Force sensor device, force measurement method, load cell, robot hand and robot arm

Abstract

To provide a force sensor device and a force measurement method capable of changing a measurement range and sensitivity, and also to provide a load cell, a robot hand, and a robot arm using the force sensor device.SOLUTION: A force sensor device 11 is a distorted body 21 which is distorted by receiving external forces W1 and W2 and includes: a cantilever-like distorted body 21 whose one end part is fixed; and a distortion gauge 30 which is an example of measurement means for measuring a deformation amount of the distorted body 21. The distorted body 21 can be deformed from a distorted body 20, and a deformed state is maintained. Since the force sensor device 11 can change the relationship between the distortion ε of the distorted body 21 and the external forces W1, W2 due to the deformation of the distorted body 21, a measurement range and sensitivity can be changed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a force sensor device and force measurement method that include a strained body that is strained by an external force and a measuring means for measuring the amount of deformation of the strained body, as well as a load cell, a robot hand, and a robot arm that use the force sensor device. [Background technology]

[0002] A conventional force sensor device that measures the amount of applied force by measuring strain is known to include a cantilevered object with one end fixed and the other end free, and a measuring means for measuring the amount of deformation of the object, such as a strain gauge. In such a cantilever-shaped force sensor device, the measurement range and sensitivity cannot be changed, but a conventional force sensor device that can be changed is known from Patent Document 1.

[0003] The sensing device described in Patent Document 1 comprises a beam layer supported at one end by a spacer, a functional fluid layer in contact with the beam layer and having a functional fluid sealed within an elastic body, an application unit that applies an electromagnetic field to the functional fluid, and a detection unit that detects the amount of deflection of the beam layer, and is configured so that the electromagnetic field determines the spring constant of the functional fluid layer and sets the measurement range of external force based on the amount of deflection detected by the detection unit when an external force is applied to the beam layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-141720 [Non-patent literature]

[0005] [Non-Patent Document 1] Yu Mukai et al., "Principles and Structure of Six-Axis Force Sensors," Journal of the Japan Society for Precision Engineering, Vol. 84, No. 4, 2018, pp. 303-306 Summary of the Invention [Problem to be solved by the invention]

[0006] In the sensing device described in Patent Document 1, the spring constant of the functional fluid is determined by applying an electromagnetic field, and by increasing or decreasing this spring constant, the cantilever beam is made more or less flexible, thereby widening the measurement range from small forces to large forces. However, while the sensing device described in Patent Document 1 can change its measurement range and sensitivity, it is a unique device that applies an electromagnetic field to a functional fluid to change the spring constant of the functional fluid layer in which the functional fluid is sealed. The sensing device described in Patent Document 1 has a limited measurement range because its measurement characteristics depend on the preset material properties of the functional fluid. Furthermore, changing the spring constant of the functional fluid requires the continuous application of an electromagnetic field, which can consume energy such as power and potentially generate noise in the measuring equipment due to the generated electromagnetic field. Therefore, the impact of the measurement environment must be taken into consideration when making measurements. If the measurement range and sensitivity of a force sensor device can be changed, its applications can be expanded and it can be adapted to changes in the measurement environment. In other words, one sensor can be used for various purposes without replacement, leading to cost savings.

[0007] Therefore, an object of the present invention is to provide a force sensor device and a force measurement method that allow the measurement range and sensitivity to be changed without affecting the measurement environment, as well as a load cell, a robot hand, and a robot arm that use the force sensor device. [Means for solving the problem]

[0008] The force sensor device of the present invention comprises a deformable body that is distorted by an external force and a measuring means for measuring the amount of deformation of the deformable body, and is characterized in that the deformable body is deformable and maintains its deformed state.

[0009] The force measurement method of the present invention is characterized in that, when measuring the deformation amount using a force sensor device equipped with a deformable body that deforms when subjected to an external force and a measuring means for measuring the deformation amount of the deformable body, it includes the steps of deforming the deformable body, applying an external force while the deformable body is in a deformed state, and measuring the deformation amount of the deformable body using the measuring means.

[0010] According to the present invention, the relationship between the deformation amount of the strained body and the external force can be changed by deforming the strained body.

[0011] In the force sensor device and the force measuring method of the present invention, the object to be strained may be made of a shape memory material. The shape memory material may be made of a shape memory polymer.

[0012] The deformable body can be provided with a temperature adjusting means for changing and fixing the shape of the body. If the temperature adjusting means is provided on either the deformable body or the forming mold, the deformable body can be deformed by adjusting the temperature. Since the deformable body is made of a shape memory material, the shape can be changed and fixed by adjusting the temperature of the deformable body using a temperature adjustment means after the shape is deformed, or by adjusting the temperature while molding using a molding die equipped with a temperature adjustment means.

[0013] The strained body may be formed in a plate shape, and by forming the strained body in this manner, it can be deformed by bending the lengthwise direction at any angle in the plate thickness direction or bending the widthwise direction toward the front surface or the back surface.

[0014] The strained body may be formed in a rod shape. By forming the strained body in this manner, it is possible to bend and deform the lengthwise direction at any angle.

[0015] The strained body may be formed in a cantilever shape, folded back one or more times to the cantilever position, and fixed in place. By forming the strained body in this manner, the overall length of the strained body in the longitudinal direction can be shortened, and the thickness of the strained body can be increased.

[0016] The strained body may be formed into a plate shape by bending the sides in a width direction perpendicular to the length direction. By forming the strained body in this way, the thickness of the strained body can be changed.

[0017] The strained body may be formed into a cylindrical shape by bending a side portion in a width direction perpendicular to the length direction. By forming the strained body in this manner, the rigidity of the strained body can be increased. Here, the longitudinal direction is the direction from one end of the fixed strained body to the other end, which is the free end, in the case of a cantilever beam, or the direction connecting the two ends, in the case where both ends are fixed.

[0018] The mounting form of the strained body can be set to any one of a cantilever type, a double-end supported type, a double-end fixed type, and a diaphragm type. In this way, the strained body of the present invention can be applied to various types of force sensor devices.

[0019] According to the force measuring method of the present invention, the method can include a step of deforming the strained body using a forming die before deforming the strained body. By doing so, the body to be deformed can be accurately deformed along the outer shape of the forming die.

[0020] When deforming the strained body using the forming mold, the method can include a step of deforming a range including the longitudinal position where the measuring means is installed, and a step of measuring the amount of deformation of the strained body deformed by the forming mold using the measuring means before the actual measurement. By measuring the strain of the deformed object before measurement, the amount of deformation under no load can be measured. Therefore, even if the object has been deformed using a mold with a similar shape, it is possible to determine which mold caused the deformation, making calibration after changing the shape unnecessary.

[0021] The load cell of the present invention has a rod portion to which an external force is applied, a movable portion that moves together with the rod portion, and a fixed portion, and the force sensor device of the present invention is provided between the movable portion and the fixed portion.

[0022] The robot hand of the present invention has an arm section and a gripping section for gripping an object on the arm section, and the force sensor device of the present invention is provided on the gripping section.

[0023] In the robot hand of the present invention, the force sensor device may be provided detachably.

[0024] The robot arm of the present invention has a shoulder and an arm extending from the shoulder, and is provided with the force sensor device of the present invention.

[0025] In the robot arm of the present invention, the sensor assembly having the force sensor device can be provided detachably. [Effects of the Invention]

[0026] According to the present invention, by deforming the deformable body, the relationship between the deformation amount of the deformable body and the external force can be changed, so that the measurement range can be changed before and after deformation, and the sensitivity can also be changed. [Brief explanation of the drawings]

[0027] [Figure 1] 1A and 1B are diagrams for explaining a force sensor device according to an embodiment of the present invention, in which FIG. 1A is a diagram showing the state before deformation of the strained body of the force sensor device, and FIG. 1B is a diagram showing the state after the tip of the strained body is bent. [Figure 2] 2 is a diagram showing the arrangement of a heater for heating the strain-receiving body when the strain-receiving body of FIG. 1 is made of a shape memory polymer. FIG. [Figure 3] 2 is a diagram of the force sensor device in a state where the strain target shown in FIG. 1 is folded in half. [Figure 4] 2A and 2B are views of the strained body shown in FIG. 1 viewed in the longitudinal direction, where (A) is a view of the strained body formed with a square cross section, and (B) is a view of the strained body with both side portions folded toward the back surface and integrated. [Figure 5] 2A and 2B are views of the strained body shown in FIG. 1 viewed in the longitudinal direction, where (A) is a view of the strained body formed into a rectangular tubular cross section, and (B) is a view of the strained body after both sides are bent toward the rear surface to form a rectangular tubular shape with a hollow portion. [Figure 6] 2A and 2B are views of the strained body shown in FIG. 1 viewed in the longitudinal direction, where (A) is a view of the strained body formed into a cylindrical cross section, and (B) is a view of the strained body after both sides are bent toward the rear side to form a cylindrical shape with a hollow portion. [Figure 7] 10A and 10B are diagrams for explaining another example of a force sensor device according to an embodiment of the present invention. [Figure 8] 1 is a diagram illustrating an acceleration sensor using a force sensor device according to the present invention. [Figure 9] 2A and 2B are diagrams for explaining a force measurement method using the force sensor device shown in FIG. 1, in which (A) is a diagram showing the initial state before deformation, (B) is a diagram for explaining the state in which a strained body is deformed using a forming die, and (C) is a diagram showing the force sensor device having a strained body after deformation. [Figure 10] 9A and 9B are diagrams for explaining an automatic forming device that automatically deforms the force sensor device shown in FIG. 8, in which (A) is a diagram for explaining the state in which the automatic forming device deforms the strained body, and (B) is a diagram for explaining the state of the strained body after deformation. [Figure 11]1A and 1B are diagrams for explaining a load cell using the force sensor device of the present invention, in which (A) is a plan view of the load cell and (B) is a side view. [Figure 12] 1 is a diagram illustrating a robot hand using a force sensor device according to the present invention. [Figure 13] 1A and 1B are diagrams for explaining a robot arm using a force sensor device of the present invention, in which (A) shows the robot arm and (B) shows the configuration of a tactile sensor. DETAILED DESCRIPTION OF THE INVENTION

[0028] <Explanation of the force sensor device> A force sensor device according to an embodiment of the present invention will be described with reference to the drawings. To facilitate understanding of the present invention, the embodiment of the present invention will be described with a focus on a cantilever-shaped configuration (hereinafter, sometimes referred to as a "cantilever type") as an example. In this specification, the left-right direction (length direction) in the drawings will be described as the X direction, the depth direction (width direction) as the Y direction, and the up-down direction (height direction, thickness direction) as the Z direction. The following description of the components is an example of an embodiment of the present invention, and the present invention is not limited to the following content unless the gist of the present invention is changed.

[0029] First, the force sensor device before deformation will be described with reference to FIG. The force sensor device 10 shown in FIG. 1(A) is configured to include a cantilever-shaped strain object 20 that strains when subjected to an external force, and a measuring means 30 that measures the amount of deformation of the strain object 20 in the Z direction (thickness direction). In the force sensor device 10 shown in FIG. 1(A), a strain gauge is used as a measuring means, but the measuring means for measuring the deformation of the strained body is not limited to this, and various types of measuring means, such as a piezoelectric body described later, can be selected and used as appropriate. The strain target 20 is formed in the shape of a long, thin plate. In Fig. 1(A), the strain target 20 is formed in a linear shape. To form the strain object 20 in a cantilever shape, a base end 20b (one end) is fixed to a fixing portion 42 erected on a base portion 41. The strain object 20 is formed so as to extend from a cantilever position 20p to a tip end 20f (the other end). The tip end 20f is formed as a free end.

[0030] <Configuration of the object to be deformed> The strained body 20 can be any body that is deformable and maintains its deformed state due to the material properties of the material used for the strained body. For example, the strained body 20 can be made of metal or resin. The material properties are, for example, characteristics consisting of mechanical properties specific to the material, such as strength, rigidity, hardness, ductility / toughness, and yield point, as shown in materials mechanics and structural mechanics. In a force sensor device, when the shape of the strained body is changed, the applied load is measured while the deformed shape is maintained due to the material properties of the strained body.

[0031] When the strain target body 20 is made of metal, various materials can be used, including various metals such as iron, aluminum, gold, silver, and copper, and various alloys such as stainless steel. When it is made of resin, polyurethane, PET (Polyethylene terephthalate), PP (polypropylene), polynorbornene, etc. are possible. Furthermore, the strain target body 20 does not need to be made of a single material, and can also be made of plates made of multiple materials bonded together, or a composite material.

[0032] The strained body 20 may be made of a shape memory material. The shape memory material may be, for example, a shape memory polymer (SMP) or a shape memory alloy such as a titanium-nickel alloy. When a shape memory polymer is used, for example, MP4510 by SMP Technologies may be used.

[0033] <Configuration of temperature adjustment means> The distortion target 20 made of a shape memory material can be provided with a temperature adjustment means capable of adjusting the temperature of the distortion target 20. In the example shown in Fig. 2, a temperature adjustment heater H is provided, and in this embodiment, since the distortion target 20 is made of a shape memory polymer, the temperature adjustment heater H is embedded in the distortion target 20. Furthermore, when the distortion target 20 is made of a shape memory alloy, the temperature adjustment heater H is arranged in contact with or adjacent to the distortion target 20 so that the temperature of the distortion target can be adjusted by the heat applied from the temperature adjustment heater H.

[0034] The temperature adjusting means can use a temperature adjusting heater H when heating, and a blower (not shown) when cooling. The temperature control heater H heats the strained body 20 to a temperature higher than the glass transition temperature Tg, and then cools it to a lower temperature using a blower to fix the changed shape of the strained body 20. For example, if the strained body 20 made of a shape memory polymer has a glass transition temperature Tg of 45°C, the temperature control heater H of the temperature adjustment means can heat it to a temperature higher than 45°C, and the blower can cool it to a temperature below 45°C.

[0035] The temperature control heater H has two parallel heating wires that snake in a continuous crank shape from the base end 20b of the strain object 20 toward the tip end 20f, where they are short-circuited at the tip end 20f. The temperature control heater H is formed in a continuous crank shape, which reduces deformation resistance to bending and expansion and contraction compared to when the temperature control heater is formed linearly in the X direction (length direction) and embedded. The arrangement of the temperature control heater H is not limited to this form, and can be set according to the measurement conditions, measurement environment, etc., such as the direction of the load applied to the strain object as described above.

[0036] In this way, by heating and cooling the strained body 20 using the temperature adjustment means, the strained body 20 can be changed into any shape. Specifically, the strained body 20 is heated to or above the glass transition temperature Tg to soften it, and the strained body 20 can be changed into any shape or restored to its pre-deformed state. Alternatively, the strained body 20 can be cooled to or below the glass transition temperature Tg to be fixed into a predetermined shape, which is then maintained. In other words, if a shape-memory material is used for the strained body, the temperature of the strained body is adjusted based on the glass transition temperature Tg and shape-memory temperature characteristics, such as the transformation temperature characteristics described below, and the shape changed by deformation is fixed and maintained. The force sensor device measures the load while this fixed shape is maintained.

[0037] While the above example shows the use of a temperature control heater H and an air blower as the temperature control means, the present invention is not limited to this, as long as it is capable of heating and cooling the object to be deformed 20. It is also possible to use an electrical heating / cooling means using a Peltier element or the like, or a heat pipe-type temperature control means using a liquid or gas medium, such as circulating a liquid or gas inside a tubular body, or to use a sheet-shaped temperature control heater H. It is also possible to configure the temperature control means, such as the heating and cooling rate, to control the timing of the shape change of the object to be deformed 20. This allows the object to be deformed 20 to be controlled so that it assumes a predetermined shape during measurement, improving the efficiency of the measurement process.

[0038] In other examples, the temperature adjustment means may be arranged to adjust the temperature of the portion of the strained body 20 that requires heating or cooling, or may be arranged to control the temperature of each portion of the strained body 20 that requires heating or cooling using a temperature adjustment means capable of controlling multiple different temperature ranges, thereby changing and controlling the shape of the strained body 20. For example, if a sheet-shaped temperature adjustment means is used as the temperature adjustment means, multiple temperature adjustment means may be used and arranged at different locations on the strained body 20, or a device with its own heating / cooling region and temperature that can be set and controlled may be used, allowing one or more specific regions of the strained body 20 to be heated or cooled. This allows the shape of the strained body 20 to be changed according to the measurement range and sensitivity required during measurement, resulting in more optimal measurements. Furthermore, by controlling the heating / cooling region and temperature range, the shape of the strained body 20 can be controlled, allowing for automation.

[0039] When the object to be deformed is a shape memory alloy, the shape memory alloy has a transformation temperature characteristic that changes the metal structure (parent phase). This temperature is the temperature Ms (hereinafter also referred to as the "transformation start temperature") at which the transformation of the metal structure (parent phase) begins and ends (hereinafter also referred to as the "transformation finish temperature"), and the temperature As (hereinafter also referred to as the "reverse transformation start temperature") at which the transformation of the metal structure to the parent phase that the alloy originally possesses, i.e., the temperature Af (hereinafter also referred to as the "reverse transformation finish temperature"), at which the transformation of the metal structure to the parent phase that the alloy remembers, begins and ends. Furthermore, when utilizing the shape memory effect due to the transformation temperature characteristic, this transformation temperature characteristic is set higher than the temperature of the environment, such as the ambient temperature. For example, according to the intensive research of the inventors of the present invention, a shape memory alloy with a reverse transformation start temperature As of 60°C was used and its transformation temperature characteristic was confirmed.

[0040] When a shape memory alloy is used as a strain target, the shape of the strain target below Ms can be changed and fixed based on the transformation temperature characteristics, and the load can be measured using a force sensor device. Furthermore, since the lower the temperature of a shape memory alloy, its rigidity is lower, so when it is deformed, it is possible to do so without the need for temperature adjustment by heating, etc., as with shape memory polymers.

[0041] Furthermore, the changed shape of the object can be restored by raising the temperature of the object to above the reverse transformation start temperature As. One possible method for raising the temperature of the object is to heat it by passing electricity directly through it. Specifically, this method involves connecting electrodes to the object, passing electricity through them, and heating the object with the Joule heat generated by the current, thereby restoring it to its original shape.

[0042] In this way, when the strained body is made of a shape memory alloy, the shape of the strained body is changed, fixed, or returned to its original shape based on the transformation temperature characteristics, and the load is measured while this fixed shape is maintained.

[0043] Typically, when performing measurements using a force sensor device, the force sensor device is considered and its specifications are set based on the measurement environment and conditions, such as its placement relative to the measurement object and the conditions required for the acquired data. Furthermore, during measurements, the force sensor device is replaced as appropriate depending on the required measurement range and sensitivity. On the other hand, when a shape-memory material is used as the deformable body, the temperature adjustment of the deformable body as described above allows the deformable body to return to its pre-change shape while retaining its material properties, without changing its shape. Therefore, for example, if a change in the measurement environment or conditions, such as a change in measurement range or sensitivity, is required based on data obtained during measurement, the same deformable body can be temporarily restored to its original shape and then reshaped to achieve the required measurement range and sensitivity, without replacing the sensor as described above. In this way, when a shape-memory material is used as the deformable body, it is possible to perform measurements using the same deformable body by changing the measurement range or sensitivity depending on the measurement situation, while maintaining the inherent material properties of the deformable body.

[0044] <Principle of the force sensor device> Next, the principles and operating characteristics of the force sensor device will be described. The strained body 20 shown in Figure 1(A) is formed in a straight line and has a rectangular cross section. It is also possible to set the initial shape to a curved shape rather than a straight line. Therefore, when a uniform bending moment M is applied by an external force W, the bending moment M can be expressed by the following equation (1). where E is the elastic modulus of the strained body 20, ε is the strain in the X direction (length direction) of the strained body 20 that can be detected by the measuring means 30 (the strain indicates the ratio of the strained body 20 changed from its original state, with the extension direction being positive), and Z is the cross-sectional modulus of the strained body 20 whose cross section is formed into a rectangular shape.

[0045]

number

[0046] Here, if the distance from the pressure point where the external force W is applied to the measuring means 30 is taken as x, the bending moment M can be expressed by the formula (2).

[0047]

number

[0048] Therefore, the relationship between the external force W and the strain ε can be expressed by equation (3).

[0049]

number

[0050]

number

[0051] Next, FIG. 1(B) shows an example of a force sensor device that is deformed and maintains the deformed state of the force sensor device shown in FIG. 1(A). The strained body 21 of the force sensor device 11 shown in FIG. 1(B) is formed by bending the tip 20f of the strained body 20, which extends in the X direction shown in FIG. 1(A), in the Z direction, to form a bent shape. Specifically, the tip 20f of the linear strained body 20 is bent downward by 90° in the Z direction (thickness direction) to form the bent portion 21c as shown in FIG. 1(B). When an external force W1 is applied to the bent tip 21e in the -X direction (length direction) at the cantilever position 21p, the bending moment M can be expressed by Equation (5), where x1 is the length of the bent portion 21c.

[0052]

number

[0053] Therefore, the external force W1 can be expressed by equation (6) from equations (4) and (5).

[0054]

number

[0055] Similarly, when an external force W2 directed upward (in the Z direction (thickness direction)) perpendicular to the X direction is applied to the tip 21e of the bent portion 21c, the external force W2 can be expressed by equation (7), where x2 is the length from the cantilever position 21p to the bent position. Note that in equation (7), the deformation of the measuring means 30 in the Z direction due to the external force W2 is considered positive.

[0056]

number

[0057] In the force sensor device 11 shown in FIG. 1(B), the strained body 21 is formed in a plate shape. Therefore, the tip 21f of the tip can be bent in the Z direction (thickness direction) from a bending position that is a predetermined distance from the cantilever position 21p (fixed position). This allows the overall length of the strained body 21 in the X direction (lengthwise direction) to be shortened, and the tip 21f of the strained body 21 can be oriented in a direction different from the tip 20f of the strained body 20. This allows for measurement of external forces W in multiple different directions, such as external forces W1 and W2 shown in FIG. 1(B), in addition to external forces W in a specific direction as shown in FIG. 1(A). Furthermore, when measuring external force W2 with the force sensor device 11 shown in FIG. 1(B), the distance from the measuring means 30 decreases from x (see FIG. 1(A)) to x2, resulting in a larger change in the external force relative to strain. This allows for a wider measurement range of the force sensor device 11.

[0058] 1(B), when distance x1<distance x2, in measuring external forces W1 and W2 in multiple different directions, the measurement of external force W1 has a wider measurement range than the measurement of external force W2 because distance x1 is shorter, while the measurement of external force W2 can be performed with higher sensitivity than the measurement of external force W1 because distance x2 is longer than distance x1. In this way, by being able to measure external forces W1 and W2 in multiple different directions, it is possible to change or select the measurement range or sensitivity depending on the direction in which the external force is applied.

[0059] Continuing from the example shown in FIG. 1(B), another example of a force sensor device 12 will be described with reference to FIG. 3. The strained body 22 of the force sensor device 12 shown in FIG. 3 is folded back one or more times to the cantilever position 22p and fixed. In this embodiment, the tip 22f of the strained body 22 is folded back once to the cantilever position 22p of the strained body 22, so that the strained body 22 is folded in half, and the tip 22f is fixed at the cantilever position 22p. By integrating the folded portions in this way, the entire strained body 22, which becomes the beam portion, becomes thicker. Since the strained body 22 is folded in half, Equation (4) can be expressed as Equation (8).

[0060]

number

[0061] As described above, by folding the cantilever-shaped strained body 20 shown in Figure 1(A) in half or in three as shown in Figure 3 and fixing it at the cantilever position, the thickness of the strained body 22 can be increased, thereby increasing the rigidity of the strained body 22 and shortening the length of the strained body 22.

[0062] In this way, the measurement range or sensitivity of the force sensor device can be adjusted mainly by changing the rigidity of the strained body 22. Furthermore, as shown in Figure 3, by simultaneously changing the distance x3 from the measuring means 30 to the external force W3, it is possible to perform measurements over a wider measurement range.

[0063] Although the strain targets 21 and 22 of the force sensor device 11 shown in Fig. 1(B) and the force sensor device 12 shown in Fig. 3 are formed in a plate shape, they may be formed in a strip or rod shape. In this case, in addition to the folded shape as described above, they may be bent one or more times in the X direction, Y direction, or Z direction, or twisted around the X direction.

[0064] As another example of changing the rigidity of the strained body as shown in FIG. 3, a force sensor device in which the side portion in the Y direction perpendicular to the X direction from the cantilever position toward the tip of the force sensor device shown in FIG. 1(A) is bent will be described with reference to FIGS. 4 to 6.

[0065] For example, in the case of a strained body having a rectangular cross section as shown in Figure 4(A), the section modulus Z is 1 / 6 × bh 2 4(B), both side portions 23s in the Y direction are bent to the back side opposite to the front side on which the measuring means 30 is mounted, thereby doubling the thickness of the plate. Therefore, the thickness is 2h and the width is b / 2, so the section modulus Z1 is given by the following equation (9).

[0066]

number

[0067] 4(B), both side portions 23s of the strained body 23 are bent so that the plate thickness is doubled, but it is also possible to bend only one side portion 23s.Furthermore, the entire side portion of the strained body can be bent, or only a part of it can be bent.

[0068] In addition, for a deformed body having a rectangular cylindrical cross section as shown in Figure 5(A), the section modulus Z is 1 / 6 × (b1h1 3 -b2h2 3) / h1. The strain object 24 shown in Fig. 5(B) is formed in a rectangular cylindrical shape by forming a rectangular cylindrical cavity 24c in the axial center when both side portions 24s in the Y direction (width direction) are bent toward the rear surface. Therefore, the thickness is b / 4 and the width is b / 4, so the section modulus Z2 is given by the following equation (10).

[0069]

number

[0070] In FIG. 5(B), the strained body 24 is formed in a rectangular cylindrical shape, but it can also be formed in a polygonal shape such as a triangular or pentagonal cylindrical shape, a horizontal J-shape with only one side bent, or a horizontal U-shape with the opening facing downward.

[0071] Furthermore, in the case of a cylindrical cross section of the strained body as shown in FIG. 6(A), the section modulus Z is π / 32×(d1 4 -d2 4 ) / d1. The strain object 25 shown in Fig. 6(B) is formed into a cylindrical shape by forming a cylindrical cavity 25c in the axial center when both side portions 25s in the Y direction are bent toward the rear surface. Therefore, since the circumference b is πd1, the section modulus Z3 is given by the following equation (11).

[0072]

number

[0073] In this way, the cantilever-shaped strain target 20 shown in Fig. 1(A) can be bent by bending the side portions 23s to 25s of the strain target 23 to 25 toward the rear surface as shown in Fig. 4(B), Fig. 5(B), and Fig. 6(B), for example, to change the section modulus of the strain target, i.e., the rigidity, and thereby increase the rigidity without changing the overall length of the strain target 23 to 25. In this case, there is also the advantage that the position to which an external force is applied remains the same even after deformation, and by appropriately deforming the strain target 23 to 25 as shown in Fig. 4(B), Fig. 5(B), and Fig. 6(B), measurements can be performed according to the measurement environment.

[0074] While the above example illustrates a method for uniformly deforming a single deformable body to change its rigidity and the distance from the measuring means to an external force, it is also possible to partially deform a single deformable body. For example, consider the example shown in FIG. 1B. The deformable body 21 in FIG. 1B has the same plate-like cross-sectional shape from the cantilever position 21p to the bent portion 21c and from the bent portion 21c to the tip 21f. The shape of the portion of the deformable body 21 from the cantilever position 21p to the bent portion 21c or from the bent portion 21c to the tip 21f can be changed by bending one or both of the Y-direction side surfaces, for example, into an L-shape, a U-shape, or a circular arc, thereby partially changing the rigidity. This allows for flexible adjustment of measurement characteristics, for example, when the measurement range or sensitivity needs to be changed depending on the measurement situation or conditions. Of course, it is also possible to make different shapes for the portion from cantilever position 21p to bent portion 21c of strain target body 21, and for the portion from bent portion 21c to tip 21f. In this case, by providing a slit in the Y direction in bent portion 21c in advance, it is possible to make it easier to change the cross-sectional shape.

[0075] As described above, the measurement range and sensitivity can be adjusted by changing the distance from the measuring means to the external force or the rigidity of the strained body, respectively, or by changing the distance and the rigidity in combination.

[0076] The above description has focused on cantilever-like configurations of the fixing of the strained body in the force sensor device, but other configurations will be described below. 7, a linear strain object 26 has both one end 26a and the other end 26b fixed to a fixing portion 42. A load application point (a point receiving an external force) where a concentrated load is applied is provided between the one end 26a and the other end 26b of the strain object 26 (the central portion 26c in the example of FIG. 7).

[0077] In this way, in the strain object 26 of the straight beam sensitive type force sensor device 16 shown in Figure 7, in which both ends (one end 26a, the other end 26b) are fixed, the bending moment M can be expressed as in equation (1), similar to the cantilever strain objects 21 to 25 shown in Figures 1(B), 3, and 4(B) to 6(B).

[0078] 7, taking into consideration that the load application point is at the central portion 26c, the bending moment M can be expressed as in the following equation (12): where l is the length of the strain target 26 (the distance between the fixed portions), and x' is the distance from one end 26a to the measuring means 30.

[0079]

number

[0080] Therefore, from equations (1) and (12), the external force W can be expressed by the following equation (13).

[0081]

number

[0082] As can be seen from equation (13), the relationship between the strain ε and the external force W can be changed by changing the section modulus Z. Therefore, by bending, folding, or changing the cross-sectional shape of the strained body 26 shown in FIG. 7 as shown in FIGS. 4(B) to 6(B), or by deforming and replacing it with the strained bodies 23 to 25, a force sensor device with adjustable measurement range and sensitivity can be created. In addition to cantilever beams and fixed-end beams, similar techniques can be applied to other structures, such as a double-supported beam in which both ends are supported without being fixed, or a curved beam in which the strained body is curved. Furthermore, a force sensor device with a membrane structure in which the periphery of a sheet-shaped strained body is fixed, a so-called diaphragm-type force sensor device, can also be used. Specifically, a circular, rectangular, or polygonal sheet-shaped strained body is fixed to fixing parts around the periphery of the strained body, and a load application part is provided between the fixing parts (e.g., the center) to serve as a load application point (a point receiving an external force).

[0083] Although the linear beam sensing type and diaphragm type force sensor devices are shown above as being formed with one strained body, it is also possible to use a configuration in which one or more strained bodies are arranged in the vertical direction.

[0084] Next, the direction of force that can be measured by the force sensor device will be described. Measuring forces in multiple directions can be achieved by attaching multiple measurement devices to the strained body with each device's sensitivity axis oriented differently. For example, when measuring external forces from only one direction, such as stress, the measurement device is attached with its sensitivity axis aligned with the direction of the force input. However, depending on the force sensor device, when measuring a load in one direction, the load direction may change depending on the device's shape and structure. Therefore, it is possible to use measurement devices calibrated with multiple gauges, such as a multi-axis measurement gauge, and attach it to the strained body in advance, allowing for different measurement devices to be used depending on the situation.

[0085] Furthermore, a single force sensor device can be configured to detect forces in up to six axial directions, including three translational directions (X, Y, and Z) and moments around each of these three axes. For example, Non-Patent Document 1 describes the structure of a strained body (strain element) inside a typical six-axis (three-directional force and moment) force sensor known as a cross-beam type. In the case of such a cross-beam type strained body, strain gauges are attached to the top, bottom, left, and right surfaces of the four beams as the basic structure to detect bending strain of the beams and convert it into force. Measuring loads in six axial directions using a force sensor device can be achieved, for example, by applying the basic structure of this cross-beam type strained body to the strained body of the force sensor device. In this case, the measurement range and sensitivity can be changed by further modifying the shape and cross-sectional structure of the beams (by changing their rigidity). In this way, various commonly known sensors can be used to configure a force sensor device.

[0086] Furthermore, since the strain generated in the strained body is proportional to the torque applied to the strained body, it is possible to measure the torque from the measured amount of deformation by attaching a measuring means in a direction tilted from the axis of the rod.When using a force sensor device, the relationship between the amount of deformation on the shaft surface and the torque applied to the shaft depends on the cross-sectional shape, so if the shape or cross-sectional structure of the strained body is changed and measurement is performed using the same method, it is possible to perform torque measurements with adjustable measurement range and sensitivity, and so it can also be used as a torque sensor.

[0087] Furthermore, the force sensor device can also measure acceleration by using, for example, an acceleration sensor 55 shown in FIG. 8. An acceleration sensor measures acceleration by connecting a deformable elastic body to a weight and detecting the vibration of the weight based on the deformation of the elastic body when acceleration is applied. Acceleration sensor 55 is configured using weight 56, a strained body 57 as an elastic body, and measurement means 30 for measuring the deformation of the weight. Acceleration can be measured by detecting the deformation of strained body 57 with measurement means 30. In this case, the measurement range and sensitivity when measuring acceleration can be changed by similarly changing the shape and cross-sectional structure of strained body 57 (by changing the rigidity). While a strain gauge is used as measurement means 30 in acceleration sensor 55, various sensors such as piezoelectric elements can be used as appropriate depending on the measurement conditions.

[0088] Next, a force measuring method using the force sensor device according to the embodiment of the present invention will be described. In this embodiment, a method of measurement will be described in which the strain target 20 of the force sensor device 10 shown in FIG. 1(A) is transformed into the strain target 21 of the force sensor device 11 shown in FIG. 1(B).

[0089] First, a force sensor device 10 is prepared as shown in Fig. 9(A). Next, a forming die 50 is prepared as shown in Fig. 9(B). The forming die 50 is pressed against the strained body 20 to deform it into a required shape according to each measurement condition, and is used to deform the strained body using forming dies of various shapes for each measurement condition when measuring with the force sensor device 10.

[0090] The forming mold 50 according to this embodiment includes a first surface 51 that deforms and shapes the tip 20f of the strained body 20, a second surface 52 that deforms and shapes the area from the X-direction position where the measuring means 30 is installed to the tip 20f, and a reference surface 53 that is brought into contact with the fixed portion 42 to position the longitudinal position of the forming mold 50 at the bending position 20m of the strained body 20. In this embodiment, the second surface 52 of the forming mold 50 has a protrusion 52p formed at a position in the X direction where the measuring means 30 is installed, and is gently inclined from the protrusion 52p toward the first surface 51 and the reference surface 53.

[0091] The forming die 50 thus formed is pressed against the strained body 20 to deform it, as shown in Fig. 9(B). In this way, the strained body 20 shown in Fig. 9(A) can be precisely formed into the shape of the forming die 50 to form the strained body 27, as shown in Fig. 9(C). Then, the measuring means 30 measures the strain under no load by measuring the amount of deformation of the strained body deformed by the protrusions 52p, in particular, before measurement by the force sensor device 17. In this way, even if the strained body has been deformed by a forming mold with a similar shape, it is possible to determine which forming mold caused the deformation, making calibration after changing the shape unnecessary.

[0092] By applying an external force to the force sensor device 17 having the deformed body 27, the amount of deformation is measured by the measuring means 30. By measuring with the force sensor device 17, the relationship between the amount of deformation of the body and the external force can be changed, so that the measurement range can be changed before and after the deformation, and the sensitivity can also be changed.

[0093] While the above describes a method for deforming and measuring the strained body of the force sensor device using a molding die 50 having protrusions 52p, the present invention is not limited to this method. For example, if a molding die without protrusions 52p is used, various molding dies corresponding to the shape of the strained body to be changed and assigned identification numbers such as ID numbers are prepared, calibration is performed for each molding die, and the results are acquired and managed. When such a molding die is used, calibration is not required after changing the shape of the strained body because the calibration results are acquired and managed in advance for each molding die. Alternatively, it is possible to deform the strained body into any shape or form depending on the measurement conditions, etc., using an appropriately selected method such as general molding without using a molding die, and then perform calibration before measurement.

[0094] When a shape-memory material is used for the strained body 20, the strained body 20 can be changed to a desired shape by heating and cooling it to a predetermined temperature, and then fixed in that shape or restored to its original shape. Specifically, as shown in FIG. 9(B), a forming die 50 is pressed against the strained body 20, heating the strained body 20 to a predetermined temperature and deforming it after or while heating. As a result, a strained body 27 formed according to the shape of the forming die 50 is obtained, as shown in FIG. 9(C), similar to the above. The strained body 27 is then cooled to a predetermined temperature, the shape of which is fixed, and the measurement means 30 measures the deformation of the strained body before measurement by the force sensor device 17, thereby obtaining the strain under no load. Even when a shape-memory material is used for the strained body, the same measures as those used for the case where a forming die without protrusions 52p or no forming die is used can be applied as appropriate.

[0095] Regarding the heating and cooling of the distortion body 20, in addition to the method of providing a temperature adjusting means in the distortion body 20, a method of providing a temperature adjusting means in the forming mold is also possible. Specifically, for example, the temperature of the forming mold can be adjusted and controlled by a temperature adjusting means provided in the forming mold, and the body to be deformed can be heated or cooled to deform or fix its shape.

[0096] This eliminates the need to provide a temperature control means for the strained body, making it possible to simplify or miniaturize the structure of the strained body. Furthermore, by making the structure of the strained body simple, it is possible to more flexibly respond to various measurement environments, conditions, etc. To speed up the heating and cooling times, the temperature adjustment means must be made larger, but by providing the temperature adjustment means in the forming mold, it is possible to prevent the size of the object to be deformed from increasing. Also, when using many force sensor devices, the temperature can be adjusted using only the forming mold, which is a jig, so costs can be kept down even when using many force sensor devices.

[0097] If the temperature control means is built into the strained body, then if the temperature control means breaks down, for example, it may become necessary to replace the entire strained body, but this situation can be avoided. Also, if the temperature control means is built into the strained body, it is possible to omit the need to consider and design the deformation form of the strained body including this temperature control means, the load characteristics at that time, and other mechanical characteristics. When the temperature adjusting means is located on the molded body side in this way, the structure of the strained body can be simplified, and various handling of the force sensor device is easy.

[0098] Furthermore, in temperature control of the forming mold, for example, if deformation of only a portion of the object to be deformed is required, the temperature of each portion of the forming mold may be set to be controllable. This allows measurements by the force sensor device to be more suited to the measurement conditions, etc.

[0099] In addition to the above-described method of deforming the strained body 20 using the forming mold 50, it is also possible to deform the strained body by automatically operating the forming mold, so-called automation. As an example, Fig. 10(A) shows an automatic forming device 60 that deforms the strained body 20 of the force sensor device 10 shown in Fig. 1(A) into the strained body 21 of the force sensor device 11 shown in Fig. 1(B). Figure 10(A) shows a state in which the bottom surface of the strained body 20 of the force sensor device 10 shown in Figure 1(A) (the surface opposite to the surface of the strained body 20 on which the measuring means 30 is attached) is abutted against the automatic molding device 60.

[0100] The automatic molding device 60 includes a mold body 61 which is a molding die, a drive unit 62, a temperature control unit 63, and a clamping unit 64. The mold body 61 sandwiches the object to be deformed 20 together with the clamping part 64 and is divided at the bending position. In this embodiment, since the tip of the object to be deformed 20 is bent in the Z direction, the mold body 61 is composed of two parts, a first mold body 61a and a second mold body 61b. The driving unit 62 is disposed at the bending position, and drives and moves the bending portion of the mold body 61. In this embodiment, the driving unit 62 is provided at the tip of the first mold body 61a, opposite the side where the cantilever position 20p of the strain target 20 is disposed, and is connected so as to move the second mold body 61b, which is the portion to be bent. The driving unit 62 may be provided on either the first mold body 61a or the second mold body 61b.

[0101] The temperature control unit 63 is arranged along the mold body 61. The temperature control unit 63 can return the shape of the object to be deformed 20 to its original state by heating or cooling the mold body 61. In this case, since the temperature control unit 63 is arranged on the mold body 61, there is no need to provide the object to be deformed 20 with, for example, a temperature control heater H as shown in FIG. 2. It goes without saying that, in order to deal with deformation of the object to be deformed 20, a temperature control means can be arranged on the object to be deformed 20 without providing the temperature control unit 63. The clamping portion 64 is provided opposite to the mold body 61. The clamping portion 64, together with the mold body 61, clamps the object to be deformed 20, thereby setting the object to be deformed into a predetermined bent shape and preventing the object to be deformed 20 from moving when the object to be deformed is bent by the driving portion 62.

[0102] In the above example, the mold body 61 is shown as corresponding to the bending of the force sensor device 11 onto the strained body 21, but for example, to correspond to the shape shown in Fig. 4(B), a forming mold having a U-shaped mold body whose side surfaces are movable and bendable can be used. Specifically, a flat strained body is brought into contact with the forming mold while being pressed by the clamping parts, and its side surfaces are temporarily bent, after which the side surfaces of the forming mold are further movable to fold the side surfaces of the strained body. 5 and 6, a clamping portion with a larger thickness in the pressing direction (Z direction) is used for Fig. 5(B), and a mold and clamping portion with a cylindrical shape are used for Fig. 6(B), and it is possible to carry out the same method as in Fig. 4. It goes without saying that when dealing with the shapes of Figs. 5 and 6, appropriate measures can be taken, if necessary, to avoid interference with the measuring means, such as providing an opening in the mold at a location where the measuring means may interfere.

[0103] In this way, an automatic molding device having a mold that deforms the deformable body into a shape corresponding to the measurement conditions, etc., a drive unit that drives the mold to deform the deformable body, and a clamping unit that holds the deformable body can automatically deform the deformable body into any shape depending on the shape of the mold (see Figure 10(B)). Furthermore, if the deformable body is a shape-memory material, providing a temperature control unit in the automatic molding device makes it possible to automatically heat and deform the deformable body, and then fix it into that shape or return it to its original shape by cooling, without providing a temperature control means for the deformable body.

[0104] The main components of the force sensor device have been described above, but the force sensor device can be equipped with various functions depending on the measurement target, conditions, etc. Although not shown in the figure, an example will be described below. The force sensor device can be equipped with a processing means that calculates and processes the measurement results obtained by the measurement means, an evaluation means that evaluates the suitability of the set measurement range and sensitivity and the need for changes based on the measurement results, or a control support means that supports the operation of various application examples described below. The processing means calculates and outputs a load based on the deformation amount of the strained body measured by the measurement means.

[0105] The evaluation means sets evaluation values ​​such as thresholds for the effectiveness of the measurement range or sensitivity set in advance based on the measurement environment, conditions, etc., and compares them with the obtained measurement results to determine the appropriateness of the measurement results for the set measurement range and sensitivity, outputting the result if they are appropriate. Also, if the measurement data is insufficient, such as if the measurement results exceed the set measurement range or sensitivity, or if the measurement results differ from the initially expected measurement results in relation to the measurement range or sensitivity and require readjustment, it outputs a message indicating that the measurement range or sensitivity needs to be changed. The evaluation means may be configured to include input means for setting thresholds or the above-mentioned processing means.

[0106] The control assistance means is provided with an analysis unit that analyzes the optimal measurement range or sensitivity based on the measurement results and the measurement object and conditions, and changes or adds the measurement range or sensitivity based on the analysis results. Furthermore, this control assistance means is connected to the control units of various devices equipped with the force sensor device, and controls the operating range of those devices based on the changed or added measurement range or sensitivity. Note that the control assistance means may be configured in combination as a function of the evaluation means or processing means described above.

[0107] By providing such various means, the force sensor device can be made to exhibit the function of changing the measurement range and sensitivity.

[0108] The force sensor device according to the embodiment of the present invention can be applied to a variety of different forms, such as an instrument that measures vibration or load based on the amount of deformation, a force sensor, a tactile sensor, etc. Major application examples will now be described.

[0109] <Load cell> 11(A) and 11(B) show a load cell as an example of application of a force sensor device according to an embodiment of the present invention. In the following description, the rod side of the load cell will be referred to as the front and the opposite side as the rear. The load cell 100 includes a base 110, a main body 120, a rod 130, a strain target 140, and a measuring means 30. Note that wiring and the like from the measuring means 30 are not shown.

[0110] The base 110 is formed from a rectangular metal plate. The main body 120 is provided on the base 110. The main body 120 includes a fixed portion 121, a front wall portion 122, and a movable portion 123.

[0111] The fixed part 121 includes a side wall part 121a erected on the base 110 and a block-shaped base part 121b fixed to the rear part of the side wall part 121a. The front wall part 122 is fixed to the side wall part 121a and is formed so as to extend from the front part of the side wall part 121a toward the opposite side part. The movable part 123 is formed in a rectangular plate shape and is disposed between the front wall part 122 and the base part 121b. The rod part 130 passes through and is fixed to the movable part 123, and is connected to the rod part 130 so as to move together with the rod part 130. The rod part 130 is formed in a rod shape. The rod part 130 passes through the front wall part 122 so as to be able to move freely. The base end of the rod part 130 is supported by the base part 121b. Object 140 is formed from an H-shaped plate member and is arranged at two locations, one on the top side and one on the bottom side of movable part 123 and fixed part 121, so as to be able to deform freely and straddle movable part 123 and fixed part 121. One end of object 140 is attached to movable part 123 by means of mounting plate 124 which is screwed, and the other end is attached to base part 121b of fixed part 121 by means of mounting plate 125 which is also screwed. Measuring means 30 is arranged on object 140.

[0112] With the load cell 100 thus configured, an external force (vertical direction in FIG. 11(B)) applied to the rod portion 130 moves the movable portion 123 together with the rod portion 130, and one end of the strained body 140 connected to the movable portion 123 moves together with the movable portion 123. This movement causes deformation of the strained body 140 at two locations, on the top and bottom sides of the movable portion 123 and the fixed portion 121, and the amount of deformation at this time can be measured by the measuring means 30.

[0113] Furthermore, by changing the shape of the part of the strained body 140 of this load cell 100 that straddles the movable part 123 and the fixed part 121 to various shapes, such as the shape of the strained body 23 shown in FIG. 4(B), the shape of the strained body 24 shown in FIG. 5(B), or the shape of the strained body 25 shown in FIG. 6(B), the load measurement range or sensitivity can be adjusted.

[0114] Normally, when measurements are made over a wide range of measurement ranges and sensitivities, multiple types of load cells with different measurement specifications such as measurement range and sensitivity are prepared, and measurements are made using the load cell that corresponds to the range or magnitude of the load to be measured. However, with this load cell 100, the measurement range or sensitivity of the load can be adjusted by changing the shape of the strained body 140, so a single load cell 100 can be used.

[0115] In addition, as another embodiment of a load cell to which the force sensor device according to the present invention is applied, a load cell having a mechanism in which a plurality of different shapes of deformable bodies that satisfy the measurement range and sensitivity are prepared and installed inside the load cell 100, and measurement can be performed by switching among the plurality of deformable bodies to one that corresponds to the measurement conditions, or instead of using load cells with different measurement specifications as described above, it is possible to use a plurality of load cells in which the deformable body is changed to a variety of shapes, thereby enabling measurements to be performed efficiently and at low cost.

[0116] In the above example, a load is applied to the strained body 140 via the rod-shaped rod portion 130 and detected. However, the load cell to which the force sensor device is applied is not limited to this configuration, and other strained bodies such as cantilever beam, double-end supported or fixed type, and diaphragm type may also be used. As an example, when a cantilever beam type strained body is used, the movable portion 123 is omitted from the load cell 100, and a strained body in which the rod portion 130 and the strained body 140 are integrated (for example, the shape of the strained body shown in FIG. 1(B)) is used, and a load is applied directly to this strained body. In this case, the shape of the strained body is not limited to a rod shape, and various shapes such as the plate shape shown in FIG. 1 may be used.

[0117] When a both-end supported or both-end fixed type strained body is used, an example of a load cell is one that uses a linear strained body 26 in which both ends are supported or fixed and a load application point (a point receiving an external force) where a load is applied in a concentrated manner is provided between both ends of the strained body 26, as shown in Figure 7. The shape of the strained body 26 in this case can also be selected appropriately, such as a rod shape or a plate shape. Also, when a diaphragm-type strained body is used, an example of a load cell is one in which the ends are fixed to a membrane-shaped strained body and a load application point is provided at the membrane part. Various other shapes can be set for each type of strained body depending on the measurement conditions, etc.

[0118] <Robot Hand> As another embodiment, an example in which the force sensor device according to the embodiment of the present invention is applied to a gripping portion of a robot hand is shown in FIG. The robot hand 200 shown in Figure 12 is a serial link type robot in which an arm section 210 is mounted on a swivel base 220 and a gripping device 230 that serves as the gripping section of the robot hand 200 is provided at the tip of the arm section 210.

[0119] In the arm unit 210, a lower arm unit 211 and a swivel base 220 are connected by a first joint 212, and the lower arm unit 211 and an upper arm unit 213 are connected by a second joint 214. The upper arm unit 213 is connected to a gripping device 230 by a wrist unit 215 that rotates the gripping device 230. The gripping device 230 is provided with a first finger portion 231 and a second finger portion 232 as gripping portions for various objects, and the gripping portions are arranged facing each other, and the base ends of the first finger portion 231 and the second finger portion 232 are connected by a joint 233 so that they can be opened and closed freely.

[0120] Force sensor devices 234 are provided at the tips of first finger portion 231 and second finger portion 232. Ends of the strained body are fixed to force sensor device 234, and protrusions 234a (the center in the example of FIG. 12) and a measuring means for measuring the deformation amount of the strained body are provided between the ends, and object T is gripped between these protrusions 234a. At this time, the gripping force of first finger portion 231 and second finger portion 232 is adjusted by joint 233 based on information from force sensor device 234. By configuring the robot hand 200 in this way, the gripping force applied to the object T by the gripping device 230 can be appropriately controlled based on information from the force sensor device 234.

[0121] Furthermore, the gripping device 230 is provided with a force sensor device 234, which allows the shape of the object to be deformed to be changed and the measurement range or sensitivity to be adjusted while taking into account the measurement conditions and the object to be gripped, thereby enabling a more optimal gripping force to be set.

[0122] In the force sensor device 234 of this example, various types of shapes can be used to fix the ends of the deformed body, such as a double-supported type, a double-fixed type, or a diaphragm type, and in the case of the double-supported type or double-fixed type, the shape of the deformed body can be selected appropriately from a plate, rod, strip, etc.

[0123] The strained body of the force sensor device 234 may also be a cantilever type in which only one side is fixed. In this case, as an example, a fixing portion for fixing the strained body is provided in the force sensor device, and a beam-shaped strained body 20 as shown in Fig. 1(A) is attached to the fixing portion, and a protrusion is further provided on this strained body to allow the object T to come into contact with it. Note that this protrusion may have various shapes, and may, for example, be in the form of a strained body 21 formed by bending the strained body as shown in Fig. 1(B).

[0124] In this example, the gripping unit (gripping device 230) is composed of two parts, first finger portion 231 and second finger portion 232, but it may be formed with multiple fingers. In this case, force sensor devices can be provided on all fingers or only on specific fingers depending on the purpose. In particular, when force sensor devices are provided on all fingers, the gripping force can be adjusted taking into account the three-dimensional shape of the object, which is useful for objects that require careful consideration of the amount of force used when touching, such as food, agricultural products such as fruit, or people. Furthermore, by changing the shape of the object to be deformed and adjusting the measurement range or sensitivity, a gripping unit incorporating a force sensor device can obtain a more accurate gripping force depending on the shape of the gripping unit and the object being gripped.

[0125] <Robot arm> As another embodiment, a robot arm to which a force sensor device according to an embodiment of the present invention is applied will be described. In this example, a force sensor device is provided on the arm of a robot arm.

[0126] As shown in FIG. 13(A), the robot arm 300 includes a shoulder 310 connected to a fixed part, a shoulder joint 320 connected to the shoulder 310, an upper arm 330 extending from the shoulder joint 320, an elbow joint 340 connected to the upper arm 330, and a forearm 350 extending from the elbow joint 340. In this form, the upper arm 330, elbow joint 340, and forearm 350 form the arm of the robot arm, and the upper arm 330 and forearm 350 of this arm are wrapped around or covered with, for example, a sheet-like tactile sensor 360 having a force sensor device. Here, the tactile sensor 360 will be described in detail with reference to FIG. 13(B).

[0127] As shown in FIG. 13(B), the tactile sensor 360 is constructed by first arranging a number of force sensor devices 362 in a matrix on a plate-like member 361, and attaching a grid-like electrode 364 to which wiring 363 is connected to the plate-like member 361 on which the force sensor devices 362 are arranged. Although not shown, the force sensor device 362 has a strained body and a measuring means, and the tactile sensor 360 has a control means for controlling the load applied to the object by the robot arm 300 based on the load measured by the force sensor device 362.

[0128] When an object is lifted by the arm of the robot arm 300, or when the arm moves, such as by moving the arm up and down, left and right, or otherwise holding an object, the tactile sensor 360 measures the load applied to the object with the force sensor device, and the robot arm 300 controls the position and posture based on this acquired measurement data.

[0129] The force sensor device 362 can be of various types, such as a cantilever type as shown in FIG. 1, a double-supported type, a double-fixed type, or a diaphragm type. In the double-supported type or double-fixed type, the shape of the body to be deformed can be selected appropriately from a plate, a rod, a strip, or the like.

[0130] Since the tactile sensor 360 has a force sensor device 362 and is formed in a sheet shape, it can be easily wrapped around or placed over the surrounding surface of the arm, such as the upper arm 330 or the forearm 350, and can be easily attached to the robot arm 300.

[0131] Furthermore, when a shape-memory material is used for the strained body of the force sensor device 362, it becomes possible to deform the force sensor device 362 and attach it while fitting it to the shape of the arm of the robot arm 300, thereby improving the ease of attachment. Furthermore, in this case, by adjusting the temperature of the strained body, it becomes possible to flexibly adjust the measurement range and sensitivity required for the measurement environment and conditions, making it possible to perform measurement work efficiently and making the tactile sensor 360 more adaptable and versatile to the measurement environment and conditions.

[0132] FIG. 13 shows a configuration in which the tactile sensor 360 is provided on the upper arm 330 and the forearm 350, but this configuration is not limiting. The tactile sensor 360 may be provided on either the upper arm 330 or the forearm 350 depending on the form and shape of the object, the measurement environment, conditions, etc. Furthermore, a sensor assembly including a force sensor device, such as the tactile sensor 360 of this example, may be formed to be attachable and detachable. In this case, it can be used with a robot arm that requires measurement, and the efficiency of the measurement work can be improved. Furthermore, by using a shape-memory material for the strained body, the measurement range and sensitivity can be flexibly adjusted, thereby enabling more efficient measurement.

[0133] It goes without saying that the above-mentioned tactile sensor 360 can be attached and detached to the robot hand described above. Specifically, a force sensor device 234 provided to the gripping device 230 of the robot hand that is formed to be attachable and detachable can be exemplified.

[0134] The plate-like member 361 of the tactile sensor 360 in Fig. 13 can be made of a metal material or a non-metal material such as rubber or resin. Taking into consideration the impact absorption upon contact with an object, the improvement of the spatial resolution of the tactile sensor, and the ease of attachment to a robot arm (fit, etc.), soft materials such as rubber or soft resin are preferable. Also, while Fig. 13 shows a force sensor device incorporated as a tactile sensor, it is also possible to provide a force sensor device on its own.

[0135] Although the example in which the force sensor device is applied to a robot arm has been shown, it can also be applied to, for example, a lifting device or other elevating device that lifts, holds, or transports an object. Specifically, one example is a configuration in which the force sensor device is provided on a loading section of an elevating device that places an object on and raises or lowers it, and the load on the object is monitored and controlled.

[0136] By disposing the force sensor device 362 on a robot arm or the like in this way, it is possible to precisely control, for example, the movement of the arm (upper arm 330, forearm 350) or the load-bearing part based on information from the force sensor device 362. As a result, for example, if the robot arm 300 is applied to the arm of a nursing care robot, the measurement range and sensitivity can be adjusted, making it suitable for lifting and holding with an optimal force for the caregiver. Also, with regard to the lifting device, it becomes possible to lift an object while adjusting the load according to the shape and situation of the object. [Industrial Applicability]

[0137] The present invention is suitable for force sensors and tactile sensors used in production equipment in various factories, measuring devices in research facilities, load cells, robot hands, robot arms, etc., because it can measure external forces. [Explanation of symbols]

[0138] 10,11,12,16,17 Force sensor device 20,21,22,23,24,25,26,27 Distorted object 20b Base end 20f tip 20m bending position 20p, 21p, 22p Cantilever position 21c Bend part 21e Tip 22f Tip 23s, 24s, 25s Side 24c,25c Cavity 26a One end 26b Other end 26c central part 30 Measurement means 41 Base 42 Fixed part 50 mold 51 Page 1 52 2nd page 52p protrusion 53 Reference plane 55 Acceleration sensor 56 Weight 57 Distorted object 60 Automatic molding equipment 61-inch main body 61a Type 1 main body 61b Type 2 main body 62 Drive unit 63 Temperature control section 64 Clamping part 100 load cells 110 Foundation 120 Main body 121 Fixed part 121a Side wall part 121b base part 122 Front wall 123 Moving parts 124,125 Mounting plate 130 Rod section 200 Robot Hand 210 Arm 211 Lower arm 212 First joint 213 Upper Arm 214 Second joint 215 Wrist part 220 Swivel 230 Gripping device 231 1st finger part 232 2nd finger 233 Joint 234 Force Sensor Device 300 Robot Arm 310 Shoulder 320 Shoulder joint 330 Upper Arm 340 Elbow joint 350 forearm 360 Tactile Sensor 361 Plate-like members 362 Force Sensor Device 363 Wiring 364 electrode H Temperature control heater W,W1,W2,W3 external force T object

Claims

1. A strained body that is strained by an external force and a measuring means for measuring the amount of deformation of the strained body are provided, The strained body is deformable and maintains a deformed state; The strained body is formed in a cantilever shape, folded back one or more times to the cantilever position, and fixed in place in the force sensor device.

2. A strained body that is strained by an external force and a measuring means for measuring the amount of deformation of the strained body are provided, The strained body is deformable and maintains a deformed state; The strained body is a force sensor device in which the sides in the width direction perpendicular to the length direction are bent to form a plate shape.

3. A strained body that is strained by an external force and a measuring means for measuring the amount of deformation of the strained body are provided, The strained body is deformable and maintains a deformed state; The strained body is a force sensor device in which the side portions in the width direction perpendicular to the length direction are bent to form a cylindrical shape.

4. 4. The force sensor device according to claim 1, wherein the body to be deformed is made of a shape memory material.

5. 5. The force sensor device according to claim 4, wherein the shape memory material is formed of a shape memory polymer.

6. 6. A force sensor device according to claim 4, wherein the strained body is provided with a temperature adjusting means for changing and fixing the shape of the strained body.

7. 7. The force sensor device according to claim 1, wherein the strain object is formed in a plate shape.

8. 2. The force sensor device according to claim 1, wherein the strained body is formed in a rod shape.

9. 8. The force sensor device according to claim 2, wherein the mounting form of the strained body is set to any one of a cantilever type, a both-end supported type, a both-end fixed type, and a diaphragm type.

10. When measuring the deformation amount of a strained body by a force sensor device having a strained body that is distorted by an external force and a measuring means for measuring the deformation amount of the strained body, deforming the strained body; applying an external force to the deformed body; measuring the deformation amount of the strained body by the measuring means; a step of deforming the strained body using a forming die before deforming the strained body; a step of deforming the object using the forming die in a range including a longitudinal position where the measuring means is installed; A force measuring method comprising a step of measuring, in advance by the measuring means, the amount of deformation of the object to be deformed by the forming die, prior to the actual measurement.

11. 11. The force measuring method according to claim 10, wherein the object to be deformed is made of a shape memory material.

12. The force measuring method of claim 11 , wherein the shape memory material is formed of a shape memory polymer.

13. 13. A force measuring method according to claim 11, wherein a temperature adjusting means for changing and fixing the shape of the deformable body is provided on either the deformable body or the forming die, and the deformable body is deformed by adjusting the temperature.

14. A load cell having a rod portion to which an external force is applied, a movable portion that moves together with the rod portion, and a fixed portion, and a force sensor device provided between the movable portion and the fixed portion, The force sensor device A strained body that is strained by an external force and a measuring means for measuring the amount of deformation of the strained body are provided, The strained body is deformable and maintains its deformed state. Load cell.

15. A load cell having a rod portion to which an external force is applied, a movable portion that moves together with the rod portion, and a fixed portion, and a force sensor device described in any one of claims 1 to 9 is provided between the movable portion and the fixed portion.

16. A robot hand having an arm and a gripping portion for gripping an object on the arm, the gripping portion being provided with the force sensor device according to any one of claims 1 to 9.

17. The robot hand according to claim 16, wherein the force sensor device is detachably provided.

18. A robot arm having a shoulder and an arm extending from the shoulder, the arm being provided with the force sensor device according to any one of claims 1 to 9.

19. 19. The robot arm according to claim 18, wherein a sensor assembly having the force sensor device is provided in a detachable manner.

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