Development of Test Rig for Position Control of Shape Memory Alloy Spring using PID Algorithm

Abstract

x Abstract Shape memory alloys are special materials which memorize their original form. These can be brought back to their programmed state after deformation by virtue of heat or magnetic stimuli. Nitinol or Nickle Titanium Alloy (NiTi) is the best known SMA. A great amount of research has been done in order to understand their chemical composition and physical properties. These materials have applications ranging from aircrafts to miniature robots and are used in medical field due to their unique behavior. SMAs offer a unique perspective in the micro-positioning industry where they can replace bulky machinery like motors to move small objects around using only heat supplied through electric current. As of now, the research is focused on controlling SMA position using complex algorithms designed in labs and the industrial application is very limited. This thesis describes the use of simple PID and Advanced PID algorithm, that can be implemented in industry, to control the position of Nitinol springs. The research carried out indicates that, although difficult, the PID algorithm can produce good results. The PID controller reached an accuracy of 0.46mm with a minimum overshoot of 1.8344mm while the advanced PID gave a minimum error of 0.211mm and the minimum overshoot at 2.38mm.