A Robot Limb Joint Drive Structure and Design Method

Abstract

This invention belongs to the field of robotics technology, specifically relating to a robot limb joint drive structure and design method. The drive structure includes an upper limb, a lower limb, and a rigid chain device. The bottom end of the upper limb and the top end of the lower limb are hinged via a hinge axis. The rigid chain device is mounted on the upper limb, and the rigid chain output from the rigid chain device moves along an arc-shaped trajectory around the hinge axis, connecting to the lower limb at its head. The design method includes determining three rotational trajectories (one, two, and three) and designing the chain plate type. This invention can effectively replace joint motor modules and linear actuators. This structure not only possesses extended rigidity but can also exhibit a specific degree of curvature, allowing it to bypass the joint pivot and directly act on the driven component. It achieves the effect of a powerful arm driving rotation without increasing structural dimensions, thus overcoming the shortcomings of traditional robot limb joint drive methods.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, specifically relating to a robot limb joint drive structure and design method. Background Technology

[0002] There are two types of limb joint drive modes for robots. Taking the leg structure as an example, they are joint motor module drive and linear actuator drive.

[0003] (1) The joint motor module drive method has a simple structure. It only needs to use the module at the knee joint to connect the thigh and the lower leg. However, due to the limitation of direct joint drive, it is often necessary to arrange a motor with large power and size to meet the end force of the leg at a long distance. This results in a large leg structure size and an inability to withstand large load forces.

[0004] (2) The linear actuator has high transmission accuracy and large load capacity. It is often placed in the limb position of the thigh or calf. By using the lever principle, the thrust is converted into torque to drive the movement of the next joint. However, the rear fixed end and the front driving end of this driving method need to be connected by hinges, which means that the linear actuator itself is in a follow-up non-stationary state during the movement, which seriously affects the coordination of the leg. In addition, in order to meet the lever structure, the driven part needs to be set with an extension structure to connect with the linear actuator, which makes the size of the joint larger and cannot well adapt to the design requirements of humanoid size. Summary of the Invention

[0005] This invention discloses a robot limb joint drive structure and design method, which can effectively replace joint motor modules and linear actuators. This structure not only has extension rigidity, but can also exhibit a specific degree of curvature, enabling it to bypass the joint pivot and directly act on the driven component. Without increasing the structural size, it achieves the effect of driving rotation with a powerful arm, thus making up for the shortcomings of robot limb joint drive methods.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A robot limb joint drive structure includes an upper limb, a lower limb, and a rigid chain device. The bottom end of the upper limb and the top end of the lower limb are hinged by a hinge axis. The upper limb is equipped with a rigid chain device. The rigid chain output by the rigid chain device moves along an arc-shaped trajectory around the hinge axis and connects to the lower limb at the head of the rigid chain.

[0008] Preferably, the rigid chain device includes a housing located on the inner side of the upper part of the limb and fixedly connected to the upper part of the limb. Guide rail one and guide rail two are respectively provided on both sides of the inner wall of the housing. Chain one and chain two are slidably connected to guide rail one and guide rail two, respectively. An output port is provided at one end of the housing facing the lower part of the limb. Chain one and chain two mesh with each other near the output port to form a rigid chain. The rigid chain has an overall arc-shaped chain structure. The arc-shaped chain structure has the same axis as the hinge shaft one. A sprocket is provided inside the housing and on the side of chain one near the output port. The sprocket meshes with chain one. The central axis of the sprocket passes through the housing and is fixedly connected to the output shaft of a drive motor pre-installed outside the housing. A joint is fixedly connected to the heads of chain one and chain two, and the joint is hinged to the lower part of the limb.

[0009] Preferably, the rigid chain adopts a meshing push chain system disclosed in utility model application number CN202321451294.0, the difference being that: the back of the chain plates of chain one and chain two are inclined surfaces, and while the front of chain one and chain two are connected by a buckle, the adjacent chain plates of chain one and chain two are fitted together through two inclined surfaces, thereby realizing the arc-shaped chain structure of the rigid chain; the chain plates of chain one and chain two are meshed by a single buckle or a double buckle.

[0010] Preferably, the joint is hinged to the lower part of the limb via hinge shaft two. The cross section of hinge shaft two rotating around hinge shaft one forms rotation trajectory one, the cross section of the chain plate hole axis of chain two rotating around hinge shaft one forms rotation trajectory two, and the cross section of the chain plate hole axis of chain one rotating around hinge shaft one forms rotation trajectory three. The distance A between rotation trajectory one and rotation trajectory two and the distance B between rotation trajectory one and rotation trajectory three are the same.

[0011] A design method for a robot limb joint drive structure includes the following steps:

[0012] Step 1: Based on the total load of the lower part of the limb and the end structure connected to the lower part of the limb, select a rigid chain that meets the load requirements, and set the standard pitch of chain two as P. A The standard pitch of chain one is P. B The width after chain 2 and chain 1 mesh is W. The width refers to the vertical distance between the lines connecting the chain plate holes of the two meshing chain plates.

[0013] Step 2: Define the axis of hinge axis one as E and the axis of hinge axis two as N. Determine that the cross-section of axis N forms a rotation trajectory one as the lower part of the limb rotates. Let the radius of rotation of rotation trajectory one be R, then the radius of rotation of rotation trajectory two is R. A =R + W / 2, the radius of gyration R of the third gyration trajectory B=RW / 2, from which we can deduce the standard pitch P of chain one. B =P A *R B / R A ;

[0014] Step 3: On the second rotary trajectory, with the standard pitch P A Design the locking structure on the front of the chain plate of chain two and the angle of the inclined surface on the back, based on the chord length.

[0015] Step 4: On the third turning trajectory, with P B Given the chord length, and taking the angle between the locking structure on the front and the inclined surface on the back of the chain plate of chain two as a reference, the locking structure on the front and the inclined surface on the back of the chain plate of chain one are designed in the form of difference set. At this time, the chain plate types of chain two and chain one have been determined, and then the sleeve, roller and pin parts of the rigid chain are designed based on this.

[0016] Step 5: Based on the required extension stroke of the rigid chain device, design the chain lengths of chain one and chain two and their storage and running trajectories within the casing to complete the overall design of the arc-shaped rigid chain.

[0017] The beneficial effects of the robot limb joint drive structure and design method of the present invention are as follows:

[0018] (1) This invention proposes a driving scheme for robot limb joints, which can overcome the disadvantages of large motor power and large joint structure size required by the direct drive method of joint motor module, and can solve the problem that linear actuators can only move with the joint and cannot be fixed and stable for transmission.

[0019] (2) The robot limb joint driving scheme proposed in this invention can achieve rigid bending, increase the driving arm of the hinge joint between the upper and lower parts of the limb, and improve the load-bearing capacity.

[0020] (3) The design method of the arc-shaped rigid chain proposed in this invention can design the running trajectory of the intermeshing rigid chain and the driven component according to the size and structure of the joint, and has the advantage of high transmission accuracy.

[0021] (4) The arc-shaped rigid chain device proposed in this invention can be arranged entirely within the torso. During reciprocating motion, it can bypass the hinge pairs of the upper and lower parts of the limbs, greatly reducing the size of the joints. Attached Figure Description

[0022] Figure 1 This is an overall structural diagram of the present invention, taking the leg structure of a humanoid robot as an example.

[0023] Figure 2 This is a diagram of the internal structure of a rigid chain device.

[0024] Figure 3 This invention describes the leg movement principle using the leg structure of a humanoid robot as an example. Figure 1 .

[0025] Figure 4 This invention describes the leg movement principle using the leg structure of a humanoid robot as an example. Figure 2 .

[0026] Figure 5 This is a schematic diagram illustrating the design principle of the rigid chain plate type for this invention.

[0027] 1. Rigid chain device; 1-1. Housing; 1-1-1. Guide rail one; 1-1-2. Guide rail two; 1-2. Rigid chain; 1-2-1. Chain two; 1-2-2. Chain one; 1-3. Sprocket; 1-4. Joint; 2. Thigh; 3. Lower leg; 4. Hinge shaft one; 5. Bolt hole one; 6. Bolt hole two; 7. Inclined surface; 8. Lock; 9. Chain plate; 10. Rotation trajectory two; 11. Rotation trajectory three. Detailed Implementation

[0028] The following description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0029] The following embodiments can be understood as illustrating a part of the structure or method of the present invention individually, or as combining the embodiments to explain the broader structure or method of the present invention.

[0030] It should be noted that the robots involved in this invention include humanoid robots and other robots of various other forms. The upper part and lower part of the limb refer to two adjacent segments that make up the limb, such as the upper arm and lower arm, or the thigh and lower leg. The upper part and lower part of the limb rotate around a pivot. This invention is based on an improvement of the driving form of this rotation.

[0031] The accompanying drawings of this invention use the leg structure of a humanoid robot as an example, showing an example of setting a robot limb joint drive structure between the thigh and the lower leg. The same principle applies to the installation of this invention on other limbs.

[0032] The specific embodiments of the present invention will now be described with reference to the accompanying drawings:

[0033] Example 1

[0034] A robotic limb joint drive structure, such as Figure 1-5As shown, it includes an upper part of a limb, a lower part of a limb, and a rigid chain device. The bottom end of the upper part of the limb and the top end of the lower part of the limb are hinged by a hinge shaft 4. A rigid chain device 1 is installed on the upper part of the limb. The rigid chain 1-2 output by the rigid chain device 1 moves along an arc-shaped trajectory around the hinge shaft 4 and connects to the lower part of the limb at the head of the rigid chain.

[0035] In this embodiment, as Figure 1-5 As shown, the thigh 2 of the humanoid robot's leg structure is considered as the upper part of the limb, and the lower leg 3 as the lower part. Since the hinge axis 2 between the rigid chain 1-2 and the lower part of the limb rotates around the hinge axis 4 as the lower part of the limb rotates, the rotational trajectory of the axis section of the hinge axis 2 is a circular trajectory coaxial with the hinge axis 4. The trajectory of the rigid chain 1-2 during extension and retraction is also within the arc-shaped trajectory around the hinge axis 4. Therefore, a rigid chain satisfying this structure can complete the drive between the upper and lower parts of the limb. Thus, it can be understood that this invention actually provides a rigid chain device where the rigid chain extension trajectory is located within an arc-shaped trajectory, which differs from traditional linear extension and retraction rigid chains. It also differs from some rigid chain devices that can extend a curved rigid chain but whose trajectory is uncertain. In other words, because the rigid chain extension and retraction trajectory of this invention is fixed, it possesses the ability to perform precise transmission. A curved rigid chain with an unfixed extension and retraction trajectory is unlikely to possess this capability.

[0036] Example 2

[0037] like Figure 1-4 As shown, the rigid chain device 1 includes a housing 1-1 located on the inner side of the upper part of the limb and fixedly connected to the upper part of the limb. Guide rails 1-1-1 and 1-1-2 are respectively provided on both sides of the inner wall of the housing 1-1. Chains 1-2-2 and 1-2-1 are slidably connected to guide rails 1-1-1 and 1-1-2, respectively. An output port is provided at one end of the housing 1-1 facing the lower part of the limb. Chains 1-2-2 and 1-2-1 mesh with each other near the output port to form a rigid chain 1-2. The rigid chain 1-2 is integrally formed... The chain has an arc-shaped structure, and the arc-shaped chain structure has the same axis as the hinge shaft 4. Inside the housing 1-1 and on the side of the chain 1-2-2 near the output port, there is a sprocket 1-3. The sprocket 1-3 is meshed with the chain 1-2-2. The central axis of the sprocket 1-3 passes through the housing 1-1 and is fixedly connected to the output shaft of the drive motor (not shown in the figure) that is preset outside the housing 1-1. The heads of the chain 1-2-2 and the chain 2-2-1 are fixedly connected to the joint 1-4. The joint 1-4 is hinged to the lower part of the limb.

[0038] In this embodiment, the rigid chain structure is a commonly used technology, typically including a housing, a guide rail disposed within the housing, and two chains that can only bend to one side move along the guide rail and are housed within the housing. When the sprocket rotates, the rigid chain formed by the meshing of the two chains extends outward or retracts into the housing. The rigid chain structure of the present invention can be a rigid chain device disclosed in the prior art that enables the rigid chain to extend and retract along a fixed circular arc trajectory.

[0039] Example 3

[0040] This embodiment provides one implementation of the rigid chain device, namely:

[0041] like Figure 1-5 As shown, the rigid chain adopts a meshing push chain system disclosed in utility model application number CN202321451294.0. The difference is that the back of the chain plates of chain one 1-2-2 and chain two 1-2-1 are inclined surfaces 7. While the front of chain one 1-2-2 and chain two 1-2-1 are connected by the buckle 8, the adjacent chain plates of chain one 1-2-2 and chain two 1-2-1 are attached to each other through two inclined surfaces 7, thereby realizing the arc-shaped chain structure of rigid chain 1-2. The chain plates of chain one 1-2-2 and chain two 1-2-1 are meshed by a single buckle or a double buckle.

[0042] In this embodiment, the utility model application with application number CN202321451294.0 discloses an interlocking push chain system, the output push chain of which is a rigid straight push chain. The difference between this invention and the system is that by setting an inclined surface and a locking buckle, the output rigid chain has an arc-shaped trajectory. The protrusions of the interlocking part can be double protrusions or single protrusions. The chain can be a single row chain or a double row or multiple rows chain.

[0043] Example 4

[0044] like Figure 1-5 As shown, the joint 1-4 is hinged to the lower part of the limb via hinge shaft 2. The cross section of the axis of hinge shaft 2 rotating around hinge shaft 4 forms rotation trajectory 1. The cross section of the chain plate hole axis of chain 2 1-2-1 rotating around hinge shaft 4 forms rotation trajectory 2 10. The cross section of the chain plate hole axis of chain 1 1-2-2 rotating around hinge shaft 4 forms rotation trajectory 3 11. The distance A between rotation trajectory 1 and rotation trajectory 2 10 and the distance B between rotation trajectory 1 and rotation trajectory 3 11 are the same.

[0045] Example 5

[0046] Based on the above embodiments, this embodiment discloses:

[0047] A design method for robot limb joint drive structure, such as Figure 1-5As shown, it includes the following steps:

[0048] Step 1: As Figure 3 , 5 As shown, based on the total load of the lower part of the limb (such as the calf) and the end structures connected to the lower part of the limb (such as the foot), a rigid chain that meets the load requirements is selected, and the standard pitch of chain 1-2-1 is set to P. A The standard pitch of chain 1-2-2 is P. B The width of chain 1-2-1 and chain 1-2-2 after they mesh is W. The width refers to the vertical distance between the lines connecting the chain plate holes of the two chain plates that mesh with each other.

[0049] Step 2: Define the axis of hinge axis 4 as E and the axis of hinge axis 2 as N. Determine that the cross-section of axis N forms a rotation trajectory 1 when the lower part of the limb rotates. Let the radius of rotation of rotation trajectory 1 be R (e.g., ...). Figure 3 As shown), the radius of rotation of the second rotation trajectory is R. A =R + W / 2, the radius of gyration R of the third gyration trajectory B ==RW / 2, to ensure that chain 1-2-1 and chain 1-2-2 rotate around hinge axis 4 after meshing, the pitch of the relative links of the two chains must be equal to the central angle of hinge axis 4 (e.g., Figure 5 As shown), it can be concluded that the standard pitch P of chain 1-2-2 is... B =P A *R B / R A ;

[0050] Step 3: On the second rotary trajectory, with the standard pitch P A For the chord length, design the angle between the locking structure 8 on the front of the chain plate of chain 2 1-2-1 and the inclined surface 7 on the back;

[0051] Step 4: On the third turning trajectory, with P B Using the chord length as a reference, and taking the angle between the front latch structure and the back inclined surface of the chain plate of chain 2 1-2-1 as a benchmark, the angle between the front latch structure and the back inclined surface of the chain plate of chain 1 1-2-2 is designed using the difference set method. At this point, the chain plate shapes of chain 2 1-2-1 and chain 1 1-2-2 are determined. Based on this, the sleeve, roller, and pin parts of rigid chain 1-2 are then designed; for example... Figure 5 As shown, once the dimensions of the adjacent chain plates of chain two are determined, the dimensions of the chain plates of chain one in the shaded area can be obtained.

[0052] Step 5: Based on the required extension stroke of the rigid chain device 1, design the chain length of chain 1-2-1 and chain 2-2-2 and their storage and running trajectory within the shell (i.e., design guide rail 1 and guide rail 2) to complete the overall design of the arc-shaped rigid chain 1-2.

[0053] This embodiment provides a design method for a rigid chain device, based on which the drawing and manufacturing of a rigid chain device between the upper and lower parts of a limb can be realized.

Claims

1. A robot limb joint drive structure, characterized in that: It includes an upper part of a limb, a lower part of a limb, and a rigid chain device. The bottom end of the upper part of the limb and the top end of the lower part of the limb are hinged by a hinge shaft. The upper part of the limb is equipped with a rigid chain device. The rigid chain output by the rigid chain device moves along an arc-shaped trajectory around the hinge shaft and connects to the lower part of the limb at the head of the rigid chain. The rigid chain device includes a housing located on the inner side of the upper part of the limb and fixedly connected to the upper part of the limb. The inner wall of the housing is provided with a guide rail 1 and a guide rail 2 on both sides respectively. A chain 1 and a chain 2 are slidably connected on the guide rail 1 and the guide rail 2 respectively. An output port is provided at the end of the housing facing the lower part of the limb. The chain 1 and the chain 2 mesh with each other near the output port to form a rigid chain. The rigid chain has an arc-shaped chain structure. The arc-shaped chain structure has the same axis as the hinge shaft 1. A sprocket is provided inside the housing and on the side of the chain 1 near the output port. The sprocket meshes with the chain 1. The central axis of the sprocket passes through the housing and is fixedly connected to the output shaft of a drive motor that is preset outside the housing. The heads of the chain 1 and the chain 2 are fixedly connected to a joint. The joint is hinged to the lower part of the limb. The back of the chain plates of chain one and chain two are inclined surfaces. While the front of chain one and chain two are connected by a buckle, the adjacent chain plates of chain one and chain two are fitted together by two inclined surfaces, thereby realizing the arc-shaped chain structure of the rigid chain; the chain plates of chain one and chain two are engaged by a single buckle or a double buckle. The joint is hinged to the lower part of the limb via hinge shaft two. The cross section of hinge shaft two rotating around hinge shaft one forms rotation trajectory one. The cross section of the chain plate hole axis of chain two rotating around hinge shaft one forms rotation trajectory two. The cross section of the chain plate hole axis of chain one rotating around hinge shaft one forms rotation trajectory three. The distance A between rotation trajectory one and rotation trajectory two and the distance B between rotation trajectory one and rotation trajectory three are the same.

2. The design method of a robot limb joint drive structure as described in claim 1, characterized by comprising the following steps: Step 1: Based on the total load of the lower part of the limb and the end structure connected to the lower part of the limb, select a rigid chain that meets the load requirements, and set the standard pitch of chain two as P. A The standard pitch of chain one is P. B The width after chain 2 and chain 1 mesh is W. The width refers to the vertical distance between the lines connecting the chain plate holes of the two chain plates that mesh with each other. Step 2: Define the axis of hinge axis one as E and the axis of hinge axis two as N. Determine that the cross-section of axis N forms a rotation trajectory one as the lower part of the limb rotates. Let the radius of rotation of rotation trajectory one be R, then the radius of rotation of rotation trajectory two is R. A =R+W / 2, the radius of rotation R of the third rotation trajectory B =RW / 2, from which we can derive the standard pitch P of chain one. B =P A (R) B / R A ); Step 3: On the second rotary trajectory, with the standard pitch P A Design the locking structure on the front of the chain plate of chain two and the angle of the inclined surface on the back, based on the chord length. Step 4: On the third turning trajectory, with P B Given the chord length, and taking the angle between the locking structure on the front and the inclined surface on the back of the chain plate of chain two as a reference, the locking structure on the front and the inclined surface on the back of the chain plate of chain one are designed in the form of difference set. At this time, the chain plate types of chain two and chain one have been determined, and then the sleeve, roller and pin parts of the rigid chain are designed based on this. Step 5: Based on the required extension stroke of the rigid chain device, design the chain lengths of chain one and chain two and their storage and running trajectories within the casing to complete the overall design of the arc-shaped rigid chain.

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