A linear actuator for the leg of a humanoid robot

Abstract

The present invention belongs to the technical fields of transmission devices and humanoid robots, and particularly relates to a linear actuator for the leg of a humanoid robot. The actuator includes a housing and joint output ends respectively provided at both ends of the housing; inside the housing, there is a motor unit that converts electrical energy into rotational kinetic energy, a planetary roller screw pair unit that converts rotational kinetic energy into linear kinetic energy, and a primary angle detection unit and a secondary angle detection unit that jointly determine the position of the planetary roller screw pair unit. The linear actuator for the leg of the humanoid robot according to the present invention has a highly integrated and compact structure, highly integrates motors, planetary roller screw pairs, angle sensors, planetary reduction mechanisms, etc. in a limited space, provides a large driving force, and achieves a high power density; through the cooperation of the primary and secondary angle detection units, the position and movement of the planetary roller screw can be accurately detected and controlled; it is easy to install, disassemble, and maintain.

Description

Technical Field

[0001] The present invention belongs to the technical fields of transmission devices and humanoid robots, and particularly relates to a linear actuator for the leg of a humanoid robot. Background Art

[0002] As a complete automatic control system, an important component of a humanoid robot is an actuator. Currently, the most widely used actuator is an electric actuator, which can be divided into a rotary actuator and a linear actuator according to motion. With the rapid development of robot technology in recent years, most robot joints use rotary actuators to achieve power output. The rotary actuator needs to be connected to a mechanism that converts rotary motion into reciprocating motion to achieve linear reciprocating motion, and it cannot be longitudinally arranged, resulting in low utilization rate of the internal space of the leg. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention discloses a linear actuator for the leg of a humanoid robot, which is used to solve the problems that the traditional rotary actuator uses connecting rods, lead screws, gears, etc. to convert rotary motion into reciprocating motion, resulting in a complex robot system, a huge volume, and limited performance.

[0004] The present invention is realized through the following technical solutions:

[0005] A linear actuator for the leg of a humanoid robot includes a housing and joint output ends respectively arranged at both ends of the housing; inside the housing, there is a motor unit that converts electrical energy into rotational kinetic energy, a planetary roller screw pair unit that converts rotational kinetic energy into linear kinetic energy, and a primary angle detection unit and a secondary angle detection unit that jointly determine the position of the planetary roller screw pair unit.

[0006] The motor unit includes a motor stator fixed inside the housing and a motor rotor rotatably arranged inside the motor stator; the planetary roller screw pair unit includes a planetary roller screw slidably arranged inside the housing and a planetary roller screw nut fitted on the planetary roller screw; the planetary roller screw nut is fixedly connected to the motor rotor.

[0007] A radially magnetized magnet that rotates synchronously with the planetary roller screw nut is further arranged inside the housing, and an angle sensor I is arranged at a position adjacent to the radially magnetized magnet to form a primary angle detection unit.

[0008] A speed reduction mechanism for reducing the speed of the planetary roller screw nut is further arranged inside the housing, a radially magnetized ring magnet is arranged on the speed reduction mechanism, and an angle sensor II is arranged at a position adjacent to the radially magnetized ring magnet to form a secondary angle detection unit.

[0009] Control the reduction ratio of the speed reduction mechanism so that within the stroke range of the planetary roller screw, the radially magnetized ring magnet rotates no more than one full turn.

[0010] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, the number of full rotations of the planetary roller screw nut is determined by the correspondence between the second angle sensor and the number of rotations of the planetary roller screw nut, and the number of non-full rotations of the planetary roller screw nut is determined by the first angle sensor. The number of full rotations and non-full rotations of the planetary roller screw nut are combined to obtain the rotation angle of the planetary roller screw nut, and the precise position of the planetary roller screw is correspondingly obtained.

[0011] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, the motor rotor is arranged in a hollow structure, and the planetary roller screw nut is fixed inside the motor rotor.

[0012] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, a limit sleeve is fixed inside the housing, and a limit groove is axially formed on the inner wall of the limit sleeve; a limit pin shaft is radially penetrated in the planetary roller screw, and both ends of the limit pin shaft are slidably embedded in the limit groove.

[0013] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, the radially magnetized magnet and the radially magnetized ring magnet are arranged in concentric rings on the same plane; a motion control board is also fixed inside the housing opposite to the radially magnetized ring magnet, and the first angle sensor and the second angle sensor are integrally arranged on the motion control board.

[0014] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, the reduction mechanism is a planetary reduction mechanism, including a planetary gear, a sun gear, a planetary carrier, and a ring gear; the sun gear is set to rotate synchronously with the planetary roller screw nut, the sun gear meshes with the planetary gear on the planetary carrier, and the planetary gear meshes with the fixedly arranged ring gear; the radially magnetized ring magnet is fixed at the end of the planetary carrier.

[0015] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, the planetary reduction mechanism is integrally arranged in an oblate shape.

[0016] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, the planetary gear is set as a double gear including a large gear and a small gear, the large gear meshes with the sun gear, and the small gear meshes with the ring gear.

[0017] Furthermore, in the above-mentioned linear actuator for the leg of the humanoid robot, by setting the number of teeth of the large and small gears in the sun gear, ring gear and planetary gear, an integer multiple reduction ratio is formed between the planetary carrier and the planetary roller screw nut.

[0018] Beneficial effects

[0019] The linear actuator for the leg of a humanoid robot according to the present invention has a highly integrated and compact structure, highly integrating a motor, a planetary roller screw pair, an angle sensor, a planetary reduction mechanism, etc. within a limited space, providing a large driving force and achieving a high power density.

[0020] The linear actuator for the leg of a humanoid robot according to the present invention can accurately detect and control the position and movement of the planetary roller screw through the cooperation of the first-level and second-level angle detection units.

[0021] The linear actuator for the leg of a humanoid robot according to the present invention is easy to install, disassemble and maintain. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the actuator.

[0023] Figure 2 It is an exploded schematic diagram of the actuator.

[0024] Figure 3 It is a schematic structural diagram of the planetary roller screw arranged in a sliding manner.

[0025] Figure 4 It is a schematic structural diagram of the angle detection unit.

[0026] Figure 5 It is a schematic structural diagram of the planetary reduction mechanism.

[0027] In the figure: 1. First joint bearing; 2. Motor end cover; 3. Motion control board; 4. First angle sensor; 5. Second angle sensor; 6. Radially magnetized magnet; 7. Radially magnetized ring magnet; 8. Planetary reduction mechanism; 9. Fixed seat; 10. First angular contact bearing; 11. Planetary roller screw; 12. Torque flange shaft; 13. Planetary roller screw nut; 14. Limit pin shaft; 15. Motor rotor; 16. Motor rotor positioning sleeve; 17. Motor stator; 18. Second angular contact bearing; 19. Limit sleeve; 20. Motor base; 21. Second joint bearing; 81. Planet gear; 82. Sun gear; 83. Planet carrier; 84. Ring gear. Detailed Embodiments

[0028] Embodiment 1

[0029] This embodiment discloses a linear actuator for the leg of a humanoid robot as shown in Figure 1 The linear actuator for the leg of a humanoid robot shown in the figure includes a housing and a first joint bearing 1 and a second joint bearing 21 respectively arranged at both ends of the housing. The motor end cover 2 covers the motor base 20 to form the housing. The first joint bearing 1 is fixed on the motor end cover 2, and the second joint bearing 21 is driven by a power mechanism inside the housing to perform a linear motion.

[0030] As shown in Figure 2As shown, inside the housing, there is a motor unit that converts electrical energy into rotational kinetic energy. The motor unit includes a motor stator 17 and a motor rotor 15. The motor stator 17 is fixed inside a motor base 20, and the motor rotor 15 is sleeved inside the motor stator 17 and can rotate. The motor stator 17 is powered to generate a rotating magnetic field to drive the motor rotor 15 to rotate. Thus, the motor unit converts electrical energy into rotational kinetic energy.

[0031] As Figure 2 shown, inside the housing, there is also a planetary roller screw pair unit that converts rotational kinetic energy into linear kinetic energy. The planetary roller screw pair unit includes a planetary roller screw 11 and a planetary roller screw nut 13. The planetary roller screw nut 13 is fixedly connected to the motor rotor 15. Therefore, the planetary roller screw nut 13 rotates synchronously with the motor rotor 15, thereby driving the planetary roller screw 11 to perform a linear motion. Preferably, the motor rotor 15 is arranged as a hollow structure, and the planetary roller screw nut 13 is fixed inside a hole in the center of the motor rotor 15 to facilitate improving the integration and compactness of the structure. One end of the planetary roller screw 11 extends out of the housing, and a second joint bearing 21 is fixed at this end. When the planetary roller screw 11 performs a linear motion, it drives the second joint bearing 21 to perform a linear motion.

[0032] As Figure 2 and Figure 3 shown, inside the motor base 20 and near one end of the second joint bearing 21, a limit sleeve 19 is fixed. The limit sleeve 19 is preferably made of copper. A limit groove is axially formed on the inner wall of the limit sleeve 19, and the length of the limit groove is adapted according to the stroke of the planetary roller screw 11. A limit pin shaft 14 is radially penetrated inside the planetary roller screw 11, and both ends of the limit pin shaft 14 are slidably embedded in the limit groove. Since the cooperation between the limit groove and the limit pin shaft 14 restricts the rotation of the planetary roller screw 11, when the planetary roller screw nut 13 rotates, the planetary roller screw 11 performs a linear motion.

[0033] As Figure 3As shown, the planetary roller screw nut 13 is sleeved and fixed inside the motor rotor 15. Outside the motor rotor 15, a motor rotor positioning sleeve 16 is also fixed to protect and position the motor rotor 15. The planetary roller screw nut 13 is also fixed with a torque flange shaft 12 for connecting the detection end. In this way, the planetary roller screw nut 13, the motor rotor 15, the motor rotor positioning sleeve 16, and the torque flange shaft 12 rotate synchronously to form a rotating assembly together. At both ends of the rotating assembly, an angular contact bearing one 10 and an angular contact bearing two 18 are respectively arranged, that is, both ends of the rotating assembly are respectively arranged in the housing through angular contact bearings. The angular contact bearings can withstand multi-directional loads such as large radial forces, axial forces, and torque forces, and have high precision, which can ensure the smooth rotation of the rotating assembly, thereby reducing vibration, wear, and energy loss during the transmission process. In addition, the above structures are assembled together to form a generally cylindrical combination body, which very efficiently and fully utilizes the limited space inside the motor base 20, making the overall structure very compact and having a very high power density.

[0034] As Figure 3 shown, a radially magnetized magnet 6 is also fixedly connected to the end face of the tail end of the torque flange shaft 12. The radially magnetized magnet 6 is directly opposite to a motion control board 3 fixed in the motor end cover 2, and an angle sensor one 4 is fixed on the motion control board 3. The rotation angle of the radially magnetized magnet 6 is detected by the angle sensor one 4 to form a primary angle detection unit. The angle sensor one 4 and the radially magnetized magnet 6 are arranged adjacent to each other, and their cooperation is as Figure 4 shown.

[0035] The above primary angle detection unit detects the angle of the planetary roller screw nut 13, that is, the angle of the rotating assembly. On this basis, a planetary reduction mechanism 8 is also arranged at the end of the torque flange shaft 12 to decelerate it. The planetary reduction mechanism 8 is as Figure 5 shown, including a planetary gear 81, a sun gear 82, a planet carrier 83, and a ring gear 84. The sun gear 82 is press-fitted with the torque flange shaft 12 to form a driving end, driving the planetary gear 81 on the planet carrier 83 to rotate. The planetary gear 81 also meshes internally with the fixedly arranged ring gear 84. In addition, a fixed seat 9 is fixedly arranged inside the housing. A bearing is arranged inside the fixed seat 9, and the inner ring of the bearing is press-fitted with the planet carrier 83 to support the rotation of the planet carrier 83 and maintain its position; the ring gear 84 is fixed on the fixed seat 9. The above planetary reduction mechanism 8 is integrally arranged in an oblate shape and is connected to the end of the torque flange shaft 12, thereby making full use of the internal space of the housing. The planetary reduction mechanism 8 makes a large reduction ratio formed between the torque flange shaft 12 and the planet carrier 83.

[0036] As Figure 3As shown, a radially magnetized ring magnet 7 is fixed to the end of the planet carrier 83, and an angle sensor II 5 is also disposed opposite on the motion control board 3. The angle sensor II 5 detects the angle of the radially magnetized ring magnet 7 to form a secondary angle detection unit. The cooperation between the radially magnetized ring magnet 7 and the angle sensor II 5 is as Figure 4 shown.

[0037] As described above, a radially magnetized magnet 6 is fixedly connected to the end face of the tail end of the torque flange shaft 12. The sun gear 82 is press-fitted and sleeved on the torque flange shaft 12. The planetary reduction mechanism 8 is integrally arranged to be oblate, and a radially magnetized ring magnet 7 is arranged on the end face of the planet carrier 83. In this way, the radially magnetized magnet 6 and the radially magnetized ring magnet 7 can be arranged in concentric rings on the same plane, and the angle sensor I 4 and the angle sensor II 5 can also be integrated on the same motion control board 3 and arranged adjacent to each other. This not only greatly saves space and improves the integration degree, but also the distances between the angle sensor I 4 and the radially magnetized magnet 6 and between the angle sensor II 5 and the radially magnetized ring magnet 7 are easily and accurately and stably limited, thereby improving the detection accuracy of the primary and secondary angle detection units.

[0038] As Figure 5 shown, in the planetary reduction mechanism 8, the planet gear 81 is arranged as a duplex gear including a large gear and a small gear. The large gear meshes with the sun gear 82, and the small gear meshes with the ring gear 84. This can not only reduce the diameter of the entire planetary reduction mechanism 8, but also obtain an additional stage of reduction to form an extremely high reduction ratio. The obtaining of a large reduction ratio plays an important role in improving the stroke accuracy of the planetary roller screw 11.

[0039] In addition, by setting the number of teeth of the large and small gears in the sun gear 82, the ring gear 84 and the planet gear 81, a high-integer multiple reduction ratio can be formed between the planet carrier 83 and the planetary roller screw nut 13.

[0040] The planet carrier 83 drives the radially magnetized annular magnet 7, and the angle of the radially magnetized annular magnet 7 is resolved by the angle sensor two 5 on the motion control board 3 through the encoder chip. Similarly, the angle sensor one 4 detects the angle of the planetary roller screw nut 13, that is, records the angle at the motor end. However, the position of the planetary roller screw 11 cannot be determined after power-off and restart. Through the compact planetary reduction mechanism 8, a large reduction ratio is generated, so that the radially magnetized annular magnet 7 rotates no more than one full circle within the stroke range of the roller screw pair. In this way, the rotation angle of the radially magnetized annular magnet 7 within the stroke range of the roller screw pair can correspond to the number of full rotations of the motor. On this basis, by using the detection information of the angle sensor one 4, the absolute position of the planetary roller screw 11 can be calculated very accurately. That is to say, the number of full rotations of the planetary roller screw nut 13 is determined by the correspondence between the angle sensor two 5 and the number of rotations of the planetary roller screw nut 13, and the non-full rotations of the planetary roller screw nut 13 are determined by the angle sensor one 4. The number of full rotations and non-full rotations of the planetary roller screw nut 13 are combined to obtain the rotation angle of the planetary roller screw nut 13, so as to correspondingly obtain the accurate position of the planetary roller screw 11.

[0041] Embodiment 2

[0042] The leg linear actuator of the humanoid robot provided in Embodiment 1 highly integrates a motor unit, a planetary roller screw pair unit, and a motion control unit within the housing, forming an integrated high-power density power component for linear motion.

[0043] The production and installation steps of this actuator are as follows:

[0044] (1) Press-fit the torque flange shaft 12 with the planetary roller screw nut 13 in advance, and press-fit the limit pin shaft 14 with the planetary roller screw 11 to form a planetary roller screw pair unit;

[0045] (2) Press-fit the limit sleeve 19, angular contact bearing two 18, motor rotor 15, motor stator 17, motor rotor positioning sleeve 16, and the planetary roller screw pair unit into the motor base 20 in sequence;

[0046] (3) Press-fit the angular contact bearing one 10 onto the fixed seat 9 and then assemble it with the motor base 20;

[0047] (4) Assemble the radially magnetized magnet 6 onto the planetary roller screw pair unit, assemble the planetary reduction mechanism 8 onto the fixed seat 9, and assemble the radially magnetized annular magnet 7 onto the planetary reduction mechanism 8;

[0048] (5) Assemble the motion control board 3 onto the fixed seat 9;

[0049] (6) Cover the motor end cover 2 on the fixed seat 9;

[0050] (7) Fix the spherical plain bearing 1 to the motor end cover 2, and fix the spherical plain bearing 21 to the threaded end of the planetary roller screw 11 to complete the assembly of the linear actuator for the leg of the whole humanoid robot.

[0051] The above embodiments are exemplary, and their purpose is to illustrate the technical concept and characteristics of the present invention, so that those skilled in this field can understand the content of the present invention and implement it accordingly. However, the protection scope of the present invention cannot be limited thereby. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A linear actuator for the leg of a humanoid robot, characterized in that: It includes a housing and joint output ends respectively provided at both ends of the housing; inside the housing, there is a motor unit that converts electrical energy into rotational kinetic energy, a planetary roller screw pair unit that converts rotational kinetic energy into linear kinetic energy, and a primary angle detection unit and a secondary angle detection unit that jointly determine the position of the planetary roller screw pair unit; The motor unit includes a motor stator (17) fixed inside the housing and a motor rotor (15) rotatably arranged inside the motor stator (17); the planetary roller screw pair unit includes a planetary roller screw (11) slidably arranged inside the housing and a planetary roller screw nut (13) fitted on the planetary roller screw (11); the planetary roller screw nut (13) is fixedly connected to the motor rotor (15); Inside the housing, there is also a radially magnetized magnet (6) that rotates synchronously with the planetary roller screw nut (13), and an angle sensor one (4) is provided at a position adjacent to the radially magnetized magnet (6), forming a primary angle detection unit; Inside the housing, there is also a speed reduction mechanism for reducing the speed of the planetary roller screw nut (13), a radially magnetized ring magnet (7) is provided on the speed reduction mechanism, and an angle sensor two (5) is provided at a position adjacent to the radially magnetized ring magnet (7), forming a secondary angle detection unit; Control the reduction ratio of the speed reduction mechanism so that within the stroke range of the planetary roller screw (11), the radially magnetized ring magnet (7) rotates no more than one full turn.

2. The linear actuator for the leg of a humanoid robot according to claim 1, characterized in that: Determine the number of full turns of the planetary roller screw nut (13) through the corresponding relationship between the angle sensor two (5) and the number of turns of the planetary roller screw nut (13), determine the non-full turns of the planetary roller screw nut (13) through the angle sensor one (4), combine the number of full turns and non-full turns of the planetary roller screw nut (13) to obtain the rotation angle of the planetary roller screw nut (13), and correspondingly obtain the precise position of the planetary roller screw (11).

3. The linear actuator for the leg of a humanoid robot according to claim 1, characterized in that: The motor rotor (15) is arranged in a hollow structure, and the planetary roller screw nut (13) is fixed inside the motor rotor (15).

4. The linear actuator for the leg of a humanoid robot according to claim 1, characterized in that: A limit sleeve (19) is fixed inside the housing, and a limit groove is axially formed on the inner wall of the limit sleeve (19); a limit pin shaft (14) is radially penetrated inside the planetary roller screw (11), and both ends of the limit pin shaft (14) are slidably embedded in the limit groove.

5. The linear actuator for the leg of a humanoid robot according to claim 1, characterized in that: The radially magnetized magnet (6) and the radially magnetized ring magnet (7) are arranged concentrically in the same plane; a motion control board (3) is also fixed inside the housing opposite to the radially magnetized ring magnet (7), and the angle sensor one (4) and the angle sensor two (5) are integrally arranged on the motion control board (3).

6. The linear actuator for the leg of a humanoid robot according to claim 1, characterized in that: The reduction mechanism is a planetary reduction mechanism, comprising a planetary gear (81), a sun gear (82), a planet carrier (83), and a ring gear (84); the sun gear (82) is arranged to rotate synchronously with the planetary roller screw nut (13); the sun gear (82) is meshed with the planetary gear (81) on the planet carrier (83); the planetary gear (81) is meshed with the inner side of a fixed ring gear (84); and the radially magnetized annular magnet (7) is fixed to an end of the planet carrier (83).

7. The linear actuator for the leg of a humanoid robot according to claim 6, characterized in that: The planetary reduction mechanism is configured to be in an oblate shape as a whole.

8. The linear actuator for the leg of a humanoid robot according to claim 6, characterized in that: The planetary gear (81) is configured as a double gear including a large gear and a small gear, the large gear meshing with the sun gear (82), and the small gear meshing with the ring gear (84).

9. The linear actuator for the leg of a humanoid robot according to claim 8, characterized in that: By setting the number of teeth of the large and small gears in the sun gear (82), the ring gear (84) and the planetary gear (81), an integral multiple reduction ratio is formed between the planet carrier (83) and the planetary roller screw nut (13).

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