JP7124809B2 - Load measuring device - Google Patents

Description

The present invention relates to a load measuring device.

A load measuring device is a device that deforms according to a contacting object and measures the load received from the object. For example, in joint work between humans and robots, there are various types of contact between the robot and the human body, and the frequency of contact is high. In addition, investigations have been made to prevent danger to the human body upon contact, and for example, flexible materials are used in the detection portion of the sensor. Furthermore, in order to grasp the contact state in detail, a method of detecting a two-dimensional distributed load is also being studied. However, since the contact load received from the contact body is a three-axis force, it is difficult for the two-dimensional sensor to detect the magnitude and direction of the load.

On the other hand, as a load measuring sensor capable of detecting the magnitude and direction of the contact load acting on the surface of the object from the contacting body, the 6-axis force sensor detects the force applied to the force acting part by dividing it into six axial forces. Sensors, multiaxial force sensors having piezoresistive elements as strain detecting elements, and the like have been proposed. In addition, an electromagnetic induction type force sensor, a capacitive type force sensor, and the like are also being considered.

In relation to a load measuring device, for example, in Patent Document 1, a layer made of an elastic body arranged on the contact body side and a load measuring layer arranged on the object side are provided. An elastic body-side substrate and an object-side substrate arranged opposite to each other with a gap therebetween. A flexible contact load measuring sensor is disclosed that is characterized by detecting the magnitude and direction of a load.

On the other hand, a shape measuring device is a device that measures the three-dimensional shape of an object by coming into contact with the object. In relation to the shape measuring device, for example, Patent Document 2 describes a three-dimensional shape measuring device that scans the three-dimensional shape of an object with a contact-type probe supported by two or more elastic bodies to measure the shape, A three-dimensional shape measuring apparatus is disclosed in which two or more elastic bodies supporting a contact probe have different elastic moduli.

Furthermore, a three-dimensional position calculation device is a device that calculates the position of a point to be measured in a three-dimensional space (hereinafter sometimes referred to as "three-dimensional coordinate position"). In relation to the three-dimensional position calculation device, for example, Patent Document 3 discloses that a moving body to be measured is photographed, and a plurality of cameras including imaging elements with different exposure timings for each line and a light beam directed toward the moving body are disclosed. , detection means for detecting that the moving object has reached a measurement position measured by a plurality of cameras, and exposure of the plurality of cameras so that all lines of the plurality of cameras are in an exposure state. and a control means for controlling the light projecting means so as to project light during a period in which all lines of a plurality of cameras are in an exposure state; A three-dimensional measuring device is disclosed, which is characterized by comprising three-dimensional distance calculation means for calculating distance.

Further, in relation to the three-dimensional position calculation device, Patent Document 4 discloses a three-dimensional position calculation device in which an absolute three-dimensional displacement amount is measured using a laser displacement meter that emits a laser beam for distance measurement and measures a distance. A displacement sensing device is disclosed.

JP 2007-187502 A Japanese Patent Application Laid-Open No. 2003-156323 JP 2014-95631 A JP-A-2000-205815

Conventional technologies related to load measuring devices have disclosed load measuring sensors capable of detecting the magnitude and direction of the contact load acting on the surface of an object from a contact body. However, when such a sensor is applied to, for example, grasping the seating condition of a seat, accurate load measurement cannot be performed. That is, the load measuring sensor according to the conventional technology does not consider the inclination of the measurement surface when a load acts. In this case, the load measuring sensor tilts according to the deformation of the seat surface. Therefore, the direction of the measurement axis of the sensor changes according to the deformation state of the seat surface.

In one example of deformation, the tilt angle may be from 30 degrees to 50 degrees. For example, the load applied to the Z axis changes the measured value by about 40% due to the influence of the tilt of the measurement axis, and the amount of change is It differs according to the deformation state of the seat surface. Therefore, when the surface to be measured is deformed, the state of deformation is grasped and the load to be measured is corrected according to the state of deformation, thereby performing accurate load measurement. In other words, it is necessary to measure the deformation simultaneously with the measurement of the load, but in the conventional technology, it is difficult to measure these simultaneously, and there is a problem that a large error occurs in the load measurement.

On the other hand, conventional technology related to shape measurement devices sometimes requires probes, digital cameras, inertial sensors, etc. as sensors for measuring three-dimensional shapes. , may have a considerable effect on the elastic properties. In other words, depending on the size, rigidity, etc. of the sensor, there are cases where the operating conditions such as the placement and operation of the object to be measured are restricted. For example, in order to obtain a three-dimensional shape by scanning the surface of an object to be measured with a probe, a probe having a predetermined size and rigidity is required, and a scanning device for scanning the probe is also required. Therefore, a measurement space of a certain size is required, and measurement becomes difficult unless the arrangement and movement of the object to be measured are restricted. For this reason, there is a possibility of causing a problem that the change in shape of the object to be measured cannot be evaluated appropriately. In this regard, even in the three-dimensional shape measuring apparatus disclosed in Patent Document 2, the probe contacts the object to be measured during measurement, so there are problems such as fluctuations in contact force during operation and damage to the object to be measured. In addition, it is difficult to measure the shape of a contact surface with which a plurality of measurement objects are in contact. In short, the shape measuring apparatus according to the prior art has a problem that highly accurate shape measurement cannot be performed in various operating conditions of the object to be measured.

Furthermore, in the prior art relating to three-dimensional measuring devices, since a digital camera, a projector, or a wireless device is used as a sensor for measuring a three-dimensional shape, the placement and movement of the object to be measured are restricted. For this reason, there is a problem that three-dimensional position measurement cannot be performed, for example, under operating conditions in which objects to be measured are in close contact with each other.

The reason why conventional three-dimensional measuring devices are limited in the arrangement and movement of the object to be measured is due to problems such as the size of the sensor and the installation space. In other words, when using image information from a digital camera or reflected light from a light projector, it is necessary to consider the measurement range, the number of pixels, or the light irradiation range. Therefore, in order to obtain a predetermined measurement range, it is necessary to separate the digital camera from the object to be measured by a predetermined distance. Similarly, the projector and the laser displacement meter must be separated from the object to be measured by a predetermined distance. Furthermore, there is also the problem that it is difficult to measure surfaces where objects to be measured are in close contact with each other. On the other hand, wireless devices can be placed in close contact with the object to be measured, but because of their high rigidity and fixed size, they can affect the appearance and structure of the object to be measured. , there is a problem that the characteristics of the object to be measured are disturbed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a load measuring apparatus capable of measuring more accurately with a simpler configuration regardless of the properties of the object to be measured. and

In order to achieve the above objects, the load measuring device according to claim 1 is a load measuring device that is brought into contact with an object to be measured and measures the load applied to the object to be measured as a load vector. a measurement terminal whose position changes in a dimensional space; a plurality of elastic bodies each having one end connected to the measurement terminal and having electrical characteristics that change with displacement; and the electrical properties of each of the plurality of elastic bodies. a plurality of three -dimensional position calculation devices , including a measurement unit that measures characteristics, and a calculation unit that calculates the spatial positions of the measurement terminals based on the electrical characteristics measured by the measurement unit; a plurality of measurement terminals connected to the other ends of the plurality of elastic bodies of the three-dimensional position calculation device and whose positions change according to the shape of the object to be measured; A three-dimensional position calculation device is connected , and the relationship between the displacement amount of the plurality of elastic bodies and the applied force is a predetermined second characteristic, and the calculation unit calculates force corresponding to the amount of displacement calculated based on the electrical characteristics measured by the measuring unit, the calculated spatial position of the measurement terminal, and each of the plurality of elastic bodies when contact is made; The directions of the forces derived using the positions of the points corresponding to the ends are obtained for each of the measurement terminals, the forces corresponding to the measurement terminals are synthesized, and the load is calculated as a vector.
Further, the invention according to claim 2 is the invention according to claim 1, wherein each of the plurality of elastic bodies is a conductive elastic body having conductivity and the electrical characteristic being a resistance value, and A relationship between the length of each of the plurality of elastic bodies and the resistance value is a predetermined first characteristic, and the calculation unit calculates the predetermined characteristic from the resistance value measured by the measurement unit. The spatial position of the measurement terminal is calculated using the length of each of the plurality of elastic bodies obtained according to the first characteristic.
In the invention according to claim 3, in the invention according to claim 2, the calculation unit is configured to calculate the length of each of the plurality of elastic bodies around a point corresponding to the other end of the plurality of elastic bodies. The point of intersection of a plurality of spheres with a radius of 100 mm is calculated as the spatial position of the measurement terminal.
In the invention according to claim 4, in the invention according to claim 3, when there are a plurality of the intersections, the calculation unit calculates a midpoint of the plurality of intersections as the spatial position of the measurement terminal. do.
According to a fifth aspect of the invention, in the invention according to any one of the first to fourth aspects, the number of the plurality of elastic bodies is at least three.

Moreover, the invention according to claim 6 is the invention according to any one of claims 1 to 5 , wherein the object to be measured is an elastic body.

ADVANTAGE OF THE INVENTION According to this invention, it is effective in the ability to provide the load measuring device which can measure more correctly with a simpler structure regardless of the property of a measuring object.

According to the first embodiment, (a) is a perspective view showing a seat as an example of a measurement object, (b) is a cross-sectional view showing a deformation state of the seat cushion surface when the seated person is seated, (c ) is a perspective view showing an example of a model of a seat cushion using the finite element method. (a) is a plan view of the load measuring device and a perspective view showing the arrangement of the load measuring device on the seat cushion, and (b) is the relationship between the load of the conductive elastic body and the electrical resistance, according to the first embodiment. 1 is a graph showing an example of , and (c) is a plan view for explaining an electrical equivalent circuit of the load measuring device. FIG. 4A is a block diagram showing electrical connection of conductive elastic bodies, and FIG. 4B is a circuit diagram showing an equivalent circuit of a unit sensor according to the embodiment; It is a top view showing an example of composition of a load measuring device concerning a 1st embodiment. (a) and (b) of the load measuring device according to the first embodiment are diagrams for explaining the relationship between the length of the conductive elastic body and the load in the unit sensor, and (c) is the coordinates using a spherical model. It is a figure explaining calculation. 3(a) is a flow chart showing the flow of processing of a coordinate calculation processing program, and (b) is a flow chart showing the flow of processing of a load vector calculation processing program of the load measuring device according to the first embodiment. It is a top view which shows an example of a structure of the shape measuring device which concerns on 2nd Embodiment. (a) and (b) of the shape measuring device according to the second embodiment are diagrams for explaining the relationship between the length of the conductive elastic body and the three-dimensional coordinate position in the unit sensor, and (c) uses a spherical model. FIG. 10 is a diagram for explaining calculation of the coordinates of the position. 9 is a flow chart showing the flow of processing of a shape measurement processing program of the shape measurement device according to the second embodiment; (a) and (b) are diagrams showing various forms of human postures. FIG. 8A is a diagram showing a first application example of the shape measuring apparatus according to the second embodiment, and FIG. 8B is a diagram showing a modification of the first application example; FIG. 8A is a diagram showing a second application example of the shape measuring apparatus according to the second embodiment, and FIG. 8B is a diagram explaining the principle of shape measurement in the second application example. In the three-dimensional position calculation device according to the third embodiment, (a) is a diagram for explaining the relationship between the length of the conductive elastic body and the three-dimensional coordinate position in the unit sensor, and (b) is the coordinates using a spherical model. It is a figure explaining calculation of. FIG. 8A is a plan view showing an example of the configuration of a three-dimensional position calculation device according to a third embodiment, and FIG. 8B is a diagram showing an electrical equivalent circuit; It is a figure explaining the error which may generate|occur|produce in a three-dimensional position calculating device. It is a figure explaining the principle of the position calculation process of the three-dimensional position calculation apparatus which concerns on 3rd Embodiment. It is a figure explaining an example of the position calculation process of the three-dimensional position calculation apparatus which concerns on 3rd Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First embodiment]
A load measuring device according to the present embodiment will be described with reference to FIGS. 1 to 6. FIG. In order to solve the above-described problems, the load measuring device according to the present embodiment reduces the shape of the sensor and lowers the rigidity as compared with the load measuring device according to the conventional technology. The effect on elastic properties is reduced. In addition, the change in shape of the object to be measured and the applied load are simultaneously measured, enabling highly accurate measurement of the load vector.

First, with reference to FIGS. 1(a) to 1(c), the measurement of the load vector by the load measuring device will be described more specifically. FIG. 1(a) shows a sheet 100 as an example of an object to be measured. When a seated person sits on the seat, a load acts on the seat cushion 101 and the seat back 102 .

FIG. 1B shows a cross section of the buttocks of the seated person 103 and the seat cushion 101 when the seated person 103 is seated. Symbol W shown in FIG. 1(b) indicates the entire downward load due to seating, and symbols P1, P2, P3, P4, P5, P6, and P7 respectively indicate load measurement points. As shown in FIG. 1(b), the seat cushion 101 is deformed by tilting or extending as the seated person 103 sits down. FIG. 1(b) shows the positions of the measurement points P1 to P7 and changes in the measurement coordinate axes of the measurement points P1 to P7. For example, as a result of the component Fz' of the load W being applied to the measurement point P2, the measurement coordinate axes (X1, Y1, Z1) are tilted as shown in FIG. 1(b). That is, as shown in FIG. 1B, the inclination angles and three-dimensional coordinate positions of the measurement coordinate axes at the measurement points P1 to P7 set on the surface of the seat cushion 101 change, and the intervals between the measurement points also change. Therefore, in order to measure the load acting on the measurement points (P1 to P7), it is necessary to measure the tilt angle of the measurement coordinate axis of the measurement point in addition to the load component of each measurement coordinate axis. That is, it is necessary to calculate the load at each of the measurement points P1 to P7 as a load vector.

As one method of calculating the load vector acting on the seat cushion 101, there is a method of calculating using the finite element method. In order to calculate the load vector using the finite element method (that is, to analyze the seating state), the seat surface of the seat cushion 101 is modeled with a grid as shown in FIG. 1(c). In the seat surface calculation model 120 shown in FIG. 1(c), the lattice is composed of a plurality of joint points 121 and a plurality of linear elastic bodies 122 connecting the joint points. FIG. 1(c) also shows a seated person contact portion 123 (buttocks), which is a source of deformation of the seat surface. <1> shown in FIG. 1(c) is a diagram of the seat surface viewed from above, and <2> is a diagram of the sheet surface viewed from below. According to the seat surface calculation model 120 shown in FIG. 1(c), the load on the three-dimensional coordinate axis at each measurement point is calculated and the shape information such as the angle of inclination is also calculated at the same time. vector can be obtained.

In the load measuring device according to the present embodiment, as in the seat surface calculation model 120 shown in FIG. Connect with an elastic body. When a load acts on the seat surface due to seating, the three-dimensional coordinate positions of the measurement terminals change, and the elastic body connecting the measurement terminals expands. The elongation of the elastic is due to the load applied to the sheet 100, and there is a predetermined relationship between the applied load and the elongation.

Here, assuming that the elongation and the change in the electrical properties due to the load are known, the amount of elongation and the load of the elastic body can be obtained by measuring the electrical properties with a measuring means. Since the amount of extension of the elastic body corresponds to the distance between the measurement terminals, the three-dimensional coordinate position of a specific measurement terminal can be analytically determined based on the three-dimensional coordinate positions of a plurality of surrounding measurement terminals. . That is, the three-dimensional coordinate position of a specific measurement terminal can be calculated based on a plurality of measurement terminals whose three-dimensional coordinate positions are known and the extension amount of the elastic body. Further, since the amount of extension corresponds to the load, if the amount of extension is replaced with the load, the load vector acting on the measurement terminals can be obtained.

Considering that the elastic body used in this embodiment does not include a rigid body portion and that the elastic characteristics of the elastic body can be made smaller than the elastic characteristics of the sheet (object to be measured), According to the load measuring device according to the present embodiment, it is possible to measure the load vector without disturbing the elastic characteristics of the seat. Moreover, since the elastic body can be disposed in close contact with the seat surface, the appearance, structure and function of the seat surface are not impaired.

The configuration and operation of the load measuring device according to this embodiment will be described in more detail below. In the present embodiment, an example in which the load measuring device is applied to the load vector measurement of the seat surface shown in FIG. 1(c) will be described.

FIG. 2(a) <1> shows the load measuring device 10 according to the present embodiment. As shown in FIG. 2(a) <1>, the load measuring device 10 includes a measuring terminal 11, a fixed terminal 12, and a conductive elastic body 13. As shown in FIG. As shown in FIG. 2A <2>, the load measuring device 10 is provided on the seat cushion 101 as a sensor sheet in which the measuring terminals 11 and the conductive elastic bodies 13 are integrated. Here, the fixed terminal 12 is a terminal arranged and fixed to the outermost periphery of the load measuring device 10 among the measurement terminals 11 .

That is, in the load measuring device 10, the conductive elastic body 13 is used as the linear elastic body 122 shown in FIG. 1(c). FIG. 2B shows the relationship between the load acting on the conductive elastic body 13 and the electrical resistance of the conductive elastic body 13. As shown in FIG. As shown in FIG. 2B, the electrical resistance of the conductive elastic body 13 according to the present embodiment changes substantially in proportion to the applied load (curve X1). Here, as shown by curves X2 and X3, when the resistance value changes non-linearly with respect to the load (elastic body length), it is possible to use it by correcting it so that it changes linearly.

Therefore, the load measuring device 10 (sensor sheet) shown in FIG. 2(c) <1> can be modeled as a resistance network as shown in FIG. 2(c) <2>. That is, in FIG. 2C <2>, the measurement terminal 11 remains as it is, and the conductive elastic body 13 shown in FIG. 2C <1> is replaced with the equivalent resistance Rc. In the model shown in FIG. 2C <2>, the resistance value of the conductive elastic body 13 (equivalent resistance Rc) changes when the interval between the measurement terminals 11 changes. The configuration including the five measurement terminals 11 and the conductive elastic body 13 connecting the five measurement terminals 11 indicated by the dashed lines in FIG. sometimes referred to as For example, the load measuring device 10 shown in FIG. 2A <1> includes 25 unit sensors with a common measuring terminal 11 serving as a relay for connection. Of course, the number of unit sensors 20 to be arranged in the load measuring device 10 is not limited to 25, and may be an appropriate number according to the size of the object to be measured.

Next, electrical connection of the unit sensors 20 will be described. FIG. 3( a ) shows a power supply connection to one conductive elastic body 13 and a circuit connected to the conductive elastic body 13 . In FIG. 3A, the conductive elastic body 13 is indicated by an equivalent resistance Ri as a variable resistance, and a fixed resistance ri is connected to the equivalent resistance Ri. A voltage E is applied to one end of a series circuit of the equivalent resistance Ri and the fixed resistance ri, and the other end is connected to GND (ground), for example.

When a voltage E is applied to a series circuit of an equivalent resistance Ri and a fixed resistance ri, a divided voltage ei (=(E×Ri)/(Ri+ri)) is generated across the equivalent resistance Ri. When the resistance value of the equivalent resistance Ri changes as the length of the conductive elastic body 13 changes, the divided voltage ei changes. The divided voltage ei is converted into a digital signal by an analog-digital converter 21 and then inputted to an arithmetic processing unit 22 such as a computer. The arithmetic processing unit 22 executes a predetermined arithmetic operation on the input signal using the graph shown in FIG. 2(b) or the like. Through the above processing, the load applied to the conductive elastic body 13 can be obtained as a digital value.

The computer described above includes, for example, a CPU, a ROM, a RAM, and the like (not shown). The CPU is a control unit that controls the entire load measuring device 10, and the ROM is storage means for storing programs such as a control program for the load measuring device 10 and a load measurement processing program for the load measuring device 10, which will be described later. , the CPU reads a necessary program from the ROM, develops it in the RAM, and executes it. The RAM may temporarily store the length of the conductive elastic body 13 and the like. Further, the conductive elastic body 13, the analog-digital converter 21, the arithmetic processing unit 22, etc. are connected by signal lines, and necessary information is transmitted as electric signals. If high-speed communication is required for high-speed arithmetic processing, signals may be transmitted through an optical cable or the like.

When the unit sensor 20 is rewritten using the series circuit of the equivalent resistance Ri and the fixed resistance ri shown in FIG. 3A, it is expressed as shown in FIG. 3B. As shown in FIG. 3B, in the unit sensor 20, four series circuits each including an equivalent resistance Ri and a fixed resistance ri are commonly connected to the measurement terminal 11 to which the voltage E is applied. The load measuring device 10 is configured by connecting the required number of unit sensors 20 shown in FIG. 3B according to the size of the object to be measured. FIG. 4 shows the load measuring device 10 configured in this way.

The load measuring device 10 is a resistance network as shown in <2> of FIG. It can be marked as the load W between the measuring terminals 11 and 11 . In FIG. 4, for example, the symbol "W1121" indicates the load between the measurement terminal C11 and the measurement terminal C21. Each direction of the load measuring device 10 can be denoted as X direction, Y direction, etc. by the coordinate axes shown in FIG. Therefore, for example, the loads acting on the measurement terminal C21 are the loads W1121, W3121, W2112 and W2132, and by vector-combining these loads, the load vector acting on the measurement terminal C21 can be obtained. By calculating the load vector at each measurement point of the load measuring device 10 through the above calculations and integrating them into a common coordinate plane, the load vector distribution of the entire load measuring device 10 can be obtained.

Next, the detailed procedure for obtaining the load vector acting on each measurement point is shown below. FIG. 5(a) shows the relationship between adjacent measurement terminals 11 of the unit sensor 20, and reference numerals "O", "C1", "C2", "C3", and "C4" indicate the measurement terminals 11. FIG. Hereinafter, these measurement terminals may be referred to as "measurement terminal O", "measurement terminal C1", "measurement terminal C2", "measurement terminal C3", and "measurement terminal C4". Since the measurement terminals 11 are arranged in a three-dimensional space, the length between the measurement terminals 11 is the distance in three-dimensional coordinates and also corresponds to the magnitude of the load W. The three-dimensional coordinate values of the measurement terminal O are the length L1 between the measurement terminal C1 and the measurement terminal O, the length L2 between the measurement terminal C2 and the measurement terminal O, and the length L2 between the measurement terminal C3 and the measurement terminal O. is defined by the length L3 between and the length L4 between the measurement terminal C4 and the measurement terminal O.

Moreover, the load W1 between the measurement terminal C1 and the measurement terminal O, the load W2 between the measurement terminal C2 and the measurement terminal O, the load W3 between the measurement terminal C3 and the measurement terminal O, and the measurement terminal C4 and the measurement terminal O are in a balanced state (equilibrium state). Therefore, the relationship between the length L and the load W is as shown in FIG. Therefore, the load vector can be obtained by calculating the three-dimensional coordinate value of the measuring terminal O and combining it with the three-dimensional coordinate value of the measuring terminals C1 to C4 to obtain the direction of each component of the load W.

On the other hand, the three-dimensional coordinate values of the measurement terminal O are the intersection points of the spherical models M1, M2, and M3 with radii L1, L2, and L3 with the measurement terminals C1, C2, and C3 as origins, as shown in FIG. becomes. Therefore, the three-dimensional coordinate values of the measurement terminal O can be obtained as follows.

That is, the three-dimensional coordinate value O=(X, Y, Z) of the measurement terminal O is the coordinate value Ci=(Xi, Yi, Zi) of each of the measurement terminals C1, C2, and C3 (i=1, 2, 3) as the intersection of spherical models M1, M2, and M3 with radius Li (i=1, 2, 3). Specifically, it can be obtained by solving the equations of the sphere represented by (Equation 1), (Equation 2), and (Equation 3) as simultaneous equations.
(X-X1) ² + (Y-Y1) ² + (ZZ1) ² = L1 ² (Formula 1)
(X-X2) ² + (Y-Y2) ² + (Z-Z2) ² = L2 ² (Formula 2)
(X-X3) ² + (Y-Y3) ² + (Z-Z3) ² = L3 ² (Formula 3)
Note that the coordinate values of the measurement terminals C1, C2, and C3, which are fixed terminals, are uniquely determined from the mounting conditions of the load measuring device 10 to the seat cushion 101. FIG.

By repeating the calculation process of the three-dimensional coordinate values of the measurement terminals 11 for each unit sensor 20 described above, the three-dimensional coordinate values of the entire measurement terminals 11 of the load measuring device 10 are obtained. As a result, it is possible to acquire the load vector in the state where the seated person 103 is seated on the seat cushion 101 on which the load measuring device 10 is arranged.

Taking the load measuring device 10 shown in FIG. 4 as an example, the content of the above iterative processing will be described. Here, it is assumed that the coordinate values of the measurement terminals on the outer periphery of the sensor sheet, that is, the measurement terminals C11, C12, C13, C14, C31, C51, C71, C72, C73, C74, C54, and C34, which are the fixed terminals 12, are known. do. These coordinate values can be defined by, for example, fixing these measurement terminals 11 to the load measuring device 10 or the like. Therefore, even if a load acts on the seat cushion 101, the coordinate values of these fixed terminals 12 do not change. Further, since the intervals of W1112, W1213, W1314, etc. connecting these fixed terminals 12 do not change, the load does not change either. Therefore, in the load measuring device 10 shown in FIG. 4, the measurement terminals capable of measuring the load vector are C21, C22, C23, C41, C42, C43, C61, C62, and C63.

As a procedure for obtaining the coordinate values of the measurement terminals 11, it is necessary to perform processing sequentially from the measurement terminals whose coordinate values are known. In the following, an example of developing the process from the left end (measurement terminals C11, C12, C13, C14) in the X direction of the load measuring device 10 and the bottom end (measurement terminals C11, C31, C51, C71) in the Y direction is shown.

First, the coordinate values of the measurement terminals C11, C12, C31, and C21 are obtained. The coordinate values of the measuring terminal C32 are determined from the determined coordinate values of the measuring terminal C21 and the measuring terminals C12 and C31. From the above, the coordinate values of the five measurement terminals 11 of the unit sensor 20 can be obtained.

Next, the unit sensor 20 is moved in the X direction by one unit sensor, the coordinate values of the measuring terminal C41 are obtained from the coordinate values of the measuring terminals C32, C31, and C51, and the measuring terminal C52 is obtained from the coordinate values of the measuring terminals C32, C41, and C51. can be obtained. Further, by moving by one unit sensor 20, the coordinate values of the measuring terminal C61 can be obtained from the coordinate values of the measuring terminals C51, C52, and C71.

Since the coordinate values of the measurement terminals C71 and C72 are known, the coordinate values from end to end in the X direction are thus found. The calculation accuracy can be confirmed by comparing the coordinate values of C72 obtained from the measurement terminals C52, C61, and C71 with the known coordinate values of C72. In addition to checking the calculation accuracy, it is possible to calculate the combination of multiple fixed points and elastic body lengths, so it is possible to check the calculation accuracy by comparing the calculation results under multiple conditions. is.

Next, it is moved by one unit sensor 20 in the Y direction, and the same processing as described above is repeated by moving one unit sensor 20 at a time from one end to the other end in the X direction. Since the coordinate values of the measurement terminals C14, C34, C54, and C74 at the ends in the Y direction are known, it is not necessary to determine the coordinate values, but they may be determined to confirm the calculation accuracy as described above. Through the above processing, the three-dimensional coordinate values of the measurement terminals 11 of the entire load measuring device 10 can be obtained.

On the other hand, the inclination angle of the conductive elastic body 13 connecting the two measurement terminals 11 with respect to the XYZ coordinate system set in the load measuring device 10 is obtained using the three-dimensional coordinate values of the two measurement terminals 11 . By synthesizing the loads W1, W2, W3, and W4 as a load vector based on the obtained angles, the load vector acting on the measurement point can be obtained.

With the above processing, the load measuring device 10 according to the present embodiment can measure the load vector at the time of seating with high accuracy without affecting the elastic characteristics of the seat cushion 101 . Regarding the elastic characteristics with respect to the load of the seat cushion 101 and the elastic characteristics of the conductive elastic body 13, which are the objects to be measured, if the load value is included in the measurement item, it is necessary to take correspondence between the two before the measurement. There is

<Application example>
A specific application example of the load measuring device 10 according to the present embodiment will be described. A specific example in which the measurement of the load vector is important is, for example, evaluation of comfort in bed. Since the load measuring device in this case also has the same basic configuration and operation as the load measuring device 10, detailed description thereof will be omitted.

In the evaluation of comfort in bed, pressure ulcers may develop especially when a patient lies in bed for a long period of time due to illness or the like. Pressure ulcers are considered to be irreversible ischemic disorders when an external force applied to the body reduces or stops blood flow in soft tissues between bones and the surface layer of the skin. According to the measurement of the load vector by the load measuring device 10 according to the present embodiment, it is possible to grasp the external force applied to the body in detail even under such circumstances. That is, the load measuring device 10 can measure a load vector, which has been difficult to measure in the past. It has little effect on the body even if it is placed in the middle of the bed, and can provide a suitable measurement state for evaluating sleeping comfort in bed.

The measurement terminal 11 in the load measuring device 10 according to the present embodiment may use the part where the conductive elastic bodies 13 are connected to each other as it is. Also, the conductive elastic body 13 may be configured by combining, for example, a member having a spring characteristic, a member having a displacement measuring function, and a member having a load measuring function.

Next, load measurement processing executed in the load measurement device 10 will be described with reference to FIG. 6 . FIG. 6 shows a flow chart of a load measurement processing program executed in the load measurement device 10. The load measurement processing program is read from the ROM, developed in the RAM, and executed by the CPU (not shown).

FIG. 6(a) shows a coordinate calculation processing program for calculating the three-dimensional coordinate values of the measurement terminal 11(O), which is executed in the load measuring device 10, and FIG. 6(b) shows a load vector calculation. 1 shows a load vector calculation processing program for

When calculating the three-dimensional coordinate value of the measurement terminal 11, as shown in FIG. 6A, first, in step S100, the voltage generated in the conductive elastic body 13, that is, the partial pressure ei is measured.

In step S101, it is determined whether or not the measurement of all the partial pressures ei has been completed. If the determination is negative, the process returns to step S100 to continue measuring the partial pressures ei, and if the determination is positive. goes to step S102.

In step S102, the divided voltage ei is converted into the length between the measurement terminals 11. FIG. The conversion is performed by calculating the equivalent resistance Ri from the current flowing through the divided voltage ei and the equivalent resistance Ri, and converting the equivalent resistance Ri into the length of the conductive elastic body 13 with reference to FIG. 2(b). Note that the relationship between the load and the electrical resistance shown in FIG. 2(b) may be stored in advance in a storage means such as a ROM. Also, at that time, it may be stored as a table instead of the curve format.

In step S103, the simultaneous equations of the sphere represented by (Equation 1) to (Equation 3) are solved to find the coordinates (X, Y, Z) of the intersection point. Specifically, the lengths between the measurement terminals 11 (the lengths of the conductive elastic bodies 13) calculated in step S102 are set to L1, L2, and L3, and the known coordinate values of the three measurement terminals 11 (Xi , Yi, Zi) (i=1, 2, 3) are substituted into (Equation 1) to (Equation 3) to obtain (X, Y, Z).

In step S104, the above coordinates are defined from the mounting conditions of the sensor sheet (load measuring device 10). After that, the coordinate calculation processing program is terminated.

On the other hand, in the load vector calculation process, as shown in FIG. 6B, first, in step S200, the coordinates of the measurement terminals 11 of the unit sensor 20 from one end to the other end in the X direction are obtained as described above.

In step S201, it is determined whether or not the processing of step S200 has ended. If the determination is negative, the process returns to step S200 to continue calculating the coordinates, and if the determination is positive, step Move to S202.

In step S202, the coordinates of the measurement terminals 11 in the unit sensor 20 from one end to the other end in the Y direction are obtained as described above.

In step S203, it is determined whether or not the processing of step S202 has been completed. If the determination is negative, the process returns to step S202 to continue the calculation of coordinates, and if the determination is positive, step Move to S204.

In step S204, the overall shape of the sensor sheet (load measuring device 10) is calculated. That is, the coordinates obtained in steps up to step S203 are converted into coordinates on the coordinate axes defined on the load measuring device 10 .

In step S205, the inclination angle of the conductive elastic body 13 with respect to the measurement terminal 11 is obtained (see FIG. 5B).

In step S206, a load vector for each measurement terminal 11 is obtained from the load (W1 to W4 shown in FIG. 5B) obtained for the conductive elastic body 13 and the tilt angle obtained in step S205.

In step S207, the load vector for each measuring terminal 11 obtained in step S206 is integrated on the coordinate axis defined on the load measuring device 10 to obtain the load vector of the entire sensor sheet (load measuring device 10). After that, the load vector calculation processing program is ended.

As described in detail above, according to the load measuring device 10 according to the present embodiment, a plurality of sensors having elastic characteristics sufficiently small with respect to the elastic characteristics of the object to be measured and whose electrical characteristics change according to the applied load. By arranging the elastic body, it becomes possible to measure the load vector acting on the object to be measured without disturbing the elastic characteristics of the object to be measured. Furthermore, since the load vector acting on the object to be measured is measured by an elastic body that has elastic properties, there is little effect on the appearance and structure of the object to be measured when the load measuring device is installed on the object to be measured. Excellent effects such as not inhibiting the function of

[Second embodiment]
A shape measuring apparatus according to the present embodiment will be described with reference to FIGS. 7 to 12. FIG. In order to solve the above problem, the shape measuring device according to the present embodiment reduces the shape of the sensor and lowers the rigidity as compared with the shape measuring device according to the prior art. This makes it possible to reduce the influence on the elastic properties of the object to be measured and to appropriately measure and evaluate the shape change without changing the elastic properties of the object to be measured. Furthermore, since the shape measuring apparatus according to the present embodiment has a low rigidity, it can be brought into close contact with an object to be measured having low elasticity such as a rigid body, and highly accurate shape measurement is possible. It has become.

When three-dimensional shape measurement is performed using the shape measuring device according to the present embodiment, the relationship between the shape measuring device and the object to be measured, the modeling of the shape measuring device, etc. are basically the same as in FIG. be.

That is, in the shape measuring apparatus according to the present embodiment, a plurality of measurement terminals 11 are arranged at the connecting points 121 of the sheet 100, which is the object to be measured, in the same manner as the sheet surface calculation model 120 shown in FIG. , the conductive elastic body 13 is arranged as the linear elastic body 122 . That is, each measurement terminal 11 is connected by the conductive elastic body 13 . When the surface shape of the seat cushion 101 changes due to the seating of the seated person, the three-dimensional coordinate values of the measurement terminals 11 change and the length of the conductive elastic body 13 connecting them changes. Here, assuming that the change in the electrical properties associated with the extension of the conductive elastic body 13 is known, the amount of extension of the elastic body can be obtained by measuring the electrical characteristics with the measuring unit. On the other hand, since the amount of extension of the conductive elastic body 13 corresponds to the distance between the measurement terminals 11, the three-dimensional coordinate position of a specific measurement terminal 11 is the three-dimensional coordinate position of a plurality of surrounding measurement terminals 11, It can be analytically determined based on the distance between the measurement terminals 11 . That is, the three-dimensional coordinate position of a specific measurement terminal 11 can be calculated based on the extension amount of a plurality of measurement terminals 11 whose three-dimensional coordinate positions are known and the conductive elastic body 13 .

Since the conductive elastic body 13 that couples the measurement terminal 11 does not include a rigid body portion and the elastic characteristics of the conductive elastic body 13 can be made smaller than the elastic characteristics of the seat, the elasticity of the seat cushion 101 is improved. It is possible to measure the shape without impairing the characteristics. Further, since the conductive elastic body 13 can be closely arranged on the seat cushion 101, the appearance and structure of the seat cushion 101 are not damaged.

The shape measuring apparatus according to the present embodiment can be applied to, for example, the sheet 100 shown in FIG. 2(a). That is, the load measuring device 10 shown in FIG. 2A can be applied as it is to the shape measuring device 30 to form a device for measuring the shape change of the seat cushion 101 . In FIG. 2(a) <2>, the shape measuring device 30 is arranged on the seat cushion 101 instead of the load measuring device 10. FIG. The relationship between the load and the electrical resistance of the conductive elastic body 13 included in the shape measuring device 30 is, for example, the characteristics shown in FIG. The characteristic resistance value changes. Therefore, the shape measuring device 30 can be equivalently expressed as a resistance network as shown in FIG. 2(c). When the interval between the measurement terminals 11 changes, the resistance value of the conductive elastic body 13 changes. Also in the shape measuring device 30, a configuration including five measurement terminals 11 within the dashed line in FIG.

Furthermore, the electrical connection in the shape measuring device 30 is also the same as the electrical connection in the load measuring device 10 shown in FIG. That is, as shown in FIG. 3(a), a fixed resistor ri and an equivalent resistor Ri as the conductive elastic body 13 are connected, and a voltage E is applied to both ends thereof. At this time, the partial pressure ei at both ends of the conductive elastic body 13 changes according to the resistance value of the conductive elastic body 13 . This partial pressure ei is converted into a digital signal by an analog-to-digital converter 21 and processed by an arithmetic processor 22 such as a computer to obtain the length of the conductive elastic body 13 as a digital value.

Since the equivalent circuit of the unit sensor 20 can also be expressed as shown in FIG. 3B, the shape measuring device 30 can be set to an arbitrary size as shown in FIG. . Using the length L obtained from the resistance of the conductive elastic body 13, the arithmetic processing device 22 grasps the shape measuring device 30 as the distribution of the distance L between the measurement terminals 11 as shown in FIG. do. In FIG. 7, for example, the code "L1121" indicates the distance between the measurement terminal C11 and the measurement terminal C21. Each direction of the shape measuring device 30 can be labeled as the X direction and the Y direction, etc., as shown in FIG.

Next, referring to FIG. 8, the measurement principle of the shape measuring device 30 will be described.

8A <1> shows a unit sensor 20, and FIG. 8A <2> shows a shape measuring device 30 in which the unit sensors 20 are combined. As shown in FIG. 8A <2>, the shape measuring device 30 is also configured by connecting a plurality of measuring terminals 11 with a conductive elastic body 13, similar to the load measuring device 10. The measuring terminals 11 on the outer circumference of the device 30 are fixed terminals 12 . Since the measurement terminals 11 are arranged in a three-dimensional space, the length between the measurement terminals 11 is the distance in three-dimensional coordinates. In FIG. 8A <1>, the three-dimensional coordinate values of the measurement terminal O are the length L1 between the measurement terminal C1 and the measurement terminal O, the length L2 between the measurement terminal C2 and the measurement terminal O, and the length L2 between the measurement terminal C2 and the measurement terminal O. It is defined by the length L3 between C3 and the measurement terminal O. As shown in FIG. 8B, this rule does not change regardless of the position of the measurement terminal O.

Therefore, as shown in FIG. 8C, the three-dimensional coordinate values (X, Y, Z) of the measurement terminal O are represented by a spherical model M1 having a radius L1 with the measurement terminal C1 as the origin, and a spherical model M1 with the measurement terminal C2 as the origin. It can be obtained as an intersection of a spherical model M2 having a radius L2 and a spherical model M3 having a radius L3 having the measurement terminal C3 as an origin. A specific calculation method is the same as the calculation method using (Formula 1), (Formula 2), and (Formula 3) described above. Note that the coordinate values of the measurement terminals C1, C2, and C3, which are fixed terminals, are uniquely determined from the mounting conditions of the shape measuring device 30 to the seat cushion 101. FIG.

By repeating the method of obtaining the three-dimensional coordinate values of the measurement terminals 11 by the unit sensor 20 described above, the three-dimensional coordinate values of the measurement terminals 11 in the entire shape measuring device 30 are obtained, and the seat cushion on which the shape measuring device 30 is arranged. The shape change in the seated state in 101 can be grasped. That is, changes in the overall shape of the shape measuring device 30 can also be grasped by the same method as the method of repeatedly obtaining the coordinate values of the measurement terminals 11 of the unit sensor 20 described with reference to FIG.

As described in detail above, according to the shape measuring device 30 (sensor sheet) according to the present embodiment, the elastic characteristics of the shape measuring device 30 are flexible with respect to the elastic characteristics of the seat cushion 101. Since the measuring device 30 deforms closely without affecting the elastic deformation characteristics of the seat cushion 101, the shape deformation of the seat cushion 101 can be measured with high accuracy.

Next, referring to FIG. 9, shape measurement processing executed in the shape measurement device 30 will be described. FIG. 9 shows the flow of the shape measurement processing program executed when the shape measuring device 30 measures the shape. This shape measurement processing program is read from the ROM, developed in the RAM, and executed by the CPU (not shown). In this shape measurement processing program, as in the above-described load measurement processing, a coordinate calculation processing program for calculating the three-dimensional coordinate values of the measurement terminal 11 (O) is executed prior to the shape measurement processing. Since the processing program has the same flow as the processing shown in FIG. 6A, illustration and description are omitted.

In this shape measurement processing program, first, in step S300, the coordinates of the measurement terminals 11 of the unit sensor 20 from one end to the other end in the X direction are obtained by the method described above.

In step S301, it is determined whether or not all the unit sensors 20 have been completed. If the determination is negative, the process returns to step S300 to continue the coordinate calculation, and if the determination is positive, the process proceeds to step S302. do.

In step S302, the coordinates of the measurement terminals 11 in the unit sensor 20 from one end to the other end in the Y direction are determined by the method described above.

In step S303, it is determined whether or not all the unit sensors 20 have been completed. If the determination is negative, the process returns to step S302 to continue the coordinate calculation, and if the determination is positive, the process proceeds to step S304. do.

In step S304, the overall shape of the shape measuring device 30 (sensor sheet) is calculated. After that, the present shape measurement processing program is ended.

Next, another application example of the shape measuring apparatus according to the present embodiment will be described with reference to FIGS. 10 to 12. FIG. The following application example is a form in which the shape measuring apparatus according to the present embodiment is applied to posture measurement of a human body.

<First application example>
FIG. 10(a) shows an example of a person's posture change. When a person's posture changes as shown in FIG. 10(a), deformation occurs on the body surface. For example, deformation of the surface of the vertebral body is seen in bending, and such deformation also occurs when sitting on the seat during driving as shown in FIG. 10(b). The shape measuring apparatus according to the present embodiment can be applied when estimating such a bent state of the spinal column at the time of sitting from the deformation of the body surface.

FIG. 11(a) <2> shows a shape measuring device 30A that is closely arranged on the surface of the spinal column. As shown in FIG. 11(a) <2>, the shape measuring device 30A includes a spine body surface contact portion 31, a waist contact portion 32, and a signal line 33. As shown in FIG. The shape measuring device 30A has measurement terminals C1, C2 and C3 closely arranged on the waist and ten measurement terminals O1, O2, O3, O4, O5, O6, O7, O8, O9 and O10 arranged closely on the surface of the spinal column. , and a conductive elastic body 13 connected between the measurement terminals 11 . A signal line 33 is connected to each measurement terminal 11, and a change in electrical characteristics when the conductive elastic body 13 is deformed is measured as a change in the partial pressure ei when the voltage E is applied (Fig. 3). The signal line 33 is also connected to the analog-digital converter 21 connected to the arithmetic processing unit 22, and the divided voltage ei is processed by the arithmetic processing unit 22 as a digital signal.

When a measurement start signal is input to the arithmetic processing unit 22, the partial pressure ei corresponding to the length of the conductive elastic body 13 is converted by the analog-digital converter 21 and sequentially input. For example, the partial pressure e1 of the conductive elastic body 13 between the measurement terminal C1 and the measurement terminal O1 corresponds to the length LC1O1 of the conductive elastic body 13, and the conductive voltage between the measurement terminal C2 and the measurement terminal O1. The partial pressure e2 of the conductive elastic body 13 corresponds to the length LC2O1 of the conductive elastic body 13, and the partial pressure e3 of the conductive elastic body 13 between the measurement terminal C3 and the measurement terminal O1 corresponds to the conductive elastic body 13. It corresponds to the length LC3O1 of the body 13. Therefore, as shown in FIG. 11(a) <1>, the three-dimensional coordinate values of the measurement terminal O1 are centered on the three-dimensional coordinate values of the measurement terminals C1, C2, and C3, and the radii LC1O1, LC2O1, and LC3O1, the coordinate values of the intersection point CP of the three spherical models M1, M2, and M3.

The three-dimensional coordinate values of the measurement terminals O2 to O10 can also be obtained from the intersection points of the three spherical models M1, M2, and M3 with the length of the conductive elastic body 13 as the radius L. As a result, the deformed shape of the spinal body surface is obtained based on the three-dimensional coordinate values of the measurement terminals O1 to O10. Note that the deformed shape acquired by the above processing is obtained by connecting the three-dimensional coordinates of the measurement terminals O1 to O10 linearly, so a deformed state such as torsion cannot be obtained. Since the shape measuring device 30A (sensor sheet) is mainly composed of the conductive elastic body 13, the shape measuring device 30A can measure without hindering the shape change of the body surface due to the deformation of the spinal column. In addition, since it follows the elongation of the body surface, highly accurate shape measurement is possible.

<Modified example of the first application>
A shape measuring device 30B according to this modified example will be described with reference to FIG. As shown in FIG. 11(b), the shape measuring device 30B includes a neck contact portion 34 in addition to the waist contact portion 32. As shown in FIG. According to the shape measuring device 30B, since the arrangement density of the measuring terminals 11 can be increased, the spatial resolution of the measuring terminals 11 is increased, and more highly accurate shape measurement becomes possible.

<Second application example>
A shape measuring device 30C according to this application example will be described with reference to FIG. As for posture changes of the human body, there are posture changes accompanied by twisting such as rotation shown in FIG. 10(a). The shape measuring device 30A (sensor sheet) described in the first application example can measure posture changes such as bending, but is limited in application to measurement of postures that involve twisting. On the other hand, the shape measuring device 30C according to this application example is a shape measuring device that can be applied to posture measurement involving twist.

The shape measuring device 30C includes measurement terminals C1, C2, and C3 closely arranged on the waist close-contact portion 32, and measurement terminals C4 to C15 closely arranged on the surface of the spinal column body (hereinafter collectively referred to as "measurement terminals 11"). ), and each measurement terminal 11 is connected by a conductive elastic body 13 . A signal line (not shown) is connected to the conductive elastic body 13 (equivalent resistance Ri) via a fixed resistance ri (see FIG. 3A). A voltage E is applied to the signal line of . When the conductive elastic body 13 is deformed, the resistance of the conductive elastic body 13 changes, and a partial pressure ei corresponding to the change in resistance is generated. The divided voltage ei is transmitted by a signal line. Since the voltage ei is an analog value, it is converted into a digital value by an analog-to-digital converter 21 connected to a signal line. is stored in storage means such as a RAM (not shown).

Based on the length L of the conductive elastic body 13 stored in storage means such as RAM, the three-dimensional coordinate values after the measuring terminal C4 are calculated. FIG. 12(b) shows the procedure for obtaining the three-dimensional coordinate values of the measuring terminals 11 after the measuring terminal C4. In FIG. 12B <1>, the three-dimensional coordinate values of measurement terminals C1, C2, and C3 are known, and the three-dimensional coordinate values of measurement terminals C4, C5, and C6 are unknown. For example, if the position of the measurement terminal C2 is the origin of the relative coordinate system, the coordinate values of the measurement terminals C1 and C3 can be defined from the arrangement positions of the measurement terminals C1 and C3.

The lengths LC1C5, LC2C5, and LC3C5 of the conductive elastic bodies 13 connecting each of the measurement terminals C1, C2, and C3 to the measurement terminal C5 are known from the measurement result of the partial pressure ei based on the change in the resistance value of the equivalent resistance Ri. Therefore, consider three spherical models M1, M2 and M3 whose origins are the three-dimensional coordinate values of the measurement terminals C1, C2 and C3 and whose radii are LC1C5, LC2C5 and LC3C5. The three-dimensional coordinate value of the measurement terminal C5 can be obtained as the coordinate value of the intersection of these three spherical models M1, M2, and M3 (Fig. 12(b) <2>).

Next, as shown in FIG. 12(c) <3>, the three-dimensional coordinate values of the measurement terminal C4 are obtained. The three-dimensional coordinate value of the measurement terminal C4 can be obtained as the intersection of three spherical models M1, M2, and M3 with radii LC5C4, LC1C4, and LC2C4. Similarly, as shown in FIG. 12(c) <4>, the three-dimensional coordinate value of the measurement terminal C6 can be determined as the intersection of three spherical models M1, M2, and M3 with radii LC5C6, LC2C6, and LC3C6.

The above processing is performed up to the upper end in the Y direction to obtain the three-dimensional coordinate values of the entire measurement terminals 11 of the shape measuring device 30C (sensor sheet). The shape of the shape measuring device 30C is acquired from the determined three-dimensional coordinate values. In this application example, since three measurement terminals 11 are arranged in the X direction, it is possible to grasp the twisted state from the three-dimensional coordinate values of these measurement terminals.

As described in detail above, according to the shape measuring apparatus (30, 30A, 30B, 30C) according to the present embodiment, the elastic characteristics are sufficiently small with respect to the elastic characteristics of the object to be measured, and the electrical By arranging a plurality of conductive elastic bodies 13 whose physical characteristics change, the three-dimensional shape of the measurement object can be measured without affecting the elastic characteristics of the measurement object. Furthermore, according to the shape measuring device according to the present embodiment, since the deformation of the object to be measured is measured by the conductive elastic body 13 having elastic properties, the appearance when the shape measuring device is arranged on the object to be measured It has excellent effects such as little influence on the structure and the original function of the object to be measured is not hindered. Moreover, the shape measuring apparatus according to the present embodiment can be applied not only when the object to be measured is an elastic body but also when it is a rigid body.

The measurement terminal 11 in the shape measuring apparatus (30, 30A, 30B, 30C) according to the present embodiment may be formed by directly using the portion where the conductive elastic bodies 13 are connected to each other. 13 may also be configured by combining, for example, a member having a spring characteristic, a member having a displacement measuring function, and a member having a shape measuring function, as in the above embodiment.

[Third embodiment]
A three-dimensional position calculation device according to the present embodiment will be described with reference to FIGS. 13 to 17. FIG. The three-dimensional position calculation device according to the present embodiment has a configuration in which the three-dimensional coordinate values of the measurement terminal 11 are determined using the three spherical models M1, M2, and M3 in the unit sensor 20 described in each of the above embodiments. It is a device with

When the three-dimensional position calculating device for calculating three-dimensional coordinate values according to the present embodiment is applied to the load measuring device and the shape measuring device of the above embodiments, the relationship between the device and the object to be measured, the Modeling of the apparatus is basically the same as in FIG.

That is, in the three-dimensional position calculation device according to the present embodiment, as in FIG. The terminals 11 are connected by the conductive elastic body 13 which is the linear elastic body 122 . When the shape of the seat surface of the seat cushion changes due to seating, the three-dimensional coordinate values of the measurement terminals 11 change, and the length of the conductive elastic body 13 connecting the measurement terminals 11 changes. Here, assuming that the change in the electrical properties accompanying the elongation of the conductive elastic body 13 is known, the amount of elongation of the conductive elastic body 13 can be obtained by measuring the electrical properties with the measuring unit.

On the other hand, since the amount of extension of the conductive elastic body 13 corresponds to the distance between the measurement terminals 11, the three-dimensional coordinate position of a specific measurement terminal 11 is based on the three-dimensional coordinate positions of the plurality of surrounding measurement terminals 11. can be obtained analytically. For example, as shown in FIG. 13(a), the three-dimensional coordinate values (x, y, z) of a specific measurement terminal O are 3 It can be calculated based on the dimensional coordinate values and the extension amount of the conductive elastic body 13 .

That is, as shown in FIG. 13(b). The three-dimensional coordinate value of the measurement terminal O can be determined as the intersection of three spherical models M1, M2 and M3 whose centers are C1, C2 and C3 and whose radii are L1, L2 and L3 respectively. However, the measured elongation amount of the conductive elastic body 13 includes an error due to the influence of the characteristics and attachment state of the conductive elastic body 13, the measurement accuracy of the measuring equipment, and the like. For this reason, the intersection point of the three spheres may not be obtained as an analytical solution.

In order to deal with the above problem, in the three-dimensional position calculation device according to the present embodiment, two of the three spherical models M1, M2, and M3 are combined, and the intersection point is obtained for each combination. That is, in this embodiment, first, an intersection point CP1 between the spherical models M1 and M2, an intersection point CP2 between the spherical models M1 and M3, and an intersection point CP3 between the spherical models M2 and M3 are obtained. Central coordinate values are obtained for the three obtained intersection points CP1, CP2, and CP3, and the obtained central coordinate values are used as three-dimensional coordinate values of the measurement terminal 11(O). As a result, the robustness against various errors is enhanced, and the three-dimensional position can be acquired even when an analytical solution cannot be obtained.

A three-dimensional position calculation device 50 according to the present embodiment will be described with reference to FIG. As shown in FIG. 14(a), the three-dimensional position calculation device 50 includes a measurement terminal 11(O) and three conductive elastic bodies 13-1 each having one end connected to the common measurement terminal 11(O). , 13-2 and 13-3. In the example shown in FIG. 14, the other ends of the conductive elastic bodies 13-1, 13-2, and 13-3 are connected to the measurement terminals 11 (C1), 11 (C2), and 11 (C3), respectively. It is At least one of the measurement terminal 11 (C1), the measurement terminal 11 (C2), and the measurement terminal 11 (C3) may be the fixed terminal 12 in some cases.

FIG. 14(b) shows an electrical equivalent circuit of the three-dimensional position calculation device 50. As shown in FIG. As shown in FIG. 14(b), the conductive elastic bodies 13-1, 13-2 and 13-3 can be replaced with the above equivalent resistances R1, R2 and R3, respectively. That is, the three-dimensional position calculation device 50 can be regarded as part of the unit sensor 20 shown in FIG. 3(b). However, in FIG. 14B, the fixed resistors r1, r2, and r3 are omitted.

The three-dimensional position calculation device 50 according to the present embodiment can be applied to the load measuring device 10 or the shape measuring device 30 (30A, 30B, 30C) according to the above embodiments, but here, FIG. A form applied to the shape measuring device 30 shown in the same drawing as (a) will be described as an example. In this case, the three-dimensional position calculation device 50 is an element constituting each of the unit sensors 20 (see FIG. 2(c)) included in the shape measurement device 30 shown in the same view as FIG. 2(a) <1>. It has become. A shape measuring device 30 including a plurality of three-dimensional position computing devices 50 shown in a view similar to FIG. 2A <2> is arranged on the seat surface of the seat cushion 101 as a sensor seat.

The load-electric resistance characteristics of the conductive elastic body 13 included in the three-dimensional position calculation device 50 are the same as those shown in FIG. It is the same as in FIG. 2C that the unit sensor 20 is configured including the three-dimensional position calculation device 50. FIG. Furthermore, the electrical connection of the conductive elastic body 13 included in the three-dimensional position calculation device 50 is the same as that shown in FIG. is the same as in FIGS. 3(b) and 7.

8 that the three-dimensional coordinate values of the measurement terminal O in the unit sensor 20 including the three-dimensional position calculation device 50 can be basically determined as the intersection of the three spherical models M1, M2, and M3. , the method of obtaining the three-dimensional coordinate values of the measurement terminals 11 of the entire shape measuring device 30 (sensor sheet) is the same as the description of FIG. The processing program is the same as in FIG.

Next, with reference to FIGS. 15 to 17, position calculation processing executed in the three-dimensional position calculation device 50 according to the present embodiment will be described. The position calculation processing according to the present embodiment employs correction when a unique solution cannot be determined in the derivation of a three-dimensional coordinate position using a spherical model.

Here, the three-dimensional coordinate values of the measurement terminals 11 included in the three-dimensional position calculation device 50 can be obtained by the above-described calculation processing using the three-dimensional position calculation device 50 . However, the characteristics of the conductive elastic body 13 may be non-linear as shown in FIG. 2(b), for example, and are not uniform due to individual variations in characteristics. In addition, there is also the influence of measurement errors due to electrical noise during measurement and calculations. Therefore, a single solution may not be obtained when the above equations (1) to (3) are simultaneously solved.

FIG. 15(a) shows position calculation processing when there is no error. In FIG. 15(a), the spherical model M1 is a sphere centered at the measurement terminal C1 and having a radius L1, the spherical model M2 is a sphere centered at the measurement terminal C2 and a radius L2, and the spherical model M3 is centered at the measurement terminal C3. is a sphere with radius L3. In this case, a single point of intersection CP1 can be obtained by solving the simultaneous equations (Equation 1) to (Equation 3), and this intersection point CP1 can be regarded as the position of the measurement terminal O.

On the other hand, FIG. 15(b) shows an example when there is the above error. In the example shown in FIG. 15B, the spherical model M1 contains an error, and the radius is L1' (<L1) instead of L1. FIG. 15(c) is a diagram showing the spherical models M1 and M2 extracted. Due to the error of the spherical model M1, the intersection of the spherical model M1 and the spherical model M2 moves from CP1 to CP2 as shown in FIG. 15(c). In FIG. 15(c), the radius of the spherical model M2 corresponding to the intersection point CP2 is indicated as L2' (=L2).

FIG. 15(d) is a diagram showing the spherical models M2 and M3 extracted. As shown in FIG. 15(d), the point of intersection between the spherical models M2 and M3 is the point of intersection CP1. Therefore, the point of intersection CP2 between the spherical models M1 and M2 and the point of intersection CP1 between the spherical models M2 and M3 are different points, making analysis using the spherical models difficult. For the reasons described above, there are cases where the coordinates of the intersection point cannot be obtained from the spherical model. Also, as shown in FIG. 15(e), when the radius L1 of the spherical model M1 increases to L1' due to the measurement error, the point of intersection CP1 similarly moves to the point of intersection CP2. Therefore, in this case also, the coordinates of the points of intersection cannot be obtained analytically by the spherical model. In addition, the intersection between a plurality of spherical models is defined by the distance between the measurement terminals from the intersection circle of the mutual spherical models as shown in FIG. 15(d). In other words, although CP1 and CP1' are conceivable points of intersection between the spherical model M2 and the spherical model M3, the point of intersection CP1 is adopted.

FIG. 16 shows the basic concept of position calculation processing using the three-dimensional position calculation device 50 according to this embodiment. FIG. 16(a) shows three spherical models in a certain equilibrium state of the three-dimensional position calculation device 50, a spherical model M1 (denoted as “spherical model 1” in FIG. 16(a)) and a spherical model M2 ( FIG. 16A shows a spherical model M3 (labeled "spherical model 2" in FIG. 16A) and a spherical model M3 (labeled "spherical model 3" in FIG. 16A). 16(b) is a diagram showing spherical models M2 and M3 extracted from FIG. 16(a), and FIG. 16(c) is a diagram showing spherical models M1 and M2 extracted from FIG. 16(a). FIG. 16(d) is a diagram showing spherical models M1 and M3 extracted from FIG. 16(a).

In general, when spheres overlap, the overlap forms a circle. Here, this circle is referred to as an "intersection circle", and for example, the intersection circle of the spherical models M1 and M2 is referred to as a "sphere model 1-2 intersection circle". According to this definition, FIG. 16(b) shows the sphere model 1-2 intersection circle and the sphere model 1-3 intersection circle in addition to the sphere models M2 and M3. When circles are superimposed, generally two points of intersection occur, and these two points of intersection are also drawn in FIG. 16(b). In a similar way, as shown in FIG. 16(c), two points of intersection are generated by the sphere model 3-2 intersection circle and the sphere model 3-1 intersection circle, and as shown in FIG. 16(c), the sphere Two points of intersection are generated by the model 2-1 intersection circle and the sphere model 2-3 intersection circle. In the position calculation processing according to the present embodiment, intersection points are obtained for each of the two spherical models shown in FIGS. 16(b), (c), and (d). Which of the two points of intersection is to be adopted is determined, for example, based on the distance from the position of the measurement terminal 11 in the past. That is, the intersection closer to the position of the measurement terminal 11 in the past may be adopted.

FIG. 17 shows an example of how to find the intersection point by this position calculation process. When measurement error is included in the three-dimensional position calculation device 50, the intersection obtained from the two spherical models cannot be uniquely determined as shown in FIG. For example, in the example shown in FIG. 17A, the point of intersection between the spherical models M2 and M3 is the point of intersection CP1, and the point of intersection between the spherical models M1 and M2 is the point CP2. In this case, the midpoint between the intersection points CP1 and CP2 is set as the corrected intersection point CPs, and the main corrected intersection point CPs is set as the intersection point of the spherical models M1, M2, and M3, that is, the three-dimensional coordinate value of the measurement terminal 11(O). In the example shown in FIG. 17B, the intersection point CP3 is the point of intersection between the spherical models M2 and M3, and the point CP4 is the intersection point of the spherical models M1 and M2. Also in this case, the midpoint between the intersection points CP3 and CP4 is the corrected intersection point CPs, and the main corrected intersection point CPs is the intersection point of the spherical models M1, M2, and M3, that is, the three-dimensional coordinate value of the measurement terminal 11(O). According to the correction process as described above, it is possible to uniquely acquire the three-dimensional coordinate position of the measurement terminal 11(O) without causing a situation in which analysis becomes difficult. In addition, it is possible to change the correction method and the degree of correction according to the measurement error without being limited to such a method, and it is possible to obtain a coordinate position with higher accuracy.

10 Load measuring device 11, O, C1 to C4 Measuring terminal 12 Fixed terminal 13, 13-1, 13-2, 13-3 Conductive elastic body 20 Unit sensor 21 Analog-digital converter 22 Arithmetic processing device 30, 30A, 30B, 30C shape measurement device 31 spine body surface contact portion 32 lumbar contact portion 33 signal line 34 neck contact portion 50 three-dimensional position calculation device 100 seat 101 seat cushion 102 seat back 103 seated person 120 seat surface calculation model 121 coupling point 122 Linear elastic body 123 Seated person contact portion CP, CP1-CP4 Intersection L1-L4 Length X1-X3 Curve W, W1-W4 Load M1-M3 Spherical model P1-P7 Measurement point Rc Equivalent resistance R1-R4, Ri Equivalent resistance r1 to r4, ri fixed resistors e1 to e4, ei divided voltage E voltage

Claims (6)

A load measuring device that is brought into contact with a measurement object and measures a load applied to the measurement object as a load vector,
a measurement terminal whose position changes in a three-dimensional space; a plurality of elastic bodies each having one end connected to the measurement terminal and having an electrical characteristic that changes with displacement; and the electrical properties of each of the plurality of elastic bodies a plurality of three -dimensional position computing devices , including a measuring unit that measures physical characteristics, and a computing unit that computes the spatial positions of the measurement terminals based on the electrical characteristics measured by the measuring unit ;
a plurality of measurement terminals connected to the other ends of the plurality of elastic bodies of the plurality of three-dimensional position calculation devices, the positions of which change according to the shape of the object to be measured ;
including
A plurality of the three-dimensional position calculation devices are connected by the plurality of measurement terminals,
a relationship between the displacement amount of the plurality of elastic bodies and the applied force is a predetermined second characteristic,
The computing unit generates a force corresponding to the amount of displacement calculated based on the electrical characteristics measured by the measuring unit and the calculated spatial position of the measurement terminal when the object to be measured contacts. and the position of the point corresponding to the other end of each of the plurality of elastic bodies is obtained for each of the measurement terminals, the force corresponding to the measurement terminal is synthesized, and the load is a vector operate as
Load measuring device. Each of the plurality of elastic bodies is a conductive elastic body having conductivity and the electrical characteristic being a resistance value, and a relationship between the length of each of the plurality of elastic bodies and the resistance value is predetermined. It is the first characteristic,
The computation unit computes the spatial position of the measurement terminal using the length of each of the plurality of elastic bodies obtained according to the predetermined first characteristic from the resistance value measured by the measurement unit. do
The load measuring device according to claim 1. The calculation unit calculates, as the spatial position of the measurement terminal, an intersection point of a plurality of spheres centered at a point corresponding to the other end of the plurality of elastic bodies and having a radius equal to the length of each of the plurality of elastic bodies.
The load measuring device according to claim 2. When there are a plurality of intersection points, the calculation unit calculates a midpoint of the plurality of intersection points as the spatial position of the measurement terminal.
The load measuring device according to claim 3. the number of said plurality of elastic bodies is at least three
The load measuring device according to any one of claims 1 to 4. The load measuring device according to any one of claims 1 to 5, wherein the object to be measured is an elastic body.

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