Bionic frog leg structure based on multi-connecting-rod mechanism

Abstract

The invention provides a bionic frog leg structure based on a multi-connecting-rod mechanism, and belongs to the field of bionic frog leg structures, the bionic frog leg structure comprises two groups of bilaterally symmetrical multi-connecting-rod rear leg mechanisms, each multi-connecting-rod rear leg mechanism comprises a driving connecting rod R1, a frame connecting rod R2, a thighbone-imitating connecting rod R3, a connecting rod R4, a connecting rod R5, a tibiofibula-imitating connecting rod R6, a connecting rod R7, a connecting rod R8, a tarsal bone-imitating connecting rod R9, a connecting rod r6 and a connecting rod r9, one end of the driving connecting rod R1 is rotationally connected to the driving end, the other end of the driving connecting rod R1 is connected to one end of the frame connecting rod R2, the other end of the frame connecting rod R2 is rotationally connected with one end of the thighbone-imitating connecting rod R3, the other end of the thighbone-imitating connecting rod R3 simulates a hip joint, one end of the tibiofibula-imitating connecting rod R6 is rotationally connected to one end of the thighbone-imitating connecting rod R3, and the other end of the tibiofibula-imitating connecting rod R6 is rotationally connected to the other end of the one end of the humanoid tarsal bone connecting rod R9 is rotationally connected with the other end of the humanoid tibiofibula connecting rod R6; the structure is simple, and miniaturization and light weight are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of bionic frog leg structures, and in particular to a bionic frog leg structure based on a multi-link mechanism. Background Art

[0002] Exploring and developing the ocean requires advanced technology and equipment. As an important carrier for humans to enter the ocean, underwater robots have received widespread attention and have developed rapidly. With the deepening of research on underwater robots, the swimming mechanisms of more and more underwater creatures have been simulated and applied to bionic robots. In the field of underwater bionic propulsion research, the research on tail fin swinging technology started early, and existing research has achieved many results in the basic analysis of the swinging mechanism and propulsion performance and its maneuverability. As early as 1985, the Shenyang Institute of Automation of the Chinese Academy of Sciences began to study underwater bionic robots, and its prototype was called Goldfish I. In 1994, Triantafyllou of the Massachusetts Institute of Technology developed the world's first bionic tuna RoboTuna. In 2014, Huang Shiming of Southwest Jiaotong University designed a fish tail swinging structure based on ADAMS (Automatic Dynamic Analysis of Mechanical Systems) simulation software. However, the fish robot will generate unbalanced lateral forces on both sides when swimming. This will cause the swimming to be not stable enough and limit the swimming speed. In 1987, Gal and Blake observed and analyzed the swimming process of frogs and divided it into two processes: extension and contraction. In 1996, Kamel et al. subdivided it into three stages: propulsion, gliding, and recovery. In 2015, Qiu Yulong of Harbin Institute of Technology designed a robot that imitates frogs based on a linkage mechanism and pneumatic muscles. However, the structure of pneumatic muscles is relatively complex, and it is still difficult to achieve the goal of lightness and miniaturization. Summary of the invention

[0003] The technical problem to be solved by the present invention is how to solve the problem that the existing bionic frog legs have a complex structure and are difficult to be miniaturized and lightweight.

[0004] The present invention solves the above technical problems through the following technical solutions: a bionic frog leg structure based on a multi-link mechanism, the structure includes two groups of multi-link hind leg mechanisms that are symmetrical on both sides, the multi-link hind leg mechanism includes a driving connecting rod R1, a frame connecting rod R2, an imitation femoral connecting rod R3, a connecting rod R4, a connecting rod R5, an imitation tibia and fibula connecting rod R6, a connecting rod R7, a connecting rod R8, an imitation tarsal connecting rod R9, a connecting rod r6, and a connecting rod r9, one end of the driving connecting rod R1 is rotatably connected to the driving end, the other end of the driving connecting rod R1 is connected to one end of the frame connecting rod R2, the other end of the frame connecting rod R2 is rotatably connected to one end of the imitation femoral connecting rod R3, the other end of the imitation femoral connecting rod R3 simulates a hip joint, one end of the connecting rod R4 is rotatably connected to one end of the connecting rod R5, and the connecting rod R The other end of link R4 is connected to the middle part of the simulated femoral link R3, the other end of link R5 is connected to the middle part of the frame link R2, one end of simulated tibia and fibula link R6 is rotationally connected to one end of simulated femoral link R3, one end of simulated tarsal link R9 is rotationally connected to the other end of simulated tibia and fibula link R6, one end of link R7 is rotationally connected to one end of link R8, the other end of link R7 is connected to the middle part of simulated femoral link R3, the other end of link R8 is connected to the middle part of simulated tibia and fibula link R6, one end of link R6 is connected to the connection point of link R4 and link R5, the other end of link R6 is connected to the middle part of simulated tibia and fibula link R6, one end of link R9 is connected to the connection point of link R7 and link R8, and the other end of link R9 is connected to the middle part of simulated tarsal link R9.

[0005] The present invention drives the driving connecting rod R1 to rotate, thereby driving the imitation femur connecting rod R3 simulating the femur of the frog's leg to rotate around the hip joint, the imitation tibia and fibula connecting rod R6 simulating the tibia and fibula of the frog's leg completes knee extension and knee flexion swing around the knee joint under the tension of the connecting rods R4 and R5, and the imitation tarsal connecting rod R9 simulating the tarsal of the frog's leg swings around the ankle joint under the tension of the connecting rods R7 and R8. The bionic frog leg structure based on the multi-link mechanism only needs to drive the driving connecting rod R1 to drive the bionic frog leg structure to simulate the entire movement process of extension, sliding and contraction. The structure is simple, and the multi-link mechanism replaces the pneumatic muscle, which can greatly reduce the weight of the bionic frog leg structure and realize miniaturization and lightweight design.

[0006] Preferably, the driving connecting rod R1 rotates around the connection point with the driving end, driving the simulated femoral connecting rod R3 to rotate around the hip joint, the simulated tibiofibular connecting rod R6 completes knee extension and knee flexion swing under the tension of the connecting rods R4 and R5, and the simulated tarsal connecting rod R9 swings under the tension of the connecting rods R7 and R8.

[0007] Preferably, the driving connecting rod R1, the frame connecting rod R2, and the artificial femoral connecting rod R3 form a crank rocker mechanism, and the driving connecting rod R1 rotates 360 degrees around the connection point between it and the driving end.

[0008] Preferably, the driving end includes a motor and two meshing gears, the two gears are respectively connected to the driving connecting rods R1 in the two sets of multi-link rear leg mechanisms, and one of the gears is connected to the output end of the motor.

[0009] Preferably, the ratio of the length of the simulated femoral connecting rod R3, the length of the simulated tibia and fibula connecting rod R6, and the length of the simulated tarsal connecting rod R9 is 3:3:2, and the length variation of each part is within ±5%.

[0010] Preferably, the sum of the length of the driving connecting rod R1 and the length of the artificial femoral connecting rod R3 is smaller than the length of the frame connecting rod R2.

[0011] Preferably, the swing angle of the artificial femoral connecting rod R3 is negatively correlated with the length of the driving connecting rod R1 and the length of the frame connecting rod R2, respectively. The swing amplitude of the artificial femoral connecting rod R3 can be changed by controlling the length of the driving connecting rod R1 and the frame connecting rod R2.

[0012] Preferably, the angle between the simulated femoral connecting rod R3 and the simulated tibia-fibula connecting rod R6 is positively correlated with the ratio of the length of the connecting rod R4 to the length of the connecting rod R5.

[0013] Preferably, the length of the connecting rod R4, the length of the connecting rod R5, and the length of the simulated tibiofibular connecting rod R6 are in a ratio of 6:3:8, and the length variation of each part is within ±5%.

[0014] Preferably, the length of the connecting rod R7, the length of the connecting rod R8, and the length of the simulated tarsal connecting rod R9 are in a ratio of 1:1.3:4.3, and the length variation of each part is within ±5%.

[0015] The advantages provided by the present invention are:

[0016] (1) The present invention drives the connecting rod R1 to rotate, thereby driving the simulated femur connecting rod R3 simulating the femur of the frog's leg to rotate around the hip joint, and the simulated tibia and fibula connecting rod R6 simulating the tibia and fibula of the frog's leg to swing around the knee joint to complete knee extension and knee flexion under the tension of the connecting rods R4 and R5. The simulated tarsal connecting rod R9 simulating the tarsal of the frog's leg swings around the ankle joint under the tension of the connecting rods R7 and R8. The bionic frog leg structure based on the multi-link mechanism only needs to drive the driving connecting rod R1 to drive the bionic frog leg structure to simulate the entire movement process of extension, sliding and contraction. The structure is simple, and the multi-link mechanism replaces the pneumatic muscle, which can greatly reduce the weight of the bionic frog leg structure and achieve a miniaturized and lightweight design.

[0017] (2) The present invention simulates the femur, tibia and fibula and tarsus of the frog's leg respectively through the simulated femoral connecting rod R3, the simulated tibia and fibula connecting rod R6 and the simulated tarsal connecting rod R9, the connecting rods R4 and R5 simulate the functions of the semimembranosus and quadriceps femoris respectively, the connecting rods R7 and R8 simulate the functions of the tibialis anterior and gastrocnemius respectively, the connecting rods r6 and r9 both simulate the tendons of the frog's leg, and the connecting rod mechanism for connecting the simulated muscles and the simulated bones is based on a simple multi-link mechanism, which not only simulates the function of the frog's skeleton, but also simulates the muscle and tendon functions by using the angle changes between the connecting rods, thereby realizing structural and functional bionics.

[0018] (3) The power mechanism composed of the driving connecting rod R1, the frame connecting rod R2 and the artificial femoral connecting rod R3 of the present invention is a crank-rocker mechanism. The crank-rocker mechanism utilizes the unique quick return characteristics to effectively shorten the time of the contraction stage and realize the rapid contraction of the bionic frog leg structure, thereby expanding the proportion of the extension and gliding stages in the periodic motion and improving the swimming efficiency of the underwater robot.

[0019] (4) The present invention installs a motor at the driving end, wherein one gear is connected to the output end of the motor. The motor drives the gear to rotate, thereby driving another meshing gear to rotate. Thus, a driving mechanism can simultaneously drive the driving connecting rods R1 on both sides of the simulated trunk connecting rod to rotate in opposite directions, thereby simultaneously driving the simulated femoral connecting rod R3, simulated tibia and fibula connecting rod R6, and simulated tarsal connecting rod R9 on both sides to move together to complete the entire movement of the frog leg structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A motion diagram of a driving connecting rod R1, a frame connecting rod R2, and a femoral connecting rod R3 in a bionic frog leg structure based on a multi-link mechanism provided in an embodiment of the present invention;

[0021] Figure 2 A motion diagram of a driving connecting rod R1, a frame connecting rod R2, a simulated femoral connecting rod R3, and a simulated tibia-fibula connecting rod R6 in a bionic frog leg structure based on a multi-link mechanism provided in an embodiment of the present invention;

[0022] Figure 3 A motion diagram of a multi-link rear leg mechanism in a bionic frog leg structure based on a multi-link mechanism provided by an embodiment of the present invention;

[0023] Figure 4 A diagram showing the corresponding relationship between the bionic frog leg structure based on a multi-link mechanism and the frog leg bones and muscles provided by an embodiment of the present invention;

[0024] Figure 5 A schematic diagram of a multi-link rear leg mechanism in a bionic frog leg structure based on a multi-link mechanism provided by an embodiment of the present invention that imitates the movement of a frog's legs;

[0025] Figure 6 The angular velocity of the femoral connecting rod R3 in the bionic frog leg structure based on the multi-link mechanism provided in the embodiment of the present invention;

[0026] Figure 7 The angular acceleration of the femoral connecting rod R3 in the bionic frog leg structure based on the multi-link mechanism provided in the embodiment of the present invention;

[0027] Figure 8 The angular velocity of the tibia-fibula connecting rod R6 in the bionic frog leg structure based on the multi-link mechanism provided in the embodiment of the present invention;

[0028] Fig. 9 The angular acceleration of the tibia-fibula connecting rod R6 in the bionic frog leg structure based on the multi-link mechanism provided in the embodiment of the present invention;

[0029] Fig.10 The angular velocity of the tarsal link R9 in the bionic frog leg structure based on the multi-link mechanism provided in the embodiment of the present invention;

[0030] Fig.11 The angular acceleration of the tarsal link R9 in the bionic frog leg structure based on the multi-link mechanism provided in the embodiment of the present invention;

[0031] Fig.12 A schematic diagram of a dynamic model of a femoral connecting rod R3, a tibia-fibula connecting rod R6, and a tarsal connecting rod R9 in a bionic frog leg structure based on a multi-link mechanism provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the technical solution of the present invention is clearly and completely described below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] like Figure 4 As shown, this embodiment provides a bionic frog leg structure based on a multi-link mechanism, including two sets of multi-link hind leg mechanisms, the two sets of multi-link hind leg mechanisms are symmetrically distributed on both sides of the symmetry axis with the trunk-like connecting rod as the symmetry axis, the trunk-like connecting rod includes two parallel rods, and a gear is fixed at the end of each rod. Figure 4The rod on the left is the first rod, and the rod on the right is the second rod. The end of the first rod is fixed with gear G1, and the end of the second rod is fixed with gear G2. Gear G1 is meshed with gear G2. By driving gear G1 or gear G2 to rotate, the other gear can be driven to rotate, thereby realizing the synchronous driving of the two sets of multi-link hind leg mechanisms, imitating the real movement state of the frog leg structure.

[0034] Continue reading Figure 4 The multi-link hind leg mechanism includes a driving connecting rod R1, a frame connecting rod R2, a simulated femoral connecting rod R3, a connecting rod R4, a connecting rod R5, a simulated tibia and fibula connecting rod R6, a connecting rod R7, a connecting rod R8, a simulated tarsal connecting rod R9, a connecting rod r6, and a connecting rod r9. One end of the driving connecting rod R1 is rotationally connected to the output end of the gear G1, and the other end of the driving connecting rod R1 is connected to one end of the frame connecting rod R2. The other end of the frame connecting rod R2 is rotationally connected to one end of the simulated femoral connecting rod R3. The other end of the simulated femoral connecting rod R3 is rotationally connected to the end of a rod in the simulated trunk connecting rod, and the end of the rod simulates the hip joint of the frog's leg. One end of the connecting rod R4 is rotationally connected to one end of the connecting rod R5. The other end of the connecting rod R4 is connected to the middle part of the simulated femoral connecting rod R3. The other end of the connecting rod R5 is connected to the middle part of the frame connecting rod R2. One end of the connecting rod R6 is rotationally connected to one end of the simulated femoral connecting rod R3, the node where the simulated tibia-fibula connecting rod R6 and the simulated femoral connecting rod R3 are connected simulates the knee joint of the frog's leg, one end of the simulated tarsal connecting rod R9 is rotationally connected to the other end of the simulated tibia-fibula connecting rod R6, the node where the simulated tarsal connecting rod R9 and the simulated tibia-fibula connecting rod R6 are connected simulates the ankle joint of the frog's leg, one end of the connecting rod R7 is rotationally connected to one end of the connecting rod R8, the other end of the connecting rod R7 is connected to the middle part of the simulated femoral connecting rod R3, the other end of the connecting rod R8 is connected to the middle part of the simulated tibia-fibula connecting rod R6, one end of the connecting rod r6 is connected to the connection point of the connecting rod R4 and the connecting rod R5, the other end of the connecting rod r6 is connected to the middle part of the simulated tibia-fibula connecting rod R6, one end of the connecting rod r9 is connected to the connection point of the connecting rod R7 and the connecting rod R8, and the other end of the connecting rod r9 is connected to the middle part of the simulated tarsal connecting rod R9.

[0035] In the bionic frog leg structure based on the multi-link mechanism of the present invention, the driving connecting rod R1 in the multi-link hind leg mechanism is rotatably connected to the driving end to Figure 4 Take the multi-link rear leg mechanism on the right side as an example, see Figure 1 , driving connecting rod R1 is equivalent to a crank, driving connecting rod R1 to do a 360-degree flip motion clockwise around the right connection point. Similarly, Figure 4The multi-link hind leg mechanism on the left side drives the connecting rod R1 to perform a 360-degree flip motion counterclockwise around the left connection point. The femoral imitation connecting rod R3 is equivalent to a rocker. When the connecting rod R1 is driven to rotate, it can drive the femoral imitation connecting rod R3 to rotate around the connection point between it and a rod in the trunk imitation connecting rod, so that the connection point between the femoral imitation connecting rod R3 and the rod in the trunk imitation connecting rod can simulate the hip joint. The femoral imitation connecting rod R3 simulates the femur of the frog's leg. The tibia and fibula imitation connecting rod R6 can complete extension and contraction like the tibia and fibula under the tension of the connecting rods R4 and R5. The knee and knee flexion swing motions are realized, and the connecting rods R4 and R5 simulate the semimembranosus and quadriceps respectively, and the tibia-imitation fibula connecting rod R6 simulates the tibia and fibula of the frog's leg. During the swinging process of the tibia-imitation fibula connecting rod R6, the angle change between the femoral connecting rod R3 and the tibia-imitation fibula connecting rod R6 drives the connecting rods R7 and R8 to rotate. The tarsal connecting rod R9 swings like a flipper under the tension of the connecting rods R7 and R8. The connecting rods R7 and R8 simulate the tibialis anterior and gastrocnemius respectively, and the tarsal connecting rod R9 simulates the tarsal of the frog's leg.

[0036] The present invention drives the connecting rod R1 to rotate, thereby driving the imitation femur connecting rod R3 simulating the femur of the frog's leg to rotate around the hip joint, the imitation tibia and fibula connecting rod R6 simulating the tibia and fibula of the frog's leg completes knee extension and knee flexion swing around the knee joint under the tension of the connecting rods R4 and R5, and the imitation tarsal connecting rod R9 simulating the tarsal of the frog's leg swings around the ankle joint under the tension of the connecting rods R7 and R8. The present invention is based on the bionic frog leg structure of the multi-link mechanism, and only needs to drive the driving connecting rod R1 to drive the bionic frog leg structure to simulate the entire movement process of extension, sliding and contraction. The structure is simple, and the multi-link mechanism replaces the pneumatic muscle, which can greatly reduce the weight of the bionic frog leg structure, realize the miniaturization and lightweight design of the underwater robot structure, effectively improve the energy efficiency of the underwater robot, and lay a foundation for the development of underwater unmanned robots.

[0037] The power mechanism composed of the driving connecting rod R1, the frame connecting rod R2 and the imitation femoral connecting rod R3 is a crank-rocker mechanism. The unique quick-return characteristics of the crank-rocker mechanism are utilized to effectively shorten the time of the contraction stage and realize the rapid contraction of the bionic frog leg structure, thereby expanding the proportion of the extension and gliding stages in the periodic motion and improving the swimming efficiency of the underwater robot.

[0038] By installing a motor at the driving end, in which one gear is connected to the output end of the motor, the motor drives the gear to rotate, thereby driving another meshing gear to rotate, so that a driving mechanism can simultaneously drive the driving connecting rods R1 on both sides of the simulated trunk connecting rod to rotate in opposite directions, thereby simultaneously driving the simulated femoral connecting rod R3, simulated tibia and fibula connecting rod R6, and simulated tarsal connecting rod R9 on both sides to move together to complete the entire movement of the frog leg structure.

[0039] The proportions of the simulated femoral connecting rod R3, simulated tibia and fibula connecting rod R6, and simulated tarsal connecting rod R9 of the present invention follow the proportions of the femur, tibia and fibula, and tarsal bones of the African clawed frog, such as Fig. 9 As shown in the figure, L1, L2, and L3 respectively represent the lengths of the simulated femoral connecting rod R3, the simulated tibia and fibula connecting rod R6, and the simulated tarsal connecting rod R9, with a specific ratio of 3:3:2. The length variation of each part should be within ±5%. Figure 3 After the structure shown is imported into ADAMS software for motion simulation, the law of change of the angle between the frame connecting rod R2 and the simulated femoral connecting rod R3 as the driving connecting rod R1 rotates can be obtained. The lengths of the driving connecting rod R1, the frame connecting rod R2, and the simulated femoral connecting rod R3 satisfy the condition that the sum of the length of the driving connecting rod R1 and the length of the simulated femoral connecting rod R3 is less than the length of the frame connecting rod R2. Among the three connecting rods, the frame connecting rod R2 is the longest and the driving connecting rod R1 is the shortest.

[0040] The length of the simulated femoral connecting rod R3 is now fixed to 40 mm. The lengths of the driving connecting rod R1 and the frame connecting rod R2 are set according to the relationship satisfied by the lengths of the driving connecting rod R1, the frame connecting rod R2, and the simulated femoral connecting rod R3, as shown in Table 1. Different parameters are substituted into the connecting rod model and ADAMS simulation to obtain the angle change between the driving connecting rod R1 and the frame connecting rod R2 and the swing angle change of the simulated femoral connecting rod R3 during the movement.

[0041] Table 1 Length and angle changes of driving connecting rod R1, frame connecting rod R2, and femoral connecting rod R3

[0042]

[0043] By comparing the data of Group 1 and Group 4 in Table 1, it can be seen that the swing angle of the artificial femoral connecting rod R3 is negatively correlated with the length of the driving connecting rod R1. By comparing the data of Group 1 and Group 3 in Table 1, it can be seen that the swing angle of the artificial femoral connecting rod R3 is also negatively correlated with the length of the frame connecting rod R2. By controlling the length of the driving connecting rod R1 and the frame connecting rod R2, the swing amplitude of the artificial femoral connecting rod R3 can be flexibly changed.

[0044] After determining the parameters of the driving connecting rod R1, the frame connecting rod R2, and the simulated femoral connecting rod R3, the simulated tibia and fibula connecting rod R6, and the simulated tarsal connecting rod R9 follow the proportional relationship between the femur, tibia and fibula and tarsal bones of the African clawed frog. It can be seen that the length of the simulated femoral connecting rod R3 and the simulated tibia and fibula connecting rod R6 are the same. Taking the length of the simulated femoral connecting rod R3 as 40 mm as an example, the length of the simulated tibia and fibula connecting rod R6 is also 40 mm. By setting the lengths of the connecting rods R4 and R5, different connecting rod parameters are substituted into the ADAMS simulation software, and then the angle data is collected, and a set of experimental data closest to the ideal parameters is selected. The ideal parameters are shown in Table 2. During the experiment, it was found that the angle between the femoral connecting rod R3 and the tibia and fibula connecting rod R6 was positively correlated with the ratio of the length of the connecting rod R4 to the length of the connecting rod R5, that is, the larger the ratio of the length of the connecting rod R4 to the length of the connecting rod R5, the larger the angle between the femoral connecting rod R3 and the tibia and fibula connecting rod R6. After many experiments, it was concluded that when the ratio of the length of the connecting rod R4 to the length of the connecting rod R5 is 2, the angle between the femoral connecting rod R3 and the tibia and fibula connecting rod R6 is most ideal. The ratio of the length of the connecting rod R4, the length of the connecting rod R5, and the length of the tibia and fibula connecting rod R6 is 6:3:8, and the length change of each part should be within ±5%. At this time, the connecting rod R4 and the connecting rod R5 control the flexion and extension of the knee joint like two muscles.

[0045] Table 2 Length of connecting rods R4, R5, R6 and angle changes between R3 and R6

[0046]

[0047] The connecting rod R7 and the connecting rod R8 correspond to the tibialis anterior and gastrocnemius of the frog respectively, and are used to control the flexion and extension of the tarsal bones. The simulated tarsal connecting rod R9 simulates the tarsal bones of the frog. It can be seen from the proportional relationship between the simulated femur connecting rod R3, the simulated tibia and fibula connecting rod R6, and the simulated tarsal connecting rod R9 that follows the proportional relationship between the femur, tibia and fibula and tarsal bones of the African clawed frog that the length of the simulated femur connecting rod R3 is 40 mm as an example, the length of the simulated tarsal connecting rod R9 is set to 27 mm, the geometric parameters of the connecting rods R7 and R8 are set, and different connecting rod parameters are substituted into the ADAMS simulation software to obtain a more ideal set of data, as shown in Table 3. Finally, the proportional relationship between the length of the connecting rod R7, the length of the connecting rod R8, and the length of the simulated tarsal connecting rod R9 is 1:1.3:4.3, and the length change of each part should also be within ±5%.

[0048] Table 3 Length of connecting rods R7, R8, R9 and angle changes between R6 and R9

[0049]

[0050] As long as the length and swing angle required by the femoral connecting rod R3 are input, the specific parameters of each connecting rod of the multi-link hind leg mechanism of the present invention can be obtained according to the proportional relationship.

[0051] Substitute the designed connecting rod parameters into the ADAMS simulation software, collect the motion data of the whole structure within one minute, and observe the change of the motion speed of the simulated femoral connecting rod R3, simulated tibia and fibula connecting rod R6, and simulated tarsal connecting rod R9, and extract a cycle from the motion data for analysis. Figure 6 , Figure 7 They are the angular velocity (in deg / sec) and angular acceleration (in deg / sec) of the simulated femoral connecting rod R3. 2 ), the period demarcation point is the time point when the angular acceleration changes from negative to positive, Figure 5 Taking the structure shown as an example, first, the femoral connecting rod R3 takes 0.3 seconds to reach the maximum clockwise angular acceleration, at which time the driving force is the largest, and then after another 2 seconds, the acceleration becomes 0, and after another 7 seconds it returns to the starting point of the cycle. Combined with the frog's swimming process, it can be seen that the 2.3 seconds from the maximum angular acceleration to the acceleration returning to 0 corresponds to the stretching stage of breaststroke, which is particularly rapid. It can be seen from the angular acceleration curve of the femoral connecting rod R3 that the angular acceleration of R3 reaches the maximum in this stage, and then begins to decline, and the acceleration of this stage can provide sufficient propulsion for the frog. In the next stage, the angular acceleration of the femoral connecting rod R3 begins to decline rapidly, the propulsion force weakens, and finally drops from the angular acceleration to 0, and the stretching stage ends. At this time, the angular velocity of the femoral connecting rod R3 reaches the maximum, the angular acceleration begins to turn into a negative value, and the angular velocity begins to decrease until it returns to 0. This stage lasts 4.2 seconds, corresponding to the gliding stage during swimming. When the angular velocity of the femoral connecting rod R3 turns negative, it starts to rotate counterclockwise. This stage lasts for 2.8 seconds, which corresponds to the muscle contraction stage of the frog's swimming process. In the movement process of the femoral connecting rod R3, it can be seen from the data that the fast reset characteristic of the crank connecting rod plays an important role. The fast stroke makes the angular acceleration of the extension stage and the contraction stage change rapidly, which increases the proportion of the gliding stage in the movement cycle and better realizes the simulation of the frog's swimming process.

[0052] The movements of the simulated tibiofibular connecting rod R6 and the simulated tarsal connecting rod R9 are similar. Figure 8 , Fig. 9 They are the angular velocity (in deg / sec), angular acceleration (in deg / sec) of the simulated tibiofibular connecting rod R6. 2 ), Fig.10 , Fig.11 They are the angular velocity (in deg / sec) and angular acceleration (in deg / sec) of the simulated tarsal link R9. 2), observing the angular velocity curves of the two, it can be found that the angular velocity of the simulated tibia and fibula connecting rod R6 and the simulated tarsal connecting rod R9 is negative in the extension stage, indicating that the simulated tibia and fibula connecting rod R6 rotates counterclockwise around the knee joint, and the simulated tarsal connecting rod R9 rotates counterclockwise around the ankle joint, so that the two rods are in an extended state, and both rods reach the maximum value of counterclockwise acceleration in this stage, providing sufficient propulsion for the extension process. In the sliding stage, the angular velocity of the simulated tibia and fibula connecting rod R6 and the simulated tarsal connecting rod R9 gradually decreases to 0 to reduce the resistance in the sliding stage. In the contraction stage, the angular velocity of the simulated tibia and fibula connecting rod R6 and the simulated tarsal connecting rod R9 rises rapidly again, improving the contraction efficiency.

[0053] From the above movement rules, it can be seen that the rationality and feasibility of the bionic frog leg structure designed based on the multi-link mechanism of the present invention, the femoral imitation connecting rod R3, the tibia and fibula imitation connecting rod R6, and the tarsal imitation connecting rod R9 respectively simulate the femur, tibia and fibula and tarsus of the frog leg, the connecting rod R4 and the connecting rod R5 respectively simulate the functions of the semimembranosus and the quadriceps, the connecting rod R7 and the connecting rod R8 respectively simulate the functions of the tibialis anterior and the gastrocnemius, and the connecting rod r6 and the connecting rod r9 both simulate the tendons of the frog leg, which are used to connect the connecting rod mechanism of the simulated muscle and the simulated bone. The present invention is based on a simple multi-link mechanism, which not only simulates the function of the frog skeleton, but also simulates the muscle and tendon functions by using the angle change between the connecting rods, and realizes the bionics in structure and function at the same time, and uses the quick return characteristics of the crank rocker to simulate the rapid contraction process of the frog during swimming, which can more realistically restore the characteristics of the frog swimming process in which the extension stage and the gliding stage account for a large proportion compared with the prior art.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bionic frog leg structure based on a multi-link mechanism, characterized in that: The structure includes two groups of left-right symmetrical multi-link hind leg mechanisms, which include a driving connecting rod R1, a frame connecting rod R2, an imitation femoral connecting rod R3, a connecting rod R4, a connecting rod R5, an imitation tibia and fibula connecting rod R6, a connecting rod R7, a connecting rod R8, an imitation tarsal connecting rod R9, a connecting rod r6, and a connecting rod r9. One end of the driving connecting rod R1 is rotatably connected to the driving end, and the other end of the driving connecting rod R1 is connected to one end of the frame connecting rod R2. The other end of the frame connecting rod R2 is rotatably connected to one end of the imitation femoral connecting rod R3. The other end of the imitation femoral connecting rod R3 simulates a hip joint. One end of the connecting rod R4 is rotatably connected to one end of the connecting rod R5. The other end of the connecting rod R4 is connected to the middle part of the imitation femoral connecting rod R3. The other end of rod R5 is connected to the middle part of the frame connecting rod R2, one end of the simulated tibia-fibula connecting rod R6 is rotationally connected to one end of the simulated femoral connecting rod R3, one end of the simulated tarsal connecting rod R9 is rotationally connected to the other end of the simulated tibia-fibula connecting rod R6, one end of the connecting rod R7 is rotationally connected to one end of the connecting rod R8, the other end of the connecting rod R7 is connected to the middle part of the simulated femoral connecting rod R3, the other end of the connecting rod R8 is connected to the middle part of the simulated tibia-fibula connecting rod R6, one end of the connecting rod r6 is connected to the connection point of the connecting rod R4 and the connecting rod R5, the other end of the connecting rod r6 is connected to the middle part of the simulated tibia-fibula connecting rod R6, one end of the connecting rod r9 is connected to the connection point of the connecting rod R7 and the connecting rod R8, and the other end of the connecting rod r9 is connected to the middle part of the simulated tarsal connecting rod R9.

2. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The driving connecting rod R1 rotates around the connection point with the driving end, driving the simulated femoral connecting rod R3 to rotate around the hip joint. The simulated tibia and fibula connecting rod R6 completes knee extension and knee flexion swing under the tension of connecting rods R4 and R5, and the simulated tarsal connecting rod R9 swings under the tension of connecting rods R7 and R8.

3. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The driving connecting rod R1, the frame connecting rod R2, and the femoral imitation connecting rod R3 form a crank rocker mechanism, and the driving connecting rod R1 rotates 360 degrees around the connection point between it and the driving end.

4. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The driving end includes a motor and two meshing gears, the two gears are respectively connected to the driving connecting rods R1 in the two sets of multi-link rear leg mechanisms, and one of the gears is connected to the output end of the motor.

5. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The length ratio of the simulated femoral connecting rod R3, the simulated tibia and fibula connecting rod R6, and the simulated tarsal connecting rod R9 is 3:3:2, and the length variation of each part is within ±5%.

6. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The sum of the length of the driving connecting rod R1 and the length of the artificial femoral connecting rod R3 is less than the length of the frame connecting rod R2.

7. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The swing angle of the artificial femoral connecting rod R3 is negatively correlated with the length of the driving connecting rod R1 and the length of the frame connecting rod R2. The swing amplitude of the artificial femoral connecting rod R3 can be changed by controlling the length of the driving connecting rod R1 and the frame connecting rod R2.

8. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The angle between the simulated femoral connecting rod R3 and the simulated tibia-fibula connecting rod R6 is positively correlated with the ratio of the length of the connecting rod R4 to the length of the connecting rod R5.

9. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The length of the connecting rod R4, the length of the connecting rod R5, and the length of the simulated tibia-fibula connecting rod R6 are in a ratio of 6:3:8, and the length variation of each part is within ±5%.

10. The bionic frog leg structure based on a multi-link mechanism according to claim 1, characterized in that: The length of the connecting rod R7, the length of the connecting rod R8, and the length of the simulated tarsal connecting rod R9 are in a ratio of 1:1.3:4.3, and the length variation of each part is within ±5%.

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