Self-propelled detector

Abstract

To easily evaluate a compaction state of the whole foundation.SOLUTION: A self-propelled type detector travelling on a predetermined range of a foundation includes: a housing; a plurality of wheels mounted on the housing; a radiation source for irradiating the foundation with radiation rays; a detector for detecting the number of radiation lays reflected on the foundation; a position detection unit for detecting the position of the self-propelled type detector; and a control unit for controlling the wheels so that the self-propelled type detector travels within the predetermined range partitioned into a plurality of regions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a self-propelled detector.

Background Art

[0002] In dam sites, road sites, airport sites, railway sites, residential land development sites, etc., a vibrating roller vehicle is used to apply pressure to soft ground to compact the ground. For the evaluation of the compaction state of the ground, there are the sand replacement method, the water replacement method, the RI (Radio Isotope) method etc., for measuring the wet density, measuring the water content ratio, etc. The sand replacement method and the water replacement method obtain the volume of the excavated hole by excavating the ground and replacing it with sand or water with uniform particle size, and obtain the wet density by dividing this by the volume obtained by finding the mass of the excavated ground. The RI method obtains the wet density of the soil with gamma rays transmitted from a radiation source, obtains the water content with neutron rays, and obtains the dry density and the water content ratio from these. The water content ratio of the ground is the ratio of the mass of the water contained in the ground to the mass of the ground when the soil of the ground is dry.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the sand replacement method and the water replacement method are destructive tests, it is difficult to measure at many points throughout the compacted ground area. The RI method is a non-destructive test, but in order to measure at many points throughout the compacted ground area, it is required to move the measuring device for each measurement, which is laborious and time-consuming.

[0005] The present invention aims to easily evaluate the overall compaction state of the ground. [Means for solving the problem]

[0006] To solve the above problems, the following measures will be taken.

[0007] That is, the first aspect is, A self-propelled detector that travels across a predetermined area of ​​the ground, The casing and Multiple wheels attached to the housing, A radiation source that irradiates the ground, A detector for detecting the number of radiation particles reflected by the ground, A position detection unit for detecting the position of the self-propelled detector, The self-propelled detector includes a control unit that controls the wheels to travel within a predetermined range divided into multiple regions, It shall be a self-propelled detector equipped with the following features. [Effects of the Invention]

[0008] The present invention aims to easily evaluate the overall compaction state of the ground. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows an example of the configuration of the self-propelled detector according to this embodiment. [Figure 2] Figure 2 shows an example of the configuration of the self-propelled detector according to this embodiment. [Figure 3] Figure 3 shows an example where the ground height at the position of wheel 106 is different from the ground height at the position of auxiliary wheel 112. [Figure 4] Figure 4 shows an example where the ground height at the position of wheel 106 is different from the ground height at the position of auxiliary wheel 112. [Figure 5] Figure 5 shows the area of ​​compacted ground over which the self-propelled detector 100 travels, and an example of the self-propelled detector 100. [Figure 6] FIG. 6 is a diagram showing the relationship between the number of measurement points per region and the variation in water content ratio. [Figure 7] FIG. 7 is a diagram showing an example of the distance dependence of the calculated water content ratio. [Figure 8] FIG. 8 is a diagram showing Modification Example 1 of the self-propelled detector 100. [Figure 9] FIG. 9 is a diagram showing the range of the compacted ground on which the self-propelled detector 100 travels and an example of the self-propelled detector 100. [Figure 10] FIG. 10 is a diagram showing Modification Example 2 of the self-propelled detector 100. [Figure 11] FIG. 11 is a diagram showing Modification Example 2 of the self-propelled detector 100.

MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. The configurations of the embodiments are examples, and the configuration of the invention is not limited to the specific configurations of the disclosed embodiments. In carrying out the invention, specific configurations according to the embodiments may be appropriately adopted.

[0011] 〔Embodiment 1〕 (Configuration Example) Figures 1 and 2 show an example of the configuration of the self-propelled detector of this embodiment. The self-propelled detector 100 of this embodiment travels over compacted ground and measures the water content, etc., to evaluate the compaction state of the ground at various points. Figure 1 is a side view of the self-propelled detector 100. Figure 2 is a top view of the self-propelled detector 100. The self-propelled detector 100 includes an upper frame 102, a column section 104 extending downward from the frame, wheels 106, and an axle 108 that serves as the axis of the wheels 106. The self-propelled detector 100 further includes a lower frame 110, auxiliary wheels 112, an axle 114 that serves as the axis of the auxiliary wheels 112, and a band (elastic traction member) 116 that suspends (tows) the lower frame 110 from the upper frame 102. The self-propelled detector 100 further includes a radiation source 118, a radiation detector 120, a laser measuring instrument 122, a position detection unit 124, and a control unit 126. Here, in Figure 1, the direction from left to right is the x-direction, the direction from the front to the back of the paper is the y-direction, and the direction from bottom to top is the z-direction. Similarly, in Figure 2, the direction from left to right is the x-direction, the direction from bottom to top is the y-direction, and the direction from the back to the front of the paper is the z-direction. The ground on which the self-propelled detector 100 travels is a plane that is approximately parallel to the xy-plane. Here, the self-propelled detector 100 is described as traveling on compacted ground to measure the water content, etc., but the self-propelled detector 100 is not limited to traveling on compacted ground.

[0012] The upper frame 102 is a rectangular frame that forms the main part of the self-propelled detector 100. The upper frame 102 has a shape in which, for example, a rectangular flat plate has a smaller rectangle cut out from the inside of the original rectangular plate. That is, the upper frame 102 has a shape in which, for example, a rectangular flat plate has a rectangular opening inside. The upper frame 102 is made of a rigid material such as metal, resin, or wood. The position detection unit 124, the control unit 126, etc. are mounted on the upper frame 102. In addition, a plurality of column sections 104 are connected to the upper frame 102.

[0013] The column part 104 is a connecting part that connects the upper frame 102 and the axle 108 of the wheel 106. The column part 104 is a rod-shaped member that extends downward (in the z-axis direction) from each corner of the upper frame 102. In the examples of FIGS. 1 and 2, the column part 104 is provided at each of the four corners of the upper frame 102. The column part 104 is made of a rigid body such as metal, resin, or wood. The column 104 may be integrally formed with the upper frame 102. One end of each column part 104 is connected to the upper frame 102. The other end of each column part 104 is connected to the axle 108 of the wheel 106. The column part 104 only needs to be able to connect the upper frame 102 and the axle 108, and is not limited to a rod-shaped member.

[0014] The shapes of the upper frame 102 and the column part 104 are not limited to those described here, and may be any housing or the like that can support the wheel 106 or the like.

[0015] The wheel 106 causes the self-propelled detector 100 to travel by rotating around the axle 108 that serves as the axis of the wheel 106. The wheel 106 is connected to the column part 104 via the axle 108. The wheel 106 is, for example, a rubber tire. The surface of the wheel 106 may be provided with irregularities so that obstacles can be easily overcome. In the example of FIG. 2, the number of wheels 106 is four, but the number of wheels 106 is not limited to four.

[0016] The axle 108 is the axis of the wheel 106. A driving motor or the like for rotating the wheel 106 (not shown) is connected to the axle 108. When the power of the driving motor is transmitted to the wheel via the axle 108, the wheel 106 rotates. A steering motor for changing the direction of the wheel 106 (not shown) may be connected to the axle 108. When the power of the steering motor is transmitted to the axle 108, the direction of the wheel 106 changes. The driving motor and the steering motor do not have to be connected to all the axles 108, and may be connected to some of the axles 108. The combination of the wheel 106 and the axle 108 is simply referred to as a wheel.

[0017] The lower frame 110 is a rectangular frame on which the radiation source 118, detector 120, laser measuring instrument 122, etc. are mounted. The lower frame 110 has a shape in which, for example, a rectangular flat plate has a smaller rectangle cut out from the inside. That is, the lower frame 110 has a shape in which, for example, a rectangular flat plate has a rectangular opening inside. The size of the lower frame 110 is smaller than the size of the upper frame 102. The lower frame 110 is suspended (pulled) from the upper frame 102 by a band 116. The lower frame 110 is made of a rigid material such as metal, resin, or wood.

[0018] The auxiliary wheels 112 are wheels connected to the lower frame 110 via an axle 114. The diameter of the auxiliary wheels 112 is smaller than the diameter of the wheels 106. As the self-propelled detector 100 moves, the auxiliary wheels 112 rotate around the axle 114, which is the axis of the auxiliary wheels 112, and move together with the lower frame 110. The wheels 106 are, for example, rubber tires. In the example in Figure 2, there are four auxiliary wheels 112, but the number of auxiliary wheels 112 is not limited to four.

[0019] Axle 114 is the axle of the auxiliary wheel 112. Unlike the axle 108 of the wheel 106, no drive motor or other components are connected to the axle 114 of the auxiliary wheel 112. The auxiliary wheel 112 and axle 114 together are simply called the auxiliary wheel.

[0020] The band 116 is a strip-shaped or string-shaped member that suspends (triggers) the lower frame 110 from the upper frame 102. In the example shown in Figures 1 and 2, four bands 116 attached to the upper frame 102 hang down and are attached to the lower frame 110. The band 116 is an elastic material such as rubber. This allows the distance between the upper frame 102 and the lower frame 110 to be flexibly changed. For example, even if the ground height at the position of the auxiliary wheel 112 differs from the ground height at the position of the wheel 106 due to uneven ground, both the wheel 106 and the auxiliary wheel 112 can make contact with the ground. The number of bands 116 is not limited to four.

[0021] Figures 3 and 4 show examples where the ground height at the position of wheel 106 is different from the ground height at the position of auxiliary wheel 112. In the example in Figure 1, the ground height at the position of wheel 106 is the same as the ground height at the position of auxiliary wheel 112. In the example in Figure 3, the ground height at the position of auxiliary wheel 112 is lower than the ground height at the position of wheel 106. In this case, as the band 116 stretches, the position of the lower frame 110 lowers, and the auxiliary wheel 112 can also touch the ground. In this case, the distance between the upper frame 102 and the lower frame 110 is longer than in the original state (Figure 1). Also, in the example in Figure 4, the ground height at the position of auxiliary wheel 112 is higher than the ground height at the position of wheel 106. In this case, as the band 116 contracts, the position of the lower frame 110 rises, and both wheel 106 and auxiliary wheel 112 can touch the ground. In this case, the distance between the upper frame 102 and the lower frame 110 is shorter than in the original state (Figure 1). By adjusting the position of the lower frame 110 relative to the position of the wheel 106 in accordance with the ground level, the distance between the radiation source 118 and the ground can be kept nearly constant even if the ground is uneven.

[0022] The radiation source 118 is a radiation source (radioactive isotope) that emits radiation (neutrons, gamma rays, etc.) to measure the condition of compacted ground. The radiation source 118 is placed on the lower frame 110 and emits radiation from the opening in the lower frame 110 toward the ground. The radiation source 118 emits radiation continuously. The radiation source 118 may include both a neutron-emitting source and a gamma-ray-emitting source.

[0023] Detector 120 is a detector that detects radiation emitted from source 118 and scattered in the ground or subsurface. Detector 120 counts, for example, the number of radiation particles incident on it. Detector 120 is mounted on lower frame 110. The radiation-detecting portion of detector 120 is directed towards an opening in lower frame 110. Detector 120 detects radiation from the opening in lower frame 110. Detector 120 is a detector tuned to the radiation emitted by source 118. For example, if source 118 is a neutron-emitting source, detector 120 is a neutron-detecting detector. If source 118 is a gamma-ray-emitting source, detector 120 is a gamma-ray-detecting detector. Detector 120 includes a neutron-detecting detector and a gamma-ray-detecting detector when source 118 emits both neutrons and gamma rays. The number of radiation particles (count value) detected by detector 120 can be converted by known methods into water content or water content ratio (neutron rays) or wet density (gamma rays) at the location of detection in the ground.

[0024] The laser measuring instrument 122 is a measuring instrument that measures the distance between the laser measuring instrument 122 and the ground using a laser. The laser measuring instrument 122 is mounted on the lower frame 110 together with the radiation source 118 and the detector 120. The laser measuring instrument 122 measures the distance between the laser measuring instrument 122 and the ground by irradiating a laser from an opening in the lower frame 110 toward the ground and detecting the laser reflected from the ground. The distance between the laser measuring instrument 122 and the ground corresponds to the distance between the radiation source 118 and the ground, and the distance between the detector 120 and the ground. A distance measuring device other than the laser measuring instrument 122 may be used instead of the laser measuring instrument 122. Multiple laser measuring instruments 122 may be installed on the lower frame 110. When multiple laser measuring instruments 122 are installed, the distance between the laser measuring instrument 122 and the ground is, for example, the average of the distances measured by each laser measuring instrument 122. By using multiple laser measuring instruments 122, the distance between the radiation source 118 and the ground, and the distance between the detector 120 and the ground can be determined more accurately. For example, by placing one laser measuring instrument 122 on each side of the radiation source 118 and detector 120, and averaging the distances measured by the two laser measuring instruments 122, the distance between the radiation source 118 (detector 120) and the ground can be determined more accurately. The laser measuring instrument 122 is an example of a distance measuring instrument. In addition to the radiation source 118, detector 120, and laser measuring instrument 122 mentioned above, the measuring instruments mounted on the lower frame 110 include an electromagnetic densimeter, a surface thermometer, and the like. That's good too.

[0025] The position detection unit 124 detects the position (current position) of the self-propelled detector 100 based on positioning signals transmitted from positioning satellites, which are GNSS (Global Navigation Satellite System) satellites. The position detection unit 124 includes a GNSS antenna that receives radio waves from positioning satellites. The position detection unit 124 detects the position of the self-propelled detector 100 at a preset period. The position detection unit 124 may also detect the position of the self-propelled detector 100 by other methods. A positioning system other than GNSS may be used.

[0026] The control unit 126 controls the operation of the self-propelled detector 100. The control unit 126 controls the travel speed and direction of the self-propelled detector 100 by controlling the drive motor and steering motor connected to the wheels 106. As a result, the self-propelled detector 100 travels autonomously. The control unit 126 makes the self-propelled detector 100 travel along a predetermined travel path at a predetermined travel speed within the area of ​​compacted ground. The control unit 126 acquires the detection results of radiation detected by the detector 120 and calculates the compaction state of the ground. The compaction state of the ground is expressed, for example, by the water content of the ground, the water content ratio of the ground, and the wet density of the ground. The control unit 126 uses the laser measuring instrument 122 to measure the distance from the laser measuring instrument 122 to the ground and acquires the measured distance. The control unit 126 uses the position detection unit 124 to measure the position of the self-propelled detector 100 and acquires the measured position.

[0027] The control unit 126, for example, is a calculation unit such as a CPU (Central Processing Unit) and records information. This is an information processing device equipped with memory units such as RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), and SSD (Solid State Drive), an input / output unit for inputting and outputting information, and a communication unit for communicating with other devices. Information processing devices include dedicated devices such as PCs (Personal Computers), smartphones, mobile phones, and tablet terminals. Alternatively, this can be implemented using a general-purpose computer or an electronic device equipped with a computer. The control unit 126 performs various controls and calculations by having the calculation unit execute a program stored in the memory unit or the like. The control unit 126 may also receive commands related to driving, etc., from other information processing devices, etc., via the communication unit and operate based on those commands.

[0028] The self-propelled detector 100 is equipped with a power supply (battery) not shown. The power supply provides power to the detector 120, laser measuring instrument 122, position detection unit 124, control unit 126, drive motor, steering motor, etc.

[0029] (Example of operation) An example of the operation of the self-propelled detector 100 will be described. The self-propelled detector 100 travels over compacted ground and measures index values ​​(such as water content) for evaluating the compaction state of the ground at each point, the distance to the ground (ground), the position of the self-propelled detector 100, etc.

[0030] Figure 5 shows the area of ​​compacted ground over which the self-propelled detector 100 travels, and an example of the self-propelled detector 100. The compacted ground is pre-divided into a mesh-like area of ​​multiple regions G1, G2, ..., Gn of predetermined size. A region of predetermined size is, for example, a square region with sides of 50 cm. The self-propelled detector 100 is pre-set to travel through each region for a predetermined amount of time or longer. If it is not necessary to evaluate the compaction state of all regions, the self-propelled detector 100 may travel through only some of the regions. The path taken by the self-propelled detector 100 is not particularly limited. The position information of the compacted ground and the position information of each region are pre-stored in the memory of the control unit 126. Lines indicating the boundaries of the regions as shown in Figure 5 do not necessarily have to be drawn on the actual ground. The position information of the multiple regions G1, G2, ..., Gn is pre-stored in the memory of the control unit 126.

[0031] The self-propelled detector 100 travels at a predetermined speed along a pre-set path within the compacted ground area, according to the control of the control unit 126. The self-propelled detector 100 travels, for example, approximately parallel to the boundary lines of each area. The self-propelled detector 100 travels, for example, at a speed of 10 cm per second, passing through one area (50 cm on each side) in 5 seconds.

[0032] The self-propelled detector 100, while moving, counts the number of radiation particles reflected from the ground or subsurface at a predetermined sampling frequency (e.g., 1 Hz) using the detector 120. The radiation detected by the detector 120 is radiation emitted from the source 118 and reflected from the ground or subsurface. The control unit 126 of the self-propelled detector acquires the number of radiation particles (count value) detected by the detector 120. If the sampling frequency is X Hz, for example, the detector 120 counts the number of radiation particles detected by the detector 120 in 1 / X seconds every 1 / X seconds. The count value of the radiation particles may be expressed as a count value per unit time (e.g., 1 second).

[0033] While the self-propelled detector 100 is moving, it measures the distance between the laser measuring instrument 122 and the ground at a predetermined sampling frequency (e.g., 1 Hz) using the laser measuring instrument 122. The laser measuring instrument 122 irradiates a laser towards the ground and detects the laser reflected by the ground. The laser measuring instrument 122 measures the distance between the laser measuring instrument 122 and the ground by, for example, the time difference between the time the laser is irradiated and the time the laser is detected. The distance between the laser measuring instrument 122 and the ground corresponds to the distance between the radiation source 118 and the ground, and the distance between the detector 120 and the ground. The control unit 126 of the self-propelled detector acquires the distance measured by the laser measuring instrument 122.

[0034] While the self-propelled detector 100 is moving, the position detection unit 124 detects the position of the self-propelled detector 100 (current position) at a predetermined sampling frequency (e.g., 1 Hz). The control unit 126 of the self-propelled detector 100 acquires the position of the self-propelled detector 100 detected by the position detection unit 124. The position of the self-propelled detector 100 is expressed, for example, by latitude, longitude, and altitude.

[0035] The sampling frequency in the laser measuring instrument 122 and the position detection unit 124 may be higher than the sampling frequency in the detector 120.

[0036] The control unit 126 of the self-propelled detector 100 stores in the memory unit the count value detected by detector 120, the distance measured by laser measuring instrument 122, and the position of the self-propelled detector 100 detected by position detection unit 124, all of which were detected at the same time, in a corresponding manner. If the sampling frequency of detector 120 is XHz, times with a difference of less than 1 / X seconds may be considered to be the same time. The distance corresponds to the distance between detector 120 and the ground at the position where detector 120 detected radiation. The position corresponds to the position where detector 120 detected radiation. Instead of the count value detected by detector 120, the water content, water content ratio, and wet density of the ground calculated from the count value by a well-known method may be stored in the memory unit. The control unit 126 may transmit the count value detected by detector 120, the distance measured by laser measuring instrument 122, the position of the self-propelled detector 100 detected by position detection unit 124, etc., stored in the memory unit, to other information processing devices via the communication unit. The other information processing device may calculate the water content ratio (wet density) for each region instead of the control unit 126 of the self-propelled detector 100.

[0037] The control unit 126 of the self-propelled detector 100 calculates which region each position of the self-propelled detector 100, stored in the memory unit, belongs to, based on the position of each region within the compacted ground area. The control unit 126 calculates the moisture content (wet density) for each region. For example, the control unit 126 calculates the moisture content (wet density) for each region by calculating the moisture content (wet density) at each position of the self-propelled detector 100 and calculating the average value of the moisture content (wet density) for each region. The control unit 126 stores the calculated moisture content (wet density) for each region in the memory unit. The control unit 126 transmits the moisture content (wet density), etc., of each region stored in the memory unit to other information via the communication unit. It may be transmitted to the information processing device.

[0038] <Number of measurement points> Figure 6 shows the relationship between the number of measurement points per region and the variability of water content. In the graph in Figure 6, the horizontal axis represents the number of measurement points of the detector 120 per region, and the vertical axis represents the variability of water content for each region. Here, each region is a square with sides of 50 cm, and the sampling frequency of the detector 120 is set to 1 Hz. The travel speed of the self-propelled detector 100 is set to 20 cm / s, 14 cm / s, 12 cm / s, 10 cm / s, and 5 cm / s. The self-propelled detector 100 is assumed to travel parallel to the boundary lines of each region. Therefore, the number of measurement points per region is 2.5 points, 3.6 points, 4.2 points, 5 points, and 10 points. The variability of water content is the standard deviation of water content for each region. As shown in the graph in Figure 6, the more measurement points there are per region (the longer the time to detect radiation), the smaller the variability of water content becomes (the more accurate the water content value becomes). Furthermore, when the number of measurement points for the detector 120 per region is 5 or more, the variation in water content becomes almost constant. Therefore, it is desirable to have 5 or more measurement points for the detector 120 per region. The same applies to wet density.

[0039] <Adjustment based on distance> The moisture content calculated using the well-known method assumes that the radiation source and detector are in contact with the ground being measured. As the distance between the radiation source 118 (detector 120) and the ground increases, the number of detected radiation particles decreases. Therefore, the moisture content calculated using the well-known method will be smaller than the actual moisture content. In other words, the calculated moisture content depends on the distance between the detector 120 and the ground. Accordingly, the actual moisture content (a more accurate moisture content) can be obtained by correcting the calculated moisture content using the distance between the detector 120 and the ground.

[0040] Figure 7 shows an example of the distance dependence of the calculated moisture content. In the graph in Figure 7, the horizontal axis represents the distance between the detector 120 (radiation source 118) and the ground, and the vertical axis represents the moisture content calculated based on the radiation count. Here, the number of radiation particles is counted at the detector 120 while varying the distance between the detector 120 (radiation source 118) and the ground in the same ground (area). The calculated moisture content decreases as the distance between the detector 120 and the ground increases. Here, an approximation function is found from the relationship between the distance between the detector 120 and the ground and the calculated moisture content, obtained in the same ground (area). The approximation function can be, for example, a linear function or a quadratic function. Furthermore, the value (moisture content) when the distance is set to 0 in the approximation function is taken as the actual moisture content. In the example in Figure 7, if the approximation function is a quadratic function, the approximation function is y = -0.0105x 2 The result is +0.006x + 3.4383. Here, x is the distance between the detector 120 (radiation source 118) and the ground, and y is the moisture content calculated by a well-known method. Therefore, in the example in Figure 7, the actual moisture content is 3.4383%. In advance, the number of radiation particles in the detector 120 is measured at various distances between the detector 120 (radiation source 118) and the ground at ground with various moisture content values, and an approximate function is obtained for each moisture content. By obtaining an approximate function for each moisture content, the actual moisture content can be determined from the distance between the detector 120 (radiation source 118) and the ground and the calculated moisture content. That is, the distance between the detector 120 (radiation source 118) and the ground can be used as a correction term for the calculated moisture content when determining the actual moisture content. Therefore, even if the distance between the detector 120 (radiation source 118) and the ground changes, the actual moisture content can be determined more accurately. The same applies to the wet density obtained by the gamma ray count.

[0041] (Variation 1) Figure 8 shows a modified example 1 of the self-propelled detector 100. The self-propelled detector 100 in Figure 8 has similarities with the self-propelled detector 100 in Figures 1 and 2. Here, we will omit the explanation of the similarities and mainly explain the differences. In the self-propelled detector 100 in Figures 1 and 2, the number of auxiliary wheels 112 was 4, but in the self-propelled detector 100 in Figure 8, the number of auxiliary wheels 112 is Let's say there are two of them. In the self-propelled detector 100 in Figure 8, the auxiliary wheels 112 are two auxiliary wheels 112 (on the right side of the lower frame 110 in Figure 8) that are on a straight line parallel to the y-axis. A skid portion 130 is provided at the left end of the lower frame 110, extending toward the nearest wheel 106. The skid portion 130 extends from the left end of the lower frame 110 toward the nearest wheel 106 and has a curved shape that is bent upward (in the z direction). The skid portion 130 may also extend from the left end of the lower frame 110 toward the nearest wheel 106 and have a shape that is bent upward (in the z direction). The self-propelled detector 100 can travel smoothly even if the ground is uneven due to the skid portion 130. The skid portion 130 may be integrated with the lower frame 110 to form a single lower frame.

[0042] (Effects and mechanisms of the embodiment) The self-propelled detector 100 autonomously travels along a predetermined route within the compacted ground area, using a housing consisting of an upper frame 102 and column sections 104, wheels 106, axles 108, a drive motor connected to the axles 108, a steering motor, a control unit 126, etc. The self-propelled detector 100 is controlled to travel within the area of ​​compacted ground, which is divided into multiple regions. The self-propelled detector 100 has a radiation source 118, a detector 120, and a laser measuring instrument 122 mounted on a lower frame 110 which has auxiliary wheels 112 suspended from the upper frame 102 of the housing by bands 116. While traveling, the self-propelled detector 100 measures the number of radiation particles irradiated from the radiation source 118 and reflected in the ground, the distance between the detector 120 and the ground, and the position of the self-propelled detector 100. By placing the radiation source 118, etc., on the lower frame 110, which has auxiliary wheels 112 suspended from an elastic band 116, the distance between the radiation source 118, etc. and the ground can be kept more constant than if it were placed on the upper frame 102. By keeping the distance between the radiation source 118, etc. and the ground constant, the moisture content, etc., can be determined more accurately.

[0043] While traveling, the self-propelled detector 100 measures the number of radiation particles, the distance between the detector 120 and the ground, and the position of the self-propelled detector 100 at least once (preferably five times or more) in each region. The self-propelled detector 100 identifies which region it is in based on its position and calculates the compaction state of the ground (moisture content, wet density, etc.) for each region. The evaluated value of the compaction state of the ground can be corrected by the distance between the detector 120 and the ground. By correcting the evaluated value of the compaction state of the ground by the distance between the detector 120 and the ground, the compaction state of the ground can be calculated more accurately. With the self-propelled detector 100, the overall compaction state of the compacted ground can be easily evaluated.

[0044] (others) In the above example, the self-propelled detector 100 travels at a predetermined speed within the compacted ground area. While traveling, the self-propelled detector 100 counts the number of radiation particles reflected from the ground or within the ground using the detector 120 at a predetermined sampling frequency (e.g., 1 Hz). Furthermore, the self-propelled detector 100 calculates the moisture content (wet density) for each area divided into a mesh-like section. However, because the self-propelled detector 100 measures while traveling at a predetermined speed, it calculates the moisture content (wet density) using the results of radiation detection at different locations within each area. When the self-propelled detector 100 detects radiation while moving, it can detect radiation at multiple locations within the area, but detection errors are likely to occur due to factors such as the unstable distance between the detector 120 and the ground. Therefore, for example, if the variation in water content (wet density) at multiple different locations within a region is small, it is desirable for the self-propelled detector 100 to stop at a single point (representative point) within the region and detect radiation for a longer period of time, rather than detecting radiation while the self-propelled detector 100 is moving. Here, we will describe a method in which the self-propelled detector 100 stops at the position of a representative point within each region and detects radiation.

[0045] Figure 9 shows the area of ​​compacted ground over which the self-propelled detector 100 travels, and an example of the self-propelled detector 100. The compacted ground is divided into several areas G1, G of predetermined size. 2. ..., Gn is divided into a mesh-like area. A predetermined area is, for example, a square area with sides of 50 cm. Each area has a center point as a representative point. The representative point of an area does not have to be the center point of the area. Here, the representative point (center point) of an area is, for example, the intersection of the two diagonals of the square area. The self-propelled detector 100 stops at the position of the representative point of each area, performs measurements, and after the measurement is completed, moves to the position of the representative point of another area. When stopping, the self-propelled detector 100 stops at a position where, for example, the detector 120 or the radiation source 118 is closest to the position of the representative point of the area. If it is not necessary to evaluate the compaction state of all areas, the self-propelled detector 100 may travel only to some areas. The path traveled by the self-propelled detector 100 is not particularly limited. The position information of the compacted ground and the position information of each area are stored in advance in the memory of the control unit 126. The actual ground does not necessarily need to have lines indicating the boundaries of the regions or points indicating representative points (center points) as shown in Figure 9. Information on the locations of multiple regions G1, G2, ..., Gn, and the locations of each representative point is stored in advance in the memory unit of the control unit 126.

[0046] The self-propelled detector 100, under the control of the control unit 126, repeatedly travels and stops along a preset path within the compacted ground area. For example, the self-propelled detector 100 may stop for 5 seconds at a representative point in one area, and then move at a speed of 50 cm per second to a representative point in another area (for example, an adjacent area). The stopping time is not limited to 5 seconds and can be changed depending on the required measurement accuracy and measurement time. For example, a longer stopping time is used when higher measurement accuracy is required, and a shorter stopping time is used when a shorter measurement time is required.

[0047] While stationary, the self-propelled detector 100 counts the number of radiation particles reflected from the ground or subsurface at a predetermined sampling frequency (e.g., 1 Hz) using the detector 120. The radiation detected by the detector 120 is radiation emitted from the source 118 and reflected from the ground or subsurface. The control unit 126 of the self-propelled detector acquires the number of radiation particles (count value) detected by the detector 120. If the sampling frequency is X Hz, for example, the detector 120 counts the number of radiation particles detected by the detector 120 every 1 / X seconds. The count value of the radiation particles may be expressed as a count value per unit time (e.g., 1 second). The count value of the radiation particles may also be expressed as a count value per stationary time (e.g., 5 seconds).

[0048] While stationary, the self-propelled detector 100 measures the distance between the laser measuring instrument 122 and the ground at a predetermined sampling frequency (e.g., 1 Hz) using the laser measuring instrument 122. The laser measuring instrument 122 irradiates a laser towards the ground and detects the laser reflected by the ground. The laser measuring instrument 122 measures the distance between the laser measuring instrument 122 and the ground by, for example, the time difference between the time the laser is irradiated and the time the laser is detected. The distance between the laser measuring instrument 122 and the ground corresponds to the distance between the radiation source 118 and the ground, and the distance between the detector 120 and the ground. The control unit 126 of the self-propelled detector acquires the distance measured by the laser measuring instrument 122.

[0049] The self-propelled detector 100 detects its position (current position) at a predetermined sampling frequency (e.g., 1 Hz) using the position detection unit 124 while moving and while stopped. The control unit 126 of the self-propelled detector 100 acquires the position of the self-propelled detector 100 detected by the position detection unit 124. The position of the self-propelled detector 100 is expressed, for example, by latitude, longitude, and altitude.

[0050] The sampling frequencies in the laser measuring instrument 122 and the position detection unit 124 may be higher than the sampling frequency in the detector 120. While the self-propelled detector 100 is moving, the detector 120 may count the number of radiation reflected from the ground or underground, and the laser measuring instrument 122 may measure the distance between the laser measuring instrument 122 and the ground. Furthermore, the self-propelled detector 100 may use the number of radiation counted and measured, and the distance, while moving to calculate the moisture content (wet density). That's fine.

[0051] The control unit 126 of the self-propelled detector 100 calculates the water content ratio (wet density) for each region in the same manner as in the example above.

[0052] Here, since the self-propelled detector 100 does not detect radiation while it is moving, the travel speed of the self-propelled detector 100 can be increased compared to the case where radiation is detected while the self-propelled detector 100 is moving. Also, here, since the self-propelled detector 100 stops at the position of a representative point in each region to detect radiation, the distance between the detector 120 (radiation source 118) and the ground is stable, and the measurement accuracy is improved. Therefore, this method can shorten the time required to detect radiation in order to obtain the same measurement accuracy as when the self-propelled detector 100 is moving. This method is more effective, for example, when the variation in moisture content (wet density) at multiple different locations within the region is small. Also, here, the measurement accuracy of the self-propelled detector 100 can be further improved by increasing the radiation detection time while it is stopped. Also, here, since the self-propelled detector 100 does not detect radiation while it is moving, the overall measurement time can be shortened by increasing the travel speed.

[0053] (Modification 2) Figures 10 and 11 show a modified example 2 of the self-propelled detector 100. The self-propelled detector 100 in Figures 10 and 11 has similarities with the self-propelled detector 100 in Figures 1 and 2. Here, we will omit the explanation of the similarities and mainly explain the differences. In the self-propelled detector 100 in Figures 1 and 2, there were four auxiliary wheels 112, but the self-propelled detector 100 in Figures 10 and 11 does not have auxiliary wheels 112. In this modified example 2 of the self-propelled detector 100, instead of a band 116, the upper frame 102 and the lower frame 110 are connected by four non-elastic rod-shaped support columns 216, such as metal columns. The support columns 216 are rotatably connected to the upper frame 102 and the lower frame 110, and the upper frame 102 and the lower frame 110 form a link mechanism via the support columns 216. Furthermore, the upper frame 102 has a drive unit 201 consisting of a servo motor or actuator. The drive unit 201 has a rotating part that rotates around an axis (y-direction) parallel to the axle 108. One end of the rotating part of the drive unit 201 is connected to a rod-shaped shaft rod 202. In response to the rotation of the rotating part of the drive unit 201, the other end of the shaft rod 202 moves up and down. One end of a rod-shaped connecting rod 203 is connected to the other end of the shaft rod 202, and the other end of the connecting rod 203 is connected to the lower frame 110. Therefore, by operating the rotating part of the drive unit 201, the connecting rod 203 moves, making it possible to move the lower frame 110 up and down relative to the upper frame 102 (ground). In the example in Figure 10, the case where the lower frame 110 is pulled up is shown, and in the example in Figure 11, the case where the lower frame 110 is lowered is shown. A string-like member may be used instead of the connecting rod 203 and the support column 216. Other mechanisms may be used instead of the drive unit 201, shaft 202, and connecting rod 203 for the mechanism that moves the lower frame 110 up and down relative to the upper frame 102 (ground). The height of the lower frame 110 from the ground (distance between the lower frame 110 and the ground) can be adjusted by the drive unit 201, shaft 202, connecting rod 203, etc. The shaft 202 may be included in the drive unit 201. The support column 216 is an example of a support column. The connecting rod 203 is an example of a connecting part.

[0054] This modified self-propelled detector 100 (Modification 2) can be suitably used in the measurement method shown in Figure 9. While the self-propelled detector 100 is moving between each section of the measurement target, it moves with the lower frame 110 raised as shown in Figure 10. When the self-propelled detector 100 reaches the measurement position, it lowers the lower frame 110 as shown in Figure 11, bringing the measuring instrument closer to the ground. This suppresses vibrations to the measuring instrument during movement and makes it possible to improve the movement speed of the self-propelled detector 100 between measurement sections.

[0055] The configurations of the above embodiments can be implemented in combination as much as possible. [Explanation of Symbols]

[0056] 100 Self-propelled detectors 102 Upper frame 104 Column section 106 Wheels 108 axles 110 Lower frame 112 Auxiliary wheels 114 axles 116 bands 118 Source 120 detectors 122 Laser measuring instruments 124 Position detection unit 126 Control Unit 130 Sled section 201 Drive Unit 202 Axis rod 203 Connecting rod 216 Post

Claims

1. A self-propelled detector that travels across a predetermined area of ​​the ground, The casing and Multiple wheels attached to the housing, A radiation source that irradiates the ground with radiation, A detector for detecting the number of radiation particles reflected by the ground, A position detection unit for detecting the position of the self-propelled detector, The radiation source and the lower frame on which the detector is mounted, A strip-shaped or string-shaped elastic traction member that pulls the lower frame from the housing, Multiple auxiliary wheels attached to the lower frame, The self-propelled detector includes a control unit that controls the wheels to travel within a predetermined range divided into multiple regions, A self-propelled detector equipped with [a specific feature / ability].

2. The self-propelled detector according to claim 1, wherein the control unit calculates the compaction state of the ground for each of the plurality of regions based on the number of radiation detected by the detector and the position of the self-propelled detector detected by the position detection unit.

3. The radiation is neutron radiation, and the compaction state of the ground is the water content of the ground. The self-propelled detector according to claim 2.

4. The radiation is gamma rays, and the compaction state of the ground is the wet density of the ground. The self-propelled detector according to claim 2.

5. A distance measuring device is mounted on the lower frame and measures the distance between the detector and the ground. Equipped with a vessel, The control unit calculates the compaction state of the ground for each of the multiple regions based on the number of radiation detected by the detector, the position of the self-propelled detector detected by the position detection unit, and the distance measured by the distance measuring instrument. The self-propelled detector according to claim 1.

6. The self-propelled detector according to claim 1, further comprising a curved portion that extends from the end of the lower frame and curves upward.

7. The self-propelled detector according to claim 1, characterized in that the lower frame further comprises an electromagnetic densimeter or a surface thermometer.

8. Each of the aforementioned regions has a representative point, The control unit controls the wheels so that the self-propelled detector stops at the position of each of the representative points. The detector detects the number of radiation when the self-propelled detector is stopped. A self-propelled detector according to any one of claims 1 to 4.

9. A self-propelled detector that travels across a predetermined area of ​​the ground, The casing and Multiple wheels attached to the housing, A radiation source that irradiates the ground with radiation, A detector for detecting the number of radiation particles reflected by the ground, A position detection unit for detecting the position of the self-propelled detector, The radiation source and the lower frame on which the detector is mounted, Multiple auxiliary wheels attached to one end of the lower frame, A curved portion extends from the other end of the lower frame and curves upward, The self-propelled detector includes a control unit that controls the wheels to travel within a predetermined range divided into multiple regions, A self-propelled detector equipped with [a specific feature / ability].

10. A self-propelled detector that travels across a predetermined area of ​​the ground, The casing and Multiple wheels attached to the housing, A radiation source that irradiates the ground with radiation, A detector for detecting the number of radiation particles reflected by the ground, A position detection unit for detecting the position of the self-propelled detector, The self-propelled detector includes a control unit that controls the wheels and is pre-configured to travel within a predetermined range, which is divided into a mesh-like area of ​​a predetermined size, and within at least a portion of the multiple areas. Equipped with, The control unit calculates the compaction state of the ground for each of the multiple mesh-shaped regions based on the number of radiation rays detected by the detector and the position of the self-propelled detector detected by the position detection unit.

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