A Stiffness Adjustment Mechanism Based on Negative Work for High-efficient Propulsion of Robotic Fish  

作　　者：Dong Xu Haining Zeng Xiang Peng Ziqing Zhao Jingmeng Liu 

机构地区：[1]School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China

出　　处：《Journal of Bionic Engineering》2018年第2期270-282,共13页仿生工程学报（英文版）

基　　金：Acknowledgment This work is supported by National Natural Science Foundation of China （under Grant Nos.： 61203353 and 61573038）.

摘　　要：The applications of robotic fish require high propulsive efficiency mechanism to prolong the mission time. Though many methods were applied, robotic fish still suffers from low efficiency. To improve the efficiency of robotic fish, this paper proposes a variable stiffness mechanism which is based on the negative work. The live fish adjusts its body stiffness to save energy when the muscles do negative work. Inspired by the live fish, a control mechanism based on negative work is proposed to change the stiffness of the robotic fish for higher efficiency. Changing the stiffness of the robotic fish is to change the joint-stiffness. A fuzzy controller is introduced to mimic the variable stiffness mechanism of the fish and depicts the relationship between the stiffness and the negative work. To evaluate the performance of this controller, a two-joint robotic fish model is established based on its kinematic model and hydrodynamic model. The evaluation results show that the robotic fish reduces the energy consumption and improves the propulsion efficiency when introducing the variable stiffness mechanism. Different environments with the control mechanism impact differently on propulsive efficiency. This mechanism may provide a high efficient propulsion control method for the robotic fish.The applications of robotic fish require high propulsive efficiency mechanism to prolong the mission time. Though many methods were applied, robotic fish still suffers from low efficiency. To improve the efficiency of robotic fish, this paper proposes a variable stiffness mechanism which is based on the negative work. The live fish adjusts its body stiffness to save energy when the muscles do negative work. Inspired by the live fish, a control mechanism based on negative work is proposed to change the stiffness of the robotic fish for higher efficiency. Changing the stiffness of the robotic fish is to change the joint-stiffness. A fuzzy controller is introduced to mimic the variable stiffness mechanism of the fish and depicts the relationship between the stiffness and the negative work. To evaluate the performance of this controller, a two-joint robotic fish model is established based on its kinematic model and hydrodynamic model. The evaluation results show that the robotic fish reduces the energy consumption and improves the propulsion efficiency when introducing the variable stiffness mechanism. Different environments with the control mechanism impact differently on propulsive efficiency. This mechanism may provide a high efficient propulsion control method for the robotic fish.

关 键 词：robotic fish propulsion efficiency negative work stiffness adjustment 

分 类 号：TV131.2[水利工程—水力学及河流动力学] S981.1[农业科学—捕捞与储运]