Six-degree-of-freedom flexible spine for legged robots and variable stiffness damping control method

Abstract

The present application relates to a kind of foot type robot six degrees of freedom flexible spine and its variable stiffness damping control method, the flexible spine includes: front support frame (2), is equipped with first ball hinge base (4-1);Rear support frame (5), is equipped with second ball hinge base (4-2);Six hydraulic dampers (3), the two ends of each hydraulic damper (3) are connected first ball hinge base (4-1) and second ball hinge base (4-2);Each described hydraulic damper (4) is obliquely placed between front support frame (2) and rear support frame (5), adjacent described hydraulic damper (4) mirror image symmetry arrangement;Described hydraulic damper (4) includes the oil cylinder execution part and damping part connected.Compared with prior art, the present application realizes the relative torsion, swing, translation etc. six degrees of freedom movement of front and rear support frame, improves the flexibility of the body of foot type robot, so that foot type robot can adapt to various complex terrains.

Description

Technical Field

[0001] This invention relates to the field of robotics, specifically to a six-degree-of-freedom flexible spine for a legged robot and its variable stiffness damping control method. Background Technology

[0002] Magnetorheological fluids exhibit magnetorheological effects under magnetic fields. That is, under the action of an external magnetic field, magnetorheological fluids can transform from a fluid state to a solid-like state. When the external magnetic field is removed, they can transform back from a solid-like state to a fluid state. Moreover, this transformation is controllable and reversible, with a fast response speed, and is widely used in important fields such as mechanical vibration, civil engineering, and aerospace.

[0003] Currently, the ability of legged robots to adapt to complex terrain makes them potentially valuable in disaster relief and material transport on rugged roads. However, traditional legged robots mostly use rigid spines, which significantly reduces their flexibility during walking. Furthermore, they cannot adjust their landing posture in time or suppress the impact on their feet caused by the inertia of the robot body when they accidentally fall or jump from the air.

[0004] With research into the bodies of animals such as cheetahs and horses, various flexible spines based on biomimicry have been proposed, such as continuous spines using flexible materials and discrete spines with multi-segment springs. However, existing flexible spines still cannot achieve adaptive stiffness and damping in complex terrain, resulting in significant impact on the robot's feet. Furthermore, for larger legged robots, the complex internal structure and numerous components make it difficult to guarantee the load-bearing capacity and flexibility of the flexible spine. Therefore, the design of flexible spines must improve the legged robot's high mobility to adapt to complex terrain and reduce foot impact, while also ensuring the load-bearing capacity of the flexible spine to achieve multi-degree-of-freedom movements such as body torsion under heavy loads. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one of the defects in the prior art by providing a six-degree-of-freedom flexible spine for a legged robot and its variable stiffness damping control method. By designing a six-degree-of-freedom flexible spine, the legged robot's body structure becomes more stable, with stronger load-bearing capacity, and its flexibility is improved to adapt to complex terrain. At the same time, the high power-to-weight ratio of the flexible spine improves the maneuverability during movement, assisting the leg structure in achieving gait such as jumping. Then, a hydraulic damping actuator is introduced into the six-degree-of-freedom flexible spine. The cylinder part can adjust the movement posture of the flexible spine, and the damping part can suppress the vibration of the piston rod, improving the underdamping problem of the hydraulic valve-controlled cylinder system, improving the control accuracy of the flexible spine, reducing the pressure impact of the actuator, and by adjusting the hydraulic pressure and damping magnitude, the damping and stiffness of the spine are adjusted, consuming the inertial energy during the body movement, suppressing body vibration, and improving terrain adaptability. Finally, to address the issues of high zero-field damping and low magnetic field utilization in multi-stage flow channel dampers, a chamfered magnetic ring and magnetic sheet were designed to ensure uniform distribution of the gaps in the magnetorheological fluid flow channels. This not only reduces the throttling damping of the magnetorheological fluid when it flows within the channel gaps, but also makes the internal magnetic field more uniform, thereby improving the dynamic adjustability coefficient of the damper.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] One objective of this invention is to provide a six-degree-of-freedom flexible spine for a legged robot, which is applied to the body of the legged robot and includes:

[0008] The front support frame is equipped with a first ball hinge base;

[0009] The rear support frame is equipped with a second ball hinge base;

[0010] Six hydraulic damping actuators, each with its two ends connected to the first ball hinge base and the second ball hinge base respectively; each hydraulic damping actuator is obliquely placed between the front support frame and the rear support frame, and adjacent hydraulic damping actuators are arranged in a mirror-symmetrical manner;

[0011] The hydraulic damping actuator includes a connected cylinder actuator and a damping part. The cylinder actuator mainly realizes the extension and retraction of the piston rod, while the damping part mainly realizes the resistance to the movement of the piston rod.

[0012] Furthermore, the hydraulic cylinder actuator includes:

[0013] A cylinder that is open at one end and closed at the other end has oil ports on its front and rear side walls that communicate with the inside of the cylinder body.

[0014] The first piston group and the second piston group each include a connected piston and a piston rod. The outer wall of the piston rod of the first piston group is fitted with an end cap that is fixedly connected to the cylinder. The piston rod of the second piston group passes through the closed end face of the cylinder. The pistons of the first piston group and the second piston group abut against each other.

[0015] Furthermore, the damping part includes:

[0016] A damping cylinder, one end of which is fixedly connected to the closed end of the cylinder, and the other end is provided with a damping end cap that is fixedly connected to it.

[0017] The damping piston is located inside the damping cylinder and is located at the end of the piston rod in the second piston group inside the damping cylinder.

[0018] Furthermore, the damping piston comprises:

[0019] The coil support has an annular groove on its outer wall and a multi-stage flow channel inside;

[0020] The coil winding is fitted into the annular groove of the coil support;

[0021] A magnetic sleeve, which is fitted onto the outer wall of the coil support;

[0022] The end caps located on both sides of the coil support are provided with flow channel holes that communicate with the multi-stage flow channels.

[0023] Furthermore, the multi-stage flow channel includes a first magnetic ring, a second magnetic ring, and a magnetic sheet located between the first magnetic ring and the second magnetic ring;

[0024] The end cap plate includes a left end cap and a right end cap of a damping piston. The left end cap of the damping piston and the second magnetic ring, the right end cap of the damping piston and the first magnetic ring, and the spacing between the magnetic sheet and the first and second magnetic rings constitute a magnetorheological fluid flow channel, in which the magnetorheological fluid can flow.

[0025] Furthermore, the end cover plate has a cone on the side facing the coil support, with an arc-shaped transition thereon; the magnetic conductive sheet has external chamfers at both ends; the magnetic conductive ring has an external chamfer on the side facing the end cover plate and an internal chamfer on the side facing the magnetic conductive sheet;

[0026] The arc-shaped transition has the same radius as the outer chamfer of the magnetic ring, and the distance between them is equal to the width of the magnetorheological fluid gap;

[0027] The outer chamfer of the magnetic conductive sheet has the same radius as the inner chamfer of the magnetic conductive ring, and the distance between them is equal to the width of the magnetorheological fluid gap. More specifically, the multi-stage flow channel mainly consists of magnetic conductive rings / sheets, embedded inside the coil support and pressed by left and right damping piston end caps; the magnetic conductive sheets and magnetic conductive rings are distributed alternately, with magnetorheological fluid gaps between each pair, allowing the magnetorheological fluid to flow within the gaps. The chamfer size at both ends of the magnetic conductive sheet is equal to the size of the flow channel gap. The inner hole at one end of the magnetic conductive ring has an outer chamfer, and the outer ring at the other end has an outer chamfer, with the radius of the chamfer equal to the size of the flow channel gap; the flow channel gap remains unchanged at the corners, which not only reduces the magnetic... The rheological fluid experiences throttling and damping when flowing within the channel gap, resulting in a more uniform internal magnetic field. The left / right end caps are equipped with channel holes, allowing the magnetorheological fluid inside the damping cylinder to flow into the multi-channel system. The inner side of the left / right end caps features a cone with a certain curvature, the radius of which is equal to the channel gap. The coil winding is wound on a coil support, and when current is applied, it forms a closed magnetic field through the left / right end caps of the damping piston, the magnetic ring / plate, and the magnetic sleeve, with magnetic field lines passing perpendicularly through the damping channel gap.

[0028] Furthermore, the hydraulic damping actuator is provided with ball heads at both ends, which are hinged to the first ball hinge base and the second ball hinge base, respectively.

[0029] The second objective of this invention is to provide a variable stiffness damping control method for a six-degree-of-freedom flexible spine of a legged robot as described above. The body of the legged robot includes a front trunk, a rear trunk, and a six-degree-of-freedom flexible spine for connecting the two. The coil support, the multi-stage flow channel disposed within the coil support, and the end caps disposed on both sides of the coil support constitute magnetorheological fluid flow channels.

[0030] The variable stiffness damping control method includes the following steps:

[0031] When the impact force on the legged robot is applied to the piston rod through the body, the piston rod drives the piston and the damping piston to reciprocate inside the cylinder and the damper cylinder, respectively.

[0032] First, by adjusting the hydraulic pressure difference between the two ends of the piston inside the cylinder, the displacement target of the piston inside the cylinder is controlled, thereby achieving the adjustment of the overall stiffness of the hydraulic damping actuator;

[0033] Secondly, when the damping piston moves, the magnetorheological fluid inside the damping cylinder flows from one end to the other through the damping piston. However, when there is a magnetic field inside the magnetorheological fluid channel, the magnetorheological fluid inside the channel changes from a liquid state to a near-solid state, which hinders the flow of the magnetorheological fluid from one end of the damping piston to the other end, thereby hindering the movement of the damping piston and realizing the adjustment of the overall damping of the hydraulic damping actuator.

[0034] The third objective of this invention is to provide a method for adjusting the motion posture of a flexible spine in a legged robot, which utilizes the variable stiffness damping control method for a six-degree-of-freedom flexible spine in a legged robot as described above.

[0035] The adjustment method includes the following steps:

[0036] The six hydraulic damping actuators are numbered ①②③④⑤⑥ in sequence, with ①②, ③④, and ⑤⑥ being adjacent to each other. ①② are located on the upper part of the machine body and are arranged in a counterclockwise order. By adjusting the movement of the six hydraulic damping actuators of the flexible spine, the front support frame and the rear support frame have six degrees of freedom, including relative torsion, swing, and translation.

[0037] By simultaneously adjusting the extension / retraction of piston rods ①②, ③④, and ⑤⑥, the relative up-down and left-right translation or swing of the front support frame and the rear support frame can be achieved, thereby driving the body to translate or swing, and realizing the legged robot's functions such as turning and obstacle avoidance.

[0038] Adjusting the piston rod extension / retraction of ①③⑤ and ②④⑥ simultaneously can achieve relative axial rotation of the front and rear support frames, thereby driving the fuselage to rotate and improving the fuselage's flexibility;

[0039] Adjusting the piston rods of ①②③④⑤⑥ simultaneously to extend / retract can achieve relative forward and backward translation of the front and rear support frames, thereby causing the robot body to extend or retract, enabling the robot to enter narrow sections or facilitate transportation.

[0040] Furthermore, when the legged robot jumps, the two hydraulic damping actuators ①② at the upper part of the flexible spine retract, and the four hydraulic damping actuators ③④⑤⑥ at the lower part extend. By changing the angle between the front support frame and the rear support frame, the swing angle between the front and rear legs of the legged robot is increased, thereby improving the gait length of the legged robot. At the moment of landing after the legged robot jumps, the two hydraulic damping actuators ①② at the upper part of the flexible spine extend, and the four hydraulic damping actuators ③④⑤⑥ at the lower part retract, reducing the swing angle between the front and rear legs of the legged robot, storing energy for the next jump, and thus enabling the flexible spine to assist the legged robot in completing the jumping motion.

[0041] Furthermore, during the movement of the legged robot, the impact force of the foot hitting the ground is transmitted to the flexible spine through the front and rear support frames and acts on the hydraulic damping actuator, causing the piston rod to vibrate and increasing the pressure fluctuation in the hydraulic system; the damping part of the hydraulic damping actuator can reduce the vibration of the piston rod and the pressure fluctuation in the hydraulic system by suppressing the movement of the damping piston.

[0042] Furthermore, the damping part of the hydraulic damping actuator can keep the piston rod stationary by controlling the damping part, thereby keeping the legged robot body in a certain posture without the need for a hydraulic oil supply.

[0043] The present invention also provides a legged robot, which mainly includes a front and rear torso, a six-degree-of-freedom flexible spine, and a leg structure. The six-degree-of-freedom flexible spine is located between the front and rear torso and connects them to form the body of the legged robot. Lateral swing joints are provided on both sides of the front and rear torso, and a first-degree-of-freedom motor is installed on both sides of the front and rear torso and drives the lateral swing joints to rotate. The leg structure is connected to the front and rear torso through the lateral swing joints. The leg structure mainly includes a thigh, a lower leg, a second-degree-of-freedom motor, a third-degree-of-freedom motor, and a foot. The second-degree-of-freedom motor mainly drives the hip joint to rotate, and the third-degree-of-freedom motor mainly drives the knee joint to rotate.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] (1) The present invention provides a six-degree-of-freedom flexible spine for a legged robot, which realizes six-degree-of-freedom movements such as relative torsion, swinging and translation of the front and rear support frames, thereby improving the flexibility of the legged robot body and enabling the legged robot to adapt to various complex terrains.

[0046] (2) The present invention provides a six-degree-of-freedom flexible spine for a legged robot, which can change the body length so that the legged robot can avoid tipping over on rough roads by increasing the body length, while avoiding obstacles and facilitating transportation by shortening the body length.

[0047] (3) The present invention provides a six-degree-of-freedom flexible spine for a legged robot, which improves the body strength, makes the body more stable and has a stronger load-bearing capacity. At the same time, the high power advantage of the hydraulic system ensures that the flexible spine can still output greater power to meet the movement of the body under heavy load.

[0048] (4) The present invention provides a six-degree-of-freedom flexible spine for a legged robot. Based on the flexible spine, by adjusting the coordinated movement of six hydraulic damping actuators, the legged robot can achieve a longer jumping gait and improve the mobility of the legged robot during movement.

[0049] (5) The present invention provides a six-degree-of-freedom flexible spine for a legged robot, which introduces a hydraulic damping actuator into the six-degree-of-freedom flexible spine. The cylinder part can adjust the motion posture of the flexible spine, and the damping part can suppress the vibration of the piston rod, thereby improving the underdamping problem of the hydraulic valve control cylinder system, improving the control accuracy of the flexible spine, and reducing the pressure impact of the actuator.

[0050] (6) The present invention provides a six-degree-of-freedom flexible spine for a legged robot. In the face of different motion conditions, the damping and stiffness of the flexible spine can be adjusted by adjusting the oil pressure and damping magnitude of the hydraulic damping actuator, so as to consume the inertial energy during the movement of the robot body, suppress the vibration of the robot body, and improve the terrain adaptability.

[0051] (7) The present invention provides a six-degree-of-freedom flexible spine for a legged robot. Under specific working conditions, the flexible spine can be kept in a fixed posture by controlling the magnetorheological damper without the intervention of the hydraulic oil source, thereby reducing the energy consumption generated by the continuous function of the hydraulic system.

[0052] (8) This invention provides a six-degree-of-freedom flexible spine for a legged robot. To address the problem of large zero-field damping and low magnetic field utilization in multi-stage flow channel dampers, a magnetic ring and magnetic sheet with chamfers are designed to make the gaps in the magnetorheological fluid flow channel uniformly distributed. This not only reduces the throttling damping of the magnetorheological fluid when it flows in the gaps in the flow channel, but also makes the internal magnetic field more uniform and improves the dynamic adjustable coefficient of the damper. Attached Figure Description

[0053] Figure 1 Overall assembly diagram of the legged robot in the embodiment

[0054] Figure 2 Schematic diagram of the extension and retraction of the legged robot body in the embodiment

[0055] Figure 3 Schematic diagram of the vertical translation of the legged robot body in the embodiment.

[0056] Figure 4 Schematic diagram of the left and right translation of the legged robot body in the embodiment

[0057] Figure 5 Schematic diagram of the legged robot's body swinging left and right in the embodiment

[0058] Figure 6 Top view of the legged robot body rotating axially in the embodiment

[0059] Figure 7 Front view of the legged robot body rotating axially in the embodiment

[0060] Figure 8 Front view of the legged robot jumping in the embodiment

[0061] Figure 9 Front view of the legged robot landing in the embodiment

[0062] Figure 10 Front view of a six-DOF flexible spine in the embodiment

[0063] Figure 11A top view of a six-DOF flexible spine in the embodiment.

[0064] Figure 12 Front view of the hydraulic damping actuator in the embodiment

[0065] Figure 13 Cross-sectional view of the hydraulic damping actuator in the embodiment

[0066] Figure 14 Cross-sectional view of the damping piston in the embodiment;

[0067] The following components are labeled in the diagram: front torso 1-1, rear torso 1-2, front support frame 2, hydraulic damping actuator 3, piston rod 3-1, end cap 3-2, cylinder 3-3, piston 3-4, damping cylinder 3-5, damping end cap 3-6, ball hinge base 4, first ball hinge base 4-1, second ball hinge base 4-2, rear support frame 5, rotating hinge 6, damping piston 7, left end cap of damping piston 7-1, magnetic cylinder 7-2, coil winding 7-3, right end cap of damping piston 7-4, coil support 7-5, first magnetic ring 7-6, magnetic sheet 7-7, second magnetic ring 7-8, magnetorheological fluid channel 7-9, first degree of freedom motor 8, side swing joint 9, second degree of freedom motor 10, thigh 11, third degree of freedom motor 12, lower leg 13, foot end 14. Detailed Implementation

[0068] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0069] Example 1

[0070] Please see Figures 10-14 A six-degree-of-freedom flexible spine for legged robots, which is used in the body of legged robots, includes:

[0071] The front support frame 2 is equipped with a first ball hinge base 4-1;

[0072] The rear support frame 5 is equipped with a second ball hinge base 4-2;

[0073] Six hydraulic damping actuators 3 are provided. Each hydraulic damping actuator 3 is connected to the first ball hinge base 4-1 and the second ball hinge base 4-2 at both ends. The first and last ends of each hydraulic damping actuator 3 are provided with ball heads that are hinged to the first ball hinge base 4-1 and the second ball hinge base 4-2, respectively. Each hydraulic damping actuator 4 is obliquely placed between the front support frame 2 and the rear support frame 5, and adjacent hydraulic damping actuators 4 are arranged in a mirror symmetrical manner.

[0074] The hydraulic damping actuator 4 includes a connected cylinder actuator and a damping unit.

[0075] Please refer to the following: Figure 13 In this embodiment, the hydraulic cylinder actuator includes:

[0076] The cylinder 3-3 is open at one end and closed at the other end, and each of its front and rear side walls is provided with an oil port that communicates with the inside of the cylinder 3-3.

[0077] The first piston group and the second piston group each include a connected piston and a piston rod. The outer wall of the piston rod of the first piston group is fitted with an end cap 3-2 that is fixedly connected to the cylinder 3-3. The piston rod of the second piston group passes through the closed end face of the cylinder 3-3. The pistons of the first piston group and the second piston group abut against each other.

[0078] Please refer to the following: Figure 13 In this embodiment, the damping part includes:

[0079] The damping cylinder 3-5 has one end fixedly connected to the closed end of the cylinder 3-3, and the other end is provided with a damping end cap 3-6 fixedly connected thereto.

[0080] The damping piston 7 is located inside the damping cylinder 3-5, and is located at the end of the piston rod in the second piston group inside the damping cylinder 3-5.

[0081] Please refer to the following: Figure 14 In this embodiment, the damping piston 7 includes:

[0082] The coil support 7-5 has an annular groove on its outer wall and a multi-stage flow channel inside;

[0083] The coil winding 7-3 is fitted into the annular groove of the coil support 7-5;

[0084] Magnetic sleeve 7-2 is fitted onto the outer wall of coil bracket 7-5;

[0085] The end caps located on both sides of the coil support 7-5 are provided with flow channel holes that communicate with the multi-stage flow channels.

[0086] Please refer to the following: Figure 14 In this embodiment, the multi-stage flow channel includes a first magnetic ring 7-6, a second magnetic ring 7-8, and a magnetic sheet 7-7 located between the first magnetic ring 7-6 and the second magnetic ring 7-8;

[0087] The end cap plate includes a left end cap 7-1 and a right end cap 7-4 of the damping piston. The left end cap 7-1 of the damping piston and the second magnetic ring 7-8, the right end cap 7-4 of the damping piston and the first magnetic ring 7-6, and the interval between the magnetic sheet 7-7 and the first magnetic ring 7-6 and the second magnetic ring 7-8 constitute a magnetorheological fluid gap, in which the magnetorheological fluid can flow.

[0088] Please refer to the following: Figure 14 In this embodiment, the end cover plate has a cone on the side facing the coil support 7-5, and the cone has an arc-shaped transition; the magnetic conductive sheet 7-7 has external chamfers at both ends; the magnetic conductive ring 7-8 has an external chamfer on the side facing the end cover plate and an internal chamfer on the side facing the magnetic conductive sheet 7-7; the arc-shaped transition of the cone and the radius of the external chamfer of the magnetic conductive ring 7-8 are the same, and the distance between them is equal to the width of the magnetorheological fluid gap; the radius of the external chamfer of the magnetic conductive sheet 7-7 and the radius of the internal chamfer of the magnetic conductive ring 7-8 are the same, and the distance between them is equal to the width of the magnetorheological fluid gap.

[0089] This embodiment also provides a variable stiffness damping control method for a six-degree-of-freedom flexible spine of a legged robot. The body of the legged robot includes a front trunk 1-1, a rear trunk 1-2, and a six-degree-of-freedom flexible spine for connecting the two. The coil support 7-5, the multi-stage flow channel disposed in the coil support 7-5, and the end caps disposed on both sides of the coil support 7-5 constitute a magnetorheological fluid flow channel.

[0090] The variable stiffness damping control method includes the following steps:

[0091] When the impact force on the legged robot is applied to the piston rod through the body, the piston rod drives the piston and the damping piston 7 to reciprocate inside the cylinder 3-3 and the damper cylinder 3-5 respectively.

[0092] First, by adjusting the hydraulic pressure difference between the two ends of the piston inside cylinder 3-3, the displacement target of the piston inside cylinder 3-3 is controlled, thereby achieving the adjustment of the overall stiffness of the hydraulic damping actuator;

[0093] Secondly, when the damping piston 7 moves, the magnetorheological fluid inside the damping cylinder 3-5 flows from one end to the other through the damping piston 7. However, when there is a magnetic field inside the magnetorheological fluid channel, the magnetorheological fluid inside the channel changes from a liquid state to a near-solid state, which hinders the flow of the magnetorheological fluid from one end of the damping piston 7 to the other end, thereby hindering the movement of the damping piston 7 and realizing the adjustment of the overall damping of the hydraulic damping actuator.

[0094] This embodiment also provides a method for adjusting the motion posture of a legged robot's flexible spine, which utilizes the variable stiffness damping control method for a six-degree-of-freedom flexible spine of a legged robot as described above.

[0095] The adjustment method includes the following steps:

[0096] The six hydraulic damping actuators 3 are numbered ①②③④⑤⑥ in sequence, where ①②, ③④, and ⑤⑥ are adjacent to each other. ①② are located on the upper part of the machine body and are arranged in a counterclockwise order. By adjusting the movement of the six hydraulic damping actuators 3 of the flexible spine, the front support frame 2 and the rear support frame 5 have six degrees of freedom, such as relative torsion, swing, and translation.

[0097] By simultaneously adjusting the extension / retraction of piston rods ①②, ③④, and ⑤⑥, the front support frame 2 and the rear support frame 5 can be moved up and down, left and right, or swung, thereby driving the body to move or swung, realizing the legged robot's functions such as turning and obstacle avoidance.

[0098] By simultaneously adjusting the extension / retraction of piston rods ①③⑤ and ②④⑥, the front support frame 2 and the rear support frame 5 can be rotated relative to each other along the axial direction, thereby driving the fuselage to rotate and improving the flexibility of the fuselage.

[0099] By simultaneously adjusting the extension / retraction of piston rods ①②③④⑤⑥, the front support frame 2 and the rear support frame 5 can be moved relative to each other, thereby causing the robot body to extend or retract, enabling the robot to enter narrow sections or facilitate transportation.

[0100] When the legged robot jumps, the two hydraulic damping actuators ①② at the upper part of the flexible spine retract, and the four hydraulic damping actuators ③④⑤⑥ at the lower part extend. By changing the angle between the front support frame 2 and the rear support frame 5, the swing angle between the front and rear legs of the legged robot is increased, thereby improving the gait length of the legged robot. At the moment of landing after the legged robot jumps, the two hydraulic damping actuators ①② at the upper part of the flexible spine extend, and the four hydraulic damping actuators ③④⑤⑥ at the lower part retract, reducing the swing angle between the front and rear legs of the legged robot, storing energy for the next jump, and thus enabling the flexible spine to assist the legged robot in completing the jumping motion.

[0101] Example 2

[0102] A legged robot with a six-degree-of-freedom flexible spine, as referenced Figure 1 , 10 As shown in Figure 11, the legged robot is characterized by the following features: the legged robot includes a forequarter 1-1, a rearquarter 1-2, and a six-degree-of-freedom flexible spine disposed between the forequarter 1-1 and the rearquarter 1-2; both the forequarter 1-1 and the rearquarter 1-2 are provided with leg structures, the leg structures including a second degree-of-freedom motor 10, a thigh 11, a third degree-of-freedom motor 12, a lower leg 13, and a foot end 14 connected in sequence, the second degree-of-freedom motor 10 mainly drives the hip joint to rotate, and the third degree-of-freedom motor 12 mainly drives the knee joint to rotate;

[0103] The front trunk 1-1 and the rear trunk 1-2 are provided with side swing joints 9 on both sides. The first degree of freedom motor 8 is installed on both sides of the front trunk 1-1 and the rear trunk 1-2 and drives the side swing joints 9 to rotate. The second degree of freedom motor 10 is connected to the front trunk 1-1 and the rear trunk 1-2 through the side swing joints 9.

[0104] The six-degree-of-freedom flexible spine consists of a front support frame 2, a rear support frame 5, and a hydraulic damping actuator 3. One side of the front support frame 2 and the rear support frame 5 is provided with a rotating hinge 6, which is fixed to the front torso 1-1 and the rear torso 1-2 respectively. The piston rod 3-1 and the damping end cap 3-6 of the hydraulic damping actuator 3 are respectively provided with internal threads and ball heads are installed on them. A ball joint base 4 is installed on the other side of the front support frame 2 and the rear support frame 5. The hydraulic damping actuator 3 is located between the front support frame 2 and the rear support frame 5, and is connected to the front support frame 2 and the rear support frame 5 respectively via ball heads at both ends. The support frame 5 is connected to the ball joint base 4; the front support frame 2 and the rear support frame 5 are provided with three bases evenly distributed in a ring, each base is provided with two ball joint bases 4, and each ball joint base is connected to a hydraulic damping actuator 3; the three bases on the front and rear support frames 2 and 5 are arranged in an alternating manner, and the six hydraulic damping actuators 3 are connected in sequence without interfering with each other; the hydraulic damping actuator 3 mainly includes a cylinder actuation part and a damping part. The actuation part mainly realizes the extension and retraction movement of the piston rod 3-1, and the damping part mainly realizes the resistance to the movement of the piston rod 3-1.

[0105] like Figure 2 , 3 As shown in Figures 4, 5, 6, and 7, the six hydraulic damping actuators 3 are arranged in the order of ①②③④⑤⑥, where ①②, ③④, and ⑤⑥ are adjacent to each other. By adjusting the movement of the six hydraulic damping actuators 3 of the flexible spine, the front support frame 2 and the rear support frame 5 can achieve six degrees of freedom, such as relative torsion, swing, and translation.

[0106] By simultaneously adjusting the extension / retraction of piston rods 3-1 of ①②, ③④, and ⑤⑥, the front and rear support frames 2 and 5 can be moved or swung relative to each other, thereby driving the body to move or swung, enabling the legged robot to perform functions such as turning and obstacle avoidance.

[0107] Simultaneously adjusting the extension / retraction of piston rods 3-1 of ①③⑤ and ②④⑥ respectively can achieve relative axial rotation of the front and rear support frames 2 and 5; thereby driving the machine body to rotate and improving the flexibility of the machine body;

[0108] By simultaneously adjusting the extension / retraction of piston rods 3-1 (①②③④⑤⑥) to both extend and retract, the relative distance between the front and rear support frames 2 and 5 can be increased or decreased; thereby causing the robot body to extend or retract, enabling the robot to enter narrow sections or facilitating transportation.

[0109] like Figure 8 ,9 As shown, when the legged robot jumps, the two upper hydraulic damping actuators ①② of the flexible spine retract, and the four lower hydraulic damping actuators ③④⑤⑥ extend, increasing the swing angle between the front and rear legs of the legged robot and improving the gait length of the legged robot; at the moment of landing after the legged robot jumps, the two upper hydraulic damping actuators ①② extend, and the four lower hydraulic damping actuators ③④⑤⑥ retract, reducing the swing angle between the front and rear legs of the legged robot, storing energy for the next jump, and thus enabling the flexible spine to assist the legged robot in movement.

[0110] During the movement of the legged robot, the impact force of the foot hitting the ground is transmitted to the flexible spine through the front and rear torso and acts on the hydraulic damping actuator 3, causing the piston rod 3-1 to vibrate and increasing the pressure fluctuation in the hydraulic system; the damping part of the hydraulic damping actuator 3 can reduce the vibration of the piston rod 3-1 and the pressure fluctuation in the hydraulic system by suppressing the movement of the damping piston 7.

[0111] The damping part of the hydraulic damping actuator 3 can keep the piston rod 3-1 stationary by controlling the damping part, thereby keeping the legged robot body in a certain posture without the need for the supply of hydraulic oil.

[0112] like Figure 12 , 13 As shown in Figure 14, the hydraulic damping actuator 3's cylinder actuation part mainly consists of a piston 3-4, a piston rod 3-1, a cylinder 3-3, and an end cap 3-2. The piston 3-4 and piston rod 3-1 are an integral structure. One end of the cylinder 3-3 is open, and the other end is closed, with a shaft hole at the closed end. The piston rod 3-1 is embedded into the cylinder 3-3 through the open end, and the end cap 3-2 is threaded into the open end of the cylinder 3-3. The piston rod 3-1 extends through the shaft hole of the end cap 3-2 and can slide freely on the inner wall of the cylinder 3-3. The cylinder 3-3 has two oil ports, and the extension or retraction of the piston rod 3-1 can be adjusted by adjusting the oil inlet and outlet sequence of the two oil ports.

[0113] The damping section is located at the closed end of cylinder 3-3 and mainly includes damping cylinder 3-5, damping piston 7, and damping end cap 3-6. The two ends of damping cylinder 3-5 are connected to cylinder 3-3 and damping end cap 3-6 respectively by threads. The damping piston 7 is located inside damping cylinder 3-5 and mainly includes damping piston left end cap 7-1, damping piston right end cap 7-4, multi-stage flow channel, coil support 7-5, coil winding 7-3, and magnetic sleeve 7-2. The damping piston left end cap 7-1 is connected to one end of piston rod 3-1 by threads. The damping piston 7 can move inside damping cylinder 3-5 with piston rod 3-1.

[0114] The left end cap 7-1 of the damping piston, the right end cap 7-4 of the damping piston, the coil support 7-5, and the multi-stage flow channel together form the magnetorheological fluid flow channel 7-9. When the damping piston 7 moves, the magnetorheological fluid inside the damping cylinder 3-5 flows from one end to the other through the damping piston 7. However, when there is a magnetic field inside the magnetorheological fluid flow channel 7-9, the magnetorheological fluid inside the magnetorheological fluid flow channel 7-9 changes from a liquid state to a near-solid state, which hinders the flow of the magnetorheological fluid from one end of the damping piston 7 to the other end, thereby hindering the movement of the damping piston 7.

[0115] Preferably, the multi-stage flow channel includes a first magnetic ring 7-6, a second magnetic ring 7-8, and a magnetic sheet 7-7 located between the first magnetic ring 7-6 and the second magnetic ring 7-8;

[0116] The end cap plate includes a left end cap 7-1 and a right end cap 7-4 of the damping piston. The left end cap 7-1 and the second magnetic ring 7-8, the right end cap 7-4 and the first magnetic ring 7-6, and the spacing between the magnetic sheet 7-7 and the first and second magnetic rings 7-6 and 7-8 constitute a magnetorheological fluid flow channel. The magnetorheological fluid can flow in the flow channel. The chamfer size at both ends of the magnetic sheet 7-7 is equal to the size of the flow channel gap. The inner hole at one end of the magnetic ring 7-8 has an outer chamfer, and the outer ring at the other end has an outer chamfer. The radius of the chamfer is equal to the size of the flow channel gap. The flow channel gap remains unchanged at the corners, which not only reduces the throttling damping of the magnetorheological fluid when flowing in the flow channel gap, but also makes the internal magnetic field more uniform.

[0117] Preferably, the left end cap 7-1 and the right end cap 7-4 of the damping piston are provided with flow channel holes, which allow the magnetorheological fluid inside the damping cylinder 3-5 to flow into the multi-stage flow channel through the flow channel holes; the inner side of the left end cap 7-1 and the right end cap 7-4 of the damping piston is provided with a cone with a certain arc radius, the radius of which is equal to the flow channel gap; the coil winding 7-3 is wound on the coil support 7-5, and when current is applied, it can form a closed magnetic field through the left end cap 7-1, the right end cap 7-4 of the damping piston, the first magnetic ring 7-6, the second magnetic ring 7-8, the magnetic sheet 7-7, and the magnetic sleeve 7-2, and the magnetic field lines pass perpendicularly through the damping flow channel gap.

[0118] Working principle:

[0119] 1. Achieve six-degree-of-freedom torsion of the fuselage:

[0120] Six hydraulic damping actuators 3 are arranged in the order ①②③④⑤⑥, with ①②, ③④, and ⑤⑥ adjacent to each other. The cylinders of the six hydraulic damping actuators 3 are connected to an oil source to control the extension and retraction of the piston rod 3-1. The damping part is connected to a current controller to control the current input to each coil winding. When hydraulic oil is supplied to ①② to extend the piston rod 3-1, and to ③④ and ⑤⑥ to retract the piston rod 3-1, the piston rod 3-1 of ①② pushes the ball hinge 4 to separate the front and rear support frames 2 and 5 around the base. The piston rod 3-1 of ③④ and ⑤⑥, through the ball hinge 4, brings the front and rear support frames 2 and 5 around the base closer together. The front and rear support frames 2 and 5 drive the front and rear torso 1-1 and 1-2 to move, causing the robot body to swing. Supplying hydraulic oil to ③④ or ⑤⑥ to extend the piston rod 3-1, and the remaining steps are similar, to control different swinging postures of the robot body. This method can realize the functions of turning and obstacle avoidance of the legged robot.

[0121] When piston rods 3-1 controlling ①③⑤ extend and piston rods 3-1 controlling ②④⑥ retract, the extended piston rods 3-1 push the front and rear support frames 2 and 5 to twist around their axis via ball joints 4, and drive the fuselage to twist via the front and rear torsos 1-1 and 1-2. Similarly, when piston rods 3-1 controlling ②④⑥ extend and piston rods 3-1 controlling ①③⑤ retract, the fuselage twists in the opposite direction.

[0122] By controlling the extension / retraction of piston rods 3-1 of ①②③④⑤⑥ respectively, the relative distance between the front and rear support frames 2 and 5 can be increased / decreased, thereby causing the machine body to extend or retract.

[0123] 2. Assisting legged robots in jumping:

[0124] When the legged robot jumps, the piston rods 3-1 of the two hydraulic damping actuators ①② at the top of the flexible spine retract, while the piston rods 3-1 of the four hydraulic damping actuators ③④⑤⑥ at the bottom extend. The moving piston rods 3-1 act on the front and rear support frames 2 and 5 through the ball joint 4, increasing the swing angle of the front and rear support frames 2 and 5. The front and rear support frames 2 and 5 drive the front and rear torso 1-1 and 1-2 to swing, thereby increasing the swing angle between the front and rear legs of the legged robot. At this time, it assists the legged robot in jumping and increases the gait length of the legged robot. At the moment of landing after the legged robot jumps, the piston rods 3-1 of the two hydraulic damping actuators 3 at the top of the flexible spine extend, while the piston rods 3-1 of the four hydraulic damping actuators 3 at the bottom retract. This controls the swing of the front and rear torso 1-1 and 1-2 to reduce the swing angle between the front and rear legs of the legged robot, thus accumulating power for the next jump.

[0125] 3. Suppress fuselage vibration:

[0126] When controlling the movement of the flexible spine, the piston rod 3-1 of the hydraulic damping actuator 3 will vibrate during extension and retraction, which will drive the damping piston 7 to move within the damper cavity. Alternatively, during the movement of the legged robot, the impact force of the foot 14 colliding with the ground is transmitted to the flexible spine through the leg structure and the front and rear torsos 1-1 and 1-2, and acts on the piston rod 3-1 of the hydraulic damping actuator 3, thereby pushing the piston rod 3-1 and the damping piston 7 to move. The moving damping piston 7 causes the magnetorheological fluid inside the damping cylinder 3-5 to flow from one end to the other through the damping piston 7. At this time, based on the jitter error of the piston rod 3-1, the controller supplies the required current to the coil winding 7-3, thereby forming a closed-loop magnetic field in the magnetorheological fluid channel 7-9. When there is a magnetic field inside the channel, the magnetorheological fluid inside the channel changes from a liquid state to a near-solid state, which hinders the flow of the magnetorheological fluid from one end of the damping piston 7 to the other end, thereby hindering the movement of the damping piston 7 and ultimately suppressing the jitter of the piston rod 3-1. When the jitter is detected, the controller disconnects the coil winding 7-3, and the variable damping control ends.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A six-degree-of-freedom flexible spine for a legged robot, which is applied to the body of the legged robot, characterized in that, include: The front support frame (2) is equipped with a first ball hinge base (4-1). The rear support frame (5) is equipped with a second ball hinge base (4-2). Six hydraulic damping actuators (3) are provided, with each hydraulic damping actuator (3) having its two ends connected to the first ball hinge base (4-1) and the second ball hinge base (4-2) respectively; each of the hydraulic damping actuators (3) is obliquely placed between the front support frame (2) and the rear support frame (5), and adjacent hydraulic damping actuators (3) are arranged in a mirror symmetrical manner; The hydraulic damping actuator (3) includes a connected cylinder actuator and a damping part; The hydraulic cylinder actuator includes: A cylinder (3-3) with one end open and the other end closed has oil ports on its front and rear side walls that communicate with the inside of the cylinder (3-3). The first piston group and the second piston group each include a connected piston and a piston rod. The outer wall of the piston rod of the first piston group is fitted with an end cap (3-2) that is fixedly connected to the cylinder (3-3). The piston rod of the second piston group passes through the closed end face of the cylinder (3-3). The pistons of the first piston group and the second piston group abut against each other. The damping component includes: The damping cylinder (3-5) has one end fixedly connected to the closed end of the cylinder (3-3), and the other end is provided with a damping end cap (3-6) fixedly connected to it. The damping piston (7) is located inside the damping cylinder (3-5), and is located at the end of the piston rod in the second piston group inside the damping cylinder (3-5); The damping piston (7) includes: The coil support (7-5) has an annular groove on its outer wall and a multi-stage flow channel inside; The coil winding (7-3) is fitted into the annular groove of the coil support (7-5); A magnetic sleeve (7-2) is fitted onto the outer wall of the coil support (7-5); The end caps located on both sides of the coil support (7-5) are provided with flow channel holes that communicate with the multi-stage flow channels; The multi-stage flow channel includes a first magnetic ring (7-6), a second magnetic ring (7-8), and a magnetic sheet (7-7) located between the first magnetic ring (7-6) and the second magnetic ring (7-8). The end cap plate includes a damping piston left end cap (7-1) and a damping piston right end cap (7-4). The damping piston left end cap (7-1) and the second magnetic ring (7-8), the damping piston right end cap (7-4) and the first magnetic ring (7-6), and the spacing between the magnetic sheet (7-7) and the first magnetic ring (7-6) and the second magnetic ring (7-8) constitute a magnetorheological fluid flow channel, in which the magnetorheological fluid can flow. The end cover plate has a cone on the side facing the coil support (7-5) with an arc transition; the magnetic sheet (7-7) has external chamfers at both ends; the magnetic ring (7-8) has an external chamfer on the side facing the end cover plate and an internal chamfer on the side facing the magnetic sheet (7-7); The arc-shaped transition has the same radius as the outer chamfer of the magnetic ring (7-8), and the distance between them is equal to the width of the magnetorheological fluid gap; The outer chamfer of the magnetic sheet (7-7) has the same radius as the inner chamfer of the magnetic ring (7-8), and the distance between them is equal to the width of the magnetorheological fluid gap.

2. The six-degree-of-freedom flexible spine for a legged robot according to claim 1, characterized in that, The hydraulic damping actuator (3) has ball heads at both ends that are hinged to the first ball hinge base (4-1) and the second ball hinge base (4-2).

3. A variable stiffness damping control method for a six-degree-of-freedom flexible spine of a legged robot as described in any one of claims 1-2, characterized in that, The legged robot's body includes a front trunk (1-1), a rear trunk (1-2), and a six-degree-of-freedom flexible spine for connecting the two; the coil support (7-5), the multi-stage flow channel provided in the coil support (7-5), and the end caps provided on both sides of the coil support (7-5) constitute magnetorheological fluid flow channels. The variable stiffness damping control method includes the following steps: When the impact force on the legged robot is applied to the piston rod through the body, the piston rod drives the piston and the damping piston (7) to reciprocate inside the cylinder (3-3) and the damping cylinder (3-5), respectively. First, by adjusting the hydraulic pressure difference between the two ends of the piston in the cylinder (3-3), the displacement target of the piston in the cylinder (3-3) is controlled, thereby realizing the adjustment of the overall stiffness of the hydraulic damping actuator (3); Secondly, when the damping piston (7) moves, the magnetorheological fluid inside the damping cylinder (3-5) flows from one end to the other through the damping piston (7). When there is a magnetic field inside the magnetorheological fluid channel, the magnetorheological fluid inside the channel changes from liquid to solid-like state, which hinders the flow of the magnetorheological fluid from one end of the damping piston (7) to the other end, thereby hindering the movement of the damping piston (7) and realizing the adjustment of the overall damping of the hydraulic damping actuator (3).

4. A method for adjusting the flexible spinal motion posture of a legged robot, characterized in that, It utilizes the variable stiffness damping control method for a six-degree-of-freedom flexible spine of a legged robot as described in claim 3. The adjustment method includes the following steps: The six hydraulic damping actuators (3) are numbered sequentially as hydraulic damping actuators ①②③④⑤⑥. Hydraulic damping actuators ① and ② are located on the upper part of the machine body and are arranged in a counterclockwise order. By adjusting the movement of the six hydraulic damping actuators (3) of the flexible spine, the front support frame (2) and the rear support frame (5) have six degrees of freedom: relative torsion, swing, and translation. Simultaneously adjust the piston rod extension / retraction of hydraulic damping actuators ①②, ③④, and ⑤⑥ to achieve relative up-down and left-right translation or swing of the front support frame (2) and the rear support frame (5), thereby driving the body to translate or swing, and realizing the legged robot's steering and obstacle avoidance functions; By simultaneously adjusting the piston rod extension / retraction of hydraulic damping actuators ①③⑤ and ②④⑥, the front support frame (2) and the rear support frame (5) can be rotated relative to each other along the axial direction, thereby driving the machine body to rotate and improving the flexibility of the machine body. By simultaneously adjusting the piston rod extension / retraction of hydraulic damping actuators ①②③④⑤⑥, the front support frame (2) and the rear support frame (5) can be moved back and forth relative to each other, thereby causing the robot body to extend or retract, enabling the robot to enter narrow sections or facilitate transportation.

5. The method for adjusting the flexible spinal motion posture of a legged robot according to claim 4, characterized in that, When the legged robot jumps, the two hydraulic damping actuators ①② at the top of the flexible spine retract, and the four hydraulic damping actuators ③④⑤⑥ at the bottom extend. By changing the angle between the front support frame (2) and the rear support frame (5), the swing angle between the front and rear legs of the legged robot is increased, thereby improving the gait length of the legged robot. At the moment of landing after the legged robot jumps, the two hydraulic damping actuators ①② at the top of the flexible spine extend, and the four hydraulic damping actuators ③④⑤⑥ at the bottom retract, thereby reducing the swing angle between the front and rear legs of the legged robot and accumulating power for the next jump. This allows the flexible spine to assist the legged robot in completing the jumping motion.

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