Compact type humanoid arm robot joint

Abstract

The invention relates to a compact type robot joint of a humanoid arm. The compact type robot joint comprises a flexible touch sensor, a joint control cavity, a joint cavity, a joint mechanical transmission part and a joint rotating body. The length of the joint cavity is 116 + / -5 mm, the diameter of the joint cavity is 90 + / -5 mm, and the outer diameter of the whole joint is 85-95 mm and is close to the size of the upper limb of a human body; the joint mechanical transmission part is composed of two parallel transmission chains, each transmission chain comprises a motor and speed reducer module and is composed of an encoder, a direct-current frameless motor, a planetary speed reducer, a bearing and an outer frame, the motor and speed reducer modules are packaged into an overall module with the diameter smaller than 45 mm and the total axial height smaller than 110 mm, and the overall module is fixed in a joint cavity through bolts. The encoder, the direct-current frameless motor and the planetary reducer are sequentially connected together from top to bottom through the bearing, the outer frame packages the encoder, the direct-current frameless motor and the area where the bearing is located, and power is transmitted to the planetary reducer in the motor and reducer module.

Description

Technical Field

[0001] This invention relates to the field of service robot technology, specifically a compact humanoid robot joint. Background Technology

[0002] Joints are fundamental to robot development. Currently, most robot joints are serial structures, where a motor drives an output link to rotate after being reduced in speed. In scenarios where joint size is constrained but heavy loads are required, such as when a nursing robot needs to assist or lift someone, traditional serial joints struggle to balance structural dimensions and output torque requirements. Under heavy load demands, the robot arm becomes bulky. Furthermore, the complexity of traditional serial structures, their lack of human-like resemblance to a human arm, and the resulting resistance from those being cared for are also problematic. The complex shape also makes it difficult to attach tactile sensors, hindering the optimization of human-robot interaction and significantly limiting the practical application of existing humanoid service robots.

[0003] If the applicant has previously applied for CN202210361782.6, although it can achieve high load and has a smooth appearance, its joint size is large, its overall volume is large, and it differs greatly from the human upper limb. As a nursing robot, it has a poor user experience and is inconvenient to use for lifting bedridden patients.

[0004] Therefore, the applicant further improved the design and provided a robot joint that can simultaneously meet the requirements of high load, smooth shape, low weight, compact size close to the size of human upper limb, and can integrate flexible tactile sensors. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of large size and low output torque in existing robot joints, and to propose a robot joint that is compact, has a large load capacity, is highly modular, has a smooth surface, and is equipped with a matching tactile skin sensor. The robotic arm composed of this joint has a protruding shape that does not affect the comfort of human-machine contact, and is convenient for picking up bedridden patients, etc.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A compact humanoid robotic joint includes a flexible tactile sensor 1, a joint control cavity 2, a joint cavity 3, a joint mechanical transmission part 4, and a joint rotating body 5. The flexible tactile sensor 1 is connected to the joint control cavity 2 and the joint cavity 3 by adhesive bonding. The joint control cavity 2 includes a joint connector 21, two actuators 22, a data acquisition board 23, and two cavity shells 24. The joint cavity 3 has a length of 116mm±5 and a diameter of 90±5mm. The length, width, and height of the actuators are 42±2mm, 30±2mm, and 20±2mm, respectively. The outer diameter of the entire joint is 85~95mm, which is close to the size of the human upper limb. The joint mechanical transmission part 4 consists of two parallel transmission chains, and the parts of the joint mechanical transmission part 4 are respectively fixed on the joint cavity 3 and the joint rotating body 5. Each transmission chain includes a motor and reducer module, bearing retaining ring, worm, worm wheel, driving bevel gear, and worm bearing. Two transmission chains are connected together via bevel gear shafts, and the driving bevel gears of both transmission chains mesh with the same driven bevel gear. The motor and reducer module 41 consists of an encoder 411, a frameless DC motor 412, a planetary reducer 413, a bearing 414, and an outer frame, packaged into a single module with a diameter less than 45mm and a total axial height of less than 110mm. It is fixed in the joint cavity 3 with bolts. The encoder 411, frameless DC motor 412, and planetary reducer 413 are connected together sequentially from top to bottom via bearings. The outer frame encapsulates the area containing the encoder 411, frameless DC motor 412, and bearings. Power is transmitted internally to the planetary reducer 413; one end of the worm bearing 43 rests on the shoulder of the worm 44, and the other end contacts and is positioned with one end of the bearing retaining ring 42; the other end of the bearing retaining ring 42 contacts and is positioned with the motor mounting base 31; the power output of the planetary reducer 413 is transmitted to the worm 44, which meshes with the worm wheel 45 of the same module. The worm wheel 45 and the driving bevel gear 46 are fixed together on one end of the bevel gear shaft by bolts; the driving bevel gear 46 meshes with the driven bevel gear 47 of the same module; the other end of the bevel gear shaft is connected to the worm wheel of the second transmission chain; the driving bevel gear 46 is fixed on the inner side of the opposite face of the two worm wheels 45, and both driving bevel gears 46 mesh with the driven bevel gear 47. The distance between the two worm wheels is less than the distance between the two lugs of the joint cavity 3.

[0007] The components above the meshing position of the worm 44 and worm wheel 45 are installed inside the joint cavity 3, while the components below the meshing position of the worm 44 and worm wheel 45 are installed in the space between the joint rotating body 5 and the joint cavity 3.

[0008] Furthermore, the planetary reducer P35H has a diameter of 35mm and a length of 47.4mm. The maximum diameter of the motor and reducer module is 40mm. The frameless DC motor is a KR3812WF motor with a diameter of 38mm, and the driver is an ELMO G-SOLTWI15 / 100SE1S driver.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The robot joint of this invention has a compact size, small radial dimension, and reasonable internal space occupancy. Utilizing a differential structure, the joint allows for two perpendicular rotational axes, enabling rotation in two directions while providing a large output torque to withstand heavy loads. Innovatively, the motor, planetary reducer, and worm gear are arranged on a single axis. Compared to a structure where the motor and planetary reducer are placed side-by-side, this simplifies the joint cavity structure and allows for direct fixing to the joint control cavity, reducing the number of parts, simplifying assembly, and improving the overall integrity and structural strength of the joint. Simultaneously, it reduces transmission losses and eliminates the need for space for motor wiring. A small frameless DC motor with a small axial dimension is used, and the motor, encoder, and reducer are integrated into a single package. These improvements collectively reduce the radial dimension of the joint, bringing the overall joint outer diameter down to 90mm, close to the size of a human upper limb. This facilitates actions such as supporting and lifting, improving the nursing experience.

[0010] 2. The robot joint of the present invention is equipped with a flexible tactile sensor and a data acquisition board. The flexible tactile sensor can sense the tactile pressure information outside the robot joint. The data acquisition board includes two parts: one part is responsible for collecting tactile pressure information and motor feedback information, and the other part is a power module that supplies power to the controller and the driver.

[0011] 3. This invention places all components (except the tactile skin sensor) within the cavities of the joint. The overall structure is smooth, simple, compact, and easy to install and maintain, making the robot joint a highly integrated module that can be used independently or in conjunction with other components or several identical modules. This invention can be entirely housed within the robot body, with electrical connections to the outside world via a single cable, facilitating control bus setup without affecting the robot's overall structure and allowing for convenient aesthetic design. The smooth outer surface of the joint structure allows for the attachment of tactile sensors, thereby enhancing human-computer interaction capabilities. Attached Figure Description

[0012] Figure 1 This is a three-dimensional structural diagram of a robot joint according to an embodiment of the present invention; Figure 2 This is a three-dimensional structural diagram of a robot joint according to an embodiment of the present invention; Figure 3 This is a three-dimensional structural diagram of the control joint cavity of a robot joint according to an embodiment of the present invention; Figure 4 This is a three-dimensional structural diagram of the joint connector of the robot joint according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the joint cavity structure of a robot joint according to an embodiment of the present invention; Figure 6This is a three-dimensional structural diagram of the motor mounting base of the robot joint according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the joint mechanical transmission part of a robot joint according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the motor and reducer module structure of the robot joint according to an embodiment of the present invention; Figure 9 This is a schematic diagram of a dual-joint assembly of a robot joint according to an embodiment of the present invention. Detailed Implementation

[0013] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention and do not limit the scope of protection of the claims of this application.

[0014] The present invention provides a compact humanoid arm robotic joint, such as... Figures 1-5 As shown, the robot joint includes a flexible tactile sensor 1, a joint control cavity 2, a joint cavity 3, a joint mechanical transmission part 4, and a joint rotating body 5. The various parts 2-5 are fixed together by screws, and the flexible tactile sensor 1 is connected to the joint control cavity 2 and the joint cavity 3 by adhesive bonding.

[0015] The joint control cavity 2, as shown Figure 3 As shown, it includes a joint connector 21, two drivers 22, a data acquisition board 23, and two cavity shells 24.

[0016] The joint connector 21 has two annular disks 211 with equal upper and lower diameters, connected by a square columnar structure 212. The three parts are integrally formed. A square opening 213 is provided on each side of the lower annular disk to ensure that data cables and power cables are led from the joint cavity 3 to the joint control cavity 2. The square opening 213 on the lower annular disk allows the cables from the joint cavity 3 to the joint control cavity 2. Electronic components and electrical wiring harnesses are all encased in a cavity, resulting in a compact structure and aesthetically pleasing appearance.

[0017] The outer shell 24 of the cavity is semi-circular, and its diameter is the same as the outer diameter of the annular disk 212. The height of the outer shell 24 is approximately equal to the distance between the two annular disks. The two outer shells 24 are fixed to the sides of the joint connector 21, forming a cylinder. The two outer shells 24 and the joint connector 21 are also fixed together with bolts. A wiring hole is provided at the center of the junction of the two outer shells 24. After the two outer shells are fixed together, the two wiring holes form a circular hole. This circular hole ensures that the data cable and power cable are led from the joint control cavity 2 to the outside for easy connection to the controller by the user.

[0018] Two drivers 22 and two data acquisition boards 23 are installed in the space of the joint control cavity 2. The two drivers are symmetrically installed. The two data acquisition boards 23 are used to collect data from the tactile skin sensor. They are also installed in the space between the cavity shell and the cylindrical tube and are fixed together with the joint connector 21. The data acquisition boards 23 are electrically connected to the flexible tactile sensor that is adhered to the cavity shell 24.

[0019] In this invention, the length, width, and height of the driver are 42mm, 30mm, and 20mm, respectively.

[0020] The joint cavity 3, as Figure 5 As shown, it includes a motor mounting base 31, a joint transmission base 32, and two joint fixing plates 33. The motor mounting base 31 and the joint transmission base 32 are connected in sequence to form a cylinder. Two joint fixing plates 33 are symmetrically fixed on the outside of the joint transmission base 32. The parts are fixed together by screws to form a cavity.

[0021] like Figure 6 As shown, the motor mounting base 31 is cylindrical, with two internal cavities 311 for mounting the motor and reducer module, and two cable routing grooves 312 for power and data cables. The upper part of the motor mounting base 31 is bolted to the lower annular disc of the joint connector 21, and has a circular boss for mating. The lower part of the motor mounting base 31 has mounting holes 313 for fixing the motor and reducer module, for mounting the corresponding motor, reducer, and reducer power output, and a corresponding inwardly recessed portion is designed to provide space for the fixing bolts, while also contacting and positioning with the bearing retaining ring 42. Compared with existing solutions, this design eliminates the need for a transmission end cover, reduces the number of bolt connections, simplifies the assembly process, and also helps improve the overall structural strength.

[0022] The two joint fixing plates 33 have the same structure and are symmetrically arranged. Their outer periphery can form an arc surface with the same diameter as the motor mounting seat. The joint fixing plate 33 has a horizontal plate, an arc plate 333, and a lug 331. The horizontal plate, arc plate 333, and lug 331 are an integral structure. The horizontal plate has a mounting hole 334 for fixing to the lower end of the joint transmission seat 32. The outer side of the horizontal plate is the arc plate 333, which has an arc-shaped surface. The outer side of the lug has a cylindrical boss 332. The outer side of the cylindrical boss 332 is located inside the arc-shaped surface. The arc plate 333 can be fixed to the recessed part of the joint transmission seat 32 to form a smooth curved surface.

[0023] The joint mechanical transmission part 4 consists of two parallel transmission chains, including a first transmission chain and a second transmission chain; the two sets of transmission chains have the same structure and are centrally symmetrical in spatial arrangement; the parts of the joint mechanical transmission part 4 are respectively fixed on the joint cavity 3 and the joint rotating body 5, the joint cavity is small in volume and has a smooth surface.

[0024] like Figure 7-8 As shown, each transmission chain includes a motor and reducer module, bearing retaining ring, worm, worm wheel, driving bevel gear and worm bearing. The two transmission chains are connected together by a bevel gear shaft, and the driving bevel gear of both transmission chains meshes with the same driven bevel gear. The motor and reducer module 41 consists of an encoder 411, a frameless DC motor 412, a planetary reducer 413, a bearing 414, and an outer frame, all packaged into a single module with a diameter of 40mm. The total axial height of the entire module is less than 110mm, and it is fixed to the joint cavity 3 with bolts. The motor transmits power to the planetary reducer 413 inside the motor and reducer module 41. One end of the worm bearing 43 rests on the shoulder of the worm 44, and the other end contacts and is positioned with one end of the bearing retaining ring 42. The other end of the bearing retaining ring 42 contacts and is positioned with the motor mounting base 31. The power output of the planetary reducer 413 is transmitted to the worm 44, which meshes with a worm gear 45 of the same module. The worm gear 45 and the driving bevel gear 46 are fixed together on one end of the bevel gear shaft with bolts. The driving bevel gear 46 meshes with a driven bevel gear 47 of the same module. The other end of the bevel gear shaft is connected to the worm gear 48 of the second transmission chain; the inner side of the opposing surfaces of the two worm gears 45 are fixed with driving bevel gears 46, and the two driving bevel gears 46 mesh with driven bevel gears 47. The distance between the two worm gears 46 is less than the distance between the two lugs of the joint cavity 3.

[0025] The components above the meshing position of the worm 44 and worm wheel 45 are installed inside the joint cavity 3, while the components below the meshing position of the worm 44 and worm wheel 45 are installed in the space between the joint rotating body 5 and the joint cavity 3.

[0026] The aforementioned motor, reducer, worm, worm wheel, driving bevel gear, driven bevel gear, bevel gear shaft, and worm bearing are procured according to requirements. The worm needs to be machined into a stepped shaft to ensure bearing positioning and to have openings for connection with the reducer. The overall length of the portion above the teeth in the planetary reducer 413 and worm 44 does not exceed the total length of the hollow portion inside the joint cavity. The motor and reducer module are bolted to the motor mounting base in the joint cavity. The planetary reducer output shaft is connected to the worm through a shaft hole. The worm shaft is a stepped shaft with two bearings symmetrically placed on both sides of the step. The bearing retaining rings rest on the motor mounting base and the bearing near the reducer end, respectively. The bearing away from the reducer end is fixed at one end by a shoulder and rests on the joint transmission seat at the other end. The worm wheel and driving bevel gear are bolted onto the bevel gear shaft, and the worm meshes with the worm wheel. The bevel gear shaft is fixed in the inner opening of the joint fixing plate 33. A flat needle roller bearing is fixed between the worm gear and the joint fixing plate 33. The driving bevel gear and the driven bevel gear mesh and transmit power.

[0027] The components of the joint mechanical transmission part are installed in part inside the joint cavity and in part inside the cavity formed by the joint rotating body 5 and the joint cavity 3. The joint rotating body and the joint cavity are connected by a pair of joint rotating body bearings. The robot joint is cylindrical in the initial state.

[0028] The joint cavity houses the joint mechanical transmission mechanism, and a flexible tactile sensor is adhesively attached to the outer surface of the joint cavity. The output of the joint mechanical transmission mechanism gives the joint rotary body two mutually perpendicular rotational degrees of freedom. One is the rotation of the joint rotary member 51 around the cylindrical boss on the joint connecting plate 34 of the joint cavity 3. At this time, the two motors have the same speed and the same direction, and the two driven bevel gears drive the cylindrical boss on the joint connecting plate 34 to rotate. The other rotation is the rotation of the joint connecting member 56 in the joint rotary body 5. At this time, the two motors have the same speed but opposite direction, and the driving bevel gear rotates, thereby driving the joint connecting member 56 to rotate.

[0029] The aforementioned flexible tactile sensor 1, joint control cavity 2, joint cavity 3, joint mechanical transmission part 4, and joint rotating body 5 can each be used as independent modules. They can be directly modularly installed to form a compact cylindrical robot joint.

[0030] In this embodiment, the joint cavity 3 is selected with a length of 116mm and a diameter of 90mm. The motor used is a KR3812WF with a diameter of 38mm, and the reducer is a planetary reducer P35H with a diameter of 35mm and a length of 47.4mm. The maximum diameter of the motor and reducer module is 40mm, ensuring that the total cross-sectional area of ​​the motor and reducer module is less than the cross-sectional area of ​​the joint cavity 3. To meet dimensional requirements, the actuator is an ELMO G-SOLTWI15 / 100SE1S with dimensions of 42mm (length), 30mm (width), and 20mm (height). To ensure meshing between the worm and worm wheel, the length of the worm is calculated, and a stepped shaft is machined on the worm to ensure bearing installation. The data acquisition board includes a flexible data acquisition section and a power supply section, with appropriate dimensions to receive tactile sensor signals and power the joint.

[0031] Figure 9 This diagram shows the structure of two differential robot joints with flexible tactile sensors connected by bolts, where the joint control cavity 2 of one joint is bolted to the rotating body 5 of the other joint.

[0032] The working principle of this invention is as follows: By connecting the power, data, and control lines of a compact, high-load, highly modular robot joint equipped with a flexible tactile skin sensor to the robot's controller, the controller sends control commands to the driver 22 inside the joint control cavity 2. The corresponding motor in the joint's mechanical transmission part rotates, driving the planetary reducer 413 to rotate, and then the power is transferred to the active bevel gear 46 through a worm gear structure. Depending on the speed and direction of the two motors, the joint rotary body 5 can achieve two degrees of freedom of rotation. The large transmission ratio and high-performance motor enable the joint to achieve a large output torque in a small size. Due to the reasonable layout of internal parts, the size of each part is limited and some parts are machined. This makes the joint cavity and joint control cavity smooth, thus allowing the installation of a matching high-sensitivity flexible tactile skin sensor. The data acquisition board of the tactile skin sensor and the motor driver are placed inside, making the entire joint a highly modular robot joint. Joint control can be completed by simply connecting the control lines and power lines of the driver and data acquisition board to the controller. The connection between the two joints can be achieved simply by bolting the joint control cavity and the joint rotary body together. Thus, a complete robot system can be assembled. The flexible tactile skin sensor is sized and its sensing array points are arranged according to the dimensions of the joint cavity and joint control cavity to ensure uniform collection of pressure information from the outer surfaces of the joint cavity 3 and joint control cavity 2. The data acquisition board integrates the information acquisition program; during use, only a data cable needs to be connected to obtain the surface pressure value.

[0033] This invention employs a differential structure consisting of a first transmission chain and a second transmission chain. Each degree of freedom in the differential structure is driven by two motors, maximizing space utilization. The chosen transmission chain and differential structure effectively meet the requirements for structural size and output torque. By altering the arrangement of the motors and reducers, a smaller size is achieved while still meeting high load requirements. The motor drivers and the skin sensor data acquisition board are placed within the joint control cavity, forming a highly portable joint. A tactile skin sensor is attached to the entire outer surface of the joint to obtain external tactile signals. The structural design of this invention makes the entire differential joint compact, modular, and highly portable, while also providing a matching tactile skin sensor. Openings for power and control lines are provided in the joint control cavity for easy sensor connection. When adjacent joints are installed together, sufficient installation space is provided to prevent interference and facilitate wiring. The entire joint has an outer diameter of 90mm, close to the size of a human upper limb, which is beneficial for the nursing robot to perform actions such as supporting and lifting.

[0034] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A compact humanoid arm robotic joint, comprising a flexible tactile sensor, a joint control cavity, a joint cavity, a joint mechanical transmission component, and a joint rotation body, wherein the flexible tactile sensor is adhesively connected to the joint control cavity and the joint cavity; the joint control cavity includes a joint connector, two actuators, a data acquisition board, and two cavity shells; characterized in that, The joint cavity is 116mm±5mm long and 90±5mm in diameter. The length, width and height of the actuator are 42±2mm, 30±2mm and 20±2mm respectively. The outer diameter of the entire joint is 85~95mm, which is close to the size of the human upper limb. The joint mechanical transmission system consists of two parallel transmission chains, with the components of the joint mechanical transmission system fixed to the joint cavity and the joint rotating body, respectively. Each transmission chain includes a motor and reducer module, bearing retaining rings, worm gear, worm wheel, driving bevel gear, and worm bearing. Two transmission chains are connected together via bevel gear shafts, and the driving bevel gears of both transmission chains mesh with the same driven bevel gear. The motor and reducer module consists of an encoder, a frameless DC motor, a planetary reducer, bearings, and an outer frame, packaged into a single module with a diameter less than 45mm and a total axial height of less than 110mm, fixed to the joint cavity with bolts. The encoder, frameless DC motor, and planetary reducer are connected together sequentially from top to bottom via bearings. The outer frame encapsulates the area containing the encoder, frameless DC motor, and bearings, transmitting power to the planetary reducer within the motor and reducer module. The planetary reducer outputs power to the worm gear.

2. The joint according to claim 1, characterized in that, The outer shell of the cavity is semi-circular, and its diameter is the same as the outer diameter of the annular disk. The height of the outer shell is approximately equal to the distance between the two annular disks. The two outer shells are wrapped and fixed to the side of the joint connector. The two outer shells and the joint connector form a cylinder. The two outer shells and the joint connector are also fixed together by bolts. A wiring hole is provided at the center of the junction of the two outer shells. After the two outer shells are fixed together, the two wiring holes form a circular hole.

3. The joint according to claim 1, characterized in that, The planetary reducer P35H has a diameter of 35mm and a length of 47.4mm. The maximum diameter of the motor and reducer module is 40mm. The frameless DC motor is a KR3812WF motor with a diameter of 38mm. The driver is an ELMO G-SOLTWI15 / 100SE1S driver.

4. The joint according to claim 1, characterized in that, The different speeds and directions of the frameless DC motors in the two transmission chains enable the joint to rotate with two degrees of freedom. The smooth surfaces of the joint cavity and joint control cavity allow for the installation of a matching high-sensitivity flexible tactile skin sensor. Inside, the data acquisition board of the tactile skin sensor and the motor driver are placed, making the entire joint a highly modular robotic joint with a diameter close to that of a human upper limb. Joint control can be completed simply by connecting the control lines and power lines of the driver and data acquisition board to the controller.

5. The joint according to claim 1, characterized in that, The frameless DC motor, planetary reducer, and worm gear are arranged on a single axis.

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