CN114353924B - On-line weighing method for materials in hydraulic excavator bucket - Google Patents

Abstract

The invention discloses an on-line weighing method for materials in a bucket of a hydraulic excavator, which comprises the following steps: acquiring pressure value P of hydraulic cylinder of bucket rod in real time ₁ And pressure value P of hydraulic cylinder of bucket ₂ (ii) a The center of a hinged point of a base and a movable arm of the excavator is taken as an original point, the horizontal advancing direction is an X axis, the direction perpendicular to the X axis is a y axis, the inclination angle theta of the bucket rod relative to the horizontal plane is obtained in real time, wherein the theta is positive above the X axis and negative below the X axis; real-time acquisition of length l of bucket rod hydraulic cylinder _AB Length l of hydraulic bucket cylinder _DE (ii) a And then the data processor of the material weighing module brings the acquired data into a formula, so that the weight of the material in the bucket can be obtained. The weighing method considers the gravity centers of all parts and materials of the excavator and the influence on the online measurement of the weight of the materials in the bucket when the working surface is not horizontal, so that the measurement result of the weight of the materials is more accurate, the online measurement of the weight of the materials excavated by the bucket of the excavator in the construction process and the statistical measurement of the total amount of the materials excavated by the excavator in the engineering construction are realized, and the foundation is laid for the realization of digital and intelligent construction.

Description

An online weighing method for materials in buckets of hydraulic excavators

technical field

The invention relates to an online weighing method for materials in a bucket of a hydraulic excavator, in particular to a weighing device and method for accurately measuring the weight of materials in the bucket of a hydraulic excavator online in real time.

Background technique

Hydraulic excavators are widely used in construction, resource mining and other fields. During the use of the hydraulic excavator, when the construction party has weight requirements for the materials excavated by the hydraulic excavator, the traditional hydraulic excavator does not have the function of online real-time and accurate weighing of the excavated materials in the bucket. The traditional method of this problem is to load the materials excavated by the hydraulic excavator each time, and weigh them through devices such as weighbridges. This method not only wastes human resources, but also often causes underload or overload due to the inability to measure the weight of materials in the bucket in real time, which leads to rework and wastes a lot of time.

At present, there are some weighing devices and methods for materials in the bucket applied to hydraulic excavators on the market. The Chinese invention patent published on June 22, 2021 has a publication number of CN 113008345A, a weighing system and method for excavators. It collects data through the boom position sensor, arm position sensor, bucket position sensor and oil pressure sensor, and calculates the digging weight through the controller using the functional relationship between the oil pressure of the main fuel tank and the digging weight of the excavator. Although this method is simple Practical, but the excavator needs to be run to a fixed posture when weighing, so that real-time online measurement of material weight cannot be realized. A Chinese invention patent published on November 05, 2014 with the publication number CN 104132721A is a mining excavator material automatic weighing method, which uses an angle sensor to collect the rotation angle between each component to calculate the real-time position between each component , and then calculate the kinematic parameters of each component such as speed and acceleration through differential calculation. Although this method has good dynamic stability, it will introduce a large amount of error when using the rotation angle for primary and secondary integration, and it does not consider the material center of gravity. Impact. A Chinese invention patent published on June 22, 2021 with the publication number CN 113010979A is an excavator weighing method and its system, which uses angle sensors and cylinder pressure sensors to detect the inclination angle of the stick, the inclination angle of the connecting rod and the bucket cylinder. The thrust of the material can be calculated simply and accurately by using the triangular geometric parameters, but it only considers the working condition of the excavator on the horizontal working surface, and does not consider the working condition of the excavator on the working surface with a certain slope. Therefore, the scope of application is greatly limited.

Contents of the invention

Aiming at the deficiencies in the prior art, the object of the present invention is to provide an online weighing method for materials in the hydraulic excavator bucket, which can accurately measure the weight of the materials in the hydraulic excavator bucket online in real time.

In order to achieve the above object, the present invention is achieved through the following technical solutions:

Embodiments of the present invention provide an online weighing method for materials in a bucket of a hydraulic excavator, as follows:

Obtain the pressure value P 1 of the stick hydraulic cylinder and the pressure value P ₂ of the bucket hydraulic cylinder in real time _;

Take the center of the hinge point of the base of the excavator and the boom as the origin, the horizontal forward direction is the x-axis, and the direction perpendicular to the x-axis is the y-axis, and the inclination angle θ of the stick relative to the horizontal plane is obtained in real time, and θ is positive above the X-axis. Below is negative;

Obtain the length l _AB of the stick hydraulic cylinder and the length l _DE of the bucket hydraulic cylinder in real time;

Then the material weighing module brings the data obtained by the sensor into the following formula to obtain the weight of the material in the bucket;

Among them, the parameters l _AC , l _BC , l _DF , l _EF , l _CG , and l _GF can all be obtained from the dimensions provided by the manufacturer,

l _EG is obtained according to the cosine law; C ₁ and C ₂ are obtained through dynamic calibration of the excavator under no-load conditions.

As a further technical solution, the pressure value P1 is measured by _a pressure sensor arranged on the stick.

As a further technical solution, the pressure value P2 is measured by a pressure sensor arranged _on the bucket.

As a further technical solution, the inclination angle θ is measured by an angle sensor arranged on the stick.

As a further technical solution, the length l _AB of the stick hydraulic cylinder is measured by a laser displacement sensor arranged on the stick hydraulic cylinder.

As a further technical solution, the length l _DE of the bucket hydraulic cylinder is measured by a laser displacement sensor arranged on the bucket hydraulic cylinder.

As a further technical solution, it also includes a coordinate conversion unit installed on the body of the excavator.

As a further technical solution, when the working face of the excavator is inclined, the coordinate conversion unit can be used to measure the inclination γ of the working face of the excavator relative to the horizontal plane, and establish the coordinate system X'OY when the excavator is on the inclined working face ', the angle between the coordinate system X'OY' and the coordinate system XOY is γ, then the coordinate transformation formula of the corresponding points on the two coordinate systems is:

Where (x, y) is the coordinate of a point m on the excavator in the coordinate system XOY, and (x', y') is the coordinate of the point in the coordinate system X'OY'; according to the coordinate conversion formula, the excavator is in When the working face is tilted, each point on the body is mapped to the horizontal coordinate system, so that the online measurement of the material weight is performed according to the excavator material measurement method on the horizontal coordinate system.

As a further technical solution, the dynamic calibration process is as follows:

First, lift the boom of the hydraulic excavator to a certain height to ensure that the bucket and stick will not touch the ground during the dynamic calibration process, and then extend and shrink the stick to the limit position successively by controlling the hydraulic cylinder of the stick. Record the arm inclination angles θ ₁ and θ ₂ at the extreme positions respectively;

Ten angle values Angle ₁ ... Angle ₁₀ are taken on average in the range of θ ₁ and θ ₂ , and the stick is stretched to Angle ₁ ... Angle ₁₀ in turn, and the boom is raised and lowered at a constant speed at each angle value to record data, and then passed The recursive least squares method dynamically calibrates two unknown parameters C ₁ and C ₂ related to the position of the center of gravity of the boom in different states.

As a further technical solution, it also includes a historical record function based on the data storage module.

The beneficial effects of the present invention are as follows:

Compared with the traditional hydraulic excavator, the online weighing method of the material in the hydraulic excavator bucket provided by the present invention can realize the real-time and accurate measurement function of the material in the hydraulic excavator bucket.

Compared with the hydraulic excavators currently on the market with the function of weighing materials in the bucket, the online weighing method of the materials in the bucket of the hydraulic excavator provided by the present invention only needs to carry out dynamic weighing before the excavator excavates. Calibration can complete the real-time weight measurement of the materials in the bucket during excavation, without the need to run the excavator arm, bucket, and stick to a fixed posture during excavation to perform measurement, which saves a lot of time and greatly improves the work efficiency. efficiency. Simultaneously, the on-line weighing method of the material in the bucket of a hydraulic excavator provided by the present invention takes into account the influence of the center of gravity of each part of the excavator and the material and the non-horizontal working surface on the online measurement of the material weight in the bucket (see weighing Formula), which makes the result of material weight measurement more accurate, makes the construction process more precise and intelligent, and reduces unnecessary rework caused by excessive or too little weight of materials excavated by the excavator. At the same time, the excavation volume of the excavator can be displayed on the operator's mobile phone, computer or IPAD through the data transmission module, which can realize the visualization of the excavator's working process and construction information, thereby realizing precise and intelligent construction.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

Figure 1: Excavator work flow chart;

Figure 2: Diagram of each functional module of the excavator;

Figure 3: Scheme diagram of online weighing of materials;

Figure 4: Force analysis diagram of bucket and stick;

Figure 5: A schematic diagram of the working device of the excavator;

Figure 6: Schematic diagram of coordinate transformation of the working surface;

In the figure: 1. Wheel; 2. Slewing mechanism; 3. Control bin; 4. Boom; 5. Stick hydraulic cylinder; 6. Stick; 7: Bucket hydraulic cylinder; 8. Bucket; 9. Boom hydraulic cylinder.

detailed description

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. 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.

It should be noted that the terminology used here is only for describing specific embodiments, and is not intended to limit exemplary embodiments according to the present invention. As used herein, unless the invention clearly states otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, their Indicate the presence of features, steps, operations, means, components and/or combinations thereof;

As introduced in the background technology, there are deficiencies in the prior art. In order to solve the above technical problems, the present invention proposes an online weighing method for materials in the bucket of a hydraulic excavator.

In a typical implementation of the present invention, as shown in Figure 3, the structure of the excavator corresponding to the weighing method is pasted on the existing excavator with a bucket pressure measurement unit, a bucket hydraulic cylinder length measurement unit, a bucket Rod pressure measurement unit, stick inclination measurement unit, stick hydraulic cylinder length measurement unit and coordinate conversion unit; through these measurement units, the weight of materials in the bucket of the excavator can be detected online in real time, and the material in the bucket of the hydraulic excavator can be realized. online weighing;

Further, the arm pressure measuring unit and the bucket pressure measuring unit in this embodiment are respectively the first pressure sensor and the second pressure sensor; the arm inclination angle measuring unit and the coordinate conversion unit are respectively the first angle sensor , the second angle sensor; the stick hydraulic cylinder length measurement unit and the bucket hydraulic cylinder length measurement unit are respectively a first laser displacement sensor and a second laser displacement sensor.

After these sensors collect the data and transmit it to the material weighing module, the least square method is used for data processing to make the measurement accuracy more accurate. At the same time, the processor also has the function of historical record. Through the data storage module, the quality of the material in the bucket of the excavator and the total quality of the material excavated during the entire excavation process can be recorded through the data storage module, and the data is sent to the terminal through the data communication module. The terminal can be the operator's mobile phone, computer or IPAD.

The corresponding measurement methods are described in detail as follows:

As shown in Figure 3, take the center of the hinge point of the base of the excavator and the boom as the origin, the horizontal forward direction is the x-axis, and the direction perpendicular to the x-axis is the y-axis. The arm pressure measuring unit and bucket pressure measuring unit on the arm measure the pressure values P ₁ and P ₂ of the arm and bucket hydraulic cylinders, and the arm inclination angle measuring unit installed on the arm measures the The inclination angle θ relative to the horizontal plane (note that θ is positive above the X-axis and negative below it), through the length measuring unit of the stick hydraulic cylinder and the length measuring unit of the bucket hydraulic cylinder installed on the stick hydraulic cylinder and bucket hydraulic cylinder , measure the length l _AB and l _DE of the stick hydraulic cylinder and the bucket hydraulic cylinder in real time. When the working surface of the hydraulic excavator is a non-horizontal plane, the coordinate conversion is performed through the coordinate conversion unit installed on the machine body.

Further, static analysis is first performed on the excavator, and the pressure P ₁ , P ₂ , the inclination angle θ of the stick can be measured by the first angle sensor installed on the stick, and the stick can be monitored in real time by the first laser displacement sensor and the second laser displacement sensor installed on the stick and bucket hydraulic cylinder and the length of the bucket hydraulic cylinder l _AB , l _DE , and at the same time use the length dimension parameters of each component of the excavator to solve the unknown length parameters based on the triangular principle, and take the moment of the connection point C between the boom and the stick, and the moment balance The principle is available:

为斗杆自身重力对连接点C的力矩，

为铲斗自身重力对连接点C的力矩，

为物料重力对连接点C的力矩，

为斗杆液压缸压力对连接点C的压力。In the formula:

is the moment of the stick's own gravity on the connection point C,

is the moment of the bucket's own gravity on the connection point C,

is the moment of material gravity on connection point C,

is the pressure of the stick hydraulic cylinder pressure to the connection point C.

l The lengths of _AC and l _BC can be provided by the manufacturer, l the length of _AB can be obtained from the stick hydraulic cylinder length measuring unit, and ∠ABC can be obtained by the law of cosines

so:

α ₁ is the angle between the center of mass of the stick and the edge of the stick, where the center of mass of the stick can be obtained by weighing method or hanging method, and then the angle α ₁ between the center of mass of the stick and the edge of the stick can be obtained, θ is the The inclination angle of the bar can be calculated as follows:

So the moment of stick gravity on point C is:

Similarly, l _EF and l _DF can be obtained from the size parameters provided by the manufacturer, and l _DE can be obtained through the length measurement unit of the bucket hydraulic cylinder, so ∠DEF can be obtained by the law of cosines:

From the law of cosines:

Among them, l _EF and l _FG can be obtained from the dimensions provided by the manufacturer, and l _EG can be obtained from the cosine law in △FEG.

∠GEP ₂ ＝π-∠DEF-∠FEG (8)

so:

The moment sum of bucket gravity m ₂ g and load gravity m ₃ g on point C is:

The moment sum of bucket gravity m ₂ g, load gravity m ₃ g, and bucket hydraulic cylinder pressure P ₂ to point G is 0:

Put (11) and (13) into (12) to get:

Put (3)(5)(10) formula into (1) to get:

Simplify (11) to:

make:

When m ₃ g = 0, that is, when there is no load, dynamic calibration can be obtained:

Bring equations (2), (6), (7), (15), and (16) back to equation (12) to simplify:

In formula 17, P ₁ , P ₂ , θ, _lAB , and _lDE can be respectively composed of stick pressure measuring unit, bucket pressure measuring unit, stick tilt angle measuring unit, stick hydraulic cylinder length measuring unit, bucket The hydraulic cylinder length measuring unit is measured in real time, and they are all functions of time t. Parameters l _AC , l _BC , l _DF , l _EF , l _CG , and l _FG can all be obtained from the dimensions provided by the manufacturer, and l _EG can be obtained from the cosine law in △FEG. So m ₃ g is a function about P ₁ (t), P ₂ (t), θ(t), l _AB (t), l _DE (t), so formula (19) can be simplified as:

F(P ₁ (t), P ₂ (t), θ(t), l _AB (t), l _DE (t)) = m ₃ g (20)

Put the real-time pressure of the stick cylinder, real-time pressure of the bucket cylinder, real-time angle of the stick, real-time length of the stick cylinder, and real-time length of the bucket cylinder measured by each sensor into the above formula (20) to calculate the load weight m ₃ g.

Further, the excavator needs to be dynamically calibrated under no-load conditions before weighing, so as to determine the weighing parameters C ₁ and C ₂ of the hydraulic excavator. The dynamic calibration process first raises the boom of the hydraulic excavator to a certain height to ensure that the bucket and the stick will not touch the ground during the dynamic calibration process, and then the stick is extended and closed successively by controlling the hydraulic cylinder of the stick. Shrink to the limit position, respectively record the inclination angles θ ₁ and θ ₂ of the stick at the limit position. Take ten angle values Angle ₁ ... Angle ₁₀ on average within the range of θ ₁ and θ ₂ (the angle values Angle ₂ -Angle ₉ are omitted here), and stretch the stick to Angle ₁ ... Angle ₁₀ in turn (the angles are omitted here value Angle ₂ -Angle ₉ ), and record the data at each angle value of lifting the boom at a constant speed, and then use the recursive least squares method to dynamically calibrate two unknown parameters C ₁ and _C2 .

Further, when the working surface where the excavator is located is an inclined surface, the angle sensor 2 installed on the body of the excavator can be used to measure the inclination γ of the working surface of the excavator relative to the horizontal plane, as shown in Figure 6, to establish when the excavator The coordinate system X'OY' when the machine is located on the inclined working surface, the angle between the coordinate system X'OY' and the coordinate system XOY is γ, then the conversion relationship of the corresponding points on the two coordinate systems is:

Where (x, y) is the coordinate of a certain point m on the excavator in the coordinate system XOY, and (x', y') is the coordinate of the point in the coordinate system X'OY'. According to the above coordinate conversion formula (21), each point on the excavator body when it is on the inclined working surface can be mapped to the horizontal plane coordinate system, so that the online measurement of material weight can be carried out according to the excavator material measurement method on the horizontal plane coordinate system.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. an online weighing method of material in a hydraulic excavator bucket, is characterized in that, as follows: Obtain the pressure value P 1 of the stick hydraulic cylinder and the pressure value P ₂ of the bucket hydraulic cylinder in real time _; Take the center of the hinge point of the base of the excavator and the boom as the origin, the horizontal forward direction is the x-axis, and the direction perpendicular to the x-axis is the y-axis, and the inclination angle θ of the stick relative to the horizontal plane is obtained in real time, and θ is positive above the X-axis. Below is negative; Obtain the length l _AB of the stick hydraulic cylinder and the length l _DE of the bucket hydraulic cylinder in real time; Then the material weighing module brings the data obtained by the sensor into the following formula to obtain the weight of the material in the bucket;

Among them, the parameters l _AC , l _BC , l _DF , l _EF , l _CG , and l _GF can all be obtained from the dimension measurement provided by the manufacturer, and l _EG can be obtained according to the law of cosines; C ₁ and C ₂ are measured by the excavator under no-load conditions Dynamic calibration is obtained; The dynamic calibration process is as follows: firstly, the boom of the hydraulic excavator is raised to a certain height to ensure that the bucket and stick will not touch the ground during the dynamic calibration process, and then the stick is extended successively by controlling the hydraulic cylinder of the stick. Lengthen and shrink to the limit position, respectively record the inclination angles θ ₁ and θ ₂ of the stick at the limit position; take an average of ten angle values Angle ₁ ... Angle ₁₀ in the range of θ ₁ and θ ₂ , and stretch the stick to Angle in turn ₁ ... Angle ₁₀ , and record the data at each angle value with the boom raised and lowered at a constant speed, and then dynamically calibrate two unknown parameters C ₁ and C ₂ related to the center of gravity of the boom in different states through the recursive least square method . 2. The online weighing method of material in the hydraulic excavator bucket as claimed in claim ₁ , wherein the pressure value P1 is measured by a pressure sensor arranged on the bucket. 3. The online weighing method of material in the hydraulic excavator bucket as claimed in claim ₁ , wherein the pressure value P2 is measured by a pressure sensor arranged on the bucket. 4. The method for online weighing of materials in the hydraulic excavator bucket according to claim 1, wherein the inclination angle θ is measured by an angle sensor arranged on the arm. 5. the on-line weighing method of material in the hydraulic excavator bucket as claimed in claim 1, is characterized in that, the length l _AB of described stick hydraulic cylinder is measured by the laser displacement sensor that is arranged on the stick hydraulic cylinder have to. 6. the on-line weighing method of material in the hydraulic excavator bucket as claimed in claim 1, is characterized in that, the length l _DE of described bucket hydraulic cylinder is measured by the laser displacement sensor that is arranged on the bucket hydraulic cylinder have to. 7. The online weighing method for materials in the hydraulic excavator bucket according to claim 1, further comprising a coordinate conversion unit installed on the excavator body. 8. The on-line weighing method of material in the hydraulic excavator bucket as claimed in claim 7, wherein, when the working face where the excavator is located is an inclined surface, the coordinate conversion unit is used to measure the working face of the excavator relative to the horizontal plane. The inclination angle γ, establish the coordinate system X'OY' when the excavator is located on the inclined working face, the angle between the coordinate system X'OY' and the coordinate system XOY is γ, then the coordinate transformation formula of the corresponding points on the two coordinate systems for:

Where (x, y) is the coordinate of a point m on the excavator in the coordinate system XOY, and (x', y') is the coordinate of the point in the coordinate system X'OY'; according to the coordinate conversion formula, the excavator is in When the working face is tilted, each point on the body is mapped to the horizontal coordinate system, so that the online measurement of the material weight is performed according to the excavator material measurement method on the horizontal coordinate system. 9. The online weighing method of materials in the hydraulic excavator bucket according to claim 1, further comprising a historical record function based on a data storage module.

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