Harmonic reducer, method for measuring torque in harmonic reducer, and robot

Abstract

The present invention relates to a harmonic reducer, a method for measuring torque in a harmonic reducer, and a robot. The harmonic reducer includes: a wave generator; a rigid gear provided with internal teeth; a flexible gear disposed between the wave generator and the rigid gear and configured to be meshed with the internal teeth of the rigid gear; multiple groups of torque sensors, wherein each group of the multiple groups of torque sensors includes a plurality of strain gauges, and each group of the multiple groups of torque sensors is respectively used to measure the torque transmitted by the harmonic reducer during the rotation of the flexible gear, wherein the signal measured by each group of the multiple groups of torque sensors contains a torque fluctuation amount, and the multiple groups of torque sensors are arranged crosswise; and a processor configured to calculate the true torque transmitted by the harmonic reducer according to the signals measured by the multiple groups of torque sensors, wherein the true torque does not contain a torque fluctuation amount.

Description

Technical Field

[0001] The present invention generally relates to the technical field of harmonic reducers, and particularly to a harmonic reducer, a method for measuring torque in a harmonic reducer, and a robot. Background Art

[0002] In recent years, robotics technology has been developing at a high speed and has been widely used in industrial production. As a speed reduction mechanism for reducing speed and increasing torque, a harmonic reducer is usually used in a robot to adjust the movement speed and output torque of the connecting arm of the robot, thereby realizing harmonic speed reduction transmission. A harmonic reducer generally consists of a rigid gear with internal teeth, a flexible gear, and a wave generator that causes the flexible gear to deform radially. As the wave generator rotates, the flexible gear generates controllable elastic deformation, whereby the teeth of the flexible gear can mesh with the internal teeth of the rigid gear to transmit motion and force.

[0003] Currently, in the joints between the connecting arms of a robot, in order to measure the output torque of a harmonic reducer, it is considered to connect a harmonic reducer in series with an elastic element and measure the output torque by arranging a torque sensor on the elastic element. However, this increases the number of components, and thus is not conducive to the miniaturization of the robot joint and the reduction of costs.

[0004] In addition, in other solutions, it is also considered to arrange a torque sensor (for example, a strain gauge) inside the harmonic reducer (for example, arranged on the flexible gear) to achieve the purpose of measuring the output torque. However, since the strain gauges are usually discretely arranged inside the harmonic reducer, the strain of each strain gauge and thus the measured strain values are not exactly the same, and then the torque values converted from the strain values will exhibit a fluctuation phenomenon, thereby affecting the measurement accuracy of the output torque. Summary of the Invention

[0005] Based on this, in order to overcome one or more of the above-mentioned defects, the present invention provides a harmonic reducer, a method for measuring torque in a harmonic reducer, and a robot that can effectively eliminate the influence of torque fluctuation in the signal measured by a torque sensor, thereby being able to accurately measure the true torque in the harmonic reducer.

[0006] Specifically, one aspect of the present invention provides a harmonic reducer, comprising: a wave generator; a rigid gear provided with internal teeth; a flexible gear disposed between the wave generator and the rigid gear and configured to be meshed with the internal teeth of the rigid gear; multiple groups of torque sensors, wherein each group of the multiple groups of torque sensors includes a plurality of strain gauges, and each group of the multiple groups of torque sensors is respectively used to measure the torque transmitted by the harmonic reducer during the rotation of the flexible gear, wherein the signal measured by each group of the multiple groups of torque sensors contains a torque fluctuation amount, and the multiple groups of torque sensors are arranged crosswise; and a processor configured to calculate the true torque transmitted by the harmonic reducer according to the signals measured by the multiple groups of torque sensors, wherein the true torque does not contain a torque fluctuation amount.

[0007] In one embodiment, the multiple groups of torque sensors include a first group of torque sensors and a second group of torque sensors. The first group of torque sensors includes four strain gauges, the second group of torque sensors includes four strain gauges, and the strain gauges in the first group of torque sensors and the strain gauges in the second group of torque sensors are arranged crosswise at an interval of 45° from each other.

[0008] In one embodiment, the harmonic reducer further includes an angle measuring device configured to measure the angle of the wave generator relative to the flexible gear during the rotation of the flexible gear.

[0009] In one embodiment, the processor calculates the true torque according to the following formula:

[0010]

[0011] wherein, τ o is the true torque transmitted by the harmonic reducer, τ1 is the torque value measured by the first group of torque sensors, τ2 is the torque value measured by the second group of torque sensors, and θ is the angle of the wave generator relative to the flexible gear.

[0012] In one embodiment, the angle measuring device includes a first angle sensor and a second angle sensor. The first angle sensor is configured to measure the angle of the wave generator relative to the rigid gear during the rotation of the flexible gear, and the second angle sensor is configured to measure the angle of the flexible gear relative to the rigid gear during the rotation of the flexible gear, so as to measure the angle of the wave generator relative to the flexible gear during the rotation of the flexible gear.

[0013] In one embodiment, the multiple 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 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. The strain gauges in the first set of torque sensors, the strain gauges in the second set of torque sensors, and the strain gauges in the third set of torque sensors are arranged crosswise at intervals of 30° from each other. Each strain gauge in the second set of torque sensors is 30° ahead of the adjacent strain gauge in the first set of torque sensors, and each strain gauge in the third set of torque sensors is 30° behind the adjacent strain gauge in the first set of torque sensors.

[0014] In one embodiment, the processor calculates the true torque according to the following formula:

[0015] τ o = τ5 + τ6 - τ4

[0016] where τ o is the true torque transmitted by the harmonic reducer, 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 τ o is the output torque value of the harmonic reducer.

[0017] In one embodiment, the processor calculates the true torque according to the following formula:

[0018]

[0019] where τ o is the true torque transmitted by the harmonic reducer, τ4 is the torque value measured by the first set of torque sensors, τ 5′ is the torque value measured by the second set of torque sensors, 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.

[0020] In one embodiment, each set of the multiple sets of torque sensors is disposed on the flexspline and arranged around the axis of the flexspline.

[0021] In one embodiment, the flexspline includes: a body portion; a toothed portion provided at one end of the body portion and configured to mesh with the internal teeth of the rigid ring gear; and a flange extending radially outward from the end of the body portion opposite to the toothed portion. The multiple sets of torque sensors are disposed on at least one of the inner side of the flexspline, the outer side of the body portion, the side of the flange facing the toothed portion, and the side of the flange facing away from the toothed portion.

[0022] In one embodiment, the wave generator, the rigid ring gear, and the flexspline are coaxially arranged.

[0023] In one embodiment, the strain gauge is made of polyvinylidene fluoride or a material suitable for Hall sensors or capacitive sensors.

[0024] In one embodiment, the strain gauge is made by screen printing.

[0025] In one embodiment, the harmonic reducer further includes a Kalman filter.

[0026] Another aspect of the present invention provides a method for measuring torque in a harmonic reducer. The harmonic reducer includes: a wave generator; a rigid ring gear provided with internal teeth; a flexspline disposed between the wave generator and the rigid ring gear and configured to mesh with the internal teeth of the rigid ring gear; multiple sets of torque sensors, each set of the multiple sets of torque sensors including a plurality of strain gauges, and the multiple sets of torque sensors being cross-arranged; and a processor. The method includes the following steps: measuring, by each set of the multiple sets of torque sensors, the torque transmitted by the harmonic reducer during the rotation of the flexspline, wherein the signal measured by each set of the multiple sets of torque sensors includes a torque fluctuation amount; and calculating, by the processor, the true torque transmitted by the harmonic reducer according to the signals measured by the multiple sets of torque sensors, wherein the true torque does not include the torque fluctuation amount.

[0027] Yet another aspect of the present invention provides a robot including a plurality of connecting arms, any two adjacent connecting arms being pivotally connected by a robot joint, wherein the robot joint includes any one of the harmonic reducers described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0030] Figure 1 is a schematic axial cross-sectional view of a harmonic reducer according to an embodiment of the present invention.

[0031] Figure 2 is a schematic structural view of a robot joint equipped with a harmonic reducer according to an embodiment of the present invention.

[0032] Figure 3 is a schematic perspective view of a flexspline of a harmonic reducer according to an embodiment of the present invention.

[0033] Figure 4 is a schematic view of the arrangement pattern of two sets of torque sensors according to an embodiment of the present invention.

[0034] Figure 5 is a flowchart of a method for measuring the true torque in a harmonic reducer according to an embodiment of the present invention.

[0035] Figure 6 is a schematic view of the arrangement pattern of three sets of torque sensors according to another embodiment of the present invention.

[0036] Figure 7 is a schematic structural view of a robot according to an embodiment of the present invention.

[0037] Reference numerals:

[0038] 100 Harmonic reducer

[0039] 102 Wave generator

[0040] 104 Rigid gear

[0041] 106 Flexspline

[0042] 108 Transmission input shaft

[0043] 110 Stator

[0044] 112 Rotor

[0045] 114 Transmission output shaft

[0046] 116 Output component

[0047] 118 First reader

[0048] 120 First disk

[0049] 122 Second reader head

[0050] 124 Second disk

[0051] 202 Body part

[0052] 204 Toothed part

[0053] 206 Flange

[0054] 208 Strain gauge

[0055] 300 Robot

[0056] 301 Connecting arm

[0057] 302 Robot joint

[0058] 303 Robot gripper

[0059] Regions A1, A2, A3, A4

[0060] Steps S100 - S200 Detailed implementation manners

[0061] To make the above - mentioned objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0062] It should be understood that although the terms "first", "second", etc. can be used herein to describe various elements, they do not denote any order, quantity, or importance, but are only used to distinguish different components. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present invention, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. Words such as "including" or "comprising" mean that the element or item appearing before this word encompasses the elements or items listed after this word and their equivalents, without excluding other elements or items.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used herein in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0064] As used herein, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0065] Now referring to Figure 1 , a harmonic reducer 100 according to an embodiment of the present invention will be described. Figure 1 FIG. is an axial sectional schematic view of a harmonic reducer 100 according to an embodiment of the present invention.

[0066] In Figure 1 , a harmonic reducer 100 is provided, which includes: a wave generator 102, such as a cam; a rigid gear 104 provided with internal teeth; and a flexible gear 106 disposed between the wave generator 102 and the rigid gear 104 and configured to be able to mesh with the internal teeth of the rigid gear 104. Further, the wave generator 102, the rigid gear 104, and the flexible gear 106 may be arranged substantially coaxially.

[0067] In conjunction with Figure 2 , Figure 2 FIG. is a schematic structural view of a robot joint equipped with a harmonic reducer 100 according to an embodiment of the present invention. As an example, in a robot joint equipped with the harmonic reducer 100, in order to achieve, for example, speed reduction transmission, generally the wave generator 102 of the harmonic reducer 100 is connected to one end of a transmission input shaft 108, and a motor is installed at the other end of the transmission input shaft 108. In Figure 2 the example shown, 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 suitable means. On the other hand, the flexible gear 106 of the harmonic reducer 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, can be installed, for example, at the other end of the transmission output shaft 114. In addition, the rigid gear 104 of the harmonic reducer 100 can also be fixed to the housing of the robot joint by any suitable means.

[0068] When used as a speed reducer, the form of the wave generator 102 being active, the rigid gear 104 being fixed, and the flexible gear 106 outputting is generally adopted. Of course, it should be recognized that in some embodiments, the form of the flexible gear 106 being fixed and the rigid gear 104 being used for output can also be used.

[0069] Specifically, during the operation of using the harmonic reducer 100 for speed reduction transmission, the wave generator 102 rotates together with the rotor 112 of the motor via the transmission input shaft 108. During the rotation of the flexspline 106 along with the wave generator 102, periodic radial deformation occurs. As a result, the teeth of the flexspline 106 mesh with the corresponding teeth on the rigid gear 104, thereby transmitting torque. Further, the rotational speed of the transmission output shaft 114 is reduced by the harmonic reducer 100, thus enabling speed reduction transmission.

[0070] Now refer to Figure 3 , and a description will be given of the flexspline 106 according to an embodiment of the present invention. Figure 3 FIG. is a schematic perspective view of the flexspline 106 of the harmonic reducer 100 according to an embodiment of the present invention.

[0071] In Figure 3 , the flexspline 106 according to an embodiment of the present invention includes: a body portion 202; a toothed portion 204 provided at one end of the body portion 202 and configured to be capable of meshing with the internal teeth of the rigid gear 104; and a flange 206 extending radially outward from the end of the body portion 202 opposite to the toothed portion 204. As Figure 3 shown, the flexspline 106 itself is a cylindrical structure and is thin-walled, thereby being capable of generating elastic deformation. As described above, during the operation of the harmonic reducer 100, under the action of the wave generator 102, the flexspline 106 can undergo periodic radial deformation.

[0072] Further, in an embodiment of the present invention, the harmonic reducer 100 further includes: multiple groups of torque sensors, where each group of the multiple groups of torque sensors includes a plurality of strain gauges, and each group of the multiple groups of torque sensors is respectively used to measure the torque transmitted by the harmonic reducer 100 during the rotation of the flexspline 106, where the signal measured by each group of the multiple groups of torque sensors includes a torque fluctuation amount, and the multiple groups of torque sensors are arranged crosswise; and a processor (not shown) configured to calculate the true torque transmitted by the harmonic reducer according to the signals measured by the multiple groups of torque sensors, where the true torque does not include the torque fluctuation amount.

[0073] In an embodiment of the present invention, each group of the multiple groups of torque sensors can be provided on the flexspline 106 and arranged around the axis of the flexspline 106. Thus, relative to the axis of the flexspline 106, the multiple groups of torque sensors and thus the plurality of strain gauges are located in the same plane. Specifically, in combination with Figure 3As shown, at least one of the multiple sets of torque sensors and thus multiple strain gauges 208 may be disposed in area A1 on the inner side of the flexspline 106, area A2 on the outer side of the body portion 202, area A3 on the side of the flange 206 facing the toothed portion 204, and area A4 on the side of the flange 206 facing away from the toothed portion 204.

[0074] Hereinafter, for ease of description, it is further described with the multiple sets of torque sensors disposed in area A3 on the side of the flange 206 facing the toothed portion 204, but this is not limited herein.

[0075] Now refer to Figure 4 , and a layout pattern of two sets of torque sensors according to an embodiment of the present invention will be described.

[0076] In an embodiment of the present invention, the multiple sets of torque sensors include a first set of torque sensors and a second set of torque sensors. The first set of torque sensors includes four strain gauges, and the second set of torque sensors includes four strain gauges. The strain gauges in the first set of torque sensors and the strain gauges in the second set of torque sensors are arranged crosswise at an interval of 45° from each other.

[0077] Specifically, as Figure 4 shown, in area A3 on the side of the flange 206 facing the toothed portion 204, eight strain gauges 208 are uniformly and annularly arranged with respect to the axis of the flexspline 106, that is, the radial distance of each strain gauge 208 from the axis of the flexspline 106 is equal, and adjacent strain gauges 208 are staggered by 45° with respect to the axis of the flexspline 106. These eight strain gauges 208 are divided into two groups, namely the first set of torque sensors and the second set of torque sensors, and thus the first set of torque sensors and the second set of torque sensors are arranged crosswise. For example, referring to Figure 4 , the strain gauge 208 directly above in the figure is set as the first one, and they are sequentially counted in the clockwise direction. Then, the first set of torque sensors may include the first, third, fifth, and seventh of these eight strain gauges 208, while the second set of torque sensors may include the second, fourth, sixth, and eighth of these eight strain gauges 208. Therefore, each set of torque sensors includes four strain gauges 208. Further, the four strain gauges 208 included in each set of torque sensors form a Wheatstone bridge in order to form a detection circuit to measure the torque transmitted by the harmonic reducer 100 during the rotation of the flexspline 106.

[0078] Further, in some embodiments, the strain gauge 208 may be, for example, a Rosette type strain gauge. As described above, by using eight strain gauges and arranging them symmetrically, as described below, the influence of the torque fluctuation amount in the signal measured by the torque sensor can be effectively eliminated, thereby effectively improving the measurement sensitivity and thus improving the measurement accuracy. Further, the strain gauge 208 may be made of, for example, polyvinylidene fluoride (PVDF), or may be made of other materials suitable for Hall sensors and capacitive sensors. In addition, the strain gauge 208 may be made by, for example, screen printing and then installed on the harmonic reducer 100. Alternatively, the strain gauge 208 may also be directly formed on the harmonic reducer 100 by screen printing.

[0079] Referring again to Figure 2 , further, in some embodiments, the harmonic reducer 100 may further include an angle measuring device configured to measure the angle θ of the wave generator 102 relative to the flexspline 106 during the rotation of the flexspline 106.

[0080] Further, the angle measuring device may include, for example, a first angle sensor and a second angle sensor. The first angle sensor is configured to measure the angle of the wave generator 102 relative to the rigid gear 104 (or a housing or other component fixedly connected to the rigid gear 104) during the rotation of the flexspline 106. The second angle sensor is configured to measure the angle of the flexspline 106 relative to the rigid gear 104 (or a housing or other component fixedly connected to the rigid gear 104) during the rotation of the flexspline 106, thereby measuring the angle θ of the wave generator 102 relative to the flexspline 106 during the rotation of the flexspline 106.

[0081] Specifically, in the Figure 2 example shown, the first angle sensor includes a first reader head 118 and a first disk 120. The first reader head 118 is disposed on a housing fixedly connected to the rigid gear 104, and the first disk 120 is disposed on the wave generator 102. In addition, the second angle sensor includes a second reader head 122 and a second disk 124. The second reader head 122 is disposed on a housing fixedly connected to the rigid gear 104, and the second disk 124 is disposed on the flexspline 106. Combining Figure 3As shown, the second disk 124 may be disposed, for example, in region A4 on a side of the flange 206 facing away from the toothed portion 204. Thus, during rotation of the flexspline 106, the processor can obtain angle data of the flexspline 106 and the wave generator 102 relative to the housing respectively through the first read head 118 and the second read head 122, so as to obtain the angle θ of the wave generator 102 relative to the flexspline 106.

[0082] In addition, it should be recognized that although in the Figure 2 example, both the first disk 120 and the second disk 124 are disposed on the housing, the first disk 120 and the second disk 124 may also be directly disposed on the rigid gear 104.

[0083] In addition, it should be recognized that although in the Figure 2 example, the angle measuring device includes two angle sensors, the angle measuring device may also include only one angle sensor. For example, in this angle sensor, the read head and the disk are respectively disposed on the wave generator 102 and the flexspline 106.

[0084] In addition, in some embodiments, the harmonic reducer 100 may further include a Kalman filter for eliminating high-frequency measurement signal components, so as to further improve the measurement accuracy.

[0085] Now refer to Figure 5 , Figure 5 is a flowchart of a method for measuring the true torque in a harmonic reducer according to an embodiment of the present invention. As shown, another aspect of the present invention provides a method for measuring the torque in a harmonic reducer. As described above, the harmonic reducer may include, for example: a wave generator; a rigid gear provided with internal teeth; a flexspline disposed between the wave generator and the rigid gear and configured to be able to mesh with the internal teeth of the rigid gear; multiple groups of torque sensors, each group of the multiple groups of torque sensors including a plurality of strain gauges, and the multiple groups of torque sensors being arranged crosswise; and a processor.

[0086] The method may include the following steps:

[0087] S100. Measure the torque transmitted by the harmonic reducer during rotation of the flexspline through each group of the multiple groups of torque sensors, wherein the signal measured by each group of the multiple groups of torque sensors includes a torque fluctuation amount; and

[0088] S200. Calculate the true torque transmitted by the harmonic reducer through the processor according to the signals measured by the multiple groups of torque sensors, wherein the true torque does not include a torque fluctuation amount.

[0089] Hereinafter, with reference to Figure 4 , the strain gauge 208 directly above in the figure is set as the first one, and the counting is carried out in the clockwise direction in sequence. The first group of torque sensors includes the second, fourth, sixth, and eighth ones among these eight strain gauges 208, and the second group of torque sensors includes the first, third, fifth, and seventh ones among these eight strain gauges 208. Therefore, each group of torque sensors includes four strain gauges 208. Next, an example will be given for illustration, but this is not limited herein.

[0090] The four strain gauges 208 included in each group of torque sensors thus form a Wheatstone bridge, thereby forming a detection circuit to measure the torque transmitted by the harmonic reducer during the rotation of the flexspline.

[0091] As described above, the amount of torque fluctuation contained in the signals measured by the first group of torque sensors and the second group of torque sensors is related to the angle θ of the wave generator relative to the flexspline, as shown in the following formula (1),

[0092] τ r =τ pr ·sin(2θ) Formula (1)

[0093] where τ r is the amount of torque fluctuation contained in the signal measured by the first group of torque sensors (or the second group of torque sensors), and τ pr is the peak value of the torque fluctuation in the amount of torque fluctuation.

[0094] As described above, since the strain gauges in the first group of torque sensors and the strain gauges in the second group of torque sensors are arranged crosswise at an interval of 45° from each other, there is a phase difference in the torque values measured by the strain gauges in these two groups of torque sensors. Assuming that the second group of torque sensors is delayed by 45° compared with the first group of torque sensors, the torque values measured by the first group of torque sensors and the second group of torque sensors are respectively as shown in the following formula (2) and formula (3),

[0095] τ1 = τ o +τ r =τ o +τ pr ·sin(2θ) Formula (2)

[0096] τ2 = τ o +τ r-45° =τ o +τ pr ·sin(2(θ - 45°)) = τ o +τ pr ·cos(2θ) Formula (3)

[0097] where 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 τ o is the output torque value of the harmonic reducer.

[0098] It should be noted that θ here is the relative angle between the wave generator and the flexspline obtained by taking the position of any strain gauge in the first set of torque sensors as the reference point on the flexspline and the point on the major axis of the elliptical wave generator as the reference point. If other points on the wave generator and the flexspline are selected as the reference points in practical applications, the above calculation formula will be adjusted accordingly, but its principle remains unchanged, and the principle and spirit of this application can still be applied.

[0099] Thereafter, the processor calculates the true torque transmitted by the harmonic reducer according to the torque values measured by the first set of torque sensors and the second set of torque sensors, where the true torque can be free of torque fluctuations. Specifically, through the above formulas (2) and (3), τ o can be calculated through the following formula (4).

[0100]

[0101] Therefore, the output torque value of the harmonic reducer can be as shown in the following formula (5).

[0102]

[0103] Furthermore, the method may further include the following step: eliminating the high-frequency measurement signal components by using a Kalman filter to correct errors and further improve the measurement accuracy.

[0104] Next, with reference to Figure 6 , the arrangement pattern of the three sets of torque sensors according to another embodiment of the present invention will be described. As shown in the figure, in this embodiment, twelve strain gauges 208 are evenly and annularly arranged on the region A3 on the side of the flange 206 facing the toothed portion 204 with respect to the axis of the flexspline 106, that is, the radial distance of each strain gauge 208 with respect to the axis of the flexspline 106 is equal, and the adjacent strain gauges 208 are staggered by 30° with respect to the axis of the flexspline 106. These twelve strain gauges 208 are divided into three groups, namely the first set of torque sensors, the second set of torque sensors, and the third set of torque sensors, and these three sets of torque sensors are arranged crosswise at intervals of 30°. For example, with reference to Figure 6, the strain gauge 208 directly above in the figure is set as the first one, and the counting is carried out in the clockwise direction in turn. Then, the first group of torque sensors may include the third, sixth, ninth, and twelfth of these twelve strain gauges 208, the second group of torque sensors may include the second, fifth, eighth, and eleventh of these twelve strain gauges 208, and the third group of torque sensors may include the first, fourth, seventh, and tenth of these twelve strain gauges 208. Therefore, each group of torque sensors includes four strain gauges 208. In addition, each strain gauge in the second group of torque sensors is 30° ahead of the adjacent strain gauge in the first group of torque sensors, and each strain gauge in the third group of torque sensors is 30° behind the adjacent strain gauge in the first group of torque sensors.

[0105] Further, the four strain gauges 208 included in each group of torque sensors form a Wheatstone bridge to form a detection circuit for measuring the torque transmitted by the harmonic reducer 100 during the rotation of the flexspline 106.

[0106] Similarly, the strain gauge 208 may be, for example, a Rosette type strain gauge. As described above, by using twelve strain gauges and arranging them symmetrically about the center, it is also possible to effectively eliminate the influence of the torque fluctuation amount in the signal measured by the torque sensor, thereby effectively improving the measurement sensitivity and thus improving the measurement accuracy. Further, the strain gauge 208 may also be made of, for example, polyvinylidene fluoride (PVDF), or may be made of other materials suitable for Hall sensors and capacitive sensors. In addition, the strain gauge 208 may also be made by screen printing and then installed on the harmonic reducer 100. Alternatively, the strain gauge 208 may also be directly formed on the harmonic reducer 100 by screen printing.

[0107] Similarly, the torque fluctuation amount contained in the signals measured by the first group of torque sensors, the second group of torque sensors, and the third group of torque sensors is related to the angle θ of the wave generator relative to the flexspline, as shown in the above formula (1),

[0108] τ r =τ pr ·sin(2θ) Formula (1)

[0109] where τ r is the torque fluctuation amount contained in the signal measured by the first group of torque sensors (or the second group of torque sensors or the third group of torque sensors), and τ pr is the peak value of the torque fluctuation in the torque fluctuation amount.

[0110] As described above, since the three sets of torque sensors are arranged crosswise at an interval of 30° from each other, there is a phase difference in the torque values measured by the strain gauges in these 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 respectively shown in the following equations (6), (7), and (8).

[0111] τ4 = τ o + τ r = τ o + τ pr ·sin(2θ) Equation (6)

[0112]

[0113]

[0114] Wherein, 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 τ o is the output torque value of the harmonic reducer.

[0115] It should be noted that θ here is the relative angle between the wave generator and the flexspline obtained by taking the position of any strain gauge in the first set of torque sensors as the reference point on the flexspline and taking the point on the major axis of the elliptical wave generator as the reference point. If other points on the wave generator and the flexspline are selected as the reference points in practical applications, the above calculation formula will be adjusted accordingly, but its principle remains unchanged, and the principle and spirit of this application can still be applied.

[0116] Thereafter, the processor calculates the true torque transmitted by the harmonic reducer according to the torque values measured by the first set of torque sensors, the second set of torque sensors, and the third set of torque sensors, wherein the true torque can be free of torque fluctuation. Specifically, through the above equations (6), (7), and (8), τ o can be calculated by the following equation (9).

[0117] τ o = τ5 + τ6 - τ4 Equation (9)

[0118] Further, in this embodiment, the situation where there is a position error between the three groups of torque sensors is considered. That is, it is assumed that after the second group of torque sensors and the third group of torque sensors are arranged, there are angle deviations of Δα and Δβ with the first group of torque sensors, respectively. Therefore, the second group of torque sensors is ahead of the first group of torque sensors by (30°+Δα), and the third group of torque sensors is delayed by (30°+Δβ) than the first group of torque sensors. Then, the torque values ​​measured by the second group of torque sensors and the third group of torque sensors are respectively as shown in the following equations (10) and (11),

[0119] τ 5′ =τ o +τ r+30° =τ o +τ pr ·sin(2(θ-(30°+Δα))) Formula (10)

[0120]

[0121] Among them, τ 5′ is the torque value measured by the second set of torque sensors, τ 6′ is the torque value measured by the third set of torque sensors.

[0122] Through the above equations (6), (10) and (11), τ can be obtained through the following equation (12): o Perform calculations.

[0123]

[0124] Furthermore, in this embodiment, the high-frequency measurement signal component can also be eliminated by using a Kalman filter, thereby correcting the error and further improving the measurement accuracy.

[0125] In addition, in other embodiments of the present invention, the harmonic reducer may further include a circuit board, and the plurality of torque sensors may be electrically connected to the circuit board. The circuit board is, for example, disposed on a side of the flexible wheel away from the toothed portion, and is fixedly connected to the flexible wheel, for example, by bolting or bonding, so that it can rotate with the rotation of the flexible wheel. In addition, a processor for calculating the real torque, a memory for recording data related to the output torque, and the like may also be mounted on the circuit board.

[0126] In addition, another aspect of the present invention provides a robot joint and a robot. Figure 7, a robot joint and a robot according to an embodiment of the present invention will be described. As shown in the figure, the robot 300 may include a plurality of connecting arms 301, and any two adjacent connecting arms 301 are pivotally connected by corresponding robot joints 302, and these joints 302 may employ the harmonic reducer as described above. The robot 300 further includes a robot gripper 303, one end of the robot gripper 303 is connected to the corresponding connecting arm 301, and at the other end of the robot gripper 303, one or more clamping devices are provided. Thus, the robot 300 can be used to grasp or capture an object. Those of ordinary skill in the art should understand that Figure 7 the structure shown is only an exemplary embodiment of the robot 300. In other embodiments, the robot 300 may include more components or fewer components, such as additional connecting arms and end effectors. Some components (e.g., two or more connecting arms) may be combined, and different or additional types of components from those depicted may be employed. For example, the robot may further include I / O devices, network access devices, communication buses, processors, memories, actuators, and sensors to implement control of the system. For example, the robot 300 may include a processor and a memory storing instructions that, when executed by the processor, cause the processor to implement the control system. The memory may also store instructions that, when executed by the processor, cause the processor to activate or deactivate the robot gripper 303 to capture or release the object to be grasped.

[0127] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0128] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two unless otherwise specifically defined.

[0129] In the present invention, unless otherwise clearly defined or limited, terms such as "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0130] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0131] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

1. A harmonic reducer, comprising: A wave generator; A rigid gear provided with internal teeth; A flexible gear disposed between the wave generator and the rigid gear and configured to be capable of meshing with the internal teeth of the rigid gear; Multiple sets of torque sensors, wherein each set of the multiple sets of torque sensors includes a plurality of strain gauges, and each set of the multiple sets of torque sensors is respectively used to measure the torque transmitted by the harmonic reducer during the rotation of the flexible gear, wherein the signal measured by each set of the multiple sets of torque sensors contains a torque fluctuation amount, and the multiple sets of torque sensors are arranged crosswise; A processor configured to calculate the true torque transmitted by the harmonic reducer according to the signals measured by the multiple sets of torque sensors, wherein the true torque does not contain a torque fluctuation amount; and An angle measuring device configured to measure the angle of the wave generator relative to the flexible gear during the rotation of the flexible gear, Wherein, the multiple sets of torque sensors include 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 in the first set of torque sensors and the strain gauges in the second set of torque sensors are arranged crosswise at an interval of 45° from each other, The processor calculates the true torque according to the following formula: ； Among them, is the true torque transmitted by the harmonic reducer, is the torque value measured by the first set of torque sensors, is the torque value measured by the second set of torque sensors, and θ is the angle of the wave generator relative to the flexspline.

2. The harmonic reducer according to claim 1, characterized in that, The angle measuring device includes a first angle sensor and a second angle sensor, the first angle sensor is configured to measure the angle of the wave generator relative to the rigid gear during the rotation of the flexible gear, the second angle sensor is configured to measure the angle of the flexible gear relative to the rigid gear during the rotation of the flexible gear, thereby measuring the angle of the wave generator relative to the flexible gear during the rotation of the flexible gear.

3. The harmonic reducer according to claim 1, characterized in that Each set of the multiple sets of torque sensors is disposed on the flexible gear and arranged around the axis of the flexible gear.

4. The harmonic reducer according to claim 3, characterized in that The flexible gear includes: A body part; A toothed part disposed at one end of the body part and configured to be capable of meshing with the internal teeth of the rigid gear; and A flange extending radially outward from the end of the body part opposite to the toothed part, Wherein, the multiple sets of torque sensors are disposed on at least one of the inner side of the flexible gear, the outer side of the body part, the side of the flange facing the toothed part, and the side of the flange facing away from the toothed part.

5. A harmonic reducer, comprising: A wave generator; A rigid gear provided with internal teeth; A flexible gear disposed between the wave generator and the rigid gear and configured to be capable of meshing with the internal teeth of the rigid gear; Multiple sets of torque sensors, wherein each set of the multiple sets of torque sensors includes a plurality of strain gauges, and each set of the multiple sets of torque sensors is respectively used to measure the torque transmitted by the harmonic reducer during the rotation of the flexible gear, wherein the signal measured by each set of the multiple sets of torque sensors contains a torque fluctuation amount, and the multiple sets of torque sensors are arranged crosswise; And a processor configured to calculate a real torque transmitted by the harmonic reducer based on signals measured by the plurality of torque sensors, wherein the real torque does not include a torque fluctuation amount, The plurality of groups of torque sensors include a first group of torque sensors, a second group of torque sensors, and a third group of torque sensors, the first group of torque sensors includes four strain gauges, the second group of torque sensors includes four strain gauges, the third group of torque sensors includes four strain gauges, the strain gauges in the first group of torque sensors, the strain gauges in the second group of torque sensors, and the strain gauges in the third group of torque sensors are arranged crosswise at a mutual interval of 30°, each strain gauge in the second group of torque sensors is 30° ahead of the adjacent strain gauge in the first group of torque sensors, and each strain gauge in the third group of torque sensors is 30° behind the adjacent strain gauge in the first group of torque sensors, The processor calculates the true torque according to the following formula: ； Among them, is the true torque transmitted by the harmonic reducer, is the torque value measured by the first set of torque sensors, is the torque fluctuation peak value in the torque fluctuation amount, is the torque value measured by the second set of torque sensors, 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.

6. The harmonic reducer according to claim 5, wherein Each of the plurality of torque sensors is disposed on the flexible spline and arranged around the axis of the flexible spline.

7. The harmonic reducer according to claim 6, wherein The flexible wheel comprises: Body part; a toothed portion, which is disposed at one end of the main body and is configured to mesh with the inner teeth of the rigid wheel; and a flange extending radially outward from an end of the body portion opposite to the toothed portion, The plurality of torque sensors are arranged on at least one of the inner side of the flexible wheel, the outer side of the main body, the side of the flange facing the toothed portion, and the side of the flange away from the toothed portion.

8. A method for measuring torque in a harmonic reducer, the harmonic reducer comprising: Wave generator; A rigid wheel having internal teeth; a flexible wheel, which is disposed between the wave generator and the rigid wheel and is configured to be meshed with the internal teeth of the rigid wheel; A plurality of groups of torque sensors, wherein each group of the plurality of groups of torque sensors comprises a plurality of strain gauges, and the plurality of groups of torque sensors are arranged crosswise; processor; as well as an angle measuring device configured to measure an angle of the wave generator relative to the flexspline during rotation of the flexspline, The method comprises the following steps: Measuring the torque transmitted by the harmonic reducer during the rotation of the flexspline by each of the plurality of torque sensors, wherein the signal measured by each of the plurality of torque sensors includes a torque fluctuation amount; and The processor calculates the real torque transmitted by the harmonic reducer according to the signals measured by the multiple sets of torque sensors, wherein the real torque does not include torque fluctuation. The plurality of groups of torque sensors include a first group of torque sensors and a second group of torque sensors, the first group of torque sensors include four strain gauges, the second group of torque sensors include four strain gauges, the strain gauges in the first group of torque sensors and the strain gauges in the second group of torque sensors are arranged crosswise at an interval of 45° from each other, The processor calculates the true torque according to the following formula: ； Among them, is the true torque transmitted by the harmonic reducer, is the torque value measured by the first set of torque sensors, is the torque value measured by the second set of torque sensors, and θ is the angle of the wave generator relative to the flexspline.

9. The method according to claim 8, characterized in that, The angle measuring device includes a first angle sensor and a second angle sensor. The first angle sensor is configured to measure the angle of the wave generator relative to the rigid gear during the rotation of the flexspline. The second angle sensor is configured to measure the angle of the flexspline relative to the rigid gear during the rotation of the flexspline. Thus, the angle of the wave generator relative to the flexspline is measured during the rotation of the flexspline.

10. The method according to claim 8, wherein Each of the multiple sets of torque sensors is disposed on the flexspline and arranged around the axis of the flexspline.

11. A method for measuring torque in a harmonic reducer, the harmonic reducer comprising: A wave generator; A rigid gear provided with internal teeth; A flexspline disposed between the wave generator and the rigid gear and configured to be meshed with the internal teeth of the rigid gear; Multiple sets of torque sensors, each of the multiple sets of torque sensors including a plurality of strain gauges, and the multiple sets of torque sensors being arranged crosswise; And A processor, The method includes the following steps: Measuring the torque transmitted by the harmonic reducer during the rotation of the flexspline through each of the multiple sets of torque sensors, wherein the signal measured by each of the multiple sets of torque sensors includes a torque fluctuation amount; and Calculating the true torque transmitted by the harmonic reducer by the processor according to the signals measured by the multiple sets of torque sensors, wherein the true torque does not include a torque fluctuation amount, Wherein, the multiple 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 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. The strain gauges in the first set of torque sensors, the strain gauges in the second set of torque sensors, and the strain gauges in the third set of torque sensors are arranged crosswise at intervals of 30°. Each strain gauge in the second set of torque sensors is 30° ahead of the adjacent strain gauge in the first set of torque sensors, and each strain gauge in the third set of torque sensors is 30° behind the adjacent strain gauge in the first set of torque sensors. The processor calculates the true torque according to the following formula: ； Among them, is the true torque transmitted by the harmonic reducer, is the torque value measured by the first set of torque sensors, is the peak value of torque fluctuation in the torque fluctuation amount, is the torque value measured by the second set of torque sensors, 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.

12. The method according to claim 11, wherein Each of the multiple sets of torque sensors is disposed on the flexspline and arranged around the axis of the flexspline.

13. A robot, comprising a plurality of connecting arms, any two adjacent connecting arms being pivotally connected by a robot joint, wherein the robot joint includes a harmonic reducer according to any one of claims 1 to 7.

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