Intelligent force control joint module

Abstract

The invention discloses an intelligent force-controlled joint module which comprises a power part, a control part and a control part, the harmonic speed reduction output part comprises a harmonic speed reducer, and the harmonic speed reducer is arranged on the power part and is in transmission connection with a motor rotating shaft of the power part, so that after the rotating power transmitted by the power part is subjected to speed reduction and torque increase, the rotating power is output outwards to do work; the torque sensing piece comprises an embedded torque sensor, and the embedded torque sensor is arranged on the power piece and the harmonic speed reduction output piece at the same time and used for detecting and sensing an external load of the output end of the harmonic speed reducer; and the detection control piece comprises a rotating speed detection piece and a control piece, and the rotating speed detection piece is arranged on the power piece and detects the high rotating speed of the rotating shaft of the motor and the low rotating speed of the output end of the harmonic speed reduction output piece at the same time. The device is reasonable in structural design, high in integration level, compact in structure, small in overall size, convenient to install and easy to use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of joint modules, and more particularly to an intelligent power-controlled joint module. BACKGROUND

[0002] With the rapid development of embodied intelligent robots, in the case of increasingly rich use scenarios, the hardware requirements for robots to interact with the surrounding environment and closed-loop feedback are accelerating. For a single power joint, the most direct hardware upgrade is to make the joint have torque sensing function, which is easy to realize force / position hybrid control. The conventional processing method is to externally mount a torque sensor on the output flange of the joint, and to measure the output torque to provide torque feedback to the control system. Such processing method has the following shortcomings in actual use: 1. affecting the mechanical rigidity of the whole arm. According to the physical principle of the torque sensor, the torque sensing mode is to convert the physical deformation of the strain beam into a physical signal for processing. However, the strain beam can only bear the load in the torque direction and cannot bear other external loads such as bending moment and axial force. For positions such as robot arms and waists where the bending moment is large, on the one hand, the mechanical rigidity of the whole machine is affected, and on the other hand, the strain beam signal torque decoupling is difficult due to the influence of bending moment and axial force, affecting the measurement accuracy; 2. affecting the mechanical size of the connection position. The externally mounted torque sensor itself is an additional component between the module output end and the load, which inevitably changes the pitch diameter of the sensor mounting screw, increases the axial and radial size, and increases the complexity of assembly. Moving the mounting screw pitch outward will obviously increase the envelope size and length of the whole arm, and moving the mounting screw inward will weaken the connection rigidity; 3. occupying the hollow aperture of the module. The cable of the externally mounted torque sensor needs to pass through the hollow aperture of the module and be connected to the drive control board at the tail end of the module. This will occupy the limited space of the hollow aperture of the module, and on the other hand, it will limit the continuous 360° rotation of the module output end, otherwise the connection line of the sensor will be pulled off.

[0003] Based on the above technical problems that need to be improved, the present application designs an intelligent power-controlled joint module with integrated structure and torque sensing function, which has important use value. SUMMARY

[0004] In order to overcome the above-mentioned defects, the present application provides an intelligent power-controlled joint module, which specifically adopts the following technical scheme: An intelligent power-controlled joint module, comprising: a power component, which provides rotation power for the module; A harmonic reducer output part is arranged on the power part, and comprises a harmonic reducer which is in transmission connection with the motor rotating shaft of the power part to output the rotating power of the power part after being reduced and increased in torque. A torque sensing part is arranged on the power part and the harmonic reducer output part, and comprises an embedded torque sensor which is arranged on the power part and the harmonic reducer output part to detect and sense the load outside the output end of the harmonic reducer. A detection control part is arranged on the power part and the harmonic reducer output part, and comprises a rotating speed detection part and a control part. The rotating speed detection part detects the high rotating speed of the motor rotating shaft and the low rotating speed of the output end of the harmonic reducer. The control part is arranged on the power part to drive and control the module.

[0005] Preferably, the power part comprises a motor part and a brake part. The motor part provides rotating power for the module, and the brake part is arranged on the motor part to brake the motor rotating shaft of the motor part as needed.

[0006] Preferably, the harmonic reducer output part further comprises a roller bearing and an output end flange. The outer ring of the roller bearing is connected to the brake part, and the output end flange is arranged on the harmonic reducer to output the power reduced and increased in torque by the harmonic reducer to work.

[0007] Preferably, the harmonic reducer comprises a wave generator, a flexspline and a rigid wheel. The wave generator is connected to the motor rotating shaft, the cup of the flexspline is sleeved outside the wave generator, the rigid wheel is fixedly connected to the inner ring of the roller bearing, and the rigid wheel is sleeved on the cup of the flexspline, and the inner teeth on the rigid wheel correspond to the outer teeth on the flexspline.

[0008] Preferably, the flexspline flange on the bottom surface of the cup of the flexspline is in a bent configuration, and the flexspline flange is used to be connected to the embedded torque sensor.

[0009] Preferably, the rigid wheel is integrated with the inner ring of the roller bearing.

[0010] Preferably, the outer ring fixed mounting part of the embedded torque sensor is fastened on the outer ring of the roller bearing and the brake end cover of the brake part, and is located between the outer ring of the roller bearing and the brake end cover. The inner ring fixed mounting part of the embedded torque sensor is connected to the flexspline flange.

[0011] Preferably, the inner ring fixed mounting portion is located at the flexspline flange, the flexspline flange has a fixed block, and the inner ring fixed mounting portion is locked and fixed on the flexspline flange by screwing a screw through a first mounting through hole on the inner ring fixed mounting portion and a second mounting through hole on the flexspline flange in sequence and then tightening the screw in a threaded hole on the fixed block.

[0012] Preferably, the thin-walled portion between the outer ring fixed mounting portion and the inner ring fixed mounting portion is a strain body, and a strain gauge and a signal processing PCB are arranged in the right side space of the strain body.

[0013] The present application at least includes the following beneficial effects: 1) The intelligence control joint module of the present application has reasonable structure design, high integration, compact structure, small overall size, convenient installation and simple use; 2) The intelligence control joint module of the present application changes the structure of the conventional harmonic reducer flexspline, transforms the flexspline flange near the center of the flexspline cup bottom surface into a bent configuration, and embeds the torque sensor between the outer ring of the roller bearing and the flexspline flange, the rigid output flange connection size is unchanged, the output rigidity is not weakened, the embedded torque sensor does not directly bear the bending moment, and the joint module can pass through more wire harnesses, and the actual prototype test meets the design requirements and has good effect; 3) The embedded torque sensor of the intelligence control joint module of the present application is isolated from the cross-roller bearing of the customer output end, does not affect the rigidity of the joint, and simplifies the signal decoupling difficulty of the embedded torque sensor; the embedded torque sensor is only connected with the flexspline, only processes torque, does not participate in the load bearing of the bending moment, axial force and radial force of the output end, and the installation interface is directly connected with the rigid wheel of the reducer, which on the one hand solves the problem of the influence of the traditional torque sensor on the rigidity, and on the other hand solves the signal decoupling problem of the traditional torque sensor under complex stress conditions; 4) The intelligence control joint module of the present application is a further lightweight, miniaturized and standardized harmonic joint module, the embedded torque sensor is completely embedded in the module, the torque sensor is not a force-bearing part, and can be further lightweighted in material and structure; the output interface is consistent with the harmonic reducer; on the one hand, this greatly simplifies customer installation, and on the other hand, it is conducive to the standardization of the module size, and prepares for mass production; 5) The embedded torque sensor of the intelligence control joint module in the application is built-in, does not occupy the hollow aperture space in the module, and is not involved in rotation, so that the output end of the module can rotate continuously by 360 degrees, greatly expanding the use scenarios of the module and the robot. 6) The embedded torque sensor of the intelligence control joint module in the application is built-in, can increase the IP protection level of the module with the embedded torque sensor, and further expand the use scenarios of the module.

[0014] Other advantages, objects, and features of the present application will be apparent from the following description, and will be appreciated by those skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a front view of the intelligence control joint module in the application. Figure 2 It is a front view of the intelligence control joint module in the application. Figure 3 It is a front view of the intelligence control joint module in the application. Figure 4 It is a front view of the intelligence control joint module in the application. Figure 5 It is a front view of the intelligence control joint module in the application. Figure 2 It is a front view of the intelligence control joint module in the application. Figure 6 It is a front view of the intelligence control joint module in the application. Figure 2 It is a front view of the intelligence control joint module in the application. Figure 7 It is a front view of the intelligence control joint module in the application. Figure 2 It is a front view of the intelligence control joint module in the application.

[0016] Wherein: 1-motor shell, 2-stator, 3-rotor, 4-motor rotating shaft, 5-first supporting bearing, 6-brake end cover, 7-stator part, 8-mover part, 9-second supporting bearing, 10-outer ring of roller bearing, 11-output end flange, 12-wave generator, 13-flexspline, 14-rigid wheel, 15-flexspline flange, 16-third supporting bearing, 17-first O-ring, 18-embedded torque sensor, 19-outer ring fixed mounting part, 20-inner ring fixed mounting part, 21-fixed block, 22-first screw, 23-fifth screw, 24-strain gauge, 25-signal processing PCB, 26-second O-ring, 27-third O-ring, 28-fourth O-ring, 29-high-speed outer ring, 30-low-speed inner ring, 31-transition sleeve, 32-encoder cover, 33-fourth supporting bearing, 34-driving control board. DETAILED DESCRIPTION

[0017] The technical solutions of the present application will be described in detail below by way of examples with reference to the drawings. It should be noted that the descriptions of these examples are used to help understand the present application and do not constitute a limitation of the present application.

[0018] The term "and / or" herein is only used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, B alone, and A and B together. The term "and" herein is used to describe another association relationship of the associated objects, which means that there can be two relationships, for example, A and B, which means that there are two cases of A alone and A and B together. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after it.

[0019] According to Figures 1-7 As shown in the figure, a smart control joint module includes a power member, a harmonic reduction output member, a torque sensing member, and a detection control member. The harmonic reduction output member is arranged on the power member, and the torque sensing member and the detection control member are arranged on the power member and the harmonic reduction output member. The power member includes a motor member and a brake member, and the brake member is arranged on the motor member.

[0020] The motor part comprises a motor housing 1, a stator 2 and a rotor 3, the stator 2 is press-fitted in the cavity of the motor housing 1, the rotor 3 is press-fitted on the middle shaft segment of the motor shaft 4, the motor shaft 4 is rotationally arranged in the motor housing 1, and the rotor 3 is positionally matched with the stator 2. Further, the first supporting bearing 5 is embedded in the right inner extension bearing chamber of the motor housing 1, the inner ring of the first supporting bearing 5 is fixedly sleeved on the right shaft segment of the motor shaft 4. When the rotor 3 drives the motor shaft 4 to rotate at high speed in the motor housing 1, the motor shaft 4 drives the harmonic reducer output part. The motor shaft 4 is in the form of a hollow pipe. Alternatively, the motor part is a frameless torque motor.

[0021] The brake part comprises a brake end cover 6, a stator part 7 and a rotor part 8, the outer ring of the brake end cover 6 is fastened on the left side port of the motor housing 1 by the first screw 22, the stator part 7 is fastened and installed in the right side installation cavity of the brake end cover 6 by the second screw, the rotor part 8 is installed on the left side large step of the motor shaft 4, and a fixed air gap is reserved between the stator part 7 and the rotor part 8, so that the stator part 7 and the rotor part 8 cooperatively constitute the brake part of the motor shaft 4. It should be noted that when the stator part 7 is supplied with current, the stator part 7 will be separated from the friction braking of the rotor part 8 to release the brake of the motor shaft 4; when the stator part 7 stops being supplied with current, the stator part 7 will tightly adhere to the friction braking of the rotor part 8 to quickly and efficiently brake the motor shaft 4. Alternatively, the brake part is a permanent magnet brake.

[0022] Further, the second supporting bearing 9 is installed in the bearing chamber of the brake end cover 6 and is axially fixed by a bearing pressing plate. The inner ring of the second supporting bearing 9 is sleeved on the front end shaft segment of the motor shaft 4 and is axially fixed by a shaft segment step and a shaft circlip. The first supporting bearing 5 and the second supporting bearing 9 are arranged at both ends of the motor shaft 4 to provide stable support for the high-speed rotation of the motor shaft 4 and constitute the high-speed shaft system part of the motor.

[0023] The harmonic reducer output part comprises a roller bearing, a harmonic reducer and an output end flange 11, the roller bearing is connected to the power part through the torque sensing part, the harmonic reducer is arranged on the motor part and the roller bearing, and the output end flange 11 is arranged on the harmonic reducer. Further, the harmonic reducer is a multiple harmonic reducer. Alternatively, the harmonic reducer is a three-time harmonic reducer. The outer ring 10 of the roller bearing is connected to the brake part by the first screw 22.

[0024] The harmonic reducer comprises a wave generator 12, a flexspline 13 and a rigid spline 14, the wave generator 12 is arranged on the motor rotating shaft 4, the flexspline 13 is arranged on the wave generator 12, the rigid spline 14 is arranged on the roller bearing, and the rigid spline 14 is sleeved outside the flexspline 13. The wave generator 12 is fastened on the left end of the motor rotating shaft 4 by a third screw to form a torque input. The flexspline 13 is generally cup-shaped, the cup opening of the flexspline 13 is sleeved outside the wave generator 12. One end surface of the rigid spline 14 is fixedly connected with one end surface of the inner ring of the roller bearing, and the rigid spline 14 is sleeved on the cup opening of the flexspline 13, and the internal teeth on the inner wall of the rigid spline 14 correspond to the external teeth on the flexspline 13, so that the internal teeth on the inner wall of the rigid spline 14 and the external teeth on the flexspline 13 can generate continuous 'tooth-misalignment' movement.

[0025] Further, the flexspline flange 15 (output flange) on the bottom surface of the flexspline 13 is in a bent configuration. Alternatively, the flexspline flange 15 has a specific configuration that one end of the flexspline flange 15 is tubular, and the other end of the flexspline flange 15 is fixedly integrated with a connecting flange outside the tube, and the connecting flange is used for connecting with the torque sensor. One end of the flexspline flange 15 is connected with the bottom surface of the flexspline 13. The rigid spline 14 is integrated with the inner ring of the roller bearing, that is, the rigid spline 14 is integrally cut or integrally welded with the inner ring of the roller bearing.

[0026] The flexspline is a cup-shaped flexspline improved type. The conventional cup-shaped flexspline outputs externally through the output flange close to the center of the 'cup bottom' part, and the external teeth are arranged at the 'cup opening' position. The wave generator 12 is installed in the cavity at the 'cup opening' position. Through the rotation of the wave generator 12, the thin wall at the 'cup arm' position is deformed complexly, and the external teeth on the flexspline and the internal teeth on the rigid spline 14 further generate continuous 'tooth-misalignment' movement, so that the rigid spline 14 obtains the rotation movement after reduction and outputs externally. The effective deformation of the flexspline is mainly borne by the thin wall of the 'cup arm' and the 'cup bottom' part away from the center, and the output flange close to the center fixedly connected with the outside has little to do with it. The flexspline flange 15 close to the center of the bottom of the flexspline 13 is bent again in the present application, which on the one hand generates the installation space of the radial and axial directions of the flexspline 13, and on the other hand does not affect the thin wall range of the 'cup bottom' part of the flexspline 13, so that the hollow size of the cup-shaped flexspline 13 can be expanded without affecting the thin wall use area of the cup-shaped flexspline 13 and affecting the output torque of the reducer. Considering the light and thin type and large aperture requirement of the robot, while increasing the hollow aperture of the cup-shaped flexspline 13, on the one hand, the rigid spline 14 is integrated with the inner ring of the roller bearing, and on the other hand, the indexing pitch circle of the rigid-flexspline tooth is expanded and the radial and axial space of the roller bearing is reduced under the condition of meeting the bending moment of the robot, so as to reserve the installation space and interface for the embedding of the embedded torque sensor 18.

[0027] The output flange 11 is mounted on the other end surface of the rigid wheel 14 through the fourth screw, and the output flange 11 is embedded in the third supporting bearing 16 in the cavity of the wave generator 12. Further, the inner ring of the third supporting bearing 16 is sleeved on the shaft section step of the output flange 11 to form the first support of the output. The other end of the output flange 11 extends to the detection control member through the motor shaft 4. Further, the first O-ring 17 is arranged between the output flange 11 and the rigid wheel 14 to improve the static seal therebetween.

[0028] The torque sensing member includes an embedded torque sensor 18 arranged on the power member and the harmonic reduction output member. The outer ring fixed mounting portion 19 of the embedded torque sensor 18 is fastened on the outer ring 10 of the roller bearing and the brake end cover 6 through the first screw 22, and the outer ring fixed mounting portion 19 is located between the outer ring 10 of the roller bearing and the brake end cover 6. The inner ring fixed mounting portion 20 of the embedded torque sensor 18 is connected with the flexible wheel flange 15.

[0029] Further, the inner ring fixed mounting portion 20 is located outside one end of the flexible wheel flange 15, and a plurality of first mounting through holes uniformly distributed on the inner ring fixed mounting portion 20 correspond to a plurality of second mounting through holes on the flexible wheel flange 15 one by one. The other end of the flexible wheel flange 15 is sleeved with a fixing block 21, and a plurality of threaded holes uniformly distributed on the fixing block 21 are aligned with a plurality of second mounting through holes. The fifth screw 23 is screwed in the threaded hole after passing through the first mounting through hole and the second mounting through hole in sequence, so as to lock and fix the inner ring fixed mounting portion 20 on the flexible wheel flange 15. Alternatively, the fixing block 21 is in the form of a semicircular arc plate, and two fixing blocks 21 form a circular ring sleeved outside the other end of the flexible wheel flange 15, and a plurality of threaded holes on the two fixing blocks 21 correspond to the second mounting through holes one by one.

[0030] The thin-walled part between the outer ring fixed mounting portion 19 (the outer ring of the embedded torque sensor 18) and the inner ring fixed mounting portion 20 (the inner ring of the embedded torque sensor 18) is a strain body, and a strain gauge 24 and a signal processing PCB 25 are arranged in the right space of the strain body, and the strain body is a solid body.

[0031] A second O-ring 26 is arranged between the left end surface of the outer ring fixing mounting portion 19 and the right end surface of the outer ring 10 of the roller bearing, a third O-ring 27 is arranged between the right end surface of the outer ring fixing mounting portion 19 and the left end surface of the brake end cover 6, and a fourth O-ring 28 is arranged between the right end surface of the inner ring fixing mounting portion 20 and the left end surface of the brake end cover 6, thereby forming a grease static seal for the harmonic reducer.

[0032] The detection control member includes a rotation speed detection member and a control member, both of which are arranged on the motor member. The rotation speed detection member includes a high-speed outer ring 29 and a low-speed inner ring 30. The high-speed outer ring 29 is locked on the right end surface of the motor rotating shaft 4 by a sixth screw, and the low-speed inner ring 30 is tightly mounted on a transition sleeve 31 on the right end mounting step of the output end flange 11 by a seventh screw. The high-speed outer ring 29 and the low-speed inner ring 30 cooperatively form a high-low speed coding measurement part. Further, the rotation speed detection member is an encoder. An encoder cover 32 of the rotation speed detection member is tightly fastened on the other end surface of the motor casing 1 by an eighth screw, and a fourth supporting bearing 33 is embedded in the mounting cavity of the encoder cover 32. The inner ring of the fourth supporting bearing 33 is sleeved on the most right shaft segment of the output end flange 11, thereby forming a second support of the output end.

[0033] The control member includes a drive control board 34, which is mounted in the mounting space formed by the encoder cover 32 and the motor casing 1, thereby constituting a drive control part of the module.

[0034] When the control piece is powered on, the motor shaft 4 is rotated by the control program, driving the wave generator 12 of the harmonic reducer to move, and the wave generator 12 forces the outer teeth of the flexspline 13 and the inner teeth of the rigid wheel 14 to mesh. When the rigid wheel 14 has an external load, the reaction load will be transmitted to the flexspline through the meshing teeth of the rigid wheel 14 and the flexspline 13, and then to the inner ring of the embedded torque sensor 18. At this time, the outer ring of the embedded torque sensor 18 is fixedly installed, thereby causing the strain body between the inner and outer rings of the embedded torque sensor 18 to produce a certain torsional deformation. The deformation will be measured by the strain gauge 24 in close contact with it, and then the torsional mode will be converted into a physical signal and transmitted to the signal processing PCB 25 on the right side for processing. After processing, the signal passes through the axial through-wiring hole reserved on the side wall of the motor housing 1 and the brake end cover 6, and is finally plugged into the drive control board 34. The drive control board 34 sends the processed signal to the host computer controller, thereby completing the collection and processing of the entire module torque signal. At this time, the encoder (high-speed outer ring 29) on the high-speed end and the encoder (low-speed inner ring 30) on the low-speed end work simultaneously to accurately measure the position information of the high-speed and low-speed shafts (motor shaft 4 and output end flange 11) and transmit it to the drive control board 34 for accurate closed-loop control. The UVW power line bundle of the motor and the drive control board 34, the encoder and the drive control board 34 communication line bundle, the permanent magnet brake and the drive control board 34 power supply line bundle, and the embedded torque sensor 18 and the drive control board 34 communication line bundle are all internally wired, without occupying the hollow aperture space of the module.

[0035] Although the embodiments of the present application have been disclosed as above, they are not limited to the applications listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application. Those skilled in the art can easily make other modifications, and therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and their equivalent scope.

Claims

1. An intelligent force-controlled joint module, characterized in that, include: The power component provides the rotational power to the module; A harmonic deceleration output component is disposed on the power component. The harmonic deceleration output component includes a harmonic reducer. The harmonic reducer is disposed on the power component and is connected to the motor shaft of the power component for transmission, so as to reduce the rotational power transmitted from the power component, increase the torque, and output it to do work. A torque sensing element is disposed on the power component and the harmonic deceleration output component. The torque sensing element includes an embedded torque sensor, which is disposed on both the power component and the harmonic deceleration output component to detect and sense the external load connected to the output end of the harmonic reducer. A detection control component is disposed on the power component and the harmonic deceleration output component. The detection control component includes a speed detection component and a control component. The speed detection component is on the power component and simultaneously detects the high speed of the motor shaft and the low speed at the output end of the harmonic deceleration output component. The control component on the power component constitutes the drive control of the module.

2. The intelligent force-controlled joint module according to claim 1, characterized in that, The power component includes a motor component and a braking component. The motor component provides rotational power to the module, and the braking component is located on the motor component and brakes the motor shaft of the motor component as needed.

3. The intelligent force-controlled joint module according to claim 2, characterized in that, The harmonic reducer output component also includes a roller bearing and an output end flange. The outer ring of the roller bearing is connected to the brake component, and the output end flange is on the harmonic reducer, which outputs the power of the harmonic reducer to reduce speed and increase torque to do work.

4. The intelligent force-controlled joint module according to claim 3, characterized in that, The harmonic reducer includes a wave generator, a flexible wheel, and a rigid wheel. The wave generator is connected to the motor shaft. The cup of the flexible wheel is fitted over the wave generator. The rigid wheel is fixedly connected to the inner ring of the roller bearing and is fitted over the cup of the flexible wheel. At the same time, the internal teeth on the rigid wheel correspond to the external teeth on the flexible wheel.

5. The intelligent force-controlled joint module according to claim 4, characterized in that, The flexible wheel flange on the bottom surface of the cup of the flexible wheel has a bent configuration, and the flexible wheel flange is used to connect to the embedded torque sensor.

6. The intelligent force-controlled joint module according to claim 4 or 5, characterized in that, The rigid wheel is integrated with the inner ring of the roller bearing.

7. The intelligent force-controlled joint module according to claim 5, characterized in that, The outer ring of the embedded torque sensor is fixedly fastened to the outer ring of the roller bearing and the brake end cap of the brake component, and the outer ring is located between the outer ring of the roller bearing and the brake end cap; the inner ring of the embedded torque sensor is connected to the flexible wheel flange.

8. The intelligent force-controlled joint module according to claim 7, characterized in that, The inner ring fixing installation part is located at the flexible wheel flange. The flexible wheel flange is covered with a fixing block. After the screw passes through the first mounting through hole on the inner ring fixing installation part and the second mounting through hole on the flexible wheel flange, it is tightened into the threaded hole on the fixing block, so that the inner ring fixing installation part is locked and fixed to the flexible wheel flange.

9. The intelligent force-controlled joint module according to claim 7 or 8, characterized in that, The thin-walled portion between the outer ring fixing part and the inner ring fixing part is a strain gauge, and a strain gauge and a signal processing PCB are arranged in the space on the right side of the strain gauge.

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