Bionic robot based on linear actuator and lower limb motion space optimization method

Abstract

The application provides a kind of bionic robot based on linear actuator and lower limb movement space optimization method, it is related to robot technical field, for solving the technical problem that bionic robot movement space is insufficient in relevant technology, movement fluidity is poor, the thigh assembly connecting rod mechanism of the bionic robot is connected with the transmission of thigh assembly, thigh linear actuator drives thigh assembly connecting rod mechanism to drive thigh assembly to rotate forward or backward;The connecting rod mechanism of calf assembly is connected with the transmission of leg assembly, calf linear actuator drives calf assembly connecting rod mechanism to drive calf assembly to rotate forward or backward;Ankle joint connecting rod mechanism is connected with the transmission of foot, ankle joint linear actuator drives ankle joint connecting rod mechanism to drive double foot to rotate forward, backward, left or right.By combining linear actuator with connecting rod mechanism, the mechanical properties of lower limbs are improved and the nonlinearity is reduced without affecting the movement space, so that the robot can achieve better performance in a larger movement space.

Description

Technical Field

[0001] This application relates to the field of robotics technology, and in particular to a biomimetic robot based on a linear actuator and a method for optimizing lower limb motion space. Background Technology

[0002] In related technologies, the joints of the bipedal motion system of humanoid robots use rotary actuators combined with mechanical transmission mechanisms to convert rotational motion into linear or other complex motion forms. However, the motion of biological muscles is mainly linear contraction, and rotary actuators are difficult to directly simulate this characteristic, resulting in poor smoothness and naturalness of robot motion. Therefore, the method of using rotary actuators combined with mechanical transmission mechanisms has certain limitations in terms of power density, structural complexity, positioning accuracy, and biomimetic effect. Summary of the Invention

[0003] In view of the above problems, this application provides a method for optimizing the motion space of a bionic robot and its lower limbs based on a linear actuator, so as to solve the problems of insufficient motion space and poor motion smoothness of bionic robots in related technologies.

[0004] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0005] This application provides a bionic robot based on a linear actuator, comprising: a thigh component linkage mechanism, a thigh linear actuator, a lower leg component linkage mechanism, a lower leg linear actuator, an ankle joint linkage mechanism, and an ankle joint linear actuator; the thigh component linkage mechanism is drivenly connected to the thigh component, the drive rod of the thigh linear actuator is drivenly connected to the thigh component linkage mechanism, the thigh linear actuator drives the thigh component linkage mechanism to move, and the thigh component linkage mechanism drives the thigh component to rotate forward or backward; the lower leg component is rotatably connected to the knee joint of the thigh component. The lower leg assembly includes a linkage mechanism that is connected to the lower leg assembly, a drive rod of a lower leg linear actuator that is connected to the linkage mechanism, and a lower leg linear actuator that drives the linkage mechanism to rotate the lower leg assembly forward or backward. The lower leg assembly has two feet rotatably connected to its ankle joint. An ankle joint linkage mechanism is connected to the two feet, and a drive rod of an ankle joint linear actuator is connected to the linkage mechanism. The ankle joint linear actuator that drives the linkage mechanism to rotate the two feet forward, backward, left, or right.

[0006] In one embodiment of this application, the thigh assembly linkage mechanism includes: a first link, a second link, a first thigh pivot, a second thigh pivot, a third thigh pivot, a fourth thigh pivot, and a fifth thigh pivot; the thigh assembly is rotatably connected to the hip joint assembly via the first thigh pivot; one end of the first link is rotatably connected to the hip joint assembly via the second thigh pivot, one end of the thigh linear actuator has a first drive rod, and the other end of the first link is rotatably connected to the first drive rod via the third thigh pivot; one end of the second link is rotatably connected to the first drive rod via the third thigh pivot, and the other end of the second link is rotatably connected to the thigh assembly via the fourth thigh pivot; the other end of the thigh linear actuator is rotatably connected to the thigh assembly via the fifth thigh pivot; wherein the central axes of the first thigh pivot, the second thigh pivot, the third thigh pivot, the fourth thigh pivot, and the fifth thigh pivot are all parallel to the left-right direction of the bionic robot.

[0007] In one embodiment of this application, a first force sensor and a first distance sensor are further provided at one end of the thigh linear actuator.

[0008] In one embodiment of this application, the lower leg assembly linkage mechanism includes: a third link, a fourth link, a first lower leg pivot, a second lower leg pivot, a third lower leg pivot, a fourth lower leg pivot, and a fifth lower leg pivot; one end of the lower leg linear actuator has a second drive rod, and the other end of the lower leg linear actuator is rotatably connected to the thigh assembly via the first lower leg pivot; one end of the third link is rotatably connected to the second drive rod via the second lower leg pivot, and the other end of the third link is rotatably connected to the thigh assembly via the fifth lower leg pivot; one end of the fourth link is rotatably connected to the second drive rod via the second lower leg pivot, and the other end of the fourth link is rotatably connected to the lower leg assembly via the third lower leg pivot; the lower leg assembly is also rotatably connected to the thigh assembly via the fourth lower leg pivot; wherein the central axes of the first lower leg pivot, the second lower leg pivot, the third lower leg pivot, the fourth lower leg pivot, and the fifth lower leg pivot are all parallel to the left-right direction of the bionic robot.

[0009] In one embodiment of this application, a second force sensor and a second distance sensor are further provided at one end of the lower leg linear actuator.

[0010] In one embodiment of this application, the ankle joint linear actuator includes a first ankle joint linear actuator and a second ankle joint linear actuator, which are respectively mounted on the left and right sides of the lower leg assembly. When the first ankle joint linear actuator and the second ankle joint linear actuator extend and retract simultaneously, the ankle joint linkage mechanism drives the two feet to rotate forward or backward. When the first ankle joint linear actuator extends while the second ankle joint linear actuator retracts, or when the first ankle joint linear actuator retracts while the second ankle joint linear actuator extends, the ankle joint linkage mechanism drives the two feet to swing to the left or right.

[0011] In one embodiment of this application, the ankle joint linkage mechanism includes: a first ankle pivot, a second ankle pivot, and a third ankle pivot. One end of the first ankle joint linear actuator has a third drive rod, which is rotatably connected to the ankle joints of both feet via the second ankle pivot. The other end of the first ankle joint linear actuator is rotatably connected to the lower leg assembly via the third ankle pivot. The lower leg assembly is also rotatably connected to the ankle joints of both feet via the first ankle pivot.

[0012] In one embodiment of this application, the other end of the first ankle joint linear actuator is connected to the lower leg assembly at a third ankle pivot via a ball joint, and one end of the first ankle joint linear actuator is connected to the ankle joints of both feet at a second ankle pivot via a ball joint.

[0013] In one embodiment of this application, a third force sensor and a third distance sensor are provided at one end of both the first ankle joint linear actuator and the second ankle joint linear actuator.

[0014] This application also provides a method for optimizing lower limb movement space, applied to the bionic robot described above, which includes:

[0015] Establish a mathematical model of the geometric relationship between the thigh component, the calf component, and both feet;

[0016] Obtain the geometric parameter variable j. When the geometric parameter variable j is 1, determine whether the geometric parameter variable j can increase the workspace. If yes, assign a positive weight value to the geometric parameter variable j; otherwise, assign a negative weight value to the geometric parameter variable j.

[0017] When the geometric parameter variable j is 2, determine whether interference or singularity occurs; if yes, assign a negative weight value to the geometric parameter variable j; if no, assign a positive weight value to the geometric parameter variable j.

[0018] When the geometric parameter variable j is 3, determine whether the loads of the thigh component linkage mechanism, the lower leg component linkage mechanism, and the ankle joint linkage mechanism are greater than the first preset threshold; if yes, assign a negative weight value to the geometric parameter variable j; if no, assign a positive weight value to the geometric parameter variable j.

[0019] When the geometric parameter variable j is 4, the parameter correspondence is derived, and the corresponding determination coefficient R2 is calculated. It is then determined whether R2 is less than the second preset threshold. If so, a negative weight value is assigned to the geometric parameter variable j; otherwise, a positive weight value is assigned to the geometric parameter variable j.

[0020] The bionic robot based on a linear actuator provided in this application has the following technical effects:

[0021] Using linear actuators to provide linear motion simplifies the mechanical design of the robot's leg joints, eliminating the need for additional limiting devices and reducing structural complexity. The motion pattern of linear actuators is similar to the linear contraction of biological muscles, which can more naturally simulate the motion mechanism of biological muscles, giving it certain advantages in gait control and motion coordination.

[0022] By combining linear actuators with linkage mechanisms, the range of motion for the thigh assembly, lower leg assembly, and feet is effectively expanded. This allows the thigh assembly to achieve pitch and oscillation within a range of -50° to 120°, the lower leg assembly to achieve oscillation within a range of 0° to 127°, and the feet to achieve pitch and oscillation within a range of -62° to 11° and roll and oscillate within a range of ±25°. Simultaneously, the extension and oscillation of the linear actuators maintain a linear relationship, optimizing the control efficiency and smoothness of motion. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 Schematic diagram of the lower limb structure of the bionic robot provided in the embodiments of this application Figure 1 ;

[0025] Figure 2 Schematic diagram of the lower limb structure of the bionic robot provided in the embodiments of this application Figure 2 ;

[0026] Figure 3 This is a schematic diagram of the structure of the thigh assembly of the bionic robot provided in the embodiments of this application;

[0027] Figure 4 The lower limb flexion state of the bionic robot provided in the embodiments of this application. Figure 1 ;

[0028] Figure 5 The lower limb flexion state of the bionic robot provided in the embodiments of this application Figure 2 ;

[0029] Figure 6 Schematic diagram of the lower limb structure of the bionic robot provided in the embodiments of this application Figure 3 ;

[0030] Figure 7 Schematic diagram of the lower limb structure of the bionic robot provided in the embodiments of this application Figure 4 ;

[0031] Figure 8 The lower limb flexion state of the bionic robot provided in the embodiments of this application Figure 3 ;

[0032] Figure 9 This is a schematic diagram of the structure of the lower leg assembly of the bionic robot provided in an embodiment of this application;

[0033] Figure 10 A schematic diagram of the structure of the hip joint assembly of the bionic robot provided in an embodiment of this application;

[0034] Figure 11 Mathematical model of the geometric relationship of the thigh of the bionic robot provided in the embodiments of this application;

[0035] Figure 12 Mathematical model of the lower leg geometry of the bionic robot provided in this application embodiment;

[0036] Figure 13 Mathematical model of bipedal geometric relationship of the bionic robot provided in the embodiments of this application;

[0037] Figure 14 A flowchart illustrating the optimization of the lower limb movement space of the bionic robot provided in this application embodiment.

[0038] Figure label:

[0039] 100-Hip joint fixation plate;

[0040] 101 - First lower limb rotary motor; 102 - Second lower limb rotary motor; 103 - First lower limb lateral swing motor; 104 - Second lower limb lateral swing motor;

[0041] 301 - First linear actuator; 302 - Second linear actuator; 303 - Third linear actuator; 304 - Fourth linear actuator;

[0042] 3011 - First drive lever; 3031 - Second drive lever;

[0043] 401 - Right leg base; 402 - Left leg base;

[0044] 501 - First ankle joint linear actuator; 502 - Second ankle joint linear actuator; 503 - Third ankle joint linear actuator; 504 - Fourth ankle joint linear actuator;

[0045] 5011 - Third drive lever; 5021 - Fourth drive lever;

[0046] 601 - Right leg side plate; 602 - Left leg side plate;

[0047] 701 - First Link; 702 - Second Link; 703 - Third Link; 704 - Fourth Link;

[0048] 801 - Right leg fixation component; 802 - Left leg fixation component;

[0049] 901-right foot; 902-left foot;

[0050] A - First thigh pivot; B - Second thigh pivot; C - Third thigh pivot; D - Fourth thigh pivot; F - Fifth thigh pivot; G - First calf pivot; M - Second calf pivot; L - Third calf pivot; K - Fourth calf pivot; H - Fifth calf pivot; S - First ankle pivot; P - Second ankle pivot; N - Third ankle pivot. Detailed Implementation

[0051] To make the above-mentioned objectives, features, and advantages of the embodiments of this application more apparent and understandable, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0052] In the embodiments of this application, the left-right and front-back directions refer to the left-right and front-back directions of the bionic robot.

[0053] refer to Figure 1 and Figure 10This application provides a bionic robot based on a linear actuator. The bionic robot includes a hip joint assembly, which includes a hip joint fixation plate 100. The front of the hip joint fixation plate 100 is provided with a first lower limb rotary motor 101 and a second lower limb rotary motor 102. The first lower limb rotary motor 101 is used to drive the right leg to rotate forward or backward, and the second lower limb rotary motor 102 is used to drive the left leg to rotate forward or backward. The back of the hip joint fixation plate 100 is provided with a first lower limb lateral swing motor 103 and a second lower limb lateral swing motor 104. The first lower limb lateral swing motor 103 is used to drive the right leg to swing to the left or right, and the second lower limb lateral swing motor 104 is used to drive the left leg to swing to the left or right.

[0054] The bionic robot also includes: a right leg fixation component 801, a left leg fixation component 802, and a thigh assembly. Both the right leg fixation component 801 and the left leg fixation component 802 are fixedly connected to the hip joint fixation plate 100. The thigh assembly includes a right leg base 401 and a left leg base 402. The right leg base 401 is rotatably connected to the right leg fixation component 801, and the left leg base 402 is rotatably connected to the left leg fixation component 802.

[0055] The front and rear ends of the right leg base 401 are provided with mounting cavities, and the front and rear ends of the left leg base 402 are also provided with mounting cavities.

[0056] The bionic robot also includes a thigh linear actuator, which comprises a first linear actuator 301 and a second linear actuator 302. The first linear actuator 301 is disposed in the mounting cavity at the rear end of the right leg base 401, and the second linear actuator 302 is disposed in the mounting cavity at the rear end of the left leg base 402. The first linear actuator 301 is used to drive the right leg base 401 to rotate forward or backward, and the second linear actuator 302 is used to drive the left leg base 402 to rotate forward or backward.

[0057] The rotation principle of the right leg base 401 and the left leg base 402 is the same. The rotation principle of the right leg base 401 is described below.

[0058] refer to Figures 2 to 5The bionic robot also includes: a first link 701, a second link 702, a first thigh pivot A, a second thigh pivot B, a third thigh pivot C, a fourth thigh pivot D, and a fifth thigh pivot F. The right leg base 401 is rotatably connected to the right leg fixing member 801 via the first thigh pivot A. One end of the first link 701 is rotatably connected to the right leg fixing member 801 via the second thigh pivot B. The other end of the first link 701 is rotatably connected to the first drive rod 3011 of the first linear actuator 301 via the third thigh pivot C. One end of the second link 702 is also rotatably connected to the first drive rod 3011 of the first linear actuator 301 via the third thigh pivot C. The other end of the second link 702 is rotatably connected to the right leg base 401 via the fourth thigh pivot D.

[0059] One end of the first linear actuator 301 has a first drive rod 3011, and the other end of the first linear actuator 301 is rotatably connected to the right leg base 401 through the fifth thigh pivot F.

[0060] Among them, the central axes of the first thigh pivot A, the second thigh pivot B, the third thigh pivot C, the fourth thigh pivot D, and the fifth thigh pivot F are all parallel to the left and right directions of the bionic robot.

[0061] When the right leg base 401 rotates forward or backward, the positions of the first thigh pivot A and the second thigh pivot B remain fixed, while the positions of the third thigh pivot C, the fourth thigh pivot D, and the fifth thigh pivot F will move with the right leg base 401.

[0062] like Figure 4 As shown, when the first drive rod 3011 of the first linear actuator 301 extends, the right leg base 401 rotates forward; as Figure 5 As shown, when the first drive rod 3011 of the first linear actuator 301 retracts, the right leg base 401 rotates backward.

[0063] The first drive rod 3011, the first connecting rod 701, the second connecting rod 702, the first thigh pivot A, the second thigh pivot B, the third thigh pivot C, the fourth thigh pivot D, and the fifth thigh pivot F together constitute a thigh assembly linkage mechanism for driving the right leg base 401 to rotate forward or backward. The thigh assembly linkage mechanism is drive-connected to the thigh assembly, and the drive rod of the thigh linear actuator is drive-connected to the thigh assembly linkage mechanism. The thigh linear actuator drives the thigh assembly linkage mechanism to move, and the thigh assembly linkage mechanism drives the thigh assembly to rotate forward or backward.

[0064] By combining the first linear actuator 301 with the thigh assembly linkage mechanism, the spatial range of the thigh assembly's movement is effectively expanded, enabling the thigh assembly to achieve pitching and swaying within the range of -50° to 120°. Simultaneously, the extension and retraction of the first drive rod 3011 of the first linear actuator 301 maintains a linear relationship with the swaying amount of the thigh assembly, optimizing the control efficiency and smoothness of the first linear actuator 301.

[0065] In this embodiment, a first force sensor and a first distance sensor are also provided at one end of the thigh linear actuator; wherein, a first force sensor and a first distance sensor are also provided at one end of the first linear actuator 301, enabling the robot to monitor the motion state and changes in the external environment in real time, providing high-precision feedback information for subsequent mechanical control algorithms (such as reinforcement learning algorithms) based on sensor data; providing a foundation for the robot to achieve more complex motion control, and helping to improve the ability of force control and adaptive control.

[0066] It should be noted that the design of the thigh linear actuator simplifies the mechanical transmission structure of the thigh assembly, thereby simplifying the installation and arrangement of the force sensor and distance sensor.

[0067] refer to Figure 6 , Figure 7 and Figure 8 The bionic robot also includes: a lower leg linear actuator, which includes: a third linear actuator 303 and a fourth linear actuator 304. The third linear actuator 303 is located in the mounting cavity at the front end of the right leg base 401, and the fourth linear actuator 304 is located in the mounting cavity at the front end of the left leg base 402.

[0068] The bionic robot also includes: a lower leg assembly, with the knee joint of the thigh assembly rotatably connected to the lower leg assembly, the lower leg assembly including a right leg side plate 601 and a left leg side plate 602, a third linear actuator 303 for driving the right leg side plate 601 to rotate forward or backward, and a fourth linear actuator 304 for driving the left leg side plate 602 to rotate forward or backward.

[0069] The rotation principle of the right leg side plate 601 and the left leg side plate 602 is the same. The rotation principle of the right leg side plate 601 is described below.

[0070] Continue to refer to Figures 2 to 5The bionic robot also includes: a third link 703, a fourth link 704, a first lower leg pivot G, a second lower leg pivot M, a third lower leg pivot L, a fourth lower leg pivot K, and a fifth lower leg pivot H; one end of the third linear actuator 303 has a second drive rod 3031, and the other end of the third linear actuator 303 is rotatably connected to the right leg base 401 via the first lower leg pivot G; one end of the third link 703 is rotatably connected to the second drive rod 3031 of the third linear actuator 303 via the second lower leg pivot M, and the other end of the third link 703 is rotatably connected to the right leg base 401 via the fifth lower leg pivot H; one end of the fourth link 704 is also rotatably connected to the second drive rod 3031 of the third linear actuator 303 via the second lower leg pivot M, and the other end of the fourth link 704 is rotatably connected to the right leg side plate 601 via the third lower leg pivot L; the right leg side plate 601 is also rotatably connected to the right leg base 401 via the fourth lower leg pivot K.

[0071] Among them, the central axes of the first lower leg pivot G, the second lower leg pivot M, the third lower leg pivot L, the fourth lower leg pivot K, and the fifth lower leg pivot H are all parallel to the left and right directions of the bionic robot.

[0072] When the right leg side plate 601 rotates forward or backward, the positions of the first lower leg pivot G, the second lower leg pivot M, the third lower leg pivot L, the fourth lower leg pivot K, and the fifth lower leg pivot H will move with the right leg side plate 601.

[0073] like Figure 4 and Figure 5 As shown, when the second drive rod 3031 of the third linear actuator 303 extends, the right leg side plate 601 rotates backward; as Figure 8 As shown, when the second drive rod 3031 of the third linear actuator 303 retracts, the right leg side plate 601 rotates forward.

[0074] The second drive rod 3031, the third connecting rod 703, the fourth connecting rod 704, the first lower leg pivot G, the second lower leg pivot M, the third lower leg pivot L, the fourth lower leg pivot K, and the fifth lower leg pivot H together form a lower leg assembly linkage mechanism for driving the right leg side plate 601 to rotate forward or backward. The lower leg assembly linkage mechanism is connected to the lower leg assembly in a transmission manner, and the drive rod of the lower leg linear actuator is connected to the lower leg assembly linkage mechanism in a transmission manner. The lower leg linear actuator drives the lower leg assembly linkage mechanism to drive the lower leg assembly to rotate forward or backward.

[0075] It should be noted that, for the above-mentioned lower leg assembly linkage mechanism, when the right leg side plate 601 rotates forward or backward relative to the right leg base 401, the positions of the fourth lower leg pivot K and the fifth lower leg pivot H remain fixed, while the positions of the first lower leg pivot G, the second lower leg pivot M and the third lower leg pivot L will move with the right leg side plate 601.

[0076] By combining the lower leg linear actuator with the lower leg assembly linkage mechanism, the spatial range of the lower leg assembly's movement is effectively expanded, enabling the lower leg assembly to swing from 0° to 127°. At the same time, the extension and retraction of the second drive rod 3031 of the third linear actuator 303 maintains a linear relationship with the swing of the lower leg, optimizing the control efficiency and smoothness of the movement of the third linear actuator 303.

[0077] In this embodiment, a second force sensor and a second distance sensor are also provided at one end of the lower leg linear actuator; specifically, a second force sensor and a second distance sensor are also provided at one end of the third linear actuator 303, enabling the robot to monitor its motion state and changes in the external environment in real time, providing high-precision feedback information for subsequent mechanical control algorithms (such as reinforcement learning algorithms) based on sensor data; providing a foundation for the robot to achieve more complex motion control, and helping to improve its force control and adaptive control capabilities.

[0078] It should be noted that setting a second force sensor and a second distance sensor on the third linear actuator 303 simplifies the installation and arrangement of the force sensor and distance sensor; and further simplifies the mechanical transmission structure of the lower leg assembly.

[0079] refer to Figure 1 , Figure 6 , Figure 7 and Figure 8 The bionic robot also includes: an ankle joint linear actuator, which includes a first ankle joint linear actuator 501 and a second ankle joint linear actuator 502, and the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 are respectively installed on the left and right sides of the lower leg assembly.

[0080] The ankle joint linear actuator also includes a third ankle joint linear actuator 503 and a fourth ankle joint linear actuator 504. The first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 are respectively installed on the left and right sides of the right leg side plate 601, and the third ankle joint linear actuator 503 and the fourth ankle joint linear actuator 504 are respectively installed on the left and right sides of the left leg side plate 602.

[0081] The bionic robot also includes: bipedalism, with the ankle joint of the lower leg assembly rotatably connected to the bipedalism, the ankle joint linkage mechanism being transmitted to the bipedalism, the drive rod of the ankle joint linear actuator being transmitted to the ankle joint linkage mechanism, and the ankle joint linear actuator driving the ankle joint linkage mechanism to rotate the bipedalism forward, backward, left, or right.

[0082] The two feet include a right foot 901 and a left foot 902. The first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 are used to drive the right foot 901 to rotate forward or backward, and the third ankle joint linear actuator 503 and the fourth ankle joint linear actuator 504 are used to drive the left foot 902 to rotate forward or backward.

[0083] Specifically, when the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 extend and retract simultaneously, the ankle joint linkage mechanism drives the right foot 901 to rotate forward or backward; when the first ankle joint linear actuator 501 extends while the second ankle joint linear actuator 502 retracts, or when the first ankle joint linear actuator 501 retracts while the second ankle joint linear actuator 502 extends, the ankle joint linkage mechanism drives the right foot 901 to swing to the left or right.

[0084] The rotation principle of the right foot 901 and the left foot 902 is the same. The rotation principle of the right foot 901 is described below.

[0085] Continue to refer to Figures 2 to 5 ,as well as Figure 9 The bionic robot also includes: a first ankle pivot S, a second ankle pivot P, and a third ankle pivot N. One end of the first ankle joint linear actuator 501 has a third drive rod 5011, which is rotatably connected to the ankle joint of the right foot 901 via the second ankle pivot P. The other end of the first ankle joint linear actuator 501 is rotatably connected to the right leg side plate 601 via the third ankle pivot N. The right leg side plate 601 is also rotatably connected to the ankle joint of the right foot 901 via the first ankle pivot S.

[0086] The other end of the first ankle joint linear actuator 501 is connected to the right leg side plate 601 at the third ankle pivot N via two sets of ball joints, and one end of the first ankle joint linear actuator 501 is connected to the right foot 901 at the second ankle pivot P via two sets of ball joints.

[0087] Similarly, one end of the second ankle joint linear actuator 502 has a fourth drive rod 5021, which is rotatably connected to the ankle joint of the right foot 901 via the second ankle pivot P, and the other end of the second ankle joint linear actuator 502 is rotatably connected to the right leg side plate 601 via the third ankle pivot N.

[0088] Among them, the central axes of the first ankle pivot S, the second ankle pivot P, and the third ankle pivot N are all parallel to the left and right directions of the bionic robot.

[0089] When the right foot 901 rotates forward or backward, the positions of the first ankle pivot S, the second ankle pivot P, and the third ankle pivot N will move with the right foot 901.

[0090] When the third drive rod 5011 of the first ankle joint linear actuator 501 and the fourth drive rod 5021 of the second ankle joint linear actuator 502 extend simultaneously, the right foot 901 rotates forward; when the third drive rod 5011 of the first ankle joint linear actuator 501 and the fourth drive rod 5021 of the second ankle joint linear actuator 502 retract simultaneously, the right foot 901 rotates backward.

[0091] The third drive rod 5011, the fourth drive rod 5021, the first ankle pivot S, the second ankle pivot P, and the third ankle pivot N together form an ankle joint linkage mechanism for driving the right foot 901 to rotate forward or backward.

[0092] It should be noted that when the third drive rod 5011 of the first ankle joint linear actuator 501 extends, the fourth drive rod 5021 of the second ankle joint linear actuator 502 can retract; or when the third drive rod 5011 of the first ankle joint linear actuator 501 retracts, the fourth drive rod 5021 of the second ankle joint linear actuator 502 can extend; at this time, the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 can drive the right foot 901 to swing to the left or to the right.

[0093] The first ankle pivot S can be a universal joint, enabling the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 to drive the right foot 901 to rotate forward or backward around the first ankle pivot S; the line connecting the first ankle pivot S and the second ankle pivot P is SP, enabling the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 to drive the right foot 901 to swing left or right around SP.

[0094] By combining the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 with the ankle joint linkage mechanism, the spatial range of movement of the right foot 901 is effectively amplified, enabling the right foot 901 to achieve pitch swing of -62° to 11° and roll swing of ±25°.

[0095] In this embodiment, the displacement output end of the first ankle joint linear actuator 501 is also equipped with a third force sensor and a third distance sensor, and the displacement output end of the second ankle joint linear actuator 502 is also equipped with a third force sensor and a third distance sensor. This enables the robot to monitor its motion state and changes in the external environment in real time, providing high-precision feedback information for subsequent mechanical control algorithms (such as reinforcement learning algorithms) based on sensor data. This provides a foundation for the robot to achieve more complex motion control and helps improve its force control and adaptive control capabilities.

[0096] It should be noted that the design of the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 simplifies the mechanical transmission structure of the thigh assembly, thereby simplifying the installation and arrangement of the force sensor and distance sensor.

[0097] In summary, the bionic robot based on linear actuators provided in this application uses linear actuators to provide linear motion, which simplifies the mechanical design of the robot's leg joints, eliminates the need for additional limiting devices, and reduces structural complexity. The motion pattern of the linear actuator is similar to the linear contraction mode of biological muscles, which can more naturally simulate the motion mechanism of biological muscles, giving it certain advantages in gait control and motion coordination.

[0098] By combining linear actuators with linkage mechanisms, the range of motion for the thigh assembly, lower leg assembly, and feet is effectively expanded. This allows the thigh assembly to achieve pitch and oscillation within a range of -50° to 120°, the lower leg assembly to achieve oscillation within a range of 0° to 127°, and the feet to achieve pitch and oscillation within a range of -62° to 11° and roll and oscillate within a range of ±25°. Simultaneously, the extension and oscillation of the linear actuators maintain a linear relationship, optimizing the control efficiency and smoothness of motion.

[0099] Furthermore, linear actuators have higher power density, enabling them to provide greater thrust and energy conversion efficiency within a limited space.

[0100] This application also provides a method for optimizing lower limb movement space, including:

[0101] Step S1: Establish a mathematical model of the geometric relationship between the thigh component, the calf component, and the feet.

[0102] like Figure 11 As shown, points ABCDF together form the linkage mechanism of the thigh component. E is located on the extension line of AD, and DE is perpendicular to EF, thus obtaining the position of point F.

[0103] The variables in the thigh assembly linkage mechanism are: AB length, B point coordinate, BC length, CD length, AD length, DE length, and EF length. Since the first drive rod 3011 can extend or shorten, the CF length is limited to between CF1 and CF2. α represents the pitch angle of the thigh assembly, and the workspace of the thigh assembly can be obtained. Based on this, a corresponding mathematical model of the geometric relationship of the thigh assembly is established.

[0104] like Figure 12As shown, the five points GMLKH together constitute the linkage mechanism of the lower leg assembly. J is located on the extension line of GH, and HJ is perpendicular to JK, thus obtaining the position of point K. Since the second drive rod 3031 can extend or shorten, the length of GM is limited between GM1 and GM2. β represents the pitch angle of the lower leg assembly, and thus the working space of the lower leg assembly can be obtained. Based on this, the corresponding geometric relationship mathematical model of the lower leg assembly is established.

[0105] like Figure 13 As shown, N1, N, and N2 are fixed points on the right leg side plate 601, and P1, P, P2, Q, S, U0, and U are fixed points on the right foot 901. N1P1 and N2P2 correspond to the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502. The lengths of N1P1 and N2P2 can be changed. Point S corresponds to the universal joint axis. Angles Q0SQ and T0ST correspond to the pitch angle and roll angle of the right foot 901, respectively. Thus, the working space of the right foot 901 can be obtained, and a corresponding bipedal geometric mathematical model can be established based on this.

[0106] In addition to length limitations, N1P1 and N2P2 also require angle limitations, namely, γ1, γ2, γ3, and γ4 cannot exceed the maximum swing angle of the ball joint. The maximum swing angle needs to be calculated based on the mechanical motion characteristics of the ball joint.

[0107] After establishing the geometric relationship mathematical model, this application optimizes each variable in the geometric parameter variable j individually. The optimization measures include: determining the optimization range of the i-th variable in the geometric parameter variable j, and then increasing or decreasing the i-th variable by assigning weights. Furthermore, for the i-th variable in the geometric parameter variable j, optimization is performed specifically according to the cases where j equals 1, 2, 3, and 4, that is, steps S2 and S3 are executed sequentially for the i-th variable until all parameter variables in the geometric parameter variable j have been optimized.

[0108] Step S2: Obtain the geometric parameter variable j.

[0109] Among them, such as Figure 11 As shown, the geometric parameter variable j includes: the length of AB, the coordinates of point B, the length of BC, the length of CD, the length of AD, the length of DE, the length of EF, and the length of CF in the thigh component linkage mechanism, and the length of CF is limited to between CF1 and CF2.

[0110] like Figure 12As shown, the geometric parameter variable j includes: the lengths of GM, LM, HM, GH, LK, JK, and L point coordinates in the lower leg assembly linkage mechanism. The length of GM is limited to between GM1 and GM2, the length of HM is limited to between HM1 and HM2, and the length of LM is limited to between LM1 and LM2.

[0111] like Figure 13 As shown, the geometric parameter variable j includes: the coordinates of point N in the ankle joint linkage mechanism (the coordinates of point N are limited to N1 and N2), the coordinates of point P (the coordinates of point P are limited to P1 and P2), the lengths of N1P1 and N2P2, the angle Q0SQ, and the angle T0ST.

[0112] Step S3: Determine whether the geometric parameter variable j can increase the workspace, whether interference or singularities are generated, whether the load of the mechanism is greater than the first preset threshold, or whether the nonlinearity of the mechanism exceeds the corresponding threshold, so as to optimize the geometric parameter variable j and achieve the purpose of optimizing the lower limb movement space.

[0113] like Figure 14 Step S3 includes:

[0114] Step S31: When the geometric parameter variable j is 1, determine whether the geometric parameter variable j can increase the workspace. If yes, assign a positive weight value to the geometric parameter variable j. If not, assign a negative weight value to the geometric parameter variable j.

[0115] The process of determining whether geometric parameter variable j can increase workspace includes: inputting geometric parameter variable j into a geometric relationship mathematical model, obtaining the maximum space occupied during lower limb movement, and thus determining whether geometric parameter variable j can increase workspace.

[0116] When the geometric parameter variable j is 1, determining whether the geometric parameter variable j can increase the workspace also includes: determining whether the geometric parameter variable j can increase the workspace in one direction or in both directions. If it is in one direction (either positive or negative), a smaller first weight value is assigned to the geometric parameter variable j; if it is in both directions (both positive and negative), a larger second weight value is assigned to the geometric parameter variable j. The first weight value is less than the second weight value, and both are positive numbers.

[0117] In other words, when the geometric parameter variable j is 1, it means that the influence of the geometric parameter variable j on the workspace needs to be determined.

[0118] After the case where the geometric parameter variable j is 1 is completed, the case where the geometric parameter variable j is 2 will be executed.

[0119] Step S32: When the geometric parameter variable j is 2, determine whether interference or singularity occurs; if yes, assign a negative weight value to the geometric parameter variable j. If not, assign a positive weight value to the geometric parameter variable j.

[0120] The process of determining whether interference or singularity occurs includes: inputting the geometric parameter variable j into the geometric relationship mathematical model, obtaining the coordinates of each position in the geometric relationship mathematical model, and then determining whether interference or singularity occurs.

[0121] In other words, when the geometric parameter variable j is 2, it means that it is necessary to determine whether interference or singularities occur, so as to facilitate subsequent mechanical design.

[0122] After the case where the geometric parameter variable j is 2 is completed, the case where the geometric parameter variable j is 3 will continue to be executed.

[0123] Step S33: When the geometric parameter variable j is 3, determine whether the load generated by the thigh component linkage mechanism, the lower leg component linkage mechanism, and the ankle joint linkage mechanism is greater than the first preset threshold; if yes, assign a negative weight value to the geometric parameter variable j. If not, assign a positive weight value to the geometric parameter variable j.

[0124] The determination of whether the load generated by the thigh component linkage mechanism, the calf component linkage mechanism, and the ankle joint linkage mechanism is greater than the first preset threshold includes: inputting the geometric parameter variable j into the geometric relationship mathematical model to obtain the force that the thigh component linkage mechanism, the calf component linkage mechanism, and the ankle joint linkage mechanism need to bear during operation, thereby determining whether the load generated by the thigh component linkage mechanism, the calf component linkage mechanism, and the ankle joint linkage mechanism is greater than the first preset threshold.

[0125] In other words, when the geometric parameter variable j is 3, it means that it is necessary to determine whether the thigh component linkage mechanism, the lower leg component linkage mechanism, and the ankle joint linkage mechanism generate large loads. Large loads mean that the first link, the second link, and the third link need to withstand large forces or weights during operation, making the mechanism unable to operate stably.

[0126] After the case where the geometric parameter variable j is 3 is completed, the case where the geometric parameter variable j is 4 will continue to be executed.

[0127] Step S34: When the geometric parameter variable j is 4, derive the parameter correspondence and calculate the corresponding determination coefficient R2. Determine whether R2 is less than the second preset threshold (i.e., whether it allows the mechanism to have greater nonlinearity). The second preset threshold ranges from greater than 0 to less than 1. If so, it indicates that the thigh component linkage mechanism, lower leg component linkage mechanism, and ankle joint linkage mechanism have greater nonlinearity. In this case, assign a negative weight value to the geometric parameter variable j to obtain the geometric parameter variable j. Then, calculate the corresponding weight value W for each variable in the geometric parameter variable j. i Furthermore, each weight value is assigned an influencing factor parameter. If R² is greater than or equal to the second preset threshold, it indicates that the linearity of the thigh component linkage, lower leg component linkage, and ankle joint linkage is relatively high. In this case, a positive weight value is assigned to the geometric parameter variable j, thus obtaining the geometric parameter variable j. This ensures that the motion of the thigh component linkage, lower leg component linkage, and ankle joint linkage is as linear as possible, which is beneficial to improving the accuracy of motion control. Then, the corresponding weight value W is calculated for each variable in the geometric parameter variable j. i Furthermore, each weight value is assigned an influence factor parameter.

[0128] Linear actuators need to convert linear motion into rotational motion of joints. The force transmission through multi-link mechanisms inevitably leads to decoupling of joint rotation, resulting in a certain degree of nonlinearity. Therefore, simulation verification requires deriving parameter correspondences and calculating the corresponding coefficient of determination R² to determine the nonlinearity of the mechanism. This ensures that regardless of the mechanism's position, the linear actuator can move to a specific range, and the joints can rotate to a specific angle.

[0129] For example, the second preset threshold can be 0.1. If R² is less than 0.1, it means that it approaches 0. Conversely, if it is greater than 0.1, it means that it approaches 1. R² can be calculated by the sum of squares of the regression fitting model; for specific implementation, please refer to relevant technologies.

[0130] When all variables in geometric parameter j have been optimized, compare the weight values ​​W. i The geometric parameters i are optimized sequentially based on their weight values, starting with the largest weight value W and working backwards. Specifically, the geometric parameters i are optimized according to their weight values ​​from largest to smallest, prioritizing the larger weight values ​​W. i The corresponding geometric parameters, since those with larger weight values ​​have a more obvious correlation with the motion effect of the mechanism, are thus beneficial to improving optimization efficiency.

[0131] Then, determine whether the optimized geometric parameter variable j meets the mechanical and operating conditions requirements. If yes, provide the optimized geometric parameter variable j. If not, continue optimizing the parameter variable i in the geometric parameter variable j and execute steps S2 and S3.

[0132] The lower limb motion space optimization method provided in this application can improve the mechanical performance of the robot's lower limbs and reduce nonlinearity without affecting the workspace, enabling the robot to achieve better motion performance in a larger workspace. It achieves a pitch swing range of -50° to +120° for the thigh and 0° to 127° for the lower leg, significantly expanding the robot's leg's range of motion.

[0133] Meanwhile, by optimizing the geometric parameters of the linear actuator and linkage mechanism, a linear relationship between the extension and retraction of the linear actuator and the swing of the leg is ensured. This linearized control improves the positioning accuracy of the motion, providing more stable and accurate control, especially when high-precision operation or dynamic balancing is required. It further enhances the stiffness of the lower limb structure and its resistance to external loads, ensuring superior stability of the robot under dynamic loads.

[0134] Furthermore, this optimization method provides the optimal solution for geometric parameters through an algorithm flowchart, and can be widely applied to the design and simulation of multi-link mechanisms, improving the flexibility and overall performance of robot leg structure design.

[0135] The various embodiments or embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

[0136] It should be noted that the terms "one embodiment," "embodiment," "exemplary embodiment," "some embodiments," etc., mentioned in the specification indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0137] Generally speaking, terms should be understood at least in part by their use in context. For example, at least in part by context, the term "one or more" as used in the text can be used to describe any feature, structure, or characteristic of the singular meaning, or a combination of features, structures, or characteristics of the plural meaning. Similarly, at least in part by context, terms such as "a" or "the" can also be understood to convey either singular or plural usage.

[0138] It should be readily understood that the terms “on,” “above,” and “on top of” in this disclosure should be interpreted in the broadest possible sense, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on top of something” but also “on top of something” without an intermediate feature or layer therebetween (i.e., directly on something).

[0139] Furthermore, for ease of explanation, spatially relative terms such as "below," "below," "under," "above," and "above" may be used to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation other than those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for optimizing lower limb movement space, characterized in that, Applied to bionic robots, the bionic robot includes: a thigh component linkage mechanism, a thigh linear actuator, a lower leg component linkage mechanism, a lower leg linear actuator, an ankle joint linkage mechanism, an ankle joint linear actuator, and a first ankle pivot; The thigh component linkage mechanism is connected to the thigh component in a transmission connection, and the drive rod of the thigh linear actuator is connected to the thigh component linkage mechanism in a transmission connection. The thigh linear actuator drives the thigh component linkage mechanism to move, and the thigh component linkage mechanism drives the thigh component to rotate forward or backward. The thigh assembly is rotatably connected to the lower leg assembly at the knee joint, and the lower leg assembly includes a right leg side plate and a left leg side plate. The lower leg assembly linkage mechanism is connected to the lower leg assembly in a transmission manner, and the drive rod of the lower leg linear actuator is connected to the lower leg assembly linkage mechanism in a transmission manner. The lower leg linear actuator drives the lower leg assembly linkage mechanism to rotate the lower leg assembly forward or backward. The lower leg assembly is rotatably connected to both feet at the ankle joint; The ankle joint linkage mechanism is connected to the two feet via transmission, and the drive rod of the ankle joint linear actuator is connected to the ankle joint linkage mechanism via transmission. The ankle joint linear actuator drives the ankle joint linkage mechanism to rotate the two feet forward, backward, left, or right. The ankle joint linear actuator includes a first ankle joint linear actuator and a second ankle joint linear actuator, and the first ankle joint linear actuator and the second ankle joint linear actuator are respectively disposed at mounting positions on the left and right sides of the lower leg assembly; The first ankle pivot is a cross-shaped universal joint; The method includes: Establish a mathematical model of the geometric relationship between the thigh component, the calf component, and both feet; Obtain the geometric parameter variable j, and determine whether the geometric parameter variable j can increase the workspace. If so, determine whether the geometric parameter variable j can increase the workspace in one direction or in both directions. If it is in one direction, assign a smaller first weight value; if it is in both directions, assign a larger second weight value. The first weight value is less than the second weight value, and both are positive numbers. If not, assign a negative weight value. Determine whether interference or singularity has occurred; if so, assign a negative weight value; if not, assign a positive weight value. Determine whether the loads on the thigh component linkage mechanism, the calf component linkage mechanism, and the ankle joint linkage mechanism are greater than a first preset threshold; if yes, assign a negative weight value; if no, assign a positive weight value. The parameter correspondence is derived, and the corresponding determination coefficient R² is calculated. The determination coefficient R² is used to determine the nonlinearity of the mechanism. It is determined whether R² is less than the second preset threshold. If it is, a negative weight value is assigned; if not, a positive weight value is assigned. Optimize the lower limb movement space according to the weight values ​​from largest to smallest; Among them, the geometric parameter variable j includes: the length of AB, the coordinates of point B, the length of BC, the length of CD, the length of AD, the length of DE, the length of EF, and the length of CF in the thigh component linkage mechanism, and the length of CF is limited to between CF1 and CF2. The five points ABCDF together constitute the thigh component linkage mechanism. E is located on the extension line of AD, and DE is perpendicular to EF. Based on this, the corresponding mathematical model of the geometric relationship of the thigh component is established. The geometric parameter variable j includes: the lengths of GM, LM, HM, GH, LK, JK, and the coordinates of point L in the lower leg assembly linkage mechanism. The length of GM is limited to between GM1 and GM2, the length of HM is limited to between HM1 and HM2, and the length of LM is limited to between LM1 and LM2. The five points GMLKH together constitute the lower leg assembly linkage mechanism. J is located on the extension line of GH, and HJ is perpendicular to JK. Based on this, a corresponding mathematical model of the geometric relationship of the lower leg assembly is established. The geometric parameter variable j includes: the coordinates of point N and point P in the ankle joint linkage mechanism, the lengths of N1P1 and N2P2, angles Q0SQ and T0ST, with the coordinates of point N limited to N1 and N2, and the coordinates of point P limited to P1 and P2. N1, N, and N2 are fixed points on the right leg side plate, and P1, P, P2, Q, S, U0, and U are fixed points on the right foot. N1P1 and N2P2 correspond to the first and second ankle joint linear actuators, respectively. Point S corresponds to the universal joint. Angles Q0SQ and T0ST correspond to the right foot's forward and backward pitch angle and left and right swing angle, respectively. Based on this, a corresponding bipedal geometric relationship mathematical model is established.

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