JP5608865B2 - Load measurement system - Google Patents

Description

  The present invention relates to a load measuring system for detecting a load acting on an object, and in particular, a load measuring system capable of stably measuring a triaxial load or a load distribution under various environments including a high temperature environment. About.

  Conventionally, a load sensor for detecting a force acting on an object such as mass or torque is used in many fields such as a scale, various testing machines, automobile parts, and other industries.

  Various types of load sensors are available, such as an elevator load detection device using a spring (see, for example, Patent Document 1) and a load measurement device using a piezoelectric element (see, for example, Patent Document 2). Exists.

  A load cell using a strain gauge is a load converter that converts a load into an electric signal, and is easy to process data after detecting the load, and is inexpensive and generally has a long life. (See, for example, Patent Document 3) and load sensors (see, for example, Patent Document 4). There are several types of load cells, such as a beam type and a diaphragm type, depending on the application. In general, metals such as iron, stainless steel, and aluminum are used as the material.

  When the load sensor measures the load applied to the object, especially when the load sensor and the object are in surface contact, information on the distribution of the load applied to the object is required. There have been proposed several load sensors for measuring such load distribution, such as a sheet sensor device (see, for example, Patent Document 5) and a tire ground contact load distribution detection device (see, for example, Patent Document 6). .

  Also, when the load sensor measures the load applied to the object, especially when precise work is required, the vertical component and the horizontal component are detected from the load applied to the load sensor, respectively. It is necessary to measure the load vector with high accuracy, and there are several methods for this purpose, such as a three-dimensional load distribution sensor using a strain gauge (for example, see Patent Document 7) and a triaxial load sensor (for example, see Patent Document 8). (Patent Documents 7 and 8).

  In addition, when the load sensor measures the load applied to the object, especially when the load sensor and the object are in surface contact, information on the distribution of the load applied to the object is required. As a load sensor for measuring such load distribution, a sensor sheet using a pressure-sensitive resistor such as pressure-sensitive conductive ink or pressure-sensitive conductive rubber has been proposed (see Patent Document 9). ing.

  In addition, the present inventors, as a force sensor for detecting the acting force of a robot arm, body, hand portion, etc., particularly a contact body such as a human body by being fixed to an object surface such as a robot or a medical bed. A flexible contact-type load measurement sensor (see Patent Document 10) capable of detecting the magnitude of the contact load (triaxial force) acting on the object surface from the contact body and the direction of the load simultaneously with the flexible deformation at the time of contact doing.

  Also proposed are tactile sensors using pressure sensitive elements (see Patent Document 11) that can be used for food robots, medical robots, industrial robots, pressure sensors for mechanical devices, computer input devices, etc. Has been.

  Furthermore, a tactile sensor using a pressure sensitive element (see Patent Document 11) that can be used for food robots, medical robots, industrial robots, pressure sensors for mechanical devices, computer input devices, and the like, from the outside There has also been proposed a sensor sheet (see Patent Document 12) using a pressure-sensitive resistor capable of detecting components corresponding to a plurality of different directions of applied force.

JP 2011-42481A JP-A-9-26366 JP 2008-216155 A JP 2008-157294 A Special table 2008-531177 gazette JP 2010-32263 A JP 2000-162054 A JP 2006-329653 A JP 2008-209384 A JP 2007-187502 A JP 2008-164557 A JP 2008-209384 A

  However, each of the conventional load sensors described in the above-mentioned patent documents has a weak point in heat resistance. For example, a sensor such as a load cell using a general strain gauge has an upper limit of the operating temperature range of about 40 ° C. to 60 ° C., and cases in which load measurement under higher temperature conditions is required are increasing. . In recent years, with the development of MEMS (Micro Electro Mechanical Systems) technology, thermal nanoimprinting has attracted attention as an advanced microfabrication technology in units of μm. Let's measure the load distribution applied to the mold used for thermal nanoimprinting In such a case, since the measurement object is heated to about 300 ° C. to 1500 ° C., there is a problem that the conventional load sensor cannot withstand.

  Moreover, since the load sensor which measures the triaxial direction load of patent document 7, 8 is the structure which arrange | positions a uniaxial load sensor for every component of a load direction, there exists a tendency for an apparatus to become complicated and enlarged. For example, when the target is a minute or fragile object, or when it is necessary to make the load sensor thin, there is a problem that the application becomes difficult.

  As shown in FIG. 24, the sensor sheet 201 described in Patent Document 9 is disposed above the substrate 210 and the substrate 210 on which a plurality of first electrodes 211 arranged in a strip shape and spaced apart from each other are disposed. The support member 230, a plurality of cylindrical core members 240 made of a material harder than the support member 230 and the cover layer 231, a flat cover layer 231 that receives external force, and the substrate 210. The strips are formed on the upper surface of the first electrode 211 and are spaced apart from each other and are arranged so as to intersect with the plurality of first electrodes 211 in a plan view, in a direction approaching the first electrode 211 in accordance with a force applied from the outside. A plurality of pressure sensitive resistors 21 arranged to cover the plurality of second electrodes 221 that can be displaced, the plurality of first electrodes 211, and the plurality of second electrodes 221, respectively. Comprises a 222, a large number of components has a complicated configuration. As described above, the sensor sheet 201 having a complicated structure in which a large number of components are laminated has a problem that it is difficult to reduce the size and weight and the manufacturing cost is high, in addition to the problem of poor heat resistance.

  The flexible contact type load measurement sensor described in Patent Document 10 includes a layer made of an elastic body and a skin layer arranged on the contact body side, and a load measurement layer arranged on the object side. On the elastic side of the substrate, the object side substrate disposed opposite to the substrate, the electrode formed on the lower surface of the elastic side substrate to turn on the microswitch, and the upper surface of the substrate facing the electrode The size of the contact load and the direction of the load are determined based on the position of the micro switch S that is turned on in response to the contact load acting on the object from the contact body. Although not shown, a sensor cell that is a unit for detection has a complicated structure with a large number of parts connected in series. As described above, the flexible contact-type load measuring sensor having a complicated configuration in which a large number of components are stacked has problems that it is difficult to reduce the size and weight, and the manufacturing cost is increased. Furthermore, since the flexible contact type load measuring sensor is configured to detect the load by utilizing the ON-OFF reaction of the micro switch S according to the load, the load resolution is not so good and the load measurement value is not good. However, there is a problem that the wiring for the micro switch S becomes complicated.

  Furthermore, the tactile sensor described in Patent Document 3 is made of a hard material, and a displaceable contact, a pressure-sensitive element that provides the contact on the surface, detects the displacement of the contact at a detection point, and outputs the detected contact. The pressure-sensitive element intersects the pressure-sensitive conductive sheet formed in a sheet shape, a plurality of first electrodes provided on the surface of the pressure-sensitive conductive sheet, and the first electrode and the pressure-sensitive conductive sheet Although the sensor cell, which is a unit having a plurality of second electrodes provided on the back surface of the pressure-sensitive conductive sheet, is not shown in the drawing, the number of parts of the plurality of first electrodes and the second electrodes connected in particular, particularly the crossing, is large. It has a complicated structure.

  In the tactile sensor having such a configuration, in addition to the problem that the heat resistance is poor, each sensor cell has a large number of comb-shaped or parallel electrodes (a plurality of intersecting first electrodes and second electrodes corresponding to a plurality of different directions). It is difficult to reduce the size of the device, and particularly when a large number of sensor cells are arranged close to each other, it is very difficult to draw out lead wires from all of the large number of first electrodes and second electrodes. Have difficulty. Further, the configuration of each sensor cell is complicated, and the efficiency in increasing the density of sensor cells is very poor. Furthermore, when converting the load detected by each sensor cell into a voltage proportional to the magnitude, an R / V conversion circuit that converts the resistance to voltage at a ratio of 1: 1 with respect to all the contact resistances is required. There is a problem that the conversion circuit becomes large, and it is difficult to reduce the size and weight, and the manufacturing cost is increased.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to have a simple, small and lightweight structure and to have a degree of design freedom, for example, various types including high temperature environments such as thermal nanoimprint. An object of the present invention is to provide a load measuring system having a load sensor capable of stably measuring a triaxial load or a load distribution under a harsh environment.

In order to achieve the above object, a load measuring system according to the present invention includes a contact portion that is a measurement object placed in contact with a load sensor, and a load sensor that measures a load acting on the contact portion. The load sensor is sandwiched between a pair of substrates on which electrodes are formed and the electrodes of the pair of substrates, and has a characteristic that an electric resistance value changes when a load is applied in a state where a voltage is applied. A conductive member comprising a conductive composite material, and the pair of substrates is formed by equally dividing the electrodes formed on one or both substrates into a plurality of planar electrode zones, When an arbitrary load P is applied to the contact portion, a shear load Pt, which is a horizontal component of the arbitrary load P, and a vertical load, which is a vertical component, are detected from the voltage change detection values of the electrode zones divided into the plurality. Pn A part or the whole of the arithmetic processing system for performing arithmetic processing separately is provided inside or outside the load sensor as a part of the configuration of the load sensor, and the conductive member is made of glassy carbon. To do.

Further, the load measuring system includes a contact portion that is a measurement object to be placed in contact with the load sensor, and a load sensor that measures a load acting on the contact portion, and the load sensor includes an electrode. A pair of substrates, and a conductive member made of a conductive composite material sandwiched between the electrodes of the pair of substrates and having a characteristic that an electric resistance value changes when a load is applied in a state where a voltage is applied. The pair of substrates is formed by equally dividing the electrodes formed on one or both substrates into a plurality of planar electrode zones and applying an arbitrary load P to the contact portion. An arithmetic processing system that performs arithmetic processing by separating the detected voltage change value of each of the electrode zones divided into the shear load Pt that is a horizontal component of the arbitrary load P and the vertical load Pn that is a vertical component of the arbitrary load P. Partly Whole, provided inside or outside of the load sensors as part of the configuration of the load sensor, the conductive member may be made of a composite material obtained by adding a vapor-grown carbon fibers in glassy carbon.

In addition, one of the pair of substrates may be replaced with a configuration in which the conductive member is integrally formed to serve as an electrode.

Further, the electrode is formed in four equally divided electrode zones in a plane where the contact portion is arranged .

The pair of substrates on which the electrodes are formed and the conductive member are both made of a biocompatible material .

The pair of substrates on which the electrodes are formed is made of a biocompatible material titanium (Ti), and the conductive member is made of a biocompatible material glassy carbon (GC) .

  Moreover, the electrode used for the load sensor according to the present invention is not particularly limited to the material as long as it has sufficient conductivity and heat resistance.

  The substrate on which the electrode used in the load sensor according to the present invention is formed is not particularly limited to a material as long as it has the heat resistance and can fix the electrode. Further, the substrate itself may be made of a conductive member made of a conductive composite material containing metal or GC, and replaced with a conductive member integrated as the electrode.

  In the load sensor according to the present invention, one or both of the pair of substrates on which the electrodes are formed is divided into a plurality of parts, and the divided electrodes are defined as zones 1, 2,. To distinguish. When an arbitrary load P is applied to the load sensor, the voltage of each zone changes due to the load being separated into each zone. Using this, it is possible to measure the arbitrary load P loaded on the load sensor separately from the relationship of voltage change in each zone into a shear load Pt which is a horizontal component and a vertical load Pn which is a vertical component. become. Further, by increasing the number of divisions of the electrodes, the resolution of the voltage change in each zone can be improved, thereby making it possible to accurately measure a detailed load distribution.

  Furthermore, since the calculation of the shear load Pt and the vertical load Pn requires a calculation process using the voltage detection value of each zone, a calculation having calculation processing means or control means for performing this calculation process. A part or the whole of the processing system may be provided inside or / and outside the load sensor as part of the configuration of the load sensor.

  According to the present invention, the electrical resistance value changes when a load is applied while applying a heat resistance and a voltage such as a pair of substrates on which electrodes are formed and a glassy carbon sandwiched between the pair of substrates. Because it has a load sensor with a simple structure and a conductive member made of a conductive composite material that also has characteristics, it is easy to make it compact and lightweight, and has a high degree of design freedom, for example, a high temperature environment such as thermal nanoimprint The effect of providing a load measurement system that can measure a triaxial load or a distributed load by separating a horizontal load and a vertical load out of loads applied to an object stably under various environments including There is.

  In the load sensor according to the present invention, biocompatible material titanium (Ti) is applied to the pair of substrates on which the electrodes are formed, and glassy carbon (GC) is applied to the conductive member. Accordingly, there is an effect that it is possible to provide a load measuring system that is small and lightweight and can measure a gripping force and a shearing force that can be applied to various medical instruments.

It is a schematic diagram which shows the concept of the load measurement system of one Embodiment (Example 1) of this invention. It is a schematic diagram for demonstrating notionally the structure of the load sensor of one Embodiment of this invention. It is a load vector figure which shows the relationship of the load isolate | separated into each zone divided | segmented into plurality at the time of the arbitrary load load to the load sensor of FIG. It is a typical electric circuit diagram of the load measuring system of FIG. FIG. 3 is a graph showing the relationship between the voltage Vm of each zone and the vertical load Pn of the arbitrary load P when an arbitrary load P is applied to the load sensor of FIG. Indicates a case where the conductive member used for the load sensor is GC / VGCF or GC, respectively. (A), (b) is a graph which shows the relationship between the voltage variation | change_quantity dVm of each zone calculated from the voltage Vm of FIG. 5 (a), (b), respectively, and the vertical load Pn, respectively. (A), (b) is a graph which shows the relationship between the sum V of the voltage variation of each zone calculated from the voltage variation dVm of FIG. 6 (a), (b), and the vertical load Pn, respectively. It is a graph which shows the result of having approximated the relationship of the sum total V of the amount of voltage changes of FIG. 7, and the vertical load Pn by the cubic equation by the least square method. It is a graph which shows the result of having compared the vertical load Pn calculated from the sum total V of the voltage change amount of each zone of FIG. 8, and the vertical load Pn measured by the load cell separately. In order to confirm the reproducibility of the load sensor of FIG. 1, graphs showing the relationship between the vertical load Pn when the vertical load Pn is applied five times and the sum V of the voltage change amount of each zone, (a), (b) Indicates the case where the conductive material of the load sensor is GC / VGCF or GC, respectively. 1 is a graph showing the relationship between the vertical load Pn and the total voltage change amount V of each zone when the load load direction angle at which the arbitrary load P is applied to the load sensor of FIG. 1 is changed to Φ = 0, 5, 10, 15 deg. (A) and (b) show cases where the conductive material of the load sensor is GC / VGCF, GC, respectively. (A), (b) is a graph which shows the relationship between voltage change (DELTA) V calculated from the voltage change amount dVm of FIG. 5 (a), (b), respectively, and the shear load Pt. (A), (b) is a graph which shows the result of having approximated the relationship between voltage change (DELTA) V of FIG. 12 (a), (b) and the shear load Pt by the quadratic equation by the least square method, respectively. (A), (b) is a graph which shows the result of having compared the shear load Pt calculated from voltage change (DELTA) V of FIG. 12 (a), (b), and the shear load Pt measured separately by the load cell, respectively. (A) and (b) were measured with a separate load cell and an arbitrary load P calculated from the vertical load Pn of FIGS. 7 (a) and 7 (b) and the shear load Pt of FIGS. 12 (a) and 12 (b), respectively. It is a graph which shows the result of having compared with arbitrary load P. FIG. The load load direction angle Φ of the arbitrary load P is represented by the ratio of the measured vertical load Pn and the shear load Pt, and is a graph showing the relationship between the measured vertical load Pn and the shear load Pt. It is a schematic diagram which shows the concept of the load measurement system of another embodiment (Example 2) of this invention. FIG. 18 is a schematic electric circuit diagram of the load measuring system of FIG. 17. It is a schematic diagram for demonstrating notionally the structure of the vertical load measurement of the load sensor of FIG. 20 is a graph showing the relationship between the voltage Vm between the upper and lower electrodes and the vertical load Pn when a vertical load Pn is applied to the load sensor of FIG. 20 is a graph showing the relationship between the voltage Vm between the upper and lower electrodes and the vertical load Pn when the vertical load Pn is applied to the load sensor of FIG. 19 having two conductive members of the same size made of GC. 20 is a graph showing the relationship between the voltage Vm between the upper and lower electrodes and the vertical load Pn when the size of the conductive member made of GC of the load sensor of FIG. 19 is changed. It is a schematic diagram which shows the concept of the load sensor in the load measurement system of another embodiment (Example 3) of this invention. It is a graph which shows the relationship between the voltage Vm between the upper and lower electrodes when the vertical load Pn is loaded on the load sensor of FIG. 23, and the vertical load Pn.

  Hereinafter, a specific example of an embodiment for carrying out the load measuring system of the present invention will be described with reference to the accompanying drawings. In these accompanying drawings, the same reference numerals are assigned to the same members even if the shapes of the constituent members in the first to third embodiments are different.

  As conceptually shown in FIG. 1, the load measuring system 1 of Example 1 according to an embodiment of the present invention uses a mold used for a measurement object, for example, thermal nanoimprint, via an electrical insulating member (not shown) as a contact portion 20. And a load sensor 10 that measures a load P acting on the contact portion 20.

  The load sensor 10 is sandwiched between a pair of upper and lower substrates 30 and 50 on which electrodes 31 and 51 are respectively formed, and the electrodes 31 and 51 of the pair of substrates 30 and 50 and applies a load P in a state where a voltage is applied. Thus, the conductive member 40 has both the characteristic that the electric resistance value changes and the heat resistance that is stable even in a high temperature environment exceeding 1000 ° C. The pair of substrates 30 and 50 and the conductive member 40 on which the electrodes 31 and 51 are formed respectively constitute a load detection layer.

  As the conductive member 40, glassy carbon (hereinafter referred to as GC) and a composite material GC / VGCF obtained by adding vapor grown carbon fiber (hereinafter referred to as VGCF) to GC were used. GC / VGCF is effective as a conductive member that can be used at high temperatures, similar to glassy carbon. Further, since GC and GC / VGCF are conductive composite materials, there is a property that an electric resistance value changes when a load P is applied while applying a voltage, and between the electrodes 31 and 51 of the pair of substrates 30 and 50. The loaded load P can be measured by measuring the voltage change. In this example, GC / 12 wt% VGCF added with 12 wt% of VGCF in mass ratio was used as GC.

  In this embodiment, the load detection layer is divided into four planar zones by dividing the lower substrate 50 on which the electrodes 51 are formed into four planes, and as shown in FIG. An x-axis and a y-axis are defined, and a z-axis is defined in a direction perpendicular to the load sensor 10. Further, each divided zone is defined as zone 1 with the positive direction of the x-axis as a reference, and is defined as zone 2, zone 3, and zone 4 counterclockwise.

  In this example, as shown in FIG. 2, a square column of SKD11 material having a shape of 10 mm × 10 mm × 5 mm was used for the mold 20.

  A glass epoxy substrate was used as the lower substrate 50, and four planar electrodes 51 were formed by etching, and the conductive member 40 was fixed on the lower electrode 51. In the example of FIG. 2, the upper substrate 30 in FIG. 1 is omitted, and the lower surface of the mold 20 is the upper electrode 31, and the conductive member 40 is sandwiched between the upper and lower electrodes 31, 51. Each of the lower substrate 50 and the conductive member 40 on which the electrodes were formed was divided into four pieces having a plane size of 4 mm × 4 mm and arranged in a plane of 10 mm × 10 mm. In order to fix the mold 20 to the load sensor 10, a screw hole having a diameter of 2 mm was opened at the center of the mold, and the mold 20 was fixed by an M2 shaped screw (not shown).

  Two types of load sensors 10 were produced when the conductive member 40 used for the load sensor 10 was GC and GC / 12 wt% VGCF, and the arbitrary load P was measured.

  When an arbitrary load P is applied to the mold 20 installed in the load sensor 10, the voltage in each zone changes due to the load being separated into each zone. As a result, the arbitrary load P applied to the mold 20 can be measured by separating it into a shear load Pt, which is a horizontal component, and a vertical load Pn, which is a vertical component, from the relationship of voltage changes in each zone.

  The measurement of the shear load Pt and the vertical load Pn requires an arithmetic process using the voltage detection value of each zone. Therefore, the load measurement system 1 of this embodiment is a voltage detection means for detecting the voltage of each zone. 120, the voltage to the electrode 51 formed on the upper electrode 31 and the lower substrate 50, the arithmetic processing means (or control means) 110 for taking the voltage detection value from the voltage detection means 120 and performing the arithmetic processing. And a stabilized power supply 130 for supplying power. These partial means or the whole of the arithmetic processing system 100 may be provided inside or / and outside the load sensor 10 as a part of the configuration of the load sensor 10.

  The load sensor 10 is an electric circuit in which a fixed resistance having a resistance value R = 100Ω is connected to each zone of the lower substrate 50 in the load detection layer, and is configured in parallel as shown in FIG. Moreover, since the electric resistance value of GC / 12 wt% VGCF and GC both changes when the load P is applied, it can be considered as variable resistances R1, R2, R3, and R4. Can be expressed as: In FIG. 4, symbol I is current, V0 is the supply voltage of the stabilized power supply 130, V1, V2, V3, and V4 are voltages between the upper and lower electrodes 31, 51 of each zone.

When the load applied to each zone formed in the load detection layer is defined as P1, P2, P3, P4, and the voltage change amount in each zone is defined as dV1, dV2, dV3, dV4, the load P1 applied to the zone 1 Can be expressed as a vector using the voltage change amount dV1 in zone 1 as shown in equation (1).

Since Zone 2, Zone 3, and Zone 4 can be considered in the same manner, loads P2, P3, and P4 applied to each zone can be expressed as a vector as shown in Expression (2).

  When these relationships are schematically represented, as shown in FIG. 3, an arbitrary load P applied to the load sensor 10 can be represented as a load vector diagram. FIG. 3 shows the relationship between the load Pm (m = 1, 2, 3, 4) applied to the four zones and the voltage change amount dVm (m = 1, 2, 3, 4) of the four zones.

The arbitrary load P is the sum of the loads Pm (m = 1, 2, 3, 4) applied to each zone. From this, the arbitrary load P can be expressed by a voltage change amount dVm (m = 1, 2, 3, 4) as shown in Expression (3).

In addition, since the arbitrary load P has x, y, z (axis) components, if the loads of the x, y, z components are respectively Px, Py, Pz, the arbitrary load P is newly expressed as shown in Expression (4). Can do.

  The vertical load Pn, which is the vertical component of the arbitrary load P, is expressed by the sum of the voltage change amounts dVm (m = 1, 2, 3, 4) in each zone as Pn = Pz from Equation (4). When the sum of the voltage change amounts dVm in each zone is V, the magnitude of the vertical load Pn can be obtained from the voltage change amount dVm in each zone.

Since the shear load Pt, which is the horizontal component of the arbitrary load P, can be expressed by the x and y components Px and Py of the arbitrary load P, the shear load Pt can be obtained by obtaining the magnitudes of Px and Py. Here, Px and Py are expressed as Vx and Vy as in equations (6) and (7), respectively, using the voltage change amount dVm (m = 1, 2, 3, 4) of each zone from equation (4). Can do. Therefore, the shear load Pt is expressed by Equation (8), and the magnitude of the shear load Pt can be obtained by obtaining the voltage change ΔV.

Since the arbitrary load P is a resultant force of the vertical load Pn and the shear load Pt, it can be obtained by Expression (9). Further, if the angle formed by the horizontal component and the vertical component of the arbitrary load P is Φ (load load direction angle), the vertical load Pn that is the vertical component of the arbitrary load P and the shear that is the horizontal component as shown in Equation (10). It can be obtained from the ratio of the load Pt.

  As described above, the load detection layer of the load sensor 10 is divided into four zones, and the load P arbitrarily applied by measuring the voltage change amount dVm (m = 1, 2, 3, 4) of each zone is vertical. It was possible to measure by separating into a vertical load Pn as a component and a shear load Pt as a horizontal component. The vertical load Pn can be expressed by the sum V of the voltage change amount of each zone, and the shear load Pt can be expressed by the voltage change ΔV. Further, the magnitude of the arbitrary load P and the load load direction angle Φ of the arbitrary load P can be measured from the measured values of the vertical load Pn and the shear load Pt.

Further, in order to obtain the voltage change amount dVm when calculating the load, Vm (m = 1, 2, 3, 4) is generated in the portion replaced with the variable resistance of each zone, and the initial voltage of each zone is Vm0. It is defined as (m = 1, 2, 3, 4), the voltage change amount dVm (m = 1, 2, 3, 4) of each zone is calculated | required using Formula (11), and a load is calculated. Therefore, the voltage between the upper and lower electrodes was measured.

  The load measurement result of the load sensor 10 is as follows.

[Example of vertical load measurement]
By calculating the change in voltage Vm (m = 1, 2, 3, 4) in each zone from the principle of load measurement, the vertical component which is the vertical component of the arbitrary load P applied to the mold 20 installed in the load sensor 10 The load Pn can be measured.

  The load load direction angle Φ of the arbitrary load P with respect to the center of the mold 20 installed in the load sensor 10 is changed to 0, 5, 10, 15 degrees, the arbitrary load P is applied, and the voltage Vm change in each zone and the arbitrary The relationship of the vertical load Pn which is the vertical component of the load P was calculated | required. The experiment conditions were a constant power supply voltage V0 = 5 V, and the change in voltage Vm of the load sensor 10 was measured by a sensor interface (Kyowa Denkisei PCD-300B).

Further, in order to apply an arbitrary load P to the center of the mold 20, a SUS 5 mm diameter sphere is installed in a screw hole (not shown) in the center of the mold 20, and the sphere apex The load direction angle Φ was changed. A small desktop test (Shimadzu EZ-500N) was used for loading, and an arbitrary load P was applied at a load loading speed of 0.5 mm / min. At this time, the vertical load Pn and the shear load Pt applied to the sensor can be calculated from the values measured by the load cell by the equations (12) and (13).

  As an example, FIG. 5 shows the relationship between the change in voltage Vm in each zone and the vertical load Pn that is the vertical component of the arbitrary load P when an arbitrary load P is applied at Φ = 0 deg.

  When the conductive member 40 used for the load sensor 10 is GC / VGCF or GC, as shown in FIGS. 5A and 5B, the vertical load Pn increases as shown in FIGS. It can be confirmed that the voltage Vm of the zone is decreasing.

  Since the load sensor 10 outputs the voltage change amount dVm of each zone, the voltage change amount dVm of each zone was obtained from the result obtained in FIG. 5 using Equation (11). 6A and 6B show the relationship between the voltage change amount dVm and the vertical load Pn in each zone. When the conductive member 40 is GC / VGCF or GC, it can be confirmed that the voltage change amount dVm of each zone increases as the vertical load Pn increases.

  From the load measurement principle, in order to measure the vertical load Pn, it is necessary to obtain the sum V of the voltage change amount dVm of each zone. Therefore, the sum V of the voltage change amount dVm of each zone is calculated from the voltage change amount dVm of each zone obtained in FIGS. 6A and 6B by Equation (5). FIG. 7 shows the relationship between the sum V of the voltage variation dVm and the vertical load Pn thus obtained. From FIG. 7, it can be confirmed that as the vertical load Pn increases, the total sum V of the voltage change amount dVm in each zone increases.

  FIG. 8 shows the result of approximating the relationship between the sum V of the voltage change amount dVm and the vertical load Pn by a cubic equation by the least square method by exchanging both axes in FIG.

An empirical formula obtained when GC / VGCF is used as a conductive member is shown in Equation (14), and an empirical formula obtained when GC is used as a conductive member is shown in Equation (15).

  Therefore, the load sensor 10 can measure the vertical load Pn, which is a vertical component of an arbitrary load P, by obtaining the total sum V of the voltage change amounts dVm of each zone and substituting it into the obtained empirical formula.

  Therefore, the equation is based on the vertical load Pn obtained by substituting the sum V of the voltage change amount dVm in each zone into Equations (14) and (15) and a value measured by a separate load cell (SM-500 manufactured by Interface). The result of comparing the vertical load Pn calculated using (12) is shown in FIG. From FIG. 9, the vertical load Pn detected by the load cell and the vertical load Pn detected by the load sensor 10 coincide with each other, and the load sensor 10 can be used regardless of whether the conductive material used for the load detection layer is GC / VGCF or GC. It was found that the vertical load Pn can be measured accurately.

  In order to clarify the reproducibility of the load sensor 10, FIGS. 10A and 10B show the relationship between the vertical load Pn when the vertical load Pn is applied 5 times and the sum V of the voltage change amount dVm in each zone. . 10A and 10B, the sum V of the vertical load Pn and the voltage change amount dVm in each zone shows the same tendency even after five measurements, so the reproducibility of the load sensor 10 is confirmed. We were able to.

  In order to clarify whether the vertical load Pn, which is the vertical component of the arbitrary load P, can be measured even if the direction in which the arbitrary load P is applied is changed, the load direction angle Φ of the arbitrary load is set to 0, 5, 10, 15 deg. 11A and 11B show the relationship between the vertical load Pn at each angle and the total sum V of the voltage change amount dVm in each zone when changed.

  11 (a) and 11 (b), it can be confirmed that the relationship between the sum V of the voltage change amount dVm of each zone and the vertical load Pn follows the same locus even when the load direction angle Φ of the arbitrary load is changed. . Therefore, it was found that the load sensor 10 can measure the magnitude of the vertical load Pn that is a vertical component of the arbitrary load P applied from an arbitrary direction.

[Measurement example of shear load]
In order to measure the shear load Pt, which is the horizontal component of the arbitrary load P, from the load measurement principle, it is necessary to obtain the voltage change ΔV. FIGS. 12A and 12B show the relationship between the voltage change ΔV obtained from the obtained voltage change amount dVm of each zone using Equation (8) and the shear load Pt.

  12A and 12B, the voltage change ΔV increases as the shear load Pt increases, and it can be confirmed that the voltage change ΔV becomes a constant value when the shear load Pt exceeds a certain value.

  FIGS. 13A and 13B show the results of obtaining the relationship between the voltage change ΔV and the shear load Pt within a range in which the voltage change ΔV changes and approximating with a quadratic equation by the least square method.

Further, an empirical formula obtained when GC / VGCF is used as a conductive member is shown in Formula (16), and an empirical formula obtained when GC is used as a conductive member is shown in Formula (17).

  13 (a) and 13 (b), it can be confirmed that the relationship between the voltage change ΔV and the shear load Pt changes in the same locus even when the load load direction angle Φ of the arbitrary load P is changed.

  Therefore, the load sensor 10 can measure the shear load Pt which is a horizontal component of an arbitrary load P by obtaining the voltage change ΔV of each zone and substituting it into the obtained empirical equations (16) and (17). it can. Therefore, the result of comparing the shear load Pt obtained by substituting the voltage change ΔV of each zone into the equation (15) and the shear load Pt calculated by the equation (13) from the value measured by a separate load cell is shown in FIG. ) And (b).

  14 (a) and 14 (b), it can be confirmed that the shear load Pt calculated from the arbitrary load P measured by the load cell and the shear load Pt detected by the load sensor 10 match. Therefore, it was found that the load sensor 10 can measure the magnitude of the shear load Pt, which is the horizontal component of the arbitrary load P, within the range in which the voltage change ΔV changes.

[Arbitrary load measurement example]
The magnitude of the arbitrary load P can be obtained from the vertical load Pn that is the vertical component of the arbitrary load P measured from the equation (9) and the shear load Pt that is the horizontal component. Accordingly, FIGS. 15A and 15B show the results of comparing the arbitrary load P detected by the load sensor 10 within a range in which the shear load Pt can be measured with the value measured by a separate load cell.

  15A and 15B, it can be confirmed that the value of the arbitrary load P detected by the load sensor 10 and the value of the arbitrary load P detected by the load cell match. Therefore, it was found that the load sensor 10 can measure the magnitude of the arbitrary load P.

  From the load measurement principle, the load load direction angle Φ of the arbitrary load P can be expressed by the ratio of the vertical load Pn that is the vertical component of the measured arbitrary load P and the shear load Pt that is the horizontal component. The relationship between the measured vertical load Pn and shear load Pt is shown in FIG.

  From FIG. 16, it can be confirmed that the load load direction angle Φ of the arbitrary load P and the load load direction angle Φ of the arbitrary load P obtained from the ratio of the vertical load Pn measured by the load sensor 10 and the shear load Pt are the same.

From the above load measurement results, the following was found.
(1) By measuring the voltage Vm change in each zone, the arbitrary load P applied to the mold can be separated into a vertical load Pn of a vertical component and a shear load Pt of a horizontal component.
(2) When a load P is applied to the mold 20 installed in the load sensor 10 from an arbitrary direction, a vertical load that is a vertical component of the arbitrary load P is measured by measuring the sum V of the voltage change amount dVm of each zone. Able to measure the size of Pn.
(3) When a load P is applied to the mold 20 installed in the load sensor 10 from an arbitrary direction, the shear load Pt, which is a horizontal component of the arbitrary load P, is measured by measuring the relationship between the voltage change amounts dVm of each zone. Be able to measure the size of
(4) The load sensor 10 can measure the magnitude of the arbitrary load P from the relationship between the measured vertical load Pn and the shear load Pt.
(5) The load sensor 10 can measure the load load direction angle Φ to which the arbitrary load P is applied from the relationship between the measured vertical load Pn and the shear load Pt.
(6) The load can be measured similarly even if the conductive member used for the load sensor 10 is changed to GC / VGCF or GC.

  The load sensor 10 of this embodiment can measure a single load vector but cannot measure the distribution of the load vector. Therefore, the distribution of a plurality of load vectors can be measured by increasing the number of divisions of the lower electrode 51 used for the load detection layer.

  The load measuring system 1A of Example 2 according to another embodiment of the present invention measures the gripping force and the shearing force by using the principle of the flexible contact sensor for triaxial load measurement, as conceptually shown in FIG. The basic configuration is the same as that of the first embodiment except that the load sensor 10A is a small and lightweight load sensor made of a biocompatible material that can be applied to various medical instruments.

  In particular, GC was selected as the conductive member 40A used for the load sensor 10A. In addition to heat resistance, GC has excellent electrical conductivity, workability, chemical resistance, low dust generation, good blood and biological tissue compatibility, and load while applying voltage. It also has the property that the electrical resistance value changes by loading.

  The basic configuration of the load sensor 10A of this embodiment includes an upper electrode 30A, a conductive member 40A made of GC, a fixing film 60A, and a lower electrode 50A. The fixing film 60A is used to fix the conductive member 40A to the upper surface of the lower electrode 50A, and is preferably a biocompatible electrical insulating member.

  In the load sensor 10A of this embodiment, the relationship between the vertical load and the voltage change when the conductive member 40A made of GC is changed to a small size suitable for the load sensor 10A that can be used for various medical instruments is measured as follows. Then, the function was evaluated.

  In the load measuring system 1A of this embodiment, biocompatible titanium (Ti) is used for the upper and lower electrodes 30A and 50A of the load sensor 10A, and the dimensions are 25 mm × 25 mm and the thickness is 0.3 mm. Further, in order to investigate the effect of changing the size of the GC conductive member 40A, 3 of 10 mm × 10 mm × 0.5 mm, 5 mm × 5 mm × 0.5 mm, 2.5 mm × 2.5 mm × 0.5 mm The size of the kind was compared.

  As shown in FIG. 18, a voltage dividing circuit was obtained by sandwiching a GC conductive member 40A between the upper and lower electrodes 30A and 50A of titanium from above and below and arranging a resistance of R = 100Ω on the upper electrode 30A. Since the electric resistance Rx changes when a load is applied while applying the voltage V0, the GC conductive member 40A can be considered as a variable resistance, and the voltage between the upper and lower electrodes 30A and 50A is defined as Vm and measured. Went.

[Example of vertical load measurement]
A vertical load was defined as Pn using a desktop universal testing machine (Shimadzu Corporation EZ-L-500N), and the vertical load Pn was applied to 100N. In order to keep the load loading speed constant at 0.5 mm / min and to lay a Teflon (registered trademark) sheet as an electrical insulating member 60B on the upper surface of the upper electrode 30A as shown in FIG. 19, and to apply the load Pn uniformly. A spherical seat 70 was installed, and a load Pn was applied to the center of the load sensor 10A. The spherical seat 70 has a diameter of 24.4 mm and a weight of 60.6 g. The stabilized power supply 130 was used for voltage supply (FIG. 17), the supply voltage V0 was kept constant at 5V, and the voltage Vm between the upper and lower electrodes 30A and 50A was measured.

  FIG. 20 shows the relationship between the voltage Vm between the upper and lower electrodes 30A and 50A and the vertical load Pn when a vertical load Pn is applied to the load sensor 10A.

  As can be seen from FIG. 20, the voltage Vm between the upper and lower electrodes 30A and 50A decreases as the vertical load Pn increases. Further, while the supply voltage V0 = 5V, the voltage Vm between the upper and lower electrodes 30A, 50A changes from about 2V. This is because the spherical seat 70 is used for the load sensor 10A, and the weight of the spherical seat 70 is loaded as an initial load.

  Further, the measurement of the voltage Vm and the vertical load Pn is performed 10 times, and the voltage Vm between the upper and lower electrodes 30A and 50A changes in a similar manner due to the increase of the vertical load Pn. I understand that.

  FIG. 21 shows the relationship between the voltage Vm between the upper and lower electrodes 30A, 50A and the vertical load Pn when the vertical load Pn is applied to two GC conductive members 40A of the same size.

  From FIG. 21, if the size of the GC conductive member 40A is the same, the voltage Vm between the upper and lower electrodes 30A and 50A when the vertical load Pn is applied is the same even when the different GC conductive member 40A is used. You can see that it changes.

  Further, the relationship between the voltage Vm and the vertical load Pn when the size of the GC conductive member 40A is changed to three types of 10 mm × 10 mm, 5 mm × 5 mm, and 2.5 mm × 2.5 mm with a thickness of 0.5 mm. Is shown in FIG.

  From FIG. 22, it can be seen that regardless of the size of the conductive member 40A, when the vertical load Pn increases, the voltage Vm between the upper and lower electrodes 30A, 50A decreases and shows the same tendency.

ここで、Ｒ＝ＲｘはＧＣの導電性部材４０Ａの抵抗値、ρは体積抵抗率、Ｌは厚さ、Ａは電極との接触面積である。式（１）から導電性部材４０Ａのサイズが小さいほうが上部及び下部電極３０Ａ、５０Ａ間の電圧Ｖｍは大きいはずだが、図２２ではサイズが小さいと上部及び下部電極３０Ａ、５０Ａ間の電圧Ｖｍが小さくなる。これは、ＧＣの結晶構造がアモルファスであるため、荷重Ｐｎを負荷したことにより結晶構造が配列され、電流Ｉが流れ易くなったためだと考えられる。 However, in general, the electrical resistance value varies in inverse proportion to the contact area with the electrode, as represented by Equation (18).

Here, R = Rx is the resistance value of the GC conductive member 40A, ρ is the volume resistivity, L is the thickness, and A is the contact area with the electrode. From equation (1), the voltage Vm between the upper and lower electrodes 30A, 50A should be larger when the size of the conductive member 40A is smaller, but in FIG. 22, the voltage Vm between the upper and lower electrodes 30A, 50A is smaller when the size is small. Become. This is presumably because the crystal structure of GC is amorphous, so that the crystal structure is arranged by applying the load Pn, and the current I easily flows.

The load sensor 10A with good biocompatibility that can measure the gripping force and the shearing force was found from the above load measurement results.
(1) The voltage Vm between the upper and lower electrodes 30A and 50A decreases due to an increase in the vertical load Pn.
(2) Since the same voltage Vm change occurs even when the vertical load Pn is repeatedly applied, reproducibility is present.
(3) When a vertical load Pn is applied to two GC conductive members 40A of the same size, the change in the voltage Vm between the upper and lower electrodes 30A, 50A is the same, so the influence of individual differences can be ignored. .
(4) The voltage Vm between the upper and lower electrodes 30A, 50A is decreased by increasing the vertical load Pn even if the size of the GC conductive member 40A is reduced.
(5) When the size of the GC conductive member 40A is reduced, the voltage Vm between the upper and lower electrodes 30A, 50A tends to change greatly.

  From the above, it has been found that even if the GC size is changed small, it can be similarly used as the conductive member 40A of the load sensor 10A. Therefore, it is recognized that the load sensor 10A according to this embodiment can be applied even when a sufficient size reduction is required so that the load sensor 10A can be mounted on various medical instruments.

  In this embodiment, the shear load Pt due to the division of the load detection layer such as the electrode is not measured, but the shear load Pt is sufficiently measured by dividing the load detection layer as in the first embodiment. Is possible.

  As shown in FIG. 23, the load measuring system of Example 3 according to another embodiment of the present invention is the same as Example 2 except that the load sensor 10B is configured by integrating the lower electrode and the conductive member. This is the basic configuration.

  The load sensor 10B of this embodiment uses a conductive member made of GC that is integrally configured to have both an upper electrode 30B made of titanium (Ti) and a lower electrode 40B, and the lower substrate in the above embodiment is omitted. This is the configuration. As a result, it is possible to realize a load sensor that can be applied to various medical devices that are thinner and lighter and thinner.

  In order to confirm the operation of the load sensor 10B of Example 3 in which the configuration is simplified by integrating the lower electrode and the conductive member in this manner, the measurement was performed as follows in the same manner as in Example 2.

[Example of vertical load measurement]
FIG. 24 shows an example of the relationship between the voltage Vm between the upper and lower electrodes 30A and 40B and the vertical load Pn when the load sensor 10B is loaded with the vertical load Pn.

  From FIG. 24, it can be seen that when the vertical load Pn increases, the voltage Vm between the upper and lower electrodes 30A, 40B decreases as in the above embodiment.

  Therefore, it is recognized that the load sensor 10B according to this embodiment can be applied as a load sensor even when one or both of the electrodes and the conductive member are integrally configured.

  In this embodiment, the shear load Pt due to the division of the load detection layer such as the electrode is not measured. However, as in the first embodiment, the measurement of the shear load Pt is sufficient by dividing the load detection layer. Is possible.

  Since the load measuring system according to the present invention has a load sensor capable of measuring triaxial load or load distribution stably under various environments including high temperature environment while having high heat resistance, thermal nanoimprint, etc. It can be used in a wide range of industrial fields including measurement of the surface pressure of a mold during pressurization in the field of advanced micromachining technology. In addition, the load sensor according to the present invention has a simple structure, and can be easily reduced in size, weight, and thickness, and thus has a degree of freedom in design. For example, various medical treatments that require delicate work, such as when handling a living body. It can be suitably used in a field or the like without degrading the accuracy of the device.

1, 1A, 1B; Load measuring system 10, 10A, 10B; Load sensor 20; Mold (contact part)
30; (Upper) substrate 30A, 30B; Upper electrode 31; (Upper) electrode 40, 40A; Conductive member 40B; Lower electrode (GC)
50; (lower) substrate 50A; lower electrode 51; (lower) electrode 60A; fixing film 60B; electrical insulating member 70; spherical seat 100; arithmetic processing system 110; arithmetic processing (or control) means 120; voltage detection means 130 ; Stabilized power supply dVm; (m = 1, 2, 3, 4) Voltage change amount (in each zone) GC; Glassy carbon P; Arbitrary load Pm; (m = 1, 2, 3, 4) Load in each zone Load Pn; vertical load Pt; shear load Px; x (axis) component of arbitrary load Py; y (axis) component of arbitrary load Pz; z (axis) component of arbitrary load R; (electrical) resistance (resistance value) )
R1, R2, R3, R4; (resistance of each zone) variable resistance Rx; (electrical) resistance (resistance value) (variable resistance)
Ti; Titanium V; Total voltage change V0; Power supply voltage VGCF; Vapor growth carbon fiber Vm; (m = 1, 2, 3, 4) Voltage Vm0 (between upper and lower electrodes) Vm0; (m = 1, 2, 3, 4) Initial voltage in each zone ΔV; Voltage change Φ; Load load direction angle

Claims (6)

A load measurement system having a contact portion that is a measurement object to be placed in contact with a load sensor, and a load sensor that measures a load acting on the contact portion,
The load sensor is
A pair of substrates on which electrodes are formed;
A conductive member made of a conductive composite material that is sandwiched between the electrodes of the pair of substrates and has a characteristic that an electric resistance value changes by applying a load in a state where a voltage is applied;
The pair of substrates is formed by equally dividing the electrodes formed on one or both substrates into a plurality of planar electrode zones,
When an arbitrary load P is applied to the contact portion, a shear load Pt, which is a horizontal component of the arbitrary load P, and a vertical load, which is a vertical component, are detected from the voltage change detection values of the electrode zones divided into the plurality. A part or the whole of the arithmetic processing system that performs the arithmetic processing separated into Pn is provided inside or outside the load sensor as a part of the configuration of the load sensor ,
The load measuring system , wherein the conductive member is made of glassy carbon . A load measurement system having a contact portion that is a measurement object to be placed in contact with a load sensor, and a load sensor that measures a load acting on the contact portion,
The load sensor is
A pair of substrates on which electrodes are formed;
A conductive member made of a conductive composite material that is sandwiched between the electrodes of the pair of substrates and has a characteristic that an electric resistance value changes by applying a load in a state where a voltage is applied;
The pair of substrates is formed by equally dividing the electrodes formed on one or both substrates into a plurality of planar electrode zones,
When an arbitrary load P is applied to the contact portion, a shear load Pt, which is a horizontal component of the arbitrary load P, and a vertical load, which is a vertical component, are detected from the voltage change detection values of the electrode zones divided into the plurality. A part or the whole of the arithmetic processing system that performs the arithmetic processing separated into Pn is provided inside or outside the load sensor as a part of the configuration of the load sensor,
The load measuring system, wherein the conductive member is made of a composite material obtained by adding vapor grown carbon fiber to glassy carbon . 3. The load measuring system according to claim 1 , wherein one of the pair of substrates is replaced with a configuration in which one of the substrates is integrally formed with the conductive member serving as an electrode. The load measuring system according to claim 1 , wherein the electrode is formed in four equally divided electrode zones in a plane in which the contact portion is disposed. The load measuring system according to any one of claims 1 to 4 , wherein each of the pair of substrates on which the electrodes are formed and the conductive member are made of a biocompatible material. 2. The load according to claim 1 , wherein the pair of substrates on which the electrodes are formed is made of biocompatible material titanium (Ti), and the conductive member is made of biocompatible material glassy carbon (GC). Measuring system.

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