Amphibious reptile bionic robot leg structure and lightweight design method thereof

Abstract

The present application belongs to the related technical field of bionic robot, and discloses a amphibious crawling bionic robot leg structure and a lightweight design method thereof, the leg structure is: the thigh assembly includes the inner side plate and the outer side plate, the first end of the inner side plate and the outer side plate is connected on the driving assembly respectively, and can rotate integrally under the driving of the driving assembly;The lower leg assembly includes the lower leg bone, the top of the lower leg bone is rotatably connected between the second end of the thigh assembly;The transmission assembly is arranged between the inner side plate and the outer side plate, and the transmission assembly can drive the lower leg bone to rotate under the driving of the driving assembly;The foot bottom assembly is connected to the bottom of the lower leg bone, the inner side plate, the outer side plate and the lower leg bone are provided as a dot matrix structure.The present application sets the thigh assembly to include independent inner side plate and outer side plate, and sets the inner side plate, the outer side plate and the lower leg bone as a dot matrix structure, which is beneficial to better realize lightweight and improve the performance of the leg structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of bionic robots, and more particularly relates to a leg structure of an amphibious crawling bionic robot and a lightweight design method thereof. BACKGROUND

[0002] In recent years, robot technology has developed rapidly. Robots are moving into more fields and are becoming closer to people's lives, which has led people to make more demands on them. In addition to completing basic tasks, robots also need to meet a series of higher performance requirements such as simple operation, low energy consumption, high flexibility, strong stability and good openness. Especially bionic robots, which have more advantages in mobility and environmental adaptability than traditional mobile robots, have been widely used in disaster rescue, resource exploration and reconnaissance. In view of the problems of excessive energy consumption, insufficient motion ability and flexibility and other related problems existing in the field of robots, lightweight design provides a better solution.

[0003] In recent decades, people have gradually increased their research on robot lightweight, and many achievements have emerged. However, the lightweight research of robots is far from meeting people's requirements and is not sufficient to support people's performance demands. The lightweight of robots is mainly realized from the aspects of materials and structure. At present, it is very convenient to make robots lightweight from the aspect of materials, but lightweight materials are high in cost and difficult to develop, and are difficult to be widely applied. With the popularization of 3D printing technology, the restrictions on making robots lightweight from the aspect of structure are less and less, and many manufacturing difficulties have been overcome, and lightweight materials can be used to achieve higher lightweight goals. Therefore, it is of great significance to make lightweight design of the leg structure of robots, reduce the weight while ensuring that the robots can work normally according to the requirements. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the present application provides a leg structure of an amphibious crawling bionic robot and a lightweight design method thereof, which is used to solve the problem that the lightweight research of existing robots is far from meeting people's requirements and is not sufficient to support people's performance demands.

[0005] To achieve the above object, according to a first aspect of the present application, a leg structure of an amphibious crawling bionic robot is provided, comprising a driving assembly, a thigh assembly, a transmission assembly, a shank assembly and a foot bottom assembly; the thigh assembly comprises a thigh inner side plate and a thigh outer side plate arranged oppositely, the first ends of the thigh inner side plate and the thigh outer side plate are connected to the driving assembly respectively and can rotate integrally under the driving of the driving assembly; the shank assembly comprises a shank bone, the top of the shank bone is rotatably connected between the second ends of the thigh inner side plate and the thigh outer side plate; the transmission assembly is arranged between the thigh inner side plate and the thigh outer side plate and is drivingly connected between the driving assembly and the shank bone and can drive the shank bone to rotate under the driving of the driving assembly; the foot bottom assembly is connected to the bottom of the shank bone, and the thigh inner side plate, the thigh outer side plate and the shank bone are arranged in a dot matrix structure.

[0006] According to the leg structure of the amphibious crawling bionic robot provided by the present application, the driving assembly comprises a first joint motor, a second joint motor and a third joint motor; the first joint motor is used to be connected to a robot body, the output end of the first joint motor is connected to the second joint motor through a first motor connecting member, the output end of the second joint motor is connected to the third joint motor through a second motor connecting member, the output end of the third joint motor is connected to the transmission assembly, the second joint motor and the third joint motor are coaxial, the second joint motor is used to drive the thigh assembly to perform leg lifting and leg folding actions, and the third joint motor is used to drive the shank assembly to perform leg lifting and leg folding actions.

[0007] According to the leg structure of the amphibious crawling bionic robot provided by the present application, the transmission assembly is a synchronous belt assembly, the synchronous belt assembly comprises a driving wheel, a driven wheel and a transmission belt, the driving wheel is rotatably connected to the first end of the thigh assembly and connected to the driving assembly, the driven wheel is rotatably connected to the second end of the thigh assembly and integrally rotatably connected to the shank bone, and the transmission belt is tensioned outside the driving wheel and the driven wheel.

[0008] According to the leg structure of the amphibious crawling bionic robot provided by the present application, the synchronous belt assembly further comprises a belt tensioner, the opposite sides of the thigh inner side plate and the thigh outer side plate are respectively provided with bosses, the belt tensioner is arranged on the bosses and used to tension the transmission belt.

[0009] According to the leg structure of the amphibious crawling bionic robot provided by the present application, the thigh inner side plate is connected to the driving assembly on one side of the driving wheel, the first end of the thigh outer side plate is connected with an arc-shaped connecting plate, and the thigh outer side plate is connected to the driving assembly on the other side of the driving wheel through the arc-shaped connecting plate.

[0010] The shank bone comprises two shank plates arranged oppositely and a reinforcing plate connected between the two shank plates.

[0011] According to the amphibious crawling bionic robot leg structure provided by the application, the foot bottom assembly comprises a ball foot base and a ball foot sleeve, the top of the ball foot base is connected to the bottom of the shank bone, the bottom of the ball foot base is spherical, and the ball foot sleeve is sleeved outside the ball foot base.

[0012] According to a second aspect of the application, a lightweight design method of an amphibious crawling bionic robot leg structure is provided, based on any one of the above-mentioned amphibious crawling bionic robot leg structures, the lightweight design method comprises:

[0013] designing the shape and size of the leg structure to obtain an initial leg structure model;

[0014] designing a reduction hole for the initial leg structure model to obtain a reduction leg structure model;

[0015] performing point lattice filling design on the structure of the medial femoral plate, the lateral femoral plate and the shank bone of the reduction leg structure model under a preset stress working condition and a preset constraint condition, with the optimization target of maximizing the stiffness, to obtain a lightweight leg structure model;

[0016] performing strength checking on the lightweight leg structure model, and completing the lightweight design after the checking.

[0017] According to the lightweight design method of the amphibious crawling bionic robot leg structure provided by the application, the preset stress working condition is determined by the following method:

[0018] performing motion trajectory planning on the amphibious crawling bionic robot under the diagonal gait and the tripedal gait respectively, and performing simulation motion according to the planned motion trajectory and the corresponding gait;

[0019] obtaining the stress condition of the foot bottom of the leg structure of the amphibious crawling bionic robot during the simulation motion;

[0020] selecting the maximum stress working condition of the foot bottom during the simulation motion as the preset stress working condition; wherein the maximum stress working condition comprises the stress size, the stress direction of the foot bottom of the leg structure and the corresponding standing posture of the leg structure.

[0021] According to the lightweight design method of the amphibious crawling bionic robot leg structure provided by the application, the preset stress working condition is specifically: the standing height of the leg structure is 0.16-0.20 m, the horizontal component of the stress at the foot end of the leg structure is 45-60 N and 18-30 N, and the vertical component of the stress is 660-700 N.

[0022] The preset constraint condition is specifically that a fixed constraint surface is arranged at the driving assembly.

[0023] The lightweight design method of the amphibious crawling bionic robot leg structure provided by the application comprises the following steps of:

[0024] The lightweight leg structure model is subjected to finite element analysis under preset stress working conditions and preset constraint conditions, strain information of a leg structure surface is obtained, and whether the strength requirement is met is determined according to the strain information.

[0025] Overall, compared with the prior art, the amphibious crawling bionic robot leg structure and the lightweight design method thereof provided by the application have the following advantages:

[0026] 1. The thigh assembly comprises independent inner and outer thigh plates, the number of components is reduced, the complexity is reduced, the weight of the thigh is reduced, and the assembly of the intermediate transmission assembly is facilitated; the driving assembly is arranged at the first end of the thigh assembly, so that the driving assembly does not need to be arranged at the calf, the flexibility of leg movement is improved, and the leg performance is improved; the inner and outer thigh plates and the calf bone are arranged in a dot matrix structure, the weight of the leg is further reduced, the lightweight is better achieved, and the leg structure performance is improved;

[0027] 2. The calf is driven by a synchronous belt, compared with the existing four-legged robot in which the calf is driven by a connecting rod, the calf has a larger movement range, and the transmission is more direct and efficient; the thigh assembly is divided into two parts, the synchronous belt and the tensioning device are hidden in the middle, the assembly is convenient, and the structure is more compact;

[0028] 3. The initial leg structure model of the amphibious crawling bionic robot is established by considering the actual working conditions and design requirements, the lightweight design of each main part of the amphibious crawling bionic robot leg structure is performed by using the reduction experience design and the grid optimization technology, the weight of the leg structure is reduced while the rigidity of the leg structure is ensured, and the flexibility and movement ability of the leg structure are indirectly improved;

[0029] 4. The motion planning and simulation are performed based on different gait modes during the grid optimization, the maximum stress working condition is selected as the preset stress working condition based on the stress in the simulation motion process, the optimization process of the dot matrix grid is more reliable, and the final leg structure obtained after the optimization design can better meet the normal activity requirements. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic view of the amphibious crawling bionic robot leg structure provided by the application;

[0031] Figure 2 is a schematic view of a medial thigh plate provided by the present application;

[0032] Figure 3 is a schematic view of a lateral thigh plate provided by the present application;

[0033] Figure 4 is a schematic view of a shank provided by the present application;

[0034] In all the drawings, the same reference signs are used to denote the same elements or structures, wherein:

[0035] 1, first joint motor; 2, second joint motor; 3, third joint motor; 4, first motor connecting piece; 5, second motor connecting piece; 6, medial thigh plate; 7, lateral thigh plate; 8, synchronous belt assembly; 9, belt tensioner; 10, shank; 11, foot base; 12, foot sleeve. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0037] Please refer to Figure 1 The embodiment provides an amphibious crawling bionic robot leg structure, which comprises a driving assembly, a thigh assembly, a transmission assembly, a shank assembly and a foot base assembly. The thigh assembly comprises a medial thigh plate 6 and a lateral thigh plate 7 arranged oppositely, the first ends of the medial thigh plate 6 and the lateral thigh plate 7 are connected to the driving assembly respectively and can rotate integrally under the driving of the driving assembly. The shank assembly comprises a shank 10, the top of the shank 10 is rotatably connected between the second ends of the medial thigh plate 6 and the lateral thigh plate 7. The transmission assembly is arranged between the medial thigh plate 6 and the lateral thigh plate 7, and is drivingly connected between the driving assembly and the shank 10 and can drive the shank 10 to rotate under the driving of the driving assembly. The foot base assembly is connected to the bottom of the shank 10. The medial thigh plate 6, the lateral thigh plate 7 and the shank 10 are arranged in a dot matrix structure.

[0038] Reference Figure 1In some specific embodiments, the driving assembly comprises a first joint motor 1, a second joint motor 2 and a third joint motor 3; the first joint motor 1 is connected with the robot body, the output end of the first joint motor 1 is connected with the second joint motor 2 through a first motor connecting piece 4, the output end of the second joint motor 2 is connected with the third joint motor 3 through a second motor connecting piece 5, the output end of the third joint motor 3 is connected with the transmission assembly, the second joint motor 2 and the third joint motor 3 are coaxial, the second joint motor 2 is used to drive the thigh assembly to perform the action of lifting the leg and collecting the leg, and the third joint motor 3 is used to drive the lower leg assembly to perform the action of lifting the leg and collecting the leg.

[0039] The first joint motor 1 is used to drive the second joint motor 2, the third joint motor 3, the thigh assembly, the lower leg assembly and the foot bottom assembly to rotate integrally, that is, to provide a rotating motion similar to the hip joint with the body. The second joint motor 2 is used to drive the third joint motor 3, the thigh assembly, the lower leg assembly and the foot bottom assembly to rotate, so as to realize the action of lifting and collecting the thigh. The motion axis of the second joint motor 2 is perpendicular to the motion axis of the first joint motor 1. The third joint motor 3 is used to drive the lower leg assembly and the foot bottom assembly to rotate through the transmission assembly, so as to realize the action of lifting and collecting the lower leg assembly. The foot bottom assembly is used to contact the ground.

[0040] Reference Figure 1 In some specific embodiments, the transmission assembly is a synchronous belt assembly 8, which comprises a driving wheel, a driven wheel and a transmission belt. The driving wheel is rotatably connected to the first end of the thigh assembly and connected with the driving assembly. The driven wheel is rotatably connected to the second end of the thigh assembly and integrally rotatably connected with the lower leg bone 10. The transmission belt is tensioned on the outer side of the driving wheel and the driven wheel. The driving assembly is used to drive the driving wheel to rotate, the driving wheel drives the driven wheel to rotate through the transmission belt, and the driven wheel drives the lower leg bone 10 to rotate integrally.

[0041] Further, the synchronous belt assembly 8 further comprises a belt tensioner 9, and the opposite sides of the inner thigh plate 6 and the outer thigh plate 7 are respectively provided with bosses. The belt tensioner 9 is arranged on the bosses and used to tension the transmission belt. The arrangement of the belt tensioner 9 is used to tension the transmission belt, which is beneficial to ensure the transmission efficiency.

[0042] Specifically, near the middle position of the thigh assembly (near the middle position of the two pulleys), there is a synchronous belt tensioning device on both sides of the synchronous belt. The tensioning mode is to press the synchronous belt downward / upward (extrude the synchronous belt to the middle) by tightening the M3 tensioning bolt to realize tensioning.

[0043] Specifically, reference Figure 1 and Figure 2The inner-thigh plate 6 is connected with the driving assembly on one side of the driving wheel, as shown in Figure 1 and Figure 3 The first end of the outer-thigh plate 7 is connected with an arc-shaped connecting plate, and the outer-thigh plate 7 is connected with the driving assembly on the other side of the driving wheel through the arc-shaped connecting plate.

[0044] The first end of the inner-thigh plate 6 and the first end of the outer-thigh plate 7 are connected with the third joint motor 3 on both sides of the driving wheel, which can provide a connecting space between the driving wheel and the output end of the third joint motor 3. The inner-thigh plate 6 and the outer-thigh plate 7 can be connected with the third joint motor 3 through M3 bolts, and the synchronous belt driving wheel can be fixed with the output flange plate of the third joint motor 3 through M3 bolts, so that the driving wheel can be smoothly driven to rotate. The outer-thigh plate 7 can be provided with an opening corresponding to the driving wheel, and a wheel cover can be detachably connected at the opening. The driving wheel can be rotatably connected with the outer-thigh plate 7 through a bearing at the opening on the side close to the outer-thigh plate 7. The arc-shaped connecting plate at the first end of the outer-thigh plate 7 can achieve the connection between the outer-thigh plate 7 and the third joint motor 3, and can also play a protective role outside the synchronous belt assembly 8.

[0045] Referring to Figure 4 The shank bone 10 includes two shank plates oppositely arranged and a reinforcing plate connected between the two shank plates.

[0046] The driven wheel can be rotatably connected with the thigh assembly through a rotating shaft. Specifically, the driven wheel is integrally rotatably connected with the rotating shaft, which can be achieved by a key structure or a fixed connection. The rotating shaft is rotatably connected with the thigh assembly through a bearing. At this time, the top of the two shank plates of the shank bone 10 can be integrally rotatably connected with the rotating shaft or the driven wheel to be rotatable relative to the thigh assembly. For example, the top of the shank plate can be y-shaped, and the top of the shank plate can be connected with the driven wheel through a bolt to be integrally rotatable with the synchronous belt assembly 8. The top of the shank plate can also be sleeved on the outside of the rotating shaft and be integrally rotatably connected with the rotating shaft through interference connection or key connection.

[0047] In other specific embodiments, the driven wheel can also be rotatably connected with the rotating shaft, and the rotating shaft can be fixedly connected with the thigh assembly, so that the driven wheel can also be rotatable relative to the thigh assembly. At this time, the top of the shank bone 10 can be connected with the driven wheel to be integrally rotatable. The connection mode of the driven wheel and the shank bone 10 relative to the thigh assembly is not limited, as long as it can be rotatable and the shank bone 10 can be driven to rotate by the rotation of the driven wheel.

[0048] The foot bottom assembly includes a ball foot base 11 and a ball foot sleeve 12. The top of the ball foot base 11 is connected with the bottom of the shank bone 10. The bottom of the ball foot base 11 is spherical. The ball foot sleeve 12 is sleeved on the outside of the ball foot base 11.

[0049] At least one of the medial thigh plate 6, the lateral thigh plate 7, the shank plate and the reinforcing plate is provided with a weight-reducing hole, i.e. a hollow hole, to reduce weight.

[0050] Further, the embodiment provides an amphibious crawling bionic robot, which comprises the amphibious crawling bionic robot leg structure according to any one of the above. Specifically, the bionic robot comprises a plurality of the above leg structures, and the bionic robot can be a bionic crocodile robot.

[0051] In some specific embodiments, a bionic crocodile robot is provided, which comprises a plurality of leg structures, each of which comprises a first joint motor 1, a second joint motor 2, a third joint motor 3, a 1-2 motor connecting piece, i.e. a first motor connecting piece 4, a 2-3 motor connecting piece, i.e. a second motor connecting piece 5, a medial thigh plate 6, a lateral thigh plate 7, a synchronous belt assembly 8, a belt tensioner 9, a shank bone 10, a ball foot base 11, and a ball foot sleeve 12.

[0052] The robot shank driving mode is belt driving, and the belt wheel type is S3M trapezoidal tooth 48 teeth with a belt width of 15 mm. The medial thigh plate 6 and the lateral thigh plate 7 are fixed with the motor through bolts, and the synchronous belt is located in the middle position of the two parts. There are bosses for installing the belt tensioner 9 on the side of the medial thigh plate 6 and the lateral thigh plate 7 close to the synchronous belt, i.e. the inner wall is not a flat surface. Aluminum columns can be additionally connected between the medial thigh plate and the lateral thigh plate for reinforced connection.

[0053] Further, the embodiment provides a lightweight design method of the amphibious crawling bionic robot leg structure, which is based on the amphibious crawling bionic robot leg structure according to any one of the above. The lightweight design method comprises:

[0054] Designing the shape and size of the leg structure to obtain an initial leg structure model;

[0055] Designing a weight-reducing hole in the initial leg structure model to obtain a weight-reduced leg structure model;

[0056] Performing point lattice filling design on the structure of the medial thigh plate 6, the lateral thigh plate 7 and the shank bone 10 of the weight-reduced leg structure model under a preset stress working condition and a preset constraint condition with the maximum stiffness as the optimization target to obtain a lightweight leg structure model, and simultaneously performing finite element analysis;

[0057] Performing strength checking on the lightweight leg structure model, and completing the lightweight design after the checking.

[0058] In this embodiment, the contour shape and structural size parameters of each component of the leg part can be determined according to the existing robot leg structure, combined with the actual working condition and overall structure of the robot, as an initial model of the leg structure; then according to the load working condition in the actual application process and design experience, while considering the manufacturing process technology, the local position of the leg structure is designed to be opened and reduced to reduce the weight while maintaining the structural strength, and finally the reduced leg structure model after preliminary reduction is obtained.

[0059] Then the reduced leg structure model after preliminary reduction is imported into the Inspire software, the correctness of the part connection is checked, the design space is set, the stress condition is set according to the extreme working condition in the obtained working condition data, that is, the pre-stress working condition and the constraint condition; then run optimization, input the model name in the pop-up dialog box, select the type as grid optimization, the optimization goal as maximum stiffness, set the related parameters of the lattice structure (the related parameters of the unit cell of the lattice structure can be selected according to the recommendation or experience, such as the maximum and minimum diameter of the rod, the target length, etc.), set the filling ratio (generally recommended to set 100% lattice structure) and mass target according to the demand, and the optimized robot leg structure is obtained after optimization;

[0060] Then according to the design requirements, the strength and displacement of the final robot leg structure obtained after optimization are checked to ensure that the deformation of the leg structure is within the safe range and no fracture occurs under the maximum load, that is, the pre-stress working condition, to determine whether it meets the requirements for the next adjustment.

[0061] Further, the pre-stress working condition is determined by the following method:

[0062] The motion trajectory of the amphibious crawling bionic robot is planned under the diagonal gait and the tripedal gait respectively, and the simulation motion is carried out according to the planned motion trajectory and the corresponding gait;

[0063] The stress condition of the foot bottom of the leg structure of the amphibious crawling bionic robot in the simulation motion process is obtained;

[0064] The maximum stress working condition of the foot bottom in the simulation motion process is selected as the pre-stress working condition; wherein the maximum stress working condition includes the stress size, stress direction of the foot bottom of the leg structure and the corresponding standing posture of the leg structure.

[0065] This embodiment proposes to first carry out simulation motion under different gait modes, and select the working condition state of the maximum stress in the simulation motion as the pre-stress working condition in the lightweight optimization design process, so that the final leg structure obtained after design can meet the stiffness requirement under the maximum stress working condition, and further make the stiffness meet the normal activity requirement. Further considering the gait mode of the amphibious crawling bionic robot, the diagonal gait and the tripedal gait are proposed.

[0066] Specifically, according to the different gait corresponding to the robot, the robot is modeled as a single rigid body model controlled by the foot end contact force, the gait sequence is optimized based on the ifopt nonlinear optimization software using continuous decision variables, the robot motion planning is generated, and the working condition data is further obtained.

[0067] That is, the motion trajectory planning specifically includes: constructing a single rigid body model according to the configuration and mass of the amphibious crawling bionic robot; setting parameters such as the starting point, end point, gait mode of robot motion; constructing the initial motion trajectory of the robot body and foot end using the set parameters; adding kinematic and dynamic constraints to the body and foot end motion trajectory to construct a nonlinear optimization problem; using ifopt nonlinear optimization software to solve, obtaining the optimized body and foot end motion trajectory. Through the optimization and solution of the motion trajectory, the trajectory that meets the kinematic and dynamic constraints and is closer to the real motion can be obtained, making the acquisition of working condition data more reliable.

[0068] Specifically, the working condition data of the robot leg under diagonal gait and three-legged gait is obtained:

[0069] The robot is modeled using a single rigid body model, the number of legs and feet, and the offset of the legs and feet relative to the center of mass of the body are set; the inertia matrix of the body and the foot movement space, as well as the gait parameters, are set; the coordinates of the starting point and the end point of the robot motion, as well as the attitude of the robot at the starting point and the end point are set;

[0070] According to the gait parameters, the leg and foot movement is decomposed into a motion sequence composed of support phase and swing phase, the center of mass and foot end motion trajectory is initialized, and kinematic and dynamic constraints are added; the duration of the foot end support phase and swing phase is optimized using ifopt nonlinear optimization, so that the center of mass and foot end motion trajectory meet the kinematic and dynamic constraints;

[0071] The center of mass and foot end motion trajectory are output, and the force and attitude data of the robot leg structure in the working condition are obtained.

[0072] The motion trajectory planning of the amphibious crawling bionic robot under diagonal gait and three-legged gait also includes: the motion trajectory planning of the robot under diagonal gait and three-legged gait is performed according to multiple motion speeds, so as to more comprehensively obtain the force condition.

[0073] In some specific embodiments, for the lightweight design of the leg structure of the amphibious crawling bionic robot, the preset force working condition specifically is: the standing height of the leg structure is 0.16-0.20m, the force of the foot end of the leg structure in two horizontal directions is 45-60N and 18-30N, and the force in the vertical direction is 660-700N;

[0074] The preset constraint condition is specifically that the driving assembly is provided as a fixed constraint surface. The single leg is mainly connected to the body through the first joint motor 1, and the upper and lower surfaces of the first joint motor 1 are provided with corresponding bolt connection hole positions, so that the side of the first joint motor 1 close to the output shaft, i.e., close to the 1-2 motor connecting piece, is provided as a fixed constraint surface.

[0075] Further, the lightweight leg structure model is subjected to strength checking, specifically including:

[0076] The lightweight leg structure model is subjected to finite element analysis under the preset stress working condition and the preset constraint condition, to obtain strain information of the leg structure surface, and whether the strength requirement is met is determined according to the strain information. If the surface strain information is within the preset threshold range, it is considered that the strength requirement is met, and if it exceeds the preset threshold range, it needs to be redesigned.

[0077] Further, the software for establishing the leg structure entity model includes the Solidworks three-dimensional software.

[0078] In some specific embodiments, the length of the thigh, i.e., the distance between the output shaft of the third joint motor 3 and the rotating shaft of the driven wheel, is 180-220 mm; for example, it can be 200 mm. The initial thickness of the inner thigh plate 6 and the outer thigh plate 7 is 4-6 mm; for example, it can be 5 mm. The length of the calf, i.e., the distance between the calf rotating shaft and the foot bottom, is 180-220 mm; for example, it can be 200 mm.

[0079] The materials of the inner thigh plate 6, the outer thigh plate 7, the calf bone 10, the 1-2 motor connecting piece, the 2-3 motor connecting piece, the ball foot base 11, and the belt tensioner 9 are aluminum alloy 5454.

[0080] The design space is the outer thigh, the inner thigh, and the calf.

[0081] The stress condition and the constraint condition are set according to the extreme working condition, i.e., when the robot standing height is 0.182 m, the tripod gait, and the movement speed is 0.5 m / s, the specific foot end stress is 52.4115 N along the x direction, 24.4803 N along the y direction, and 685.7389 N along the z direction.

[0082] The grid structure related parameters are set according to the default data and the actual situation, the mass target is set to be 80% of the total volume of the design space, and the frequency constraint is set to be none.

[0083] The present application aims at the deficiency of the existing robot leg structure that the self weight is large, which affects its performance, and discloses a lightweight design method of amphibious crawling bionic robot leg lattice filling structure, comprising: establishing an initial model of the robot leg structure; performing hole opening, hole expansion and reduction design on the local positions of the thigh and the lower leg to obtain a preliminarily designed leg structure; obtaining the working condition data of the robot leg under diagonal gait and tripedal gait respectively; importing the preliminarily designed leg structure into the Inspire software, setting the design space after checking whether the connection is correct, setting the load working condition and the boundary constraint condition; running optimization, selecting the grid structure, setting the optimization target as the maximum stiffness, setting the related parameters, and obtaining the final optimized robot leg structure; checking the displacement and the strength of the final structure to achieve the lightweight target of weight reduction and ensure the stiffness and manufacturability; reducing the weight of the leg and improving the manufacturing economy of the robot.

[0084] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A leg structure for an amphibious reptile biomimetic robot, characterized in that, The device includes a drive assembly, a thigh assembly, a transmission assembly, a lower leg assembly, and a foot assembly. The thigh assembly includes an inner thigh plate and an outer thigh plate disposed opposite to each other. The first ends of the inner thigh plate and the outer thigh plate are respectively connected to the drive assembly and can rotate integrally under the drive of the drive assembly. The lower leg assembly includes a shinbone, the top of which is rotatably connected between the second ends of the inner thigh plate and the outer thigh plate. The transmission assembly is disposed between the inner thigh plate and the outer thigh plate, and is drively connected between the drive assembly and the shinbone, and can drive the shinbone to rotate under the drive of the drive assembly. The foot assembly is connected to the bottom of the shinbone. The inner thigh plate, the outer thigh plate, and the shinbone are configured with a dot matrix structure. The leg structure of the amphibious reptile biomimetic robot is designed based on a lightweight design method, which includes: Design the shape and size of the leg structure to obtain an initial leg structure model; The initial leg structure model is subjected to reduction holes to obtain a reduced leg structure model; Under preset stress conditions and preset constraints, the structure of the inner thigh plate, the outer thigh plate, and the tibia is designed with lattice filling to maximize stiffness in the reduced leg structure model, thereby obtaining a lightweight leg structure model. The lightweight leg structure model was subjected to strength verification, and the lightweight design was completed after verification.

2. The amphibious reptile biomimetic robot leg structure as described in claim 1, characterized in that, The drive assembly includes a first joint motor, a second joint motor, and a third joint motor. The first joint motor is connected to the robot body. The output end of the first joint motor is connected to the second joint motor through a first motor connector. The output end of the second joint motor is connected to the third joint motor through a second motor connector. The output end of the third joint motor is connected to the transmission assembly. The second joint motor and the third joint motor are coaxial. The second joint motor is used to drive the thigh assembly to perform leg raising and retracting movements. The third joint motor is used to drive the lower leg assembly to perform leg raising and retracting movements.

3. The amphibious reptile biomimetic robot leg structure as described in claim 1, characterized in that, The transmission assembly is a synchronous belt assembly, which includes a drive pulley, a driven pulley, and a transmission belt. The drive pulley is rotatably connected to the first end of the thigh assembly and connected to the drive assembly. The driven pulley is rotatably connected to the second end of the thigh assembly and is integrally rotatably connected to the shinbone. The transmission belt is tensioned on the outside of the drive pulley and the driven pulley.

4. The amphibious reptile biomimetic robot leg structure as described in claim 3, characterized in that, The synchronous belt assembly also includes a belt tensioner. The inner thigh plate and the outer thigh plate are respectively provided with bosses on opposite sides. The belt tensioner is disposed on the bosses and is used to tension the transmission belt.

5. The amphibious reptile biomimetic robot leg structure as described in claim 3, characterized in that, The inner thigh plate is connected to the drive assembly on one side of the drive wheel, and the first end of the outer thigh plate is connected to an arc-shaped connecting plate. The outer thigh plate is connected to the drive assembly on the other side of the drive wheel through the arc-shaped connecting plate. The shinbone includes two shin plates arranged opposite each other and a reinforcing plate connecting the two shin plates.

6. The amphibious reptile biomimetic robot leg structure as described in claim 1, characterized in that, The foot assembly includes a ball-foot base and a ball-foot sleeve. The top of the ball-foot base is connected to the bottom of the tibia. The bottom of the ball-foot base is spherical. The ball-foot sleeve is fitted over the ball-foot base.

7. The amphibious reptile biomimetic robot leg structure as described in claim 1, characterized in that, The preset stress condition is determined by the following method: The motion trajectory of the amphibious reptile biomimetic robot was planned in diagonal gait and triped gait respectively, and the robot was simulated to move according to the planned motion trajectory and corresponding gait. To obtain the force conditions of the foot sole of the leg structure of an amphibious reptile during simulated movement; The maximum force condition of the foot during simulated movement was selected as the preset force condition. The maximum stress conditions include the magnitude and direction of the force on the sole of the foot and the corresponding standing posture of the leg structure.

8. The amphibious reptile biomimetic robot leg structure as described in claim 7, characterized in that, The preset stress conditions are as follows: the standing height of the leg structure is 0.16-0.20m, the force on the foot end of the leg structure is 45-60N and 18-30N in the two horizontal directions, and 660-700N in the vertical direction. The preset constraint condition is specifically: setting the driving component as a fixed constraint surface.

9. The amphibious reptile biomimetic robot leg structure as described in claim 1, characterized in that, The lightweight leg structure model was subjected to strength verification, specifically including: Finite element analysis is performed on the lightweight leg structure model under preset stress conditions and preset constraints to obtain strain information on the surface of the leg structure, and the strength requirements are determined based on the strain information.

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