1. Introduction to Active Origami Structures

Origami, the ancient art of paper folding, has inspired the design and functionality of engineering structures for decades. The underlying principles of origami are very general, it takes two-dimensional components that are easy to manufacture (sheets, plates, etc.) into three-dimensional structures. More recently, researchers have become interested in the use of active materials that convert various forms of energy into mechanical work to produce the desired folding behavior in origami structures. Such structures are termed active origami structures and are capable of folding and/or unfolding without the application of external mechanical loads but rather by the stimulus provided by a non-mechanical field (thermal, chemical, electromagnetic). This is advantageous for many areas including aerospace systems, underwater robotics, and small scale devices. In this chapter, we introduce the basic concepts and applications of origami structures in general and then focus on the description and classification of active origami structures. We finalize this chapter by reviewing existing design and simulation efforts applicable to origami structures for engineering applications.