The Design And Motion Analysis Of The Crawling Mechanism About Bionic Machine Alligator

The crocodile is a kind of very ancient amphibians. It has very strong adaptability to environment, and can move freely on land, swamp and in water. Because of the cleaning difficulties to petroleum pipelines and other industrial pipes, and the current research trends in amphibious robots all over the world, this paper devises a bionic machine alligator based on the biological prototype of crocodile, and it has a simple structure, reliable performance, a strong adaptability to environment, and the ability of flexible movement. So that it can provide basic application platform for pipeline cleaning, environmental sampling and underwater detection.First of all, this paper introduces the topic source, the purpose and significance of the research, points out the necessity and importance about the research of the bionic machine alligator, and analyses the current development status and the existence deficiency about the bionic robots at home and abroad. And then it analyzes the body structure features and movement characteristics of the crocodile, and proposes the general design scheme of the machine alligator. After that, the paper ascertains the main structure size of the machine alligator, the type and structure parameters of the drive motors, reducers, and other transmission parts. And it gives three-dimensional structure diagram of the whole alligator and some key mechanisms, and analyses their principle.In order to enhance the movement flexibility of bionic machine alligator, this paper adopts four-foot joint type mobile mechanism on the basis of bionic. Each joint movement is driven by a drive motor, and all the drive motors are placed inside of the leg and the machine body, which makes the compact and beautiful structure. In the movement, all the drive motor control and cooperate with each other. The drive power, which is transmitted by the transmission mechanism of straight bevel gear, changes the angle of each joint so that changes the movement stance of the machine alligator.In order to ensure the movement performance of the machine alligator, this paper analyses the kinematics of the swing-phase leg, which adopts D-H method to establish the coordinate system of the joints. So it establishes the mathematical model of the leg movement, and then gets the relationship between the rotation angle of the joints and the position of swing-leg foot, the velocity and acceleration of the joints.The stability movement of the machine is the key research content of this paper. In order to obtain the stable movement, this article compares the common robot movement gaits. Then it determines the gait form of bionic machine alligator, and plans the straight walking and turning gait of the machine alligator. According to the foot end position by kinematics analysis, it adopts a polynomial fitting method and simulates in Matlab to get the movement track of the machine alligator foot end.Finally, this paper summarizes the main work and the research content in the process of study, and makes the prospect of the future research direction.