A posture-stiffness-gait integrated reconfigurable joint mechanism

Abstract

The application discloses a posture-rigidity-gait integrated reconfigurable joint mechanism, which comprises a fixed platform 1, a movable platform 2 and first to seventh motion branch chains (3, 4, 5, 6, 7). The seventh branch chain is driven by a main driving push rod to realize the reconfiguration of the posture of the mechanism. The posture-rigidity-gait integrated reconfigurable joint mechanism is suitable for a closed-chain leg-foot type mobile platform, and the closed-chain leg-foot type mobile platform has better driving smoothness, terrain adaptability and passing performance in the movement process.

Description

Technical Field

[0001] This invention relates to a reconfigurable joint mechanism integrating posture, stiffness, and gait; specifically, it is a reconfigurable joint mechanism with two degrees of freedom: rotation and translation. Of these two degrees of freedom, one achieves vibration reduction through external excitation, and the other achieves pitch attitude adjustment through an active push rod. This invention serves as an intermediate connecting mechanism to reduce motion fluctuations caused by the lower mechanism, achieving pitch attitude adjustment while maintaining motion stability. Specifically, when the active push rod is locked, the invention only has the degree of freedom for vertical translation, achieving vibration reduction through external excitation. When the active push rod is released, the invention can change the attitude angle between the two connected platforms. Background Technology

[0002] Currently, commonly used mobile robots include wheeled, tracked, and legged robots. Wheeled and tracked mobile robots have simple structures and controls, but their mobility is somewhat limited. Legged robots have discrete contact with the ground and can adapt to more complex road conditions. This patent is based on a closed-chain legged robot that can work on gravel roads, slopes, muddy roads, ditches, grasslands, and can carry people. Because the walking platform has large center of gravity fluctuations and poor driving stability, the foot trajectory is not sufficient to overcome some high obstacles. A posture-stiffness-gait integrated reconfigurable joint mechanism is adopted to improve the driving smoothness of the walking platform and meet the obstacle-crossing requirements. Summary of the Invention

[0003] This invention addresses the problems of large center of gravity fluctuations, poor driving stability, and insufficient foot trajectory to overcome some high obstacles during the movement of a closed-chain multi-legged mobile platform. An integrated posture-stiffness-gait reconfigurable joint mechanism couples planar series closed-chain five-bar units with spatial parallel units to achieve rotational and translational motion, thus solving the aforementioned problems.

[0004] The technical solution of the present invention:

[0005] A posture-stiffness-gait integrated reconfigurable joint mechanism consists of a fixed platform 1, a moving platform 2, and kinematic chains. The moving platform 2 is rotatably connected to the fixed platform 1 through four kinematic chains.

[0006] Parallel units consist of 3, 4, 5, or 6 branches, while closed-loop five-bar units consist of 7 branches. Details of each branch's composition can be found in the specific implementation method. Figure 3 As shown;

[0007] The third and fifth branches share the same component composition, component shape, mechanical structure, assembly method, and mounting method with the frame.

[0008] This invention utilizes the characteristics of a closed-loop five-bar linkage to restrict the movement of parallel units and applies it to a multi-legged mobile platform. In the parallel units, external excitation serves as the driving force, resulting in irregular movement. Locking the closed-loop five-bar linkage restricts the movement of the two platforms within the parallel unit to vertical within a certain range, due to its motion characteristics. Releasing the closed-loop five-bar linkage allows for changes in the motion attitude angle between the two platforms within a certain spatial range, enabling the platform to autonomously adjust its posture and overcome obstacles, thereby improving the terrain adaptability of the multi-legged mobile platform. Attached Figure Description

[0009] Figure 1 A three-dimensional diagram of the overall structure of a posture-stiffness-gait integrated reconfigurable joint mechanism;

[0010] Figure 2 A schematic diagram of a reconfigurable joint mechanism integrating posture, stiffness, and gait.

[0011] Figure 3 Institutional application diagram;

[0012] Figure 4 Schematic diagram of the geometric relationship of the mechanism;

[0013] Figure 5 Diagram of pitch motion;

[0014] Figure 6 Member 3;

[0015] Figure 7 Member 7.

[0016] Key reference numerals:

[0017] Fixed platform 1, moving platform 2, first branch 3, second branch 4, third branch 5, fourth branch 6, fifth branch 7; member 1 (3-1), member 2 (3-2), member 3 (4-1), member 4 (4-2), member 5 (5-1), member 6 (5-2), member 7 (6-1), member 8 (6-2); the height between fixed platform (1) and fixed platform (2) is h, the length of member 1 (3-1) is l1, and the length of member 2 (3-2) is l1. The length is l2, link 3 (4-1) is a three-link joint, the length between kinematic pair a and kinematic pair b is l3, the length between kinematic pair b and kinematic pair c is l9, the angle between l3 and l9 is θ1, the length of link 4 (4-2) is l4, the length of link 5 (5-1) is l5, the length of link 6 (5-2) is l6, link 7 (6-1) is a three-link joint, the length between kinematic pair e and kinematic pair f is l7, the length between kinematic pair d and kinematic pair e is l 10 ,l7 and l 10The included angle between them is θ2, the length of rod 8 (6-2) is l8, and the length of the active push rod Ac when locked is l. 11 The length of the fixed platform (1) is l 12 . Detailed Implementation

[0018] The invention will be further described below with reference to the accompanying drawings.

[0019] like Figure 1 As shown, a posture-stiffness-gait integrated reconfigurable joint mechanism consists of a fixed platform 1, a moving platform 2, and first to fifth kinematic branches (3, 4, 5, 6, 7). The fixed platform 1 and the moving platform 2 are connected by mounting holes and bearing seats to achieve rotational connection of the first branch 3, the second branch 4, the third branch 5, and the fourth branch 6. The fifth branch 7 consists of rod 3 (4-1), rod 4 (4-2), rod 7 (6-1), rod 8 (6-2), and active push rod Ac. The first branch consists of rod 1 (3-1) and rod 2 (3-2), the second branch 4 consists of rod 3 (4-1) and rod 4 (4-2), the third branch 5 consists of rod 5 (5-1) and rod 6 (5-2), and the fourth branch 6 consists of rod 7 (6-1) and rod 8 (6-2).

[0020] The first branch 3 is rotatably connected to the fixed platform 1 and the moving platform 2, wherein the rod 1 (3-1) and the rod 2 (3-2) in the first branch are hinged by a ball joint; the third branch 5 is symmetrically arranged with the first branch 3 about the YOZ plane and is installed in the same way; the second branch 4 is rotatably connected to the fixed platform 1 and the moving platform 2, wherein the rod 3 (4-1) and the rod 4 (4-2) in the second branch are rotatably connected; the fourth branch 6 is rotatably connected to the fixed platform 1 and the moving platform 2, wherein the rod 7 (6-1) and the rod 8 (6-2) in the fourth branch are rotatably connected; the active push rod Ac in the fifth branch 7 is rotatably connected to the rod 7 (6-1) in the fourth branch 6, and the active push rod Ac is rotatably connected to the rod 3 (4-1) in the second branch.

[0021] like Figure 2 As shown, the analysis of the degrees of freedom of the general configuration of this mechanism yields results with greater general applicability. Therefore, in the fixed coordinate system O-XYZ, the helical system of each kinematic pair in this mechanism is represented as:

[0022]

[0023] The parameters (a\b\c\d\e\f\g\h\i\j\k\l\m) are arbitrary numbers.

[0024] This requires analyzing all joint variables of the mechanism, resulting in the following four loops: 1-2-3-4-9-10-1 is loop I; 1-5-6-4-7-8-1 is loop II; 4-7-11-12-6-4 is loop III; and 1-5-6-4-9-10-1 is loop IV. The velocity closed-loop equations for each loop are then derived.

[0025]

[0026] A multi-loop mechanism can be viewed as a combination of multiple single-loop mechanisms, where each loop is a single-loop mechanism. Therefore, the first-order kinematic constraint equations of a multi-loop mechanism can be represented by a matrix obtained by simultaneously solving the first-order kinematic constraint equations of each loop. The first-order kinematic constraint equations of the multi-loop mechanism are as follows:

[0027]

[0028] In the formula, matrix J is the Jacobian matrix of the mechanism, and w is the joint variable w in the mechanism. i The Jacobian matrix J is a column vector composed of (i = 1, 2, ..., 19). This Jacobian matrix J determines the instantaneous motion of the mechanism in this configuration. The dimension of the Jacobian matrix J is 24 × 19, corresponding to the four loops and 19 kinematic pairs of the mechanism. Analysis shows that the rank of this Jacobian matrix is ​​17. Considering that the mechanism has 19 joint variables, it can be concluded that the instantaneous degree of freedom of the mechanism in any configuration is 2. Therefore, the mechanism has one rotational and one translational degree of freedom, enabling the movement of platform 1 and 2 along the Z-axis and the rotation of platform 2 around the Y-axis.

[0029] like Figure 3 As shown, an integrated posture-stiffness-gait reconfigurable joint mechanism consists of an integrated posture-stiffness-gait reconfigurable joint mechanism A, a legged mobile platform B, a vibration isolation unit spring damper Aa and a spring damper Ab, and an active push rod Ac. The moving platform 2 serves as the frame of the legged mobile platform B. Links 2 (3-2) and 6 (5-2) in the integrated posture-stiffness-gait reconfigurable joint mechanism A are rotatably connected to the fixed frame of the legged mobile platform B, with the kinematic pair in the X direction. Links 4 (4-2) and 8 (6-2) in the integrated posture-stiffness-gait reconfigurable joint mechanism A are rotatably connected to the fixed frame of the legged mobile platform B, with the kinematic pair in the Y direction.

[0030] like Figure 4As shown, the height between fixed platform (1) and fixed platform (2) is h, the length of link 1 (3-1) is l1, the length of link 2 (3-2) is l2, link 3 (4-1) is a three-pronged link, the length between kinematic pair a and kinematic pair b is l3, the length between kinematic pair b and kinematic pair c is l9, the angle between l3 and l9 is θ1, the length of link 4 (4-2) is l4, the length of link 5 (5-1) is l5, the length of link 6 (5-2) is l6, link 7 (6-1) is a three-pronged link, the length between kinematic pair e and kinematic pair f is l7, and the length between kinematic pair d and kinematic pair e is l 10 ,l7 and l 10 The included angle between them is θ2, the length of rod 8 (6-2) is l8, and the length of the active push rod Ac is l. 11 The length of the fixed platform (1) is l 12 :

[0031] l1=l2=l3=l4=l5=l6=l7=l8,

[0032]

[0033] The posture-stiffness-gait integrated reconfigurable joint mechanism satisfies:

[0034] x+l 10 >l 11 ;x+l 11 >l 10 ;l 10 +l 11 >x

[0035] like Figure 5 As shown, the change in the active push rod in the posture-stiffness-gait integrated reconfigurable joint mechanism causes the leg-type mobile platform to rotate in the Y direction, and the overall stiffness of the mechanism decreases during the movement.

Claims

1. A reconfigurable joint mechanism integrating posture, stiffness, and gait, characterized in that: A reconfigurable joint mechanism integrating posture, stiffness, and gait consists of a fixed platform (1), a moving platform (2), and first to fifth kinematic branches (3, 4, 5, 6, 7). The fixed platform (1) and the moving platform (2) are connected by mounting holes and bearing seats to achieve rotational connection of the first branch (3), the second branch (4), the third branch (5), and the fourth branch (6). The fifth branch (7) is an active push rod. The first branch consists of rod 1 (3-1) and rod 2 (3-2), and the second branch (4)... It is composed of rod 3 (4-1) and rod 4 (4-2), the third branch (5) is composed of rod 5 (5-1) and rod 6 (5-2), the fourth branch (6) is composed of rod 7 (6-1) and rod 8 (6-2), the fifth branch (7) is composed of rod 3 (4-1), rod 4 (4-2), rod 7 (6-1), rod 8 (6-2) and active push rod Ac, and the fixed platform (1) and the moving platform (2) are isolated by spring vibration isolators Aa and spring vibration isolators Ab; The posture-stiffness-gait integrated reconfigurable joint mechanism can realize vibration reduction and cushioning as well as walking posture adjustment functions; In the posture-stiffness-gait integrated reconfigurable joint mechanism, the first branch (3) is rotatably connected to the fixed platform (1) and the moving platform (2). The first to fourth branches (3, 4, 5, 6) are connected to the fixed platform (1) and the moving platform (2) in the same way. In the first branch, link 1 (3-1) and link 2 (3-2) are hinged by a ball joint. In the second branch, link 3 (4-1) and link 4 (4-2) are rotatably connected. The third branch (5) and the first branch (3) are symmetrically arranged about the YOZ plane. In the fourth branch... Link 7 (6-1) is rotatably connected to link 8 (6-2); the active push rod 1 in the fifth branch (7) is rotatably connected to link 7 (6-1) in the fourth branch 6, and the active push rod is rotatably connected to link 3 (4-1) in the second branch; the spring damper Aa and the spring damper Ab are rotatably connected to the fixed platform 1 of the posture-stiffness-gait integrated reconfigurable joint mechanism A and the fixed frame in the leg-foot moving platform B, and the kinematic pair direction is the X direction; the spring dampers Aa and Ab are symmetrical about the XOZ plane.

2. The posture-stiffness-gait integrated reconfigurable joint mechanism according to claim 1, characterized in that: The height between fixed platform (1) and fixed platform (2) is h. The length of link 1 (3-1) is l1, the length of link 2 (3-2) is l2, link 3 (4-1) is a three-pronged link, the length between kinematic pair a and kinematic pair b is l3, the length between kinematic pair b and kinematic pair c is l9, the angle between l3 and l9 is θ1, the length of the two kinematic pairs in link 4 (4-2) is l4, the length of link 5 (5-1) is l5, the length of link 6 (5-2) is l6, link 7 (6-1) is a three-pronged link, the length between kinematic pair e and kinematic pair f is l7, and the length between kinematic pair d and kinematic pair e is l 10 ,l7 and l 10 The included angle between them is θ2, the length between the two kinematic pairs in link 8 (6-2) is l8, and the length of the active push rod is l. 11 The length of the fixed platform (1) is l 12 : The posture-stiffness-gait integrated reconfigurable joint mechanism satisfies: x+l 10 >l 11 ;x+l 11 >l 10 ;l 10 +l 11 >x。 3. The posture-stiffness-gait integrated reconfigurable joint mechanism according to claim 1, characterized in that: The moving platform (2) serves as the frame (B) of the legged mobile platform. Links 2 (3-2) and 6 (5-2) in the posture-stiffness-gait integrated reconfigurable joint mechanism (A) are rotatably connected to the frame of the legged mobile platform (B), with the kinematic pair in the X direction. Links 4 (4-2) and 8 (6-2) in the posture-stiffness-gait integrated reconfigurable joint (A) are rotatably connected to the fixed frame of the legged mobile platform (B), with the kinematic pair in the Y direction. The change of the active push rod in the posture-stiffness-gait integrated reconfigurable joint mechanism causes the legged mobile platform to rotate in the Y direction. During the movement, the overall stiffness of the mechanism decreases.

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