Research On SMA Actuator Applied To Biomimetic Propel

Shape Memory Alloys (SMA) is a kind of intelligent materials, which has specific property of shape memory effect and has been paid much attention in the field of actuating mechanism of robot's structure. In virtue of its good malleability and corrosion resistance, SMA is very fitly applied to the structure of underwater robot. Researching the technology of SMA using in underwater actuating mechanism, not only helps to exploit new-style aquatic robots, but also can develop the technical level of the application of SMA.In this dissertation, the design and research on SMA actuator which applied to bionic propulsion was finished. The main work and creative achievement are contained in the paper as follows:Firstly, the paper introduces study background and meaning of SMA actuator, describes development process of Shape Memory Alloys, sums up the research and application status of SMA in the fields of robots and underwater robots.Secondly, most of the constitutive relations of SMA, which have been established before, are so complex that they cannot be used to calculate in the design of SMA springs. In this paper, it puts forward to an easier mechanical constitutive relation of SMA spring, which is fit for designing. Its applicability has been proved by the experiment which includes SMA spring compression and uninstall. Contrast the test results of other paper, the conclusion is the same.Thirdly, basic structure of the SMA actuator that applied to bionic propulsion was confirmed through analyzing the driving means and mechanism of the SMA actuator and physical character of fish body, and mechanical properties of the joint was analysis. Driving element of the SMA actuator was designed through the characteristic of bionic propulsion .Fourthly, the method of electrothermal drive and relative merits of all sorts of cooling system was introduced. The factors that influence response speed of SMA spring was been analysis and emulation calculation was finished. Experiment on response speed of SMA actuator was completed. Contrast the test result and simulation result, some conclusion was brought and coefficient of convective heat transfer of the SMA spring was confirmed. Fifthly. Control means of SMA actuator was researched. Aim at the physical characteristic of the SMA actuator was nonlinear, thermal hysteresis, time change and temperature effects prodigious, the fuzzy control was applied to SMA actuator. The control system was designed and fuzzy control rule was given through author's experience, and that has been proved by experiment.Finally, simplified body characteristic and ahead dummy of robot fish was obtained according to the feature of fish motion. The design means of multi-joint SMA actuator was brought by the personal behaviour of SMA actuator. The basic structure size of multi-joint SMA actuator was confirmed through optimization design. Control means of multi-joint SMA actuator that simulates the fish motion was given and experiment was carried out.