Strain sensor and method for detecting strain

Abstract

To provide a new type of strain sensor and a strain detection method that convert an external force received by a strain generating body that performs fluid control with one degree of freedom into another physical quantity.SOLUTION: A strain sensor comprises a plate-shaped strain generating body made of an elastic material. The strain generating body has a flow path 13 that penetrates the inside of the strain generating body by connecting an inlet 11, which is an opening provided on a first side surface of the strain generating body, and an outlet 12, which is an opening on a second side surface of the strain generating body. The flow path 13 has a nozzle 14, which is a location in the middle of the flow path where a flow path cross-sectional area is locally small. The nozzle 14 changes the flow path cross-sectional area in the nozzle 14 according to distortion caused in the nozzle 14 by the strain generating body being subjected to an external force, thereby changing the pressure of fluid sent to the inlet 11, or the nozzle 14 changes the characteristics of sound generated.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a strain sensor and a method for sensing strain. [Background technology]

[0002] Conventionally, various types of strain sensors have been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-133175 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a new type of strain sensor and a strain detection method that utilizes a fluid flow. [Means for solving the problem]

[0005] In order to achieve the above object, a strain sensor according to one embodiment of the present disclosure includes a plate-shaped strain body made of an elastic member, the strain body having a flow path penetrating the inside of the strain body connecting an inlet which is an opening provided on a first side of the strain body and an outlet which is an opening provided on a second side of the strain body, the flow path having a nozzle in the middle of the flow path which is a location where the flow path cross-sectional area is locally small, the nozzle changes the flow path cross-sectional area in the nozzle in response to strain generated in the nozzle when the strain body is subjected to an external force, thereby changing the pressure of the fluid sent to the inlet, or the nozzle changes the characteristics of the sound generated.

[0006] In order to achieve the above-mentioned object, a strain detection method according to one embodiment of the present disclosure is a strain detection method using the above-mentioned strain sensor, and includes an installation step of installing the strain sensor at a location subjected to an external force, an inlet step of pumping a fluid into the inlet of the strain sensor, and a detection step of detecting the pressure of the fluid pumped into the inlet of the strain sensor. Effect of the Invention

[0007] The present disclosure provides a new type of strain sensor and method for detecting strain that utilizes fluid flow. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an example of the structure of the strain sensor according to the first embodiment. [Diagram 2] FIG. 2 is a top view of the strain sensor of FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a diagram showing the operation of the strain sensor of FIG. 1 when a high flow rate of fluid is fed into it. [Figure 6] FIG. 6 is a cross-sectional view taken along line III-III in FIG. 1 when a high flow rate of fluid is fed into the strain sensor of FIG. [Figure 7] FIG. 7 is a diagram showing the operation of the strain sensor of FIG. 1 when a low flow rate of fluid is fed into it. [Figure 8] FIG. 8 is a cross-sectional view taken along line III-III in FIG. 1 when a low flow rate of fluid is fed into the strain sensor in FIG. [Figure 9] FIG. 9 is a block diagram showing a configuration of the strain sensing system according to the first embodiment. As shown in FIG. [Figure 10] FIG. 10 is a flowchart showing the operation of the strain sensing system in FIG. [Figure 11]FIG. 11 is a schematic diagram showing the configuration and operation of a load applying device in the strain sensing system shown in FIG. [Figure 12] FIG. 12 is a graph showing the relationship between the external force received by the strain sensor of FIG. 1 and the fluid pressure detected by the pressure sensor when the flow rate of the fluid fed to the strain sensor in the strain detection system of FIG. 9 is kept constant at 10 L / min. [Figure 13] FIG. 13 is a graph showing the relationship between the external force received by the strain sensor of FIG. 1 and the pressure of the fluid detected by the pressure sensor when the flow rate of the fluid fed to the strain sensor in the strain detection system of FIG. 9 is changed. [Figure 14] FIG. 14 is a diagram illustrating an example of the structure of the strain sensor according to the second embodiment. In FIG. [Figure 15] FIG. 15 is a top view of the strain sensor of FIG. [Figure 16] FIG. 16 is a cross-sectional view showing an example seen from each cross section of FIG. 15(b). [Figure 17] FIG. 17 is a cross-sectional view showing another example as viewed from each cross section of FIG. 15(b). [Figure 18] FIG. 18 is a cross-sectional view showing still another example as viewed from each cross section of FIG. 15(b). [Figure 19] FIG. 19 is a block diagram showing a configuration of a strain sensing system according to the second embodiment. As shown in FIG. [Figure 20] FIG. 20 is a flowchart showing the main operations of the strain sensing system in FIG. [Figure 21] FIG. 21 is a flowchart showing the detailed operation of the analysis step in FIG. [Figure 22] FIG. 22 is a schematic diagram showing the configuration and operation of a load applying device in the strain sensing system shown in FIG. [Diagram 23] FIG. 23 is a graph showing the relationship between the position at which an external force is applied to the strain sensor of FIG. 14 and the sound pressure of the sound generated from the nozzle when the magnitude of the external force is changed. [Figure 24]FIG. 24 is a graph showing the relationship between the position at which an external force is applied to the strain sensor of FIG. 14 and the frequency of the sound generated by the nozzle when the magnitude of the external force is changed. [Diagram 25] FIG. 25 is a diagram showing an experiment in which the strain sensor of FIG. 14 is curved. [Figure 26] Figure 26 is a graph showing the relationship between the spectral change over time in the frequency of the sound generated by the nozzle when the degree of curvature experienced by the strain sensor of Figure 14 is changed, when the flow rate of the fluid sent to the strain sensor in the strain detection system of Figure 19 is kept constant at 10 L / min. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, the arrangement and connection of the components, as well as the processes, steps, and order of the processes shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims showing the highest concept of the present disclosure will be described as optional components.

[0010] Note that each figure is a schematic diagram and is not necessarily precisely illustrated. Therefore, the scales and the like do not necessarily match in each figure. Furthermore, in each figure, the same reference numerals are used for substantially the same configuration, and duplicated explanations are omitted or simplified. Furthermore, in this specification, the terms "upper" and "lower" do not necessarily refer to the upper direction (vertically upward) and the lower direction (vertically downward) in absolute spatial recognition.

[0011] (Embodiment 1) First, the strain sensor 1 according to the first embodiment will be described.

[0012] The strain sensor 1 according to the first embodiment is a strain sensor that converts an external force received by the strain sensor 1, which has a function of switching between discharge and suction by one-degree-of-freedom fluid control, into the pressure of a fluid being fed by one-degree-of-freedom fluid control. One-degree-of-freedom fluid control means that the inlet through which the fluid is fed from the outside to the strain sensor 1 is limited to one, and the flow rate of the fluid is controlled to a constant amount. In other words, the strain sensor 1 according to the first embodiment is a new type of strain sensor that converts an external force received by the strain sensor 1 into the pressure of a fluid while the fluid is being fed.

[0013] Fig. 1 is a perspective view showing an example of the structure of a strain sensor 1 according to embodiment 1. Fig. 2 is a top view of the strain sensor 1 of Fig. 1. Figs. 1 and 2 are perspective views showing the inside of the strain sensor 1 in order to explain the structure of the strain sensor 1.

[0014] 1 and 2, the strain sensor 1 includes an inlet 11, an outlet 12, a flow path 13, a nozzle 14, a valve 15, a suction and discharge port 16, branch flow paths 17a and 17b, expansion chambers 18a and 18b, and walls 19a and 19b. The strain sensor 1 is a plate-shaped strain element made of an elastic material. For example, the strain sensor 1 is made of silicone rubber or the like.

[0015] The inlet 11 is an opening provided on a first side surface of the strain sensor 1. The inlet 11 is an opening for allowing a fluid to flow into the inside of the strain sensor 1 from the outside.

[0016] The outlet 12 is an opening provided on the second side surface of the strain sensor 1. The outlet 12 is an opening for allowing the fluid that has flowed into the strain sensor 1 to flow out. In the first embodiment, the outlet 12 is provided on a surface facing the inlet 11, but it may be provided on a surface not facing the inlet 11.

[0017] The flow path 13 passes through the inside of the strain sensor 1 and connects the inlet 11 and the outlet 12. More specifically, the flow path 13 branches into two flow paths midway, and the two flow paths merge after passing through nozzles 14 provided at the most downstream of each of the branched flow paths, and then pass through a valve 15 before being connected to the outlet 12.

[0018] The nozzle 14 is a portion where the cross-sectional area of ​​the flow path 13 is locally small in the middle of the flow path 13 (more specifically, the most downstream portion of the branch of the flow path 13). The cross-sectional area of ​​the flow path of the nozzle 14 changes depending on the external force received by the strain sensor 1, and a detailed description of this will be given later.

[0019] The valve 15 is provided in the flow path 13 closer to the outlet 12 than the nozzle 14. The valve 15 opens and closes depending on the flow rate of the fluid. When the valve 15 is open, the fluid flowing from upstream passes through the valve 15 and flows out from the outlet 12.

[0020] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. Line III-III passes through valve 15. Valve 15 is an elastic member that is made up of two partition plates 15a and 15b that are separated vertically. Valve 15 has a rectangular plate-like overall shape. The upper side of partition plate 15a and the lower side of partition plate 15b are fixed to the upper and bottom surfaces that constitute strain sensor 1. Partition plates 15a and 15b are structured to be openable and closable depending on the flow rate of fluid. Valve 15 is not limited to the structure shown in embodiment 1, and may be structured to be openable and closable depending on the flow rate of fluid, made up of one or more partitions.

[0021] 1 and 2, the suction and discharge port 16 is an opening that leads to the flow path 13 that is closer to the inlet 11 than the valve 15, and in this embodiment, is provided on the top surface of the strain sensor 1. The suction and discharge port 16 is an opening for sucking fluid into the strain sensor 1 from the outside or discharging fluid from the strain sensor 1 to the outside by changing the flow rate of the fluid flowing into the strain sensor 1 from the inlet 11. A detailed description of the suction and discharge of fluid performed by the strain sensor 1 via the suction and discharge port 16 will be given later.

[0022] The branch flow paths 17a and 17b are flow paths branched off from the flow path 13, which is closer to the inlet 11 than the nozzle 14, in a manner that bypasses the portion that constitutes the suction and discharge port 16. A part of the fluid that has flowed in from the inlet 11 flows from the flow path 13 to the branch flow paths 17a and 17b.

[0023] The expansion chamber 18a is connected to the branch flow passage 17a, and the expansion chamber 18b is connected to the branch flow passage 17b. The expansion chambers 18a and 18b are bag-shaped and do not have an opening through which the fluid flows out to the outside. As shown in Figs. 1, 2, and 3, the expansion chambers 18a and 18b are provided at positions sandwiching the flow passage 13 and the valve 15, separated by walls 19a and 19b, when viewed from above the strain sensor 1. A part of the fluid that flows in from the inlet 11 flows from the flow passage 13 to the branch flow passages 17a and 17b, and fills the expansion chambers 18a and 18b through the branch flow passages 17a and 17b, respectively. Since the strain sensor 1 is made of an elastic member, the expansion chambers 18a and 18b expand depending on the flow rate of the fluid. The walls 19a and 19b are pushed in a direction narrowing the flow passage 13 from the left and right as the expansion chambers 18a and 18b expand.

[0024] The wall 19a is an elastic member and separates the flow passage 13 from the expansion chamber 18a, while the wall 19b is an elastic member and separates the flow passage 13 from the expansion chamber 18b.

[0025] Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1. Fig. 4(a) is a cross-sectional view taken along line IV-IV in Fig. 1 when the strain sensor 1 is not subjected to an external force. Fig. 4(b) is a cross-sectional view taken along line IV-IV in Fig. 1 when the strain sensor 1 is subjected to an external force. The external force in Fig. 4(b) is applied to the periphery of the nozzle 14 from the top surface of the strain sensor 1.

[0026] The strain sensor 1 is deformed by receiving an external force. Therefore, when the strain sensor 1 is subjected to an external force, the flow path cross-sectional area of ​​the nozzle 14 becomes smaller as shown in FIG. 4(b) than the flow path cross-sectional area of ​​the nozzle 14 shown in FIG. 4(a). Due to the smaller flow path cross-sectional area of ​​the nozzle 14, the pressure of the fluid passing through the nozzle 14 becomes higher in FIG. 4(b) than in FIG. 4(a). As a result, when the fluid fed to the strain sensor 1 is controlled at a constant flow rate, the pressure of the fluid fed from the inlet 11 becomes higher in FIG. 4(b) than in FIG. 4(a). By monitoring this pressure change, the strain sensor 1 detects whether or not an external force is being received and the magnitude of the external force.

[0027] Next, the operation of the strain sensor 1 when a fluid is fed into the inlet 11 of the strain sensor 1 will be described.

[0028] The mechanism by which the strain sensor 1, which is subjected to one-degree-of-freedom fluid control, sucks in a fluid from the suction and discharge port 16 will be described. Fig. 5 is a diagram showing the operation when a high flow rate of fluid is fed into the strain sensor 1 of Fig. 1. Fig. 5 is a see-through diagram showing the inside of the strain sensor 1 from its top surface to explain the structure of the strain sensor 1. Fig. 6 is a cross-sectional view taken along line III-III in Fig. 1 when a high flow rate of fluid is fed into the strain sensor 1 of Fig. 1.

[0029] As shown in FIG. 5, most of the fluid sent from the inlet 11 flows through the flow path 13 and the nozzle 14 to the valve 15. On the other hand, a part of the fluid sent from the inlet 11 flows from the flow path 13 to the branch flow paths 17a and 17b, and reaches the expansion chambers 18a and 18b through the branch flow paths 17a and 17b. When the flow rate of the fluid sent from the inlet 11 is high, the proportion of the fluid that passes through the branch flow paths 17a and 17b and reaches the expansion chambers 18a and 18b is greater than when the flow rate is low. When a sufficient amount of fluid is sent to the expansion chambers 18a and 18b, the expansion chambers 18a and 18b expand. The walls 19a and 19b are pushed in a direction that narrows the flow path 13 by the expansion of the expansion chambers 18a and 18b.

[0030] 6, the walls 19a and 19b are pushed in a direction narrowing the flow path 13 by the expansion of the expansion chambers 18a and 18. Then, the valve 15 sandwiched between the expansion chambers 18a and 18b is crushed from the left and right, and a space is created between the partition plates 15a and 15b.

[0031] Returning to the explanation in Figure 5, the flow of fluid will now be described. Because a large space is created between partition plates 15a and 15b, the fluid passes through valve 15 and flows out from outlet 12. When valve 15 opens and the fluid sent in from inlet 11 flows out from outlet 12, negative pressure is generated near the connection of suction and discharge port 16 to flow path 13, causing a jet flow that draws in the fluid inside suction and discharge port 16. Because the fluid near suction and discharge port 16 is drawn in by the jet flow, the fluid outside strain sensor 1 flows into strain sensor 1 through suction and discharge port 16. Due to the above operation of strain sensor 1, strain sensor 1 draws in the fluid outside strain sensor 1 from suction and discharge port 16.

[0032] The mechanism by which the strain sensor 1, which is subjected to one-degree-of-freedom fluid control, discharges fluid from the suction and discharge port 16 will be described. Fig. 7 is a diagram showing the operation when a low flow rate of fluid is fed into the strain sensor 1 of Fig. 1. Fig. 7 is a diagram showing the inside of the strain sensor 1, seen through the top surface of the strain sensor 1, to explain the operation of the strain sensor 1. Fig. 8 is a cross-sectional view taken along line III-III in Fig. 1 when a low flow rate of fluid is fed into the strain sensor 1 of Fig. 1.

[0033] As shown in Fig. 7, most of the fluid sent from the inlet 11 flows through the flow path 13 and the nozzle 14 to the valve 15. A part of the fluid sent from the inlet 11 flows from the flow path 13 to the branch flow paths 17a and 17b, and reaches the expansion chambers 18a and 18b through the branch flow paths 17a and 17b. When the flow rate of the fluid sent from the inlet 11 is low, the proportion of the fluid that passes through the branch flow paths 17a and 17b and reaches the expansion chambers 18a and 18b is smaller than when the flow rate is high. Therefore, a sufficient amount of fluid is not sent to the expansion chambers 18a and 18b, and the expansion chambers 18a and 18b hardly expand.

[0034] As shown in FIG. 8, the expansion chambers 18a and 18b barely expand, and the valve 15 barely deforms.

[0035] Returning to the explanation in Fig. 7, the flow of the fluid will now be described. Since only a small space is formed between partition plates 15a and 15b, only a small amount of the fluid passes through valve 15. Most of the fluid collides with valve 15 and flows back through flow path 13 into suction and discharge port 16, through which it flows out of strain sensor 1. Due to the above operation of strain sensor 1, the strain sensor 1 discharges the fluid from suction and discharge port 16 to the outside of strain sensor 1.

[0036] 9 is a block diagram showing a configuration of a strain sensing system 2 according to embodiment 1. The strain sensing system 2 is a system that detects an external force acting on a strain sensor 1. The strain sensing system 2 includes the strain sensor 1, a fluid inflow device 21, a load application device 22, a pressure sensor 23, and an analysis device 24.

[0037] The fluid inflow device 21 is connected to the inlet 11 of the strain sensor 1 via a tube, and feeds fluid into the strain sensor 1 via the tube. For example, the fluid inflow device 21 is a pump that feeds fluid into the strain sensor 1, and feeds, for example, 5 to 30 L / min of fluid into the strain sensor 1 via the tube. The fluid inflow device 21 also controls the inflow amount of the fluid fed into the strain sensor 1 to be constant.

[0038] The load applying device 22 is a device that applies an external force (that is, applies a load) to the upper surface of the strain sensor 1, or releases the external force applied to the strain sensor 1 to remove the load. The detailed configuration and operation of the load applying device 22 will be described later.

[0039] The pressure sensor 23 is connected to the inlet 11 of the strain sensor 1 via a tube. The pressure sensor 23 detects the pressure of the fluid fed from the fluid inflow device 21 to the inlet 11 of the strain sensor 1, and is, for example, a fluid pressure sensor.

[0040] The analysis device 24 is a device that receives a signal from the pressure sensor 23 and analyzes the fluid pressure detected by the pressure sensor 23, thereby identifying the magnitude of the external force acting on the strain sensor 1. For example, the analysis device 24 is a computer that performs signal input processing (such as A / D conversion) and information processing (such as conversion of physical quantities).

[0041] The load application device 22 is a device that is provided experimentally in order to apply a known external force to the strain sensor 1, and does not necessarily have to be provided as a component of the strain detection system 2.

[0042] Next, the operation of the strain detection system 2, that is, the method of detecting strain, will be described.

[0043] FIG. 10 is a flowchart showing the operation of the strain sensing system 2 in FIG.

[0044] First, the strain sensor 1 is placed at a location where an external force is applied (installation step S1).

[0045] The fluid inflow device 21 connected to the inlet 11 of the strain sensor 1 feeds a fluid into the strain sensor 1 (inflow step S2).

[0046] The load application device 22 applies an external force to the upper surface of the strain sensor 1 (loading step S3). Then, the nozzle 14 of the strain sensor 1 changes the flow path cross-sectional area in response to the received external force. As a result, the strain sensor 1 converts the received external force into the pressure of the fluid sent from the fluid inflow device 21 to the strain sensor 1 (conversion step S4).

[0047] The pressure sensor 23 connected to the inlet 11 of the strain sensor 1 detects the pressure of the fluid fed from the fluid inflow device 21 to the strain sensor 1 (detection step S5).

[0048] The analysis device 24 receives a signal from the pressure sensor 23 and, by referring to a conversion table prepared in advance, converts the fluid pressure detected by the pressure sensor 23 into the magnitude of the external force received by the strain sensor 1, and displays the result on a display or the like (analysis step S6).

[0049] Since the load step S3 is a step for experimentally applying a known external force to the strain sensor 1, when the strain sensor 1 is used for detecting an unknown strain, it does not necessarily have to be included in the strain detection system 2. The order of the installation step S1 and the flow-in step S2 may be reversed, or they may be performed simultaneously.

[0050] Fig. 11 is a schematic diagram showing the configuration and operation of the load application device 22 in the strain sensing system 2 shown in Fig. 9. Fig. 11(a) is a schematic diagram of the strain sensing system 2 as viewed from the Y-axis direction. Fig. 11(b) is a top view of the strain sensor 1 showing the location to which an external force is applied by the load application device 22. Fig. 11(b) is a see-through view of the inside of the strain sensor 1, showing the location to which an external force is applied to the strain sensor 1, from the top surface of the strain sensor 1, in order to explain the location to which an external force is applied to the strain sensor 1.

[0051] As shown in FIG. 11( a ), the load application device 22 includes a load cell 221 and a Z-axis linear actuator 222 .

[0052] The load cell 221 is a transducer that converts the force received into an electrical signal.

[0053] The Z-axis linear actuator 222 is a driving device that moves the load cell 221 in the Z-axis direction so as to press it against the strain sensor 1 .

[0054] 11(b), in the first embodiment, the load cell 221 moved by the Z-axis linear actuator 222 presses a circled area of ​​the strain sensor 1. Specifically, the load cell 221 moved by the Z-axis linear actuator 222 presses an area including the nozzle 14 of the strain sensor 1.

[0055] Figure 12 is a graph showing the relationship between the external force received by the strain sensor 1 of Figure 1 and the fluid pressure detected by the pressure sensor 23 when the flow rate of the fluid fed to the strain sensor 1 in the strain detection system 2 of Figure 9 is kept constant at 10 L / min.

[0056] Fig. 12(a) is a graph showing the external force received by the strain sensor 1 and the fluid pressure detected by the pressure sensor 23 over time when the flow rate of the fluid fed to the strain sensor 1 of the strain detection system 2 is 10 L / min. The experimental procedure will be described with reference to Fig. 12(a).

[0057] As shown in FIG. 12(a), the load application device 22 applies an external force to the strain sensor 1 in accordance with an external control instruction in the following order of operations 1 to 3.

[0058] The Z-axis linear actuator 222 moves the load cell 221 downward in the Z-axis direction at a constant speed of 0.1 mm / s, applying an external force to the strain sensor 1 (operation 1). Operation 1 corresponds to the section in FIG. 12(a) where the external force and the pressure of the fluid detected by the pressure sensor 23 increase.

[0059] Since the strain sensor 1 is an elastic member, it is deformed by the application of an external force. When the load application device 22 presses the strain sensor 1 by 1 mm, the Z-axis linear actuator 222 stops the load cell 221 in place for 10 seconds (operation 2). Operation 2 corresponds to the section in FIG. 12(a) where the external force and the pressure of the fluid detected by the pressure sensor 23 decrease slightly.

[0060] After the load cell 221 has stopped for 10 seconds, the Z-axis linear actuator 222 moves the load cell 221 upward in the Z-axis direction at a constant speed of 0.1 mm / s, and releases the external force applied to the strain sensor 1 (operation 3). Operation 3 corresponds to the section in FIG. 12(a) where the external force and the pressure of the fluid detected by the pressure sensor 23 suddenly decrease.

[0061] When the load applying device 22 confirms that the load cell 221 and the strain sensor 1 are completely separated, it repeats the above operations 1 to 3. In the experiment, the load applying device 22 repeated the above operations 1 to 3 three times. During this experiment, a constant flow rate of 10 L / min was fed to the strain sensor 1 from the fluid inflow device 21.

[0062] 12(a), the fluctuation in fluid pressure detected by pressure sensor 23 follows the fluctuation in external force applied to strain sensor 1. The fluid pressure detected by pressure sensor 23 is correlated with the external force applied to strain sensor 1. It can be seen that strain detection system 2 detects the external force applied to strain sensor 1.

[0063] Based on the above correlation, a conversion table showing the relationship between the magnitude of a known external force applied to the strain sensor 1 and the pressure of the fluid detected by the pressure sensor 23 can be created in advance by prior calibration.

[0064] Therefore, the analysis device 28 can specify the magnitude of the unknown external force applied to the strain sensor 1 by analyzing the pressure of the fluid measured by the pressure sensor 23 and referring to a conversion table created in advance.

[0065] FIG. 12(b) is a graph showing the fluid pressure detected by the pressure sensor 23 relative to the external force applied to the strain sensor 1 when the flow rate of the fluid fed to the strain sensor 1 of the strain detection system 2 is 10 L / min.

[0066] 12(b), there is no significant difference between the straight line obtained by operation 1 and the straight line obtained by operation 3. In other words, the hysteresis phenomenon, which is influenced not only by the currently applied external force but also by external forces applied in the past, does not occur in the strain sensor 1. This allows the strain detection system 2 to identify the magnitude of the external force received by the strain sensor 1, whether the external force applied to the strain sensor 1 is a load or an unload.

[0067] An experimental procedure for the strain detection method of the strain detection system 2 when the flow rate of the fluid sent from the fluid inflow device 21 to the strain sensor 1 is changed will be described. Only the points that are different from the experimental procedure in Fig. 12 will be described, and the same points will be omitted.

[0068] When the load application device 22 performed the same operations 1 to 3 as those in the experimental procedure shown in Fig. 12, the flow rate of the fluid fed from the fluid inflow device 21 to the strain sensor 1 was changed. Specifically, the flow rates of the fluid fed from the fluid inflow device 21 to the strain sensor 1 were set to 10, 20, and 30 L / min.

[0069] FIG. 13 is a graph showing the relationship between the external force received by the strain sensor 1 of FIG. 1 and the fluid pressure detected by the pressure sensor 23 when the flow rate of the fluid fed to the strain sensor 1 in the strain detection system 2 of FIG. 9 is changed.

[0070] Fig. 13(a) is a graph showing the external force received by the strain sensor 1 over time and the fluid pressure detected by the pressure sensor 23 when the flow rate of the fluid fed from the fluid inflow device 21 to the strain sensor 1 is 10 L / min. Fig. 13(b) is a graph showing the external force received by the strain sensor 1 over time and the fluid pressure detected by the pressure sensor 23 when the flow rate of the fluid fed from the fluid inflow device 21 to the strain sensor 1 is 20 L / min.

[0071] 13(a), in the strain sensor 1 according to embodiment 1, when the flow rate of the fluid fed from the inlet 11 of the strain sensor 1 is 10 L / min or less, the fluid is discharged from the suction and discharge port 16. On the other hand, as shown in Fig. 13(b), when the flow rate of the fluid fed from the inlet 11 of the strain sensor 1 is 20 L / min or more, the fluid is sucked in from the suction and discharge port 16. In other words, in the experimental results shown in Fig. 13, Fig. 13(a) shows the experimental results in a state where the strain sensor 1 discharges fluid from the suction and discharge port 16, and Fig. 13(b) shows the experimental results in a state where the strain sensor 1 sucks in fluid from the suction and discharge port 16.

[0072] Comparing FIG. 13(a) and FIG. 13(b), the slope of the straight line in FIG. 13(b) is larger than the slope of the straight line in FIG. 13(a). This indicates that when the same magnitude of external force is applied to the strain sensor 1, the pressure of the fluid detected by the pressure sensor 23 is larger when the flow rate of the fluid fed from the fluid inflow device 21 is 20 L / min than when it is 10 L / min. As the pressure of the fluid detected by the pressure sensor 23 increases, the magnitude of the external force analyzed and identified by the analysis device 24 increases. In other words, by increasing the flow rate of the fluid fed to the strain sensor 1 and switching the state in which the strain sensor 1 discharges the fluid from the suction and discharge port 16 to the state in which the fluid is sucked in from the suction and discharge port 16, the sensitivity of the strain detection system 2 to the external force received by the strain sensor 1 can be increased.

[0073] From the experimental results shown in FIG. 13, it is understood that the strain detection system 2 can change the sensitivity of the strain sensor 1 to an external force received by switching between suction and discharge of fluid from the suction and discharge port 16 of the strain sensor 1.

[0074] As described above, the strain sensor 1 of embodiment 1 includes a plate-shaped strain body made of an elastic material, the strain body having a flow path 13 that passes through the inside of the strain body, connecting the inlet 11, which is an opening provided on a first side of the strain body, and the outlet 12, which is an opening provided on a second side of the strain body, and the flow path 13 has a nozzle 14, which is a location where the flow path cross-sectional area is locally small, in the middle of the flow path 13, and the nozzle 14 changes the flow path cross-sectional area at the nozzle 14 in response to the strain generated in the nozzle 14 when the strain body is subjected to an external force, thereby changing the pressure of the fluid sent to the inlet 11.

[0075] As a result, the new type of strain sensor, which performs one-degree-of-freedom fluid control without using electronic components or wiring, can detect whether or not an external force is being applied and the magnitude of the external force.

[0076] Furthermore, the strain detection method of embodiment 1 is a strain detection method using the strain sensor 1 described above, and includes an installation step S1 of installing the strain sensor 1 at a location where it will be subjected to an external force, a flow-in step S2 of pumping a fluid into the inlet 11 of the strain sensor 1, and a detection step S5 of detecting the pressure of the fluid pumped into the inlet 11 of the strain sensor 1.

[0077] This makes it possible to identify the magnitude of an unknown external force using a new type of strain detection method configured using a new type of strain sensor that allows for one-degree-of-freedom fluid control without using electronic components or wiring.

[0078] In addition, in the strain detection method according to embodiment 1, the flexure body has a valve 15 that opens and closes a flow path 13 that is closer to the outlet 12 than the nozzle 14, and the flexure body has a suction and discharge port 16 that is an opening that leads to the flow path 13 that is closer to the inlet 11 than the valve 15, and in the inflow step S2, the opening sends fluid into the inlet 11 at a flow rate that causes the opening to suck in or discharge air from the outside.

[0079] This allows the new type of strain detection method to change the sensitivity of the strain sensor to an external force received by the strain sensor by switching between suction and discharge of fluid.

[0080] The strain sensor 1 according to the first embodiment does not necessarily have to include the valve 15, the suction and discharge port 16, the branch flow paths 17a and 17b, and the expansion chambers 18a and 18b. The objective can be achieved even with a strain sensor 1 that does not include the valve 15, the suction and discharge port 16, the branch flow paths 17a and 17b, and the expansion chambers 18a and 18b.

[0081] (Embodiment 2) Next, a description will be given of the strain sensor 1a according to embodiment 2. The strain sensor 1 according to embodiment 1 converts the external force received by the strain sensor 1 into the pressure of a fluid sent to the inlet 11 of the strain sensor 1. On the other hand, the strain sensor 1a according to embodiment 2 converts the external force received by the strain sensor 1a into a sound generated by the nozzle 14 of the strain sensor 1a.

[0082] The strain sensor 1a according to the second embodiment is a strain sensor that converts an external force received by the strain sensor 1a into sound by fluid control with one degree of freedom.

[0083] Fig. 14 is a perspective view showing the structure of a strain sensor 1a according to embodiment 2. Fig. 14 is a see-through view of the top surface of the strain sensor 1a to illustrate the inside of the strain sensor 1a in order to explain the structure of the strain sensor 1a. Below, differences from the strain sensor 1 according to embodiment 1 will be explained, and explanations of the same points will be omitted.

[0084] Like the strain sensor 1 according to the first embodiment, the strain sensor 1a includes an inlet 11, an outlet 12, a flow path 13, a nozzle 14, and a suction and discharge port 16, but unlike the strain sensor 1 according to the first embodiment, the strain sensor 1a does not include a valve 15, branch flow paths 17a and 17b, expansion chambers 18a and 18b, and walls 19a and 19b. The strain sensor 1a also includes a nozzle outer wall 14a. The nozzle outer wall 14a will be described in detail with reference to FIG. 15.

[0085] Fig. 15 is a top view of the strain sensor 1a in Fig. 14. Fig. 15 is a see-through view of the inside of the strain sensor 1a from the top to explain the structure of the strain sensor 1a. Fig. 15(a) is a top view of the entire strain sensor 1a in Fig. 14. Fig. 15(b) is an enlarged view of the part surrounded by the dotted line in Fig. 15(a).

[0086] 15(a) and 15(b), the nozzle outer wall 14a is provided in a direction that extends the tip of the nozzle 14 toward the outlet 12. As a result, the nozzle 14 of the strain sensor 1a is formed longer toward the outlet 12 than the nozzle 14 of the strain sensor 1.

[0087] Fig. 16 is a cross-sectional view showing an example seen from each cross section of Fig. 15(b). Fig. 16(a) is a cross-sectional view taken along line A-A' of Fig. 15(b). Fig. 16(b) is a cross-sectional view taken along line B-B' of Fig. 15(b).

[0088] 16(a) and 16(b), the nozzle outer wall 14a has a rectangular slit 14b in the center of the nozzle outer wall 14a. The rectangular slit 14b is provided from the tip of the nozzle outer wall 14a close to the outlet 12 to the position where the thickness of the nozzle outer wall 14a changes. Fig. 17 is a cross-sectional view showing another example seen from each cross section of Fig. 15(b). Fig. 17(a) is a cross-sectional view taken along line A-A' of Fig. 15(b). Fig. 17(b) is a cross-sectional view taken along line B-B' of Fig. 15(b).

[0089] 17(a) and 17(b), the nozzle outer wall 14a has rectangular notches 14b on the upper and lower sides thereof. The rectangular notches 14b are provided from the tip of the nozzle outer wall 14a close to the outlet 12 to the position where the thickness of the nozzle outer wall 14a changes.

[0090] Fig. 18 is a cross-sectional view showing yet another example seen from each cross section of Fig. 15(b). Fig. 18(a) is a cross-sectional view taken along line A-A' of Fig. 15(b). Fig. 18(b) is a cross-sectional view taken along line B-B' of Fig. 15(b).

[0091] As shown in (a) of FIG. 18 and (b) of FIG. 18, the nozzle outer wall 14a has a slit 14b. The slit 14b has an L-shape and is composed of a rectangular slit 14b1 and another rectangular slit 14b2. The nozzle outer wall 14a has a rectangular slit 14b1 on the upper side of the nozzle outer wall 14a. The rectangular slit 14b1 is provided from the tip of the nozzle outer wall 14a close to the outlet 12 to a position where the thickness of the nozzle outer wall 14a changes. In addition, the nozzle outer wall 14a has another rectangular slit 14b2. The other rectangular slit 14b2 is provided at the position where the thickness of the nozzle outer wall 14a changes so as to connect the upper side and the lower side of the nozzle outer wall 14a. The rectangular slit 14b1 and the other rectangular slit 14b2 are connected at the upper side of the nozzle outer wall 14a.

[0092] The fluid sent to the strain sensor 1a not only flows into the flow path 13 from the tip of the nozzle 14 close to the outlet 12, but also flows into the flow path 13 by passing through the slit 14b in the nozzle outer wall 14a.

[0093] The notch 14b in the nozzle outer wall 14a of the strain sensor 1a is not limited to the shape described above, and is within the scope of variation of the present disclosure as long as it has a shape that realizes the function performed by the nozzle outer wall 14a described below.

[0094] 15(a), the fluid sent to the strain sensor 1a from the inlet 11 passes through the flow path 13 and the nozzle 14 provided midway through the flow path 13, and flows out from the outlet 12. The fluid sent to the strain sensor 1a not only flows into the flow path 13 from the tip of the nozzle 14 close to the outlet 12, but also flows into the flow path 13 by passing through the slit 14b in the nozzle outer wall 14a.

[0095] The nozzle outer wall 14a vibrates due to the fluid flowing into the flow path 13 from the slits 14b in the nozzle outer wall 14a. The vibration of the nozzle outer wall 14a causes the nozzle 14 to generate sound. Furthermore, the nozzle 14 changes the characteristics of the sound generated by the nozzle 14 depending on the external force received by the strain sensor 1a. Specifically, the nozzle 14 changes the characteristics of the sound generated by the nozzle 14 depending on the magnitude of the external force received by the strain sensor 1a, the position on the strain sensor 1a that receives the external force, and the degree of curvature received by the strain sensor 1a. The changes in the characteristics of the sound generated by the nozzle 14 will be described in detail using experimental results described later.

[0096] 19 is a block diagram showing a configuration of a strain sensing system 2a according to Embodiment 2. The explanation of the strain sensing system 2a according to Embodiment 2 will focus on differences from the strain sensing system 2 according to Embodiment 1, and the same points will be omitted.

[0097] 19, the strain sensing system 2a is a system for detecting an external force applied to the strain sensor 1a. Unlike the strain sensor 1 according to the first embodiment, the strain sensing system 2a includes the strain sensor 1a, a fluid inflow device 25, a load application device 26, a microphone 27, and an analysis device 28.

[0098] The fluid inflow device 25 is the same device as the fluid inflow device 21 of the embodiment 1. The fluid inflow device 25 is connected to the inlet 11 of the strain sensor 1a via a tube, and sends a fluid to the strain sensor 1a via the tube.

[0099] The load applying device 26 is similar to the load applying device 22 of the embodiment 1. The detailed configuration and operation of the load applying device 26 will be described later.

[0100] The microphone 27 is a device that detects the sound generated by the nozzle 14 of the strain sensor 1a. The microphone 27 may be provided inside or outside the strain sensor 1a.

[0101] The analysis device 28 is a device that receives a signal from the microphone 27 and analyzes (such as fast Fourier transform) the sound detected by the microphone 27 to identify the magnitude of the external force applied to the strain sensor 1a, the position in the strain sensor 1a that has received the external force, and the degree of curvature applied to the strain sensor 1a. For example, the analysis device 28 is a computer that performs input processing of signals (such as A / D conversion) and information processing (such as conversion of physical quantities).

[0102] The load application device 26 is a device that is provided experimentally in order to apply a known external force to the strain sensor 1a, and is not necessarily required to be provided as a component of the strain detection system 2a.

[0103] Next, the operation of the strain detection system 2a, that is, the method of detecting strain, will be described.

[0104] FIG. 20 is a flowchart showing main operations of the strain sensing system 2a in FIG.

[0105] First, the strain sensor 1a is placed at a location where an external force is applied (installation step S1).

[0106] The fluid inflow device 25 connected to the inlet 11 of the strain sensor 1a feeds a fluid into the strain sensor 1a (inflow step S2).

[0107] The load application device 26 applies an external force to the strain sensor 1a (load step S3), which causes the nozzle 14 of the strain sensor 1a to change the characteristics of the sound it generates (conversion step S4a).

[0108] The microphone 27 detects the sound generated by the nozzle 14 of the strain sensor 1a (detection step S5a).

[0109] The analysis device 28 receives a signal from the microphone 27 and analyzes the sound detected by the microphone 27 to identify the magnitude and position of the external force received by the strain sensor 1a or the degree of curvature received by the strain sensor 1a, and displays the result on a display or the like (analysis step S6a).

[0110] In addition, since the load step S3 is a step for applying a known external force to the strain sensor 1a in an experiment, when the strain sensor 1a is used for detecting an unknown strain, it does not necessarily have to be included in the strain detection system 2a. In addition, the order of the installation step S1 and the flow-in step S2 may be reversed, or they may be performed simultaneously.

[0111] FIG. 21 is a flow chart showing the detailed operation of the analysis step S6a in FIG.

[0112] Fig. 21(a) is a flowchart showing the operation of identifying the position of the external force received by the strain sensor 1a. Fig. 21(b) is a flowchart showing the operation of identifying the magnitude of the external force received by the strain sensor 1a. Fig. 21(c) is a flowchart showing the operation of identifying the degree of curvature received by the strain sensor 1a.

[0113] As shown in (a) of FIG. 21, the analysis device 28 analyzes the loudness of the sound detected by the microphone 27 in the detection step S5a, and converts the analyzed loudness of the sound into a corresponding force using a conversion table prepared in advance, thereby identifying the magnitude of the external force received by the strain sensor 1a (analysis step S6a).

[0114] As shown in (b) of Figure 21, the analysis device 28 analyzes the frequency spectrum of the sound detected by the microphone 27 in the detection step S5a, and converts the peak frequency or frequency spectrum of the analyzed sound into a corresponding position using a conversion table prepared in advance, thereby identifying the position of the external force received by the strain sensor 1a (analysis step S6a).

[0115] As shown in (c) of Figure 21, the analysis device 28 analyzes the frequency of the sound detected by the microphone 27 in the detection step S5a, and converts the frequency spectrum of the analyzed sound into a corresponding degree of curvature using a conversion table prepared in advance, thereby identifying the degree of curvature experienced by the strain sensor 1a (analysis step S6a).

[0116] The analysis device 28 executes at least one of the analysis steps S6a shown in Fig. 21(a), Fig. 21(b), and Fig. 21(c). The analysis device 28 may execute a plurality of analysis steps S6a simultaneously. There is no restriction on the combination of a plurality of analysis steps S6a.

[0117] FIG. 22 is a schematic diagram showing the configuration and operation of the load applying device 26 in the strain sensing system 2a shown in FIG.

[0118] Fig. 22(a) is a schematic diagram of the strain sensing system 2a as viewed from the Y-axis direction. Fig. 22(b) is an enlarged view of the strain sensor 1a in Fig. 15(a) enclosed in a dotted line frame. Fig. 22(b) is a see-through view of the inside of the strain sensor 1a as viewed from the top surface of the strain sensor 1a to explain the location where an external force is applied to the strain sensor 1a.

[0119] As shown in FIG. 22( a ), the load application device 26 includes a load cell 261 , a Z-axis linear actuator 262 , and an X-axis linear actuator 263 .

[0120] The load cell 261 is a converter similar to the load cell 221 of the first embodiment.

[0121] The Z-axis linear actuator 262 is a driving device similar to the Z-axis linear actuator 222 of the first embodiment.

[0122] The shape of the member in contact with the strain sensor 1a will be described. As shown in (a) of Fig. 22, when viewed from the Y-axis direction, the shape of the member is a pointed shape at the part in contact with the strain sensor 1a. On the other hand, as shown in (b) of Fig. 22, when viewed from the Z-axis direction, the strain sensor 1a receives an external force from the member, for example, as shown by the dotted lines (I) and (II). In other words, the shape of the member is a rectangle at the part in contact with the strain sensor 1a.

[0123] The X-axis direction linear actuator 263 is a driving device that moves, in the X-axis direction, the strain sensor 1a fixed to the X-axis direction linear actuator 263. For example, when the X-axis direction linear actuator 263 moves the strain sensor 1a in the X-axis direction, as shown in Fig. 22(b), the load application device 26 applies an external force to the strain sensor 1a in the range indicated by the double arrow (where the nozzle outer wall 14a has the notch 14b).

[0124] Next, an experimental method for analyzing the volume of the sound detected by the microphone 27 and identifying the volume of the external force applied to the strain sensor 1a will be described.

[0125] As shown in FIG. 22(b), the strain sensor 1a receives an external force from the load device 26 at the positions of dotted lines (I) and (II). The position of dotted line (I) is the root of the notch 14b in the nozzle outer wall 14a. The position of dotted line (II) is the center of the notch 14b in the nozzle outer wall 14a. A constant external force is applied to the strain sensor 1a from the load device 26, and the external forces applied to the strain sensor 1a are 0.5 N, 0.7 N, and 1.0 N. During this experiment, a constant flow rate is fed to the strain sensor 1a.

[0126] Next, the results of an experiment in which the volume of the sound detected by the microphone 27 was analyzed and the volume of the external force received by the strain sensor 1a was identified will be described.

[0127] FIG. 23 is a graph showing the relationship between the position at which an external force is applied to the strain sensor 1a of FIG. 14 and the sound pressure of the sound generated from the nozzle 14 when the magnitude of the external force is changed.

[0128] 23(a), 23(b) and 23(c) are graphs showing the sound pressure when the strain sensor 1a receives an external force along the dotted line (I). 23(d), 23(e) and 23(f) are graphs showing the sound pressure when the strain sensor 1a receives an external force along the dotted line (II). 23(a) and 23(d) are graphs showing the sound pressure when the load device 26 applies an external force of 0.5N to the strain sensor 1a. 23(b) and 23(e) are graphs showing the sound pressure when the load device 26 applies an external force of 0.7N to the strain sensor 1a. 23(c) and 23(f) are graphs showing the sound pressure when the load device 26 applies an external force of 1.0N to the strain sensor 1a. A predetermined external force is applied to the strain sensor 1a from a load applying device 26 between the dotted lines shown in (a) to (f) of FIG.

[0129] The vertical axis in Figures 23(a) to 23(f) is sound pressure, and the larger the absolute value of the measured sound pressure, the louder the sound. The magnitude of sound pressure is compared using the results when an external force is applied to the dotted line (I). Comparing Figures 23(a) to 23(c) shows that the greater the applied external force, the greater the sound pressure. Similarly, the magnitude of sound pressure is compared using the results when an external force is applied to the dotted line (II). Comparing Figures 23(d) to 23(f) shows that the greater the applied external force, the greater the sound pressure.

[0130] On the other hand, the magnitude of sound pressure is compared in the results when an external force of 0.5 N is applied to the strain sensor 1a. Comparing (a) of FIG. 23 with (d) of FIG. 23 shows that there is no difference in the magnitude of sound pressure due to differences in the position at which the external force is applied. Similarly, the magnitude of sound pressure is compared in the results when an external force of 0.7 N and 1.0 N is applied to the strain sensor 1a. Comparing (b) of FIG. 23 with (e) of FIG. 23, and (c) of FIG. 23 with (f) of FIG. 23 also shows that there is no difference in the magnitude of sound pressure due to differences in the position at which the external force is applied.

[0131] The experimental results shown in FIG. 23 show that the greater the external force applied to the strain sensor 1a, the greater the sound pressure detected by the microphone 27, and further, that the magnitude of the sound pressure detected by the microphone 27 does not change depending on the position at which the external force is applied to the strain sensor 1a.

[0132] From the above, a conversion table showing the relationship between the magnitude of a known external force applied to the strain sensor 1a and the sound pressure detected by the microphone 27 can be created in advance by performing a preliminary calibration.

[0133] Therefore, the analysis device 28 can analyze the magnitude of the sound pressure measured by the microphone 27 and identify the magnitude of the unknown external force applied to the strain sensor 1a by referring to a conversion table created in advance.

[0134] Next, an experimental method will be described in which the analysis device 28 analyzes the frequency spectrum of the sound detected by the microphone 27 and identifies the position on the strain sensor 1a where an external force has been applied.

[0135] 23, the strain sensor 1a received an external force at the positions of dotted lines (I) and (II) from the load device 26. A constant external force was applied to the strain sensor 1a from the load device 26, and the external forces applied to the strain sensor 1a were 0.5 N and 1.0 N. During this experiment, a constant flow rate was fed to the strain sensor 1a.

[0136] FIG. 24 is a graph showing the relationship between the position at which an external force is applied to the strain sensor of FIG. 14 and the frequency of the sound generated by the nozzle 14 when the magnitude of the external force is changed.

[0137] Figures 24(a) and 24(b) are graphs showing the frequency spectrum of the sound when an external force of 0.5 N is applied. Figures 24(c) and 24(d) are graphs showing the frequency spectrum of the sound when an external force of 1.0 N is applied. Figures 24(a) and 24(c) are graphs showing the frequency spectrum of the sound when an external force is applied at the position of the dotted line (I). Figures 24(b) and 24(d) are graphs showing the frequency spectrum of the sound when an external force is applied at the position of the dotted line (II).

[0138] When an external force is applied to the strain sensor 1a, sounds of multiple frequencies appear strongly. These are called peak frequencies. They are represented by multiple lines in the graphs shown in Figures 24(a) to 24(d).

[0139] The peak frequency of the sound is compared in the results when an external force of 0.5 N is applied to the strain sensor 1a. Comparing Fig. 24(a) with Fig. 24(b), the peak frequency of the sound is higher in Fig. 24(a) than in Fig. 24(b). In other words, the peak frequency of the sound when an external force is applied to the position of the dotted line (I) is higher than the peak frequency of the sound when an external force is applied to the position of the dotted line (II).

[0140] Similarly, the peak frequency of the sound is compared in the results when an external force of 1.0 N is applied to the strain sensor 1a. Comparing (c) of Fig. 24 with (d) of Fig. 24, the peak frequency of the sound in (c) of Fig. 24 is higher than the peak frequency of the sound in (d) of Fig. 24. In other words, the results show that the peak frequency of the sound when an external force is applied to the position of the dotted line (I) is higher than the peak frequency of the sound when an external force is applied to the position of the dotted line (II).

[0141] The experimental results shown in Figure 24 show that when an external force of the same magnitude is applied to the strain sensor 1a, the peak frequency of the sound detected by the microphone 27 decreases as the position of the external force applied to the strain sensor 1a approaches the tip of the notch 14b in the nozzle outer wall 14a.

[0142] From the above, a conversion table indicating the relationship between the position of a known external force applied to the strain sensor 1a and the peak frequency of the sound detected by the microphone 27 can be created in advance by performing a preliminary calibration.

[0143] Therefore, the analysis device 28 can identify the position of the external force in the strain sensor 1a by analyzing the peak frequency of the sound detected by the microphone 27 and referring to a conversion table created in advance.

[0144] FIG. 25 is a diagram showing an experiment in which the strain sensor 1a of FIG. 14 is curved.

[0145] 25, an experiment was conducted by manually bending the strain sensor 1a and adjusting the degree of bending that the strain sensor 1a received, without using the load application device 26. In addition, the flow rate of the fluid fed to the strain sensor 1a was controlled to be constant.

[0146] Fig. 26 is a graph showing the relationship between the frequency (vertical axis) of the sound generated by the nozzle 14 and the change in spectrum (shading) over time (horizontal axis) when the degree of curvature of the strain sensor 1a in Fig. 14 is changed, in the case where the flow rate of the fluid fed to the strain sensor 1a in the strain detection system 2a in Fig. 19 is kept constant at 10 L / min. In the shading of this graph, the whiter the color, the greater the sound intensity.

[0147] As shown by the multiple white lines in Fig. 26, sounds with peak intensities were confirmed at multiple frequencies. The results show that the greater the degree of bending that the strain sensor 1a receives (i.e., as time passes in the range of about 5 to 7 seconds), the higher the frequency of the sounds detected by the microphone 27 becomes (i.e., the white lines rise to the right).

[0148] From the above, a conversion table showing the relationship between the known degree of bending received by the strain sensor 1a and the frequency of the peak sound detected by the microphone 27 can be created in advance by performing a calibration in advance.

[0149] Therefore, the analysis device 28 can analyze the frequency of the sound detected by the microphone 27 and identify the degree of bending that the strain sensor 1a has received by referring to a conversion table created in advance.

[0150] As described above, the strain sensor 1a according to embodiment 2 includes a plate-shaped strain body made of an elastic material, the strain body having a flow path 13 penetrating the inside of the strain body, connecting the inlet 11 which is an opening provided on a first side surface of the strain body and the outlet 12 which is an opening provided on a second side surface of the strain body, the flow path 13 having a nozzle 14 in the middle of the flow path 13 which is a location where the cross-sectional area of ​​the flow path is locally small, and the nozzle 14 changes the characteristics of the sound generated by the nozzle 14 in response to the strain generated in the nozzle 14 due to the strain generated in the strain body being subjected to an external force.

[0151] As a result, this new type of strain sensor that uses fluid with one degree of freedom can detect the magnitude of an external force, the position of the external force, and the degree of bending, without using any electronic components or wiring.

[0152] The strain detection method of embodiment 2 is a strain detection method using the strain sensor 1a described above, and includes an installation step S1 of installing the strain sensor 1a at a location where it will be subjected to an external force, a flow-in step S2 of pumping a fluid into the inlet 11 of the strain sensor 1, and a detection step S5a of detecting a sound generated by the nozzle 14 of the strain sensor 1.

[0153] As a result, the new type of strain detection method, constructed using a new type of strain sensor that utilizes fluid with one degree of freedom, without using any electronic components or wiring, can identify the magnitude of the external force, the location of the external force, and the degree of curvature.

[0154] The distortion detection method according to the second embodiment includes an analysis step S6a of identifying the magnitude of the external force by analyzing the magnitude of the sound detected in the detection step S5a.

[0155] As a result, the new type of strain detection method can analyze the volume of the sound generated by the strain sensor and identify the magnitude of the unknown external force received by the strain sensor by referring to a pre-created conversion table.

[0156] The strain detection method according to the second embodiment includes an analysis step S6a of identifying the position of the strain sensor 1a that has received the external force by analyzing the frequency of the sound detected in the detection step S5a.

[0157] As a result, the new type of strain detection method can identify the position on the strain sensor that has been subjected to an external force by analyzing the frequency characteristics of the sound generated by the strain sensor and referring to a conversion table created in advance.

[0158] The strain detection method according to the second embodiment includes an analysis step S6a of identifying the degree of bending received by the strain sensor 1a by analyzing the frequency of the sound detected in the detection step S5a.

[0159] This new type of strain detection method can identify the degree of bending that the strain sensor has experienced by analyzing the frequency characteristics of the sound generated by the strain sensor and referring to a conversion table created in advance.

[0160] The strain sensor 1a according to the second embodiment does not necessarily have to include the suction and discharge port 16. The strain sensor 1a according to the second embodiment may also include the valve 15, the branch flow paths 17a and 17b, the expansion chambers 18a and 18b, and the walls 19a and 19b.

[0161] The strain sensor of the present disclosure can be attached to a robot hand that grasps an object. This allows it to be used as a strain sensor that detects external forces when the robot hand grasps an object. Furthermore, by providing the strain sensor with a suction and release port, the strain sensor can suck up an object and release the sucked object through the suction and release port. This allows the strain sensor to be used as an auxiliary material that assists the robot hand in grasping an object.

[0162] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that would come to mind by a person skilled in the art, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the spirit of the present disclosure.

[0163] As described above, the embodiment has been described as an example of the technology in the present disclosure. For this purpose, the attached drawings and detailed description have been provided. Therefore, among the components and steps described in the attached drawings and detailed description, not only the components and steps essential for solving the problem but also the components and steps that are not essential for solving the problem in order to illustrate the above implementation may be included. Therefore, the fact that the components and steps that are not essential are described in the attached drawings or detailed description should not be used to immediately determine that the components and steps that are not essential are essential.

[0164] Furthermore, since the above-described embodiments are intended to illustrate the technology in the present disclosure, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0165] The strain sensor and strain detection method according to the present disclosure can be used as a new type of strain sensor that utilizes fluid flow, for example, in a robot hand that grasps an object. [Explanation of symbols]

[0166] 1, 1a Strain sensor 2.2a Strain detection system 11 Entrance 12 Exit 13 Flow Path 14 Nozzles 14a Nozzle outer wall 14b, 14b1, 14b2 cut 15 Valve 15a, 15b Partition plate 16 Suction outlet 17a, 17b branch channels 18a, 18b Expansion chamber 19a, 19b Wall 21, 25 Fluid inlet device 22, 26 Load bearing device 23 Pressure Sensor 24, 28 Analyzer 27. Mike 221, 261 load cells 222, 262 Z-axis linear actuator 263 X-axis Linear Actuator

Claims

1. A plate-shaped strain body made of an elastic member is provided, The flexure body has a flow path that connects an inlet, which is an opening provided on a first side surface of the flexure body, and an outlet, which is an opening provided on a second side surface of the flexure body, and penetrates the inside of the flexure body, the flow path has a nozzle in the middle of the flow path, the nozzle being a location where a flow path cross-sectional area is locally small, The nozzle changes a flow path cross-sectional area in the nozzle in response to a strain generated in the nozzle when the strain generating body receives an external force, thereby changing a pressure of the fluid sent to the inlet, or the nozzle changes characteristics of a sound generated. Strain sensor.

2. The nozzle has a notch. The strain sensor according to claim 1 .

3. A method for detecting strain using the strain sensor according to claim 1 or 2, comprising the steps of: An installation step of installing the strain sensor at a location where the strain sensor is subjected to an external force; an inlet step of forcing a fluid into the inlet of the strain sensor; and detecting a pressure of the fluid fed to the inlet of the strain sensor. How to detect distortion.

4. the strain generating body has a valve that opens and closes the flow path closer to the outlet than the nozzle, the strain generating body has a suction and discharge port which is an opening leading to the flow path closer to the inlet than the valve, In the inflow step, the fluid is fed into the inlet at a flow rate that causes the opening to draw in outside air. The method for detecting distortion according to claim 3.

5. Further, the pressure of the fluid detected in the detection step is analyzed to identify the magnitude of the external force. The method for detecting distortion according to claim 3.

6. A method for detecting strain using the strain sensor according to claim 1 or 2, comprising the steps of: An installation step of installing the strain sensor at a location where the strain sensor is subjected to an external force; an inlet step of forcing a fluid into the inlet of the strain sensor; and detecting a sound generated by the nozzle of the strain sensor. How to detect distortion.

7. Further, the method includes an analysis step of identifying a magnitude of the external force by analyzing the magnitude of the sound detected in the detection step. The method for detecting distortion according to claim 6.

8. Further, the present invention includes an analysis step of identifying a position of the strain body that has received the external force by analyzing a frequency spectrum of the sound detected in the detection step. The method for detecting distortion according to claim 6.

9. Further, the method includes an analysis step of identifying the degree of bending of the strain body by analyzing the frequency spectrum of the sound detected in the detection step. The method for detecting distortion according to claim 6.

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