Sensors, devices and manufacturing methods

Abstract

To improve the detection accuracy of a sensor.SOLUTION: A sensor that includes: a first support portion and a second support portion opposite the first support portion; a plurality of elastic portions connecting the first support portion and the second support portion; and a scale fixed to the first support portion, and a detection head opposite the scale and fixed to the second support portion. The sensor detects a rotation of the second support portion relative to the first support portion by means of the scale and the detection head. The sensor is characterized in that the plurality of elastic portions are arranged side by side in a circumferential direction of the rotation, a connecting portion between each of the plurality of elastic portions and a first support portion, and a connecting portion between each of the plurality of elastic portions and the second support portion are arranged along an axial direction of the rotation, and the scale and the detection head are arranged side by side in a radial direction of the rotation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sensor. [Background technology]

[0002] Automobiles and robots are equipped with sensors that detect torque and output it as an electrical signal. The sensors are equipped with displacement detection devices such as encoders, and torque values ​​are calculated using the displacement information detected by the displacement detection devices. The encoders are required to detect the torque acting on the sensors with high accuracy.

[0003] Therefore, Patent Document 1 proposes a configuration in which the detection head is disposed outward from the scale in the Y-axis direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-189516 Summary of the Invention [Problem to be solved by the invention]

[0005] The sensor of Patent Document 1 is structurally prone to displacement in directions other than the torque detection direction, and to avoid this, a reinforcing structure that suppresses displacement in directions other than the original torque detection direction is provided in the encoder (linear scale and detection head) that detects elastic deformation due to external force, but this makes the configuration complicated and there is a risk that detection accuracy will be reduced, especially by displacement in the Z-axis direction that is not the torque detection direction. Therefore, an object of the present invention is to improve the detection accuracy of sensors. [Means for solving the problem]

[0006] A first means for solving the above problem is a sensor comprising a first support part, a second support part facing the first support part, a plurality of elastic parts connecting the first support part and the second support part, a scale fixed to the first support part, and a detection head facing the scale and fixed to the second support part, and detecting rotation of the second support part relative to the first support part using the scale and the detection head, characterized in that the plurality of elastic parts are arranged side by side in the circumferential direction of the rotation, the connecting parts between each of the plurality of elastic parts and the first support part and the connecting parts between each of the plurality of elastic parts and the second support part are arranged along the axial direction of the rotation, and the scale and the detection head are arranged side by side in the radial direction of the rotation.

[0007] A second means for solving the above problem is a sensor having a first support portion, a second support portion facing the first support portion, and a plurality of elastic portions connecting the first support portion and the second support portion, and detecting rotation of the second support portion relative to the first support portion by an encoder consisting of a scale and a detection head facing the scale, wherein the elastic portions are arranged at predetermined intervals on a concentric circle about the center of rotation and have a first connecting portion provided between the first support portion and the elastic portion and a second connecting portion provided between the second support portion and the elastic portion, the scale is fixed to the first support portion, the detection head is fixed to the second support portion, and the scale and detection head are arranged side by side in the radial direction of the rotation. [Effects of the Invention]

[0008] It is possible to provide a technique that is advantageous in improving the detection accuracy of the sensor. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a top view of the sensor according to the first embodiment, FIG. 1B is a schematic diagram of the area surrounded by a circle 5000 in FIG. 1A as viewed from the Y direction, and FIG. 1C is an enlarged view of the main part in FIG. 1B. [Figure 2]1A is a perspective view of a steel plate according to the first embodiment, FIG. 1B is an enlarged view of a main part of FIG. 1A, and FIG. 1C is a schematic view showing a process for manufacturing a sensor. [Figure 3] 1A is a perspective view of a structural part according to the first embodiment, FIG. 1B is a perspective view of a structure according to the first embodiment, and FIG. 1C is an enlarged view of a part surrounded by a circle 6000 in FIG. 1B. [Figure 4] 1A is a block diagram of the configuration of a sensor according to the first embodiment, and FIG. 1B is a block diagram of the functions of the sensor according to the first embodiment. [Figure 5] 1A is a schematic diagram of an encoder device, which is an example of a displacement detection device according to the first embodiment, and FIG. 1B is a plan view of a detection head according to the first embodiment. [Figure 6] FIG. 2 is an explanatory diagram of a scale according to the first embodiment. [Figure 7] FIG. 2 is a plan view of the light-receiving element array according to the first embodiment. [Figure 8] (a) is a perspective view of a structure according to a second embodiment, (b) is an enlarged view of the part surrounded by a circle 7000 in (a), (c) is a diagram showing a method for attaching an encoder, and (d) is a bottom view of the attachment part. [Figure 9] FIG. 10 is an explanatory diagram of a robot system according to a third embodiment. [Figure 10] FIG. 11 is a partial cross-sectional view showing a joint of a robot arm according to a third embodiment. [Figure 11] FIG. 11 is a block diagram showing a control system for a joint of a robot arm according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a description will be given of an embodiment of the present invention with reference to the drawings. However, the embodiment described below is one embodiment of the invention and is not limited to this. Common configurations will be described with mutual reference to multiple drawings, and descriptions of configurations with common reference numerals will be omitted as appropriate. Items with the same name but different functions can be distinguished by adding "0", such as "first item" and "second item".

[0011] First Embodiment Fig. 1(a) is a top view of a torque sensor as an example of a sensor 500 according to this embodiment. Fig. 1(b) is a schematic diagram of a portion surrounded by a circle 5000 in Fig. 1(a) as viewed from the Y direction. Fig. 1(c) is an enlarged view of a main portion of Fig. 1(b).

[0012] The sensor 500 comprises an encoder 510 and a structure 520. The encoder 510 comprises a detection head 7 and a scale 2. The structure 520 comprises a support portion 501, a support portion 502, and a structural portion 900. The structural portion 900 has connecting portions 601, 602 arranged between the support portion 501 and the elastic portion 503 and between the support portion 502 and the elastic portion 503. The structural portion 900 comprises a plurality of elastic portions 503 that connect the support portion 501 and the support portion 502. The portion where the support portion 501 and the elastic portion 503 are connected is the connecting portion 401, and the portion where the support portion 502 and the elastic portion 503 are connected is the connecting portion 402.

[0013] A plurality of elastic portions 503 are arranged at predetermined intervals on a circle whose center coincides with the rotation axis C0.

[0014] Joining parts 601, 602 and elastic part 503 are made of the same material and configured as a single unit. However, by providing support parts 501, 502 above and below joining parts 601, 602, joining parts 601, 602 are reinforced, and only elastic part 503 is configured to elastically deform due to a force applied to structure 520. Joining part 601 is, for example, a first joining part, and joining part 602 is, for example, a second joining part.

[0015] The support portions 501 and 502 are flat plate-like members, and are, for example, annular in shape with the rotation axis C0 as the center as shown in Fig. 1(a). The support portion 501 is capable of being displaced relative to the support portion 502 in the rotation direction with the rotation axis C0 as the center. Note that the shape of the support portions 501 and 502 is not limited to this, and may be, for example, a disk shape.

[0016] Support portion 501 and support portion 502 are arranged facing each other with a gap in the Z direction, which is the direction in which rotation axis C0 extends. Elastic portion 503 is arranged between support portions 501 and 502 and is connected to connecting portions 601 and 602.

[0017] The support portions 501 and 502 are fixed to the elastic portion 503 via the connecting portions 601 and 602. The elastic portions 503 are deformed by the force applied to the structure 520, and a plurality of elastic portions 503 are arranged at intervals from each other on the outer periphery of the sensor 500 along the circumferential direction of the rotation axis C0 or lined up in the circumferential direction.

[0018] The support part 501 supports one of the scale 2 and the detection head 7, and the support part 502 supports the other of the scale 2 and the detection head 7. In this embodiment, the support part 501 supports the scale 2, and the support part 502 supports the detection head 7.

[0019] When a torque in the rotational direction acts between the support portions 501 and 502, the elastic portion 503 deforms according to the magnitude of the torque, and the connecting portion 601 rotates relative to the connecting portion 602 around the rotation axis C0 by an amount corresponding to the amount of deformation. The elastic portion 503 is made of a material having an elastic modulus, i.e., a spring constant, according to the target torque measurement range and the required resolution. The elastic portion 503 is made of a material such as resin or metal, including steel and stainless steel. In this embodiment, the connecting portions 601 and 602 and the elastic portion 503 are made of the same material and are integrally constructed as a unit. "Integratedly constructed" means that there are no attachment or connecting parts between the connecting portions 601 and 602 and the elastic portion 503.

[0020] The materials constituting the connecting portions 601, 602 and the elastic portion 503 may be metal or a non-metallic base material that has been plated. In this embodiment, SECC (Steel Electrolytic Cold Commercial) is used, and the connecting portions 601, 602 and the elastic portion 503 are made by bending a metal sheet made of SECC. By manufacturing the structural portion 900 by bending a metal sheet, it is possible to manufacture the sensor at a lower cost than conventional sensors that are manufactured by cutting. Since the connecting portions 601, 602 and the elastic portion 503 are integrally formed from metal sheet, they have a uniform thickness. Similarly, the support portions 501, 502 are also made of metal sheet made of SECC.

[0021] The SECC used in this embodiment is a steel type obtained by electrogalvanizing a cold-rolled steel plate, SPCC (Steel Plate Cold Commercial). SPCC is a steel plate made of carbon, manganese, phosphorus, and sulfur. The material properties of the SPCC used in this embodiment are as follows:

[0022] The melting point is between 1510℃ and 1550℃, and the specific gravity is 7.8g / cm 3 More than 7.9g / cm 3 The electrical resistance is between 0.085 μΩ·m and 0.1 μΩ·m, and the specific heat is between 440 KJ / kg·K and 480 KJ / kg·K. The volumetric specific heat is 3.3 W / cm 3 ·K or more 3.9W / cm 3 ·K or less, linear expansion coefficient 10×10 6 / K or more 12×10 6 / K or less, Young's modulus is 200 GPa or more and 220 GPa or less, and Poisson's ratio is 0.25 or more and 0.35 or less.

[0023] The sensor 500 according to this embodiment detects torque acting in the circumferential direction of rotation around the rotation axis C0. It is preferable to minimize torque acting in the Z-axis direction, i.e., the axial direction of rotation. Therefore, the connecting portion 401 connecting the elastic portion 503 and the support portion 501, and the connecting portion 402 connecting the elastic portion 503 and the support portion 502, are connected along the axial direction of rotation. The elastic portion 503 is disposed on the outer ring of the sensor 500, increasing the amount of displacement of the elastic portion 503 when an external force (torque) is applied. However, the elastic portion 503 does not necessarily have to be disposed on the outer ring, as long as it is disposed along the circumferential direction of rotation. Additionally, the support portions 501 and 502 are attached as support members to the surface of the connecting portion 601 opposite the elastic portion 503 and the surface of the connecting portion 602 opposite the elastic portion 503. This minimizes detection of torque acting in the axial direction of rotation, enabling accurate detection of torque acting in the circumferential direction of rotation, which is the positioning direction.

[0024] In this embodiment, the scale 2 and the detection head 7 are attached to the support parts 501 and 502 as support materials, which makes it more difficult to detect the torque acting in the direction of the rotation axis than when they are attached to the connecting parts 601 and 602.

[0025] Furthermore, the scale 2 and detection head 7 according to this embodiment are arranged side by side in the radial direction of the annular support parts 501 and 502, i.e., in the direction in which the support parts 501 and 502 rotate relative to one another. With this configuration, the scale 2 and detection head 7 can be arranged closer to the outer periphery of the sensor 500 than when they are arranged side by side in the axial direction of rotation, i.e., in the direction in which the support parts 501 and 502 overlap. This increases the amount of displacement of the scale 2 when torque is applied to the sensor 500, thereby improving the torque detection accuracy. Furthermore, the scale 2 and detection head 7 are arranged close to the elastic part 503, i.e., in a position facing the elastic part 503. This allows the displacement of the elastic part 503 to be measured more accurately.

[0026] The scale 2 is preferably disposed outward of the distance R from the rotation axis C0 to the end 6010 in the radial direction of the coupling portions 601 and 602, but it is sufficient that the surface 20 opposite the surface of the scale 2 on the rotation axis C0 side is disposed outward of the distance R. The distance R is, for example, not less than 3 cm and not more than 7 cm. Although the scale 2 is used here as an example, the detection head 7 may also be disposed outward of the distance R.

[0027] The sensor 500 measures torque by detecting the relative displacement between the coupling portions 601 and 602, i.e., the displacement in the rotational direction acting between the coupling portions 601 and 602. Although torque can be measured using just one encoder 510, it is preferable that a plurality of encoders are provided in the circumferential direction of the support portions 501 and 502. It is even more preferable that the number of encoders is four. In this embodiment, the sensor 500 has four encoders 510.

[0028] The four encoders 510 have the same configuration. The four encoders 510 are arranged at equal intervals at positions symmetrical by 90 degrees around the rotation axis C0. The number of encoders 510 included in the sensor 500 is preferably four, but is not limited to this. The number of encoders 510 included in the sensor 500 may be one, two, three, five or more.

[0029] Each encoder 510 is an incremental or absolute encoder. In this embodiment, an incremental encoder will be described as an example, but an absolute encoder may also be used. Furthermore, each encoder 510 is preferably an optical, capacitive, or magnetic encoder, and among these, an optical encoder that can achieve high detection resolution is more preferable. Therefore, in this embodiment, each encoder 510 is an optical encoder.

[0030] Furthermore, when an optical encoder is used, the scale 2 (or the detection head 7) is attached to the inside of the bent part of the support part 501, so the bent part has a light-blocking effect against external light.

[0031] Each encoder 510 may be a linear encoder or a rotary encoder. The relative displacement in the rotational direction between the support unit 501 and the support unit 502 around the rotation axis C0 is a minute displacement at the position of each encoder 510 and can be considered as a displacement in the translational direction. Therefore, in this embodiment, each encoder 510 is a linear encoder. Also, although the encoder 510 is a reflective type in this embodiment, it may be a transmissive type. Each encoder 510 can detect the relative displacement in the rotational direction of the support unit 502 with respect to the support unit 501 around the rotation axis C0, i.e., the relative displacement in the tangential direction.

[0032] Each encoder 510 has a scale 2 and a detection head 7 arranged to face the scale 2. The detection head 7 includes a light-transmitting material 6 that transmits light, and a light source 1, a light-receiving unit 3, and a printed wiring board 4 that are fixed to the light-transmitting material 6 and serve as a detection unit that processes information from the scale 2. The light-transmitting material 6 is located between the detection unit and the scale 2 and may be made of, for example, glass or plastic, but is preferably made of glass. The rotation axis C0 is the axis of rotation of the structure 520 in the direction from the detection head 7 toward the scale 2.

[0033] The light-transmitting material 6 of the detection head 7 is adhered to the support part 502 by an adhesive 11 that contacts the light-transmitting material 6 and the support part 502. The light-transmitting material 6 is directly adhered to the support part 502, but the resin 5 that covers the detection unit and the printed wiring board 4 may also be directly adhered to the support part 502.

[0034] In this embodiment, the detection head 7 is adhered to and supported by the support part 502. The scale 2 is adhered to and supported by the support part 501. In other words, the supports 501, 502 are directly adhered to the scale 2 and the detection head 7, without any parts such as a sensor stay being interposed therebetween. This minimizes the number of attachment parts and coupling parts that make up the sensor 500, and therefore the torque value τ can be determined with high accuracy even if there is an environmental change such as an increase in the temperature around the sensor 500.

[0035] Next, the configuration of the detection head 7 will be described with reference to FIG.

[0036] The detection head 7 has a light-transmitting material 6, and a light source 1, a light-receiving unit 3, and a printed wiring board 4 as detection units. The light source 1 used in this embodiment will be described as an example in which a current-confined point-emitting LED is used. Diverging light is irradiated from the light source 1 onto the scale 2, and the reflected light is received by the light-receiving unit 3. The light irradiated from the light source 1 onto the scale 2 may have any wavelength, but is preferably 550 nm or more and 1000 nm or less, and more preferably 650 nm or more and 900 nm or less.

[0037] The light receiving unit 3 has a light receiving element array 9. The light source 1 and the light receiving unit 3 are mounted on a printed wiring board 4 and sealed with a transparent resin 5 that transmits light. A transparent light transmitting material 6 that transmits light is disposed on the surface of the resin 5. With this configuration, the light source 1 and the light receiving unit 3 are protected by the resin 5 and the light transmitting material 6.

[0038] Even if glass or the like serving as the light-transmitting material 6 is not present on the surface of the resin 5 and the resin 5 is exposed, the resin 5 can still function as the light-transmitting material 6. In this case, the resin 5 is bonded to the support portion 502 by an adhesive 11 that contacts the resin 5 and the support portion 502. In this embodiment, the light-transmitting material 6 of the detection head 7 is bonded to the support portion 502, but not only the light-transmitting material 6 but also the printed wiring board 4 and the resin 5 may be bonded to the support portion 501. The refractive indexes of the resin 5 and the light-transmitting material 6 are 1.2 or more and 1.8 or less, and the difference between their respective refractive indices is preferably 0.2 or less, and more preferably they are equal.

[0039] The support part 502 has an opening, and there is no obstruction between the scale 2 and the detection head 7.

[0040] The distance between the scale 2 and the detection head 7 may be, for example, 0.2 mm or more, preferably 0.6 mm or more. Alternatively, the distance may be, for example, 1.2 mm or less, preferably 1.0 mm or less. A distance between 0.6 mm and 1.0 mm is more preferable.

[0041] The thickness of the light transmitting material 6 is preferably 0.2 mm or more, more preferably 0.6 mm or more, and is preferably 1.2 mm or less, more preferably 1.0 mm or less.

[0042] The thickness of the resin 5 is preferably 0.4 mm or more, and more preferably 0.6 mm or more. It is also preferably 1.1 mm or less, and more preferably 0.9 mm or less. The distance between the light transmitting material 6 and the detection unit 10 is preferably, for example, 0.4 mm or more and 1.4 mm or less.

[0043] As shown in Figure 1(c), when adhesive 11 is applied to the bonding position between support part 502 and detection head 7, the liquid surface may form a meniscus. Although a normal adhesive can be used as adhesive 11, a two-part mixed curing type or ultraviolet curing type adhesive is preferable, as it allows for fixing at any timing. By using encoder 510, it is possible to measure the relative displacement between connecting part 601 and connecting part 602 as a relative amount starting from a certain reference position.

[0044] Next, a method for forming the sensor 500 according to this embodiment will be described with reference to FIGS.

[0045] Fig. 2(a) shows a steel plate 700 with a uniform thickness. The steel plate 700 has a freely bendable portion 703. Fig. 2(b) is an enlarged view of a main portion of Fig. 2(a), and Fig. 2(c) shows the assembly process of the steel plate 700.

[0046] Bendable portion 701 and bendable portion 702 are bent along line 800 in the directions of arrows 710 and 720, respectively. Also, portion 703 is bent along line 801 in the direction of arrow 730. Bent portions 701 and 702 become coupling portions 601 and 602 in sensor 500, and portion 703 becomes elastic portion 503 in sensor 500.

[0047] Steel plate 700 bent along the bending line is then bent in the direction of arrow 740, using line 802 as the bending line. End 750 and end 751 are then joined together to form structural part 900 as shown in FIG. 3(a).

[0048] Next, as shown in Fig. 3(b), support parts 501 and 502 are provided above and below the structural part 900. Fig. 3(b) shows a state in which the support parts 501 and 502 are provided but the scale 2 and the detection head 7 are not attached.

[0049] Figure 3(c) is an enlarged view of the area surrounded by a circle 6000 in Figure 3(b) with the scale 2 and detection head 7 attached to the support parts 501 and 502. The support parts 501 and 502 are bent, and the scale 2 and detection head 7 are attached to the tip of the bent part along the radial direction of rotation to manufacture the sensor 500. By providing the scale 2 or detection head 7 at the tip of the bent part, i.e., on the outer ring of the sensor 500, the displacement of the elastic part 503 can be measured with high precision.

[0050] 4(a) is a block diagram showing the configuration of the arithmetic processing device 600 of the sensor 500 according to this embodiment. The arithmetic processing device 600 has the same number of signal processing circuits 50 as the encoders 510, for example, four, and a computer 650 connected to the four signal processing circuits 50. The computer 650 is, for example, a microcomputer. An example of the configuration of the computer 650 will be described below.

[0051] The computer 650 has a CPU 651 (Central Processing Unit) as a processor, which is an example of a processing unit. The computer 650 also has a ROM 652 (Read Only Memory) that stores a program 620 for causing the CPU 651 to perform arithmetic processing to determine the torque value τ, and a RAM 653 (Random Access Memory) used to temporarily store data, etc. The computer 650 also has an I / O (Input / Output) 654 that is an interface with the signal processing circuit 50 and externally connected devices, such as the control unit 300 and external storage (not shown). The CPU 651, ROM 652, RAM 653, and I / O 654 are connected to each other via a bus 660 so as to be able to communicate with each other.

[0052] The torque value τ is torque information, i.e., torque data, and may be a normalized value. The CPU 651 acquires phase information from each signal processing circuit 50, performs arithmetic processing in accordance with the program 620 to determine the torque value τ, and outputs the determined torque value τ to the control unit 300.

[0053] In this embodiment, a storage device 670, which is an example of a storage unit, is configured with the ROM 652 and the RAM 653. Note that the configuration of the storage device 670 is not limited to this. Furthermore, the storage device 670 may be an internal storage, an external storage, or a combination of an internal storage and an external storage.

[0054] In this embodiment, the non-transitory recording medium readable by the computer 650 is the ROM 652, and the program 620 is recorded in the ROM 652, but this is not limiting. The program 620 may be recorded on any recording medium as long as it is a non-transitory recording medium readable by the computer 650. As a recording medium for supplying the program 620 to the computer 650, for example, a flexible disk, an optical disk, a magneto-optical disk, a magnetic tape, a non-volatile memory, etc. can be used.

[0055] The arithmetic processing device 600 determines relative displacement information between the connecting portion 601 and the connecting portion 602 based on the detection signal S, which is an encoder signal from the detection head 7 of each encoder 510. Then, the arithmetic processing device 600 converts the determined displacement information into a torque value τ and outputs it to the control unit 300. The CPU 651 performs processes such as interpolation processing of the information obtained by the detection head 7 from the scale 2 as the detection signal S, writing and reading information to and from the storage device 670, and outputting a position signal.

[0056] FIG. 4(b) is a block diagram showing the functions of the sensor 500 according to this embodiment.

[0057] The sensor 500 has a plurality of, for example, four encoder devices 550 as an example of a plurality of displacement detection devices. Each encoder device 550 has an encoder 510, a signal processing circuit 50, and some of the functions of the computer 650 shown in Fig. 4(a). When the CPU 651 shown in Fig. 4(a) executes the program 620, it functions as each displacement calculation unit 680 and torque calculation unit 681 shown in Fig. 4(b).

[0058] That is, the CPU 651 functions as a displacement calculation unit 680 of each encoder device 550. The CPU 651 also functions as a torque calculation unit 681 of the sensor 500 that calculates a torque value τ using the phase Φ1 that is displacement information calculated by each displacement calculation unit 680. The calculation process of the phase Φ1 by each displacement calculation unit 680 will be described later. The phase Φ1 is relative displacement information of the joint portion 601 with respect to the joint portion 602 that is caused by the elastic deformation of the elastic portion 503 in response to the torque acting on the sensor 500, and does not include elastic deformation of the joint portion 601.

[0059] An encoder device 550 according to this embodiment will be described with reference to Fig. 5. Fig. 5(a) is a schematic diagram of the encoder device 550 according to this embodiment as seen from the Y direction, and Fig. 5(b) is a plan view of the detection head 7 according to this embodiment as seen from the X direction.

[0060] The scale 2 moves translationally in the circumferential direction of rotation relative to the detection head 7. The direction of movement of the scale 2 moving translationally relative to the detection head 7 is the X direction, or the Y direction intersecting the X direction, and the direction intersecting the X and Y directions is the Z direction. The X direction, Y direction, and Z direction are preferably perpendicular to each other. The X direction and Y direction are also positioning directions in the encoder 510.

[0061] The detection head 7 is disposed at a position facing the scale 2 in the X or Y direction. The detection head 7 has a light source 1 made up of an LED, which is an example of a light-emitting unit, and a light-receiving unit 3. The light-receiving unit 3 is disposed at a distance from the light source 1 in the X or Y direction.

[0062] An encoder device 550 will be described with reference to Figure 5. A scale track 8 is provided on the surface of the scale 2. A divergent light beam emitted from the light source 1 is irradiated onto the scale track 8 of the scale 2 from an oblique direction. The light beam reflected by the scale track 8 is reflected towards the light receiving element array 9 of the detection head 7.

[0063] The signal processing circuit 50 is configured with a semiconductor element such as an IC chip. The signal processing circuit 50 is mounted on the surface of the printed wiring board 4, for example. The arrangement position of the signal processing circuit 50 is not limited thereto, and the signal processing circuit 50 may be arranged in a location other than on the printed wiring board 4. In FIG. 5(a), the signal processing circuit 50 is illustrated in a location other than on the printed wiring board 4 for convenience of explanation. The signal processing circuit 50 includes a circuit unit 51 that processes the detection signal S acquired from the light receiving element array 9, out of the detection signals S.

[0064] Next, the configuration of the scale 2 will be described with reference to Figure 6. The scale 2 has a pattern portion 80, and the detection head 7 reads the pattern portion 80 of the scale 2 and outputs a detection signal S to the signal processing circuit 50. The pattern portion 80 is formed on the scale track 8.

[0065] The light beam received by the light receiving element array 9 is converted into electrical signals. Each electrical signal is sent as a detection signal S to a circuit section 51 of a signal processing circuit 50.

[0066] The patterns 810 of the scale track 8 are spaced apart from one another in the X or Y direction at a predetermined pitch P1. The pitch P1 used to measure torque is preferably as small as possible. By narrowing the pitch P1, a sensor 500 with high resolution can be achieved. The following describes a case where the pitch P1 is 100 μm.

[0067] The scale 2 has a substrate such as glass. The pattern portion 80 is formed by patterning a chromium film on the substrate. The substrate of the scale 2 may be a resin such as polycarbonate or a metal such as SUS. The pattern portion 80 may also be a film such as aluminum, as long as it functions as a reflective film.

[0068] 7 is a plan view of the light receiving element array 9 according to this embodiment. The light receiving element array 9 has a plurality of light receiving elements 90, for example, 32 light receiving elements 90, arranged at a pitch of 50 μm in the X direction. Each light receiving element 90 has, for example, a width X_pd of 50 μm in the X direction and a width Y_pd of 800 μm in the Y direction. The total width X_total of the light receiving element array 9 is 1600 μm.

[0069] The pattern 810 on the scale 2 is projected at a magnification of 2 times on the light receiving element array 9. Therefore, the detection range on the scale 2 is, for example, 800 μm in the X direction and 400 μm in the Y direction. The detection signal of the light receiving element array 9 is output to a circuit section 51 shown in FIG. 5(a).

[0070] Second Embodiment Next, a method for attaching the encoder 510 according to this embodiment will be described with reference to Fig. 8. This embodiment differs from the first embodiment in that attachment portions 310 and 320 are provided between the support portions 501 and 502 and the detection head 7 and the scale 2.

[0071] Fig. 8(a) is a diagram showing support parts 501 and 502 provided above and below structural part 900, Fig. 8(b) is an enlarged view of the part surrounded by circle 7000 in Fig. 8(a), and Fig. 8(c) is a diagram showing a method for attaching encoder 510. Fig. 8(d) is a bottom view of encoder 510 after it has been attached.

[0072] In this embodiment, the scale 2 and the detection head 7 are attached to the attachment portions 310 and 320 , and the attachment portions 310 and 320 are fixed to the support portions 501 and 502 .

[0073] Mounting portion 310 is made up of components 301 and 302, and components 301 and 302 are combined to form mounting portion 310, to which scale 2 is attached. Similarly, mounting portion 320 is made up of components 303 and 304, and components 303 and 304 are combined to form mounting portion 320, to which detection head 7 is attached.

[0074] Mounting portion 310 is positioned on one of support portions 501 and 502 by pin 305, and mounting portion 320 is positioned on the other of support portions 501 and 502 by pin 306. Support portions 501 and 502 are provided with holes of the same diameter as pins 305 and 306, and mounting portions 310 and 320 are positioned by fitting pins 305 and 306 into these holes.

[0075] In this embodiment, a sponge sealant 307 is sandwiched between the component 302 and the component 304. This prevents dust and other particles from entering around the sensor 500. The component 302 is provided with a hole for positioning the scale 2. Although the sealant 307 is not shown in FIG. 8(d), the sealant 307 is provided between the component 302 and the component 304 to prevent dust and other particles from entering around the scale 2.

[0076] When attaching the attachment parts 310, 320 to the support parts 501, 502, the attachment parts 310, 320 can be positioned by fitting shafts of the same diameter into recesses provided in the components 301-304.

[0077] One of the detection head 7 and the scale 2 can be attached to the attachment part 310, and the other of the detection head 7 and the scale 2 can be attached to the attachment part 320. Furthermore, one of the attachment part 310 and the attachment part 320 can be attached to the support part 501, and the other of the attachment part 310 and the attachment part 320 can be attached to the support part 502.

[0078] <Third embodiment> Next, a robot system 100 as an example of a system equipped with the sensor 500 according to the first embodiment will be described with reference to FIGS.

[0079] FIG. 9 is an explanatory diagram of a robot system 100 according to this embodiment. As shown in FIG. 9, the robot system 100 includes a robot 200 and a control unit 300. The robot 200 can perform tasks such as manufacturing an article by grasping a first workpiece W10 and assembling the grasped first workpiece W10 to a second workpiece W20. Furthermore, even if a worker is nearby, the robot 200 can work collaboratively with the worker.

[0080] The mechanical device is, for example, a robot 200, and the control unit 300 that controls the mechanical device is, for example, a robot control device that controls the robot 200. A teaching pendant 400, which is an example of a teaching device, can be connected to the control unit 300. The teaching pendant 400 is a device that teaches the robot 200 and outputs teaching data to the control unit 300. The control unit 300 generates trajectory data based on the teaching data and operates the robot 200 according to the trajectory data.

[0081] The robot 200 includes a robot arm 201 and a robot hand 202, which is an example of an end effector. The robot arm 201 is, for example, a vertically articulated robot arm. A fixed end 201A, which is the base end of the robot arm 201, is fixed to a base 150. A robot hand 202 is attached to a free end 201B, which is the tip of the robot arm 201. The robot arm 201 has multiple links 210, 211, 212, and 213, which are rotatably connected at joints J1, J2, and J3. A driving device 230 is provided at each of the joints J1 to J3 of the robot arm 201. The driving device 230 for each of the joints J1 to J3 has an output appropriate for the required torque.

[0082] In the following, the joint J1 of the robot arm 201 will be described as a representative example, and the other joints J2 and J3 may differ in size and performance, but have the same configuration, so description thereof will be omitted.

[0083] FIG. 10 is a partial cross-sectional view showing a joint J1 of a robot arm 201 according to this embodiment. The drive device 230 includes an electric motor 141 serving as a rotational drive source, a reducer 143 connected to a rotating shaft 142 of the motor 141 and transmitting the rotation of the rotating shaft 142 to the sensor 500 after reducing the speed, and the sensor 500 disposed on the output side of the reducer 143. The rotating shaft 142 of the motor 141 rotates around a rotation axis C0. The link 210 and the link 211 are rotatably connected via a cross roller bearing 147. The motor 141 is a servomotor, such as a brushless DC servomotor or an AC servomotor. The motor 141 generates heat, and the temperature of the motor 141 can reach, for example, 90°C or higher. The heat generated by the motor 141 increases the temperature around the sensor 500, which in turn increases the temperature of the adhesive 11 that bonds the support portion 501 and the detection head 7, potentially loosening the adhesive 11.

[0084] In particular, the adhesive 11 is likely to loosen when the temperature of the adhesive 11 becomes higher than the glass transition point of the adhesive 11. The glass transition point of the adhesive 11 is, for example, 40 to 80°C.

[0085] Therefore, when the motor 141 is driven, if the temperature of the motor 141 becomes higher than the glass transition point of the adhesive, the adhesive 11 is likely to become loose.

[0086] The shorter the distance between sensor 500 and motor 141, for example, within 3 cm, the more likely the temperature around sensor 500 will increase due to heat emitted from motor 141.

[0087] In this embodiment, the reducer 143 is a wave gear reducer. The reducer 143 includes a web generator 151, which is an example of an input shaft, connected to the rotating shaft 142 of the motor 141, and a circular spline 152, which is an example of an output shaft, fixed to a link 211. Note that although the circular spline 152 is connected to the link 211, it may be formed integrally with the link 211.

[0088] The reducer 143 also includes a flexspline 153 that is disposed between the web generator 151 and the circular spline 152 and is connected to the link 210 via a sensor 500. The flexspline 153 is formed in a cup shape. The flexspline 153 is flexibly deformed into an elliptical shape by the web generator 151, and meshes with the circular spline 152 at the major axis of the elliptical shape. When the web generator 151 rotates, the major axis of the elliptical shape of the flexspline 153 rotates, and the meshing position between the flexspline 153 and the circular spline 152 moves in the rotational direction of the web generator 151. When the web generator 151 rotates once, the circular spline 152 rotates relative to the flexspline 153 by an amount equal to the difference in the number of teeth between the flexspline 153 and the circular spline 152.

[0089] As a result, the circular spline 152 is decelerated at a predetermined reduction ratio with respect to the rotation of the web generator 151, and rotates relatively to the flexspline 153. Therefore, the link 211 to which the circular spline 152 is connected rotates about the rotation axis C0 relative to the link 210 to which the flexspline 153 is connected via the sensor 500.

[0090] The sensor 500 is disposed on the flexspline 153 on the output side of the reducer 143. That is, the sensor 500 is disposed between the link 210 and the flexspline 153 of the reducer 143, that is, between the link 210, which is an example of a first link, and the link 211, which is an example of a second link. The sensor 500 measures the torque about the rotation axis C0 acting between the link 210 and the link 211, and outputs an electric signal (digital signal) corresponding to the torque value τ, which is the measured value, to the control unit 300. The control unit 300 controls the robot 200 based on the torque value.

[0091] 11 is a block diagram showing a control system for the joint J1 of the robot arm 201 in this embodiment. The driving device 230 has a driving control device 260 electrically connected to the motor 141 and the control unit 300. The sensor 500 of the driving device 230 is electrically connected to the control unit 300.

[0092] The control unit 300 controls the entire robot system. That is, the control unit 300 controls the operation of the robot 200. The control of the operation of the robot 200 includes position control and force control.

[0093] During position control, the control unit 300 generates an operation command based on the position of the hand of the robot 200 and outputs the generated operation command to the drive control device 260. During force control, the control unit 300 generates an operation command based on a torque value τ that is a measurement value from the sensor 500 and outputs the generated operation command to the drive control device 260. The drive control device 260 controls the energization of the motor 141 in accordance with the operation command to drive the motor 141.

[0094] During force control, the control unit 300 operates the robot 200 based on the torque value τ that is the output of the sensor 500. Therefore, the force control performance of the robot 200 depends on the accuracy of the sensor 500, that is, the resolution.

[0095] Next, a method for controlling the robot 200 will be described.

[0096] When the robot 200 operates, the control unit 300 controls the robot 200 so that the robot 200 operates according to trajectory data corresponding to a robot program including teaching data. At this time, the control unit 300 supplies a drive current to the motor 141 of each of the joints J1 to J3 to drive each of the joints J1 to J3. Each of the joints J1 to J3 may or may not be in a state where an external torque load is applied thereto.

[0097] After the robot 200 starts operating, the displacement calculation unit 680 detects a phase Φ1 that indicates the amount of displacement in the X direction from the pattern 810. That is, the displacement calculation unit 680 uses the sine wave signals S(A) and S(B) from the circuit unit 51 to determine the amount of displacement in the X direction of the scale 2 relative to the detection head 7 as the phase Φ1.

[0098] Based on the detection result, the control unit 300 acquires the torque value τ from the sensor 500 while controlling the robot 200 .

[0099] The phase Φ1 is calculated from the following equation (3) using equations (1) and (2). Φ1=ATAN2[S(A),S(B)] (3)

[0100] ATAN2[Y,X] is an arctangent calculation function that determines the quadrant and converts it into a phase between 0 and 2π.

[0101] Before calculating equation (3), the gain ratio and offset error included in the sine wave signals S(A) and S(B) due to the offset and gain variation of each amplifier may be corrected using a correction value calculated in advance. For example, for each of the sine wave signals S(A) and S(B), the gain ratio, i.e., the amplitude ratio, may be calculated from (maximum value - minimum value) / 2, and a correction value may be calculated to equalize the signal amplitudes. Similarly, the amount of offset error may be calculated from (maximum value + minimum value) / 2, and a correction value for correcting the offset error may be calculated. These correction values ​​may be stored in the storage device 670.

[0102] As described above, the displacement calculation section 680 obtains the phase Φ1 from the sine wave signals S(A) and S(B).

[0103] The torque calculation unit 681 then calculates the torque value τ based on the four phases Φ1 calculated for each of the four encoders 510. For example, the torque calculation unit 681 calculates the torque value τ by averaging the four phases Φ1 and multiplying the average value by a predetermined coefficient, for example, a sensitivity coefficient proportional to the elastic coefficient of the elastic unit 503. Note that the method of calculating the torque value τ is not limited to this, and the torque value τ may be calculated by converting each phase Φ1 into a provisional torque value and averaging the four provisional torque values. The displacement calculation unit 680 outputs the calculated torque value τ to the control unit 300.

[0104] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0105] The sensor 500 of this embodiment can be applied not only to industrial equipment such as robots, but also to transportation equipment such as automobiles, electronic devices such as cameras, office equipment such as printers, medical equipment such as CT scans, industrial equipment such as exposure devices, assistive devices such as prosthetic limbs and power-assisted suits, etc. In these devices, the mechanical devices can be controlled by a control device based on the signal detected by the sensor 500.

[0106] In the above-described embodiment, a torque sensor has been described as an example of the sensor 500, but the sensor 500 is not limited to a torque sensor. For example, if the sensor is a device (sensor) that detects displacement, such as a displacement detector, potentiometer, or strain gauge, the application of the present invention can suppress a decrease in the accuracy of the sensor.

[0107] The above-described embodiment can be modified as appropriate within the scope of the technical concept.

[0108] For example, a plurality of embodiments may be combined, and some details of at least one embodiment may be deleted or replaced.

[0109] Furthermore, new matters may be added to at least one embodiment. The disclosure of this specification includes not only what is explicitly described in this specification, but also all matters that can be understood from this specification and the drawings attached hereto.

[0110] Furthermore, the disclosure of this specification includes the complement of each individual concept described in this specification. In other words, if this specification contains a statement that "A is greater than B," for example, it can be said that this specification discloses "A is not greater than B," even if it omits the statement that "A is not greater than B." This is because when a statement that "A is greater than B" is made, it is assumed that the case in which "A is not greater than B" is taken into consideration. [Explanation of symbols]

[0111] C0 axis of rotation 2. Scale 7 Detector head 401 Connection section 402 Connection part 500 sensors 501 1st support part 502 Second support part 503 Elastic part

Claims

1. a first support portion and a second support portion facing the first support portion; a plurality of elastic portions connecting the first support portion and the second support portion; a sensor that detects rotation of the second support portion relative to the first support portion by an encoder including a scale and a detection head facing the scale, The elastic portions are arranged side by side on a circle having a center that coincides with the center of rotation. a first connecting portion provided between the first support portion and the elastic portion, and a second connecting portion provided between the second support portion and the elastic portion, the scale is fixed to the first support portion, and the detection head is fixed to the second support portion; The sensor is characterized in that the scale and the detection head are arranged side by side in the radial direction of the rotation.

2. The sensor according to claim 1 , wherein the first connecting portion and the second connecting portion are integrally formed with the elastic portion.

3. 3. The sensor according to claim 1, wherein the first connecting portion, the second connecting portion, and the elastic portion are made of a single material.

4. 4. The sensor according to claim 1, wherein the plurality of elastic portions connect the first connecting portion and the second connecting portion in the axial direction of the rotation.

5. 5. The sensor according to claim 1, wherein one of the scale and the detection head is adhered to the first support portion, and the other of the scale and the detection head is adhered to the second support portion.

6. The sensor according to claim 1 , wherein the plurality of elastic portions are arranged on an outer periphery of the sensor.

7. 5. The sensor according to claim 1, wherein one of the scale and the detection head fixed to the first support portion has a surface opposite to a surface on the side of the axis of rotation, and the surface is positioned at a position away from the center of rotation by a distance R from the center of rotation to an end of the first coupling portion in the radial direction of rotation.

8. 8. The sensor according to claim 7, wherein the other of the scale and the detection head fixed to the second support portion is disposed at a distance closer than the distance R.

9. 9. The sensor according to claim 7, wherein the first connecting portion, the second connecting portion, and the elastic portion are made of sheet metal.

10. 10. The sensor according to claim 9, wherein the metal plate is a plated metal plate.

11. 11. The sensor according to claim 1, wherein the scale has a pattern portion, and the detection head reads the pattern portion and outputs a detection signal.

12. 12. The sensor according to claim 1, wherein the distance between the detection head and the scale is 0.2 mm or more and 1.2 mm or less.

13. A first support portion and a second support portion facing the first support portion; a plurality of elastic portions connecting the first support portion and the second support portion; a scale fixed to the first support portion; and a detection head facing the scale and fixed to the second support portion, a sensor that detects rotation of the second support portion relative to the first support portion by the scale and the detection head, The plurality of elastic portions are arranged side by side in the circumferential direction of the rotation, a connecting portion between each of the plurality of elastic portions and the first support portion, and a connecting portion between each of the plurality of elastic portions and the second support portion are arranged along the rotation axis direction, the scale and the detection head are arranged side by side in the radial direction of the rotation, A sensor characterized in that a gap between the scale and the detection head is sealed by a sealant.

14. A mechanical device controlled based on a signal detected by a sensor described in any one of claims 1 to 13.

15. An apparatus comprising a sensor described in any one of claims 1 to 13, a mechanical device, and a control device that controls the mechanical device based on a signal output from the detection head.

16. The equipment described in claim 15 is a robot, and the manufacturing method is characterized in that the robot grasps a workpiece and manufactures an article.

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