Force sensor and fitting system

Abstract

To stably perform force control of a robot or the like by determining whether there is an abnormality in a force sensor.SOLUTION: A force sensor (10) comprises: a force-receiving body (14) that receives force or moment acting on a detection target portion (S); and a strain-generating body (16) which is provided in a sensor base (12) and acts as an elastic support supporting the force-receiving body (14). The force sensor (10) comprises: two systems of detection units (28 and 30) that independently detect strain of four beam portions 26 of the strain-generating body (16); two systems of arithmetic circuits (34 and 36) that independently calculate the force or moment acting on the detection target portion (S), based on detection results from the two systems of detection units (28 and 30); and two systems of output units (38 and 40) that independently output calculation results from the two systems of arithmetic circuits (34 and 36) as electric signals.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a force sensor that detects a force or moment acting on a site to be inspected, and a fitting system for fitting a fitting workpiece to a workpiece to be fitted.

Background Art

[0002] For example, a force sensor is used when performing force control of a robot. The force sensor includes a sensor base, a force receiving body that receives a force or moment acting on a detection target site such as the base of a robot hand, and an elastic support body that is provided on the sensor base and supports the force receiving body. The elastic support body has an elastic portion that is elastically deformable at least partially. The force sensor includes a strain gauge type detection unit that detects the strain of the elastic portion of the elastic support body, an arithmetic circuit that calculates the force or moment acting on the detection target site based on the detection result from the strain gauge type detection unit, and an output unit that outputs the calculation result from the arithmetic circuit as an electrical signal (see Patent Document 1).

[0003] Note that, instead of the strain gauge type detection unit, a capacitance type detection unit that electrically detects the displacement of the elastic portion of the elastic support body, or an optical type detection unit that optically detects the displacement of the elastic portion of the elastic support body is provided. Force sensors are also widely known (see Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a conventional force sensor, since the strain or displacement of the elastic part of the elastic support is detected by one detection unit and the force or moment acting on the detection target part is output as an electrical signal by one output unit, it is impossible to determine whether there is an abnormality (failure) in the force sensor. Therefore, for example, during the force control of a robot, even if an abnormality occurs in the force sensor, the state will continue, and there is a problem that stable force control of the robot or the like cannot be performed.

[0006] Therefore, one aspect of the present invention aims to determine the presence or absence of an abnormality in a force sensor and perform stable force control of a robot or the like.

Means for Solving the Problems

[0007] In order to solve the above problems, a force sensor according to one aspect of the present invention includes a sensor base, a force-receiving body that receives a force or moment acting on a detection target part, an elastic support provided on the sensor base and having an elastic part that can be elastically deformed at least partially, and that supports the force-receiving body, two detection units that independently detect the strain or displacement of the elastic part of the elastic support, two arithmetic circuits (two arithmetic circuits) that independently calculate the force or moment acting on the detection target part based on the detection results from the two detection units, and two output units (two output units) that independently output the calculation results from the two arithmetic circuits as electrical signals.

[0008] Also, in order to solve the above problems, a fitting system according to an aspect of the present invention includes a multi-joint arm, a robot having a hand provided on the tip side of the arm and gripping a fitting work, a force sensor disposed between the base of the hand and the tip of the arm for detecting a force or moment acting on the hand, a table device for supporting the work to be fitted so as to be able to change the posture of the work to be fitted, a robot controller for performing force control of the robot so as to adjust the posture of the fitting work based on the calculation result output from one of the two output parts of the force sensor when fitting the fitting work to the work to be fitted, and a table controller for performing force control of the table device so as to adjust the posture of the work to be fitted based on the calculation result output from the other of the two output parts of the force sensor when fitting the fitting work to the work to be fitted.

Effect of the Invention

[0009] According to one aspect of the present invention, it is possible to determine the presence or absence of an abnormality in the force sensor and stably perform force control of a robot or the like.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0011] Hereinafter, this embodiment will be described with reference to the drawings. As shown in the drawings, the direction of the central axis of the force sensor is referred to as the Z-axis direction, and the two directions orthogonal to the direction of the central axis of the force sensor are referred to as the X-axis direction and the Y-axis direction.

[0012] [Embodiment 1] Based on FIGS. 1 to 5, the configuration of the force sensor 10 according to Embodiment 1 will be described.

[0013] As shown in FIGS. 1 to 4, the force sensor 10 according to Embodiment 1 is a six-axis force sensor that detects the forces in each axial direction (X-axis direction, Y-axis direction, and Z-axis direction) and the moments around each axis (X-axis, Y-axis, and Z-axis) acting on the detection target site S. The force sensor 10 is disposed between the detection target site S and the opposing site T facing it. Note that the force sensor 10 is not limited to a six-axis force sensor, and may be a force sensor that detects a force in a predetermined axial direction or a moment around a predetermined axis.

[0014] (Sensor Base) The force sensor 10 includes a cylindrical sensor base 12, and the sensor base 12 is attached to the opposing site T. Two corner portions 12a and 12b are formed on both sides of the sensor base 12 in the X-axis direction.

[0015] (Force-receiving Body) On one side of the sensor base 12 in the Z-axis direction, a disk-shaped force-receiving body 14 that receives the force and moment acting on the detection target site S is provided, and the force-receiving body 14 is attached to the detection target site S. A slight gap C of about 1 mm in the Z-axis direction is formed between the force-receiving body 14 and the sensor base 12, and the force-receiving body 14 is allowed to move relative to the sensor base 12 according to the gap C.

[0016] (Strain body as elastic support) As shown in FIGS. 1 and 5, inside the sensor base 12, a strain body 16 as an elastic support for supporting the force-receiving body 14 is provided, and the strain body 16 is concentrically located with the force-receiving body 14. The strain body 16 has a disk-shaped core portion 18, and the core portion 18 is fixed to the force-receiving body 14 via a columnar connecting member 20. The strain body 16 has a ring portion 22 surrounding the core portion 18, and the ring portion 22 is fixed to the sensor base 12 via an annular spacer 24. The strain body 16 is provided with four beam portions 26 that connect to the outer peripheral surface of the core portion 18 and the inner peripheral surface of the ring portion 22, and the four beam portions 26 are arranged at equal intervals along the circumferential direction. The four beam portions 26 correspond to elastic portions that can be elastically deformed when the core portion 18 and the ring portion 22 are regarded as rigid bodies. Note that the number of the beam portions 26 is not limited to four and may be three or more.

[0017] (Two detection units) As shown in FIG. 5, each beam portion 26 is provided with a first detection unit 28 for detecting its distortion, and each first detection unit 28 has a plurality of strain gauges (not shown) respectively arranged on the front and back surfaces of each beam portion 26. Each beam portion 26 is provided with a second detection unit 30 for detecting its distortion independently of the first detection unit 28, and each second detection unit 30 has a plurality of strain gauges (not shown) respectively arranged on the front and back surfaces of each beam portion 26. That is, the strain generating body 16 as the elastic support is provided with two systems of strain gauge type detection units for independently detecting the distortions of the four beam portions 26 as the elastic portions. The four first detection units 28 constitute one system of strain gauge type detection unit for independently detecting the distortions of the four beam portions 26. The four second detection units 30 constitute the other system of strain gauge detection unit for independently detecting the distortions of the four beam portions 26.

[0018] Note that the force sensor 10 may be provided with two systems of capacitance type detection units (not shown) for electrically independently detecting the displacements of the four beam portions 26, or two systems of optical type detection units (not shown) for optically independently detecting the displacements of the four beam portions 26, instead of the two systems of strain gauge type detection units.

[0019] (Two systems of arithmetic circuits) As shown in Fig. 1, a substrate 32 for comprehensively controlling the detection operation of the force sensor 10 is disposed inside the sensor base 12. A first arithmetic circuit 34 having a processor (not shown) is mounted on the substrate 32. Based on the detection results from the four first detection units 28 that constitute one system of detection units, the first arithmetic circuit 34 calculates the force and moment acting on the detection target site S. A second arithmetic circuit 36 having a processor (not shown) is mounted on the substrate 32. Based on the detection results from the four second detection units 30 that constitute the other system of detection units, the second arithmetic circuit 36 calculates the force and moment acting on the detection target site S. In other words, the first arithmetic circuit 34 and the second arithmetic circuit 36 that constitute the two-system arithmetic circuit independently calculate the force and moment acting on the detection target site S based on the detection results from the two-system strain gauge type detection units. Since the specific arithmetic methods of the first arithmetic circuit 34 and the second arithmetic circuit 36 are well-known, the description thereof is omitted.

[0020] (Output units of two systems) As shown in Figs. 1 and 2, near one corner portion 12a of the sensor base 12, a first interface 38 as a first output unit for outputting the arithmetic result from the first arithmetic circuit 34 as an electric signal is provided. The first interface 38 is connected to the first arithmetic circuit 34. Near the other corner portion 12b of the sensor base 12, a second interface 40 as a second output unit for outputting the arithmetic result from the second arithmetic circuit 36 as an electric signal is provided. The second interface 40 is connected to the second arithmetic circuit 36. That is, the sensor base 12 is provided with two-system output units (the first interface 38 and the second interface 40) for independently outputting the arithmetic results from the two-system arithmetic circuits (the first arithmetic circuit 34 and the second arithmetic circuit 36) as electric signals.

[0021] (Operation and effect of Embodiment 1) The strain gauge type detection units of the 2 systems (the 4 first detection units 28 and the 4 second detection units 30) independently detect the strain of the 4 beam units 26. Then, the first arithmetic circuit 34 calculates the force and moment acting on the detection target site S based on the detection results from the 4 first detection units 28 that constitute the detection unit of one system. The second arithmetic circuit 36 calculates the force and moment acting on the detection target site S based on the detection results from the 4 second detection units 30 that constitute the detection unit of the other system. And the first interface 38 outputs the calculation result from the first arithmetic circuit 34 as an electrical signal, and the second interface 40 outputs the calculation result from the second arithmetic circuit 36 as an electrical signal.

[0022] Therefore, it is possible to determine whether or not the difference between the force and moment output from the first interface 38 and the force and moment output from the second interface 40 exceeds the threshold for abnormality determination. If it exceeds the threshold for abnormality determination, it is determined that there is an abnormality in the force sensor 10, and if it does not exceed the threshold for abnormality determination, it is determined that there is no abnormality in the force sensor 10. Here, the threshold for abnormality determination is a threshold for determining the presence or absence of an abnormality in the force sensor 10. The entity that determines whether or not it exceeds the threshold for abnormality determination is an external controller (not shown) electrically connected to the force sensor 10, but it may also be the force sensor 10 itself.

[0023] Therefore, according to the first embodiment, it is possible to determine the presence or absence of an abnormality in the force sensor 10 and stably perform force control of a robot or the like using the force sensor 10.

[0024] 〔Second Embodiment〕 Another embodiment of the present invention will be described with reference to FIGS. 6 to 8. For the sake of convenience of explanation, members having the same functions as the members described in the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0025] As shown in FIG. 6, the force sensor 42 according to Embodiment 2 is a six-axis force sensor that detects the forces in the respective axial directions (X-axis direction, Y-axis direction, and Z-axis direction) acting on the detection target site S and the moments around the respective axes (X-axis, Y-axis, and Z-axis). The force sensor 42 is disposed between the detection target site S and the opposing site T facing the detection target site S. The force sensor 42 has the same configuration as the force sensor 10 (see FIG. 1) except for a part thereof, and only the configuration different from that of the force sensor 10 will be described among the configurations of the force sensor 42. Note that the force sensor 42 is not limited to a six-axis force sensor, and may be a force sensor that detects a force in a predetermined axial direction or a moment around a predetermined axis.

[0026] (First strain body constituting the elastic support) As shown in FIGS. 6 and 7, the force sensor 42 includes, as an elastic support, a first strain body 44 and a second strain body 46 that overlap in the Z-axis direction, instead of the strain body 16 (see FIG. 5). The specific configurations of the first strain body 44 and the second strain body 46 are as follows.

[0027] A first strain body 44 that constitutes a part of the elastic support is provided in the sensor base 12, and the first strain body 44 is located concentrically with the force receiving body 14. The first strain body 44 has a disk-shaped first core portion 48, and the first core portion 48 is fixed to the force receiving body 14 via a columnar first connecting member 50 with respect to the force receiving body 14. The first strain body 44 has a first ring portion 52 that surrounds the first core portion 48, and the first ring portion 52 is fixed to the sensor base 12 via an annular first spacer 54. The first strain body 44 has four first beam portions 56 provided so as to connect the outer peripheral surface of the first core portion 48 and the inner peripheral surface of the first ring portion 52, and the four first beam portions 56 are arranged at equal intervals along the circumferential direction. The four first beam portions 56 correspond to elastic portions that can be elastically deformed when the first core portion 48 and the first ring portion 52 are regarded as rigid bodies. Note that the number of the first beam portions 56 is not limited to four, and may be three or more.

[0028] (Second strain body constituting the elastic support) As shown in FIGS. 6 and 8, a second strain generating body 46 that forms part of the elastic support is provided inside the sensor base 12. The second strain generating body 46 is concentric with and overlaps the first strain generating body 44. The second strain generating body 46 has a disk-shaped second core portion 58, and the second core portion 58 is fixed to the first core portion 48 of the first strain generating body 44 via a columnar second connecting member 60. The second strain generating body 46 has a second ring portion 62 surrounding the second core portion 58, and the second ring portion 62 is fixed to the sensor base 12 via an annular second spacer 64. The second strain generating body 46 is provided with four second beam portions 66 that connect to the outer peripheral surface of the second core portion 58 and the inner peripheral surface of the second ring portion 62, and the four second beam portions 66 are arranged at equal intervals along the circumferential direction. The four second beam portions 66 correspond to elastic portions that can be elastically deformed when the second core portion 58 and the second ring portion 62 are regarded as rigid bodies. The four second beam portions 66 are configured to generate a strain corresponding to the strain of the four first beam portions 56 when the force receiving body 14 receives a force and a moment. Note that the number of the second beam portions 66 is not limited to four, and may be three or more.

[0029] (Two systems of detection units) As shown in FIGS. 6 to 8, in the second embodiment, the first detection unit 28 is provided not on each beam portion 26 of the strain generating body 16 but on each first beam portion 56 of the first strain generating body 44. Each first detection unit 28 detects the strain of each first beam portion 56 of the first strain generating body 44. Each first detection unit 28 has a plurality of strain gauges (not shown) respectively arranged on the front and back surfaces of each first beam portion 56 of the first strain generating body 44. Further, the second detection unit 30 is provided not on each beam portion 26 of the strain generating body 16 but on each second beam portion 66 of the second strain generating body 46. Each second detection unit 30 detects the strain of each second beam portion 66 of the second strain generating body 46. Each second detection unit 30 has a plurality of strain gauges (not shown) respectively arranged on the front and back surfaces of each second beam portion 66 of the second strain generating body 46. That is, the elastic support (the first strain generating body 44 and the second strain generating body 46) is provided with two systems of strain gauge type detection units that independently detect the strain of the elastic portions (the four first beam portions 56 and the four second beam portions 66). One system of strain gauge type first detection unit detects the strain of the four first beam portions 56, and the other system of strain gauge type detection unit detects the strain of the four second beam portions 66.

[0030] Note that the force sensor 42 may include one system of capacitive detection unit (not shown) that electrically detects the displacement of the four first beam portions 56, or one system of optical detection unit (not shown) that optically detects the displacement of the four first beam portions 56, instead of one system of strain gauge type detection unit. The force sensor 42 may include the other system of capacitive detection unit (not shown) that electrically detects the displacement of the four second beam portions 66, or the other system of optical detection unit (not shown) that optically detects the displacement of the four second beam portions 66, instead of the other system of strain gauge type detection unit.

[0031] (Operation and Effect of the Second Embodiment) One strain gauge type detection unit (four first detection units 28) of one system detects the strain of the four first beam parts 56. The strain gauge type detection unit (four second detection units 30) of the other system detects the strain of the four second beam parts 66. Then, the first arithmetic circuit 34 calculates the force and moment acting on the detection target part S based on the detection results from the four first detection units 28 that constitute the detection unit of one system. The second arithmetic circuit 36 calculates the force and moment acting on the detection target part S based on the detection results from the four second detection units 30 that constitute the detection unit of the other system. And the first interface 38 outputs the calculation result from the first arithmetic circuit 34 as an electric signal, and the second interface 40 outputs the calculation result from the second arithmetic circuit 36 as an electric signal.

[0032] Therefore, it is possible to determine whether or not the difference between the force and moment output from the first interface 38 and the force and moment output from the second interface 40 exceeds the threshold for abnormality determination. When the threshold for abnormality determination is exceeded, it is determined that there is an abnormality in the force sensor 42, and when the threshold for abnormality determination is not exceeded, it is determined that there is no abnormality in the force sensor 42.

[0033] Therefore, according to the second embodiment, it is possible to determine the presence or absence of an abnormality in the force sensor 42 and stably perform force control of a robot or the like using the force sensor 42. In particular, even when permanent strain has occurred in either the first strain generating body 44 or the second strain generating body 46 which is a part of the elastic support, it can be determined that there is an abnormality in the force sensor 42, and force control of a robot or the like using the force sensor 42 can be performed more stably.

[0034] [Embodiment 3] Hereinafter, other embodiments of the present invention will be described with reference to FIGS. 9 and 10. For the sake of convenience of explanation, members having the same functions as the members described in Embodiment 1 and Embodiment 2 are denoted by the same reference numerals, and the description thereof will not be repeated.

[0035] (Outline of the fitting system) As shown in FIG. 9, the fitting system 68 according to Embodiment 3 is a system for fitting a convex workpiece WA as a fitting workpiece into a concave workpiece WB as a workpiece to be fitted. The specific configuration of the fitting system 68 is as follows.

[0036] (Robot) The fitting system 68 includes a robot 70 that mainly performs the fitting operation of the convex workpiece WA. The robot 70 includes an articulated arm 72 and a hand 74 provided at the tip of the arm 72 and gripping the convex workpiece WA.

[0037] (Force sensor) The fitting system 68 includes a force sensor 10 (or 42) that detects the force and moment acting on the hand 74. The force sensor 10 (or 42) has the above-described configuration and is disposed between the base of the hand 74 as the detection target site S (see FIG. 1) and the tip of the arm 72 as the opposing site T (see FIG. 1).

[0038] (Table device) The fitting system 68 includes a Stewart platform type table device 76 disposed in the vicinity of the robot 70 and assisting in performing the fitting operation of the convex workpiece WA. The table device 76 includes a support base 78 that supports the concave workpiece WB and a parallel link mechanism 80 that moves the support base 78 so as to be able to change the posture of the concave workpiece WB. In other words, the table device 76 supports the concave workpiece WB so as to be able to change the posture of the concave workpiece WB. Note that the table device 76 can be regarded as a second robot.

[0039] (Robot controller) The fitting system 68 includes a robot controller 82 that controls a robot 70, and the robot controller 82 is electrically connected to a first interface 38 in a force sensor 10 (or 42). The robot controller 82 has a memory (not shown) that stores a robot control program and the like for controlling the robot 70, and a microprocessor (not shown) that interprets and executes the robot control program.

[0040] Based on the robot control program, the robot controller 82 performs position control of the robot 70 so as to fit the convex workpiece WA into the concave workpiece WB. Further, when fitting the convex workpiece WA into the concave workpiece WB, the robot controller 82 performs force control of the robot 70 so as to adjust the posture and position of the convex workpiece WA based on the calculation result output from the first interface 38. In other words, when fitting the convex workpiece WA into the concave workpiece WB, the robot controller 82 performs force control of the robot 70 so that the force and torque output from the first interface 38 are reduced.

[0041] (Table controller) The fitting system 68 includes a table controller 84 that controls a table device 76, and the table controller 84 is electrically connected to a second interface 40 in a force sensor 10 (or 42). The table controller 84 has a memory (not shown) that stores a table control program and the like for controlling the table device 76, and a microprocessor (not shown) that interprets and executes the table control program.

[0042] When fitting the convex workpiece WA into the concave workpiece WB, the table controller 84 performs force control of the table device 76 so as to adjust the posture and position of the concave workpiece WB based on the calculation result output from the second interface 40. In other words, when fitting the convex workpiece WA into the concave workpiece WB, the table controller 84 performs force control of the table device 76 so that the force and torque output from the second interface 40 are reduced.

[0043] (Main Controller) The fitting system 68 includes a main controller (not shown) that comprehensively controls the entire system. The main controller is electrically connected to a first interface 38, a second interface 40, a robot controller 82, and a table controller 84. The main controller determines whether the difference between the force and moment output from the first interface 38 and the force and moment output from the second interface 40 exceeds a threshold for abnormality determination. When the threshold for abnormality determination is exceeded, the main controller determines that there is an abnormality in the force sensor 10 (or 42). When the threshold for abnormality determination is not exceeded, the main controller determines that there is no abnormality in the force sensor 10 (or 42).

[0044] (Operational Effects of Embodiment 3) As shown in FIGS. 9 and 10, the robot controller 82 controls the position of the robot 70 so that the hand 74 is positioned near the placement area of the convex workpiece WA from the original position. Next, the robot controller 82 controls the robot 70 so that the hand 74 grips the convex workpiece WA (step S101 in FIG. 10). Then, the robot controller 82 controls the robot 70 so that the hand 74 and the convex workpiece WA are positioned above the concave workpiece WB on the support base 78 (step S102 in FIG. 10). Thereby, the fitting operation of the convex workpiece WA is started (step S103 in FIG. 10), and the force control of the robot 70 and the table device 76 is turned on (step S104 in FIG. 10).

[0045] When fitting the convex workpiece WA into the concave workpiece WB, based on the calculation result output from the first interface 38, the robot controller 82 performs force control of the robot 70 to adjust the posture and position of the convex workpiece WA. Also, based on the calculation result output from the second interface 40, the table controller 84 performs force control of the table device 76 to adjust the posture and position of the concave workpiece WB. Then, while adjusting the postures and positions of the convex workpiece WA and the concave workpiece WB, the convex workpiece WA can be inserted into the concave workpiece WB (step S105 in FIG. 10).

[0046] And when the force in the Z-axis direction, which is one of the calculation results output from the first interface 38, exceeds the threshold for completion determination, the robot controller 82 determines that the insertion of the convex workpiece WA is completed (step S106 in FIG. 10). The threshold for completion determination is the threshold for determining whether the insertion operation of the convex workpiece WA is completed. Subsequently, the robot controller 82 controls the robot 70 so that the hand 74 holds the convex workpiece WA (step S107 in FIG. 10). Thereby, the force control of the robot 70 and the table device 76 is turned off (step S108 in FIG. 10).

[0047] Furthermore, the robot controller 82 controls the robot 70 so that the hand 74 is positioned above the convex workpiece WA and the table device 76 (step S109 in FIG. 10), thereby ending the fitting operation of the convex workpiece WA (step S110 in FIG. 10). The robot controller 82 performs position control of the robot 70 so that the hand 74 returns to the original position.

[0048] That is, according to the configuration of the third embodiment, as described above, when fitting the convex workpiece WA into the concave workpiece WB, the robot controller 82 performs force control of the robot 70 and the table controller 84 performs force control of the table device 76. Therefore, according to the third embodiment, compared with the case where only the robot 70 performs force control, the tact time can be reduced and the convex workpiece WA can be fitted into the concave workpiece WB in a short time.

[0049] 〔Summary〕 The force sensor according to Aspect 1 of the present invention includes a sensor base, a force-receiving body that receives a force or moment acting on a detection target site, an elastic support body that is provided on the sensor base and has an elastic portion that can be elastically deformed at least in part, and supports the force-receiving body, two systems of detection units that independently detect the strain or displacement of the elastic portion of the elastic support body, two systems of arithmetic circuits (two arithmetic circuits) that independently calculate the force or moment acting on the detection target site based on the detection results from the two systems of detection units, and two systems of output units (two output units) that independently output the calculation results from the two systems of arithmetic circuits as electrical signals.

[0050] According to the above configuration, the two systems of detection units independently detect the strain or displacement of the elastic portion of the elastic support body. Then, the two systems of arithmetic circuits independently calculate the force or moment acting on the detection target site based on the detection results from the two systems of detection units. And the two systems of output units independently output the calculation results from the two systems of arithmetic circuits as electrical signals. Therefore, it is possible to determine whether the difference between the force or moment output from one of the two systems of output units and the force or moment output from the other of the two systems of output units exceeds the threshold for abnormality determination. Thus, it is possible to determine the presence or absence of an abnormality in the force sensor and stably perform force control of a robot or the like using the force sensor.

[0051] The force sensor according to Aspect 2 of the present invention, in the above Aspect 1, the elastic support body is a strain-inducing body, and the strain-inducing body may include a core portion fixed to the force-receiving body, a ring portion fixed to the sensor base and surrounding the core portion, and a plurality of beam portions as the elastic portions provided to connect the outer peripheral surface of the core portion and the inner peripheral surface of the ring portion and arranged at equal intervals along the circumferential direction.

[0052] According to the above configuration, the two detection units detect the distortion or displacement of the plurality of beam units independently.

[0053] The force sensor according to Aspect 3 of the present invention, in the Aspect 1, the elastic support is composed of an overlapping first strain generating body and a second strain generating body, the first strain generating body includes a first core portion fixed to the force receiving body, a first ring portion fixed to the sensor base and surrounding the first core portion, and a plurality of first beam portions as the elastic portions provided so as to connect the outer peripheral surface of the first core portion and the inner peripheral surface of the first ring portion and arranged at equal intervals along the circumferential direction, the second strain generating body includes a second core portion fixed to the first core portion of the first strain generating body, a second ring portion fixed to the sensor base and surrounding the second core portion, and a plurality of second beam portions as the elastic portions provided so as to connect the outer peripheral surface of the second core portion and the inner peripheral surface of the second ring portion and arranged at equal intervals along the circumferential direction, one detection unit of the two detection units may detect the distortion or displacement of the plurality of first beam portions, and the other detection unit of the two detection units may detect the distortion or displacement of the plurality of second beam portions.

[0054] According to the above configuration, one detection unit of the two detection units detects the distortion or displacement of the plurality of first beam portions. The other detection unit of the two detection units detects the distortion or displacement of the plurality of second beam portions. Thereby, even when permanent distortion has occurred in either the first strain generating body or the second strain generating body, in other words, in a part of the elastic support, it can be determined that there is an abnormality in the force sensor.

[0055] The force sensor according to Aspect 4 of the present invention, in any one of the Aspects 1 to 3, the two detection units may be two strain gauge type detection units.

[0056] According to the above configuration, the two strain gauge type detection units independently detect the distortion of the elastic portion of the elastic support.

[0057] The fitting system according to aspect 5 of the present invention includes a multi-joint arm, a robot having a hand provided on the tip side of the arm and gripping a fitting workpiece, a force sensor according to any one of aspects 1 to 4 disposed between the base of the hand and the tip of the arm for detecting a force or moment acting on the hand, a table device for supporting the workpiece to be fitted so as to be able to change the posture of the workpiece to be fitted, a robot controller for performing force control of the robot so as to adjust the posture of the fitting workpiece based on the calculation result output from one of the two output parts of the force sensor when fitting the fitting workpiece to the workpiece to be fitted, and a table controller for performing force control of the table device so as to adjust the posture of the workpiece to be fitted based on the calculation result output from the other of the two output parts of the force sensor when fitting the fitting workpiece to the workpiece to be fitted.

[0058] According to the above configuration, when fitting the fitting workpiece to the workpiece to be fitted, the robot controller performs force control of the robot so as to adjust the posture of the workpiece to be fitted based on the calculation result output from one of the output parts. Also, the table controller performs force control of the table device so as to adjust the posture of the workpiece to be fitted based on the calculation result output from the other output part. Thereby, compared with the case of performing force control only by the robot, the tact time can be reduced and the fitting workpiece can be fitted to the workpiece to be fitted in a short time.

[0059] 〔Supplementary Notes〕 The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0060] 10 Force sensor 12 Sensor base 14 Force receiving body 16 Distorted body (elastic support) 18 Core part 22 Ring part 26 Beam part (elastic part) 28 First detection part (detection part of one system) 30 Second detection part (detection part of the other system) 32 Substrate 34 First arithmetic circuit (arithmetic circuit of one system) 36 Arithmetic circuit (arithmetic circuit of the other system) 38 First interface (first output part, output part of one system) 40 Second interface (second output part, output part of the other system) 42 Force sensor 44 First distorted body (elastic support) 46 Second distorted body (elastic support) 48 First core part 52 First ring part 56 First beam part (elastic part) 58 Second core part 62 Second ring part 68 Fitting system 70 Robot 72 Arm 74 Hand 76 Table device 78 Support stand 80 Parallel link mechanism 82 Robot controller 84 Table controller WA Convex workpiece (fitting workpiece) WB Concave workpiece (workpiece to be fitted)

Claims

1. A sensor base, a force-receiving body that receives a force or moment acting on a detection target site, an elastic support body that is provided on the sensor base and has an elastic portion that can be elastically deformed at least partially, and supports the force-receiving body, two systems of detection units that independently detect the strain or displacement of the elastic portion of the elastic support body, two systems of arithmetic circuits that independently calculate the force or moment acting on the detection target site based on the detection results from the two systems of detection units, two systems of output units that independently output the calculation results from the two systems of arithmetic circuits as electrical signals, and is provided with, the elastic support body is composed of an overlapping first strain-generating body and a second strain-generating body, the first strain-generating body is, a first core portion fixed to the force-receiving body, a first ring portion fixed to the sensor base and surrounding the first core portion, a plurality of first beam portions as the elastic portions provided so as to connect the outer peripheral surface of the first core portion and the inner peripheral surface of the first ring portion and arranged at equal intervals along the circumferential direction, and has, the second strain-generating body is, a second core portion fixed to the first core portion of the first strain-generating body, a second ring portion fixed to the sensor base and surrounding the second core portion, a plurality of second beam portions as the elastic portions provided so as to connect the outer peripheral surface of the second core portion and the inner peripheral surface of the second ring portion and arranged at equal intervals along the circumferential direction, and has, one system of the two systems of detection units detects the strain or displacement of the first beam portion, and the other system of the two systems of detection units detects the strain or displacement of the second beam portion. A force sensor characterized by that.

2. A sensor base, a force-receiving body that receives a force or moment acting on a detection target site, an elastic support body that is provided on the sensor base and has an elastic portion that can be elastically deformed at least partially, and supports the force-receiving body, a first detection unit and a second detection unit, which are two systems of detection units that independently detect the strain or displacement of the elastic portion of the elastic support body, two systems of arithmetic circuits that independently calculate the force or moment acting on the detection target site based on the detection results from the two systems of detection units, which are a first arithmetic circuit connected to the first detection unit and a second arithmetic circuit connected to the second detection unit, Two output units that independently output the operation results from the two systems of arithmetic circuits as electrical signals, including a first output unit that outputs the operation result from the first arithmetic circuit and a second output unit that outputs the operation result from the second arithmetic circuit. The first output unit is connected to a robot controller that performs force control of a first robot. The second output unit is connected to a robot controller that performs force control of a second robot. A force sensor characterized by this. **Claim 3** The elastic support is a strain generating body. The strain generating body A core part fixed to the force receiving body, A ring part fixed to the sensor base and surrounding the core part, The force sensor according to claim 2, further comprising a plurality of beam parts as the elastic parts provided to connect the outer peripheral surface of the core part and the inner peripheral surface of the ring part and arranged at equal intervals along the circumferential direction. **Claim 4** The elastic support consists of an overlapping first strain generating body and second strain generating body. The first strain generating body A first core part fixed to the force receiving body, A first ring part fixed to the sensor base and surrounding the first core part, A plurality of first beam parts as the elastic parts provided to connect the outer peripheral surface of the first core part and the inner peripheral surface of the first ring part and arranged at equal intervals along the circumferential direction. The second strain generating body A second core part fixed to the first core part of the first strain generating body, A second ring part fixed to the sensor base and surrounding the second core part, A plurality of second beam parts as the elastic parts provided to connect the outer peripheral surface of the second core part and the inner peripheral surface of the second ring part and arranged at equal intervals along the circumferential direction. The force sensor according to claim 2, wherein one of the two systems of detection parts detects the strain or displacement of the first beam part, and the other of the two systems of detection parts detects the strain or displacement of the second beam part. **Claim 5** The two systems of detection parts are two systems of strain gauge type detection parts. The force sensor according to any one of claims 1 to 4, characterized by this. **Claim 6** A multi-joint arm and a robot having a hand provided on the tip side of the arm and gripping a fitting work. The force sensor according to any one of claims 1 to 5, which is disposed between the base of the hand and the tip of the arm and detects a force or moment acting on the hand. A table device that supports the workpiece to be inserted so that the posture of the workpiece to be inserted can be changed. A robot controller that performs force control of the robot so as to adjust the posture of the mating workpiece based on the calculation result output from one of the two output units of the force sensor when the mating workpiece is inserted into the workpiece to be inserted. A table controller that performs force control of the table device so as to adjust the posture of the workpiece to be inserted based on the calculation result output from the other output unit of the two output units of the force sensor when the mating workpiece is inserted into the workpiece to be inserted, comprising: The table device functions as a robot. The table controller functions as a robot controller that performs force control of the table device that functions as a robot, and a fitting system characterized by this.

Images