Bionic leg and foot mechanism based on four-bar mechanism

Abstract

According to the bionic leg and foot mechanism based on the four-bar mechanism, the crossed four-bar mechanism is combined with a linear actuator to drive knee joints to move, the rotation movement of the knee joints of the human body is simulated in the movement process, the movement flexibility of the leg and foot mechanism is improved, and a robot can more naturally and smoothly complete actions such as walking and running. A double-electric-drive ankle joint driving system is adopted, a parallelogram mechanism is designed, and a driving joint is upwards moved to the top of a shank rod piece, so that the rotational inertia of the leg-foot mechanism can be greatly reduced, the movement flexibility of the ankle joint is improved, and the simulation of complex actions in the walking process of a human body is realized.

Description

Technical Field

[0001] The invention relates to the field of robot design, in particular to a bionic leg and foot mechanism based on a four-bar mechanism. Background Art

[0002] The bionic leg-foot mechanism simulates the activities of human hip, knee and ankle joints through the connection and rotation of components to achieve support and coordination of the body. By imitating the biological characteristics of each joint of the human body, the leg-foot robot's movement flexibility is further improved, while reducing the performance requirements for the drive components. The leg-foot robot has the advantages of intelligence and self-adaptation, and can be used to perform tasks such as search and rescue, exploration and rescue in complex environments.

[0003] By simulating human motion, the working efficiency of leg-foot robots can be further improved, the demand for drive element power and torque can be reduced, and the flexibility of robot motion can be improved. Currently, the simulation of human joint motion is mainly achieved by using a connecting rod mechanism. Specifically, the patent WO2024073135A1 [system and methods for a robot knee joint assembly] discloses a four-bar mechanism using a linear actuator to simulate the human knee joint. The disadvantage is that the rotation center of the knee joint is fixed and the change of the instantaneous center of motion during the rotation of the human knee joint cannot be simulated. The patent CN1152060075B [a bionic knee joint mechanism based on a tensegrity structure] uses a tensegrity mechanism and a four-bar mechanism to simulate the biological characteristics of the human knee joint. At the same time, the four-bar mechanism can be used to achieve self-locking. The disadvantage is that the structure is complex, there are many components, and it is difficult to achieve precise drive control. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and provide a bionic leg-foot mechanism based on a four-bar mechanism, so as to realize the change of the rotation center during the rotation process of the knee joint, and the structure is simple and compact.

[0005] The technical solution of the present invention is: a bionic leg-foot mechanism based on a four-bar mechanism, comprising a thigh bar, a shank bar and a sole plate;

[0006] The rotation of the knee joint between the thigh rod and the shank rod is realized by a connecting rod, a triangular connecting rod and a linear actuator. The thigh rod, the shank rod, the connecting rod and the triangular connecting rod together constitute a cross four-bar mechanism. The triangular connecting rod is driven by the linear actuator to drive the connecting rod to realize the rotation of the shank rod, and the rotation center changes with the rotation process.

[0007] The rotation of the ankle joint between the calf rod and the plantar plate is achieved through two parallel ankle rotation joints, two ankle rotation joint output rods and two actuating rods. The two ankle rotation joints are arranged on the upper side of the calf rod, and the output ends of the ankle rotation joints are connected to the ankle rotation joint output rods, and then connected to the plantar plate through the actuating rods. The ankle end of the calf rod is connected to the plantar plate, and the plantar plate is driven by the two ankle rotation joints to achieve pitch and lateral swing movements.

[0008] Furthermore, the fixed end of the linear actuator is installed on the thigh rod, the output end is connected to one connecting end of the triangular connecting rod, and the other two connecting ends of the triangular connecting rod are respectively connected to the knee end of the thigh rod and the knee end of the calf rod. One end of the connecting rod is connected to the knee end of the thigh rod, and the other end is connected to the knee end of the calf rod.

[0009] Furthermore, the triangular connecting rod is designed as a V-shaped block, the upper two connecting ends of the V-shaped block are connected to the knee end of the thigh rod and the linear actuator, and the lower one connecting end is connected to the knee end of the calf rod.

[0010] Furthermore, the hip end of the thigh rod is connected with a hip rotation joint, which is fixed to the platform through the hip rotation joint to achieve rotation of the hip joint.

[0011] Furthermore, the ankle end of the calf rod is connected to the sole plate through a cross hinge.

[0012] Furthermore, the actuating rod is connected to the rear end of the sole plate, and the ankle end of the calf rod is connected to the middle part of the sole plate.

[0013] Furthermore, two connecting rods are symmetrically installed on the left and right sides of the knee joint.

[0014] Furthermore, the thigh rod is composed of a rod member that transitions from a straight section to a convergent section, the straight section is the hip end, and the convergent section is the knee end.

[0015] The present invention also provides a bionic structure, comprising the bionic leg-foot mechanism based on the four-bar mechanism as described above.

[0016] The present invention also provides a bionic robot, comprising a bionic leg and foot mechanism based on the four-bar mechanism as described above.

[0017] The advantages of the present invention compared with the prior art are:

[0018] (1) The present invention innovatively proposes a small bionic knee joint mechanism with a variable rotation center based on a cross-four-bar mechanism and a triangular connecting rod. The cross-connecting rod mechanism is driven by a linear actuator to simulate the human knee joint, and the rotation center changes during the knee joint rotation process. The structure is simple and compact, and the rod connection position can be adjusted to adjust the rotation center trajectory curve. It can better simulate the rotation movement of the human knee joint during the movement process, improve the movement flexibility of the leg and foot mechanism, and enable the robot to complete walking, running and other movements more naturally and smoothly. At the same time, the cross-four-bar mechanism can be used to compress the front and rear length of the knee joint as much as possible during the entire movement process, reducing the overall mass and volume of the robot.

[0019] (2) The present invention innovatively proposes a dual-electric drive ankle joint mechanism based on a spatial parallel four-bar mechanism, which adopts a dual-electric drive ankle joint system to drive the joint to the top of the calf rod, greatly reducing the leg size and inertia. The calf rod and the foot component are connected by a cross hinge, and a connecting rod is used to drive the foot to simulate the complex movements of the human body during walking, thereby increasing the flexibility of the ankle joint movement.

[0020] (3) The present invention proposes to use a linear actuator to drive a connecting rod to drive the knee joint of the leg to move, which is close to the force and torque transmission mode of the human leg and provides support when the leg-foot mechanism touches the ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the principle diagram of the cross four-bar mechanism of the present invention;

[0022] Figure 2 Schematic diagram of a bionic leg and foot mechanism in an embodiment of the present invention;

[0023] Figure 3 Schematic diagram of the bionic leg and foot mechanism assembly in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to better understand the technical solution of the present invention, the specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. The parts of each structure in the accompanying drawings will be described separately. It is worth noting that the components not shown in the drawings or not described in words are forms known to ordinary technicians in the relevant technical field.

[0025] The present invention uses a cross-four-bar mechanism combined with a linear actuator to drive the knee joint movement, simulating the rotational movement of the human knee joint during the movement process, improving the flexibility of the leg-foot mechanism, and enabling the robot to complete walking, running and other movements more naturally and smoothly. The dual-electric drive ankle joint system is used to design a parallel quadrilateral mechanism to achieve two-degree-of-freedom movement of the sole plate, and the driving joint is moved up to the top of the calf rod, which can greatly reduce the rotational inertia of the leg-foot mechanism, improve the flexibility of the ankle joint movement, and achieve the simulation of complex movements of the human body during walking.

[0026] like Figure 1 As shown, the cross four-bar mechanism designed by the present invention for use in a bionic leg-foot mechanism comprises a thigh bar, a shank bar, a linear actuator, a rocker, and a triangular connecting rod. The linear actuator pushes the triangular connecting rod to move around the thigh bar, driving the shank bar and the rocker to rotate about a variable rotation center in a plane.

[0027] like Figure 2 As shown, the bionic leg-foot mechanism proposed by the present invention includes a thigh rod 1, a linear actuator 2, an actuator rod 3, a cross hinge 4, a shank rod 5, a foot plate 6, a hip rotation joint 7, a connecting rod 8, an ankle rotation joint 9, a thigh rod connecting shaft 10, a connecting rod rotation shaft 11, a V-shaped block 12, and an ankle rotation joint output rod 13. The thigh rod 1 is fixed on the platform through the hip rotation joint 7 to realize the rotation movement of the hip joint. The fixed end of the linear actuator 2 is installed on the thigh rod 1, and the output end is fixed on the V-shaped block 12. The V-shaped block 12 is also connected to the thigh rod 1 and the shank rod 5 through an axle pin. In order to achieve the balance of the forces on both sides, connecting rods 8 are installed on both sides. One end of the connecting rod 8 is connected to the thigh rod and the other end is connected to the shank rod.

[0028] like Figure 3 As shown, the thigh rod 1, the shank rod 5, the connecting rod 8 and the V-shaped block 12 together form a cross four-bar mechanism, and the linear actuator 2 telescopically drives the V-shaped block 12 to drive the connecting rod 8 to realize the rotation movement of the shank rod 5. In order to reduce the inertia when the leg and foot rotate, the two ankle rotation joints 9 are arranged on the upper side of the shank rod 5, that is, the side close to the knee end, and the two ankle rotation joint output rods 13 are respectively fixed on the output ends of the two ankle rotation joints 9. The plantar plate 6 is driven by two actuating rods 3. The plantar plate 6 is connected to the shank rod 5 through a cross hinge 4. The two ankle rotation joints 9, the two ankle rotation joint output rods 13, and the two actuating rods 3 drive the plantar plate 6 to form a parallel four-bar mechanism, which drives the plantar plate 6 to realize the movement of two degrees of freedom of pitch and roll. Preferably, the two ankle rotation joints 9 are arranged in parallel.

[0029] It is to be understood that the present invention is described by way of embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and embodiments that can fall within the scope of the claims of this application all fall within the scope protected by the present invention.

[0030] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A bionic leg-foot mechanism based on a four-bar mechanism, comprising a thigh bar (1), a shank bar (5) and a foot plate (6), characterized in that: The rotation of the knee joint between the thigh rod and the shank rod is achieved through a connecting rod (8), a triangular connecting rod and a linear actuator (2); the thigh rod (1), the shank rod (5), the connecting rod (8) and the triangular connecting rod together form a cross four-bar mechanism; the triangular connecting rod is driven by the linear actuator (2) to drive the connecting rod (8) to achieve the rotation of the shank rod (5), and the rotation center changes with the rotation process; The rotation of the ankle joint between the shank rod and the sole plate is achieved through two parallel ankle rotation joints (9), two ankle rotation joint output rods (13) and two actuating rods (3). The two ankle rotation joints (9) are arranged on the upper side of the shank rod (5). The output ends of the ankle rotation joints (9) are connected to the ankle rotation joint output rods (13), and then connected to the sole plate (6) through the actuating rods (3). The ankle end of the shank rod (5) is connected to the sole plate (6). The sole plate (6) is driven by the two ankle rotation joints (9) to achieve pitch and roll movements.

2. The bionic leg-foot mechanism based on the four-bar mechanism according to claim 1, characterized in that: The fixed end of the linear actuator (2) is mounted on the thigh rod (1), the output end is connected to one connecting end of the triangular connecting rod, the other two connecting ends of the triangular connecting rod are respectively connected to the knee end of the thigh rod (1) and the knee end of the calf rod (5), one end of the connecting rod (8) is connected to the knee end of the thigh rod (1), and the other end is connected to the knee end of the calf rod (5).

3. The bionic leg-foot mechanism based on the four-bar mechanism according to claim 1, characterized in that: The triangular connecting rod is designed as a V-shaped block (12), the two upper connecting ends of the V-shaped block are connected to the knee end of the thigh rod (1) and the linear actuator (2), and the lower connecting end is connected to the knee end of the calf rod (5).

4. The bionic leg-foot mechanism based on the four-bar mechanism according to claim 1, characterized in that: The hip end of the thigh rod (1) is connected to a hip rotation joint (7) and is fixed to the platform via the hip rotation joint (7) to achieve rotation of the hip joint.

5. The bionic leg-foot mechanism based on the four-bar mechanism according to claim 1, characterized in that: The ankle end of the calf rod (5) is connected to the sole plate (6) through a cross hinge (4).

6. The bionic leg-foot mechanism based on the four-bar mechanism according to claim 1, characterized in that: The actuating rod (3) is connected to the rear end of the sole plate (6), and the ankle end of the calf rod (5) is connected to the middle part of the sole plate (6).

7. The bionic leg-foot mechanism based on the four-bar mechanism according to claim 1, characterized in that: Two connecting rods (8) are symmetrically mounted on the left and right sides of the knee joint.

8. The bionic leg-foot mechanism based on the four-bar mechanism according to claim 1, characterized in that: The thigh rod (1) is composed of a rod member that transitions from a straight section to a convergent section, the straight section is the hip end, and the convergent section is the knee end.

9. A bionic structure, characterized in that: It comprises a bionic leg and foot mechanism based on a four-bar mechanism as described in any one of claims 1 to 8.

10. A bionic robot, characterized in that: It comprises two bionic leg and foot mechanisms based on a four-bar mechanism as described in any one of claims 1 to 8.

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