A Review of Active Mechanical Driving Principles of Spherical Robots <s> Shape Memory Alloys <s> This paper deals with hopping motion analysis of spherical robot with a typical impact condition like 'superball'. A horizontal velocity of super ball after an impact depends on the angular velocity before the impact where it doesn't slip at the contact point. Our robot model consists of an elastic spherical shell with such an impact condition and of an internal rotary input. Assuming the perfectly elastic impact in a vertical direction, a feedback control strategy for generating the horizontal velocity after an impact by the rotary input during flying phase is derived. Simulation results show that some hopping motion is achieved by the proposed method. In addition, this paper shows the possibility and necessary condition that a climbing motion with impacts against two parallel vertical planes is achieved. <s> BIB001 </s> A Review of Active Mechanical Driving Principles of Spherical Robots <s> Shape Memory Alloys <s> 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. <s> BIB002
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 . 