CN118907268A - Variable rigidity buffer structure and bionic bipedal robot - Google Patents

Abstract

A variable stiffness buffer structure and a bionic biped robot relate to the field of robot technology. The current legged robots have the problems of poor impact resistance and poor terrain adaptability. The present invention comprises a buffer elastic member, a tendon and a steering support assembly. The steering support assembly is installed on the leg of the robot and can deflect. The buffer elastic member is installed on the steering support assembly and can deflect with the steering support assembly. The tendon connects the buffer elastic member and the foot of the robot and is tensioned. When the foot of the robot contacts the ground, the foot of the robot flips around the ankle joint and pulls the tendon. The buffer elastic member is deformed by the stretching of the tendon. When the foot of the robot is lifted, the foot of the robot is reset under the rebound of the buffer elastic member. As the steering support assembly deflects, the buffer elastic member deflects and the angle between the buffer elastic member and the tendon changes. The resultant force along the tendon direction changes, thereby realizing the change of the stiffness of the variable stiffness buffer structure. The present invention is mainly used for the design of robots.

Description

A variable stiffness buffer structure and a bionic biped robot

Technical Field

The invention relates to the technical field of robots, and in particular to a variable stiffness buffer structure and a bionic biped robot.

Background Art

Humanoid robots are highly flexible, have good adaptability and passability to complex terrains, can freely use tools used by humans, have a human appearance, and are more natural in human-machine interaction, so they have great potential for application in human society. Bipedal walking, which is similar to humans, is more passable than other drive methods such as wheels or belts, so it is of great significance to make the lower limb structure design of humanoid robots more suitable for human legs.

At present, the connection between the legs and feet of humanoid robots is mostly rigid connection. When the legged robot moves, especially during strenuous movements such as jumping, the feet will be subjected to a certain impact force from the ground after contacting the ground. This impact force will be transmitted to the robot's ankle joints and legs, causing the robot's ankle joints, legs or motors on the legs to be subjected to large vibrations, affecting the service life of the robot's feet, legs and motors. Therefore, the current legged robots have the problem of poor impact resistance.

Summary of the invention

In view of this, the present invention provides a variable stiffness buffer structure and a bionic bipedal robot, which utilizes the variable stiffness buffer structure to absorb the impact force exerted on the feet of the footed robot during movement, thereby increasing the impact resistance of the footed robot. At the same time, the variable stiffness buffer structure can also be utilized to change the stiffness of the ankle joint, thereby increasing the adaptability of the bipedal robot to different terrains.

The technical solution adopted by the present invention to solve the above technical problems is:

A variable stiffness buffer structure comprises a buffer elastic member and a tendon, wherein the buffer elastic member and the tendon are arranged on the rear side of the leg, the buffer elastic member is installed on the leg of a robot, and the tendon connects the buffer elastic member and the foot of the robot and is tensioned; when the foot of the robot contacts the ground, the foot of the robot flips around the ankle joint and pulls the tendon, and the buffer elastic member is deformed by the stretching of the tendon; when the foot of the robot is lifted, the foot of the robot is reset under the rebound of the buffer elastic member.

Furthermore, it also includes a steering support assembly, which is installed on the leg of the robot and can deflect, and a buffer elastic member is installed on the steering support assembly and can deflect along with the steering support assembly; as the steering support assembly deflects, the buffer elastic member deflects and the angle between the buffer elastic member and the tendon changes, and the resultant force along the tendon direction changes, thereby realizing a change in the stiffness of the variable stiffness buffer structure.

Furthermore, the steering support assembly includes a steering motor and a support sleeve for supporting a buffer elastic member, the support sleeve is connected to the motor shaft of the steering motor and can rotate with the motor shaft, and the buffer elastic member is built into the support sleeve; when the steering motor is started, the support sleeve rotates with the motor shaft of the steering motor to cause the buffer elastic member to deflect.

Furthermore, it also includes a tensioning wheel and an ankle joint locking assembly for locking the ankle joint; the tensioning wheel is installed on the leg of the robot and can rotate; the ankle joint locking assembly includes a locking slide post, a pressure plate and a slide post locking piece, the pressure plate is placed on the top of the buffer elastic piece and contacts it, the locking slide post passes through the pressure plate, the buffer elastic piece and the support sleeve in sequence and can move axially; one end of the tendon is connected to the lower end of the locking slide post, and the other end of the tendon bypasses the tensioning wheel and is connected to the foot; the slide post locking piece is installed on the leg of the robot, and the slide post locking piece is provided with a locking braking part that cooperates with the locking slide post; when the locking braking part of the slide post locking piece brakes the locking slide post, the position of the locking slide post is locked, the tendon is tensioned and maintained, and the ankle joint position is locked, so that the variable stiffness buffer structure switches from a variable stiffness mode to a pure rigidity mode.

Furthermore, the slide column locking piece is provided with a locking pin, and the locking pin can be driven to extend and retract, and a locking hole is opened at the lower end of the locking slide column. When the locking pin of the slide column locking piece is extended, the locking pin is inserted into the locking hole of the locking slide column to lock the locking slide column.

A bionic biped robot comprises legs and feet, wherein the legs and feet are movably connected to form ankle joints at the connection points; and also comprises a variable stiffness buffer structure; the variable stiffness buffer structure connects the legs and feet to relieve the impact force on the feet of the biped robot when it moves and to increase the terrain adaptability of the biped robot.

Furthermore, it also includes a fuselage and a hip joint driving mechanism; the hip joint driving mechanism connects the fuselage and the legs and drives the legs to perform two-degree-of-freedom movement; the hip joint driving mechanism includes a motor connecting part, a side-swing motor and a hip joint pitch motor, the casing of the side-swing motor is installed on the fuselage, the motor connecting part is connected to the motor shaft of the side-swing motor and rotates with the motor shaft, the casing of the hip joint pitch motor is installed on the motor connecting part, and the legs are connected to the motor shaft of the hip joint pitch motor and rotate with the motor shaft; when the motor connecting part rotates with the motor shaft of the side-swing motor, the motor connecting part drives the hip joint pitch motor and the legs to perform side-swing movement; when the legs rotate with the motor shaft of the hip joint pitch motor, the legs perform pitch movement.

Furthermore, the leg includes a thigh, a calf and a knee joint driving mechanism; the thigh and the calf are movably connected and form a knee joint at the connection point, the knee joint driving mechanism connects the thigh and the calf and drives the calf to perform pitching movement around the knee joint; the knee joint driving mechanism includes a knee joint pitching motor, a crank, connecting rod 1, connecting rod 2 and connecting rod 3, the knee joint pitching motor is installed on the thigh, one end of the crank is connected to the motor shaft of the knee joint pitching motor and rotates with the motor shaft, the other end of the crank is hinged to one end of connecting rod 1, the other end of connecting rod 1 is hinged to one end of connecting rod 2, the other end of connecting rod 2 is hinged to the top of the calf, one end of connecting rod 3 is connected to the connection point between connecting rod 1 and connecting rod 2 and can rotate, and the other end of connecting rod 3 is connected to the thigh and can rotate; when the crank rotates with the motor shaft of the knee joint pitching motor, the torque of the crank is transmitted to the calf via connecting rod 1 and connecting rod 2 in sequence, so that the calf performs pitching movement around the knee joint.

Furthermore, a limit block 1 is provided at the heel of the foot to prevent the calf from flipping backwards, and a limit block 2 is provided at the lower end of the front side of the thigh to prevent the thigh from tipping forward; when the foot-type robot stands, the lower end of the calf abuts against the limit block 1 and can remain motionless, and the limit block 2 on the thigh abuts against the upper end of the calf, and the thigh can remain upright and motionless, thereby realizing the robot's non-driven standing.

Furthermore, the foot comprises a sole, a toe and a torsion spring, the sole and the toe are movably connected via a pin, the torsion spring is sleeved on the pin, and two torsion legs of the torsion spring are respectively in contact with the sole and the toe.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention arranges a variable stiffness buffer structure with rigid-flexible coupling between the legs and feet of the legged robot, and utilizes the elasticity of the variable stiffness buffer structure to absorb the impact force on the feet, thereby increasing the anti-impact ability of the legged robot; and also utilizes the variable stiffness of the variable stiffness buffer structure to adapt to complex road conditions, thereby increasing the adaptability and movement stability of the legged robot.

2. The design of the knee joint drive mechanism in the present invention can not only realize the pitching movement of the calf, but also realize the upright and fully folded forms of the legs. In the fully folded form, the storage volume of the robot is saved. The knee joint pitch motor is arranged on the thigh side and symmetrically arranged with the hip joint pitch motor, which not only ensures the uniformity of the leg mass, but also realizes the long-distance drive of the knee joint, increases the length of the lever arm, and reduces the output torque of the motor. At the same time, it also increases the center of mass of the leg, reduces the inertia of the leg, realizes the lightweight design of the leg, and greatly reduces the difficulty of controlling the leg.

3. In the present invention, mechanical limiters are designed at the heel of the foot and the lower end of the thigh, so that the foot-type robot can stand without drive and avoid the defect of falling down when the power is off.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated as part of this application and are used to provide a further understanding of the present invention.

FIG. 1 is a cross-sectional view of a variable stiffness buffer structure installed on a leg of a robot.

FIG. 2 is a schematic structural diagram of a variable stiffness buffer structure for implementing the present invention.

FIG. 3 is a schematic diagram of the structure in which the variable stiffness buffer structure is installed on the leg of the robot.

FIG. 4 is a schematic diagram of the structure of a foot-type robot implementing the present invention.

FIG. 5 is a schematic diagram of the structure of the legged robot in a fully gathered state.

FIG. 6 is a schematic diagram of the assembly of the fuselage, the hip joint drive mechanism and the thigh.

FIG. 7 is a schematic diagram of the assembly of the thigh, calf and knee joint drive mechanism.

FIG8 is a schematic diagram showing the stiffness change of the variable stiffness buffer structure when it deflects.

Description of reference numerals:

Variable stiffness buffer structure 1, buffer elastic member 11, tensioning wheel 12, tendon 13, tendon tensioning knob 14, steering support assembly 15, mounting frame 151, steering motor 152, support sleeve 153, ankle joint locking assembly 16, locking slide column 161, pressure plate 162, slide column locking member 163;

Body 2;

Thigh 3, limit block 2 31;

calf 4;

Foot 5, sole 51, toe 52, torsion spring 53; limit block 1 54;

Hip joint drive mechanism 6, motor connector 61, sway motor 62, hip joint pitch motor 63;

Knee joint driving mechanism 7 , knee joint pitch motor 71 , crank 72 , connecting rod 1 73 , connecting rod 2 74 , connecting rod 3 75 .

DETAILED DESCRIPTION

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

Embodiment 1:

The feet of existing robots are generally driven by ankle joint drive components to achieve pitch motion. However, the general ankle joint drive components drive the feet in a purely rigid manner. When the legged robot moves, especially during strenuous movements such as jumping, the feet will be subject to a certain impact force from the ground after contacting the ground. This impact force will be transmitted to the legs of the robot, causing the robot's legs or the motors on the legs to be subject to greater vibration, affecting the service life of the robot's feet, legs, and motors. In addition, the ankle joint stiffness required for bipedal robots to walk on different surfaces is different, and a fixed ankle joint stiffness cannot improve the terrain adaptability of the bipedal robot.

To this end, as shown in Figures 1 to 8, this embodiment provides a variable stiffness buffer structure, including a buffer elastic member 11, a tendon 13 and a tendon tensioning knob 14. The leg and foot of the robot are movably connected and form an ankle joint at the connection point. The buffer elastic member 11 and the tendon 13 are arranged on the rear side of the leg. The buffer elastic member 11 is installed on the leg of the robot. A threading hole is opened at the foot of the robot and close to the heel. The tendon tensioning knob 14 is installed on the instep of the foot of the robot. The buffer elastic member 11 is connected to one end of the tendon 13 and deforms with the stretching of the tendon 13. The other end of the tendon 13 passes through the threading hole on the foot of the robot and is connected to the tendon tensioning knob 14. The tendon 13 is pre-tightened by twisting the tendon tensioning knob 14.

In this embodiment, the foot and leg of the foot-type robot are connected through the ankle joint and the variable stiffness buffer structure. Since the variable stiffness buffer structure is composed of a buffer elastic member 11 and a tendon 13, the tendon 13 is a long flexible member of the rope type, and the buffer elastic member 11 can be a spring, an elastic component formed by stacking multiple disc springs, or other elastic elements that can be deformed along the extension direction of the tendon 13. Therefore, the variable stiffness buffer structure is an elastic flexible member as a whole. When the foot-type robot walks, jumps, etc., the foot of the robot will be subjected to impact force at the moment of contact with the ground, and under this impact force, it will flip around the ankle joint and pull the tendon 13. The buffer elastic member 11 is deformed by the stretching of the tendon 13, absorbing part of the impact force and anti-interference force, playing a buffering role for mechanical parts such as the foot, ankle joint, and leg, extending the service life of the foot-type robot, and improving the stability of the robot during movement. When the leg of the foot-type robot is lifted, the buffer elastic member 11 is reset under its own resilience, and the foot is reset by flipping around the ankle joint through the tendon 13.

As shown in Figures 1, 2 and 3, since the footed robot needs to adapt to different usage environments to increase its versatility. Generally, the usage environment it faces is soft ground such as sand or hard ground such as asphalt. When facing soft ground, the footed robot is walking or jumping, and the deformation of the soft ground will absorb the impact force between the footed robot and the ground. If the variable stiffness buffer structure has low rigidity/high elasticity, it will cause the ankle joint to deform more easily, and the stability of the footed robot on the soft ground will be poor. When facing hard ground, the impact force between the footed robot and the ground is large. If the variable stiffness buffer structure has high rigidity/low elasticity, the buffering effect of the variable stiffness buffer structure is poor, which will still cause the foot to be subjected to large impact force and anti-interference force.

To this end, the variable stiffness buffer structure described in this embodiment also includes a steering support assembly 15 for changing the stiffness of the variable stiffness buffer structure. Specifically, the steering support assembly 15 includes a mounting frame 151, a steering motor 152, and a support sleeve 153 for supporting the buffer elastic member 11. The mounting frame 151 is fixedly mounted on the leg of the robot, the housing of the steering motor 152 is mounted on the mounting frame 151, and the support sleeve 153 is mounted on the mounting frame 151 via a pin shaft and can rotate around the pin shaft. At the same time, the support sleeve 153 is connected to the motor shaft of the steering motor 152 and rotates under the drive of the motor shaft. The motor shaft is coaxially arranged with the pin shaft to avoid rotation interference; the buffer elastic member 11 is built into the support sleeve 153.

In this embodiment, the buffer elastic member 11 is installed on the leg of the robot through the steering support assembly 15. When the steering support assembly 15 is in the initial position, the deformation direction of the buffer elastic member 11 is close to 180° with the extension direction of the tendon 13. At this time, the buffer elastic member 11 is easily deformed under the tension of the tendon 13; when the steering support assembly 15 is deflected, the buffer elastic member 11 will also deflect together. At this time, the angle between the buffer elastic member 11 and the tendon 13 gradually becomes smaller. When the elongated length of the buffer elastic member 11 remains unchanged, the elastic force of the buffer elastic member 11 remains unchanged, but the resultant force along the tendon direction increases, and the ankle joint stiffness increases. Therefore, with the change of the angle between the buffer elastic member 11 and the tendon 13, the stiffness of the variable stiffness buffer structure can be changed to adapt to the use of different road conditions and increase the stability of the robot movement. When the footed robot moves from a hard ground to a soft ground, the steering motor 152 is started, the support sleeve 153 rotates with the motor shaft of the steering motor 152, and the buffer elastic member 11 deflects together with the support sleeve 153. When the buffer elastic member 11 deflects, the angle between the buffer elastic member 11 and the tendon 13 gradually decreases, and the tension of the tendon 13 gradually increases, so as to increase the stability of the connection between the foot and the leg when the footed robot is on a soft ground. On the contrary, when the footed robot moves from a soft ground to a hard ground, the steering motor 152 is reversed, the support sleeve 153 rotates with the motor shaft of the steering motor 152, and the buffer elastic member 11 deflects together with the support sleeve 153. When the buffer elastic member 11 deflects, the angle between the buffer elastic member 11 and the tendon 13 gradually increases, and the tension of the tendon 13 gradually decreases, the rigidity of the variable stiffness buffer structure decreases, and the buffering performance increases, so that more impact force can be absorbed. In other words, this embodiment increases the ability of the footed robot to adapt to different terrains through the design of the steering support assembly 15.

As shown in Figures 1, 2 and 3, in addition to adapting to soft or hard road conditions, legged robots also need to adapt to flat and rugged road conditions. When facing a flat road, the walking speed of the legged robot needs to be increased. If the robot's ankle joint has degrees of freedom, it will increase the difficulty of controlling the robot's movement. When facing a rugged road with more complex road conditions, in order to increase the stability of the robot's movement, the walking speed of the legged robot will be reduced. If the robot's ankle joint is locked, the adaptability of the legged robot will be reduced.

To this end, the variable stiffness buffer structure described in this embodiment also includes a tensioning wheel and an ankle joint locking assembly 16 for locking the ankle joint; the tensioning wheel is installed on the leg of the robot and can rotate; the ankle joint locking assembly 16 includes a locking slide post 161, a pressure plate 162 and a slide post locking piece 163, the pressure plate 162 is placed on the top of the buffer elastic piece 11 and contacts it, and the locking slide post 161 passes through the pressure plate 162, the buffer elastic piece 11 and the support sleeve 153 in sequence and can move axially. One end of the tendon 13 is connected to the lower end of the locking slide column, and the other end of the tendon 13 passes around the tensioning wheel and is connected to the tendon tensioning knob 14; the slide column locking piece 163 is installed on the leg of the robot, and the slide column locking piece 163 is provided with a locking brake part that cooperates with the locking slide column 161. Specifically, the slide column locking piece 163 is provided with a locking pin, and the locking pin can be driven to retract, and the slide column locking piece 163 is preferably an electromagnetic latch lock; a locking hole is opened at the lower end of the locking slide column 161. When the locking pin of the slide column locking piece 163 is extended, the locking pin is inserted into the locking hole of the locking slide column 161, so that the position of the locking slide column 161 is locked, the tendon 13 is tensioned and maintained, and the variable stiffness buffer structure switches from the variable stiffness mode to the pure rigidity mode.

In this embodiment, when the tendon 13 pulls the locking slide post 161, the locking slide post 161 moves downward along the axis direction of the support sleeve 153 and drives the pressure plate 162 to move downward. The pressure plate 162 squeezes the buffer elastic member 11 so that the buffer elastic member 11 is compressed to absorb energy. When the road condition faced by the foot-type robot is a flat road, the slide post locking member 163 is activated, and the locking brake part of the slide post locking member 163 brakes the locking slide post 161. The locking slide post 161 is locked and cannot move, and thus cannot continue to drive the pressure plate 162 downward to squeeze the buffer elastic member 11 under the pull of the tendon 13; at this time, the tendon 13 is in a tensioned state and maintained, and the robot's foot remains motionless with the robot's leg under the tension of the tendon 13, that is, the ankle joint has been locked and cannot rotate, and the variable stiffness buffer structure switches from the variable stiffness mode to the pure rigidity mode to reduce the control difficulty of the foot-type robot. When the foot-type robot is faced with a complex and rugged road condition, the locking brake part of the slide column locking member 163 disengages from the locking slide column 161, and the locking slide column 161 can move axially and continue to drive the pressure plate 162 downward under the pull of the tendon 13 to squeeze the buffer elastic member 11. The ankle joint is unlocked, and the variable stiffness buffer structure switches from pure rigidity to variable stiffness mode to adapt to walking on rugged roads.

Embodiment 2:

As shown in Figures 4 to 7, this embodiment provides a bionic biped robot, including a body 2, a thigh 3, a calf 4 and a foot 5 arranged in sequence from top to bottom, and also including a hip joint drive mechanism 6, a knee joint drive mechanism 7 and a variable stiffness buffer structure 1. The body 2 and the thigh 3 are connected via the hip joint drive mechanism 6, and the thigh 3 performs pitching and side swinging motions under the drive of the hip joint drive mechanism 6. The thigh 3 and the calf 4 are movably connected via a pin shaft and form a knee joint at the connection point. The knee joint drive mechanism 7 connects the thigh 3 and the calf 4 and drives the calf 4 to perform pitching motion around the knee joint. The calf 4 and the foot 5 are movably connected via a pin shaft and form an ankle joint at the connection point, and the foot 5 can perform pitching motion around the ankle joint. The variable stiffness buffer structure 1 connects the leg and the foot 5 to alleviate the impact force and anti-interference force on the foot 5 when the foot robot moves, and can also achieve the reset of the foot 5 after the pitching motion.

The hip joint driving mechanism 6 comprises a motor connector 61, a sway motor 62 and a hip joint pitch motor 63. The housing of the sway motor 62 is installed on the rear side of the fuselage 2. The motor connector 61 is an L-shaped connector. One side plate of the L-shaped connector is connected to the motor shaft of the sway motor 62 and rotates with the motor shaft. The housing of the hip joint pitch motor 63 is installed on the other side plate of the L-shaped connector. The hip joint pitch motor 63 is located on the outside of the thigh 3. The motor shaft of the sway motor 62 is arranged vertically with the motor shaft of the hip joint pitch motor 63. The thigh 3 is connected to the motor shaft of the hip joint pitch motor 63 and rotates with the motor shaft. When the motor connector 61 rotates with the motor shaft of the sway motor 62, the motor connector 61 drives the hip joint pitch motor 63 and the thigh 3 to sway. When the thigh 3 rotates with the motor shaft of the hip joint pitch motor 63, the thigh 3 pitches around the motor shaft of the hip joint pitch motor 63. In this embodiment, the design of the hip joint driving mechanism 6 enables the thigh 3 to have two degrees of freedom.

Among them, the knee joint driving mechanism 7 includes a knee joint pitch motor 71, a crank 72 and a multi-link assembly composed of connecting rod 1 73, connecting rod 2 74 and connecting rod 3 75. The knee joint pitch motor 71 is installed on the inner side of the thigh 3 and is symmetrically arranged with the hip joint pitch motor 63 to ensure the symmetry of the leg structure and the balance of mass. One end of the crank 72 is connected to the motor shaft of the knee joint pitch motor 71 and rotates with the motor shaft, and the other end of the crank 72 is connected to the calf 4 via a multi-link assembly. Specifically, the other end of the crank 72 is hinged to one end of the connecting rod 1 73, the other end of the connecting rod 1 73 is hinged to one end of the connecting rod 2 74, the other end of the connecting rod 2 74 is hinged to the top of the calf 4, one end of the connecting rod 3 75 is connected to the connecting point of the connecting rod 1 73 and the connecting rod 2 74 and can rotate, the other end of the connecting rod 3 75 is connected to the thigh 3 and can rotate. The design of the connecting rod 3 75 makes the knee joint drive mechanism 7 have only one degree of freedom, ensuring the certainty of the calf movement angle; when the crank 72 rotates with the motor shaft of the knee joint pitch motor 71, the torque of the crank 72 is transmitted to the calf 4 via the connecting rod 1 73 and the connecting rod 2 74 in sequence, so that the calf 4 pitches around the knee joint.

It should be noted that, in the non-driven state, the crank 72 of the knee joint driving mechanism 7 in this embodiment can still rotate around the motor shaft of the knee joint pitch motor 71 under the action of inertia force, and drive the connecting rod 1 73, the connecting rod 2 74 and the calf 4 to swing. In order to ensure that the foot-type robot can maintain an upright state without driving, this embodiment is provided with an opening at the lower end of the thigh 3, and a limit block 2 31 is provided at the opening and close to the front side of the thigh 3, and the upper end of the calf 4 is inserted into the opening of the thigh 3. When the thigh 3 and the calf 4 are in the extreme position, the limit block 2 31 at the lower end of the thigh 3 abuts against the front end surface of the upper end of the calf 4, avoiding the forward tilt of the thigh 3. In other words, the maximum angle between the thigh 3 and the calf 4 is close to 180°, and the non-driven upright state of the thigh 3 and the calf 4 can be achieved under the action of the limit block 2 31. In addition, connecting rod 2 74 adopts an arc-shaped connecting rod, and the arc-shaped connecting rod is bent toward the back of the thigh. The thigh 3 and the calf 4 can be changed from an upright state to a fully retracted state of the leg through the drive of the knee joint drive mechanism 7. The specific driving process is as follows: when the knee joint pitch motor 71 rotates clockwise, the crank 72 rotates clockwise with the motor shaft, and the crank 72 transmits the rotational torque to connecting rod 1 73 and connecting rod 2 74 in turn. Connecting rod 2 74 generates an eccentric thrust on the calf 4, and the calf 4 swings counterclockwise around the knee joint to gradually gather the thigh 3 and the calf 4 until the leg forms a fully retracted state. On the contrary, when the leg changes from a fully folded state to an upright state, when the knee joint pitch motor 71 rotates counterclockwise, the crank 72 rotates counterclockwise with the motor shaft, and the crank 72 transmits the rotating torque to the connecting rod 1 73 and the connecting rod 2 74 in sequence, and the connecting rod 2 74 produces an eccentric pulling force on the calf 4, and the calf 4 swings clockwise around the knee joint to gradually expand between the thigh 3 and the calf 4 until the leg forms an upright state. It should also be noted that in this embodiment, the knee joint pitch motor 71 in the knee joint drive mechanism 7 is arranged at the root of the thigh 3. In addition to forming a symmetrical structure with the hip joint pitch motor 63, it can also realize the long-distance drive of the knee joint, increase the length of the force arm, and reduce the output torque of the motor. At the same time, it also increases the center of mass of the leg, reduces the inertia of the leg, realizes the lightweight design of the leg, and greatly reduces the difficulty of controlling the leg.

The foot 5 includes a sole 51, a toe 52 and a torsion spring 53. The sole 51 and the toe 52 are movably connected via a pin, and the toe 52 can do pitching motion around the pin. The torsion spring 53 is sleeved on the pin, and the two torsion feet of the torsion spring 53 are respectively abutted against the sole 51 and the toe 52 to achieve the reset of the toe 52 after the pitching motion. When the foot robot walks on an uneven road surface, the toe 52 is squeezed by the road surface and flipped, and the torsion spring 53 is deformed at this time. When the foot 5 is lifted, the toe 52 is reset under the rebound force of the torsion spring 53. The design of the torsion spring 53 in the foot 5 in this embodiment can still absorb the impact force received by the foot 5, thereby improving the anti-impact force and anti-interference force of the foot robot. In addition, a limit block 54 is provided at the heel of the foot 5 to prevent the calf 4 from flipping backwards. Generally, the center of gravity of a bipedal robot is biased backward when standing. The bipedal robot relies on its own center of gravity to make the lower end of the robot's shank 4 lean against the inner surface of the limit block 54 and remain motionless, thereby achieving the undriven uprightness of the shank 4.

The following further describes the movement process of the legged robot under different road conditions to further demonstrate the working principle and advantages of the present invention:

Start the hip joint pitch motor 63 and the knee joint pitch motor 71, the thigh 3 rotates with the motor shaft of the hip joint pitch motor 63, and the thigh 3 pitches around the motor shaft of the hip joint pitch motor 63. At the same time, the crank 72 rotates with the motor shaft of the knee joint pitch motor 71, and drives the connecting rod 1 73, the connecting rod 2 74, the connecting rod 3 75 and the calf 4 to swing, and the calf 4 pitches; the calf 4 drives the foot 5 to lift and fall, and the foot 5 of the robot will be subjected to impact force at the moment of contact with the ground, and under this impact force, it will flip around the ankle joint and pull the tendon 13, and the buffer elastic part 11 will be deformed by the stretching of the tendon 13, absorbing part of the impact force and anti-interference force, and playing a buffering role on the foot 5, ankle joint, leg and other mechanical parts, thereby extending the service life of the foot-type robot and improving the stability of the robot during movement.

When the footed robot moves from hard ground to soft ground, the steering motor 152 is started, and the support sleeve 153 rotates along with the motor shaft of the steering motor 152. The buffer elastic member 11 deflects along with the support sleeve 153. As the buffer elastic member 11 deflects, the angle between the buffer elastic member 11 and the tendon 13 gradually decreases, and the tension of the tendon 13 gradually increases, so as to increase the stability of the connection between the foot 5 and the leg when the footed robot is on soft ground.

When the legged robot moves from soft ground to hard ground, the steering motor 152 reverses, the support sleeve 153 rotates along with the motor shaft of the steering motor 152, and the buffer elastic member 11 deflects along with the support sleeve 153. As the buffer elastic member 11 deflects, the angle between it and the tendon 13 gradually increases, and the tension of the tendon 13 gradually decreases. The rigidity of the variable stiffness buffer structure 1 decreases, and the buffering performance increases, so that more impact force can be absorbed.

When the road condition faced by the footed robot is a flat road, the slide locking member 163 is activated, and the locking brake part of the slide locking member 163 brakes the locking slide 161, so that the locking slide 161 is locked and cannot move, and thus cannot continue to drive the pressure plate 162 downward to squeeze the buffer elastic member 11 under the pull of the tendon 13; at this time, the tendon 13 is in a tensioned state and maintained, and the robot's foot 5 remains motionless with the robot's leg under the tension of the tendon 13, that is, the ankle joint has been locked and cannot rotate, and the variable stiffness buffer structure 1 switches from a variable stiffness mode to a pure rigidity mode to reduce the control difficulty of the footed robot.

When the foot-type robot is faced with a complex and rugged road condition, the locking brake part of the slide column locking member 163 disengages from the locking slide column 161, and the locking slide column 161 can move axially and continue to drive the pressure plate 162 downward under the pull of the tendon 13 to squeeze the buffer elastic member 11. The ankle joint is unlocked, and the variable stiffness buffer structure 1 switches from a pure rigidity mode to a variable stiffness mode to adapt to walking on rugged roads.

The present invention absorbs the impact between the foot 5 and the ground through the design of the variable stiffness buffer structure 1 and the torsion spring 53 in the foot 5, thereby improving the stability of the robot during walking. The variable stiffness buffer structure 1 can be transformed into two state modes: variable stiffness and pure rigidity, thereby improving the adaptability of the humanoid robot to the ground. At the same time, the knee joint pitch motor 71 in the knee joint drive mechanism 7 is moved up and arranged at the hip joint, so that the center of gravity of the entire leg is moved up, reducing the inertia of the lower limb during swinging, which is beneficial to the stability during walking; in addition, a four-bar linkage is used as the knee joint drive mechanism 7, so that the humanoid robot can be fully folded. Mechanical limiters are used at the knee joint and ankle joint to achieve the non-driven standing of the humanoid robot, thereby avoiding the problem that the humanoid robot may fall when the power is off.

Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims (10)

1. A variable stiffness cushioning structure, characterized by: the robot comprises a buffering elastic piece and tendons, wherein the buffering elastic piece and the tendons are arranged on the rear side of a leg, the buffering elastic piece is installed on the leg of the robot, and the tendons are connected with the buffering elastic piece and the foot of the robot and are tensioned; when the foot of the robot contacts the ground, the foot of the robot turns around the ankle joint and pulls the tendon, and the buffer elastic member is deformed by the stretching of the tendon; when the foot of the robot is lifted, the foot of the robot is reset under the rebound of the buffering elastic piece.

2. A variable stiffness cushioning structure according to claim 1, wherein: the steering support assembly is arranged on the leg of the robot and can deflect, and the buffer elastic piece is arranged on the steering support assembly and can deflect along with the steering support assembly; the deflection of the steering support component is followed, the deflection of the buffering elastic piece is simultaneously changed with the angle of the included angle between the buffering elastic piece and the tendons, the resultant force along the direction of the tendons is changed, and the rigidity of the variable rigidity buffering structure is changed.

3. A variable stiffness cushioning structure according to claim 2, wherein: the steering support assembly comprises a steering motor and a support sleeve for supporting the buffer elastic piece, the support sleeve is connected to a motor shaft of the steering motor and can rotate along with the motor shaft, and the buffer elastic piece is arranged in the support sleeve; the steering motor is started, and the supporting sleeve rotates along with the motor shaft of the steering motor so as to deflect the buffering elastic piece.

4. A variable stiffness cushioning structure according to claim 3, wherein: the ankle locking assembly is used for locking the ankle; the tensioning wheel is arranged on the leg of the robot and can rotate; the ankle joint locking assembly comprises a locking slide column, a pressing plate and a slide column locking piece, wherein the pressing plate is arranged at the top of the buffering elastic piece and contacts with the buffering elastic piece, and the locking slide column sequentially penetrates through the pressing plate, the buffering elastic piece and the supporting sleeve and can axially move; one end of the tendon is connected with the lower end of the locking slide column, and the other end of the tendon bypasses the tensioning wheel and is connected with the foot; the sliding column locking piece is arranged on the leg of the robot and is provided with a locking braking part matched with the locking sliding column; when the locking braking part of the strut lock brakes the locking strut, the position of the locking strut is locked, the tendon is tensioned and maintained, and the ankle position is locked, so that the variable stiffness buffer structure is switched from the variable stiffness mode to the pure stiffness mode.

5. A variable stiffness cushioning structure according to claim 4, wherein: the sliding column locking piece is provided with a lock pin, the lock pin can be driven to stretch and retract, the lower end of the locking sliding column is provided with a lock hole, and when the lock pin of the sliding column locking piece extends out, the lock pin is inserted into the lock hole of the locking sliding column, so that the locking sliding column is locked.

6. A bionic bipedal robot comprises legs and feet, wherein the legs are movably connected with the feet and form ankle joints at connection points; the method is characterized in that: a variable stiffness cushioning structure according to any one of claims 1-5; the rigidity-variable buffer structure is connected with the legs and the feet so as to relieve the impact force received by the feet when the foot-type robot moves and increase the terrain adaptability of the bipedal robot.

7. The biomimetic bipedal robot of claim 6, wherein: the device also comprises a machine body and a hip joint driving mechanism; the hip joint driving mechanism is connected with the body and the leg and drives the leg to do two-degree-of-freedom movement; the hip joint driving mechanism comprises a motor connecting piece, a side swing motor and a hip joint pitching motor, wherein a shell of the side swing motor is arranged on the machine body, the motor connecting piece is connected with a motor shaft of the side swing motor and rotates along with the motor shaft, the shell of the hip joint pitching motor is arranged on the motor connecting piece, and a leg is connected with the motor shaft of the hip joint pitching motor and rotates along with the motor shaft; when the motor connecting piece rotates along with the motor shaft of the side swing motor, the motor connecting piece drives the hip joint pitching motor and the legs to do side swing movement; when the legs rotate along with the motor shaft of the hip joint pitching motor, the legs do pitching motion.

8. The biomimetic bipedal robot of claim 6, wherein: the leg comprises a thigh, a shank and a knee joint driving mechanism; the thigh and the shank are movably connected and form a knee joint at the connecting point, and the knee joint driving mechanism is connected with the thigh and the shank and drives the shank to do pitching motion around the knee joint; the knee joint driving mechanism comprises a knee joint pitching motor, a crank, a first connecting rod, a second connecting rod and a third connecting rod, wherein the knee joint pitching motor is arranged on the thigh, one end of the crank is connected with a motor shaft of the knee joint pitching motor and rotates along with the motor shaft, the other end of the crank is hinged with one end of the first connecting rod, the other end of the first connecting rod is hinged with one end of the second connecting rod, the other end of the second connecting rod is hinged with the top end of the shank, one end of the third connecting rod is connected with a connecting point of the first connecting rod and the second connecting rod and can rotate, and the other end of the third connecting rod is connected with the thigh and can rotate; when the crank rotates along with the motor shaft of the knee joint pitching motor, the torque of the crank is transmitted to the lower leg through the first connecting rod and the second connecting rod in sequence, so that the lower leg does pitching motion around the knee joint.

9. The biomimetic bipedal robot of claim 8, wherein: a first limiting block for preventing the lower leg from overturning backwards is arranged at the heel of the foot, and a second limiting block for preventing the thigh from overturning forwards is arranged at the lower end of the front side of the thigh; when the foot-type robot stands, the lower end of the lower leg is abutted against the limiting block and can be kept motionless, the second limiting block on the thigh is abutted against the upper end of the lower leg, and the thigh can be kept standing motionless, so that the robot stands without driving.

10. The biomimetic bipedal robot of claim 6, wherein: the foot comprises a sole, toes and torsion springs, wherein the sole and the toes are movably connected through pin shafts, the torsion springs are sleeved on the pin shafts, and two torsion feet of the torsion springs are respectively abutted to the sole and the toes.