Linear actuator and humanoid robot

Abstract

The invention provides a linear actuator and a humanoid robot, and relates to the field of linear actuators. The linear actuator comprises a shell assembly, a driving piece, a torque transmission assembly, a ball screw assembly and an execution rod. The driving piece, the torque transmission assembly and the ball screw assembly are all installed in the shell assembly, and a driving shaft of the driving piece extends into the input end of the torque transmission assembly and is in static friction connection with the torque transmission assembly. The ball screw assembly comprises a screw shaft and a nut, and the output end of the torque transmission assembly is connected with the screw shaft; the nut is in threaded connection with the lead screw shaft and is in sliding fit with the shell assembly. One end of the execution rod extends into the shell assembly and is connected with the nut. According to the linear actuator provided by the invention, the technical problems of high system complexity and cost and low force control response speed caused by the fact that a linear actuator in the prior art cannot realize reverse driving and needs to be provided with a force sensor are solved.

Description

Technical Field

[0001] The present application relates to the field of linear actuators, and more particularly, to a linear actuator and a humanoid robot. Background Art

[0002] A linear actuator is an important actuator for achieving linear motion and has wide applications in the field of humanoid robots. At present, the commonly used linear actuators in humanoid robots mainly adopt the method of connecting and driving a motor with a planetary roller screw; this method drives the planetary roller screw through a rotating motor to convert the rotational motion into a linear motion. However, in the context of the increasing requirements for compliant control and force feedback in humanoid robots, this linear actuator solution has the following limitations: (1) The planetary roller screw transmission mechanism cannot achieve reverse driving due to its self-locking characteristic; in order to achieve force sensing and compliant control, it is usually necessary to additionally install a force sensor at the output end of the actuator; this results in a complex system structure, and at the same time, since the force sensor is located at the outer end of the control loop, the force control response speed is slow, there is a contradiction between force sensing and control, and it is difficult to meet the requirements of humanoid robots for fast force feedback.

[0003] (2) The additionally installed force sensor not only increases the mechanical complexity of the system but also increases the complexity of the control system; at the same time, the introduction of the force sensor also increases the overall cost of the actuator, affecting its large-scale application in the field of humanoid robots. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a linear actuator and a humanoid robot to alleviate the technical problems existing in the prior art, such as the linear actuator cannot achieve reverse driving and needs to install a force sensor, resulting in high system complexity and cost, and low force control response speed.

[0005] To solve the above technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the linear actuator provided by the present invention includes a housing assembly, a driving member, a torque transmission assembly, a ball screw assembly, and an actuator rod; The driving member, the torque transmission assembly, and the ball screw assembly are all installed in the housing assembly, and the driving shaft of the driving member extends into the input end of the torque transmission assembly and is in static friction connection with the torque transmission assembly; The ball screw assembly includes a screw shaft and a nut, and the output end of the torque transmission assembly is connected to the screw shaft; the nut is threadedly connected to the screw shaft and is slidably engaged with the housing assembly; One end of the actuator rod extends into the housing assembly and is connected to the nut.

[0006] Furthermore, the lead of the screw shaft is greater than 10 mm.

[0007] Furthermore, the torque transmission assembly includes an output shaft member, a shrink disc, and a flange; The drive shaft of the drive member is in static friction connection with the output shaft member through the shrink disc; One end of the flange is connected to the output shaft member, and the lead screw shaft is connected to the other end of the flange.

[0008] Furthermore, the torque transmission assembly further includes a pressing piece and a pin, and the flange is set as a D-axis flange; The end of the D-axis flange is connected to the pressing piece and clamps the lead screw shaft; The pin passes through the lead screw shaft, and both ends are respectively inserted into the D-axis flange and the pressing piece.

[0009] Furthermore, a ball body is installed at the connection between the lead screw shaft and the nut.

[0010] Furthermore, the actuating rod is connected to the nut through a nut output member.

[0011] Furthermore, the housing assembly includes an actuator housing, a coupling housing, and a mounting housing. Both ends of the coupling housing are respectively connected to the actuator housing and the mounting housing; The drive member is installed in the mounting housing, the torque transmission assembly is installed in the coupling housing, the ball screw assembly is in sliding fit with the actuator housing, and the actuating rod extends into the actuator housing and is connected to the nut output member.

[0012] Furthermore, a sensor is installed inside the coupling housing, and a magnet is installed on the nut output member.

[0013] Furthermore, a first radial spherical plain bearing is provided at the end of the actuating rod, a second radial spherical plain bearing is provided at the head end of the mounting housing, and an encoder is installed inside the mounting housing.

[0014] In a second aspect, the humanoid robot provided by the present invention includes the linear actuator as described in any one of the above.

[0015] Based on the above technical solutions, the technical effects that the present invention can achieve are analyzed as follows: The linear actuator provided by the present invention includes a housing assembly, a driving member, a torque transmission assembly, a ball screw assembly, and an actuating rod; the driving member, the torque transmission assembly, and the ball screw assembly are all installed in the housing assembly, and the driving shaft of the driving member extends into the input end of the torque transmission assembly and is in static friction connection with the torque transmission assembly; the ball screw assembly includes a screw shaft and a nut, and the output end of the torque transmission assembly is connected to the screw shaft; the nut is in threaded connection with the screw shaft and is in sliding fit with the housing assembly; one end of the actuating rod extends into the housing assembly and is connected to the nut. The housing assembly is used to support and fix the internal parts of the linear actuator. The driving member is used to rotate and drive the components connected to the driving shaft; the driving shaft of the driving member is in static friction connection with the torque transmission assembly, ensuring the stable transmission of torque during the normal operation of the linear actuator. And when an extreme condition of over-thrust limit occurs at the end of the actuating rod, the static friction between the driving shaft and the torque transmission assembly will turn into sliding friction, thereby protecting the driving shaft of the driving member; at the same time, it is worth noting that the near-rigid connection characteristic provided by the torque transmission assembly eliminates the deformation problem of the traditional elastic coupling and effectively avoids the problem of force control performance lag caused by elastic deformation. The output end of the torque transmission assembly is connected to the screw shaft, so that when the driving shaft drives the torque transmission assembly to rotate, the torque transmission assembly drives the screw shaft to rotate; because the nut is in threaded connection with the screw shaft and is in sliding fit with the housing assembly, when the screw shaft rotates, it drives the nut to move along the axial direction of the screw shaft. The actuating rod is connected to the nut, and when the nut moves along the axial direction of the screw shaft, it drives the actuating rod to move, realizing the basic function of the linear actuator. Because the driving shaft of the driving member is connected to the torque transmission assembly by a static friction connection method, and the nut of the ball screw assembly does not self-lock, when an external force is applied to the end of the actuating rod, the actuating rod becomes the driving part and drives the nut to rotate, so that the actuating rod automatically retracts into the housing assembly when it is subjected to an external force, having a reverse driving ability. And when the actuating rod retracts, it will not damage the driving shaft of the driving member; therefore, this linear actuator does not need to install additional sensors, reducing the number of parts, lowering the cost, and improving the force control response speed.

[0016] When this linear actuator is applied to a humanoid robot, the linear actuator has a reverse driving ability, enabling the humanoid robot to better interact with the physical environment, better sense the impact of the external environment, and improve the dynamic performance of the robot. Brief Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a perspective view of the linear actuator provided for the embodiments of the present application; Figure 2 A partial schematic diagram of the linear actuator provided by the embodiment of the present application; Figure 3 A cross-sectional view of the linear actuator provided by the embodiment of the present application; Figure 4 A partial cross-sectional view of the linear actuator provided by the embodiment of the present application; Figure 5 is Figure 4 The partial enlarged view at position A in Figure 6 An exploded schematic diagram of the linear actuator provided by the embodiment of the present application; Figure 7 A three-dimensional view of the calf of the humanoid robot provided by the embodiment of the present application; Figure 8 A side view of the calf of the humanoid robot provided by the embodiment of the present application.

[0019] Icon: 1 - First radial spherical plain bearing; 2 - Second radial spherical plain bearing; 3 - Coupling housing; 4 - Mounting housing; 5 - Driving member; 6 - Ball screw assembly; 61 - Screw shaft; 62 - Nut; 63 - Pressure plate; 64 - Ball return pipe; 65 - Dust-proof sheet; 66 - Ball body; 7 - Linear sliding bearing; 8 - Crossed roller bearing; 9 - Actuating rod; 10 - Torque transmission assembly; 11 - Hall sensor; 12 - Magnet; 13 - Actuator housing; 24 - Housing assembly; 25 - Output shaft member; 26 - Expansion sleeve; 27 - D-shaft flange; 28 - Pressing piece; 29 - Nut output member; 30 - Pin; 31 - Encoder; 32 - Anti-rotation slide rail. Detailed implementation manners

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0021] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this application is usually placed when in use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0022] In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "arrangement" and "connection" 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, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0023] Embodiment 1 The linear actuator is an important actuator for realizing linear motion and has wide applications in the field of humanoid robots. At the present stage, the commonly used linear actuators in humanoid robots mainly adopt the scheme of motor and screw drive, among which the planetary roller screw drive is the most common. This scheme drives the planetary roller screw through a rotating motor to convert the rotational motion into a linear motion, and has the advantages of large load-bearing capacity and high positioning accuracy. However, in the context of the increasing requirements for compliant control and force feedback in humanoid robots, this linear actuator scheme has the following limitations: the planetary roller screw drive mechanism has a low back-driving efficiency and an inherent self-locking characteristic, which makes it difficult for the actuator body to achieve reverse driving. To achieve force sensing and compliant control, a force sensor usually needs to be additionally installed at the output end of the actuator. This scheme makes the system structure more complex, and at the same time, since the force sensor is located at the outer end of the control loop, the force control response speed is limited, there is a contradiction between force sensing and control, and it is difficult to meet the requirements of humanoid robots for fast force feedback; the additionally added force sensor not only increases the mechanical complexity of the system, but also increases the complexity of the control system. At the same time, the introduction of the force sensor also increases the overall cost of the actuator, affecting its large-scale application in the field of humanoid robots. With the continuous improvement of the performance requirements of humanoid robots for actuators, it is urgent to develop a new linear actuator scheme with the ability of body reverse driving to achieve better force sensing and control performance.

[0024] In view of this, referring to Figures 1 to 6 , the linear actuator provided by the embodiment of the present invention includes a housing assembly 24, a driving member 5, a torque transmission assembly 10, a ball screw assembly 6, and an actuator rod 9; the driving member 5, the torque transmission assembly 10, and the ball screw assembly 6 are all installed in the housing assembly 24, and the driving shaft of the driving member 5 extends into the input end of the torque transmission assembly 10 and is in static friction connection with the torque transmission assembly 10; the ball screw assembly 6 includes a screw shaft 61 and a nut 62, the output end of the torque transmission assembly 10 is connected to the screw shaft 61; the nut 62 is threadedly connected to the screw shaft 61 and is slidably matched with the housing assembly 24; one end of the actuator rod 9 extends into the housing assembly 24 and is connected to the nut 62.

[0025] Specifically, the driving member 5 is set as a high-power density BLDC direct drive motor, and the linear actuator reaches the performance of a thrust of 1200 N and a linear velocity of 0.3 m / s.

[0026] The housing assembly 24 is used to support and fix the internal parts of the linear actuator. The driving member 5 is used to rotationally drive the components connected to the drive shaft; the drive shaft of the driving member 5 is in static friction connection with the torque transmission assembly 10, ensuring the stable transmission of torque during the normal operation of the linear actuator. And when an extreme condition of over-thrust limit occurs at the end of the actuator rod 9, the static friction between the drive shaft and the torque transmission assembly 10 will turn into sliding friction, thus protecting the drive shaft of the driving member 5. At the same time, it is worth noting that the near-rigid connection characteristic provided by the torque transmission assembly 10 eliminates the deformation problem of the traditional elastic coupling, effectively avoiding the problem of force control performance lag caused by elastic deformation. The output end of the torque transmission assembly 10 is connected to the lead screw shaft 61, so that when the drive shaft drives the torque transmission assembly 10 to rotate, the torque transmission assembly 10 drives the lead screw shaft 61 to rotate. Since the nut 62 is in threaded connection with the lead screw shaft 61 and is in sliding fit with the housing assembly 24, when the lead screw shaft 61 rotates, it drives the nut 62 to move axially along the lead screw shaft 61. The actuator rod 9 is connected to the nut 62, and when the nut 62 moves axially along the lead screw shaft 61, it drives the actuator rod 9 to move, realizing the basic function of the linear actuator. Because the drive shaft of the driving member 5 is connected to the torque transmission assembly 10 by a static friction connection method, and the nut 62 of the ball screw assembly 6 does not self-lock, when an external force is applied to the end of the actuator rod 9, the actuator rod 9 becomes the driving part and drives the nut 62 to rotate, causing the actuator rod 9 to automatically retract into the housing assembly 24 when subjected to an external force, having a reverse driving ability. And when the actuator rod 9 retracts, it will not damage the drive shaft of the driving member 5. Therefore, this linear actuator does not need to install additional sensors, reducing the number of parts and cost, and improving the force control response speed.

[0027] When this linear actuator is applied to a humanoid robot, the linear actuator has a reverse driving ability, enabling the humanoid robot to better interact with the physical environment, better sense the impact of the external environment, and improve the dynamic performance of the robot.

[0028] The following details the structure and shape of the linear actuator: In an alternative embodiment of the present invention, the lead of the lead screw shaft 61 is greater than 10 mm.

[0029] Specifically, based on computational theoretical analysis, the larger the lead and the smaller the diameter of the lead screw shaft 61, the more conducive it is to achieve reverse driving. Physical reverse driving tests were carried out on ball screw assemblies 6 with different lead specifications, and the results are shown in the following table.

[0030] Table 1 Comparative experiment table of ball screw assemblies 6 with different lead specifications

[0031] Based on the experimental data in the above table, when the lead of the lead screw shaft 61 is greater than or equal to 10 mm, stable anti-driving can be achieved. However, considering the inverse relationship between the lead and the output thrust, the requirement for product compactness, and the performance status of direct drive motors, which are mostly high-speed and low-torque. In actual design, it is necessary to make a reasonable balance among the anti-driving performance, output thrust, performance of the driving motor, and installation dimensions. Finally, a lead screw shaft 61 with a diameter of 12 mm and a lead of 10 mm is selected, and a small pre-tightening force is applied to the ball circulation system during the prefabrication of the ball screw assembly 6 to ensure that the system has the characteristics of low friction loss.

[0032] In an alternative embodiment of the present invention, the torque transmission assembly 10 includes an output shaft member 25, a shrink disc 26, and a flange; the drive shaft of the drive member 5 is connected to the output shaft member 25 by static friction through the shrink disc 26; one end of the flange is connected to the output shaft member 25, and the lead screw shaft 61 is connected to the other end of the flange.

[0033] Specifically, the drive shaft of the drive member 5 is frictionally connected to the output shaft member 25 through the shrink disc 26, and the output shaft member 25 is bolted to the flange.

[0034] The shrink disc 26 is assembled inside the output shaft member 25, and the shrink disc 26 is connected to the output shaft of the high power density BLDC direct drive motor by a static friction connection; this connection structure has two functions: on the one hand, it ensures the stable transmission of torque during normal operation; on the other hand, in the extreme working condition where the output thrust limit is exceeded at the end of the actuator, the static friction between the shrink disc 26 and the motor output shaft will turn into sliding friction, thus playing a role in protecting the drive motor; at the same time, it is worth noting that the near-rigid connection characteristic provided by the shrink disc 26 eliminates the deformation problem of the traditional elastic coupling, effectively avoiding the problem of force control performance lag caused by elastic deformation.

[0035] In an alternative embodiment of the present invention, the torque transmission assembly 10 further includes a pressing piece 28 and a pin 30, the flange is set as a D-axis flange 27; the end of the D-axis flange 27 is connected to the pressing piece 28 and clamps the lead screw shaft 61; the pin 30 passes through the lead screw shaft 61 and is inserted into the D-axis flange 27 and the pressing piece 28 at both ends respectively.

[0036] Specifically, the end of the D-axis flange 27 is bolted to the pressing piece 28. The D-axis flange includes a cylindrical portion and a connecting portion. One end of the cylindrical portion is connected to the output shaft member 25, and the other end is connected to the connecting portion. The cylindrical portion and the connecting portion are coaxial, and the outer diameter of the cylindrical portion is larger than that of the connecting portion. The cross-section of the connecting portion is semi-circular and is provided with a threaded hole. The pressing piece is square and is disposed between the connecting portion and the connecting portion to enclose a region for installing the lead screw shaft 61, and the bolt passes through the pressing piece 28 and is connected to the threaded hole of the connecting portion. Further, the torque transmission assembly 10 further includes a crossed roller bearing 8, and the crossed roller bearing 8 is embedded in the outer wall of the D-axis flange 27 and is slidably engaged with the inner wall of the housing assembly 24. In the shafting structure of this linear actuator, the crossed roller bearing 8 provided in the torque transmission assembly 10 is mainly used to bear two types of loads: one is the axial thrust transmitted from the external environment through the ball screw assembly 6, and the other is the radial force generated by supporting the ball screw assembly 6.

[0037] The end of the torque transmission assembly 10 uses the D-axis flange 27 to cooperate with the lead screw shaft 61 for connection, ensuring the rigidity and stability of torque transmission. Secondly, the standard coupling method is adopted, which facilitates the rapid replacement of lead screw shafts 61 with different specification parameters and can meet the needs of diversified and rapid testing.

[0038] In an alternative embodiment of the present invention, a ball body 66 is installed at the connection between the lead screw shaft 61 and the nut 62.

[0039] Specifically, a ball return pipe 64 is installed on one side of the ball body 66, a pressing plate 63 is installed on the surface of the nut 62, and a dust-proof sheet 65 is installed at one end of the nut 62.

[0040] A ball body 66 is installed at the connection between the lead screw shaft 61 and the nut 62, realizing transmission using the ball body 66, with stable transmission and avoiding self-locking during reverse drive.

[0041] In an alternative embodiment of the present invention, the actuator rod 9 is connected to the nut 62 through a nut output member 29.

[0042] Specifically, the end of the lead screw shaft 61 extends into the cavity of the actuator rod 9, and the nut 62 is connected to the actuator rod 9 through the nut output member 29. Further, the connection between the nut output member 29 and the actuator rod 9 adopts a mating structure of a cylindrical boss and a groove, realizing coaxial positioning and torque transmission between components. Compared with the traditional bolt connection method, it effectively avoids the risk of shear force acting on the bolt and improves the reliability and positioning accuracy of the connection structure.

[0043] The nut output member 29 realizes the connection between the nut 62 and the actuator rod 9.

[0044] In an alternative embodiment of the present invention, an anti-rotation slide rail 32 is installed on the inner wall of the housing assembly 24 and is in frictional contact with both sides of the nut output member 29.

[0045] To prevent the nut 62 from rotating following the drive of the lead screw shaft 61 and to achieve pure axial movement, an anti-rotation slide rail 32 is provided at the contact part of the nut output member 29; the nut 62 is prevented from rotating following by frictional contact limit; the anti-rotation slide rail 32 is made of materials such as copper and POM with excellent self-lubricating properties.

[0046] In an alternative embodiment of the present invention, the housing assembly 24 includes an actuator housing 13, a coupling housing 3, and a mounting housing 4. The two ends of the coupling housing 3 are respectively connected to the actuator housing 13 and the mounting housing 4; the driving member 5 is installed in the mounting housing 4, the torque transmission assembly 10 is installed in the coupling housing 3, the ball screw assembly 6 is slidably engaged with the actuator housing 13, and the actuator rod 9 extends into the actuator housing 13 and is connected to the nut output member 29.

[0047] Specifically, the connection parts between the actuator housing 13, the coupling housing 3, and the mounting housing 4 all adopt a matching structure of cylindrical bosses and grooves, realizing coaxial positioning and torque transmission between components; compared with the traditional bolt connection method, the risk of shear force acting on the bolts is effectively avoided, and the reliability and positioning accuracy of the connection structure are improved. Further, a linear sliding bearing 7 is installed at the end of the actuator housing, and the actuator rod 9 passes through the linear sliding bearing 7 and is connected to the nut output member 29; the linear sliding bearing 7 has two functions: realizing motion guidance and bearing radial loads.

[0048] The actuator housing 13, the coupling housing 3, and the mounting housing 4 are respectively used to support and fix the corresponding internal components.

[0049] In an alternative embodiment of the present invention, a sensor is installed inside the coupling housing 3, and a magnet 12 is installed on the nut output member 29.

[0050] Specifically, the sensor includes two Hall sensors 11. The two Hall sensors 11 are symmetrically arranged inside the coupling housing 3, and magnets 12 are symmetrically installed on the nut output member 29 that moves axially together with the nut 62.

[0051] A dual-sensor redundancy design is adopted to achieve high-precision detection of the zero position distance; by comparing the signal feedback of the two Hall sensors 11, the errors that may be generated by a single sensor can be effectively eliminated, thereby significantly improving the reliability and accuracy of zero position detection.

[0052] In an alternative embodiment of the present invention, a first radial spherical plain bearing 1 is provided at the end of the actuator rod 9, a second radial spherical plain bearing 2 is provided at the head end of the mounting housing 4, and an encoder 31 is installed inside the mounting housing 4.

[0053] Specifically, the encoder 31 is located behind the driving member 5; since the driving shaft of the driving member 5 is connected to the torque transmission assembly 10 by a static friction connection method, and the nut 62 of the ball screw assembly 6 does not have self-locking, when an external force is applied to the end of the actuating rod 9, the actuating rod 9 becomes the driving member and drives the nut 62 to rotate, so that the actuating rod 9 automatically retracts into the housing assembly when an external force is applied, having the anti-driving ability; at the same time, the rotation of the nut will drive the driving member 5 to rotate. In the anti-driving state, the anti-driving state of the actuator can be observed and controlled according to the sensing information sampled by the encoder 31 on the driving member 5.

[0054] This configuration of the two-way spherical plain bearing provides additional degrees of freedom of motion for the linear actuator, enabling it to adapt to the spatial motion requirements of the multi-degree-of-freedom mechanism of the robot and facilitating rapid integration and application in the robot system.

[0055] The advantages of this linear actuator are described as follows: This linear actuator uses the ball screw assembly 6 for transmission. Through the screw shaft 61 with a small diameter and high lead, combined with a high power density BLDC direct drive motor, the anti-driving function of the linear actuator is successfully realized. This linear actuator has excellent dynamic performance indicators: the thrust can reach 1200 N, and the linear velocity reaches 0.3 m / s. Its structural and performance characteristics can effectively meet the relevant motion control requirements of the calf and ankle joints of the humanoid robot; For a humanoid robot, this linear actuator has excellent reverse driving ability, enabling the robot to better interact with the physical environment, better sense the impact of the external environment, and improve the dynamic performance of the robot.

[0056] The anti-driving force of the linear actuator provided in the embodiment of the present invention is tested, and the test method is as follows: A forward thrust test is carried out. The linear actuator adopts an external driver scheme to control the linear actuator. During the test process, the driving member 5 of the linear actuator is first calibrated for current-torque to establish an accurate current-torque correspondence relationship, and the theoretical output thrust of the linear actuator under different current conditions is calculated accordingly; then the linear actuator is installed on the test bench. Under the condition that the linear actuator outputs a specified current, the actual output thrust of the linear actuator is measured in real time by using the pressure sensor installed at the end of the actuating rod 9 to complete the current-thrust calibration of the actuator; at the same time, the error between the actual thrust measured by the pressure sensor and the theoretically calculated thrust under each current condition is recorded to evaluate the thrust conversion efficiency of the entire linear actuator.

[0057] The reverse drive test drives a pressure sensor through an external drive to apply a preset thrust to the actuator. During this process, the linear actuator remains stationary and continuously outputs current to resist the thrust. By recording the current sampling values of the linear actuator under different reverse drive thrust conditions and comparing and analyzing them with the current-thrust relationship obtained from the previous forward thrust calibration, the reverse drive ability characteristics of the linear actuator can be evaluated.

[0058] In addition, to avoid the jamming problem caused by the installation error of the linear actuator on the test bench, a ball joint is installed at the end of the actuator, and the installation error of the actuator is compensated by the freedom of movement provided by the ball joint.

[0059] Embodiment 2 The humanoid robot provided by the embodiment of the present invention includes the linear actuator described in Embodiment 1, so it also has the beneficial effects in Embodiment 1, which will not be elaborated here.

[0060] See Figure 7 and Figure 8 , the linear actuator is designed for the application of the calf and ankle joint of a 60 kg humanoid robot, achieving a humanoid ankle joint movement range. The ankle joint angular velocity can reach 200 deg / s, reaching the humanoid movement level. Through the design of the integrated ball screw drive scheme, the linear actuator body has excellent reverse drive characteristics, effectively improving the interaction ability of the humanoid robot with the physical environment and enhancing the perception ability of external impacts, thus significantly improving the dynamic performance of the robot.

[0061] It should be noted that, without conflict, the features in the embodiments of the present application can be combined with each other.

[0062] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A linear actuator, characterized in that: include: A housing assembly (24), a driving member (5), a torque transmission assembly (10), a ball screw assembly (6) and an actuator rod (9); The driving member (5), the torque transmission assembly (10) and the ball screw assembly (6) are all installed in the housing assembly (24), and the driving shaft of the driving member (5) extends into the input end of the torque transmission assembly (10) and is statically frictionally connected to the torque transmission assembly (10); The ball screw assembly (6) comprises a screw shaft (61) and a nut (62); the output end of the torque transmission assembly (10) is connected to the screw shaft (61); the nut (62) is threadedly connected to the screw shaft (61) and is slidably matched with the housing assembly (24); One end of the actuating rod (9) extends into the housing assembly (24) and is connected to the nut (62).

2. The linear actuator according to claim 1, characterized in that: The lead of the screw shaft (61) is greater than 10 mm.

3. The linear actuator according to claim 2, characterized in that: The torque transmission assembly (10) comprises an output shaft member (25), a tightening sleeve (26) and a flange; The drive shaft of the drive member (5) is statically frictionally connected to the output shaft member (25) via the expansion sleeve (26); One end of the flange is connected to the shaft outlet member (25), and the screw shaft (61) is connected to the other end of the flange.

4. The linear actuator according to claim 3, characterized in that: The torque transmission assembly (10) further comprises a pressing plate (28) and a pin (30), and the flange is configured as a D-axis flange (27); The end of the D-axis flange (27) is connected to the pressing sheet (28) and is clamped with the screw shaft (61); The pin (30) passes through the screw shaft (61), and two ends thereof are respectively inserted into the D-axis flange (27) and the pressing sheet (28).

5. The linear actuator according to claim 2, characterized in that: A ball body (66) is installed at the connection between the screw shaft (61) and the nut (62).

6. The linear actuator according to claim 2, characterized in that: The actuating rod (9) is connected to the nut (62) via a nut output member (29).

7. The linear actuator according to claim 6, characterized in that: The housing assembly (24) comprises an actuator housing (13), a coupling housing (3) and a mounting housing (4), and two ends of the coupling housing (3) are respectively connected to the actuator housing (13) and the mounting housing (4); The driving member (5) is installed in the mounting housing (4), the torque transmission assembly (10) is installed in the coupling housing (3), the ball screw assembly (6) is slidably matched with the actuator housing (13), and the actuator rod (9) extends into the actuator housing (13) and is connected to the nut output member (29).

8. The linear actuator according to claim 7, characterized in that: A sensor is installed inside the coupling housing (3), and a magnet (12) is installed on the nut output member (29).

9. The linear actuator according to claim 7, characterized in that: A first radial spherical bearing (1) is arranged at the end of the actuator rod (9), a second radial spherical bearing (2) is arranged at the head end of the mounting shell (4), and an encoder (31) is installed inside the mounting shell (4).

10. A humanoid robot, characterized in that: Comprising a linear actuator as described in any one of claims 1-9.

Images