You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A Review of Active Mechanical Driving Principles of Spherical Robots 
Chapter Title:  Shape Memory Alloys 
1. Abstract of Cited Paper (BIB001):  We describe circular/spherical robots for crawling and jumping. Locomotion over rough terrain has been achieved mainly by rigid body systems including crawlers and leg mechanisms. This paper presents an alternative method of moving over rough terrain, one that employs deformation. First, we describe the principle of crawling and jumping as performed through deformation of a robot body. Second, in a physical simulation, we investigate the feasibility of the approach. Next, we show experimentally that prototypes of a circular robot and a spherical robot can crawl and jump.

Literature Review:
Others have even proposed deforming the outer shell in such a way that will allow the robot to jump. T. Yamanaka proposes such a robot with "Super-ball-like" properties BIB001 . Superballs have a unique way of bouncing due to their spin and elastic properties. By manipulating the outer shell and placing a rotor in the internal structure, the robot should be able to have controlled hops. Sugiyama proposes and demonstrates locomotion entirely by manipulation of the outer shell BIB002 . The robot is comprised of shape memory alloy (SMA) coils that can be extended/retracted when voltage is applied to them. This allows the robot to flatten like a pancake and spring back to its original form in an instant, causing it to jump. When controlled properly, it can also be used for smooth locomotion as shown in Figure 16 .