A robot joint and design method thereof

Abstract

The present invention discloses a robot joint and a design method thereof, comprising: a motor assembly and an elastic sleeve type small-tooth-difference planetary reducer assembly arranged in a joint housing; the elastic sleeve type small-tooth-difference planetary reducer assembly comprises: an input shaft arranged in a reducer housing is coaxially matched with the motor outer rotor of the motor assembly, the input end planetary carrier and the output end disk are arranged at both ends of the input shaft through bearing sleeves, and the outer gear disc is movably sleeved at the first eccentric part and the second eccentric part of the input shaft; an inner gear is arranged between the inner walls of the reducer housing corresponding to the outer gear disc; an even number of elastic sleeves are arranged on the outer gear disc along the circumferential direction, and the outer gear disc is meshed with the inner gear; the elastic sleeve is connected to the outer gear disc, the input end planetary carrier and the output end disk through screw pins. The present invention discloses a robot joint and a design method thereof, adopting an elastic sleeve type small-tooth-difference planetary transmission to improve the load-bearing capacity and torque density of the robot joint; reduce backlash and hysteresis, and improve the transmission accuracy of the robot joint.

Description

Technical Field

[0001] The present invention relates to the field of rotary joints, and in particular to a robot joint and a design (execution) method thereof. Background Art

[0002] The planetary transmission mechanism with small tooth difference has the advantages of compact structure, large transmission ratio, strong load-bearing capacity and high transmission efficiency. It has been widely used in many industrial fields, such as metallurgy and mining, aerospace and CNC machine tools, etc. It has also received more and more attention in the field of robot precision transmission and is the main reduction transmission device used in current robot joints.

[0003] However, the existing planetary transmission mechanisms with small tooth difference have ignored the fact that when the gears are meshing, meshing force will be generated between the gear pairs due to meshing contact, which will further cause elastic deformation, thereby changing the ideal design tooth profile of the gears and affecting the transmission accuracy of the mechanism. In addition, most traditional robot joints connect the torque sensor with the motor, reducer and encoder in a superimposed manner. This design solution will lead to the problem of excessive axial thickness of the robot joint, which will seriously restrict the rapid development of robot products. Summary of the invention

[0004] The present invention overcomes the shortcomings of the prior art and provides a robot joint and a design method thereof, which adopts a planetary transmission with a small tooth difference, can obtain a larger number of meshing teeth and a meshing range, thereby further improving the load-bearing capacity of the robot joint; can reduce the transmission error, and improve the transmission accuracy of the robot joint, making the joint more compact and flexible, and having more market application value.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a robot joint, comprising: a joint housing, the joint housing comprising a drive plate cover, an end cover and a shell, the end cover dividing the accommodation space inside the joint housing into an upper accommodation space and a lower accommodation space;

[0006] A driving plate assembly is arranged in the upper accommodation space; a motor assembly and an elastic sleeve type small-tooth-difference planetary reducer assembly drivingly connected to the motor assembly are arranged in the lower accommodation space;

[0007] The elastic sleeve type small-tooth-difference planetary reducer assembly includes: a reducer housing, and an input shaft arranged in the reducer housing, the input shaft is coaxially matched with the motor outer rotor of the motor assembly, the input end planet carriers and the output end disk on the left and right sides are respectively mounted on the two ends of the input shaft through bearing two and bearing seven, and the two outer gear disks are respectively mounted on the first eccentric part and the second eccentric part of the input shaft through bearing five and bearing six; an inner gear is arranged between the inner walls of the reducer housing corresponding to the outer gear disk; elastic sleeves are evenly arranged on the outer gear disk along the circumferential direction, and the outer gear disk is meshed with the inner gear through the elastic sleeve; a screw pin is installed in the middle of the elastic sleeve, one end of which is fixed by a hexagonal nut, and the outer gear disk, the input end planet carrier and the output end disk are connected by the screw pin to realize torque output.

[0008] In a preferred embodiment of the present invention, strain gauges are provided on the four protrusions of the internal gear to form a bridge circuit, which communicates with the drive board assembly via internal wiring, transmits electrical signals to the drive board assembly, and calculates the joint output torque by measuring its strain.

[0009] In a preferred embodiment of the present invention, an even number of elastic sleeves are evenly arranged on the outer gear disc along the circumferential direction; and / or the number of teeth of the inner gear is one more than the number of the elastic sleeves.

[0010] In a preferred embodiment of the present invention, the elastic sleeve is a cylindrical sleeve. During the process of meshing transmission with the internal gear, the elastic sleeve is affected by the contact force and undergoes elastic deformation, changing from a circle to a quasi-ellipse. The circumference before and after the transformation remains unchanged, thereby obtaining the lengths of the minor semi-axis and the major semi-axis.

[0011] In a preferred embodiment of the present invention, a third bearing is provided between the input-end planetary carrier and the reducer housing; and a fourth bearing is provided between the output-end disk and the housing.

[0012] In a preferred embodiment of the present invention, after the elastic sleeve is deformed by force, the major semi-axis and the minor semi-axis of the ellipse are respectively a and b, and the lengths of the major semi-axis and the minor semi-axis are obtained, including the following algorithm;

[0013] ;

[0014] in, is the major semiaxis, is the minor semiaxis, is the radius of the outer ring of the elastic sleeve before deformation, is the eccentricity;

[0015] The corresponding elliptic equation is:

[0016] ;

[0017] The tooth profile of the internal gear is a non-standard cycloid curve, which is determined by the ellipse-like equation The quasi-elliptical profile represented by forms the envelope of a family of curves in relative motion. It is a conjugate curve that is always in tangential contact with the quasi-elliptical wheel. The tooth profile equation of the internal gear is:

[0018] ;

[0019] in, is the ratio of the major and minor semi-axes of the ellipse-like elastic sleeve, is the eccentricity, is the distribution radius of the elastic sleeve, is the number of teeth on the internal gear, is the number of elastic sleeves, satisfying And it is even, and is the angular parameter, and the relationship between the two is determined by the tooth profile equation of the internal gear.

[0020] In a preferred embodiment of the present invention, the internal gear is fixed to the inner wall of the reducer housing; the front end of the protruding part of the internal gear bears the torque, and inner grooves are opened on both sides of the middle to meet the deformation requirements of the strain gauge; the bridge circuit formed by the four strain gauges attached to the protruding part of the internal gear converts the changes of the strain gauge under the action of the torque into a measurable electrical signal, which is transmitted to the drive plate assembly; the ratio of the output torque transmitted by the internal gear to the output torque on the output end disk is ;in, is the number of teeth on the internal gear, is the number of elastic sleeves.

[0021] In a preferred embodiment of the present invention, the first eccentric portion and the second eccentric portion of the input shaft are distributed at 180°;

[0022] and / or,

[0023] The diameter of the smooth rod of the screw pin is equal to the maximum inscribed circle diameter of the overlapping portion of the inner hole of the corresponding elastic sleeve.

[0024] In a preferred embodiment of the present invention, a design method for a robot joint is provided. Based on a robot joint, the elastic sleeve is a cylindrical sleeve. During the process of meshing and transmission between the elastic sleeve and the internal gear, the elastic sleeve is affected by the contact force and elastically deforms from a circle to a quasi-ellipse. The circumference before and after the transformation remains unchanged, thereby obtaining the lengths of the minor semi-axis and the major semi-axis.

[0025] The lengths of the minor semi-axis and the major semi-axis are obtained, including the following algorithms;

[0026] ;

[0027] in, is the major semiaxis, is the minor semiaxis, is the radius of the outer ring of the elastic sleeve before deformation, is the eccentricity; the corresponding ellipse-like equation is:

[0028] ;

[0029] The tooth profile of the internal gear is a non-standard cycloid curve. The envelope of the curve family formed by the above-mentioned elliptical profile in relative motion is a conjugate curve that always maintains tangential contact with it. The tooth profile equation of the internal gear is:

[0030] ;

[0031] in, is the ratio of the major and minor semi-axes of the ellipse-like elastic sleeve, is the eccentricity, is the distribution radius of the elastic sleeve, is the number of teeth on the internal gear, is the number of elastic sleeves, satisfying And it is even, and is an angular parameter, and the relationship between the two can be determined by the tooth profile equation of the internal gear.

[0032] The present invention solves the defects existing in the technical background, and the beneficial technical effects of the present invention are:

[0033] In view of the problems that the reduction transmission device in the existing robot joint has low transmission accuracy due to the tooth side clearance, the involute gear has poor load-bearing capacity, and the robot joint has excessive axial thickness due to the direct stacking connection of torque sensors, the present invention provides a robot joint and a design method thereof.

[0034] 1. The use of elastic sleeve type small tooth difference planetary transmission can obtain a larger number of meshing teeth and meshing range, thereby further improving the load-bearing capacity and torque density of the robot joint.

[0035] 2. When the cycloid gears are meshing, the gear pair will be elastically deformed due to the force. In this regard, the internal gear adopts a non-standard cycloid tooth profile, which can approximate the gear tooth profile after elastic deformation, reduce backlash and hysteresis, and improve the transmission accuracy of the robot joint.

[0036] 3. The present invention utilizes the fact that the internal gear fixed on the reducer housing will undergo a certain elastic deformation when subjected to torque. Therefore, four strain gauges are pasted on the protruding part of the internal gear to form a bridge circuit to measure the torque. This can effectively shorten the axial dimension of the robot joint, thereby making the joint more compact and flexible, and having greater market application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0038] Figure 1 It is a schematic diagram of the overall structure of a preferred embodiment of the present invention;

[0039] Figure 2 It is a schematic diagram of the structure explosion of a preferred embodiment of the present invention;

[0040] Figure 3 is an isometric view of the input shaft of the preferred embodiment of the present invention;

[0041] Figure 4 It is a front view of the internal gear 1 (or internal gear 2) and the strain gauge 1 (strain gauge 2) after matching in the preferred embodiment of the present invention;

[0042] Figure 5 It is a front view of the outer gear disc 1 (or outer gear disc 2) and the elastic sleeve 1 (elastic sleeve 2) after being matched in the preferred embodiment of the present invention;

[0043] Figure 6 This is a front view of the elastic sleeve 1 and the elastic sleeve 2 after being matched with the screw pin in the preferred embodiment of the present invention;

[0044] Figure 7 is a meshing schematic diagram of a gear pair according to a preferred embodiment of the present invention;

[0045] Figure 8 yes Figure 7 The meshing diagram shows the change of tooth profile before and after the elastic sleeve 1 and the elastic sleeve 2 are meshed and subjected to force;

[0046] Fig. 9 yes Figure 7 The meshing diagram shown is a tooth profile curve of the internal gear and a meshing diagram of the tooth profile after the elastic sleeve is deformed;

[0047] In the figure, 1, drive plate cover, 2, drive plate assembly, 3, end cover, 4, bearing 1, 5, outer rotor, 6, magnetic ring, 7, input shaft, 7a-first eccentric part, 7b-second eccentric part, 8, bearing 2, 9, input end planetary frame, 10, screw pin, 11, hexagonal nut, 12, bearing 3, 13, right casing, 14, reducer housing, 15, inner stator core and winding, 16, outer rotor magnetic ring, 17, motor housing, 18, hexagon socket head screw, 19, housing, 20, elastic sleeve 1, 20c -tooth profile after deformation of elastic sleeve, 21, internal gear 1, 21a-groove 1, 21b-protrusion 1, 21c-tooth profile curve of internal gear, 22, elastic sleeve 2, 23, internal gear 2, 23a-groove 2, 23b-protrusion 2, 24, bearing 4, 25, output end plate, 26, bearing 5, 27, bearing 6, 28, bearing 7, 29, external gear disc 1, 29a-semicircular groove 1, 30, external gear disc 2, 30a-semicircular groove 2, 31, strain gauge 1, 32, strain gauge 2, 33, slotted cylindrical head screw, O 20c -Oval elastic sleeve distribution circle center, O 21c -Center of the internal gear. DETAILED DESCRIPTION

[0048] The present invention will now be further described in detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0049] It should be noted that if there are directional indications (such as up, down, bottom, top, etc.) involved in the embodiments of the present invention, the directional indication is only used to explain the relative position relationship, movement, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly. The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Unless otherwise clearly specified and defined, the terms "set", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Embodiment 1

[0050] like Figure 1-Figure 9As shown, a robot joint includes a joint housing composed of a drive plate cover 1, an end cover 3 and a shell 19, the end cover 3 divides the entire housing internal accommodating space into an upper accommodating space and a lower accommodating space, the upper accommodating space is provided with a drive plate assembly 2; the lower accommodating space is provided with a motor assembly and a small-tooth-difference planetary reducer assembly; the small-tooth-difference planetary reducer assembly includes: a reducer housing 14 and an input shaft 7 arranged in the housing 14, the input shaft 7 is coaxially matched with an outer rotor 5, and bearings 28 and 29 are provided at both ends of the input shaft 7, which are respectively connected to the input end planetary carrier 9 and the output The output disk 25 is matched, and the first eccentric part 7a and the second eccentric part 7b of the input shaft 7 are respectively provided with bearing five 26 and bearing six 27 to match the two outer gear disks. The inner wall of the reducer housing 14 corresponding to the outer gear disk is directly provided with an inner gear. An even number of elastic sleeves are evenly provided on the outer gear disk along the circumferential direction, and the number of teeth of the inner gear is one more than the number of elastic sleeves, and the inner gear is meshed with the inner gear; strain gauges are provided on the four protrusions of the inner gear to form a bridge circuit, which communicates with the drive board assembly 2 through internal wiring to transmit electrical signals in sequence, and the torque is solved by measuring its strain. The elastic sleeve 13 is a cylindrical sleeve, which is pressed between the inner gear and the outer gear disk. After being deformed by force, it presents an elliptical shape. A screw pin 10 is installed in the middle of the elastic sleeve, and one end is fixed by a hexagonal nut 11, and the outer gear disk, the input end planetary carrier 9 and the output disk 25 are connected by the screw pin 10 to achieve torque output. The torque output is completed by connecting the outer gear disk, the input end planetary carrier 9 and the output end disk 25; a bearing three 12 is arranged between the input end planetary carrier 9 and the reducer housing 14; a bearing four 24 is also arranged between the output end disk 25 and the outer shell 19. The right housing 13 is fixedly connected to the outer shell 19 by an inner slotted cylindrical head screw 33, and the outer rotor magnetic ring 16 is evenly distributed inside the motor housing 17 to form the rotor of the motor, and forms an outer rotor motor structure with the inner stator core and the winding 15, and the end cover 3 is fixedly connected to the outer shell 19 by an inner hexagonal cylindrical head screw 18. Further, in this embodiment, the bearing two 8 and the bearing seven 28 are deep groove ball bearings, the bearing five 26 and the bearing six 27 are needle bearings, and the bearing three 12 and the bearing four 24 are deep groove ball bearings. Embodiment 2

[0051] like Figure 1-Figure 9As shown, a robot joint includes a joint housing composed of a drive plate cover 1, an end cover 3 and a shell 19, the end cover 3 divides the entire housing internal accommodating space into an upper accommodating space and a lower accommodating space, the upper accommodating space is provided with a drive plate assembly 2; the lower accommodating space is provided with a motor assembly and an elastic sleeve type small tooth difference planetary reducer assembly; the elastic sleeve type small tooth difference planetary reducer assembly includes: a reducer housing 14 and an input shaft 7 arranged in the housing 14, the input shaft 7 is coaxially matched with the motor outer rotor 16, the two ends of the input shaft 7 are provided with bearings 28 and bearings 28 respectively matched with the input end planetary carrier 9 and the output end disk 25, the first eccentric portion 7a and the second eccentric portion 7b of the input shaft 7 are respectively provided with bearings 5 ​​26 and bearings 6 27 and the outer toothed disk 1 29 of the two outer toothed disks Cooperating with the outer gear disc 2 30, the internal gears directly arranged on the inner wall of the reducer housing 14 corresponding to the outer gear disc 1 29 and the outer gear disc 2 30 include an inner gear 1 21 and an inner gear 2 23, and an even number of elastic sleeves uniformly arranged along the circumferential direction on the outer gear disc 1 29 and the outer gear disc 2 30 include an elastic sleeve 1 20 and an elastic sleeve 22, and the number of teeth of the inner gear 1 21 and the inner gear 2 23 is one more than that of the elastic sleeve 1 20 and the elastic sleeve 2 22, and they cooperate and mesh with the inner gear 1 21 and the inner gear 2 23; strain gauges 1 31 and strain gauges 2 32 are arranged on the protrusion 1 21b and the protrusion 2 23b of the four protrusions of the inner gear 1 21 and the inner gear 2 23, forming a bridge circuit, communicating with the drive board assembly 2 through internal wiring, transmitting electrical signals in sequence, and solving the torque by measuring the strain. Furthermore, the specific structure of the bridge circuit formed by the strain gauge 1 31 and the strain gauge 2 32 adopts the general bridge circuit structure in the prior art, and the specific bridge circuit structure is not described one by one here. The line connection relationship adopts the general connection relationship in the prior art, as long as it can realize the formation of communication and transmit electrical signals in sequence. The elastic sleeve 1 20 and the elastic sleeve 2 22 of the elastic sleeve are cylindrical sleeves, which are respectively pressed between the inner gear 1 21 and the inner gear 2 23 and the outer gear disc 1 29 and the outer gear disc 2 30. After being deformed by force, they present an elliptical shape. A screw pin 10 is installed in the middle of the elastic sleeve 1 20 and the elastic sleeve 2 22, and one end is fixed by a hexagonal nut 11, and the outer gear disc 1 29 and the outer gear disc 2 30, the input end planetary carrier 9 and the output end disc 25 are connected through it to complete the torque output; a bearing 3 12 is arranged between the input end planetary carrier 9 and the reducer housing 14; a bearing 4 24 is also arranged between the output end disc 25 and the outer shell 19. Furthermore, in this embodiment, bearing two 8 and bearing seven 28 adopt deep groove ball bearings, bearing five 26 and bearing six 27 adopt needle bearings, and bearing three 12 and bearing four 24 adopt deep groove ball bearings. Embodiment 3

[0052] like Figure 1-Figure 9As shown, a robot joint includes a joint housing composed of a drive plate cover 1, an end cover 3 and an outer shell 19, the end cover 3 divides the entire housing internal accommodating space into an upper accommodating space and a lower accommodating space, the upper accommodating space is provided with a drive plate assembly 2; the lower accommodating space is provided with a motor assembly and a small-tooth difference planetary reducer assembly; the small-tooth difference planetary reducer assembly includes: a reducer housing 14 and an input shaft 7 arranged in the housing 14, the input shaft 7 is coaxially matched with an outer rotor 5, both ends of the input shaft 7 are provided with bearings 2 8 and bearings 7 28 respectively matched with the input end planetary carrier 9 and the output end disk 25, the first eccentric portion 7a and the second eccentric portion 7b of the input shaft 7 are respectively provided with bearings 5 ​​26 and bearings 6 27 and the outer toothed disks of the two outer toothed disks The inner gear directly arranged on the inner wall of the reducer housing 14 corresponding to the outer gear disc 1 29 and the outer gear disc 2 30 includes an inner gear 1 21 and an inner gear 2 23. The even number of elastic sleeves evenly arranged along the circumferential direction on the outer gear disc 1 29 and the outer gear disc 2 30 include an elastic sleeve 1 20 and an elastic sleeve 2 22, and the number of teeth of the inner gear is one more than the number of elastic sleeves, and the inner gear 1 21 and the inner gear 2 23 are meshed with each other; the strain gauges 1 31 and the strain gauges 2 32 are arranged on the protrusion 1 21b and the protrusion 2 23b of the four protrusions of the inner gear 1 21 and the inner gear 2 23, forming a bridge circuit, communicating with the drive board assembly 2 through internal wiring, transmitting electrical signals in sequence, and solving the torque by measuring its strain. Further, the specific structure of the bridge circuit formed by the strain gauges 1 31 and the strain gauges 2 32 adopts the general bridge circuit structure in the prior art, and the specific bridge circuit structure is not repeated here one by one. The line connection relationship adopts the general connection relationship in the prior art, as long as it can realize the formation of communication and the transmission of electrical signals in sequence. The elastic sleeve 1 20 and the elastic sleeve 2 22 of the elastic sleeve are cylindrical sleeves, which are respectively pressed between the inner gear 1 21 and the inner gear 2 23 and the outer gear disc 1 29 and the outer gear disc 2 30. After being deformed by force, they present an elliptical shape. A screw pin 10 is installed in the middle of the elastic sleeve 1 20 and the elastic sleeve 2 22, and one end is fixed by a hexagonal nut 11, and the outer gear disc 1 29 and the outer gear disc 2 30, the input end planetary carrier 9 and the output end disc 25 are connected through it to complete the torque output; a bearing 3 12 is arranged between the input end planetary carrier 9 and the reducer housing 14; a bearing 4 24 is also arranged between the output end disc 25 and the housing 19. Further, in this embodiment, the bearing 2 8 and the bearing 7 28 are deep groove ball bearings, the bearing 5 26 and the bearing 6 27 are needle bearings, and the bearing 3 12 and the bearing 4 24 are deep groove ball bearings.

[0053] In one embodiment, Figure 5-Figure 8As shown, the inner gears 21 and 23 are evenly provided with four protrusions 1 21b and 23b of the same structure along the circumferential direction, and grooves 1 21a and 23a with a length of 5-7mm and a depth of 1-2mm are opened on both sides of the protrusions 1 21b and 23b, so that the strain gauges 1 31 and 232 attached thereto can indirectly measure the strain generated by the protrusions due to the load without directly bearing the pressure generated by the load, and then calculate the generated torque through the formed bridge circuit. The outer gear disc 1 29 and the outer gear disc 2 30 are evenly provided with 8 semicircular grooves 1 29a and semicircular grooves 2 30a of the same size along the circumferential direction, respectively, and cooperate with the elastic sleeve 1 20 and the elastic sleeve 2 22 to form the gear teeth of the meshing transmission of the outer gear disc and the inner gear, thereby avoiding the processing of the outer gear disc with complex tooth profile, which not only facilitates the maintenance and replacement of the outer gear disc teeth, but also effectively reduces the manufacturing difficulty and manufacturing cost. In view of the fact that the two outer gear discs 1 29 and the outer gear disc 2 30 are at a phase angle of 180°, and their respective eccentricities are Placed, there is a gap between the elastic sleeve 1 20 or the elastic sleeve 2 22 located on the same screw pin 10. The eccentricity of the screw pin 10 is (in It is the inner circle radius of the elastic sleeve 1 20 or the elastic sleeve 2 22), and the output torque is transmitted to the output end plate 25 through multiple screw pins 10. Each screw pin 10 can share a part of the output torque, which ensures that each screw pin 10 will not cause structural damage due to excessive output torque, further ensuring the stability and durability of the system structure. Embodiment 4

[0054] Based on the first embodiment, in one of the embodiments, as Figure 8-Figure 9 As shown in the figure, the cylindrical tooth profile of the elastic sleeve will undergo elastic deformation after meshing and present a tooth profile quasi-elliptical cylinder. At this time, the major and minor semi-axes and tooth profile equations of the quasi-elliptical cylinder elastic sleeve are expressed as:

[0055] ;

[0056] in, is the major semiaxis, is the minor semiaxis, is the radius of the outer ring of the elastic sleeve before deformation, is the eccentricity; the conjugate curve of the internal gear generated by the envelope of such an elliptical cylindrical elastic sleeve is expressed as follows:

[0057] ;

[0058] in, is the ratio of the major and minor semi-axis of the ellipse. is the eccentricity, is the distribution radius of the elastic sleeve, is the number of teeth on the internal gear, is the number of elastic sleeves, satisfying And it is even, and is the angle parameter, and the relationship between the two is determined by the meshing equation in the above formula.

[0059] Furthermore, a and b are the major and minor axes of the ellipse-like shape formed after the elastic sleeve is deformed by force; a and b are the major and minor axes of the ellipse-like shape, Fig. 9 Schematically shows the generated tooth profile curve 21c of the internal gear and the deformed tooth profile 20c of the elastic sleeve which is elliptical and formed after the elastic body is deformed by force. Embodiment 5

[0060] Based on the third embodiment, in one of the embodiments, Figure 8-Figure 9 As shown, the cylindrical tooth profiles of the elastic sleeve 1 20 and the elastic sleeve 2 22 will undergo elastic deformation after meshing and force, presenting a tooth profile quasi-elliptical cylinder. At this time, the major and minor semi-axes and tooth profile equations of the quasi-elliptical cylinder-shaped elastic sleeve 1 20 and the elastic sleeve 2 22 are expressed as:

[0061] ;

[0062] in, is the major semiaxis, is the minor semiaxis, is the radius of the outer ring of the elastic sleeve 1 20 or the elastic sleeve 2 22 before deformation, is the eccentricity; the conjugate curve of the internal gear generated by the envelope of such an elliptical cylindrical elastic sleeve 20 or an elastic sleeve 22, the equation of which is:

[0063] ;

[0064] in, is the ratio of the major and minor semi-axis of the ellipse. is the eccentricity, is the distribution radius of the elastic sleeve 1 20 or the elastic sleeve 2 22, is the number of teeth of internal gear 1 21 or internal gear 2 23, is the number of elastic sleeves 1 20 or elastic sleeves 2 22, satisfying And it is even, and is the angle parameter, and the relationship between the two is determined by the conjugate curve of the internal gear. Embodiment 6

[0065] On the basis of any one of the embodiments in the first to third embodiments, the motor assembly includes: a magnetic ring 6, an outer rotor 5, an inner stator core and winding 15, and an outer rotor magnetic ring 16 that are assembled in cooperation with each other. Specifically, the assembly drive connection relationship adopts the assembly structure in the prior art. For example: the installation of the outer rotor magnetic ring 16 and the outer rotor 5: the outer rotor magnetic ring 16 and the groove installed on the side of the outer rotor 5 are flush with the inner side of the outer rotor 5, and the two are in a concentric relationship and are assembled in sequence. Installation of the inner stator core and winding 15: the inner stator winding is wound on the inner stator core according to the design requirements. The assembled inner stator is placed in the motor housing 17, and after the inner stator is fixed, the outer rotor 5 is installed around the inner stator to ensure that there is an appropriate air gap between the outer rotor 5 and the inner stator core. However, it is not limited to this, and the specific product model drive connection relationship selected by the motor assembly is not repeated and listed one by one here, as long as the drive of the motor assembly required in this embodiment can be basically achieved. Embodiment 7

[0066] like Figure 1-Figure 9 As shown, based on any one of the embodiments 1 to 6, a method for designing a robot joint is as follows:

[0067] The cylindrical tooth profile of the elastic sleeve 1 20 or the elastic sleeve 2 22 will undergo elastic deformation after meshing and present a tooth profile that is quasi-elliptical. At this time, the major and minor semi-axes and tooth profile equations of the quasi-elliptical elastic sleeve 1 20 or the elastic sleeve 2 22 are:

[0068] ;

[0069] in, is the major semiaxis, is the minor semiaxis, is the radius of the outer ring of the elastic sleeve 1 20 or the elastic sleeve 2 22 before deformation, is the eccentricity; the conjugate curve of the internal gear generated by the envelope of such an elliptical cylindrical elastic sleeve 20 or elastic sleeve 22 is as follows:

[0070] ;

[0071] in, is the ratio of the major and minor semi-axis of the ellipse. is the eccentricity, is the distribution radius of the elastic sleeve 1 20 or the elastic sleeve 2 22, is the number of teeth of internal gear 1 21 or internal gear 2 23, is the number of elastic sleeves 1 20 or elastic sleeves 2 22, satisfying And it is even, and is an angular parameter, and the relationship between the two can be determined by the conjugate curve equation of the internal gear.

[0072] Working principle:

[0073] The present invention provides a robot joint and a design method thereof; an elastic sleeve type small tooth difference planetary transmission is adopted to obtain a larger number of meshing teeth and a meshing range, thereby further improving the load-bearing capacity and torque density of the robot joint. Considering the meshing of cycloid gear teeth, the gear pair will undergo elastic deformation due to the force. In this regard, the internal gear adopts a non-standard cycloid tooth profile, which can approximate the gear tooth profile after elastic deformation, can reduce backlash and hysteresis, and improve the transmission accuracy of the robot joint. The present invention utilizes that the internal gear 1 21 and the internal gear 2 23 fixed on the reducer housing 14 will undergo a certain elastic deformation when subjected to torque. Therefore, four strain gauges 1 and strain gauge 2 are pasted on the protruding parts of the internal gear 1 21 and the internal gear 2 23 to form a bridge circuit to measure the torque size, which can effectively shorten the axial size of the robot joint, thereby making the joint more compact and flexible, and more marketable.

[0074] The above specific implementation methods are specific support for the scheme ideas proposed in the present invention, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or equivalent modifications made on the basis of this technical scheme in accordance with the technical ideas proposed in the present invention still fall within the scope of protection of the technical scheme of the present invention.

Claims

1. A robot joint, characterized in that: include: A joint housing, the joint housing comprising a drive plate cover, an end cover and a housing, the end cover dividing the accommodation space inside the joint housing into an upper accommodation space and a lower accommodation space; A driving plate assembly is arranged in the upper accommodation space; a motor assembly and an elastic sleeve type small-tooth-difference planetary reducer assembly drivingly connected to the motor assembly are arranged in the lower accommodation space; The elastic sleeve type small-tooth-difference planetary reducer assembly comprises: a reducer housing, and an input shaft arranged in the reducer housing, the input shaft is coaxially matched with the motor outer rotor of the motor assembly, the input end planet carriers and the output end disk on the left and right sides are respectively sleeved on the two ends of the input shaft through bearing two and bearing seven, and the two outer gear disks are respectively sleeved on the first eccentric part and the second eccentric part of the input shaft through bearing five and bearing six; an inner gear is arranged between the inner walls of the reducer housing corresponding to the outer gear disk; elastic sleeves are evenly arranged on the outer gear disk along the circumferential direction, and the outer gear disk and the inner gear are meshed through the elastic sleeve; a screw pin is installed in the middle of the elastic sleeve, one end of which is fixed by a hexagonal nut, and the outer gear disk, the input end planet carrier and the output end disk are connected by the screw pin to realize torque output; The elastic sleeve is a cylindrical sleeve, which is press-fitted between the inner gear and the outer gear disc, and presents an elliptical shape after being deformed by force; During the process of meshing transmission between the elastic sleeve and the internal gear, the elastic sleeve is elastically deformed due to the contact force; The elastic sleeve is transformed from a circle to a quasi-ellipse, and the circumference before and after the transformation remains unchanged, thereby obtaining the lengths of the minor and major semi-axis.

2. A robot joint according to claim 1, characterized in that: Strain gauges are provided on the four protrusions of the internal gear to form a bridge circuit, which communicates with the drive board assembly via internal wiring, transmits electrical signals to the drive board assembly, and calculates the joint output torque by measuring the strain.

3. A robot joint according to claim 2, characterized in that: An even number of elastic sleeves are evenly arranged on the outer gear disc along the circumferential direction; and / or the number of teeth of the inner gear is one more than the number of the elastic sleeves.

4. A robot joint according to claim 3, characterized in that: A third bearing is arranged between the input end planetary carrier and the reducer housing; and a fourth bearing is arranged between the output end disk and the housing.

5. A robot joint according to claim 4, characterized in that: After the elastic sleeve is deformed by force, the major semi-axis and the minor semi-axis of the ellipse are formed respectively, and the lengths of the major semi-axis and the minor semi-axis are obtained, including the following algorithm; ； Among them, a is the major semi-axis, b is the minor semi-axis, R is the radius of the outer ring of the elastic sleeve before deformation, and e is the eccentricity; The corresponding elliptic-like equation is expressed as: ； The tooth profile of the internal gear is a non-standard cycloid curve, which is determined by the ellipse-like equation The quasi-elliptical profile represented by forms the envelope of a family of curves in relative motion. It is a conjugate curve that is always in tangential contact with the quasi-elliptical wheel. The tooth profile equation of the internal gear is: ； Among them, k is the ratio of the major semi-axis to the minor semi-axis of the ellipse of the elastic sleeve, e is the eccentricity, is the distribution radius of the elastic sleeve, is the number of teeth on the internal gear, is the number of elastic sleeves, satisfying And it is even, and is the angular parameter, and the relationship between the two is determined by the tooth profile equation of the internal gear.

6. A robot joint according to claim 5, characterized in that: The internal gear is fixed to the inner wall of the reducer housing; the front end of the protruding part of the internal gear bears the torque, and inner grooves are opened on both sides of the middle to meet the deformation requirements of the strain gauge; the bridge circuit formed by the four strain gauges attached to the protruding part of the internal gear converts the changes of the strain gauge under the action of torque into a measurable electrical signal, which is transmitted to the drive board assembly; The ratio of the output torque transmitted by the internal gear to the output torque on the output end disc is ;in, is the number of teeth on the internal gear, is the number of elastic sleeves.

7. A robot joint according to claim 6, characterized in that: The first eccentric portion and the second eccentric portion of the input shaft are distributed at 180 degrees; and / or, The diameter of the smooth rod of the screw pin is equal to the maximum inscribed circle diameter of the overlapping portion of the inner hole of the corresponding elastic sleeve.

8. A method for designing a robot joint, characterized in that: Based on a robot joint according to any one of claims 1 to 7, the elastic sleeve is a cylindrical sleeve, and in the process of meshing transmission with the internal gear, the elastic sleeve is affected by the contact force, and elastic deformation occurs on the elastic sleeve, changing from a circle to a quasi-ellipse, and the circumference before and after the transformation remains unchanged, thereby obtaining the lengths of the minor semi-axis and the major semi-axis; Obtaining the lengths of the minor and major semi-axis, including the following algorithms; ； Among them, a is the major semi-axis, b is the minor semi-axis, R is the radius of the outer ring of the elastic sleeve before deformation, and e is the eccentricity; the corresponding ellipse-like equation is expressed as: ； The tooth profile of the internal gear is a non-standard cycloid curve. The envelope of the curve family formed by the above-mentioned elliptical profile in relative motion is a conjugate curve that always maintains tangential contact with it. The tooth profile equation of the internal gear is: ； Among them, k is the ratio of the major semi-axis to the minor semi-axis of the ellipse of the elastic sleeve, e is the eccentricity, is the distribution radius of the elastic sleeve, is the number of teeth on the internal gear, is the number of elastic sleeves, satisfying And it is even, and is an angular parameter, and the relationship between the two can be determined by the tooth profile equation of the internal gear.

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