Weight calculation system, weight calculation method, and program

Abstract

The present invention provides a weight calculation system that can accurately calculate the weight of the contents of a bucket, regardless of the arm's position. [Solution] A weight calculation system for calculating the weight of an object contained in a bucket rotatably attached to the tip of an arm of a work device, comprising: an acquisition unit that acquires first information from a load sensor that measures the force received by the arm from a bucket cylinder attached between the arm and the bucket, and second information from a posture sensor that detects the posture of the arm; and a calculation unit that calculates the weight of the object based on the first information and the second information acquired by the acquisition unit.

Description

Technical Field

[0001] The present disclosure relates to a weight calculation system, a weight calculation method, and a program.

Background Art

[0002] A technique has been proposed in which a bucket and an arm are connected by a pin-type load cell, and the weight of the contents such as earth and sand in the bucket is detected by measuring the strain generated by the shear force applied to the pin-type load cell. (See, for example, Patent Documents 1-2)

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional technology, there is a problem that the weight of the detected contents varies depending on the posture of the arm.

[0005] Therefore, in one aspect, an object of the present invention is to provide a weight calculation system or the like that can accurately calculate the weight of the contents of a bucket regardless of the posture of the arm.

Means for Solving the Problems

[0006] In one aspect, A weight calculation system for calculating the weight of the contents accommodated in a bucket rotatably attached to the tip side of the arm of a working device, An acquisition unit that acquires first information from a load sensor that measures the force received by the arm from a bucket cylinder mounted between the arm and the bucket, and second information from a posture sensor that detects the posture of the arm, A calculation unit calculates the weight of the contents based on the first information and second information acquired by the acquisition unit, A weight calculation system is provided that includes the following features. [Effects of the Invention]

[0007] In one respect, according to the present invention, the weight of the contents of the bucket can be calculated accurately regardless of the position of the arm. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of the weight calculation system in the first embodiment. [Figure 2] This is a diagram of a hydraulic excavator. [Figure 2A] This diagram shows the state of the most bucket-clouded work machine. [Figure 2B] This diagram shows the state of the work machine with the most bucket-dumped load. [Figure 3] This is a diagram showing the area around the load cell. [Figure 3A] This is a view of the area around the load cell, along the Y-axis. [Figure 4] This figure shows the relationship between the load measurement, the arm angle, and the weight of the contents contained in the bucket in the first embodiment. [Figure 5] This figure shows the direction of the arm and the direction of the load Fx. [Figure 6] This figure shows the relationship between the load measurement, the arm angle, and the weight of the contents contained in the bucket in the second embodiment. [Figure 7] This diagram shows the direction of the arm and the direction of the load F1. [Modes for carrying out the invention]

[0009] (First Embodiment) FIG. 1 is a diagram showing the configuration of the weight calculation system according to the first embodiment. The weight calculation system 100 has a function of calculating the weight of the contents accommodated in a bucket 23 (FIG. 2) rotatably attached to the tip side of an arm 22 of a working device 20.

[0010] As shown in FIG. 1, the weight calculation system 100 includes an acquisition unit 101 that acquires first information from a load sensor 70A that measures the force received by the arm 22 from a bucket cylinder 43 (FIG. 2) attached between the arm 22 and the bucket 23, and second information from an inclinometer 80 (FIG. 2) that detects the posture of the arm 22, a calculation unit 102 that calculates the weight of the contents based on the first information and the second information acquired by the acquisition unit 101, and a storage unit 103 that stores data necessary for the operation of the weight calculation system 100.

[0011] The weight calculation system 100 according to the first embodiment is configured using one or more computers on which a predetermined program is implemented.

[0012] FIG. 2 is a diagram showing a hydraulic excavator, FIG. 2A is a diagram showing the state of the working machine with the bucket most curled, and FIG. 2B is a diagram showing the state of the working machine with the bucket most dumped. Although a hydraulic excavator is exemplified as the working machine to which the weight calculation system 100 is applied, the working machine and the working device to which the weight calculation system 100 is applied are arbitrary.

[0013] As shown in FIG. 2, a hydraulic excavator 10 as a working machine includes a traveling device 11 provided at the lower part of the hydraulic excavator 10, a revolving body 12 rotatably attached to the traveling device 11, and a working device 20 attached to the revolving body 12. Note that the weight calculation system 100 can be mounted on the hydraulic excavator 10. Also, the weight calculation system 100 can be installed outside the hydraulic excavator 10.

[0014] The working device 20 includes a boom 21 whose base end is rotatably connected to the revolving body 12 via a boom pin 21a, an arm 22 whose base end is rotatably connected to the tip of the boom 21 via an arm pin 22a, and a bucket 23 that is rotatably connected to the tip of the arm 22 via a bucket pin 23a.

[0015] As shown in FIG. 2, the boom 21 is driven by a boom cylinder 41. The base end of the boom cylinder 41 is rotatably connected to the revolving body 12 via a support pin 41a, and the tip of the boom cylinder 41 is rotatably connected to the boom 21 via a support pin 41b. As the boom cylinder 41 contracts, a boom lowering operation in which the boom 21 rotates downward around the boom pin 21a is performed, and as the boom cylinder 41 extends, a boom raising operation in which the boom 21 rotates upward around the boom pin 21a is performed.

[0016] The arm 22 is driven by an arm cylinder 42. The base end of the arm cylinder 42 is rotatably connected to the boom 21 via a support pin 42a, and the tip of the arm cylinder 42 is rotatably connected to the bucket 23 via a support pin 42b. As the arm cylinder 42 contracts, an arm dump operation in which the arm 22 rotates upward around the arm pin 22a is performed, and as the arm cylinder 42 extends, an arm crowd operation in which the arm 22 rotates downward around the arm pin 22a is performed.

[0017] In addition, an inclinometer 80 as a posture sensor for acquiring the posture of the arm 22 is attached to the arm 22. The inclinometer 80 outputs a measured angle θ of the angle of the arm 22.

[0018] The bucket 23 is driven by a bucket cylinder 43. The base end of the bucket cylinder 43 is rotatably connected to the arm 22 via a pin-type load cell 70, and the tip of the bucket cylinder 43 is connected to the bucket 23 via a link mechanism 60.

[0019] The link mechanism 60 includes a first link member 61 whose base end is rotatably attached to the arm 22 via a pin 64, and a second link member 62 whose base end is rotatably attached to the bucket 23 via a pin 65. The tips of both the first link member 61 and the second link member 62 are rotatably attached to the tip of the bucket cylinder 43 via a pin 63. With this configuration, as shown in Figures 2A and 2B, as the bucket cylinder 43 extends, a bucket cloud operation is performed in which the bucket 23 rotates inward around the bucket pin 23a as a pivot point, and as the bucket cylinder 43 retracts, a bucket dump operation is performed in which the bucket 23 rotates outward around the bucket pin 23a as a pivot point.

[0020] Figure 3 shows the area around the load cell, and Figure 3A shows the area around the load cell viewed in the Y-axis direction.

[0021] As shown in Figures 3 and 3A, the pin-type load cell 70 is formed in a substantially cylindrical shape with an axis in the Z direction (extension direction of the arm pin 22a) in an XYZ Cartesian coordinate system where the extension and retraction direction of the bucket cylinder 43 is the X-axis, and the direction perpendicular to the X-axis and along the moving surface of the arm 22 is the Y-axis. As shown in Figure 3A, the pin-type load cell 70 has mounting parts 71, 72 and 73 arranged in order in the Z-axis direction. Mounting parts 71 and 73 are fixed to a pair of blankets 22A formed on the arm 22 by a key plate 75, and the base end of the bucket cylinder 43 is rotatably attached to mounting part 72.

[0022] The pin-type load cell 70 incorporates a load sensor 70A (Figure 1) that detects the load (shear force) in the X-axis direction applied to the mounting portion 72 and outputs a measured load value (load Fx) as first information.

[0023] Next, we will explain the operation of the weight calculation system 100.

[0024] Figure 4 shows the relationship between the measured load, the arm angle, and the weight of the contents contained in the bucket in the first embodiment, and Figure 5 shows the direction of the arm and the direction of the load Fx.

[0025] The load Fx is acquired by the acquisition unit 101 as first information (measured load value) output from the load sensor 70A (Figure 1). The measured angle θ is also acquired by the acquisition unit 101 as second information output from the inclinometer 80 (Figure 1). The acquisition unit 101 may acquire the load Fx and measured angle θ via communication means (including wired communication and wireless communication).

[0026] The memory unit 103 (Figure 1) stores the relationship between the load Fx, the measurement angle θ of the arm 22, and the weight W of the contents contained in the bucket 23, as shown in Figure 4. This relationship can be acquired in advance by calibration, for example, and stored in the memory unit 103.

[0027] The calculation unit 102 calculates the weight W of the contents contained in the bucket 23 based on the load Fx and measurement angle θ obtained by the acquisition unit 101, by referring to the relationship shown in Figure 4.

[0028] As shown in Figure 4, the weight W calculated by the calculation unit 102 increases with increasing load Fx, but also depends on the measurement angle θ. In the example in Figure 4, only the cases θ=θ0, θ=θ1, and θ=θ2 are shown, but the relationship between load Fx, measurement angle θ, and weight W can be stored in the storage unit 103 in the form of a table or calculation formula (approximate formula), for example, to satisfy the required range and accuracy.

[0029] Thus, in the first embodiment, the weight W of the contents is calculated not only based on the load Fx obtained from the load sensor 70A, but also based on the measured angle θ obtained from the inclinometer 80. Therefore, the weight W of the contents can always be accurately calculated regardless of the angle of the arm 22. In addition to the measured angle θ indicating the angle of the arm 22, the weight W of the contents may also be calculated based on other information indicating the posture of the work device 20. For example, the angle (direction) of the bucket 23 may be measured by the inclinometer, and the measured angle may be reflected in the calculated value of the weight W.

[0030] (Second example) Figure 6 shows the relationship between the measured load, the arm angle, and the weight of the contents contained in the bucket in the second embodiment, and Figure 7 shows the direction of the arm and the direction of the load F1.

[0031] As shown in Figures 6 and 7, in the second embodiment, a load sensor 70A is used that is capable of detecting loads Fx and Fy for the X and Y axes, respectively. Therefore, in the second embodiment, the load F1 (the resultant force of loads Fx and Fy) that the arm 22 receives from the bucket cylinder 43 can be determined at the mounting location of the load sensor 70A.

[0032] The memory unit 103 (Figure 1) stores the relationship between the load F1, the measurement angle θ of the arm 22, and the weight W of the contents contained in the bucket 23, as shown in Figure 6. This relationship can be acquired in advance by calibration, for example, and stored in the memory unit 103.

[0033] The calculation unit 102 calculates the weight W of the contents contained in the bucket 23 based on the load F1 and measurement angle θ acquired by the acquisition unit 101, by referring to the relationship shown in Figure 6. In the example in Figure 6, only the cases θ=θ0, θ=θ1, and θ=θ2 are illustrated, but the relationship between load Fx, measurement angle θ, and weight W can be stored in the storage unit 103 in the form of a table or calculation formula (approximate formula), for example, to satisfy the required range and accuracy.

[0034] Thus, in the second embodiment, the weight W of the contents is calculated using not only the load Fx obtained from the load sensor 70A, but also the load Fy. Therefore, the weight W of the contents can be calculated with greater accuracy compared to the first embodiment. For example, the load Fx corresponding to the same weight W changes in a complex way depending on the posture of the work device 20, such as the cloud of the bucket 23 and the direction of dumping (see Figures 2A and 2B). However, in the second embodiment, for example, by using load F1, such changes can be suppressed, and thus the accuracy of the calculated weight W can be improved. In addition, in the second embodiment as well, the weight W of the contents is calculated (corrected) based on the measured angle θ obtained from the inclinometer 80. Therefore, the weight W of the contents can always be calculated accurately regardless of the angle of the arm 22. Note that in addition to the measured angle θ indicating the angle of the arm 22, the weight W of the contents may also be calculated based on other information indicating the posture of the work device 20. For example, the angle (direction) of the bucket 23 may be measured by the inclinometer, and the measured angle may be reflected in the calculated weight W.

[0035] Note that while Figure 7 shows an example where load F1 (the resultant force of loads Fx and Fy) is treated as a single variable, loads Fx and Fy may also be treated as separate variables.

[0036] As described above, according to the above embodiment, the weight W of the contents of the bucket 23 is calculated based on first information from the load sensor 70A, which measures the force received by the arm 22 from the bucket cylinder 43, and second information from the inclinometer 80, which detects the posture of the arm 22. Therefore, the weight W of the contents of the bucket 23 can be calculated accurately regardless of the posture of the arm 22. Consequently, for example, it is no longer necessary to keep the hydraulic excavator 10 in the same posture each time when calculating the weight W, reducing the effort and time required for manual operation by the operator. Therefore, for example, extra actions required for load detection are not necessary in a series of operations such as excavation and loading, improving work efficiency.

[0037] Furthermore, in general, when loading soil and sand onto dump trucks using hydraulic excavators at construction sites, it is necessary to manage the load to prevent the dump trucks from becoming overloaded. However, at construction sites, soil and sand are often loaded without checking the weight, and whether or not it is overloaded is judged based on the shape of the cargo bed (package appearance). In this case, it is difficult to judge the load weight because the weight changes greatly depending on the moisture content of the soil and sand. In addition, large dump trucks with a maximum load capacity of 5 tons or more are required to be equipped with a weighing scale, but most of these are analog meters and are mounted on the underside of the cargo bed. Therefore, when using them, the driver has to get out of the seat to check the meter reading, so they are rarely used effectively. In addition, some sites may consider introducing a truck scale, but it needs to be installed on a level and flat surface, and a measuring person must also be stationed there, so the hurdles to installation tend to be high.

[0038] In contrast, according to this embodiment, the weight W of the contents of the bucket 23 can be calculated accurately without having to worry about the posture of the work machine. Therefore, the loading weight onto the dump truck can be properly managed.

[0039] Furthermore, costs can be reduced by, for example, making the weight calculation system 100 compatible with a monitor and retrofitting it to existing work machinery.

[0040] Furthermore, by not only being able to monitor the weight W of the contents of bucket 23, but also being able to output it as data in a predetermined format, the weight W can be incorporated into the automated driving system as loading information. In this case, by executing a process to automatically calculate the weight W, the automated driving system can, for example, determine the loading weight onto the dump truck.

[0041] Although each embodiment has been described in detail above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the claims. Furthermore, it is possible to combine all or more of the components of the embodiments described above. For example, this disclosure can be applied to any work machine and work apparatus. [Explanation of symbols]

[0042] 20 Working equipment 22 Arms 23 buckets 43 Bucket Cylinder 100 Weight Calculation System 101 Acquisition Department 102 Calculation Unit 103 Storage section

Claims

1. A weight calculation system for calculating the weight of an object contained in a bucket rotatably mounted on the tip of the arm of a work device, An acquisition unit that acquires first information from a load sensor that measures the force received by the arm from a bucket cylinder mounted between the arm and the bucket, and second information from a posture sensor that detects the posture of the arm, A calculation unit calculates the weight of the contents based on the first information and the second information acquired by the acquisition unit, A weight calculation system equipped with the following features.

2. The weight calculation system according to claim 1, wherein the first information includes a measured value of a force applied to the bucket cylinder in a first direction corresponding to the extension and contraction direction of the bucket cylinder.

3. The weight calculation system according to claim 2, wherein the first information includes a measured value of a force received by the arm from the bucket cylinder in a second direction perpendicular to the first direction and along the vertically moving surface of the arm.

4. A method for calculating the weight of an object contained in a bucket rotatably attached to the tip of the arm of a work device, An acquisition step of acquiring first information from a load sensor that measures the force received by the arm from a bucket cylinder attached between the arm and the bucket, and second information from a posture sensor that detects the posture of the arm, A calculation step in which the weight of the contents is calculated based on the first information and the second information obtained in the acquisition step, A weight calculation method comprising the following features.

5. A program that causes a computer to execute a weight calculation method for calculating the weight of an object contained in a bucket rotatably attached to the tip of the arm of a work device, The aforementioned weight calculation method is: An acquisition step of acquiring first information from a load sensor that measures the force received by the arm from a bucket cylinder attached between the arm and the bucket, and second information from a posture sensor that detects the posture of the arm, A calculation step in which the weight of the contents is calculated based on the first information and the second information obtained in the acquisition step, A program that includes the following features.

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