A flexible joint for a space robotic arm based on a left-right rotating screw-leaf spring mechanism

Abstract

This invention provides a flexible joint for a space robotic arm based on a left-right rotating screw-leaf spring mechanism, comprising a joint driving component, a stiffness adjusting component, and a flexible joint output component. The stiffness adjusting component has a first end and a second end disposed opposite to each other. The first end of the stiffness adjusting component is fixedly connected to the joint driving component, and the second end of the stiffness adjusting component is connected to the flexible joint output component. The stiffness adjusting component is configured to adjust the stiffness value of the flexible joint of the robotic arm. This invention can adjust the stiffness in real time, has a large stiffness adjustment range, a compact structure, and low energy loss.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more specifically, to a flexible joint for a space robotic arm based on a left-right rotating screw-leaf spring mechanism. Background Technology

[0002] Traditional robotic arms typically require high joint stiffness to achieve high end-effector positioning accuracy. However, this process often results in large output forces and high response speeds, introducing significant uncertainties and risks to human-machine interaction safety and adaptation to unknown environments. In space missions, robotic arms need strong adaptability, high safety, high stability, and high efficiency. Flexible robotic arms have demonstrated significant application value in specialized fields such as aerospace and nuclear power plants. However, flexible robotic arms are characterized by high redundant degrees of freedom, strong coupling, and nonlinearity, making the systems extremely complex and challenging to design. Therefore, flexible joints with variable stiffness characteristics have become a research hotspot.

[0003] For complex scenarios with confined spaces and multiple coupled indicators, the output stiffness of flexible joints can change with the load, making them suitable for precision space operations. Variable stiffness flexible joints can reduce impact forces during contact collisions and effectively solve problems such as high dynamic response, nonlinear contact collisions, and transient distributed forces that exist during spacecraft docking.

[0004] Flexible leaf springs, as a special type of flexible component, can produce different stiffness values ​​while maintaining a constant effective working length, and can also function as a torque-transmitting component. Adding a leaf spring between the input and output of a joint can effectively change the joint's output stiffness, increasing joint compliance. To meet the requirements of adjustable stiffness and precise positioning in flexible joints, various variable stiffness flexible joints have been developed both domestically and internationally. For example, Chinese utility model patent CN206561438U discloses a robot flexible joint with continuously adjustable stiffness based on a spring. This mechanism incorporates a pulley transmission assembly between the lead screw motor and the lead screw, resulting in low transmission efficiency. The lead screw motor output shaft and the lead screw are subjected to significant radial pressure and are prone to slippage, making it difficult to achieve precise adjustment of joint stiffness. Chinese invention patent with publication number CN104669261A discloses a method for adjusting the stiffness of a robot joint actuator and a displacement-type variable stiffness joint actuator that can be adjusted synchronously. The mechanism uses an Archimedes spiral disk to change the position of the leaf spring fulcrum. When the position of the fulcrum needs to be changed, the transmission angle of the motion is small, and at the same time, the Archimedes spiral disk will bear a large force.

[0005] Therefore, the present invention provides a flexible joint for a spatial robotic arm based on a left-right rotating screw-leaf spring mechanism, which has a compact structure, real-time stiffness adjustment capability, a large stiffness adjustment range, and low energy loss. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a flexible joint for a space robotic arm based on a left-right rotating screw-leaf spring mechanism.

[0007] The present invention provides a flexible joint for a space robotic arm based on a left-right rotating screw-leaf spring mechanism, comprising a joint driving component, a stiffness adjusting component, and a flexible joint output component. The stiffness adjusting component has a first end and a second end disposed opposite to each other. The first end of the stiffness adjusting component is fixedly connected to the joint driving component, and the second end of the stiffness adjusting component is connected to the flexible joint output component. The stiffness adjusting component is configured to adjust the stiffness value of the flexible joint of the robotic arm.

[0008] Furthermore, the joint drive component includes a joint driver and an output flange. The joint driver is connected to a first side of the output flange, and the second side of the output flange is connected to a first end of the stiffness adjustment component. The joint driver is an integrated structure of a motor and a harmonic reducer.

[0009] Furthermore, the joint drive component also includes a motor bottom connector, which includes an upper flange, an input shaft, a third rolling bearing, a first shaft end elastic retaining ring, a first gasket, a chassis housing, and a joint input plate. The upper flange is fixedly connected to the joint actuator. One end of the chassis housing is connected to the joint input plate, and the other end of the chassis housing is connected to the upper flange. The third rolling bearing is disposed inside the chassis housing, and one end of the input shaft is sleeved inside the third rolling bearing. The first shaft end elastic retaining ring is disposed between the first end of the third rolling bearing and the chassis housing. The first gasket is disposed between the second end of the third rolling bearing and the upper flange. The upper flange is fixedly connected to the joint actuator.

[0010] Furthermore, the stiffness adjustment component includes a variable stiffness mechanism and a lead screw mechanism, wherein the moving part of the lead screw mechanism is disposed within the variable stiffness mechanism, and the moving part of the lead screw mechanism cooperates with the variable stiffness mechanism.

[0011] Furthermore, the variable stiffness mechanism includes a stiffness adjustment disc, a first leaf spring, and a second leaf spring. The first leaf spring and the second leaf spring are disposed inside the stiffness adjustment disc. One end of the first leaf spring and the second leaf spring is fixedly connected to the stiffness adjustment disc, and the other end of the first leaf spring and the second leaf spring is suspended. The first leaf spring and the second leaf spring are symmetrically arranged around the center of the stiffness adjustment disc.

[0012] Further, the lead screw mechanism includes a lead screw motor, left-hand and right-hand lead screws, a first lead screw nut, a second lead screw nut, a first slider, a second slider, a slider moving guide rail, a first rolling bearing, a second rolling bearing, a first stiffness adjusting fulcrum component, and a second stiffness adjusting fulcrum component. The first rolling bearing and the second rolling bearing are fixed on the stiffness adjusting disc. The two ends of the left-hand and right-hand lead screws are respectively fitted into the first rolling bearing and the second rolling bearing. The output end of the lead screw motor is connected to the left-hand and right-hand lead screws. The left-hand and right-hand lead screws have a left-hand threaded section and a right-hand threaded section. The first lead screw nut is connected to the... The left-hand threaded section is connected, the second lead screw nut is connected to the right-hand threaded section, the first slider is slidably mounted on the slider moving guide rail, the first slider is connected to the first lead screw nut, the first stiffness adjusting fulcrum component is connected to the first slider, the second slider is slidably mounted on the slider moving guide rail, the second slider is connected to the second lead screw nut, the second stiffness adjusting fulcrum component is connected to the first slider; the first stiffness adjusting fulcrum component is slidably connected to the first leaf spring, and the second stiffness adjusting fulcrum component is slidably connected to the second leaf spring.

[0013] Furthermore, the output end of the lead screw motor is connected to a first bevel gear, and the end of the left and right turn lead screw near the lead screw motor is connected to a second bevel gear, with the first bevel gear meshing with the second bevel gear.

[0014] Furthermore, the flexible joint output component includes an output component, a joint output disk, an input / output connection disk, and an output shaft. The input / output connection disk is connected to the second end of the stiffness adjustment disk, the joint output disk is connected to the input / output connection disk, and one end of the output shaft passes through the joint output disk and is located inside the input / output connection disk. One end of the output component is connected to the suspended ends of the first leaf spring and the second leaf spring, respectively, and the other end of the output component is connected to the joint output disk, respectively.

[0015] Furthermore, the flexible joint output component also includes a second shaft end elastic retaining ring, a second washer, and a fourth rolling bearing. The fourth rolling bearing is disposed inside the input / output connection plate and sleeved on the output shaft. The second shaft end elastic retaining ring is disposed at one end of the fourth rolling bearing, and the second washer is disposed between the second shaft end elastic washer and the fourth rolling bearing.

[0016] Furthermore, a compression spring is provided between the stiffness adjustment disc and the joint output disc.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The flexible joint of the space robotic arm provided by this invention is based on a left-right rotating screw-leaf spring mechanism. The left-right rotating screw has self-locking property. When the overall fulcrum position adjustment mechanism is adjusted to the target position and the stiffness output reaches the target value, it does not need to rely on external force to maintain stiffness stability. The leaf spring, as a flexible body, transmits torque while making the joint flexible, suppressing joint vibration, improving system stability, and improving structural compactness. Attached Figure Description

[0019] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0020] Figure 1 This is an overall schematic diagram of the flexible joint of the space robotic arm based on the left and right rotating screw-leaf spring mechanism according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the joint drive component of the flexible joint of the space robotic arm based on the left and right helical screw-leaf spring mechanism according to an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the motor bottom connector of the flexible joint of the space robotic arm based on the left and right helical screw-leaf spring mechanism according to an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the stiffness adjustment component of the flexible joint of the space robotic arm based on the left and right helical screw-leaf spring mechanism in an embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of a variable stiffness mechanism for a flexible joint of a spatial robotic arm based on a left-right helical screw-leaf spring mechanism, according to an embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram of the lead screw mechanism of the flexible joint of the space robotic arm based on the left-right turning lead screw-leaf spring mechanism according to an embodiment of the present invention.

[0026] Figure 7 This is a schematic diagram of the fulcrum position adjustment mechanism of the flexible joint of the space robotic arm based on the left and right helical screw-leaf spring mechanism according to an embodiment of the present invention.

[0027] Figure 8 This is a schematic diagram of the flexible joint output component of the flexible joint of the space robotic arm based on the left and right rotating screw-leaf spring mechanism according to an embodiment of the present invention.

[0028] Figure 9 This is a cross-sectional view of the flexible joint output component of the flexible joint of the space robot arm based on the left and right helical screw-leaf spring mechanism according to an embodiment of the present invention.

[0029] Figure 10This is a schematic diagram of the stiffness adjustment component and variable stiffness mechanism of the flexible joint of the space robotic arm based on the left and right helical screw-leaf spring mechanism according to an embodiment of the present invention.

[0030] Figure 11 This is a schematic diagram of the assembly of the input / output connection plate and stiffness adjustment plate of the flexible joint of the space robotic arm based on the left-right rotating screw-leaf spring mechanism according to an embodiment of the present invention. Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0032] This invention provides a flexible joint for a spatial robotic arm based on a left-right helical screw-leaf spring, which can achieve a wide range of stiffness adjustment and real-time stiffness adjustment, and has a compact structure and low energy loss.

[0033] like Figure 1 As shown, the flexible joint of the robotic arm of the present invention includes a joint driving component 1, a stiffness adjusting component 2, and a flexible joint output component 3. The joint driving component 1 is used to drive the joint movement. The stiffness adjusting component 2 drives the stiffness adjusting fulcrum component to move through the rotation of the lead screw, thereby changing the effective working length of the leaf spring and realizing the change of the overall joint output stiffness. A specific embodiment of the present invention is as follows.

[0034] like Figure 2 As shown, the joint drive component 1 includes a joint driver 11, a motor bottom connector 12, and an output flange 13; the joint drive component 1 is used to drive the entire joint to rotate around the axis, and its bottom is used to connect to the previous joint.

[0035] In this embodiment, the joint actuator 11 is an integrated motor-harmonic reducer joint actuator, and the output flange 13 is the output flange of the harmonic reducer.

[0036] like Figure 3As shown, the motor bottom connector 12 consists of an upper flange 12-1, an input shaft 12-2, a third rolling bearing 12-3, a first shaft end elastic retaining ring 12-4, a first gasket 12-5, a chassis housing 12-6, and a joint input plate 12-7. The outer ring of the third rolling bearing 12-3 is fixed, and there is a gap between the inner ring and the input shaft 12-2. The upper end of the third rolling bearing 12-3 abuts against the shoulder of the input shaft 12-2, and the lower end of the third rolling bearing 12-3 abuts against the boss of the chassis housing 12-6. The boss of the chassis housing 12-6 is connected and fixed to the joint input plate 12-7 by a threaded connection. The upper flange 12-1 of the connector is connected and fixed to the bottom of the joint actuator 11 by a threaded connection.

[0037] like Figure 4 As shown, the stiffness adjustment component 2 includes a variable stiffness mechanism 21 and a lead screw mechanism 22.

[0038] like Figure 5 As shown, the variable stiffness mechanism consists of a stiffness adjustment disc 21-1, a first leaf spring 21-2A, and a second leaf spring 21-2B. The first leaf spring 21-2A and the second leaf spring 21-2B are located within the stiffness adjustment disc 21-1. One end of each leaf spring 21-2A and the second leaf spring 21-2B is fixedly connected to the stiffness adjustment disc 21-1, while the other ends are suspended. The first leaf spring 21-2A and the second leaf spring 21-2B are arranged symmetrically around the stiffness adjustment disc 21-1.

[0039] The connection between the first leaf spring 21-2A, the second leaf spring 21-2B and the stiffness adjustment plate 21-1 is in the shape of an "I". The stiffness adjustment plate is provided with symmetrical "I" shaped grooves. The first leaf spring 21-2A, the second leaf spring 21-2B and the stiffness adjustment plate 21-1 are all provided with threaded holes, and the first leaf spring 21-2A, the second leaf spring 21-2B and the stiffness adjustment plate 21-1 are fixed through the threaded holes.

[0040] Holes are opened on opposite sides of the side wall of the stiffness adjustment disc 21-1 for mounting the lead screw mechanism 22.

[0041] like Figure 6As shown, the lead screw mechanism 22 consists of a lead screw motor 22-1, a first bevel gear 22-2A, a second bevel gear 22-2B, a first rolling bearing 22-3A, a second rolling bearing 22-3B, a sleeve 22-4, a first shaft end retaining ring 22-5A, a second shaft end retaining ring 22-5B, a left-right turning lead screw 22-6, a first lead screw nut 22-7A, a second lead screw nut 22-7B, a first slider 22-8A, a second slider 22-8B, a slider moving guide rail 22-9, a slider moving platform 22-10, a first stiffness adjusting fulcrum component 22-11A, and a second stiffness adjusting fulcrum component 22-11B. The stiffness adjustment plate 21-1 is mounted on the output flange 13, the slider moving platform 22-10 is mounted on the stiffness adjustment plate 21-1, the lead screw motor 22-1 is mounted on the slider moving platform 22-10, the output shaft of the lead screw motor 22-1 is provided with a keyway, the lead screw motor 22-1 transmits torque to the first bevel gear 22-2A through the keyway of the output shaft, the first shaft end retaining ring 22-5A is mounted on the lower side of the first bevel gear 22-2A; the second bevel gear 22-2B is mounted on the end of the left and right turn lead screw 22-6, the first bevel gear 22-2A and the second bevel gear 22-2B mesh with each other, the axes of the bevel gear sets intersect and the shaft intersection angle is 90°. Two reverse-mounted first rolling bearings 22-3A and second rolling bearings 22-3B restrict the axial movement of the left and right rotating screws 22-6. The outer rings of the first rolling bearings 22-3A and second rolling bearings 22-3B are fixed to the stiffness adjustment plate 21-1, and the inner rings rotate relative to the outer rings. The left and right rotating screws 22-6 are mounted on the first rolling bearings 22-3A and second rolling bearings 22-3B and are located at the center of the slider moving platform 22-10.

[0042] The left-hand and right-hand lead screw 22-6 includes a left-hand guide rod, a left-hand threaded section, a right-hand threaded section, and a right-hand guide rod. The guide rod is used to engage with the second bevel gear 22-2B, the first rolling bearing 22-3A, and the second rolling bearing 22-3B. The left-hand and right-hand lead screw 22-6 is equipped with a first lead screw nut 22-7A and a second lead screw nut 22-7B. The first lead screw nut 22-7A is connected to the first slider 22-8A by a threaded component, and the second lead screw nut 22-7B is connected to the second slider 22-8B by a threaded component. The first stiffness adjustment fulcrum component 22-11A is fixedly connected to the first slider 22-8A by a threaded component, and the second stiffness adjustment fulcrum component 22-11B is fixedly connected to the second slider 22-8B by a threaded component. When the left and right turn screw 22-6 rotates, the screw nut, slider, and stiffness adjustment fulcrum components form an integrated fulcrum position adjustment mechanism, performing reciprocating linear motion. The first screw nut 22-7A, the first slider 22-8A, and the first stiffness adjustment fulcrum 22-11A constitute the first integrated fulcrum position adjustment mechanism, while the second screw nut 22-7B, the second slider 22-7B, and the second stiffness adjustment fulcrum 22-7B constitute the second integrated fulcrum position adjustment mechanism. The first and second integrated fulcrum position adjustment mechanisms always maintain a symmetrical state. The rotation of the left and right turn screw 22-6 drives the first and second integrated fulcrum position adjustment mechanisms to simultaneously approach or move away from the center of rotation at the same speed.

[0043] The lead screw motor 22-1 is reversible, driving the left and right turn lead screws 22-6 to rotate clockwise or counterclockwise, thereby driving the two integral fulcrum position adjustment mechanisms to translate back and forth. The lead screw motor 22-1 is a bidirectional servo stepper motor with a step angle of 1.8°. The first rolling bearing 22-3A and the second rolling bearing 22-3B are reverse-mounted angular contact ball bearings used to limit the axial movement of the left and right turn lead screws 22-6.

[0044] The bottom of the stiffness adjustment plate 21-1 is hollow, providing space for the wiring of the lead screw motor 22-1 and reducing its own weight. Several threaded holes and bosses are arranged circumferentially on the bottom of the stiffness adjustment plate 21-1, and the stiffness adjustment plate 21-1 is fixed to the joint drive component 1 by threaded parts.

[0045] The lead screw mechanism 22 in this embodiment also includes a micro switch 22-12, which can cut off the power in case of a collision to prevent the overall fulcrum position adjustment mechanism from colliding if the lead screw motor 22-1 fails.

[0046] like Figure 7 As shown, the slot of the first stiffness adjustment fulcrum 22-11A can be engaged with the first leaf spring 21-2A, and the slot of the second stiffness adjustment fulcrum 22-11B can be engaged with the second leaf spring 21-2B, so that the stiffness adjustment fulcrum can move relative to the leaf spring.

[0047] like Figure 8 and Figure 9 As shown, the flexible joint output component 3 includes an output component 31, a joint output disk 32, an input / output connection disk 33, an output shaft 34, a second shaft end elastic retaining ring 35, a second washer 36, and a fourth rolling bearing 37; the top of the stiffness adjustment disk 21-1 has three grooves arranged circumferentially, and the input / output connection disk 33 is arranged in a "V" shape and is installed on the top of the stiffness adjustment disk 21-1 by threaded parts to maintain the radial and axial fixation of the joint output part. The articulated output plate 32, input / output connection plate 33, output shaft 34, second shaft end elastic retaining ring 35, second washer 36, and fourth rolling bearing 37 are coaxially mounted. The lower side of the fourth rolling bearing 37 is axially positioned by the shoulder of the output shaft 34, and the upper side is axially fixed by the second shaft end elastic retaining ring 35. To avoid mutual friction between the fourth rolling bearing 37 and the second shaft end elastic retaining ring 35, which would affect the rotational movement of the output shaft, a second washer 36 is added between them. The outer ring of the fourth rolling bearing 37 is fixed, while there is a gap between the inner ring and the output shaft 34, allowing the output shaft 34 to rotate freely relative to the input / output connection plate 33. The articulated output plate 32 is reserved with an electromechanical connection interface for matching and installing the end load.

[0048] like Figure 8 and Figure 10 As shown, two output components 31 are provided. The output components 31 are connected to the joint output disk 32 and are located inside the stiffness adjustment disk 21-1. The output components 31 are specifically canine-shaped, that is, they are formed by two parts interlocking with each other. The first output component 31-A includes canine-shaped components 31-A1 and 31-A2, and the second output component 31-B includes canine-shaped components 31-B1 and 31-B2.

[0049] The first leaf spring 21-2A is connected at its end to the first output component 31-A, and the second leaf spring 21-2B is connected at its end to the second output component 31-B. The leaf spring is engaged by a canine-shaped component, and the leaf spring and the canine-shaped component work together to transmit torque to the flexible joint output component 3. The concave groove of the first integral fulcrum position adjustment mechanism passes through both sides of the first leaf spring 21-2A, and the concave groove of the second integral fulcrum position adjustment mechanism passes through both sides of the second leaf spring 21-2B. The two integral fulcrum position adjustment mechanisms move simultaneously along the direction of the leaf spring in a counter-clockwise manner at the same speed.

[0050] like Figure 11 As shown, to prevent friction between the joint output disc 32 and the stiffness adjustment disc 21-1, which would affect their mutual rotation, a compression spring 38 is added between the joint output disc 32 and the stiffness adjustment disc 21-1 to provide axial support for the stiffness adjustment disc 21-1. The compression spring 38 can also be used to assist in circumferentially fixing the position of the leaf spring in the canine-type output component 31.

[0051] Both the input axis 12-2 and the output axis 33 can rotate freely independently of the flexible joints. They can be used to test one or more flexible joints individually when building the overall robotic arm, or to drive one or more flexible joints individually in special scenarios.

[0052] In this embodiment, a joint drive motor drives the joint to rotate around the joint's rotation center. The joint is connected to a stiffness adjustment disc, and one end of a leaf spring is fixed to the stiffness adjustment disc, while the other end is clamped to a dog-tooth-shaped output disc. During the joint's rotation, the leaf spring, the overall fulcrum position adjustment mechanism, and the joint as a whole rotate, thereby driving the output disc to rotate. When the output end is under load, the leaf spring undergoes effective flexible deformation from the position of the overall fulcrum position adjustment mechanism to the end of the leaf spring, giving the joint a flexible characteristic. Specifically, the degree of deformation of the leaf spring under load changes with the external load, thereby achieving the overall joint's compliance.

[0053] The torque transmission path in this embodiment is as follows: the joint drive motor drives the harmonic reducer, the output flange of the harmonic reducer rotates, the output flange of the harmonic reducer drives the stiffness adjustment plate to rotate, the stiffness adjustment plate transmits the torque to the dog tooth type output component through two symmetrically arranged leaf springs, the dog tooth type output component drives the output plate to rotate, thus realizing the relative rotation of input and output and completing the torque transmission of the entire joint.

[0054] The motion transmission path of the stiffness adjustment module in this embodiment is as follows: the rotation of the lead screw motor drives the first bevel gear to rotate, the first bevel gear meshes with the second bevel gear, the second bevel gear drives the left and right turn lead screws to rotate, and when the left and right turn lead screws rotate, the two integral fulcrum position adjustment mechanisms move at the same speed but in opposite directions. Under the drive of the external load, the leaf spring undergoes flexible deformation, and its effective working length is the distance between the integral fulcrum position adjustment mechanism and the end of the leaf spring.

[0055] The advantages of this invention are:

[0056] The left and right turn screws have self-locking properties. When the overall fulcrum position adjustment mechanism is moved to the target position and the stiffness output reaches the target value, there is no need to rely on external force to maintain the stiffness stability.

[0057] The joint drive motor and the lead screw motor are independent of each other. Regardless of whether the joint rotates or not, the position of the overall fulcrum position adjustment mechanism in the lead screw mechanism can be changed, thereby changing the stiffness value of the entire joint.

[0058] As a flexible material, leaf springs transmit torque while making joints more flexible, suppressing joint vibration, improving system stability, and enhancing structural compactness.

[0059] A micro switch is installed on the overall fulcrum position adjustment mechanism, which can cut off the power in case of a collision; this can prevent the two overall fulcrum position adjustment mechanisms from colliding under the condition that the lead screw motor driver fails, thereby affecting the safety of the entire joint;

[0060] The input / output connection plate has a "human" shaped structure. The crossbars in each direction of the input / output connection plate are embedded in the corresponding concave grooves of the stiffness adjustment plate and are fixedly connected by threaded parts. This can prevent the input / output connection plate from moving in any direction and ensure the structural stability of the entire variable stiffness flexible joint.

[0061] Both the top of the output disk and the bottom of the joint drive mechanism are equipped with rotating shafts that can rotate freely relatively independently of the flexible joints. These shafts can be used to test each flexible joint individually when building the overall robotic arm later, or to drive one or more flexible joints in the overall robotic arm independently in special scenarios.

[0062] A compression spring is placed between the stiffness adjustment disc and the joint output disc to axially support the joint output disc and prevent sliding friction from occurring when the stiffness adjustment disc and the joint output disc rotate; the spring can also be used to assist the canine-type output disc in fixing the axial position of the leaf spring.

[0063] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A flexible joint for a space robotic arm based on a left-right rotating lead screw-leaf spring mechanism, characterized in that, The device includes a joint drive component, a stiffness adjustment component, and a flexible joint output component. The stiffness adjustment component has a first end and a second end that are disposed opposite to each other. The first end of the stiffness adjustment component is fixedly connected to the joint drive component, and the second end of the stiffness adjustment component is connected to the flexible joint output component. The stiffness adjustment component is configured to adjust the stiffness value of the flexible joint of the robotic arm. The stiffness adjustment component includes a variable stiffness mechanism and a lead screw mechanism. The moving part of the lead screw mechanism is disposed inside the variable stiffness mechanism, and the moving part of the lead screw mechanism cooperates with the variable stiffness mechanism. The variable stiffness mechanism includes a stiffness adjustment disc, a first leaf spring, and a second leaf spring. The first leaf spring and the second leaf spring are disposed inside the stiffness adjustment disc. One end of the first leaf spring and the second leaf spring are fixedly connected to the stiffness adjustment disc, and the other end of the first leaf spring and the second leaf spring are suspended. The first leaf spring and the second leaf spring are symmetrically arranged around the center of the stiffness adjustment disc. The lead screw mechanism includes a lead screw motor, left-hand and right-hand lead screws, a first lead screw nut, a second lead screw nut, a first slider, a second slider, a slider moving guide rail, a first rolling bearing, a second rolling bearing, a first stiffness adjusting fulcrum component, and a second stiffness adjusting fulcrum component. The first and second rolling bearings are fixed on the stiffness adjusting disc. The two ends of the left-hand and right-hand lead screws are respectively fitted into the first and second rolling bearings. The output end of the lead screw motor is connected to the left-hand and right-hand lead screws. The left-hand and right-hand lead screws have a left-hand threaded section and a right-hand threaded section. The first lead screw nut and the left-hand threaded section... The system includes a threaded section connection, a second lead screw nut connected to the right-hand threaded section, a first slider slidably mounted on the slider moving guide rail, the first slider connected to the first lead screw nut, a first stiffness adjustment fulcrum component connected to the first slider, a second slider slidably mounted on the slider moving guide rail, the second slider connected to the second lead screw nut, and a second stiffness adjustment fulcrum component connected to the first slider; the first stiffness adjustment fulcrum component is slidably connected to the first leaf spring, and the second stiffness adjustment fulcrum component is slidably connected to the second leaf spring.

2. The flexible joint of the space robotic arm based on the left-right turning screw-leaf spring mechanism according to claim 1, characterized in that, The joint drive component includes a joint driver and an output flange. The joint driver is connected to a first side of the output flange, and the second side of the output flange is connected to a first end of the stiffness adjustment component. The joint driver is an integrated structure of a motor and a harmonic reducer.

3. The flexible joint of the space robotic arm based on the left-right turning screw-leaf spring mechanism according to claim 2, characterized in that, The joint drive component further includes a motor bottom connector, which includes an upper flange, an input shaft, a third rolling bearing, a first shaft end elastic retaining ring, a first gasket, a chassis housing, and a joint input plate. The upper flange is fixedly connected to the joint actuator. One end of the chassis housing is connected to the joint input plate, and the other end of the chassis housing is connected to the upper flange. The third rolling bearing is disposed inside the chassis housing, and one end of the input shaft is sleeved inside the third rolling bearing. The first shaft end elastic retaining ring is disposed between the first end of the third rolling bearing and the chassis housing. The first gasket is disposed between the second end of the third rolling bearing and the upper flange. The upper flange is fixedly connected to the joint actuator.

4. The flexible joint of the space robotic arm based on the left-right turning screw-leaf spring mechanism according to claim 1, characterized in that, The output end of the lead screw motor is connected to a first bevel gear, and the end of the left and right turn lead screw near the lead screw motor is connected to a second bevel gear, with the first bevel gear meshing with the second bevel gear.

5. The flexible joint of the space robotic arm based on the left-right turning screw-leaf spring mechanism according to claim 4, characterized in that, The flexible joint output component includes an output component, a joint output disk, an input-output connection disk, and an output shaft. The input-output connection disk is connected to the second end of the stiffness adjustment disk, the joint output disk is connected to the input-output connection disk, and one end of the output shaft passes through the joint output disk and is located inside the input-output connection disk. One end of the output component is connected to the suspended ends of the first leaf spring and the second leaf spring, respectively, and the other end of the output component is connected to the joint output disc.

6. The flexible joint of the space robotic arm based on the left-right turning screw-leaf spring mechanism according to claim 5, characterized in that, The flexible joint output component further includes a second shaft end elastic retaining ring, a second washer, and a fourth rolling bearing. The fourth rolling bearing is disposed inside the input / output connection plate and sleeved on the output shaft. The second shaft end elastic retaining ring is disposed at one end of the fourth rolling bearing, and the second washer is disposed between the second shaft end elastic washer and the fourth rolling bearing.

7. The flexible joint of the space robotic arm based on the left-right turning screw-leaf spring mechanism according to claim 6, characterized in that, A compression spring is also provided between the stiffness adjustment disc and the joint output disc.

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