CN112758209B - Robot leg structure based on seven connecting rods - Google Patents

Abstract

The invention discloses a seven-link leg structure of a robot, comprising a frame, a hip/knee motor is respectively installed at both ends of the frame, and the output shaft of the hip/knee motor is fixed with a hip joint connector; the The connecting part of the hip joint connector is fixedly connected to the thigh link; each thigh link is connected to the calf link through the free hinge of the knee joint; among the two calf links, the first calf link, the first auxiliary leg link and the friction foot Jointly hinged at one point, the second lower leg link and the second auxiliary leg link are jointly hinged at one point, and a sliding wheel is installed at the hinge; the first auxiliary leg link and the second auxiliary leg link are mutually hinged; the first auxiliary leg link A connection spring is connected with the first lower leg link, the second auxiliary leg link and the second lower leg link through the spring; the auxiliary leg link, the lower leg link and the connection spring form a triangular relationship. The invention can reduce the inertia of the foot end, thereby improving the single-leg load-bearing capacity and the foot control degree of the robot.

Description

A seven-link based robot leg structure

technical field

The invention relates to the field of robots, in particular to a seven-link-based robot leg structure.

Background technique

A biped robot is a bionic type of robot that can realize bipedal walking and related actions of the robot. In the future production and life, humanoid biped walking robots can help humans solve many problems, such as a series of dangerous or heavy tasks such as carrying objects and emergency rescue.

The leg structure of the bipedal walking robot is similar to that of human beings, and it can walk like a human being. How to maintain balance without sacrificing speed is one of the obstacles to the development of bipedal robots. Today's state-of-the-art bipedal robots are capable of walking and running at relatively high speeds. However, in complex environments, the ability to walk and run as anti-interference as humans is still "lack" for biped robots.

The existing robot tandem structure and four-bar linkage structure have shortcomings such as low load, weak strength, large energy loss, and large leg inertia, which need to be improved.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a seven-link-based robot leg structure, which can reduce the inertia of the foot, thereby improving the robot's single-leg load-bearing capacity and foot control.

In order to solve the above-mentioned technical problems, the present invention is realized in this way.

A seven-link leg structure of a robot comprises a frame, a hip/knee motor is respectively installed at both ends of the frame, and the output shaft of the hip/knee motor is fixedly connected with a hip connector; The connecting part of the connector is fixedly connected to the thigh link; each thigh link is connected to the lower leg link through the free hinge of the knee joint; among the two lower leg links, the first lower leg link, the first auxiliary leg link and the friction foot are jointly hinged At one point, the second lower leg link and the second auxiliary leg link are jointly hinged at one point, and a sliding wheel is installed at the hinge; the first auxiliary leg link and the second auxiliary leg link are mutually hinged; A connecting spring is connected between the lower leg connecting rod, the second auxiliary leg connecting rod and the second lower leg connecting rod through the spring; the auxiliary leg connecting rod, the lower leg connecting rod and the connecting spring form a triangular relationship.

Preferably, the thigh link is a double link structure, and the double links are parallel to each other.

Preferably, the two lower leg links have shock absorbing structures capable of buffering axial force and absorbing foot end impact.

Preferably, the lower leg link has a two-section structure; one section is provided with a spring accommodating cavity communicating with the outside, and the other section is inserted into the spring accommodating cavity to abut against the buffer in the cavity.

Preferably, the hip/knee motors all use the following motor units:

The motor unit includes brake, brake encoder connector, encoder, motor rotor shaft, motor and harmonic reducer;

The brake encoder connector connects the fixed end of the brake and the magnetic head of the encoder to realize the fixation of the brake and the encoder; one end of the rotor shaft of the motor is fixed to the magnetic ring of the encoder and the rotating end of the brake, and the other end is fixed to the rotor of the motor; The other side of the motor rotor is fixedly connected to the input end of the harmonic reducer; the output end of the harmonic reducer is the output of the entire motor unit.

Preferably, the motor in the motor unit adopts a frameless torque motor.

Preferably, the casing of the harmonic reducer is fixedly connected to the casing of the motor.

Preferably, the housing of the motor provides space for accommodating the brake and the encoder; the motor unit further comprises a motor rear cover, which is fixedly connected with the housing of the motor.

Preferably, the frame provides two motor installation positions, and the hip joint connector is arranged in the motor installation positions; the output end of the motor unit is sequentially connected with the hip joint connector and the hip joint encoder; the hip joint bearing is A deep groove ball bearing, the inner side is fixed to the frame, and the outer side is fixed to the hip joint connector.

Preferably, the thigh link and the calf link are divided into end parts at both ends and a middle rod-shaped connecting part, the end parts are made of aluminum alloy material, and the rod-shaped connecting part is made of carbon fiber material; the robot foot part is made of aluminum alloy Manufactured, a layer of latex is attached to where the robot's feet contact the ground.

Beneficial effects:

(1) The present invention uses a seven-link mechanism as the main structure of the biped robot. The hip/knee motor is responsible for the control tasks of the hip and knee. A high-stiffness spring is added between the auxiliary leg and the calf to absorb the impact of the foot end, so that the seven-bar linkage mechanism can be operated without external force. "Degenerate" into a five-bar mechanism, so that the motor torque at the hip joint is converted into the foot torque in any direction in the seven-link plane, then the position of the foot can be controlled by adjusting the angle of the hip/knee motor, without An additional motor is required at the knee joint, which is equivalent to moving the knee motor up to the hip joint. The upward movement of the motor effectively reduces the inertia of the leg, improves the load-bearing capacity of the robot's single leg, and provides a hardware foundation for the realization of high-speed and heavy-loading of the robot. The foot end design of "foot + wheel" proposed by the present invention imitates the process of human foot contraction and relaxation during walking, and at the same time, the foot end design of "foot + wheel" can absorb more Most of it comes from the impact of the foot.

(2) The shock absorber under the knee joint of the present invention is designed to disperse the force on the foot, so that the high load impact from any direction can be absorbed by the shock absorber. In the "leg drop" stage of the robot, the stored energy is compressed and part of the energy is consumed to reduce the peak torque of the motor; in the "leg lift" stage of the robot, the energy is released during relaxation and energy utilization is improved.

(3) The reduction of leg inertia and joint impact can improve the control of the foot, so that the leg structure of the robot can also run in a good position and posture under extreme and complex conditions. It can also be said that the robot is in complex It has good robustness under working conditions and extreme working conditions.

(4) The solution provided by the embodiment of the present invention does not need to use a dedicated robot joint motor, but only needs to use a frameless torque motor to control the size, speed, and amplitude of the steps. The frameless torque motor can use the domestic frameless motor, which greatly reduces the cost of the robot.

(5) The present invention redesigns the motor unit to maximize the use of the axial space of the motor, so that the space occupancy rate of the robot is greatly improved. Moreover, the integration and layout of the motor unit are independently designed, which further reduces the cost.

(6) The present invention uses aluminum alloy and carbon fiber to make the leg structure of the robot, wherein the carbon fiber rod is used to build the skeleton of the robot thigh and calf, which is similar to the human skeleton, and the aluminum alloy is used to construct the joint of the robot, and the combination of the two is used. to support the robot. The robot's feet are made of aluminum alloy and latex, which simulates the soles of human feet to support the walking and stability of the robot.

Description of drawings

1 is a schematic diagram of the structure of a seven-link leg of the present invention;

Figure 2 is a structural diagram of the lower leg and the buffer structure;

Fig. 3 is a calf structure and a cross-sectional structure diagram of a buffer;

Figure 4 is an isometric view of the motor unit;

Figure 5 is a side view of the motor unit unfolded;

Figure 6 is an isometric view of the frame and hip/knee motor;

Figure 7 is a top view of the frame and the hip/knee motor;

Figure 8 is a top view of the frame and the hip/knee motor after installation;

Among them, 1-frame, 2,3-hip/knee motor, 4-first thigh link, 5-first calf link, 6-first auxiliary leg link, 7-second auxiliary leg link , 8- 2nd calf link, 9- 2nd thigh link, 10- friction foot, 11- sliding wheel, 12- buffer, 13- motor rear cover, 14- brake, 15- brake encoder connector, 16-encoder, 17-motor rotor shaft, 18-motor, 19-harmonic reducer, 20-hip encoder, 21-hip connector, 21a-connecting part, 21b-rotating ring part, 22-hip Spherical bearing, 23 - connecting spring.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

The present invention provides a seven-link leg structure of a robot. Referring to FIG. 1, it mainly includes a frame 1, a thigh link (a first thigh link 4 and a second thigh link 9), a calf link (the first calf link) Link 5 and second lower leg link 8), auxiliary leg link (first auxiliary leg link 6 and second auxiliary leg link 7), friction foot 10 and sliding wheel 11. A hip/knee joint motor 2, 3 is respectively installed on both ends of the frame 1, and the output shaft of the hip/knee joint motor 2, 3 is fixedly connected with the hip joint connector 21. Referring to FIG. 6 , in this embodiment, the hip joint connector 21 is inserted into the groove provided by the frame 1 , and the hip joint connector 21 has a rotating ring portion 21b and a connecting portion 21a connected to each other. The rotating ring portion 21b is fixed on the output shafts of the hip/knee joint motors 2,3, and rotates under the driving of the hip/knee joint motors 2,3. The connecting portion 21a is connected to the thigh link. The connection of the hip joint connector 21 enables the thigh link to rotate about the output shaft of the hip/knee joint motors 2,3. Preferably, the thigh link is a double link structure, and the double links are parallel to each other.

The first thigh link 4 is connected to the first lower leg link 5 through the free hinge of the knee joint; the second thigh link 9 is connected to the second lower leg link 8 through the free hinge of the knee joint. The first lower leg link 5, the first auxiliary leg link 6 and the friction foot 10 are hinged together at one point, the second lower leg link 8 and the second auxiliary leg link 7 are hinged at one point together, and a sliding wheel 11 is installed at the hinge. The ends of the first auxiliary leg link 6 and the second auxiliary leg link 7 that are not connected to the friction foot/sliding wheel are hinged to each other. A connecting spring 23 is connected between the first auxiliary leg link 6 and the first lower leg link 5, and between the second auxiliary leg link 7 and the second lower leg link 8 through the spring to provide the connection between the auxiliary leg and the lower leg. responsiveness between. The auxiliary leg link, the lower leg link and the connecting spring form a triangular relationship.

In order to fit the control model of the three-mass spring oscillator, a buffer is set under the knee joint of the robot to absorb the impact of the foot and improve the energy utilization rate. Referring to Fig. 2 and Fig. 3, the lower leg link has a shock absorbing structure that can buffer the axial force and absorb the impact of the foot end. This kind of buffer design under the knee joint compresses and stores energy during the "leg drop" stage of the robot, while consuming part of the energy to reduce the peak torque of the motor; during the "leg raising" stage of the robot, it relaxes and releases energy to improve energy utilization. In this embodiment, the lower leg link is a two-section structure, one of which is provided with a spring accommodating cavity that communicates with the outside, and the other section is inserted into the spring accommodating cavity and abuts against the buffer 12 in the cavity. The bumper 12 may be a spring.

The present invention further provides a motor unit suitable for this mechanism, which can be used as a hip/knee motor 2,3.

4-5 , the motor unit is structured from left to right as motor rear cover 13 , brake 14 , brake encoder connector 15 , encoder 16 , motor rotor shaft 17 , motor 18 and harmonic reducer 19 . Wherein, the brake encoder connector 15 is connected to the fixed end of the brake 14 and the magnetic head of the encoder 16 to realize the fixing of the brake 14 and the encoder 16 . One end of the motor rotor shaft 17 is fixedly connected to the magnetic ring of the encoder 16 and the rotating end of the brake 14, and the other end is fixedly connected to the rotor of the motor 18, so as to realize the transmission of rotational torque. The other side of the rotor of the motor 18 is fixedly connected to the input end of the harmonic reducer 19 . The output terminal of the harmonic reducer 19 is the output of the entire motor unit. The casing of the harmonic reducer 19 is fixedly connected with the casing of the motor 18 . The housing of the motor 18 provides space for accommodating the brake 14 and the encoder 16 ; the motor unit further includes a motor rear cover 13 , which is fixedly connected to the housing of the motor 18 for waterproof and dustproof functions. The motor in this motor unit structure can use a frameless torque motor instead of an imported robot joint motor, so the cost can be greatly reduced.

Referring to Figure 6 and Figure 7, when installing the motor unit to the rack, the rack 1 needs to provide two motor mounting positions, and the hip joint connector 21 is set in the motor mounting positions; the output end of the motor unit penetrates the mounting positions Connect the hip joint connector 21 to drive the hip joint connector 21 to rotate. The output end of the motor unit is also connected to the hip joint encoder 20 to realize angle detection. The hip joint bearing 22 is a deep groove ball bearing, the inner side is fixed to the frame 1 , and the outer side is fixed to the hip joint connector 21 .

In this embodiment, the device selection is as follows: the motor 21 in the motor unit is a frameless torque motor from TQ Company of Germany, and the model is ILM85x13STD VSS; the harmonic reducer is a combined harmonic reducer from Hamernaco, Japan. The model is CSG-25-100; the encoder selects the encoder from Israel Renishaw Company, the model is RD85-AKSIM; the brake selects the brake RD85-RSV80 from Germany Maier Company.

The operation mode of the seven-link leg structure of the robot of the present invention is as follows:

First, the position and force of the end of the foot are derived by the control algorithm, and the position and torque required by the two hip/knee motors2,3 are solved by the kinematics and dynamics algorithm. Then, the controller sends a signal to control the two motors to output a predetermined angle and torque. In the absence of external force, due to the existence of the connecting spring, the seven-bar linkage "degenerates" into a five-bar linkage, thereby converting the motor torque at the hip joint into the foot moment in any direction in the seven-bar linkage plane, then Foot position can be controlled by adjusting the angle of the two hip/knee motors 2,3. By controlling the appropriate control algorithm, when the robot leg changes from the swing item to the support item (feet landing), the friction foot first touches the ground, at this time the sliding wheel does not touch the ground, and the spring between the calf and the auxiliary leg provides the ground. Under the action of the supporting force of the friction foot, deformation occurs, forcing the angle between the calf and the auxiliary leg to change, so that the sliding wheel contacts the ground, so as to realize the conversion and absorption of the impact of the foot end.

The above specific embodiments only describe the design principle of the present invention, and the shapes and names of the components in the description can be different and are not limited. Therefore, those skilled in the field of the present invention can modify or equivalently replace the technical solutions recorded in the foregoing embodiments; and these modifications and replacements do not depart from the inventive concept and technical solutions of the present invention, and should belong to the protection scope of the present invention.

Claims (9)

1. A robot seven-connecting-rod leg structure is characterized by comprising a rack (1), wherein two ends of the rack (1) are respectively provided with a hip/knee joint motor (2,3), and an output shaft of the hip/knee joint motor (2,3) is fixedly connected with a hip joint connector (21); the connecting part (21a) of the hip joint connector is fixedly connected with thigh connecting rods (4, 9); each thigh connecting rod is freely articulated with a shank connecting rod (5,8) through a knee joint; in the two shank connecting rods, a first shank connecting rod (5), a first auxiliary leg connecting rod (6) and the friction foot (10) are hinged together at one point, a second shank connecting rod (8) and a second auxiliary leg connecting rod (7) are hinged together at one point, and a sliding wheel (11) is arranged at the hinged position; the first auxiliary leg connecting rod (6) and the second auxiliary leg connecting rod (7) are hinged with each other; connecting springs (23) are connected between the first auxiliary leg connecting rod (6) and the first lower leg connecting rod (5) and between the second auxiliary leg connecting rod (7) and the second lower leg connecting rod (8); the auxiliary leg connecting rod, the shank connecting rod and the connecting spring form a triangular relation;

the hip/knee joint motors (2,3) all adopt the following motor units:

the motor unit comprises a brake (14), a brake encoder connector (15), an encoder (16), a motor rotor shaft (17), a motor (18) and a harmonic reducer (19);

the brake encoder connector (15) is connected with the fixed end of the brake (14) and the magnetic head of the encoder (16) to realize the fixation of the brake (14) and the encoder (16); one end of a motor rotor shaft (17) is fixedly connected with a magnetic ring of an encoder (16) and a rotating end of a brake (14), and the other end of the motor rotor shaft is fixedly connected with a rotor of a motor (18); the other side of the rotor of the motor (18) is fixedly connected with the input end of a harmonic reducer (19); the output end of the harmonic reducer (19) is the output of the whole motor unit.

2. Robot seven-link leg construction according to claim 1, characterized in that the thigh links (4,9) are of a double link construction, the double links being parallel to each other.

3. A robot seven-link leg structure according to claim 1, wherein the two shank links have shock absorbing structures for axial force damping and foot end shock absorption.

4. A robot seven-link leg structure according to claim 3, wherein said shank link is a two-piece structure; one section of the buffer is provided with a spring accommodating cavity communicated with the outside, and the other section of the buffer is inserted into the spring accommodating cavity and abuts against the buffer (12) in the cavity.

5. Robot seven-link leg construction according to claim 1, characterized in that the motors (18) in the motor units are frameless torque motors.

6. The robot seven-link leg structure according to claim 1, wherein the housing of the harmonic reducer (19) is fixedly connected to the housing of the motor (18).

7. A robot seven-link leg structure according to claim 1, characterized in that the housing of the motor (18) provides space to accommodate the brake (14) and the encoder (16); the motor unit further comprises a motor rear cover (13), and the motor rear cover (13) is fixedly connected with a shell of the motor (18).

8. Robot seven-link leg construction according to claim 7, characterized in that the frame (1) provides two motor mounting locations in which hip joints connectors (21) are arranged; the output end of the motor unit is fixedly connected with the hip joint connector (21) and the hip joint encoder (20) in sequence; the hip joint bearing (22) is a deep groove ball bearing, the inner side of the hip joint bearing is fixedly connected with the frame (1), and the outer side of the hip joint bearing is fixedly connected with the hip joint connector (21).

9. The robot seven-link leg structure according to claim 1, wherein the thigh link and the shank link are each divided into an end portion at both ends and a rod-like connecting portion in the middle, the end portions are made of an aluminum alloy material, and the rod-like connecting portion is made of a carbon fiber material; the robot foot is made of aluminum alloy, and a layer of latex is connected to the contact position of the robot foot and the ground.

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