Sensor Device

Abstract

To reduce influence of a temperature under a detection environment and detect a proper state amount.SOLUTION: A sensor device 60 for detecting a predetermined state amount includes a correction unit 61 for performing a first detection and a second detection in which a state amount to be generated is less than the first detection, and for correcting a detected value of the first detection on the basis of a detected value of the second detection. Since the detected value of the second detection with a smaller state amount has less influence on an environmental temperature, the correction unit 61 corrects the detected value acquired in the first detection on the basis of the detected value acquired in the second detection, and makes the state amount proper, for example.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sensor device.

Background Art

[0002] As a sensor device for detecting a state quantity of a target device, for example, there is a device that uses a strain gauge to detect the strain of an internal gear of a flexure engagement type gear device (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, conventionally, there has been room for improvement in countermeasures against disturbances.

[0005] An object of the present invention is to reduce the influence of disturbances and perform appropriate detection of state quantities.

Means for Solving the Problems

[0006] The present invention is a sensor device for detecting a predetermined state quantity, which performs a first detection and a second detection in which the state quantity generated is smaller than the first detection, and has a correction unit that corrects the detection value of the first detection based on the detection value of the second detection.

Effects of the Invention

[0007] According to the present invention, it is possible to reduce the influence of disturbances and perform appropriate detection of state quantities.

Brief Description of the Drawings

[0008] [Figure 1] This is an axial cross-sectional view showing a flexible meshing gear device to which the sensor device according to Embodiment 1 of the present invention is applied. [Figure 2] This is a perspective view of the first internal tooth member. [Figure 3] Figure 3(A) shows the circuit diagram of a Wheatstone bridge circuit incorporating two off-diagonal strain gauges, and Figure 3(B) shows its equivalent circuit diagram. [Figure 4] This is a front view showing the first internal tooth member of a flexible meshing gear device to which the sensor device according to Embodiment 2 is applied. [Figure 5] This is a perspective view showing another example of the first internal tooth member of a flexible meshing gear mechanism to which the sensor device according to Embodiment 3 is applied. [Figure 6] Figure 5 is an axial cross-sectional view of the first internal tooth member. [Figure 7] This is a front view showing the first internal tooth member of a flexible meshing gear mechanism to which the sensor device according to Embodiment 4 is applied. [Figure 8] This is a front view of the first internal tooth member of a flexible meshing gear mechanism to which the sensor device according to Embodiment 5 is applied. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0010] [Embodiment 1] In this embodiment 1, a sensor device 60 (see Figure 2) is provided as an example, which uses a strain gauge 416 (detection unit) to detect the strain (state quantity) of a flexible mesh gear device 1 (rotating device) as the target device for detecting the state quantity. The strain detected by the sensor device 60 is used for torque detection of the flexible mesh gear device 1.

[0011] [Flexible meshing gear system] Figure 1 is an axial cross-sectional view showing a flexible meshing gear device 1 to which the sensor device 60 according to Embodiment 1 of the present invention is applied. In the following description, the direction parallel to the rotation axis O1 to be described later is referred to as the axial direction, the direction along the circumference centered on the rotation axis O1 is referred to as the circumferential direction, and the direction along the radius of the circumference centered on the rotation axis O1 is referred to as the radial direction.

[0012] The flexible meshing type gear device 1 is, for example, a speed reduction device. The use of the flexible meshing type gear device 1 is not particularly limited and can be applied to various uses. For example, it is used to drive the joints of a collaborative robot that works in cooperation with a human. This flexible meshing type gear device 1 includes an oscillator shaft 30, an oscillator bearing 31, a first external tooth part 32 (external gear), a second external tooth part 33 (external gear), a first internal tooth part 411, a second internal tooth part 421, a casing 43, a first cover 44, a second cover 45, a third cover 49, bearings 46, 47, a main bearing 48, and stopper rings 51, 52.

[0013] The oscillator shaft 30 is a hollow cylindrical shaft that rotates around the rotation axis O1, and has an oscillator 30A whose outer shape in a cross section perpendicular to the rotation axis O1 (axial perpendicular cross section) is non-circular (for example, elliptical), and shaft parts 30B, 30C provided on both axial sides of the oscillator 30A. The elliptical shape does not need to be a geometrically exact ellipse and includes a substantially elliptical shape. The shaft parts 30B, 30C are shafts whose outer shape in a cross section perpendicular to the rotation axis O1 is circular. Note that the oscillator shaft 30 may be a solid shaft.

[0014] The first internal tooth part 411 is configured by providing teeth on a part of the inner circumference of a first internal tooth member 41 as a rigid internal gear. The second internal tooth part 421 is configured by providing teeth on a part of the inner circumference of a second internal tooth member 42 having rigidity.

[0015] The first external tooth part 32 and the second external tooth part 33 are integrally provided side by side in one axial direction and the other axial direction on the outer circumference of a single flexible metal cylindrical base 34. These first external tooth part 32, second external tooth part 33, and base 34 constitute an external gear. And the first external tooth part 32 meshes with the first internal tooth part 411, and the second external tooth part 33 meshes with the second internal tooth part 421.

[0016] The oscillation body bearing 31 is, for example, a roller bearing and is disposed between the oscillation body 30A and a base portion 34 formed with a first outer tooth portion 32 and a second outer tooth portion 33. The oscillation body 30A, the first outer tooth portion 32, and the second outer tooth portion 33 are relatively rotatable via the oscillation body bearing 31. The oscillation body bearing 31 has an outer ring 31a fitted inside the base portion 34, a plurality of rolling elements (rollers) 31b, and a cage 31c that holds the plurality of rolling elements 31b. The plurality of rolling elements 31b include a first group of rolling elements 31b arranged radially inward of the first outer tooth portion 32 and the first inner tooth portion 411 and aligned in the circumferential direction, and a second group of rolling elements 31b arranged radially inward of the second outer tooth portion 33 and the second inner tooth portion 421 and aligned in the circumferential direction. These rolling elements 31b roll with the outer peripheral surface of the oscillation body 30A and the inner peripheral surface of the outer ring 31a as rolling surfaces. The oscillation body bearing 31 may have an inner ring separate from the oscillation body 30A. Also, the oscillation body bearing 31 may eliminate the outer ring 31a and use the inner peripheral surface of the base portion 34 as the outer ring side rolling surface. The type of the rolling elements is not particularly limited and may be, for example, balls. Also, the number of rows of the rolling elements is not limited to two and may be one row or three or more rows

[0017] The stopper rings 51 and 52 are disposed on both axial sides of the first outer tooth portion 32 and the second outer tooth portion 33 and the oscillation body bearing 31, and regulate the axial movement of the first outer tooth portion 32 and the second outer tooth portion 33 and the oscillation body bearing 31.

[0018] The casing 43 covers the outer peripheral side of the second inner tooth member 42. An outer ring portion of the main bearing 48 is formed on the inner peripheral portion of the casing 43, and the second inner tooth member 42 is rotatably supported via the main bearing 48. The casing 43 is connected to the first inner tooth member 41 via a connecting member such as a bolt, for example.

[0019] The main bearing 48 is, for example, a cross roller bearing and has a plurality of rolling elements arranged between an inner ring portion integrated with the second internal tooth member 42 and an outer ring portion integrated with the casing 43. The type of the main bearing 48 is not particularly limited, and for example, it may be composed of a plurality of bearings (angular contact ball bearings, tapered bearings, etc.) spaced apart in the axial direction between the second internal tooth member 42 and the casing 43, or it may be a four-point contact ball bearing. Furthermore, the main bearing 48 may have a dedicated inner ring and outer ring separate from the second internal tooth member 42 and the casing 43. Furthermore, an oil seal 541 is provided between the casing 43 and the second internal gear member 42, on the output side of the main bearing 48, to suppress the outflow of lubricant axially outward (output side).

[0020] The first cover 44 is connected to the third cover 49 via connecting members such as bolts (not shown), and the third cover 49 is further connected to the first internal tooth member 41 and the casing 43 via connecting members such as bolts (not shown). The first cover 44 covers the first external tooth portion 32 and the first internal tooth portion 411 from the axial non-output side. The first cover 44, the third cover 49, the first internal tooth member 41, and the casing 43 are connected directly or indirectly to an external member (for example, the base end arm member of a collaborative robot).

[0021] The side that outputs reduced motion to an external member (also called a mating member; for example, one of the members of a main body device into which a flexible meshing gear device 1 is incorporated as a component) is called the output side, and the side opposite to the output side in the axial direction is called the non-output side. A bearing 46 is positioned between the first cover 44 and the shaft portion 30B of the vibrator shaft 30, and the vibrator shaft 30 is rotatably supported by the first cover 44. Although a ball bearing is shown as an example for the bearing 46, other radial bearings may also be used. Furthermore, an oil seal 542 is provided between the first cover 44 and the shaft portion 30B of the vibrator shaft 30, on the side opposite to the output side of the bearing 46, to suppress the outflow of lubricant axially outward (on the side opposite to the output side).

[0022] The second cover 45 is connected to the second internal tooth member 42 via a connecting member 533, such as a bolt, and covers the second external tooth portion 33 and the second internal tooth portion 421 from the axial output side. The second cover 45 and the second internal tooth member 42 are connected to an external member that outputs reduced motion (for example, the end-effector arm member of a collaborative robot) (this external member rotates relative to the external member to which the first internal tooth member 41, etc., is connected). A bearing 47 is positioned between the second cover 45 and the shaft portion 30C of the vibrator shaft 30, and the vibrator shaft 30 is rotatably supported by the second cover 45. Although a ball bearing is shown as an example for bearing 47, other radial bearings may also be used. Furthermore, an oil seal 543 is provided between the second cover 45 and the shaft portion 30C of the vibrator shaft 30, on the output side of the bearing 47, to suppress the outflow of lubricant axially outward (output side). The second cover 45 may be formed integrally with the second internal tooth member 42.

[0023] Furthermore, an O-ring 551 for sealing is interposed between the first internal tooth member 41 and the casing 43. Similarly, an O-ring 554 for sealing is interposed between the first internal tooth member 41 and the third cover 49, an O-ring 552 for sealing is interposed between the third cover 49 and the first cover 44, and an O-ring 553 for sealing is interposed between the second internal tooth member 42 and the second cover 45. Therefore, the internal space of the flexible meshing gear device 1 (the space where the first external teeth 32 and the first internal teeth 411 mesh, the second external teeth 33 and the second internal teeth 421, the main bearing 48, bearings 46, 47, the vibrator bearing 31, etc. are located) is a lubricant-filled space into which lubricant is sealed, and is sealed by oil seals 541-543 and O-rings 551-554.

[0024] Figure 2 is a perspective view of the first internal tooth member 41. As shown in the figure, the first internal tooth member 41 comprises an internal tooth ring portion 412 on which the internal teeth of the first internal tooth portion 411 are formed on its inner circumference, an external connecting portion 413 which is connected to the external member together with the casing 43 and the third cover 49, and a deformable portion 414 provided between the internal tooth ring portion 412 and the external connecting portion 413 in the radial direction, which is configured to deform more easily (deform more) than the internal tooth ring portion 412 when torque is applied to the first internal tooth member 41.

[0025] The internal tooth ring portion 412 is ring-shaped, and the aforementioned first internal tooth portion 411 (internal tooth) is formed on its inner circumferential surface. The external connecting portion 413 is ring-shaped and located on the outermost circumference of the first internal tooth member 41, with multiple mounting holes for the external member formed axially through it at regular intervals in the circumferential direction. The external connecting portion 413 may be directly connected to the external member, or it may be connected to the external member via the first cover 44 or the third cover 49.

[0026] The easily deformable portion 414 is composed of a plurality of columnar members 415 intermittently provided in the circumferential direction between the internal tooth ring portion 412 and the external connecting portion 413. The column member 415 extends radially outward from the outer circumference of the internal tooth ring portion 412 and is connected to the inner circumference of the external connecting portion 413. Here, we illustrate the case in which the easily deformable portion 414, the internal tooth ring portion 412, and the external connecting portion 413 are integrally formed from the same material (for example, metal material, resin material, etc.). Furthermore, an example is given where four column members 415 are provided at regular intervals in the circumferential direction. In other words, column members 415 are arranged at each end of the two mutually orthogonal diametrical directions of the first internal tooth member 41. While it is preferable for the circumferential spacing of each column member 415 to be uniform, it is not mandatory. Furthermore, the number of column members 415 can be increased or decreased.

[0027] The external connecting portion 413 and the column member 415 have equal axial width (thickness), and the axial width is smaller than that of the internal tooth ring portion 412. The column member 415 may have a different axial width from the external connecting portion 413; for example, if sufficient strength is provided to ensure torque transmission functionality, the axial width may be smaller than that of the external connecting portion 413. The column member 415 may also have a recess for housing the strain gauge 416. Furthermore, on the radially inner surface of the external connecting portion 413, a convex ridge 413a is formed along the entire circumference, extending toward the output side, and is fitted (spigot fitting) into the recess on the opposite output side of the casing 43.

[0028] [Deceleration operation] When rotational motion is input from a motor (not shown) or the like, and the exciter shaft 30 rotates, the motion of the exciter 30A is transmitted to the first external teeth 32 and the second external teeth 33. At this time, the first external teeth 32 and the second external teeth 33 are restricted to a shape along the outer circumferential surface of the exciter 30A, and when viewed from the axial direction, they are deflected into an elliptical shape having a long axis portion and a short axis portion. Furthermore, the first external teeth 32 meshes with the first internal teeth 411 of the fixed first internal teeth member 41 at its long axis portion. For this reason, the first external teeth 32 and the second external teeth 33 do not rotate at the same rotational speed as the exciter 30A, and the exciter 30A rotates relatively inside the first external teeth 32 and the second external teeth 33. As a result of this relative rotation, the first external teeth 32 and the second external teeth 33 deform by deflection so that their long axis position and short axis position move in the circumferential direction. The period of this deformation is proportional to the rotation period of the exciter axis 30.

[0029] When the first external teeth 32 and the second external teeth 33 deform by bending, their major axis positions shift, causing the meshing position between the first external teeth 32 and the first internal teeth 411 to change in the rotational direction. Here, if the first external teeth 32 has 100 teeth and the first internal teeth 411 has 102 teeth, then with each rotation of the meshing position, the meshing teeth of the first external teeth 32 and the first internal teeth 411 shift, causing the first external teeth 32 to rotate (spin). With the above number of teeth, the rotational motion of the vibrator shaft 30 is reduced at a reduction ratio of 100:2 and transmitted to the first external teeth 32.

[0030] On the other hand, the second external tooth portion 33, which shares the same base portion 34 as the first external tooth portion 32, meshes with the second internal tooth portion 421. Therefore, the meshing position between the second external tooth portion 33 and the second internal tooth portion 421 also changes in the rotational direction as the vibrator shaft 30 rotates. However, since the number of teeth of the second internal tooth portion 421 matches the number of teeth of the second external tooth portion 33, the second external tooth portion 33 and the second internal tooth portion 421 do not rotate relative to each other, and the rotational motion of the second external tooth portion 33 is transmitted to the second internal tooth portion 421 at a reduction ratio of 1:1. As a result, the rotational motion of the vibrator shaft 30 is reduced at a reduction ratio of 100:2 and transmitted to the second internal tooth member 42 and the second cover 45. This reduced rotational motion is then output to the external members.

[0031] [Sensor device] As shown in Figure 2, the sensor device 60 includes strain gauges 416-1 to 416-4, which serve as detection units, provided on each column member 415 of the first internal tooth member 41, and a measuring device 417 connected to each strain gauge 416-1 to 416-4. Each of the strain gauges 416-1 to 416-4 described above is a strain gauge with the same structure, characteristics, and performance. When providing a common explanation without distinguishing between them, they are collectively referred to as "strain gauge 416".

[0032] Strain gauges 416-1 and 416-3 are provided on one and the other of two column members 415 located at both ends in the diametrical direction, respectively, while strain gauges 416-2 and 416-4 are provided on one and the other of two column members 415 located at both ends in another diametrical direction perpendicular to the diametrical direction. In the following explanation, the arrangement of two strain gauges 416-1 and 416-3 located at both ends in the diametrical direction, and the arrangement of two strain gauges 416-2 and 416-4 located at the other ends in the diametrical direction, will be referred to as a "diagonal arrangement," while the arrangements of two strain gauges 416-1 and 416-2, two strain gauges 416-1 and 416-4, two strain gauges 416-3 and 416-2, and two strain gauges 416-3 and 416-4 that are not in a "diagonal arrangement" will be referred to as an "off-diagonal arrangement."

[0033] Furthermore, in the rotational operation of the flexible meshing gear device 1, when the strain gauge 416 is said to be on the "long axis side" of the vibrator 30A, it indicates that it is within a predetermined angular range on both sides in the circumferential direction with respect to the long axis of the vibrator 30A. Alternatively, when the strain gauge 416 is closer to the long axis than to the short axis of the vibrator 30A, it can also be said to be on the "long axis side". Furthermore, when the strain gauge 416 is located on the "short axis side" of the vibrator 30A, it may indicate that it is closer to the short axis than when it is on the long axis side (i.e., it is located on a side other than the long axis), and it may also indicate that it is within a predetermined angular range on both sides in the circumferential direction with respect to the short axis of the vibrator 30A. The default angles on the "major axis" or "minor axis" are, for example, exemplified by being within a range of 45° in both directions around the major or minor axis, but may be set to a narrower range.

[0034] The strain gauge 416 is shown as being attached to the column member 415 in a direction that detects radial expansion and contraction strain in the column member 415. Furthermore, the direction of strain detected by the strain gauge 416 is not limited to the radial direction, but may also be the circumferential direction, the axial direction, or a combination of these directions in an oblique direction. The easily deformable portion 414 (column member 415) deforms more than the internal tooth ring portion 412 when torque is applied to the first internal tooth member 41 (specifically, when torque is applied to the first internal tooth member 411 due to the meshing reaction force while the external connecting portion 413 is connected to the external member). As a result, the radial expansion and contraction strain generated in the column member 415 also increases. Since this strain in the column member 415 is correlated with torque, the torque can be obtained by detecting the strain with a strain gauge 416.

[0035] Each strain gauge 416 is connected to the measuring device 417. Although Figure 2 shows a state where only one strain gauge 416 is connected, in reality all strain gauges 416 are connected to the measuring device 417. Since the strain gauge 416 has the characteristic that its resistance value changes according to the strain, the measuring device 417 can receive a detection signal (e.g., a voltage signal) indicating the resistance value of each strain gauge 416 and acquire the strain. In the flexible meshing gear device 1, the column member 415 on the long axis side of the rotating, substantially elliptical vibrator 30A experiences the greatest contraction. The measuring device 417 is equipped with a rotation detection device (not shown) that detects the rotation angle of the vibrator 30A, and acquires strain detection signals from each strain gauge 416 at the timing when each column member 415 detects the rotation angle on the long axis side of the vibrator 30A. Furthermore, the measuring device 417 has a data table that associates the detected values ​​indicated by the strain detection signals of the strain gauges 416 located on the long axis side of the vibrator 30A with torque values, and can obtain torque values ​​by referring to the data table. Alternatively, the measuring device 417 may obtain torque values ​​by calculation from the detected values ​​of each strain gauge 416 without using the data table.

[0036] The measuring device 417 performs a first detection and a second detection of a smaller amount of strain than the first detection individually for each strain gauge 416 according to the rotation angle of the exciter 30A. When each strain gauge 416 performs the first detection, it performs a correction (temperature compensation) for fluctuations in the detected value of the first detection due to disturbances (ambient temperature) based on the detected value of the second detection performed by the other strain gauges 416. Here, it is preferable that the other strain gauge 416 performing the second detection generates less strain (state quantity) than the strain gauge 416 performing the first detection, and that its ambient temperature is approximately equal to that of the strain gauge 416 performing the first detection, either in terms of its arrangement or detection timing. In this embodiment 1, an example is described in which preferred conditions for the strain gauge 416 that performs the second detection are achieved by its arrangement relative to the strain gauge 416 that performs the first detection.

[0037] Figure 3(A) is a circuit diagram of a Wheatstone bridge circuit 61 incorporating two off-diagonal strain gauges 416, and Figure 3(B) is its equivalent circuit diagram.

[0038] The Wheatstone bridge circuit 61 has first to fourth paths 611 to 614. One end of the first path 611 and one end of the third path 613 are both connected to the positive terminal side of the voltage supply source. One end of the second path 612 and one end of the fourth path 614 are both connected to the negative terminal side (ground side) of the voltage supply source. Furthermore, the Wheatstone bridge circuit 61 has a connection point where the other end of the first path 611 is connected to the other end of the second path 612, and another connection point where the other end of the third path 613 is connected to the other end of the fourth path 614. The measuring device 417 detects the potential difference between the two connection points as a strain detection signal.

[0039] The measuring device 417 is equipped with two sets of Wheatstone bridge circuits 61, each incorporating two strain gauges 416 arranged in an asymmetrical configuration. In this embodiment, for example, one Wheatstone bridge circuit 61 incorporates strain gauges 416-1 and 416-2, while the other Wheatstone bridge circuit 61 incorporates strain gauges 416-3 and 416-4. The two strain gauges 416 may also be arranged in other combinations that are not diagonally opposite each other.

[0040] Figure 3(A) illustrates a Wheatstone bridge circuit 61 consisting of a combination of strain gauges 416-1 and 416-2. This Wheatstone bridge circuit 61 consisting of these combinations will be explained, while the explanation for the other Wheatstone bridge circuit 61 will be omitted. The other Wheatstone bridge circuit 61 can be modified by replacing strain gauges 416-1 and 416-2 with strain gauges 416-3 and 416-4, respectively, in the following explanation.

[0041] In the Wheatstone bridge circuit 61 described above, a strain gauge 416-1 is provided in the first path 611, a strain gauge 416-2 is provided in the second path 612, and resistors R1 and R2 are provided in the third path 613 and the fourth path 614, respectively. The resistance values ​​of resistors R1 and R2 are both equal to the resistance values ​​of strain gauge 416 when no strain is present at room temperature (e.g., 20°C).

[0042] As shown in the equivalent circuit diagram in Figure 3(B), the Wheatstone bridge circuit 61 has strain gauges 416-1 and 416-2 connected in series, and resistors R1 and R2 connected in series, which are connected in parallel between the positive and negative terminals of the voltage supply source. The measuring device 417 then acquires the potential difference between two points, between strain gauge 416-1 and strain gauge 416-2, and between resistor R1 and resistor R2, as the output voltage e (strain detection signal). If the supply voltage from the voltage source is E, and the resistance values ​​of strain gauge 416-1, strain gauge 416-2, resistor R1, and resistor R2 are ε1 to ε4, then the output voltage e is given by the following equation (1). e=(K / 4)·(ε1-ε2-ε3+ε4)·E …(1) Note that K represents the gauge factor, which is usually set to approximately 2.0.

[0043] Since ε3 = ε4, the output voltage e is given by equation (2) below, and is a value proportional to the difference in resistance (output) between strain gauge 416-1 and strain gauge 416-2. e = (K / 4)·(ε1-ε2)·E …(2)

[0044] Since the resistance characteristics of the strain gauge 416 vary with ambient temperature, temperature compensation is necessary to accurately detect strain according to the ambient temperature at the time of detection.

[0045] As mentioned above, in the flexible meshing gear device 1, heat is mainly generated from the meshing portions of the first internal tooth portion 411 and the first external tooth portion 32, and the second internal tooth portion 421 and the second external tooth portion 33. In the first internal tooth member 41, heat is transferred from the internal tooth ring portion 412 to the external connecting portion 413. At that time, the multiple column members 415 located between these components all receive heat under the same conditions, so each strain gauge 416-1 to 416-4, and each column member 415, always have approximately the same ambient temperature.

[0046] Furthermore, since strain gauges 416-1 and 416-2 are arranged off-diagonally, for example, when one strain gauge 416-1 is on the long axis side of the rotating vibrator 30A, the other strain gauge 416-2 is on the short axis side of the vibrator 30A. As a result, the amount of strain in the column member 415 equipped with strain gauge 416-2 is significantly smaller than that in the column member 415 equipped with strain gauge 416-1. For example, strain gauge 416-2 is in a state where there is almost no strain.

[0047] In other words, at the moment when the first detection is performed, in which one strain gauge 416-1 is on the long axis side of the exciter 30A and the detected strain amount (state variable) is large, the other strain gauge 416-2 is on the short axis side and performs a second detection, in which the detected strain amount (state variable) is sufficiently smaller than that of the first detection. The detected value obtained from strain gauge 416-1 by the first detection described above is a value corresponding to the amount of strain generated in the column member 415, plus a value of variation due to the ambient temperature at that time. On the other hand, the detected value obtained from strain gauge 416-2 by the second detection at the same time is solely the value of variation due to the ambient temperature at that time, because the amount of strain in the column member 415 is sufficiently small.

[0048] As mentioned above, the Wheatstone bridge circuit 61 outputs an output voltage e that is proportional to the difference in resistance values ​​(outputs) between strain gauge 416-1 and strain gauge 416-2. Therefore, the output voltage e detected when strain gauge 416-1 is on the long axis side is a value obtained by subtracting the value of fluctuation due to ambient temperature from the value corresponding to the amount of strain generated in the column member 415 of strain gauge 416-1 (temperature-compensated detected value).

[0049] Furthermore, since strain gauges 416-1 and 416-2 are arranged off-diagonally, when strain gauge 416-2 is positioned on the long axis side for the first detection, strain gauge 416-1 is positioned on the short axis side for the second detection, thus enabling temperature compensation for the detected value of strain gauge 416-2. Furthermore, since strain gauges 416-3 and 416-4 also constitute the same Wheatstone bridge circuit 61, strain detection can be performed on these as well while performing temperature compensation.

[0050] [Technical Effects of Embodiment 1] The sensor device 60 has a Wheatstone bridge circuit 61 that acquires a detection value based on a first detection when the amount of strain in the column member 415 of each strain gauge 416 is large, and a detection value based on a second detection when the strain is smaller than the first detection, and corrects the detection value of the first detection based on the detection value of the second detection. This suppresses the effect of temperature drift, which is a disturbance when detecting strain, and makes it possible to detect strain with greater accuracy. Furthermore, by detecting strain with greater accuracy, it becomes possible to detect the torque of the deflection mesh type gear device 1 with greater accuracy.

[0051] Furthermore, in the Wheatstone bridge circuit 61 of the sensor device 60, the first detection and the second detection are performed using separate strain gauges 416 (for example, in the example in Figure 3(A), strain gauge 416-1 and strain gauge 416-2). Therefore, since the first and second detections can be performed simultaneously, it is possible to shorten the overall measurement processing time.

[0052] Furthermore, the sensor device 60 utilizes the fact that each of the multiple strain gauges 416 sequentially performs first detection and second detection in accordance with the rotational movement of the deflection mesh type gear device 1. It performs strain detection with the strain gauge 416 that performs the first detection (e.g., 416-1) and makes corrections based on the detection of the strain gauge 416 that performs the second detection at the same timing (e.g., 416-2). Therefore, it becomes possible to perform strain detection with temperature compensation without having to prepare a dedicated strain gauge (strain gauge for temperature compensation) for correction, and the number of strain gauges 416 required can be reduced. Furthermore, it eliminates the need to secure space for installing strain gauges for temperature compensation, and this also makes it possible to miniaturize the target device.

[0053] Furthermore, the flexible meshing gear device 1, which is the target device, is a rotating device that performs rotational motion, and the sensor device 60 performs first detection and second detection in accordance with the rotational motion of the flexible meshing gear device 1, so it is possible to continuously perform strain detection with temperature compensation during rotational motion. In particular, since the target device is a flexible meshing type gear device 1, the long axis position of the vibrator 30A rotates. By arranging multiple strain gauges 416 around it, it becomes possible to perform periodic and continuous strain detection with temperature compensation in accordance with the rotational movement.

[0054] Although a Wheatstone bridge circuit 61 has been given as an example of a correction unit, the correction unit may be limited to a Wheatstone bridge circuit. Other circuits or configurations capable of performing corrections such as subtraction of the detected value of the strain detection signal of the strain gauge 416 that performs the second detection from the detected value of the strain detection signal of the strain gauge 416 that performs the first detection may also be used as the correction unit.

[0055] [Embodiment 2] Figure 4 is a front view showing the first internal tooth member 41D of a flexible meshing gear device 1 to which the sensor device according to Embodiment 2 of the present invention is applied. In the embodiment 1 described above, a configuration in which four strain gauges 416 are provided at uniform intervals in the circumferential direction was illustrated, but the number of strain gauges 416 is not limited to the above, and may be an odd number. For example, as shown in Figure 4, seven column members 415 may be provided, and strain gauges 416-1 to 416-7 may be individually provided on each column member 415.

[0056] In the above arrangement, for example, when strain gauge 416-1 is located on the long axis side of the vibrator 30A, strain gauges 416-2, 416-3, 416-6, and 416-7, which are positioned off-diagonally from strain gauge 416-1, are located on the short axis side. That is, when strain gauge 416-1 is located on the long axis side and a large amount of strain is detected, strain gauges 416-2, 416-3, 416-6, and 416-7 are located on the short axis side and the amount of strain detected is sufficiently small. Therefore, when obtaining the detection value of the first detection using strain gauge 416-1, it is preferable to obtain the detection value of the second detection from any of the above strain gauges 416-2, 416-3, 416-6, and 416-7.

[0057] For example, by configuring a Wheatstone bridge circuit 61 with other strain gauges 416 arranged in a non-diagonal configuration for each strain gauge 416, it is possible to perform strain detection in the same way as the first internal gear member 41D, even when the number of strain gauges 416 mounted differs.

[0058] In the case of Embodiment 2, the correction unit may also be a configuration of another circuit or the like that capable of performing correction such as subtraction of the detected value of the strain detection signal of the strain gauge 416 that performs the second detection from the detected value of the strain detection signal of the strain gauge 416 that performs the first detection, instead of a Wheatstone bridge circuit.

[0059] [Embodiment 3] Figure 5 is a projective view of the first internal tooth member 41E of a flexible meshing gear device 1 to which the sensor device according to Embodiment 3 of the present invention is applied. The aforementioned first internal tooth member 41 has a deformable portion 414 composed of four intermittently spaced columnar members 415 in the circumferential direction, but is not limited to this. As shown in this first internal tooth member 41E, the easily deformable portion 414E is formed from a ring-shaped flat plate that is continuous in the circumferential direction between the internal tooth ring portion 412 and the external connecting portion 413. However, as shown in the axial cross-sectional view of Figure 6, the axial thickness d3 of this easily deformable portion 414E is set to be smaller than both the axial thickness d1 of the internal tooth ring portion 412 and the axial thickness d2 of the external connecting portion 413.

[0060] Multiple strain gauges 416 are mounted at uniform intervals in the circumferential direction on one of the planes of the easily deformable portion 414E. Here, we illustrate the case where four strain gauges 416 are provided. Note that the number of strain gauges 416 is not limited to four and can be increased or decreased. Each strain gauge 416 is mounted in a direction that detects expansion and contraction strain along the radial direction.

[0061] Thus, in the first internal tooth member 41E, the easily deformable portion 414E is a continuous flat plate in the circumferential direction, and its axial thickness d3 is set to be smaller than the axial thickness d1 of the internal tooth ring portion 412 and the axial thickness d2 of the external connecting portion 413. For this reason, the easily deformable portion 414E is more easily deformed than the internal tooth ring portion 412 when torque is transmitted in the flexible meshing gear device, and as a result, expansion and contraction strain is more easily generated along the radial direction, making it possible to perform more accurate and better torque detection, similar to the easily deformable portion 414. Note that the axial thickness d3 of the easily deformable portion 414E only needs to be smaller than the axial thickness d1 of the internal tooth ring portion 412, and may be the same as or greater than the axial thickness d2 of the external connecting portion 413.

[0062] Although the easily deformable portion 414E is made easily deformable by reducing its thickness, the easily deformable portion 414E may also be formed from a softer metal material or a softer resin material than the other parts (internal tooth ring portion 412, external connecting portion 413), rather than by reducing its thickness.

[0063] Furthermore, in embodiments 1 to 3, the first internal tooth members 41, 41D, and 41E are provided with easily deformable portions 414 and 414E, but these are not essential. For the first internal gear member that does not have a part that is easily deformable, strain gauges 416 may be provided at multiple locations where strain is generated by the rotational operation of the flexible meshing gear device 1 and where heat is similarly transmitted.

[0064] [Embodiment 4] Figure 7 is a front view showing the first internal tooth member 41F of a flexible meshing gear device 1 to which the sensor device according to Embodiment 4 of the present invention is applied. The sensor device 60 provided on the aforementioned first internal tooth member 41 is configured to perform a first detection when each strain gauge 416, which is provided at uniform intervals in the circumferential direction, is located on the long axis side of the vibrator 30A, and to perform a second detection when other strain gauges 416 located on the short axis side are positioned off-diagonally and at the same time. In other words, all strain gauges 416 provided on the first internal tooth member 41 are configured to perform both first and second detection, and no strain gauge is provided specifically for second detection only.

[0065] In contrast, the sensor device according to Embodiment 4 is equipped with a dedicated strain gauge 416a that performs only the second detection without performing the first detection (detection of state quantity). The strain gauge 416a is a strain gauge that has the same structure, characteristics, performance, etc. as the strain gauge 416. The first internal tooth member 41F, like the column member 415, has a column member 415a that extends radially outward from the outer circumference of the internal tooth ring portion 412, and whose extended end does not come into contact with the external connecting portion 413, and the strain gauge 416a is provided on the column member 415a. The column member 415a is made of the same material as the column member 415, and its width and thickness are also set to be the same, so that it transmits heat to the same extent as the column member 415. On the other hand, since the column member 415a does not come into contact with the external connecting part 413, it is structured so that no distortion occurs when the flexible meshing gear device 1 is in rotation, even when it is located on the long axis side of the vibrator 30A.

[0066] By attaching the strain gauge 416a to the column member 415a, the strain gauge 416a can perform a second detection at an ambient temperature approximately the same as that of the other strain gauges 416, while virtually eliminating the influence of strain changes caused by the rotational operation of the deflection-meshing gear device 1.

[0067] Furthermore, the sensor device according to Embodiment 4 performs temperature compensation during the rotational operation of the flexible meshing gear device 1 by subtracting the detected value of the strain detection signal obtained by the second detection of the strain gauge 416a from the detected value of the strain detection signal obtained by the first detection of the strain gauge 416 located on the long axis side of the vibrator 30A, thereby enabling the detection of appropriate strain.

[0068] In this case, the strain gauges 416a are switched on so that a Wheatstone bridge connection is made at the timing of the first detection of each strain gauge 416, thereby configuring a Wheatstone bridge circuit 61 for each strain gauge 416. Alternatively, when the first detection of each strain gauge 416 is performed, software processing may be performed to correct the detected value based on the detected value obtained by the second detection of strain gauge 416a.

[0069] [Embodiment 5] Figure 8 is a front view of the first internal tooth member 41G of a flexible meshing gear device 1 to which the sensor device 60G according to Embodiment 5 of the present invention is applied. In the aforementioned sensor device 60, the first detection and the second detection are performed by separate strain gauges 416, and strain detection with temperature compensation is performed based on the detected values ​​derived from the respective strain detection signals. In contrast, the sensor device 60G performs a first detection when each strain gauge 416 is positioned on the long axis side of the exciter 30A, and a second detection when the exciter 30A rotates and is positioned on the short axis side. Temperature compensation is performed by subtracting the detected value of the strain detection signal based on the second detection performed by the same strain gauge 416 from the detected value of the strain detection signal based on the first detection performed by the same strain gauge 416.

[0070] Therefore, the sensor device 60G does not use the Wheatstone bridge circuit 61, which performs strain detection and temperature compensation simultaneously, as a correction unit. The sensor device 60G includes a plurality of processing circuits 418 that detect resistance values ​​connected to each strain gauge 416, and a measuring device 417G that serves as a correction unit connected to each processing circuit 418. Furthermore, the measuring device 417G includes a storage unit for each strain gauge 416 that stores the detected value based on the strain detection signal at the first detection and the detected value based on the strain detection signal at the second detection. In addition, for each strain gauge 416, when the storage unit contains the most recent detected value from the first detection and the most recent detected value from the second detection, the measuring device 417G calculates a temperature-compensated strain detected value for each strain gauge 416.

[0071] In the sensor device 60G shown in Embodiment 5 above, each strain gauge 416 performs a first detection and a second detection in any order, and strain detection with temperature compensation is performed individually for each strain gauge 416 based on the detected value from the first detection and the detected value from the second detection obtained by the same strain gauge 416. Therefore, a dedicated strain gauge for the second detection is not required, and furthermore, there is no need to prepare a pair of strain gauges 416 for the first detection and another strain gauge 416 for the second detection, which makes it possible to simplify the configuration, facilitate manufacturing, and reduce the number of parts. Furthermore, when multiple strain gauges 416 are installed, it is not necessary to select an arrangement where the ambient temperature of each strain gauge 416 is equal, thus ensuring design flexibility. Furthermore, with the above configuration, it is possible to reduce the number of strain gauges 416 to as few as one.

[0072] Furthermore, the flexible meshing gear device 1, which is the target device, performs a first detection when each strain gauge 416 is on the long axis side of the vibrator 30A, and a second detection when it is on the short axis side, and performs strain detection with temperature compensation from these detected values. The sensor device 60G is particularly suitable for detecting strain in a flexible mesh type gear device 1, where each strain gauge 416 has ample opportunity to periodically perform first and second detections, as described above.

[0073] [others] The details shown in each of the above embodiments can be modified as appropriate without departing from the spirit of the invention. For example, although the sensor devices shown in each of the above embodiments were described using a cylindrical flexible meshing gear device as an example, they can also be suitably applied to flexible meshing gear devices other than cylindrical ones, such as cup-shaped or top-hat-shaped gear devices. Furthermore, the sensor devices shown in each embodiment are not limited to flexible meshing gear systems as target devices, but can also be applied to other devices that perform various types of motion, such as rotational and linear motion, for example, motors, linear motors, ball screw devices, and injection molding machines. In this case, if the configuration has multiple strain gauges, it is preferable to arrange them around a member that performs rotational motion, or to arrange them in line with the operating range of a member that performs linear motion.

[0074] Furthermore, although a strain gauge was used as an example of a detection unit, the above sensor device configuration can be applied to any sensor that requires correction such as temperature compensation. Examples of detection units other than strain gauges include magnetic sensors and vibration sensors. Furthermore, in the embodiment, correction was performed by subtracting the detected value of the second detection from the detected value of the first detection. However, the correction method is not particularly limited as long as the detected value of the first detection is corrected based on the detected value of the second detection. For example, the detected value of the second detection may be multiplied by a predetermined coefficient and then subtracted from the detected value of the first detection. [Explanation of Symbols]

[0075] 1. Gear system 30 Vibrator axis 30A vibrator 32. First external teeth (external gear) 33. Second external gear (external gear teeth) 41 First internal tooth member 411 First internal teeth 412 Internal tooth ring section 413 External connection part 414 Easily deformable parts 415 Column members 416, 416-1~416-7 Strain gauge (detection unit) 417 Measuring device 417G Measuring device (correction section) 418 Processing Circuit 42 Second internal tooth member 421 Second internal tooth region 60,60G sensor device 61. Wheatstone bridge circuit (correction section) O1 Rotation axis R1,R2 resistor

Claims

1. A sensor device for detecting a predetermined state quantity, performing a first detection and a second detection in which a state quantity generated by the first detection is smaller than that generated by the first detection; The sensor device includes a correction unit that corrects the detection value of the first detection based on the detection value of the second detection.

2. The first detection and the second detection are performed by different detection units. The sensor device according to claim 1 .

3. The plurality of detection units perform the first detection and the second detection in accordance with the operation of the target device. The sensor device according to claim 2 .

4. The target device is a rotating device, and the plurality of detecting units perform the first detection and the second detection in accordance with the rotation of the rotating device. The sensor device according to claim 3 .

5. the rotating device is a flexible mesh gear device having a vibrator whose cross section perpendicular to the axis has a substantially elliptical outer shape, The detecting section on the long axis side of the vibrator performs the first detection, and the detecting section on the short axis side of the vibrator performs the second detection. The sensor device according to claim 4 .

6. The first detection and the second detection are performed by the same detection unit, and the first detection and the second detection are switched over with the passage of time. The sensor device according to claim 1 .

7. The target device is a flexible mesh gear device having a vibrator with a substantially elliptical outer shape in cross section perpendicular to the axis, and the detection unit performs the first detection when the vibrator is closer to the major axis side than to the minor axis side, and performs the second detection when the vibrator is closer to the minor axis side than at the time of the first detection. The sensor device according to claim 6.

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