Soil property determination device and soil property determination method

Abstract

To realize a soil property determination technique that is more accurate and simpler.SOLUTION: A soil property determination device 1 comprises a sample container 11, a stirring unit 10, and a control unit 20. The sample container 11 accommodates a sample formed by aggregating soil to be subjected to soil property determination. The stirring unit 10 stirs the sample accommodated in the sample container 11. The control unit 20 controls the stirring unit 10 on the basis of control parameters for the stirring unit 10, and acquires a response of the sample to stirring on the basis of the control parameters. The control unit 20 determines a soil property of the sample on the basis of the response of the sample to stirring.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a soil quality determination device and a soil quality determination method. [Background technology]

[0002] Conventionally, boring surveys are carried out to determine soil quality. When determining soil quality through boring surveys, soil classification is determined by human judgment based on visual and tactile observations. In determining such soil classification, although the particle size of gravel and sand can be distinguished visually, the particle size of clay and silt is small and therefore difficult to distinguish visually. Patent Document 1 describes a technique for applying vibration to soil and determining the soil quality from images of the conditions before and after the vibration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-066613 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technique described in Patent Document 1 requires large-scale devices such as a device for vibrating the soil and a device for capturing images of the soil. Furthermore, the technology described in Patent Document 1 judges soil quality using criteria that are different from those used to judge soil quality classification based on human intuition, so there is a possibility that the results may not match those obtained by a skilled worker.

[0005] An object of the present invention is to realize a soil quality determination technique that is more accurate and simpler. [Means for solving the problem]

[0006] In order to achieve the above object, a soil quality determination device according to one aspect of the present invention comprises: a container for containing a sample of soil in the form of a lump, the sample being the object of soil quality assessment; a stirring means for stirring the sample contained in the container; a control means for controlling the stirring means based on a control parameter for the stirring means, and for obtaining a response of the sample to the stirring based on the control parameter; determining means for determining the soil quality of the sample based on the response of the sample to the agitation; The present invention is characterized by comprising: [Effects of the Invention]

[0007] According to the present invention, a more accurate and simple soil quality determination technique can be realized. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of a soil quality determination device 1 according to one embodiment of the present invention. [Figure 2] FIG. 1 is a conceptual diagram showing an example of soil classification. [Figure 3] 2 is a schematic diagram showing the hardware configuration of an information processing device 800 that constitutes the control unit 20. FIG. [Figure 4] FIG. 2 is a block diagram showing the functional configuration of a control unit 20. [Figure 5] FIG. 2 is a schematic diagram showing the position and force control algorithm used in the control unit 20. [Figure 6] 3 is a flowchart showing the flow of a soil quality determination process executed by the soil quality determination device 1. [Figure 7] FIG. 2 is a schematic diagram showing an example of a state in which a sample is placed in a sample container 11. [Figure 8] 1 is a schematic diagram showing an example of a state in which fixing members 12 and 13 and a driving motor 14 are installed in a sample container 11. FIG. [Figure 9] FIG. 10 shows a state in which the sample has been stirred. [Figure 10]FIG. 10 is a schematic diagram showing the relationship between time and measured torque values. [Figure 11] FIG. 10 is a schematic diagram showing the relationship between time and the rotation speed of the drive motor 14. [Figure 12] FIG. 1 is a diagram showing the relationship between the fine particle content and the average value of the rotational torque (average rotational torque). [Figure 13] FIG. 10 is a diagram showing the relationship between the uniform clay content and the uniform standard deviation of the rotational torque value. [Figure 14] FIG. 10 is a diagram showing the relationship between the uniform content rate of silt and the uniform division of the standard deviation of the rotational torque value. [Figure 15] 13 is a diagram illustrating the results of confirming the soil type in which the rotational torque value was measured to be high in the experiment shown in FIG. 12.

[0033] FIG. [Figure 16] FIG. 10 is a schematic diagram showing the relationship between time and measured torque values. [Figure 17] FIG. 1 is a diagram showing the relationship between the fine particle content and the average value of the rotational torque (average rotational torque). [Figure 18] This is a graph plotting the average values ​​of the average rotational torque measured up to 25 times. [Figure 19] FIG. 10 is a diagram showing the standard deviation of rotational torque values ​​divided equally. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Basic concept of the present invention] The present invention measures the response (physical quantities such as force, position, and speed) received by the stirring member from a sample (e.g., a lump-shaped soil mass) whose soil quality is to be determined by stirring the sample. The stirring is performed using position-force control technology used to transmit haptic sensations, and the response (physical quantities such as rotational torque and rotational speed) from the sample is measured using various data (control parameters) used for control during the stirring. As a position / force control technique, the techniques described in International Publication No. 2015 / 041046 or International Publication No. 2005 / 109139, which are applications filed by some of the applicants of the present application, can be used. The soil quality of the sample (such as the content of fine particles consisting of clay and silt) is then determined based on the measurement results obtained during mixing. The criteria used in this process are generated based on data on known soil properties. Therefore, it is possible to judge the soil quality based on data that is close to the feel (touch, etc.) that a person would have when making the judgment. Therefore, a more accurate and simple soil quality determination technique can be realized. Specific embodiments of the present invention will be described below.

[0010] [Configuration of soil quality determination device] FIG. 1 is a schematic diagram showing the configuration of a soil quality determining device 1 according to one embodiment of the present invention. As shown in FIG. 1, the soil quality determination device 1 includes an agitation unit 10 (agitation means) and a control unit (control means, determination means) 20, and the agitation unit 10 and the control unit 20 are configured to be able to communicate with each other via a network using wired or wireless communication. The stirring unit 10 includes a sample container (container) 11, fixing members 12 and 13, and a driving motor 14. The sample container 11 is, for example, a glass container (beaker, etc.) that contains a sample (clod of soil) whose soil quality is to be determined. In this embodiment, the sample clod of soil is obtained by gradually adding water to collected soil, and solidifying it to a moisture content that is sufficient to form a clump but not to cause it to collapse. Since it is desirable to be able to visually observe the state of the sample from the outside while it is being stirred, it is preferable that the sample container 11 be made of a transparent material.

[0011] The fixing members 12 and 13 are plate-like members that fix the sample container 11, and a drive motor 14 is installed on the fixing member 12. When a sample (clod of soil) is contained in the sample container 11 and is to be stirred, the fixing member 12 closes the opening of the sample container 11 placed on the fixing member 13 from above, and the fixing members 12 and 13 are fixed in place by fixtures such as bolts. As a result, the sample container 11 is sandwiched between the fixing members 12 and 13 and fixed together, and the drive motor 14 is able to stir the sample from outside.

[0012] The drive motor 14 is equipped with a rotating rod 14a that rotates to stir the sample, and stirs the sample inside the sample container 11 through a through-hole formed in the fixing member 12. Blades 14b for stirring the sample are attached to the tip of the rotating rod 14a, and as the rotating rod 14a rotates, the blades 14b break down the sample clods while stirring them. At this time, the force (reaction force) that blades 14b receive from the sample clods is transmitted to the rotating rod 14a, and therefore the drive torque is controlled by the control unit 20 to maintain the rotation speed of the drive motor 14 at a target rotation speed.

[0013] The control unit 20 controls the rotational speed and force (rotational torque) of the drive motor 14 using an algorithm (described later) that can control position and force independently. At this time, the control unit 20 sequentially detects the reaction force that the blades 14b of the drive motor 14 receive from the soil mass of the sample, sequentially calculates the target rotational torque (rotational torque corresponding to the reaction force from the sample) for the rotational speed of the blades 14b to become the target rotational speed, and outputs command values ​​(force command value and position command value) to the drive motor 14.

[0014] The control unit 20 also stores the control parameters output when controlling the drive motor 14, and executes processing to determine the soil quality of the sample (clod) based on the control parameters. In this embodiment, the control unit 20 acquires the rotational torque (physical quantity when the sample is stirred) when the sample (soil mass) is stirred, and judges the soil quality of the sample by comparing the acquired rotational torque with a judgment criterion.

[0015] Figure 2 is a conceptual diagram showing an example of soil classification. In conventional soil quality assessments using boring surveys, soil classification is determined by human judgment based on visual and tactile observation. Although the particle size of gravel and sand can be distinguished visually, the particle size of clay and silt is small, making it difficult to distinguish visually. Therefore, when distinguishing between clay and silt, the subdivision is mainly based on the feel of stickiness, as shown in Figure 2, and also takes into account the amount of sand mixed in.

[0016] Here, when determining soil quality using conventional boring surveys, even when distinguishing between clay and silt is done by a human, the distinction is not always made correctly, and there is variation depending on the person making the determination. Furthermore, as the super-aging society continues to progress, a large number of elderly workers are expected to leave the workforce, raising concerns about a labor shortage. Therefore, efforts are being made to realize technology that can replace humans and perform work at the same level or better than humans, by using robots, AI (Artificial Intelligence), etc. to assist human judgment. In other words, there will be an increasing demand in the future to realize the automation and autonomy of technology and improve quality by passing on the techniques currently used by humans as objective information and turning tacit knowledge into explicit knowledge.

[0017] The position / force control technology (so-called real haptics technology) applied in this embodiment is a force tactile transmission technology that can perform force control and force measurement for transmitting the sensation of a contact object. This invention aims to standardize the judgment currently performed by humans based on touch as a judgment method based on objective criteria by using position / force control technology (real haptics technology). Position / force control technology (real haptics technology) can quantify the sensation, thereby obtaining physical properties that reflect the state of viscosity, enabling more accurate soil quality judgment. In addition, soil quality can be judged by stirring the collected sample, allowing soil quality to be judged using simple equipment.

[0018] [Configuration of control unit 20] Next, the configuration of the control unit 20 will be described. The control unit 20 includes an information processing device such as a PC (Personal Computer), a PLC (Programmable Logic Controller), or an IC (Integrated Circuit), and controls the rotation of the drive motor 14 according to set conditions.

[0019] FIG. 3 is a schematic diagram showing the hardware configuration of an information processing device 800 that constitutes the control unit 20. As shown in FIG. As shown in FIG. 3, the information processing device 800 constituting the control unit 20 includes a processor 811, a ROM (Read Only Memory) 812, a RAM (Random Access Memory) 813, a bus 814, an input unit 815, an output unit 816, a memory unit 817, a communication unit 818, a drive 819, and an imaging unit 820.

[0020] The processor 811 executes various processes according to a program recorded in the ROM 812 or a program loaded from the storage unit 817 into the RAM 813 . The RAM 813 also stores data and the like necessary for the processor 811 to execute various processes.

[0021] The processor 811, ROM 812, and RAM 813 are connected to one another via a bus 814. To the bus 814, an input unit 815, an output unit 816, a storage unit 817, a communication unit 818, a drive 819, and an imaging unit 820 are connected.

[0022] The input unit 815 is composed of various buttons, a keyboard, a pointing device, etc., and inputs various information in response to instruction operations. The output unit 816 is composed of a display, a speaker, etc., and outputs images and sounds. The storage unit 817 is configured with a hard disk or a DRAM (Dynamic Random Access Memory), etc., and stores various data managed by the soil type determination device 1. The communication unit 818 controls communication with other devices via the network.

[0023] Removable media 831, such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, is appropriately loaded into the drive 819. A program read from the removable media 831 by the drive 819 is installed in the storage unit 817 as needed. The imaging unit 820 is configured by an imaging device equipped with a lens, an imaging element, etc., and captures a digital image of a subject.

[0024] It is also possible to omit the imaging unit 820 from the information processing device 800. Also, the information processing device 800 can be configured with a touch panel by configuring the input unit 815 with a touch sensor and arranging it over the display of the output unit 816.

[0025] [Functional configuration] Next, the functional configuration of the control unit 20 will be described. FIG. 4 is a block diagram showing the functional configuration of the control unit 20. As shown in FIG. As shown in FIG. 4, the system includes a position data acquisition unit 21, a drive control unit 22, a command value output unit 23, and an analysis unit 24. The position data acquisition unit 21 acquires data on the position (angular position) of the rotation shaft of the drive motor 14. The position of the rotation shaft of the drive motor 14 can be acquired from a rotary encoder built into the drive motor 14, or from a separately provided position sensor or the like.

[0026] Based on data on the position (angular position) of the rotation shaft of the drive motor 14 acquired by the position data acquisition unit 21, the drive control unit 22 calculates a control command value (a command value for eliminating the error between the target rotation speed and the current rotation speed and for eliminating the error between the target rotation torque and the current rotation torque) so that the rotation shaft of the drive motor 14 rotates at the target rotation speed and the target rotation torque. For example, the drive control unit 22 calculates a value of a drive current (current command value) for the drive motor 14 as the control command value. The drive control unit 22 calculates the current rotation speed and rotation torque from acceleration-dimensional data obtained by second-order differentiation of the position of the rotation shaft of the drive motor 14 acquired by the position data acquisition unit 21, and uses the calculated data to calculate the control command value. Note that the data acquired by the drive control unit 22 to control the drive motor 14 and the command values ​​calculated are included in the "control parameters" in this embodiment. The command value output unit 23 outputs the control parameter (here, a current command value) calculated by the drive control unit 22 to the drive motor 14. As a result, the drive current is controlled by the driver of the drive motor 14 so that the drive motor 14 operates at the target rotation position and target rotation torque.

[0027] The analysis unit 24 calculates the physical quantity during sample stirring based on the time-series data used to control the drive motor 14. The calculated physical quantity corresponds to the measurement result (response from the sample) measured during sample stirring, and in this embodiment, for example, the average value of the rotational torque value (average rotational torque) is calculated as the physical quantity during sample stirring. As an example, the analysis unit 24 acquires data on the position (angular position) of the rotational shaft of the drive motor 14 acquired by the position data acquisition unit 21, as well as data on the target rotational position and target rotational torque (reference values), as time-series data, and calculates the average value of the rotational torque value during sample stirring (average rotational torque). Note that, instead of the position (angular position) of the rotational shaft of the drive motor 14 acquired by the position data acquisition unit 21, the current rotational speed and rotational torque calculated from acceleration-dimensional data obtained by second-order differentiation of the position of the rotational shaft may be used.

[0028] At this time, the analysis unit 24 calculates the average rotational torque value by excluding data to be excluded from the rotational torque data of the drive motor 14. The data to be excluded is data that is estimated to not adequately represent the physical quantity of the sample (response from the sample) during mixing. For example, data from a predetermined period of time (e.g., 5 seconds) at the beginning of mixing, data in which the rotational torque continues to increase abnormally (up to or above a set threshold) and does not converge, and data in which the rotational torque begins to increase suddenly (at a rate of change above a set threshold) during mixing, etc., can be excluded. In this embodiment, conditions for excluding data to be used (exclusion conditions) are set in advance, and the analysis unit 24 performs analysis after excluding data of the rotational torque of the drive motor 14 based on the exclusion conditions. The threshold used to exclude data to be excluded can be an absolute value determined based on the results of measuring a large number of samples, or it can be determined as the ratio of the rotational torque value that is determined to be relatively excessive or insufficient in the measurement results (data group) of a single sample (e.g., "30% or more higher than the average").

[0029] The analysis unit 24 also determines the soil quality of the sample based on the calculated physical quantity (average rotational torque). In this embodiment, for a sample in which the fine particle content Fc (clay and silt content) is high in a predetermined range (e.g., 80% or more), the analysis unit 24 determines that the fine particle content is higher as the average rotational torque when stirring the sample increases. Furthermore, when distinguishing between the clay content and the silt content, the analysis unit 24 calculates the clay content by subtracting the silt content from the fine particle content, using the silt content as a reference. The silt content can be estimated by dividing the standard deviation σ(M+C) (=2·σ·Fc / 100) of the rotational torque values ​​in a single measurement of clay and silt equally, and then estimating the relationship between this equally divided standard deviation and the uniform silt content (a relationship derived based on known soil properties).

[0030] [Position and force control algorithm] Next, the position and force control algorithms used in the control unit 20 will be described. As described above, in this embodiment, the technology described in International Publication No. 2015 / 041046 or International Publication No. 2005 / 109139 can be used, but here we will explain the application of the algorithm described in International Publication No. 2015 / 041046. FIG. 5 is a schematic diagram showing the position and force control algorithm used in the control unit 20. As shown in FIG. 5, the position and force control algorithm used in the control unit 20 is expressed as a control law including a controlled system S, a functional force-velocity allocation conversion block FT, at least one of an ideal force source block FC or an ideal velocity (position) source block PC, and an inverse conversion block IFT.

[0031] The controlled system S is a system that is operated by an actuator, and controls the actuator based on acceleration, etc. In this embodiment, the controlled system S is configured by a drive motor 14.

[0032] The functional force-speed allocation transformation block FT defines the transformation of control energy into the velocity (position) and force domains set according to the function of the controlled system S. Specifically, the functional force-speed allocation transformation block FT defines a coordinate transformation that takes as input the reference value (reference value) of the function of the controlled system S and the current position of the actuator (drive motor 14). This coordinate transformation generally transforms an input vector whose elements are the reference value and the current velocity (position) into an output vector consisting of velocity (position) for calculating the target velocity (position) control value, and also transforms an input vector whose elements are the reference value and the current force into an output vector consisting of force for calculating the target force control value. Specifically, the coordinate transformation in the functional force-speed allocation transformation block FT is generalized and expressed as the following equations (1) and (2).

[0033]

number

[0034] However, in formula (1), x'1 to x' n (n is an integer greater than or equal to 1) is the velocity vector for deriving the velocity state value, and x' a ~x' m (m is an integer of 1 or more) is a vector whose elements are the reference value and the velocity based on the action of the actuator (the velocity of the actuator's moving element or the velocity of the object moved by the actuator), h 1a ~h nm are elements of the transformation matrix that represents the function. Also, in equation (2), f1 to f n (n is an integer greater than or equal to 1) is a force vector for deriving the force state value, and f a ~f m (m is an integer of 1 or more) is a vector whose elements are a reference value and a force based on the action of the actuator (the force of the actuator's moving element or the force of the object moved by the actuator). By setting the coordinate transformation in the functional force / velocity allocation transformation block FT according to the function to be realized, it is possible to realize various actions and reproduce actions involving scaling. That is, in the basic principle of this invention, the functional force-velocity allocation conversion block FT "converts" the variables of a single actuator (variables in real space) into a group of variables of the entire system (variables in virtual space) that express the functions to be realized, and allocates control energy to the control energy of velocity (position) and the control energy of force. Therefore, compared to when control is performed using the variables of a single actuator (variables in real space), it is possible to assign the control energy of velocity (position) and the control energy of force independently.

[0035] The Ideal Force Source Block FC is a block that performs calculations in the force domain according to the coordinate transformation defined by the Functional Force-Velocity Allocation Transformation Block FT. In the Ideal Force Source Block FC, a target value for force is set when performing calculations based on the coordinate transformation defined by the Functional Force-Velocity Allocation Transformation Block FT. This target value is set as a fixed value or a variable value depending on the function to be realized. For example, when realizing a function similar to the function indicated by the reference value, zero can be set as the target value, or when scaling is performed, a value obtained by enlarging or reducing the information indicating the function to be reproduced can be set.

[0036] The ideal velocity (position) source block PC is a block that performs calculations in the velocity (position) domain according to the coordinate transformation defined by the functional force-velocity allocation transformation block FT. In the ideal velocity (position) source block PC, a target value for velocity (position) is set when performing calculations based on the coordinate transformation defined by the functional force-velocity allocation transformation block FT. This target value is set as a fixed value or a variable value depending on the function to be realized. For example, if you want to achieve a function similar to the function indicated by the reference value, you can set zero as the target value, or if scaling is performed, you can set a value that is an enlarged or reduced version of the information indicating the function to be reproduced.

[0037] The inverse transformation block IFT is a block that converts values ​​in the domain of velocity (position) and force into values ​​in the domain of input to the controlled system S (for example, voltage values ​​or current values). Based on this basic principle, when position information of the actuator of the controlled system S is input to the functional force-velocity allocation conversion block FT, the functional force-velocity allocation conversion block FT applies the control rules for each position and force region according to the function using the velocity (position) and force information obtained based on the position information. Then, the ideal force source block FC calculates the force according to the function, and the ideal velocity (position) source block PC calculates the velocity (position) according to the function, and the control energy is distributed to each of the force and velocity (position).

[0038] The calculation results in the ideal force source block FC and the ideal velocity (position) source block PC become information indicating the control target of the controlled system S, and these calculation results are used as input values ​​for the actuators in the inverse transformation block IFT and input to the controlled system S. As a result, the actuators of the controlled system S perform operations according to the functions defined by the functional force-velocity allocation transformation block FT, and the desired system operation is realized.

[0039] With the above-described configuration, the soil quality determination device 1 according to this embodiment can determine the soil quality (such as the content of fine particles consisting of clay and silt) contained in a sample based on the measurement results (physical quantities at the time of stirring the sample) measured when the sample is stirred. The measurement results measured when the sample is stirred represent the tactile sensation given by the sample. Therefore, it is possible to judge the soil quality based on data that is close to the feel (touch, etc.) that a person would have when making the judgment. Furthermore, the soil quality can be determined by stirring the collected sample, so that the soil quality can be determined using a simple device.

[0040] [Operation] Next, the operation of the soil type determining device 1 will be described. Before the soil quality determination device 1 executes a process for determining the soil quality of a sample (soil quality determination process), a lump of the sample, compacted into a ball, is first placed in the sample container 11. Here, two samples are used, with one sample placed on each side of the center of the sample container 11. Compacting the sample into a ball eliminates variation in the initial state, allowing for more objective measurement of the sample. That is, the sample to be determined here is composed mainly of clay and silt, and therefore becomes ball-shaped when a certain amount of water is added, and if too much water is added, it will not be able to maintain its shape (i.e., it will collapse). Therefore, compacting the sample into a ball allows for an appropriate initial state.

[0041] Then, the sample container 11 is fixed by the fixing members 12 and 13. These preparation steps can be performed manually by an operator, but may also be performed automatically by a robot or the like for performing the preparation steps. Next, the soil quality is determined by the soil quality determining device 1.

[0042] FIG. 6 is a flowchart showing the flow of the soil quality determination process executed by the soil quality determination device 1. The soil quality determination process is started in response to an instruction to execute the soil quality determination process being input to the control unit 20. As shown in FIG. 6, when the soil type determination process is started, in step S1, the drive control unit 22 calculates control parameters (current command values) for operating the stopped drive motor 14 at a target rotation speed and target rotation torque (reference values). In step S2, the command value output unit 23 outputs the control parameter (current command value) calculated by the drive control unit 22 to the drive motor 14. As a result, the drive motor 14 rotates at the target rotation speed and target rotation torque.

[0043] In step S3, the position data acquisition unit 21 acquires data on the position (angular position) of the rotation shaft of the drive motor 14. In step S4, the drive control unit 22 calculates a control command value (a current command value for eliminating the error between the target rotation speed and the current rotation speed, and for eliminating the error between the target rotation torque and the current rotation torque) based on the acquired data on the position (angular position) of the rotation shaft of the drive motor 14 so that the rotation shaft of the drive motor 14 rotates at the target rotation speed and target rotation torque (reference value).

[0044] In step S5, the drive control unit 22 determines whether or not a set time (for example, one minute) has elapsed for stirring the sample. If the set time (for example, 1 minute) for mixing the sample has not elapsed, the determination in step S5 is NO, and the process proceeds to step S3. On the other hand, if the set time (for example, 1 minute) for stirring the sample has elapsed, the determination in step S5 is YES, and the process proceeds to step S6.

[0045] In step S6, the analysis unit 24 calculates a physical quantity (here, the average rotational torque) during sample agitation based on the time-series data used to control the drive motor 14, and determines the soil quality of the sample based on the calculated average rotational torque. As described above, the calculated physical quantity (average rotational torque) corresponds to the measurement result (response from the sample) measured during sample agitation. In this embodiment, the analysis unit 24 determines that the fine particle content Fc (clay and silt content) is higher in a predetermined range (e.g., 80% or higher) as the average rotational torque during agitation is higher. The analysis unit 24 also estimates the silt content from the relationship between the equalized standard deviation of the torque values ​​measured for clay and silt and the equalized silt content (a relationship derived based on known soil properties), and calculates the clay content by subtracting the silt content from the fine particle content based on the silt content. In step S7, the analysis unit 24 outputs (stores or displays, etc.) the results of determining the soil quality of the sample. After step S7, the soil type determination process ends.

[0046] This type of processing makes it possible to determine soil quality based on data that is close to the feel (touch, etc.) that a person would have when making the determination. In addition, because soil quality can be determined by stirring the collected sample, soil quality can be determined using a simple device. Therefore, a more accurate and simple soil quality determination technique can be realized.

[0047] [Verification of effectiveness] Hereinafter, an experiment was conducted on a soil quality determination method using the soil quality determination device 1 according to this embodiment, and the results of verifying the effects thereof will be described. [Experimental Method] Fig. 7 is a schematic diagram showing an example of a state in which a sample is placed in a sample container 11. Fig. 8 is a schematic diagram showing an example of a state in which fixing members 12 and 13 and a drive motor 14 are placed in the sample container 11. Fig. 9 is a diagram showing a state in which the sample has been stirred. The procedure of the experimental method will be explained below with reference to FIGS. 7 to 9 as appropriate.

[0048] (1) Two lump-shaped samples (clay soil lumps) were prepared and placed on opposite sides of the center of a glass container (diameter 95 mm, height 78 mm). Here, the size of the sample was adjusted based on the height so that the size of the sample lump reached the top of the stirring blade 14b (see Figure 7). If the sample was larger than the top of the stirring blade 14b, either reduce the amount of sample or deform the sample by hand.

[0049] (2) The fixing members 12 and 13 and the drive motor 14 are arranged in the sample container 11 with the positions of the blades 14b and the samples offset so that the two samples and the blades 14b do not overlap in the vertical direction. (3) Fix the fixing members 12 and 13 with jigs (bolts, nuts, etc.) (see FIG. 8). (4) The control unit 20 is operated to rotate the drive motor 14 at 0.5 [rps] (30 rotations per minute). (5) Measure the sample for at least one minute and then stop the rotation. (6) Remove the fixing members 12, 13 and the drive motor 14 from the sample container 11, and check the state of the sample. If the sample is not broken down by the blades 14b, such as when the sample is attached to the blades 14b and being dragged around, the stirring process is inappropriate, and the data is discarded.

[0050] [Data analysis method] FIG. 10 is a schematic diagram showing the relationship between time and the measured torque value. FIG. 11 is a schematic diagram showing the relationship between time and the rotation speed of the drive motor 14. As shown in FIG. As shown in FIGS. 10 and 11, waveform graphs of torque value versus time and rotational speed versus time were generated as representative waveform graphs of the measurement results of the sample. In the waveform graph of the torque values ​​shown in FIG. 10, for all measurement times, some torque values ​​become excessively large in the range of about 0 to 5 seconds, then gradually decrease or remain almost horizontal.

[0051] The purpose of the measurements in this embodiment is to quantify the feel of the blades 14b touching the sample. Therefore, data from the 0-5 second interval was excluded from processing because the increase in measurement value was due to the large influence of soil pressure at the start of mixing. Furthermore, although 25 measurements were taken for one sample, some of the measurement results included data in which the rotational torque continued to increase abnormally (above a set threshold) and did not converge, and data in which the rotational torque began to increase suddenly (above a set threshold) during mixing. Therefore, these data were also excluded from processing.

[0052] In Figure 11, the waveform graph of the rotation speed is controlled to match the target rotation speed of 3.14 (=0.5 [rps]). Data analysis revealed that properly measured data generally falls within the range of ±0.25 (2.89 to 3.39). If there was an error greater than this and the data was outside the appropriate range, there was a high possibility that the sample had adhered to the blade 14b and was being dragged around, so it was excluded from processing. As a result, 2 samples were excluded from the 47 samples, and 45 samples were used.

[0053] [Conditions for comparison with sample particle size distribution] The conditions for comparison with the particle size distribution of the sample are as follows: (1) Test data · 25 measurements per sample · 47 samples were measured. ·Extraction time: 5~60 seconds Rotational torque and rotational speed measurements: 5500 data per measurement (every 0.01 seconds)

[0054] (2) Assumptions (i) A comparison of the waveform graphs of 47 samples showed that the rotational torque value tends to decrease as the amount of sand mixed in increases. Based on this, it was assumed that the fine particle content Fc [%] is related to the average value of the rotational torque value in one measurement (average rotational torque). (ii) The standard deviation σ of the rotational torque value in a single measurement was calculated from the unbiased variance, and a 95% confidence interval was used, using 2σ. From the data of 47 samples, the standard deviation σ of the rotational torque value in a single measurement tends to be larger when there is a high clay content and smaller when there is a high silt content, compared to the particle size distribution in the soil test. Therefore, in order to numerically exclude the influence of gravel and sand, it was decided to calculate the standard deviation σ(M+C) of the rotational torque value in a single measurement of the clay and silt content from the fine particle content Fc [%] in equal parts. σ(M+C)=2·σ·Fc / 100

[0055] Furthermore, to distinguish between the clay content C [%] and the silt content M [%], an equal division was adopted, where the clay content C [%] and the silt content M [%] were divided by the fine particle content Fc [%]. The equal division of the standard deviation of the torque values ​​for the clay content σ(M) and the equal division of the standard deviation of the torque values ​​for the silt content σ(C) were calculated by multiplying the equal division of the clay and silt content by the standard deviation of the rotational torque values ​​for the clay and silt content in a single measurement σ(M+C). In other words, the equal division of the standard deviation of the torque values ​​for the clay content σ(M) and the equal division of the standard deviation of the torque values ​​for the silt content σ(C) can be calculated as follows: Standard deviation of torque value of clay fraction σ(M) = σ(M+C)·C / Fc[%] Standard deviation of torque value of silt component divided equally σ(C)= σ(M+C)·M / Fc[%]

[0056] [Comparison results] Based on the above indicators, the soil quality of the samples was compared with the measurement data, and the following results were found. (1) Relationship between fine particle content and torque value FIG. 12 is a diagram showing the relationship between the fine particle content and the average value of the rotational torque (average rotational torque). As shown in FIG. 12, although there is variation within each data, there is correlation up to 80% to 100%, where it is difficult to determine the soil type visually. Therefore, by using a measurement method that reduces data variability, such as measuring the same sample multiple times, the fine particle content can be determined from the average value of the measured torque values ​​(average rotational torque), at least in a specified range where the fine particle content is high (80[%] to 100[%] in the example of Figure 12).

[0057] (2) Relationship between the clay and silt content and the standard deviation of torque values ​​divided equally Fig. 13 is a diagram showing the relationship between the uniform clay content and the uniform standard deviation of the rotational torque value, and Fig. 14 is a diagram showing the relationship between the uniform silt content and the uniform standard deviation of the rotational torque value. Referring to Figs. 13 and 14, the uniform content of the silt content has smaller variations in the uniform standard deviation of the torque values ​​than the uniform content of the clay content. Therefore, the fine particle content is determined based on the measurement results, and the silt content is estimated from the relationship between the uniform silt content and the uniform standard deviation of the torque value.The clay content can then be estimated by subtracting the silt content from the fine particle content.

[0058] [Additional verification of effects] An additional verification was carried out to verify the effects of using the soil type determination device 1 according to this embodiment. [Data analysis method] In this additional verification, first, the moisture content of the clayey soil sample was measured one to three times depending on the number of measurements during the experiment. The test method was carried out in accordance with the Geotechnical Society standard JGS0122-202, "Method for testing soil moisture content using a microwave oven." The moisture content measurement was carried out using a microwave oven with an output of 600W and a heating time of 20 minutes (for organic soil), as specified as a guideline. After the experiment, the clayey soil samples were subjected to a soil particle size test (JIS A 1204), a soil water content test (JIS A 1203), and a soil liquid limit and plastic limit test (JIS A 1205) depending on the remaining sample amount.

[0059] The clay samples used in the experiments were mixed thoroughly with water to make them sticky before the experiment was carried out. Of the 101 samples, the most common was 48 samples with a moisture content of 50.1 to 100%, followed by 24 samples with a moisture content of 0 to 50%, and then 18 samples with a moisture content of 101 to 150%, together accounting for approximately 90%.

[0060] Additionally, the difference between the moisture content measured using the microwave oven and that measured in the laboratory soil test was measured. At this time, the moisture content of the laboratory soil test was adjusted using the remaining sample volume, so this was carried out on 76 of the 101 samples. As a result, since 90% of the samples had a moisture content difference of 10% or less, the microwave moisture content can be considered to be roughly equivalent to that of the laboratory soil test. Liquid limit and plastic limit tests were conducted on the remaining samples, excluding the two NP (Non-Plastic) samples. The soil consistency was evaluated at microwave and laboratory soil test moisture contents.

[0061] As a result, the microwave moisture content of 31 samples was liquid. One sample had an abnormal value of 695.6% compared to humus soil, but the other 30 samples ranged from 0.1 to 24.4%, with an average of 4.6%. The water content of the 10 samples in the laboratory soil tests ranged from 0.5 to 4.9%, with an average of 1.9%. Therefore, the soil was in a liquid state, but within the liquid limit of 5%. During the experiment, the water content was adjusted by adding water until the material felt viscous to the human senses, and the majority of the water content was in the plastic region. Although some parts were in a liquid state, it was within 5% of the liquid limit, so it is believed that some plasticity remained.

[0062] Next, for the three experimental samples shown in Figure 12, we confirmed that the soil quality had a high measured torque value despite having a low fine particle content. FIG. 15 is a diagram explaining the results of confirming the soil quality for which high rotational torque values ​​were measured in the experiment shown in FIG. 12, where (a) is a diagram showing the three samples of interest in FIG. 12, and (b) is a diagram showing examples of foreign matter (shells, gravel, etc.) contained in the samples. After examining the three samples of interest, it was determined that one sample had soil quality that included "shells," one sample was clayey fill soil mixed with gravel, and one sample was semi-solidified tuffaceous clayey soil that had been hydrated and mixed but was still insufficient in quality.

[0063] There was no insufficient mixing in the 101 clay samples used in this experiment. Furthermore, 17 of the 101 samples were found to contain pebbles, shell fragments, etc., which were removed manually (see Figure 15(b)).

[0064] The following measures are proposed to deal with gravel. (i) Add water to the target soil sample (a partial sample of about 100 g is acceptable) and mix well to determine whether gravel is present. (ii) If gravel is found mixed in, measure the total mass. (iii) Remove the gravel, wash it with water, dry it or wipe it thoroughly with a paper towel, etc., and measure the mass. (iv) Calculate the gravel content using the following formula: Gravel fraction [%] = Gravel mass [g] / Total mass [g] × 100

[0065] Shells whose size can be determined, such as those in the center of Figure 15(b), are problematic and need to be removed. Of the 45 samples from the previous experiment, 3 samples with high rotational torque values ​​were excluded, leaving 42 samples, and 101 samples from this experiment, for a total of 143 samples, for which the experimental data was evaluated. The analysis method was the same as the [Experimental Method] described above.

[0066] (1) Overall trends of torque values ​​and clayey soil As a result of the experiment, characteristics with clear trends were obtained, so a representative graph is shown below. FIG. 16 is a schematic diagram showing the relationship between time and the measured torque value. In Figure 16, the upper graph shows the measurement results for fine particle content Fc = 91.7 [%], viscosity content 61.6 [%], and silt content 30.1 [%], the middle graph shows the measurement results for fine particle content Fc = 51.4 [%], viscosity content 26.6 [%], and silt content 24.8 [%], and the lower graph shows the measurement results for fine particle content Fc = 23.7 [%], viscosity content 7 [%], and silt content 16.4 [%]. From the three graphs, in the 5-60 seconds range, the torque value increases as the fine particle content increases. Also, due to the influence of the high clay content, the range of variation tends to increase. From this, it is considered important to determine the fine particle content using both the rotation speed and the torque value, since as the range of variation in the rotation speed increases, the torque value also increases.

[0067] For example, in the above-described embodiment, the control unit 20 (analysis unit 24) can correct the fine particle content calculated from the average rotational torque measured using the above-described measurement method to reflect variations in rotational speed, thereby calculating the final fine particle content. The correction to reflect variations in rotational speed can be performed by multiplying the fine particle content calculated from the average rotational torque by a correction coefficient determined based on the relationship between the fine particle content calculated from the average rotational torque in actual measurements or simulations and the fine particle content in the actual sample, thereby calculating the final fine particle content. Alternatively, the final fine particle content may be calculated using a function that includes the fine particle content calculated from the average rotational torque and variations in rotational speed as elements. In these cases, the correction can be performed so that the smaller the average rotational torque, the smaller the correction amount based on variations in rotational speed for the fine particle content calculated from the rotational torque.

[0068] (2) Relationship between fine particle content and torque value Next, the relationship between the fine particle content of the sample and the measured rotational torque value was examined. FIG. 17 is a diagram showing the relationship between the fine particle content and the average value of the rotational torque value (average rotational torque), and FIG. 18 is a graph plotting the average value of the average rotational torque measured up to 25 times. That is, Figure 17 shows the average rotational torque value (average rotational torque) from a single measurement of the sample, and Figure 18 shows the average value of the average rotational torque from up to 25 measurements of a sample with the same soil type. The correlation of the fitted curve is the coefficient of determination R 2 = 0.2, which is a weak correlation. Number of tests n = 3419 (number of samples 143), coefficient of determination R 2 ≒0.2, correlation coefficient R = (R 2 ) 1 / 2 =0.4472. The t-value in the t-test is as follows: t-value = R·(n-2) 1 / 2 / (1-R 2 ) 1 / 2 =0.4472×(3417) 1 / 2 / 0.81 / 2 ≒29 The t-values ​​for both the number of tests and the number of samples are large, and it can be evaluated that there is a certain degree of correlation. The approximation curve increases as the fine particle content increases in the 20-40[%] and 70-100[%] ranges, but remains almost constant in the 40-70[%] range.

[0069] (3) Relationship between the uniform content of silt and clay and the standard deviation of torque values ​​divided equally Next, we examined the relationship between the uniform content of silt and clay and the uniform standard deviation of torque values. Figure 19 shows the standard deviation of rotational torque values ​​divided equally. The two figures on the left show values ​​calculated from the individual standard deviations, and the two figures on the right show graphs plotting the average values ​​of up to 25 measurements. In Figure 19, the standard deviation is set at a 95% confidence interval of 2σ, and the following formula is used to show an evenly distributed graph for each silt and clay content. σ (M) (σ (C) )=σ (M+C) M (C) / F σ (M) (σ (C) ): Standard deviation of torque value of silt (clay) M (C) : Silt (clay) content (from soil grain size test) Fc: Fine particle content (from soil particle size test) σ (M+C) =2σFc / 100 σ: standard deviation of torque values, Referring to Figure 19, the approximation curve for the silt fraction is almost constant and the correlation is unclear, while the approximation curve for the clay fraction shows a positive correlation. Therefore, it can be seen that the clay content is more effective as an approximation curve.

[0070] (4) Coefficient of determination R 2 and evaluation of t-value Next, the coefficient of determination R 2 and t-values ​​were evaluated. Coefficient of determination R by approximation curve 2 As shown in Figures 18 and 19, the correlation coefficient is 0.2 excluding the silt content, and is evaluated as having a weak correlation. On the other hand, the sample size is 3419, and the coefficient of determination is R 2 = 0.2, the t-value is 29, which is a statistically significant result. Therefore, it is believed that the approximate curve can be evaluated to a certain extent.

[0071] The present invention can be modified and improved as appropriate within the scope of the effects of the present invention, and is not limited to the above-described embodiment. For example, the soil quality determination device 1 in the above-described embodiment is not limited to the configuration shown in Fig. 1 etc., and can take various forms. For example, the agitation unit 10 and control unit 20 of the soil quality determination device 1 shown in Fig. 1 can be configured as an integrated device. Also, the control unit 20 may be implemented in a server computer, and the control unit 20 may remotely control the agitation unit 10 via a network.

[0072] Furthermore, in the above-described embodiment, a physical quantity such as rotational torque is used to determine the soil type, but other physical quantities may be used as long as they can be used to determine the soil type. In the above-described embodiment, the target rotation speed when stirring the sample can be set to a constant speed, or can be increased or decreased continuously.

[0073] Furthermore, the present invention can be implemented by appropriately combining the above-described embodiments and modifications. The control processes in the above-described embodiments can be performed by either hardware or software. That is, it is sufficient that the soil type determination device 1 is provided with a function that can execute the above-mentioned processing, and the functional and hardware configurations for realizing this function are not limited to the above-mentioned examples.

[0074] The above embodiment shows an example of application of the present invention and does not limit the technical scope of the present invention. In other words, the present invention can be modified in various ways, such as by omission or substitution, without departing from the gist of the present invention, and various embodiments other than the above embodiment can be adopted. The various embodiments and modifications that the present invention can adopt are included in the scope of the invention described in the claims and their equivalents.

[0075] The soil quality determining device 1 configured as above includes the sample container 11, the stirring unit 10, and the control unit 20. The sample container 11 contains a lump sample of soil whose soil quality is to be determined. The stirring unit 10 stirs the sample contained in the sample container 11 . The control unit 20 controls the agitation unit 10 based on control parameters for the agitation unit 10, and obtains a response of the sample to the agitation based on the control parameters. The control unit 20 determines the soil type of the sample based on the sample's response to the agitation. This type of processing makes it possible to judge soil quality based on data that is close to the feel (touch, etc.) that a person would have when making the judgment. Therefore, a more accurate and simple soil quality determination technique can be realized.

[0076] The control unit 20 determines the fines content of the sample based on the sample's response to agitation. This allows the fine particle content of the sample to be determined based on data that reflects the physical properties (viscosity, etc.) of the sample.

[0077] The control unit 20 determines the fines content of the sample based on the magnitude of the average rotational torque in the sample's response to agitation. This makes it possible to determine the fine particle content of a sample based on force information (torque) similar to the feel of a person touching a sample with their hand.

[0078] The control unit 20 determines the clay and silt content in the sample. This makes it possible to objectively determine the clay content and silt content, which are difficult to determine visually.

[0079] The control unit 20 determines the silt content in the sample from the equal division of the standard deviation of the torque values ​​measured for clay and silt in the sample based on the relationship between the equal division of the standard deviation of the torque values ​​measured for clay and silt and the equal division of the silt content. This allows the silt content in the sample to be determined based on relatively reliable data.

[0080] The control unit 20 determines the clay content of the sample by subtracting the silt content of the sample from the fines content of the sample. This allows the clay content to be determined with higher accuracy than if the clay content were determined directly.

[0081] The control unit 20 sets the rotation speed of the stirring unit 10 as a target value, controls the output of a rotation torque to maintain the target value, and detects the force acting on the stirring unit 10 from the sample in accordance with the rotation torque. This makes it possible to obtain the reaction force from the sample based on the control parameters for rotating the sample at a predetermined rotation speed, and determine the soil type.

[0082] The control unit 20 corrects the fine particle content based on variations in the rotation speed during stirring. This allows the fine particle content calculated from the average rotational torque to be corrected so as to reflect variations in rotational speed.

[0083] The control unit 20 corrects the fine particle content rate so that the amount of correction based on the variation in rotation speed becomes smaller as the average rotation torque becomes smaller. This allows for the tendency for the rotational speed to vary more as the average rotational torque increases, and when the average rotational torque is small, the correction amount for the fine particle content calculated from the average rotational torque can be reduced. [Explanation of symbols]

[0084] 1 soil quality determination device, 10 stirring unit, 11 sample container, 12, 13 fixing member, 14 drive motor, 14a rotating rod, 14b blade, 20 control unit, 21 position data acquisition unit, 22 drive control unit, 23 command value output unit, 24 analysis unit, 800 information processing device, 811 processor, 812 ROM, 813 RAM, 814 bus, 815 input unit, 816 output unit, 817 memory unit, 818 communication unit, 819 drive, 820 imaging unit, 831 removable media, S controlled system, FT functional force-velocity allocation conversion block, FC ideal force source block, PC ideal velocity (position) source block, IFT inverse conversion block

Claims

1. a container for containing a sample of soil in the form of a lump, the sample being the object of soil quality assessment; a stirring means for stirring the sample contained in the container; a control means for controlling the stirring means based on a control parameter for the stirring means, and for obtaining a response of the sample to the stirring based on the control parameter; determining means for determining the soil quality of the sample based on the response of the sample to the agitation; A soil quality determination device comprising:

2. 2. The soil quality determination device according to claim 1, wherein the determining means determines the fine particle content of the sample based on the response of the sample to the stirring.

3. 3. The soil quality determination device according to claim 1, wherein the determining means determines the fine particle content of the sample based on the magnitude of an average rotational torque in the response of the sample to the stirring.

4. 3. The soil quality determining device according to claim 1, wherein the determining means determines the clay content and the silt content in the sample.

5. The soil quality determination device described in claim 1 or 2, characterized in that the determination means determines the silt content in the sample from the equal division of the standard deviation of the torque values ​​measured for clay and silt in the sample, based on the relationship between the equal division of the standard deviation of the torque values ​​measured for clay and silt and the equal content of the silt.

6. 6. The soil quality determination device according to claim 5, wherein the determining means determines the clay content of the sample by excluding the silt content of the sample from the fine particle content of the sample.

7. The soil quality determination device according to claim 1 or 2, characterized in that the control means sets the rotational speed of the stirring means to a target value, controls the rotational torque to maintain the target value, and detects the force acting from the sample on the stirring means in accordance with the rotational torque.

8. 4. The soil quality determination device according to claim 3, wherein the determination means corrects the fine particle content based on variations in rotation speed during the stirring.

9. 9. The soil quality determination device according to claim 8, wherein the determination means corrects the fine particle content so that the smaller the average rotational torque, the smaller the amount of correction based on the variation in rotational speed.

10. A soil quality determination method for determining soil quality, comprising: a storing step of storing a sample of soil in a lump form, the sample being the object of soil quality determination, in a storage container; a stirring step of stirring the sample contained in the container by a stirring means; a control step of controlling the stirring means based on a control parameter for the stirring means and acquiring a response of the sample to the stirring based on the control parameter; determining the soil quality of the sample based on the sample's response to the agitation; A soil quality determination method comprising:

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