Bionic crab walking mechanism and its kinematic characteristics analysis

Abstract: The research of bionic walking mechanism is of great significance for the development of walking mechanism on complex terrain. In order to design a bionic walking mechanism with superior performance and simple structure, by analyzing the walking gait of Eriocheir sinensis Milne-Edwards, the design scheme of the crab walking mechanism was proposed. Due to 2 feet at the end of the crab less involved in walking, in order to simplify the structure, the walking mechanism was designed to have 6 feet, and leg movement was achieved by the six-link mechanism. The whole model of the walking mechanism was established by the three-dimensional (3D) modeling software CATIA, and the kinematics analysis was finished in ADAMS. The results showed that the walking mechanism could complete the expected action. Based on the design, bionic walking mechanism prototype was produced, and walking test of bionic walking mechanism on the smooth hard ground was carried out for the dynamic video information to analyze its working gait. Then the kinematic parameters of the collected digital images were extracted in the SimiMotion3D motion analysis system, and the supporting phase and mobile phase of the legs of the walking mechanism were acquired. The results showed that taking no account of the fourth step of the crab, both of them showed a high degree of similarity, and the bionic walking mechanism could imitate the natural gait of the crab. Through the comparison test of the wheeled model car and bionic walking mechanism on the non conventional ground, the movement performance and trafficability characteristics of the walking mechanism were analyzed on the different ground. Choosing the horizontal swing, the longitudinal turbulence as the characteristic parameters, the displacement fluctuation range and absolute maximum value of acceleration of the 2 directions were used as the characteristic parameters of the bionic walking mechanism. The results show that the bionic walking mechanism had a strong adaptability to different ground, and had good performance on the ground and loose dry sand ground. On the smooth hard ground, the fluctuation of the bionic walking mechanism was obviously larger than the wheeled model car and was not suitable for walking on the smooth hard ground. The displacement fluctuation range was 5.5 and 2.2 times as large as wheeled model car in longitudinal and horizontal axis direction, and compared with the bionic walking mechanism, the absolute maximum value of acceleration of the wheeled model car was reduced by 40% and 45% in the longitudinal and horizontal axis direction respectively. On the rough ground involved in agricultural production activities, the bionic walking mechanism was better than the wheeled model car. The kinematic parameters of the bionic walking mechanism were very close to the wheeled model car along the horizontal axis on the small rough hard ground. Compared with the wheeled model car, the displacement fluctuation range and the absolute maximum value of acceleration of the bionic walking mechanism decreased by 5% and 7% respectively. Along the direction of the longitudinal axis, the difference was bigger, the displacement fluctuation range of the bionic walking mechanism was 75% lower than the wheeled model car, and the absolute maximum value of the acceleration was 26% lower than the wheeled model car. The walking mechanism could also be used as a test platform to provide basic research equipment for improving the walking mechanism trafficability characteristics on the different terrain through the optimization of the leg bar size and the foot end touchdown way..