other, resulting in limited swing reduction.
To achieve the above objective, the present invention provides an oscillation reducing system for crane load, which includes a crane, a smart camera, a load, an index and a guiding interface. Firstly, the crane comprises a base, a fixing frame, a front arm, a suspension arm and a suspension line, wherein the fixing frame is arranged on the base, the base is connected with the suspension arm through the front arm, and the suspension arm is connected with the suspension line. Secondly, the intelligent camera is composed of a video camera and a computer, and is arranged at the front end of the suspension arm, and the computer stores a template in advance. Furthermore, the load is connected with the suspension line through a hook, an image of the load is acquired through the intelligent camera, a position of the load is sensed, an angle, an angular speed and an oscillation direction of the load on a tangential plane can be calculated through the position of the load, and a guide signal is sent out. In addition, the pointer is placed on top of the hook, and the hanging line passes through the center of the pointer, and the pointer is extracted from the image. In addition, the guide interface is arranged on the fixed frame and comprises two light emitting diodes and a rotary control rod, the rotary control rod is used for controlling the rotary motion of the suspension arm, and the guide interface utilizes the two light emitting diodes to indicate an operator to input a control command at a proper moment; when the load firstly passes through a balance point of a tangential oscillation motion, an operator is guided to execute the control command, and the swing control rod is used for controlling the suspension arm to rotate in the corresponding direction; when the load passes through the same balance point for the second time, the operator is guided to execute the control command to stop the boom. Wherein the computer includes a program that is compiled in a National Instrument Builder for Automated Inspection (VBAI) to provide a kit including a plurality of machine Vision tools.
In the oscillation reducing system for crane load of the present invention, a three-axis stabilizer is further included, which is disposed at the front end of the boom and connected to the smart camera.
In the oscillation reducing system of the crane load, the rotation motion of the boom is divided into a constant acceleration stage, a constant speed stage and a constant deceleration stage, and the constant acceleration stage and the constant deceleration stage are used for interfering with an oscillation motion of the load.
In the swing reducing system for a crane load according to the present invention, the control command includes an on command and an off command, the boom starts to accelerate in the constant acceleration stage when the on command is input, the constant acceleration stage is ended and the constant acceleration stage is entered when a target speed determined by a degree of pulling or pushing the swing lever is reached, and the input control command is maintained at the on command in the constant acceleration stage and the constant acceleration stage.
In the oscillation reducing system for crane load of the present invention, the smart camera includes an image sensor, and the smart camera controls the two light emitting diodes by a pulse signal to turn on or off the two light emitting diodes.
In the swing reducing system for crane load according to the present invention, it is possible to have a threshold value applied to the image according to the color of RBG, the threshold value allowing only a pixel having a B value ranging from 160 to 255 and an R value and a G value ranging from 0 to 130 to pass through.
In the oscillation reducing system for a crane load according to the invention, the load has an oscillation angle θ, and the actual vertical distance between the load and a middle line L is dpmThe vertical distance between the load and the middle line L of an image sensor is disThe length of the suspension line suspending the load is l, and the oscillation angle θ can be calculated as follows:
in the swing reducing system for crane load of the present invention, the length of the suspension line is l, and an actual distance d needs to be obtainedpmTo calculate θ, when θ is small, cos θ ≈ 1, assuming that the vertical distance lcos θ ≈ l between the smart camera and the load, a scene width WsAnd an image sensor width WisThe ratio between is the ratio between l and the focal length f of the lens
And the actual distance dpmTo be provided with
Calculating the oscillation angle of the load
In the oscillation reducing system of crane load of the present invention, the angular velocity ω of the oscillating motion is calculated by the following equation θ1Is the current oscillating angle of the load in the frame, and θ0For the oscillation angle in the last processed picture, δ t is the time difference between the two pictures
Further, the oscillation reducing system of a crane load of the present invention determines whether it is an appropriate timing to perform oscillation reduction. If the result is negative, the invention will continue to process subsequent frames. If the result is positive, the pilot signal is output to indicate the operator. Since the state of the load is measured through the picture of the image, the swing reducing system of the crane load of the present invention repeatedly operates.
The present invention aims to propose a vision-based guided oscillation reduction method that does not require complex control. Our goal is to direct the novice operator to reduce the oscillatory motion of the load on the tangent plane of the crane. Instructing the operator to rotate and stop the boom of the crane only at the appropriate time and direction. The present invention uses the smart camera on the tip of the boom of the crane to observe the motion of the load. A guidance interface is applied to instruct the operator to perform simple such control commands on the slewing system of the crane jib at the appropriate time and direction. By the slewing movement of the boom of the crane, oscillations of the load can be reduced. By guiding the operator at the appropriate time, it is expected that the amount of energy reduced during operation is maximized. In other words, the aim of the invention is to guide the novice operator to perform a compensating movement to dampen oscillations, since if severe oscillations occur at the end of the transport phase of the lifting task, an experienced operator will perform a compensating movement to dampen oscillations.
The invention utilizes the directed control instructions to control the crane to reduce tangential oscillations of the load based on observing the load with the smart camera. Typically a conventional crane operating cycle, the operator adjusts the control commands input to the crane by observing the load. Next, the operator manipulates the swing lever to control the movement of the boom arm. When the boom is moved, the load is influenced by the motion of the boom. The operator then adjusts subsequent control commands based on the continuous observations. The smart camera of the present invention takes the image of the load, and then analyzes the state of the load and guides an operator according to the state. The present invention does not control the crane itself, but allows the operator to decide whether to perform the suggested operation. Thus, the present invention preserves the ability of the operator to respond to unforeseen circumstances that may not be considered in an automated system.
Drawings
FIG. 1 is a schematic view of an oscillation reducing system for a crane load according to the present invention.
FIG. 2A is a schematic view of the load and applied acceleration of the swing reducing system of the crane load according to the present invention.
FIG. 2B is a schematic view of the load and applied acceleration of the swing reducing system of the crane load according to the present invention.
FIGS. 3A and 3B are schematic diagrams of the crane load oscillation reducing system according to the present invention, showing the acceleration and gravitational acceleration applied to the load.
FIG. 4 is a schematic view of the swing reducing system for crane load according to the present invention.
FIG. 5A is a side view of the smart camera mounting of the swing reducing system of the crane load according to the present invention.
FIG. 5B is a top view of the smart camera installation of the swing reducing system for crane loads according to the present invention.
FIG. 6 is an image obtained by the smart camera of the oscillation reducing system of the crane load according to the present invention.
FIG. 7 is a schematic diagram of the crane load swing reducing system according to the present invention.
Fig. 8A is an original image of the load of the present invention.
FIG. 8B is an image of the present invention after loading a threshold.
Fig. 9 is a binary image of the load of the present invention.
Fig. 10A is a schematic diagram of a smart camera and load of the present invention.
Fig. 10B is a schematic diagram of an image taken by the smart camera of the present invention.
Fig. 11 is a schematic diagram of the scene width and the width of the image sensor.
FIG. 12 is a schematic view of the swing reducing system for crane load according to the present invention, which is used to simulate the load of a crane.
FIG. 13 is a graph showing the load of the swing reducing system of the crane load according to the present invention for numerical simulation.
FIG. 14 shows the results of uncontrolled oscillations of the load in the swing reducing system of the crane load according to the present invention.
Fig. 15 is an oscillation control in which an experienced operator performs oscillation reduction without oscillation reduction.
FIG. 16 shows the results of the oscillation of the swing reducing system of the crane load under the control of a novice operator according to the present invention.
FIG. 17 is a comparison graph of uncontrolled oscillations, controlled oscillations of an experienced operator performing oscillation reduction without the system of the present invention, and controlled oscillations of a novice operator performing oscillation reduction using the system of the present invention.
FIG. 18 is a comparative line graph of uncontrolled oscillations, an experienced operator without the inventive system, and a novice operator of the inventive system.
Description of the reference numerals
1 Crane load swing reducing system 10 crane
101 stand 102 fixing frame
103 front arm 104 suspension arm
1041 front end 105 suspension line
Three-axis stabilizer for 20 intelligent camera 201
30 load 301 hook
40 index 50 guide interface
Detailed Description
The following embodiments of the present invention are provided by way of examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. Moreover, the invention is capable of other and different embodiments and of being practiced or being carried out in various ways without departing from the spirit of the invention.
Referring to fig. 1, fig. 1 is a schematic view of an oscillation reducing system for a crane load according to the present invention.
As shown in FIG. 1, the present invention provides an oscillation reducing system 1 for crane load, comprising: a crane 10, a smart camera 20, a load 30, a pointer 40, and a guidance interface 50. Firstly, the crane 10 includes a base 101, a fixing frame 102, a front arm 103, a suspension arm 104 and a suspension line 105, wherein the fixing frame 102 is installed on the base 101, the base 101 is connected with the suspension arm 104 through the front arm 103, and the suspension arm 104 is connected with the suspension line 105. Next, the smart camera 20 is composed of a camera and a computer, and is disposed at a front end 1041 of the boom 104, and the computer stores a template in advance to sense a position of the load 30. Furthermore, an image of the load 30 is acquired by the smart camera 20 through a hook 301 connected to the suspension wire 105, and an angle, an angular velocity and an oscillation direction of the load 30 on a tangential plane are calculated from the position, and a guiding signal is sent. In addition, the pointer 40 is placed on top of the hook 301, and the hanging line 105 passes through the center of the pointer 40, and the pointer 40 is extracted from the image. In addition, the guiding interface 50 is disposed on the fixing frame 102, and includes two light emitting diodes and a rotation control rod, wherein the rotation control rod is used to control a rotation motion of the suspension arm 104, and the guiding interface 50 uses the two light emitting diodes to instruct an operator to input a control command at a proper time; wherein, when the load 30 first passes an equilibrium point of a tangential oscillatory motion, an operator is guided to execute the control command, and the boom 104 is controlled to rotate in a corresponding direction by the rotary control rod; when the load 30 passes the same balance point for the second time, the operator is guided to execute the control command to stop the boom 104.
Referring to fig. 2A and 2B, fig. 2A is a schematic view of a load and an applied acceleration; fig. 2B is a schematic diagram of an oscillating load and applied acceleration.
As shown in fig. 2A and 2B, the present invention aims to maximize the energy that is reduced during the acceleration and deceleration phases when executing the control command. As shown in fig. 2A, if an acceleration is applied to the upper portion of the load 30, the load will accelerate in the opposite direction by the same value. As can be seen from the upper part of the load. According to the kinetic theorem, the effect of acceleration on the load 30 is equal to the change in the total energy in the load 30. As shown in fig. 2B, the load 30 applies acceleration in the opposite direction, and the load 30 oscillates in a stroke from point P1 to point P2. In this case, the acceleration is doing negative work on the load 30. In other words, acceleration is reducing the energy of the oscillating motion. The invention therefore aims to maximise the negative work done on the load during the acceleration and deceleration phases.
Secondly, as shown in fig. 2B, the load 30 of mass m and the suspension line of length l oscillate from point P1 to P2. Over the entire stroke, an acceleration a is exerted on the load 30 in the opposite direction. The load 30 is driven from theta1Move to theta2The angle indicated is counterclockwise and starts from the vertical. Therefore, in this case, θ1Is positive and theta2Is negative. This indicates that the tangential component of the acceleration a can be expressed as acos θ, whether θ is positive or negative. Furthermore, when θ is small, cos θ ≈ 1. This indicates acos θ ═ a. Therefore, the negative work done by the acceleration on the load 30 can be calculated as follows:
since the mass m, the acceleration a and the length l remain constant, the formula indicates the angle (θ)1-θ2) The larger the load 30 moves in the original direction during the application of acceleration in the opposite direction, the more negative work is performed on the load 30. Thus, by varying the acceleration and deceleration stepsMaximizing the angle of travel of the load 30 during a segment maximizes the energy reduction.
Referring to fig. 3A and 3B, fig. 3A and 3B are schematic diagrams illustrating an acceleration and a gravitational acceleration applied to a load.
As shown in fig. 3A and 3B, when the acceleration a starts to be applied to the load 30, there is an initial angular velocity ω0. Fig. 3A shows the applied acceleration a and its tangential component acos θ, while fig. 3B shows the applied gravitational acceleration g and its tangential component gsin θ. If an acceleration a is applied to the load 30 taSecond, at acceleration θa＝(θ1-θ2) The angle traveled by the load 30 during the period can be expressed by equation 2.
If θ is small, then cos θ ≈ 1 and sin θ ≈ θ ≈ 0. Therefore, equation 2 can be simplified to equations 3 and 4.
According to formula 4, due to taA and l are kept constant, the initial angular velocity ω0Only the travel angle theta is determinedaThe value of (c). Therefore, a larger ω0Contribute to a larger thetaa. According to the law of conservation of energy, the maximum angular velocity of the load occurs at the point of equilibrium, while the load is at the lowest altitude. Since the potential energy of the load is completely converted into kinetic energy. Thus, if acceleration is applied to the load in the opposite direction starting at the equilibrium point, the angle at which the load travels in the original direction can be maximized. In this case, the initial angular velocity ω in equation 40Is the speed of the load at the point of equilibrium. Omega0Can be calculated using the law of conservation of energy. Assuming that the potential energy of the load at the highest point is completely converted into kinetic energy at the equilibrium point, the relationship between the potential energy U and the kinetic energy can be written as equation 5.
θhIs the angle of the load at the highest point. Then, equation 5 can be simplified to equation 6.
Formula 6 can be converted to formula 7.
The swing reducing system of the present invention accelerates the boom when the load first passes the balance point. The boom is then decelerated as the load oscillates backwards and passes the balance point a second time. The direction in which the boom rotates must be the same as the direction in which the load first passes through the balance point.
Referring to fig. 4A to 4D, fig. 4A to 4D are schematic views of the load of the swing reducing system of the crane load according to the present invention.
As shown in fig. 4A, the load initially oscillates from right to left. As shown in fig. 4B, when the load 30 first passes the balance point, the boom tip begins to accelerate in the oscillating direction. At the same time, the load 30 has an initial angular velocity ω in the initial oscillation direction0And has an acceleration a in the opposite direction. As shown in fig. 4C, during the acceleration duration taThereafter, the boom ground tip reaches a target speed VtargetAt this time, the acceleration of the boom is ended. Therefore, the end of the acceleration applied to the load can be observed, and the remaining angular velocity ω' can be observed. Then, when the load returns to the equilibrium point in the opposite direction, the boom starts to move from VtargetAnd (5) decelerating. Therefore, the acceleration a is applied to the load in the original direction. At taAfter that, the boom is stopped and the derotation is finished. According to formulas 1, 4 and 7, the expression energy W is reduced by controlling as follows:
in equation 8, m, a, l, and t are variables of the oscillation damping system of the crane load. To effect control of the system, the swing reducing system of the crane load guides the operator to input an on command in the corresponding direction when the load 30 first passes the balance point. The swing reducing system of the crane load then guides the operator to enter an off command when the load passes the balance point again.
Referring to fig. 5A, 5B and 6, fig. 5A is a side view of the installation of the smart camera of the swing reducing system for crane load according to the present invention; FIG. 5B is a top view of the smart camera mounting of the swing reducing system of the crane load according to the present invention; and FIG. 6 is an image obtained by the smart camera of the oscillation reducing system of the crane according to the present invention.
As shown in fig. 5A and 5B, to acquire an image 201 of the load, the smart camera 20 is mounted on the front end 1041 of the boom 104 of the crane. As shown in fig. 5A and 5B, the smart camera 20 is vertically installed so as to horizontally acquire the image 201. The smart camera 20 is aligned with the boom 104 such that the horizontal axis of the image 201 is parallel to the tangent of the crane's boom 104 rotation. As shown in fig. 6, when the load 30 is at the equilibrium point of the tangential oscillatory motion, the load 30 will stay on the middle line L of an acquired image.
As shown in fig. 5A and 5B, in order to know an oscillation angle, an angular velocity and an oscillation direction of the load 30, the position of the load 30 is obtained first. Thus, the load 30 is tracked by the swing reducing system for crane loads of the present invention. First, the smart camera 20 captures the image 201, processes the image 201 to remove unnecessary information, and searches the entire image 201 for the load 30 according to a pre-stored template. Since the image 201 is pre-filtered, the edges of the load 30 are very visible. Thus, an edge matching algorithm using pre-stored templates finds the load 30 throughout the image 201. The position of the load 30 is then updated. If the subtraction has not been completed, the smart camera 20 will acquire another image 201 and filter it. The load 30 is then tracked by a mean shift tracking method, searching for the load 30 based on pre-stored templates in the vicinity of the last location. If the load 30 is found, a new location will be updated. The above steps are repeated to track the load 30. In case the load 30 is not found by the mean shift tracking method, the tracking process will be interrupted and the same edge matching algorithm is used to search for the load 30 throughout the image 201. After the load 30 position is retrieved, the subsequent tracking cycle will be updated. This image 201 filtering process is necessary to enhance the likelihood of tracking success. As shown in fig. 1, 5A, and 5B, the index 401 is attached to the load 30 as the target to be tracked. The purpose of the image 201 filtering process is to extract the indicator 40 from the image 201.
Referring to FIG. 7, FIG. 7 is a schematic diagram of the swing reducing system for crane load according to the present invention. As shown in fig. 7, the pointer 40 is a bright blue circular plate placed on top of the hook 301 with the hanging wire 105 passing through the center thereof. In an image filtering step, a threshold based on the RBG colors is applied to the image 201. The threshold allows only pixels with high B, low R and G values to pass. In one embodiment of the invention, the B values range from 160 to 255, and the R and G values range from 0 to 130. A pixel must simultaneously satisfy the above constraints to pass the threshold; the indicator 40 is the only object in the image 201 with high B value, and also includes some R value and G value. On the other hand, limiting high R and G values may eliminate over-exposed or near-white portions of the image 201.
Referring to fig. 8A, 8B and 9, fig. 8A is an original image of the load according to the present invention; FIG. 8B is an image of the present invention after loading a threshold; and FIG. 9 is a binary image of the load of the present invention.
As shown in fig. 8A, 8B and 9, the image before the threshold and the image after the threshold. The resulting image is changed to a binary image, and as shown in fig. 9, the pixels that pass the threshold become white, while the pixels that fail become black. The image processing is used to ensure successful load tracing.
Referring to fig. 10A and 10B, fig. 10A is a schematic diagram of a smart camera and a load according to the present invention; and FIG. 10B is a schematic diagram of an image taken by the smart camera of the present invention.
After the position of the load 30 is obtained, an oscillation angle can be calculated, as shown in fig. 10A and 10B. The load 30 has an oscillation angle theta. The actual vertical distance between the load 30 and the middle line L is dpm. The vertical distance between the load 30 and the middle line L of an image sensor is dis. The suspension line 105 suspending the load 30 has a length l. The oscillation angle θ can be calculated as follows.
Referring to fig. 11, fig. 11 is a schematic diagram illustrating a scene width and a width of the image sensor.
As shown in FIGS. 10A, 10B and 11, assuming that the length of the suspension wire 105 is known to be l, it is necessary to obtain an actual distance dpmTo calculate theta. When θ is small, cos θ ≈ 1. As shown in FIG. 10A, it may be assumed that the vertical distance lcos θ ≈ l between the smart camera and the load 30. In FIG. 11, a scene width WsAnd the width W of the image sensorisThe ratio between is the ratio between l and the focal length f of the lens, as shown in equation 10 below.
According to the above relation, the actual distance dpmIt can be calculated as follows:
from equations 9 and 11, the oscillation angle θ of the load is calculated as follows:
in one embodiment, the x-axis direction of the image is as shown in FIG. 10B. By means of Xmiddle-XpayloadTo calculate the distance dis. Thus, if the load is located on the right side of the image, dis>0, if the load is on the left side of the image, dis<0. After obtaining the oscillation angle of the load, the angular velocity and the oscillation direction can be calculated. The angular velocity ω of the oscillating motion is calculated as follows.
In formula 13, θ1Is the current oscillation angle of the load in the frame, and θ0Is the oscillation angle in the picture that is finally processed. δ t is the time difference between the two pictures. In fact, after processing the frame, the frame just captured continues to be processed. To ensure that an immediate load condition is achieved. On the other hand, the direction of the oscillating motion is determined by the sign of the angular velocity ω. Since the x-axis of the processed image points from left to right, if the load oscillates to the right, ω>0, if the load oscillates to the left, ω<0. When the load first passes the balance point of the tangential oscillatory motion, the operator is guided to control the boom arm to rotate in the corresponding direction. The operator is then guided to stop the boom when the load passes the same point a second time.
Indicating the on command as output t in the corresponding direction before the load passes the balance pointreactAnd second. After the operator executes the control command, the boom starts to accelerate taSeconds and reaches a constant speed phase. The load remains oscillating during this constant speed phase. The load then passes the highest point on the other side and begins to oscillate. Similarly, the off command is output t before the load again passes the balance pointreactAnd second. After the operator executes the control command, the suspension arm starts to decelerate taSecond and finally stop.
The intelligent camera of the crane load oscillation reducing system is provided with a 6 mm C-shaped lens for shooting images. The computer is used to execute the control program of the whole oscillation reducing system, including the sensing of the load and the control of the guide interface. In one embodiment of the present invention, the smart camera processes 16 pictures per second on average. To ensure that the smart camera is mounted vertically at the front end of the crane boom, a three-axis stabilizer is used. In one embodiment of the invention, a wide flat load weighing 88 kg is used for the swing reducing system of the crane load. The marker for aiding vision-based tracking is located above the load. The guide interface is composed of two light emitting diodes indicating left and right, respectively. The two light-emitting diodes controlled by the intelligent camera through pulse signals can be turned on and off. In the guidance interface, the operator is guided to input a left-hand turn-on signal when the light emitting diode indicating the left hand side is turned on. The operator will push the swing lever. On the other hand, when the light emitting diode indicating the right side is turned on, the operator is guided to pull the swing lever. When the light emitting diode is off, the operator is guided to return the swing lever to the neutral position and input a turn-off command.
Furthermore, in one embodiment of the present invention, the angular acceleration of the swing motion of the boom arm is about 0.245rad/sec2. When the swing control lever is fully pushed or pulled, the target angular velocity of the boom is about 0.095rad/sec2. The linear acceleration of the front end of the boom arm is 1.348m/sec2. When the control stick is fully pushed or pulled, the target linear velocity of the front end of the boom arm is 0.525 m/sec. The duration of acceleration and deceleration is ta-0.389 sec.
Referring to fig. 12, fig. 12 is a schematic view of an oscillation reducing system for a crane load according to the present invention for simulating a load of a crane.
The equation of motion of the load is as follows.
A numerical model was calculated in MATLAB R2018a to simulate the behavior of the crane load when implementing the swing reducing system of the load.
Referring to fig. 13, fig. 13 is a diagram illustrating the load of the swing reducing system of the crane load according to the present invention for numerical simulation.
The result of the numerical simulation is shown in fig. 13, in which the load is released from the side having θ of 10 °. Then the acceleration a is 1.348m/sec and when the load passes the balance point a third time, the load t is applied in the opposite direction of its oscillation 0.389 sec. The next time the load passes through balance, it is subjected to a reverse acceleration of the same value for the same duration. As shown in fig. 13, the maximum oscillation angle of the load decreased from 10 ° to 1.61 ° after the oscillation decreased, which was 83.9%.
In another embodiment of the invention, a field test is performed to evaluate the performance of the swing reducing system of the vision-based crane load on a hydraulic rotating crane by checking the swing reducing capability of the swing reducing system. The field test was performed to evaluate the performance of the swing reducing system of the vision-based crane load on a hydraulic rotating crane by checking its swing reducing capability. In these tests, manual swinging on a rotating crane section was generated for testing. The load is manually pulled to the left of the boom tip θ 10 ° and released freely. The smart camera records the angle of oscillation of the load.
Referring to FIG. 14, FIG. 14 shows the result of uncontrolled oscillations of the load in the swing reducing system for crane loads according to the present invention.
As shown in fig. 14, during uncontrolled oscillation testing, the load is free to be released and no further disturbance is applied. It can be seen that the oscillation angle gradually decreases with time. The damping ratio of the oscillation reducing system of the crane load is about 0.0068.
Referring to fig. 15, fig. 15 shows an oscillation control in which an experienced operator performs oscillation reduction without oscillation reduction.
As shown in fig. 15, during the test of an experienced operator without the swing reducing system for crane loads of the present invention, the experienced operator starts control immediately after the load is released. The operator then stops controlling the boom after 27.3 seconds. The duration of the control was 27.3 seconds.
Referring to FIG. 16, FIG. 16 shows the oscillation damping system for crane loads according to the present invention under the control of a novice operator.
As shown in fig. 16, during the operator's period of testing the swing reducing system of the crane load of the present invention, the operator started inputting the on command in 1.14 seconds. The operator then enters the off command at 3.03 seconds. The duration of the control was 1.89 seconds. This second mode of load vibration can be observed from the relatively dense waves shown earlier in fig. 16 after the oscillation reduction control is completed.
Referring to fig. 17, fig. 17 is a graph comparing uncontrolled oscillations, controlled oscillations of an experienced operator performing oscillation reduction without the system of the present invention, and controlled oscillations of a novice operator performing oscillation reduction using the system of the present invention.
As shown in fig. 17, in these graphs, the maximum value is converted to 100%. Thus, the wave is stable in the range of 1 to-1. In addition, the peak envelope is also shown in the graph. The envelope is calculated by means of built-in envelope functions in MATLAB. These envelopes are used to represent the drop in oscillation angle for these tests. As shown in fig. 17, the angle of oscillation controlled by the novice operator is significantly smaller after the oscillation reduction is completed. The oscillation angle of the system of the invention controlled by the novice operator is then even smaller than the oscillation angle controlled by the experienced operator.
In table 1, to further compare the results of the three tests of fig. 17, we compared the 50 th cycle at times 5, 10, 15, 20, 25, 30, 35, 40 and 45 where uncontrolled oscillations occurred in the distance between the upper and lower seals. Since the waves are converted to the range of-1 to 1, it can be assumed that the distance between the upper and lower envelope lines is 2 at the full state of the load system.
TABLE 1
Referring to fig. 18, fig. 18 is a graph comparing uncontrolled oscillations, an experienced operator without the system of the present invention, and a novice operator with the system of the present invention.
As shown in fig. 18, a represents controlled oscillation, B represents an experienced operator without the inventive system, and C represents a novice operator of the inventive system. With the help of the inventive crane load sway mitigation system, novice operators reduce the sway more than experienced operators without the inventive system. In fact, after 23.9 seconds, the remaining oscillation of the untrained novice operator is only 54.7% of the remaining oscillation of the experienced operator. Then, at t-48.0 seconds, the rate decreases to 38.5%. After 144.5 seconds, the ratio is even lower to close to 20% and remains similar in the rest of the recording.
TABLE 2
As shown in table 2, when the control is stopped for 3.03 seconds, the residual oscillation angle of the oscillation reducing system of the crane load according to the present invention is 43.5% of the full state. Meanwhile, the remaining angle of the conventional method is 85.5%. In other words, the swing reducing system of the crane load of the present invention has a 56.5% reduction in angle, while the conventional swing reducing system of the crane load has a 14.5% reduction only at the same time as the swing reducing system of the crane load of the present invention has completed control. When the swing reducing system for crane load of the present invention is completed, the swing reducing system for crane load of the present invention reduces the angle by 3.9 times that of the conventional method. At the time when the experienced operator stops the control, i.e., t is 27.30 seconds, the remaining angle of the conventional method is 25%. Meanwhile, the residual angle of the swing reducing system for the crane load is 13%. In other words, the conventional oscillation angle is reduced by 75%. However, at the same time, the remaining angle of the swing reducing system of the crane load of the present invention is only 52% of the former.
In summary, in this case the sway reduction performed by a novice operator using the inventive crane load sway reduction system is superior to the sway reduction performed by an experienced operator in two aspects without this method. First, the control duration of the swing reducing system for crane load according to the present invention is shorter than that of the conventional method. In fact, the present invention requires only 1.89 seconds, whereas the conventional method requires 27.3 seconds. Second, the oscillation reduction capability of the present invention performed by novice operators is superior to conventional methods performed by experienced operators.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, so that equivalent changes made by using the contents of the present specification and the drawings are all included in the scope of the present invention.
Claims (10)
1. An oscillation reducing system for crane load, comprising:
the crane comprises a base, a fixing frame, a front arm, a suspension arm and a suspension line, wherein the fixing frame is arranged on the base, the base is connected with the suspension arm through the front arm, and the suspension arm is connected with the suspension line;
the intelligent camera consists of a camera and a computer, is arranged at the front end of the suspension arm, and the computer stores a template in advance;
a load connected with the suspension line by a hook, acquiring an image of the load by the intelligent camera and sensing a position of the load, calculating an angle, an angular velocity and an oscillation direction of the load on a tangential plane by the position of the load, and sending a guide signal;
the pointer is placed at the top of the hook, and the suspension line passes through the center of the pointer to capture the pointer from the image; and
the guide interface is arranged on the fixed frame and comprises two light-emitting diodes and a rotary control rod, the rotary control rod is used for controlling the rotary motion of the suspension arm, and the guide interface utilizes the two light-emitting diodes to indicate an operator to input a control command at a proper moment;
when the load firstly passes through a balance point of a tangential oscillation motion, an operator is guided to execute the control command, and the swing control rod is used for controlling the suspension arm to rotate in the corresponding direction; when the load passes through the same balance point for the second time, the operator is guided to execute the control command to stop the boom.
2. The swing reducing system for crane loads as claimed in claim 1, further comprising a three-axis stabilizer disposed at the front end of the boom and connected to the smart camera.
3. The swing reducing system for crane load according to claim 1, wherein the swing motion of the boom is divided into a constant acceleration phase, a constant speed phase and a constant deceleration phase for disturbing an oscillating motion of the load.
4. The swing reducing system for a crane load according to claim 3, wherein the control command includes an on command and an off command, the boom starts to accelerate in the constant acceleration phase when the on command is inputted, the constant acceleration phase is ended and the constant acceleration phase is entered when a target speed determined by a degree of pulling or pushing the swing lever is reached, and the inputted control command is maintained at the on command in the constant acceleration phase and the constant acceleration phase.
5. The swing reducing system for crane loads according to claim 3, wherein the boom starts to enter the constant deceleration phase until stopped when the off command is inputted.
6. The oscillation reducing system of crane load according to claim 1, wherein the smart camera comprises an image sensor, and the smart camera controls the two light emitting diodes by a pulse signal to turn on or off the two light emitting diodes.
7. The swing reducing system for crane load according to claim 1, wherein a threshold value is applied to the image according to the color of RBG, the threshold value allowing only one pixel of a B value ranging from 160 to 255, an R value and a G value ranging from 0 to 130 to pass through.
8. The oscillation reducing system of claim 1, wherein the load has an oscillation angle θ, and the actual vertical distance between the load and a middle line L is dpmThe vertical distance between the load and the middle line L of an image sensor is disThe length of the suspension line suspending the load is l, and the oscillation angle θ can be calculated as follows:
9. the swing reducing system for crane loads according to claim 8, wherein the suspension line has a length l, such that a substantial distance d is requiredpmTo calculate θ, when θ is small, cos θ ≈ 1, assuming that the vertical distance lcos θ ≈ l between the smart camera and the load, a scene width WsAnd an image sensor width WisThe ratio between is the ratio between l and the focal length f of the lens
And the actual distance dpmTo be provided with
10. The opener of claim 1Swing reducing system for a heavy machine load, wherein the angular velocity ω of the oscillating motion is calculated by the following equation, θ1Is the current oscillating angle of the load in the frame, and θ0For the oscillation angle in the last processed picture, δ t is the time difference between the two pictures
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| CN201811010043.2A CN110872057A (en) | 2018-08-31 | 2018-08-31 | Swing reducing system for crane load |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115884937A (en) * | 2020-08-05 | 2023-03-31 | 科尼全球公司 | Jib slewing crane with camera and method for reducing load pendulum during crane operation |
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