Stiffness control device, endoscope system, and stiffness control method

Abstract

The present invention is a rigidity control device for controlling a variable rigidity device having a variable rigidity member in which the flexural rigidity increases upon being heated, and a heater capable of heating the variable rigidity member, the rigidity control device being provided with a heater temperature detection unit for calculating information relating to the temperature of the heater, and a variable rigidity member temperature estimation unit for estimating information relating to the temperature of the variable rigidity member on the basis of the information relating to the temperature of the heater.

Description

[Technical field]

[0001] The present invention relates to a stiffness control device that has a stiffness varying device that changes the stiffness of an insertion section of an endoscope and controls the stiffness varying device, an endoscope system, and a stiffness control method for the stiffness control device. [Background technology]

[0002] Conventionally, various types of rigidity variable devices that change the rigidity of an endoscope insertion section are known. One type of rigidity variable device is a method of increasing rigidity by heating a shape memory alloy member (SMA) using a heater coil. For example, International Publication No. 2018 / 189888 discloses a configuration in which a shape memory alloy member (SMA) is formed into a pipe shape and a heating element (heater coil) is arranged coaxially with the SMA pipe.

[0003] Furthermore, as a method for controlling the stiffness of a shape memory alloy member (SMA), International Publication No. 2016 / 189683 discloses a technology for measuring the temperature of a heater coil by measuring the electrical resistance of the heater coil, and then calculating (estimating) the stiffness of the shape memory alloy member (SMA) based on the heater coil temperature.

[0004] Here, when controlling the temperature of a variable stiffness actuator consisting of a thin-diameter SMA pipe and a heater coil based on temperature detection of the heater coil, the following problem occurs. That is, because there is a small clearance between the heater coil and the SMA pipe, even if this clearance distance is small, it takes a certain amount of time for heat to be conducted from the heater coil to the SMA pipe. Therefore, when attempting to control heating with the aim of achieving fast response, a temperature difference occurs between the heater coil and the SMA pipe (shape memory alloy member), resulting in a problem of low accuracy in estimating the temperature (stiffness value) of the shape memory alloy member.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a stiffness control device, an endoscope system, and a stiffness control method for the stiffness control device that are capable of estimating the stiffness value of a shape memory alloy member with high accuracy. DISCLOSURE OF THEINVENTION [Means for solving the problem]

[0006] A stiffness control device according to one aspect of the present invention is a stiffness control device that controls a stiffness variable device having a stiffness variable member whose bending stiffness increases when heated and a heater capable of heating the stiffness variable member, the stiffness control device comprising: a heater temperature detection unit that calculates information regarding a temperature of the heater; before a stiffness variable member temperature estimating unit that estimates information regarding the temperature of the stiffness variable member; The stiffness variable member temperature estimating unit estimates information regarding the temperature of the stiffness variable member based on information regarding the temperature of the heater as a transfer function obtained by Laplace transforming a set heat conduction equation.

[0007] An endoscope system according to one aspect of the present invention includes an endoscope having an insertion section, a rigidity varying device having a rigidity variable member mounted on the insertion section and having bending rigidity increased by being heated, and a heater mounted on the insertion section and capable of heating the rigidity variable member, a heater temperature detection unit that calculates a temperature of the heater, and before A stiffness variable member temperature estimating unit that estimates a temperature of the stiffness variable member based on a temperature of the heater. The stiffness variable member temperature estimation unit estimates information about the temperature of the stiffness variable member based on information about the temperature of the heater as a transfer function obtained by Laplace transforming a set heat conduction equation. and a stiffness control device.

[0008] A stiffness control method according to one aspect of the present invention is a stiffness control method for controlling a stiffness variable device having a stiffness variable member whose bending stiffness is increased by heating and a heater capable of heating the stiffness variable member, the method comprising the steps of: Stiffness control device calculating information regarding a temperature of the heater; The stiffness control device Estimating a temperature of the stiffness variable member. The stiffness control device estimates information about the temperature of the stiffness variable member based on information about the temperature of the heater as a transfer function obtained by Laplace transforming a set heat conduction equation. do. [Brief description of the drawings]

[0009] [Figure 1]FIG. 1 is a perspective view showing the external appearance of a main part of an endoscope system including a stiffness control device according to a first embodiment of the present invention and an endoscope having a stiffness variable device controlled by the stiffness control device. FIG. [Diagram 2] FIG. 2 is a block diagram showing the configuration of a main part of the stiffness control device according to the first embodiment and the configuration of a stiffness varying device in the endoscope insertion portion. [Diagram 3] FIG. 3 is a graph showing the rise characteristics of the temperature of the shape memory member determined by the stiffness variable member temperature estimator in the stiffness control device according to the first embodiment. [Figure 4] FIG. 4 is a table showing a gain setting table used in the stiffness control device according to the second embodiment of the present invention. [Diagram 5] Figure 5 is a graph showing the relationship between the estimated temperature, target temperature, heater temperature and temperature of the shape memory member when the stiffness variable member temperature estimator in a stiffness control device of the third embodiment of the present invention estimates the temperature of the shape memory member. [Figure 6] FIG. 6 is a diagram showing the hysteresis characteristic of the SMA displacement amount with respect to the SMA temperature change of a shape-memory member disposed in the endoscope insertion portion according to the third embodiment. [Figure 7] FIG. 7 is a table showing a time constant setting table used in the stiffness control device according to the third embodiment. [Figure 8] FIG. 8 is a block diagram showing the configuration of a main part of a stiffness control device according to a fourth embodiment of the present invention, and the configurations of a stiffness varying device and a memory part in an endoscope insertion portion. BEST MODE FOR CARRYING OUT THEINVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] <First embodiment> FIG. 1 is an external perspective view of a main part showing the configuration of an endoscopic system having a stiffness control device according to a first embodiment of the present invention and an endoscope having a stiffness variable device controlled by the stiffness control device, and FIG. 2 is a block diagram showing the configuration of the main parts of the stiffness control device according to the first embodiment and the configuration of the stiffness variable device in an endoscope insertion portion.

[0012] As shown in Figures 1 and 2, an endoscopic system 1 according to a first embodiment of the present invention mainly comprises an endoscope 2 which is inserted into a subject and captures endoscopic images related to the inside of a body cavity, and a processor 3 which is connected to the endoscope 2 and performs predetermined image processing on the acquired endoscopic images and outputs the images to the outside.

[0013] The endoscope 2 includes an insertion section 11 to be inserted into a subject, an operation section 12 provided on the base end side of the insertion section 11, and a universal cord 13 extending from the operation section 12. The endoscope 2 is configured to be detachably connected to the processor 3 via a scope connector 13A provided at the end of the universal cord 13.

[0014] In this embodiment, a light source device (not shown) is provided inside the processor 3. A light guide (not shown) for transmitting illumination light supplied from the light source device and a predetermined electric cable 14 extending from the processor 3 are provided inside the insertion section 11, the operation section 12, and the universal cord 13.

[0015] The insertion section 11 is configured to have flexibility and an elongated shape. The insertion section 11 is configured by providing, in order from the tip side, a hard tip section 11A, a bending section 11B formed to be freely bendable, and a long flexible tube section 11C having flexibility.

[0016] The tip portion 11A is provided with an illumination window (not shown) for emitting illumination light transmitted by a light guide provided inside the insertion portion 11 to a subject. The tip portion 11A is also provided with an imaging section (not shown) configured to perform an operation according to an imaging control signal supplied from the processor 3, and to image a subject illuminated by illumination light emitted through the illumination window and output an imaging signal. The imaging section is configured to have an image sensor such as a CMOS image sensor or a CCD image sensor.

[0017] The bending portion 11B is configured so as to be able to be bent in response to the operation of an angle knob 12A provided on the operation portion 12.

[0018] In this embodiment, as will be described later in detail, within the rigidity variable range corresponding to a predetermined range from the base end of the bending section 11B to the tip end of the flexible tube section 11C, a rigidity variable section configured to be able to change the bending rigidity of the rigidity variable range according to the control of the processor 3 (rigidity control device) is provided. Device 20 is provided along the longitudinal direction of the insertion portion 11. Device The specific configuration etc. of 20 will be described in detail later.

[0019] In the following description, for the sake of convenience, the term "bending rigidity" will be abbreviated to simply "rigidity." In the present embodiment, the aforementioned variable rigidity range may be provided in at least a portion of the insertion portion 11.

[0020] The operation unit 12 is configured to have a shape that allows the user to grip and operate it. The operation unit 12 is also provided with an angle knob 12A configured to allow operation for bending the bending portion 11B in four directions, up, down, left, right (UDLR), intersecting with the longitudinal axis of the insertion portion 11. The operation unit 12 is also provided with one or more scope switches 12B that can give instructions according to input operations by the user.

[0021] < Variable stiffness Device20> Variable stiffness Device As shown in Figures 1 and 2, 20 is composed of an SMA pipe 21, a heater 22, and a thermally conductive member 23, and is capable of changing the bending rigidity within the rigidity variable range under the control of a processor 3 (rigidity control device).

[0022] The SMA pipe 21 is a variable stiffness member formed of a shape memory alloy (SMA) member having a small diameter pipe shape, and whose bending stiffness increases when heated. In this embodiment, the SMA pipe 21 is disposed along the longitudinal direction of the insertion section 11 in a predetermined range from the base end of the bending section 11B to the tip end of the flexible tube section 11C in the insertion section 11 of the endoscope 2. Note that, although the variable stiffness member in this embodiment has a small diameter pipe shape, the shape of the variable stiffness member is not limited to this, and variable stiffness members of various shapes can be used.

[0023] The heater 22 is composed of a heat coil arranged along the longitudinal direction on the inner diameter part of the SMA pipe 21. This heat coil is formed into a substantially cylindrical shape by winding a conductive material, which is conductive and generates heat when energized by receiving a supply of electric power, coaxially around the axis of the SMA pipe 21.

[0024] In this embodiment, the heater 22 is disposed inside the SMA pipe 21 which is a variable rigidity member, and the outer periphery of the cylindrical coil is disposed along the longitudinal direction while substantially abutting against the inner diameter part of the SMA pipe 21.

[0025] In this embodiment, the heater 22 is connected to a heater heating unit 32 in the processor 3, and generates heat by receiving power from the heater heating unit 32. The heating of the heater 22 is controlled by a heater heat amount control unit 31 also disposed in the processor 3. The heating control of the heater 22 will be described later.

[0026] When the heater 22 receives power and generates heat, its resistance value changes in response to changes in temperature, and accordingly, the voltage and current values ​​in the power supply line connected to the heater 22 also change. In this embodiment, information relating to the resistance value of the heater 22 is fed back to the processor 3 by measuring the voltage and current values ​​in the power supply line, and the temperature of the heater 22 is detected from the information relating to the resistance value of the heater 22, and further the temperature of the SMA pipe 21 is estimated from the temperature of the heater 22. The detection of the heater temperature and the estimation of the temperature of the SMA pipe 21 will be described in detail later.

[0027] The configuration of the SMA pipe 21 and the heater 22 may use the technology described in WO 2018 / 189888. However, this embodiment is characterized in that a thermally conductive member 23, which is not adopted in the technology described in WO 2018 / 189888, is filled between the heater 22 and the SMA pipe 21.

[0028] As described above, the thermally conductive member 23 is a characteristic component employed in this embodiment, and is made of a thermally conductive material having thermal conductivity at least higher than that of air. In this embodiment, the thermally conductive member 23 is disposed so as to fill the clearance between the heater 22 and the inner diameter part of the SMA pipe 21, which is a variable rigidity member, and serves to efficiently transfer heat generated in the heater 22 to the SMA pipe 21.

[0029] In this manner, in this embodiment, by disposing a thermally conductive member 23 between the SMA pipe 21, which is a shape memory alloy member (SMA), and the heater 22, which is a heater coil, the effect of reducing the temperature difference between the shape memory alloy member and the heater coil is achieved.

[0030] <Stiffness control device (processor 3)> In this embodiment, the processor 3 is connected to the endoscope 2 and has various well-known functions as a so-called video processor (image processing device), such as a function to perform predetermined image processing on the acquired endoscopic image and output it to the outside, and a function to control the connected endoscope 2. However, detailed explanation of these well-known functions of an image processing device will be omitted here, and the configuration having the characteristic functions of this embodiment will be described below.

[0031] FIG. 2 shows the configuration of the main part of the processor 3 as the stiffness control device according to this embodiment, and the stiffness variable device in the endoscope insertion section. 20 FIG. 2 is a block diagram showing the configuration of the embodiment;

[0032] As shown in FIG. 2, the processor 3 in this embodiment includes a configuration related to a known image processing function (not shown), as well as a configuration related to a rigidity variable sensor in the endoscope 2. Device It has the function of a stiffness control device that controls 20.

[0033] Specifically, the processor 3 is a variable stiffness Device 20, a heater heating unit 32, a heater heating amount control unit 31 (heater control unit) that controls the heater heating unit 32, and a stiffness variable Device The heater temperature detector 33 detects the temperature of the heater 22 in the heater 20 , and an SMA temperature estimator 34 estimates the temperature of the SMA pipe 21 based on the temperature of the heater 22 detected by the heater temperature detector 33 .

[0034] When the endoscope 2 is connected to the processor 3, the heater heating unit 32 is a variable stiffness heater arranged in the endoscope 2. Device Electric power is supplied to the heater 22 in 20 via a power supply line to cause the heater 22 to generate heat. At this time, the heater heating unit 32 supplies the electric power under the control of the heater heat amount control unit 31, based on heater heat amount information acquired from the heater heat amount control unit 31.

[0035] The heater heating amount control unit 31 acquires a predetermined SMA target temperature, calculates the heater heating amount to be applied to the heater 22 based on the acquired SMA target temperature and the SMA estimated temperature acquired from the SMA temperature estimation unit 34, and transmits information related to the heater heating amount to the heater heating unit 32.

[0036] Note that the heater heating amount control unit 31 also has a function of estimating the rigidity of the SMA pipe 21 based on the SMA estimated temperature acquired from the SMA temperature estimation unit 34.

[0037] The heater temperature detection unit 33 acquires voltage-current information related to the heater 22 from the endoscope 2. For example, it is connected to a signal line for measuring the voltage across both ends of the heater 22 to acquire information related to the heater voltage, and is connected to a power supply line for supplying power to heat the heater 22 to acquire the heater current. Then, the heater temperature detection unit 33 sequentially acquires information related to the resistance value of the heater 22 based on the acquired voltage-current information related to the heater 22. Further, the heater temperature related to the heater 22 is sequentially calculated from the relational expression between the heater resistance value and the heater temperature.

[0038] The SMA temperature estimation unit 34 acquires information on the heater temperature related to the heater 22 calculated by the heater temperature detection unit 33, and estimates the temperature (SMA temperature) of the SMA pipe 21, which is a shape memory member (hereinafter, sometimes abbreviated as SMA). At this time, in addition to the acquired heater temperature information, the SMA temperature estimation unit 34 estimates the SMA temperature related to the SMA pipe 21 based on a "heat conduction model" that takes into account the heat conduction characteristics of each of "between the heater 22 - SMA pipe 21", "the SMA pipe 21 itself", and "the surrounding environment of the SMA pipe 21".

[0039] Note that in this embodiment, the SMA temperature estimation unit 34 functions as a variable rigidity member temperature estimation unit.

[0040] <Estimation of SMA Temperature in the SMA Temperature Estimation Unit 34> Next, the method for estimating the SMA temperature in the SMA temperature estimation unit 34, which serves as a variable rigidity member temperature estimation unit, will be described.

[0041] The SMA temperature estimation unit 34 takes as input information about the temperature of the heater 22 calculated by the heater temperature detection unit 33, and outputs information about the temperature of the SMA pipe 21, which is a variable stiffness member, based on a function having a gain related to the temperature of the SMA pipe 21 relative to the temperature of the heater 22, and a time constant related to the speed of response of the SMA pipe 21 to temperature changes.

[0042] Specifically, the SMA temperature estimation unit 34 uses an equation derived from the set heat conduction equation to estimate the SMA temperature of the SMA pipe 21 with information on the temperature of the heater 22 as an input value.

[0043] <SMA Temperature Estimation Method in SMA Temperature Estimation Unit 34 in First Embodiment> The SMA temperature estimation method used by the SMA temperature estimator 34 in the first embodiment will now be described in more detail.

[0044] In the first embodiment, the heat conduction equation shown below is set, and the heat conduction equation is Laplace transformed to obtain a first-order transfer function, and the SMA temperature related to the SMA pipe 21 is estimated with the heater temperature as the input and the SMA estimated temperature as the output.

[0045] In the first embodiment, the "gain" and "time constant" are fixed values.

[0046] [Heat conduction equation in the first embodiment] TIFF0007611998000001.tif3284

[0047] m:SMA mass [g], c: SMA specific heat [J / g / K], T SMA : SMA temperature [K] (output value), t: time [s], K K :Average thermal conductivity from the heater coil to the SMA (mainly conductive material), AK :Average surface area of ​​heater coil to SMA (mainly conductive material), D K : Average thickness from heater coil to SMA (mainly conductive material), T HEATER : Heater temperature (input value) K S : Average thermal conductivity of the SMA surrounding environment (air space inside the scope, components inside the scope), A S :SMA surface area [m 2 ], D S : Average thickness to the SMA surroundings (air space inside the scope, components inside the scope) T e : SMA surrounding environment (air space inside the scope, components inside the scope) temperature [K]

[0048] [Laplace transformed first-order transfer function] The first-order transfer function obtained by Laplace transforming the above heat conduction equation is as follows: TIFF0007611998000002.tif5689TIFF0007611998000003.tif2888TIFF0007611998000004.tif2462

[0049] Here, "S" is the Laplace operator, which means the time derivative, and the output value is the SMA temperature T SMA As shown in FIG. 3, the signal rises smoothly over time.

[0050] Moreover, the "gain" and "time constant" are set to fixed values ​​in the first embodiment as described above.

[0051] Here, the input value of the heater temperature T HEATER When : is "1", TIFF0007611998000005.tif1770TIFF0007611998000006.tif29112TIFF0007611998000007.tif2367

[0052] "Gain" is the number of times the output (SMA temperature T SMA The "time constant" determines the time when the output becomes 63.2% of the gain (see Figure 3).

[0053] The stiffness control device according to the first embodiment may further include a shape detection unit that detects the shape of the insertion section 11 of the endoscope 2, and a selection unit that selects a heat conduction equation to be applied to the calculation from a plurality of different heat conduction equations according to the detected shape. The gap between the components of the endoscope 2 may change as the degree of bending of the insertion section 11 changes, but the presence of the shape detection unit and the selection unit makes it possible to select an optimal heat conduction equation that takes the change in gap into consideration. The shape detection unit may be, for example, a magnetic shape sensor.

[0054] <Advantages of the First Embodiment> As described above, according to the stiffness control device of the first embodiment, the accuracy of stiffness control of the SMA pipe 21 can be further improved by using an equation derived from a predetermined heat conduction equation to estimate the temperature of the shape memory alloy member (SMA pipe 21), which is a stiffness variable member also constituting the stiffness variable device, using temperature information of the heater 22 constituting the stiffness variable device as an input value.

[0055] <Second embodiment> Next, a second embodiment of the present invention will be described. The stiffness control device of the second embodiment has a basic configuration similar to that of the first embodiment, so only the differences will be described here. Note that, in the second embodiment, the heat conduction equation and the first-order transfer function obtained by Laplace transforming the heat conduction equation are similar to those in the first embodiment.

[0056] In the first embodiment, the "gain" is a fixed value, but the second embodiment is characterized in that the "gain" is a variable value.

[0057] That is, in the second embodiment, the SMA temperature estimation unit 34 acquires information about the heater temperature at the start of heating when the heater 22 starts heating the SMA pipe 21, which is a variable stiffness member, and sets the gain based on the information about the heater temperature at the start of heating. Specifically, the variable value of "gain" is set using a table of heater temperatures and gain values ​​as shown in Fig. 4.

[0058] In this embodiment, the table of heater temperatures and gain values ​​is assumed to be stored in the SMA temperature estimation unit 34, but may be stored in another storage unit in the processor 3.

[0059] If the surrounding environment Te varies, the gain that should be set will differ, but the heater temperature at the start of heating the SMA pipe 21 will be Heater temperature ≒ ambient temperature Te Therefore, in this embodiment, the gain is set according to Te at the start of heating the SMA pipe 21.

[0060] <Advantages of the second embodiment> As described above, the stiffness control device of the second embodiment achieves the same effects as the first embodiment, but by making the "gain" a variable value using a table of heater temperature and gain value, it is possible to more accurately estimate the temperature of the shape memory alloy member (SMA pipe 21), which is the stiffness variable member, and therefore to further improve the accuracy of stiffness control of the SMA pipe 21.

[0061] <Third embodiment> Next, a third embodiment of the present invention will be described. The stiffness control device of the third embodiment has a basic configuration similar to that of the first embodiment, so only the differences will be described here. Note that, in the third embodiment, the heat conduction equation and the first-order transfer function obtained by Laplace transforming the heat conduction equation are similar to those in the first embodiment.

[0062] In the first embodiment, the "time constant" is a fixed value, but in the third embodiment, the "time constant" is a variable value.

[0063] That is, in the third embodiment, the processor 3 is provided with a temperature history storage unit that records temperature history information related to the SMA pipe 21, and the SMA temperature estimation unit 34 sets the time constant based on the temperature history information. Specifically, the variable value of the "time constant" is set using a table such as that shown in FIG.

[0064] Here, Figure 5 is a graph showing the relationship between the estimated temperature, target temperature, heater temperature and temperature of the shape memory member when the stiffness variable member temperature estimator in the stiffness control device according to the third embodiment of the present invention estimates the temperature of the shape memory member, and Figure 6 is a diagram showing the hysteresis characteristics of the SMA displacement amount relative to the SMA temperature change of the shape memory member arranged in the endoscope insertion portion according to the third embodiment.

[0065] The specific heat c of the SMA pipe 21 changes during transformation of the shape memory alloy member SMA associated with the SMA pipe 21 and has hysteresis, so in this embodiment, the specific heat c is set based on the temperature history of the SMA.

[0066] That is, the specific heat of SMA increases due to austenite transformation, while the specific heat decreases due to martensite transformation, as shown in Figure 5. Also, as shown in Figure 6, the displacement of SMA has a certain hysteresis, and the specific heat also has hysteresis.

[0067] In this embodiment, the temperature history storage unit is assumed to be provided in the SMA temperature estimation unit 34, but may be provided in another location in the processor 3.

[0068] <Advantages of the Third Embodiment> As described above, the stiffness control device of the third embodiment achieves the same effects as the first embodiment, but by providing a temperature history storage unit that records temperature history information related to the SMA pipe 21 and having the SMA temperature estimation unit 34 set the time constant as a variable value based on the temperature history information, it is possible to more accurately estimate the temperature of the shape memory alloy member (SMA pipe 21), which is the stiffness variable member, and therefore to further improve the accuracy of stiffness control of the SMA pipe 21.

[0069] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described. The stiffness control device of the fourth embodiment has a basic configuration similar to that of the first embodiment, so only the differences will be described here. Note that, in the fourth embodiment, the heat conduction equation and the first-order transfer function obtained by Laplace transforming the heat conduction equation are similar to those in the first embodiment.

[0070] FIG. 8 is a block diagram showing the configuration of a main part of a stiffness control device according to a fourth embodiment of the present invention, and the configurations of a stiffness varying device and a memory part in an endoscope insertion portion.

[0071] 8, the fourth embodiment is characterized in that information relating to a "gain" and a "time constant" predetermined for each endoscope 2 is stored in a memory 25 in the endoscope 2. When a specific endoscope 2 is connected to a processor 3 in the stiffness control device of the fourth embodiment, an SMA temperature estimation unit 34 in the processor 3 acquires information specific to the endoscope 2 (information relating to the predetermined "gain" and "time constant") from the memory 25 in the connected endoscope 2, and estimates the SMA temperature of the SMA pipe 21 from the temperature of the heater 22 based on the information relating to the "gain" and "time constant."

[0072] <Effects of the Fourth Embodiment> As described above, the stiffness control device of the fourth embodiment achieves the same effects as the first embodiment, but information relating to the "gain" and "time constant" predetermined for each endoscope 2 is stored in memory 25 in the endoscope 2, and the SMA temperature estimation unit 34 estimates the SMA temperature of the SMA pipe 21 from the temperature of the heater 22 based on the information relating to the "gain" and "time constant" for the connected endoscope 2. Therefore, even when multiple types of endoscopes 2 are connected to a single processor 3, which is a stiffness control device, the SMA temperature of the SMA pipe 21 can be accurately estimated for each type of endoscope.

[0073] The present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention.

Claims

1. A stiffness control device for controlling a stiffness variable device having a stiffness variable member whose bending stiffness is increased by being heated and a heater capable of heating the stiffness variable member, a heater temperature detection unit that calculates information regarding the temperature of the heater; a stiffness variable member temperature estimator that estimates information regarding a temperature of the stiffness variable member; Equipped with The stiffness variable member temperature estimation unit estimates information regarding the temperature of the stiffness variable member based on information regarding the temperature of the heater as a transfer function obtained by Laplace transforming a set heat conduction equation, according to a stiffness variable member temperature estimation unit.

2. The stiffness variable member temperature estimating unit receives information about the temperature of the heater as an input value, and outputs information about the temperature of the stiffness variable member based on a function having a gain related to a convergence value of the temperature of the stiffness variable member with respect to the temperature of the heater and a time constant related to a convergence speed of the temperature of the stiffness variable member. The stiffness control device according to claim 1 .

3. The stiffness variable member temperature estimating unit acquires information regarding a heater temperature at the start of heating when the heater starts heating the stiffness variable member, and sets the gain based on the information regarding the heater temperature at the start of heating. The stiffness control device according to claim 2 .

4. A temperature history storage unit that records temperature history information of the rigidity variable member, The rigidity variable member temperature estimating unit sets the time constant based on the temperature history information. The stiffness control device according to claim 2 .

5. a heater control unit that controls the heater based on information about a temperature of the rigidity variable member; Further equipped The stiffness control device according to claim 1 .

6. The heater is conductive and generates heat when electricity is applied thereto. The heater temperature detection unit calculates the temperature of the heater based on information on a voltage and a current related to the heater. The stiffness control device according to claim 1 .

7. The rigidity variable member has a cylindrical shape, The heater is disposed inside the rigidity variable member and has a cylindrical shape. The stiffness control device according to claim 1 .

8. The rigidity variable member temperature estimating unit acquires information on a heater temperature at the start of heating when the heater starts heating the rigidity variable member, and estimates a temperature of the rigidity variable member based on the information on the heater temperature and the heater temperature at the start of heating. The stiffness control device according to claim 1 .

9. A temperature history storage unit that records temperature history information of the rigidity variable member, The stiffness variable member temperature estimating unit estimates the temperature of the stiffness variable member based on information about the heater temperature and the temperature history information. The stiffness control device according to claim 1 .

10. The stiffness control device described in claim 1, characterized in that the heat conduction equation is as follows. however, m: SMA mass [g], c: SMA specific heat [J / g / K], TSMA:SMA temperature [K] (output value), t: time [s], K K : Average thermal conductivity from the heater coil to the SMA (mainly conductive material), A K : Average surface area from the heater coil to the SMA (mainly conductive material), D K : Average thickness from the heater coil to the SMA (mainly conductive material), T HEATER: Heater temperature (input value) K S : Average thermal conductivity of the SMA surrounding environment (air layer inside the scope, components inside the scope), A S :SMA surface area [m 2 ], D S : Average thickness to the SMA surroundings (air layer inside the scope, components inside the scope), T e : Temperature of the SMA surrounding environment (air layer inside the scope, components inside the scope) [K]

11. A stiffness control device as described in claim 10, characterized in that a transfer function obtained by Laplace transforming the heat conduction equation is as follows. Here, "S" is the Laplace operator, which means time differentiation.

12. An endoscope having an insertion section, a rigidity variable device having a rigidity variable member mounted on the insertion section and heated to increase bending rigidity, and a heater mounted on the insertion section and capable of heating the rigidity variable member; a stiffness control device including a heater temperature detection unit that calculates a temperature of the heater, and a stiffness variable member temperature estimation unit that estimates a temperature of the stiffness variable member based on the temperature of the heater, wherein the stiffness variable member temperature estimation unit estimates information regarding the temperature of the stiffness variable member based on information regarding the temperature of the heater as a transfer function obtained by Laplace transforming a set heat conduction equation; An endoscope system comprising:

13. A thermally conductive material having a thermal conductivity higher than that of air is filled between the heater and the rigidity variable member. The endoscope system according to claim 12 .

14. The rigidity variable member temperature estimating unit is a function that takes information about the temperature of the heater as an input value and outputs information about the temperature of the rigidity variable member, the function having a gain related to a convergence value of the temperature of the rigidity variable member with respect to the temperature of the heater and a time constant related to a speed of convergence of the temperature of the rigidity variable member, and outputs the information about the temperature of the rigidity variable member based on the function. The endoscope system according to claim 12 .

15. The endoscope has a memory in which information relating to the gain and the time constant is pre-stored. The endoscope system according to claim 14 .

16. The stiffness control device controls the heater based on information regarding a temperature of the stiffness variable member. The endoscope system according to claim 12 .

17. The heater is electrically conductive and heats when electricity is passed through it, The stiffness control device calculates the temperature of the heater based on information on the voltage and current associated with the heater. The endoscope system according to claim 12 .

18. The rigidity variable member is cylindrical, The heater is disposed inside the rigidity variable member and has a cylindrical shape. The endoscope system according to claim 12 .

19. An endoscopic system as described in claim 12, characterized in that the heat conduction equation is as follows: however, m: SMA mass [g], c: SMA specific heat [J / g / K], TSMA:SMA temperature [K] (output value), t: time [s], K K : Average thermal conductivity from the heater coil to the SMA (mainly conductive material), A K : Average surface area from the heater coil to the SMA (mainly conductive material), D K : Average thickness from the heater coil to the SMA (mainly conductive material), T HEATER: Heater temperature (input value) K S : Average thermal conductivity of the SMA surrounding environment (air layer inside the scope, components inside the scope), A S :SMA surface area [m 2 ], D S : Average thickness to the SMA surroundings (air layer inside the scope, components inside the scope), T e : Temperature of the SMA surrounding environment (air layer inside the scope, components inside the scope) [K]

20. An endoscopic system as described in claim 19, characterized in that the transfer function obtained by Laplace transform of the heat conduction equation is as follows. Here, "S" is the Laplace operator, which means time differentiation.

21. A stiffness control method for controlling a stiffness variable device having a stiffness variable member whose bending stiffness is increased by heating and a heater capable of heating the stiffness variable member, comprising: a stiffness controller calculating information regarding the temperature of the heater; The stiffness control device estimating a temperature of the stiffness variable member; having The stiffness control method, characterized in that the stiffness control device estimates information regarding the temperature of the stiffness variable member based on information regarding the temperature of the heater as a transfer function obtained by Laplace transforming a set heat conduction equation.

22. The stiffness control device outputs information about the temperature of the stiffness variable member based on a function that uses information about the temperature of the heater as an input value and outputs information about the temperature of the stiffness variable member, the function having a gain related to a convergence value of the temperature of the stiffness variable member with respect to the temperature of the heater and a time constant related to a speed of convergence of the temperature of the stiffness variable member.

22. The method of claim 21 .

23. The stiffness control device obtains information regarding a heater temperature at the start of heating when the heater starts heating the stiffness variable member, and sets a gain based on the information regarding the heater temperature at the start of heating.

22. The method of claim 21 .

24. Further comprising a temperature history storage unit for recording temperature history information of the rigidity variable member, The time constant is set based on the temperature history information.

23. The method of claim 22, wherein the stiffness control method comprises:

25. The stiffness control method described in claim 21, characterized in that the heat conduction equation is as follows: however, m: SMA mass [g], c: SMA specific heat [J / g / K], TSMA:SMA temperature [K] (output value), t: time [s], K K : Average thermal conductivity from the heater coil to the SMA (mainly conductive material), A K : Average surface area from the heater coil to the SMA (mainly conductive material), D K : Average thickness from the heater coil to the SMA (mainly conductive material), T HEATER: Heater temperature (input value) K S : Average thermal conductivity of the SMA surrounding environment (air layer inside the scope, components inside the scope), A S :SMA surface area [m 2 ], D S : Average thickness to the SMA surroundings (air layer inside the scope, components inside the scope), T e : Temperature of the SMA surrounding environment (air layer inside the scope, components inside the scope) [K]

26. The stiffness control method described in Claim 25, characterized in that the transfer function obtained by Laplace transforming the heat conduction equation is as follows. Here, "S" is the Laplace operator, which means time differentiation.

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