Robot joint actuator

Abstract

The utility model discloses a robot joint actuator which comprises an actuator shell. The actuator comprises an actuator shell, a frameless torque motor, a motor stator arranged in the actuator shell, a motor rotor arranged in the motor stator and a permanent magnet arranged on the motor rotor. The inverted planetary roller screw is nested in a rotor of the frameless torque motor and comprises a screw shaft, one end of the screw shaft is provided with a linear guide rail groove, and the other end of the screw shaft is provided with a screw thread; the planet carrier is sleeved on the lead screw shaft; the rotary pin rollers are inserted into the planet carrier and distributed in the circumferential direction of the planet carrier; the surface of the rotary roller is provided with a roller thread groove matched with the screw thread; and the lead screw nut is sleeved on the rotating pin roller and is embedded in the motor rotor. The inverted planetary roller lead screw is matched with the frameless torque motor, the coaxial direct connection mode is adopted, the occupied space in the length direction and the height direction is reduced, and compared with a traditional motor turn-back type structure, the occupied space in the height direction is small.

Description

Technical Field

[0001] This utility model relates to the field of actuators, specifically a robot joint actuator. Background Technology

[0002] The development of linear actuators for humanoid robot joints stems from the urgent need for high-dynamic motion, precise force control, and compact structures.

[0003] Traditional rotary motor acceleration and deceleration solutions suffer from problems such as large size and slow response, while hydraulic drives face bottlenecks such as low energy efficiency and complex maintenance. Therefore, it is necessary to develop linear actuators suitable for humanoid robot joints.

[0004] Linear actuators are a type of end effector for humanoid robots, playing a crucial role in converting the rotational motion output by the power unit into linear motion.

[0005] In the context of humanoid robot applications, higher requirements are placed on the overall size, motion accuracy, stability, and dynamic response capability of linear actuators.

[0006] Traditional linear actuators typically consist of components such as an electric motor, a helical motion pair (including ball screws and planetary rotary roller screws), sensors (such as torque sensors and position sensors), encoders, drivers, and controllers.

[0007] Although these components can achieve precise motion feedback through closed-loop control, existing solutions, such as fully automatic intelligent servo electric cylinders, use a motor folding structure, resulting in a large overall size, especially in terms of height space, which cannot meet the driving requirements of narrow joint spaces such as the forearm or wrist of humanoid robots.

[0008] Therefore, there is a need to design a compact precision linear actuator to solve the problems of excessive size and insufficient control accuracy of existing linear actuators. Utility Model Content

[0009] Purpose of the utility model: To provide a robot joint actuator to solve the above-mentioned problems existing in the prior art.

[0010] Technical solution: A robot joint actuator, comprising:

[0011] Actuator housing;

[0012] A frameless torque motor includes a motor stator disposed within the actuator housing, a motor rotor disposed within the motor stator, and permanent magnets on the motor rotor;

[0013] The frameless torque motor is equipped with a Hall encoder at its rear end to monitor the motor's real-time speed and angle.

[0014] An inverted planetary roller screw, nested within the rotor of a frameless torque motor, includes:

[0015] A lead screw shaft, one end of which has a linear guide groove, and the other end has a lead screw thread;

[0016] Two planetary carriers are designed and fitted onto the lead screw shaft;

[0017] Four rotating rollers are designed and inserted into the planetary carrier, distributed along the circumference of the planetary carrier; the surface of the rotating rollers is provided with roller thread grooves that are adapted to the thread of the lead screw.

[0018] A lead screw nut is sleeved on the rotating roller and embedded in the motor rotor. The inner wall of the lead screw nut has a nut thread that matches the thread groove of the roller.

[0019] This utility model uses a reverse planetary roller screw and a frameless torque motor in combination, and adopts a coaxial direct connection method to reduce the space occupied in the length and height directions. Compared with the traditional motor folding structure, it occupies less space in the height direction. At the same time, by designing a reverse planetary roller screw, this solution has a larger transmission ratio, higher transmission efficiency, and stronger load-bearing capacity. It also eliminates the need for the installation of unnecessary components, making the structure more compact.

[0020] The threads on the inner wall of the lead screw nut and the rotating rollers form a planetary motion fit;

[0021] The rotating rollers achieve axial positioning and circumferential distribution through the planetary carriers designed at the front and rear ends, realizing load distribution at multiple contact points between the lead screw shaft and the lead screw nut. The rotating rollers both revolve around the lead screw shaft and rotate on their own axis, while the planetary carriers ensure the synchronous movement of the rotating rollers through bearings sleeved on the lead screw shaft.

[0022] In a further embodiment, the actuator housing is provided with a rear lifting lug at its end.

[0023] The housing comprises a front housing, a middle housing, and a rear housing connected in sequence;

[0024] The connection is made using connecting bolts.

[0025] A grating position sensor is installed inside the front housing;

[0026] The front housing has a lead screw extension opening adapted to the lead screw shaft at its end, and an extension washer adapted to the lead screw shaft is provided inside the lead screw extension opening.

[0027] The front housing is also provided with a bearing end cap washer that is compatible with the bearing sleeve;

[0028] The central housing is provided with a motor mounting base, the frameless torque motor is disposed in the motor mounting base, and the motor stator is mounted in the motor mounting base;

[0029] The rear housing contains a control board that communicates with the frameless torque motor, and the rear actuator housing contains an electrical interface.

[0030] The rear lug is mounted on the rear housing and is tightly threaded to the rear housing, thereby enabling connection with the robot's joint parts.

[0031] The control board is electrically connected to the Hall encoder, the frameless torque motor, and the grating position sensor. The control board is also electrically connected to the electrical interface. The control board can receive motor information from the Hall encoder and lead screw position information from the grating position sensor, and can control the frameless torque motor, thereby precisely controlling the forward stroke of the lead screw.

[0032] In a further embodiment, the lead screw shaft is connected to a front lug at one end located in the linear guide groove. The front lug enables connection to the robot's joint.

[0033] In a further embodiment, the actuator housing is provided with a guide block adapted to the linear guide groove. The guide block is fixedly installed in the front housing and forms an axial moving pair with the lead screw shaft to ensure the precise linear movement of the lead screw shaft. The grating position sensor is located above the guide block to monitor the distance the lead screw shaft moves forward in real time.

[0034] In a further embodiment, the rotating roller has a cavity inside, one end of the rotating roller is provided with a grease injection hole communicating with the cavity, and the other end is provided with an adapter port communicating with the cavity.

[0035] A one-way valve is provided inside the grease injection hole;

[0036] The surface of the rotating roller has grease outlet holes.

[0037] In a further embodiment, the planetary carrier is provided with extrusion members, and the extrusion members are designed in multiple sets, each set including:

[0038] The connecting block is connected to the planetary carrier;

[0039] A connecting post passes through the planetary carrier, through the adapter port, and extends into the chamber inside the rotating roller; the connecting post is provided with a rotary seal that mates with the adapter port;

[0040] An extrusion plate, connected to the connecting column, is located within the cavity and is adapted to the cavity.

[0041] Beneficial effects: This utility model discloses a robot joint actuator. This utility model uses an inverted planetary roller screw and a frameless torque motor in combination, and adopts a coaxial direct connection method to reduce the space occupied in the length and height directions. Compared with the traditional motor folding structure, it occupies less space in the height direction. At the same time, by designing an inverted planetary roller screw, this solution has a larger transmission ratio, higher transmission efficiency, and stronger load-bearing capacity. It also eliminates the installation of unnecessary components, making the structure more compact. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of this utility model.

[0043] Figure 2 This is a top view of the present invention.

[0044] Figure 3 This is a cross-sectional schematic diagram of the present invention.

[0045] Figure 4 This is a schematic diagram of the frameless torque motor of this utility model.

[0046] Figure 5 This is a schematic diagram of the inverted planetary roller screw of this utility model.

[0047] Figure 6 This is a schematic diagram of the linear guide groove of this utility model.

[0048] Figure 7 This is a schematic diagram of the rotating roller structure of this utility model.

[0049] The attached figures are labeled as follows:

[0050] 1. Front housing; 2. Middle housing; 3. Rear housing;

[0051] 4. Reverse planetary roller screw; 401. Screw shaft; 402. Rotating roller; 4021. Connecting block; 4022. Connecting column; 4023. Extrusion plate; 403. Planetary carrier; 404. Screw nut;

[0052] 5. Front lifting lug; 6. Rear lifting lug; 7. Electrical interface; 8. Connecting bolt; 9. Hall encoder; 10. Bearing sleeve; 11. Deep groove ball bearing; 12. Bearing end cover washer;

[0053] 13. Linear guide groove; 131. Guide block; 14. Lead screw protrusion; 15. Protrusion washer; 16. Grating position sensor; 17. Control board; 18. Frameless torque motor; 1801. Motor rotor; 1802. Permanent magnet; 1803. Motor stator. Detailed Implementation

[0054] This application relates to a robot joint actuator, which will be explained in detail below through specific embodiments.

[0055] A robotic joint actuator, comprising:

[0056] The actuator housing has a rear lifting lug 6 at its end.

[0057] The housing comprises a front housing 1, a middle housing 2, and a rear housing 3 connected in sequence;

[0058] The connection is made using connecting bolt 8;

[0059] A grating position sensor 16 is provided inside the front housing 1. A bearing sleeve 10 is provided inside the front housing 1. A deep groove ball bearing 11 is provided inside the bearing sleeve 10. The deep groove ball bearing 11 is sleeved on the lead screw nut 404.

[0060] A deep groove ball bearing 11 is located between the lead screw nut 404 and the front housing 1. The inner ring of the deep groove ball bearing 11 is tightly fitted with the lead screw nut 404. A bearing sleeve 10 is located between the inner ring of the bearing and the shoulder of the lead screw nut 404, which serves to axially position the deep groove ball bearing 11. The outer ring of the deep groove ball bearing 11 is tightly fitted with the front housing 1. There is a preload between the deep groove ball bearing 11 and the lead screw nut 404 to prevent the mechanism from shaking violently during operation. At the same time, it also provides a certain radial support and increases the rigidity of the overall structure.

[0061] Meanwhile, the front housing 1 also serves as a bearing end cover. A bearing end cover washer 12 with a certain preload is installed inside the front housing 1. Lubricating grease is added to the rear end of the bearing end cover washer 12 to ensure that the lead screw nut 404 rotates stably and smoothly.

[0062] The front housing 1 has a lead screw extension 14 adapted to the lead screw shaft 401 at one end, and an extension washer 15 adapted to the lead screw shaft 401 is provided in the lead screw extension 14.

[0063] The front housing 1 is also provided with a bearing end cover washer 12 that is adapted to the bearing sleeve 10;

[0064] The central housing 2 is provided with a motor mounting base, the frameless torque motor 18 is disposed in the motor mounting base, and the motor stator 1803 is installed in the motor mounting base;

[0065] The rear housing 3 is equipped with a control board 17 that communicates with the frameless torque motor 18, and the rear actuator housing is equipped with an electrical interface 7.

[0066] The rear lug 6 is mounted on the rear housing 3 and is tightly threaded to the rear housing 3, thereby enabling connection with the robot's joint parts.

[0067] The control board 17 is electrically connected to the Hall encoder 9, the frameless torque motor 18, and the grating position sensor 16. The control board 17 is electrically connected to the electrical interface 7. The motor stator 1803 of the frameless torque motor 18 is connected to the electrical interface 7.

[0068] The control board 17 can receive motor information from the Hall encoder 9 and position information of the lead screw shaft 401 from the grating position sensor 16, and can control the frameless torque motor 18, thereby accurately controlling the forward stroke of the lead screw shaft 401.

[0069] A frameless torque motor 18, a motor stator 1803 disposed in the actuator housing, a motor rotor 1801 disposed in the motor stator 1803, and a permanent magnet 1802 on the motor rotor;

[0070] The frameless torque motor 18 is equipped with a Hall encoder 9 at its rear end to monitor the motor's real-time speed and angle.

[0071] The motor stator 1803 is connected to the U / V / W three-phase power supply and the drive board via the electrical interface 7. The drive board controls the U / V / W three-phase power supply to form an electromagnetic field through the stator windings on the motor stator 1803. Since there is a permanent magnet on the motor rotor 1801, the motor rotor 1801 will rotate under the action of this electromagnetic field. The Hall encoder 9 can monitor the rotation phase of the permanent magnet in real time and convert it into the motor speed and angle. The Hall encoder 9 is electrically connected to the control board 17 and can transmit the speed and angle information to the control board 17. After comparing the speed and angle information with the target value, the control board 17 controls the U / V / W three-phase power supply again to achieve the effect of feedback control of the motor speed and angle, and realizes precise control of the frameless torque motor 18.

[0072] An inverted planetary roller screw 4, nested within the rotor of a frameless torque motor 18, includes:

[0073] The lead screw shaft 401 has a linear guide groove 13 at one end and a lead screw thread at the other end.

[0074] Two planetary carriers 403 are designed and fitted onto the lead screw shaft 401;

[0075] Four rotating rollers 402 are designed and inserted into the planetary carrier 403, distributed circumferentially along the planetary carrier 403; the surface of the rotating rollers 402 is provided with roller thread grooves that are adapted to the screw thread.

[0076] The lead screw nut 404 is sleeved on the rotating roller 402 and embedded in the motor rotor 1801. The inner wall of the lead screw nut 404 has a nut thread that matches the thread groove of the roller.

[0077] The nut thread on the inner wall of the lead screw nut 404 forms a planetary motion fit with the rotating roller 402;

[0078] The rotating roller 402 achieves axial positioning and circumferential distribution through the planetary carrier 403 designed at the front and rear ends, realizing load distribution at multiple contact points between the lead screw shaft 401 and the lead screw nut 404. The rotating roller 402 both revolves around the lead screw shaft 401 and rotates on its own axis. The planetary carrier 403 ensures the synchronous movement of the rotating roller 402 by bearings sleeved on the lead screw shaft 401.

[0079] The lead screw shaft 401 is connected to a front lug 5 at one end of the linear guide groove 13, and the front lug 5 is used to connect with the robot joint.

[0080] The actuator housing is provided with a guide block 131 that is adapted to the linear guide groove 13. The guide block 131 is fixedly installed in the front housing 1 and forms an axial moving pair with the lead screw shaft 401 to ensure the precise linear movement of the lead screw shaft 401. The grating position sensor 16 is located above the guide block 131 to monitor the distance the lead screw shaft 401 moves forward in real time.

[0081] In the reverse planetary roller screw 4, the screw nut 404 is tightly engaged with the motor rotor 1801 in the frameless torque motor 18. That is, when the motor rotor 1801 rotates clockwise, the screw nut 404 will also rotate clockwise at the same angular velocity because the screw nut 404 is tightly engaged with the motor rotor 1801 in the circumferential direction. Under the triple constraints of the screw thread of the screw shaft 401, the planet carrier 403, and the nut thread of the screw nut 404, the rotating roller 402 simultaneously generates three kinds of motion: rotational motion around its own axis, revolution motion around the center of the screw shaft 401, and axial precession with the nut thread.

[0082] This composite motion causes the rotating roller 402 to form a dynamic planetary gear train within the planet carrier 403, directly converting the rotational motion of the lead screw nut 404 into the precise linear displacement of the lead screw shaft 401.

[0083] Since all rotating rollers 402 participate in load transmission, force equalization is achieved through phase difference arrangement. In conjunction with the guide structure in the planetary carrier 403, the lead screw shaft 401 can achieve micron-level positioning accuracy within a millimeter-level stroke, while bearing extremely high axial and radial composite loads.

[0084] The rotating roller 402 has a cavity inside. One end of the rotating roller 402 is provided with a grease injection hole communicating with the cavity, and the other end is provided with an adapter port communicating with the cavity.

[0085] A one-way valve is provided inside the grease injection hole;

[0086] The surface of the rotating roller 402 has grease outlet holes.

[0087] The planetary carrier 403 is equipped with extrusion components, which are designed in multiple sets, each set including:

[0088] Connecting block 4021 is connected to the planetary carrier 403;

[0089] The connecting post 4022 passes through the planetary carrier 403, through the adapter port, and extends into the chamber inside the rotating roller 402; the connecting post 4022 is provided with a rotary seal that is adapted to the adapter port;

[0090] The extrusion plate 4023 is connected to the connecting column 4022, located inside the cavity, and adapted to the cavity.

[0091] By designing the extrusion part, grease can be injected into the rotating roller 402. The grease is injected into the cavity through the oil injection hole. When the rotating roller 402 rotates, the internal grease is scraped by the extrusion plate 4023 and discharged through the grease outlet hole to complete the lubrication work.

[0092] When grease needs to be added, remove the rear housing 3 and add grease through the grease filler hole;

[0093] This method of injecting grease utilizes the rotation of the rotating roller 402. Since the extrusion plate 4023 is connected to the connecting column 4022 and fixed on the planetary gear through the coupling, when the rotating roller 402 rotates, the internal grease will be driven to move by the extrusion plate 4023 and discharged through the grease outlet.

[0094] Working principle description: During operation, the frameless torque motor 18 drives the motor rotor 1801 to rotate. When the motor rotor 1801 rotates, it drives the lead screw nut 404 to rotate, which in turn drives the rotating roller 402 to rotate. Under the triple constraints of the lead screw thread of the lead screw shaft 401, the planetary carrier 403, and the nut thread of the lead screw nut 404, the rotating roller 402 simultaneously generates three motions: rotational motion around its own axis, revolution motion around the center of the lead screw shaft 401, and axial precession with the nut thread. This, in turn, drives the extension and retraction motion of the lead screw shaft 401, thus directly converting the rotational motion of the lead screw nut 404 into the precise linear displacement of the lead screw shaft 401. During movement, the linear guide groove 13 and the guide block 131 cooperate to make the lead screw shaft 401 move linearly, which in turn drives the front lifting lug 5 to move.

[0095] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

Claims

1. A robot joint actuator, characterized in that, include: Actuator housing; The frameless torque motor (18) includes a motor stator (1803) disposed in the actuator housing, a motor rotor (1801) disposed in the motor stator (1803), and a permanent magnet (1802) on the motor rotor. An inverted planetary roller screw (4), nested within the rotor of a frameless torque motor (18), includes: A lead screw shaft (401) has a linear guide groove (13) at one end and a lead screw thread at the other end. Planetary carrier (403) is sleeved on the lead screw shaft (401). Rotating rollers (402) are inserted into the planetary carrier (403) and distributed circumferentially along the planetary carrier (403); the surface of the rotating rollers (402) is provided with roller thread grooves that are adapted to the screw thread; The lead screw nut (404) is sleeved on the rotating roller (402) and embedded in the motor rotor (1801). The inner wall of the lead screw nut (404) has a nut thread that matches the thread groove of the roller.

2. The robot joint actuator according to claim 1, characterized in that: The actuator housing is provided with a rear lifting lug (6) at its end.

3. A robot joint actuator according to claim 1, characterized in that: The lead screw shaft (401) is connected to a front lifting lug (5) at one end of the linear guide groove (13).

4. A robot joint actuator according to claim 1, characterized in that: The actuator housing is provided with a guide block (131) that is adapted to the linear guide groove (13).

5. A robot joint actuator according to claim 1, characterized in that: The rotating roller (402) has a cavity inside. One end of the rotating roller (402) is provided with a grease injection hole communicating with the cavity, and the other end is provided with an adapter port communicating with the cavity. A one-way valve is provided inside the grease injection hole; The surface of the rotating roller (402) has grease outlet holes.

6. A robot joint actuator according to claim 5, characterized in that: The planetary carrier (403) is provided with an extrusion member, including: Connecting block (4021) is connected to the planetary carrier (403); The connecting column (4022) passes through the planetary carrier (403), through the adapter port, and extends into the chamber inside the rotating roller (402); The extrusion plate (4023) is connected to the connecting column (4022), located inside the cavity, and adapted to the cavity.

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