A weight measurement method for crane monitoring system

Abstract

The present invention relates to the field of measurement technology, and in particular to a weight measurement method for a crane monitoring system. The method first obtains the output power and lifting height of the hoisting motor of the crane; according to the historical data corresponding to the crane, the relationship between the output power of the crane and the length of the wire rope is fitted to obtain the initial hoisting weight excluding the influence of the wire rope. The acceleration is obtained by analyzing the operation process of the crane, which is used to subsequently eliminate the influence of the acceleration and accurately obtain the net hoisting weight of the crane. Based on the force calculation formula, the actual hoisting weight after eliminating the influence of the acceleration is obtained in combination with the acceleration; the present invention calculates the power of the hoisting motor from the current and voltage parameters that are easy to obtain from the installation angle, and combines the acceleration value obtained during operation to accurately calculate the actual hoisting weight, and eliminates the influence of the wire rope on the actual hoisting weight of the crane, thereby improving the accuracy of the hoisting weight obtained during the crane weight measurement.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, and in particular to a weight measurement method for a crane monitoring system. Background Art

[0002] The crane monitoring system collects signals such as the crane's lifting weight, travel and height, operating actions, and limit closure status, and conducts comprehensive analysis and judgment. It is mainly used for recording, analyzing, and warning the crane's operating and operation conditions.

[0003] Since cranes are special equipment, in order to ensure safe operation, the country issued a special national standard GB / T28264-2017 in 2017, which made clear requirements for crane safety monitoring systems and must collect crane weight signals. At present, in terms of crane weight measurement in the monitoring system, in order to obtain the on-site lifting weight signal, the common fixed end of the wire rope is not exposed, and the side pressure weight sensor cannot be newly installed, making it difficult to collect the actual lifting weight of the crane, and the subsequent lifting weight measurement will be greatly affected by the length of the wire rope. Summary of the invention

[0004] In order to solve the technical problem that the error in crane weight measurement is greatly affected by the length of the wire rope, the purpose of the present invention is to provide a weight measurement method for a crane monitoring system, and the technical solution adopted is as follows:

[0005] Obtain the motor current, motor voltage and lifting height of the hoisting motor of the crane;

[0006] The output power of the winch motor is obtained by combining the motor current and the motor voltage; the relationship between the output power of the crane and the length of the wire rope is fitted according to the historical data corresponding to the crane, and the real-time output power of the crane and two different wire rope lengths are input into the fitted relationship to obtain the initial hoisting weight;

[0007] The operation process of the crane is interrupted by a timer, and the lifting heights during adjacent interruptions are analyzed to obtain the acceleration. Based on the force calculation formula, the actual lifting weight after eliminating the influence of acceleration is obtained in combination with the acceleration.

[0008] Preferably, fitting the relationship between the output power of the crane and the length of the wire rope according to the historical data corresponding to the crane includes:

[0009] The power acquisition value is p0, the height above the ground is h0, and the corresponding wire rope length is L0;

[0010] The power collection value is p1, the height from the ground is h1, and the corresponding wire rope length is L1;

[0011] The power collection value is p2, the height from the ground is h2, and the corresponding wire rope length is L2; ​​...;

[0012] The power collection value pn, the height above the ground is hn, and the corresponding wire rope length is Ln;

[0013] According to the historical data corresponding to the above cranes, the relationship between the output power of the crane and the length of the wire rope is fitted;

[0014] p=k*L+b

[0015] Among them, p is the power collection value; k is the slope in the relationship; b is the intercept in the relationship; L is the length of the wire rope.

[0016] Preferably, the real-time output power of the crane and two different wire rope lengths are input into the fitted relationship to obtain the initial hoisting weight, including:

[0017] The conversion formula for the relationship is:

[0018] p0'=k*(L1-L0)+p0

[0019] Among them, p0' is the power collection value when the converted wire rope length is L1 and the hook is empty; k is the slope; L1 and L0 are two different wire rope lengths; p0 is the power collection value when the original wire rope length is L0 and the hook is empty;

[0020] The calculation formula for the power collection value containing only weights is:

[0021] py=Px–(k*(Lx-L0)+p0))

[0022] Among them, py is the power collection value containing only weights, Px is any power collection value; L0 is the set wire rope length; Lx is any wire rope length other than the wire rope length L0;

[0023] The calculation formula for the initial hoisting weight containing only heavy objects and excluding the influence of the length of the wire rope is:

[0024] Py=(py-p0') / (p1-p0')×(Pr)

[0025] Among them, Py is the initial hoisting weight, that is, only the weight of the heavy object, excluding the weight of the wire rope; p0' is the power collection value when the converted wire rope length is L1 and the hook is empty; p1 is the power collection value when the wire rope length is L1 and the weight is hoisted; Pr is the actual hoisting value when the wire rope length is L1; py is the weight collection value containing only the heavy object.

[0026] Preferably, the method further comprises a weight suspension processing algorithm:

[0027] An intermediate variable is set in the weight measurement algorithm of the crane monitoring system to memorize the last collected current value of the hoisting motor;

[0028] When the falling edge of the lifting or lowering signal arrives, that is, when the winch is to be stopped, the last collected current value memorized in the previous step is sealed and stored in another global variable;

[0029] When the machine is stopped, that is, when there is neither an upward nor downward signal, the weight is calculated based on the current value stored in the above steps.

[0030] Preferably, the method of interrupting the operation of the crane by a timer, analyzing the lifting heights during adjacent interruptions, and obtaining the acceleration includes:

[0031] In the acquisition hardware, the timer interrupt method is used to process, and a 1ms pulse interrupt is taken. The change in height h is processed in the interrupt function as Δh1=h2-h1, where h2 is the real-time hook height obtained by this 1ms interrupt, and h1 is the hook height obtained by the last 1ms interrupt; when the second 1ms interrupt edge arrives, let h2 be the hook height measured at the second interrupt, Δh1=h2-h1, and the weight-lifting speed is v1=Δh1 / 1ms; when the third 1ms interrupt edge arrives, let h3 be the hook height measured at the third interrupt, then Δh2=h3-h2, and the hook speed is v2=Δh2 / 1ms;

[0032] The acceleration is calculated as:

[0033]

[0034] Among them, Δv is the speed change value; Δt is the time change value; v2 is the hook speed at the current moment; v1 is the hook speed at the previous moment; Δh2 is the height difference collected between the next moment and the current moment; Δh1 is the height difference collected between the current moment and the previous moment; h3 is the height corresponding to the next moment; h2 is the height corresponding to the current moment; h1 is the height corresponding to the previous moment.

[0035] Preferably, the force-based calculation formula, combined with acceleration, obtains the actual hoisting weight after eliminating the influence of acceleration, including:

[0036] When the crane hook moves upward with acceleration, the calculation formula for the actual lifting weight is:

[0037] m=Py / (a+g)

[0038] Among them, m is the actual hoisting weight; Py is the initial hoisting weight; a is the acceleration; g is the gravitational acceleration.

[0039] The embodiments of the present invention have at least the following beneficial effects:

[0040] The present invention reads the lifting height signal and runs a newly designed weight calculation calibration method during weight measurement, thereby eliminating the influence of the length and weight of the wire rope on the actual lifting weight of the crane. At the same time, by calculating the acceleration of the crane hook during operation, the influence of the acceleration on the actual lifting weight of the crane is further eliminated, thereby improving the accuracy of the lifting weight acquisition during the crane weight measurement. Since the present invention does not rely on the installation of a weight sensor and only needs to add a current transformer that is easy to install, it has a relatively large practical significance for occasions where the weight sensor cannot be applied, and the measurement accuracy is also high. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A method flow chart of a weight measurement method for a crane monitoring system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a weight measurement method for a crane monitoring system proposed by the present invention, its specific implementation, structure, features and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0044] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0045] The embodiment of the present invention provides a specific implementation method of a weight measurement method for a crane monitoring system, and the method is suitable for crane hoisting weight measurement scenarios. This is to solve the technical problem that the error in crane weight measurement is greatly affected by the length of the wire rope. Starting from practical applications, the present invention designs a weight monitoring module based on current and voltage. There should be a lifting height signal in the crane monitoring system, so the lifting height signal can be read directly; the present invention only needs to increase the measurement of motor current and motor voltage, or it can be said that a current and voltage signal acquisition channel is added. The collected motor current and motor voltage provide realistic conditions for the proposal and application of the present invention. The newly designed weight calculation and calibration method is run in this module with high accuracy, and is mainly used in the monitoring system of cranes.

[0046] A specific scheme of a weight measurement method for a crane monitoring system provided by the present invention is described in detail below with reference to the accompanying drawings.

[0047] See also Figure 1 , which shows a flow chart of a weight measurement method for a crane monitoring system provided by an embodiment of the present invention, the method comprising the following steps:

[0048] Step S100, obtaining the motor current, motor voltage and lifting height of the hoisting motor of the crane.

[0049] The lifting height is obtained by monitoring the original signal of the system, and the lifting height is used to calculate the length of the wire rope, removing the influence of the wire rope. In the embodiment of the present invention, the wire rope is a tool used by the crane to lift heavy objects.

[0050] The motor current of the hoisting motor is obtained through the open current transformer installed on the hoisting motor of the crane. The motor current is used to calculate the current size and Fast Fourier Transform (FFT) analysis to obtain the slip rate of the hoisting motor. The open current transformer can be installed without dismantling the power line, which is easy to implement. Voltage acquisition realizes the two functions of power supply and acquisition. In other words, the voltage signal is divided into two paths after entering the module. One path is used to power the CPU after voltage conversion, and the other path enters the acquisition circuit after conversion.

[0051] The motor voltage of the winch motor is obtained through the voltage sensor. This motor voltage is used to calculate the motor output shaft power and is also used as the power supply for the module after conversion.

[0052] Step S200, combining the motor current and the motor voltage to obtain the output power of the winch motor; fitting the relationship between the output power of the crane and the length of the wire rope based on the historical data corresponding to the crane, inputting the real-time output power of the crane and two different wire rope lengths into the fitted relationship to obtain the initial lifting weight.

[0053] According to common sense of mechanics, the power output of the winch motor is used to lift heavy objects. Assume that the upward lifting force is F1, and record F1 as the accelerated weight. The accelerated weight includes not only the original weight of the heavy object, but also the force generated during the accelerated motion. The mass of the heavy object is m, the magnitude of the acceleration is a, and the gravitational acceleration is g. There are four cases in total, as shown in Table 1 below:

[0054] Table 1

[0055] Serial number situation Acceleration direction formula 1 Accelerate upward up F1=mg+ma 2 Slow down upward down F1=mg-ma 3 Downward acceleration down F1=mg-ma 4 Slow down up F1=mg+ma

[0056] In the above table, there are three unknown quantities, namely the lifting force F1, the mass m of the weight, and the acceleration a. Among them, the mass m of the weight is the quantity to be determined. First, calculate the magnitude of the acceleration a. Finally, analyze the calculation of the lifting force. In the embodiment of the present invention, the lifting force is replaced or approximated by the output power. In the description of eliminating the influence of the rope length, Wy is the output power parameter of the motor. Therefore, the starting point of the embodiment of the present invention is that due to various restrictions, when the weight sensor cannot be installed, the motor voltage and motor current of the winch motor are used to calculate the actual output power, and the actual lifting weight is calculated using the power. In the calculation process, the influence of acceleration and the influence of the length of the wire rope are eliminated, and the calculation result is more accurate, which solves the practical problems in field applications.

[0057] That is, in the embodiment of the present invention, the lifting force F1 is replaced by the output power P of the hoisting motor. After the actual output power is calculated by the motor voltage and motor current of the hoisting motor, the actual hoisting weight is calculated in combination with the output power.

[0058] Specifically, the calculation formula for output power is:

[0059]

[0060] Among them, P is the output power; U is the motor voltage of the winch motor; I is the motor current of the winch motor; is the power factor; In the embodiment of the present invention, the values ​​of the power factor and the motor transmission efficiency are specifically set by the implementer according to the actual situation.

[0061] It should be noted that the method of obtaining power according to voltage and current is a well-known technology to those skilled in the art and will not be described in detail here.

[0062] Furthermore, in the process of crane lifting heavy objects, as the lifting height or lowering depth changes, the length of the wire rope also changes continuously.

[0063] Whether the weight is detected by current or by installing a lateral pressure weight sensor, the influence of the wire rope length needs to be considered, because for the winch motor, the weight generated by the length of the wire rope is the same as the weight of the lifted object, and both require the winch motor to do work to lift it.

[0064] However, during the lifting and lowering of the hoisting motor, the length of the wire rope is constantly changing, which requires the weight calculation algorithm to constantly correct the influence of the change in the length of the wire rope. Currently, it is common to use the product of the density of the wire rope and the length of the wire rope as the weight of the wire rope after obtaining the length of the wire rope. However, due to the large differences in the thickness, material, and arrangement method of the wire rope, it is difficult to obtain the data of the density of the wire rope. Once the density is inaccurate, it will affect the calculation of the weight of the wire rope, resulting in a large error in the calculation of the weight of the wire rope. Therefore, in order to avoid the problem of large errors in the method of obtaining the weight of the wire rope by density, the present invention designs a method that can automatically eliminate the influence of the weight of the wire rope and accurately obtain the weight of the hoisted heavy object.

[0065] Assume that the length of the wire rope is l, denoted as the wire rope length; the height of the crane hook from the ground is h, that is, the lifting height of the crane is h. The lifting signal is the signal that has been measured by the monitoring system, so it is directly quoted here. The height of the crane beam from the ground is H, denoted as the beam height, then the wire rope length l = Hh.

[0066] The sensor's induced weight Gc is divided into two parts, one is the actual hoisting weight G, and the other is the weight G' of the wire rope that changes with the height. The greater the wire rope length l, the greater G', and vice versa, the smaller the wire rope length l, the smaller G'. That is, Gc = G + G', where Gc is the weight induced by the sensor, G is the actual hoisting weight, and G' is the weight of the wire rope.

[0067] For example, when a crane lifts a weight of Gx from the ground, the wire rope is the longest and the sensor sensed value is the largest. After it starts to rise, as the height increases, the length of the wire rope decreases and the sensed weight decreases, but the actual weight of the object does not decrease and remains unchanged.

[0068] If the influence of the wire rope is not taken into account when measuring the crane's hoisting weight, the error will be too large. Field tests have found that for a 90-meter-high crane, the influence of the wire rope can reach between 2 tons and 3 tons, so the influence of the wire rope cannot be ignored.

[0069] First, ensure that the height signal is calibrated and the height is accurate. The height here refers to the distance from the hook to the boom, that is, the length of the wire rope, represented by L, which is recorded as the length of the wire rope.

[0070] First, a two-point calibration is performed, which is divided into empty hook and hanging weight calibration.

[0071] When the hook is empty, the power collection value is p0, the height from the ground is h0, and the corresponding wire rope length is L0. At this time, the corresponding actual lifting weight value is 0 tons.

[0072] When lifting, the power acquisition value is p1, the height from the ground is h1, and the corresponding wire rope length is L1. At this time, the corresponding actual value of the lifting weight is Pr tons. This actual value of the lifting weight can also be said to be the net power output generated by the weight of the lifting object after the influence of the rope length is removed.

[0073] When any power and height are required, the system can automatically give the accurate lifting weight without being affected by the length of the wire rope.

[0074] Generally speaking, lifting or lowering movements will go through stages of acceleration, deceleration and uniform motion, and uniform motion needs to be automatically identified first.

[0075] When the motion is uniform, the weight of the suspended object is considered to be unchanged. The method of judging uniform motion is that the change in height per unit time Δh is basically equal, but not necessarily completely equal, and there can be a tolerance.

[0076] Based on this judgment, multiple endpoint coordinates of uniform motion are generated.

[0077] The power acquisition value is p0, the height above the ground is h0, and the corresponding wire rope length is L0;

[0078] The power collection value is p1, the height from the ground is h1, and the corresponding wire rope length is L1;

[0079] The power acquisition value is p2, the height above the ground is h2, and the corresponding wire rope length is L2;

[0080] …

[0081] The power collection value pn, the height above the ground is hn, and the corresponding wire rope length is Ln;

[0082] According to the historical data corresponding to the above cranes, the relationship between the output power of the crane and the length of the wire rope is fitted.

[0083] p=k*L+b

[0084] Among them, p is the power collection value; k is the slope in the relationship; b is the intercept in the relationship; L is the length of the wire rope.

[0085] According to the above-mentioned collection points, the slope k is calculated using the least square method. The physical meaning of this slope k is the power collection value corresponding to the unit length. So far, the slope k and the intercept b when the actual lifting weight remains unchanged (uniform motion) have been calculated.

[0086] Return to the two-point calibration again, which is divided into empty hook and loaded hook calibration.

[0087] When the hook is empty, the power collection value is p0, the height from the ground is h0, and the corresponding wire rope length is L0. At this time, the corresponding actual lifting weight value is 0 tons.

[0088] When lifting weight, the power collection value is p1, the height from the ground is h1, and the corresponding wire rope length is L1. At this time, the corresponding actual lifting weight value is Pr tons.

[0089] In the above two conditions, the wire rope lengths corresponding to the two points are different. According to the obtained k, we can convert these two points into two points under the same wire rope length L1. This makes it easier to calculate the total weight at the same height, which refers to the weight of the heavy object and the wire rope at the same height. That is, convert the power collection value p0 of the wire rope length L0 into the power collection value p0' of the wire rope length L1. In this way, p0' and p1 are both collection values ​​under the same wire rope length L1.

[0090] The conversion formula is:

[0091] p0'=k*(L1-L0)+p0

[0092] Among them, p0' is the power collection value when the converted wire rope length is L1 and the hook is empty; k is the slope; L1 and L0 are two different wire rope lengths; p0 is the power collection value when the original wire rope length is L0 and the hook is empty.

[0093] In this way, new weight calibration points (p0', 0) and (p1, Pr) are obtained, and these two points are at the same wire rope length L1.

[0094] It can calculate the actual lifting weight Px corresponding to any wire rope length Lx and any weight collection value. Because the collection value is the total collection value, the calculated Px includes the weight and wire rope;

[0095] Power collection value = collection value corresponding to actual lifting weight - collection value corresponding to wire rope weight. The calculation formula for the power collection value containing only heavy objects is:

[0096] py=Px–(k*(Lx-L0)+p0))

[0097] Among them, py is the power collection value containing only weights, Px is an arbitrary power collection value; L0 is the set wire rope length; Lx is any wire rope length except the wire rope length L0.

[0098] The calculation formula for the initial hoisting weight containing only heavy objects and excluding the influence of the length of the wire rope is:

[0099] Py=(py-p0') / (p1-p0')×(Pr)

[0100] Among them, Py is the initial hoisting weight, that is, only the weight of the heavy object, excluding the weight of the wire rope; p0' is the power collection value when the converted wire rope length is L1 and the hook is empty; p1 is the power collection value when the wire rope length is L1 and the weight is hoisted; Pr is the actual hoisting value when the wire rope length is L1; py is the weight collection value containing only the heavy object.

[0101] The initial hoisting weight is the mass of the object minus the length of the wire rope, or the weight collection value containing only the object. However, since the crane is moving up or down when it is working, it has acceleration, and the acceleration of the corresponding crane hook at work will also affect the hoisting weight. Therefore, the acceleration of the crane hook at work is further obtained to achieve the actual hoisting weight after the acceleration is subtracted.

[0102] Step S300, using a timer to interrupt the operation of the crane, analyzing the lifting heights during adjacent interruptions to obtain acceleration; based on a force calculation formula, combining the acceleration to obtain the actual hoisting weight after eliminating the influence of acceleration.

[0103] During the start-up phase of the winch motor, the acceleration a is relatively large, the motor does a lot of work, and the motor current is also relatively large. During the deceleration phase, the acceleration a is also relatively large, and the motor current decreases instead.

[0104] Generally speaking, cranes are divided into several fixed gears, from first gear to fourth gear, with first gear having the lowest speed and fourth gear having the highest speed. There is acceleration a when shifting gears, or there is acceleration when shifting from low gear to high gear or from high gear to low gear. The starting process is a special case of shifting gears, which is equivalent to the stable speed from zero speed to first gear, and the acceleration a is relatively large; when moving at a uniform speed, the acceleration a is 0.

[0105] According to the physical definition, acceleration That is, acceleration a is equal to the change in velocity per unit time. In the measurement of the monitoring system, there is a detection value of the lifting height h, but the detection value of the lifting height may have a certain error.

[0106] In order to accurately calculate the lifting or lowering speed, the timer interrupt method is used in the acquisition hardware. A 1ms pulse interrupt is taken, and the change in height h is processed in the interrupt function, Δh1=h2-h1, where h2 is the real-time hook height obtained by this 1ms interrupt, and h1 is the hook height obtained by the last 1ms interrupt. When a new interrupt arrives, both values ​​are updated and the latest value is taken. When the second 1ms interrupt edge arrives, let h2 be the hook height measured at the second interrupt, Δh1=h2-h1, then the lifting speed is v1=Δh1 / 1ms. When the third 1ms interrupt edge arrives, let h3 be the hook height measured at the third interrupt, then Δh2=h3-h2, and the hook speed v2=Δh2 / 1ms.

[0107] When the calculated hook speed v is greater than zero, the hook rises upward, that is, the hook height gradually increases; when the calculated hook speed v is less than zero, the hook drops downward, that is, the hook height gradually decreases. It should be noted that the hook height is referenced when the ground is zero.

[0108] In the above calculation, it takes a total of 1ms for the hook speed v1 to change to v2, so the value of acceleration a can be calculated, that is, Among them, Δv is the speed change value; Δt is the time change value; v2 is the hook speed at the current moment; v1 is the hook speed at the previous moment; Δh2 is the height difference collected between the next moment and the current moment; Δh1 is the height difference collected between the current moment and the previous moment; h3 is the height corresponding to the next moment; h2 is the height corresponding to the current moment; h1 is the height corresponding to the previous moment.

[0109] If h1+h3>2h2, then acceleration a>0, the direction of acceleration is upward, the lifted heavy object is accelerated upward or decelerated downward, and the direction of the resultant external force on the heavy object is upward.

[0110] If h1+h3<2h2, then acceleration a<0, the direction of acceleration is downward, the lifted heavy object is decelerating upward or accelerating downward, and the direction of the resultant external force on the heavy object is downward.

[0111] The magnitude and direction of acceleration a are calculated. Since it is a vector, it can be directly expressed by the formula F1=mg+ma, where a can be positive or negative.

[0112] After obtaining the initial lifting weight of the crane, the initial lifting weight Py is substituted into F1 in the formula in Table 1, and the acceleration obtained in step S300 is used as a in the formula, and g is the acceleration of gravity, which is set to 9.80 in the embodiment of the present invention. Therefore, the calculation formula of the actual lifting weight of the heavy object lifted by the crane hook is further obtained. For example, when the crane hook accelerates upward, the formula of its force is: F1 = mg + ma.

[0113] Therefore, when the crane hook accelerates upward, the corresponding calculation formula for the actual lifting weight is:

[0114] m=Py / (a+g)

[0115] Among them, m is the actual hoisting weight; Py is the initial hoisting weight; a is the acceleration; g is the gravitational acceleration.

[0116] So far, the actual lifting weight of the crane is obtained, which eliminates the influence of the wire rope length and acceleration.

[0117] Finally, we need to process the situation when the hoisted heavy object is suspended and there is no current. When the crane lifts the heavy object and it is suspended in the air, the hoisting motor is not running, and there is no running current and motor output power, but there is a heavy object at this time. It is necessary to add a hovering processing algorithm to the entire processing process.

[0118] (1) An intermediate variable is set in the weight measurement algorithm of the crane monitoring system to memorize the last collected winch motor current value.

[0119] (2) Make full use of the lifting signal and lowering signal of the original monitoring system. When the falling edge of the lifting or lowering signal arrives, that is, when the winch operation is to be stopped, the last collected current value memorized in the previous step is sealed and stored in another global variable.

[0120] (3) When the machine is stopped, that is, when there is neither an upward signal nor a downward signal, the weight is calculated based on the current value stored in the above steps.

[0121] According to the above basic situation, the overall algorithm is based on the output power of the motor, while taking into account the impact of running acceleration, wire rope length and suspended weight, and finally gives the weight of the hanging object.

[0122] In summary, the present invention first obtains the motor current, motor voltage and lifting height of the hoisting motor of the crane; the output power of the hoisting motor is obtained by combining the motor current and motor voltage; according to the historical data corresponding to the crane, the relationship between the output power of the crane and the length of the wire rope is fitted, and the real-time output power of the crane and two different wire rope lengths are input into the fitted relationship to obtain the initial lifting weight; the operation process of the crane is interrupted by a timer, and the lifting heights at adjacent interruptions are analyzed to obtain the acceleration; based on the force calculation formula, the actual lifting weight after eliminating the influence of the acceleration is obtained in combination with the acceleration.

[0123] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0124] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A weight measurement method for a crane monitoring system, characterized in that: The method comprises the following steps: Obtain the motor current, motor voltage and lifting height of the hoisting motor of the crane; The output power of the winch motor is obtained by combining the motor current and the motor voltage; the relationship between the output power of the crane and the length of the wire rope is fitted according to the historical data corresponding to the crane, and the real-time output power of the crane and two different wire rope lengths are input into the fitted relationship to obtain the initial hoisting weight; The operation process of the crane is interrupted by a timer, and the lifting heights during adjacent interruptions are analyzed to obtain the acceleration. Based on the force calculation formula, the actual lifting weight after eliminating the influence of acceleration is obtained in combination with the acceleration.

2. The weight measurement method for a crane monitoring system according to claim 1, characterized in that: The method of fitting the relationship between the output power of the crane and the length of the wire rope according to the historical data corresponding to the crane includes: The power collection value is p0, the height above the ground is h0, and the corresponding wire rope length is L0; The power collection value is p1, the height above the ground is h1, and the corresponding wire rope length is L1; The power collection value is p2, the height from the ground is h2, and the corresponding wire rope length is L2; ​​...; The power collection value pn, the height above the ground is hn, and the corresponding wire rope length is Ln; According to the historical data corresponding to the above cranes, the relationship between the output power of the crane and the length of the wire rope is fitted; p=k*L+b Among them, p is the power collection value; k is the slope in the relationship; b is the intercept in the relationship; L is the length of the wire rope.

3. The weight measurement method for a crane monitoring system according to claim 2, characterized in that: The real-time output power of the crane and two different wire rope lengths are input into the fitted relationship to obtain the initial hoisting weight, including: The conversion formula for the relationship is: p0'=k*(L1-L0)+p0 Among them, p0' is the power collection value when the converted wire rope length is L1 and the hook is empty; k is the slope; L1 and L0 are two different wire rope lengths; p0 is the power collection value when the original wire rope length is L0 and the hook is empty; The calculation formula for the power collection value containing only weights is: py=Px–(k*(Lx-L0)+p0) Among them, py is the power collection value containing only weights, Px is any power collection value; L0 is the set wire rope length; Lx is any wire rope length other than the wire rope length L0; The calculation formula for the initial hoisting weight containing only heavy objects and excluding the influence of the length of the wire rope is: Py=(py-p0') / (p1-p0')×(Pr) Among them, Py is the initial hoisting weight, that is, it only contains the weight but not the weight of the wire rope; p0' is the power collection value when the converted wire rope length is L1 and the hook is empty; p1 is the power collection value when the wire rope length is L1 and the weight is hoisted; Pr is the actual value of the hoisting weight when the wire rope length is L1.

4. The weight measurement method for a crane monitoring system according to claim 1, characterized in that: The method also includes a weight suspension processing algorithm: An intermediate variable is set in the weight measurement algorithm of the crane monitoring system to memorize the last collected current value of the hoisting motor; When the falling edge of the lifting or lowering signal arrives, that is, when the winch is to be stopped, the last collected current value memorized in the previous step is sealed and stored in another global variable; When the machine is stopped, that is, when there is neither an upward nor downward signal, the weight is calculated based on the current value stored in the above steps.

5. The weight measurement method for a crane monitoring system according to claim 1, characterized in that: The method of interrupting the operation of the crane by a timer and analyzing the lifting heights during adjacent interruptions to obtain the acceleration includes: In the acquisition hardware, the timer interrupt method is used to process, and a 1ms pulse interrupt is taken. The change in height h is processed in the interrupt function as Δh1=h2-h1, where h2 is the real-time hook height obtained by this 1ms interrupt, and h1 is the hook height obtained by the last 1ms interrupt; when the second 1ms interrupt edge arrives, let h2 be the hook height measured at the second interrupt, Δh1=h2-h1, then the hook speed is v1=Δh1 / 1ms; when the third 1ms interrupt edge arrives, let h3 be the hook height measured at the third interrupt, then Δh2=h3-h2, and the hook speed is v2=Δh2 / 1ms; The acceleration is calculated as: Among them, Δv is the speed change value; Δt is the time change value; v2 is the hook speed at the current moment; v1 is the hook speed at the previous moment; Δh2 is the height difference collected between the next moment and the current moment; Δh1 is the height difference collected between the current moment and the previous moment; h3 is the height corresponding to the next moment; h2 is the height corresponding to the current moment; h1 is the height corresponding to the previous moment.

6. The weight measurement method for a crane monitoring system according to claim 1, characterized in that: The force-based calculation formula, combined with acceleration, obtains the actual lifting weight after eliminating the influence of acceleration, including: When the crane hook moves upward with acceleration, the calculation formula for the actual lifting weight is: m=Py / (a+g) Among them, m is the actual hoisting weight; Py is the initial hoisting weight; a is the acceleration; g is the gravitational acceleration.

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