Driver and robot with reliable torque sensor arrangement

Abstract

A driver of a robot system and a robot are provided. The driver may include a central shaft, a housing connected to the central shaft, an input flange and an output flange coaxially mounted on the central shaft, a torque sensor, and a motor assembly. The input flange and the output flange are radially fixed with at least one of the housing and the central shaft through a plurality of bearings. The torque sensor is connected between the input flange and the output flange and is configured to measure torque transmitted through the input flange and the output flange. The motor assembly is coupled to the input flange. Interference transmitted from either side of the torque sensor may be isolated from the sensor. Therefore, the reliability of the reading of the torque sensor can be improved.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62 / 743,303, filed on October 9, 2018, entitled “HIGHLY COMPACT SHAFT REFERENCE ROTARY DRIVE SYSTEM WITH HIGH-FILIMENT TORQUE SENSING,” the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates generally to robotics and more particularly to a drive and a robot having a reliable torque sensor arrangement. Background Art

[0004] Torque sensors are commonly used in various tasks in robotics and are an important component for achieving torque control of robotic arms. In a torque-controlled robotic arm, each joint of the robotic arm (i.e., the drive system / driver) may include a torque sensor for measuring the output torque for use in a closed-loop control system. However, there are many challenges in integrating sensitive torque sensors into the joints of a robot. For example, in order to minimize the errors caused by sensor crosstalk, it is generally necessary to decouple the torque sensor from forces and moments that are not in the sensing direction. In addition, conventional joint drive systems may use the housing as the sole reference for the component, which may result in a complex and bulky mechanical design for the associated torque sensor. Summary of the invention

[0005] It is therefore an object of the present invention to provide a drive and a robot with a reliable torque sensor arrangement which can improve the reliability of the torque sensor readings contained in the drive.

[0006] In order to solve the above-mentioned problem, the present invention adopts a technical solution to provide a driver for a robot system. The driver may include: a central shaft, a housing connected to the central shaft, an input flange and an output flange coaxially mounted on the central shaft, a torque sensor, and a motor assembly. The input flange and the output flange are radially fixed to at least one of the housing and the central shaft through a plurality of bearings. The torque sensor is connected between the input flange and the output flange and is configured to measure the torque transmitted through the input flange and the output flange. The motor assembly is coupled to the input flange.

[0007] In order to solve the above-mentioned problems, the present invention adopts a technical solution to provide a robot with multiple drivers and multiple connectors. The multiple connectors are connected in sequence through the drivers. Each of the drivers may include: a central shaft, a housing connected to the central shaft, an input flange and an output flange coaxially mounted on the central shaft, a torque sensor, and a motor assembly. The input flange and the output flange are radially fixed to at least one of the housing and the central shaft through multiple bearings. The torque sensor is connected between the input flange and the output flange and is configured to measure the torque transmitted through the input flange and the output flange. The motor assembly is coupled to the input flange.

[0008] In order to solve the above-mentioned problems, the present invention adopts a technical solution to provide a driver for a robot system. The driver may include: a central shaft, a housing, a motor, a harmonic drive, an input flange, an output flange, and a torque sensor. The housing may be connected to the central shaft. The motor, the harmonic drive, the input flange, and the output flange may be coaxially mounted on the central shaft through a plurality of bearings. The motor may be coupled to the harmonic drive, and the output end of the harmonic drive may be coupled to the input flange. The torque sensor may be connected between the input flange and the output flange, and may be configured to measure the torque transmitted through the input flange and the output flange.

[0009] According to some embodiments of the present invention, the input flange and the output flange may be radially fixed to the housing and / or the central axis, and the torque sensor may be connected between the input flange and the output flange. Therefore, interference transmitted from either side of the torque sensor may be isolated from the torque sensor. Accordingly, the reliability of the reading of the torque sensor may be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly describes the drawings used in the description of the embodiments. The drawings in the following description are only exemplary embodiments of the present invention. For those of ordinary skill in the art, other embodiments can be obtained based on these drawings without any creative work.

[0011] Figure 1 is a schematic diagram showing the internal structure of a driver according to an embodiment of the present invention.

[0012] Figure 2 An exemplary torque sensor arrangement for a drive according to an embodiment of the present invention is shown.

[0013] Figure 3An exemplary torque sensor arrangement for a drive according to an embodiment of the present invention is shown.

[0014] Figure 4 An exemplary torque sensor arrangement for a drive according to an embodiment of the present invention is shown.

[0015] Figure 5 An exemplary structure of a harmonic drive of a driver according to an embodiment of the present invention is shown.

[0016] Figure 6 An exemplary structure of a motor of a driver according to an embodiment of the present invention is shown.

[0017] Figure 7 A schematic diagram of a robot according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0018] The present invention will now be described in detail with reference to the accompanying drawings and examples. The described embodiments are merely examples and represent only a subset of the embodiments of the present invention. Based on the embodiments of the present invention, a person of ordinary skill in the art can think of other embodiments without making creative work, and all of these embodiments fall within the scope of protection of the present invention.

[0019] Figure 1 An exemplary internal structure of the driver 10 according to one embodiment of the present invention is shown. Figure 1 The driver 10 shown in FIG. 1 may include a housing 11 , a central shaft 12 , a motor assembly 13 , an input flange 14 , a torque sensor 15 and an output flange 16 .

[0020] The housing 11 can be connected to the central shaft 12. For example, the central shaft 12 can be bolted to the housing 11 at the left end, and can be guided by two bearings at the right end. In this example, the housing 11 and the central shaft 12 can use each other as a reference. Other components can use the housing 11 or the central shaft 12 or both as a reference for alignment. In some aspects of the present invention, the central shaft 12 can be hollow to allow wires to pass through. For example, the central shaft 12 can be provided with a central channel 121, which can accommodate a control cable (not shown) of a drive. The input flange 14 and the output flange 16 can be coaxially mounted on the central shaft 12 (directly or indirectly). Bearings 20 can be used to align the input flange 14 and the output flange 16 coaxially with the central shaft 12 while still allowing relative rotational movement.

[0021] In one embodiment, Figure 2As shown, the bearing 20 may include a first bearing 201, a second bearing 202, and a third bearing 203. The first bearing 201 may be connected between the input flange 14 and the central shaft 12. The second bearing 202 may be connected between the output flange 16 and the central shaft 12. The third bearing 203 may be connected between the output flange 16 and the housing 11.

[0022] In other embodiments, Figure 3 As shown, the bearing 20 may include a first bearing 204, a second bearing 205, and a third bearing 206. The first bearing 204 may be connected between the input flange 14 and the housing 11. The second bearing 205 may be connected between the output flange 16 and the housing 11. The third bearing 206 may be connected between the output flange 16 and the central shaft 12. In other examples of the present invention, the bearing 20 may be arranged differently so that the input flange 14 and the output flange 16 may be appropriately connected to the housing 11 or the central shaft 12 or both.

[0023] For example, in Figure 4 In the embodiment shown in , the central shaft 12 can be rotatably connected to the housing 11, and the output flange 16 can be fixed to the central shaft 12, so that the output flange 16 and the central shaft 12 can rotate together relative to the housing 11. In this example, the bearing 20 can only include a first bearing 207 and a second bearing 208, the first bearing 207 is located between the input flange 14 and the central shaft 12, and the second bearing 208 is located between the output flange 16 and the housing 11. In some aspects of the present invention, the bearing 20 can be an angular contact bearing. In other aspects, the bearing 20 can have a sufficient axial load rating, such as a deep groove ball bearing.

[0024] See also Figures 1 to 4 In some aspects, the torque sensor 15 can be connected between the input flange 14 and the output flange 16. The torque sensor 15 can be used to measure the torque transmitted through the input flange 14 and the output flange 16. The torque sensor 15 can be any suitable torque sensor known in the art. For example, the torque sensor 15 may include two rigid plates (not shown), the two rigid plates are respectively connected to the input flange 14 and the output flange 16, and the two rigid plates can be connected by an elastic component. One or more pairs of signal pairs can be mounted on the two rigid plates. In this example, the transmitted torque can be the deformation result of the elastic component (i.e., the displacement between the two rigid plates) and is estimated based on the reading of the signal pair.

[0025] In the foregoing embodiments, the input flange 14 and the output flange 16 may be radially fixed to the housing 11 and / or the central shaft 12, and the torque sensor 15 is connected between the input flange 14 and the output flange 16. Accordingly, interference transmitted from either side of the torque sensor 15 may be isolated from the torque sensor 15 by the input flange 14, the output flange 16, and the bearing 20. Therefore, the reliability of the reading of the torque sensor 15 may be improved.

[0026] In some examples, the bearing 20 can be used to resist axial interference generated by other internal components. When the joint with the driver 10 is subjected to loads from different directions, the central shaft 12 and the housing 11 can provide rigid protection accordingly, so that: (1) the torque sensor 15 only measures axial torque, and (2) loads from other directions cannot penetrate the rigid shaft reference structure. In addition, vibrations or other interferences generated by any component of the driver 10 (e.g., the motor assembly 13) will not affect other components of the joint with the driver 10 because the central shaft 12 and the housing 11 provide strong support to resist and prevent vibration propagation. For example, vibrations may be attenuated by the stiffness of the central shaft 12. Therefore, the torque sensor 15 can be used to collect high-fidelity readings that reflect the actual axial torque applied to the robot arm at the driver 10.

[0027] See also Figure 2 The driver 10 may further include a sleeve 22. The sleeve 22 may be disposed around the central shaft 12 and between the first bearing 21 and the second bearing 202 so as to maintain a predetermined distance between the first bearing 201 and the second bearing 202. In this example, the distance between the first bearing 201 and the second bearing 202 may be changed by adjusting the size of the sleeve 22.

[0028] In various examples, the driver 10 may further include a stop nut 23. Figure 2 As shown, the limit nut 23 can be connected to the output flange 16 by a threaded connection. Therefore, when the limit nut 23 rotates, the axial position of the limit nut 23 can be adjusted. The limit nut 23 can be used to limit the axial position of the first bearing 201 and the second bearing 202 relative to the central shaft 12. In other embodiments, the limit nut 23 can be connected to the input flange 14 by a threaded connection, and is similarly used to limit the axial position of the bearing 20. In some examples, a protrusion for limiting the axial position of the bearings 201, 202 and 203 can be formed on the housing 11, the central shaft 12, the input flange 14 and / or the output flange 15.

[0029] See also Figure 1 and Figure 5, the motor assembly 13 of the exemplary drive may include a motor (not shown) and a harmonic drive 133. The harmonic drive 133 may be coupled between the motor and the input flange 14. The motor may include a motor stator 131 and a motor rotor 132. The motor stator 131 may be mounted on the housing 11, and the motor rotor 132 may be rotatably connected to the central shaft 12 via a motor bearing (not shown). The harmonic drive 133 may include a wave generator 1331, a circular spline 1332, and a flexible spline 1333. The wave generator 1331 may be connected to the output end of the motor rotor 132. The circular spline 1332 may be fixed to the housing 11. The flexible spline 1333 may be coupled to the input flange 14.

[0030] In some examples, both the wave generator 1331 and the flexible gear 1333 may be rotatably connected to the central shaft 12 via a plurality of harmonic drive bearings 1334. In these examples, the harmonic drive 133 may be concentrically aligned with very tight tolerances to prevent torque fluctuations and improve the durability of the harmonic drive 133. Figure 5 As shown, the exemplary harmonic drive 133 uses the housing 11 aligned with the central axis 12 and a pair of bearings 1334 as a reference to meet the alignment requirements. In the exemplary design, the reference positions of the wave generator 1331 and the flexible gear 1333 can be very close along the central axis 12, thereby avoiding tolerance stacking on multiple parts and helping to ensure that the tight tolerances of the harmonic drive 133 are met.

[0031] In some aspects of the present invention, a frameless motor may be used in the drive 10 to meet the requirements of compact structure and high torque density of the drive 10. Such a motor may include a motor stator 131 and a motor rotor 132, and the motor stator 131 and the motor rotor 132 require appropriate mounting structures to ensure concentricity. Figure 6 As shown in , the motor stator 131 may include a coil 1311 and an annular fixing portion 1312 assembled together. The annular fixing portion 1312 may fit the inner surface of the housing 11. Specifically, in some examples, the outer diameter of the annular fixing portion 1312 may be substantially equal to the inner diameter of the housing 11, and the annular fixing portion 1312 may slide into the housing 11 during installation.

[0032] In some examples, radial screws 1313 can fix the annular fixing portion 1312 to the housing 11. In these examples, the motor stator 1312 can be more easily installed on the housing 11. This assembly configuration can eliminate the need to replace the entire housing 11 if an error occurs when fixing the motor stator 1312, which is different from adhesive-based solutions.

[0033] In some examples, the driver 10 may further include other components. For example, a brake 19 may be mounted on the central shaft 12 or the housing 11 to stop the rotation of the motor assembly 13. An encoder reader 17 may be connected to the output flange 16, and a corresponding encoder disk 18 may be connected to the central shaft 12.

[0034] Figure 7 1 shows an exemplary robot 300 of the present invention, for example, the robot 300 may be an industrial robot. The exemplary robot 300 may include a plurality of actuators 32 and a plurality of connectors 31. The plurality of connectors 31 may be connected in sequence through the actuators 32. At least part of the actuators may have a similar structure as described in any of the previous embodiments. In some embodiments, the robot 300 may include a plurality of actuators 32 and a plurality of connectors 31. Figure 7 The robot 300 may include more components or fewer components than those shown in the figure. For example, some components may be combined or different types of components may be used. For example, the robot 300 may also include I / O devices, network access devices, communication buses, processors, memories, sensors, and the like. In some aspects of the present invention, the processor of the robot 300 may obtain the torque detected by the torque sensor of each drive 32 to implement closed-loop torque control.

[0035] It should be understood that the various changes and modifications of the examples described herein are obvious to those skilled in the art. These changes and modifications can be made without departing from the spirit and scope of the present application, and will not reduce its expected advantages. Therefore, it is intended that these changes and modifications be covered by the appended claims.

Claims

1. A driver for a robot system, comprising: Central axis; A housing connected to the central shaft, wherein the central shaft and the housing are configured to provide rigid protection when a joint where the actuator is located is subjected to loads from different directions; an input flange and an output flange coaxially mounted on the central shaft, wherein the input flange and the output flange are radially fixed to at least one of the housing and the central shaft by a plurality of bearings configured to resist axial interference caused by other internal components; a torque sensor connected between the input flange and the output flange and configured to measure an axial torque transmitted through the input flange and the output flange; and a motor assembly coupled to the input flange; The plurality of bearings include: a first bearing connected between the input flange and the central shaft; a second bearing connected between the output flange and the central shaft; and A third bearing is connected between the output flange and the housing.

2. The driver according to claim 1, further comprising: A sleeve is disposed around the central shaft and between the first bearing and the second bearing to maintain a predetermined distance between the first bearing and the second bearing.

3. The driver according to claim 2, further comprising: A limiting nut is connected to the input flange or the output flange by threaded connection, wherein the limiting nut is configured to limit the axial position of the first bearing and the second bearing.

4. The driver according to claim 1, characterized in that: The motor assembly includes a motor and a harmonic drive, wherein the harmonic drive is coupled between the motor and the input flange, and The motor comprises: a motor stator mounted on the housing; and A motor rotor is rotatably connected to the central shaft through a motor bearing.

5. The driver according to claim 4, characterized in that: The harmonic drive comprises: A wave generator connected to the output end of the motor rotor; a rigid gear fixed to the housing; and A flexible gear connected with the input flange, Wherein, the wave generator and the flexible gear are rotatably connected to the central shaft through a plurality of harmonic drive bearings.

6. The driver according to claim 4, characterized in that: The motor stator comprises a coil and an annular fixing portion, wherein the coil and the annular fixing portion are assembled together; and The annular fixing portion fits the inner surface of the housing and is connected to the housing by radial screws.

7. The driver according to claim 1, characterized in that: The central shaft is provided with a central passage passing through the central shaft for accommodating a control cable of the drive.

8. A robot comprising a plurality of actuators and a plurality of connectors, wherein the plurality of connectors are sequentially connected through the plurality of actuators, and each of the plurality of actuators comprises: Central axis; A housing connected to the central shaft, wherein the central shaft and the housing are configured to provide rigid protection when a joint where the actuator is located is subjected to loads from different directions; an input flange and an output flange coaxially mounted on the central shaft, wherein the input flange and the output flange are radially fixed to at least one of the input flange and the output flange by a plurality of bearings configured to resist axial interference caused by other internal components; a torque sensor connected between the input flange and the output flange and configured to measure an axial torque transmitted through the input flange and the output flange; and a motor assembly coupled to the input flange; The plurality of bearings include: a first bearing connected between the input flange and the central shaft; a second bearing connected between the output flange and the central shaft; and A third bearing is connected between the output flange and the housing.

9. The robot according to claim 8, further comprising: A sleeve is disposed around the central shaft and between the first bearing and the second bearing to maintain a predetermined distance between the first bearing and the second bearing.

10. The robot according to claim 9, further comprising: A limiting nut is connected to the input flange or the output flange by threaded connection, wherein the limiting nut is configured to limit the axial position of the first bearing and the second bearing.

11. The robot according to claim 8, characterized in that: The motor assembly includes a motor and a harmonic drive, wherein the harmonic drive is coupled between the motor and the input flange, and The motor comprises: a motor stator mounted on the housing; and A motor rotor is rotatably connected to the central shaft through a motor bearing.

12. The robot according to claim 11, characterized in that: The harmonic drive comprises: A wave generator connected to the output end of the motor rotor; a rigid gear fixed to the housing; and A flexible gear connected with the input flange, Wherein, the wave generator and the flexible gear are rotatably connected to the central shaft through a plurality of harmonic drive bearings.

13. The robot according to claim 11, characterized in that: The motor stator comprises a coil and an annular fixing portion, wherein the coil and the annular fixing portion are assembled together; and The annular fixing portion fits the inner surface of the housing and is connected to the housing by radial screws.

14. The robot according to claim 8, characterized in that The central shaft is provided with a central passage passing through the central shaft for accommodating a control cable of the drive.

15. A driver for a robot system, comprising a central shaft, a housing, a motor, a harmonic drive, an input flange, an output flange and a torque sensor, wherein: The housing is connected to the central shaft, and the central shaft and the housing are configured to provide rigid protection when the joint where the actuator is located is subjected to loads from different directions; The motor, the harmonic drive, the input flange and the output flange are coaxially mounted on the central shaft by a plurality of bearings, the plurality of bearings being configured to resist axial interference caused by other internal components; The motor is coupled to the harmonic drive, and the output end of the harmonic drive is coupled to the input flange; The torque sensor is connected between the input flange and the output flange and is configured to measure the axial torque transmitted through the input flange and the output flange; The plurality of bearings include: a first bearing connected between the input flange and the central shaft; a second bearing connected between the output flange and the central shaft; and A third bearing is connected between the output flange and the housing.

16. The driver according to claim 15, further comprising: At least one flange bearing is arranged between at least one of the input flange and the output flange and the housing.

17. The driver according to claim 15, characterized in that The central shaft is provided with a central passage passing through the central shaft for accommodating a control cable of the drive.

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