Experiment Research Of Dynamic Property For Nitonial Memory Alloy And Its Application Of Actuator For Biomimetic Robot Fish

There is great distinct contrast between high efficiency and high agility formed by evolution of more than 1 billion years for the fish and low efficiency and poor agility exists in the underwater propeller with the traditional electro-mechanics actuators. Moreover, the traditional propeller can't provide large power enough to actuate miniature or small biomimetic robot fish for their very poor power-weigh-rate.So new actuator technology with smart materials has being new focus in the field of small biomimetic robot. Investigations from the literature and research experience in our lab show that nitonial memory alloy would have unique latent application in miniature or small scale biomimetic robot because of some merits, such as great power rate, integration between sense and actuators, large strain etc. In this dissertation some main research works are presented as following: 50.8at%-Ni-Ti memory alloy is chosen for the best general property by the comparison with other several present smart materials in actuating properties. Parameter variables required in Tanaka-Liang-Brinson constitutive models are viewed as important characteristics of SMA, which are obtained from quasi-static tests and also viewed as the dynamic evaluation index. The results of dynamic experiment shows the influence resulted by different strain rates.Then Brinson model is revised to express the shear phrase transformation with the equivalent relations between extension stress and strain and shear stress and shear strain. Common spring formula are connected with revised Brinson model to form the SMA spring thermodynamics. The method of design for SMA spring differential actuator system is presented with the assumption that the strain is no more than 1.5%. the thermodynamics of SMA actuator system are alse investigated. Finally, a dynamic model of the small biomimetic robot fish system is developed and some experiments are performed to prove the validity of the SMA actuator system.Firstly, the propulsion mode of thunniform and lunular fin is chosen based on analysis of swimming mode and swimming mechanism of fish. Nitonial memory alloy is chosen as actuators for the best total property with the comparison between several common smart materials. Some important parameters, such as driving moment, swaying angle and frequency, which are dependent on analysis of kinematic...