JP7033939B2 - Indentation test device and zero point setting method - Google Patents

Description

The present invention relates to an indentation test device for injecting an indenter into a food such as kamaboko or ham or a flexible tissue of a human and measuring the softness of the indenter, and a method for setting a zero point thereof.

The following Patent Document 1 discloses an indentation test device for measuring the softness of a flexible food, a human body tissue, or the like as a subject.
As shown in FIG. 8, this device includes an indenter 10 pushed into a subject, a force sensor 30 that detects a force acting on the indenter 10 when the indenter 10 is pushed into a subject, and a detection output of the force sensor. It includes a control board 40 on which a calculation unit and the like for calculating Young's modulus of a subject based on the above are mounted, and a housing 20 in which they are arranged.
The indenter 10 is arranged in the housing 20 so that a certain amount of the hemispherical portion at the tip protrudes from the end portion 21 of the housing 20.
Further, an operation button 50 for setting the zero point of the force sensor 30 and instructing the start of measurement is attached to the housing 20 so that it can be operated from outside the housing 20.

The operator who operates this device grips the housing 20 portion, performs a button operation for setting the zero point, and then pushes the indenter 10 into the subject until the end portion 21 of the housing 20 abuts on the subject. ..

This zero point setting is the same as pressing the zero point setting button to make the weighing display zero when weighing the article with the weighing device. By setting the weighing display to zero and then placing the article on the weighing pan, the correct weight of the article is displayed on the display.

この(数１)を用いて、力センサ３０で検出された押込荷重Ｆから被検体の柔らかさを評価するヤング率Ｅを求めることができる。 When the indenter 10 of the indentation test device is pushed into the subject, the force (pushing load) detected by the force sensor 30 when the end 21 of the housing 20 comes into contact with the subject is set to F, and the end of the housing 20 is set. The amount of protrusion of the indenter 10 protruding from the portion 21 (that is, the amount of indentation 10 pushed into the subject) is δ, the diameter of the hemisphere of the indenter 10 is φ, the Young's modulus of the subject is E, and the subject is unique. If the Poisson's ratio of is ν, there is a relationship represented by (Equation 1) between them.

Using this (Equation 1), Young's modulus E for evaluating the softness of the subject can be obtained from the pushing load F detected by the force sensor 30.

This indentation test device can measure the softness of a subject at the place where the subject should be (so-called “in-situ measurement”).
FIG. 9 shows a push-in test device 50 in which the grip portion 51 is provided in the housing 20, and FIG. 10A uses this device to measure the flexibility of the cushioning material attached to the transport pipe. It shows how it is doing. Further, FIG. 10B shows how the hardness of the leg muscle is measured by using this device.

WO2017 / 164426

In this indentation test apparatus, the indentation direction can be set to various angles according to the state of the subject in the field. It is also possible to insert the tip of the housing 20 through a narrow gap and measure the softness of the subject at the tip.
However, in such a measurement, it may be difficult to operate the button for setting the zero point, or the button operation may be forgotten.

If the zero point is not set, the following inconveniences will occur.
As shown in FIG. 11A, where F is the weight of the indenter 10 and its accessories applied to the force sensor 30 when the housing 20 is vertical, the housing 20 is as shown in FIG. 11B. The weight F'of the indenter 10 and the accessory parts applied to the force sensor 30 when tilted by θ from the vertical direction is
F'= Fsinθ
Will be.
As described above, since the force applied to the force sensor 30 changes depending on the inclination of the housing 20, accurate measurement cannot be performed unless the zero point is always set when measuring the softness.

The present invention has been devised in consideration of such circumstances, and an object of the present invention is to provide an indentation test apparatus capable of performing zero point setting with a simple operation, and a zero point setting method thereof.

In the present invention, the indenter pushed into the subject, the housing in which the indenter is arranged with at least a part thereof protruding from the end portion, and the housing operated so as to push the indenter into the subject. When this is done, it has an abutting portion that comes into contact with the subject after the indenter and a force sensor that detects the force acting on the indenter, and the abutting portion hits the subject with the operation. A push-in test device in which the force acting on the indenter at the time of contact is detected by the force sensor to calculate the softness of the subject, and the first is to detect the amount of change in the detection output of the force sensor with time. The fluctuation detection unit, the tilt sensor that detects the tilt of the housing, the second fluctuation detection unit that detects the amount of change in the detection output of the tilt sensor with time, and the first fluctuation detection unit. The amount of change in the detection output of the force sensor is less than the preset first threshold value, and the amount of change in the detection output of the tilt sensor detected by the second fluctuation detection unit is preset. It is characterized by comprising a zero point setting unit for setting the output of the force sensor to the zero point when the value is less than the second threshold value.
If the operator who operates the indentation test apparatus keeps the indentation test apparatus stationary for a predetermined time prior to indenting the subject, the zero point setting of the apparatus is automatically performed.

Further, in the indentation test apparatus of the present invention, a display unit for displaying an error may be provided when the zero point is not set by the zero point setting unit.
The operator who recognizes the error display again executes the indentation test device to stand still for a predetermined time, so that the zero point is set.

In the present invention, the indenter pushed into the subject, the housing in which the indenter is arranged with at least a part thereof protruding from the end portion, and the housing operated so as to push the indenter into the subject. When this is done, it has an abutting portion that comes into contact with the subject after the indenter and a force sensor that detects the force acting on the indenter. It is a zero point setting method of the indentation test device in which the force acting on the indenter at the time of contact is detected by the force sensor and the softness of the subject is calculated, and the change with time of the detection output of the force sensor. The second threshold value is the amount of change with time of the first fluctuation detection step for detecting whether or not the amount is less than the preset first threshold value and the detection output of the tilt sensor for detecting the tilt of the housing. The amount of change in the detection output of the force sensor in the second fluctuation detection step for detecting whether or not it is less than the first fluctuation detection step is less than the first threshold value, and the second fluctuation detection step is performed. It is characterized by including a zero point setting step for setting the output of the force sensor to a zero point when the change amount of the detection output of the tilt sensor is less than the second threshold value in the fluctuation detection step.
The zero point can be easily set regardless of the angle at which the indentation test device is operated.

In the indentation test apparatus and the zero point setting method of the present invention, the zero point is automatically set if the indentation test apparatus is temporarily stopped at the stage where the indenter is prepared to be pushed into the subject. The zero point can be easily set even when the pushing operation is performed at any angle.
In addition, since this zero point setting method keeps a stationary state for a period of a series of pushing operations, it may be forgotten compared to the case where the zero point setting button is operated separately from the pushing operation. Less is.

The figure which shows the indentation test apparatus which concerns on embodiment of this invention. The figure which shows the example of the tilt sensor of FIG. A block diagram showing the configuration of the automatic zero point setting unit of FIG. The flow chart which shows the operation of the indentation test apparatus of FIG. The figure which shows the modification of the flow diagram of FIG. The figure which shows the contact detection sensor which forms the contact part. The figure which shows the pin type contact detection sensor which forms the contact part. The figure which shows the conventional indentation test apparatus The figure which shows the conventional indentation test apparatus which has a grip part. The figure which shows the use example of the indentation test apparatus of FIG. Figure explaining the necessity of zero point setting

FIG. 1 shows an indentation test apparatus according to an embodiment of the present invention.
This device is based on the indenter 10 pushed into the subject, the force sensor 30 that detects the force acting on the indenter 10 when the indenter 10 is pushed into the subject, and the Young's modulus of the subject based on the detection output of the force sensor. It includes a control board 40 on which a calculation unit 41 for calculating a rate, an inclination sensor 42 for detecting an inclination, an automatic zero point setting unit 43, and the like are mounted, and a housing 20 in which they are arranged.
The indenter 10 is arranged in the housing 20 so that a certain amount of the hemispherical portion at the tip protrudes from the end portion 21 of the housing 20. This end portion 21 also serves as a contact portion, and when the housing 20 is operated to push the indenter 10 into the subject, the end portion 21 comes into contact with the subject behind the indenter 10.

As the tilt sensor 42, for example, a commercially available sensor shown in FIG. 2 can be used.
This sensor is made by MEMS technology, and has a proof mass 421 supported by a spring 422, a movable electrode 423 extending from the four sides of the proof mass 421, and a differential that changes the capacitance according to the position of the movable electrode 423. It has a pair of fixed electrodes 424 that make up a capacitive cell. When the proof mass 421 is tilted, the position of the movable electrode 423 with respect to the fixed electrode 424 changes accordingly, and the capacitance between the pair of fixed electrodes 424 changes accordingly. The slope is calculated by measuring this capacitance.

As shown in FIG. 3, the automatic zero point setting unit 43 is a first fluctuation detection unit 431 that inputs the detection output of the force sensor 30 and detects the amount of change of the detected value with time, and the detection output of the tilt sensor 42. Is input, and the change amount of the detection value of the second fluctuation detection unit 432 that detects the change amount of the detected value with time and the force sensor 30 detected by the first fluctuation detection unit 431 is set in advance. When the amount is less than the threshold value and the amount of change in the detected value of the tilt sensor 42 detected by the second fluctuation detection unit 432 is less than the preset second threshold value, the output of the force sensor 30 is set to the zero point. It is provided with a zero point setting unit 433. The zero point setting unit 433 informs the calculation unit 41 when the zero point is set and when the zero point is released.
The automatic zero point setting unit 43 is realized by executing a process specified by a program by an arithmetic processing unit such as a CPU.

Prior to pushing the indenter 10 into the subject, the operator who operates the indentation test device makes the indentation test device stand still for a predetermined time in a state where the housing 20 is oriented in the pushing direction. This operation automatically sets the zero point of the indentation test device. After the zero point is set, the operator advances the housing 20 in the pushing direction and pushes the indenter 10 into the subject until the end portion 21 of the housing 20 comes into contact with the subject.
By setting the zero point of the indentation test device in this way, it is possible to obtain an accurate indentation load when the indenter 10 is indented into the subject from the detection value of the force sensor 30.

The flow chart of FIG. 4 shows the operation procedure of this indentation test apparatus.
The first fluctuation detection unit 431 of the automatic zero point setting unit 43 acquires the detection value of the force sensor 30 and identifies whether or not the amount of change of the value with time is less than the preset first threshold value. (Step 1).
Further, the second fluctuation detection unit 432 of the automatic zero point setting unit 43 acquires the detection value of the tilt sensor 42, and determines whether or not the amount of change of the value with time is less than the preset second threshold value. Identify (step 2).
When the identification results of step 1 and step 2 are both Yes, the zero point setting unit 433 of the automatic zero point setting unit 43 sets the detection output of the force sensor 30 at that time to the zero point, and sets it to the calculation unit 41. Tell (step 3).

After setting the zero point, when the second fluctuation detection unit 432 acquires information on the change in inclination of a predetermined value or more from the inclination sensor 42 (Yes in step 4), the zero point setting unit 433 cancels the zero point setting (Yes). Step 7), and convey it to the calculation unit 41. When the zero point setting is canceled, the procedure from step 1 is repeated.
When the detection output of the force sensor 30 changes with the zero point set (Yes in step 5), the arithmetic unit 41 determines the Young's modulus of the subject based on the amount of change from the zero point of the detection output of the force sensor 30. Is calculated (step 6).
In this way, the indentation test device automatically sets the zero point when it is stationary for a predetermined time. Further, when the zero point is set against the intention, the zero point can be released by changing the direction of the indentation test device.

Further, when the stationary time of the indentation test device is insufficient and the zero point is not set, an error may be displayed to notify the operator.
The flow chart of FIG. 5 shows the procedure in this case.
FIG. 5 differs from FIG. 4 only in that an error is displayed in the case of No in steps 1 and 2, and that the error display is erased when the zero point is set in step 3. ..

Note that FIG. 1 shows a push-in test device in which the contact portion that comes into contact with the subject after the indenter 10 at the time of measuring the softness is the end portion 21 of the housing 20, and FIGS. 6 and 7 show. As shown, a contact detection sensor 22 for detecting contact with a subject or a pin-type contact detection sensor 221 may be provided at the end 21 of the housing 20, and these may be used as the contact portion.
Further, although an indenter having a hemispherical surface is shown here, the shape of the indenter is not limited to this. It may be a cylinder, a cylinder, a cube, or the like.

The indentation test apparatus of the present invention can easily set a zero point, and can be used in a wide range of fields such as a food field that requires measurement of softness, a medical field, and a field that handles materials.

10 Indenter 20 Housing 21 Housing end 22 Contact detection sensor 30 Force sensor 40 Control board 41 Calculation unit 42 Tilt sensor 43 Automatic zero point setting unit 50 Operation button 221 Pin type contact detection sensor 421 Proof mass 422 Spring 423 Movable electrode 424 Fixed electrode 431 1st fluctuation detection unit 432 2nd fluctuation detection unit 433 Zero point setting unit

Claims (3)

When the indenter pushed into the subject, the housing in which the indenter is arranged so that at least a part thereof protrudes from the end, and the housing is operated so as to push the indenter into the subject. It has an abutting portion that comes into contact with the subject after the indenter and a force sensor that detects a force acting on the indenter, and the abutting portion abuts on the subject with the operation. It is an indentation test device in which the force acting on the indenter at the time of the movement is detected by the force sensor and the softness of the subject is calculated.
A first fluctuation detection unit that detects the amount of change in the detection output of the force sensor with time, and
An inclination sensor that detects the inclination of the housing and
A second fluctuation detection unit that detects the amount of change in the detection output of the tilt sensor with time, and
The amount of change in the detection output of the force sensor detected by the first fluctuation detection unit is less than a preset first threshold value, and the tilt sensor detected by the second fluctuation detection unit. When the amount of change in the detection output of the above is less than a preset second threshold value, the zero point setting unit that sets the output of the force sensor to the zero point, and the zero point setting unit.
Indentation test device equipped with. The indentation test apparatus according to claim 1, further
An indentation test device including a display unit that displays an error when the zero point is not set by the zero point setting unit. When the indenter pushed into the subject, the housing in which the indenter is arranged so that at least a part thereof protrudes from the end, and the housing is operated so as to push the indenter into the subject. It has an abutting portion that comes into contact with the subject after the indenter and a force sensor that detects a force acting on the indenter, and the abutting portion hits the subject with the operation. It is a zero point setting method of the indentation test device in which the force acting on the indenter at the time of contact is detected by the force sensor and the softness of the subject is calculated.
A first fluctuation detection step for detecting whether or not the amount of change in the detection output of the force sensor with time is less than a preset first threshold value, and
A second fluctuation detection step for detecting whether or not the amount of change in the detection output of the tilt sensor for detecting the tilt of the housing with time is less than the second threshold value, and
In the first fluctuation detection step, the change amount of the detection output of the force sensor is less than the first threshold value, and in the second fluctuation detection step, the change amount of the detection output of the tilt sensor is said. When the value is less than the second threshold value, the zero point setting step for setting the output of the force sensor to the zero point and the zero point setting step.
How to set the zero point of an indentation test device.

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