Bionic frog and control method thereof

Abstract

The invention belongs to the technical field of bionic robots, and particularly discloses a bionic frog and a control method thereof. The front leg mechanisms are symmetrically arranged on the lower side of the frog body front position; the rear leg mechanisms are symmetrically arranged on the lower side of the rear position of the frog body and are connecting rod mechanisms; the driving mechanism is arranged in a body cavity on the inner side of the frog body and comprises a driving motor, a driving gear and a reduction gear assembly, and the driving motor is arranged on the outer side of a side wall plate of the frog body; the driving gear is arranged at the driving end of the driving motor and meshed with the reduction gear assembly, and the bionic frog is arranged between the two symmetrically-arranged side wall plates through the reduction gear assembly and used in cooperation with the rear leg mechanism; through the structural design of the rear leg mechanism and the driving mechanism, the transmission efficiency of the frog in the jumping process can be effectively guaranteed, meanwhile, the stability of the frog in the jumping process is guaranteed, and the problem that in the background technology, the transmission efficiency and stability of an existing bionic frog in the jumping process are poor is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of bionic robots, and in particular to a bionic frog and a control method thereof. Background Art

[0002] At present, the scope of use of robots is getting wider and wider. With the expansion of its application field, the places where robots are used are also constantly enriched, and there are higher requirements for their range of movement. Faced with harsh environments and complex terrains, robots are required to have strong autonomous movement capabilities, survival capabilities and high movement flexibility. Wheeled or tracked robots and bionic crawling or walking robots are the main objects of research on autonomous mobile robots. However, wheeled or tracked robots are only suitable for working on relatively flat ground, and their movement performance on uneven ground is greatly weakened; in addition, walking or crawling robots have many degrees of freedom, complex control, slow movement and other disadvantages, and they also cannot meet the needs of obstacle crossing. In many practical applications of robots, they are required to have the ability to jump over obstacles or ditches. However, multi-wheel drive and crawling robots cannot meet this requirement. Therefore, it is urgent to develop a bouncing robot that can cross building stairs, gravel and even forests and deserts, thereby greatly improving the range of activities of the robot. Compared with other types of mobile robots, bouncing robots can easily jump over obstacles or ditches that are several times or even dozens of times larger than themselves, and are more suitable for complex and unpredictable environments. In addition, the suddenness and explosiveness of the bouncing motion helps the robot avoid danger, and it also has good application prospects in archaeological exploration, military reconnaissance, and anti-terrorism activities.

[0003] Frogs, as members of the Amphibia, Anura, Ranidae, are widely distributed in various regions of my country and are well-known amphibians. The skeletal system of frogs is one of the key factors in achieving efficient jumping. The forelimb bones of frogs are mainly composed of the humerus, radius and ulna, carpal bones, metacarpal bones and phalanges, while the hindlimb bones are mainly composed of the femur, tibia and fibula, tarsus, metatarsus and phalanges. The shapes and structures of these bones are designed to meet the needs of frog jumping. Among them, the length of the humerus and radius and ulna are basically the same, and the length of the femur and tibia and fibula are basically the same. Such a structure helps to maintain the stability and force transmission of the forelimbs and hindlimbs. The phalanges and toes are bones that play a supporting role when they are in direct contact with the ground. Their shapes and structures are designed to better disperse the impact force and provide support. In addition to bones, the joints of frogs are also an important factor in their jumping ability. The forelimb joints are mainly composed of the shoulder joint, elbow joint and wrist joint, while the hindlimb joints are mainly composed of the hip joint, knee joint, ankle joint and tarsometatarsal joint. These joints can rotate within a certain range, thereby driving the skeletal activities of various parts when jumping. In particular, the shoulder joint and hip joint have three rotational degrees of freedom, which enables the frog to achieve all-round flexible movement. From the perspective of bionics, the skeletal and joint structures of frogs provide them with excellent jumping ability. Therefore, when designing a bionic robot, a bionic frog machine is designed, which can utilize the robot's bouncing function to enhance its terrain adaptation and autonomous movement capabilities, and can effectively overcome the obstacle jumping problem of the above-mentioned existing robots. After searching, patents about bionic frog robots have been disclosed, such as a bionic frog electric robot disclosed in patent number CN105292291B. The robot structure can solve the take-off and landing problems of the jumping robot through the setting of the hind leg jumping mechanism, the front leg shock absorbing mechanism, the transmission mechanism, the trunk bracket and the slider mechanism. It has good jumping performance, can adapt to different surfaces, and can cross ditches and obstacles; but when the device is in use, there are:

[0004] 1. The hind leg jumping mechanism is realized by a rocker mechanism, which has a dead point when in use, making the power transmission smoother and seriously affecting the transmission efficiency of the frog during the jump;

[0005] 2. The device is not designed with a deceleration mechanism, so it cannot effectively amplify the output torque and reduce the rotation speed when driving the hind leg jumping mechanism, which seriously affects the stability of the frog during the jumping process;

[0006] In view of the above problems, it is urgent to design a bionic frog with a simple structure and a control method thereof to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0007] In view of the above-mentioned problems, the present invention aims to provide a bionic frog and a control method thereof. Through the structural design of the hind leg mechanism and the driving mechanism, the transmission efficiency of the frog during the jumping process can be effectively guaranteed, while the stability of the frog during the jumping process can be guaranteed, thereby effectively solving the problems of poor transmission efficiency and stability of the existing bionic frog during the jumping process in the background technology.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides a first solution: a bionic frog, comprising

[0010] frog body;

[0011] The front leg mechanism is symmetrically arranged on the lower side of the front part of the frog body;

[0012] The hind leg mechanism is symmetrically arranged on the lower side of the rear part of the frog body and is a connecting rod mechanism;

[0013] The driving mechanism is arranged in the inner body cavity of the frog body, and includes a driving motor, a driving gear and a reduction gear assembly. The driving motor is arranged on the outer side of the side wall plate of the frog body; the driving gear is arranged at the driving end of the driving motor and meshes with the reduction gear assembly. The reduction gear assembly is arranged between two symmetrically arranged side wall plates and is used in conjunction with the hind leg mechanism.

[0014] Preferably, the rear leg mechanism comprises

[0015] A boom connecting rod, one end of which is fixedly connected to the reduction gear assembly;

[0016] A driven connecting rod, one end of which is rotatably connected to the side wall plate, and the other end of which is rotatably connected to the boom connecting rod, and is arranged parallel to the boom connecting rod;

[0017] The middle shaft connecting rod is rotatably connected with the big arm connecting rod and the driven connecting rod respectively;

[0018] A small arm connecting rod, one end of which is rotatably connected to the big arm connecting rod, and the other end of which is rotatably connected to the take-off support connecting rod;

[0019] The take-off support connecting rod has one end rotatably connected to the middle axis connecting rod, and the other end connected to the frog's rear foot plate.

[0020] Preferably, a torsion spring is provided at the connection between the boom connecting rod and the driven connecting rod, and one end of the torsion spring is fixedly connected to the boom connecting rod, and the other end is fixedly connected to the driven connecting rod.

[0021] Preferably, a synchronous driving connecting rod is also provided at the connection between the forearm connecting rod and the take-off support connecting rod.

[0022] Preferably, the reduction gear assembly is an incomplete gear two-stage reduction mechanism, comprising

[0023] A first mounting rod is arranged between the two side wall plates, a first reduction gear set and a driven large gear are arranged on the first mounting rod, and the first mounting rod is fixedly connected to the large arm connecting rod;

[0024] The second mounting rod is arranged between the two side wall plates, and the first reduction gear group and the second reduction gear group are arranged on the second mounting rod, the first reduction gear group arranged on the second mounting rod is meshed with the driving gear and the first reduction gear group arranged on the first mounting rod; and is meshed with the first reduction gear group arranged on the first mounting rod and the second reduction gear group arranged on the second mounting rod, and the second reduction gear group is meshed with the driven large gear.

[0025] Preferably, the first reduction gear group and the second reduction gear group both include a high-speed large gear, the first reduction gear group also includes a high-speed small gear, and the second reduction gear group also includes an incomplete gear; the high-speed large gear is meshed with the driving gear and the high-speed small gear at an adjacent position, and the incomplete gear is meshed with the driven large gear.

[0026] The present invention provides a second solution: a control method of a bionic frog, comprising:

[0027] Step 1. Analyze the frog's movement mechanism;

[0028] Step 2. Model and analyze the frog's legs based on the frog's movement mechanism;

[0029] Step 3. Based on the analysis results of step 2, model and analyze the robot jumping process.

[0030] Preferably, the frog leg modeling and analysis process described in step 2 includes:

[0031] Step 21. Establish a frog-like robot mechanism model;

[0032] Step 22. According to the mechanism coordinate change method in the frog-like robot mechanism model, the absolute position vector of the center of mass of each connecting rod is obtained. The vector set consisting of the centroid vector;

[0033] Step 23. Establish a total center of mass position model of the frog-like robot according to the vector set formed by the center of mass vector;

[0034] Step 24. Calculate the total center of mass acceleration vector of the frog robot

[0035] Preferably, the modeling and analysis process of the robot jumping process described in step 3 includes:

[0036] Step 31. Establish the Lagrangian dynamic equation;

[0037] Step 32. Based on the Lagrangian dynamics equation, a kinetic energy control model of the robot system is established;

[0038] Step 33. Based on the Lagrangian dynamics equation, establish a potential energy control model of the robot system;

[0039] Step 34. Based on the Lagrangian dynamics equation, a robot completion take-off condition judgment model is established;

[0040] Step 35. Combine steps 32 to 34 to establish a robot jumping model.

[0041] The beneficial effects of the present invention are as follows: the present invention discloses a bionic frog and a control method thereof. Compared with the prior art, the present invention has the following improvements:

[0042] 1. Through the setting of the front leg mechanism and the design of the optimized connecting rod and double crank mechanism, there is no dead point in the operation of the structure, the power transmission is smoother, and the transmission efficiency of the frog during the jump is effectively improved;

[0043] 2. Through the setting of the driving mechanism, the output torque of the servo can be successfully amplified, the rotation speed is reduced, and the stability of the jumping process is greatly enhanced;

[0044] 3. A bionic frog control method was established by modeling and analyzing the frog's legs and the robot's jumping process. Experimental verification shows that this method can effectively complete obstacle avoidance and jumping tasks. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of the bionic frog of the present invention;

[0046] Figure 2 This is an installation effect diagram of the rear leg mechanism and the driving mechanism of the present invention;

[0047] Figure 3 is a side view schematic diagram of the bionic frog of the present invention;

[0048] Figure 4 It is a driving principle diagram of the driving mechanism of the present invention;

[0049] Figure 5 A top view of the driving mechanism of the present invention;

[0050] Figure 6 is a side view of the driving mechanism of the present invention;

[0051] Figure 7 It is a structural schematic diagram of the rear leg mechanism of the present invention;

[0052] Figure 8 This is a characteristic diagram of the frog structure in Example 2 of the present invention;

[0053] Fig. 9 This is a diagram of the frog-like robot mechanism model of Embodiment 2 of the present invention;

[0054] Fig.10 This is a diagram of the jumping displacement simulation of a frog model by ADAMS in Example 2 of the present invention;

[0055] Among them: Figure 1-6 In the figure, 1. frog body; 11. side wall plate; 2. front leg mechanism; 3. rear leg mechanism; 31. big arm connecting rod; 32. driven connecting rod; 33. middle axis connecting rod; 34. small arm connecting rod; 35. take-off support connecting rod; 36. driving connecting rod; 4. driving mechanism; 41. driving motor; 42. driving gear; 43. first reduction gear set; 431. high-speed large gear; 432. high-speed small gear; 44. second reduction gear set; 441. incomplete gear; 45. driven large gear; 46. first mounting rod; 47. second mounting rod; 5. power supply; 6. controller;

[0056] exist Figure 8 In the figure, (a) is a side view of the frog skeleton, (b) is a top view of the frog joints, and (c) is a diagram of the frog's hind limb muscles;

[0057] exist Fig.10 In the figure, (a) is a curve diagram of the frog's displacement along the X direction, and (b) is a curve diagram of the frog's displacement along the Y direction; DETAILED DESCRIPTION

[0058] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0059] Example 1: Refer to the attached Figure 1-7 , the present invention provides a technical solution:

[0060] A bionic frog, comprising

[0061] Frog body 1;

[0062] The front leg mechanism 2 is symmetrically arranged at the lower side of the front part of the frog body 1, and plays a buffering role during the frog's jump;

[0063] The hind leg mechanism 3 is symmetrically arranged at the lower side of the rear position of the frog body 1, and plays the role of energy storage for jumping, completing the frog's jumping process;

[0064] The driving mechanism 4 is arranged in the inner body cavity of the frog body 1 and is used in conjunction with the hind leg mechanism 3 to drive the hind leg mechanism 3 to move and complete the frog jumping operation.

[0065] As a preferred embodiment, Figure 1 As shown, the frog body 1 shell takes advantage of the light-curing printing technology to achieve excellent surface quality and extremely high dimensional accuracy.

[0066] As a preferred embodiment, Figure 1 As shown, in the frog structure, this embodiment selects carbon fiber material to create the leg structure to ensure its durability; the middle axis part is made of aluminum to provide stable support for the overall structure; as for the feet, this embodiment uses TPU film, which is flexible and has a certain elasticity, so that the frog's feet can be softer when contacting the ground, providing sufficient friction and cushioning capacity to ensure stable landing and take-off.

[0067] As a preferred embodiment, Figure 2 , Figure 3 , Figure 4 and Figure 7 As shown, the rear leg mechanism 3 is an optimized connecting rod mechanism, including

[0068] A boom connecting rod 31, one end of which is fixedly connected to the driving mechanism 4, and the boom connecting rod 31 is driven to rotate by the driving mechanism 4;

[0069] A driven connecting rod 32, one end of which is rotatably connected to the side wall plate 11 of the frog body 1, and the other end of which is rotatably connected to the boom connecting rod 31, and is arranged parallel to the boom connecting rod 31;

[0070] The middle shaft connecting rod 33 is rotatably connected to the big arm connecting rod 31 and the driven connecting rod 32 respectively;

[0071] A small arm connecting rod 34, one end of which is rotatably connected to the big arm connecting rod 31, and the other end of which is rotatably connected to the take-off support connecting rod 35;

[0072] A take-off support link 35, one end of which is rotatably connected to the middle axis link 33, and the other end of which is connected to the frog's rear foot plate;

[0073] When in use, the driving mechanism 4 drives the upper arm connecting rod 31 to rotate. When the upper arm connecting rod 31 rotates, the driven connecting rod 32, the middle axis connecting rod 33 and the small arm connecting rod 34 drive the driven connecting rod 32, the middle axis connecting rod 33, the small arm connecting rod 34 and the take-off support connecting rod 35 to move together, complete the extension and energy storage of the rear leg mechanism 3, simulate the leg contraction and explosive action of the frog when running, simulate the frog's jumping force, and thus achieve a powerful jump.

[0074] As a preferred embodiment, Figure 2 , Figure 3 and Figure 4As shown, in order to facilitate resetting and minimize the size and weight of the frog, the present embodiment adopts a hidden torsion spring design, that is, a torsion spring is provided at the connection between the upper arm connecting rod 31 and the driven connecting rod 32, and one end of the torsion spring is fixedly connected to the upper arm connecting rod 31, and the other end is fixedly connected to the driven connecting rod 32.

[0075] As a preferred implementation scheme, in order to realize the linkage effect of the two hind leg mechanisms 3 symmetrically arranged on the left and right, a synchronous driving link 36 is also provided at the connection between the forearm connecting rod 34 and the take-off support connecting rod 35. The two hind leg mechanisms symmetrically arranged on the left and right sides are connected by the driving link 36, so that they can move in linkage under the driving action of the driving mechanism 4 to realize the overall jumping of the frog.

[0076] As a preferred implementation scheme, in the design of the rear leg mechanism 3, this embodiment uses carbon fiber material to finely manufacture the leg frame to ensure that it has high strength and lightweight characteristics; after strict cutting, molding and assembly processes, high-precision structure of the legs is achieved; in order to facilitate the flexible movement of the legs, the connecting rods of this embodiment are connected by bolts to ensure the stability and reliability of the connection.

[0077] As a preferred embodiment, Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, in order to facilitate driving the hind leg mechanism 3 to move and realize the frog jumping, the driving mechanism 4 is designed to include

[0078] A driving motor 41 is fixedly arranged on the outside of the side wall plate 11;

[0079] The driving gear 42 is arranged at the driving end of the driving motor 41 and meshes with the reduction gear assembly, and the driving motor 41 drives the driving gear 42 to rotate;

[0080] The reduction gear assembly is disposed between two symmetrically disposed side wall plates 11 and connected to the arm connecting rod 31 disposed outside the side wall plates 11 .

[0081] As a preferred embodiment, Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the reduction gear assembly is an incomplete gear two-stage reduction mechanism, including

[0082] A first mounting rod 46 is disposed between the two side wall plates 11, and a first reduction gear set 43 and a driven large gear 45 are disposed on the first mounting rod 46, the driven large gear 45 is fixedly connected to the first mounting rod 46, and the first mounting rod 46 is fixedly connected to the large arm connecting rod 31, and the large arm connecting rod 31 is driven to rotate by the first mounting rod 46 when in use;

[0083] The second mounting rod 47 is arranged between the two side wall plates 11, and the first reduction gear group 43 and the second reduction gear group 44 are arranged on the second mounting rod 47. The first reduction gear group 43 arranged on the second mounting rod 47 is meshed with the driving gear 42, and is meshed with the first reduction gear group 43 arranged on the first mounting rod 46; and the first reduction gear group 43 arranged on the first mounting rod 46 is also meshed with the second reduction gear group 44 arranged on the second mounting rod 47, and the second reduction gear group 44 is meshed with the driven large gear 45; that is, when in use, the driven large gear 45 is driven to rotate by the driving motor 41.

[0084] As a preferred embodiment, Figure 4 and Figure 5 As shown, the first reduction gear group 43 and the second reduction gear group 44 both include a high-speed large gear 431, the first reduction gear group 43 also includes a high-speed small gear 432, and the second reduction gear group 44 also includes an incomplete gear 441; wherein, the high-speed large gear 431 is meshed with the driving gear 42 and the high-speed small gear 432 at the adjacent position, and the incomplete gear 441 is meshed with the driven large gear 45 to form a linkage drive mechanism.

[0085] As a preferred embodiment, Figure 4 and Figure 5 As shown, the number of teeth of the high-speed large gear 431 and the driven large gear 45 is 32, and the number of teeth of the high-speed small gear 432 is 16. This design successfully amplifies the output torque of the servo by 4 times, reduces the rotation speed, and greatly enhances the stability of the jumping process.

[0086] As a preferred embodiment, Figure 1 and Figure 2 As shown, the bionic frog further includes a power supply 5 , which is connected to the driving motor 41 for supplying power to the driving motor 41 .

[0087] As a preferred embodiment, Figure 1 and Figure 2 As shown, the bionic frog also includes a controller 6, which uses ESP32-S3 as a main control chip and uses a Bluetooth module to allow a mobile phone to remotely control the movement of the drive motor 41.

[0088] Example 2: Refer to the attached Figure 8-Figure 10 The present invention provides another technical solution: a control method of a bionic frog, comprising:

[0089] Step 1. Analyze the frog's movement mechanism

[0090] Step 11. Analyze the structural characteristics of the frog

[0091] The analysis of the frog's movement mechanism is based on the clarification of the frog's body structure. The frog's structural characteristics will be explained from the two aspects of bones and muscles. The frog's body can be divided into three parts: forelimbs, trunk and hind limbs, among which the forelimbs and hind limbs are the focus of structural characteristics analysis.

[0092] The skeletal system of a frog is one of the key factors in achieving efficient jumping. The forelimb skeleton of a frog is mainly composed of the humerus, radius and ulna, carpal bones, metacarpal bones and phalanges, while the hindlimb skeleton is mainly composed of the femur, tibia and fibula, tarsus, metatarsal bones and phalanges. The shapes and structures of these bones are designed to meet the needs of frog jumping; among them, the humerus and radius and ulna are basically the same length, and the femur and tibia and fibula are basically the same length. This structure helps to maintain the stability and force transmission of the forelimbs and hindlimbs. The phalanges and toes are bones that play a supporting role when in direct contact with the ground. Their shapes and structures are designed to better disperse the impact force and provide support. The side view of the bones is shown below. Figure 8 (a); In addition to bones, frog joints are also an important factor in their jumping ability. The forelimb joints are mainly composed of shoulder joints, elbow joints and wrist joints, while the hind limb joints are mainly composed of hip joints, knee joints, ankle joints and tarsometatarsal joints. These joints can rotate within a certain range, thereby driving the movement of bones in various parts when jumping. In particular, the shoulder joint and hip joint have three degrees of rotational freedom, which enables frogs to achieve full-range flexible movement. The top view of the joints is shown in the figure. Figure 8 (b) as shown.

[0093] From the perspective of bionics, the skeletal and joint structures of frogs provide them with excellent jumping abilities. In the subsequent design of frog-like jumping robots, we need to fully consider and imitate the characteristics of these structures to ensure the stability and flexibility of the robot. Through the study of frog bones and joints, we can provide more inspiration and ideas for the design of bionic robots. In jumping movements, the forelimbs and hindlimbs of frogs play different roles. The forelimbs are mainly used to support the body, while the hindlimbs are the main parts that drive the jumping movement and ensure the jumping movement. Therefore, when analyzing frog muscles, we mainly focus on the hindlimb muscles; the hindlimb muscles are mainly composed of the gluteal muscles, semimembranosus muscles, biceps femoris and gastrocnemius muscles, such as Figure 8(c) These muscles work together when the frog jumps, allowing the frog to contract and release in an instant to complete the jump. The characteristics of this muscle make the frog's jump sudden and explosive.

[0094] The gluteal muscle is the largest muscle in a frog's hind limb, connecting the frog's pelvis and thigh bone. The gluteal muscle is responsible for generating force that allows the frog to push its body upward when jumping. The semimembranosus muscle connects the thigh bone to the shin bone and its main function is to stabilize the knee joint and prevent the knee from bending too much when jumping. The biceps femoris is located in the back of the thigh and its main function is to bend the shin bone, allowing the frog to push its foot off the ground. The gastrocnemius muscle connects the shin bone to the ankle and is responsible for bending the sole of the foot, helping the frog to maintain balance when landing after a jump. The muscles of a frog work together to make their jumping movements both fast and powerful. This characteristic gives frogs an advantage when catching prey or escaping predators. For example, a frog can easily jump across a wide body of water or escape a fast-moving predator. This suddenness and explosiveness makes frogs an agile animal that can survive and thrive in a variety of environments.

[0095] By simplifying the skeletal structure of the frog's hind legs and analyzing the principle of jumping, we designed a frog-like jumping robot based on the frog structure.

[0096] Step 2. Modeling and analyzing the frog legs

[0097] Step 21. Build a frog-like robot mechanism model

[0098] A Cartesian coordinate system is set up, with a specific point O on the ground as the starting point, the horizontal direction is defined as the X axis, and the vertical direction is defined as the Y axis. During the robot's jump, it rotates around the top point A of the toe, and configures the coordinate system for the lower joint according to the DH rule, as detailed in Figure 2 . Define the distance from the origin O to point A as l A , the size of the connecting rod n is l n 、Mass m n , and the moment of inertia are I n (n=1,2,3,4), the center of mass of each connecting rod is denoted by c n , the joint angle between adjacent links is The angle between the connecting rod and the ground is denoted by θ n , the positive direction is defined as counterclockwise. The following relationship is followed:

[0099]

[0100] The relationship between the center of mass vector of each link and the absolute position of the overall center of mass is expressed by defining the direction cosine matrix:

[0101]

[0102] Step 22. Using the principle of coordinate transformation, we can derive the absolute position vectors of the center of mass of each connecting rod, which are defined by formula (3).

[0103]

[0104] Step 23. If the sum of the masses of all the robot's links is set to m, then

[0105] The position of the overall center of mass can be expressed by formula (4).

[0106]

[0107] By substituting the vector values ​​in formula (3) into formula (4), the expression of the total center of mass position can be derived, namely formula (5).

[0108]

[0109] Step 24. The motion variables θ of each joint of the robot n(t) As the time variable t changes, the direction cosine matrix G composed of these variables on It also changes with time t; by differentiating formula (5) with respect to time t, we can obtain the absolute velocity vector of the total center of mass: It is expressed as formula (6).

[0110]

[0111] The total center of mass velocity as a function depends on the generalized variable θ and its time derivative. By differentiating formula (6) with respect to time t, we can obtain the acceleration vector of the total center of mass: As shown in formula (7).

[0112]

[0113] Step 3. Modeling and analysis of the robot jumping process

[0114] In step 2, we constructed a geometric motion model that describes the robot's take-off action and established the mathematical relationship between the joint angles and the center of mass path. In order to determine the dynamic path of the robot's center of mass under the action of elastic elements, we usually apply Lagrangian mechanics to solve this type of dynamic problem.

[0115] Step 31. Construct the dynamic equations based on Lagrangian mechanics.

[0116] (1) According to the universal equation of dynamics, the dynamic equation of the system can be expressed by Lagrangian:

[0117]

[0118] In formula (8): Lagrangian function Defined as the total kinetic energy E of the system k and the total potential energy E P The difference is T i (i=1,2,3,4) is the joint input torque;

[0119] (2) During the take-off phase of the spring-driven jumping robot, due to the lack of active input of external torque, the joint torque T on the right side of the Lagrangian equation i is the zero vector. Therefore, the focus of solving Lagrange's equations is to calculate the kinetic energy and potential energy of the system.

[0120] Step 32. Establish the kinetic energy control model of the robot system

[0121] The system kinetic energy of the robot includes the translational and rotational kinetic energy of all the links. The mechanism model has two independent degrees of freedom. We choose the angle between the sole of the foot and the ground and the angle of the ankle joint As a generalized coordinate, the kinetic energy K of the entire system is calculated p .

[0122]

[0123] According to the robot mechanism, the knee joint and the ankle joint are connected by a timing belt, and there is a specific relationship between them.

[0124]

[0125] In formula (10), Δ represents two angles The initial phase difference between the hip and ankle joints. The angles of the hip and ankle joints are restricted by the four-bar linkage. Through literature review, we get the calculation of these two angles Expression of relationship between .

[0126]

[0127] In order to reduce the complexity of the calculation and the time required for the solution, we used a cubic curve to fit the relationship between the two and obtained the following equation:

[0128]

[0129] Step 33. Establish the potential energy control model of the robot system

[0130] In the robot's take-off action, the potential energy of the system consists of two parts: gravitational potential energy E Gand the elastic potential energy E generated by the energy storage spring p .

[0131] Taking the ground as the reference zero point of gravitational potential energy, the gravitational potential energy of the system is expressed as:

[0132]

[0133] The energy storage spring is mounted on the joint axis, so the elastic potential energy of the system depends only on the selected generalized coordinates. Related, its expression is:

[0134]

[0135] In formula (14), k represents the stiffness coefficient of the spring; a and b represent the installation positions of the spring on the adjacent connecting rods, and L 0 Represents the initial length of the spring.

[0136] Step 34. Establish a model for judging the robot's take-off conditions

[0137] When the robot completes the jump, the force exerted by its feet on the ground is 0, so the conditions for judging the robot's take-off time are:

[0138]

[0139] Substituting formula (15) into formula (5), we can obtain the joint space conditions for judging the take-off action.

[0140]

[0141] That is, when the vertical acceleration of the robot's center of mass decreases to a value equal to the gravity acceleration and in the opposite direction, the robot can be considered to have completed the jump.

[0142] Step 35. Build the robot's jumping motion model.

[0143] Substituting equations (9)-(14) into equation (8), the Lagrange equation is simplified into the following form:

[0144]

[0145] G is the potential energy vector, including gravitational potential energy E G and elastic potential energy E p ;

[0146]

[0147] Step 4. Conduct a frog simulation test and perform simulation analysis on the frog simulation model established in steps 1 to 3 to verify the feasibility of the above modeling and control methods.

[0148] In order to further study the motion performance of the bionic robot, ADAMS was used to simulate and verify the jumping motion of the three-dimensional model.

[0149] Step 41. Displacement analysis

[0150] The displacement of the bionic frog's center of mass in the x and y directions is as follows: Fig.10 shown; according to Figure 3 It can be seen that the displacement in the x-direction shows a forward trend, and the displacement in the y-direction shows an upward trend. At 0.52s, the displacement in the y-direction is zero, and the maximum displacement in the x-direction is about 2.3m.

[0151] That is, it can be seen from the above results that the frog model established by the above modeling and control method described in this embodiment can effectively complete the tasks of obstacle avoidance and jumping.

[0152] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A bionic frog, characterized in that: include frog body (1); The front leg mechanism (2) is symmetrically arranged on the lower side of the front part of the frog body (1); The hind leg mechanism (3) is symmetrically arranged on the lower side of the rear part of the frog body (1) and is a connecting rod mechanism; The driving mechanism (4) is arranged in the inner body cavity of the frog body (1), and comprises a driving motor (41), a driving gear (42) and a reduction gear assembly. The driving motor (41) is arranged outside the side wall plate (11) of the frog body (1); the driving gear (42) is arranged at the driving end of the driving motor (41) and meshes with the reduction gear assembly. The reduction gear assembly is arranged between two symmetrically arranged side wall plates (11) and is used in conjunction with the hind leg mechanism (3).

2. A bionic frog according to claim 1, characterized in that: The rear leg mechanism (3) comprises A boom connecting rod (31), one end of which is fixedly connected to the reduction gear assembly; A driven connecting rod (32), one end of which is rotatably connected to the side wall plate (11), and the other end of which is rotatably connected to the boom connecting rod (31), and is arranged parallel to the boom connecting rod (31); The middle shaft connecting rod (33) is rotatably connected to the big arm connecting rod (31) and the driven connecting rod (32) respectively; A small arm connecting rod (34), one end of which is rotatably connected to the large arm connecting rod (31), and the other end of which is rotatably connected to the take-off support connecting rod (35); A take-off support connecting rod (35) has one end rotatably connected to the center axis connecting rod (33) and the other end connected to the frog rear foot plate.

3. A bionic frog according to claim 2, characterized in that: A torsion spring is provided at the connection between the boom connecting rod (31) and the driven connecting rod (32), and one end of the torsion spring is fixedly connected to the boom connecting rod (31), and the other end is fixedly connected to the driven connecting rod (32).

4. A bionic frog according to claim 2, characterized in that: A synchronous driving connecting rod (36) is also provided at the connection between the forearm connecting rod (34) and the take-off supporting connecting rod (35).

5. The bionic frog according to claim 2, characterized in that: The reduction gear assembly is an incomplete gear two-stage reduction mechanism, comprising A first mounting rod (46) is arranged between the two side wall plates (11), a first reduction gear set (43) and a driven large gear (45) are arranged on the first mounting rod (45), and the first mounting rod (46) is fixedly connected to the large arm connecting rod (31); The second mounting rod (47) is arranged between the two side wall plates (11), and a first reduction gear set (43) and a second reduction gear set (44) are arranged on the second mounting rod (47). The first reduction gear set (43) arranged on the second mounting rod (47) is meshed with the driving gear (42) and the first reduction gear set (43) arranged on the first mounting rod (46); and is meshed with the first reduction gear set (43) arranged on the first mounting rod (46) and the second reduction gear set (44) arranged on the second mounting rod (47). The second reduction gear set (44) is meshed with the driven large gear (45).

6. The bionic frog according to claim 5, characterized in that: The first reduction gear set (43) and the second reduction gear set (44) both include a high-speed large gear (431), the first reduction gear set (43) also includes a high-speed small gear (432), and the second reduction gear set (44) also includes an incomplete gear (441); the high-speed large gear (431) is meshed with the driving gear (42) and the high-speed small gear (432) at an adjacent position, and the incomplete gear 9441 is meshed with the driven large gear (45).

7. A control method for a bionic frog as claimed in any one of claims 1 to 6, characterized in that: include Step 1. Analyze the frog's movement mechanism; Step 2. Model and analyze the frog's legs based on the frog's movement mechanism; Step 3. Based on the analysis results of step 2, model and analyze the robot jumping process.

8. A control method for a bionic frog as claimed in claim 7, characterized in that: The frog leg modeling and analysis process described in step 2 includes: Step 21. Establish a frog-like robot mechanism model; Step 22. According to the mechanism coordinate change method in the frog-like robot mechanism model, the absolute position vector of the center of mass of each connecting rod is obtained. The vector set consisting of the centroid vector; Step 23. Establish a total center of mass position model of the frog-like robot according to the vector set formed by the center of mass vector; Step 24. Calculate the total center of mass acceleration vector of the frog robot 9. A control method for a bionic frog as claimed in claim 7, characterized in that: The modeling and analysis process of the robot jumping process described in step 3 includes: Step 31. Establish the Lagrangian dynamic equation; Step 32. Based on the Lagrangian dynamics equation, a kinetic energy control model of the robot system is established; Step 33. Based on the Lagrangian dynamics equation, establish a potential energy control model of the robot system; Step 34. Based on the Lagrangian dynamics equation, a robot completion take-off condition judgment model is established; Step 35. Combine steps 32 to 34 to establish a robot jumping model.

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