Soil type determination device and soil type 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 type determination device and a soil type determination method. [Background technology]

[0002] Traditionally, boring surveys have been conducted to determine soil type. In soil type determination using boring surveys, the soil classification is determined by human judgment based on visual and tactile observations of the soil. In determining these soil classifications, while the particle sizes of gravel and sand can be visually distinguished, the particle sizes of clay and silt are finer and therefore difficult to distinguish visually. Furthermore, Patent Document 1 describes a technique for determining soil type from images of the soil's state before and after vibration. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-066613 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, the technology described in Patent Document 1 requires large-scale equipment such as a device for vibrating the soil and a device for imaging the soil. Furthermore, the technology described in Patent Document 1 determines soil type using criteria different from those used for determining soil classification by human senses, which may result in discrepancies with the results obtained by skilled workers.

[0005] The objective of this invention is to realize a soil type determination technology that is more accurate and simpler. [Means for solving the problem]

[0006] To achieve the above objective, a soil type determination device according to one aspect of the present invention is: A container for containing a sample of soil to be judged in a块状 form, Stirring means for stirring the sample contained in the container, Control means for controlling the stirring means based on control parameters for the stirring means and for obtaining the response of the sample to the stirring based on the control parameters, Judgment means for judging the soil quality of the sample based on the response of the sample to the stirring, characterized by comprising.

Advantages of the Invention

[0007] According to the present invention, a more accurate and simple soil quality judgment technology can be realized.

Brief Description of the Drawings

[0008] [Figure 1] It is a schematic diagram showing the configuration of a soil quality judgment device 1 according to an embodiment of the present invention. [Figure 2] It is a conceptual diagram showing an example of soil classification. [Figure 3] It is a schematic diagram showing the hardware configuration of an information processing device 800 constituting a control unit 20. [Figure 4] It is a block diagram showing the functional configuration of a control unit 20. [Figure 5] It is a schematic diagram showing an algorithm for position and force control used in a control unit 20. [Figure 6] It is a flowchart showing the flow of a soil quality judgment process executed by a soil quality judgment device 1. [Figure 7] It is a schematic diagram showing an example of a state where a sample is installed in a sample container 11. [Figure 8] It is a schematic diagram showing an example of a state where fixing members 12, 13 and a driving motor 14 are installed in a sample container 11. [Figure 9] It is a diagram showing a state where a sample is being stirred. [Figure 10]This is a schematic diagram showing the relationship between time and measured torque values. [Figure 11] This is a schematic diagram showing the relationship between time and the rotational speed of the drive motor 14. [Figure 12] This figure shows the relationship between the fine particle content and the average value of the rotational torque (average rotational torque). [Figure 13] This figure shows the relationship between the uniform clay content and the uniform distribution of the standard deviation of the rotational torque value. [Figure 14] This figure shows the relationship between the uniform silt content and the uniform distribution of the standard deviation of the rotational torque value. [Figure 15] Figure 12 is a diagram illustrating the results of the experiment in which high rotational torque values ​​were measured for the soil type. [Figure 16] This is a schematic diagram showing the relationship between time and measured torque values. [Figure 17] This figure shows the relationship between the fine particle content and the average value of the rotational torque (average rotational torque). [Figure 18] This graph plots the average value of the average rotational torque measured up to 25 times. [Figure 19] This figure shows the standard deviation of rotational torque values ​​distributed evenly. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. [Basic Concepts] This invention measures the response (physical quantities such as force, position, and velocity) that a stirring member receives from a sample (for example, a ball-shaped soil mass) during stirring, thereby determining the soil type. At this time, stirring is performed using position and force control technology used for transmitting force and tactile sensation, and the response from the sample (physical quantities such as rotational torque and rotational velocity) is measured using various data (control parameters) used for control during the stirring process. As for position and force control technology, the technology described in International Publication No. 2015 / 041046 or International Publication No. 2005 / 109139, which are applications filed by some of the applicants of this application, can be used. Then, based on the measurement results taken during mixing, the soil composition of the sample (such as the content of fine-grained clay and silt) is determined. The criteria used for this determination are generated based on known soil composition data. Therefore, it becomes possible to determine soil type based on data that closely resembles the tactile sensation (such as touch) that a human would use to make a judgment. Therefore, it becomes possible to realize a soil type determination technology that is more accurate and simpler. Specific embodiments of the present invention will be described below.

[0010] [Configuration of the soil type determination device] Figure 1 is a schematic diagram showing the configuration of a soil type determination device 1 according to one embodiment of the present invention. As shown in Figure 1, the soil type determination device 1 comprises a stirring unit 10 (stirring means) and a control unit (control means, determination means) 20, and the stirring unit 10 and the control unit 20 are configured to communicate with each other via a wired or wireless communication network. The stirring unit 10 comprises a sample container (container) 11, fixing members 12 and 13, and a drive motor 14. The sample container 11 is, for example, a glass container (beaker, etc.) and contains the sample (soil mass) to be determined for soil type. In this embodiment, the soil mass of the sample is formed by gradually adding water to the collected soil until it forms a lump, within a range of water content that does not self-destruct. It is desirable that the state of the sample during stirring be visible from the outside, so the sample container 11 is preferably made of a transparent material.

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

[0012] The drive motor 14 is equipped with a rotating rod 14a that rotates to agitate the sample, and agitates the sample inside the sample container 11 through a through hole formed in the fixed member 12. A blade 14b for agitating the sample is installed at the tip of the rotating rod 14a, and as the rotating rod 14a rotates, the blade 14b agitates the sample while breaking up the soil clumps. At this time, the force (reaction force) that the blade 14b receives from the soil clumps of the sample is transmitted to the rotating rod 14a, so the drive torque is controlled by the control unit 20 in order to maintain the rotation speed of the drive motor 14 at the 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 allows independent control of position and force. 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 sample, and sequentially calculates the target rotational torque (rotational torque corresponding to the reaction force from the sample) required for the rotational speed of the blades 14b to reach the target rotational speed, and outputs command values ​​(force command values ​​and position command values) to the drive motor 14.

[0014] Furthermore, the control unit 20 stores the control parameters output when controlling the drive motor 14, and performs processing to determine the soil type of the sample (soil mass) based on the control parameters. In this embodiment, the control unit 20 acquires the rotational torque (physical quantity during sample agitation) when the sample (soil mass) is stirred, and determines the soil type 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. Conventional soil type determination using boring surveys relies on human judgment based on visual and tactile observation of the soil. While the particle sizes of gravel and sand can be distinguished visually, the particle sizes of clay and silt are finer and therefore difficult to distinguish visually. Therefore, when distinguishing between clay and silt, the subdivision is mainly based on the feel of the viscosity, as shown in Figure 2, and in addition, the amount of sand present is taken into consideration.

[0016] In conventional soil type determination using boring surveys, even when humans make the determination, the distinction between clay and silt is not always accurate, resulting in inconsistencies depending on the determination body. Furthermore, with the super-aging society progressing further and a large number of elderly workers expected to leave their jobs, labor shortages are also a concern. Therefore, efforts are being made to realize technologies that can perform tasks on behalf of humans, at least as well as humans, by using robots and AI (Artificial Intelligence) to support human judgment. In other words, it will become increasingly important to improve quality by objectively transferring the skills currently performed by humans as information and by converting tacit knowledge into explicit knowledge, thereby achieving automation and autonomy of technology.

[0017] The position and force control technology (so-called real haptics technology) applied in this embodiment is a force-tactile transmission technology capable of controlling and measuring forces to transmit sensations from an object being touched. This invention aims to standardize judgments currently made by humans based on tactile sensation into a judgment method based on objective criteria by using position and force control technology (real haptics technology). Because position and force control technology (real haptics technology) can quantify tactile sensations, it is possible to acquire physical properties that reflect the viscosity state and perform soil type judgments with higher accuracy. Furthermore, since soil type can be determined by agitating the collected sample, soil type can be determined with simple equipment.

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

[0019] Figure 3 is a schematic diagram showing the hardware configuration of the information processing device 800 that constitutes the control unit 20. As shown in Figure 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 storage unit 817, a communication unit 818, a drive 819, and an imaging unit 820.

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

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

[0022] The input unit 815 consists of various buttons, a keyboard, or a pointing device, and inputs various types of information according to the instructions and operations. The output unit 816 consists of a display, speakers, etc., and outputs images and sound. The memory unit 817 consists of a hard disk or DRAM (Dynamic Random Access Memory), 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] A removable media 831, consisting of a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, is appropriately mounted in the drive 819. Programs read from the removable media 831 by the drive 819 are installed in the storage unit 817 as needed. The imaging unit 820 is composed of an imaging device equipped with a lens and an image sensor, and captures a digital image of the subject.

[0024] It is also possible to omit the imaging unit 820 in the information processing device 800. Furthermore, it is possible to configure the information processing device 800 to include a touch panel by configuring the input unit 815 with a touch sensor and placing it on top of the display of the output unit 816.

[0025] [Functional configuration] Next, the functional configuration of the control unit 20 will be described. Figure 4 is a block diagram showing the functional configuration of the control unit 20. As shown in Figure 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 axis of the drive motor 14. The position of the rotation axis 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] The drive control unit 22 calculates control command values ​​(command values ​​that eliminate the error between the target rotation speed and the current rotation speed, and 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 target rotation torque, based on the position (angular position) data of the rotation shaft of the drive motor 14 acquired by the position data acquisition unit 21. For example, the drive control unit 22 calculates the value of the drive current of the drive motor 14 (current command value) as a control command value. The drive control unit 22 calculates the current rotation speed and rotation torque from the acceleration dimension data obtained by taking the second derivative of the position of the rotation shaft of the drive motor 14 acquired by the position data acquisition unit 21, and uses this data to calculate the control command values. The data acquired and the command values ​​calculated by the drive control unit 22 to control the drive motor 14 are included in the "control parameters" in this embodiment. The command value output unit 23 outputs the control parameter (in this case, the 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 rotational position and target rotational torque.

[0027] The analysis unit 24 calculates physical quantities during sample stirring based on time-series data used to control the drive motor 14. The physical quantities calculated at this time correspond to the measurement results (response from the sample) measured during sample stirring. In this embodiment, for example, the average value of the rotational torque (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 rotation axis of the drive motor 14 acquired by the position data acquisition unit 21, as well as data on the target rotation position and target rotational torque (reference value), as time-series data, and calculates the average value of the rotational torque (average rotational torque) during sample stirring. Alternatively, instead of the position (angular position) of the rotation axis of the drive motor 14 acquired by the position data acquisition unit 21, the current rotational speed and rotational torque calculated from acceleration dimension data obtained by taking the second derivative of the rotation axis position may be used.

[0028] At this time, the analysis unit 24 excludes data that is to be excluded from the rotational torque data of the drive motor 14 and calculates the average value of the rotational torque. The data to be excluded is data that is presumed not to properly represent the physical quantity of the sample (response from the sample) during stirring. For example, data from a predetermined time at the beginning of stirring (e.g., 5 seconds), data in which the rotational torque continues to rise abnormally (above a set threshold) and does not converge, and data in which the rotational torque suddenly starts to rise (at a rate of change above a set threshold) during stirring can be excluded. In this embodiment, conditions for excluding data from the data to be used (exclusion conditions) are set in advance, and the analysis unit 24 performs the analysis after excluding the rotational torque data of the drive motor 14 based on the exclusion conditions. The threshold used to exclude the 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 a ratio of rotational torque values ​​that are judged to be relatively excessive or insufficient in the measurement results (data group) of a single sample (e.g., "30% or more greater than the average value").

[0029] Furthermore, the analysis unit 24 determines the soil type of the sample based on the calculated physical quantity (average rotational torque). In this embodiment, the analysis unit 24 determines that for samples in a predetermined range (for example, 80% or more) with a high fine-grained content Fc (clay and silt content), the larger the average rotational torque when the sample is stirred, the higher the fine-grained content. Also, when distinguishing between clay content and silt content, the analysis unit 24 calculates the clay content by subtracting the silt content from the fine-grained 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 value in a single measurement of clay and silt equally, and then examining the relationship between this equally divided standard deviation and the uniform silt content (a relationship derived based on known soil types).

[0030] [Algorithms for position and force control] Next, the position and force control algorithms used in the control unit 20 will be described. As described above, this embodiment can utilize the techniques described in International Publication No. 2015 / 041046 or International Publication No. 2005 / 109139, but here we will explain the application of the algorithm described in International Publication No. 2015 / 041046. Figure 5 is a schematic diagram showing the position and force control algorithms used in the control unit 20. As shown in Figure 5, the position and force control algorithm used in the control unit 20 is expressed as a control law that includes the controlled system S, a function-specific force / velocity assignment 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 operated by an actuator, and the actuator is controlled based on acceleration, etc. In this embodiment, the controlled system S is composed of a drive motor 14.

[0032] The Functional Force / Velocity Assignment Conversion Block FT is a block that defines the conversion of control energy to the velocity (position) and force domains set according to the function of the controlled system S. Specifically, the Functional Force / Velocity Assignment Conversion Block FT defines a coordinate transformation that takes a reference value (reference value) for the function of the controlled system S and the current position of the actuator (drive motor 14) as inputs. This coordinate transformation generally converts an input vector with the reference value and current velocity (position) as elements into an output vector consisting of velocity (position) for calculating the control target value of velocity (position), and also converts an input vector with the reference value and current force as elements into an output vector consisting of force for calculating the control target value of force. Specifically, the coordinate transformation in the Functional Force / Velocity Assignment Conversion Block FT is expressed in general terms as shown in the following equations (1) and (2).

[0033]

number

[0034] However, in equation (1), x'1~x' n (where n is an integer greater than or equal to 1) is the velocity vector used to derive the velocity state value, and x' a ~x' m (m is an integer greater than or equal to 1) 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 representing the function. Also, in equation (2), f1~f n (where n is an integer greater than or equal to 1) is the force vector used to derive the force state value, and f a ~f m (where m is an integer greater than or equal to 1) is a vector whose elements are the reference value and the 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 function-specific force / velocity assignment conversion block FT according to the function to be implemented, various actions can be realized, and actions involving scaling can be reproduced. In other words, the basic principle of this invention is that, in the function-specific force / velocity assignment conversion block FT, the variables of an individual actuator (variables in real space) are "converted" into a group of system-wide variables (variables in virtual space) that represent the function to be realized, and control energy is assigned to the control energy of velocity (position) and the control energy of force. Therefore, compared to the case where control is performed using the variables of an individual actuator (variables in real space), it is possible to independently assign the control energy of velocity (position) and the control energy of force.

[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 Assignment Conversion 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 Assignment Conversion 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, the target value can be set to zero, or when scaling can be set to a value that is enlarged or reduced in information indicating the function to be reproduced.

[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 Assignment Conversion 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 Assignment Conversion Block FT. This target value is set as a fixed or variable value depending on the function to be realized. For example, when realizing a function similar to the function indicated by the reference value, the target value can be set to zero, or when scaling can be performed, a value that is an enlarged or reduced version of the information indicating the function to be reproduced can be set.

[0037] The inverse transformer block IFT is a block that converts values ​​in the velocity (position) and force domains into values ​​in the input domain to the controlled system S (e.g., voltage value or current value). Based on these fundamental principles, when position information of the actuator of the controlled system S is input to the functional force-velocity assignment conversion block FT, the functional force-velocity assignment conversion block FT applies control laws for the position and force domains corresponding 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 control energy is distributed to the force and velocity (position) respectively.

[0038] The calculation results from 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. These calculation results are then used as input values ​​for the actuator in the inverse transform block IFT and input to the controlled system S. As a result, the actuators of the controlled system S perform actions according to the functions defined by the function-specific force-velocity assignment conversion block FT, thereby achieving the desired operation of the system.

[0039] By having the above configuration, the soil type determination device 1 according to this embodiment can determine the soil type contained in the sample (such as the content of fine-grained material consisting of clay and silt) based on the measurement results (physical quantities during sample agitation) measured during sample agitation. The measurement results measured during sample agitation represent the tactile sensation provided by the sample. Therefore, it becomes possible to determine soil type based on data that closely resembles the tactile sensation (such as touch) that a human would use to make a judgment. Furthermore, since the soil type can be determined by agitating the collected sample, the soil type can be determined using a simple device.

[0040] [Operation] Next, we will explain the operation of the soil type determination device 1. Prior to the soil type determination device 1 performing the processing (soil type determination processing) for determining the soil type of the sample, the soil clods of the sample, which have been compacted into balls, are 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. By compacting the samples into balls, variations in the initial state are eliminated, allowing for more objective measurement of the samples. Specifically, since the samples being determined here are mainly composed of clay and silt, they become ball-shaped when a certain amount of water is added, and they cannot maintain their shape (i.e., they self-destruct) when too much water is added. Therefore, compacting them into balls allows for an appropriate initial state.

[0041] The sample container 11 is then fixed in place by the fixing members 12 and 13. These preparation steps can be performed manually by workers, but they may also be automated using robots or other devices designed for performing the preparation steps. Next, the soil type is determined by the soil type determination device 1.

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

[0043] In step S3, the position data acquisition unit 21 acquires data on the position (angular position) of the rotation axis of the drive motor 14. In step S4, the drive control unit 22 calculates a control command value (a current command value that eliminates the error between the target rotation speed and the current rotation speed, and 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, 1 minute) has elapsed for stirring the sample. If the set time for stirring the sample (for example, 1 minute) has not elapsed, the result is determined to be NO in step S5, and the process proceeds to step S3. On the other hand, if the set time for stirring the sample (for example, 1 minute) has elapsed, the result in step S5 is determined to be 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 stirring based on the time-series data used to control the drive motor 14, and determines the soil type of the sample based on the calculated average rotational torque. As described above, the physical quantity (average rotational torque) calculated at this time corresponds to the measurement result (response from the sample) measured during sample stirring. In this embodiment, the analysis unit 24 determines that for samples in a predetermined range (for example, 80% or more) with a high fine-grained content Fc (clay and silt content), the larger the average rotational torque when the sample is stirred, the higher the fine-grained content. The analysis unit 24 also estimates the silt content from the relationship between the uniform distribution of the standard deviation of the measured torque values ​​for clay and silt and the uniform content of silt (a relationship derived based on known soil types), and calculates the clay content by subtracting the silt content from the fine-grained content, using the silt content as a reference. In step S7, the analysis unit 24 outputs (stores or displays, etc.) the result of determining the soil type of the sample. After step S7, the soil type determination process is completed.

[0046] This processing method makes it possible to determine soil type based on data that closely resembles the tactile sensation (such as feel) that a human would use to make a judgment. Furthermore, since soil type can be determined by agitating the collected sample, it is possible to determine soil type with simple equipment. Therefore, it becomes possible to realize a soil type determination technology that is more accurate and simpler.

[0047] [Verification of effectiveness] The following describes the results of an experiment conducted to verify the effectiveness of a soil type determination method using the soil type determination device 1 according to this embodiment. [Experimental Method] Figure 7 is a schematic diagram showing an example of a sample being placed in the sample container 11. Figure 8 is a schematic diagram showing an example of a sample container 11 with the fixing members 12 and 13 and the drive motor 14 installed. Figure 9 shows the sample after it has been stirred. The experimental procedure will be explained below, with reference to Figures 7 to 9 as appropriate.

[0048] (1) Two ball-shaped samples (cloves of clay) 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 samples was adjusted based on the height so that the size of the sample balls reached the top of the stirring blade 14b (see Figure 7). If the sample was larger than the top of the stirring blade 14b, the amount of sample was reduced or the sample was deformed by hand.

[0049] (2) The fixing members 12, 13 and the drive motor 14 are arranged in the sample container 11 with a staggered position between the blades 14b and the samples 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 a jig (bolts and nuts, etc.) (see Figure 8). (4) The control unit 20 is operated to rotate the drive motor 14 at 0.5 [rps] (30 revolutions per minute). (5) Measure the sample for at least one minute, then stop the rotation. (6) Remove the fixing members 12, 13 and the drive motor 14 from the sample container 11 and check the condition of the sample. If the sample is not broken up by the blades 14b, for example, if it is stuck to the blades 14b and being carried around, the stirring process is inappropriate and the data should be discarded.

[0050] [Data Analysis Method] Figure 10 is a schematic diagram showing the relationship between time and measured torque values. Figure 11 is a schematic diagram showing the relationship between time and the rotational speed of the drive motor 14. As shown in Figures 10 and 11, waveform graphs of time and torque value, and waveform graphs of time and rotational speed were generated as representative waveform graphs of the sample measurement results. The torque value waveform graph shown in Figure 10 shows that in all measurements, some torque values ​​become excessively large in the range of 0 to 5 seconds, then gradually decrease or remain almost horizontal.

[0051] In this embodiment, the purpose of measurement is to quantify the tactile sensation of the blade 14b touching the sample. Therefore, data in the 0-5 second range were excluded from processing because the increase in measured values ​​was largely due to the influence of soil pressure at the start of stirring. In addition, although 25 measurements were taken for each sample, some measurement results included data where the rotational torque continued to rise abnormally (above the set threshold) and did not converge, and data where the rotational torque began to rise sharply (above the set threshold) during stirring. These data were also excluded from processing.

[0052] In Figure 11, the rotational speed waveform graph is controlled to match the target rotational speed of 3.14 (=0.5 [rps]). Data analysis revealed that properly measured data generally falls within the range of ±0.25 (2.89~3.39). Samples with errors greater than this and outside the appropriate range were excluded from processing, as it was highly likely that the sample was adhering to the blade 14b and being carried around. As a result, 2 samples were excluded from the 47 samples, and 45 samples were adopted.

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

[0054] (2) Assumptions (i) Comparison of waveform graphs of 47 samples showed a tendency for the rotational torque value to decrease as the sand content increased. From this, it was assumed that the fine particle content Fc[%] is related to the average value of the rotational torque value in a single 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 adopted, 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 the clay content is high and smaller when the silt content is high, compared with the particle size distribution of the soil test. Therefore, in order to numerically exclude the effects of gravel and sand, we decided to equally divide the standard deviation σ(M+C) of the rotational torque values ​​for clay and silt in a single measurement from the fine-grain content Fc[%]. σ(M+C)=2·σ·Fc / 100

[0055] Furthermore, in order to distinguish between the clay content C[%] and the silt content M[%], a uniform ratio was adopted by dividing the clay content C[%] and silt content M[%] by the fine-grain content Fc[%]. The standard deviation of the torque value of the clay content σ(M) and the standard deviation of the torque value of the silt content σ(C) were obtained by multiplying the uniform ratio of the clay and silt content by the standard deviation of the rotational torque value of the clay and silt content in one measurement σ(M+C). That is, the standard deviation of the torque value of the clay content σ(M) and the standard deviation of the torque value of the silt content σ(C) can be obtained as follows. The standard deviation of the torque value due to the clay content, divided equally, is σ(M) = σ(M+C)·C / Fc[%] The standard deviation of the torque value due to silt, divided equally, is σ(C) = σ(M+C)·M / Fc[%]

[0056] [Comparison results] Based on the indicators mentioned above, a comparison of the soil type of the sample with the measurement data revealed the following results. (1) Relationship between fine particle content and torque value Figure 12 shows the relationship between the fine particle content and the average value of the rotational torque (average rotational torque). As shown in Figure 12, there is variability in a single data point, but there is a correlation between 80% and 100% of the data, where visual inspection makes it difficult to determine the soil type. Therefore, by using a measurement method that reduces data variability, such as measuring the same sample multiple times, it is possible to determine the fine particle content from the average value of the measured torque (average rotational torque), at least in a predetermined range where the fine particle content is high (80% to 100% in the example in Figure 12).

[0057] (2) Relationship between the uniform content of clay and silt and the standard deviation of torque values. Figure 13 shows the relationship between the uniform clay content and the equal distribution of the standard deviation of the rotational torque value. Figure 14 shows the relationship between the uniform silt content and the equal distribution of the standard deviation of the rotational torque value. Referring to Figures 13 and 14, the uniform distribution of silt content results in less variation in torque values ​​relative to the standard deviation of the uniform distribution than the uniform distribution of clay content. Therefore, based on the measurement results, the fine-grain content can be determined, and further, the proportion of silt can be estimated from the relationship between the uniform silt content and the uniform distribution of the standard deviation of the torque value. By subtracting the silt content from the fine-grain content, the clay content can be estimated.

[0058] [Further verification of the effects] Further verification was conducted to confirm the effectiveness of using the soil type determination device 1 according to this embodiment. [Data Analysis Method] In this additional verification, we first measured the water content of cohesive soil samples 1 to 3 times, depending on the number of measurements taken during the experiment. The test method was carried out in accordance with the Japanese Geotechnical Society standard JGS0122-202, "Method for testing soil moisture content using a microwave oven." Moisture content was measured using a microwave oven with a power output of 600W and a heating time of 20 minutes (for organic soils), as specified as a guideline. In addition to soil particle size distribution testing (JIS A 1204), soil water content testing (JIS A 1203) and soil liquid limit / plastic limit testing (JIS A 1205) were performed on the remaining soil samples after the experiment, depending on the amount of sample remaining.

[0059] The clay samples used for the experiment are mixed thoroughly with water to develop viscosity before the experiment is conducted. Of the 101 samples, the most common was 48 samples with a water content of 50.1-100%, followed by 24 samples with a water content of 0-50%, and then 18 samples with a water content of 101-150%, together accounting for about 90%.

[0060] Furthermore, the difference between the moisture content measured using a microwave oven and the moisture content measured in a laboratory soil test was measured. In this case, the moisture content of the laboratory soil test was adjusted using the remaining sample volume, so the test was performed on 76 out of 101 samples. As a result, since 90% of the samples showed a moisture content difference of 10% or less, the microwave-measured moisture content can be considered to be approximately equivalent to the moisture content measured in a laboratory soil test. Liquid and plastic limit tests were performed on the soil according to the remaining sample volume. The consistency of the soil was evaluated at microwave moisture content and laboratory soil test moisture content, excluding the two NP (Non-Plastic) samples.

[0061] As a result, the microwave moisture content of 31 samples was found to be liquid. One sample had an abnormal value of 695.6% relative to humus, but the other 30 samples ranged from 0.1% to 24.4% with an average of 4.6%. The moisture content of the soil samples tested indoors ranged from 0.5% to 4.9% in 10 samples, with an average of 1.9%. Therefore, although the soil is in a liquid state, it is within the liquid limit of 5%. The water content, adjusted by adding water until viscosity was perceived by human senses during the experiment, was mostly within the plastic region. While some areas were in a liquid state, this was within 5% of the liquid limit, suggesting that a plastic state also remained.

[0062] Next, we examined the soil types that showed high torque values ​​despite having a low fine-grained content in the three experimental samples shown in Figure 12. Figure 15 illustrates the results of the soil type verification in the experiment shown in Figure 12, where (a) shows the three samples of interest in Figure 12, and (b) shows examples of foreign matter (seashells, gravel, etc.) contained in the samples. Upon examining the three samples of interest, it was determined that one sample had a soil composition containing seashells, one sample was a clayey soil from a backfill with gravel, and one sample was a semi-consolidated tuffaceous clay soil that, despite being hydrated and mixed, was insufficiently treated.

[0063] None of the 101 clay samples used in this experiment showed any signs of insufficient mixing. Furthermore, based on the feel of the clay during mixing, gravel and shell fragments were detected in 17 of the 101 samples, and these were removed manually (see Figure 15(b)).

[0064] The following methods are proposed as countermeasures against gravel. (i) Add water to the target soil sample (a partial sample of about 100g is also acceptable) and mix it well to determine the presence of gravel. (ii) If gravel is found to be present, the total mass shall be measured. (iii) Take out the gravel, wash it with water, dry it or wipe it thoroughly with a paper towel, and measure its mass. (iv) Determine the gravel portion using the following formula. Gravel content [%] = Mass of gravel [g] / Total mass [g] × 100

[0065] Shells that are large enough to be identified, such as the one in the center of Figure 15(b), are problematic and should be removed. We evaluated experimental data from a total of 143 samples: 42 samples from the previous experiment (excluding 3 samples with high rotational torque values) and 101 samples from the current experiment. The analysis method was the same as described in [Experimental Method] above.

[0066] (1) Torque values ​​and overall trends in cohesive soils The experiment yielded characteristics that clearly showed trends, so a representative graph is shown. Figure 16 is a schematic diagram showing the relationship between time and measured torque values. In Figure 16, the upper graph shows the measurement results for a fine particle content Fc = 91.7[%], viscosity 61.6[%], and silt content 30.1[%], the middle graph shows the measurement results for a fine particle content Fc = 51.4[%], viscosity 26.6[%], and silt content 24.8[%], and the lower graph shows the measurement results for a fine particle content Fc = 23.7[%], viscosity 7[%], and silt content 16.4[%]. From the three graphs, it can be seen that in the 5-60 second interval, the torque value increases as the fine particle content increases. Furthermore, a tendency for the range of variation to widen is observed, likely due to the influence of a higher clay content. Therefore, as the variation range of rotational speed increases, the torque value also increases accordingly. Thus, it is considered important to determine the fine particle content by using both rotational speed and torque value.

[0067] For example, in the above-described embodiment, the control unit 20 (analysis unit 24) can calculate the final fine particle content rate by adding a correction that reflects the variation in the rotation speed to the fine particle content rate calculated from the average rotation torque measured by the above measurement method. As the correction that reflects the variation in the rotation speed, a correction coefficient specified based on the relationship between the fine particle content rate calculated from the average rotation torque in the measured value or simulation value and the fine particle content rate in the actual sample is multiplied by the fine particle content rate calculated from the average rotation torque to calculate the final fine particle content rate. Alternatively, the final fine particle content rate may be calculated by a function that includes the variation in the rotation speed as an element based on the fine particle content rate calculated from the average rotation torque. In these cases, the correction can be performed such that the smaller the average rotation torque, the smaller the correction amount based on the variation in the rotation speed with respect to the fine particle content rate calculated from the rotation torque.

[0068] (2) Relationship between fine particle content rate and torque value Next, the relationship between the fine particle content rate of the sample and the measured rotation torque value was verified. FIG. 17 is a diagram showing the relationship between the fine particle content rate and the average value (average rotation torque) of the rotation torque value, and FIG. 18 is a graph plotting the average value of the average rotation torque measured up to 25 times at maximum. That is, in FIG. 17, the average value (average rotation torque) of the rotation torque value in one measurement of the sample is shown, and FIG. 18 shows the value obtained by averaging the average rotation torque measured up to 25 times for samples of the same soil type. The correlation of the approximate curve is the coefficient of determination R 2 = 0.2, indicating a weak correlation. The number of test times n = 3419 (143 samples), the coefficient of determination R 2 ≈ 0.2, and the correlation coefficient R = (R 2 ) <- 1 / 2 = 0.4472. Also, 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 Both the number of trials and the sample size yielded large t-values, suggesting a certain degree of correlation. The approximation curve increases as the fine particle content increases in the 20-40% and 70-100% ranges, and exhibits a nearly constant shape in the 40-70% range.

[0069] (3) Relationship between the uniform content of silt and clay and the uniform distribution of the standard deviation of the torque value Next, we examined the relationship between the uniform distribution of silt and clay content and the equal distribution of the standard deviation of the torque value. Figure 19 shows the even distribution of the standard deviation of rotational torque values. The two figures on the left show the values ​​calculated from the individual standard deviations, while the two figures on the right show a graph plotting the average value of up to 25 measurements. In Figure 19, the standard deviation is calculated using a 95% confidence interval of 2σ, and the graphs are shown separately for silt and clay content, with equal distribution according to the following formula. σ (M) (σ (C) )=σ (M+C) M (C) / F σ (M) (σ (C) ): Standard deviation of torque value due to silt content (clay content) M (C) : Silt content (clay content) (from soil particle size distribution test) Fc: Fine particle content (from soil particle size distribution test) σ (M+C) =2σFc / 100 σ: Standard deviation of torque value, Referring to Figure 19, the approximation curve for silt content is almost constant, and the correlation is unclear. On the other hand, a positive correlation is observed in the approximation curve for clay content. Therefore, it can be seen that the clay content is a more effective approximation curve.

[0070] (4) Coefficient of determination R 2 and evaluation of the t-value Next, the coefficient of determination R 2 The t-value was also evaluated. R-squared based on the approximation curve 2 As shown in Figures 18 and 19, the value is 0.2 excluding silt, and is evaluated as having a weak correlation. On the other hand, with a sample size of 3419, the coefficient of determination R 2 The t-value obtained with a value of 0.2 is 29, which is a statistically significant result. Therefore, it is considered that a certain degree of evaluation of the approximation curve can be performed.

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

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

[0073] Furthermore, the present invention can be implemented by appropriately combining the above-described embodiments and modifications. The control process in the above-described embodiment can be performed by either hardware or software. In other words, the soil type determination device 1 only needs to be equipped with a function that can perform the above-mentioned processing, and the functional configuration and hardware configuration used to realize this function are not limited to the examples given above.

[0074] The above embodiments are merely examples of how the present invention can be applied and do not limit the technical scope of the present invention. That is, the present invention can be modified in various ways, such as by omitting or substituting, without departing from the spirit of the invention, and various embodiments other than those described above are possible. The various embodiments that the present invention can take and their variations are included within the scope of the invention described in the claims and its equivalents.

[0075] The soil type determination device 1, configured as described above, includes a sample container 11, a stirring unit 10, and a control unit 20. The sample container 11 contains a sample of soil that is to be used to determine its soil type, in the form of a clump. The stirring unit 10 stirs the sample contained in the sample container 11. The control unit 20 controls the stirring unit 10 based on control parameters for the stirring unit 10, and also obtains the sample's response to stirring based on those control parameters. The control unit 20 determines the soil type of the sample based on the sample's response to agitation. This type of processing makes it possible to determine soil type based on data that closely resembles the tactile sensation (such as feel) that a human would use to make a judgment. Therefore, it becomes possible to realize a soil type determination technology that is more accurate and simpler.

[0076] The control unit 20 determines the fine particle content in the sample based on the sample's response to stirring. This allows for the determination of the fine particle content of a sample based on data that reflects the physical properties (viscosity, etc.) of the sample.

[0077] The control unit 20 determines the fine particle content in the sample based on the magnitude of the average rotational torque in the sample's response to stirring. This allows for the determination of the fine particle content of a sample based on force information (torque) similar to the tactile sensation experienced when a person touches the sample by hand.

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

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

[0080] The control unit 20 determines the clay content of the sample by subtracting the silt content from the fine particle content of the sample. This allows for a more accurate determination of clay content than directly determining the clay content.

[0081] The control unit 20 sets the rotational speed of the stirring unit 10 to a target value, controls it to output a rotational torque to maintain that target value, and detects the force acting from the sample on the stirring unit 10 according to the rotational torque. This allows for the acquisition of reaction forces from the sample and the determination of soil properties based on control parameters for rotating the sample at a predetermined rotational speed.

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

[0083] The control unit 20 corrects the fine particle content so that the smaller the average rotational torque, the smaller the correction amount based on the variation in rotational speed. This allows us to reflect the tendency for greater variation in rotational speed as the average rotational torque increases, and to correct the amount of correction for the fine particle content calculated from the average rotational torque to be smaller when the average rotational torque is small. [Explanation of Symbols]

[0084] 1 Soil type determination device, 10 Agitation unit, 11 Sample container, 12,13 Fixing members, 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 Storage unit, 818 Communication unit, 819 Drive, 820 Imaging unit, 831 Removable media, S Control target system, FT Function-specific force / velocity assignment conversion block, FC Ideal force source block, PC Ideal velocity (position) source block, IFT Inverse conversion block

Claims

1. A container for holding a sample of soil, which is formed into a lump, to be used for soil type determination, A stirring means for stirring the sample contained in the container, A control means that controls the stirring means based on control parameters for the stirring means, and acquires the response of the sample to the stirring based on said control parameters, A determination means for determining the soil type of the sample based on the sample's response to the agitation, A soil type determination device characterized by comprising the following features.

2. The soil type determination device according to claim 1, characterized in that the determination means determines the fine particle content in the sample based on the sample's response to the stirring.

3. The soil type determination device according to claim 1 or 2, characterized in that the determination means determines the fine particle content in the sample based on the magnitude of the average rotational torque in the sample's response to the stirring.

4. The soil type determination device according to claim 1 or 2, characterized in that the determination means determines the clay content and silt content in the sample.

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

6. The soil type determination device according to claim 5, characterized in that the determination means determines the clay content of the sample by excluding the silt content of the sample from the fine-grained content of the sample.

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

8. The soil determination device according to claim 3, characterized in that the determination means corrects the fine particle content based on the variation in rotational speed during stirring.

9. The soil type determination device according to claim 8, characterized in that the determination means corrects the fine-grain content such that the amount of correction based on the variation in rotational speed becomes smaller as the average rotational torque decreases.

10. A method for determining soil type, A storage step involves placing a sample of soil, which is to be used to determine the soil type, into a container, A stirring step in which the sample contained in the container is stirred with a stirring means, A control step of controlling the stirring means based on control parameters for the stirring means and obtaining the response of the sample to the stirring based on said control parameters, A determination step in which the soil type of the sample is determined based on the sample's response to the agitation, A soil type determination method characterized by including the following.

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