Open-Loop Control Design of Shape Memory Alloys and Polymers through Tapping Motion

: Shape memory alloys and polymers are a class of smart materials that remember a pre-trained shape or form when exposed to an appropriate temperature. In this work, shape memory alloys consisting of wires, 1-way springs, and 2-way springs are described; an open-loop control of shape memory alloys and polymers is also implemented. Since the amount of electric current that flows through a wire is directly proportional to temperature, control of the electric circuit is used for open-loop temperature control. The designed smart control is applied to rotate a lever mechanism through the conversion of the linear motion of the shape memory alloy (SMA) into the rotational motion of the lever through the tapping of a piezoelectric transducer to deliver the open-loop control. When the piezo transducer is deformed by mechanical stress via tapping, striking, or any other mechanical stimulus, it produces an electrical signal, which when sent to the microelectronic circuit activates the SMA. The implemented system can be applied in robotic systems and autonomous applications.