Rotating shaft structure with force sensor and robot

Abstract

The rotation axis structure includes: an actuator having an output shaft for driving a driven body to rotate; a force sensor disposed between the output shaft and the driven body for detecting a force acting between the output shaft and the driven body; and a soft deformable body that contacts the output shaft and the driven body, wherein the entire force sensor is sealed by the output shaft, the driven body, and the soft deformable body.

Description

Technical Field

[0001] The present invention relates to a rotating shaft structure and a robot, and more particularly to a rotating shaft structure and a robot having a force sensor. Background Art

[0002] Generally, in high-performance collaborative robots, in most cases, a force sensor capable of highly sensitively detecting force is assembled into a joint portion to instantaneously detect the contact force with a human, and the robot is safely stopped according to a small contact force, or when directly teaching (direct teach) the position and posture of the robot by directly holding the robot mechanism portion by a human, it is possible to lead through with a light force.

[0003] At the same time, in a collaborative robot, a structure is sought in which a line body for driving the robot is disposed inside the robot mechanism portion so as not to be exposed to the outside of the robot mechanism portion to prevent the line body from being wound around a human. Generally, it is desirable that the line body is not constrained near the joint portion and is in a free state to prevent the line body from being cut due to the rotational movement of the joint portion and causing a disconnection. In addition, by not constraining the line body, the force for returning the line body to its original state does not easily act on the force sensor, which helps to improve the detection accuracy of the force sensor.

[0004] However, generally, robots are mostly used in harsh environments where a large amount of foreign substances such as dust, debris, water, and oil are present. Therefore, sometimes the force sensor itself is corroded by foreign substances and cannot maintain the detection accuracy, or foreign substances invade the inside of the force sensor and cause a force sensor failure, or the line body passing through the through portion inside the force sensor bites into foreign substances. Therefore, a joint structure that does not allow foreign substances to invade is required. As a technology related to such a rotating shaft structure, the technology described later is well known.

[0005] Patent Document 1 describes a robot having a joint portion that connects a first frame and a second frame. In this robot, a wiring for driving the robot, an input portion of a torque sensor, and an output portion of the torque sensor are fixed to the first frame by a fixing member, thereby suppressing the influence of interference torque generated by the wiring.

[0006] Patent Document 2 describes a rotating shaft module in which both ends of a line body that penetrates and extends inside an actuator are respectively connected to a relay portion (for example, a connector), thereby facilitating the assembly and reorganization of the robot.

[0007] Patent Document 3 describes the following: In a torque sensor formed by connecting a first structure and a second structure using an elastic connecting member, a detection unit for detecting the relative movement amount between the first structure and the second structure includes a detection portion fixed to either the first structure or the second structure, a detected portion fixed to the other of the first structure and the second structure, and a sealing member that seals the space facing each other between the detection portion and the detected portion.

[0008] Patent Document 4 describes the following: In a wheel bearing device incorporating a load sensor, the load sensor includes: a detected portion disposed on the outer ring of a constant velocity joint coupled to an internal member; and a detection portion disposed opposite the detected portion on an external member, and the load applied to the wheel bearing is detected by detecting changes in the detected portion. Here, the waterproof property of a U-shaped cutout for disposing a cable led out from the detection portion is improved by overlapping a part of a sealing metal ring on the U-shaped cutout.

[0009] Patent Document 5 describes the following: In a power steering device including a torque sensor, there are provided: a housing through which a rotating shaft for transmitting a steering torque passes; a torque sensor having a sensor sleeve mounted on the outer peripheral surface of the rotating shaft; and a sealing member disposed between the outer peripheral surface of the sensor sleeve and the inner peripheral surface of the housing. The sealing member has: a main body portion press-fitted onto the outer peripheral surface of the sensor sleeve; a first rib portion protruding radially outward from the main body portion and abutting against the inner peripheral surface of the housing; and a second rib portion protruding axially toward the torque input side from the main body portion and abutting against a vertical surface of the housing.

[0010] Prior Art Documents

[0011] Patent Documents

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-159397

[0013] Patent Document 2: Japanese Patent Application Laid-Open No. 2015-123570

[0014] Patent Document 3: Japanese Patent Application Laid-Open No. 2019-90718

[0015] Patent Document 4: Japanese Patent Application Laid-Open No. 2005-321291

[0016] Patent Document 5: Japanese Patent Application Laid-Open No. 2015-155291 Summary of the Invention

[0017] Problems to be Solved by the Invention

[0018] To prevent foreign objects from entering, it is also possible to consider a method of covering the force sensor with a cover and inserting a seal between the covers and then tightening them with bolts. However, when using these sealing members to seal the force sensor itself, the outer diameter and thickness of the force sensor increase, which in turn makes the rotating shaft structure larger and heavier. At the same time, there is also a case where the sealing member affects the detection performance of the force sensor. On the other hand, the more the number of wire bodies passing through the inside of the robotic arm, the more likely the wire bodies will be cut due to the rotational movement and break, or the force (reaction force) that returns the wire bodies to their original state when performing the rotational movement becomes larger. Therefore, there is also a case where the wire bodies affect the detection performance of the force sensor.

[0019] Therefore, a rotating shaft structure that stabilizes or improves the detection accuracy of the force sensor is sought.

[0020] Solution to the problem

[0021] One aspect of the present disclosure provides a rotating shaft structure including: an actuator having an output shaft for driving a driven body to rotate; and a force sensor disposed between the output shaft and the driven body for detecting a force acting between the output shaft and the driven body. The rotating shaft structure further includes a flexible deformable body that contacts the output shaft and the driven body, and the entire force sensor is sealed by the output shaft, the driven body, and the flexible deformable body.

[0022] Another aspect of the present disclosure provides a rotating shaft structure including: an actuator having an output shaft for driving a driven body to rotate; a force sensor disposed between the output shaft and the driven body for detecting a force acting between the output shaft and the driven body; and a through hole that penetrates the actuator and the force sensor in the axial direction of the output shaft, and a wire body penetrates through the through hole. In the rotating shaft structure, the force sensor includes a communication substrate capable of serial communication or wireless communication, and the number of wire bodies penetrating through the through hole is reduced by the communication substrate.

[0023] Effects of the invention

[0024] According to one aspect of the present disclosure, the entire force sensor is sealed by the output shaft, the driven body, and the flexible deformable body. Therefore, not only corrosion, failure, or foreign object biting of the force sensor is prevented, but also since there is no need to provide a sealing member for the force sensor itself, the force sensor can be miniaturized and lightened, and thus a small and lightweight rotating shaft structure can be provided. At the same time, the flexible deformable body deforms softly in a manner that follows the strain of the force sensor without generating a reaction force. Therefore, it does not affect the detection accuracy of the force sensor. That is, a rotating shaft structure that stabilizes or improves the detection accuracy of the force sensor can be provided.

[0025] According to other aspects of the present disclosure, by providing a communication substrate capable of serial communication or wireless communication through a force sensor, the number of wire bodies passing through the through holes is reduced, so that the possibility of disconnection of the wire bodies occurring during the rotation operation can be reduced, and the reaction force for restoring the wire bodies to the original state during the rotation operation can be suppressed. That is, a rotation shaft structure capable of stabilizing or improving the detection accuracy of the force sensor can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a cross-sectional view showing a rotation shaft structure in one embodiment.

[0027] Figure 2 is a perspective view showing details of the force sensor.

[0028] Figure 3 is a cross-sectional view showing a rotation shaft structure in other embodiments.

[0029] Figure 4 is an enlarged cross-sectional view showing a soft deformable body having a slack.

[0030] Figure 5 is an enlarged cross-sectional view showing another deformation example of the soft deformable body.

[0031] Figure 6 is an enlarged cross-sectional view showing another deformation example of the soft deformable body.

[0032] Figure 7 is a block diagram showing an example of a robot for correcting the variation amount of the force sensor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar reference numerals are assigned to the same or similar components. In addition, the embodiments described below do not limit the technical scope and the meaning of the terms of the invention described in the claims.

[0034] Figure 1 A rotation shaft structure 1 in the present embodiment is shown. The rotation shaft structure 1 is, for example, a joint structure of a robot, but may also be a rotation shaft structure in other shaft-type machines such as machine tools, construction machines, and vehicles. The rotation shaft structure 1 is a structure that relatively rotates a driven body 11 with respect to a main body 10, and includes an actuator 20 for driving the driven body 11 to rotate and a force sensor 30 for detecting a force acting between the actuator 20 and the driven body 11.

[0035] The actuator 20 is fixed to the main body 10 and includes a drive source 21 such as a motor and a speed reducer 22 for reducing the output speed of the drive source 21. However, it may also be a direct drive motor without the speed reducer 22. The actuator 20 includes an output shaft 23 for driving the driven body 11 to rotate. The force sensor 30 is disposed between the output shaft 23 and the driven body 11 and detects the force acting between the output shaft 23 and the driven body 11. The force sensor 30 is, for example, a triaxial force sensor capable of detecting the torque Mz about the A (Z) axis when the A axis is taken as the Z axis, and the forces Fx and Fy in two directions perpendicular to each other and perpendicular to the A (Z) axis. However, it may also be a six-axis force sensor capable of detecting the forces Mx, My, Mz, Fx, Fy, and Fz in six-axis directions. In addition, it may also be a uniaxial torque sensor capable of only detecting the torque Mz about the A (Z) axis when the A axis is taken as the Z axis. The type of force (force, torque) that the force sensor can detect and the number of axes (detection degrees of freedom) that can be detected are not limited to the above-described embodiments. The combination of the type of force that can be detected and the number of axes that can be detected may also be any combination.

[0036] Figure 2 Details of the force sensor 30 are shown. The force sensor 30 is, for example, a strain gauge type force sensor, but it may also be a force sensor of other detection methods such as piezoelectric, optical, electrostatic capacitance, and magnetostrictive. For example, the force sensor 30 includes: an input body 31 connected to the output shaft 23; an output body 32 connected to the driven body 11; a strain generating body 33 connecting the input body 31 and the output body 32 and capable of generating strain due to the relative rotation of the input body 31 and the output body 32; and a strain detection sensor 34 capable of detecting the strain generated in the strain generating body 33. However, the force sensor 30 may also adopt various structures according to the detection method.

[0037] Refer again to Figure 1 , the rotating shaft structure 1 further includes a soft deformable body 40 in contact with the output shaft 23 and the driven body 11, and the whole of the force sensor 30 is sealed by the output shaft 23, the driven body 11, and the soft deformable body 40. By using the soft deformable body 40, foreign matters are prevented from entering the space around the force sensor 30 through the gap 35 formed between the input body 31 and the output body 32, so that corrosion of the force sensor 30 can be prevented. At the same time, the force sensor 30 itself does not have a sealing member and does not need to have high dust-proof ability, high waterproof ability, high rust-proof ability, etc. Therefore, the force sensor 30 can be miniaturized and lightened, and furthermore, a small and lightweight rotating shaft structure 1 can be provided.

[0038] In addition, it is desirable that the contact portions of the soft deformable body 40 that come into contact with the output shaft 23 and the driven body 11 do not move relative to the output shaft 23 and the driven body 11, respectively, and that the portions of the soft deformable body 40 other than the contact portions deform softly without generating a reaction force. The degree of softness and the degree of reaction force in the soft deformable body 40 are such that, for example, almost no reaction force to return to the original shape (i.e., no influence on the detection accuracy of the force sensor 30) is generated at a deformation amount (i.e., the strain amount of the force sensor 30) in the range of several hundred micrometers to several millimeters. The reaction force does not necessarily need to be zero. The deformed portion of the soft deformable body 40 can be, for example, a soft film-like (e.g., 0.01 mm thick sheet-like) portion formed of an elastic material such as an elastomer like a rubber balloon. The contact portions of the soft deformable body 40 that come into contact with the output shaft 23 or the driven body 11 can be fixed by an adhesive, screw fastening, etc. Thus, the contact portions of the soft deformable body 40 that come into contact with the output shaft 23 and the driven body 11 do not move relative to the output shaft 23 and the driven body 11, respectively, and the portions of the soft deformable body 40 other than the contact portions (i.e., the deformed portions) deform softly following the strain of the force sensor 30 without generating a reaction force. Furthermore, a rotating shaft structure 1 that stabilizes or improves the detection accuracy of the force sensor 30 can be provided.

[0039] In addition, the rotating shaft structure 1 may include a through-hole 51 that penetrates the actuator 20 and the force sensor 30 in the axial direction of the rotation axis A, and a line body 50 passes through the through-hole 51. Particularly in the joint structure of a robot, the line body 50 includes at least one of a line body for driving the actuator 20, a line body for communicating with the force sensor 30, and a line body for driving a tool mounted at the front end of the robot. That is, the line body 50 includes, for example, a plurality of line bodies composed of a power cable, a signal cable, an air tube for a suction manipulator, etc. By passing the line body 50 through the through-hole 51, the line body 50 is disposed inside the rotating shaft structure 1 without getting entangled with a person, which is particularly advantageous in the case of the joint structure of a collaborative robot. At the same time, the through-hole 51 communicates with the gap 35 of the force sensor 30, and the soft deformable body 40 also prevents foreign matter from entering the through-hole 51 from the gap 35, so that damage to the line body 50 caused by corrosion or biting of foreign matter in the through-hole 51 can be suppressed.

[0040] The force sensor 30 may also include a communication substrate 36 capable of serial communication or wireless communication. That is, the communication substrate 36 can sequentially transmit or receive data bit by bit on a wired or wireless transmission path. By using the communication substrate 36, the number of wire bodies 50 passing through the through holes 51 can be reduced, so that the possibility of disconnection of the wire body 50 during the rotation operation can be further reduced, and the reaction force that restores the wire body 50 to its original state during the rotation operation can be suppressed. That is, a rotation shaft structure 1 that can stabilize or improve the detection accuracy of the force sensor 30 can be provided. In addition, since the entire force sensor 30 is sealed by a flexible deformable body 40, the sealing function of the communication substrate 36 itself is not required, and the outer shape of the force sensor 30 can be further miniaturized.

[0041] In addition, it is desirable that the communication substrate 36 or the wire body for the force sensor can be daisy-chain connected. In the case where there are multiple rotation shaft structures 1, especially in the joint structure of a multi-joint robot, the communication substrates 36 or the wire bodies for the force sensors of each joint part are connected in a daisy-chain manner, whereby the number of wire bodies 50 passing through the through holes 51 can be further reduced. Therefore, the possibility of disconnection of the wire body 50 during the rotation operation can be further reduced, and the reaction force that restores the wire body 50 to its original state during the rotation operation can be further suppressed.

[0042] In addition, the rotation shaft structure 1 may also include a failover structure that duplicates the detection circuit of the force sensor 30. For example, as Figure 2 shown, the rotation shaft structure 1 includes at least two strain generating bodies 33, and at least two strain detection sensors 34 for detecting the strain generated in each of the two strain generating bodies 33 are daisy-chain connected in another system through the communication substrate 36 or the wire body for the force sensor. Alternatively, the rotation shaft structure 1 may include at least one strain generating body 33, and at least two strain detection sensors 34 for detecting the strain generated in the at least one strain generating body 33 are daisy-chain connected in another system through the communication substrate 36 or the wire body for the force sensor. Thus, especially in a collaborative robot, even if the detection circuit of one system fails for some reason, the robot can be safely stopped by the detection circuit of the other system. At the same time, even when the detection circuit of the force sensor 30 is duplicated, the detection circuits of the two systems can be daisy-chain connected respectively, so that the increase in the number of wire bodies 50 passing through the through holes 51 can be significantly suppressed.

[0043] Figure 3The rotational axis structure 1 in other embodiments is shown. In the rotational axis structure 1 of this example, the difference from the above-described embodiment is that the driven body 11 extends to the side of the output shaft 23 so as to cover the outer periphery of the force sensor 30. By bringing the driven body 11 closer to the output shaft 23, it is possible to reduce the size of the soft deformable body 40 that contacts the output shaft 23 and the driven body 11, and thus the possibility of affecting the force sensor 30 can be minimized.

[0044] In addition, in the rotational axis structure 1 of this example, it is also different from the above-described embodiment in that the soft deformable body 40 has a degree of slack. Figure 4 It is an enlarged view of the soft deformable body 40 having a degree of slack. It can be that the deformed portion 41 of the soft deformable body 40 has a degree of slack such as that of a damaged and deflated rubber balloon, and the contact portions 42 of the soft deformable body 40 that contact the output shaft 23 and the driven body 11 are fixed by an adhesive, screw fastening, etc., respectively. The degree of slack in the soft deformable body 40 is, for example, a degree of slack such that almost no reaction force to return it to its original shape (i.e., it does not affect the detection accuracy of the force sensor 30) is generated at a deformation amount (i.e., the strain amount of the force sensor 30) in the range of several hundred micrometers to several millimeters. The slack is formed in a manner of undulating in the radial direction toward the rotational axis, but it can also be formed in a manner of undulating in a direction inclined with respect to the radial direction with respect to the rotational axis. Thereby, the contact portions 42 of the soft deformable body 40 that contact the output shaft 23 and the driven body 11 do not relatively move with respect to the output shaft 23 and the driven body 11, and the portions (i.e., the deformed portion 41) of the soft deformable body 40 other than the contact portions deform softly in a manner of following the strain of the force sensor 30 without generating a reaction force. Furthermore, it is possible to provide the rotational axis structure 1 that stabilizes or improves the detection accuracy of the force sensor 30.

[0045] Figure 5Shows other modified examples of the flexible deformable body 40. The deformed portion 41 of the flexible deformable body 40 is a flexible film-like portion formed of an elastic material such as an elastomer. However, the contact portion 42 of the flexible deformable body 40 that contacts the output shaft 23 and the driven body 11 may not be fixed, but at least one of the surfaces of the contact portion has a coefficient of friction that does not allow relative movement. For example, it may be configured such that relative movement prevention grooves 43 for preventing relative movement of the flexible deformable body 40 are formed in the circumferential direction on the outer circumferential surface of the output shaft 23 and the inner circumferential surface of the driven body 11, and the vicinity of the contact portion 42 of the flexible deformable body 40 is elastically deformed and then inserted (i.e., pressed) into the relative movement prevention grooves 43 so that the contact portion 42 does not undergo relative movement. Additionally, in order to prevent relative movement of the flexible deformable body 40, at least one of the surfaces of the contact portion 42 of the flexible deformable body 40 that contacts the output shaft 23 and the driven body 11 may have a surface roughness such as a rough portion or uneven portions that increases the coefficient of friction. As a result, the contact portions 42 of the flexible deformable body 40 that contact the output shaft 23 and the driven body 11 do not undergo relative movement with respect to the output shaft 23 and the driven body 11, respectively, and the portions of the flexible deformable body 40 other than the contact portion 42 (i.e., the deformed portion 41) are softly deformed in a manner following the strain of the force sensor 30 without generating a reaction force. Furthermore, a rotation shaft structure 1 that stabilizes or improves the detection accuracy of the force sensor 30 can be provided.

[0046] Figure 6Another modified example of the flexible deformable body 40 is shown. The flexible deformable body 40 may also be a member in the shape of an O-ring with a double-layer structure. It may be that the deformed portion 41 of the flexible deformable body 40 is an inner layer portion composed of a fluid such as gas, liquid, or gel, and the contact portion 42 of the flexible deformable body 40 that contacts the output shaft 23 and the driven body 11 is a flexible film-like outer layer portion formed of an elastic material such as an elastomer. Alternatively, it may be that the deformed portion 41 (inner layer portion) is composed of the same elastic material such as an elastomer as the contact portion 42 (outer layer portion), but it may also be composed of a material softer than the contact portion 42 (outer layer portion). In addition, it may be that the deformed portion 41 (inner layer portion) and the contact portion 42 (outer layer portion) are composed of the same soft elastic material such as an elastomer, and the surface of the contact portion 42 (outer layer portion) has a coefficient of friction that does not allow relative movement with respect to the surfaces of the output shaft 23 and the driven body 11. For example, it may be configured such that a relative movement prevention groove 43 for preventing relative movement of the flexible deformable body 40 is formed in the circumferential direction on the outer peripheral surface of the output shaft 23, and while elastically deforming a vicinity portion of the contact portion 42 of the flexible deformable body 40, it is inserted (i.e., pressed) into the relative movement prevention groove 43 so that the contact portion 42 does not undergo relative movement. In addition, in order to prevent relative movement of the flexible deformable body 40, the surface of at least one of the contact portions 42 of the flexible deformable body 40 that contacts the output shaft 23 may also have a surface roughness such as a rough portion or an uneven portion that increases the coefficient of friction. On the other hand, the contact portion 42 of the flexible deformable body 40 that contacts the driven body 11 is fixed by an adhesive or the like, but it may also be configured such that a relative movement prevention groove is formed in the circumferential direction on the outer peripheral surface of the driven body 11, and while elastically deforming a vicinity portion of the contact portion 42 of the flexible deformable body 40, it is inserted into the relative movement prevention groove so that the contact portion 42 does not undergo relative movement. Thus, the contact portions 42 of the flexible deformable body 40 that contact the output shaft 23 and the driven body 11 do not undergo relative movement with respect to the output shaft 23 and the driven body 11, respectively, and the portion of the flexible deformable body 40 other than the contact portion 42 (i.e., the deformed portion 41) is softly deformed in a manner following the strain of the force sensor 30 without generating a reaction force. Furthermore, a rotating shaft structure 1 that stabilizes or improves the detection accuracy of the force sensor 30 can be provided.

[0047] Figure 7An example of a robot 60 that corrects the variation amount of a force sensor 30 is shown. When the above-described rotary shaft structure 1 is applied to the joint structure of the robot 60, it is desirable that the robot 60 be provided with a control device that estimates the variation amount (other axis interference force) of the force sensor 30 acting on a specific joint axis and corrects it. The control device includes: a variation amount estimation unit 61 that estimates the variation amount of the force sensor 30 acting on a specific joint axis by using known parameters of the robot 60; a force correction unit 62 that corrects the force detected by the force sensor 30 based on the estimated variation amount; a motion command correction unit 63 that corrects the motion command based on the corrected force; and a drive unit 64 that drives the drive source 21 of a specific joint axis based on the corrected motion command.

[0048] For example, the variation amount estimation unit 61 can calculate the tilting torque in a direction other than the rotational direction and the static load in other directions (first other axis force component) acting on a specific joint axis according to the posture of the robot 60 at a certain moment by using known parameters such as the wrist load and the arm mass of the robot 60, and calculate the tilting torque in a direction other than the rotational direction and the force in other directions (second other axis force component) acting on a specific joint axis due to inertial force according to the motion speed of the robot 60 at a certain moment by using known parameters such as the wrist load and the arm mass of the robot 60, and estimate the correction torque Tf by adding the first other axis force component and the second other axis force component.

[0049] In addition, the force correction unit 62 calculates the estimated actual torque Tr by subtracting the estimated correction torque Tf from the detected torque T of the force sensor 30. The estimated actual torque Tr represents the actual torque generated in the rotational direction of a specific joint axis after excluding the other axis force component in a direction other than the rotational direction acting on the specific joint axis.

[0050] The motion command correction unit 63 calculates the drive torque by subtracting the calculated estimated actual torque Tr from the torque command value Ti that is the motion command of the robot 60. The drive unit 64 drives the drive source 21 according to the calculated drive torque. That is, the detected torque T detected by the force sensor 30 during the driving of the drive source 21 is used as the estimated actual torque Tr for the feedback control of the drive unit 64 after subtracting the correction torque Tf. Thus, for example, when an operator directly contacts the robot mechanism part and applies an external force to perform lead-through teaching, the actual torque generated in the rotational direction of a specific joint axis due to the external force can be estimated with high accuracy.

[0051] According to the above embodiments, the entire force sensor 30 is sealed by the output shaft 23, the driven body 11, and the flexible deformable body 40. Therefore, not only can corrosion of the force sensor 30 or intrusion of foreign matters be suppressed, but also since there is no need to provide a sealing member for the force sensor 30 itself, the force sensor 30 can be miniaturized and lightened. Furthermore, a small and lightweight rotating shaft structure 1 can be provided. At the same time, the flexible deformable body 40 deforms softly in a manner that follows the strain of the force sensor 30 without generating a reaction force. Therefore, the detection accuracy of the force sensor 30 is not affected. That is, a rotating shaft structure 1 that can stabilize or improve the detection accuracy of the force sensor 30 can be provided.

[0052] In addition, the force sensor 30 reduces the number of wire bodies 50 penetrating through the through hole 51 by providing a communication substrate capable of serial communication or wireless communication. Therefore, the possibility of disconnection of the wire body 50 occurring during the rotation operation can be reduced, and the reaction force for restoring the wire body 50 to its original state during the rotation operation can be suppressed. That is, a rotating shaft structure 1 that can stabilize or improve the detection accuracy of the force sensor 30 can be provided.

[0053] Although various embodiments have been described in this specification, it should be recognized that the present invention is not limited to the above embodiments, and various modifications can be made within the scope described in the claims.

[0054] Description of Reference Numerals

[0055] 1: Rotating shaft structure; 10: Main body; 11: Driven body; 20: Actuator; 21: Driving source; 22: Reducer; 23: Output shaft; 30: Force sensor; 31: Input body; 32: Output body; 33: Strain generating body; 34: Strain detection sensor; 35: Gap; 36: Communication substrate; 40: Flexible deformable body; 41: Deformation part; 42: Contact part; 43: Relative movement prevention groove; 50: Wire body; 51: Through hole; 60: Robot; 61: Variation amount estimation unit; 62: Force correction unit; 63: Motion command correction unit; 64: Driving unit; A: Rotation axis.

Claims

1. A rotary shaft structure, comprising: an actuator having an output shaft for driving a driven body to rotate; and a force sensor disposed between the output shaft and the driven body for detecting a force acting between the output shaft and the driven body. The rotary shaft structure further includes a flexible deformable body that contacts the output shaft and the driven body, and the entire force sensor is sealed by the output shaft, the driven body, and the flexible deformable body.

2. The rotary shaft structure according to claim 1, wherein the contact portions of the flexible deformable body that contact the output shaft and the driven body do not relatively move with respect to the output shaft and the driven body, and portions of the flexible deformable body other than the contact portions deform softly without generating a reaction force.

3. The rotary shaft structure according to claim 1 or 2, wherein the contact portion of the flexible deformable body that contacts the output shaft or the driven body is fixed, or at least one of the surfaces of the contact portions has a coefficient of friction that does not allow relative movement.

4. The rotary shaft structure according to claim 1 or 2, wherein the deformable portion of the flexible deformable body is a soft film-like portion.

5. The rotary shaft structure according to claim 1 or 2, wherein the deformable portion of the flexible deformable body has a slack.

6. The rotary shaft structure according to claim 1 or 2, wherein the contact portion of the flexible deformable body is fitted into a relative movement prevention groove formed in at least one of the output shaft and the driven body.

7. The rotary shaft structure according to claim 1 or 2, wherein the driven body extends to the side of the output shaft so as to cover the outer periphery of the force sensor.

8. The rotary shaft structure according to claim 1 or 2, wherein the force sensor includes: an input body connected to the output shaft; an output body connected to the driven body; and a strain generating body connecting the input body and the output body, capable of generating strain due to relative rotation between the input body and the output body. The flexible deformable body prevents foreign matter from entering the gap formed between the input body and the output body.

9. The rotary shaft structure according to claim 1 or 2, wherein the force sensor itself does not have a sealing member.

10. The rotary shaft structure according to claim 1 or 2, wherein a through hole is further provided, the through hole penetrates the actuator and the force sensor along the axial direction of the output shaft, and a wire body penetrates through the through hole. The flexible deformable body prevents foreign matter from entering the through hole.

11. The rotary shaft structure according to claim 10, wherein the force sensor includes a communication substrate capable of serial communication or wireless communication, and the number of the wire bodies penetrating through the through hole is reduced by the communication substrate.

12. The rotary shaft structure according to claim 11, wherein the communication substrate or the wire body for the force sensor can be daisy-chain connected.

13. A rotary shaft structure includes: an actuator having an output shaft for driving a driven body to rotate; A force sensor configured between the output shaft and the driven body to detect a force acting between the output shaft and the driven body; A through-hole that penetrates the actuator and the force sensor along the axial direction of the output shaft, and a wire body penetrates through the through-hole. In the rotary shaft structure, the force sensor includes a communication substrate capable of serial communication or wireless communication. A through-hole coaxial with the through-hole is formed in the communication substrate, and the number of wire bodies penetrating through the through-hole and the through-hole is reduced by the communication substrate. The rotary shaft structure further includes a flexible deformable body that contacts the output shaft and the driven body, and the entire force sensor is sealed by the output shaft, the driven body, and the flexible deformable body.

14. The rotary shaft structure according to claim 13, wherein The communication substrate or the wire body for the force sensor can be daisy-chain connected.

15. The rotary shaft structure according to claim 13 or 14, wherein The force sensor further includes: an input body connected to the output shaft; an output body connected to the driven body; at least two strain generating bodies that connect the input body and the output body and can generate strain due to the relative rotation of the input body and the output body; And at least two strain detection sensors that detect the strain generated in each of the two strain generating bodies of the two strain generating bodies. Each of the strain detection sensors is daisy-chain connected to other systems through the communication substrate or the wire body for the force sensor.

16. The rotary shaft structure according to claim 13 or 14, wherein The force sensor further includes: an input body connected to the output shaft; an output body connected to the driven body; at least one strain generating body that connects the input body and the output body and can generate strain due to the relative rotation of the input body and the output body; And at least two strain detection sensors that detect the strain generated in the one strain generating body. Each of the strain detection sensors is daisy-chain connected to other systems through the communication substrate or the wire body for the force sensor.

17. A robot includes the rotary shaft structure according to any one of claims 1 to 16 as a joint structure. The robot includes: a variation amount estimation unit that estimates the variation amount of the force using known parameters of the robot; and a force correction unit that corrects the force detected by the force sensor based on the estimated variation amount.

18. A robot includes the rotary shaft structure according to any one of claims 10 to 16 as a joint structure. In the robot, the wire body includes at least one of a wire body for driving an actuator, a wire body for force sensor communication, and a wire body for driving a tool mounted at the front end of the robot.

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