Force Sensor

Abstract

This force sensor comprises: a first substrate, a second substrate and a third substrate that are arranged spaced apart in the plate thickness direction; a first connecting member that connects the first substrate and the second substrate so that the same are displaceable in the plate thickness direction; a second connecting member that connects the second substrate and the third substrate so that the same are displaceable in a direction orthogonal to the plate thickness direction; a first detection unit that detects relative displacement between the first substrate and the second substrate; and a second detection unit that is disposed in such a manner as to extend between the second substrate and the third substrate in the plate thickness direction, and that detects relative displacement between the second substrate and the third substrate. The second substrate has an area for mounting the second detection unit and an area other than the mounting area, where the area other than the mounting area protrudes toward the third substrate, forming a thick wall portion.

Description

[Technical Field]

[0001] The present disclosure relates to force sensors. [Background technology]

[0002] BACKGROUND ART Displacement detection type force sensors have been known in the past (see, for example, Patent Document 1). The force sensor comprises three substrate sections spaced apart from one another in the thickness direction, a detection section arranged between these substrate sections, and a force calculation section that calculates force components based on the detection values ​​from the detection sections.

[0003] The force calculation unit is composed of a processor mounted on a printed circuit board, and generates heat when powered on. In order to make the force sensor thinner, the board is made thin, so it is easily affected by changes in heat. For this reason, the force sensor is equipped with a buffer section that absorbs thermal deformation of the board through elastic deformation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6673979 Summary of the Invention [Problem to be solved by the invention]

[0005] The method of absorbing the thermal deformation of the substrate by the elastic deformation of the buffer section makes it difficult to sufficiently suppress deformation of the substrate due to a sudden or uneven temperature rise. Therefore, it is desirable to make the force sensor thinner while being able to accurately detect force even when the temperature rises suddenly. [Means for solving the problem]

[0006] One aspect of the present disclosure provides a mounting device comprising: a first substrate; a second substrate disposed at an interval in a thickness direction relative to the first substrate; a third substrate disposed at an interval in the thickness direction relative to the second substrate; a first connecting member connecting the first substrate and the second substrate so as to be displaceable in the thickness direction; a second connecting member connecting the second substrate and the third substrate so as to be displaceable in a direction perpendicular to the thickness direction; a first detection unit that detects relative displacement between the first substrate and the second substrate; and a second detection unit that is disposed between the second substrate and the third substrate and extends in the thickness direction, and detects relative displacement between the second substrate and the third substrate, wherein an area of ​​the second substrate other than an attachment area of ​​the second detection unit protrudes toward the third substrate beyond an attachment area of ​​the second detection unit. Increases heat capacity It is a force sensor with a thick portion. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a longitudinal sectional view showing a force sensor according to a first embodiment of the present disclosure. [Figure 2] 2 is a plan view illustrating an electrode plate provided on a second substrate of the force sensor of FIG. 1. FIG. [Figure 3] 2 is a schematic perspective view illustrating a first detection electrode provided between a first substrate and a second substrate of the force sensor of FIG. 1. FIG. [Figure 4] 2 is a longitudinal cross-sectional view illustrating a second detection electrode provided between a second substrate and a third substrate of the force sensor of FIG. 1. FIG. [Figure 5] FIG. 5 is a plan view illustrating the second detection electrode of FIG. 4. [Figure 6] 5 is a schematic diagram illustrating an electrode plate of the second detection electrode of FIG. 4. FIG. [Figure 7] 5 is a plan view illustrating the wiring of the cables of the second detection electrode of FIG. 4. FIG. [Figure 8] 1. FIG. 4 is a plan view showing a modified example of the second substrate of the force sensor of FIG. [Figure 9] FIG. 2 is a schematic vertical cross-sectional view showing a modified example of the force sensor of FIG. [Figure 10] FIG. 2 is a schematic vertical cross-sectional view showing another modified example of the force sensor of FIG. [Figure 11]FIG. 10 is a longitudinal sectional view showing a force sensor according to a second embodiment of the present disclosure. [Figure 12] 12 is a longitudinal sectional view illustrating a second detection electrode provided between the second substrate and the third substrate of the force sensor of FIG. 11. FIG. [Figure 13] 12 is a plan view illustrating the wiring of the cables of the second detection electrodes of the force sensor of FIG. 11. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] A force sensor 1 according to a first embodiment of the present disclosure will be described below with reference to the drawings. The force sensor 1 according to this embodiment is a six-axis force sensor that is placed, for example, between the robot's base B and an installation surface A such as a floor, and detects forces acting on the robot in three orthogonal axial directions and moments around the three axes.

[0009] 1, the force sensor 1 includes a first substrate 2, a second substrate 3 arranged parallel to and spaced apart from the first substrate 2 in the thickness direction, and a third substrate 4 arranged parallel to and spaced apart from the second substrate 3 in the thickness direction. Hereinafter, an axis passing through the centers of the first substrate 2, second substrate 3, and third substrate 4 and extending in the thickness direction will be referred to as a first axis O1, and the thickness direction will also be referred to as the direction of the first axis O1. FIG. 1 shows the PP cross section of FIG. 5.

[0010] The force sensor 1 also includes a first connecting member 5 that connects the first substrate 2 and the second substrate 3 so as to be displaceable in the direction of the first axis O1, and a second connecting member 6 that connects the second substrate 3 and the third substrate 4 so as to be displaceable in a direction perpendicular to the direction of the first axis O1. Specifically, as shown in FIG. 1, the force sensor 1 includes a relay member 8 to which the second substrate 3 is fixed, for example, by a bolt 7, and a frame-shaped base member 9 to which the third substrate 4 is fixed, for example, by a bolt 10.

[0011] The first substrate 2 is connected to the second substrate 3 by a first connecting member 5 via a relay member 8, for example. The second substrate 3 is connected to the base member 9 by a second connecting member 6 via a relay member 8, for example. As a result, the first substrate 2 and the second substrate 3 are indirectly connected by the first connecting member 5, and the second substrate 3 and the third substrate 4 are indirectly connected by the second connecting member 6.

[0012] The first connecting member 5 elastically deforms so that the first substrate 2 and the second substrate 3 relatively move in the direction of the first axis O1 and / or rotate about an axis along a plane perpendicular to the direction of the first axis O1 when an external force is applied to the force sensor 1. That is, the first connecting member 5 has low rigidity in the direction of the first axis O1 and sufficiently high rigidity in the direction perpendicular to the first axis O1.

[0013] When a force in the direction of the first axis O1 or a moment about an axis along a plane perpendicular to the direction of the first axis O1 acts on the first substrate 2, the first connecting member 5 is elastically deformed, changing the distance in the direction of the first axis O1 between the first substrate 2 and the second substrate 3. On the other hand, even if a force in a direction perpendicular to the first axis O1 or a moment about the first axis O1 acts on the first substrate 2, the first connecting member 5 is not elastically deformed and transmits the force or moment as is to the relay member 8.

[0014] Furthermore, the second connecting member 6 elastically deforms so that the second substrate 3 and the third substrate 4 relatively move in a direction perpendicular to the first axis O1 and / or rotate about the first axis O1 when an external force is applied to the force sensor 1. That is, the second connecting member 6 has low rigidity in the direction perpendicular to the first axis O1 and sufficiently high rigidity in the direction of the first axis O1.

[0015] When a force in a direction perpendicular to the first axis O1 or a moment about the first axis O1 acts on the first substrate 2, the second connecting member 6 is elastically deformed, and the second substrate 3 is displaced in a direction perpendicular to the first axis O1 relative to the third substrate 4. On the other hand, even if a force in the direction of the first axis O1 or a moment about an axis along a plane perpendicular to the first axis O1 acts on the first substrate 2, the second connecting member 6 is not elastically deformed, and no relative displacement occurs between the second substrate 3 and the third substrate 4.

[0016] The force sensor 1 also includes a first detection electrode (first detection unit) 11 between the first substrate 2 and the second substrate 3, which detects relative displacement between the first substrate 2 and the second substrate 3. The force sensor 1 also includes a second detection electrode (second detection unit) 12 between the second substrate 3 and the third substrate 4, which detects relative displacement between the second substrate 3 and the third substrate 4.

[0017] The first detection electrode 11 includes a flat electrode plate (first electrode plate) 13 fixed to the surface of the first substrate 2 facing the second substrate 3, and a flat electrode plate (first electrode plate) 14 fixed to the surface of the second substrate 3 facing the first substrate 2. The electrode plates 13 and 14 are formed, for example, from an FPC (Flexible Printed Circuit).

[0018] The electrode plates 13 and 14 are fixed directly to the surfaces of the first substrate 2 and the second substrate 3, respectively. As a result, the electrode plates 13 and 14 each extend along a plane perpendicular to the first axis O1, and are arranged in parallel and opposite positions with a small gap in the direction of the first axis O1.

[0019] In this disclosure, expressions such as "along" or "along" do not only mean strictly coinciding with or parallel to an object such as an axis or plane, but also mean a general directionality. For example, a direction along a certain axis or plane includes a direction that deviates from a direction that is strictly coinciding with or parallel to the direction represented by that axis or plane, for example, a direction that intersects at an angle of less than 45°.

[0020] 2 and 3, the electrode plates 13 and 14 each include a plurality of electrode pieces 13a and 14a. Each of the electrode pieces 13a and 14a has a sector shape with a central angle of 90°, for example. The electrode plates 13 and 14 each have a shape that forms a circle by combining four sector-shaped electrode pieces 13a and 14a.

[0021] The four fan-shaped electrode pieces 13a, 14a constituting each of the electrode plates 13, 14 are arranged opposite each other as shown in Fig. 3. This allows each of the four pairs of electrode pieces 13a, 14a to detect a change in capacitance value in response to a change in the gap between the electrode pieces 13a, 14a.

[0022] That is, the first detection electrode 11 can detect four capacitance values ​​that change according to the relative displacement in the first axis O1 direction between the first substrate 2 and the second substrate 3. Then, from the four acquired capacitance values, it is possible to calculate a force component in the first axis O1 direction, a moment component about a second axis O2 that is perpendicular to the first axis O1, and a moment component about a third axis O3 that is perpendicular to the first axis O1 and the second axis O2.

[0023] When the first detection electrode 11 is configured using multiple pairs of electrode pieces 13a, 14a, it is sufficient that the opposing electrode pieces 13a, 14a have the same shape. In other words, the shapes of the multiple electrode pieces 13a, 14a configuring each electrode plate 13, 14 do not have to be the same.

[0024] The second detection electrode 12 includes an electrode plate (second electrode plate) 15 fixed to the surface of the second substrate 3 facing the third substrate 4, and an electrode plate (second electrode plate) 16 fixed to the surface of the third substrate 4 facing the second substrate 3. As shown in FIG. 4, each of the electrode plates 15, 16 is, for example, a rectangular FPC, and is attached to the surface of a rectangular parallelepiped member 18. A ribbon-shaped FPC cable 17 extends from each of the electrode plates 15, 16. FIG. 4 shows a QQ cross section of FIG. 5.

[0025] 5 and 6, the electrode plates 15, 16 are fixed to the surfaces of the second substrate 3 and the third substrate 4 by rectangular parallelepiped members 18. As a result, the electrode plates 15, 16 extend along the first axis O1 direction and are arranged in parallel to and facing each other with a small gap in the circumferential direction around the first axis O1.

[0026] As described above, the electrode plates 15, 16 are attached to a rectangular parallelepiped member 18 having a predetermined size and extend along the first axis O1. Therefore, the second substrate 3 and the third substrate 4 need to be arranged with a gap in the first axis O1 direction of a distance D that is the size of the rectangular parallelepiped member 18 in the first axis O1 direction plus a small gap, as shown in Fig. 6 .

[0027] There are provided a plurality of pairs of each electrode plate 15, 16. For example, as shown in Fig. 5, four pairs of electrode plates 15, 16 facing each other are arranged in a cross shape at equal intervals of 90° around the first axis O1 in the circumferential direction.

[0028] That is, two pairs of electrode plates 15, 16 arranged on both sides of the first axis O1 (for example, left and right in FIG. 5) are arranged parallel to each other with a small gap in the direction of the second axis O2, and the other two pairs of electrode plates 15, 16 arranged on both sides of the first axis O1 (for example, top and bottom in FIG. 5) are arranged parallel to each other with a small gap in the direction of the third axis O3, and are arranged parallel to each other with a small gap in the direction of the third axis O3.

[0029] As a result, second detection electrode 12 can detect changes in the capacitance value of each of the four pairs of electrode plates 15, 16 that correspond to the gap between electrode plates 15, 16. That is, second detection electrode 12 can detect four capacitance values ​​that change in accordance with the relative displacement between second substrate 3 and third substrate 4 in a direction along a plane perpendicular to first axis O1. Then, from the four acquired capacitance values, it is possible to calculate a force component in the direction of second axis O2, a force component in the direction of third axis O3, and a moment component about first axis O1.

[0030] 5, in this embodiment, the second substrate 3 is formed in the shape of a square flat plate with rounded corners, and the electrode plates 15, 16 of the second detection electrode 12 are attached to an attachment region R1 in the center of the second substrate 3. The attachment region R1 is a substantially cross-shaped region that includes attachment positions for four pairs of electrode plates 15, 16 arranged in a cross shape.

[0031] An intermediate portion (thick portion) R2 and an outer frame portion (thick portion) R3, which are regions other than the mounting region R1 and surround the outside of the mounting region R1, are configured to be thicker than the mounting region R1. In this embodiment, the intermediate portion R2 and the outer frame portion R3, which are separated by a two-dot chain line in Figure 5, have the same plate thickness.

[0032] Specifically, the outer frame portion R3 is a frame-shaped region that extends around the entire periphery of the second substrate 3, and the intermediate portion R2 is a region that continues inside the outer frame portion R3 and is provided at the four corners of the second substrate 3. More specifically, the second substrate 3 has a thin mounting region R1 formed by cutting away the central portion of a metal flat plate having the thickness dimensions of the outer frame portion R3 and the intermediate portion R2 in the thickness direction.

[0033] An outer frame portion R3 is provided on the periphery of the second substrate 3, and has through holes 19 formed at the center of each side of the second substrate 3, which penetrate in the radial direction centered on the first axis O1. Electrode plates 15 and 16 of the second detection electrode 12 are arranged close to each other inside the outer frame portion R3. The detection sensitivity can be improved as the positions of the electrode plates 15 and 16 are moved farther away from the first axis O1, and therefore the electrode plates 15 and 16 are arranged close to the outer frame portion R3.

[0034] When the cable 17 connected to the electrode plates 15, 16 is an FPC cable, the cable 17 extends in one direction along the same plane as the electrode plates 15, 16, or in both directions across the electrode plates 15, 16. Therefore, if the outer frame portion R3 did not have through holes 19, the cable 17 extending from each electrode plate 15, 16 would have to be forcibly bent with a small radius of curvature in the narrow gap between the outer frame portion R3 and the cable 17. According to this embodiment, the provision of the through holes 19 ensures that the cable 17 extended toward the outer frame portion R3 can be bent with a large radius of curvature without difficulty, as shown in FIG. 7 .

[0035] A cut-out can be used instead of the through-hole 19 to ensure a space for smoothly bending the above-described cable 17. In this embodiment, by using the through-hole 19, the intermediate portions R2 on both sides of the through-hole 19 can be connected by the beam-shaped outer frame portion R3. This makes it possible to efficiently improve the rigidity of the second substrate 3.

[0036] 7, through holes 20 for fixing the second substrate 3 to the relay member 8 with bolts 7 are provided at the four corners of the outer frame portion R3 connected to the intermediate portion R2. By fixing the second substrate 3 to the relay member 8 in the outer frame portion R3, which has been made thicker and therefore has increased rigidity, the second substrate 3 can be firmly supported by the relay member 8.

[0037] The force sensor 1 according to this embodiment also includes a processor 21 that calculates force components in the three axial directions and moment components about the three axes of an applied external force based on detection values ​​detected by the first detection electrode 11 and the second detection electrode 12. As shown in Fig. 1, the processor 21 is mounted on a circuit board 22 and is fixed, for example, to the surface of the third substrate 4 opposite to the second substrate 3. The processor 21 serves as a heating element that generates heat when current is applied.

[0038] A flat plate (thermal influence mitigation member) 23 made of a material with high thermal conductivity such as an aluminum alloy or a material with high thermal insulation properties such as a resin is disposed at a distance in the direction of the first axis O1 between the third substrate 4 and the circuit board 22. As shown in FIG. 1 , the flat plate 23 is formed larger than the circuit board 22, and is disposed in a position where the entire circuit board 22 is hidden when viewed from any position on the third substrate 4.

[0039] Although not shown, electrode plates 13 and 14 of first detection electrode 11 and circuit board 22 are connected by cables that pass through through-holes that penetrate second substrate 3 and third substrate 4 in the thickness direction. Electrode plates 15 and 16 of second detection electrode 12 and circuit board 22 are also connected by cables that pass through through-holes that penetrate third substrate 4 in the thickness direction. The through-holes of third substrate 4 are also located in positions that are covered by flat plate 23 (for example, near the center of third substrate 4), which prevents heat from processor 21 from being transmitted to second substrate 3 through the through-holes.

[0040] The operation of the force sensor 1 according to this embodiment configured as above will be described below. To detect an external force and moment acting on a robot using the force sensor 1 according to this embodiment, for example, the third substrate 4 is fixed as the installation side, and the first substrate 2 is set as the side on which the external force acts.

[0041] That is, the third substrate 4 is fixed to the installation surface A of the robot, for example, the floor surface, directly or indirectly (for example, via a sensor base 24 and an adapter 25) as shown in Fig. 1. The first substrate 2 is fixed to the bottom surface of the base B of the robot directly or indirectly (for example, via an adapter 26) as shown in Fig. 1.

[0042] When an external force acts on the robot, the external force acts on the first substrate 2 (via the adapter 26) and displaces the first substrate 2. The force sensor 1 detects either a force component or a moment component depending on the direction in which the first substrate 2 is displaced.

[0043] First, a case where an external force acts to separate the first substrate 2 from the second substrate 3 in the direction of the first axis O1 will be described. In this case, the first connecting member 5 elastically deforms, and the first substrate 2 is displaced in the direction of the first axis O1 relative to the second substrate 3. When the capacitance values ​​between the four pairs of electrode pieces 13a, 14a of the first detection electrode 11 change uniformly, a force component in the direction of the first axis O1 is detected.

[0044] On the other hand, if the change in capacitance value between the four pairs of electrode pieces 13a, 14a of the first detection electrode 11 is uneven, a moment component around the second axis O2 or the third axis O3 is detected in addition to or instead of the force component in the direction of the first axis O1. That is, when a difference in capacitance occurs between two pairs of electrodes 13a, 14a on both sides of the second axis O2, a moment component about the second axis O2 is detected. Also, when a difference in capacitance occurs between two pairs of electrodes 13a, 14a on both sides of the third axis O3, a moment component about the third axis O3 is detected.

[0045] Next, a case where an external force acts on the second substrate 3 to move it relative to the third substrate 4 in a direction perpendicular to the first axis O1 will be described. In this case, the first connecting member 5 does not elastically deform, suppressing the relative movement between the first substrate 2 and the second substrate 3, and the second connecting member 6 elastically deforms, displacing the second substrate 3 in a direction perpendicular to the first axis O1 relative to the third substrate 4. When the capacitance values ​​between the four pairs of electrode plates 15, 16 of the second detection electrode 12 change uniformly, a moment component about the first axis O1 is detected.

[0046] On the other hand, when the changes in capacitance value between the four pairs of electrode plates 15, 16 of the second detection electrode 12 are unequal, a force component in at least one of the second axis O2 and third axis O3 directions is detected. That is, when a difference occurs in the capacitance value between two pairs of electrode plates 15, 16 spaced apart in the second axis O2 direction, a force component in the second axis O2 direction is detected. In this case, the changes in capacitance value between the two pairs of electrode plates 15, 16 spaced apart in the third axis O3 direction are the same.

[0047] Furthermore, when a difference occurs in the capacitance values ​​between two pairs of electrode plates 15, 16 spaced apart in the third axis O3 direction, a force component in the third axis O3 direction is detected. In this case, the change in capacitance values ​​between two pairs of electrode plates 15, 16 spaced apart in the second axis O2 direction is the same.

[0048] The capacitance values ​​detected by the first detection electrode 11 and the second detection electrode 12 are sent to the processor 21 on the circuit board 22. Then, the processor 21 operates to calculate the force components and moment components acting on the robot.

[0049] In this case, when the processor 21 is powered on, the processor 21 generates heat, which heats up the components inside the force sensor 1. The processor 21, which is the heat source, is usually arranged asymmetrically on the circuit board 22 as shown in FIG.

[0050] According to this embodiment, a flat plate 23 made of a material with high thermal conductivity is disposed between the circuit board 22 and the third board 4. In this case, the heat from the processor 21 is converted into an even distribution (heat equalization) by the flat plate 23 and then transferred to the third board 4 and the second board 3. Therefore, even if the processor 21 suddenly generates heat immediately after power is turned on, the third board 4 can be prevented from being unevenly heated.

[0051] If the third substrate 4 is heated unevenly, the displacement of the third substrate 4 will differ depending on the location, resulting in differences in the capacitance values ​​detected by the four pairs of second detection electrodes 12 and reduced detection accuracy. In this embodiment, uneven heating of the third substrate 4 can be prevented, thereby improving detection accuracy.

[0052] Furthermore, when a flat plate 23 made of a highly insulating material is disposed between the circuit board 22 and the third board 4, the propagation of heat from the processor 21 is blocked by the flat plate 23. Therefore, even if the processor 21 suddenly generates heat immediately after power is turned on, the third board 4 and the second board 3 can be prevented from being suddenly heated.

[0053] Furthermore, flat plate 23, which is made of a material with high thermal conductivity or high thermal insulation, is formed larger than circuit board 22 and is positioned so that circuit board 22 is entirely hidden when viewed from any position on third board 4. This allows flat plate 23 to block the transfer of radiant heat from processor 21, which is a heat source, to third board 4.

[0054] Furthermore, according to the force sensor 1 of this embodiment, the second substrate 3 is formed to be thicker than the mounting region R1 in regions R2 and R3 other than the mounting region R1 of the electrode plate 15. This increases the rigidity of the second substrate 3 and significantly increases the heat capacity of the second substrate 3 compared to when the entire second substrate 3 is a flat plate with the same thickness as the mounting region R1.

[0055] The second substrate 3 has a thick intermediate portion R2 and an outer frame portion R3 integral with the mounting region R1 in an area other than the cross-shaped mounting region R1 for mounting the second detection electrode 12. This allows the heat to be quickly dissipated to the thick intermediate portion R2 and the outer frame portion R3 even if the mounting region R1 is heated. As a result, thermal deformation of the mounting region R1 can be suppressed, and detection accuracy can be improved.

[0056] That is, even if the second substrate 3 is heated by heat generated by the processor 21, it is possible to suppress a temperature rise in the mounting region R1 and reduce thermal deformation (particularly thermal deformation in the plate thickness direction). In this case, according to the present embodiment, the second substrate 3 has the intermediate portion R2 and the outer frame portion R3 protruding from the surface of the mounting region R1 toward the third substrate 4 in order to form the intermediate portion R2 and the outer frame portion R3 thick.

[0057] A distance D is required between the second substrate 3 and the third substrate 4 to ensure a space for arranging the second detection electrode 12 so that it extends along the first axis O1. In this embodiment, the necessary space between the second substrate 3 and the third substrate 4 is utilized to make the middle portion R2 and the outer frame portion R3 of the second substrate 3 thick.

[0058] This makes it possible to increase the thickness of the second substrate 3 and increase the heat capacity without increasing the distance D between the second substrate 3 and the third substrate 4. In other words, there is an advantage that it is possible to suppress thermal deformation of the second substrate 3 and improve the detection accuracy of the capacitance value without increasing the overall height of the force sensor 1.

[0059] In the force sensor 1 according to this embodiment, the second substrate 3 has been exemplified as a square with rounded corners, but is not limited to this. It may be circular as shown in FIG. 8, or may have another shape. Furthermore, the force sensor 1 in which the third substrate 4 side is the fixed side and the force acts on the first substrate 2 side has been exemplified, but the reverse may also be true.

[0060] Furthermore, as shown in FIG. 1, the first substrate 2 is connected to the relay member 8 fixed to the second substrate 3 by the first connecting member 5, and the third substrate 4 is connected to the relay member 8 by the second connecting member 6, but this is not limited to this. 9, a configuration may be employed in which parallel first to third substrates 2 to 4 are connected to three annular first to third bridge sections 32 to 34 connected by a first support section 30 and a second support section 31. For example, the first bridge section 32 is an elastically deformable first connecting member, and the second support section 31 is an elastically deformable second connecting member.

[0061] In this force sensor 1 as well, the periphery of the second substrate 3 is made thick by protruding it toward the third substrate 4, thereby increasing the rigidity and heat capacity of the second substrate 3 while maintaining a small overall height of the force sensor 1. In the figure, the first substrate 2 is fixed to an adapter 26, and an external force from the robot is transmitted via the adapter 26.

[0062] 10, a housing 35 connected to the third substrate 4 on the opposite side of the second support 31 across the third bridge 34 may be fixed as the installation side. A housing 36 connected to the first substrate 2 on the opposite side of the first support 30 across the first bridge 32 may be fixed as the force acting side.

[0063] In this embodiment, the first detection unit 11 and the second detection unit 12 are configured with electrodes and detect capacitance values, respectively. Alternatively, the first detection unit 11 and the second detection unit 12 may detect changes in the amount of charge, inductance, light amount, ultrasonic waves, magnetism, or the like.

[0064] Furthermore, in this embodiment, the force sensor 1 is exemplified as being installed between the base B of the robot and an installation surface A such as a floor. Instead, the force sensor 1 according to this embodiment may be installed in another location on the robot, for example, between the tip of the wrist and a tool.

[0065] Next, a force sensor 40 according to a second embodiment of the present disclosure will be described below with reference to the drawings. In the description of this embodiment, parts having the same configuration as the force sensor 1 according to the first embodiment described above will be assigned the same reference numerals and description thereof will be omitted. As shown in FIGS. 11 to 13, the force sensor 40 according to this embodiment includes two pairs of electrode plates 15, 16 at four locations, each pair of which has a second detection electrode 12 that detects the same displacement.

[0066] 12 and 13, the second detection electrode 12 includes two pairs of electrode plates 15, 16 at four locations equally spaced apart in the circumferential direction around the first axis O1. This allows redundancy in the detection of forces and moments by the force sensor 40, and even if a problem occurs in one of the two pairs of electrode plates 15, 16, the other pair can maintain detection accuracy.

[0067] 11 and 12, in the force sensor 40 according to this embodiment, the thickness of the intermediate portion R2 of the second substrate 3 is smaller than the thickness of the outer frame portion R3. As a result, a step corresponding to the difference in thickness is formed between the intermediate portion R2 and the outer frame portion R3. The step is formed to be larger than the thickness of the cable 17.

[0068] 11, by forming the intermediate portion R2 and the outer frame portion R3 of the second substrate 3 to be thick, the outer frame portion R3 and the intermediate portion R2 are close to the surface of the opposing base member 9. By providing a step between the outer frame portion R3 and the intermediate portion R2, it is possible to increase the gap between the intermediate portion R2 and the base member 9 in the direction of the first axis O1.

[0069] According to this embodiment, as shown in Fig. 13, the cable 17 can be routed by utilizing the gap widened by the step between the outer frame portion R3 and the middle portion R2. That is, when the cable 17 is an FPC cable, as shown in Fig. 13, the cable 17 can be twisted by 90 degrees and laid along the surface of the middle portion R2.

[0070] Since two pairs of electrode plates 15, 16 are arranged in one location, the number of cables 17 extending from each of the electrode plates 15, 16 is greater than that of the force sensor 1 of the first embodiment. In this case, if two cables 17 connecting two pairs of circumferentially adjacent electrode plates 15, 16 are routed along the same route, the two cables 17 may come close to or into contact with each other, causing crosstalk and reducing detection accuracy.

[0071] According to this embodiment, one cable 17a can be routed to a position that crosses the intermediate portion R2, as shown in the upper left of Fig. 13. This has the advantage of ensuring a sufficient distance between one cable 17a and the other cable 17b, preventing a decrease in detection accuracy.

[0072] In addition, in the present embodiment, the electrode plates 13 and 14 and the cables 17a and 17b are configured by FPCs, but this is not limiting. For example, the electrode plates 13 and 14 may be configured by metal plates or may be formed by film deposition. Furthermore, the cables 17a and 17b may be electric wires with an electrically insulating coating.

[0073] Although the embodiments of the present disclosure have been described in detail, the present disclosure is not limited to the individual embodiments described above. These embodiments can be variously added, replaced, modified, partially deleted, etc., without departing from the gist of the invention or the concept and spirit of the present invention derived from the content of the claims and their equivalents. For example, in the above-described embodiments, the order of each operation, the order of each process, the omission or addition of some operations depending on conditions, and the omission or addition of some processes depending on conditions can be changed without being bound by the above examples. The same applies when numerical values ​​or mathematical expressions are used in the description of the above embodiments. [Explanation of symbols]

[0074] 1,40 Force sensor 2 First board 3 Second board 4 Third board 5 First connecting member 6 Second connecting member 11 First detection electrode (first detection unit) 12 Second detection electrode (second detection unit) 13,14 Electrode plate (1st electrode plate) 15,16 Electrode plate (second electrode plate) 17, 17a, 17b cables 19 Through hole 21 processors 23 Flat plate (heat mitigation material) 31 second support portion (second connecting member) 32 First bridge section (first connecting member) R1 mounting area R2 middle part (thick wall part) R3 Outer frame (thick part) O1 Axis 1 O2 second axis O3 third axis

Claims

1. a first substrate; a second substrate disposed at an interval in a thickness direction relative to the first substrate; a third substrate disposed at an interval from the second substrate in the plate thickness direction; a first connecting member that connects the first substrate and the second substrate so as to be displaceable in the plate thickness direction; a second connecting member that connects the second substrate and the third substrate so as to be displaceable in a direction perpendicular to the plate thickness direction; a first detection unit that detects a relative displacement between the first substrate and the second substrate; a second detection unit disposed between the second substrate and the third substrate and extending in the plate thickness direction, and configured to detect a relative displacement between the second substrate and the third substrate; A force sensor in which the second substrate has a thick portion that protrudes toward the third substrate in an area other than the mounting area of ​​the second detection unit, thereby increasing the heat capacity, and the thick portion has a thickness that is greater in a direction perpendicular to the plate thickness direction than in the plate thickness direction.

2. the first detection unit detects a value that changes in accordance with at least one of a relative movement along a first axis that is a central axis extending in the thickness direction of the first substrate and the second substrate, and a relative rotation between the first substrate and the second substrate around a second axis that is perpendicular to the first axis and a third axis that is perpendicular to the first axis and the second axis; 2. The force sensor according to claim 1, wherein the second detection unit detects a value that changes in accordance with at least one of the relative movement between the second substrate and the third substrate along a plane perpendicular to the first axis and the relative rotation between the second substrate and the third substrate about the first axis.

3. the first detection unit includes flat first electrode plates fixed to the mutually opposing surfaces of the first substrate and the second substrate, respectively, and extending in a direction perpendicular to the plate thickness direction; The force sensor according to claim 2 , wherein the second detection portion comprises flat second electrode plates fixed to mutually opposing surfaces of the second substrate and the third substrate, respectively, and extending in the thickness direction.

4. Four pairs of the second electrode plates are provided, 4. The force sensor according to claim 3, wherein the second electrode plates extend in a radial direction about the first axis and are arranged in a cross shape at positions that are 90° apart in a circumferential direction about the first axis.

5. The force sensor according to claim 4 , wherein the thick portion has an intermediate portion sandwiched in the circumferential direction between the second electrode plates adjacent in the circumferential direction.

6. The force sensor according to claim 5 , wherein the thick portion comprises an outer frame portion provided around the entire periphery of the second substrate.

7. 7. The force sensor according to claim 6, wherein the thickness of the intermediate portion is smaller than the thickness of the outer frame portion.

8. a cable connecting the second electrode plates adjacent in the circumferential direction, 8. The force sensor according to claim 7, wherein a step formed by a difference in thickness between the outer frame portion and the intermediate portion is larger than a thickness of the cable.

9. The force sensor according to claim 6 , wherein a through hole penetrating in the radial direction is provided in the outer frame portion adjacent to the radially outer side of each of the second electrode plates.

10. a processor that calculates a force or a moment based on the detection values ​​detected by the first detection unit and the second detection unit, the processor is disposed on the third substrate opposite the second substrate; 10. The force sensor according to claim 1, further comprising a heat influence mitigation portion disposed between the processor and the third substrate, the heat influence mitigation portion mitigating the transfer of heat from the processor to the third substrate.

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