Wave gear device, method for measuring torque in a wave gear device, and robot

Abstract

The strain gauges are arranged alternately in the plurality of torque sensor sets, and each set includes a plurality of strain gauges. Each set of torque sensors is configured to measure a torque transmitted by the strain wave gear device during rotation of the flexible spline. Signals measured by the plurality of torque sensor sets include torque ripple. The processor calculates the true torque transmitted by the strain wave gear device based on the signals measured by the plurality of torque sensor sets, and the torque ripple is excluded from the true torque.

Description

[Technical Field]

[0001] The present invention relates to the technical field of strain wave gearing, and more particularly to a strain wave gearing, a method for measuring torque in a strain wave gearing, and a robot. [Background technology]

[0002] In recent years, robotics has continued to develop rapidly and is widely used in industrial production. Strain wave gearing is commonly used in robots as a deceleration mechanism to reduce rotational speed and increase torque, adjusting the movement speed and output torque of the robot's connecting arm and achieving harmonic reduction transmission. Strain wave gearing typically comprises an internally toothed circular spline, a flexible spline, and a wave generator that deforms the flexible spline along its radial direction. As the wave generator rotates, the flexible spline undergoes controllable elastic deformation, causing the teeth of the flexible spline to mesh with the internal teeth of the circular spline, thereby transmitting motion and force.

[0003] Currently, in order to measure the output torque of a strain wave gearing device in a joint between connecting arms of a robot, one possible method is to connect an elastic body in series to the strain wave gearing device and place a torque sensor on the elastic body. However, this increases the number of parts, which is disadvantageous for reducing the size and cost of the robot joint.

[0004] In another aspect, the purpose of measuring output torque can be achieved by arranging a torque sensor (e.g., a strain gauge) inside the strain wave gearing (e.g., on a flexible spline). However, because strain gauges are usually arranged discretely inside the strain wave gearing, the strain of each strain gauge does not perfectly match the measured strain value, and as a result, there is variation in the torque value converted from the strain value, which affects the measurement accuracy of the output torque. Summary of the Invention [Problem to be solved by the invention]

[0005] Based on this, in order to overcome one or more of the above-mentioned drawbacks, the present invention provides a strain wave gearing device, a method for measuring torque in a strain wave gearing device, and a robot that can effectively eliminate the effect of torque ripple in a signal measured by a torque sensor and accurately measure the true torque in the strain wave gearing device. [Means for solving the problem]

[0006] Specifically, one aspect of the present invention provides a strain wave gearing device, the strain wave gearing device including: a wave generator; a circular spline having internal teeth; a flexible spline provided between the wave generator and the circular spline and configured to mesh with the internal teeth of the circular spline; multiple sets of torque sensors; and a processor, the multiple sets of torque sensors are arranged alternately and each set includes multiple strain gauges, and each set of torque sensors is configured to measure a torque transmitted by the strain wave gearing device during rotation of the flexible spline, the signals measured by the multiple sets of torque sensors include torque ripple, and the processor calculates a true torque transmitted by the strain wave gearing device based on the signals measured by the multiple sets of torque sensors, and the torque ripple is excluded from the true torque.

[0007] In one embodiment, the plurality of sets of torque sensors comprises a first set of torque sensors including four strain gauges and a second set of torque sensors including four strain gauges, the strain gauges of the first set of torque sensors and the strain gauges of the second set of torque sensors being alternately arranged at a 45° angle.

[0008] In one embodiment, the strain wave gearing further includes an angle measuring device that measures the angle of the wave generating device relative to the flexible spline during rotation of the flexible spline.

[0009] In one embodiment, the processor calculates the true torque according to the following formula: where τ is the true torque transmitted by the strain wave gearing, τ is the torque value measured by the first set of torque sensors, τ is the torque value measured by the second set of torque sensors, and θ is the angle of the wave generator relative to the flexible spline.

[0010]

number

[0011] In one embodiment, the angle measurement device includes a first angle sensor configured to measure the angle of the wave generator relative to the circular spline during rotation of the flexible spline, and a second angle sensor configured to measure the angle of the flexible spline relative to the circular spline during rotation of the flexible spline, making it possible to measure the angle of the wave generator relative to the flexible spline during rotation of the flexible spline.

[0012] In one embodiment, the plurality of sets of torque sensors includes a first set of torque sensors, a second set of torque sensors, and a third set of torque sensors, wherein the first set of torque sensors includes four strain gauges, the second set of torque sensors includes four strain gauges, and the third set of torque sensors includes four strain gauges, wherein the strain gauges of the first set of torque sensors, the second set of torque sensors, and the third set of torque sensors are alternately arranged at an angle of 30°, wherein each strain gauge in the second set of torque sensors is arranged 30° ahead of an adjacent strain gauge in the first set of torque sensors, and wherein each strain gauge in the third set of torque sensors is arranged 30° behind an adjacent strain gauge in the first set of torque sensors.

[0013] In one embodiment, the processor calculates the true torque according to the following formula: Here, τ0 is the true torque value transmitted by the strain wave gearing, τ4 is the torque value measured by the first set of torque sensors, τ5 is the torque value measured by the second set of torque sensors, τ6 is the torque value measured by the third set of torque sensors, and τ6 is the output torque value of the strain wave gearing.

[0014]

number

[0015] In one embodiment, the processor calculates the true torque according to the following formula: where τ is the true torque transmitted by the strain wave gearing, τ is the torque value measured by the first set of torque sensors, and τ 5´ is the torque value measured by the second set of torque sensors, and τ 6´ is the torque value measured by the third set of torque sensors, Δα is the angular deviation between the second set of torque sensors and the first set of torque sensors, and Δβ is the angular deviation between the third set of torque sensors and the first set of torque sensors.

[0016]

number

[0017] In one embodiment, each of the plurality of torque sensor sets is disposed on the flexible spline and configured to surround the axis of the flexible spline.

[0018] In one embodiment, the flexible spline includes a main body portion, a toothed portion provided at one end of the main body portion and configured to mesh with the internal teeth of the circular spline, and a flange extending radially outward from an end of the main body portion opposite the toothed portion, and the multiple sets of torque sensors are provided on at least one of the inside of the flexible spline, the outside of the main body portion, the side of the flange facing the toothed portion, and the side of the flange away from the toothed portion.

[0019] In one embodiment, the wave generator, the circular spline, and the flexible spline are arranged coaxially.

[0020] In one embodiment, the strain gauges are made from polyvinylidene fluoride, or a material suitable for Hall sensors, capacitive sensors.

[0021] In one embodiment, the strain gauges are fabricated by screen printing.

[0022] In one embodiment, the strain wave gear device further includes a Kalman filter.

[0023] Another aspect of the present invention provides a method for measuring torque in a strain wave gearing device, the strain wave gearing including a wave generator, a circular spline provided with internal teeth, a flexible spline provided between the wave generator and the circular spline and configured to mesh with the internal teeth of the circular spline, multiple sets of torque sensors arranged alternately, each set including multiple strain gauges, and a processor, the method including the steps of measuring, with each of the multiple sets of torque sensors, the torque transmitted by the strain wave gearing during rotation of the flexible spline, the signals measured by the multiple sets of torque sensors including torque ripple, and calculating, by the processor, a true torque transmitted by the strain wave gearing based on the signals measured by the multiple sets of torque sensors, the torque ripple being excluded from the true torque.

[0024] Another aspect of the present invention provides a robot including a plurality of connecting arms, any two adjacent connecting arms being rotatably connected by a robot joint, and the robot joint including the strain wave gear device described above.

[0025] The accompanying drawings, which form a part of this invention, are used to provide a further understanding of the invention, and the schematic embodiments of the invention and their descriptions are used to interpret the invention and do not constitute an undue limitation of the invention.

[0026] In order to more clearly explain the technical aspects of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. However, the accompanying drawings in the following description are only a part of the embodiments of the present invention, and it is clear to those skilled in the art that other accompanying drawings can be obtained from these accompanying drawings without any creative effort. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic diagram of an axial cross section of a strain wave gear device according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram illustrating the configuration of a robot joint to which a strain wave gear device according to an embodiment of the present invention is attached. [Figure 3] FIG. 1 is a schematic perspective view of a flexible spline of a strain wave gear device based on an embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram of an arrangement pattern of two sets of torque sensors according to one embodiment of the present invention. [Figure 5] 1 is a flowchart of a method for measuring true torque in a strain wave gear device according to one embodiment of the present invention. [Figure 6] FIG. 10 is a schematic diagram of an arrangement pattern of three sets of torque sensors according to another embodiment of the present invention. [Figure 7] 1 is a schematic diagram of a robot based on an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] In order to make the above-mentioned objects, features, and advantages of the present invention clearer and easier to understand, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In order to fully understand the present invention, many specific details are set forth in the following description. However, the present invention can be embodied in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific examples disclosed below.

[0029] It should be understood that terms such as "first," "second," and the like used to describe various components do not denote any order, quantity, or importance, but are merely used to distinguish between different components. These terms are used only to distinguish one component from another. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component, without departing from the scope of the present invention. Similar terms such as "comprise" or "include" do not exclude other elements or objects, but rather mean that the elements or objects preceding the term include the elements or objects listed after the term, and equivalents thereof.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms used in the specification of the present invention are used only for the purpose of describing specific examples and are not intended to limit the present invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] The term "embodiment" referred to herein means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that mutually excludes other embodiments. Those skilled in the art will understand, either explicitly or implicitly, that the embodiments described herein may be combined with other embodiments.

[0032] A wave gearing 100 according to one embodiment of the present invention will now be described with reference to Fig. 1. Fig. 1 is a schematic diagram of an axial cross section of a wave gearing 100 according to one embodiment of the present invention.

[0033] 1, a strain wave gearing 100 is provided. The strain wave gearing 100 includes a wave generator 102, for example a cam, a circular spline 104 provided with internal teeth, and a flexible spline 106 provided between the wave generator 102 and the circular spline 104 and configured to mesh with the internal teeth of the circular spline 104. Furthermore, the wave generator 102, the circular spline 104, and the flexible spline 106 are arranged substantially coaxially.

[0034] Referring to FIG. 2, FIG. 2 is a schematic diagram of a robot joint equipped with a strain wave gearing 100 according to an embodiment of the present invention. For example, in a robot joint equipped with the strain wave gearing 100, the wave generator 102 of the strain wave gearing 100 is generally connected to one end of a transmission input shaft 108, and a motor is generally attached to the other end of the transmission input shaft 108, for example, to achieve reduction transmission. In the example shown in FIG. 2, the motor includes a stator 110 and a rotor 112, and the stator 110 can be fixed to the housing of the robot joint by any appropriate means. Meanwhile, the flexible spline 106 of the strain wave gearing 100 is connected to one end of a transmission output shaft 114, and an output member 116 of the robot joint, such as an end effector, is attached to the other end of the transmission output shaft 114. Additionally, the circular spline 104 of the strain wave gearing 100 can also be fixed to the housing of the robot joint by any suitable means.

[0035] When the strain wave gear device 100 is used as a reducer, it is common to adopt a configuration in which the wave generator 102 is in operation, the circular spline 104 is fixed, and output is provided by the flexible spline 106. Of course, in some embodiments, a configuration in which the flexible spline 106 is fixed and output is provided by the circular spline 104 may also be adopted.

[0036] Specifically, in an operation process in which the strain wave gearing 100 is used for reduction transmission, the wave generator 102 rotates together with the motor rotor 112 via the transmission input shaft 108, and the flexible spline 106 periodically deforms radially while rotating together with the wave generator 102, causing the teeth of the flexible spline 106 to mesh with corresponding teeth on the circular spline 104 and transmit torque. Furthermore, the rotational speed of the transmission output shaft 114 is reduced by the strain wave gearing 100, thereby achieving reduction transmission.

[0037] A flexible spline 106 according to an embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a schematic perspective view of the flexible spline 106 of the strain wave gear device 100 according to an embodiment of the present invention.

[0038] 3, the flexible spline 106 according to one embodiment of the present invention includes a main body portion 202, a toothed portion 204 provided at one end of the main body portion 202 and configured to mesh with the internal teeth of the circular spline 104, and a flange 206 extending radially outward from the end of the main body portion 202 opposite the toothed portion 204. As shown in FIG. 3, the flexible spline 106 itself has a cylindrical structure and is thin-walled and elastically deformable. As described above, the flexible spline 106 can be periodically deformed radially by the wave generating device 102 during operation of the strain wave gearing 100.

[0039] Furthermore, in one embodiment of the present invention, the strain wave gearing 100 further includes a plurality of torque sensor sets that are arranged alternately, each set including a plurality of strain gauges, each set being used to measure the torque transmitted by the strain wave gearing 100 during rotation of the flexible spline 106, and each signal measured by each set including a torque ripple; and a processor (not shown) that calculates the true torque transmitted by the strain wave gearing based on the signals measured by the plurality of torque sensor sets, wherein the torque ripple is excluded from the true torque.

[0040] In an embodiment of the present invention, each of the plurality of torque sensors is disposed on the flexible spline 106 so as to surround the axis of the flexible spline 106. As a result, the plurality of strain gauges of the plurality of torque sensors are located in the same plane with respect to the axis of the flexible spline 106. Specifically, as shown in Fig. 3, the plurality of strain gauges 208 of the plurality of torque sensors are provided, for example, in at least one of an area A1 inside the flexible spline 106, an area A2 outside the main body portion 202, an area A3 on the side of the flange 206 facing the toothed portion 204, and an area A4 on the side of the flange 206 away from the toothed portion 204.

[0041] In the following, for ease of explanation, the multiple sets of torque sensors will be described as being located in area A3 on the side of the flange 206 facing the toothed portion 204, but the present specification is not limited to this.

[0042] Referring to FIG. 4, an arrangement pattern of two sets of torque sensors according to one embodiment of the present invention will be described.

[0043] In one embodiment of the present invention, the plurality of sets of torque sensors includes a first set of torque sensors and a second set of torque sensors, the first set of torque sensors includes four strain gauges, the second set of torque sensors includes four strain gauges, and the strain gauges of the first set of torque sensors and the strain gauges of the second set of torque sensors are alternately arranged at an angle of 45°.

[0044] Specifically, as shown in FIG. 4, in an area A3 of the flange 206 facing the toothed portion 204, eight strain gauges 208 are uniformly and annularly arranged about the axis of the flexible spline 106. That is, each strain gauge 208 is equidistant from the axis of the flexible spline 106 in the radial direction, and adjacent strain gauges 208 are offset by 45° from the axis of the flexible spline 106. The eight strain gauges 208 are divided into two sets, i.e., a first set of torque sensors and a second set of torque sensors, and the first set of torque sensors and the second set of torque sensors are alternately arranged. For example, referring to FIG. 4, the strain gauge 208 located at the top of FIG. 4 is counted first and counted clockwise. As a result, the first set of torque sensors includes the first, third, fifth, and seventh strain gauges of the eight strain gauges 208, and the second set of torque sensors includes the second, fourth, sixth, and eighth strain gauges of the eight strain gauges 208. Therefore, each set of torque sensors includes four strain gauges 208. Furthermore, the four strain gauges 208 included in each set of torque sensors form a Wheatstone bridge, forming a detection circuit for measuring the torque transmitted by the strain wave gear drive 100 during rotation of the flexible spline 106.

[0045] Furthermore, in some embodiments, the strain gauge 208 may be, for example, a rosette-type strain gauge. As described above, symmetrically arranging eight strain gauges can effectively eliminate the influence of torque ripple in the signal measured by the torque sensor, as described below, thereby effectively improving measurement sensitivity and accuracy. Furthermore, the strain gauge 208 may be made of, for example, polyvinylidene fluoride (PVDF) or other materials suitable for Hall sensors and capacitive sensors. Furthermore, the strain gauge 208 may be manufactured by, for example, screen printing and attached to the strain wave gearing 100. Alternatively, the strain gauge 208 may be directly formed on the strain wave gearing 100 by screen printing.

[0046] Referring again to FIG. 2, in some embodiments, the strain wave gearing 100 may further include an angle measuring device configured to measure the angle θ of the wave generating device 102 relative to the flexible spline 106 during rotation of the flexible spline 106.

[0047] Further, the angle measurement device may include, for example, a first angle sensor and a second angle sensor, wherein the first angle sensor is configured to measure the angle of the wave generating device 102 relative to the circular spline 104 (or a housing or other member fixedly connected to the circular spline 104) during rotation of the flexible spline 106, and the second angle sensor is configured to measure the angle of the flexible spline 106 relative to the circular spline 104 (or a housing or other member fixedly connected to the circular spline 104) during rotation of the flexible spline 106, thereby measuring the angle θ of the wave generating device 102 relative to the flexible spline 106 during rotation of the flexible spline 106.

[0048] 2, the first angle sensor includes a first read head 118 mounted on a housing fixedly connected to the circular spline 104 and a first disk 120 mounted on the wave generator 102. Furthermore, the second angle sensor includes a second read head 122 mounted on a housing fixedly connected to the circular spline 104 and a second disk 124 mounted on the flexible spline 106. As shown in FIG. 3, the second disk 124 is mounted, for example, in an area A4 on the side of the flange 206 away from the toothed portion 204. As a result, while the flexible spline 106 is rotating, the processor can obtain angle data of the flexible spline 106 and the wave generator 102 relative to the housing using the first read head 118 and the second read head 122, respectively, and as a result, can obtain the angle θ of the wave generator 102 relative to the flexible spline 106.

[0049] Furthermore, in the example of FIG. 2, the first disk 120 and the second disk 124 are both mounted to a housing, but it should also be considered that the first disk 120 and the second disk 124 may be mounted directly to the circular spline 104.

[0050] 2, the angle measurement device includes two angle sensors, but it should be considered that the angle measurement device may include only one angle sensor, for example, in which a read head and a disk are mounted on the wave generator 102 and the flexible spline 106, respectively.

[0051] Furthermore, in some embodiments, the strain wave gearing 100 may further include a Kalman filter for eliminating high frequency measurement signal components to further improve measurement accuracy.

[0052] 5, which is a flowchart of a method for measuring true torque in a strain wave gearing device according to one embodiment of the present invention. As shown, another aspect of the present invention provides a method for measuring torque in a strain wave gearing device. As described above, the strain wave gearing device includes, for example, a wave generator, a circular spline having internal teeth, a flexible spline provided between the wave generator and the circular spline and configured to intermesh with the internal teeth of the circular spline, multiple sets of torque sensors arranged alternately, each set including multiple strain gauges, and a processor.

[0053] The method comprises: a step S100 of measuring torque transmitted by the strain wave gear device during rotation of the flexible spline by each of the plurality of torque sensor sets, and measuring signals measured by the plurality of torque sensor sets including torque ripple; and step S200, in which the processor calculates the true torque transmitted by the strain wave gearing based on the signals measured by the plurality of sets of torque sensors, and the torque ripple is excluded from the true torque.

[0054] 4, the strain gauge 208 at the top of FIG. 4 is counted first and counts clockwise. The first set of torque sensors includes the second, fourth, sixth, and eighth strain gauges of the eight strain gauges 208, and the second set of torque sensors includes the first, third, fifth, and seventh strain gauges of the eight strain gauges 208. Therefore, each set of torque sensors includes four strain gauges 208. This will be described below as an example, but the present specification is not limited thereto.

[0055] As a result, the four strain gauges 208 included in each set of torque sensors form a Wheatstone bridge, forming a detection circuit for measuring the torque transmitted by the strain wave gear device during rotation of the flexible spline.

[0056] As described above, the torque ripple contained in the signals measured by the first set of torque sensors and the second set of torque sensors is related to the angle θ of the wave generator relative to the flexible spline as shown in equation (1) below. where τ r is the torque ripple contained in the signal measured by the first set of torque sensors (or the second set of torque sensors), and τ pr is the peak value of the torque ripple.

[0057]

number

[0058] As described above, the strain gauges of the first set of torque sensors and the strain gauges of the second set of torque sensors are arranged alternately at an angle of 45°, so there is a phase difference between the torque values ​​measured by the strain gauges of these two sets of torque sensors. Assuming that the second set of torque sensors lags the first set of torque sensors by 45°, the torque values ​​measured by the first set of torque sensors and the second set of torque sensors are expressed by the following equations (2) and (3), respectively. Here, τ1 is the torque value measured by the first set of torque sensors, τ2 is the torque value measured by the second set of torque sensors, and τ0 is the output torque value of the strain wave gear device.

[0059]

number

[0060]

number

[0061] It should be noted that θ here is the relative angle between the wave generator and the flexible spline, obtained by taking the position of any strain gauge in the first set of torque sensors as the reference point on the flexible spline and a point on the major axis of the elliptical wave generator as the reference point. In practical application, if other points on the wave generator and the flexible spline are taken as the reference points, the above formula will be adjusted accordingly, but the principle remains unchanged, and the principle and spirit of the present disclosure are still applicable.

[0062] Then, the processor calculates the true torque transmitted by the strain wave gearing based on the torque values ​​measured by the first set of torque sensors and the second set of torque sensors, and the torque ripple is excluded from the true torque. Specifically, τ0 can be calculated by the above-mentioned equations (2) and (3) and the following equation (4).

[0063]

number

[0064] Therefore, the output torque value of the strain wave gear device is expressed by the following equation (5).

[0065]

number

[0066] Additionally, the method may further include using a Kalman filter to eliminate high frequency measurement signal components and correct errors to further improve measurement accuracy.

[0067] Referring now to FIG. 6, an arrangement pattern of three sets of torque sensors according to another embodiment of the present invention will be described. As shown in the figure, in this embodiment, in an area A3 on the side of the flange 206 facing the toothed portion 204, twelve strain gauges 208 are uniformly and annularly arranged with respect to the axis of the flexible spline 106. That is, each strain gauge 208 is equidistant from the axis of the flexible spline 106 in the radial direction, and adjacent strain gauges 208 are offset by 30° with respect to the axis of the flexible spline 106. The twelve strain gauges 208 are divided into three sets alternately arranged at 30° angles, i.e., a first set of torque sensors, a second set of torque sensors, and a third set of torque sensors. For example, referring to FIG. 6, the upper strain gauge 208 in FIG. 6 is counted first, and the sets are counted clockwise. As a result, the first set of torque sensors includes the third, sixth, ninth, and twelfth strain gauges of the twelve strain gauges 208, the second set of torque sensors includes the second, fifth, eighth, and eleventh strain gauges of the twelve strain gauges 208, and the third set of torque sensors includes the first, fourth, seventh, and tenth strain gauges of the twelve strain gauges 208. Thus, each set of torque sensors includes four strain gauges 208. Furthermore, each strain gauge of the second set of torque sensors is positioned 30° ahead of the adjacent strain gauges of the first set of torque sensors, and each strain gauge of the third set of torque sensors is positioned 30° behind the adjacent strain gauges of the first set of torque sensors.

[0068] Furthermore, the four strain gauges 208 included in each set of torque sensors form a Wheatstone bridge, forming a detection circuit that measures the torque transmitted by the strain wave gearing 100 during rotation of the flexible spline 106.

[0069] Similarly, the strain gauges 208 may be, for example, rosette-type strain gauges. As described above, symmetrically arranging the 12 strain gauges can effectively eliminate the influence of torque ripple in the signal measured by the torque sensor, thereby effectively improving measurement sensitivity and accuracy. Furthermore, the strain gauges 208 may be made of, for example, polyvinylidene fluoride (PVDF) or other materials suitable for Hall sensors and capacitive sensors. Furthermore, the strain gauges 208 may be manufactured by, for example, screen printing and attached to the strain wave gearing 100. Alternatively, the strain gauges 208 may be directly formed on the strain wave gearing 100 by screen printing.

[0070] Similarly, the torque ripple contained in the signals measured by the first set of torque sensors, the second set of torque sensors, and the third set of torque sensors is related to the angle θ of the wave generator relative to the flexible spline, as shown in equation (1) above. where τ r is the torque ripple contained in the signal measured by the first set of torque sensors (or the second set of torque sensors or the third set of torque sensors), and τ pr is the peak value of the torque ripple.

[0071]

number

[0072] As described above, the three sets of torque sensors are arranged alternately at an angle of 30°, so there is a phase difference between the torque values ​​measured by the strain gauges of the three sets of torque sensors. The torque values ​​measured by the first set of torque sensors, the second set of torque sensors, and the third set of torque sensors are expressed by the following equations (6), (7), and (8), respectively. Here, τ4 is the torque value measured by the first set of torque sensors, τ5 is the torque value measured by the second set of torque sensors, τ6 is the torque value measured by the third set of torque sensors, and τ0 is the output torque value of the strain wave gear device.

[0073]

number

[0074]

number

[0075]

number

[0076] It should be noted that θ here is the relative angle between the wave generator and the flexible spline, obtained by taking the position of any strain gauge in the first set of torque sensors as the reference point on the flexible spline and a point on the major axis of the elliptical wave generator as the reference point. In practical application, if other points on the wave generator and the flexible spline are taken as the reference points, the above formula will be adjusted accordingly, but the principle remains unchanged, and the principle and spirit of the present disclosure are still applicable.

[0077] Then, the processor calculates the true torque transmitted by the strain wave gearing based on the torque values ​​measured by the first set of torque sensors, the second set of torque sensors, and the third set of torque sensors, and the torque ripple is excluded from the true torque. Specifically, τ0 is calculated using the above-mentioned equations (6), (7), and (8) and the following equation (9):

[0078]

number

[0079] Furthermore, in this embodiment, a situation where there is a position error among the three sets of torque sensors is considered. That is, after the second set of torque sensors and the third set of torque sensors are arranged, it is assumed that there are angular deviations of Δα and Δβ with respect to the first set of torque sensors, respectively. Therefore, the second set of torque sensors are arranged to be (30°+Δα) ahead of the first set of torque sensors, and the third set of torque sensors are arranged to be (30°+Δβ) behind the first set of torque sensors. As a result, the torque values ​​measured by the second set of torque sensors and the third set of torque sensors are expressed by the following equations (10) and (11), respectively. where τ 5´ is the torque value measured by the second set of torque sensors, and τ 6´ is the torque value measured by the third set of torque sensors.

[0080]

number

[0081]

number

[0082] τ0 is calculated using the above equations (6), (10), (11) and the following equation (12).

[0083]

number

[0084] Furthermore, in this embodiment, a Kalman filter can be used to eliminate high frequency measurement signal components and correct errors, further improving measurement accuracy.

[0085] Furthermore, in another embodiment of the present invention, the strain wave gear drive may further include a circuit board to which the plurality of torque sensors are electrically connected. The circuit board may be installed, for example, on the side of the flexible spline opposite the toothed portion and fixedly connected to the flexible spline by, for example, bolting or gluing. This allows the circuit board to rotate in accordance with the rotation of the flexible spline. Furthermore, the circuit board may be equipped with a processor for calculating true torque, a memory for recording data related to output torque, etc.

[0086] Another aspect of the present invention provides a robotic joint and a robot. A robotic joint and a robot according to one embodiment of the present invention will now be described with reference to FIG. 7 . As shown, the robot 300 includes multiple articulated arms 301, which are pivotally connected to corresponding robotic joints 302 using the harmonic gearing described above. The robot 300 further includes a robotic gripping jaw 303, one end of which is connected to a corresponding articulated arm 301, and the other end of which is provided with one or more gripping devices. This allows the robot 300 to be used to clamp or grasp an object. Those skilled in the art should understand that the configuration shown in FIG. 7 is merely an exemplary embodiment of the robot 300. In other embodiments, the robot 300 may include more or fewer components, such as additional articulated arms and end effectors. Some components (e.g., two or more articulated arms) may be combined, and different or additional types of components than those depicted may be employed. For example, the robot may further include I / O devices, network access devices, communication buses, a processor, memory, actuators, and sensors to achieve control of the system. For example, the robot 300 includes a processor and a memory that stores instructions that, when executed by the processor, enable control of the system. The memory may also store instructions that, when executed by the processor, activate or deactivate the robot gripping jaws 303 to grasp or release a clamped article.

[0087] In describing the present invention, terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like, indicate orientations or positional relationships based on those shown in the accompanying drawings, and are used solely for the purpose of facilitating and simplifying the description of the present invention, and do not expressly or imply that the devices or elements shown must have a particular orientation, be configured, or operate in a particular orientation, and therefore should not be construed as limitations of the present invention.

[0088] Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as expressing or implying relative importance, nor do they implicitly designate the number of technical features shown. Thus, a feature defined with the term "first" or "second" may expressly or imply the inclusion of at least one of the feature. In the description of the present invention, unless otherwise specified, "plurality" means at least two.

[0089] In the present invention, unless otherwise specified, the terms "attached," "connected," "coupled," "fixed," etc., are to be understood in a broad sense. For example, they may refer to a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, a connection within two elements, or an interaction between two elements. Those skilled in the art can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0090] The various technical features of the above-described embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations of the various technical features of the above-described embodiments have been described, and as long as there is no contradiction in the combination of these technical features, it should be considered to fall within the scope described in this specification.

[0091] The above examples merely represent some embodiments of the present invention in more detail and should not be construed as limiting the scope of protection of the present invention. It should be noted that a person skilled in the art may make some modifications and improvements without departing from the spirit of the present invention, and all such modifications and improvements are within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. [Explanation of symbols]

[0092] 100 Strain wave gear device 102 Wave Generator 104 Circular Spline 106 Flexible Spline 108 Transmission input shaft 110 Stator 112 rotor 114 Transmission output shaft 116 Output member 118 first read head 120 First Disc 122 second read head 124 Second Disc 202 Main body 204 Toothed part 206 flange 208 Strain Gauge 300 robots 301 Connecting arm 302 Robot Joints 303 Robotic Grasping Jaw A1, A2, A3, A4 area S100~S200 steps

Claims

1. A strain wave gear device, A wave generator; a circular spline provided with internal teeth; a flexible spline provided between the wave generating device and the circular spline and configured to mesh with the internal teeth of the circular spline; a plurality of torque sensors; a processor, the plurality of sets of torque sensors are arranged alternately, each set including a plurality of strain gauges, each of the plurality of sets of torque sensors being configured to measure a torque transmitted by the strain wave gear device during rotation of the flexible spline, and signals measured by the plurality of sets of torque sensors include torque ripple; The strain wave gearing, wherein the processor calculates a true torque transmitted by the strain wave gearing based on signals measured by the plurality of sets of torque sensors, and the torque ripple is excluded from the true torque.

2. 2. The strain wave gear device according to claim 1, wherein the plurality of sets of torque sensors comprises a first set of torque sensors including four strain gauges and a second set of torque sensors including four strain gauges, and the strain gauges of the first set of torque sensors and the strain gauges of the second set of torque sensors are arranged alternately at an angle of 45°.

3. 3. The strain wave gearing according to claim 2, further comprising an angle measuring device that measures the angle of the wave generator relative to the flexible spline during rotation of the flexible spline.

4. The processor may be configured to: [Equation 17] Calculate the true torque according to ０ is the true torque transmitted by the strain wave gearing, and τ １ is the torque value measured by the first set of torque sensors, and τ ２ 4. The strain wave gearing according to claim 3, wherein θ is the torque value measured by the second set of torque sensors, and θ is the angle of the wave generator relative to the flexible spline.

5. 4. The strain wave gearing according to claim 3, wherein the angle measurement device includes a first angle sensor configured to measure an angle of the wave generator relative to the circular spline during rotation of the flexible spline, and a second angle sensor configured to measure an angle of the flexible spline relative to the circular spline during rotation of the flexible spline, and is capable of measuring the angle of the wave generator relative to the flexible spline during rotation of the flexible spline.

6. the plurality of sets of torque sensors include a first set of torque sensors, a second set of torque sensors, and a third set of torque sensors, the first set of torque sensors including four strain gauges, the second set of torque sensors including four strain gauges, and the third set of torque sensors including four strain gauges, the strain gauges of the first set of torque sensors, the strain gauges of the second set of torque sensors, and the strain gauges of the third set of torque sensors are alternately arranged at an angle of 30°; 2. The strain gauge of claim 1, wherein each strain gauge in the second set of torque sensors is positioned 30° ahead of an adjacent strain gauge in the first set of torque sensors, and each strain gauge in the third set of torque sensors is positioned 30° behind an adjacent strain gauge in the first set of torque sensors.

7. The processor may be configured to: [Equation 18] Calculate the true torque according to ０ is the true torque value transmitted by the strain wave gearing, and τ ４ is the torque value measured by the first set of torque sensors, and τ ５ is the torque value measured by the second set of torque sensors, and τ ６ is the torque value measured by the third set of torque sensors, and τ ０ is the output torque value of the strain wave gearing device.

8. The processor may be configured to: [Equation 19] Calculate the true torque according to ０ is the true torque transmitted by the strain wave gearing, and τ ４ is the torque value measured by the first set of torque sensors, and τ ５´ is the torque value measured by the second set of torque sensors, and τ ６´ is a torque value measured by the third set of torque sensors, Δα is an angular deviation between the second set of torque sensors and the first set of torque sensors, and Δβ is an angular deviation between the third set of torque sensors and the first set of torque sensors.

9. 2. The strain wave gear device according to claim 1, wherein each of the plurality of torque sensor sets is disposed on the flexible spline and configured to surround the axis of the flexible spline.

10. The flexible spline a main body; a toothed portion provided at one end of the main body portion and configured to mesh with the internal teeth of the circular spline; a flange extending radially outward from an end of the body portion opposite the toothed portion, 10. The wave gear device according to claim 9, wherein the plurality of torque sensors are provided on at least one of an inside of the flexible spline, an outside of the main body, a side of the flange facing the toothed portion, and a side of the flange away from the toothed portion.

11. 1. A method for measuring torque in a strain wave gear device, comprising: The wave gear device is A wave generator; a circular spline provided with internal teeth; a flexible spline provided between the wave generating device and the circular spline and configured to mesh with the internal teeth of the circular spline; a plurality of sets of torque sensors arranged alternately, each set including a plurality of strain gauges; a processor, The method comprises: measuring, by each of the plurality of torque sensor sets, a torque transmitted by the strain wave gear device during rotation of the flexible spline, and detecting a torque ripple in the signal measured by the plurality of torque sensor sets; calculating, by the processor, a true torque transmitted by the strain wave gearing based on signals measured by the plurality of sets of torque sensors, wherein the torque ripple is excluded from the true torque.

12. 12. The method of claim 11, wherein the sets of torque sensors comprise a first set of torque sensors including four strain gauges and a second set of torque sensors including four strain gauges, the strain gauges of the first set of torque sensors and the strain gauges of the second set of torque sensors being alternately positioned at a 45° angle.

13. 13. The method of claim 12, wherein the strain wave gearing further includes an angle measuring device that measures the angle of the wave generator relative to the flexible spline during rotation of the flexible spline.

14. The processor may be configured to: [Equation 20] Calculate the true torque according to ０ is the true torque transmitted by the strain wave gearing, and τ １ is the torque value measured by the first set of torque sensors, and τ ２ 14. The method of claim 13, wherein Θ is the torque value measured by the second set of torque sensors and θ is the angle of the wave generator relative to the flexible spline.

15. 14. The method of claim 13, wherein the angle measurement device comprises a first angle sensor configured to measure the angle of the wave generator relative to the circular spline during a rotation of the flexible spline, and a second angle sensor configured to measure the angle of the flexible spline relative to the circular spline during a rotation of the flexible spline, and is capable of measuring the angle of the wave generator relative to the flexible spline during a rotation of the flexible spline.

16. the plurality of sets of torque sensors include a first set of torque sensors, a second set of torque sensors, and a third set of torque sensors, the first set of torque sensors including four strain gauges, the second set of torque sensors including four strain gauges, and the third set of torque sensors including four strain gauges, the strain gauges of the first set of torque sensors, the strain gauges of the second set of torque sensors, and the strain gauges of the third set of torque sensors are alternately arranged at an angle of 30°; 12. The method of claim 11, wherein each strain gauge in the second set of torque sensors is positioned 30° ahead of an adjacent strain gauge in the first set of torque sensors, and each strain gauge in the third set of torque sensors is positioned 30° behind an adjacent strain gauge in the first set of torque sensors.

17. The processor may be configured to: [Equation 21] Calculate the true torque according to ０ is the true torque transmitted by the strain wave gearing, and τ ４ is the torque value measured by the first set of torque sensors, and τ ５ is the torque value measured by the second set of torque sensors, and τ ６ is the torque value measured by the third set of torque sensors, and τ ０ 17. The method of claim 16, wherein: is the output torque value of the strain wave gearing.

18. The processor may be configured to: [Equation 22] Calculate the true torque according to ０ is the true torque transmitted by the strain wave gearing, and τ ４ is the torque value measured by the first set of torque sensors, and τ ５´ is the torque value measured by the second set of torque sensors, and τ ６´ 17. The method of claim 16, wherein Δα is the torque value measured by the third set of torque sensors, Δα is the angular deviation between the second set of torque sensors and the first set of torque sensors, and Δβ is the angular deviation between the third set of torque sensors and the first set of torque sensors.

19. The method of claim 11 , wherein each set of the plurality of torque sensors is disposed on the flexible spline and configured to surround an axis of the flexible spline.

20. A robot, The robot includes a plurality of connecting arms, any two adjacent connecting arms are rotatably connected by a robot joint, and the robot joint includes the strain wave gear device according to any one of claims 1 to 10.

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