CN115159347A - Method and system for detecting height of suspended weight of crane hook - Google Patents

Abstract

The invention discloses a method and a system for detecting the height of a suspended weight of a crane hook, which can acquire the height of the weight by only utilizing an existing electric control system of the crane and matching a height calculation algorithm without adopting any additional sensor, wherein the height of the weight refers to the height after a hanging strip is connected with the weight, namely the height between the bottom of the hook and the bottom of the weight. A hoisting mechanism electric control system of the crane adopts a frequency converter for speed regulation, the frequency converter adopts a closed loop vector control mode, a hoisting motor is provided with an incremental encoder, and signals of the motor encoder are in signal connection with an encoder card of the frequency converter.

Description

Method and system for detecting height of suspended weight of crane hook

Technical Field

The invention relates to the technical field of crane detection, in particular to a method and a system for detecting the height of a suspended weight of a crane hook.

Background

At present, with the development of intellectualization and safety of a crane, how to actively avoid obstacles (avoid colliding with the obstacles) when a hook suspends a heavy object in the automatic operation process is a topic which can not be avoided by the intellectualization and safety of the crane. To actively avoid the obstacle, the height of the suspended weight needs to be obtained, so that the weight suspended by the lifting hook can be controlled to rise to a proper height to cross the obstacle raised on the ground, the efficiency can be considered, and the purpose of safe operation can be achieved. In general, the size and shape of the weight suspended by the crane in the actual working process are various, and the length of the sling or the steel wire rope used for connecting the lifting hook and the weight is also different. For example, the tower crane has various shapes of objects such as binding steel bars, trolley, steel coils and the like hung on a construction site, and the tower crane has eight doors with five flowers. If a sensor is used for detecting the height from the bottom of the lifting hook to the bottom of the heavy objects, the installation position of the sensor, the severe field environment, the power supply mode, the detection precision and the cost are all the problems to be considered, and the detection scheme is quite complex to realize and has low reliability.

Therefore, how to improve the convenience and reliability of detecting the height of the suspended weight of the crane hook is a problem to be solved urgently by those skilled in the art.

Disclosure of Invention

In view of this, the invention provides a method and a system for detecting the height of a suspended weight of a crane hook, which can obtain the height of the weight by only utilizing an existing electronic control system of the crane and a height calculation algorithm without adopting any additional sensor, wherein the height of the weight refers to the height after a hanging strip is connected with the weight, namely the height between the bottom of the hook and the bottom of the weight. A hoisting mechanism electric control system of the crane adopts a frequency converter for speed regulation, the frequency converter adopts a closed loop vector control mode, a hoisting motor is provided with an incremental encoder, and signals of the motor encoder are in signal connection with an encoder card of the frequency converter.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for detecting the height of a suspended weight of a crane hook comprises the following steps:

step 1: the method comprises the following steps that a crane hook is suspended in an air manner, and when a frequency converter of an electric control system of a crane hoisting mechanism controls the hook to ascend to a position limited by an ascending endpoint of the hoisting mechanism and stop, the frequency converter resets the numerical value of an encoder;

the lifting hook is not hung with any hanging strip and heavy objects, the frequency converter controls the lifting hook to ascend to the ascending end point limit position of the lifting mechanism to stop, and the frequency converter clears the encoder value of the encoder to 0;

step 2: acquiring an encoder value Encode1 when the lifting hook is controlled by the frequency converter to descend to the ground until the bottom of the lifting hook just contacts with the ground;

the bottom of the lifting hook just contacts with the ground to stop, and the encoder code value Encode1 displayed on the panel of the frequency converter at the moment is recorded;

and 3, step 3: collecting a coder value Encode2 when the lifting hook is controlled by the frequency converter to rise to a position away from the ground by a set unit distance;

and the frequency converter controls the lifting hook to accurately rise to a position 1 m away from the ground. Recording the encoder code value Encode2 displayed by the frequency converter panel at the moment,

and 4, step 4: calculating a code value of the lifting hook lifting unit distance according to the encoder value Encode1 and the encoder value Encode2;

at this time, a code value of each lifting hook lifting by 1 meter can be obtained and expressed by a variable PPM, and the calculation formula of the PPM is as follows:

PPM＝|Encode2-Encode1|

the PPM value is a positive value, an absolute value is taken from a calculation formula, and the PPM value is filled into the corresponding parameter of the frequency converter;

and 5: acquiring a load torque value LoadTorque1 when a lifting hook is controlled by a frequency converter to be suspended at a preset rotating speed;

controlling the lifting hook to ascend at a stable speed of 10HZ by the frequency converter, recording a load torque value LoadTorque1 displayed on a panel of the frequency converter during the stable speed, and filling the value into parameters of the frequency converter;

step 6: when the lifting hook suspends a heavy object, the frequency converter controls the lifting hook to rise at a preset rotating speed, and a load torque value LoadTorque2 and an encoder code value Encode3 when the heavy object is judged to be completely separated from the ground according to the load torque value LoadTorque1 are collected;

controlling the lifting hook to move to a position near the position right above the weight, fixing the weight by using one end of a sling or a steel wire rope, and then hanging the other end of the sling or the steel wire rope on the lifting hook; after the hook is hung, the frequency converter controls the lifting hook to rise at the speed of 10HZ, and in the lifting process of the lifting hook, the frequency converter can detect the change of load torque in real time until a heavy object is completely taken away from the ground by the lifting hook, the load torque is not increased any more, and the load torque value is changed into LoadTorque2;

the load torque value LoadTorque2 is not changed after lasting for 0.5 second, the fact that the heavy object completely leaves the ground can be judged, and the frequency converter records the code value Encode3 of the encoder at the moment;

and 7: calculating to obtain the height of a hanging weight suspended by the hook, namely the height from the bottom of the hook to the bottom of the weight according to the code value of the lifting unit distance of the hook, the encoder code value Encode1 and the encoder code value Encode3;

and calculating the height H from the bottom of the lifting hook to the bottom of the weight according to the PPM obtained in the S4 and the Encode1 obtained in the S2, wherein the calculation formula is as follows:

H＝|Encode3-Encode1|/PPM。

preferably, in the step 1, the converter controls a lifting motor to rotate forwards, the lifting motor drives a lifting hook to ascend to a lifting end point for limiting through a winding drum and a steel wire rope, the pulley drives the lifting hook to ascend to a lifting end point, the converter controls the motor to stop after receiving a lifting end point limiting signal, the converter clears the encoder value fed back by the encoder to 0 at the moment, and the position with the code value of 0 serves as a position reference point of the lifting hook;

the frequency converter clears 0 the code value fed back by the encoder means that the frequency converter can receive a switch signal of the ascending end point limit when the lifting hook is positioned at the ascending end point limit, the limit switch signal is in signal connection with a digital input terminal of the frequency converter, and the frequency converter clears 0 the code value of the encoder after receiving the signal.

Preferably, in step 2, the frequency converter controls the lifting hook to descend to the ground until the bottom of the lifting hook just contacts with the ground and stops, that is, a driver operates the lifting handle to give a reverse rotation instruction to the frequency converter, and then the frequency converter controls the lifting hook to descend, when the lifting hook descends to be close to the ground, the driver can give a forward rotation or reverse rotation instruction to the frequency converter through the lifting handle to adjust the bottom of the lifting hook to just contact with the ground, and at the moment, the ground cannot support the lifting hook.

Preferably, in step 3, the unit distance is 1 meter, and the method for controlling the lifting hook to accurately rise to the position 1 meter away from the ground by the frequency converter means that the frequency converter controls the lifting hook to rise until the height between the bottom of the lifting hook and the ground is just 1 meter.

Preferably, in step 5, the inverter controls the motor in a closed-loop vector control mode, and the load torque is an important calculated variable for the inverter to control the operation of the motor. The load torque is a characteristic value representing the load weight carried by the motor, the larger the weight of the heavy object carried by the motor is, the larger the load torque is, the smaller the weight of the heavy object is, and the smaller the load torque is; the load torque value LoadTorque1 represents the load weight of the motor with an empty hook, and is a calibrated value of the load weight of the empty hook.

Preferably, in step 6, the specific manner of fixing the weight by using one end of the sling or the steel wire rope and then hanging the other end of the sling or the steel wire rope on the hook is as follows:

when hanging the both ends of suspender or wire rope respectively on heavy object and lifting hook, for the convenience couple, certain length's surplus is all left to suspender or wire rope, and after hanging at both ends, the suspender or the wire rope that leaves certain length surplus all hangs down.

Preferably, in step 6, during the lifting process of the hook, since the sling or the steel wire rope is in the initial state of hanging down, the sling or the steel wire rope is firstly gradually straightened by the hook, and the load torque of the frequency converter at this time is LoadTorque1 in S5. Until the hanging strip or the steel wire rope is straightened and tensioned, the heavy object is not taken away from the ground by the hook, and the load torque of the frequency converter is rapidly increased in the process that the heavy object is taken away from the ground. Until the weight is completely taken off the ground by the hook, the load torque will not become large any more, and the load torque value becomes LoadTorque2.

Preferably, in step 6, the load torque will not increase any more, and a stable value is maintained, that is, after the weight leaves the ground, the ground no longer has a supporting force for the weight, and at this time, the load torque will not change any more, the stable value is greater than the load torque value LoadTorque1, and after lasting for 0.5 second, the frequency converter records the encoder code value at this time, that is, the value of Encode3.

A detection system for the height of a suspended weight of a crane hook comprises a hoisting mechanism electric control system and a detection mechanism;

the hoisting mechanism electric control system comprises a lifting motor and a frequency converter; the frequency converter controls the lifting motor to work to drive the lifting hook to ascend or descend; an encoder of the frequency converter records an encoder value and a load torque value and transmits the encoder value and the load torque value to the detection mechanism;

the detection mechanism calculates the height of the hanging weight of the lifting hook according to the numerical value of the encoder and the load torque value.

According to the technical scheme, compared with the prior art, the height of the weight can be obtained by utilizing an existing electric control system of the crane and matching with a height calculation algorithm, the code value of the lifting hook at a unit distance is calculated by respectively acquiring the code value of an encoder when the lifting hook is in an empty suspension state and just contacts the ground and rises to the unit height through a frequency converter of the electric control system of the crane hoisting mechanism, and then the height of the hanging weight of the lifting hook is obtained by calculating according to the code value of the lifting hook at the unit distance and the code value of the encoder when the lifting hook is in the empty suspension state, the load torque value rising at a stable speed and the load torque value and the encoder code value when the weight is hung to just fall off the ground. The load torque value is used for judging whether the lifting hook or the heavy object is completely lifted, the hanging strip or the steel wire rope hangs down after the heavy object is hung on the lifting hook and cannot be in a tensioning state, only the heavy object is taken away from the ground by the lifting hook through the hanging strip or the steel wire rope, and the real height between the bottom of the lifting hook and the bottom of the heavy object can be obtained after the hanging strip or the steel wire rope is in the complete tensioning state.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of hook data calibration provided by the present invention;

FIG. 2 is a schematic diagram of the process of lifting the weight according to the present invention;

fig. 3 is a schematic diagram illustrating the variation of load torque during the process of hoisting a heavy object according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides a method for detecting the height of a suspended weight of a crane hook, which comprises the following steps:

fig. 1 mainly shows that data calibration is performed on a lifting hook 1 in a debugging stage, and the lifting hook data calibration includes 4 steps, namely S1, S2, S3, and S4. These 4 steps are performed sequentially in order.

S1 is used for finding a fixed height on the crane as a position reference point of the lifting hook 1. Since the crane is provided with a lifting end limit switch in order to prevent the occurrence of a roof-rushing dangerous accident, the lifting hook 1 can be automatically stopped when receiving an action signal of the limit switch in the lifting operation process, and therefore, the lifting end limit position is most suitable to be used as a reference point. The ascending L1 of converter control lifting hook is to the spacing department of ascending terminal point, and the spacing signal of ascending terminal point can be received to the converter, and clear 0 with the sign indicating number value of encoder feedback this moment, the sign indicating number value is 0 as the position reference point of lifting hook 1.

And S2 is used for obtaining an encoder code value Encode1 when the bottom of the hook 1 touches the ground. And the frequency converter controls the lifting hook to descend to the ground until the bottom of the lifting hook just contacts with the ground to stop. And recording the encoder code value Encode1 displayed on the panel of the frequency converter at the moment. Encode1 is important data for calibrating and calculating the height of the heavy object in the subsequent steps.

S3 is to obtain a code value of L2=1 meter per rise of the hook. The converter control lifting hook rises, stops when the height of lifting hook bottom and ground just is 1 meter, can measure with the scale here. Recording the code value Encode2 of the encoder displayed by the panel of the frequency converter at the moment, calculating the code value of 1 m rising of the lifting hook 1 through the Encode2 and the Encode1 recorded in the step S2, wherein the code value is expressed by a variable PPM, and the calculation formula of the PPM is as follows:

PPM＝|Encode2-Encode1|

the PPM value is a positive value, the absolute value is taken from the calculation formula, and the PPM value is filled into the corresponding parameter of the frequency converter. PPM is important data for calculating the height of the heavy object in the subsequent steps.

S4 is a load torque value LoadTorque1 when the empty hook is raised at 10 Hz. The frequency converter controls the lifting hook to ascend at a stable speed of 10HZ, records a load torque value LoadTorque1 displayed on a frequency converter panel during the stable speed, and fills the value into parameters of the frequency converter. LoadTorque1 is a judgment value used for judging whether the sling or the steel wire rope 2 is straightened, and the frequency converter detects that the LoadTorque2 is greater than the LoadTorque1 in the process of lifting the heavy object from the ground, and then the steel wire rope is considered to be tensioned, namely straightened.

After the data calibration is completed, the height of a heavy object suspended by the lifting hook can be detected in real time in the actual hoisting operation process of the crane.

Fig. 2 is a schematic diagram of a process of hoisting a heavy object from the ground during an actual hoisting operation of the crane, and fig. 3 is a schematic diagram of a load torque change during the process of hoisting the heavy object. The time when the weight is lifted off the ground can be obtained by combining the figure 2 and the figure 3, and then the height between the bottom of the lifting hook and the bottom of the weight is calculated, and the method comprises the steps of S5, S6 and S7.

S5: the lifting hook 1 is controlled to move to the position near the position right above the heavy object, the heavy object is fixed by one end of a hanging strip or a steel wire rope 2, and then the other end of the hanging strip or the steel wire rope 2 is hung on the lifting hook 1. In order to facilitate the hook, the hanging strip or the steel wire rope 2 is provided with a certain length of allowance, after the two ends of the hanging strip or the steel wire rope 2 are hung, the hanging strip or the steel wire rope 2 provided with the certain length of allowance is hung, and the height of the lifting hook is H1.

S6: after hanging, the frequency converter controls the hook 1 to rise at a steady speed of 10HZ, the values of the hook speed and the load torque change with time as shown in fig. 3, a broken line a in fig. 3 represents the hook speed, a curve b represents the load torque, and the hook 1 accelerates from 0HZ to 10HZ corresponding to the time period of 0-t1 in fig. 3, which is sufficiently short, generally about 0.4 seconds. During the lifting process of the hook 1, because the sling or the wire rope 2 is in the initial state of hanging down, the sling or the wire rope 2 is firstly gradually straightened by the hook 1, the height is H2, the process corresponds to the time period from 0 to t2 in the figure 3, and the load torque value of the frequency converter during the time period is LoadTorque1. Until the hanging strip or the steel wire rope 2 is straightened and tensioned, the weight is not taken away from the ground by the lifting hook 1, in the process that the weight is taken away from the ground, the load torque of the frequency converter is rapidly increased from the loadTorque1 until the weight is completely taken away from the ground by the lifting hook 1, the load torque is not increased any more, and the load torque value is changed into the loadTorque2. This process corresponds to the time t2-t3 of fig. 3.

S7: if the load torque value LoadTorque2 does not change for 0.5 second in S6, it can be determined that the weight completely leaves the ground, which corresponds to the period from t3 to t4 in fig. 3. The frequency converter records the code value Encode3 of the encoder at the moment. And calculating the height H3 from the bottom of the lifting hook to the bottom of the weight according to the PPM obtained in the S2 and the Encode2 obtained in the S4. The calculation formula is as follows:

H3＝|Encode3-Encode1|/PPM

in the actual operation process of the crane, when different weights are hoisted, the LoadTorque2 is different according to the weight of the weights, but the load torque is a stable value once the same weight is hoisted.

In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A method for detecting the height of a suspended weight of a crane hook is characterized by comprising the following steps:

step 1: the method comprises the following steps that a crane hook is suspended in an air manner, and when a frequency converter of an electric control system of a crane hoisting mechanism controls the hook to ascend to a position limited by an ascending endpoint of the hoisting mechanism and stop, the frequency converter clears the numerical value of an encoder;

step 2: collecting a coder value Encode1 when the frequency converter controls the lifting hook to descend to the ground until the bottom of the lifting hook just contacts with the ground;

and step 3: collecting a coder value Encode2 when the lifting hook is controlled by the frequency converter to rise to a position away from the ground by a set unit distance;

and 4, step 4: calculating a code value of the lifting hook lifting unit distance according to the encoder value Encode1 and the encoder value Encode2;

and 5: acquiring a load torque value LoadTorque1 when a lifting hook is controlled by a frequency converter to be suspended at a preset rotating speed;

and 6: when the lifting hook suspends a heavy object, the frequency converter controls the lifting hook to rise at a preset rotating speed, and a load torque value LoadTorque2 and an encoder code value Encode3 when the heavy object is judged to be completely separated from the ground according to the load torque value LoadTorque1 are collected;

and 7: and calculating to obtain the height of the suspended weight of the lifting hook according to the code value of the lifting hook in unit distance, the encoder code value Encode1 and the encoder code value Encode3.

2. The method for detecting the height of the suspended weight of the crane hook according to claim 1, wherein in the step 1, the converter controls the lifting motor to rotate forwards, and controls the lifting motor to stop after receiving a lifting end limit signal, the converter clears the encoder value fed back by the encoder to 0, and the current position is used as the position reference point of the lifting hook; the ascending key limit is connected with the digital input end of the frequency converter, and the limit switch signal is sent to the frequency converter.

3. The method for detecting the height of the suspended weight of the crane hook according to claim 1, wherein in the step 2, the lifting handle is operated to give a reverse rotation instruction to the frequency converter, the frequency converter controls the lifting hook to descend, and the lifting handle gives a forward rotation or reverse rotation instruction to the frequency converter to adjust until the bottom of the lifting hook just contacts with the ground, and at the moment, the ground has no supporting force on the lifting hook.

4. The method for detecting the height of a crane hook suspended weight according to claim 1, wherein the code value of the unit distance of the hook rising in step 4 is calculated by the formula:

PPM＝|Encode2-Encode1|。

5. the method for detecting the height of the suspended weight of the crane hook according to claim 1, wherein in the step 5, the motor is controlled by the frequency converter in a closed-loop vector control mode, and a load torque value loadTorque1 is acquired, wherein the load torque value loadTorque1 represents the load weight when the motor drives the suspended hook.

6. The method for detecting the height of the suspended weight of the crane hook according to claim 1, wherein in step 6, the two ends of the sling or the steel wire rope are respectively hung on the weight and the hook, and the sling or the steel wire rope is in a hanging state, the frequency converter controls the hook to rise at a preset rotating speed, the sling or the steel wire rope is gradually straightened by the hook, the load torque value of the frequency converter is gradually increased until the sling or the steel wire rope is straightened and tensioned, the weight is taken away from the ground by the hook, and the load torque value is not increased any more.

7. A method for detecting the height of a crane hook suspended weight according to claim 1, wherein in step 6, if the load torque value is greater than the load torque value LoadTorque1 and is stable for 0.5 seconds, then the encoder code value Encode3 is recorded.

8. A method as claimed in claim 1, wherein the calculation formula for the height of the hook suspended weight in step 7 is:

H＝|Encode3-Encode1|/PPM

PPM is the code value of the lifting hook in unit distance.

9. A system for detecting the height of a suspended load from a crane hook according to any one of claims 1 to 8, comprising a hoist electrical control system and a detection mechanism;

the hoisting mechanism electric control system comprises a hoisting motor and a frequency converter; the frequency converter controls the lifting motor to work to drive the lifting hook to ascend or descend; an encoder of the frequency converter records an encoder value and a load torque value and transmits the encoder value and the load torque value to the detection mechanism;

the detection mechanism calculates the height of the hanging weight of the lifting hook according to the numerical value of the encoder and the load torque value.

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