Leg movement mechanism of humanoid robot

Abstract

The application discloses a leg movement mechanism of a humanoid robot, which comprises a hip joint structure, a thigh structure, a knee joint structure, a shank structure, an ankle joint structure and a foot sole structure, an ankle joint pitching driving motor and an ankle joint horizontal rolling driving motor are fixedly installed at the thigh structure close to the hip joint structure, the two motors are connected to two power input gears of a differential mechanism through a transmission mechanism, a power output gear of the differential mechanism is connected to a shank connecting rod through a spherical hinge, and the shank connecting rod is connected to the foot sole structure at the end. The ankle joint pitching driving motor and the ankle joint horizontal rolling driving motor are moved upward to the thigh structure close to the hip joint structure, the mass and the rotational inertia of the shank structure are effectively reduced, the energy consumption is reduced, the movement flexibility and the response speed are improved, and the adaptability to different movement modes and terrains is enhanced through coupling and decoupling control.

Description

Technical Field

[0001] This invention belongs to the field of humanoid robot technology, specifically relating to a leg movement mechanism for a humanoid robot, and more particularly to a leg movement mechanism that moves the ankle and knee joint drive motors upward to optimize the mass distribution of the legs. Background Technology

[0002] With the rapid development of robotics technology, humanoid robots, due to their ability to adapt to human living and working environments, are showing broad application prospects in service, medical, industrial, and special operations fields. The leg mechanism, as the core moving component of a humanoid robot, directly affects the robot's walking stability, movement flexibility, and energy consumption.

[0003] In the design of leg mechanisms for humanoid robots, the actuation methods of the ankle and knee joints have always been a research focus. Currently, the leg mechanisms in related technologies mainly suffer from the following shortcomings:

[0004] 1. An unreasonable layout of the drive motors leads to excessive mass in the lower leg. In existing technology, the pitch and roll degree-of-freedom drive motors of the ankle joint are usually installed at the end of the lower leg or near the ankle joint, resulting in the mass of the lower leg being concentrated at the lower end. This layout results in a large rotational inertia of the leg, requiring more energy to be consumed during dynamic movements such as walking and running, while also limiting the leg's flexibility and response speed.

[0005] 2. The joint drive structure is complex, making it difficult to decouple the control strategy. Some existing solutions use a series drive layout to achieve multi-degree-of-freedom movement of the ankle joint. Although the structure is relatively simple, the dispersed arrangement of drive motors increases the difficulty of control, and the motion coupling between each degree of freedom is strong, making it difficult to achieve independent and precise control. Although some solutions have adopted a parallel drive method, the overall integration is not high, and there is still room for optimization in terms of size and weight.

[0006] 3. Lack of coupling / decoupling motion mechanisms between the knee and ankle joints. During humanoid robot walking, there is a certain degree of coordination between the pitch motion of the knee joint and the pitch motion of the ankle joint. However, few existing technologies can achieve flexible motion coupling and decoupling control between the two, which limits the potential for gait optimization and energy recovery.

[0007] Therefore, there is an urgent need for a humanoid robot leg movement mechanism that can significantly improve the leg's motion performance and energy utilization efficiency. Summary of the Invention

[0008] This invention aims to provide a leg motion mechanism for a humanoid robot. By moving the ankle joint pitch and roll drive motors and the knee joint pitch drive motor to the thigh near the hip joint, and cooperating with the differential transmission and ball joint output mechanism, the mass of the lower leg is significantly reduced and the rotational inertia of the leg is effectively reduced. At the same time, a coupling / decoupling control mechanism for the knee joint and ankle joint pitch degrees of freedom is introduced to improve the leg's motion performance and energy utilization efficiency.

[0009] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0010] A humanoid robot leg movement mechanism, from top to bottom, includes a hip joint structure, a thigh structure, a knee joint structure, a lower leg structure, an ankle joint structure, and a foot structure connected together;

[0011] The thigh structure is equipped with a hip joint pitch drive motor, a knee joint pitch drive motor, an ankle joint pitch drive motor, and an ankle joint roll drive motor near the hip joint structure. The hip joint structure is fitted onto the output end of the hip joint pitch drive motor. The knee joint pitch drive motor is connected to the knee joint structure via a crank-connecting rod mechanism, and a differential is also provided at the knee joint structure. The ankle joint pitch drive motor and the ankle joint roll drive motor are connected to the first power input gear and the second power input gear of the differential via a transmission mechanism. The power output gear of the differential is connected to the lower leg linkage of the lower leg structure via a ball joint, and the end of the lower leg linkage is connected to the foot structure.

[0012] Furthermore, the transmission mechanism is any one or a combination of several of the following: belt transmission mechanism, chain transmission mechanism, or linkage transmission mechanism.

[0013] Furthermore, the differential is a bevel gear differential or a planetary gear differential, and an axial buffer assembly is provided between the power output gear and the ball joint.

[0014] Furthermore, a motion coupling and decoupling control mechanism is provided between the ankle joint pitch drive motor and the knee joint pitch drive motor to enable independent or coordinated movement of the two.

[0015] Furthermore, the motion coupling and decoupling control mechanism is any one of an electromagnetic clutch, a one-way bearing, or a controllable damper.

[0016] Furthermore, the lower leg connecting rod is a hollow rod-shaped structure with a transmission cable or transmission rod running through it.

[0017] Furthermore, an elastic foot sensor is provided between the foot structure and the lower leg connecting rod to detect ground reaction force and feed it back to the humanoid robot's control system.

[0018] Furthermore, an angle sensor is provided between the thigh structure and the calf structure to monitor the knee and ankle joint angles in real time and feed the data back to the humanoid robot's control system.

[0019] Furthermore, the hip joint pitch drive motor, knee joint pitch drive motor, ankle joint pitch drive motor, and ankle joint roll drive motor are frameless torque motors or flat permanent magnet synchronous motors, and their output ends are integrated with reducers.

[0020] The technical solution of the present invention has the following beneficial technical effects:

[0021] 1. This invention moves the hip joint pitch drive motor, knee joint pitch drive motor, ankle joint pitch drive motor, and ankle joint roll drive motor all to the position of the thigh near the hip joint, so that the lower leg part only retains lightweight components such as the transmission mechanism and lower leg connecting rod; the mass of the lower leg is greatly reduced, and the rotational inertia of the leg is also greatly reduced, significantly improving the robot's motion flexibility and dynamic stability.

[0022] 2. This invention uses a differential to receive the power input from the ankle joint pitch drive motor and the ankle joint roll drive motor. The differential characteristics of the differential are used to synthesize and distribute the two degrees of freedom of motion. The power is then transmitted to the lower leg linkage via a ball joint. This not only makes the structure compact, but also enables decoupled control of the pitch and roll motion, avoiding the problem of mutual interference between degrees of freedom in traditional series structures.

[0023] 3. The present invention also adds a motion coupling and decoupling control mechanism, which enables the ankle and knee joints to achieve coordinated or independent movements according to the needs of the movement mode, significantly enhancing the adaptability of the leg mechanism to different terrains and movement modes. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the overall structure of the present invention. Figure 2 ;

[0026] Figure 3 This is a schematic diagram of the rear side of the present invention.

[0027] The following components are labeled: 1. Hip joint structure; 2. Thigh structure; 3. Lower leg structure; 4. Foot structure; 5. Ankle joint pitch drive motor; 6. Ankle joint roll drive motor; 7. Transmission mechanism; 8. Differential; 8. First power input gear; 81. Second power input gear; 82. Power output gear; 83. Ball joint; 9. Lower leg connecting rod; 10. Knee joint pitch drive motor; 11. Hip joint pitch drive motor; 12. Crank-connecting rod mechanism; 13. Detailed Implementation

[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] Example 1:

[0030] like Figure 1 As shown, this embodiment provides a humanoid robot leg movement mechanism, which includes, from top to bottom, a hip joint structure 1, a thigh structure 2, a calf structure 3, an ankle joint structure, and a foot structure 4.

[0031] Ankle joint pitch drive motor 5 and ankle joint roll drive motor 6 are fixedly installed on the thigh structure 2 near the hip joint structure 1. Both ankle joint pitch drive motor 5 and ankle joint roll drive motor 6 are frameless torque motors with planetary reducers integrated at their output ends. The output shafts of ankle joint pitch drive motor 5 and ankle joint roll drive motor 6 are connected to the first power input gear 81 and the second power input gear 82 of differential 8 via transmission mechanism 7. Differential 8 is a bevel gear differential, and its power output gear 83 is connected to the upper end of lower leg link 10 via ball joint 9. The lower end of lower leg link 10 is connected to foot structure 4.

[0032] The knee joint pitch drive motor 11 and the hip joint pitch drive motor 12 are also fixedly installed on the thigh structure 2 near the hip joint structure 1, above the ankle joint pitch drive motor 5 and the ankle joint roll drive motor 6. The knee joint pitch drive motor 11 drives the lower leg structure 3 to rotate around the knee joint axis through the crank-connecting rod mechanism 13, thereby realizing the flexion and extension movement of the lower leg structure 3.

[0033] A motion coupling and decoupling control mechanism is provided between the ankle joint pitch drive motor 5 and the knee joint pitch drive motor 11. In this embodiment, the motion coupling and decoupling control mechanism is selected as an electromagnetic clutch, which is located on the transmission path between the output shaft of the ankle joint pitch drive motor 5 and the first power input gear 81 of the differential 8. When the electromagnetic clutch is engaged, the ankle joint pitch movement and the knee joint pitch movement are coupled, and the two move in coordination according to a preset transmission ratio; when the electromagnetic clutch is disengaged, the two are decoupled and can be controlled independently.

[0034] In this embodiment, an inertial measurement unit is also installed on the thigh structure 2 to detect leg posture and participate in control decisions. An angle sensor is installed on the lower leg structure 3 to monitor the knee joint angle position in real time.

[0035] During the robot's walking process, the ankle joint pitch drive motor 5, the ankle joint roll drive motor 6, and the knee joint pitch drive motor 11 each output power. The power from the ankle joint pitch drive motor 5 and the ankle joint roll drive motor 6 is combined through the differential 8 and then transmitted to the lower leg linkage 10 through the ball joint 9, driving the foot structure 4 to achieve free movement in both pitch and roll directions.

[0036] When the robot is in the normal walking phase, the control system detects that the leg is in the swing phase through the IMU and controls the electromagnetic clutch to engage, so that the pitching motion of the ankle joint is coupled with the pitching motion of the knee joint. The foot structure 4 automatically adjusts the angle during the leg lifting process to reduce the risk of dragging on the ground.

[0037] When the robot is in a standing support phase or needs to adjust its posture independently, the electromagnetic clutch is disengaged, the pitch motion of the ankle joint is decoupled from the pitch motion of the knee joint, and the foot structure 4 can independently respond to ground reaction force and posture requirements to make adjustments.

[0038] Since the ankle joint pitch drive motor 5, the ankle joint roll drive motor 6, and the knee joint pitch drive motor 11 are all moved to the position of the thigh structure 2 near the hip joint structure 1, and only lightweight transmission components such as the lower leg link 10 are retained on the lower leg structure 3, the mass and rotational inertia of the lower leg structure 3 are significantly reduced, thereby reducing the energy consumption of leg swing and improving the motion response speed.

[0039] Example 2:

[0040] This embodiment is also a humanoid robot leg motion mechanism, basically the same as Embodiment 1, except that the motion coupling and decoupling control mechanism is a controllable damper, which is set on the transmission path between the knee joint pitch drive motor 11 and the crank-connecting rod mechanism 13. By adjusting the damping coefficient of the damper, different degrees of coupling between the ankle joint pitch degree of freedom and the knee joint pitch degree of freedom can be achieved, that is, continuous adjustment from complete coupling to complete decoupling can be achieved, which better adapts to the gait control requirements under complex terrain.

[0041] Meanwhile, in this embodiment, the differential 8 is selected as a planetary gear differential, and an axial buffer assembly, which is a wave spring, is provided between the power output gear 83 and the ball joint 9 to absorb axial impact loads during transmission and protect the ball joint 9 and the differential 8 from damage. The lower leg link 10 is selected as a hollow tube structure of carbon fiber composite material, with a transmission rod passing through it to transmit the power of the differential 8 to the drive end of the foot structure 4 via the ball joint 9. An elastic foot sensor is provided between the foot structure 4 and the lower leg link 10 to detect the ground contact reaction force. Based on the feedback signals from the foot sensor and the IMU, the control system adjusts the output torque of each drive motor and the state of the motion coupling and decoupling control mechanism in real time to achieve smooth contact between the foot structure 4 and the ground and adaptive posture adjustment.

[0042] Example 3:

[0043] The difference between this embodiment and Embodiment 1 is that the motion coupling and decoupling control mechanism is a one-way bearing, located between the output shaft of the knee joint pitch drive motor 11 and the crank-connecting rod mechanism 13. The one-way bearing allows the knee joint pitch drive motor 11 to extend the lower leg structure 3 when rotating forward, while when rotating in the reverse direction, it links with the power output of the ankle joint pitch drive motor 5. This is suitable for the coordinated control of knee extension and ankle dorsiflexion during robot walking, and effectively utilizes the directional transmission characteristics of the one-way bearing to simplify the control logic.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A leg movement mechanism for a humanoid robot, characterized in that, From top to bottom, it includes the connected hip joint structure, thigh structure, knee joint structure, calf structure, ankle joint structure, and foot structure; The thigh structure is equipped with a hip joint pitch drive motor, a knee joint pitch drive motor, an ankle joint pitch drive motor, and an ankle joint roll drive motor near the hip joint structure. The hip joint structure is fitted onto the output end of the hip joint pitch drive motor. The knee joint pitch drive motor is connected to the knee joint structure via a crank-connecting rod mechanism, and a differential is also provided at the knee joint structure. The ankle joint pitch drive motor and the ankle joint roll drive motor are connected to the first power input gear and the second power input gear of the differential via a transmission mechanism. The power output gear of the differential is connected to the lower leg linkage of the lower leg structure via a ball joint, and the end of the lower leg linkage is connected to the foot structure.

2. The humanoid robot leg movement mechanism according to claim 1, characterized in that, The transmission mechanism is any one or a combination of several of the following: belt drive mechanism, chain drive mechanism, or linkage drive mechanism.

3. The humanoid robot leg movement mechanism according to claim 1, characterized in that, The differential is a bevel gear differential or a planetary gear differential, and an axial buffer assembly is provided between the power output gear and the ball joint.

4. The humanoid robot leg movement mechanism according to claim 1, characterized in that, The ankle joint pitch drive motor and the knee joint pitch drive motor are provided with a motion coupling and decoupling control mechanism to enable independent or coordinated movement of the two.

5. The humanoid robot leg movement mechanism according to claim 4, characterized in that, The motion coupling and decoupling control mechanism is any one of an electromagnetic clutch, a one-way bearing, or a controllable damper.

6. The humanoid robot leg movement mechanism according to claim 1, characterized in that, The lower leg connecting rod is a hollow rod-shaped structure with a transmission cable or transmission rod running through it.

7. The humanoid robot leg movement mechanism according to claim 6, characterized in that, An elastic foot sensor is also provided between the foot structure and the lower leg connecting rod to detect the ground reaction force and feed it back to the humanoid robot's control system.

8. The humanoid robot leg movement mechanism according to claim 7, characterized in that, An angle sensor is also installed between the thigh structure and the calf structure to monitor the knee and ankle joint angles in real time and feed them back to the humanoid robot's control system.

9. The humanoid robot leg movement mechanism according to claim 1, characterized in that, The hip joint pitch drive motor, knee joint pitch drive motor, ankle joint pitch drive motor, and ankle joint roll drive motor are frameless torque motors or flat permanent magnet synchronous motors, and their output ends are integrated with reducers.

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