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

Abstract

The invention provides a bionic robot based on a linear actuator and a lower limb motion space optimization method, relates to the technical field of robots, and aims to solve the technical problems of insufficient motion space and poor motion fluency of bionic robots in related technologies. The thigh linear actuator drives the thigh assembly connecting rod mechanism to drive the thigh assembly to rotate forwards or backwards; the shank component connecting rod mechanism is in transmission connection with the shank component; the shank linear actuator drives the shank component connecting rod mechanism to drive the shank component to rotate forwards or backwards; the ankle joint connecting rod mechanism is in transmission connection with the feet, and the ankle joint linear actuator drives the ankle joint connecting rod mechanism to drive the two feet to rotate forwards or backwards or leftwards or rightwards. By combining the linear actuator and the connecting rod mechanism, the mechanical property of the lower limbs is improved and the nonlinearity is reduced on the premise that the motion space is not affected, so that the robot achieves better motion performance in a larger motion space.

Description

Technical Field

[0001] The present application relates to the field of robotics, and in particular to a bionic robot based on a linear actuator and a method for optimizing the motion space of lower limbs. Background Art

[0002] In the related art, the joints of the bipedal motion system of humanoid robots use a rotary actuator combined with a mechanical transmission mechanism to convert rotary motion into linear or other complex motion forms. However, the motion form of biological muscles is mainly linear contraction, and it is difficult for rotary actuators to directly simulate this characteristic, resulting in poor smoothness and naturalness of robot motion; therefore, the method of combining rotary actuators with mechanical transmission mechanisms has certain limitations in terms of power density, structural complexity, positioning accuracy, and bionic effects. Summary of the invention

[0003] In view of the above problems, the embodiments of the present application provide a bionic robot based on a linear actuator and a method for optimizing the motion space of lower limbs to solve the problems of insufficient motion space and poor motion smoothness of the bionic robot in the related art.

[0004] In order to achieve the above objectives, the embodiments of the present application provide the following technical solutions:

[0005] The embodiment of the present application provides a bionic robot based on a linear actuator, which includes: a thigh component connecting rod mechanism, a thigh linear actuator, a calf component connecting rod mechanism, a calf linear actuator, an ankle joint connecting rod mechanism and an ankle joint linear actuator; the thigh component connecting rod mechanism is transmission-connected with the thigh component, the driving rod of the thigh linear actuator is transmission-connected with the thigh component connecting rod mechanism, the thigh linear actuator drives the thigh component connecting rod mechanism to move, and the thigh component connecting rod mechanism drives the thigh component to rotate forward or backward; the thigh component is rotationally connected to the calf component at the knee joint The calf assembly connecting rod mechanism is connected to the calf assembly in a transmission connection, the driving rod of the calf linear actuator is connected to the calf assembly connecting rod mechanism, the calf linear actuator drives the calf assembly connecting rod mechanism to drive the calf assembly to rotate forward or backward; the calf assembly is rotatably connected to the ankle joint with two feet; the ankle joint connecting rod mechanism is connected to the two feet in a transmission connection, the driving rod of the ankle joint linear actuator is connected to the ankle joint connecting rod mechanism, the ankle joint linear actuator drives the ankle joint connecting rod mechanism to drive the two feet to rotate forward, backward, left or right.

[0006] In one embodiment of the present application, the thigh component linkage mechanism includes: a first connecting rod, a second connecting rod, a first thigh rotating shaft, a second thigh rotating shaft, a third thigh rotating shaft, a fourth thigh rotating shaft and a fifth thigh rotating shaft; the thigh component is rotatably connected to the hip joint component through the first thigh rotating shaft; one end of the first connecting rod is rotatably connected to the hip joint component through the second thigh rotating shaft, one end of the thigh linear actuator has a first driving rod, and the other end of the first connecting rod is rotatably connected to the first driving rod through the third thigh rotating shaft; one end of the second connecting rod is rotatably connected to the first driving rod through the third thigh rotating shaft, and the other end of the second connecting rod is rotatably connected to the thigh component through the fourth thigh rotating shaft; the other end of the thigh linear actuator is rotatably connected to the thigh component through the fifth thigh rotating shaft; wherein the central axes of the first thigh rotating shaft, the second thigh rotating shaft, the third thigh rotating shaft, the fourth thigh rotating shaft and the fifth thigh rotating shaft are all parallel to the left and right directions of the bionic robot.

[0007] In one embodiment of the present 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 the present application, the calf component linkage mechanism includes: a third link, a fourth link, a first calf pivot, a second calf pivot, a third calf pivot, a fourth calf pivot and a fifth calf pivot; one end of the calf linear actuator has a second drive rod, and the other end of the calf linear actuator is rotatably connected to the thigh component through the first calf pivot; one end of the third link is rotatably connected to the second drive rod through the second calf pivot, and the other end of the third link is rotatably connected to the thigh component through the fifth calf pivot; one end of the fourth link is rotatably connected to the second drive rod through the second calf pivot, and the other end of the fourth link is rotatably connected to the calf component through the third calf pivot; the calf component is also rotatably connected to the thigh component through the fourth calf pivot; wherein the central axes of the first calf pivot, the second calf pivot, the third calf pivot, the fourth calf pivot and the fifth calf pivot are all parallel to the left-right direction of the bionic robot.

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

[0010] In one embodiment of the present application, 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 arranged at the installation positions on the left and right sides of the calf assembly; when the first ankle joint linear actuator and the second ankle joint linear actuator are extended and retracted at the same time, the ankle joint linkage mechanism drives the two feet to rotate forward or backward; when the first ankle joint linear actuator is extended and the second ankle joint linear actuator is contracted, or when the first ankle joint linear actuator is contracted and the second ankle joint linear actuator is extended, the ankle joint linkage mechanism drives the two feet to swing to the left or to the right.

[0011] In one embodiment of the present 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 driving rod, the third driving rod is rotatably connected to the ankle joints of the two feet through the second ankle pivot, the other end of the first ankle joint linear actuator is rotatably connected to the calf assembly through the third ankle pivot; the calf assembly is also rotatably connected to the ankle joints of the two feet through the first ankle pivot.

[0012] In one embodiment of the present application, the other end of the first ankle joint linear actuator is connected to the calf assembly at the third ankle rotation axis through a ball joint, and one end of the first ankle joint linear actuator is connected to the ankle joints of both feet at the second ankle rotation axis through a ball joint.

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

[0014] The present application also provides a method for optimizing the lower limb motion space, which is applied to the bionic robot described above and includes:

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

[0016] Get 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 so, assign a positive weight value to the geometric parameter variable j; if not, 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 so, assign a negative weight value to the geometric parameter variable j; if not, 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 link mechanism, the calf component link mechanism and the ankle joint link mechanism are greater than a first preset threshold; if so, assign a negative weight value to the geometric parameter variable j; if not, 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 to determine whether R2 is less than the second preset threshold; if so, a negative weight value is assigned to the geometric parameter variable j; if not, a positive weight value is assigned to the geometric parameter variable j.

[0020] The bionic robot based on the linear actuator provided in the embodiment of the present application has the following technical effects:

[0021] The use of linear actuators to provide linear motion simplifies the mechanical design of the robot's leg joints, eliminates the need for additional limit devices, and reduces structural complexity. The movement of the linear actuator is similar to the linear contraction of biological muscles and can more naturally simulate the movement mechanism of biological muscles, giving it certain advantages in gait control and movement coordination.

[0022] By combining the linear actuator with the linkage mechanism, the spatial range of movement of the thigh component, calf component and feet is effectively enlarged, so that the thigh component can achieve a forward and backward pitch swing within the range of -50° to 120°, the calf component can achieve a swing of 0° to 127°, and the feet can achieve a pitch swing of -62° to 11° and a rolling swing of ±25°. At the same time, the linear actuator's telescopic amount and swing amount maintain a linear relationship, which optimizes the linear actuator's control efficiency and motion smoothness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

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

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

[0026] Figure 3 A schematic diagram of the structure of a thigh component of a bionic robot provided in an embodiment of the present application;

[0027] Figure 4 The lower limb bending state of the bionic robot provided in the embodiment of the present application Figure 1 ;

[0028] Figure 5 The lower limb bending state of the bionic robot provided in the embodiment of the present application Figure 2 ;

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

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

[0031] Figure 8 The lower limb bending state of the bionic robot provided in the embodiment of the present application Figure 3 ;

[0032] Fig. 9 A schematic diagram of the structure of the calf assembly of the bionic robot provided in an embodiment of the present application;

[0033] Fig.10 A schematic diagram of the structure of a hip joint assembly of a bionic robot provided in an embodiment of the present application;

[0034] Fig.11 A mathematical model of the geometric relationship of the thigh of the bionic robot provided in the embodiment of the present application;

[0035] Fig.12 A mathematical model of the geometric relationship of the lower leg of the bionic robot provided in the embodiment of the present application;

[0036] Fig.13 A mathematical model of the bipedal geometric relationship of the bionic robot provided in the embodiment of the present application;

[0037] Fig.14 A flow chart for optimizing the lower limb motion space of a bionic robot provided in an embodiment of the present application.

[0038] Reference numerals:

[0039] 100-Hip plate;

[0040] 101- first lower limb rotation motor; 102- second lower limb rotation motor; 103- first lower limb side swing motor; 104- second lower limb side swing motor;

[0041] 301 - first linear actuator; 302 - second linear actuator; 303 - third linear actuator; 304 - fourth linear actuator;

[0042] 3011-first driving rod; 3031-second driving rod;

[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 driving rod; 5021-fourth driving rod;

[0046] 601-right leg side plank; 602-left leg side plank;

[0047] 701-first connecting rod; 702-second connecting rod; 703-third connecting rod; 704-fourth connecting rod;

[0048] 801-right leg fixing piece; 802-left leg fixing piece;

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

[0050] A-first thigh rotation; B-second thigh rotation; C-third thigh rotation; D-fourth thigh rotation; F-fifth thigh rotation; G-first calf rotation; M-second calf rotation; L-third calf rotation; K-fourth calf rotation; H-fifth calf rotation; S-first ankle rotation; P-second ankle rotation; N-third ankle rotation. DETAILED DESCRIPTION

[0051] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of this application.

[0052] The left-right direction and the front-back direction in the embodiments of the present application refer to the left-right and front-back of the bionic robot.

[0053] refer to Figure 1 and Fig.10The embodiment of the present application provides a bionic robot based on a linear actuator, the bionic robot comprising: a hip joint assembly, the hip joint assembly comprising a hip joint fixation plate 100, a first lower limb rotary motor 101 and a second lower limb rotary motor 102 are arranged on the front of the hip joint fixation plate 100, 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; a first lower limb side swing motor 103 and a second lower limb side swing motor 104 are arranged on the back of the hip joint fixation plate 100, the first lower limb side swing motor 103 is used to drive the right leg to swing to the left or to the right, and the second lower limb side swing motor 104 is used to drive the left leg to swing to the left or to the right.

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

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

[0056] The bionic robot also includes: a thigh linear actuator, which includes: a first linear actuator 301 and a second linear actuator 302, the first linear actuator 301 is arranged in the installation cavity at the rear end of the right leg base 401, and the second linear actuator 302 is arranged in the installation 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, and 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 connecting rod 701, a second connecting rod 702, a first thigh rotating shaft A, a second thigh rotating shaft B, a third thigh rotating shaft C, a fourth thigh rotating shaft D and a fifth thigh rotating shaft F. The right leg base 401 is rotatably connected to the right leg fixing member 801 through the first thigh rotating shaft A, one end of the first connecting rod 701 is rotatably connected to the right leg fixing member 801 through the second thigh rotating shaft B, the other end of the first connecting rod 701 is rotatably connected to the first driving rod 3011 of the first linear actuator 301 through the third thigh rotating shaft C, one end of the second connecting rod 702 is also rotatably connected to the first driving rod 3011 of the first linear actuator 301 through the third thigh rotating shaft C, and the other end of the second connecting rod 702 is rotatably connected to the right leg base 401 through the fourth thigh rotating shaft D.

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

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

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

[0062] like Figure 4 As shown, when the first driving rod 3011 of the first linear actuator 301 is extended, the right leg base 401 rotates forward; Figure 5 As shown, when the first driving rod 3011 of the first linear actuator 301 contracts, the right leg base 401 rotates backward.

[0063] The first driving rod 3011, the first connecting rod 701, the second connecting rod 702, the first thigh rotating shaft A, the second thigh rotating shaft B, the third thigh rotating shaft C, the fourth thigh rotating shaft D and the fifth thigh rotating shaft F together constitute a thigh assembly connecting rod mechanism for driving the right leg base 401 to rotate forward or backward. The thigh assembly connecting rod mechanism is transmission-connected to the thigh assembly, the driving rod of the thigh linear actuator is transmission-connected to the thigh assembly connecting rod mechanism, the thigh linear actuator drives the thigh assembly connecting rod mechanism to move, and the thigh assembly connecting rod 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 movement is effectively enlarged, so that the thigh assembly can achieve a forward and backward pitch swing within a range of -50° to 120°. At the same time, the extension amount of the first driving rod 3011 of the first linear actuator 301 maintains a linear relationship with the swing amount of the thigh assembly, which optimizes the control efficiency and movement smoothness of the first linear actuator 301.

[0065] In the embodiment of the present application, 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, so that the robot can monitor the motion state and external environmental changes in real time, and provide high-precision feedback information for subsequent mechanical control algorithms based on sensor data (such as reinforcement learning algorithms, etc.); it provides a basis for the robot to achieve more complex motion control and helps 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 component, 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 calf linear actuator, which includes: a third linear actuator 303 and a fourth linear actuator 304, the third linear actuator 303 is arranged in the installation cavity at the front end of the right leg base 401, and the fourth linear actuator 304 is arranged in the installation cavity at the front end of the left leg base 402.

[0068] The bionic robot also includes: a calf assembly, the knee joint of the thigh assembly is rotatably connected to the calf assembly, the calf assembly includes a right leg side plate 601 and a left leg side plate 602, the third linear actuator 303 is used to drive the right leg side plate 601 to rotate forward or backward, and the fourth linear actuator 304 is used to drive 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 are the same, and the rotation principle of the right leg side plate 601 is described below.

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

[0071] Among them, the central axes of the first calf rotation axis G, the second calf rotation axis M, the third calf rotation axis L, the fourth calf rotation axis K, and the fifth calf rotation axis H are all parallel to the left-right direction of the bionic robot.

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

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

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

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

[0076] By combining the calf linear actuator with the calf assembly connecting rod mechanism, the spatial range of movement of the calf assembly is effectively enlarged, allowing the calf assembly to swing from 0° to 127°; at the same time, the extension and retraction amount of the second driving rod 3031 of the third linear actuator 303 maintains a linear relationship with the swing amount of the calf, thereby optimizing the control efficiency and movement smoothness of the third linear actuator 303.

[0077] In the embodiment of the present application, a second force sensor and a second distance sensor are also provided at one end of the calf linear actuator; specifically, a second force sensor and a second distance sensor are also provided at one end of the third linear actuator 303, so that the robot can monitor the motion state and external environmental changes in real time, and provide high-precision feedback information for subsequent mechanical control algorithms based on sensor data (such as reinforcement learning algorithms, etc.); it provides a basis for the robot to achieve more complex motion control and helps to improve the ability of force control and adaptive control.

[0078] It should be noted that, by providing the second force sensor and the second distance sensor on the third linear actuator 303 , the installation and arrangement of the force sensor and the distance sensor can be simplified, and the mechanical transmission structure of the calf assembly can be further simplified.

[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 arranged at the installation positions on the left and right sides of the calf component.

[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 arranged at the installation positions 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 arranged at the installation positions on the left and right sides of the left leg side plate 602.

[0081] The bionic robot also includes: two feet, the ankle joints of the calf components are rotatably connected to the two feet, the ankle joint connecting rod mechanism is transmission connected to the two feet, the driving rod of the ankle joint linear actuator is transmission connected to the ankle joint connecting rod mechanism, and the ankle joint linear actuator drives the ankle joint connecting rod mechanism to drive the two feet to rotate 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 are extended and retracted at the same time, the ankle joint linkage mechanism drives the right foot 901 to rotate forward or backward; when the first ankle joint linear actuator 501 is extended and the second ankle joint linear actuator 502 is contracted, or when the first ankle joint linear actuator 501 is contracted and the second ankle joint linear actuator 502 is extended, the ankle joint linkage mechanism drives the right foot 901 to swing to the left or to the right.

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

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

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

[0087] Similarly, one end of the second ankle joint linear actuator 502 has a fourth driving rod 5021, and the fourth driving rod 5021 is rotationally connected to the ankle joint of the right foot 901 through the second ankle rotation axis P, and the other end of the second ankle joint linear actuator 502 is rotationally connected to the right leg side plate 601 through the third ankle rotation axis N.

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

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

[0090] When the third driving rod 5011 of the first ankle joint linear actuator 501 and the fourth driving rod 5021 of the second ankle joint linear actuator 502 are extended at the same time, the right foot 901 rotates forward; when the third driving rod 5011 of the first ankle joint linear actuator 501 and the fourth driving rod 5021 of the second ankle joint linear actuator 502 are contracted at the same time, the right foot 901 rotates backward.

[0091] The third driving rod 5011, the fourth driving rod 5021, the first ankle rotation axis S, the second ankle rotation axis P and the third ankle rotation axis N together constitute 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 driving rod 5011 of the first ankle joint linear actuator 501 is extended, the fourth driving rod 5021 of the second ankle joint linear actuator 502 can be contracted; or when the third driving rod 5011 of the first ankle joint linear actuator 501 is contracted, the fourth driving rod 5021 of the second ankle joint linear actuator 502 can be extended; 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] Among them, the first ankle rotation axis S can be a cross universal joint, so that the first ankle joint linear actuator 501 and the second ankle joint linear actuator 502 can drive the right foot 901 to rotate forward or backward around the first ankle rotation axis S; the connecting line between the first ankle rotation axis S and the second ankle rotation axis P is SP, and 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 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 enlarged, so that the right foot 901 can achieve a pitch swing of -62° to 11° and a roll swing of ±25°.

[0095] In the embodiment of the present application, the displacement output end of the first ankle joint linear actuator 501 is also provided 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 provided with a third force sensor and a third distance sensor, so that the robot can monitor the motion state and external environmental changes in real time, and provide high-precision feedback information for subsequent mechanical control algorithms based on sensor data (such as reinforcement learning algorithms, etc.); it provides a basis for the robot to achieve more complex motion control and helps to improve the ability of force control and adaptive control.

[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 component, thereby simplifying the installation and arrangement of the force sensor and the distance sensor.

[0097] In summary, the bionic robot based on linear actuator provided in the embodiment of the present 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 movement form of the linear actuator is similar to the linear contraction of biological muscles, and can more naturally simulate the movement mechanism of biological muscles, giving it certain advantages in gait control and movement coordination.

[0098] By combining the linear actuator with the linkage mechanism, the spatial range of movement of the thigh component, calf component and feet is effectively enlarged, so that the thigh component can achieve a forward and backward pitch swing within the range of -50° to 120°, the calf component can achieve a swing of 0° to 127°, and the feet can achieve a pitch swing of -62° to 11° and a rolling swing of ±25°. At the same time, the linear actuator's telescopic amount and swing amount maintain a linear relationship, which optimizes the linear actuator's control efficiency and motion smoothness.

[0099] Furthermore, linear actuators have higher power density and can provide greater thrust and energy conversion efficiency in a limited space.

[0100] The present application also provides a method for optimizing lower limb motion space, including:

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

[0102] like Fig.11 As shown, the five points ABCDF together constitute the thigh assembly linkage mechanism, E is located on the extension line of AD, and DE is perpendicular to EF, so as to obtain the position of point F.

[0103] The variables in the thigh component linkage mechanism are: AB length, B point coordinates, BC length, CD length, AD length, DE length, EF length; since the first driving rod 3011 can be extended or shortened, the CF length is limited between CF1 and CF2; α represents the pitch angle of the thigh component, and then the working space of the thigh component can be obtained, based on which the corresponding mathematical model of the geometric relationship of the thigh component is established.

[0104] like Fig.12As shown, the five points GMLKH together constitute the calf assembly linkage mechanism, J is located on the extension line of GH, and HJ is perpendicular to JK, so as to obtain the position of point K; since the second driving rod 3031 can be extended or shortened, the length of GM is limited between GM1 and GM2; β represents the pitch angle of the calf assembly, and then the working space of the calf assembly can be obtained, based on which the corresponding mathematical model of the geometric relationship of the calf assembly is established.

[0105] like Fig.13 As shown, N1, N, N2 are fixed points on the right leg side plate 601, P1, P, P2, Q, S, U0, U are all 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, and the length of N1P1 and the length of N2P2 can be changed; point S corresponds to the cross universal joint, and the angle Q0SQ and the angle T0ST correspond to the front and rear pitch angle (Pitch) and the left and right swing angle (Roll) of the right foot 901 respectively, and then the working space of the right foot 901 can be obtained, based on which the corresponding mathematical model of the geometric relationship of the two feet is established.

[0106] Among them, N1P1 and N2P2 not only have length limitations, but also need angle limitations, that is, 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, the present application optimizes each variable in the geometric parameter variable j. 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 a weight. In addition, for the i-th variable in the geometric parameter variable j, the optimization is performed specifically according to the cases where j is equal to 1, 2, 3, and 4, that is, step S2 and step S3 are performed in sequence for the i-th variable until all parameter variables in the geometric parameter variable j are optimized.

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

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

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

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

[0112] Step S3: Determine whether the geometric parameter variable j can increase the working space, whether interference or singularity points 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 motion space.

[0113] like Fig.14 , step S3 comprises:

[0114] Step S31: when the geometric parameter variable j is 1, determine whether the geometric parameter variable j can increase the workspace, if so, 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] Among them, judging whether the geometric parameter variable j can increase the working space includes: inputting the geometric parameter variable j into the geometric relationship mathematical model, obtaining the maximum occupied space during the movement of the lower limbs, and judging whether the geometric parameter variable j can increase the working space.

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

[0117] That is to say, 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 executed, the case where the geometric parameter variable j is 2 is continued.

[0119] Step S32: When the geometric parameter variable j is 2, determine whether interference or singularity occurs; if so, 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 step of judging whether interference or singular points are generated 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 judging whether interference or singular points are generated.

[0121] That is to say, when the geometric parameter variable j is 2, it means that it is necessary to determine whether interference or singularity occurs for subsequent mechanical design.

[0122] After the case where the geometric parameter variable j is 2 is executed, the execution continues with the case where the geometric parameter variable j is 3.

[0123] Step S33: When the geometric parameter variable j is 3, determine whether the loads generated by the thigh component link mechanism, the calf component link mechanism and the ankle joint link mechanism are greater than a first preset threshold; if so, 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] Among them, judging whether the load generated by the thigh component link mechanism, the calf component link mechanism and the ankle joint link mechanism is greater than the first preset threshold value includes: inputting the geometric parameter variable j into the geometric relationship mathematical model, obtaining the force that the thigh component link mechanism, the calf component link mechanism and the ankle joint link mechanism need to bear during operation, so as to judge whether the load generated by the thigh component link mechanism, the calf component link mechanism and the ankle joint link mechanism is greater than the first preset threshold value.

[0125] That is to say, when the geometric parameter variable j is 3, it means that it is necessary to judge whether the thigh component linkage mechanism, the calf component linkage mechanism and the ankle joint linkage mechanism generate a large load. A large load means that the first link, the second link and the third link need to bear a large force or weight during operation, making the mechanism unable to operate stably.

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

[0127] Step S34: When the geometric parameter variable j is 4, the parameter correspondence is derived, and the corresponding determination coefficient R2 is calculated to determine whether R2 is less than the second preset threshold (that is, whether the mechanism has a larger nonlinearity). Among them, the value range of the second preset threshold is greater than 0 and less than 1. If so, it means that the nonlinearity of the thigh component linkage mechanism, the calf component linkage mechanism and the ankle joint linkage mechanism is large. In this case, a negative weight value is assigned to the geometric parameter variable j to obtain the geometric parameter variable j. Then, the corresponding weight value W is calculated for each variable in the geometric parameter variable j. i , and assign influencing factor parameters to each weight value. If R2 is greater than or equal to the second preset threshold, it means that the linearity of the thigh component linkage mechanism, the calf component linkage mechanism and the ankle joint linkage mechanism is large. In this case, a positive weight value is assigned to the geometric parameter variable j to obtain the geometric parameter variable j. In this way, the movement of the thigh component linkage mechanism, the calf component linkage mechanism and the ankle joint linkage mechanism can be ensured to be biased towards linear control as much as possible, which is conducive to improving the accuracy of motion control. And then the corresponding weight value W is calculated for each variable in the geometric parameter variable j. i , and assign impact factor parameters to each weight value.

[0128] Among them, the linear actuator needs to convert the linear motion into the rotational motion of the joint. The force transmission through the multi-link mechanism will inevitably cause the joint rotation decoupling to produce a certain degree of nonlinearity; therefore, the parameter correspondence needs to be derived during simulation verification, and the corresponding determination coefficient R2 needs to be calculated to determine the nonlinearity of the mechanism. This ensures that no matter where the mechanism runs, the linear actuator can move to a specific range and the joint can rotate to a specific angle.

[0129] For example, the second preset threshold may be 0.1, and if R2 is less than 0.1, it means that it is close to 0. Otherwise, it means that it is close to 1. R2 can be calculated by the sum of squares of the regression fitting model, and the specific implementation can refer to the relevant technology.

[0130] When all variables in the geometric parameter variable j are optimized, the weight value W is compared. i Specifically, the geometric parameters i are optimized in descending order according to the weight values, with the larger weight value W being the first to be optimized. i The corresponding geometric parameters, since the geometric parameters corresponding to larger weight values ​​are more obviously related to the movement effect of the mechanism, this is conducive to improving the optimization efficiency.

[0131] Then, it is determined whether the optimized geometric parameter variable j meets the mechanical and working condition requirements. If so, the optimized geometric parameter variable j is given. If not, the parameter variable i in the geometric parameter variable j is continuously optimized, and steps S2 and S3 are executed.

[0132] The lower limb motion space optimization method provided in the embodiment of the present application can improve the mechanical properties of the robot's lower limbs and reduce nonlinearity without affecting the workspace, so that the robot can achieve better motion performance in a larger workspace. The pitch swing range of the thigh is -50° to +120° and the calf is 0° to 127°, which greatly expands the activity space of the robot's legs.

[0133] At the same time, by optimizing the geometric parameters of the linear actuator and the linkage mechanism, the linear relationship between the extension and contraction of the linear actuator and the swing of the legs is ensured. This linear control improves the positioning accuracy of the movement, especially when high-precision operation or dynamic balance is required, it can provide more stable and accurate control. The stiffness and external load resistance of the lower limb structure are further improved, ensuring that the robot has excellent stability under dynamic loads.

[0134] In addition, this optimization method gives the optimal solution of geometric parameters through an algorithm flow chart, and can be widely used in the design and simulation of multi-link mechanisms to improve the flexibility and overall performance of the robot leg structure design.

[0135] In this specification, each embodiment or example is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referenced to each other.

[0136] It should be noted that the phrases "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. mentioned in the specification indicate that the described embodiments may include certain features, structures or characteristics, but not every embodiment may include the certain features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when describing certain features, structures or characteristics in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures or characteristics in conjunction with other embodiments, whether explicitly or not explicitly described.

[0137] In general, terms should be understood, at least in part, by the context in which they are used. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," or "the" may also be understood to convey singular usage or to convey plural usage, depending, at least in part, on the context.

[0138] It should be easily understood that “on,” “above,” and “over” in the present disclosure should be interpreted in the broadest manner, so that “on” not only means “directly on something,” but also includes the meaning of “on something” with intervening features or layers therebetween, and “above” or “over” not only includes the meaning of “above” or “over,” but also may include the meaning of “above” or “over something” with no intervening features or layers therebetween (i.e., directly on something).

[0139] In addition, spatially relative terms, such as "below," "below," "beneath," "above," "above," etc., may be used herein for ease of description 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 in addition to the orientation shown in the figures. The device may have other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A bionic robot based on a linear actuator, characterized in that: include: A thigh assembly linkage mechanism, a thigh linear actuator, a calf assembly linkage mechanism, a calf linear actuator, an ankle joint linkage mechanism, and an ankle joint linear actuator; The thigh assembly connecting rod mechanism is transmission-connected with the thigh assembly, the driving rod of the thigh linear actuator is transmission-connected with the thigh assembly connecting rod mechanism, the thigh linear actuator drives the thigh assembly connecting rod mechanism to move, and the thigh assembly connecting rod mechanism drives the thigh assembly to rotate forward or backward; The thigh component is rotatably connected to the calf component at the knee joint; The calf assembly connecting rod mechanism is transmission-connected to the calf assembly, the driving rod of the calf linear actuator is transmission-connected to the calf assembly connecting rod mechanism, and the calf linear actuator drives the calf assembly connecting rod mechanism to drive the calf assembly to rotate forward or backward; The ankle joint of the calf component is rotatably connected to the two feet; The ankle joint linkage mechanism is transmission connected to the two feet, the driving rod of the ankle joint linear actuator is transmission connected to the ankle joint linkage mechanism, and the ankle joint linear actuator drives the ankle joint linkage mechanism to drive the two feet to rotate forward, backward, left or right.

2. The bionic robot based on a linear actuator according to claim 1, characterized in that: The thigh assembly connecting rod mechanism comprises: a first connecting rod, a second connecting rod, a first thigh rotating shaft, a second thigh rotating shaft, a third thigh rotating shaft, a fourth thigh rotating shaft and a fifth thigh rotating shaft; The thigh assembly is rotatably connected to the hip joint assembly via the first thigh rotation shaft; One end of the first connecting rod is rotatably connected to the hip joint assembly through the second thigh rotating shaft, one end of the thigh linear actuator has a first driving rod, and the other end of the first connecting rod is rotatably connected to the first driving rod through the third thigh rotating shaft; One end of the second connecting rod is rotatably connected to the first driving rod through the third thigh rotating shaft, and the other end of the second connecting rod is rotatably connected to the thigh component through the fourth thigh rotating shaft; The other end of the thigh linear actuator is rotationally connected to the thigh component through the fifth thigh rotating shaft; Among them, the central axes of the first thigh rotation axis, the second thigh rotation axis, the third thigh rotation axis, the fourth thigh rotation axis and the fifth thigh rotation axis are all parallel to the left-right direction of the bionic robot.

3. The bionic robot based on a linear actuator according to claim 2, characterized in that: A first force sensor and a first distance sensor are also provided at one end of the thigh linear actuator.

4. The bionic robot based on a linear actuator according to claim 1, characterized in that: The calf assembly connecting rod mechanism comprises: a third connecting rod, a fourth connecting rod, a first calf rotating shaft, a second calf rotating shaft, a third calf rotating shaft, a fourth calf rotating shaft and a fifth calf rotating shaft; One end of the calf linear actuator has a second driving rod, and the other end of the calf linear actuator is rotatably connected to the thigh component through the first calf rotating shaft; One end of the third connecting rod is rotatably connected to the second driving rod through the second calf rotating shaft, and the other end of the third connecting rod is rotatably connected to the thigh component through the fifth calf rotating shaft; One end of the fourth connecting rod is rotatably connected to the second driving rod through the second calf rotating shaft, and the other end of the fourth connecting rod is rotatably connected to the calf assembly through the third calf rotating shaft; The calf component is also rotatably connected to the thigh component via the fourth calf rotating shaft; Among them, the central axes of the first calf rotation axis, the second calf rotation axis, the third calf rotation axis, the fourth calf rotation axis and the fifth calf rotation axis are all parallel to the left-right direction of the bionic robot.

5. The bionic robot based on a linear actuator according to claim 4, characterized in that: A second force sensor and a second distance sensor are also provided at one end of the calf linear actuator.

6. The bionic robot based on a linear actuator according to claim 1, characterized in that: The ankle joint linear actuator comprises a first ankle joint linear actuator and a second ankle joint linear actuator, wherein the first ankle joint linear actuator and the second ankle joint linear actuator are respectively arranged at installation positions on the left and right sides of the calf assembly; When the first ankle joint linear actuator and the second ankle joint linear actuator are extended and retracted at the same time, the ankle joint linkage mechanism drives the two feet to rotate forward or backward; When the first ankle joint linear actuator extends and the second ankle joint linear actuator contracts, or when the first ankle joint linear actuator contracts and the second ankle joint linear actuator extends, the ankle joint linkage mechanism drives the two feet to swing to the left or to the right.

7. The bionic robot based on a linear actuator according to claim 6, characterized in that: The ankle joint linkage mechanism includes: a first ankle rotation axis, a second ankle rotation axis and a third ankle rotation axis; One end of the first ankle joint linear actuator has a third driving rod, and the third driving rod is rotatably connected to the ankle joints of the two feet through the second ankle rotating shaft, and the other end of the first ankle joint linear actuator is rotatably connected to the calf component through the third ankle rotating shaft; The calf assembly is also rotationally connected to the ankle joints of the two feet via the first ankle rotation axis.

8. The bionic robot based on a linear actuator according to claim 6, characterized in that: The other end of the first ankle joint linear actuator is connected to the calf assembly at the third ankle rotation axis through a ball joint, and one end of the first ankle joint linear actuator is connected to the ankle joints of both feet at the second ankle rotation axis through a ball joint.

9. The bionic robot based on a linear actuator according to claim 6, characterized in that: A third force sensor and a third distance sensor are disposed at one end of the first ankle joint linear actuator and the second ankle joint linear actuator.

10. A method for optimizing lower limb motion space, characterized in that: A bionic robot as claimed in any one of claims 1 to 9, comprising: Establish a mathematical model of the geometric relationship between the thigh component, the calf component and the feet; Get 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 so, assign a positive weight value to the geometric parameter variable j; if not, assign a negative weight value to the geometric parameter variable j. When the geometric parameter variable j is 2, determine whether interference or singularity occurs; if so, assign a negative weight value to the geometric parameter variable j; if not, assign a positive weight value to the geometric parameter variable j; When the geometric parameter variable j is 3, determine whether the loads of the thigh component link mechanism, the calf component link mechanism and the ankle joint link mechanism are greater than a first preset threshold; if so, assign a negative weight value to the geometric parameter variable j; if not, assign a positive weight value to the geometric parameter variable j; When the geometric parameter variable j is 4, the parameter correspondence is derived, and the corresponding determination coefficient R2 is calculated to determine whether R2 is less than the second preset threshold; if so, a negative weight value is assigned to the geometric parameter variable j; if not, a positive weight value is assigned to the geometric parameter variable j.

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